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1

Total Sediment Load Measurement Using Point-Source Suspended-Sediment Data.  

National Technical Information Service (NTIS)

A procedure for measuring total sediment discharge using point-source suspended-sediment data was developed. The proposed procedure, TSL (Total Sediment Load), was tested with field data from the Niobrara River at Cody, NE; Fivemile Creek at Shoshoni, WY;...

J. J. Ingram

1988-01-01

2

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

USGS Publications Warehouse

A natural chute in the Niobrara River near Cody, Nebr., constricts the flow of the river except at high stages to a narrow channel in which the turbulence is sufficient to suspend nearly the total sediment discharge. Because much of the flow originates in the sandhills area of Nebraska, the water discharge and sediment discharge are relatively uniform. Sediment discharges based on depth-integrated samples at a contracted section in the chute and on streamflow records at a recording gage about 1,900 feet upstream are available for the period from April 1948 to September 1953 but are not given directly as continuous records in this report. Sediment measurements have been made periodically near the gage and at other nearby relatively unconfined sections of the stream for comparison with measurements at the contracted section. Sediment discharge at these relatively unconfined sections was computed from formulas for comparison with measured sediment discharges at the contracted section. A form of the Du Boys formula gave computed tonnages of sediment that were unsatisfactory. Sediment discharges as computed from the Schoklitsch formula agreed well with measured sediment discharges that were low, but they were much too low at measured sediment discharges that were higher. The Straub formula gave computed discharges, presumably of bed material, that were several times larger than measured discharges of sediment coarser than 0.125 millimeter. All three of these formulas gave computed sediment discharges that increased with water discharges much less rapidly than the measured discharges of sediment coarser than 0.125 millimeter. The Einstein procedure when applied to a reach that included 10 defined cross sections gave much better agreement between computed sediment discharge and measured sediment discharge than did anyone of the three other formulas that were used. This procedure does not compute the discharge of sediment that is too small to be found in the stream bed in appreciable quantities. Hence, total sediment discharges were obtained by adding computed discharges of sediment larger than 0.125 millimeter to measured discharges of sediment smaller than 0.125 millimeter. The size distributions of the computed sediment discharge compared poorly with the size distributions of sediment discharge at the contracted section. Ten sediment discharges computed from the Einstein procedure as applied to a single section averaged several times the measured sediment discharge for the contracted section and gave size distributions that were unsatisfactory. The Einstein procedure was modified to compute total sediment discharge at an alluvial section from readily measurable field data. The modified procedure uses measurements of bed-material particle sizes, suspended-sediment concentrations and particle sizes from depth-integrated samples, streamflow, and water temperatures. Computations of total sediment discharge were made by using this modified procedure, some for the section at the gaging station and some for each of two other relatively unconfined sections. The size distributions of the computed and the measured sediment discharges agreed reasonably well. Major advantages of this modified procedure include applicability to a single section rather than to a reach of channel, use of measured velocity instead of water-surface slope, use of depth-integrated samples, and apparently fair accuracy for computing both total sediment discharge and approximate size distribution of the sediment. Because of these advantages this modified procedure is being further studied to increase its accuracy, to simplify the required computations, and to define its limitations. In the development of the modified procedure, some relationships concerning theories of sediment transport were reviewed and checked against field data. Vertical distributions of suspended sediment at relatively unconfined sections did not agree well with theoretical dist

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

1955-01-01

3

TOTAL AND BIOAVAILABLE METALS AT MARINA SEDIMENTS IN LAKE TEXOMA  

EPA Science Inventory

Total and bioavailable metals in sediments were measured at marina areas in Lake Texoma during the fall of 2001. The metals most often found in the highest concentrations in sediments were Ca (56811 mg/kg) and Al (31095 mg/kg), followed by Fe (19393 mg/kg), K (6089 mg/kg), and Mg...

4

Total Sediment Thickness of the Worlds Oceans and Marginal Seas  

NSDL National Science Digital Library

This annotated global map show the total sediment thickness of the world's ocean basins. It may be useful in a discussion about how sedimentary transport processes and tectonics interact to create areas of high sediment thickness, particularly in the Gulf of Mexico and the Indian Ocean.

Center, National G.; Noaa

5

Sediment and Total Phosphorous Contributors in Rock River Watershed  

EPA Science Inventory

Total phosphorous (TP) and total suspended sediment (TSS) pollution is a problem in the US Midwest and is of particular concern in the Great Lakes region where many water bodies are already eutrophic. Increases in monoculture corn planting to feed ethanol based biofuel productio...

6

Sediment yield and spurious correlation-toward a better portrayal of the annual suspendend-sediment load of rivers  

USGS Publications Warehouse

Bivariate relations between annual sediment yield (tons per year per unit drainage area) and drainage-basin area are spurious because drainage-basin area is common to both axes. Two alternative methods for portraying the annual suspended-sediment load of a river are suggested. One method consists of plotting suspended-sediment load (tons per year) against distance downstream. Such plots indicate that annual suspended-sediment load does not necessarily have a linear relationship with distance. The second method consists of plotting annual suspended-sediment load against drainage-basin area. Both methods more accurately portray fundamental relations between annual sediment load and drainage-basin characteristics than does the yield-area relation because spurious correlation is avoided. Plots were made of annual suspended-sediment load versus time for several stations along each of eight rivers for the 10-15 years of available data. The plots are in-phase with respect to relative magnitude of annual sediment loads. ?? 1988.

Waythomas, C. F.; Williams, G. P.

1988-01-01

7

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

Microsoft Academic Search

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

H. N. Williams

1988-01-01

8

LONG-TERM DISTRIBUTIONS OF ANNUAL SEDIMENT YIELDS FROM SMALL WATERSHEDS  

EPA Science Inventory

Annual sediment yields from small (< 20 sq km) mountain watersheds in the northwestern United States are approximately log normally distributed over time. Stochastic sediment yield models, based on brief, infrequent transport events, reproduce the log normal property. Observed cu...

9

Soil respiration at mean annual temperature predicts annual total across vegetation types and biomes.  

PubMed

Soil respiration (SR) constitutes the largest flux of CO(2) from terrestrial ecosystems to the atmosphere. However, there still exist considerable uncertainties as to its actual magnitude, as well as its spatial and interannual variability. Based on a reanalysis and synthesis of 80 site-years for 57 forests, plantations, savannas, shrublands and grasslands from boreal to tropical climates we present evidence that total annual SR is closely related to SR at mean annual soil temperature (SR(MAT)), irrespective of the type of ecosystem and biome. This is theoretically expected for non water-limited ecosystems within most of the globally occurring range of annual temperature variability and sensitivity (Q(10)). We further show that for seasonally dry sites where annual precipitation (P) is lower than potential evapotranspiration (PET), annual SR can be predicted from wet season SR(MAT) corrected for a factor related to P/PET. Our finding indicates that it can be sufficient to measure SR(MAT) for obtaining a well constrained estimate of its annual total. This should substantially increase our capacity for assessing the spatial distribution of soil CO(2) emissions across ecosystems, landscapes and regions, and thereby contribute to improving the spatial resolution of a major component of the global carbon cycle. PMID:23293656

Bahn, M; Reichstein, M; Davidson, E A; Grünzweig, J; Jung, M; Carbone, M S; Epron, D; Misson, L; Nouvellon, Y; Roupsard, O; Savage, K; Trumbore, S E; Gimeno, C; Yuste, J Curiel; Tang, J; Vargas, R; Janssens, I A

2010-07-01

10

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

EPA Science Inventory

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

11

SEDIMENT TOTAL ORGANIC CARBON: IS IT TIME TO PULL THE PLUG ON THIS INDICATOR?  

EPA Science Inventory

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

12

16 CFR 801.11 - Annual net sales and total assets.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 2012-01-01 false Annual net sales and total assets. 801.11 Section...OF 1976 COVERAGE RULES § 801.11 Annual net sales and total assets. (a) The annual net sales and total assets of a person shall...

2012-01-01

13

16 CFR 801.11 - Annual net sales and total assets.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Annual net sales and total assets. 801.11 Section...OF 1976 COVERAGE RULES § 801.11 Annual net sales and total assets. (a) The annual net sales and total assets of a person shall...

2013-01-01

14

16 CFR 801.11 - Annual net sales and total assets.  

...2014-01-01 2014-01-01 false Annual net sales and total assets. 801.11 Section...OF 1976 COVERAGE RULES § 801.11 Annual net sales and total assets. (a) The annual net sales and total assets of a person shall...

2014-01-01

15

16 CFR 801.11 - Annual net sales and total assets.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Annual net sales and total assets. 801.11 Section...OF 1976 COVERAGE RULES § 801.11 Annual net sales and total assets. (a) The annual net sales and total assets of a person shall...

2011-01-01

16

16 CFR 801.11 - Annual net sales and total assets.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Annual net sales and total assets. 801.11 Section...OF 1976 COVERAGE RULES § 801.11 Annual net sales and total assets. (a) The annual net sales and total assets of a person shall...

2010-01-01

17

An Energetics Total Load Sediment Transport Model For a Plane Sloping Beach  

Microsoft Academic Search

Bagnold's energetics-based total load sediment transport model for streams is used as a basis for the development of a total load model of time varying sediment transport over a plane sloping bed. In both the bedload and suspended load, the transport rate vectors are found to be composed of a velocity-induced component directed parallel to the instantaneous velocity vector and

James A. Bailard

1981-01-01

18

FLUSHING SEDIMENT THROUGH RESERVOIRS  

Microsoft Academic Search

About 1% of the total storage capacity in the world's reservoirs is lost annually due to sedimentation. Sediments can also block intakes in reservoirs and damage tunnels or turbines. One of the most effective techniques to remove these sediments is flushing, whereby water level is lowered sufficiently to re-erode deposits and flush them through the intakes. Outflow sediment discharge may

N. TALEBBEYDOKHTI; A. NAGHSHINEH

19

Variability of suspended-sediment concentration at tidal to annual time scales in San Francisco Bay, USA  

USGS Publications Warehouse

Singular spectrum analysis for time series with missing data (SSAM) was used to reconstruct components of a 6-yr time series of suspended-sediment concentration (SSC) from San Francisco Bay. Data were collected every 15 min and the time series contained missing values that primarily were due to sensor fouling. SSAM was applied in a sequential manner to calculate reconstructed components with time scales of variability that ranged from tidal to annual. Physical processes that controlled SSC and their contribution to the total variance of SSC were (1) diurnal, semidiurnal, and other higher frequency tidal constituents (24%), (2) semimonthly tidal cycles (21%), (3) monthly tidal cycles (19%), (4) semiannual tidal cycles (12%), and (5) annual pulses of sediment caused by freshwater inflow, deposition, and subsequent wind-wave resuspension (13%). Of the total variance 89% was explained and subtidal variability (65%) was greater than tidal variability (24%). Processes at subtidal time scales accounted for more variance of SSC than processes at tidal time scales because sediment accumulated in the water column and the supply of easily erodible bed sediment increased during periods of increased subtidal energy. This large range of time scales that each contained significant variability of SSC and associated contaminants can confound design of sampling programs and interpretation of resulting data.

Schoellhamer, D. H.

2002-01-01

20

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

USGS Publications Warehouse

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.

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

2013-01-01

21

Sediment concentration prediction and statistical evaluation for annual load estimation  

NASA Astrophysics Data System (ADS)

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.

Wang, You-Gan; Tian, Ting

2013-03-01

22

Annual replenishment of bed material by sediment transport in the Wind River near Riverton, Wyoming  

USGS Publications Warehouse

The U.S. Geological Survey, in cooperation with the Wyoming Department of Transportation, conducted a study during 1985-87 to determine the annual replenishment of sand and gravel along a point bar in the Wind River near Riverton, Wyoming. Hydraulic- geometry relations determined from streamflow measurements; streamflow characteristics determined from 45 years of record at the study site; and analyses of suspended-sediment, bedload, and bed- material samples were used to describe river transport characteristics and to estimate the annual replenishment of sand and gravel. The Wind River is a perennial, snowmelt-fed stream. Average daily discharge at the study site is about 734 cubic feet per second, and bankfull discharge (recurrence interval about 1.5 years) is about 5,000 cubic feet per second. At bankfull discharge, the river is about 136 feet wide and has an average depth of about 5.5 feet and average velocity of about 6.7 feet per second. Streams slope is about 0.0010 foot per foot. Bed material sampled on the point bar before the 1986 high flows ranged from sand to cobbles, with a median diameter of about 22 millimeters. Data for sediment samples collected during water year 1986 were used to develop regression equations between suspended-sediment load and water discharge and between bedload and water discharge. Average annual suspended-sediment load was computed to be about 561,000 tons per year using the regression equation in combination with flow-duration data. The regression equation for estimating bedload was not used; instead, average annual bedload was computed as 1.5 percent of average annual suspended load about 8,410 tons per year. This amount of bedload material is estimated to be in temporary storage along a reach containing seven riffles--a length of approximately 1 river mile. On the basis of bedload material sampled during the 1986 high flows, about 75 percent (by weight) is sand (2 millimeters in diameter or finer); median particle size is about 0.5 milli- meter. About 20 percent (by weight) is medium gravel to small cobbles--12.7 millimeters (0.5 inch) or coarser. The bedload moves slowly (about 0.03 percent of the water speed) and briefly (about 10 percent of the time). The average travel distance of a median-sized particle is about 1 river mile per year. The study results indicate that the average replenishment rate of bedload material coarser than 12.7 millimeters is about 1,500 to 2,000 tons (less than 1,500 cubic yards) per year. Finer material (0.075 to 6.4 millimeters in diameter) is replen- ishment at about 4,500 to 5,000 cubic yards per year. The total volume of potentially usable material would average about 6,000 cubic yards per year.

Smalley, M. L.; Emmett, W. W.; Wacker, A. M.

1994-01-01

23

Comparability of Suspended-Sediment Concentration and Total Suspended Solids Data.  

National Technical Information Service (NTIS)

Two laboratory analytical methods-suspended-sediment concentration (SSC) and total suspended solids (TSS)-are predominantly used to quantify concentrations of suspended solid-phase material in surface waters of the United States. The analytical methods di...

J. R. Gray G. D. Glysson L. M. Turcios G. E. Schwarz

2000-01-01

24

Total Maximum Daily Load of Sediment in the Seneca Creek Watershed, Montgomery County, Maryland.  

National Technical Information Service (NTIS)

This document, upon approval by the U.S. Environmental Protection Agency (EPA), establishes a Total Maximum Daily Load (TMDL) for sediment in the Seneca Creek watershed (basin number 02140208) (2010 Integrated Report of Surface Water Quality in Maryland A...

2011-01-01

25

Quantitative PCR Enumeration of Total/Toxic Planktothrix rubescens and Total Cyanobacteria in Preserved DNA Isolated from Lake Sediments  

PubMed Central

The variability of spatial distribution and the determinism of cyanobacterial blooms, as well as their impact at the lake scale, are still not understood, partly due to the lack of long-term climatic and environmental monitoring data. The paucity of these data can be alleviated by the use of proxy data from high-resolution sampling of sediments. Coupling paleolimnological and molecular tools and using biomarkers such as preserved DNA are promising approaches, although they have not been performed often enough so far. In our study, a quantitative PCR (qPCR) technique was applied to enumerate total cyanobacterial and total and toxic Planktothrix communities in preserved DNA derived from sediments of three lakes located in the French Alps (Lake Geneva, Lake Bourget, and Lake Annecy), containing a wide range of cyanobacterial species. Preserved DNA from lake sediments was analyzed to assess its quality, quantity, and integrity, with further application for qPCR. We applied the qPCR assay to enumerate the total cyanobacterial community, and multiplex qPCR assays were applied to quantify total and microcystin-producing Planktothrix populations in a single reaction tube. These methods were optimized, calibrated, and applied to sediment samples, and the specificity and reproducibility of qPCR enumeration were tested. Accurate estimation of potential inhibition within sediment samples was performed to assess the sensitivity of such enumeration by qPCR. Some precautions needed for interpreting qPCR results in the context of paleolimnological approaches are discussed. We concluded that the qPCR assay can be used successfully for the analysis of lake sediments when DNA is well preserved in order to assess the presence and dominance of cyanobacterial and Planktothrix communities.

Savichtcheva, Olga; Debroas, Didier; Kurmayer, Rainer; Villar, Clement; Jenny, Jean Philippe; Arnaud, Fabien; Perga, Marie Elodie; Domaizon, Isabelle

2011-01-01

26

Distribution of total mercury and methyl mercury in water, sediment, and fish from South Florida estuaries  

USGS Publications Warehouse

Concentrations of total mercury and methyl mercury were determined in sediment and fish collected from estuarine waters of Florida to understand their distribution and partitioning. Total mercury concentrations in sediments ranged from 1 to 219 ng/g dry wt. Methyl mercury accounted for, on average, 0.77% of total mercury in sediment. Methyl mercury concentrations were not correlated with total mercury or organic carbon content in sediments. The concentrations of total mercury in fish muscle were between 0.03 and 2.22 (mean: 0.31) ??g/g, wet wt, with methyl mercury contributing 83% of total mercury. Methyl mercury concentrations in fish muscle were directly proportional to total mercury concentrations. The relationship of total and methyl mercury concentrations in fish to those of sediments from corresponding locations was fish-species dependent, in addition to several abiotic factors. Among fish species analyzed, hardhead catfish, gafftopsail catfish, and sand seatrout contained the highest concentrations of mercury. Filtered water samples from canals and creeks that discharge into the Florida Bay showed mercury concentrations of 3-7.4 ng/L, with methyl mercury accounting for <0.03-52% of the total mercury. Consumption of fish containing 0.31 ??g mercury/g wet wt, the mean concentration found in this study, at rates greater than 70 g/day, was estimated to be hazardous to human health.

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

1998-01-01

27

Estimated 1996--97 and long-term average annual loads for suspended sediment and selected trace metals in streamflow of the upper Clark Fork Basin from Warm Springs to Missoula, Montana  

SciTech Connect

The report presents annual load estimates for suspended sediment and selected trace metals in streamflow at 12 sites in the upper Clark Fork basin from Warm Springs to Missoula during water years 1996-97. Annual constituent loads were calculated using constituent concentrations measured in periodically collected samples, data from daily suspended-sediment and streamflow records, and regression relations. The resulting loads are summarized to provide a spatial characterization of sediment and metals inputs during 1996-97. Methods used to calculate loads are presented for suspended sediment, total-recoverable copper, lead, and zinc, and dissolved copper.

Lambing, J.H.

1998-08-01

28

Annual sediment flux estimates in a tidal strait using surrogate measurements  

USGS Publications Warehouse

Annual suspended-sediment flux estimates through Carquinez Strait (the seaward boundary of Suisun Bay, California) are provided based on surrogate measurements for advective, dispersive, and Stokes drift flux. The surrogates are landward watershed discharge, suspended-sediment concentration at one location in the Strait, and the longitudinal salinity gradient. The first two surrogates substitute for tidally averaged discharge and velocity-weighted suspended-sediment concentration in the Strait, thereby providing advective flux estimates, while Stokes drift is estimated with suspended-sediment concentration alone. Dispersive flux is estimated using the product of longitudinal salinity gradient and the root-mean-square value of velocity-weighted suspended-sediment concentration as an added surrogate variable. Cross-sectional measurements validated the use of surrogates during the monitoring period. During high freshwater flow advective and dispersive flux were in the seaward direction, while landward dispersive flux dominated and advective flux approached zero during low freshwater flow. Stokes drift flux was consistently in the landward direction. Wetter than average years led to net export from Suisun Bay, while dry years led to net sediment import. Relatively low watershed sediment fluxes to Suisun Bay contribute to net export during the wet season, while gravitational circulation in Carquinez Strait and higher suspended-sediment concentrations in San Pablo Bay (seaward end of Carquinez Strait) are responsible for the net import of sediment during the dry season. Annual predictions of suspended-sediment fluxes, using these methods, will allow for a sediment budget for Suisun Bay, which has implications for marsh restoration and nutrient/contaminant transport. These methods also provide a general framework for estimating sediment fluxes in estuarine environments, where temporal and spatial variability of transport are large. ?? 2006 Elsevier Ltd. All rights reserved.

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

2006-01-01

29

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...

30

Total mercury and methylmercury in sediments near offshore drilling sites in the Gulf of Mexico  

NASA Astrophysics Data System (ADS)

Concentrations of total Hg in sediments near six drilling sites in the Gulf of Mexico were elevated well above average background values of 40-80 ng/g. The excess Hg was associated with barite from discharged drilling mud. In contrast with total Hg, concentrations of methylmercury (MeHg) in these sediments did not vary significantly at nearfield (<100 m) versus farfield (>3 km) distances from the drilling sites. Observed variability in concentrations of MeHg were related to local differences in redox state in the top 10 cm of sediment. Low to non-detectable concentrations of MeHg were found in nearfield sediments that were anoxic, highly reducing and contained abundant H2S. At most drilling sites, nearfield samples with high concentrations of total Hg (>200 ng/g) had similar or lower amounts of MeHg than found at background (farfield) stations. Higher values of MeHg were found in a few nearfield sediments at one site where concentrations of TOC were higher and where sediments were anoxic and moderately reducing. Overall, results from this study support the conclusion that elevated concentrations of MeHg in sediments around drilling sites are not a common phenomenon in the Gulf of Mexico.

Trefry, John H.; Trocine, Robert P.; McElvaine, Michelle L.; Rember, Robert D.; Hawkins, Lucas T.

2007-10-01

31

Effective Discharge and Annual Sediment Yield on Brazos River  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

32

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

USGS Publications Warehouse

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.

Horowitz, A. J.

2008-01-01

33

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...

34

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

USGS Publications Warehouse

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.

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

2014-01-01

35

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

USGS Publications Warehouse

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.

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

2004-01-01

36

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

USGS Publications Warehouse

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.

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

2000-01-01

37

Temporal and vertical distribution of total ammonia nitrogen and un-ionized ammonia nitrogen in sediment pore water from the upper Mississippi River  

USGS Publications Warehouse

We examined the temporal and vertical distribution of total ammonia nitrogen (TAN) and un-ionized ammonia nitrogen (NH3-N) in sediment pore water and compared the temporal patterns of TAN and NH3-N concentrations in overlying surface water with those in pore water. Pore water was obtained by core extraction and subsequent centrifugation. We measured TAN concentrations and calculated NH3-N concentrations from February through October 1993 at four sites in Pool 8, upper Mississippi River, at depths of 0 to 4, 4 to 8, and 8 to 12 cm below the sediment-water interface. Total ammonia nitrogen and NH3-N concentrations were significantly different among sampling dates (p = 0.0001) and sediment depths (p = 0.0001). Concentrations of TAN and NH3-N in surface water were significantly less than those in pore water from all sediment depths (p < 0.05). Concentrations in pore water ranged from 0.07 to 4.0 mg TAN/L and less than 1 to 20 I?g NH3-N/L in winter, and from 0.07 to 10.0 mg TAN/L and 1 to 175 I?g NH3-N/L in summer; greatest concentrations were usually found in sediments 8 to 12 cm deep. Annual mean TAN concentrations were positively correlated with silt and volatile solids content and were negatively correlated with sand content. Because of the high variability of TAN and NH3-N concentrations in pore water, sediment toxicity studies should take into account the season and the depth at which sediments are obtained. The annual mean NH3-N concentration in pore water at one site (55 I?g/L) exceeded the concentration (30 I?g/L) demonstrated to inhibit growth of fingernail clams in laboratory studies. However, these concentrations apparently were not lethal, as evidenced by the presence of fingernail clams at this site.

Frazier, Bradley E.; Naimo, Teresa J.; Sandheinrich, Mark B.

1996-01-01

38

Dependence of Total Longshore Sediment Transport Rates on Incident Wave Parameters and Breaker Type.  

National Technical Information Service (NTIS)

Experiments were conducted in the Large-scale Sediment Transport Facility (LSTF) at the U.S. Army Engineer Research and Development Center to investigate the importance of wave height, period, and breaker type (spilling and plunging breakers) on total rat...

B. A. Ebersole, E. R. Smith, J. Zhang, P. Wang

2009-01-01

39

Total Maximum Daily Loads of Phosphorus and Sediments for Clopper Lake, Montgomery County, MD.  

National Technical Information Service (NTIS)

On the basis of water quality problems associated with nutrients and sediments, Clopper Lake in the Seneca Creek watershed (02-14-02-08) was identified on Marylands 1998 list of WQLSs as being impaired. This document establishes Total Maximum Daily Loads ...

2002-01-01

40

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

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

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

2014-02-15

41

Identifying the annual signal in laminated clastic sediments from a Late Pleistocene lake succession  

NASA Astrophysics Data System (ADS)

A thick (>250m) succession of laminated lacustrine sediments at the Baumkirchen site in the Inn Valley (Austria) indicates the presence of a lake or series of lake phases existing during Marine Isotope Stage 3. The laminations are highly complex, entirely clastic, and vary considerably in thickness and internal structure. Despite high sedimentation rates of 5-6 cm per year indicated by radiocarbon and pollen data, there is no systematic macroscopic annual pattern in the laminations which could be used to develop a high-resolution (varve) chronology. Microscopic investigations of thin sections revealed sub-mm to cm-scale silt layers punctuated by very thin (0.25-2 mm) clay-rich layers spaced semi-regularly between 2 and 8 cm where present. The spacing and small grain size of these thin layers suggests a possible annual process responsible for their formation: rain-out of the fine suspended sediment from the water column during winter, when fluvial discharge into the lake was negligible and its surface was frozen. These potentially annual layers are not reliably identifiable macroscopically, however, analysis of X-ray fluorescence core scan data revealed the layers to be enriched in several heavy metals: most strongly in Zn but also in Pb, Cu and Ni. Possible carrier minerals of these heavy metals are currently being investigated. The radiocarbon chronology (in the short upper section where it is available) and heavy metal peak counting agree within error suggesting the heavy metal enriched clay-rich layers are mostly annual. Available X-ray fluorescence data for 150 m of the section suggest no significant long-term changes in annual layer spacing (i.e. sedimentation rate) from the 5-6 cm average indicated by the radiocarbon data, although there is a high degree of small-scale variation. Preliminary optically stimulated luminescence dates point to the presence of several hiatuses in this succession suggesting a fragmented record containing several lake periods of high sedimentation rates, rather than a continuous record. Local, annually resolved chronologies will open the door to perform high-resolution investigations into rates of change of climate proxies (pollen and biomarkers) across stadial-to-interstadial transitions.

Barrett, Samuel; Starnberger, Reinhard; Spötl, Christoph; Brauer, Achim; Dulski, Peter

2014-05-01

42

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

USGS Publications Warehouse

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)

Thompson, K. R.

1985-01-01

43

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

USGS Publications Warehouse

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)

Thompson, K. R.

1984-01-01

44

Total mercury in fish, sediments and soil from the River Pra Basin, southwestern Ghana.  

PubMed

Total Mercury (Hg) concentrations were determined in soil, river sediments and six (6) species of fish from the River Pra Basin in southwestern Ghana by Cold Vapour Atomic Absorption Spectrometry. Mercury concentration (microg g(-1)) ranged from 0.042 to 0.145 for soil: from 0.390 to 0.707 for sediments and from <0.001 to 0.370 for fish. All the fish samples had Hg concentration below the World Health Organisation (WHO) permissible limit of 0.5 microg g(-1) whereas all the sediment samples had levels higher than the US-EPA value of 0.2 microg g(-1). The results obtained from this study showed that fish from River Pra Basin are unlikely to constitute any significant mercury exposure to the public through consumption. No apparent trend of increasing mercury concentration along the main river as it flows downward toward the sea was observed. PMID:20585751

Oppong, S O B; Voegborlo, R B; Agorku, S E; Adimado, A A

2010-09-01

45

Computer program for the computation of total sediment discharge by the modified Einstein procedure  

USGS Publications Warehouse

Two versions of a computer program to compute total sediment discharge by the modified Einstein procedure are presented. The FORTRAN 77 language version is for use on the PRIME computer, and the BASIC language version is for use on most microcomputers. The program contains built-in limitations and input-output options that closely follow the original modified Einstein procedure. Program documentation and listings of both versions of the program are included. (USGS)

Stevens, H. H.

1985-01-01

46

Coupling annual and decadal patterns of sediment flux with channel morphology in gravel- bedded mountain streams  

NASA Astrophysics Data System (ADS)

Channel morphologic parameters that may be expected to change in response to changes in driving variables of streamflow and sediment supply include bed material grain size, bed configuration, channel width and depth, and gradient. Determination of which variable is most likely to respond to a particular perturbation depends on the type and magnitude of perturbation and the time scale of interest. Channel width is often of primary interest because it has the potential to adjust on a decadal time frame and because it is a typical criterion in the evaluation of stream health and function. Changes in channel width associated with changes in flow and sediment flux on large sand-bed rivers have been frequently described. We have initiated a project to evaluate the coupling between changes in flow and sediment flux and channel morphologic variables and on a gravel-bedded mountain stream. On the Cub River in southern Idaho, a series of streamflow diversions have caused changes in the average pattern of runoff. Peak flows are lower in magnitude and of shorter duration in segments affected by greater proportions of floodwater extraction. Field measurements of sediment transport and calibrated transport relations indicate these changes in streamflow have significantly altered the longitudinal sediment flux. Annual sediment flux significantly decreases downstream in years of average to high runoff, in contrast to the stable or increasing flux that our models predict for undiverted conditions. However, have these changes affected channel morphology to a degree that can be detected on a gravel-bedded mountain stream over a period of ~100 years? Detailed longitudinal measurements of bed elevation, channel width, bed material size, bed mobility, and channel configuration indicate that with increasing magnitude of flow extraction (1) channel width and channel width variability decreases, (2) bed elevation variability increases, (3) bed mobility increases, and (4) there is a greater abundance of gravel bars that are in-channel sediment storage sites. We compare these patterns of channel characteristics with the sediment mass balance to determine the relative importance of changes in channel width and in-channel sediment storage in accommodating the estimated longitudinal imbalance of sediment supply and export.

Grams, P. E.; Schmidt, J.; Majerova, M.

2007-12-01

47

STANDARD-REFERENCE WATER-SUSPENDED SEDIMENT SAMPLE FOR TOTAL RECOVERABLE METALS.  

USGS Publications Warehouse

The U. S. Geological Survey has been preparing and maintaining a library of standard-reference water samples for dissolved inorganic constituents for 19 years. Recently, the reference-sample program was expanded to include a water-suspended sediment mixture for the determination of total recoverable metals. An interlaboratory round-robin study was conducted. Digestion procedures used by the U. S. Geological Survey and the U. S. Environmental Protection Agency were used to solubilize the metals before their measurement. The data indicate that both digestion procedures for total recoverable metals are essentially equivalent. Precision data are comparable to those data obtained in standard-reference water samples for dissolved metals.

Fishman, Marvin, J.; Malo, Bernard, A.; Boyle, Delora, K.

1984-01-01

48

Emission of sulfur from Lake Ontario sediments  

Microsoft Academic Search

Calculations indicate that about 6.0 x 10⁵ kg of sulfur is released annually from Lake Ontario sediments. This constitutes about 1% of the annual sulfur input into the sediments and is insignificant compared to the total sulfur that cycles annually through the lake. The sulfur released from the sediments is enriched in ³²S with the result that the sulfur in

J. O. Nriagu; R. D. Coker

1976-01-01

49

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)

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.

Drott, A.; Skyllberg, U.

2007-12-01

50

Impregnation method for detecting annual laminations in sediment cores: An overview  

NASA Astrophysics Data System (ADS)

Annually laminated sediments can provide an absolute time scale (by varve counting) and a high-resolution palaeoclimate information (from varve thickness). Both types of information may be directly measured from sediment core surfaces. In this paper, we stress that varve counting and varve thickness measurements derived from fresh core surfaces could not systematically reveal the internal sedimentary structure, even if assisted by high resolution image analysis. We present an example of a homogeneous sediment core for which the varves were only observable after core impregnation and polishing steps. Because the impregnation methods are not yet standardized, the aim of this paper is to give an updated review of the methodology. In this review, we present the major critical points during impregnation steps. In particular, we focus on all of the post-treatment sediment disturbances that can alter the laminated micro-structure and, consequently, varve measurements. Finally, we propose a modified impregnation protocol, especially adapted for tracking varved intervals in long cores.

Boës, Xavier; Fagel, Nathalie

2005-08-01

51

Mean annual temperature and total annual precipitation trends at Canadian biosphere reserves.  

PubMed

This article examines instrumental climate records from a variety of stations associated with the following Biosphere Reserves across Canada: (i) Waterton Lakes, (ii) Riding Mountain, (iii) Niagara Escarpment, (iv) Long Point, and (v) Kejimkujik (Candidate Biosphere Reserve). Annual series are generated from daily temperature and precipitation values. In addition, homogeneous data are used from other stations and regional records to supplement the records from the local biosphere stations. Long term trends are identified over the period of the instrumental record. In general, data from the interval 1900 to 1998 show cooler temperatures in the 1920's, warming from the early 1940's into the early 1950's, cooling into the 1970's, and subsequent warming. At many stations, 1998 is the warmest in the instrumental record. Comparisons with the regional data sets show good agreements between the temperature series. The 20th century warming is approximately 1.0 degree C in the Riding Mountain area and 0.6 degrees C in the Long Point, Niagara Escarpment, and Waterton Lakes areas. There has been slight cooling in the Kejimkujik area over the past half century. Precipitation data show increasing trends in the Kejimkujik. Long Point, Niagara Escarpment, and Waterton Lakes areas with no long term trend in the Riding Mountain area. This work is part of the Canadian Biosphere Reserves Association (CBRA) Climate Change Initiative (CCI), designed to present climate change information to Biosphere Reserve communities to allow local organizations to understand climate change and adapt to potential impacts. PMID:11339701

Hamilton, J P; Whitelaw, G S; Fenech, A

2001-01-01

52

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

Microsoft Academic Search

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

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

2007-01-01

53

Total mercury concentration in sediment from the continental shelf of central California  

NASA Astrophysics Data System (ADS)

In order to understand the biogeochemical distribution of mercury (Hg) and locate specific Hg hot spots in the coastal region of central California, total mercury (HgT) concentration were measured in 43 archived sediment cores collected between Año Nuevo and the southern end of Monterey Bay. The samples were taken from USGS in Menlo Park, California on May 4th 2012. The cores were collected through the Environmental Management Assessment Program (EMAP), with ID sites: M-1-95-MB, P-2-95-MB and P-1-97-MB. For the purpose of this study we assumed that there has been negligible diagenesis on trace metal Hg since samples were taken. Total Hg concentrations were measured on the top five cm of the cores and yielded a mean of 0.037 ?g g-1, and ranged from 0.013 to 0.113 ?g g-1. In addition, the 43 samples were split into nine transects, and transects found near the mouth of Monterey Bay submarine canyon (MBSC) contained the highest concentration of HgT, with a mean concentration of 0.043 ?g g-1, and ranged from 0.038 to 0.113 ?g g-1. This substantial increase in HgT concentration near MBSC might be a product of the bathymetry acting as a sink or interaction between internal waves and the canyon's rim. This allows reactivation of surface sediment, which can separate fine grained sand, mud and clay content near the mid-shelf region and the canyon rim. Three depth profiles with 0-30 cm intervals were measured for HgT concentrations. Cores averaged mean HgT concentrations of 0.032, 0.040, and 0.037 ?g g-1, while each profile ranged from 0.025-0.043, 0.028-0.065 and 0.022-0.051 ?g g-1. Each depth profile had slight variations in HgT concentrations. One core located between Daven Port and Santa Cruz displayed decreasing HgT concentration with increasing depth. The inconsistency seen in the depth profiles might be products of external factors such as textural changes as depth increases, changes in Hg fluxes, bio mixing, and diagenesis such as redox reactions. Furthermore, comparisons of our data with sedimentation rates found in Monterey Bay have shown mercury concentration in the sediment not influenced by sedimentation rates. Instead, we observed decrease in mud content corresponded to decrease in HgT concentrations; perhaps supporting Hg's strong correlation to organic matter. Although, the sediment Hg concentration in the coastal regions of Monterey Bay, was substantially lower than those found in San Francisco Bay, the data found in this study is conclusive that the hot spots found near MBSC could be an overlooked source of Hg in coastal environments and needs further investigation.

Acosta, R. M.; Weiss-Penzias, P. S.; Bauer, V.; Ryan, J. P.; Flegal, A. R.

2012-12-01

54

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

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

55

Determination of total chromium in Marine Sediment Reference Material BCSS-1.  

PubMed

The determination of Cr in National Research Council of Canada Marine Sediment Reference Material BCSS-1 is addressed. Mixed acid digestions utilizing HF, HClO(4) and HNO(3) were investigated. Single microwave assisted digestions in closed vessels at medium pressures (8 bar) were inappropriate (80% recovery). Double digestion at moderate pressure and digestions at high pressure (70 bar) or lengthy open-beaker hot plate dissolutions resulted in 93+/-5% recovery of certified Cr content. Flame atomic absorption and inductively coupled plasma atomic emission spectrometry were used for quantitation. In all cases, the method of standard additions was necessary to eliminate the approximately 10% enhancement in re- sponce relative to unmatched standards. Compared to a certified content of 123+/-7 microg/g (mean and standard deviation), values of 116+/-6 were obtained using an open beaker digestion; 114+/-5 using a double microwave digestion at 8 bar; 113+/-2 for microwave digestion at high pressure and 111+/-4 at high pressure (81 bar) with triple microwave digestion in a Parr bomb. No acid dissolution procedure is adequate for Cr in this sample although recovery of total Cr is complete from National Institute of Standards and Technology Buffalo River Sediment (SRM 2704). PMID:15045221

Liu>, J.; Sturgeon, R. E.; Boyko, V. J.; Willie, S. N.

1996-12-01

56

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

USGS Publications Warehouse

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

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

2011-01-01

57

Direct analysis of bottom sediments by a microcoulometric titration method for determination of total organic halide pollutants  

Microsoft Academic Search

.  Up to now the content of the organic halides in sediments was measured as extractable organic halides compounds by different\\u000a methods including microcoulometric titration one. We describe a procedure for microcoulometric determination of total organic\\u000a halide pollutants by using a direct combustion of the sediments into the microcoulometric system furnace. An accelerated removal\\u000a of the inorganic chlorides by reaction with

Pavlina G. Ivanova; Zara V. Aneva

2008-01-01

58

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

NASA Astrophysics Data System (ADS)

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 as the latitudinal symmetrical and asymmetrical parts, A' and A" of A1. Thus, we investigated in detail the TEC climatology from maps of these indices, with an emphasis on the quantitative presentation for local time and latitudinal changes in the seasonal, annual and semiannual anomalies of the ionospheric TEC. Then we took the TEC value at 14:00 LT to examine various anomalies at a global scale following the same procedure. Results reveal similar features appearing in NmF2, such as that the seasonal anomaly is more significant in the near-pole regions than in the far-pole regions and the reverse is true for the semiannual anomaly; the winter anomaly has least a chance to be observed at the South America and South Pacific areas. The most impressive feature is that the equinoctial asymmetry is most prominent at the East Asian and South Australian areas. Through the analysis of the TIMED GUVI columnar [O/N2] data, we have investigated to what extent the seasonal, annual and semiannual variations can be explained by their counterparts in [O/N2]. Results revealed that the [O/N2] variation is a major contributor to the daytime winter anomaly of TEC, and it also contributes to some of the semiannual and annual anomalies. The contribution to the anomalies unexplained by the [O/N2] data could possibly be due to the dynamics associated with thermospheric winds and electric fields.

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

2007-12-01

59

Effect of the 11-year cycle of solar activity on characteristics of the total ozone annual variation  

Microsoft Academic Search

The goal of the paper is an analysis of changes in the amplitude and phase characteristics of the annual variation (AC) of\\u000a total ozone (TO) from ground-based and satellite (TOMS) measurements and their interpretation with a two-dimensional photochemical\\u000a model. According to ground-based TO measurements, two characteristic types of quasi-decadal variations in the phase of the\\u000a annual harmonic (AH) of total

A. N. Gruzdev; G. P. Brasseur

2007-01-01

60

7th Annual NASA/Contractors Conference on Quality and Productivity: "Total Quality Leadership"  

NASA Technical Reports Server (NTRS)

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, processess, and services. The annual NASA/contractors conferences serve as catalysts for achieving success in this mission. The conference was highlighted by the announcement of the first recipients of the George M. Low Trophy: NASA's Quality and Excellence Award. My congratulations go out to all nine finalist organizations and to the two recipients of this prestigious honor: Rockwell Space Systems Division and Marotta Scientific Controls, Inc. (the first small business to achieve this honor). These organizations have demonstrated a commitment to quality that is unsurpassed in the aerospace industry. This report summarizes the presentations and is not intended to be a verbatim proceedings document. You are encouraged to contact the speakers with any requests for further information.

1991-01-01

61

METHODS FOR THE DETERMINATION OF TOTAL ORGANIC CARBON (TOC) IN SOILS AND SEDIMENTS  

EPA Science Inventory

Organic matter in soils and sediments is widely distributed over the earth's surface occurring in almost all terrestrial and aquatic environments (Schnitzer, 1978). Soils and sediments contain a large variety of organic materials ranging from simple sugars and carbohydrates to th...

62

Sediment-adsorbed total mercury flux through Yolo Bypass, the primary floodway and wetland in the Sacramento Valley, California.  

PubMed

The fate and transport of mercury are of critical concern in lowland floodplains and wetlands worldwide, especially those with a history of upstream mining that increases the mobility of both dissolved and sediment-bound Hg in watersheds. A mass budget of total mercury (THg) quantifies sources and storage for particular areas - knowledge that is required for understanding of management options in lowland floodplains. In order to assess contaminant risk in the largest flood-control bypass, prime wetland, and restoration target in the Sacramento River basin, we estimated empirical relationships between THg, suspended sediment concentration (SSC), and streamflow (Q) for each of the major inputs and outputs using data from various publicly available sources. These relationships were improved by incorporating statistical representations of the dynamics of seasonal and intra-flood exhaustion (hysteresis) of sediment and mercury. Using continuous records of Q to estimate SSC suspended sediment flux and SSC to estimate THg flux, we computed the net transfer of sediment-adsorbed mercury through the Yolo Bypass over a decade, 1993-2003. Flood control weirs spilling Sacramento River floodwaters into the bypass deliver ~75% of the water and ~50% of the river's suspended sediment load, while one Coast Range tributary of the bypass, Cache Creek, contributes twice the THg load of the mainstem Sacramento. Although estimated sediment flux entering Yolo Bypass is balanced by efflux to the Sacramento/San Francisco Bay-Delta, there is much evidence of deposition and remobilization of sediment in Yolo Bypass during flooding. These factors point to the importance of the bypass as sedimentary reservoir and as an evolving substrate for biogeochemical processing of heavy metals. The estimates of mercury flux suggest net deposition of ~500 kg in the 24,000 ha floodway over a decade, dominated by two large floods, representing a storage reservoir for this important contaminant. PMID:22078330

Springborn, Michael; Singer, Michael Bliss; Dunne, Thomas

2011-12-15

63

Spatial and seasonal dynamics of total suspended sediment and organic carbon species in the Congo River  

NASA Astrophysics Data System (ADS)

The Congo (Zaire) River, the world's second largest river in terms both of water discharges and of drainage area after the Amazon River, has remained to date in a near-pristine state. For a period between 2 and 6 years, the mainstream near the river mouth (Brazzaville/Kinshasa station) and some of the major and minor tributaries (the Oubangui, Mpoko, and Ngoko-Sangha) were monitored every month for total suspended sediment (TSS), particulate organic carbon (POC), and dissolved organic carbon (DOC). In this large but relatively flat equatorial basin, TSS levels are very low and organic carbon is essentially exported as DOC: from 74% of TOC for the tributaries flowing in savannah regions and 86% for those flowing in the rain forest. The seasonal patterns of TSS, POC, and DOC show clockwise hysteresis in relation to river discharges, with maximum levels recorded 2 to 4 months before peak flows. At the Kinshasa/Brazzaville station, the DOC distribution is largely influenced by the input from the tributaries draining the large marshy forest area located in the center of the basin. There is a marked difference between specific fluxes, threefold higher in the forest basins than in the savannah basins. The computation of inputs to the Atlantic Ocean demonstrates that the Congo is responsible for 14.4 × 106 t/yr of TOC of which 12.4 × 106 t/yr is DOC and 2 × 106 t/yr is POC. The three biggest tropical rivers (the Amazon, the Congo, and the Orinoco), with only 10% of the exoreic world area drained to world oceans, contribute ˜4% of its TSS inputs but 15-18% of its organic carbon inputs. These proportions may double when considering only world rivers discharging into the open ocean.

Coynel, Alexandra; Seyler, Patrick; Etcheber, Henri; Meybeck, Michel; Orange, Didier

2005-12-01

64

Fast and Inexpensive Detection of Total and Extractable Element Concentrations in Aquatic Sediments Using Near-Infrared Reflectance Spectroscopy (NIRS)  

PubMed Central

Adequate biogeochemical characterization and monitoring of aquatic ecosystems, both for scientific purposes and for water management, pose high demands on spatial and temporal replication of chemical analyses. Near-infrared reflectance spectroscopy (NIRS) may offer a rapid, low-cost and reproducible alternative to standard analytical sample processing (digestion or extraction) and measuring techniques used for the chemical characterization of aquatic sediments. We analyzed a total of 191 sediment samples for total and NaCl-extractable concentrations of Al, Ca, Fe, K, Mg, Mn, N, Na, P, S, Si, and Zn as well as oxalate- extractable concentrations of Al, Fe, Mn and P. Based on the NIR spectral data and the reference values, calibration models for the prediction of element concentrations in unknown samples were developed and tested with an external validation procedure. Except Mn, all prediction models of total element concentrations were found to be acceptable to excellent (ratio of performance deviation: RPD 1.8–3.1). For extractable element fractions, viable model precision could be achieved for NaCl-extractable Ca, K, Mg, NH4+-N, S and Si (RPD 1.7–2.2) and oxalate-extractable Al, Fe and P (RPD 1.9–2.3). For those elements that showed maximum total values below 3 g kg?1 prediction models were found to become increasingly critical (RPD <2.0). Low concentrations also limited the performance of NIRS calibrations for extracted elements, with critical concentration thresholds <0.1 g kg?1 and 3.3 g kg?1 for NaCl and oxalate extractions, respectively. Thus, reliable NIRS measurements of trace metals are restricted to sediments with high metal content. Nevertheless, we demonstrated the suitability of NIRS measurements to determine a large array of chemical properties of aquatic sediments. The results indicate great potential of this fast technique as an analytical tool to better understand the large spatial and temporal variation of sediment characteristics in an economically viable way.

Kleinebecker, Till; Poelen, Moni D. M.; Smolders, Alfons J. P.; Lamers, Leon P. M.; Holzel, Norbert

2013-01-01

65

Fast and inexpensive detection of total and extractable element concentrations in aquatic sediments using near-infrared reflectance spectroscopy (NIRS).  

PubMed

Adequate biogeochemical characterization and monitoring of aquatic ecosystems, both for scientific purposes and for water management, pose high demands on spatial and temporal replication of chemical analyses. Near-infrared reflectance spectroscopy (NIRS) may offer a rapid, low-cost and reproducible alternative to standard analytical sample processing (digestion or extraction) and measuring techniques used for the chemical characterization of aquatic sediments. We analyzed a total of 191 sediment samples for total and NaCl-extractable concentrations of Al, Ca, Fe, K, Mg, Mn, N, Na, P, S, Si, and Zn as well as oxalate- extractable concentrations of Al, Fe, Mn and P. Based on the NIR spectral data and the reference values, calibration models for the prediction of element concentrations in unknown samples were developed and tested with an external validation procedure. Except Mn, all prediction models of total element concentrations were found to be acceptable to excellent (ratio of performance deviation: RPD 1.8-3.1). For extractable element fractions, viable model precision could be achieved for NaCl-extractable Ca, K, Mg, NH4 (+)-N, S and Si (RPD 1.7-2.2) and oxalate-extractable Al, Fe and P (RPD 1.9-2.3). For those elements that showed maximum total values below 3 g kg(-1) prediction models were found to become increasingly critical (RPD <2.0). Low concentrations also limited the performance of NIRS calibrations for extracted elements, with critical concentration thresholds <0.1 g kg(-1) and 3.3 g kg(-1) for NaCl and oxalate extractions, respectively. Thus, reliable NIRS measurements of trace metals are restricted to sediments with high metal content. Nevertheless, we demonstrated the suitability of NIRS measurements to determine a large array of chemical properties of aquatic sediments. The results indicate great potential of this fast technique as an analytical tool to better understand the large spatial and temporal variation of sediment characteristics in an economically viable way. PMID:23923001

Kleinebecker, Till; Poelen, Moni D M; Smolders, Alfons J P; Lamers, Leon P M; Hölzel, Norbert

2013-01-01

66

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

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

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

2004-01-01

67

DIATOM INDICATORS OF TOTAL PHOSPHORUS, SEDIMENTS, AND WATERSHED FOREST COVER IN LAKE MICHIGAN COASTAL, RIVERINE WETLANDS  

EPA Science Inventory

Diatom assemblages are being investigated as response and diagnostic indicators as part of our Great Lakes coastal wetlands research designed to support the development of nutrient, habitat, and sediment criteria and to develop community- and landscape-level diagnostic indicator ...

68

Monitoring Fine Sediment; Grande Ronde and John Day Rivers, 1999 Annual Report.  

SciTech Connect

This project was initiated to monitor surface fine sediment levels and overwinter intrusion of fine sediment in spring chinook salmon spawning habitat in the North Folk John Day and Grande Ronde Rivers, for five years.

Rhodes, Jonathan J.; Greene, M. Jonas; Purser, Michael D. (Columbia River Inter-Tribal Fish Commission, Portland, OR)

2000-01-01

69

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

Microsoft Academic Search

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

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

2010-01-01

70

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

NASA Technical Reports Server (NTRS)

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.

1991-01-01

71

Monitoring Fine Sediment; Grande Ronde and John Day Rivers, 2000 Annual Report.  

SciTech Connect

Fine sediment in spawning substrate has a major effect on salmon survival from egg to smolt. Basin-wide restoration plans have established targets for fine sediment levels in spawning habitat. The project was initiated to monitor surface fine sediment levels and overwinter intrusion of fine sediment in spring chinook salmon spawning habitat in the North Fork John Day (NFJDR) and Grande Ronde Rivers, for five years. The project is also investigating the potential relationship between surface fine levels and overwinter sedimentation. It will provide data to assess trends in substrate conditions in monitored reaches and whether trends are consistent with efforts to improve salmon habitat conditions. The data on the magnitude of overwinter sedimentation will also be used to estimate salmon survival from egg to emergence. In Sept. 1998, 1999, and Aug. 2000, sites for monitoring overwinter sedimentation were established in salmon spawning habitat in the upper Grande Ronde River, Catherine Creek (a Grande Ronde tributary), the North Fork John Day River (NFJDR), and Granite Creek (a NFJDR tributary). Surface fine sediment levels were measured in these reaches via the grid method and visually estimated to test the relative accuracy of these two methods. In 1999 and 2000, surface fine sediment was also estimated via pebble counts at selected reaches to allow comparison of results among the methods. Overwintering substrate samples were collected in April 1999 and April-May 2000 to estimate the amount of overwinter sedimentation in clean gravels in spawning habitat. Monitoring methods and locations are described.

Rhodes, Jonathan J.; Greene, M. Jonas; Purser, Michael D. (Columbia River Inter-Tribal Fish Commission, Portland, OR)

2001-01-01

72

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...

73

Estimation of annual suspended-sediment fluxes, 1931-95, and evaluation of geomorphic changes, 1950-2010, in the Arkansas River near Tulsa, Oklahoma  

USGS Publications Warehouse

An understanding of fluvial sediment transport and changing channel morphology can assist planners in making responsible decisions with future riverine development or restoration projects. Sediment rating curves can serve as simple models and can provide predictive tools to estimate annual sediment fluxes. Sediment flux models can aid in the design of river projects by providing insight to past and potential future sediment fluxes. Historical U.S. Geological Survey suspended-sediment and discharge data were evaluated to estimate annual suspended-sediment fluxes for two stations on the Arkansas River located downstream from Keystone Dam in Tulsa County. Annual suspended-sediment fluxes were estimated from 1931-95 for the Arkansas River at Tulsa streamflow-gaging station (07164500) and from 1973-82 for the Arkansas River near Haskell streamflow-gaging station (07165570). The annual flow-weighted suspended-sediment concentration decreased from 1,970 milligrams per liter to 350 milligrams per liter after the completion of Keystone Dam at the Tulsa station. The streambed elevation at the Arkansas River at Tulsa station has changed less than 1 foot from 1970 to 2005, but the thalweg has shifted from a location near the right bank to a position near the left bank. There was little change in the position of most of the banks of the Arkansas River channel from 1950 to 2009. The most substantial change evident from visual inspection of aerial photographs was an apparent decrease in sediment storage in the form of mid-channel and meander bars. The Arkansas River channel between Keystone Dam and the Tulsa-Wagoner County line showed a narrowing and lengthening (increase in sinuosity) over the transition period 1950-77 followed by a steady widening and shortening of the river channel (decrease in sinuosity) during the post-dam (Keystone) periods 1977-85, 1985-2003, and 2003-10.

Lewis, Jason M.; Smith, S. Jerrod; Buck, Stephanie D.; Strong, Scott A.

2011-01-01

74

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

USGS Publications Warehouse

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.

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

2011-01-01

75

Mediterranean (Annually?) Laminated Sediments of Miocene to Pleistocene age; a Study of Seasonal Variability During Precession Minima.  

NASA Astrophysics Data System (ADS)

Laminated sediments are increasingly sought as an excellent archive of paleo-environmental change at a very high temporal resolution comparable to that of ice cores, tree rings and corals. They are found in widely different settings ranging from lacustrine and shallow to deep marine depositional environments. Laminated sediments dominantly reflect the annual cycle, but they can also have a daily or interannual origin or record episodic events such as storm floods. In the Mediterranean Neogene the most conspicuous type of sedimentary cycles is the alternation of homogeneous marls and brown to black coloured, often well-laminated beds enriched in organic carbon, termed sapropels. Sapropels are not distributed evenly or randomly in the stratigraphic succession but display characteristic cycle patterns which reflect the influence of the three orbital parameters (precession, obliquity, and eccentricity). Individual sapropels are related to precession minima and sapropel clusters to eccentricity maxima. Besides sapropels, several other types of laminites are found throughout the Mediterranean. We intend to study diatomites and diatomitic sapropels of Messinian to Pleistocene age which are present in several land sections in Southern Italy. Initial research focuses on the description and classification of laminations found in two Late Pliocene sapropels from the Vrica section of southern Italy. They may provide considerable insight into the biological and sedimentation responses to climate forcing at times of maximum seasonal contrast (i.e. precession minima). In this respect, it is of crucial importance to determine whether the laminations are of annual origin. At a later stage research will also focus on diatomites of various ages in order to compare the different types of laminations present. Such laminated sapropels and diatomites may be used as an excellent geochronometer to detect multi-annual to centennial periodicities in the Mediterranean paleoclimate. Image analysis of the Vrica d and e sapropels will further provide a clearer insight into the duration of sapropel formation. Back scattered electron microscopy has been used extensively by several workers for the analyses of fine laminations, e.g. Dean et al. (1999). Images produced using this method may provide valuable information regarding sedimentological and oceanographical processes at the the time of depositioning. A major problem in this study is the impregnation of the sediment due to the very low porosity of the clays (i.e. poor penetration). First results, however, show that impregnation with Synolite resin is fairly successful. Other types of resin are currently being tested for the impregnation of diatomites. Dean, J. M., A. E. S. Kemp, et al. (1999). "Taking varves to bits: Scanning electron microscopy in the study of laminated sediments and varves." Journal of Paleolimnology 22: pp. 121-136.

Huiskamp, F. P.; Hilgen, F. J.; Lourens, L. J.

2001-05-01

76

Total rate of longshore sediment transport in the surf zone: field measurements and empirical predictions  

Microsoft Academic Search

Roundness decreases with decreasing grain size. The differences among grains of different sizes are most remarkable on barrier beaches, but few differences can be observed in the underlying flood-fluvial sediments of the barrier-lagoon systems. These indicate that grains of different sizes have different potential for being rounded. Grains finer than 0.84 ? are very difficult to round, even on high-energy

Ping Wang; Nicholas C. Kraus; Davis Richard A. Jr

1998-01-01

77

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

Code of Federal Regulations, 2010 CFR

12 Banks and Banking 3 2009-01-01...Reverse Mortgage Transactions K Appendix K to Part 226 Banks...REGULATION Z) Pt. 226, App. K Appendix K to Part 226âTotal Annual...unit-periods per year shall be 12. (iii) If the...

2009-01-01

78

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

Code of Federal Regulations, 2010 CFR

12 Banks and Banking 3 2010-01-01...Reverse Mortgage Transactions K Appendix K to Part 226 Banks...REGULATION Z) Pt. 226, App. K Appendix K to Part 226âTotal Annual...unit-periods per year shall be 12. (iii) If the...

2010-01-01

79

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

NASA Astrophysics Data System (ADS)

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 (Blass et al. 2007, Trachsel et al. 2008) and compare well with alpine tree-ring reconstructions and climate field reconstructions. The combined response of the proxies to climate state variables was assessed using redundancy analysis (RDA). After evaluating different regression and calibration models such as principle components regression, ordinary least squares regression and partial least squares regression the most parsimonious model was used to infer summer temperature. Our multi-proxy reconstruction does not show a distinct summer temperature cooling during Little Ice Age, whereas a climate amelioration was reconstructed during medieval times. References: Blass, A., Grosjean, M., Troxler, A., and Sturm, M. (2007). How stable are twentieth-century calibration models? A high-resolution summer temperature reconstruction for the eastern Swiss Alps back to AD 1580 derived from proglacial varved sediments. The Holocene. Trachsel, M., Eggenberger, U., Grosjean, M., Blass, A., and Sturm, M. (2008). Mineralogy-based quantitative precipitation and temperature reconstructions from annually laminated lake sediments (Swiss Alps) since AD 1580. Geoph. Res. Let.

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

2009-04-01

80

Geochemical signature of contaminated sediment remobilization revealed by spatially resolved X-ray microanalysis of annual rings of Salix nigra.  

PubMed

An X-ray microprobe was used to determine the concentration and distribution of Ni, U, and other metals within annual rings of willows (Salix nigra L.) from a former de facto radiological settling basin (Steed Pond; SP) and a depositional environment downstream (Tims Branch; TB) on the Savannah River Site (SRS). Geochemical and historical information about both areas are well documented. Following spillway breaches at SP in 1984 and the early 1990s, TB is inundated with contaminated sediments during storms. Bulk elemental composition of tree cores was determined using ICP-OES. Synchrotron X-rayfluorescence (SXRF) analysis showed that the metal contents of SP and TB cores were an order of magnitude higher than those from a reference site. TB cores were enriched with Ni in 1984 and 1991, corresponding with SP spillway breaches (containing 790 mg kg(-1) Ni in 1991). Cores from SP exhibited an extremely high Ni peak in 1996, approximately 5000 mg kg(-1), even though contaminant levels at SP did not change. The geochemical signature of contaminants recorded in TB annual rings reflected the significant sediment remobilization events consistent with the detailed history of the site, and at concentrations relative to their proximity to the source term. However, physiological processes occurring within impacted trees strongly influence the chronological accuracy of dendroanalysis and must be investigated further. PMID:12775047

Punshon, Tracy; Bertsch, Paul M; Lanzirotti, Antonio; McLeod, Ken; Burger, Joanna

2003-05-01

81

Phosphorus dynamics and bioavailability in sediments of the Penzé Estuary (NW France): in relation to annual P-fluxes and occurrences of Alexandrium Minutum  

Microsoft Academic Search

The macrotidal estuary of Penzé (Brittany, Western part of the Channel, France) has been subjected to recurrent annual toxic\\u000a blooms of Alexandrium minutum since 1988. This study aims to specify the phosphorus dynamics and bioavailability in sediments in order to improve our understanding\\u000a of Alexandrium occurrences. Sediment-P pools and diffusive phosphate fluxes were studied under similar hydrodynamic conditions, in the

F. Andrieux-Loyer; X. Philippon; G. Bally; R. Kérouel; A. Youenou; J. Le Grand

2008-01-01

82

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.  

National Technical Information Service (NTIS)

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 exten...

2001-01-01

83

Distribution and transport of total mercury and methylmercury in mercury-contaminated sediments in reservoirs and wetlands of the Sudbury River, east-central Massachusetts  

USGS Publications Warehouse

Total mercury and methylmercury were measured in 4 reservoir cores and 12 wetland cores from Sudbury River. The distribution of total mercury and methylmercury in these cores was evaluated to determine the potential for total mercury and methylmercury transport from reservoir and wetlands sediments to the water column. Concentrations of methylmercury were corrected for an analytical artifact introduced during the separation distillation used in the analysis procedure. Corrected methylmercury concentrations correlated with total mercury concentrations in bulk sediment from below the top layers of reservoir and wetland cores; methylmercury concentrations at the top layers of cores were relatively high, however, and were not correlated with total mercury concentrations. Concentrations of methylmercury in pore water were positively correlated with methylmercury concentrations in the bulk sediment. High concentrations of total mercury and methylmercury in sediment (73 and 0.047 micrograms per gram dry-weight basis, respectively) contributed less to the water column in the reservoir than in the wetlands probably because of burial by low concentration sediment and differences in the processes available to transport mercury from the sediments to the water in the reservoirs, as compared to the wetlands .

Colman, John A.; Waldron, Marcus C.; Breault, Robert F.; Lent, Robert M.

1999-01-01

84

Paleoenvironmental changes during the last 8,500 years recorded in annually laminated sediments from Lake Szurpi?y, NE Poland  

NASA Astrophysics Data System (ADS)

Annually laminated (varved) lake sediments provide a precise time scale for high-resolution paleoenvironmental reconstructions of climatic change and human impact. We reconstructed the environmental changes from Lake Szurpi?y (NE Poland) using varve chronology and multi-proxy interdisciplinary approach. Our reconstruction is one of the few for NE Poland and extends the geographical network of laminated lacustrine sediments. This research was supported by the Polish Ministry of Science and Higher Education grants (N N306 275635, N N306 009337, N N306 291639). It is a contribution to the bilateral scientific program "Northern Polish Lake Research" (NORPOLAR). Parallel overlapping sediment cores with total length of 12.38 m and extending back to the Late Glacial were retrieved in 2007. The geochemical (X-ray Fluorescence, CNS, stable isotopes), microscopic (varve thickness and structure), biological (diatoms, pollen) and statistical analyses were applied and combined in an annual scale based on the varve chronology, which was verified by independent radiometric dating (Pb-210, Cs-137 and AMS radiocarbon dating). Due to the large slump, this study focuses on the almost continuously varved uppermost 7.58-m long section of the profile, covering the last 8,500 years. The climate fluctuations were the main cause of the environmental changes during the first 6,000 years. The geochemical record is mainly driven by the lake productivity, oxic conditions and minerogenic input. Although the first evidence of the anthropogenic impact is documented in pollen record at 8,000 BP, the environmental conditions were relatively stable until 2,500 BP, when the human activity increased significantly. Since that time the climatic and human influence are combined and more difficult to disentangle. Three settlement phases separated by natural regeneration of the environment occurred between 2,500-400 BP. The variation of geochemical and pollen data at 400-100 BP reflects climate fluctuations during Little Ice Age. The synchronous distinct change in the variability of ?13C, lithogenic elements, C/N ratio and pollen (high percentage of Bryales) may be interpreted as the allochtonous organic matter enrichment related to forest clearing and soil erosion. The lake productivity increased possibly due to the peat bogs drainage and agriculture development. The lake become eutrophic in the last period (since 150 BP).

Kinder, Ma?gorzata; Tylmann, Wojciech; Bubak, Iwona; Enters, Dirk; Kupryjanowicz, Miros?awa; Mayr, Christoph; Ohlendorf, Christian; Piotrowska, Natalia; Zolitschka, Bernd

2014-05-01

85

ESCHERICHIA COLI AND TOTAL COLIFORMS IN WATER AND SEDIMENTS AT LAKE MARINAS  

EPA Science Inventory

Escherichia coli, a fecal coliform, and total coliforms were monitored between September 1999 to October 2001 in five marinas on Lake Texoma, located on the Oklahoma and Texas border. General trend was that densities of E. coli were lower in the summer season due to the lower ...

86

Coupling annual and decadal patterns of sediment flux with channel morphology in gravel bedded mountain streams  

Microsoft Academic Search

Channel morphologic parameters that may be expected to change in response to changes in driving variables of streamflow and sediment supply include bed material grain size, bed configuration, channel width and depth, and gradient. Determination of which variable is most likely to respond to a particular perturbation depends on the type and magnitude of perturbation and the time scale of

P. E. Grams; J. Schmidt; M. Majerova

2007-01-01

87

USING A BANK EROSION HAZARD INDEX (BEHI) TO ESTIMATE ANNUAL SEDIMENT LOADS FROM STREAMBANK EROSION IN THE WEST FORK WHITE RIVER WATERSHED  

Microsoft Academic Search

The Arkansas Department of Environmental Quality (ADEQ), through an EPA Section 319 NPS grant, utilized a bank erosion hazard index (BEHI) and data collected from surveys of streambank profile measurements to develop a graphical model to estimate streambank erosion rates and to estimate the annual sediment load due to accelerated streambank erosion in the West Fork White River (WFWR) watershed.

M. A. Van Eps; S. J. Formica; T. L. Morris; J. M. Beck; A. S. Cotter

88

Export of dissolved organic and inorganic nitrogen and total suspended sediments across an urbanization gradient in four tropical rivers of Venezuela  

NASA Astrophysics Data System (ADS)

We determined monthly concentrations of total dissolved nitrogen (TDN), dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON) and total suspended sediment (TSS) from 4 Venezuelan watersheds from August 2008 to September 2009. Three of these watersheds are mountainous rivers (Tuy, Neverí and Manzanares) and one is flat (Unare River). The three mountainous rivers vary in the degree of urbanization, with the Tuy hosting Caracas, the largest city in Venezuela. We found an order of magnitude larger TDN concentrations in the Tuy, which is impacted mainly by untreated point sources derived from Caracas metropolitan area. The largest TSS values were observed in the three mountainous rivers (Tuy, Neveri and Manzanares). TDN and TSS concentrations varied seasonally with larger TDN and lower TSS values during the dry season for all rivers. Most of the annual discharge of TDN (92%) and TSS (97%) takes place during the rainy season. Our results suggest that urbanization is the largest contributor affecting the composition and magnitude of TDN, whereas orography and local hydrology control the discharge of both TSS and TDN. We calculated the Water Pollution Level (WPL) for DIN and DON to determine the degree of contamination of these species in the evaluated watersheds. WPL values less than 1 indicate that there is in average enough dilution capacity in the river to assimilate the pollutant, whereas WPL larger than 1 indicate that the pollution assimilation capacity has been surpassed. All our evaluated rivers but the Tuy River show WPL-DIN and WPL-DON values between 0.1 and 0.96. The Tuy River had a WPL-DIN=6.3 and WPL-DON= 7.5. We attribute the Tuy River's large DIN and DON contamination to untreated urban point sources due to the strong correlation between population density and DIN and DON concentration from the evaluated watersheds. Our results suggest that urgent water treatment is required for this watershed to diminish the impact in coastal ecosystems.

Rasse, R. J.; Perez, T.; Giuliante, A.; Donoso, L.

2012-12-01

89

Total Maximum Daily Load of Sediment in the Little Patuxent River Watershed, Howard and Anne Arundel Counties, Maryland.  

National Technical Information Service (NTIS)

Currently in Maryland, there are no specific numeric criteria that quantify the impact of sediment on the aquatic life of nontidal stream systems. Therefore, to determine whether aquatic life is impacted by elevated sediment loads, MDEs Biological Stresso...

2011-01-01

90

Mass-height profile and total mass transport of wind eroded aeolian sediments from rangelands of the Indian Thar Desert  

NASA Astrophysics Data System (ADS)

Wind erosion is an active land degradation process in the Indian Thar Desert and severe dust storm events during hot summer months in the region are very common. Assessment of soil loss due to dust storm events from major land use systems of the Indian Thar Desert is highly essential for proper environmental planning. Characterization of the mass-height profile of wind eroded aeolian sediment is an important step to compute soil loss/mass transport but was not previously studied in the region. In the present study, aeolian mass fluxes (kg m -2) at different heights from soil surface were measured at two major rangelands in the Indian Thar Desert: Overgrazing rangeland at Jaisalmer (26°55'N and 70°57'E), and controlled grazing rangeland at Chandan (27°01'N and 71°01'E). Evaluation of several mass-height profile models revealed that a power decay function [ q( z) = az-b, where q( z) is the measured mass flux at an height of z (m) from soil surface; a and b are parameters of the equation] was best to characterize the mass-height relationship of aeolian sediments from the Indian Thar Desert. The average mass transport rate (kg m -1 day -1) or the total soil loss during hot summer months was significantly higher at the overgrazed rangeland site than at the controlled grazing rangeland site. Therefore, protection of existing rangelands, which comprise about 80% geographical area of the Indian Thar Desert may check the land degradation process due to wind erosion.

Mertia, R. S.; Santra, Priyabrata; Kandpal, B. K.; Prasad, R.

2010-11-01

91

A comparative study of metal pollution and potential eco-risk in the sediment of Chaohu Lake (China) based on total concentration and chemical speciation.  

PubMed

Total and extractable concentrations of Cu, Pb, and Zn were determined in surface sediments of west Chaohu Lake (China) by HCl-HNO3-HF-HClO4 digestion and an optimized BCR sequential extraction procedure, respectively. The metal pollution was evaluated by the enrichment factor approach, and the potential eco-risk was evaluated by the sediment quality guideline (SQG) and risk assessment code (RAC) assessments. The results indicated that both total and extractable metal concentrations were highly variable and were affected by sediment properties, even though the sediments were predominantly composed of <63-?m particles (>89 %). Enrichment factors of the metals based on the total and extractable concentrations all showed higher values in the northern lake area and decreasing values towards the south. This distribution indicated an input of anthropogenic metals via the Nanfei River. Anthropogenic Cu, Pb, and Zn in surface sediments showed comparable values for each metal based on the total and extractable concentrations, suggesting that anthropogenic Cu, Pb, and Zn resided predominantly in the extractable fractions. Sediment Cu had low eco-risk, and Pb and Zn had medium eco-risk by the SQG assessment, whereas the eco-risk rankings of Cu, Pb, and Zn were medium, low, and low-high, respectively, by the RAC assessment. Referencing to the labile (dilute acid soluble) metal concentrations, we deduced that the eco-risk of Cu may be largely overestimated by the RAC assessment, and the eco-risk of Pb may be largely overestimated by the SQG assessment. Overall, sediments Cu and Pb may pose low eco-risk, and Zn may pose low-high eco-risk. PMID:24566968

Liu, Enfeng; Shen, Ji

2014-06-01

92

An Assessment of The Contribution of Organic Carbon of Terrigenous Origin To The Total Organic Carbon In Sediments In Scottish Coastal Waters (sea Lochs and Shelf Depressions)  

NASA Astrophysics Data System (ADS)

Sedimentary organic carbon is of global importance because it represents a significant sink of fixed carbon, which is being lost from the biosphere through eventual burial. In the process some carbon is remineralized which fuels marine biogeochemical cycles and returns most of the bound nutrients to the water column. In addition it may bind anthropogenic contaminants, such as heavy metals and PCBs which are removed from the water column. Sea lochs are representative of low energy hydrographic regimes and act as traps for sediment, which generally accumulates at high rat es. The sediments are associated with enhanced levels of terrigenous input, and are rich in organic matter. Further out to sea towards the shelf break, sedimentation rates decrease and the contribution of carbon of marine origin to the total decreases. It is generally considered that organic carbon of marine origin is readily degradable and that organic carbon of terrestrial origin is refractory and eventually becomes integrated into permanent sediment deposits. Thus terrigenous particulate organic carbon would be transported across the shelf and deposited on the shelf slope. Recent experiments have shown however, that on a transect from the head of Loch Etive (West Coast of Scotland) to the sea, it is the input of particulate terrigenous organic carbon that seems to determine the oxygen uptake rates. Work presented in this paper is being undertaken in association with the Centre for Coastal and Marine Sciences core programme, Restricted Exchange Environments. The wider study involves measuring processes such as oxygen uptake rates, sulphate reduction rates and total sediment carbon contents. The aims of the research presented here is to assess the contribution of terrigenous organic carbon to total carbon inputs; to assess degradation of organic carbon; to measure lignin content of sediment; to compare sedimentation rates with those outside the loch and to measure sedimentary carbon of marine origin. One primary method adopted is to measure the lignin content of various sediments and sediment trap fractions. Lignin has long- been used to identify land derived organic material. The projected long-term outcome is a data set that will allow correlation of the terrigenous organic carbon content in sediments with measures of the biogeochemical reactivity of those sediments. In addition, the results will allow us to make some estimate of the local rate of burial of terrigenous and marine organic carbon that is being removed from the biosphere.

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

93

Spatio-temporal changes in totally and enzymatically hydrolyzable amino acids of superficial sediments from three contrasted areas  

NASA Astrophysics Data System (ADS)

Spatio-temporal changes in totally and enzymatically hydrolyzable amino acids (THAA and EHHA) and EHAA/THAA ratios of superficial sediments were assessed during 1997-1999 in three areas (i.e., the Gulf of Lions, the Bay of Biscay, and Central Chile) differing in their primary productivity. In all three areas, and even off Central Chile where a strong El Niño event took place during 1997-1998, spatial changes were always much greater than temporal ones. The factors affecting the spatial distributions of amino acid concentrations differed among areas. In the Gulf of Lions, sediment granulometry was apparently the most important driving force of THAA, EHAA, and EHAA/THAA, and there was no marked difference between stations located on the open slope and those in submarine canyons. Conversely, in the Bay of Biscay, there were clear differences between the stations located off Cap-Breton, on the open slope, and those in the Cap-Ferret canyon; the latter two featuring lower EHAA and THAA but higher EHAA/THAA. This pattern is likely to result from the predominance of different sources of organic matter and especially from the importance of continental inputs to the Cap-Breton canyon. Off Central Chile, amino acid concentrations and ratios were both maximal around 100 m depth, probably reflecting the interaction between the primary productivity gradient and the presence of an oxygen minimum zone (OMZ) reducing the degradation of sedimentary organics. When comparing the average values collected in the three areas studied, THAA and EHAA were highest in Central Chile, intermediate in the Bay of Biscay and lowest in the Gulf of Lions. EHAA/THAA ratios were also highest in Central Chile but were lowest in the Bay of Biscay. Differences between the Gulf of Lions and the Bay of Biscay could have been affected by sampling design. In Central Chile, the use of labile organic carbon to total organic carbon (C-LOM/TOC) and EHAA/THAA as indices of organic matter lability led to very similar results. This was not the case in the Bay of Biscay. It is therefore argued that the use of C-LOM/TOC should be restricted to highly productive areas.

Grémare, Antoine; Gutiérrez, Dimitri; Anschutz, Pierre; Amouroux, Jean Michel; Deflandre, Bruno; Vétion, Gilles

2005-04-01

94

Spatial distribution and concentration assessment of total petroleum hydrocarbons in the intertidal zone surface sediment of Todos os Santos Bay, Brazil.  

PubMed

The primary objective of this study was to investigate the concentrations and spatial distribution of the total petroleum hydrocarbons (TPHs) in the intertidal zone surface sediment of Todos os Santos Bay, Brazil, to assess the distribution and degree of contamination by TPHs, measure the level of TPH degradation in the surface sediment, and identify the organic matter sources. The surface sediment used in this study was collected in 50 stations, and TPHs, isoprenoid alkanes (pristane and phytane), and unresolved complex mixture (UCM) were analyzed by gas chromatography with a flame ionization detector. The total concentrations ranged from 0.22 to 40,101 ?g g(-1) dry weight and showed a strong correlation with the total organic carbon (TOC) content. The highest TPH concentrations were observed in samples from the mangrove sediments of a river located near a petroleum refinery. Compared with other studies in the world, the TPH concentrations in the intertidal surface sediment of Todos os Santos Bay were below average in certain stations and above average in others. An analysis of the magnitude of UCM (0.11 to 17,323 ?g g(-1) dry weight) and the ratios nC17/Pr and nC18/Ph suggest that an advanced state of oil weathering, which indicates previous contamination. The molar C/N ratios varied between 5 and 43, which indicate organic matter with a mixed origin comprising marine and continental contributions. PMID:24100798

Silva, Carine S; Moreira, Icaro T A; de Oliveira, Olivia M C; Queiroz, Antonio F S; Garcia, Karina S; Falcão, Brunno A; Escobar, Narayana F C; Rios, Mariana Cruz

2014-02-01

95

Total Quality Management on Campus: Pipe Dream or New Paradigm? AIR 1994 Annual Forum Paper.  

ERIC Educational Resources Information Center

This study looked at how Total Quality Management (TQM) is being adopted in institutions of higher education. A questionnaire was developed seeking information on: (1) leadership of the TQM movement and timing of events; (2) the training, educating, and informing of employees; (3) specific areas using TQM and the specific statistical tools being…

Freed, Jann E.; And Others

96

Total Quality Management: Statistics and Graphics II-Control Charts. AIR 1992 Annual Forum Paper.  

ERIC Educational Resources Information Center

An examination was conducted of the control chart as a quality improvement statistical method often used by Total Quality Management (TQM) practitioners in higher education. The examination used an example based on actual requests for information gathered for the Director of Human Resources at a medical center at a midwestern university. The…

Cherland, Ryan M.

97

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

NASA Astrophysics Data System (ADS)

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 DNA synthesis (a measure of bacterial growth) and the concentration of bulk POC and total nitrogen in surficial deep-sea sediments and recently deposited phytodetritus, at three sites in the NE Atlantic. We found statistically significant positive exponential relationships between bacterial numbers and [ 3H]-thymidine incorporation rates (DNA synthesis) and sediment and phytodetritus % particulate organic carbon (POC) and % total nitrogen (%TN) from samples collected in the deep NE Atlantic at three different times at 3 contrasting sites. Mean bacterial numbers were in the range 5.6-53.2×10 10 cell l -1 in surficial sediments and 9.2-12.9×10 10 cells l -1 in the phytodetritus; [ 3H]-thymidine incorporation rates were 14.8-593.7 pmol l -1 h -1 in the sediment and 395.8-491.4 pmol l -1 h -1 in the phytodetritus. POC concentrations were 0.22-0.61% in the sediment and 0.92-0.99% in the phytodetritus; TN was 0.04-0.09% in the sediment and 0.13-0.14% in the phytodetritus. The C:N ratio was 6.7-9.0 in sediment and 7.6-7.9 in phytodetritus. In addition, a positive exponential relationship was still evident with the inclusion of other data from the NE Atlantic and Solomon and Coral Sea. The logarithmic regression for this combined relationship was not statistically different from the one derived from the current data alone. However, the relationship failed with the inclusion of data from the highly eutrophic Arabian Sea, which has a mid-water oxygen minimum zone that may inhibit heterotrophic bacterial production. This implies that such a relationship is not generic to all ocean systems, and additional research is required to further test the relationship between bacterial [ 3H]-thymidine incorporation rates and % POC from other oceanic deep-sea surficial sediments.

Turley, C. M.; Dixon, J. L.

2002-05-01

98

Effect of pH, sulphate concentration and total organic carbon on mercury accumulation in sediments in the Volta Lake at Yeji, Ghana.  

PubMed

In this study, pH, total organic carbon, sulphate concentration and mercury concentrations of sediment samples from the Volta Lake at Yeji in the northern part of Ghana were determined. The results indicate that pH ranged from 6.32 to 8.21, total organic carbon ranged from 0.17 to 3.02 g/kg and sulphate concentration from 10.00 to 57.51 mg/kg. Total mercury concentrations ranged from 32.61 to 700 ng/g which is below the International Atomic Energy Agency recommended value of 810 ng/g. Humic substance-bound mercury ranged from 81.15 to 481.31 mg/kg in sediments and its two fractions existed as humic acid-bound mercury > fulvic acid-bound mercury with the ratio of humic substance-bound mercury to fulvic acid-bound mercury as 1.62 on the average. Humic substance-bound mercury and the two fractions fulvic acid-bound mercury and humic substance-bound mercury in sediments were favorably determined and found to correlate significantly positive with total organic carbon (r = 0.538) and total mercury (r = 0.574). However, there were poor correlations between SO(4) (2-) concentrations and humic substance-bound mercury (r = -0.391) as well as the two fractions; fulvic acid (r = -0.406) and humic acid (r = -0.381). By assuming that methyl mercury is mostly formed in sediments, these significant relations suggest that the efficiency of mercury being methylated from a given inorganic form depends on the amount, and most likely biochemical composition of total organic carbon in the lake sediment but not the SO(4) (2-) concentration. PMID:22258497

Kwaansa-Ansah, E E; Voegborlo, R B; Adimado, A A; Ephraim, J H; Nriagu, J O

2012-03-01

99

Evaluation of heavy metal contamination in sediments using the method of total digestion and determination of the binding forms-Tisa River Basin, Serbia  

Microsoft Academic Search

This paper describes an approach for the evaluation of metal contamination in sediment, using the determination of binding forms of elements (sequential extraction method), the total element content (digestion method), as well as a comparison of the obtained results with the legislative limits of the EU. Results indicate that silicates are significant substrates for Ni and Cr, whereas Zn, Cd,

Sanja M. Sakan; Dragana S. ?or?evi?

2010-01-01

100

Assessment of Total Aromatic Hydrocarbons, Aliphatic and Polycyclic Aromatic Hydrocarbons in Surface Sediment and Fish from the Gulf of Tunis (Tunisia)  

Microsoft Academic Search

This investigation represents the extensive study of the spatial distribution and sources of hydrocarbons in the Gulf of Tunis. Sediments and fish were sampled within the open sea of the Gulf of Tunis during August 2004. All samples were extracted with organic solvents, separated by silica\\/alumina column chromatography, and analyzed by spectrofluorometry for the determination of total aromatic hydrocarbons (TAH)

Nadia Mzoughi; Lassaad Chouba; Gaëtane Lespes

2010-01-01

101

A combination of organic carbon/total nitrogen ratios and pyrite contents in sediments as a paleoenvironmental indicator: A preliminary study in northern Kyushu, Japan  

SciTech Connect

Organic carbon (Corg) and total nitrogen (N) contents in Tertiary mudstone samples from four basins in northern Kyushu, Japan, were determined by using a CHN analyzer. A good correlation was observed between the stratigraphic distribution of the Corg/N values and geologically inferred depositional environments. Pyrite contents in carbonaceous sediments from the same basins were also obtained employing a reflecting microscope. Stratigraphic changes of pyrite content in carbonaceous sediments can be correlated with these depositional environments. Pyrite is expected to play a useful role as an index mineral in estimation of depositional environments in future studies.

Miki, Takashi [Kyushu Univ., Fukuoka (Japan). Dept. of Earth and Planetary Sciences; Aizawa, Jun [Fukuoka Univ. (Japan). Dept. of Geology

1995-01-01

102

Late Holocene climate of the Eastern Mediterranean inferred from diatom analysis of annually-laminated lake sediments  

NASA Astrophysics Data System (ADS)

Diatoms from the annually-laminated sediments of Nar crater lake in central Turkey are used to investigate climatic changes throughout the last 1720 years at decadal time resolution. A diatom-conductivity transfer function is employed to infer past water balance. Further information has been extracted from the palaeo-record through calculation of diatom biovolume, rarefaction (species diversity) and concentration, and through the identification of diatom bloom events in core thin sections. The Nar diatom sequence is compared with oxygen isotope (? 18O) and pollen records from the same sediment cores in order to test the respective roles of changes in climate and land cover. Diatom-inferred (DI) conductivity excluding bloom taxa and ? 18O show very good correspondence for the first half of the record and demonstrate that this region experienced a period of century-scale drought prior to AD 540, with a subsequent rapid and simultaneous shift to fresher lake conditions and wetter climate. After a drier phase in the Nar record from AD 800-950, the period of the Medieval Climate Anomaly (AD 950-1400) was generally well watered. During the subsequent Little Ice Age (˜AD 1700-1900), DI-conductivity and ? 18O become decoupled. Thin sections reveal between 20 and 40 distinct diatom bloom events per century since AD 1100, with increasing frequency between AD 1700 and 2000. Human land-use changes evident in the pollen sequence may have influenced the diatom relationship with lake water conductivity in the later part of the record. None the less, diatom DCA axes do show a clear response to multi-decadal drought events within the last six centuries. Differences between the proxy-climate records from Nar Lake may be associated with the dissimilar thresholds to environmental fluctuations and non-stationarity in the response of different proxies through time. The palaeoclimate records from Nar show that arid periods occurred in the Eastern Mediterranean during the last two millennia that were more prolonged and extreme than those experienced in the last century.

Woodbridge, Jessie; Roberts, Neil

2011-11-01

103

Evaluation of heavy metal contamination in sediments using the method of total digestion and determination of the binding forms-Tisa River Basin, Serbia.  

PubMed

This paper describes an approach for the evaluation of metal contamination in sediment, using the determination of binding forms of elements (sequential extraction method), the total element content (digestion method), as well as a comparison of the obtained results with the legislative limits of the EU. Results indicate that silicates are significant substrates for Ni and Cr, whereas Zn, Cd, Pb, and Cu were not dominantly bound to silicates. Mg is present in the form of carbonates and silicates; Fe is in the form of oxides, and Mn is in the form of Mn carbonate and oxides. Zn, Cd, and Cu are dominantly extracted in the labile fractions and because of this they are likely to pose a direct and significant threat to the environment. The results of a comparison with the legislative limits of the EU indicated that in some of the sediments, elevated levels of Zn, Cd, and Cu exist. The contamination was caused by permanent pollution, originating mainly from industrial activities, municipal sewage discharge and agriculture. Results indicate to the significance of the employment both of methods, sequential extraction and total digestion, for metal investigation in sediment. With the aim of protecting the sediment quality of the Tisa River, of importance for Central Europe, the obtained results also indicate the necessity for systematic investigations in all countries through which this river flows. PMID:20397085

Sakan, Sanja M; Dordevi?, Dragana S

2010-01-01

104

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

PubMed

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

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

2013-05-15

105

Application of Infrared-Attenuated Total Reflection Technique Combined with Sedimentation Phenomena to Particle Size Measurement: Fundamental Experiments on Applicability of the Method  

NASA Astrophysics Data System (ADS)

A new method using infrared attenuated total reflection (IR-ATR) spectroscopy and sedimentation of particles in a suspension was proposed for particle size measurement. The time dependence of the IR-ATR signal intensity for mono-size dispersed particles agreed qualitatively with the theoretical expectation. Content analyses of samples containing dispersed particles of two sizes gave values close to actual ones. The possibility of size distribution analysis was shown.

Sarno, B. J.; Yoshidome, T.; Ikuta, Y.; Rabor, J. B.; Tsurumura, Y.; Montecillo, M. E.; Higo, M.

2013-09-01

106

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

USGS Publications Warehouse

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.

Juracek, K. E.

1997-01-01

107

Bioprospecting from Marine Sediments of New Brunswick, Canada: Exploring the Relationship between Total Bacterial Diversity and Actinobacteria Diversity  

PubMed Central

Actinomycetes are an important resource for the discovery of natural products with therapeutic properties. Bioprospecting for actinomycetes typically proceeds without a priori knowledge of the bacterial diversity present in sampled habitats. In this study, we endeavored to determine if overall bacterial diversity in marine sediments, as determined by 16S rDNA amplicon pyrosequencing, could be correlated with culturable actinomycete diversity, and thus serve as a powerful tool in guiding future bioprospecting efforts. Overall bacterial diversity was investigated in eight marine sediments from four sites in New Brunswick, Canada, resulting in over 44,000 high quality sequences (x = 5610 per sample). Analysis revealed all sites exhibited significant diversity (H’ = 5.4 to 6.7). Furthermore, statistical analysis of species level bacterial communities (D = 0.03) indicated community composition varied according to site and was strongly influenced by sediment physiochemical composition. In contrast, cultured actinomycetes (n = 466, 98.3% Streptomyces) were ubiquitously distributed among all sites and distribution was not influenced by sediment composition, suggesting that the biogeography of culturable actinomycetes does not correlate with overall bacterial diversity in the samples examined. These actinomycetes provide a resource for future secondary metabolite discovery, as exemplified by the antimicrobial activity observed from preliminary investigation.

Duncan, Katherine; Haltli, Bradley; Gill, Krista A.; Kerr, Russell G.

2014-01-01

108

Total Viable Count and Concentration of Enteric Bacteria in Bottom Sediments from the Czarna Ha?cza River , Northeast Poland  

Microsoft Academic Search

Studies were carried out to determine counts of TVC 20°C, TVC 37°C, TC, FC, FS and Clostridium perfringens in bottom sediments of the Czarna Haricza River, from about 1 cm layer, at 10 stations located in Suwatki region (stations 1 and 2), in the villages Sobolewo (stations 3 and 4), the old river bed of the Czarna Hancza and its

S. Niewolak

1998-01-01

109

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

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)

Hickman, R. E.

1989-01-01

110

Correlations between speciation of Cd, Cu, Pb And Zn in sediment and their concentrations in total soft tissue of green-lipped mussel Perna viridis from the west coast of Peninsular Malaysia.  

PubMed

Total concentrations and speciation of cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) in surface sediment samples were correlated with the respective metal measured in the total soft tissue of the green-lipped mussel Perna viridis, collected from water off the west coast of Peninsular Malaysia. The aim of this study is to relate the possible differences in the accumulation patterns of the heavy metals in P. viridis to those in the surface sediment. The sequential extraction technique was employed to fractionate the sediment into 'freely leachable and exchangeable' (EFLE), 'acid-reducible,' 'oxidisable-organic' and 'resistant' fractions. The results showed that significant (P<.05) correlations were observed between Cd in P. viridis and Cd in the sediment (EFLE fraction and total Cd), Cu in P viridis and Cu in the sediment (EFLE and 'acid-reducible' fractions and total Cu) and Pb in P viridis and Pb in the sediment ('oxidisable-organic' fraction and total Pb). No significant correlation (P > .05) was found between Zn in P viridis and all the sediment geochemical fractions of Zn and total Zn in the sediment. This indicated that Zn was possibly regulated from the soft tissue of P. viridis. The present results supported the use of P viridis as a suitable biomonitoring agent for Cd, Cu and Pb. PMID:12046948

Yap, C K; Ismail, A; Tan, S G; Omar, H

2002-04-01

111

Total petroleum hydrocarbons and heavy metals in the surface sediments of Bohai Bay, China: Long-term variations in pollution status and adverse biological risk.  

PubMed

Surface sediments collected from 2001 to 2011 were analyzed for total petroleum hydrocarbons (TPH) and five heavy metals. The sediment concentration ranges of TPH, Zn, Cu, Pb, Cd and Hg were 6.3-535?g/g, 58-332?g/g, 7.2-63?g/g, 4.3-138?g/g, 0-0.98?g/g, and 0.10-0.68?g/g, respectively. These results met the highest marine sediment quality standards in China, indicating that the sediment was fairly clean. However, based on the effects range-median (ERM) quotient method, the calculated values for all of the sampling sites were higher than 0.10, suggesting that there was a potential adverse biological risk in Bohai Bay. According to the calculated results, the biological risk decreased from 2001 to 2007 and increased afterwards. High-risk sites were mainly distributed along the coast. This study suggests that anthropogenic influences might be responsible for the potential risk of adverse biological effects from TPH and heavy metals in Bohai Bay. PMID:24837025

Zhou, Ran; Qin, Xuebo; Peng, Shitao; Deng, Shihuai

2014-06-15

112

Mixing it Up: A Record of Holocene Climate Change in Non-Annually Laminated Sediment of Seneca Lake, NY  

Microsoft Academic Search

The mid to late Holocene climate record was examined in two cores that represent distal sedimentation in Seneca Lake, one of 11 Finger Lakes in western New York. Laminated sediments, ~5 m thick, were collected from the middle of the lake at 131-137 m water depths. These sites were selected because they preserve a continuous record of changes in the

C. E. Rogers; T. M. Curtin

2005-01-01

113

Simultaneous determination of arsenic, cadmium, copper, chromium, nickel, lead and thallium in total digested sediment samples and available fractions by electrothermal atomization atomic absorption spectroscopy (ET AAS).  

PubMed

This study describes the optimization and validation of a quick and simple method for the simultaneous determination of total content and available fractions of As, Cr, Cu, Ni, Pb and Tl in sediments by ET AAS, which has been proved to be useful for environmental research. The optimization was carried out using a 3(3) Box-Behnken factorial design which was applied to matrices of total digestion and to stages 1 and 2 of the modified BCR sequential extraction scheme for sediments in order to determine the appropriate atomization temperatures and masses for the chemical modifiers: Pd(NO(3))(2) and Mg(NO(3))(2). The simultaneous determination of the elements in all matrices considered was performed, without the use of chemical modifiers at atomization temperatures of 1700 °C for Cd and Tl, and 2100 °C for As, Cu, Cr, Ni and Pb, using a standard calibration curve for calibration purposes. The characteristic masses and limits of detection obtained were 36.5, 1.8, 6.5, 28, 34, 46.5 and 48 ?g and 0.11, 0.001, 0.022, 0.04, 0.2, 0.03 and 0.003 ?g g(-1) for As, Cd, Cr, Cu, Ni, Pb and Tl, respectively. The analytical procedure was validated by analyzing three sediment certified reference materials (CRM NCS DC 73315 and LKSD-4 for total content and BCR 701 for available fractions). Good accuracy was obtained (tested statistically, P=0.05, and shown by the high recovery for each element in each matrix), except for total As in the matrix of total digestion, where losses of the analyte could be attributed to sample treatment with HNO(3). The precision of the procedure was between 0.6% and 6%. PMID:22841115

Álvarez, María Á; Carrillo, Génesis

2012-08-15

114

Episodic Fan Dissection: Insights from Total Mercury Concentrations on Transport and Storage of Legacy Gold Mining Sediments in California  

Microsoft Academic Search

Nineteenth century hydraulic mining in the Sierra Nevada foothills of California displaced ~ 1.0 x 109 m3 of sediment, much of which constructed large tailings fans that linked up into valley-scale fans (e.g. Yuba fan) and graded into the Central Valley more than 50 km downstream. Additionally, ~4.0 x 106 kg of mercury used in gold separation was lost, leading

M. B. Singer; L. James; R. Aalto

2008-01-01

115

Modern and historical fluxes of halogenated organic contaminants to a lake in the Canadian arctic, as determined from annually laminated sediment cores.  

PubMed

Two annually laminated cores collected from Lake DV09 on Devon Island in May 1999 were dated using 210Pb and 137Cs, and analyzed for a variety of halogenated organic contaminants (HOCs), including polychlorinated biphenyls (PCBs), organochlorine pesticides, short-chain polychlorinated n-alkanes (sPCAs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polybrominated diphenyl ethers (PBDEs). Dry weight HOC concentrations in Lake DV09 sediments were generally similar to other remote Arctic lakes. Maximum HOC fluxes often agreed well with production maxima, although many compound groups exhibited maxima at or near the sediment surface, much later than peak production. The lower than expected HOC concentrations in older sediment slices may be due to anaerobic degradation and possibly to dilution resulting from a temporary increase in sedimentation rate observed between the mid-1960s and 1970s. Indeed, temporal trends were more readily apparent for those compound classes when anaerobic metabolites were also analyzed, such as for DDT and toxaphene. However, it is postulated here for the first time that the maximum or increasing HOC surface fluxes observed for many of the major compound classes in DV09 sediments may be influenced by climate variation and the resulting increase in algal primary productivity which could drive an increasing rate of HOC scavenging from the water column. Both the fraction (F(TC)) and enantiomer fraction (EF) of trans-chlordane (TC) decreased significantly between 1957 and 1997, suggesting that recent inputs to the lake are from weathered chlordane sources. PCDD/Fs showed a change in sources from pentachlorophenol (PeCP) in the 1950s and 1960s to combustion sources into the 1990s. Improvements in combustion technology may be responsible for the reducing the proportion of TCDF relative to OCDD in the most recent slice. PMID:15866277

Stern, G A; Braekevelt, E; Helm, P A; Bidleman, T F; Outridge, P M; Lockhart, W L; McNeeley, R; Rosenberg, B; Ikonomou, M G; Hamilton, P; Tomy, G T; Wilkinson, P

2005-04-15

116

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

USGS Publications Warehouse

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.

Juracek, K. E.

1998-01-01

117

Net and gross sedimentation in relation to the phosphorus budget of Eau Galle Reservoir, Wisconsin  

Microsoft Academic Search

We compared P retention with direct measures of Psedimentation, estimated fromsediment cores (annual P sedimentation) and sedimenttraps (daily P sedimentation),to quantify P sedimentation in Eau Galle Reservoir,Wisconsin. Mean annual Pretention was similar to mean annual P sedimentation,as estimated from sediment corerates integrated over the entire lake basin,indicating that annual P mass balanceapproximated annual net P sedimentation in thisreservoir. However, sediment

William F. James; John W. Barko

1997-01-01

118

Factors controlling temporal and spatial distribution of total mercury and methylmercury in hyporheic sediments of the Allequash Creek wetland, northern Wisconsin  

NASA Astrophysics Data System (ADS)

Hyporheic pore water samples were collected from two sites within the Allequash Creek wetland, in Vilas County, northern Wisconsin, from August 2003 to October 2004. Samples were collected simultaneously at the surface and at 2, 5, 7, 10, and 15 cm below the sediment-water interface. Concentration ranges were 3.7 to 58 pM for inorganic mercury, <0.5 to 16 pM for methylmercury, 3.02 to 152 ?M and 0.38 to 96.6 ?M for oxidized and reduced iron, respectively, 1.28 to 48.2 ?M and< 0.05 to 9.76 ?M for oxidized and reduced sulfur, respectively, and 109 to 689 ?M for dissolved organic carbon. These concentrations are typical of anoxic environments such as wetlands and lake sediments. These data were used to gain a better understanding of the processes controlling spatial and temporal variability of inorganic mercury and methylmercury. Findings show that conditions conducive to mercury methylation exist in the hyporheic zone, especially in late summer, when accumulation of reduced iron and sulfide are indicative of microbial iron and sulfate reduction. Methylmercury concentrations also peak in late summer, with the highest concentrations appearing 2 to 10 cm below the sediment-water interface. While there is a general covariance of total mercury and methylmercury over the depth profile, poor correlation was observed over time, highlighting the dynamic nature of hyporheic zone conditions and suggesting changes in mercury speciation and partitioning.

Creswell, Joel E.; Kerr, Sara C.; Meyer, Matthew H.; Babiarz, Christopher L.; Shafer, Martin M.; Armstrong, David E.; Roden, Eric E.

2008-06-01

119

Sediment transport by streams draining into the Delaware Estuary  

USGS Publications Warehouse

The quantity of sediment transported by streams draining into the Delaware estuary from Pennsylvania, New Jersey, and Delaware varies areally according to geology, physiography, and land use. Of the estimated total sediment load of 1.6 million tons entering the Delaware estuary annually, about 48 percent is contributed by the Delaware River main stem at Trenton, NJ; 34 percent by Pennsylvania tributaries; and 18 percent by New Jersey and Delaware tributaries.

Mansue, Lawrence J.; Commings, Allen B.

1974-01-01

120

Annual course of sediment parameters and meiofauna on a sandy tidal flat in the wadden sea after the severe winter of 1995/96  

NASA Astrophysics Data System (ADS)

Local abiotic and biotic data are presented from the Gröninger Plate (a sandy tidal flat south of Spiekeroog Island) covering a period of one year (February 1996 — February 1997), which includes the coldest part of the ice winter of 1995/96 as well as the winter of 1996/97. The thickness of the visible oxidized layer revealed a clear seasonality. Regarding sandy sediments, values were generally low and ranged between 2.9 cm in winter and 0.9 cm in summer. Biotic and abiotic data are restricted to composition and abundance of meiofauna taxa, total organic carbon, Chl a and phaeopigments as well as temperature and salinity. A significant reduction of meiofaunal abundance, particularly of nematodes, in the top 2 cm was recorded in samples taken in sediments covered by ice, as compared to sediments without an ice cover. However, vertical distribution of meiofauna under ice cover showed that nematodes had migrated to deeper sediment layers. The meiofauna appeared to have overcome the stress of low temperatures and ice formation better than the macrofauna.

Neira, Carlos; Höpner, Thomas; Rackemann, Michael

1998-12-01

121

Annual and seasonal temperature variance along an inter-tidal sediment transect in Yaquina bay, Oregon, 1999 - 2006  

EPA Science Inventory

Sediment temperature was measured using submersible Onset TidbiT® recording thermistor thermometers at eelgrass (Zostera marina, Z. japonica) mid-rhizome root depth (~5 cm) at 6 stations on a transect from ~MLLW (mean lower low water) at the channel edge to near MHHW (mean higher...

122

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...

123

Effects of different soil management practices on total P and Olsen-P sediment loss: A field rainfall simulation study  

Microsoft Academic Search

Field rainfall simulations were conducted in 2002 and 2005 to study the effects of different soil management practices on the total phosphorous (TP) and Olsen-P losses by soil erosion and redistribution along a 15 m long slope in Luoyang, Henan province, China. Field plots were set up in 2001 and included the following soil management practices: subsoiling with mulch (SSM), no-till

K. Jin; W. M. Cornelis; W. Schiettecatte; J. J. Lu; D. X. Cai; J. Y. Jin; S. De Neve; R. Hartmann; D. Gabriels

2009-01-01

124

The pollen season dynamics and the relationship among some season parameters (start, end, annual total, season phases) in Kraków, Poland, 1991-2008.  

PubMed

The dynamics of 15 taxa pollen seasons in Kraków, in 1991-2008 was monitored using a Burkard volumetric spore trap of the Hirst design. The highest daily pollen concentrations were achieved in the first half of May, and they were caused mainly by Betula and Pinus pollen. The second period of the high concentrations took place from the middle of July to the end of August (mainly Urtica pollen). Tree pollen seasons were shorter (18-24 days) in comparison with the most herbaceous pollen seasons (73-89 days), except at Artemisia and Ambrosia seasons (30 and 24 days, respectively). The season phases (percentyles) of the spring and late-summer taxa were the most variable in the consecutive years. The highest annual sums were noted for Urtica, Poaceae (herbaceous pollen seasons) and for Betula, Pinus, Alnus (tree pollen seasons), and the highest variability of annual totals was stated for Urtica, Populus, Fraxinus and the lowest for Ambrosia, Corylus, Poaceae. For the plants that pollinate in the middle of the pollen season (Quercus, Pinus and Rumex), the date of the season start seems not to be related to the season end, while for late pollen seasons, especially for Ambrosia and Artemisia, the statistically negative correlation between the start and the end season dates was found. Additionally, for the most studied taxa, the increase in annual pollen totals was observed. The presented results could be useful for the allergological practice and general botanical knowledge. PMID:21892249

Myszkowska, D; Jenner, B; St?palska, D; Czarnobilska, E

2011-09-01

125

Mixing it Up: A Record of Holocene Climate Change in Non-Annually Laminated Sediment of Seneca Lake, NY  

NASA Astrophysics Data System (ADS)

The mid to late Holocene climate record was examined in two cores that represent distal sedimentation in Seneca Lake, one of 11 Finger Lakes in western New York. Laminated sediments, ~5 m thick, were collected from the middle of the lake at 131-137 m water depths. These sites were selected because they preserve a continuous record of changes in the hydrologic balance and sedimentary processes. Variations in grain size and fabric at 50-100-cm intervals were observed and represent time periods of hundreds to thousands of years. The combination of magnetic susceptibility, loss-on-ignition, grain size analysis by laser diffraction, and grain fabric analysis using thin sections allow us to reconstruct the evolution of the lake since deglaciation and to compare and contrast paleoclimate indicator data. Variations in the type of sedimentary fabrics preserved are coincident with variations in geochemical and sedimentological indicators of environmental conditions that may have occurred in response to fluctuations in the hydrologic balance and circulation and/or overturn. Laterally continuous, thin, black laminae rich in organic matter and possibly minute grains of iron sulfides accumulated during the mid Holocene Hypsithermal (~9-7 ka). Presence of black laminae may signify a steady supply of organic matter and an absence of oxygen, at least below the sediment-water interface if not in the lower part of the water column. Coincident with finely laminated sediment are the coarsest mean grain sizes. Three 2-6 cm thick sand beds occur in one core, suggesting that an influx of water and sediment occurred during intense storms. A combination of warmer surface water and influx of freshwater from storms during the Hypsithermal may have influenced the turnover history of the lake by stabilizing the water column. Absence of overturn would result in depletion of nutrients in surface waters, a decrease in primary productivity, and a decrease in oxygen at the bottom of the lake as a result of decaying organic matter. The presence of thicker, undisrupted black laminae (with iron sulfides) in both cores during this interval supports this hypothesis. Homogeneous, disrupted, or peloidal-rich laminae may have formed as a result of reworking by a combination of bottom currents and burrowing during the late Hypsithermal and Neoglacial (~7 ka-present). Cooler surface air temperatures and an associated southward shift in the jet stream likely changed the stratification history of the lake. If, during the winter months, the lake water circulates freely but stratifies during the summer, mixing of sediment may have occurred during the winter. Laminae would not be well-preserved in this scenario. Previous work shows that selective truncation of early Holocene sediment in shallower depths of Seneca Lake may reflect a change to dynamic atmospheric and lake circulation at during the end of the Hypsithermal and during the Neoglacial in response to cooler atmospheric temperatures and supports our working model for the degree of formation and preservation of laminae in Seneca Lake.

Rogers, C. E.; Curtin, T. M.

2005-12-01

126

Heart rate, respiration and total oxyradical scavenging capacity of the Arctic spider crab, Hyas araneus, following exposure to polycyclic aromatic compounds via sediment and injection.  

PubMed

Increasing industrial activity in the European Arctic has raised concerns of the potential anthropogenic impact of chemicals on this polar marine ecosystem. For the past 20 years or so, biomarkers have been developed to provide early-warning signals of detrimental impacts of chemicals on the marine ecosystem, however, most biomarker methods have been established for organisms living in temperate rather than polar waters. Little is known about biomarker responses in organisms living within the temperature range of -1.88 to +5 degrees C. In this study, established biomarkers from temperate studies were tested on the Arctic spider crab Hyas araneus to validate their use in polar ecosystems. H. araneus is common in Svalbard fjord (Norway), although it is a temperate water species occurring from northern Spain to Svalbard at depths from 10 to 1200 m. In this paper, the effects of oil were investigated at 2 degrees C via two routes: (i) injection and (ii) contaminated sediment. After 2 weeks of exposure, heart rate, oxygen consumption and total oxyradical scavenging capacity (TOSC) were measured in the same individuals. In both methods of contaminant exposure, heart rate showed a significant increase compared with the control (P < 0.0001, n = 7); mean heart rate values (+/- S.D.) of H. araneus were 49.06 (+/- 13.72), 57.56 (+/- 7.28) and 63.30 (+/- 6.57) beats per minute in control, injected and sediment-treated groups, respectively. Respiration of H. araneus was not affected significantly by either oil treatment (P > 0.05), but two individuals (n = 8) showed a marked increase in oxygen uptake in the sediment-exposed group. The basal oxygen consumption of control H. araneus was lower (0.025 mg O(2) g wet wt.(-1) h(-1)) than reported for H. araneus living in temperate water. Although TOSC of H. araneus was not affected significantly by either exposure treatment (P > 0.05) the mean TOSC value in the sediment-exposed group was lower than the control, indicating some saturation of the oxyradical scavenging system. Results indicate that although low temperature appears to be the main factor reducing the bioavailability of polycyclic-aromatic hydrocarbons, the relatively low metabolic rate of Arctic H. araneus is also implicated in decreased uptake and metabolism of oil compounds into reactive oxygen species (ROS). PMID:12297367

Camus, L; Jones, M B; Børseth, J F; Regoli, F; Depledge, M H

2002-11-13

127

Erosion and sediment transport in the Ganges river basin (India)  

NASA Astrophysics Data System (ADS)

Based on sampling of the entire region of the Ganges basin, chemical and sediment load supplied at various parts of the basin have been computed. Annual flux of materials from sub-basin into the main basin and input to the Hoogly estuary have been calculated and compared to major river systems of the world. The total annual load at Calcutta (mouth of the river) was calculated as 411 · 10 6 t (328 · 10 6 t sediment load + 83 · 10 6 t chemical load). Erosion rate (549 t km -2 yr. -1) is among the highest in this river system and controlling factors on a global scale, such as basin area, are discussed in detail. Annual decrease in basin elevation indicates a rapid process of denudation and such rates have a bearing on rates of shelf sediment accumulation.

Abbas, Nazar; Subramanian, V.

1984-02-01

128

MOVEMENT OF TRACTIVE SEDIMENT FROM DISTURBED LANDS.  

USGS Publications Warehouse

The Smoky Creek basin of the coal area of northeastern Tennessee shows extensive evidence of tractive movement of coarse sediment from mined tributary basins into the main channel. Coal-rich gravel bars and flood-plain debris are common below tributaries. Using a combination of techniques including channel-geometry and bar measurements, sediment sampling for rock-debris and coal size distributions, and botanical dating of flood events and geomorphic features, an average annual yield of 65 metric tons per square kilometer (187 tons per square mile) for tractively moved sediment has been calculated for the period 1977 to 1982. This value, 8 percent of the total sediment load, is probably an underestimate owing to the method of calculation. Slightly more than half of the traction load is coal, which moves through the basin within a few years. Rock debris, however, appears to require years to decades to move similar distances.

Osterkamp, W. R.; Carey, W. P.; Hupp, C. R.; Bryan, B. A.

1984-01-01

129

Correlations between speciation of Cd, Cu, Pb and Zn in sediment and their concentrations in total soft tissue of green-lipped mussel Perna viridis from the west coast of Peninsular Malaysia  

Microsoft Academic Search

Total concentrations and speciation of cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) in surface sediment samples were correlated with the respective metal measured in the total soft tissue of the green-lipped mussel Perna viridis, collected from water off the west coast of Peninsular Malaysia. The aim of this study is to relate the possible differences in the accumulation

C. K. Yap; A. Ismail; S. G. Tan; H. Omar

2002-01-01

130

Late Quaternary climates of East Asia deduced from the total organic carbon contents of cored sediments (MD179-3304, 3312) off Joetsu City, Japan Sea  

NASA Astrophysics Data System (ADS)

Total organic carbon (TOC) and total nitrogen (TN) concentrations are analyzed with high temporal resolution (ca. 100 years) for cores MD179-3304 and MD179-3312 taken from the Japan Sea off Joetsu City. The temporal changes in TOC and TN concentrations vary quasi-regularly in similar patterns. The age models are formed on the basis of the dates of 14C dating, marker tephra beds, TL layers, and marine isotope events with depth. TOC concentration is high in MIS 1 and 5, low in MIS 2 and 4, and slightly elevated in MIS 3 with frequent short fluctuations. This general trend is very similar to LR04 curve, except for the reduced dominance of TOC around the MIS 5.5 substage. As shown typically in MIS 3, there are many peaks of TOC in a short interval. The details of these TOC peaks can be correlated with the warm interstadials of the Greenland ice core. We can identify a sawtooth-like decreasing trend of TOC in MIS 3. In contrast, the decreasing trend of ?18O in the ice core corresponds to an increasing trend of TOC in MIS 5. The most plausible explanation for the correlation of climate changes between East Asia and the North Atlantic is oscillation of the Arctic polar front through time. The detailed correspondence of TOC concentrations of the Japan Sea sediments to other common paleoclimate proxies means that the TOC concentrations of these sediments is an excellent paleoclimate record in Far East Asia, although the genetic relationship between air temperature and biological productivity in the Japan Sea is as yet unknown.

Urabe, Tasuku; Kuriyama, Manato; Matsumoto, Ryo; Kumon, Fujio

2014-08-01

131

Sediment transport in the Burhi Dining River India  

Microsoft Academic Search

ABSTRACT The Burhi,Dining,is a tributary,of the,Brahmaputra,River,in north-east,India.,The basin,covers,an area,of 6000 km2and,receives about,300 cm average,annual,rainfall.,Data on suspended,sediment,of the river,span,the,period,from,1972 to 1982. Higher,concentration,of sediment,occurs,from,April,to October.,The highest,concentration,that has,been,measured,so far,is 1.19 gm 1 ~\\\\ The,suspended,sediment,load,is generally,higher,in the,rising,limb,of the,flood,hydrograph,as compared to the,recession,limb.,The sediment-rating,curve,shows,a highly positive,correlation,between,the,sediment,load,and,the,water,discharge. The heaviest,loads,of sediment,are,related,to sudden,flash,floods.,The mean,annual,sediment,load,is 3 620 000 tons;,33 percent of the,annual total,is transported,in the,month,of July.,Duration-curve,analysis shows,that,in some,years,it took,only,25 days

J. n. Sarma

132

The benthic silica cycle in the Northeast Atlantic: annual mass balance, seasonality, and importance of non-steady-state processes for the early diagenesis of biogenic opal in deep-sea sediments  

NASA Astrophysics Data System (ADS)

Within the framework of the EU-funded BENGAL programme, the effects of seasonality on biogenic silica early diagenesis have been studied at the Porcupine Abyssal Plain (PAP), an abyssal locality located in the northeast Atlantic Ocean. Nine cruises were carried out between August 1996 and August 1998. Silicic acid (DSi) increased downward from 46.2 to 213 ?M (mean of 27 profiles). Biogenic silica (BSi) decreased from ca. 2% near the sediment-water interface to <1% at depth. Benthic silicic acid fluxes as measured from benthic chambers were close to those estimated from non-linear DSi porewater gradients. Some 90% of the dissolution occurred within the top 5.5 cm of the sediment column, rather than at the sediment-water interface and the annual DSi efflux was close to 0.057 mol Si m -2 yr -1. Biogenic silica accumulation was close to 0.008 mol Si m -2 yr -1 and the annual opal delivery reconstructed from sedimentary fluxes, assuming steady state, was 0.065 mol Si m -2 yr -1. This is in good agreement with the mean annual opal flux determined from sediment trap samples, averaged over the last decade (0.062 mol Si m -2 yr -1). Thus ca. 12% of the opal flux delivered to the seafloor get preserved in the sediments. A simple comparison between the sedimentation rate and the dissolution rate in the uppermost 5.5 cm of the sediment column suggests that there should be no accumulation of opal in PAP sediments. However, by combining the BENGAL high sampling frequency with our experimental results on BSi dissolution, we conclude that non-steady state processes associated with the seasonal deposition of fresh biogenic particles may well play a fundamental role in the preservation of BSi in these sediments. This comes about though the way seasonal variability affects the quality of the biogenic matter reaching the seafloor. Hence it influences the intrinsic dissolution properties of the opal at the seafloor and also the part played by non-local mixing events by ensuring the rapid transport of BSi particles deep into the sediment to where saturation is reached.

Ragueneau, O.; Gallinari, M.; Corrin, L.; Grandel, S.; Hall, P.; Hauvespre, A.; Lampitt, R. S.; Rickert, D.; Stahl, H.; Tengberg, A.; Witbaard, R.

133

Cumulative sediment trapping by reservoirs in large river basins: A case study of the Yellow River basin  

NASA Astrophysics Data System (ADS)

Reservoir sedimentation has been a serious problem for reservoir operation and watershed management worldwide, which highlights the importance of accurate estimate of the deposited sediment amount. With reservoir information derived from remote sensing dataset and observed hydrological records of water and sediment, this paper is concerned with the cumulative reservoir sediment trapping in the Yellow River basin. The river basin was divided into 12 sub-basins, upon which the reservoirs' sediment trapping efficiency (TE) and their interception effects on inflowing sediment were estimated with sediment records extracted from 179 field sampling stations. The results show that, with the sediment TE greater than 80% for all the sub-basins, theoretically the basin-wide reservoirs are able to trap most sediment. For the whole river basin, the sediment TE averages 95.2%, which indicates that the reservoirs can collectively make a significant anthropogenic signature on basin-wide sediment delivery. A basin-wide sediment yield map was generated to estimate the reservoir sedimentation amount. During 1950-1970, annually about 2.483 Gt of sediment was transported into channels from sloping lands. Taking into account the actual water storage changes and the reservoir construction history, the actual reservoir sedimentation rate was estimated at 0.59 Gt/yr after corrections, which represents 47.6% of the river basin's total sediment load reduction. Globally, reservoir sedimentation in the Yellow River basin represents about 12-15% of the global mean rate. Up to 2010, approximately 19.32 Gt of sediment has been trapped by Yellow River reservoirs, and totally about 40.32 Gt of sediment has been artificially fixed if silt check dams are also considered. With huge amounts of sediment deposited, these reservoirs have been losing their storage capacity to sedimentation at a rate of 0.6% per year. The magnitude is expected to enhance in future following new reservoir completions. Thus, more efforts are strongly needed to explore the associated responses.

Ran, Lishan; Lu, X. X.; Xin, Zhongbao; Yang, Xiankun

2013-01-01

134

Status report and FY95 plans -- Re-evaluation of NOAA Dobson spectrophotometer total ozone data. 1994 annual report  

SciTech Connect

The goal of this project was to re-evaluate NOAA/CMDL Dobson spectrophotometer total ozone data during FY94 from the stations Haute Provence, France; Lauder, New Zealand; Perth, Australia; and Poker Flat, Alaska and the Umkehr data from Boulder, Colorado and Mauna Loa, Hawaii. During the second year the authors planned to re-evaluate total ozone data from Byrd, Hallett and South Pole, Antarctica; Fairbanks, Alaska; Puerto Montt, Chile; Huancayo, Peru and Umkehr data from Huancayo.

NONE

1994-12-31

135

High Suspended Sediment Yields of the Conestoga River Watershed to the Susquehanna River and Chesapeake Bay are the Result of Ubiquitous Post-Settlement Mill Dams  

Microsoft Academic Search

The Conestoga River watershed of Lancaster County, Pennsylvania constitutes 1.7% of the total area of the Susquehanna River basin and drains mostly Piedmont Province with very low relief and hillslope gradients, yet it contributes the largest annual suspended sediment yield of any tributary in the basin. Nearly one-third of the Susquehanna's sediment is deposited in the northern Chesapeake Bay, causing

D. Merritts; R. Walter; C. Lippincott; S. Siddiqui

2004-01-01

136

Sedimentation and Occurrence and Trends of Selected Nutrients, Other Chemical Constituents, and Diatoms in Bottom Sediment, Fall River Lake, Southeast Kansas, 1948-2006  

USGS Publications Warehouse

A combination of available bathymetric-survey information and bottom-sediment coring was used to investigate sedimentation and the occurrence of selected nutrients (total nitrogen and total phosphorus), organic and total carbon, 25 trace elements, diatoms, and the radionuclide cesium-137 in the bottom sediment of Fall River Lake, southeast Kansas. The total estimated volume and mass of bottom sediment deposited from 1948 through 2006 in the original conservation pool of the reservoir was 470 million cubic feet and 18.8 billion pounds, respectively. The estimated sediment volume occupied about 36 percent of the original conservation-pool, water-storage capacity of the reservoir. Mean annual net sediment deposition since 1948 in the original conservation pool of the reservoir was estimated to be 324 million pounds per year. Mean annual net sediment yield from the Fall River Lake Basin was estimated to be 585,000 pounds per square mile per year. The mean annual net loads of total nitrogen and total phosphorus deposited in the bottom sediment of Fall River Lake were estimated to be 648,000 pounds per year and 267,000 pounds per year, respectively. The estimated mean annual net yields of total nitrogen and total phosphorus from the Fall River Lake Basin were 1,170 pounds per square mile per year and 480 pounds per square mile per year, respectively. Throughout the history of Fall River Lake, total nitrogen and total phosphorus concentrations in the deposited sediment were relatively uniform. Trace element concentrations in the bottom sediment of Fall River Lake generally were uniform over time. Arsenic, chromium, nickel, and zinc 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. Diatom occurrence in the bottom sediment of Fall River Lake was dominated by the species Aulacoseira granulata, which is an indicator of eutrophic (nutrient-rich) conditions. The abundance of the diatom Aulacoseira granulata, combined with cyanobacteria evidence and historical water-quality data, indicated that Fall River Lake likely has been eutrophic throughout much of its history.

Juracek, Kyle E.

2008-01-01

137

Aggregation of Selected Three-Day Periods to Estimate Annual and Seasonal Wet Deposition Totals for Sulfate, Nitrate, and Acidity. Part II: Selection of Events, Deposition Totals, and Source Receptor Relationships.  

NASA Astrophysics Data System (ADS)

A method for deriving estimates of long-term acidic deposition over eastern North America based on a limited number of Regional Acid Deposition Model runs has been developed. The main components of this method are the identification of a representative sample of events for model simulation and the aggregation of the deposition totals associated with the events. Meteorological categories, defined according to 3-day progressions of 850-mb wind flow over eastern North America, were used to guide the selection of events. This paper describes how events were selected from the categories and how they were combined (aggregated) to estimate long-term deposition. The effectiveness of the category-based approach was compared against alternate aggregation approaches and it was found to provide the best sample-based estimates of long-term wet sulfate deposition across eastern North America.Thirty events from the 1982 85 time period were selected using a set of predetermined criteria and aggregated to estimate seasonal and annual SO24, NO3, and H+ deposition at 20 Utility Acid Precipitation Study Program sites. The accuracy of the estimates varied geographically and depending upon whether they were for the annual or seasonal time periods. Over the main area of interest (a smaller 13-site region), the mean rms errors for annual deposition were 10%, 15%, and 12% for sulfate, nitrate, and acidity, respectively. Source receptor relationships associated with the 30 events were examined for three sites located in Michigan, North Carolina, and upstate New York. It was found that the amount of time that transport was to these areas from the U.S. Midwest (an area of high SO2 emissions) was represented to within 20%.

Brook, Jeffrey R.; Samson, Perry J.; Sillman, Sanford

1995-02-01

138

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

ERIC Educational Resources Information Center

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…

Schwabe, Robert A.

139

Solar Total Energy Project, Shenandoah, Georgia site. Annual technical progress report, July 1, 1982-June 30, 1983  

SciTech Connect

A part of the National Solar Thermal Energy Program, initially funded by DOE, the Shenandoah Project, is the world's largest industrial application of the solar total energy concept. The objective of the Project is to evaluate a solar total energy system that provides electrical power, process steam, and air conditioning for a knit-wear factory (operated by Bleyle of America, Inc.). During normal operation, solar energy generates a large part of the electricity and displaces part of the fossil fuels normally used to run the factory and produce the clothing. Construction of the system was completed early in 1982, when operations were initiated. Solution of unexpected electrical and mechanical problems produced significant information for subsequent system designs. An overview of the Project and a brief System Description is presented following a chronological summary of progress. A discussion of varius anomalies, together with subsequent high quality solar and thermodynamic system performance results, is then discussed.

Not Available

1983-01-01

140

Interhemispheric ratio and annual cycle of carbonyl sulfide (OCS) total column from ground-based solar FTIR spectra  

Microsoft Academic Search

We have made extensive measurements of total column OCS by ground-based high- resolution solar Fourier transform infrared absorption spectroscopy from two southern hemisphere sites to complement earlier measurements in the northern hemisphere and to investigate the interhemispheric ratio, variability, and seasonal cycles of OCS in the atmosphere. The measurements were made at Lauder, New Zealand (45.0øS, 169.7øE, 370 rn asl,

David W. T. Griffith; Nicholas B. Jones; W. Andrew Matthews

1998-01-01

141

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

USGS Publications Warehouse

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)

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

1978-01-01

142

A three-band semi-analytical model for deriving total suspended sediment concentration from HJ-1A/CCD data in turbid coastal waters  

NASA Astrophysics Data System (ADS)

The accurate assessment of total suspended sediment (TSM) concentration in coastal waters by means of remote sensing is quite challenging, due to the optical complexity and significant variability of these waters. In this study, three-band semi-analytical TSM retrieval (TSTM) model with HJ-1A/CCD spectral bands was developed for the retrieval of TSM concentration from turbid coastal waters. This model was calibrated and validated by means of one calibration dataset and three independent validation datasets obtained from three different turbid waters. It was found that the TSTM model may be used to retrieve accurate TSM concentration data from highly turbid waters without the spectral slope of the model requiring further optimization. Finally, the TSM concentration data were quantified from the HJ-1A/CCD images after atmospheric correction using the dark-object subtraction technique. Upon comparing the model-derived and field-measured TSM concentration data, it was observed that the TSTM model produced <29% uncertainty in deriving TSM concentration from the HJ-1A/CCD data. These findings imply that the TSTM model may be used for the quantitative monitoring of TSM concentration in coastal waters, provided that the atmospheric correction scheme for the HJ-1A/CCD imagery is available.

Chen, Jun; Cui, Tingwei; Qiu, Zhongfeng; Lin, Changsong

2014-07-01

143

Sediment discharge in the Upper Arroyo Grande and Santa Rita Creek basins, San Luis Obispo County, California  

USGS Publications Warehouse

Sediment data collected in the upper Arroyo Grande and Santa Rita Creek basins, San Luis Obispo County, California, during the 1968-73 water years were analyzed to determine total sediment discharge at four stations in the basins. Water discharge and total sediment discharge at these stations, representative of the 1943-72 period, were estimated from long-term flow data for nearby gaging stations and water-sediment discharge relations determined for the 1968-73 water years. Most of the total annual sediment discharge at each station occurs during a few days each year. The quantity of sediment transported in a single day often accounts for more than 40 percent of the total annual sediment discharge. Estimated sediment discharge for the upper Arroyo Grande and Santa Rita Creek basins during the 1943-72 water years averaged 53,000 tons and 23,000 tons per year. Long-term sediment deposition in Lopez Reservoir, which is in the southern part of the upper Arroyo Grande basin, was estimated to be 35 acre-feet per year. (Woodard-USGS)

Knott, J. M.

1976-01-01

144

Pinpointing the key parameters that control the errors in estimating the total-load sediment flux using sand particles measured data in reservoir engineering  

Microsoft Academic Search

Sediment deposition is the principal problem affecting the useful life of reservoirs. Knowledge of both the rate and pattern of sediment deposition in a reservoir is required to predict the types of service impairments which will occur, the time frame in which they will occur, and the types of remedial strategies which may be practicable. The present analysis details the

Saeed Khorram; Mostafa Jafari

2010-01-01

145

Hydroclimatic control of sediment and metal export from a rural catchment in Northwest Spain  

NASA Astrophysics Data System (ADS)

This paper examines sediment and metal (Al, Fe, Mn, Cu, and Zn) exportation at different time scales (annual, seasonal and event) during a three-year period (2005-2008) in the Mero River headwater, a rural catchment under humid temperate climate. Inter-annual differences were found both in annual loads and their distributions throughout the year. At annual scale, sediment and particulate metal loads followed the same trend as streamflow, while dissolved metals showed different patterns. Runoff events contributed to 63% of the total sediment load, whereas particulate and dissolved metal loads accounted for between 38-61 and 27-49% of the total load, respectively. Runoff events were characterized by high variability in sediment and metal loads, a few events representing a high percentage of the metal exported. Sediment loads were related to maximum and initial discharge. Particulate metal loads were highly correlated with sediment loads, runoff being the hydrological variable that best explains the load of these metals. Dissolved metal loads displayed different patterns. Dissolved Al, showed a great correlation with runoff, while dissolved Mn with maximum discharge.

Palleiro, L.; Rodríguez-Blanco, M. L.; Taboada-Castro, M. M.; Taboada-Castro, M. T.

2014-04-01

146

The Eighth Annual NASA/Contractors Conference and 1991 National Symposium on Quality and Productivity: Extending the boundaries of total quality management  

NASA Technical Reports Server (NTRS)

The Eighth Annual NASA/Contractors Conference and 1991 National Symposium on Quality and Productivity provided a forum to exchange knowledge and experiences in these areas of continuous improvement. The more than 1,100 attendees from government, industry, academia, community groups, and the international arena had a chance to learn about methods, tools, and strategies for excellence and to discuss continuous improvement strategies, successes, and failures. This event, linked via satellite to concurrent conferences hosted by the NASA Goddard Space Flight Center in Greenbelt, Maryland, and Martin Marietta Astronautics Group in Denver, Colorado, also explored extending the boundaries of Total Quality Management to include partnerships for quality within communities and encouraged examination, evaluation, and change to incorporate the principles of continuous improvement.

Templeton, Geoffrey B. (editor); Stewart, Lynne M. (editor); Still, William T. (editor)

1992-01-01

147

Suspended-sediment loads from major tributaries to the Missouri River between Garrison Dam and Lake Oahe, North Dakota, 1954-98  

USGS Publications Warehouse

Annual suspended-sediment loads for water years 1954 through 1998 were estimated for the major tributaries in the Missouri River Basin between Garrison Dam and Lake Oahe in North Dakota and for the Missouri River at Garrison Dam and the Missouri River at Bismarck, N. Dak. The major tributaries are the Knife River, Turtle Creek, Painted Woods Creek, Square Butte Creek, Burnt Creek, Heart River, and Apple Creek. Sediment and streamflow data used to estimate the suspended-sediment loads were from selected U.S. Geological Survey streamflow-gaging stations located within each basin. Some of the stations had no sediment data available and limited continuous streamflow data for water years 1954 through 1998. Therefore, data from nearby streamflow-gaging stations were assumed for the calculations.The Heart River contributed the largest amount of suspended sediment to the Missouri River for 1954-98. Annual suspended-sediment loads in the Heart River near Mandan ranged from less than 1 to 40 percent of the annual suspended-sediment load in the Missouri River. The Knife River contributed the second largest amount of suspended sediment to the Missouri River. Annual suspended-sediment loads in the Knife River at Hazen ranged from less than 1 to 19 percent of the annual suspended-sediment load in the Missouri River. Apple Creek, Turtle Creek, Painted Woods Creek, Square Butte Creek, and Burnt Creek all contributed 2 percent or less of the annual suspended-sediment load in the Missouri River. The Knife River and the Heart River also had the largest average suspended-sediment yields for the seven tributaries. The yield for the Knife River was 91.1 tons per square mile, and the yield for the Heart River was 133 tons per square mile. The remaining five tributaries had yields of less than 24 tons per square mile based on total drainage area.

Macek-Rowland, Kathleen M.

2000-01-01

148

Impacts of soil-water conservation in Jialing River on sedimentation of the Three Gorges Reservoir  

Microsoft Academic Search

The Jialing River is one of the main tributaries of the Yangtze River. The average annual runoff accounts for 16% and the\\u000a sediment load 26% of the total at Yichang therefore it's one of the main contributors of sediment to the Three Gorges Reservoir.\\u000a Ever since 1989, our country has implemented “Yangtze River soil and water conservation” project, Till the

Lei Xiaozhang; Cao Shuyou; Jiang Xiaohua

2006-01-01

149

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

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

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

2002-01-01

150

Fluvial sedimentation in Kentucky  

USGS Publications Warehouse

Covering periods 1942-45 and 1951-81, this report documents the characteristics of sediments being transported from 79 drainage areas within the Commonwealth of Kentucky, and from eight stations on the main stem of the Ohio River. The drainage areas range in size from 0.67 square mile at Cane Branch near Parkers Lake to 40,330 square miles at Tennessee River near Paducah. Sediment yields and particle size of suspended and bed sediments are discussed by physiographic province. The Blue Grass had the highest average annual suspended-sediment yield for selected stations of 741 tons per square mile, and the Western Coal Field had the lowest with 197. The Eastern Coal Field had the broadest range of annual suspended-sediment yields. The range was from 25 tons per square mile at Helton Branch near Greenwood to 21,000 tons per square mile at Millers Creek near Phyllis. For selected stations bedload discharge was estimated to be 5 to 10 percent as much as the suspended-sediment discharge. Only three drainage areas had sediment yields that exceeded the average annual erosion rates for cultivated land in Kentucky of 9.93 tons per acre (6,355 tons per square mile). These three were in the Eastern Coal Field. (USGS)

Flint, R. F.

1983-01-01

151

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

PubMed Central

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.

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

1982-01-01

152

SUSPENDED-SEDIMENT TRANSPORTS FLOWING INTO TOKYO BAY WITH A SS MONITORING NETWORK  

NASA Astrophysics Data System (ADS)

For comprehensive management of sediments of inner bays, it is important to understand the suspended-sediment transports from the watershed through rivers flowing into inner bays. However the sediment transport have not been understood especially under flood-flow conditions due to few continuous monitoring data for suspended sediment transports. For this purpose, we have installed turbidity sensors in the influent rivers into Tokyo Bay to continuously monitor SS trasnports. The observed results indicate that the coefficient b in sediment rating curve (L=aQb) are closely related to land use of the watershed. Total SS transports flowing into Tokyo Bay were annually 0.6 - 2.5*106 ton. The SS trasnports in Edogawa, Arakawa and Tamagawa Rivers are 66 % of total SS transports.

Tanaka, Kentaro; Nihei, Yasuo

153

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

NASA Astrophysics Data System (ADS)

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.

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

2009-08-01

154

Streamflow and sediment transport in the Quillayute River basin, Washington  

USGS Publications Warehouse

From October 1976 to September 1978 the U.S. Geological Survey made a reconnaissance evaluation of the fluvial-sediment transport and documented the natural streamflow characteristics in the Quillayute River basin in northwestern Washington. Most of the flow originates from the tributaries, the Soleduck, Bogachiel, and Calawah Rivers. Flow in the summer months from the Calawah River is about half that from either the Bogachiel or Soleduck Rivers. In the winter months flow from the Soleduck River is about 1 1/2 times that of the Bogachiel or Calawah Rivers. In general, the highest monthly flows during the winter are about 10 times greater than the lowest monthly flows during the summer except for the Dickey River where winter flows are about 20 times greater. Annual mean discharges may vary greatly from year to year, ranging from about 1/2 to 1 1/2 times the mean annual discharge. For the study period, the observed suspended-sediment concentration ranged from less than 1 to 2 ,150 milligrams per liter. The estimated mean annual suspended-sediment discharges were: Bogachiel River--400,000 tons (includes Calawah River); Calawah River--120,000 tons; Soleduck River--120,000 tons; Dickey River--75,000 tons; and other tributaries--10,000 tons, for a total of 606,000 tons transported annually by the Quillayute River. The estimated annual bedload of 21,000 tons was transported into the Quillayute River by the Soleduck, Bogachiel, and Dickey Rivers. (USGS)

Nelson, L. M.

1982-01-01

155

Interim report on streamflow, sediment discharge, and water quality in the Calabazas Creek Basin, Santa Clara County, California  

USGS Publications Warehouse

Streamflow, sediment-discharge, and water-quality data are being collected in the Calabazas Creek basin, Santa Clara County, Calif., to determine annual water and sediment discharge at base-line conditions that are representative of a basin prior to urbanization. Results of the first 3 years of the study (1973-75) are given in this report. Climatic conditions during this period were representative of a very wet year (1973) and 2 years of above-average rainfall (1974 and 1975). Daily water and sediment discharge were monitored at three primary stations, and periodic measurements were made at five secondary stations during selected storms. Most of the total annual sediment discharge at each station was transported during a few days each year. Maximum daily sediment discharge in a given year ranged from 23 to 62 percent of the annual total. Daily water discharge at the gaging station Calabazas Creek at Rainbow Drive, near Cupertino, ranged from no flow to 3.31 cubic meters per second. Streamflow at this location was significantly augmented during low flow by diversion of water from the South Bay Aqueduct. Annual sediment discharge at Calabazas Creek at Rainbow Drive was 4,900 t in 1974 and 9,570 t in 1975. A large quantity of sediment was trapped in a debris basin at Comer Drive upstream from this station during both years. If this sediment had not been trapped, sediment discharge at the station would have been about 35 percent greater in 1974 and 30 percent greater in 1975. Most of the trapped sediment consists of sand and gravel that would probably have been deposited in the Calabazas Creek channel downstream from the station. (Woodard-USGS)

Knott, J. M.; Pederson, G. L.; Middelburg, Robert F.

1978-01-01

156

Response of total belowground carbon flux and soil organic carbon storage to increasing mean annual temperature in Hawaiian tropical montane wet forest.  

NASA Astrophysics Data System (ADS)

Controls on the allocation of carbon belowground by plants and the retention of this carbon as new soil organic carbon are poorly quantified, yet exert a large influence on the carbon balance of the terrestrial biosphere. While many studies have now quantified total belowground carbon flux (TBCF), and general global patterns have been identified, rigorous field tests of the effects of climate variables on TBCF do not yet exist, and the conversion of TBCF into soil organic carbon - particularly long-lived soil organic carbon - has received little attention. These represent critical gaps in our understanding of terrestrial carbon cycling, and currently severely constrain efforts to model climate change impacts on belowground carbon processes and storage. We have established a model mean annual temperature gradient spanning 5.2°C in Hawaiian tropical montane wet forests where soil type and age, soil moisture balance, vegetation composition, and disturbance history do not co-vary with temperature. We found that TBCF increases by a factor of two over the 5.2°C MAT gradient in response to increasing ecosystem productivity, while total soil carbon storage is constant. These findings suggest that as temperatures warm, there will be a significant increase in TBCF and belowground carbon process leading to increased flux of CO2 from soils as soil respiration, but that soil organic carbon storage will be relatively insensitive to warming - at least where moisture availability is not affected by rising temperatures. While short-term responses to warming may differ, this study represents long-term insight into the impacts of rising temperatures on belowground carbon cycling and assumes that ecosystem characteristics will change with warming as quantified across this MAT gradient.

Giardina, C. P.; Litton, C. M.; Crow, S. E.

2011-12-01

157

Estimates of Sediment Load Prior to Dam Removal in the Elwha River, Clallam County, Washington  

USGS Publications Warehouse

Years after the removal of the two dams on the Elwha River, the geomorphology and habitat of the lower river will be substantially influenced by the sediment load of the free-flowing river. To estimate the suspended-sediment load prior to removal of the dams, the U.S. Geological Survey collected suspended-sediment samples during water years 2006 and 2007 at streamflow-gaging stations on the Elwha River upstream of Lake Mills and downstream of Glines Canyon Dam at McDonald Bridge. At the gaging station upstream of Lake Mills, discrete samples of suspended sediment were collected over a range of streamflows including a large peak in November 2006 when suspended-sediment concentrations exceeded 7,000 milligrams per liter, the highest concentrations recorded on the river. Based on field measurements in this study and from previous years, regression equations were developed for estimating suspended-sediment and bedload discharge as a function of streamflow. Using a flow duration approach, the average total annual sediment load at the gaging station upstream of Lake Mills was estimated at 327,000 megagrams with a range of uncertainty of +57 to -34 percent (217,000-513,000 megagrams) at the 95 percent confidence level; 77 percent of the total was suspended-sediment load and 23 percent was bedload. At the McDonald Bridge gaging station, daily suspended-sediment samples were obtained using an automated pump sampler, and concentrations were combined with the record of streamflow to calculate daily, monthly, and annual suspended-sediment loads. In water year 2006, an annual suspended-sediment load of 49,300 megagrams was determined at the gaging station at McDonald Bridge, and a load of 186,000 megagrams was determined upstream at the gaging station upstream of Lake Mills. In water year 2007, the suspended-sediment load was 75,200 megagrams at McDonald Bridge and 233,000 megagrams upstream of Lake Mills. The large difference between suspended-sediment loads at both gaging stations shows the extent of sediment trapping by Lake Mills, and a trap efficiency of 0.86 was determined for the reservoir. Pre-dam-removal estimates of suspended-sediment load and sediment-discharge relations will help planners monitor geomorphic and habitat changes in the river as it reaches a dynamic equilibrium following the removal of dams.

Curran, Christopher A.; Konrad, Christopher P.; Higgins, Johnna L.; Bryant, Mark K.

2009-01-01

158

Radiometrically determined dates and sedimentation rates for recent sediments in nine North African wetland lakes (the CASSARINA Project)  

Microsoft Academic Search

Sediment cores were collected from nine wetland lakes in Morocco, Tunisia and Egypt for the CASSARINA project investigating environmental change in Northern African wetlands. The cores were dated radiometrically by using natural (210Pb) and artificial (137Cs and 241Am) radionuclides. At sites in Morocco and Tunisia with mean annual rainfall totals ranging from 500–1000 mm yr-1, fallout records were generally satisfactory

P. G. Appleby; H. H. Birks; R. J. Flower; N. Rose; S. M. Peglar; M. Ramdani; M. M. Kraïem; A. A. Fathi

2001-01-01

159

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

Code of Federal Regulations, 2013 CFR

...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,...

2013-04-01

160

Assimilation of selected PAH and PCB congeners sorbed to sediment by benthic invertebrates. Annual report, 15 Oct 90-14 Oct 91  

SciTech Connect

Methods have been developed for removing and manipulating fecal pellets, and techniques for measuring organic carbon in sediment and fecal pellets and lipid content in Diporeia have been learned. A simple and time efficient extraction procedure has been developed to extract 14C-B(a)P and 51Cr from sediment, Diporeia and fecal pellets. In addition, experiments have shown that 51Cr can be used as a conservative tracer for Diporeia and sediment. Good progress has been made in developing the basic methods involved in determining assimilation efficiencies and preliminary data have been collected for the direct measurement and dual-labeled approaches independent of one another.

Lydy, M.J.

1991-08-29

161

Spatial distribution and historical records of mercury sedimentation in urban lakes under urbanization impacts.  

PubMed

China is assumed one of the largest contributors to the world's total mercury (Hg) emissions, with a rapid increase in anthropogenic Hg emissions. However, little is known about Hg fate and transport in urban areas of China. In this study, total Hg contents in surface (0-5 cm) sediments from lakes in 14 parks (3 in the central urban core (CUC) area, 5 in the developed urban (DDU) area, 2 in the developing urban (DIU) area, and 4 in the suburban (SU) area) and (210)Pb-dated sediment cores from lakes in 5 parks (3 in the CUC and 2 in the DDU) in Shanghai were assessed to compare current patterns (urbanization effect) with the historical records of Hg emissions over the past century. Total Hg content in surface sediments showed a clear urbanization pattern. Dated sediment cores revealed a 2-3 fold increase in total Hg content, while Hg fluxes exponentially increased from ~1900 to present and accelerated since 1990 when China's economy and urbanization booms started. Anthropogenic Hg fluxes in post-2000 ranged from 253 to 1452 ?g m(-2) yr(-1), 2-7 times greater than preindustrial (pre-1900) Hg fluxes. Total Hg and Pb contents in both surface sediments and sediment cores were highly correlated and Hg flux in sediment cores also significantly correlated with annual coal consumption in the period 1949-2008. The significant correlations suggest that coal combustion is a major source of Hg emission in Shanghai. PMID:23327992

Li, Hong-Bo; Yu, Shen; Li, Gui-Lin; Deng, Hong; Xu, Bo; Ding, Jing; Gao, Jin-Bo; Hong, You-Wei; Wong, Ming-Hung

2013-02-15

162

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

PubMed

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

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

2012-01-01

163

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

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.

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

164

Fallout radionuclide tracers identify a switch in sediment sources and transport-limited sediment yield following wildfire in a eucalypt forest  

NASA Astrophysics Data System (ADS)

Fire can alter sediment sources and transport rates in river basins, changing landforms and aquatic habitats and degrading downstream water quality. Variability in the response between environments, between fires, and with time since fire makes predicting the catchment-scale effect of individual fires difficult. This study applies the fallout radionuclides 137Cs and 210Pb xs to trace the sources and transport of fine sediment through a river network following a wildfire of moderate to extreme severity in the 629-km 2 eucalypt-forested Nattai River water-supply catchment near Sydney, Australia. The tracer analysis showed that post-fire erosion caused a switch in fine (< 10 µm) sediment sources from 80% subsoil derived from gully and river bank erosion to 86% topsoil derived from hillslope surface erosion. The fine sediment phosphorus content increased 4-10 fold over pre-fire levels. Annual post-fire sediment yields estimated from suspended solids rating curves were 109-250 times higher than they would have been without fire. A large additional amount of sediment remained stored within the river network for at least four years, particularly in lower-gradient reaches. Analysis of a sediment core showed that surface erosion following a previous fire had supplied at least 29% of total catchment sediment yield over the past 36 years. It is concluded that wildfire can alter catchment sediment budgets in two ways. Firstly, a spatially-diffuse pulse of elevated erosion is associated with moderate or intense rainfall events in post-fire years. Secondly, pulses of elevated catchment sediment yield are driven by the timing and river sediment transport capacity of runoff events. Severe post-fire erosion and high interannual hydrologic variability can result in large sediment stores persisting within the river network for many years. Fallout radionuclide tracers are shown to be useful in quantifying fine sediment sources and transport dynamics following wildfire, and the contribution of wildfire to catchment sediment yield.

Wilkinson, S. N.; Wallbrink, P. J.; Hancock, G. J.; Blake, W. H.; Shakesby, R. A.; Doerr, S. H.

2009-09-01

165

Factors controlling temporal and spatial distribution of total mercury and methylmercury in hyporheic sediments of the Allequash Creek wetland, northern Wisconsin  

Microsoft Academic Search

Hyporheic pore water samples were collected from two sites within the Allequash Creek wetland, in Vilas County, northern Wisconsin, from August 2003 to October 2004. Samples were collected simultaneously at the surface and at 2, 5, 7, 10, and 15 cm below the sediment-water interface. Concentration ranges were 3.7 to 58 pM for inorganic mercury, <0.5 to 16 pM for

Joel E. Creswell; Sara C. Kerr; Matthew H. Meyer; Christopher L. Babiarz; Martin M. Shafer; David E. Armstrong; Eric E. Roden

2008-01-01

166

Spatial variation of sediment deposition in the Hudson River - a detailed inventory and potential causes (Invited)  

NASA Astrophysics Data System (ADS)

Sediment deposition in urban estuaries is controlled by the interaction of human modifications and natural factors that include tides, fresh water inputs, bed morphology, sediment supply, and hydrodynamics. A key element of managing these estuaries is detailed understanding of sediment deposition and its driving processes. Using a combination of geophysical and geochemical analysis we establish a detailed inventory of 20 century deposition for most of the mud-dominated sections of the Hudson River. These data show variations between different segments of the Hudson River as well as strong local variations within each section, with depositional settings ranging from erosional to those accumulating at ~10 mm/year. Our work indicates that 170,000 - 250,000 metric tons of sediment are deposited annually in the areas studied, which is a significant portion of the estimated total annual sediment load of ~700,000 - 800,000 metric tons. This also suggests that some of the accumulated sediments are re-mobilized, e.g. during major storms. The observed patterns of deposition/erosion are primarily caused by natural conditions, but, in some parts, they are strongly influenced by human modifications of the estuary, such as dredging. In addition to improving our understanding of the sediment dynamic of the Hudson River, the observed distribution of sediment deposition is also an indicator for the occurrence of contaminants including heavy metals and PCB’s and thus a valuable tool for management decisions.

Nitsche, F. O.; Kenna, T. C.

2010-12-01

167

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

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).

Aulenbach, Brent T.

2006-01-01

168

Large-scale quantification of suspended sediment transport and deposition in the Mekong Delta  

NASA Astrophysics Data System (ADS)

Sediment dynamics play a major role for the agricultural and fishery productivity of the Mekong Delta. However, the understanding of sediment dynamics in the Mekong Delta, one of the most complex river deltas in the world, is very limited. This is a consequence of its large extent, the intricate system of rivers, channels and floodplains and the scarcity of observations. This study quantifies, for the first time, the suspended sediment transport and sediment-nutrient deposition in the whole Mekong Delta. To this end, a quasi-2-D hydrodynamic model is combined with a cohesive sediment transport model. The combined model is calibrated automatically using six objective functions to represent the different aspects of the hydraulic and sediment transport components. The model is calibrated for the extreme flood season in 2011 and shows good performance for the two validation years with very different flood characteristics. It is shown how sediment transport and sediment deposition vary from Kratie at the entrance of the Delta to the coast. The main factors influencing the spatial sediment dynamics are the setup of rivers, channels and dike-rings, the sluice gate operations, the magnitude of the floods and tidal influences. The superposition of these factors leads to high spatial variability of sediment transport, in particular in the Vietnamese floodplains. Depending on the flood magnitude, the annual sedimentation rate averaged over the Vietnamese floodplains varies from 0.3 to 2.1 kg m-2 yr-1, and the ring dike floodplains trap between 1 and 6% of the total sediment load at Kratie. This is equivalent to 29 × 103-440 × 103 t of nutrients (N, P, K, TOC) deposited in the Vietnamese floodplains. This large-scale quantification provides a basis for estimating the benefits of the annual Mekong floods for agriculture and fishery, and is important information for assessing the effects of deltaic subsidence and climate change related sea level rise.

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

2014-04-01

169

A high resolution proxy-climate record from an arctic lake with annually-laminated sediments on Devon Island, Nunavut, Canada  

Microsoft Academic Search

Sediments from a 3 ha lake (75 °34.34'N, 89 °18.55'W) from the coastal region of northern Devon Island, Nunavut, Canada, contain discrete laminations in the deepest part of the basin. The laminations are varves as indicated by the correspondence between counts and thickness measurements of the couplets and 210Pb dating. A 14 cm core representing 150 years of sedimentation contained

K. Gajewski; P. B. Hamilton; R. McNeely

1997-01-01

170

A Kinetic Model To Quantify The Effect Of Total Organic Carbon Content On The Loss Of Magnetic Susceptibility Values In Surficial Sediments Of Coastal Environments: The Case Study Of The Ría De Muros, NW Spain  

NASA Astrophysics Data System (ADS)

A detailed magnetic study of mineral dissolution has been carried out in surficial sediments from the Ría de Muros, a large coastal embayment in NW Iberia. The study area is under the influence of one of the world's most intense coastal upwelling systems, which along with the important continental supplies of organic carbon, cause very high organic matter contents in the sediment. The magnetic susceptibility of the surficial (top 20 cm of the sea bed) sediments of the Ría de Muros is dominated by the occurrence of ferromagnetic minerals, mostly biogenic magnetite and detrital (titano-) magnetite. The way in which the Total Organic Carbon (TOC) in the sediment controls the occurrence and concentration of these minerals is twofold. First because a minimal amount of organic matter it is needed for the development of the magnetotactic bacteria. Second because values above a given TOC concentration promote early redoxomorfic diagenesis and subsequently, ferromagnetic minerals depletion by dissolution. Maximum magnetic susceptibility values (up to 7 x 10-8 SI) are subsequently found in sediments with enough supply of organic matter to ensure the growth of magnetotactic bacteria, but where the TOC content is not as high as to cause the development of suboxic conditions within the surficial layers of the sediments. The magnetic susceptibility loss due to the increase in TOC can be explained and quantified with a simple geochemical kinetic model. Textural dilution of the magnetic signal due to the presence of coarse diamagnetic quartz and biogenic carbonates in the sediment matrix, are accounted for by normalizing with Al, a well-know grain-size proxy in this environment. When the normalized magnetic susceptibility is plotted against the TOC, the resulting distribution shows a neat exponential decay trend from high magnetic susceptibility and low TOC values to low magnetic susceptibility and high TOC values, resulting from the kinetics of magnetite dissolution. This profile is interpreted as a consequence of the microbial degradation of organic matter that occurs in muddy or muddy sandy ría sediments, where the TOC availability is not a limiting factor due to the high organic matter concentrations (2 to 10%). On the contrary, the process appears to be limited by the availability of electron acceptors and, as a result, suboxic conditions are achieved at very shallow depths. Considering this, we propose a simple second order kinetic model for the dissolution of magnetite in which the rate of dissolution of magnetite depends on the TOC and magnetite concentrations of the sediment. The resulting model explains the exponential profile of magnetic susceptibility versus TOC with a significance level of p<0.01 (r2=0.98). From the parameters of this model, it is possible to estimate that an increase of 0.35±0.05% in the sedimentary TOC is able to reduce by half the magnetite concentration in the sediments of this ría.

Andrade, A.; Rey, D.; Mohamed, K. J.; Rubio, B.

2013-05-01

171

Estimates of suspended sediment entering San Francisco Bay from the Sacramento and San Joaquin Delta, San Francisco Bay, California  

USGS Publications Warehouse

This study demonstrates the use of suspended-sediment concentration (SSC) data collected at Mallard Island as a means of determining suspended-sediment load entering San Francisco Bay from the Sacramento and San Joaquin River watersheds. Optical backscatter (OBS) data were collected every 15 min during water years (WYs) 1995-2003 and converted to SSC. Daily fluvial advective sediment load was estimated by combining estimated Delta outflow with daily averaged SSC. On days when no data were available, SSC was estimated using linear interpolation. A model was developed to estimate the landward dispersive load using velocity and SSC data collected during WYs 1994 and 1996. The advective and dispersive loads were summed to estimate the total load. Annual suspended-sediment load at Mallard Island averaged 1.2??0.4 Mt (million metric tonnes). Given that the average water discharge for the 1995-2003 period was greater than the long -term average discharge, it seems likely that the average suspended-sediment load may be less than 1.2??0.4 Mt. Average landward dispersive load was 0.24 Mt/yr, 20% of the total. On average during the wet season, 88% of the annual suspended-sediment load was discharged through the Delta and 43% occurred during the wettest 30-day period. The January 1997 flood transported 1.2 Mt of suspended sediment or about 11% of the total 9-year load (10.9 Mt). Previous estimates of sediment load at Mallard Island are about a factor of 3 greater because they lacked data downstream from riverine gages and sediment load has decreased. Decreasing suspended-sediment loads may increase erosion in the Bay, help to cause remobilization of buried contaminants, and reduce the supply of sediment for restoration projects. ?? 2005 Elsevier B.V. All rights reserved.

McKee, L. J.; Ganju, N. K.; Schoellhamer, D. H.

2006-01-01

172

Nitrogen dynamics in sediment during water level manipulation on the Upper Mississippi River  

USGS Publications Warehouse

Nitrogen (N) has been linked to increasing eutrophication in the Gulf of Mexico and as a result there is increased interest in managing and improving water quality in the Mississippi River system. Water level reductions, or 'drawdowns', are being used more frequently in large river impoundments to improve vegetation growth and sediment compaction. We selected two areas of the Upper Mississippi River system (Navigation Pool 8 and Swan Lake) to examine the effects of water level drawdown on N dynamics. Navigation Pool 8 experienced summer drawdowns in 2001 and 2002. Certain areas of Swan Lake have been drawn down annually since the early 1970s where as other areas have remained inundated. In the 2002 Pool 8 study we determined the effects of sediment drying and rewetting resulting from water level drawdown on (1) patterns of sediment nitrification and denitrification and (2) concentrations of sediment and surface water total N (TN), nitrate, and ammonium (NH4+). In 2001, we only examined sediment NH4+ and TN. In the Swan Lake study, we determined the long-term effects of water level drawdowns on concentrations of sediment NH4+ and TN in sediments that dried annually and those that remained inundated. Sediment NH4+ decreased significantly in the Pool 8 studies during periods of desiccation, although there were no consistent trends in nitrification and denitrification or a reduction in total sediment N. Ammonium in sediments that have dried annually in Swan Lake appeared lower but was not significantly different from sediments that remain wet. The reduction in sediment NH4+ in parts of Pool 8 was likely a result of increased plant growth and N assimilation, which is then redeposited back to the sediment surface upon plant senescence. Similarly, the Swan Lake study suggested that drawdowns do not result in long term reduction in sediment N. Water level drawdowns may actually reduce water retention time and river-floodplain connectivity, while promoting significant accumulation of organic N. These results indicate that water level drawdowns are probably not an effective means of removing N from the Upper Mississippi River system.

Cavanaugh, Jennifer C.; Richardson, William B.; Strauss, Eric A.; Bartsch, Lynn A.

2006-01-01

173

Multi-proxy analysis of annually laminated sediments from two neighboring lakes in South-Central Chile: a continuous activity record of Villarrica Volcano for the past 600 years  

NASA Astrophysics Data System (ADS)

Lake sediments contain valuable information about past volcanic and seismic events that affected the lake and its catchment, and provide unique records of the recurrence rate and magnitude of such events. This study uses a multi-lake and multi-proxy analytical approach to obtain reliable and high-resolution records of past natural catastrophes from c. 600 year old annually-laminated (varved) lake sediment sequences extracted from two lakes, Villarrica and Calafquén, in the volcanically and seismically active Chilean Lake District. Using a combination of µXRF scanning, microfacies analysis, grain-size analysis, color analysis and magnetic susceptibility, we detected and characterized four different types of event deposits (EDs) (lacustrine turbidites; tephra-fall layers; run-off cryptotephras; lahar deposits) and revised the eruption record for Villarrica Volcano, which is unprecedented in its continuity and temporal resolution. Moreover, lahar deposits in lacustrine sediments were described for the first time. Time series analysis shows 112 eruptions with a Volcanic Explosivity Index (VEI) ? 2 in the last c. 600 years. Also deposits of eruptions from the more remote Carrán-Los Venados Volcanic Complex, Mocho-Choshuenco, Quetrupillán and Lanín or Huanquihue volcanoes were identified in the studied lake sediments. The last VEI ? 2 eruption of Villarrica Volcano occurred in AD 1991. We estimate the probability of the occurrence of future eruptions from Villarrica Volcano, and statistically demonstrate that the probability of a 21-year repose period (anno 2012) without eruptions is ? 1.9 %. This new perspective on the recurrence interval of eruptions and historical lahar activity will help improve volcanic hazard assessments for this rapidly expanding tourist region.

Van Daele, Maarten; Moernaut, Jasper; Silversmit, Geert; Schmidt, Sabine; Fontijn, Karen; Heirman, Katrien; Vandoorne, Willem; De Clercq, Maikel; Van Acker, Joris; Wolff, Christian; Pino, Mario; Urrutia, Roberto; Roberts, Stephen J.; Vincze, Laszlo; De Batist, Marc

2013-04-01

174

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

USGS Publications Warehouse

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.

Singer, M. B.; Dunne, T.

2006-01-01

175

Exchanges of sediment between the flood plain and channel of the Amazon River in Brazil  

USGS Publications Warehouse

Sediment transport through the Brazilian sector of the Amazon River valley, a distance of 2010 km, involves exchanges between the channel and the flood plain that in each direction exceed the annual flux of sediment out of the river at O??bidos (???1200 Mt yr-1). The exchanges occur through bank erosion, bar deposition, settling from diffuse overbank flow, and sedimentation in flood-plain channels. We estimated the magnitude of these exchanges for each of 10 reaches of the valley, and combined them with calculations of sediment transport into and out of the reaches based on sediment sampling and flow records to define a sediment budget for each reach. Residuals in the sediment budget of a reach include errors of estimation and erosion or deposition within the channel. The annual supply of sediment entering the channel from bank erosion was estimated to average 1570 Mt yr-1 (1.3 ?? the O??bidos flux) and the amount transferred from channel transport to the bars (380 Mt yr-1) and the flood plain (460 Mt yr-1 in channelized flow; 1230 Mt yr-1 in diffuse overbank flow) totaled 2070 Mt yr-1 (1.7 ?? the O??bidos flux). Thus, deposition on the bars and flood plain exceeded bank erosion by 500 Mt yr-1 over a 10-16 yr period. Sampling and calculation of sediment loads in the channel indicate a net accumulation in the valley floor of approximately 200 Mt yr-1 over 16 yr, crudely validating the process-based calculations of the sediment budget, which in turn illuminate the physical controls on each exchange process. Another 300-400 Mt yr-1 are deposited in a delta plain downstream of O??bidos. The components of the sediment budget reflect hydrologie characteristics of the valley floor and geomorphic characteristics of the channel and flood plain, which in turn are influenced by tectonic features of the Amazon structural trough.

Dunne, T.; Mertes, L. A. K.; Meade, R. H.; Richey, J. E.; Forsberg, B. R.

1998-01-01

176

Sediment deposition and occurrence of selected nutrients, other chemical constituents, and diatoms in bottom sediment, Perry Lake, northeast Kansas, 1969-2001  

USGS Publications Warehouse

A combination of bathymetric surveying and bottom-sediment coring was used to investigate sediment deposition and the occurrence of selected nutrients (total nitrogen and total phosphorus), organic and total carbon, 26 metals and trace elements, 15 organochlorine compounds, 1 radionuclide, and diatoms in bottom sediment of Perry Lake, northeast Kansas. The total estimated volume and mass of bottom sediment deposited from 1969 through 2001 in the original conservation-pool area of the lake was 2,470 million cubic feet (56,700 acre-feet) and 97,200 million pounds (44,100 million kilograms), respectively. The estimated sediment volume occupied about 23 percent of the original conservation-pool, water-storage capacity of the lake. Mean annual net sediment deposition since 1969 was estimated to be 3,040 million pounds (1,379 million kilograms). Mean annual sediment yield from the Perry Lake Basin was estimated to be 2,740,000 pounds per square mile (4,798 kilograms per hectare). The estimated mean annual net loads of total nitrogen and total phosphorus deposited in the bottom sediment of Perry Lake were 7,610,000 pounds per year (3,450,000 kilograms per year) and 3,350,000 pounds per year (1,520,000 kilograms per year), respectively. The estimated mean annual yields of total nitrogen and total phosphorus from the Perry Lake Basin were 6,850 pounds per square mile per year (12.0 kilograms per hectare per year) and 3,020 pounds per square mile per year (5.29 kilograms per hectare per year), respectively. A statistically significant positive trend for total nitrogen deposition in the bottom sediment of Perry Lake was indicated. However, the trend may be due solely to analytical variance. No statistically significant trend for total phosphorus deposition was indicated. Overall, the transport and deposition of these constituents have been relatively uniform throughout the history of Perry Lake. On the basis of nonenforceable sediment-quality guidelines established by the U.S. Environmental Protection Agency, concentrations of arsenic, chromium, copper, and nickel in the bottom sediment of Perry Lake typically exceeded the threshold-effects levels, which represent the concentrations above which toxic biological effects occasionally occur. Most nickel concentrations also exceeded the probable-effects level, which represents the concentration above which toxic biological effects usually or frequently occur. Sediment concentrations of metals and trace elements were relatively uniform over time. Statistically significant positive depositional trends for arsenic and manganese and statistically significant negative depositional trends for beryllium, chromium, titanium, and vanadium were indicated. However, the trends may be due solely to analytical variance. Organochlorine compounds either were not detected or were detected at concentrations less than the threshold-effects levels. Evidence of a negative depositional trend for DDE (degradation product of DDT) was consistent with the history of DDT use. Other organochlorine compounds detected were DDD and dieldrin. Diatom occurrence in the bottom sediment of Perry Lake was dominated by species that are indicators of eutrophic (nutrient-rich) conditions. Thus, it was concluded that eutrophic conditions have existed during much of the history of Perry Lake. However, an increase in the relative percentage abundance of the oligotrophic (nutrient-poor) species, combined with the significant positive depositional trends for two oligotrophic species (Aulacoseira islandica and Cyclotella radiosa) and the significant negative depositional trend for one eutrophic species (Stephanodiscus niagarae), indicated that conditions in Perry Lake may have become less eutrophic in recent years. Notable changes in human activity within the basin included a substantial decrease in alfalfa production and a substantial increase in soybean production from 1965 to 2000. These and other changes in human activi

Juracek, Kyle E.

2003-01-01

177

The efficacy of oxidative coupling for promoting in-situ immobilization of hydroxylated aromatics in contaminated soil and sediment systems. 1998 annual progress report  

Microsoft Academic Search

'Hydroxylated aromatic compounds (HAC''s) and their precursors are common contaminants of surface and subsurface systems at DOE facilities. The environmental fate and transport of such compounds, particularly in subsurface systems, is generally dominated by their sorption and desorption by soils and sediments. Certain secondary chemical reactions, most specifically abiotic and\\/or enzymatic oxidative coupling, may be significant in controlling the sorption

W. J. Weber; A. Bhandari

1998-01-01

178

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 ...

179

QUANTIFICATION AND INTERPRETATION OF TOTAL PETROLEUM HYDROCARBONS IN SEDIMENT SAMPLES BY A GC/MS METHOD AND COMPARISON WITH EPA 418.1 AND A RAPID FIELD METHOD  

EPA Science Inventory

ABSTRACT: Total Petroleum hydrocarbons (TPH) as a lumped parameter can be easily and rapidly measured or monitored. Despite interpretational problems, it has become an accepted regulatory benchmark used widely to evaluate the extent of petroleum product contamination. Three cu...

180

Polycyclic aromatic hydrocarbons increase in Athabasca River Delta sediment: temporal trends and environmental correlates.  

PubMed

The Athabasca River in Alberta, Canada, flows north through an area undergoing extensive bitumen resource extraction and processing before discharging its water and sediments into the Athabasca Delta and Lake Athabasca. Polycyclic aromatic hydrocarbons (PAHs) have been identified as an environmental concern in the region. We analyzed environmental data collected by the Regional Aquatics Monitoring Program and government agencies to determine whether temporal trends exist in the concentration of sediment PAHs in the Athabasca River Delta. We then determined what environmental factors related to the trends in sediment PAH concentrations. Total PAH concentrations in the sediment of the Athabasca River Delta increased between 1999 and 2009 at a rate of 0.05 mg/kg/yr ± 0.02 s.e. Annual bitumen production and mined sand volume, extent of landscape disturbance, and particulate emissions were correlated with sediment PAH concentrations as were total organic carbon in sediment and discharge of the Clearwater River, a major tributary of the Athabasca River. Within four tributaries of the Athabasca River, only the Clearwater River showed a significant correlation between discharge and sediment PAH concentration at their river mouths. Carefully designed studies are required to further investigate which factors best explain variability in sediment PAH concentrations. PMID:21520949

Timoney, Kevin P; Lee, Peter

2011-05-15

181

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

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

182

Sediment Loading from Crab Creek and Other Sources to Moses Lake, Washington, 2007 and 2008  

USGS Publications Warehouse

The average sediment-accumulation rate on the bed of Moses Lake since 1980, based on the identification of Mount St. Helens ash in lakebed cores, was 0.24 inches per year. Summed over the lake surface area, the average sediment-accumulation rate on the lakebed is 190,000 tons per year. Based on USGS stream-gaging station data, the average annual sediment load to Moses Lake from Crab Creek was 32,000 tons per year between 1943 and 2008; the post Mount St. Helens eruption annual load from Crab Creek was calculated to be 13,000 tons per year. The total mass input from Crab Creek and other fluvially derived sediment sources since 1980 has been about 20,000 tons per year. Eolian sediment loading to Moses Lake was about 50,000 tons per year before irrigation and land-use development largely stabilized the Moses Lake dune field. Currently, eolian input to the lake is less than 2,000 tons per year. Considering all sediment sources to the lake, most (from 80 to 90 percent) of post-1980 lakebed-sediment accumulation is from autochthonous, or locally formed, mineral matter, including diatom frustuals and carbonate shells, derived from biogenic production in phytoplankton and zooplankton. Suspended-sediment samples collected from Crab Creek and similar nearby waterways in 2007 and 2008 combined with other USGS data from the region indicated that a proposed Bureau of Reclamation supplemental feed of as much as 650 cubic feet per second through Crab Creek might initially contain a sediment load of as much as 1,500 tons per day. With time, however, this sediment load would decrease to about 10 tons per day in the sediment-supply-limited creek as available sediment in the channel is depleted. Sediment loads in the supplemental feed ultimately would be similar to loads in other bypass canals near Moses Lake. Considering the hydrology and geomorphology of the creek over multiple years, there is little evidence that the proposed supplemental feed would substantially increase the overall sediment load from Crab Creek to Moses Lake relative to natural, background conditions. Because Moses Lake is relatively shallow and subject to significant wind-driven circulation currents, mixing also would redistribute some of the fluvial sediment load deposited from Crab Creek throughout Parker Horn and the rest of Moses Lake, further mitigating the local effect of Crab Creek sedimentation near the City of Moses Lake.

Magirl, Christopher S.; Cox, Stephen E.; Mastin, Mark C.; Huffman, Raegan L.

2010-01-01

183

Identification of Diurnal, Seasonal and Inter-Annual Variability Across SE Asian Field Observations of key Water Cycle Variables: Rainfall, net Radiation, Total Evaporation and River Discharge  

NASA Astrophysics Data System (ADS)

The identification of periodic patterns in water cycle variables is critical to the understanding of land-atmosphere interactions, climate change and the evaluation of General Circulation Model (GCM) output. SE Asia in particular plays a very important role on the global climate because it is a large source of energy and water fluxes into the upper atmosphere. Cycle identification is carried out following the Data Based Mechanistic (DBM) philosophy, which focuses on the use of parsimonious, rigorous models which are characterised by lack of a priori assumptions, built in uncertainty analysis and final model acceptance dependent on the physical interpretation of the results. The DBM tool used here is the Unobserved Component - Dynamic Harmonic Regression (UC-DHR) model, which is a statistical method that allows the identification of variability in time series by introducing Time Variable Parameter (TVP) estimation of harmonic components. UC-DHR is not scale dependent and was thus applied to both hourly (to investigate diurnal variation) and fortnightly datasets (for intra- and inter-annual variability). The data used in the analysis has been gathered from existing catchment datasets for three regions of tropical SE Asia, namely Northern Thailand, Central Peninsular Malaysia and Northeast Borneo. These regions were chosen because they represent the hydro-climatic gradient (seasonal to equatorial) present within the tropics and because SE Asia has the most extensive set of catchment/plot studies within the humid tropics. Results show modeling tools were able to quantify the main patterns present in the observations throughout different time scales (diurnal, intra-annual and inter-annual) and the strength of the correlation pattern between the four hydro-climatic variables. The subsequent discussion focuses on the physical processes behind those patterns (e.g. diurnal variability caused by local convection due to solar heating; impact of El Niño Southern Oscillation on inter-annual variability of rainfall and river discharge).

Solera García, M. A.; Tych, W.; Chappell, N.

2007-12-01

184

Comparative application of two mathematical models to predict sedimentation in Yermasoyia Reservoir, Cyprus  

NASA Astrophysics Data System (ADS)

The Yermasoyia Reservoir is located northeast of the town of Limassol, Cyprus. The storage capacity of the reservoir is 13.6 × 106 m3. The basin area of the Yermasoyia River, which feeds the reservoir, totals 122.5 km2. This study aims to estimate the mean annual deposition amount in the reservoir, which originates from the corresponding basin. For the estimate of the mean annual sediment inflow into the reservoir, two mathematical models are used alternatively. Each model consists of three submodels: a rainfall-runoff submodel, a soil erosion submodel and a sediment transport submodel for streams. In the first model, the potential evapotranspiration is estimated for the rainfall-runoff submodel, and the soil erosion submodel of Schmidt and the sediment transport submodel of Yang are used. In the second model, the actual evapotranspiration is estimated for the rainfall-runoff submodel, and the soil erosion submodel of Poesen and the sediment transport submodel of Van Rijn are used. The deposition amount in the reservoir is estimated by means of the diagram of Brune, which delivers the trap efficiency of the reservoir. Daily rainfall data from three rainfall stations, and daily values of air temperature, relative air humidity and sunlight hours from a meteorological station for four years (1986-89) were available. The computed annual runoff volumes and mean annual soil erosion rate are compared with the respective measurement data. Copyright

Hrissanthou, V.

2006-11-01

185

Fluvial sediment in Double Creek subwatershed No. 5, Washington County, Oklahoma  

USGS Publications Warehouse

Most precipitation falling on subwatershed No. 5 does not flow through the reservoir. During this study approximately three-fourths (47,000 acre-feet) of the precipitation was lost by evaporation and transpiration; a small amount is lost by deep subsurface percolation. Fifty-nine percent of the total sediment load was discharged from the reservoir during four major outflow periods representing 34 percent of the outflow days. The highest percentage of runoff and sediment yield occurs from March through June. Fifty-three percent of the water discharged and 63 percent of the sediment yield occurred during this 4-month period. The average annual yield of fluvial sediment from watershed No. 5 was 607 tons per square mile, or 0.95 ton per acre. A total of 21,370 tons of fluvial sediment was transported into reservoir No. 5 and a total of 19,930 tons was deposited. Seventy-eight percent of the total fluvial sediment was deposited during the first 9.2 years, or 63 percent of time of reservoir operation. The computed trap efficiency of reservoir No. 5 was 93 percent.

Bednar, Gene A.; Waldrep, T. E.

1973-01-01

186

Spatial and Temporal Variability of Total Non-Residual Heavy Metals Content in Stream Sediments from the Suquia River System, Cordoba, Argentina  

Microsoft Academic Search

The Suquía is a semiarid (rainfall, 700-900 mm y-1), medium-size (7700 km2) riversystem located in central Argentina. Its mountainous upper catchment includes pristine areas aswell as a variety of human settlements and a reservoir lake. A large city (Córdoba, ca. 1.3million inhabitants) and a terminal hypersaline lake are included in the middle and lower basin.Total non-residual (TNR) heavy metals (Pb,

D. M. Gaiero; G. Roman Ross; P. J. Depetris; S. Kempe

1997-01-01

187

Nutrients and Suspended Sediment in Snowmelt Runoff from Part of the Upper Mississippi River Basin, Minnesota and Wisconsin, 1997  

USGS Publications Warehouse

The U.S. Geological Survey sampled snowmelt runoff from 42 stream sites during March and April 1997 in part of the Upper Mississippi River Basin, Minnesota and Wisconsin, to characterize nutrient and suspended-sediment concentrations, yields, and loads. Ancillary data from 12 sites provided data to estimate constituent loads delivered during snowmelt and 1997. The snowmelt period contributed from 1 to 50 percent of 1997 annual loads of total nitrogen, total phosphorus, and suspended sediment at small stream sites, and 17 to 70 percent of annual loads at mainstem river sites. Small streams in agricultural areas transported the greatest proportions of annual loads during snowmelt. Snowmelt from urban streams transported the least proportions of annual loads. Agricultural streams had significantly greater median yields (p < 0.025) of dissolved nitrite, nitrate, phosphorus, orthophosphate, total nitrogen, and total phosphorus than forested sites, and significantly greater median yields (p < 0.025) of dissolved nitrate and orthophosphate than all other land uses. In forested areas, yields of suspended sediment and all nutrient forms were significantly greater (p < 0.05) for streams draining impermeable deposits than permeable deposits.

Fallon, James D.; McNellis, Ryan P.

2000-01-01

188

The contribution of sediment from forested areas of the Chesapeake Bay Watershed  

NASA Astrophysics Data System (ADS)

Fine-grained sediment is a major pollutant in the Chesapeake Bay and its receiving waters. Sediment budget studies have been conducted in small basins draining to the Bay over the last decade to understand the important sources of fine-grained sediment, quantify erosion rates, and determine sediment yields. Sediment budget approaches include modeling (SPARROW), sediment fingerprinting, and quantifying upland rates of erosion (Cesium-137). SPARROW model results indicate that forests deliver between 2 to 8% of the total sediment to the Bay. Sediment-fingerprinting results from small watershed studies indicate that forests contribute between 13 to 29 % of the sediment. The Cesium-137 technique was used to quantify soil redistribution (erosion and deposition) rates for forested areas in the Linganore Creek (146 km2) watershed which drains the Piedmont Physiographic Province. Average forest erosion rates measured in 2009 for Linganore Creek using Cesium-137 were 2.6 t/ha/yr. With 27% of the Linganore Creek watershed in forest, over 10,300 may be eroded off of forested lands which is more than the average annual suspended-sediment load (8,050 Mg/yr) in Linganore Creek, indicating that much of the eroded forest sediment goes in storage. Most of the forested areas in the Chesapeake Bay watershed were cut down for agriculture between the time of European colonization and the early 20th Century. In the late 20th century forested lands show an increase in areal extent. Although studies have not been conducted to understand why these secondary growth forests are eroding, it may involve that these forests have not fully recovered from deforestation. Soil profiles are thin, and runoff and sediment relations may have been altered, leading to high rates of erosion.

Gellis, A.; Brakebill, J.

2012-12-01

189

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

USGS Publications Warehouse

Continuous streamflow and turbidity data collected from October 1, 2008, to September 30, 2010, at streamgage sites upstream and downstream from Kanopolis and Tuttle Creek Lakes, Kansas, were used to compute the total suspended-sediment load delivered to and released from each reservoir as well as the sediment trap efficiency for each reservoir. Ongoing sedimentation is decreasing the ability of the reservoirs to serve several purposes including flood control, water supply, and recreation. River channel stability upstream and downstream from the reservoirs was assessed using historical streamgage information. For Kanopolis Lake, the total 2-year inflow suspended-sediment load was computed to be 600 million pounds. Most of the suspended-sediment load was delivered during short-term, high-discharge periods. The total 2-year outflow suspended-sediment load was computed to be 31 million pounds. Sediment trap efficiency for the reservoir was estimated to be 95 percent. The mean annual suspended-sediment yield from the upstream basin was estimated to be 129,000 pounds per square mile per year. No pronounced changes in channel width were evident at five streamgage sites located upstream from the reservoir. At the Ellsworth streamgage site, located upstream from the reservoir, long-term channel-bed aggradation was followed by a period of stability. Current (2010) conditions at five streamgages located upstream from the reservoir were typified by channel-bed stability. At the Langley streamgage site, located immediately downstream from the reservoir, the channel bed degraded 6.15 feet from 1948 to 2010. For Tuttle Creek Lake, the total 2-year inflow suspended-sediment load was computed to be 13.3 billion pounds. Most of the suspended-sediment load was delivered during short-term, high-discharge periods. The total 2-year outflow suspended-sediment load was computed to be 327 million pounds. Sediment trap efficiency for the reservoir was estimated to be 98 percent. The mean annual suspended-sediment yield from the upstream basin was estimated to be 691,000 pounds per square mile per year. In general, no pronounced changes in channel width were evident at six streamgage sites located upstream from the reservoir. At the Barnes and Marysville streamgage sites, located upstream from the reservoir, long-term channel-bed degradation followed by stability was indicated. At the Frankfort streamgage site, located upstream from the reservoir, channel-bed aggradation of 1.65 feet from 1969 to 1989 followed by channel-bed degradation of 2.4 feet from 1989 to 2010 was indicated and may represent the passage of a sediment pulse caused by historical disturbances (for example, channelization) in the upstream basin. With the exception of the Frankfort streamgage site, current (2010) conditions at four streamgages located upstream from the reservoir were typified by channel-bed stability. At the Manhattan streamgage site, located downstream from the reservoir, high-flow releases associated with the 1993 flood widened the channel about 60 feet (30 percent). The channel bed at this site degraded 4.2 feet from 1960 to 1998 and since has been relatively stable. For the purpose of computing suspended-sediment concentration and load, the use of turbidity data in a regression model can provide more reliable and reproducible estimates than a regression model that uses discharge as the sole independent variable. Moreover, the use of discharge only to compute suspended-sediment concentration and load may result in overprediction. Stream channel banks, compared to channel beds, likely are a more important source of sediment to Kanopolis and Tuttle Creek Lakes from the upstream basins. Other sediment sources include surface-soil erosion in the basins and shoreline erosion in the reservoirs.

Juracek, Kyle E.

2011-01-01

190

Sedimentation-related meetings  

NASA Astrophysics Data System (ADS)

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

191

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

SciTech Connect

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

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

1987-11-01

192

Changes in bottom-surface elevations in three reservoirs on the lower Susquehanna River, Pennsylvania and Maryland, following the January 1996 flood; implications for nutrient and sediment loads to Chesapeake Bay  

USGS Publications Warehouse

The Susquehanna River drains about 27,510 square miles in New York, Pennsylvania, and Maryland, contributes nearly 50 percent of the freshwater discharge to the Chesapeake Bay, and contributes nearly 66 percent of the annual nitrogen load, 40 percent of the phosphorus load, and 25 percent of the suspended-sediment load from non-tidal parts of the Bay during a year of average streamflow. A reservoir system formed by three hydroelectric dams on the lower Susquehanna River is currently trapping a major part of the phosphorus and suspended-sediment loads from the basin and, to a lesser extent, the nitrogen loads. In the summer of 1996, the U. S. Geological Survey collected bathymetric data along 64 cross sections and 40 bottom-sediment samples along 14 selected cross sections in the lower Susquehanna River reservoir system to determine the remaining sediment-storage capacity, refine the current estimate of when the system may reach sediment-storage capacity, document changes in the reservoir system after the January 1996 flood, and determine the remaining nutrient mass in Conowingo Reservoir. Results from the 1996 survey indicate an estimated total of 14,800,000 tons of sediment were scoured from the reservoir system from 1993 (date of previous bathymetric survey) through 1996. This includes the net sediment change of 4,700,000 tons based on volume change in the reservoir system computed from the 1993 and 1996 surveys, the 6,900,000 tons of sediment deposited from 1993 through 1996, and the 3,200,000 tons of sediment transported into the reservoir system during the January 1996 flood. The January 1996 flood, which exceeded a 100-year recurrence interval, scoured about the same amount of sediment that normally would be deposited in the reservoir system during a 4- to 6-year period. Concentrations of total nitrogen in bottom sediments in the Conowingo Reservoir ranged from 1,500 to 6,900 mg/kg (milligrams per kilogram); 75 percent of the concentrations were between 3,000 and 5,000 mg/kg. About 96 percent of the concentrations of total nitrogen consisted of organic nitrogen. Concentrations of total phosphorus in bottom sediments ranged from 286 to 1,390 mg/kg. About 84 percent of the concentrations of total phosphorus were comprised of inorganic phosphorus. The ratio of concentrations of plant-available phosphorus to concentrations of total phosphorus ranged from 0.6 to 3.5 percent; ratios generally decreased in a downstream direction. About 29,000 acre-feet, or 42,000,000 tons, of sediment can be deposited before Conowingo Reservoir reaches sediment-storage capacity. Assuming the average annual sediment-deposition rate remains unchanged and no scour occurs due to floods, the reservoir system could reach sediment-storage capacity in about 17 years. The reservoir system currently is trapping about 2 percent of the nitrogen, 45 percent of the phosphorus, and 70 percent of the suspended sediment transported by the river to the upper Chesapeake Bay. Once the reservoir reaches sediment-storage capacity, an estimated 250-percent increase in the current annual loads of suspended sediment, a 2-percent increase in the current annual loads of total nitrogen, and a 70-percent increase in the current annual loads of total phosphorus from the Susquehanna River to Chesapeake Bay can be expected. If the goal of a 40-percent reduction in controllable phosphorus load from the Susquehanna River Basin is met before the reservoirs reach sediment-storage capacity, the 40-percent reduction goal will probably be exceeded when the reservoir system reaches sediment-storage capacity.

Langland, Michael J.; Hainly, Robert A.

1997-01-01

193

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

NASA Astrophysics Data System (ADS)

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.

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

2009-12-01

194

Sediment inflow, outflow and deposition for Lakes Marion and Moultrie, South Carolina, October 1983-March 1985  

USGS Publications Warehouse

In 1941 a Coastal Plain reach of the Santee River was impounded to form Lake Marion and diverted into a diked-off part of the Cooper River basin to form Lake Moultrie. Rates of sediment inflow and outflow of the lakes were determined by the U.S. Geological Survey for the periods July 1966 - June 1968 and October 1983 - March 1985. Total sediment discharge was estimated for two inflow stations and continuous streamflow monitors and automatic suspended-sediment samplers were used for computation of suspended-sediment discharge. Bedload discharge was computed by the modified Einstein procedure. Suspended-sediment discharge was monitored at three outflow stations, with the suspended-sediment concentration measured on a weekly basis. During the 1983-1985 study, mean annual suspended-sediment inflow to Lakes Marion and Moultrie was estimated to be 722,000 tons, and the outflow was estimated at 175,000 tons, for a trap efficiency of 76% and a deposition rate of about 547,000 tons/year. This is about 33% less than the deposition rate determined during the 1966-68 study. The deposition rate for suspended and bedload sediment during the 1983 - 1985 study was about 650,000 tons/year. (USGS)

Cooney, T. W.

1988-01-01

195

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

USGS Publications Warehouse

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.

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

2011-01-01

196

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)

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.

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

1999-05-01

197

Full implementation of a distributed hydrological model based on check dam trapped sediment volumes  

NASA Astrophysics Data System (ADS)

Lack of hydrometeorological data is one of the most compelling limitations to the implementation of distributed environmental models. Mediterranean catchments, in particular, are characterised by high spatial variability of meteorological phenomena and soil characteristics, which may prevents from transferring model calibrations from a fully gauged catchment to a totally o partially ungauged one. For this reason, new sources of data are required in order to extend the use of distributed models to non-monitored or low-monitored areas. An important source of information regarding the hydrological and sediment cycle is represented by sediment deposits accumulated at the bottom of reservoirs. Since the 60s, reservoir sedimentation volumes were used as proxy data for the estimation of inter-annual total sediment yield rates, or, in more recent years, as a reference measure of the sediment transport for sediment model calibration and validation. Nevertheless, the possibility of using such data for constraining the calibration of a hydrological model has not been exhaustively investigated so far. In this study, the use of nine check dam reservoir sedimentation volumes for hydrological and sedimentological model calibration and spatio-temporal validation was examined. Check dams are common structures in Mediterranean areas, and are a potential source of spatially distributed information regarding both hydrological and sediment cycle. In this case-study, the TETIS hydrological and sediment model was implemented in a medium-size Mediterranean catchment (Rambla del Poyo, Spain) by taking advantage of sediment deposits accumulated behind the check dams located in the catchment headwaters. Reservoir trap efficiency was taken into account by coupling the TETIS model with a pond trap efficiency model. The model was calibrated by adjusting some of its parameters in order to reproduce the total sediment volume accumulated behind a check dam. Then, the model was spatially validated by obtaining the simulated sedimentation volume at the other eight check dams and comparing it to the observed sedimentation volumes. Lastly, the simulated water discharge at the catchment outlet was compared with observed water discharge records in order to check the hydrological sub-model behaviour. Model results provided highly valuable information concerning the spatial distribution of soil erosion and sediment transport. Spatial validation of the sediment sub-model provided very good results at seven check dams out of nine. This study shows that check dams can be a useful tool also for constraining hydrological model calibration, as model results agree with water discharge observations. In fact, the hydrological model validation at a downstream water flow gauge obtained a Nash-Sutcliffe efficiency of 0.8. This technique is applicable to all catchments with presence of check dams, and only requires rainfall and temperature data and soil characteristics maps.

Bussi, Gianbattista; Francés, Félix

2014-05-01

198

SURFACE-SEDIMENT DIATOM ASSEMBLAGES IN SHALLOW, ARTIFICIAL, ENRICHED PONDS, AND IMPLICATIONS FOR RECONSTRUCTING TROPHIC STATUS  

Microsoft Academic Search

This paper examines the surface-sediment diatom assemblages of 31 shallow, artificial, enriched ponds in southeast England lying along a total phosphorus (TP) gradient (annual mean TP 25-646 ?g 1), with respect to their species composition, and the role of such waters in generating diatom-chemistry training sets for reconstructing lake nutrient status. Detrended Correspondence Analysis (DCA) was used to explore the

Helen Bennion

1995-01-01

199

Sediment accumulation and net storage determined by field observation and numerical modelling for an extensive tropical floodplain: Beni River, Bolivian Llanos  

NASA Astrophysics Data System (ADS)

Lowland floodplains in subsiding basins form major depocentres responsible for the storage and cycling of large quantities of fine sediment and associated nutrients and contaminants. Obtaining reliable estimates of sediment storage in such environments is problematic due to the high degree of spatial and temporal variability exhibited by overbank sediment accumulation rates, combined with the logistical difficulties inherent in sampling locations far away from the channel. Further complexity is added by the high channel mobility, which recycles sediment and reconfigures the relationships between channel and floodplain morphology, sediment transport and overbank sedimentation. Estimates of floodplain accretion can be derived using a range of numerical sedimentation models of varying complexity. However, data required for model calibration are rarely available for the vast floodplains associated with tropical rivers. We present results from a study of channel-floodplain sediment exchange fluxes on the Rio Beni, a highly dynamic, tropical sand-bed tributary of the Amazon in northern Bolivia. The Beni transports high concentrations of suspended sediment, generated in the river's Andean headwaters, and disperses this material across an extensive floodplain wetland that experiences annual inundation over an area of up to 40000 km2. We utilise estimates of overbank sedimentation rates over the past century derived from 210Pb analysis of floodplain sediment cores collected along a 375 km length of channel, including sampling a range of channel-floodplain configurations within the channel belt and on the distal floodplain (up to 60 km from the channel). These data are used to investigate spatial and temporal variations in rates of floodplain sediment accumulation for a range of grain sizes. Specifically, we examine relationships between sedimentation rate and distance from the channel, and characterise within channel belt variability in sedimentation linked to patterns of channel migration and associated levee reworking. Field data are used to inform a hydrodynamically-driven model of overbank sedimentation and to derive uncertainty-bounded estimates of total floodplain sediment accumulation. Sediment exchange due to planform channel mobility is quantified using a numerical model of meander migration, calibrated using analysis of remote sensing imagery to determine rates and geometry of channel migration. Our combined data and model analysis allows the construction of a mean annual sediment budget for the Beni, which suggests channel-sediment exchange fluxes in the order of 100 Mt a-1, equivalent to 10% of the sediment load of the mainstem Amazon.

Schwendel, Arved; Aalto, Rolf; Nicholas, Andrew

2014-05-01

200

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...

201

Background radioactivity in sediments near Los Alamos, New Mexico.  

PubMed

River and reservoir sediments have been collected annually by Los Alamos National Laboratory since 1974 and 1979, respectively. These background samples are collected from five river stations and four reservoirs located throughout northern New Mexico and southern Colorado. Analyses include 3H, 90Sr, 137Cs, total U, 238Pu, 239,240Pu, 241Am, gross alpha, gross beta, and gross gamma radioactivity. Surprisingly, there are no federal or state regulatory standards in the USA that specify how to compute background radioactivity values on sediments. Hence, the sample median (or 0.50 quantile) is proposed for this background because it reflects central data tendency and is distribution-free. Estimates for the upper limit of background radioactivity on river and reservoir sediments are made for sampled analytes using the 0.95 quantile (two-tail). These analyses also show that seven of ten analytes from reservoir sediments are normally distributed, or are normally distributed after a logarithmic or square root transformation. However, only three of ten analytes from river sediments are similarly distributed. In addition, isotope ratios for 137Cs/238Pu, 137Cs/239,240Pu, and 239,240Pu/238Pu from reservoir sediments are independent of clay content, total organic carbon/specific surface area (TOC/SSA) and cation exchange capacity/specific surface area (CEC/SSA) ratios. These TOC/SSA and CEC/SSA ratios reflect sediment organic carbon and surface charge densities that are associated with radionuclide absorption, adsorption, and ion exchange reactions on clay mineral structures. These latter ratio values greatly exceed the availability of background radionuclides in the environment, and insure that measured background levels are a maximum. Since finer-grained reservoir sediments contain larger clay-sized fractions compared to coarser river sediments, they show higher background levels for most analytes. Furthermore, radioactivity values on reservoir sediments have remained relatively constant since the early 1980s. These results suggest that clay contents in terrestrial sediments are often more important at concentrating background radionuclides than many other environmental factors, including geology, climate and vegetation. Hence, reservoirs and floodplains represent ideal radionuclide sampling locations because fine-grained materials are more easily trapped here. Ultimately, most of these differences still reflect spatial and temporal variability originating from global atmospheric nuclear weapons testing and disintegration of nuclear-powered satellites upon atmospheric reentry. PMID:15207580

McLin, Stephen G

2004-07-26

202

Total Quality Leadership  

NASA Technical Reports Server (NTRS)

More than 750 NASA, government, contractor, and academic representatives attended the Seventh Annual NASA/Contractors Conference on Quality and Productivity. 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 (TQM). The presentations from the conference are summarized.

1991-01-01

203

Aquatic Sediments.  

ERIC Educational Resources Information Center

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

Sanville, W. D.; And Others

1978-01-01

204

Moraine Sediments  

NSDL National Science Digital Library

In this assignment students look at the provenance of glacial sediments and the size and shape of clasts to investigate the sources of moraine material and what happens as glaciers transport sediment. Students visit the field site to see sediment in place, collect a sample to sort in the lab, and compile and review a geologic map in ArcGIS.

Tranel, Lisa

205

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...

206

The value of manual, event-based sediment sampling in local-scale sediment budget studies  

NASA Astrophysics Data System (ADS)

Many contemporary sediment-budget studies lack two things: a first-hand understanding of the behavior of the system, and high-frequency data during storm events. In a study designed to understand sediment source areas, we have approach these deficiencies through manual sampling, almost exclusively during storm events. Manual sampling leads to better understanding. Frequently, the researcher finds oneself standing in streams observing phenomenon that contradict their a priori, desktop, or textbook-based perception of system behaviour. The case study we present reflects this in its observations of very high percolation rates, differing levels of land-stream connectivity under different sized events, and landowner intervention in water and sediment flux. In drier regions with episodic rainfall, event sampling is essential. During one season, we sampled 13 sites in a 316 km2 watershed about 50 times each. The sampling times were targeted to observe the start of the rising stage, many points immediately around the hydrograph peak, once or twice during the falling stage, and once after the return to pre-event conditions. The same number of samples spread over the year at regular intervals would lead to a grossly inaccurate representation of the system by the data. For example, event sampling permitted a reasonably accurate characterization of total annual load at each site. A simple, static model was then used to apportion total loads to different land use sources, and in-channel sources.

Casagrande, J.; Watson, F.; Hager, J.; Anderson, T.; Newman, W.; Kozlowski, D.; Rocha, A.; Cole, W.; Larson, J.; Feikert, B.; Oakins, A.; Pierce, L.; Curry, B.

2001-12-01

207

Sediment transport by streams in the Palouse River basin, Washington and Idaho, July 1961-June 1965  

USGS Publications Warehouse

The Palouse River basin covers about 3,300 square miles in southeastern Washington and northwestern Idaho. The eastern part of the basin is composed of steptoes and foothills which are generally above an altitude of 2,600 feet; the central part is of moderate local relief and is mantled chiefly by thick loess deposits; and the western part is characterized by low relief and scabland topography and is underlain mostly by basalt. Precipitation increases eastward across the study area. It ranges annually from 12 to 18 inches in the western part and from 14 to 23 inches in the central part, and it exceeds 40 inches in the eastern part. Surface runoff from the basin for the 4-year period of study (July 1961-June 1965) averaged 408,000 acre-feet per year, compared with 445,200 acre-feet per year for the 27-year period of record. The eastern part of the basin contributed about 55 percent of the total, whereas the central and western parts contributed 37 percent and 8 percent, respectively. Most sediment transport from the Palouse River basin and the highest sediment concentrations in streams occurred in the winter. Of the several storms during the study period, those of February 3-9, 1963, December 22-27, 1964, and January 27-February 4, 1965, accounted for 81 percent of the total 4-year suspended-sediment load; the storm of February 3-9, 1963, accounted for nearly one-half the total load. The discharge-weighted mean concentration of suspended sediment carried in the Palouse River past Hooper during the study period was 2,970 milligrams per liter. The average annual sediment discharge of the Palouse River at its mouth was about 1,580,000 tons per year, and the estimated average annual sediment yield was 480 tons per square mile. The yield ranged from 5 tons per square mile from the western part of the basin to 2,100 tons per square mile from the central part. The high yield from the central part is attributed to a scarcity of vegetal cover, to the fine-grained loess soils, and to rapid runoff during winter storms. Sediment yield from the eastern part of the basin ranged from 460 to more than 1,000 tons per square mile. During high flow, silt particles make up the largest part of the suspended-sediment load, whereas during low flow, clay particles represent the greatest part. On the average, the suspended sediment transported by the Palouse River past Hooper contained 3 percent sand, 68 percent silt, and 29 percent clay. Unmeasured sediment discharge was estimated to have been 5 percent of the total sediment discharge. Data collected during the 4-year period of study show that sediment loads were higher than those recorded by V. G. Kaiser during the longer period 1939-65. Whereas Kaiser's study showed an average annual soil loss of 9.6 million tons, the average annual loss during the recent study was 14.2 million tons. The factor that has had the greatest effect on the increase of sediment yields is land use. Lands once covered and protected by natural vegetation have been extensively, cultivated, and much of the soil has become susceptible to erosion, particularly in areas mantled by loessal soils.

Boucher, P. R.

1970-01-01

208

RIVER3: Simulation of river discharge and sediment transport  

NASA Astrophysics Data System (ADS)

RIVER3 is an ANSI standard FORTRAN-77 numerical model that simulates the discharge and sediment load of rivers. From basic data on climate, hinterland geometry, and river characteristics, the model predicts four contributions to river flow (nival melt, ice melt, rainfall, and groundwater). Input parameters include annual rainfall and snowfall, seasonal evaporation, days per month with measurable rainfall, days per month with temperatures exceeding 5, 10, and 20 °C, topography, glacier equilibrium line altitude, seasonal freezing line altitude, areal extent of lakes, sediment transport, and erosion coefficients. The model has both deterministic and stochastic elements for the simulation of daily flow and channel size, and the transport rates for five sediment size fractions (from clay to gravel). The model is deterministic in that given an input file, which includes a random seed number used to determine the magnitude and occurrence of a particular rainfall or snow or ice-melt event, the predicted stream hydrograph will be the same. The model is stochastic in that for each subsequent year being simulated, a different random number operator is used and a different hydrograph is predicted, although the total discharge related to ice melt, snow melt, rainfall, and baseflow is conserved. Model output includes interannual variation of a river's discharge history and sediment transport, and an input file for basin-fill models (DELTA and GRAIN) already in use. RIVER3 is able to offer a variety of applications for the study of regional climatic change (past or future) on fluid discharge and sediment processes.

Syvitski, J. P. M.; Alcott, J. M.

1995-02-01

209

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

USGS Publications Warehouse

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.

Biedenbach, James M.

2011-01-01

210

The mobilisation potential of trace metals in aquatic sediments as a tool for sediment quality classification  

Microsoft Academic Search

Heavy metal contents and distributions in aquatic sediments in the Belgian rivers Dommel, a well oxygenated, non-navigable river with sandy bottom sediments, and Bovenschelde, a suboxic, frequently dredged river with muddy anoxic sediments, were assessed. To that aim two methods were used: firstly, pore water and total sediment analyses and secondly, sequential extraction experiments, providing the following operationally defined speciation

Ramses van Ryssen; Martine Leermakers; Willy Baeyens

1999-01-01

211

Surface-water and suspended-sediment inflow and outflow for Nutria Reservoir No 3, Zuni Indian Reservation, New Mexico, March 1994 to September 1995  

USGS Publications Warehouse

Surface-water and suspended-sediment inflow to and outflow from Nutria Reservoir No. 3 on the Zuni Indian Reservation, western New Mexico, were calculated. The period of study was March 3, 1994, to September 30, 1995. Total runoff into Nutria Reservoir No. 3 during the study period was 6,812 acre-feet. During the study period, 24,310 tons of suspended sediment was transported into Nutria Reservoir No. 3, and 259 tons of suspended sediment was transported out of Nutria Reservoir No. 3. Runoff during the study period, recorded at an upstream gage with 25 years of record, was 137 percent higher than that for a 19-month period similar to the study period. This may indicate that suspended-sediment loads transported into Nutria Reservoir No. 3 also were larger than average. Based on the difference between inflow and outflow of suspended sediment, 24,050 tons of suspended sediment was deposited in Nutria Reservoir No. 3. From March 1994 to May 1994 the spillway elevation of Nutria Reservoir No. 3 was raised to allow water to be diverted into an adjacent reservoir, Nutria Reservoir No. 4. This flow and sediment transported into Nutria Reservoir No. 4 were not recorded. If the elevation of the spillway had not been raised, suspended- sediment loads recorded downstream from Nutria Reservoir No. 3 would have been larger and the calculated amount of sediment deposited in Nutria Reservoir would have been smaller. Of the total suspended-sediment load entering Nutria Reservoir No. 3 during the study period, 94 percent was transported by an arroyo, Garcia Draw. Garcia Draw drains only 15 percent of the total drainage area of Nutria Reservoir No. 3 and contributed less than 5 percent of the total surface runoff to the reservoir. The average annual amount of sediment deposited in Nutria Reservoir No. 3 during the study was 15,355 tons. By using a dry-weight density of 99.4 pounds per cubic foot for the deposited sediment, the annual volume of sediment deposited in Nutria Reservoir No. 3 is 7.09 acre-feet per year. This number is smaller than the previously reported sedimentation rate of 15.0 acre-feet per year obtained from past surveys. The capacity of Nutria Reservoir No. 3 in 1993 was 191 acre-feet. By using the calculated average sedimentation rate of 7.09 acre-feet per year, Nutria Reservoir No. 3 could be completely filled approximately 27 years after the 1993 survey.

Gellis, A. C.

1998-01-01

212

Annual report of 1995 groundwater monitoring data for the Kerr Hollow Quarry and Chestnut Ridge Sediment Disposal Basin, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee  

SciTech Connect

The Kerr Hollow Quarry (KHQ) and the Chestnut Ridge Sediment Disposal Basin (CRSDB) are inactive waste management sites located at the Oak Ridge Y-12 Plant. The KHQ and CRSDB are regulated as treatment, storage, or disposal (TSD) facilities under the Resource Conservation and Recovery Act (RCRA). The facilities were granted interim status in calendar year (CY) 1986 under Tennessee Department of Environment and Conservation (TDEC) Hazardous Waste Management Rule 1200-1-11-.05. Historical environmental monitoring data and baseline characterization under interim status indicated that releases of contaminants to groundwater had not occurred; thus, the detection monitoring was implemented at the sites until either clean closure was completed or post-closure permits were issued. The CRSDB was closed in Cy 1989 under a TDEC-approved RCRA closure plan. A revised RCRA PCPA for the CRSDB was submitted by DOE personnel to TDEC staff in September 1994. A final post-closure permit was issued by the TDEC on September 18, 1995. Closure activities at KHQ under RCRA were completed in October 1993. The Record of Decision will also incorporate requirements of the RCRA post-closure permit once it is issued by the TDEC.

NONE

1996-02-01

213

Distributed Hydrology Soil Vegetation Model (DHSVM) and Sediment Discharge in a Small, Timber Production Watershed, Humboldt County, California  

NASA Astrophysics Data System (ADS)

Sediment impacts to streams and rivers, either as suspended sediment concentration (SSC), or as aggradation, are well documented in the Pacific Northwest. Fishery stocks, estuarine, infrastructural and wildland resources can be negatively impacted. The causes and reasons for sedimentation of river resources are varied and diverse: tectonic setting - the relative rapid uplift of the study region produces a dominant erosional process of landsliding and mass wasting; regolithic setting - the relatively recent uplift of marine sediments has produced local formations of poorly and moderately consolidated soils, and lithic melanges that are naturally susceptible to erosion; climatic/geographic setting - coastal locations are subject to seasonal delivery of a relatively high average annual precipitation serving to transport available sediment; and finally, management setting - the activities that serve to make sediment available for transport to the river channel, forest road building and harvesting activities associated with timber production, agriculture, gravel mining, and fire management. The reduction of sediment loading can be accomplished through restoration activities like forest road decommissioning or riparian area revegetation. The need to prioritize restoration efforts is confounded by a lack of hydrographic and sediment discharge data, the complex terrain, and the inability to predict the effects of these activities on a dynamic scale. The Distributed Hydrology Soil Vegetation Model (DHSVM) has been developed to model watersheds using spatially explicit geographical data coupled with physically based hydrologic equations. DHSVM simulates watershed processes across a grid on a cell-by-cell manner. The most recent development within the DHSVM includes a mass wasting / sediment production and channel routing module which allows prediction of total sediment loading in a forest basin. We are applying DHSVM to the McReady sub-basin of Freshwater Creek, Humboldt County, California, utilizing site specific precipitation, hydrographic, and sediment data. Hydrographic and sediment discharge data from 2002 to present are used to train and validate the model. A detailed sediment source inventory from both the road and stream courses further informs the model process and parameterization of sediment production and mobilization within the watershed. The availability of continuous discharge and sediment loading via turbidity threshold stations (TTS) allows validation of the model's performance on multiple levels: average annual, monthly, or weekly sediment loading, and on an event by event basis. Effective validation permits the use of the model to understand the effects of future management strategies, i.e. timber harvest, road construction or decommissioning on a site-specific basis, and to model landscape effects of wildfire and climate change scenarios on watershed functions.

Stubblefield, A.; Huggett, B.; Sullivan, K.; Dhakal, A.

2008-12-01

214

Sediment Loads and Yield, and Selected Water-Quality Parameters in Clear Creek, Carson City and Douglas County, Nevada, Water Years 2004-07  

USGS Publications Warehouse

Some reaches of Clear Creek above U.S. Highway 395 have experienced severe erosion as a result of fires, extreme precipitation events, and past and current human activities in the basin. Previous evaluations of erosion in the basin have concluded that most of the sediment produced and transported in the basin was associated with U.S. Highway 50, a four-lane highway that roughly parallels Clear Creek through much of the basin. During this study (water years 2004-07), construction of roads and a large residential area and golf course in the area began and are likely to affect water quality and sediment transport in the basin. Sediment data were collected between October 2003 and September 2007 (water years 2004-07) from three sites along Clear Creek. Annual suspended-sediment load was estimated to range from 1,456 tons in water year 2006 to only 100 tons in water year 2004, which corresponds to suspended-sediment yields of 93.9 tons per square mile per year in 2006 to 6.4 tons per square mile per year in 2004. In water year 2006, the suspended-sediment load on December 31, 2005, alone exceeded the combined annual load for water years 2004, 2005, and 2007. Bedload sediment was estimated to comprise 73 percent of total sediment load in the creek. Mean annual suspended-sediment yield in Clear Creek basin was much greater than yields in the Logan House, Edgewood, and Glenbrook Creek basins in the adjacent Lake Tahoe basin. Comparison of data collected during this study with data collected by university researchers in the 1970s is inconclusive as to whether fundamental changes in basin sediment characteristics have occurred during the 30-year period because different methods and sampling locations were used in the earlier studies.

Seiler, Ralph L.; Wood, James L.

2009-01-01

215

Studies of the photoelectrochemistry of organic dyes using attenuated total-reflection techniques. Annual progress report, June 1, 1981-May 31, 1982  

SciTech Connect

A laser total internal reflection system (laser IRS) has been used to study the photooxidation of cyanine dyes at ZnO, TiO/sub 2/, and SrTiO/sub 3/ single crystal electrodes. The quantum efficiency for photocurrent production, phi/sub p/, was found to be approx. 10/sup -3/ at these electrodes for the monomer form of the dye. Aggregates of the dyes were also found to play a significant role with an oxidation mechanism which differs from the monomer. Energetic thresholds for electron injection into the semiconductor predicted by theory were confirmed for SrTiO/sub 3/ and TiO/sub 2/. A spectroelectrochemical total internal reflection spectroscopy system (spectroelectrochemical IRS) has been constructed to study the photooxidation of triphenylmethane dyes at gold electrodes. Experimentation with this system is in progress.

Spitler, M.T.

1982-01-01

216

Light fraction organic N, ammonium, nitrate and total N in a thin Black Chernozemic soil under bromegrass after 27 annual applications of different N rates  

Microsoft Academic Search

Anadequate supply of N for a crop depends among others on the amounts of N thataremineralized from the soil organic matter plus the supply of ammonium andnitrateN already present in the soil. The objective of this study was to determine thebehaviour of light fraction organic N (LFN), NH4-N, NO3-Nand total N (TN) in soil in response to different rates of

S. S. Malhi; K. S. Gill; J. T. Harapiak; M. Nyborg; E. G. Gregorich; C. M. Monreal

2003-01-01

217

Effects of urbanization on streamflow and sediment transport in the Rock Creek and Anacostia River basins, Montgomery County, Maryland, 1962-74  

USGS Publications Warehouse

Land use, precipitation, streamflow, and sediment discharge data were collected from nine small drainage basins in Montgomery County, Maryland, to evaluate runoff and sediment response to sediment-control practices in areas undergoing urban development. Drainage basins ranged in size from 0.35 to 21.1 sq mi and land use ranged from rural to 60 percent urban. Urbanization did not affect low and medium flows, but it did result in increased storm runoff and peak flows. Suspended sediment transported from one of the basins that underwent urban development, the 21.1 sq mi Anacostia River basin, averaged 15 ,400 tons/yr between 1962 and 1974. Bedload was estimated as 5 to 11 percent of the total load. Cropland, urban land, and construction sites were the major sources of sediment. Average annual sediment yields ranged from 065 to 4.3 tons/acre for cropland, 3.7 tons/acre for urban land, and 7 to 100 tons/acre for urban construction sites. The magnitude of the yields from construction sites was significantly affected by (1) the slope of the sites, (2) the proximity of stream channels, (3) buffer zones of natural vegetation, and (4) sediment-control measures. Sediment controls, particularly those enforced under a 1971 sediment-control ordinance, apparently decreased construction-site sediment yields by 60 to 80 percent. (Woodard-USGS)

Yorke, Thomas H.; Herb, William J.

1978-01-01

218

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

USGS Publications Warehouse

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.

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

2013-01-01

219

Simulation of contaminated sediment transport in White Oak Creek basin  

SciTech Connect

This paper presents a systematic approach to management of the contaminated sediments in the White Oak Creek watershed at Oak Ridge National Laboratory near Oak Ridge, Tennessee. The primary contaminant of concern is radioactive cesium-137 ({sup 137}Cs), which binds to soil and sediment particles. The key components in the approach include an intensive sampling and monitoring system for flood events; modeling of hydrological processes, sediment transport, and contaminant flux movement; and a decision framework with a detailed human health risk analysis. Emphasis is placed on modeling of watershed rainfall-runoff and contaminated sediment transport during flooding periods using the Hydrologic Simulation Program- Fortran (HSPF) model. Because a large number of parameters are required in HSPF modeling, the major effort in the modeling process is the calibration of model parameters to make simulation results and measured values agree as closely as possible. An optimization model incorporating the concepts of an expert system was developed to improve calibration results and efficiency. Over a five-year simulation period, the simulated flows match the observed values well. Simulated total amount of sediment loads at various locations during storms match with the observed values within a factor of 1.5. Simulated annual releases of {sup 137}Cs off-site locations match the data within a factor of 2 for the five-year period. The comprehensive modeling approach can provide a valuable tool for decision makers to quantitatively analyze sediment erosion, deposition, and transport; exposure risk related to radionuclides in contaminated sediment; and various management strategies.

Bao, Y.; Clapp, R.B.; Brenkert, A.L. [Oak Ridge National Lab., TN (United States); Moore, T.D. [Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN (United States); Fontaine, T.A. [Department of Civil and Environmental Engineering, South Dakota School of Mines and Technology, Rapid City, SD (United States)

1995-12-31

220

Studies of the photoelectrochemistry of organic dyes using attenuated total-reflection techniques. Annual progress report, June 1, 1982-May 31, 1983  

SciTech Connect

Using a laser total internal reflection system (laser IRS), the energetic threshold has been mapped for photocurrent sensitized excited singlet dye molecules adsorbed on the surface of SrTiO/sub 3/ single crystals. The results, obtained in terms of the quantum efficiency of photocurrent production (phi), are compared with theory and implications summarized. Data are presented from an initial study of the photoxidation of triphenylmethane dyes at gold electrodes which utilized spectroelectrochemical internal reflection spectroscopy (spectroelectrochemical IRS). The progress in new dye sensitization experiments with triplets and dye aggregates is outlined.

Spitler, M.T.

1983-01-01

221

Studies of the photoelectrochemistry of organic dyes using attenuated total reflection techniques. Annual progress report, June 1, 1983-May 31, 1984  

SciTech Connect

Employing two experimenal arrangements of internal reflection spectroscopy, work has been completed which define the energetic threshold for sensitized photocurrent and explore the photochemistry of J aggregate sensitization of semiconductor electrodes by cyanine dyes. The threshold measurements were made using a laser total internal reflection system (laser ATR); the aggregate experiments were done using internal reflection spectroscopy with white light (spectroelectrochemical IRS). A summary is made of the progress in measurements with H-band aggregates of cyanine dyes and triplet state studies with xanthene dyes. The direction of research during the remainder of the contract year is outlined.

Spitler, M.T.

1983-11-01

222

Nitrogen and phosphorus flux rates from sediment in the lower St. Johns River estuary.  

PubMed

Internal cycling of nutrients from the sediment and water column can be an important contribution to the total nutrient load of an aquatic ecosystem. Our objective was to estimate the internal nutrient loading of the Lower St. Johns River (LSJR). Dissolved reactive phosphorus (DRP) and ammonium (NH(4)-N) flux from sediments were measured under aerobic and anaerobic water column conditions using intact cores, to estimate the overall contribution of the sediments to P and N loading to the LSJR. The DRP flux under aerobic water column conditions averaged 0.13 mg m(-2) d(-1), approximately 37 times lower than that under anaerobic conditions (4.77 mg m(-2) d(-1)). The average NH(4)-N released from the anaerobic cores (18.03 mg m(-2) d(-1)) was also significantly greater than in the aerobic cores for all sites and seasons, indicating the strong relationship between nutrient fluxes and oxygen availability in the water column. The mean annual internal DRP load was estimated to be 330 metric tons (Mg) yr(-1), 21% of the total P load to the river, while the mean annual internal load of NH(4)-N was determined to be 2066 Mg yr(-1), 28% of the total N load to the LSJR estuary. As water resource managers reduce external loading to the LSJR the frequency of anaerobic events should decline, thereby reducing nutrient fluxes from the sediment to the water column, reducing the internal loading of DRP and NH(4)-N. Results from this study demonstrate that the internal flux of nutrients from sediments may be a significant portion of the total load and should be accounted for in the total nutrient budget of the river for successful restoration. PMID:15254137

Malecki, Lynette M; White, John R; Reddy, K R

2004-01-01

223

Aquatic sediments  

SciTech Connect

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.

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

1984-06-01

224

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

SciTech Connect

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.

Bao, Y.

1999-04-12

225

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

PubMed

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

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

2014-01-01

226

Sediment Production From Forest Road Surfaces  

NASA Astrophysics Data System (ADS)

Erosion on roads is an important source of fine-grained sediment in streams draining logged basins of the Pacific Northwest. Runoff rates and sediment concentrations from 10 road segments subject to a variety of traffic levels were monitored to produce sediment rating curves and unit hydrographs for different use levels and types of surfaces. These relationships are combined with a continuous rainfall record to calculate mean annual sediment yields from road segments of each use level. A heavily used road segment in the field area contributes 130 times as much sediment as an abandoned road. A paved road segment, along which cut slopes and ditches are the only sources of sediment, yields less than 1% as much sediment as a heavily used road with a gravel surface.

Reid, Leslie M.; Dunne, Thomas

1984-11-01

227

Multielement determination in sediments, pore water and river water of Upper Austrian rivers by total-reflection X-ray fluorescence 1 This paper was presented at the 6th Conference on “Total Reflection X-Ray Fluorescence Analysis and Related Methods” (TXRF '96) held in two parts in Eindhoven (The Netherlands) and Dortmund (Germany) in June 1996, and is published in the Special Issue of Spectrochimica Acta, Part B, dedicated to that Conference. 1  

Microsoft Academic Search

Multielement determination in sediments, pore water and river water has been carried out using total-reflection X-ray fluorescence (TXRF), electrothermal atomic absorption spectrometry (ETAAS) and hydride generation atomic absorption spectrometry (Hyd-AAS). TXRF in particular facilitates multielement determination by allowing easy quantification with internal one-element standardization, and is therefore central to these investigations. In connection with the simplicity of sample preparation an

Hermann Miesbauer

1997-01-01

228

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

229

The Assessment of Sediment Production Yield from Forest Road Using Sediment Prediction Model  

Microsoft Academic Search

Forest road construction is including high costs as if in operations of road construction the saving be inappropriate thus, it is following more damages. Therefore, this study was performed for estimate of annual sediment mean in a forest road network of forest watershed in southeast of Sari city (North of Iran) using a sediment prediction model with considering to the

Hossein Khalilpoor; Seyed Ataollah Hosseini; Majid Lotfalian; Yahya Kooch

2008-01-01

230

Prediction of sediment load by sediment rating curve and neural network (ANN) in El Kebir catchment, Algeria  

NASA Astrophysics Data System (ADS)

The annual sediment load of a river is generally determined either from direct measurements of the sediment load throughout the year or from any of the many sediment transport equations that are available today. Due to lack of a long-term sediment concentration data, sediment rating curves and flux estimation are the most widely applied. This paper has investigated the abilities of statistical models to improve the accuracy of streamflow-suspended sediment relationships in daily and annual suspended sediment estimation. In this study, a comparison was made between suspended sediment rating curves and artificial neural networks (ANNs) for the El Kebir catchment. Daily water discharge and daily suspended sediment data from the gauging station of Ain Assel, were used as inputs and targets in the models which were based on the cascade-forward and feed-forward back-propagation using Levenberg-Marquardt and Bayesian regularization algorithms. The model results have shown that the ANN models have the highest efficiency to reproduce the daily sediment load and the global annual sediment yields. Our estimation based on the available data indicated that the areas along the El Kebir River have experienced high sediment fluxes that could have obvious impacts on the sediment trapping and siltation in the Mexa reservoir.

Boukhrissa, Z. A.; Khanchoul, K.; Le Bissonnais, Y.; Tourki, M.

2013-10-01

231

Aquatic sediments  

SciTech Connect

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.

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

1990-06-01

232

Temporal and spatial variability of sediment flux into the sea from the three largest rivers in China  

NASA Astrophysics Data System (ADS)

The Yellow, Yangtze and Pearl Rivers supply over 90% of the sediment flux from China to the western Pacific Ocean. Trends and abrupt changes in the water discharge and sediment load of the three rivers were examined and compared based on data updated to the year 2011 at the seasonal and annual scales. The total water discharge from the three rivers shows a statistically insignificant decreasing trend with a rate of 0.62 × 109 m3/a, and the total sediment load shows a statistically significant decreasing trend at a rate of 31.12 × 106 t/a from the 1950s to 2011. The water discharge of the entire Yellow River and the upstream portion of the Yangtze River shows significant decreasing trends, and that of the mid-lower stream of Yangtze River and the entire Pearl River shows insignificant trends. The sediment loads in the three river basins all show significant decreasing trends at the annual and seasonal scales, and a dramatic decrease in the 2000s resulted in a more obvious decreasing trend over the studied period. From the 1950s to the 2000s, the contribution of sediment flux from the Yellow River to the ocean decreased from 71.8% to 37.0%, and the contributions of the Yangtze and Pearl Rivers increased from 24.2% and 4.0% to 53.0% and 10.0%, respectively. Inter-annual variations in water discharge and sediment load were affected by climate oscillations, such as the El Niño/Southern Oscillation, and the long-term decreasing trend in sediment load was primarily caused by human activities. Dam constructions and soil conservation projects were the major causes of sediment reduction. From the 1970s to the 2000s, the decrease in total sediment load from the three rivers caused by climate change and human activities was 2.24 × 108 t/a (23.0%) and 7.5 × 108 t/a (77.0%), respectively. In the coming decades, the sediment flux from the three rivers into the sea will decrease further with intensifying human activities, resulting in many challenges for the management of river basins and river deltas.

Liu, Feng; Yang, Qingshu; Chen, Shenliang; Luo, Zhifa; Yuan, Fei; Wang, Runtian

2014-06-01

233

Post Little Ice Age record of coarse and fine clastic sedimentation in an Alaskan proglacial lake  

Microsoft Academic Search

Many assessments of glacial sediment yield rely solely on measurements of fine-grained suspended sediment. We show that suspended sediment contributes <20% of the total clastic sediment discharge into Iceberg Lake, an Alaskan proglacial lake. Drainage of this lake in 1999 exposed outcrops of varved lacustrine sediment that record suspended sediment deposition. Since a Little Ice Age highstand two centuries ago,

Michael G. Loso; Robert S. Anderson; Suzanne P. Anderson

2004-01-01

234

Effects of low-level dams on the distribution of sediment, trace metals, and organic substances in the lower Schuylkill River basin, Pennsylvania  

USGS Publications Warehouse

Heavy use of the Schuylkill River for municipal water supplies and a history of accidental spills and discharges of trace metals and organic substances have been a concern of State and local officials for many years. The U.S. Geological Survey, as part of their River Quality Assessment Program, developed a study to assess the occurrence and distribution of trace substances that pose a threat to human health and aquatic life. This report presents the results of the part of the study that evaluates the effects of low-level dams in the lower basin on the distribution and transport of sediment and trace substances. A combination of historical and current data were used in the assessment. Suspended-sediment data collected at several mainstem and tributary sites from 1954 to 1979 and sedimentation surveys of the six pools in the lower basin were used to define the sediment-transport characteristics of the river. These data provided a base for assessing the transport of trace substances, which are associated closely with riverbed sediments and suspended particles. Water and riverbed samples were collected for analyses of trace substances at numerous sites in the lower basin from 1978 to 1980. The six dams on the river between Pottstown and Philadelphia have had a significant effect on the transport of sediment and trace substances. Between 1954 and 1970, more than 4.7 million cubic yards of sediment accumulated in the pools formed by the dams. The quantity of sediment deposited in the pools ranged from 150,000 cubic yards in Plymouth Pool to 1.6 million cubic yards in Fairmount Pool. The rate of accumulation in the pools was a function of pool size and geometry and the frequency of storms. About 35 percent of the total sediment discharged by the river was stored in the six pools from 1954 to 1970. Since 1970, the net change in sediment accumulation has been minimal. More than 24 percent of the sediment in Fairmount Pool in 1970 was scoured from the pool during Hurricane Agnes in 1972; however, total sediment accumulation returned to the 1970 level within 2 years. Analyses of water samples showed that some trace substances are associated closely with particulate material transported by the river. The concentration of suspended and total cadmium, chromium, copper, lead, nickel, and zinc correlated well with the concentration of suspended sediment and suspended organic carbon. The average annual discharge of metals in suspension as a percentage of total average annual discharge ranged from 46 percent for nickel to 94 percent for lead for the Schuylkill River at Manayunk. The average annual discharge of each metal remained about the same or decreased between Pottstown and Philadelphia. Synoptic sampling of the inflow and outflow of several pools during storm runoff showed that the pools limit the transport of trace metals. More than 50 percent of the suspended copper transported by the river at Pottstown was deposited in Vincent Pool during the storm of May 12-15, 1980. Similar reductions were observed between Port Kennedy and Manayunk as the storm runoff passed through Norristown, Plymouth, and Flat Rock Pools. Analyses of riverbed sediments showed that concentrations of trace substances were higher in sediments that included all particles finer than 0.062 millimeter than in sediments that included only particles finer than 0.016 millimeter. This suggests that medium and coarse silt particles or conglomerates of finer particles sorb as much or more trace constituents as the individual fine silts and clay particles. Concentrations of trace metals were as much as 90 percent higher in the sediments that included coarse silt. Concentrations of trace organic substances were several times higher in the sediments that included coarse silt than in sediments consisting of only fine silt or clay. Surficial and core samples of riverbed sediments were used to define the present and historical distribution of trace substances in

Yorke, Thomas H.; Stamer, John K.; Pederson, Gary L.

1985-01-01

235

Cumulative sediment reduction to the Lower Mekong River from planned dams  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

236

Flux estimates and sedimentation of polychlorinated naphthalenes in the northern part of the Baltic Sea.  

PubMed

The concentrations and fluxes of polychlorinated naphthalenes (PCNs) were measured in surface sediments, and settling particulate matter collected in sediment traps, at two coastal and two offshore sampling stations in the Gulf of Bothnia, northern Baltic Sea, Sweden. The PCN concentrations (of tetra- to hepta-chloro congeners) in the surface sediments ranged from 0.27 to 2.8 ng/g dry weight and were of the same order of magnitude as background concentrations reported previously in Europe. The PCN fluxes in the southern basin (0.93 and 0.86 microg/m2/year) of the Gulf of Bothnia were higher than those in the northern basin (0.58 and 0.49 microg/m2/year); they were also higher near the coast than in the open sea. These PCN fluxes are similar to the pre-industrial levels determined from lake sediments in northwest England. The PCN homologue distribution changed from a relatively even distribution in samples collected near the coast, to TeCNs dominating in the samples from the open sea. This indicates that higher chlorinated PCNs are deposited and retained in sediments to a higher degree near the coast. The total annual deposition of PCNs in sediments in the Gulf of Bothnia was estimated to be 91 kg/year. PMID:12860106

Lundgren, Kjell; Tysklind, Mats; Ishaq, Rasha; Broman, Dag; van Bavel, Bert

2003-01-01

237

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

USGS Publications Warehouse

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)

Eckhardt, David A. V.

1976-01-01

238

Comparison of sediment supply to San Francisco Bay from watersheds draining the Bay Area and the Central Valley of California  

USGS Publications Warehouse

Quantifying suspended sediment loads is important for managing the world's estuaries in the context of navigation, pollutant transport, wetland restoration, and coastal erosion. To address these needs, a comprehensive analysis was completed on sediment supply to San Francisco Bay from fluvial sources. Suspended sediment, optical backscatter, velocity data near the head of the estuary, and discharge data obtained from the output of a water balance model were used to generate continuous suspended sediment concentration records and compute loads to the Bay from the large Central Valley watershed. Sediment loads from small tributary watersheds around the Bay were determined using 235 station-years of suspended sediment data from 38 watershed locations, regression analysis, and simple modeling. Over 16 years, net annual suspended sediment load to the head of the estuary from its 154,000 km2 Central Valley watershed varied from 0.13 to 2.58 (mean = 0.89) million metric t of suspended sediment, or an average yield of 11 metric t/km2/yr. Small tributaries, totaling 8145 km2, in the nine-county Bay Area discharged between 0.081 and 4.27 (mean = 1.39) million metric t with a mean yield of 212 metric t/km2/yr. The results indicate that the hundreds of urbanized and tectonically active tributaries adjacent to the Bay, which together account for just 5% of the total watershed area draining to the Bay and provide just 7% of the annual average fluvial flow, supply 61% of the suspended sediment. The small tributary loads are more variable (53-fold between years compared to 21-fold for the inland Central Valley rivers) and dominated fluvial sediment supply to the Bay during 10 out of 16 yr. If San Francisco Bay is typical of other estuaries in active tectonic or climatically variable coastal regimes, managers responsible for water quality, dredging and reusing sediment accumulating in shipping channels, or restoring wetlands in the world's estuaries may need to more carefully account for proximal small urbanized watersheds that may dominate sediment supply.

McKee, L. J.; Lewicki, M.; Schoellhamer, D. H.; Ganju, N. K.

2013-01-01

239

A budget of bioavailable inorganic phosphorus in the sediment for the western Wadden Sea  

NASA Astrophysics Data System (ADS)

This paper provides quantitative and qualitative information on the sediment P pool for the western Wadden Sea. Total extractable P concentrations in the sediment were lower than 4 ?mol g- 1, with the exception of a depositional area of fine sediment where P concentrations reached 45 ?mol g- 1. Most P was in a non-bioavailable form, with the bioavailable inorganic fraction corresponding to 12-42% of the total extractable pool and being mainly composed of Fe-bound P. A strong negative relationship between median grain size and bioavailable inorganic P content was found based on which a budget was calculated for the periods of maximum (February/March) and minimum (November) content of bioavailable inorganic P in the top 9 cm's of sediment. The sediment P budget decreased from 1.0 × 108 mol in February/March to 0.6 × 108 mol in November. Assuming that the seasonal difference was due to the release to the overlying water, an exchange of 4.0 × 107 mol of P was estimated, which has the potential to fuel approximately 40% of the current annual primary production of ~ 200 g C m- 2.

Leote, Catarina; Mulder, Lieke; Epping, Eric

2014-03-01

240

Sediment Transport  

NSDL National Science Digital Library

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

Williams, Karen

241

Quantifying the origin of different sediment types in a catchment of the Southern French Alps by combining hydro-sedimentary records and fingerprinting  

NASA Astrophysics Data System (ADS)

Soil erosion and subsequent sediment supply to rivers are particularly massive and episodic in mountainous environments, such as in the Southern French Alps. Those processes typically lead to an increase in water turbidity and a rapid filling of reservoirs in downstream areas. This situation is particularly problematic in regions where reservoirs are used to provide clear water to hydroelectric power plants. Sediment source areas must first be delineated and sediment fluxes between hillslopes and the river system must be better understood to implement efficient sediment management. We therefore combined traditional monitoring techniques (i.e., installation of river gauges and sediment samplers in several subcatchments) and sediment fingerprinting using elemental geochemistry and fallout radionuclides as potential discriminant properties to quantify the supply of sediment provided by different lithological sources (i.e., black marls, marly limestones, conglomerates, Quaternary deposits) to the River Bléone (905 km²). Those analyses were conducted on different material types collected within the catchment (i.e. suspended and riverbed sediment), and at the catchment outlet (i.e. on a sequence of sections of a 3-m long sediment core). Sediment exports at the river catchment outlet (330±100 t km-2 yr-1) were mainly driven (80%) by the occurrence of widespread rainfall events (long duration, low intensities). In contrast, heavy, local and short duration storms generated high peak discharges and suspended sediment concentrations, but they were restricted to small upstream torrents. Our study (2007-2009) confirmed the important contribution of black marls (up to 70% at the flood scale) to sediment transported in rivers, although this substrate only occupies c. 10% of the total catchment surface. However, the contribution of other lithological sources varied at both intra- and inter-flood scales. Sediment exports generated by local convective storms were dominated by black marls/marly limestones. In contrast, widespread flood events that generate the bulk of annual sediment supply at the outlet were characterized by a more stable lithologic composition and by a larger contribution of limestones, Quaternary deposits and conglomerates, which corroborated the analysis of riverbed sediment. Finally, we found that black marls and marly limestone sources provided the main fraction of sediment analysed throughout the outlet core sequence (40 and 22 %, respectively, for the period 1962-2009). However, we also found evidence for the occurrence of major floods carrying large quantities of sediment originating from Quaternary deposits and conglomerates (25 and 16 %, respectively). The variability of sediment sources throughout the sequence may reflect the spatial variability of rainfall within the catchment, which in turn reflects its origin. This study emphasizes the importance of using archival data to validate the results of sediment fingerprinting studies conducted during short contemporary monitoring programmes.

Evrard, Olivier; Navratil, Oldrich; Ayrault, Sophie; Esteves, Michel; Legout, Cédric; Némery, Julien; Lefèvre, Irène; Bonté, Philippe

2013-04-01

242

Sediment storage and yield in an urbanized karst watershed  

NASA Astrophysics Data System (ADS)

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

Hart, Evan A.; Schurger, Stephen G.

2005-08-01

243

River discharge, sediment transport and exchange in the Tana Estuary, Kenya  

NASA Astrophysics Data System (ADS)

This study focuses on sediment transport and exchange dynamics in the 27 km 2 Tana Estuary located at Kipini in the north Kenya coast. The estuary is drained by the Tana River, which contributes more than 50% of the total river discharges into the Kenyan sector of the Indian Ocean. The study involved measurement of river discharges, estuarine flood-ebb tidal discharges, total and particulate organic suspended sediment concentrations (TSSC, POSC) and fluxes, tidal water elevation, current velocities, temperature and salinity. The study was conducted between February 2001 and November 2003. The results of the study showed that the Tana River discharge ranged between 60 and 750 m 3 s -1. The maximum river discharges during the Southeast and Northeast monsoons were 750 and 350 m 3 s -1, respectively. The peak river discharges occurred in May and November. The total daily sediment load of the Tana River varied from 2796 tons day -1 during the dry season to 24,322 tons day -1 during the rainy season. The annual total sediment load is 6.8 × 10 6 tons yr -1, which is, however, smaller than that before the damming of the river in the Upper Tana Basin. Because of river discharge and occurrence of a wide mangrove wetland, the estuary is mainly ebb tide dominant. The peak ebb tide currents (0.87 m s -1) were 30% larger than the peak flood tide currents (0.65 m s -1). During spring tide, the estuary was partially well mixed. However, in neap tide, the estuary was stratified in the middle zone. The turbidity maximum zone with TSSC > 1.5 g l -1 was generated in spring tide by wave stirring of frontwater zone bed sediments and trapping of fine sediments at the toe of the salt wedge. The peak TSSC ranging from 1.5 to 5.0 g l -1 occurred at low tide due to river supply of sediment and resuspension of channel bed sediments by wind waves, particularly at the last stages of ebb tide and early stages of flood tide. Due to the influx of oceanic water into the estuary at flood tide TSSC decreased to <0.2 g l -1 at high tide in the frontwater zone and was larger in the backwater zones of the estuary. The estuary exports sediments at a rate ranging from 0.02 to 0.08 kg m -2 tidal cycle -1. The net export of sediments causes a net denudation of the estuary at a rate ranging from 0.08 to 0.04 mm tidal cycle -1.

Kitheka, J. U.; Obiero, M.; Nthenge, P.

2005-05-01

244

Sediment Yields and Sediment Sources in the Chesapeake Bay Watershed  

NASA Astrophysics Data System (ADS)

Fine-grained sediment is having an adverse effect on the living resources and habitat of the Chesapeake Bay and its watershed. In order to reduce sediment inputs to the Bay, it is necessary to quantify erosion rates and sediment yields and identify the significant sources of fine-grained sediment. Sediment sources in the Chesapeake Bay watershed were identified using different methods at several scales. At the Chesapeake Bay scale (165,800 km2), U.S. Geological Survey suspended-sediment data collected from 1985 through 2001 for 35 stations showed that 4 of the 6 highest sediment yields were in the Conestoga River Basin, Pennsylvania, which drains to the Susquehanna River. In the Susquehanna River Basin (70,190 km2), erosion rates were determined using atmospheric 10Be at 92 river outlets and confirmed that the highest rates of erosion were in the Conestoga River Basin. In three small watersheds draining to the Chesapeake Bay -- the Pocomoke River (157 km2), Little Conestoga Creek (109 km2), and Mattawoman Creek (142 km2) -- sediment sources were identified using a sediment-fingerprinting approach. In this approach, the sources of fine-grained suspended sediment in transport can be established by comparing physical and chemical properties of the suspended sediment to potential sources. In this study, suspended sediment (< 0.062 mm) collected during storm runoff was compared to upland sediment sources (cropland, construction sites, and forest) and channel corridor sources (channel banks and bed) using radionuclides (210Pb, 137Cs), stable isotopes (13C, 15N), and total C, N, and P. Preliminary results are available for two of the three watersheds. In the Pocomoke River watershed, ditch beds which were dug to drain cropland are a significant source of sediment. In the Little Conestoga Creek watershed, river banks and cropland are significant sources Erosion rates for nine cropland sites in the Little Conestoga Creek watershed were also determined with 137Cs inventories and indicated an average rate of erosion of 16.4 tons/hectare/year, which is about 25 times the sediment yield of the Little Conestoga Creek (0.65 tons/hectare/year). This finding indicates substantial sediment storage in the watershed.

Gellis, A. C.; Landwehr, J. M.; Pavich, M. J.; Hupp, C. R.; Ritchie, J. C.; Reuter, J. M.

2005-12-01

245

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

USGS Publications Warehouse

In the absence of actual suspended sediment concentration (SSC) measurements, hydrologists have used sediment rating (sediment transport) curves to estimate (predict) SSCs for subsequent flux calculations. Various evaluations of the sediment rating-curve method were made using data from long-term, daily sediment-measuring sites within large (>1 000 000 km2), medium ( 1000 km2), and small (<1000 km2) river basins in the USA and Europe relative to the estimation of suspended sediment fluxes. The evaluations address such issues as the accuracy of flux estimations for various levels of temporal resolution as well as the impact of sampling frequency on the magnitude of flux estimation errors. The sediment rating-curve method tends to underpredict high, and overpredict low SSCs. As such, the range of errors associated with concomitant flux estimates for relatively short time-frames (e.g. daily, weekly) are likely to be substantially larger than those associated with longer time-frames (e.g. quarterly, annually) because the over- and underpredictions do not have sufficient time to balance each other. Hence, when error limits must be kept under ??20%, temporal resolution probably should be limited to quarterly or greater. The evaluations indicate that over periods of 20 or more years, errors of <1% can be achieved using a single sediment rating curve based on data spanning the entire period. However, somewhat better estimates for the entire period, and markedly better annual estimates within the period, can be obtained if individual annual sediment rating curves are used instead. Relatively accurate (errors annual suspended sediment fluxes can be obtained from hydrologically based monthly measurements/samples. For 5-year periods or longer, similar results can be obtained from measurements/samples collected once every 2 months. In either case, hydrologically based sampling, as opposed to calendar-based sampling is likely to limit the magnitude of flux estimation errors. Published in 2003 by John Wiley and Sons, Ltd.

Horowitz, A. J.

2003-01-01

246

Sedimentation survey of Lago Cerrillos, Ponce, Puerto Rico, April-May 2008  

USGS Publications Warehouse

Lago Cerrillos dam, located in the municipality of Ponce in southern Puerto Rico, was constructed in 1991 as part of the multipurpose Rio Portugues and Bucana Project. This project provides flood protection, water supply, and recreation facilities for the municipio of Ponce. The reservoir had an original storage capacity of 38.03 million cubic meters at maximum conservation pool elevation of 174.65 meters above mean sea level and a drainage area of 45.32 square kilometers. Sedimentation in Lago Cerrillos reservoir has reduced the storage capacity from 38.03 million cubic meters in 1991 to 37.26 million cubic meters in 2008, which represents a total storage loss of about 2 percent. During July 29 to August 23, 2002, 8,492 cubic meters of sediment were removed from the Rio Cerrillos mouth of the reservoir. Taking into account this removed material, the total water-storage loss as of 2008 is 778,492 cubic meters, and the long-term annual water-storage capacity loss rate is about 45,794 cubic meters per year or about 0.12 percent per year. The Lago Cerrillos net sediment-contributing drainage area has an average sediment yield of about 1,069 cubic meters per square kilometer per year. Sediment accumulation in Lago Cerrillos is not uniformly distributed and averages about 3 meters in thickness. This represents a sediment deposition rate of about 18 centimeters per year. On the basis of the 2008 reservoir storage capacity of 37.26 million cubic meters per year and a long-term sedimentation rate of 45,794 cubic meters per year, Lago Cerrillos is estimated to have a useful life of about 814 years or until the year 2822.

Soler-Lopez, Luis R.

2011-01-01

247

Concentrations, loads, and yields of nutrients and suspended sediment in the South Pacolet, North Pacolet, and Pacolet Rivers, northern South Carolina and southwestern North Carolina, October 2005 to September 2009  

USGS Publications Warehouse

The U.S. Geological Survey, in cooperation with Spartanburg Water, evaluated the concentrations, loads, and yields of suspended sediment, dissolved ammonia, dissolved nitrate plus nitrite, total organic nitrogen, total nitrogen, dissolved orthophosphate, dissolved phosphorus, and total phosphorus at sites in the South Pacolet, North Pacolet, and Pacolet Rivers in northern South Carolina and southwestern North Carolina from October 1, 2005, to September 30, 2009 (water years 2006 to 2009). Nutrient and sediment loads and yields also were computed for the intervening subbasin of the Pacolet River not represented by the South and North Pacolet River Basins. Except for a few outliers, the majority of the measurements of total nitrogen concentrations were well below the U.S. Environmental Protection Agency recommended guideline of 0.69 milligram per liter for streams and rivers in the nutrient ecoregion IX, which includes the study area within the Pacolet River Basin. Dissolved orthophosphate, dissolved phosphorus, and total phosphorus concentrations were significantly lower at the South Pacolet River site compared to the North Pacolet and Pacolet River sites. About 90 percent of the total phosphorus concentrations at the South Pacolet River site were below the U.S. Environmental Protection Agency recommended guideline of 0.37 milligram per liter, and more than 75 percent of the total phosphorus concentrations at the North Pacolet and Pacolet River sites were above that guideline. At all sites, minimum annual nutrient loads for the estimation period were observed during water year 2008 when severe drought conditions were present. An estimated mean annual total nitrogen load of 37,770 kilograms per year and yield of 2.63 kilograms per hectare per year were determined for the South Pacolet River site for the estimation period. The North Pacolet River site had a mean annual total nitrogen load of 65,890 kilograms per year and yield of 2.19 kilograms per hectare per year. The Pacolet River had a mean annual total nitrogen load of 99,780 kilograms per year and yield of 1.82 kilograms per hectare per year. Mean annual total phosphorus loads of 2,576; 9,404; and 11,710 kilograms per year and yields of 0.180, 0.313, and 0.213 kilograms per hectare per year were estimated at the South Pacolet, North Pacolet, and Pacolet River sites, respectively. Annually, the intervening subbasin of the Pacolet River contributed negligible amounts of total nitrogen and total phosphorus loads, and large losses of dissolved nitrate plus nitrite and orthophosphate loads were determined for the subbasin. Biological (algal) uptake in the two reservoirs in this intervening area was considered the likely explanation for the loss of these constituents. Estimated mean annual suspended-sediment loads were 21,190,000; 9,895,000; and 6,547,000 kilograms per year at the South Pacolet, North Pacolet, and Pacolet River sites, respectively. In the intervening Pacolet River subbasin, computed annual suspended-sediment loads were consistently negative, indicating large percentage losses in annual suspended-sediment load. Sedimentation processes in the two reservoirs are the most likely explanations for these apparent losses. At all sites, the winter season tended to have the highest estimated seasonal dissolved orthophosphate and dissolved nitrate plus nitrite fluxes, and the summer and fall seasons tended to have the lowest fluxes. The reverse pattern, however, was observed in the intervening drainage area in the Pacolet River where the lowest fluxes of dissolved orthophosphate and nitrate plus nitrite occurred during the winter and spring seasons and the highest occurred during the summer and fall seasons. Synoptic samples were collected during a high-flow event in August 2009 at eight sites that represented shoreline and minor tributary drainages. The South Pacolet River site was identified as contributing greater than 80 percent of the cumulative nutrient and sediment l

Journey, Celeste A.; Caldwell, Andral W.; Feaster, Toby D.; Petkewich, Mattew D.; Bradley, Paul M.

2011-01-01

248

Coupling sediment flow-paths with organic carbon dynamics across a Mediterranean catchment  

NASA Astrophysics Data System (ADS)

Terrestrial sedimentation buries large amounts of organic carbon (OC) annually, contributing to the terrestrial carbon sink. The temporal significance of this sink will strongly depend on the attributes of the depositional environment, but also on the characteristics of the OC reaching these sites and its stability upon deposition. The goal of this study was to characterise the OC during transport and stored in the depositional settings of a medium sized catchment (111 km2) in SE Spain, to better understand how soil erosion and sediment transport processes determine catchment scale OC redistribution. Total Organic Carbon (TOC), Mineral-Associated Organic Carbon (MOC), Particulate Organic Carbon (POC), Total Nitrogen (N) and particle size distributions were determined for soils (i), suspended sediments (ii) and sediments stored in a variety of sinks such as sediment wedges behind check-dams (iii), channel bars (iv), a small delta in the conjunction of the channel and a reservoir downstream (v) and the reservoir at the outlet of the catchment (vi). The data show that the OC content of sediments was approximately half of that in soils (9.42 ± 9.01 g kg-1 vs. 20.45 ± 7.71 g kg-1, respectively) with important variation between sediment deposits. Selectivity of mineral and organic material during transport and deposition increased in a downstream direction. The OC mineralisation, burial or formation occurred in sediments depending on their transport process and on the post-sedimentary conditions. Upstream sediments showed low OC contents because they were partially mobilised by non-selective erosion processes affecting deeper soil layers. We hypothesise that the relatively short transport distances, the effective preservation of OC in micro-aggregates and the burial of sediments in the alluvial wedges give rise to low OC mineralisation, with C : N ratios similar to those in soils. Deposits in middle stream areas (fluvial bars) were enriched in sand, selected upon deposition and had low OC concentrations. Downstream, sediment transported over longer distances was more selected, dominated by silt and clay fractions and associated with OC. Overall, the study shows that OC redistribution in the studied catchment is highly complex, and that transport and deposition processes have a strong effect on the concentration and quality of OC found at the different depositional settings, with important consequences for the temporal stability of the buried OC and in turn for the OC budget.

Boix-Fayos, C.; Nadeu, E.; Quiñonero, J. M.; Martínez-Mena, M.; Almagro, M.; de Vente, J.

2014-05-01

249

Sedimentation of particulate matter in the south-west lagoon of New Caledonia: Spatial and temporal patterns  

Microsoft Academic Search

Suspended and sedimented particulate materials were assessed monthly at five sites on the south-west lagoon of New Caledonia, from May 1986 to April 1987. Sedimentation of particulate matter was measured using sediment traps for 24 h. Resuspension, which accounted for more than 80% of the total sedimentation, was distinguished to calculate net sedimentation values. The mean net sedimentation rate for

J. Clavier; P. Chardy; C. Chevillon

1995-01-01

250

Global calibration of Gephyrocapsa coccolith abundance in Holocene sediments for paleotemperature assessment  

NASA Astrophysics Data System (ADS)

A global sea surface temperature calibration based on the relative abundance of different morphotypes within the coccolithophore genus Gephyrocapsa in Holocene deep-sea sediments is presented. There is evidence suggesting that absolute sea surface temperature for a given location can be calculated from the relative abundance of Gephyrocapsa morphotypes in sediment samples, with a standard error comparable to temperature estimates derived from other temperature proxies such as planktic foraminifera transfer functions. A total of 110 Holocene sediment samples were selected from the Pacific, Indian, and Atlantic Oceans covering a mean sea surface temperature gradient from 13.6° to 29.3°C. Standard multiple linear regression analyses were applied to this data set, linking the relative abundance of Gephyrocapsa morphotypes to sea surface temperature. The best model revealed an r2 of 0.83 with a standard residual error of 1.78°C for the estimation of mean sea surface temperature. This new proxy provides a unique opportunity for the reconstruction of paleotemperatures with a very small amount of sample material due to the minute size of coccoliths, permitting examination of thinly laminated sediments (e.g., a pinhead of material from laminated sediments for the reconstruction of annual sea surface temperature variations). Such fine-scale resolution is currently not possible with any other proxy. Application of this new paleotemperature proxy may allow new paleoenvironmental interpretations in the late Quaternary period and discrepancies between the different currently used paleotemperature proxies might be resolved.

Bollmann, Jörg; Henderiks, Jorijntje; Brabec, Bernhard

2002-08-01

251

Comment on ``Wetland Sedimentation from Hurricanes Katrina and Rita''  

Microsoft Academic Search

Turner et al. (Reports, 20 October 2006, p. 449) measured sedimentation from Hurricanes Katrina and Rita in coastal Louisiana and inferred that storm deposition overwhelms direct Mississippi River sediment input. However, their annualized hurricane deposition rate is overestimated, whereas riverine deposition is underestimated by at least an order of magnitude. Their numbers do not provide a credible basis for decisions

Torbjörn E. Törnqvist; Chris Paola; Gary Parker; Kam-biu Liu; David Mohrig; John M. Holbrook; Robert R. Twilley

2007-01-01

252

Toxicity evaluation by using intact sediments and sediment extracts.  

PubMed

The toxicity of intact sediments and sediment extracts, from both an uncontaminated site and a site contaminated by pulp-mill effluents, was tested in a five months study. The deposit-feeding amphipod Monoporeia affinis was exposed in soft-bottom flow-through water microcosms. To examine potential toxicity a set of reproduction endpoints was used including fecundity and different embryo aberrations such as malformed eggs. Among extracts, the aliphatic/monoaromatic and diaromatic fractions along with the total extract were shown to cause the highest toxicity measured as malformed eggs, while the polyaromatic fraction caused toxicity at background levels. A comparison between sediment extracts and pulp mill contaminated intact sediment, however, showed no toxicity of the intact sediment. Thus, the extraction procedure seems to increase bioavailability and subsequently toxicity as compared to the intact sediments in situ. In toxicity testing using fractionated extracts of sediments in a toxicity identification evaluation (TIE) procedures, caution should therefore be taken when assessing bioavailable contaminants in contaminated areas. This should be taken in account both in determining remediation priorities as well as in ecological risk assessments. PMID:15935181

Eriksson Wiklund, Ann-Kristin; Dag Broman, Brita Sundelin

2005-06-01

253

Total protein  

MedlinePLUS

The total protein test measures the total amount of two classes of proteins found in the fluid portion of your blood. These are albumin and globulin. Proteins are important parts of all cells and tissues. ...

254

Phosphorus distribution in sediments of the Delaware River estuary  

Microsoft Academic Search

In order to determine the primary factors related to the accumulation of phosphorus in estuarine sediments, a study of phosphorus\\u000a fractions in sediments of the Delaware River Estuary was undertaken. A correlation matrix between the phosphorus fractions,\\u000a determined by serial extraction, and 14 sediment variables was computed. Total phosphorus and total inorganic phosphorus in\\u000a the sediment-phosphorus reservoir decreases with increasing

Richard N. Strom; Robert B. Biggs

1982-01-01

255

From deposition to erosion: spatial and temporal variability of sediment sources, storage, and transport in a small agricultural watershed  

USGS Publications Warehouse

The spatial and temporal variability of sediment sources, storage, and transport were investigated in a small agricultural watershed draining the Coast Ranges and Sacramento Valley in central California. Results of field, laboratory, and historical data analysis in the Willow Slough fluvial system document changes that transformed a transport-limited depositional system to an effective erosion and transport system, despite a large sediment supply. These changes were caused by a combination of factors: (i) an increase in transport capacity, and (ii) hydrologic alteration. Alteration of the riparian zone and drainage network pattern during the past ~ 150 years included a twofold increase in straightened channel segments along with a baselevel change from excavation that increased slope, and increased sediment transport capacity by ~ 7%. Hydrologic alteration from irrigation water contributions also increased transport capacity, by extending the period with potential for sediment transport and erosion by ~ 6 months/year. Field measurements document Quaternary Alluvium as a modern source of fine sediment with grain size distributions characterized by 5 to 40% fine material. About 60% of an upland and 30% of a lowland study reach incised into this deposit exhibit bank erosion. During this study, the wet 2006 and relatively dry 2007 water years exhibited a range of total annual suspended sediment load spanning two orders of magnitude: ~ 108,500 kg/km2/year during 2006 and 5,950 kg/km2/year during 2007, only 5% of that during the previous year. Regional implications of this work are illustrated by the potential for a small tributary such as Willow Slough to contribute sediment – whereas large dams limit sediment supply from larger tributaries – to the Sacramento River and San Francisco Bay Delta and Estuary. This work is relevant to lowland agricultural river–floodplain systems globally in efforts to restore aquatic and riparian functions and where water quality management includes reducing fine sediment contributions that can couple with other pollutants.

Florsheim, J. L.; Pellerin, B. A.; Oh, N. H.; Ohara, N.; Bachand, P. A. M.; Bachand, S. M.; Bergamaschi, B. A.; Hernes, P. J.; Kavvas, M. L.

2011-01-01

256

River sediments.  

PubMed

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

Williams, Martin

2012-05-13

257

Sediment TMDL Development for the Amite River  

Microsoft Academic Search

The Amite River is recognized as one of the 15 water bodies impaired by sediments in Louisiana, USA. Based on US EPA’s Protocol\\u000a sediment TMDL (Total Maximum Daily Load) development is conducted for the Amite River and described in this paper. The TMDL\\u000a development consists of four components: (1) development of a new model for cohesive sediment transport, (2) estimation

Pradeep K. Mishra; Zhi-Qiang Deng

2009-01-01

258

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

Microsoft Academic Search

Analyses of flow, sediment-transport, bed-topographic, and sedimentologic data suggest that before the closure of Glen Canyon Dam in 1963, the Colorado River in Marble and Grand Canyons was annually supply-limited with respect to fine sediment (i.e., sand and finer material). Furthermore, these analyses suggest that the predam river in Glen Canyon was not supply-limited to the same degree and that

David J. Topping; David M. Rubin; L. E. Vierra

2000-01-01

259

Snake and Columbia Rivers Sediment Sampling Project  

SciTech Connect

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

Pinza, M.R.; Word, J.Q; Barrows, E.S.; Mayhew, H.L.; Clark, D.R. (Battelle/Marine Sciences Lab., Sequim, WA (United States))

1992-12-01

260

The Impact of Rainstorm Stochasticity on Hillslope Sediment Supply to River Channels in Dryland Basins  

NASA Astrophysics Data System (ADS)

Climate interacts with hillslopes supplying sediment to river channels, and impacting drainage basin functioning and evolution. In particular, coarse sediment supply from hillslopes exerts a strong control on channel bed material grain-size distributions (GSD) which feeds back on bedload flux and consequently affects long-term rates of valley incision/aggradation. However, process-based understanding of sediment supply from hillslopes is poorly constrained because it is spatially and temporally variable as a result of interactions between rainstorm attributes (frequency, intensity, duration, size) and hillslope characteristics within a basin (length, gradient, infiltration rates, GSD). Drylands are particularly sensitive to climatic forcing because they are subjected to infrequent, short-lived, but high intensity rainfall events, which are spatially-variable and often smaller than the basin area. These climatic factors coupled with thin, stony soils typical of drylands, produce dynamic and variable sediment supply to channels, with a high proportion of coarse material that remains in channel beds over long timescales. Currently there is limited understanding of how variability and nonstationarity in regional climate affect hillslope sediment supply to valley floors in dryland basins. In these landscapes, the discrete and spatially variable nature of convective rainstorms and other catchment characteristics create challenges for deterministic modelling of the interaction between climate and sediment transport. Here we represent climate as a stochastic process characterized by probability density functions of storm properties (total annual rainfall, location, size, duration, peak rainfall intensity). This stochastic driver is coupled to a physics-based hillslope sediment transport model in order to investigate the decadal impact of climatic variability on longitudinal hillslope coarse (> 2 mm) sediment supply (flux and GSD) to a mainstem channel within a 170 km2 basin in SE Spain. We also test a number of plausible scenarios of regional climate change and compare all our results against GSDs measured in the channel. Results show highly discontinuous and variable sediment supply along the river reach which is sensitive to rainstorm characteristics as manifested in runoff changes. The interaction between hillslope characteristics and rainstorm attributes results in a non-linear relationship between climate forcing and sediment supply and has significant implications for changing volume and GSD of sediment delivered to the channel.

Michaelides, K.; Singer, M. B.

2013-12-01

261

Erosion, storage, and transport of sediment in two subbasins of the Rio Puerco, New Mexico  

USGS Publications Warehouse

Arroyos in the American Southwest proceed through cut-and-fill cycles that operate at centennial to millennial time scales. The geomorphic community has put much effort into understanding the causes of arroyo cutting in the late Quaternary and in the modern record (late 1800s), while little effort has gone into understanding how arroyos fill and the sources of this fill. Here, we successfully develop a geographic information system (GIS)-modeled sediment budget that is based on detailed field measurements of hillslope and channel erosion and deposition. Field measurements were made in two arroyo basins draining different lithologies and undergoing different land disturbance (Volcano Hill Wash, 9.30 km2; Arroyo Chavez, 2.11 km2) over a 3 yr period. Both basins have incised channels that formed in response to the late nineteenth-century incision of the Rio Puerco. Large volumes of sediment were generated during arroyo incision, equal to more than 100 yr of the current annual total sediment load (bed load + suspended load) in each basin. Downstream reaches in both arroyos are presently aggrading, and the main source of the sediment is from channel erosion in upstream reaches and first- and second-order tributaries. The sediment budget shows that channel erosion is the largest source of sediment in the current stage of the arroyo cycle: 98% and 80% of the sediment exported out of Volcano Hill Wash and Arroyo Chavez, respectively. The geomorphic surface most affected by arroyo incision and one of the most important sediment sources is the valley alluvium, where channel erosion, gullying, soil piping, and grazing all occur. Erosion rates calculated for the entire Volcano Hill Wash (-0.26 mm/yr) and Arroyo Chavez (-0.53 mm/yr) basins are higher than the modeled upland erosion rates in each basin, reflecting the large contributions from channel erosion. Erosion rates in each basin are affected by a combination of land disturbance (grazing) and lithology--erodible sandstones and shales in Arroyo Chavez compared with basalt for Volcano Hill Wash. Despite these differences, hillslope sediment yields are similar to long-term denudation rates. As the arroyo fills over time from mouth to headwaters, hillslope sediment becomes a more significant sediment source.

Gellis, A. C.; Pavich, M. J.; Ellwein, A. L.; Aby, S.; Clark, I.; Wieczorek, M. E.; Viger, R.

2012-01-01

262

The Impact of Rainstorm Stochasticity on Hillslope Sediment Supply to River Channels in Dryland Basins  

NASA Astrophysics Data System (ADS)

Climate interacts with hillslopes supplying sediment to river channels, and impacting drainage basin functioning and evolution. In particular, coarse sediment supply from hillslopes exerts a strong control on channel bed material grain-size distributions (GSD) which feeds back on bedload flux and consequently affects long-term rates of valley incision/aggradation. However, process-based understanding of sediment supply from hillslopes is poorly constrained because it is spatially and temporally variable as a result of interactions between rainstorm attributes (frequency, intensity, duration, size) and hillslope characteristics within a basin (length, gradient, infiltration rates, GSD). Drylands are particularly sensitive to climatic forcing because they are subjected to infrequent, short-lived, but high intensity rainfall events, which are spatially-variable and often smaller than the basin area. These climatic factors coupled with thin, stony soils typical of drylands, produce dynamic and variable sediment supply to channels, with a high proportion of coarse material that remains in channel beds over long timescales. Currently there is limited understanding of how variability and nonstationarity in regional climate affect hillslope sediment supply to valley floors in dryland basins. In these landscapes, the discrete and spatially variable nature of convective rainstorms and other catchment characteristics create challenges for deterministic modelling of the interaction between climate and sediment transport. Here we represent climate as a stochastic process characterized by probability density functions of storm properties (total annual rainfall, location, size, duration, peak rainfall intensity). This stochastic driver is coupled to a physics-based hillslope sediment transport model in order to investigate the decadal impact of climatic variability on longitudinal hillslope coarse (> 2 mm) sediment supply (flux and GSD) to a mainstem channel within a 170 km2 basin in SE Spain. We also test a number of plausible scenarios of regional climate change and compare all our results against GSDs measured in the channel. Results show highly discontinuous and variable sediment supply along the river reach which is sensitive to rainstorm characteristics as manifested in runoff changes. The interaction between hillslope characteristics and rainstorm attributes results in a non-linear relationship between climate forcing and sediment supply and has significant implications for changing volume and GSD of sediment delivered to the channel.

Michaelides, K.; Singer, M. B.

2011-12-01

263

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

Microsoft Academic Search

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

Mirva Nykänen; Kirsi Vakkilainen; Mikko Liukkonen; Timo Kairesalo

2009-01-01

264

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

USGS Publications Warehouse

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

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

2000-01-01

265

Totally James  

ERIC Educational Resources Information Center

This article presents an interview with James Howe, author of "The Misfits" and "Totally Joe". In this interview, Howe discusses tolerance, diversity and the parallels between his own life and his literature. Howe's four books in addition to "The Misfits" and "Totally Joe" and his list of recommended books with lesbian, gay, bisexual, transgender,…

Owens, Tom

2006-01-01

266

Weldon Spring, Missouri: Annual environmental monitoring report, calendar year 1987  

SciTech Connect

Radiological monitoring at the WSS during 1987 measured uranium, Radium-226, and Thorium-230 concentrations in surface water, groundwater, and sediment; radon gas concentrations in air; all long-lived natural series isotopes in air particulates; and external gamma radiation exposure rates. Potential radiation doses to the public were calculated based on assumed exposure periods and the above measurements. Radon concentrations, external gamma exposure rates, and radionuclide concentrations in groundwater and surface water at the site were generally equivalent to previous years' levels. The maximum calculated annual radiation dose to a hypothetically exposed individual at the WSRP and WSCP area was 1 mrem, or 1 percent of the DOE radiation protection standard of 100 mrem. The maximum calculated annual radiation dose to a hypothetically exposed individual at the WSQ was 14 mrem, or about 14 percent of the standard. Thus the WSS currently complies with DOE Off-site Dose Standards. Chemical contamination monitoring at the WSS during 1987 measured nitroaromatics, total organic carbon and the inorganic anions chloride, nitrate, fluoride and sulfate in surface water, groundwater and sediment. 22 refs., 26 figs., 21 tabs.

Not Available

1987-01-01

267

A re-evaluation of sediment and solute transfers in Karkevagge Swedish Lapland  

NASA Astrophysics Data System (ADS)

Karkevagge, Swedish Lapland, has been the site of detailed geomorphic investigations for over sixty years. The classic study by Rapp (1960) not only identified the dominant processes operating on slope evolution in the valley, but also their magnitudes. Since that landmark study, there has been on-going research focused on better understanding magnitudes and frequencies of the dominant processes, but there has been no comprehensive reassessment of the overall sediment and solute fluxes in the valley. This paper compiles data from numerous recent studies in an effort to obtain an understanding of contemporary sediment fluxes in the valley. . Kärkevagge is a 5km long glacial valley located in northern Swedish Lapland at approximately 68o26' N latitude and 18o18'E longitude. The 30 year mean annual air temperature from the nearby Katterjakk climate station is -1.7oC and mean annual precipitation is 844mm. Some 50% of the precipitation comes in the form of snow. Mean total sediment output from the catchment is 0.2-11.2tkm-2d-1 (Rehn et al., 1982). There is however considerable spatial variability in sediment transfer within the valley. Solifluction accounts for the greatest sediment mass transfer in the valley at 1176 t/km2/yr. Mean mass transfer is in the vicinity of 20,000t/yr. (Ridefelt et al., 2009). Annual movement is on average 4cm/ yr. but displays considerable spatial variability depending on moisture availability Slush avalanches and slush torrents represent significant contributors to sediment transfer in the valley, with mean mass/area transfers of 128t/km2/yr. They display considerable variability in their magnitude, varying from as little as 0.5m3 to >300m3. Slush torrents may contribute between 10,000 and 20,000m3 of mass flow (Gude et al., 2000). Solute transfer amounts to 46t/km2/yr. for the valley as a whole but there is considerable spatial variability. Total solute flux is greatest at the valley outlet, but within the valley solute flux is greatest at the base of the dam impounding Lake Rissajaure. Within-valley solute variability is strongly controlled by bedrock lithology variability. Earth slides and debris flows account for approximately 43t/km2/yr. Rockfalls account for approximately 8.7 t/km2/yr. while small avalanches account for 1.4t/km2/yr. These mass movements display considerable spatial and temporal variability in magnitude and frequency within the valley. Valley side wash moves 0.59t/km2/yr. of fine sediment. Fluvial transport is estimated to be between 40-50 t/km2/yr. flood and slush events contribute suspended sediment up to as much as 3.4t/km2/day. There is considerable variability in suspended sediment transport within the valley channel systems (Rhen et al. 1982). Rapp's (1960) sediment transfer rates continue to provide a broadly reliable framework for understanding sediment fluxes in Kärkevagge. However subsequent calculations suggest some earlier magnitude determinations need minor revision. Process rates are highly variable spatially and temporally.

Dixon, John

2014-05-01

268

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

NASA Astrophysics Data System (ADS)

Ongoing changes in the Central Asian climate including increasing temperatures can influence the hydrological regimes of rivers and the waterborne transport of sediments. Changes in the latter, especially in combination with adverse human activities, may severely impact water quality and aquatic ecosystems. However, waterborne transport of sediments is a result of complex processes and varies considerably between, and even within, river systems. There is therefore a need to increase our general knowledge about sediment transport under changing climate conditions. The Tuul River, the case site of this study, is located in the upper part of the basin of the Selenga River that is the main tributary to Lake Baikal, a UNESCO World Heritage Site. Like many other rivers located in the steppes of Northern Mongolia, the Tuul River is characterized by a hydrological regime that is not disturbed by engineered structures such as reservoirs and dams. However, the water quality of the downstream Tuul River is increasingly affected by adverse human activities - including placer gold mining. The largest contribution to the annual river discharge occurs during the relatively warm period in May to August. Typically, there are numerous rainfall events during this period that cause considerable river flow peaks. Parallel work has furthermore shown that due to climate change, the daily variability of discharge and numbers of peak flow events in the Tuul River Basin has increased during the past 60 years. This trend is expected to continue. We here aim at increasing our understanding of future sediment transport patterns in the Tuul River, specifically considering the scenario that peak flow events may become more frequent due to climate change. We use a one-dimensional sediment transport model of the downstream reach of the river to simulate natural patterns of sediment transport for a recent hydrological year. In general, the results show that sediment transport varies considerably spatially and temporally. Peak flow events during the warm period contribute largely to the total annual transport of sediments and also to the erosion of stored bed material. These results suggest that if the number of peak flow events will increase further due to climate change, there will be a significant increase in the annual sediment load and consequently in the load of contaminants that are attached to the sediments, in particular downstream of mining sites. The present results are furthermore consistent with parallel studies on sediment transport and climate change showing that increased water discharges and frequencies of rainfall/flow events can lead to enhanced erosion processes. Furthermore, in addition to climate change effects, human activates can change sediment loads in rivers to even greater extent, as pointed out in several studies. Thus, several different challenges can be expected to face the management of Central Asian rivers such as Tuul and their ecosystems in the future.

Pietro?, Jan; Jarsjö, Jerker

2014-05-01

269

Hydroclimatic controls over sediment transport and clastic varve formation in the Canadian Arctic; ten years of process research (Invited)  

NASA Astrophysics Data System (ADS)

Clastic varved sedimentary records have been used as key paleoenvironmental records in regions where other high resolution proxy records are not available. These varved records are often interpreted as proxies of hydroclimatic processes: a combination of one or more climatic or meteorological processes that generate sufficient hydrological response to alter sediment delivery to the lake. While most clastic varved records have used statistical regression techniques to interpret the varve-climate relationship, few records have been investigated from a process perspective, and fewer still have sustained process studies for more than a two years. Although process studies are not an absolute requirement for interpreting clastic varve records, there remains a compelling rationale for pursuing them to enhance the interpretation of the hydroclimatic signals within the varves. Process research at the Cape Bounty Arctic Watershed Observatory (CBAWO) on south-central Melville Island (74°55'N, 109°35'W), Canada, are carried out in paired watersheds that drain into similar lakes that both contain long varve sequences. Parallel measurements have been undertaken to characterize climate, hydrology, sediment transport, limnology and sediment deposition processes. At CBAWO, stream flow is generated primarily from snow melt during the spring and it is during this period that the majority of sediment is often transported to lakes. The main control over water volume and maximum discharge rate is catchment snow water equivalence (SWE), most reliably measured as total runoff. While incoming radiation and air temperature correlate with daily discharge, there is no significant correlation between energy and discharge at the seasonal level. Annual sediment yields suggest a close correspondence between SWE, sediment yield and sediment deposition in traps in the lake bottom. In some years, rainfall plays an important role over sediment yield. In 2009, a single two-day event was responsible for more than 80% of the annual yield. By contrast, in 2012, a similar rainfall event generated essentially no runoff response. These results point to the key hydroclimatic processes that affect sediment accumulation and varve properties and can aid in calibration of the varve paleoenvironmental signal. Despite the relative hydroclimatic simplicity of this setting, the primary processes for sediment delivery are complex and can vary substantially in a given year.

Lamoureux, S. F.

2013-12-01

270

Lake sediment records of industrialization in the Sudbury area of Ontario, Canada  

SciTech Connect

The smelting of nickel and copper sulfide ores has drastically modified the original landscape around Sudbury, Ontario. A record of this impact exists in the sediments of local lakes. Changes in the annual fallout of heavy metals, identifiable smoke particulates, and pollen grains reflect the changes that occurred in the sedimentation rate and the vegetation. A year by year chronology for the last 300 years was provided by meromictic lake sediments containing countable seasonal laminations, obtained by a freezing technique that kept the sediments and sediment/water interface undisturbed. Results indicate that: correspondences of vegetation changes, and sedimentation rates with metal residues and smoke particulates in the sediments, and with published smelter records are good; annual laminations in meromictic lakes provided an excellent chronology, as checked against known dates for settlement and the onset of smelting; identifiable smoke particulates provided a good record of smelter activity, and were also a check on metal residue mobility in the sediments.

Huhn, F.J.

1985-01-01

271

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

USGS Publications Warehouse

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.

Horowitz, A. J.

1995-01-01

272

Annual cycle in co-located in situ, total-column, and height-resolved aerosol observations in the Po Valley (Italy): Implications for ground-level particulate matter mass concentration estimation from remote sensing  

Microsoft Academic Search

Remote sensing represents a prospective tool to complement in situ measurements for monitoring particulate matter air pollution. The remotely sensed aerosol metric which is generally related to the in situ measured particulate matter mass concentration (PM) is the aerosol optical thickness (AOT), the vertically integrated aerosol extinction that optically quantifies the aerosol load in the whole atmospheric column. Annual variations

F. Barnaba; J. P. Putaud; C. Gruening; A. dell'Acqua; S. Dos Santos

2010-01-01

273

Seismostratigraphic analysis with centennial to decadal time resolution of the sediment sink in the Ganges-Brahmaputra subaqueous delta  

NASA Astrophysics Data System (ADS)

The deltas of large rivers have become the focus of many research studies due to their vulnerability in times of expected sea level rise. One major delta in peril is the Ganges-Brahmaputra Delta (Bangladesh) due to its low elevation and high subsidence rate. In this study, high-resolution seismic and sediment echosounder data of the subaqueous part of the delta are analyzed by an integrated seismo-acoustic stratigraphic approach. Transparent Units (TUs) are the most prominent, continuously traceable architectural elements within the sigmoidal clinoform. TUs consist of homogenized sediments and are interpreted to be formed by liquefaction flows generated by subduction-related earthquakes of the nearby plate-boundary. The uppermost TUs are related to the historical well known major earthquakes which occurred in 1762, 1897 and 1950. Using the TUs as time marks the mean annual storage rates for the intervals could be assessed. A direct comparison of echosounder data gathered in 1994, 1997 and 2006 is used as another method to estimate the last decade mean annual storage rate. In general, the averaged decadal to centennial mean annual storage rates in the foreset beds have significantly decreased within the last ˜300 years from 22% to 18% and down to 13.8% of the present total annual fluviatile suspension supply to the delta (10 9 t a -1). This decrease, however, is not evenly distributed along the foreset beds. In the western clinoform mean annual storage rates slightly decreased during the last ˜300 years, whereas in the eastern clinoform the mean annual storage rate of the last decade is one-third of the initial value in the late eighteenth century. The variation of clinoform slope angles generally coincides with the local accumulation rates but a variable degree of asymmetry gives some new insights in the future trend of the subaqueous delta development. The sink of sediment in the western clinoform depocentre landward of the inflection point, where shape changes from convex to concave, is producing an increase in concavity. The decline in monsoon precipitation over the last centuries is assumed to have significantly contributed to the decreased mean annual storage rate in the eastern clinoform where the convexity of the clinoform increases seaward of the inflection point. It is very likely that the whole depocentre of the fluvial sediment load is shifting toward the western subaqueous delta and to the Swatch of No Ground Canyon and, thereby, increasing the export to the deep-sea fan.

Palamenghi, Luisa; Schwenk, Tilmann; Spiess, Volkhard; Kudrass, Hermann R.

2011-04-01

274

Contaminated Sediments in Water  

MedlinePLUS

... Sediments Contaminated Sediments in Water Contaminated Sediments in Water Overview Basic Information Technical Resources CS Data Find ... released years ago while other contaminants enter our water every day. Some contaminants flow directly from industrial ...

275

CONTAMINATED SEDIMENTS SCIENCE PRIORITIES  

EPA Science Inventory

The Contaminated Sediment Science Priorities (CSSP) document isa mechanism for the U.S. EPA to develop and coordinate Agency-wide science activities that affect contaminated sediments. It analyzes current Agency contaminated sediments science activities, identifies and evaluates...

276

Sediment loads in the Red River of the North and selected tributaries near Fargo, North Dakota, 2010--2011  

USGS Publications Warehouse

Natural-resource agencies are concerned about possible geomorphic effects of a proposed diversion project to reduce the flood risk in the Fargo-Moorhead metropolitan area. The U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers collected data in the spring of 2010 and 2011, and from June to November 2011, during rainfall-runoff events and base-flow conditions to provide information on sediment transport. The data were used to examine sediment concentrations, loads, and particle-size distributions at nine selected sites in the Red River and its tributaries near the Fargo-Moorhead metropolitan area. Suspended-sediment concentration varied among sites in 2010 and 2011. The least suspended-sediment concentrations were measured at the Red River (site 1) and the Buffalo River (site 9), and the greatest concentrations were measured at the two Sheyenne River sites (sites 3 and 4). Estimated daily suspended-sediment loads were highly variable in 2010 and 2011 in the Red River and its tributaries, with the greatest loads occurring in the spring and the smallest loads occurring in the winter. For the Red River, daily suspended-sediment loads ranged from 26 to 3,500 tons per day at site 1 and from 30 to 9,010 tons per day at site 2. For the Sheyenne River, daily loads ranged from less than 10 to 10,200 tons per day at site 3 and from less than 10 to 4,530 tons per day at site 4. The mean daily load was 191 tons per day in 2010 and 377 tons per day in 2011 for the Maple River, and 610 tons per day in 2011 for the Wild Rice River (annual loads were not computed for 2010). For the three sites that were only sampled in 2011 (sites 7, 8 and 9), the mean daily suspended-sediment loads ranged from 40 tons per day at the Lower Branch Rush River (site 8) to 118 tons per day at the Buffalo River (site 9). For sites that had estimated loads in 2010 and 2011 (sites 1–5), estimated annual (March–November) suspended-sediment loads were greater in 2011 compared to 2010. In 2010, annual loads ranged from 68,650 tons per year at the Maple River (site 5) to 249,040 tons per year at the Sheyenne River (site 3). In 2011, when all nine sites were sampled, annual loads ranged from 8,716 tons per year at the Lower Branch Rush River (site 8) to 552,832 tons per year at the Sheyenne River (site 3). With the exception of the Sheyenne River (site 4), the greatest monthly loads occurred in March for 2010, with as little as 27 percent (site 1) and as much as 42 percent (site 3) of the annual load occurring in March. For 2011, the greatest monthly loads occurred in April, ranging from 33 percent (site 1) to 63 percent (site 7) of the 2011 annual load. A relatively small amount of sediment was transported past the nine sites as bedload in 2010 and 2011. For most of the samples collected at the nine sites, the bedload composed less than 1 percent of the calculated daily total sediment load.

Galloway, Joel M.; Nustad, Rochelle A.

2012-01-01

277

Processing of a fine sediment pulse after dam removal: sediment mass balance and longitudinal trends  

NASA Astrophysics Data System (ADS)

A sediment mass balance around the site of a dam removal can provide useful insight into the processes driving and nature (e.g. magnitude, spatial extent, and duration) of downstream impacts associated with the release of fine sediment. Chiloquin Dam was removed from the Sprague River in southern Oregon in August of 2008. A sediment mass balance was calculated based on continuous suspended sediment concentrations (SSCs), which were developed over 3 years (1 year pre removal and 2 years post removal) from continuous turbidity measurements. The processing of the sediment stored behind the dam (composed primarily of sand and fines) and the resulting bedform changes were examined using annual cross section surveys, bathymetric surveys using RTK GPS and ADCP, and surface sediment characterization. Longitudinal profiles and differenced DEMs indicate that a) the sediment wedge behind the dam was not fully processed during the first 2 years post-removal due to low water but substantial processing occurred during year 3 with higher flows, b) deposition in pools downstream of the dam occurred during all years, though the magnitude and spatial extent varied with water year type, and c) transient deposition of fine sediment in downstream riffles occurred, although deposition was partially obscured by basin wide trends of fining in the absence of high flows. Results demonstrate the implications of delayed sediment processing due to low flow over the two years, limiting the extent but extending the duration of potential downstream impacts to habitat. Results are organized to outline a conceptual model for how annual hydrologic regimes (low vs. high flow years) drive temporal and spatial dynamics of sediment processing in the context of dam removal as a disturbance.

Cox, M. M.; Tullos, D. D.

2011-12-01

278

Silver toxicity to Chironomus tentans in two freshwater sediments  

Microsoft Academic Search

Sediment collected from two freshwater lakes, West Bearskin Lake (Cook, MN, USA) and Bond Lake (Douglas, WI, USA), was characterized for grain size, total organic carbon, (TOC), acid-volatile sulfides (AVS), simultaneously extracted metals (SEM), and iron (Fe). Both sediments had low levels of TOC. West Bearskin Lake sediment contained more small particles than Bond Lake, which was 95% sand. West

Daniel J. Call; Christine N. Polkinghorne; Thomas P. Markee; Larry T. Brooke; Dianne L. Geiger; Joseph W. Gorsuch; Kenneth A. Robillard

1999-01-01

279

Anaerobic Oxalate Degradation: Widespread Natural Occurrence in Aquatic Sediments  

PubMed Central

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.

Smith, Richard L.; Oremland, Ronald S.

1983-01-01

280

Hydrodynamic sorting and transport of terrestrially derived organic carbon in sediments of the Mississippi and Atchafalaya Rivers  

NASA Astrophysics Data System (ADS)

Over the course of two years, four cruises were conducted at varying levels of discharge in the lower Mississippi and Atchafalaya Rivers (MR and AR) where grab samples were collected from sand- and mud-dominated sediments. The tetramethylammonium hydroxide (TMAH) thermochemolysis method was used to determine sources of terrestrially derived organic carbon (OC) in these two sediment types, to examine the effects of hydrodynamic sorting on lignin sources in river sediments. Average lignin concentrations in the lower MR were 1.4 ± 1.1 mg gOC -1 at English Turn (ET) and 10.4 ± 27.4 mg gOC -1 at Venice. Using these concentrations, annual lignin fluxes to the Gulf of Mexico, from tidal and estuarine mud remobilization at ET and Venice, were 3.1 ± 2.5 × 10 5 kg and 11.4 ± 30.0 × 10 5 kg, respectively. Much of the lignin-derived materials in muddy sediments appeared to be derived from non-woody grass-like sources - which should decay more quickly than the woody materials typically found in the sandy deposits. The average total OC% (1.93 ± 0.47) of English Turn sands yields an annual flux of 0.34 ± 0.09 × 10 9 kg. Lignin flux in the English Turn sands (3.6 ± 2.6 mg gC -1) using the numbers above would be 12.2 ± 9.4 × 10 5 kg. The extensive amounts of sand-sized woody materials (coffee-grinds) found in the sandy sediments in both the AR and MR are likely derived from woody plant materials. This is the first time it has been demonstrated that sandy sediments in the MR provide an equally important pathway (compared to muds) for the transport of terrestrially derived organic matter to the northern Gulf of Mexico. Using the AR average %OC in sand (1.16 ± 0.72), we estimated an annual flux of OC to the shelf of 0.13 ± 0.07 × 10 9 kg. Lignin flux for AR sands was estimated to be 12.4 ± 12.1 × 10 5 kg. Despite the high error associated with these numbers, we observe for the first time that the flux of lignin in sandy sediments in the AR to the northern Gulf of Mexico is comparable to that found in the MR. These results further support the likelihood of grain-size related hydrodynamic sorting of terrestrially derived organic carbon in the lower Mississippi and Atchafalaya Rivers, suggesting that there is a distinct sandy sediment organic fraction contributed by major rivers to the global carbon cycle.

Bianchi, Thomas S.; Galler, John J.; Allison, Mead A.

2007-06-01

281

Distribution and partitioning of heavy metals in estuarine sediment cores and implications for the use of sediment quality standards  

NASA Astrophysics Data System (ADS)

Total metal concentrations in surface sediments and historically contaminated sediments were determined in sediment cores collected from three estuaries (Thames, Medway and Blackwater) in south-east England. The partitioning behaviour of metals in these sediments was also determined using a sequential extraction scheme. These data were then compared with sediment quality values (SQVs) to determine the potential ecotoxicological risk to sediment dwelling organisms. When total metal concentrations in surface sediments are examined, no risk to biota in any of the estuaries is indicated. However, when historically contaminated sediments at depth are also considered, risks to biota are apparent and are greatest for the Thames, followed by the Medway and then the Blackwater. This suggests that regulatory authorities should examine vertical metal profiles, particularly in estuaries that are experiencing low sediment accumulation rates where historically contaminated sediments are in the shallow sub-surface zone and where erosion or dredging activities may take place. When metal partitioning characteristics are also considered, the risk to biota is comparable for the Medway and the Blackwater with the potentially bioavailable fraction presenting no ecotoxicological risk. Conversely, over 70% of metals are labile in the Thames Estuary sediments and toxic effects are probable. This suggests that the application of SQVs using total sediment metal concentrations may over- or under-estimate the risk to biota in geochemically dissimilar estuarine sediments.

Spencer, K. L.; MacLeod, C. L.

282

Size characteristics and mineralogy of suspended sediments of the Ganges river, India  

Microsoft Academic Search

With a mean annual flow of 5.9×1011m3yr-1 and sediment load of 1600x1012gyr-1 the Ganges river ranks second and third, respectively, in terms of water flow and sediment load among the world's rivers. Considering the enormous sediment transport by Ganges to the Bay of Bengal, a study was conducted on the size distribution and mineral characteristics of the suspended sediments of

G. J. Chakrapani; V. Subramanian; R. J. Gibbs; P. K. Jha

1995-01-01

283

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

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

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

2014-01-01

284

Chemical Exchange at the Sediment-Water Interface of Cannonsville Reservoir  

Microsoft Academic Search

Rates of chemical exchange at the sediment-water interface of Cannonsville Reservoir were determined using intact sediment cores. Reference sites for coring were selected based on the results of a surficial sediment survey. Higher levels of volatile suspended solids, chemical oxygen demand, total organic carbon, total nitrogen, and total phosphorus were noted at deep water stations proximate to the dam and

Michael J. Erickson; Martin T. Auer

1998-01-01

285

Occurrence of phthalate esters in sediments in Qiantang River, China and inference with urbanization and river flow regime.  

PubMed

Phthalate esters (PAEs), a group of emerging organic contaminants, have become a serious issue arousing much attention for their ubiquitous presence and hazardous impact on the environment. This study provides the first data on distribution of PAEs in the sediments in the Qiantang River, Zhejiang Province, China, and the inference with urbanization and river flow regime. PAEs were detected in all 23 sediment samples analyzed, and the total concentrations of their 16 congeners in sediments ranged from 0.59 to 6.74?g/g dry weight (dw), with the geometric mean value of 2.03?g/g dw. Of the 16 PAE congeners, di-n-butyl phthalate (DnBP), diisobutyl phthalate (DiBP), and di(2-ethylhexyl) phthalate (DEHP) were present in all sediment samples. The PAEs concentrations in urban regions were higher than those in rural regions because of higher discharge of PAEs from plastic materials in urbanized areas. Concentrations of PAEs were positively correlated with sediment organic matter (fOM) and negatively correlated with logistic value of annual average flow volume at sample sites. River flow regime modified by man-made dams significantly affected the distribution of PAEs. Analysis of congener composition of PAEs indicated that the DEHP was predominant congener in the Qiantang River. The normalized concentration of DEHP exceeded recommended environmental risk limit (ERL). PMID:23339883

Sun, Jianqiang; Huang, Jing; Zhang, Anping; Liu, Weiping; Cheng, Wenwei

2013-03-15

286

Effect of algal bloom deposition on sediment respiration and fluxes  

Microsoft Academic Search

Using sediment cores collected in November 1989 from Aarhus Bight, Denmark, the fluxes of O2, SCO2 (total CO2), NH4+, NO3-+NO2-and DON (dissolved organic nitrogen) across the sediment-water interface were followed for 20 d in an experimental continous flow system. On day 7, phytoplankton was added to the sediment surface, to see the result of simulated algal bloom sedimentation. Benthic O2

L. S. Hansen; T. H. Blackburn

1992-01-01

287

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

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.

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

2011-01-01

288

Rates and spatial patterns of sediment dispersal across the lower Strickland River floodplain, Papua New Guinea  

NASA Astrophysics Data System (ADS)

As part of a NSF Margins Source to sink study, we are exploring the rates and patterns of floodplain sediment vertical accretion on the Middle Fly River and the lower Strickland River, Papua New Guinea. The rivers join at 6 m above sea level where tidal influences are currently weak (except at exceptionally low flow). In response to post-glacial sea level rise both rivers aggraded, but the Strickland, carrying 7 times the sediment load, twice the discharge, and transiting through a much shorter lowland reach, has built a roughly 10 times steeper slope and a much coarser bed than the Fly. We have hypothesized that as a consequence of this difference the rate of sediment loss to the floodplain will be much lower than on the Fly (which is currently about 40% for the Middle Fly Reach). Near the gravel-sand transition, the Strickland floodplain rapidly widens downstream to an average width of approximately 10 km, and the channel has built an elevated meander belt across the roughly 100 km long plain. Recently, sediment laden flood flows have occasionally spilled out of the Strickland through an oxbow and traveled along a small channel into Lake Murray. Lake Murray is directly connected to the Strickland via the Herbert River, a large, deep channel that occasionally reverses and directs Strickland waters to the Lake. To document the spatial pattern of sediment deposition, sediment cores were collected at 11 transects across the floodplain. In addition, samples were collected along the outflow channel, in Lake Murray, and in a separate oxbow fed only by a tie channel. Duplicates and, in places, triplicate core samples were taken to enable independent analysis of sedimentation rates using two methods. Mine tailings introduced into the headwaters of the Strickland since 1990, although of relatively minor importance to the total load of the lower Strickland; provide a distinct elevated Pb and Ag signature in the recently deposited sediment. In over 30 cores, 210Pb analyses have been performed to document sedimentation rates over longer periods. Analyses are still underway, but findings to date show that the two methods of estimating sedimentation rates give roughly similar rates. Across the approximately 2 km active portion of the floodplain, vertical accretion rates on average are on the order of 1 cm/yr, with rates being highest near the channel. Applying this rate uniformly across the entire active floodplain gives an annual sedimentation rate of about 2 million tonnes, which is less than 3% of the estimated annual load of 70 Mt/yr. It is unlikely that further refinement of our analyses will increase this percent to a value similar to the 40% found on the Fly. Although the current sediment loss rate to the Strickland floodplain appears to be relatively low, sediment laden flood pulses from the uplands are substantially damped out by transient flow storage in the main channel and floodplain.

Swanson, K. M.; Apte, S.; Aalto, R.; Marshall, A.; Dietrich, W.

2004-12-01

289

Development of an Electrohydraulic Total Artificial Heart.  

National Technical Information Service (NTIS)

The third annual report on the development of an implantable untethered Total Artificial Heart (TAH) is presented. The system consists of (1) two blood chambers, and four trileaflet valves fabricated from Angioflex(R), a polyetherurethane, resulting in se...

A. R. Millner B. Ochs D. Menn R. Cumming R. T. V. Kung

1990-01-01

290

Stream sediment and nutrient loads in the Tahoe Basin--estimated vs monitored loads for TMDL "crediting".  

PubMed

Total maximum daily load (TMDL) programs utilize pollutant load reductions as the primary strategy to restore adversely affected waters of the USA. Accurate and defensible "crediting" for TMDL reductions of sediment and nutrients requires stream monitoring programs capable of quantitative assessment of soil erosivity and the "connectivity" between erosive areas and stream channels across the watershed. Using continuous (15-min) stream monitoring information from typical alpine, snowmelt-driven watersheds [Ward (2,521 ha), Blackwood (2,886 ha), and Homewood (260 ha, Homewood Mountain Resort--HMR) Creeks] on the west shore of the Lake Tahoe Basin, daily sediment (and nutrient for HMR) loads are determined and compared with those developed from estimated load-flow relationships developed from grab sampling data. Compared to the previously estimated sediment load-discharge relationships, measured curves were slightly below those estimated, though not significantly so at Blackwood and Ward Creeks in the period 1997-2002. Based on average daily flowrates determined from calibrated hydrologic modeling during the period 1994-2004, average daily flowrate frequency distributions per year are determined from which load reduction "crediting" towards TMDL targets can be evaluated. Despite seemingly similar estimated and measured sediment load-flow relationships, annual "estimated" loads exceeded those "measured" by about 40 % for Ward and Blackwood Creeks and over 300 times for HMR Creek. Similarly, though less dramatic, estimated annual nutrient loads at HMR Creek exceeded those measured by 1.7 and 6 times for total nitrogen and total phosphorus, respectively. Such results indicate that actual measured load-flow relationships are likely necessary for realistic quantitative and defensible TMDL crediting. PMID:23435852

Grismer, M E

2013-09-01

291

Recycling and burial of organic carbon in sediments of the Porcupine Abyssal Plain, NE Atlantic  

NASA Astrophysics Data System (ADS)

Rates of degradation, recycling and burial of organic carbon (OC) and their temporal and spatial variability were investigated in deep-sea sediments of the Porcupine Abyssal Plain (PAP) in the Northeast Atlantic Ocean (depth 4800-4850 m) during six cruises in August 1996—April 1999. Benthic fluxes of total dissolved inorganic carbon ( CT) and alkalinity ( AT) were measured in situ using benthic chambers of a free-vehicle benthic lander on four of the cruises. To obtain the OC oxidation rate ( Cox), the CT flux in each chamber was corrected for CaCO 3 dissolution. Burial of OC was determined by using downcore profiles of OC ( n=20) in the solid phase of the sediment and sediment accumulation rates estimated from a model age based on 14C dating of foraminifera. Results obtained showed that during 1996-1999 Cox rates in PAP sediments varied between deployments from 0.21±0.04 to 0.86±0.23 mmol m -2 d -1 with a total mean of 0.46 mmol m -2 d -1 (SD±0.37, n=31). No statistically significant spatial (between stations) or temporal (seasonal as well as interannual) variation in the Cox rates could be detected during the sampling period. The mean burial rate was determined to be 0.03±0.01 mmol m -2 d -1. On average over the sampling period, ˜94% of the particulate organic carbon (POC) deposited was recycled as CT to the overlying water and ˜6% was buried. The calculated mean POC demand during 1996-1999 of 0.49±0.37 mmol m -2 d -1 (the sum of corrected CT and burial fluxes) was not significantly different from the annual integrated mean POC supply (1997-1999) of 0.24±0.06 mmol m -2 d -1 estimated from calibrated sediment traps 1800 mab at the same locality.

Ståhl, Henrik; Tengberg, Anders; Brunnegård, Jenny; Hall, Per O. J.

2004-06-01

292

Sorption and sedimentation of Zn and Cd by seston in southern Lake Michigan  

SciTech Connect

The sorption and sedimentation of Zn and Cd by southern Lake Michigan seston particles was investigated using /sup 65/Zn and /sup 109/Cd in 21 radiotracer experiments. The time-series sorption by total seston >0.45 ..mu..m was asymptotic with apparent equilibria of approx.100-200 ng Zn/L and approx.1.0-2.0 ng Cd/L, occurring in approx.24-30h during the summer phytoplankton bloom. Studies of the sorption by different particle size fractions showed that the abundance of phytoplankton and detritus control the concentrations of particle-bound Zn and Cd. The seasonal maximum concentrations of particle-bound Zn and Cd correlated with the development of both the summer and fall phytoplankton blooms. Serial additions of Zn and Cd in combination with the radiotracers showed that these additions inhibit the sorption of both metals as their toxic effects are expressed. Coupling of the particle-bound Zn and Cd estimates for the period May to December with data on the seasonal variations in the net settling velocity in southern Lake Michigan provided annual sedimentation rates of approx.9 ..mu..g Zn/cm/sup 2/.yr and approx.0.1 ..mu..g Cd/cm/sup 2/.yr. Likewise, dividing the particle-bound estimates by the dry weight of total seston in the samples provided sediment concentration estimates of approx.38-185 ng Zn/mg dry weight (ppm) and 0.5-2.3 ng Cd/mg dry weight that agree with measured levels from the surficial Lake Michigan sediment. The results of these experiments suggest that, if the dissolved concentrations of Zn and Cd do increase to toxic levels, the impacts on phytoplankton may potentiate further increases in the dissolved levels by reducing plankton sorption and removal by sedimentation.

Paker, J.I.; Stanlaw, K.A.; Marshall, J.S.; Kennedy, C.W.

1982-01-01

293

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

294

Seasonal mass balance of sediment transport along the upper Urumqi River in Tianshan  

NASA Astrophysics Data System (ADS)

Measurements were performed during two complete flow seasons on the Urumqi River, a proglacial mountain stream in the northeastern flank of the Tianshan, an active mountain range in Central Asia. This survey of flow dynamics and sediment transport (dissolved, suspended and bed loads), together with a 25-year record of daily discharge, enables the assessment of secular denudation rates on this high mountain catchment of Central Asia. Our results show that chemical weathering accounts for more than one-third of the total denudation rate. Sediment transported as bed load cannot be neglected in the balance, given that sand and gravel transport accounts for one third of the solid load of the river. Overall, the mean denudation rates are low, averaging 46 t - km-2 - yr-1(17-18 m Myr-1). We furthermore analyse the hydrologic record to show that the long-term sediment budget is not dominated by extreme and rare events but by the total amount of rainfall or annual runoff. The rates we obtain are in agreement with rates obtained from the mass balance reconstruction of the Plio-Quaternary gravely deposits of the foreland but signicantly lower than the rates recently obtained from cosmogenic dating of the Kuitun River sands, west of the Urumqi River. We show that the resolution of this incompatibility may have an important consquence for our understanding of the interplay between erosion and tectonics in the semi-humid ranges of Central Asia.

Métivier, F.; Liu, Y.; Gaillardet, J.; Ye, B.; Meunier, P.; Narteau, C.; Lajeunesse, E.; Han, T.

2012-04-01

295

Hydrology, suspended sediment dynamics and nutrient loading in Lake Takkobu, a degrading lake ecosystem in Kushiro Mire, northern Japan.  

PubMed

Suspended sediment and nutrient loadings from agricultural watersheds have lead to habitat degradation in Lake Takkobu. To examine their relationships with land-use activities, we monitored sediment, nutrient and water discharges into the lake for a 1-year sampling period. The Takkobu River contributed the largest portion of the annual water discharge into the lake, compared with the other tributaries. During dry conditions, lake water flowed into the Kushiro River, and conversely during flooding, Kushiro River water flowed into the lake. Inflows from the Kushiro River had a high proportion of inorganic matter, with high concentrations of total nitrogen and total phosphorus, attributed to agricultural land-use development and stream channelization practiced since the 1960s in the Kushiro Mire. Nutrient loadings from these two rivers were significantly higher during flooding than in dry conditions. However, there was no clear correlation between river discharge and nutrient concentrations. Since land-use activities in the Kushiro River and Takkobu River watersheds were concentrated near rivers, nutrients easily entered the drainage system under low flow conditions. In contrast, water discharged from small, forest-dominated watersheds contained a low proportion of inorganic matter, and low nutrient concentrations. The suspended sediment delivered to the lake during the sample period was estimated as approximately 607 tons, while the total nitrogen and total phosphorus inflows were about 10,466 and 1,433 kg, respectively. Suspended sediment input into the lake was 65%, and total nitrogen and total phosphorus were 40% and 48%, respectively, being delivered by the Kushiro River. PMID:18060513

Ahn, Young Sang; Nakamura, Futoshi; Mizugaki, Shigeru

2008-10-01

296

Efficiency of erosion mitigation strategies in reducing sediment-loading rates from unpaved road networks into coral reef-bearing waters of the Eastern Caribbean  

NASA Astrophysics Data System (ADS)

Erosion from unpaved road networks represents a critical source of stress affecting the coral reef systems of the U.S. Virgin Islands in the Northeastern Caribbean. Combined community- and government-driven efforts to reduce sediment contributions from unpaved roads in the island of St. John have consisted in improving road drainage design, paving selected road segments, and constructing sediment retention structures. Here we describe empirical evidence attesting to the efficacy of these mitigation efforts. Road drainage improvements reduced sediment production rates to about a third of pre-treatment levels. Road-segment scale erosion rates following paving ranged from 5-30% of pre-treatment levels, depending on road slope and road grading frequency. A 616-m3 sediment retention pond proved to contain 86 Mg of sediment annually and about 94% of the runoff generated from a 12 ha sub-catchment with an unpaved road density of 19 km km-2. Watershed-scale modeling evaluations suggested that the combination of these three treatments within the 13-km2 Coral Bay watershed resulted in the reduction of annual sediment delivery rates from 445 Mg yr-1 to 327 Mg yr-1. Cost-effectiveness analyses suggest that road drainage improvements and construction of the detention pond provided the greatest reductions in sediment delivery per total amount of funds spent. Even though paving is a proven erosion control method, the high costs involved made it a relatively cost-inefficient method. Marine sedimentation of terrigenous sediment (land-derived) was regularly monitored (every 26 days) at 15 near-shore and reef sites from 2008 to 2013 below the treated and undeveloped watersheds. Sediment composition (% terrigenous) determined by loss on ignition was multiplied by the total sediment accumulation rate in tube sediment traps to obtain terrigenous sediment accumulation rates (in mg cm-2 d-1). Mean terrigenous sediment accumulation rates were over 24 (near-shore) and 6 (reef) times greater below developed compared to undeveloped watersheds. Comparisons of marine terrigenous accumulation rates between undeveloped and developed areas were consistent with those based on modeled sediment yields. At all near-shore sites below mitigated watersheds, mean post-mitigation marine terrigenous sediment accumulation rates were reduced by up to 70% of mean pre-mitigation values. Nevertheless, further analysis is required to evaluate whether the observed post-mitigation reduction is strictly related to watershed restoration. At the developed coral reef sites, acute terrigenous sediment accumulation rates during major storms equaled or exceeded coral-stressing levels (>50 mg cm-2d-1). Results from this research are being employed in the design of mitigation strategies within our study areas as well as in other parts of the Caribbean where roads are considered a major threat to coral reefs.

Ramos-Scharron, Carlos; Gray, Sarah; Sears, Whitney

2014-05-01

297

Large sediment budget of Algerian deltas  

NASA Astrophysics Data System (ADS)

This presentation studies the causes of the widespread decline of Algerian coast as erosion watershed is among the largest in the world. Six areas including deltaic mouths of the wadis are studied by mapping methods, by modelling sediment transport in suspension and bed load as well as modeling the long-shore redistribution of sediment on the coast. If using the model of Probst (1992) to 5 parameters gives good results for quantifying sediment transport in suspension carried by the wadis, as the sites studied transport modelling along-shore by the methods of Kamphuis, CERC and Van Rijn can lead to conflicting data in relation to comments made. By trapping a significant portion of material carried by the wadis, the role played by dams in the sediment transport towards the coast is also considered and quantified in order to make a sediment budget in the total volume of 103 years. We evidence chronic deficit in sediment from the rivers in relation to dams constructions. Along the coastline, erosion is dominant and littoral cell sediment budget suggest offshore loss of sediments for each case. Even if hard engineering coastal structures locally stabilize the shoreline, a large retreat is observed. There is no doubt that these regions should resolve a huge sediment source to sink challenge during the 21th century.

quinquis, michel; sabatier, francois; anthony, edward; delanghe-sabatier, doriane

2014-05-01

298

Partitioning of Heavy Metals In Estuarine Sediments Cores and Implications For The Use of Sediment Quality Standards  

NASA Astrophysics Data System (ADS)

Total metal concentrations and partitioning behaviour of metal contaminants in sedi- ment cores collected from three estuaries (Thames, Medway and Blackwater) in south east England were examined with respect to sediment quality guidelines (SQGs). Metal data from surface sediments were compared with historically contaminated sed- iments at depth to determine whether vertical contaminant profiles should be consid- ered when applying sediment quality guidelines. Initial investigations, based on total metal concentrations in surface sediments indicate that there is no risk to biota in any of the estuaries studied. However, in the Medway and Thames estuaries, which have received past industrial inputs, consideration of sediments at depth is also im- portant. Comparison of sediments at depth with SQGs suggests that local authorities should examine vertical metal profiles, particularly in estuaries that are experiencing low sediment accumulation rates, erosion or dredging activities. Total metal data indi- cate that the risk to biota is greatest in the Thames followed by the Medway and then the Blackwater. However, metal partitioning data indicate that the risk to biota is com- parable for the Medway and the Blackwater with the potentially bioavailable fraction presenting no risk to biota. Conversely, over 70% of metals are labile in the Thames Estuary sediments and toxic effects are probable. This suggests that the application of sediment quality guidelines using total sediment metal concentrations may over or under estimate the risk to biota in geochemically dissimilar estuarine sediments.

Spencer, K.; MacLeod, C.

299

Mathematical simulation of sediment and radionuclide transport in estuaries  

SciTech Connect

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

Onishi, Y.; Trent, D.S.

1982-11-01

300

GJI Geomagnetism, rock magnetism and palaeomagnetism Bacterial magnetite produced in water column dominates lake sediment mineral magnetism: Lake Ely, USA  

Microsoft Academic Search

SUMMARY Environmental magnetic studies of annually laminated sediments from Lake Ely, northeastern Pennsylvania, USA indicate that bacterial magnetite is the dominant magnetic mineral in the lake sediment. In previous studies of Lake Ely sediment, the dark, organic-rich layers in the annual laminae were interpreted to have high-intensity saturation isothermal remanent magnetizations (SIRMs) while the light-coloured, silt-rich layers have low-intensity SIRMs.

BangYeon Kim; Kenneth P. Kodama; Robert E. Moeller

301

Health-Based Criteria for Sediment Disposal Options: A Case Study of the Port of New York\\/New Jersey  

Microsoft Academic Search

Approximately 4 million cubic yards of sediment are dredged annually from the Port of New York and New Jersey in order to maintain navigable channels. In many cases, the sediments contain elevated levels of numerous contaminants. The New York District of the U.S. Army Corps of Engineers and U.S. Environmental Protection Agency Region II employ a framework of sediment quality

Steave Su; Julie Rothrock; Leslie Pearlman; Brent Finley

2001-01-01

302

Empirical and conceptual modelling of the suspended sediment dynamics in a large tropical African river: the Upper Niger river basin  

Microsoft Academic Search

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

C. Picouet; B. Hingray; J. C. Olivry

2001-01-01

303

Little Ice Age recorded in summer temperature reconstruction from varved sediments of Donard Lake, Baffin Island, Canada  

Microsoft Academic Search

Clastic varved sediments from Donard Lake, in the Cape Dyer region of Baffin Island, provide a 1250 yr record of decadal-to-centennial scale climate variability. Donard Lake experiences strong seasonal fluctuations in runoff and sediment fluxes due to the summer melting of the Caribou Glacier, which presently dominates its catchment. The seasonal variation in sediment supply results in the annual deposition

J. J. Moore; K. A. Hughen; G. H. Miller

2001-01-01

304

Dissolved and particulate carbohydrates in contrasting marine sediments  

NASA Astrophysics Data System (ADS)

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.

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

2000-03-01

305

Influence of sediment-organic matter quality on growth and polychlorobiphenyl bioavailability in Echinodermata (Amphiura filiformis)  

Microsoft Academic Search

Sediment total organic carbon (TOC) content is considered to be a primary food source for benthic invertebrates and a major factor influencing the partitioning and bioavailability of sediment-associated organic contaminants. Most studies report that both toxicity and uptake of sediment-associated contaminants by benthic organisms are inversely proportional to sediment TOC content. The aim of this study was to determine the

J. S. Gunnarsson; M. E. Granberg; H. C. Nilsson; R. Rosenberg; B. Hellman

1999-01-01

306

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

307

Seasonal flux and assemblage composition of planktic foraminifers from a sediment-trap study in the northern Gulf of Mexico  

USGS Publications Warehouse

Sediment-trap samples from the northern Gulf of Mexico reveal that Globorotalia truncatulinoides, Neogloboquadrina dutertrei, Pulleniatina spp. (includes P. obliquiloculata and P. finalis), and the Globorotalia menardii group (includes Gt. menardii, Gt. tumida, and Gt. ungulata) generally occur in cold months. Globigerinoides ruber (white and pink varieties) and Globigennoides sacculifer occur throughout the year. The seasonal occurrence of individual taxa of planktic foraminifers in the Gulf of Mexico have important differences with the seasonal occurrence of the same taxa observed in a 6-year sediment-trap dataset from the western Sargasso Sea. Thus information on the ecologic preferences of individual taxa determined in one region cannot necessarily be applied directly to another area. In the northern Gulf of Mexico 90% of the total flux of Globorotalia truncatulinoides tests to sediments occurs in January and February. Mg/Ca and d18? measurements indicate that nonencrusted forms of Gt. truncatulinoides calcify in the upper-surface-mixed zone. Thus, analyses of nonencrusted Gt. truncatulinoides in sediments of the northern Gulf of Mexico have potential for monitoring past conditions in the winter-surface-mixed layer. The relatively low overall abundance of Globigerinoides ruber (white) in sediment-trap samples is anomalous because Gs. ruber (white) is one of the most abundant foraminifers in>150 µm census data from northern Gulf of Mexico Holocene sediment core samples. Globigerinoides ruber (pink) is a relatively persistent and common component of the sediment-trap samples. Thus Gs. ruber (pink) has potential as a proxy for mean annual sea-surface temperature in the Gulf of Mexico

Poore, Richard Z.;Spear, Jessica W.;Tedesco, Kathy A.

2013-01-01

308

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

PubMed

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

Bogen, J; Bønsnes, T E

2001-02-01

309

Proxies of pre-industrial charcoal production and land use in lake sediments from South Brandenburg, Germany  

NASA Astrophysics Data System (ADS)

During the last decades, archaeological research has revealed that large-scale charcoal burning was carried out in Lower Lusatia (South Brandenburg) situated within the North Germany Lowland. From the 17th to the 19th century, charcoal was mainly produced for the ironwork in Peitz. Within the framework of the ICLEA project lake sediments from two lakes, Byhleguhrer See and Großsee, are investigated to study the impact of pre-industrial charcoal production on the environment. The investigation area is situated c. 15 km ne of Cottbus in the Tauerscher Forst, an area mainly forested with pine. The climate is continental (mean annual air temperature: 8-9 °C, mean annual precipitation sum: 565 mm). The geology and geomorphology were formed by Quaternary glaciations. Two lakes, Großsee and Byhleguhrer See, were selected for our research. Großsee (51° 56,007' N, 14° 28,282' E, 63 m a.s.l., max. 9 m water depth) is c. 0.31 km2 large and lies in the central part of the Tauersche Forst. Byhleguhrer See (51° 55,41' N, 14° 9,922' E, 50 m a.s.l., max. 1 m water depth) is situated in c. 22 km linear distance W of Großsee at the western margin of the Tauersche Forst. This lake is c. 0.89 km2 large. During the last 50 years Byhleguhrer See and its surrounding was intensively used (fishing, wastewater discharge, agriculture). Three short sediment cores were gained from each lake. All cores were opened, described and photographed. Magnetic susceptibility (split-core logger) and total element contents (µXRF) were measured on selected cores. Based on the first data, two sediment cores were chosen for further analyses (CNS, 14C-dating, etc.). The sediment core from Großsee (GR13-SH-PO56) is 77 cm long. The sediments are quite homogenous and have a high organic content. S values are increased in the upper part (10-30 cm sediment depth) correlating with high magnetic susceptibility and iron values, which hint on the occurrence of pyrite in the sediment. 14C-dating of the sediment base (71-75 cm sediment depth) resulted in an age of 778-1018 AD (2?, Poz-58091). The sediment core from Byhleguhrer See (BHG-13-1) is 107 cm long. Again, the sediments are homogenous and are rich in organics. CNS analyses are in progress. In the upper part high Fe and S contents (µXRF) correlate with high magn. susceptibility values hinting on pyrite. The base of the core (100-107 cm sediment depth) was 14C-dated to 1739-1531 BC (2?, Poz-58092) and 2872-2471 BC (2?, Poz-58093). Preliminary tests of charcoal particle contents of both sediment cores were carried out. In conclusion, the sediments of Großsee and Byhleguhrer See are quite homogenous. An anthropogenic disturbance of the uppermost sediment part cannot be excluded. But, the 14C-datings resulted in reasonable ages, even though we cannot rule out a hardwater effect on the radiocarbon ages of Byhleguhrer See. Most probably, the cores contain the relevant time span (17th - 19th century), when charcoal was produced in the surroundings. Besides the CNS analyses and absolute age determinations, at present the focus lies on microscopic charcoal analyses.

Raab, Alexandra; Frantiuc, Alexandru; Brademann, Brian; Ott, Florian; Hirsch, Florian; Brauer, Achim; Raab, Thomas

2014-05-01

310

Geochemistry of Peruvian near-surface sediments  

NASA Astrophysics Data System (ADS)

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.

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

2004-11-01

311

Linking sediment transport and channel roughness in bedrock rivers  

NASA Astrophysics Data System (ADS)

Improved understanding of sediment transport processes in bedrock rivers is needed for both upland management and for prediction of landscape evolution. Recent advances have focussed on the sediment processes in bedrock rivers that have implications for both sediment transfer and bedrock incision. A significant component of grain-scale transport dynamics is the difference in roughness between bedrock and alluvial surfaces. Although bedrock surfaces typically exhibit roughness at a range of scales, they are often locally smooth at the scale of individual grains; significant roughness can however also exist at this length scale. Grains on smooth bedrock surfaces are more easily entrained than grains on alluvial patches because of the higher grain exposure and lower pivoting angles. Recent laboratory and modelling work has demonstrated the effect of these differing entrainment thresholds on the development of sediment cover in a smooth channel. Here we model the effect of the spatial distribution of roughness in a bedrock river on the total sediment transport capacity of the channel. The model represents the channel as two parallel strips; an alluvial strip and a bedrock strip with sparse sediment cover. We evaluate the effect of sediment cover on the sediment flux conveyed by the entire channel, including the total sediment flux integrated over multiple flow events. A range of conditions between two end members are explored; sediment cover is increased either by widening the alluvial strip, and/or by increasing the density of sediment cover on the bedrock strip (subject to the condition that there is not significant interaction between grains). Depending on the exact conditions applied, increasing sediment cover can actually decrease the total sediment flux in the channel as a result of the decreased mobility of the alluvial sediment. However, laboratory experiments show that sediment accumulation alters the spatial pattern of roughness in bedrock channels, affecting local hydraulics and hence entrainment and deposition. To fully understand the interactions between hydraulics and sediment on bedrock surfaces, further components of the roughness also need to be taken into consideration. Another area for consideration is the initial roughness of the bedrock surface, and the impact that this has on sediment cover development, especially given the common assumption of smooth bedrock surfaces in both flume and modelling studies. We present some preliminary findings that show the partitioning of sediment cover into alluvial patches and sparse individual grains in channels with ranges of both bedrock roughness and total sediment cover, and consider the effect of these findings on total sediment flux.

Hodge, R. A.; Hoey, T.; Maniatis, G.

2012-12-01

312

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

USGS Publications Warehouse

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.

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

2009-01-01

313

Yearly variation and annual cycle of total column ozone over New Delhi (29°N, 77°E), India and Halley Bay (76°S, 27°W), British Antarctic Survey Station and its effect on night airglow intensity of OH(8, 3) for the period 1979-2005  

NASA Astrophysics Data System (ADS)

A critical analysis made on the long-term monthly, seasonal, yearly variation and annual cycle of total column ozone (TCO) concentration at New Delhi (29°N, 77°E), India and Halley Bay (76°S, 27°W), a British Antarctic Service Station reveals more decline in yearly mean ozone concentration at Halley Bay than at New Delhi from 1979 to 2005. The nature of variations of monthly mean TCO during the months of August and September was the most identical with that of yearly mean ozone values at New Delhi and Halley Bay, respectively, for the same period. Annual cycles of TCO over these stations are completely different for the above period. The effect of O3 depletion on night airglow emission of OH(8, 3) line at New Delhi and Halley Bay has been studied. Calculations based on chemical kinetics show that the airglow intensity of OH(8, 3) has also been affected due to the depletion of O3 concentration. The yearly variations and annual cycle of intensities of OH(8, 3) line for the above two stations are depicted and compared. It has been shown that the rate of decrease of intensity of OH(8, 3) line was comparatively more at Halley Bay due to dramatic decrease of Antarctic O3 concentration.

Jana, P. K.; Saha, D. K.; Sarkar, D.

2012-12-01

314

Sediment fingerprinting in Northern Jordan - approaching sediment comparability  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

315

Elwha River Restoration: Sediment Management  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

316

Comment on "Wetland sedimentation from hurricanes Katrina and Rita".  

PubMed

Turner et al. (Reports, 20 October 2006, p. 449) measured sedimentation from Hurricanes Katrina and Rita in coastal Louisiana and inferred that storm deposition overwhelms direct Mississippi River sediment input. However, their annualized hurricane deposition rate is overestimated, whereas riverine deposition is underestimated by at least an order of magnitude. Their numbers do not provide a credible basis for decisions about coastal restoration. PMID:17431155

Törnqvist, Torbjörn E; Paola, Chris; Parker, Gary; Liu, Kam-Biu; Mohrig, David; Holbrook, John M; Twilley, Robert R

2007-04-13

317

Environmental geology and geochemistry of lake sediments (Holzmaar, Eifwl, Germany)  

Microsoft Academic Search

Quaternary sediments of the lake Holzmaar comprise a well laminated, undisturbed sequence of diatomaceous gyttja, silt, clay\\u000a laminites and tuff layers. The annually deposited gyttja has been dated by varve chronology yielding a continuous high-resolution\\u000a time sequence for the Holocene and early Pleistocene. These organic-rich sediments provide an unique paleolimnological record\\u000a on climatic changes, forest fires, volcanic eruptions, and anthropogenic

B. Lottermoser; R. Oberhänsli; B. Zolitschka; J. Negendank; U. Schütz; J. Boenecke

1993-01-01

318

Total Phosphorus Loads for Selected Tributaries to Sebago Lake, Maine  

USGS Publications Warehouse

The streamflow and water-quality datacollection networks of the Portland Water District (PWD) and the U.S. Geological Survey (USGS) as of February 2000 were analyzed in terms of their applicability for estimating total phosphorus loads for selected tributaries to Sebago Lake in southern Maine. The long-term unit-area mean annual flows for the Songo River and for small, ungaged tributaries are similar to the long-term unit-area mean annual flows for the Crooked River and other gaged tributaries to Sebago Lake, based on a regression equation that estimates mean annual streamflows in Maine. Unit-area peak streamflows of Sebago Lake tributaries can be quite different, based on a regression equation that estimates peak streamflows for Maine. Crooked River had a statistically significant positive relation (Kendall's Tau test, p=0.0004) between streamflow and total phosphorus concentration. Panther Run had a statistically significant negative relation (p=0.0015). Significant positive relations may indicate contributions from nonpoint sources or sediment resuspension, whereas significant negative relations may indicate dilution of point sources. Total phosphorus concentrations were significantly larger in the Crooked River than in the Songo River (Wilcoxon rank-sum test, p<0.0001). Evidence was insufficient, however, to indicate that phosphorus concentrations from medium-sized drainage basins, at a significance level of 0.05, were different from each other or that concentrations in small-sized drainage basins were different from each other (Kruskal-Wallis test, p= 0.0980, 0.1265). All large- and medium-sized drainage basins were sampled for total phosphorus approximately monthly. Although not all small drainage basins were sampled, they may be well represented by the small drainage basins that were sampled. If the tributaries gaged by PWD had adequate streamflow data, the current PWD tributary monitoring program would probably produce total phosphorus loading data that would represent all gaged and ungaged tributaries to Sebago Lake. Outside the PWD tributary-monitoring program, the largest ungaged tributary to Sebago Lake contains 1.5 percent of the area draining to the lake. In the absence of unique point or nonpoint sources of phosphorus, ungaged tributaries are unlikely to have total phosphorus concentrations that differ significantly from those in the small tributaries that have concentration data. The regression method, also known as the rating-curve method, was used to estimate the annual total phosphorus load for Crooked River, Northwest River, and Rich Mill Pond Outlet for water years 1996-98. The MOVE.1 method was used to estimate daily streamflows for the regression method at Northwest River and Rich Mill Pond Outlet, where streamflows were not continuously monitored. An averaging method also was used to compute annual loads at the three sites. The difference between the regression estimate and the averaging estimate for each of the three tributaries was consistent with what was expected from previous studies.

Hodgkins, Glenn A.

2001-01-01

319

Wetland sedimentation from hurricanes Katrina and Rita.  

PubMed

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

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

2006-10-20

320

Particle Fluxes, South Central Black Sea: 1982-1985 (Black Sea Sedimentation Data File, Volume 1).  

National Technical Information Service (NTIS)

Annual particle fluxes were measured by sediment traps deployed at a station about 40 km north of Amasra, Southern Black Sea, by an international team of oceanographers from Germany, Turkey, and the United States. This experiment continuously monitored oc...

S. Honjo S. J. Manganini V. L. Asper B. J. Hay A. Karowe

1987-01-01

321

Annual cycle in co-located in situ, total-column, and height-resolved aerosol observations in the Po Valley (Italy): Implications for ground-level particulate matter mass concentration estimation from remote sensing  

NASA Astrophysics Data System (ADS)

Remote sensing represents a prospective tool to complement in situ measurements for monitoring particulate matter air pollution. The remotely sensed aerosol metric which is generally related to the in situ measured particulate matter mass concentration (PM) is the aerosol optical thickness (AOT), the vertically integrated aerosol extinction that optically quantifies the aerosol load in the whole atmospheric column. Annual variations in AOT and PM can follow very different patterns, indicating that the AOT-to-PM conversion is not straightforward. In the Po Valley, northern Italy, AOT and PM seasonal cycles exhibit a marked phase shift. Making use of aerosol extinction vertical profiles derived from continuous aerosol lidar measurements, we further searched through the AOT-to-PM10 relationship in this region. On the basis of a 2-year (2006-2007) multisensor database, including remote sensing observations from ground and space and in situ measurements, this study: (1) discloses for the first time the height-resolved seasonal variability of the aerosol optical properties in the Po Valley, (2) demonstrates and quantifies the crucial role of the aerosol vertical distribution in the AOT-to-PM relationship in this region, (3) suggests a methodology to rescale AOT to ground-level aerosol extinction values that correlate with PM concentration and from which PM10 annual average and exceedances frequency of daily limit value can be retrieved within a few percentage points, and (4) highlights that the hygroscopic growth of the particles in the atmosphere is a critical factor for comparing in situ-measured to remotely sensed aerosol properties.

Barnaba, F.; Putaud, J. P.; Gruening, C.; Dell'Acqua, A.; Dos Santos, S.

2010-10-01

322

Long-term trends in catchment export and lake retention of dissolved organic carbon, dissolved organic nitrogen, total iron, and total phosphorus: The Dorset, Ontario, study, 1978-1998  

NASA Astrophysics Data System (ADS)

Annual catchment export of total phosphorus (TP), dissolved organic carbon (DOC), total iron (Fe), and dissolved organic nitrogen (DON) to seven lakes in central Ontario was measured between 1978 and 1998. Fluctuations in annual water discharge and total DOC load (including precipitation) to the lakes over the 20-year period were similar in the seven study lakes. DOC export to the lakes responded proportionally to changes in discharge, decreasing during drier and warmer years. There were similar but less accentuated variations in annual DOC lake concentrations. There were no clear regional trends evident during the 20-year period toward drier or wetter conditions, less DOC load, clearer lakes, etc., that could be interpreted as signaling a shift toward a different equilibrium state. The fraction of the DOC load retained by lakes (transferred to sediments and the atmosphere) increased during an extended dry period. Fe, TP, and DON export decreased more than DOC export during the extended dry period. Runoff appears to affect Fe, TP, and DON export first by controlling export of organic matter and second by affecting water table position and thus redox levels in the surface layer of peatlands. Permanently drier conditions with less runoff would likely lead to clearer lakes that are less productive. Conversely, increased runoff would lead to more colored and productive lakes. Both scenarios have implications for subsistence and sport fishing economies.

Dillon, Peter J.; Molot, Lewis A.

2005-09-01

323

Sediment and phosphorus transport in irrigation furrows.  

PubMed

Sediment and phosphorus (P) in agricultural runoff can impair water quality in streams, lakes, and rivers. We studied the factors affecting P transfer and transport in irrigated furrows in six freshly tilled fallow fields, 110 to 180 m long with 0.007 to 0.012 m m-1 slopes without the interference of raindrops or sheet flow that occur during natural or simulated rain. The soil on all fields was Portneuf silt loam (coarse-silty, mixed, superactive, mesic Durinodic Xeric Haplocalcids). Flow rate, sediment concentration, and P concentrations were monitored at four, equally spaced locations in each furrow. Flow rate decreased with distance down the furrow as water infiltrated. Sediment concentration varied with distance and time with no set pattern. Total P concentrations related directly to sediment concentrations (r2=0.75) because typically >90% of the transported P was particulate P, emphasizing the need to control erosion to reduce P loss. Dissolved reactive phosphorus (DRP) concentrations decreased with time at a specific furrow site but increased with distance down the furrow as contact time with soil and suspended sediment increased. The DRP concentration correlated better with sediment concentration than extractable furrow soil P concentration. However, suspended sediment concentration tended to not affect DRP concentration later in the irrigation (>2 h). These results indicate that the effects of soil P can be overshadowed by differences in flow hydraulics, suspended sediment loads, and non-equilibrium conditions. PMID:16585621

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

2006-01-01

324

Sediment characteristics of small streams in southern Wisconsin, 1954-59  

USGS Publications Warehouse

The results of investigations of the sediment and water discharge characteristics of Black Earth Creek, Mount Vernon Creek, and Yellowstone River from 1954 to 1959 and Dell Creek for 1958 and 1959 indicate large differences in annual runoff and sediment yields. The suspended-sediment discharge of Black Earth Creek averaged 3,260 tons per year or 71 tons per square mile : the annual yields ranged from 27 to 102 tons per square mile. The annual suspended-sediment yield of Mount Vernon Creek ranged from 48 to 171 tons per square mile and averaged 96 tons per square mile. The maximum daily discharge was 1,120 tons on April 1, 1960, during a storm which produced 67 percent of the suspended load for that water year and exceeded the discharge for the preceding 3 years. The sediment discharge of the Yellowstone River averaged 6,870 tons per year or 236 tons per square riffle. The maximum daily sediment discharge, 3,750 tons on April 1, 1959, occurred during a 14-day period of high flow during which the sediment discharge was 15,480 tons. In 1958 and 1959, Dell Creek had suspended-sediment yields of 4.7 and 26 tons per square mile of drainage area. The suspended sediment transported by Black Earth and Mount Vernon Creeks is about two-thirds clay and one-third silt. For Yellowstone River the particle-size distribution of the suspended sediment ranged from three-fourths clay and one-fourth silt during periods of low sediment discharge to one-third clay and two-thirds silt during high sediment discharges. For Dell Creek nearly all of the suspended sediment is clay, but the bed load is sand. The mean sediment concentration of storm runoff averaged two to three times more in the summer than in the winter. No significant changes with time occurred in the relation between storm runoff and sediment yield.

Collier, Charles R.

1963-01-01

325

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

SciTech Connect

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

Day, K.E.; Kirby, R.S.; Reynoldson, T.B. [National Water Research Inst., Burlington, Ontario (Canada). Dept. of the Environment

1995-08-01

326

Total and subtotal abdominal hysterectomy.  

PubMed

Hysterectomy is one of the most frequently performed operations in the world, accounting for 500,000-600,000 procedures annually in the USA; the abdominal route for hysterectomy is the preferred route in 60-80% of these operations. Although the number of total abdominal hysterectomies performed annually has decreased, the number of subtotal abdominal hysterectomies increased by >400%. The major indications for abdominal hysterectomy include abnormal uterine bleeding, myomata uteri, adenomyosis, endometriosis, neoplasia, and chronic salpingitis. The basis for selection for subtotal versus total hysterectomy has little in the way of factual data to support it and may actually present some significant disadvantages, such as continued menstruation and cervical prolapse. The detailed technique for performing intrafascial abdominal hysterectomy relies heavily on precise knowledge of pelvic anatomy and compulsive detail to tissue handling. The consistent and correct usage of prophylactic antimicrobials, measures to prevent thromboemboli, and procedures to avoid urinary retention are key to the overall success of the surgery. PMID:15985251

Baggish, Michael S

2005-06-01

327

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)

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.

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

2012-04-01

328

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

329

Fluvial sediment concepts  

USGS Publications Warehouse

This report is the first of a series concerned with the measurement of and recording of information about fluvial sediment and with related environmental data needed to maintain and improve basic sediment knowledge. Concepts presented in this report involve (1) the physical characteristics of sediment which include aspects relative 'to weathering, soils, resistance to erosion, and particle size, (2) sediment erosion, transport, and deposition characteristics, which include aspects relative to fine sediment and overland flow, coarse sediment and streamflow, variations in stream sediment concentration, deposition, and denudation, (3) geomorphic considerations, which include aspects relative to the drainage basin, mass wasting, and channel properties, (4) economic aspects, and (5) data needs and program objectives to be attained through the use of several kinds of sediment records.

Guy, Harold P.

1970-01-01

330

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

331

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

USGS Publications Warehouse

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.

Fisher, Lawrence H.; Wood, Tamara M.

2004-01-01

332

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

USGS Publications Warehouse

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.

Kalnejais, L. H.; Martin, W. R.; Bothner, M. H.

2010-01-01

333

Activities about Sediments  

NSDL National Science Digital Library

This series of activities will allow students to learn more about sediments and develop their skills in using a variety of strategies to study our planet. The activities include using a stereomicroscope to view tiny sediment grains, finding their actual sizes by comparing them with the scope's field of view, separating a sediment sample using a set of sieves, and preparing bar graphs representing the grain size distribution of the sediment. The site also includes instructions for a proper lab write-up.

Passow, Michael

334

Coal industry annual 1997  

SciTech Connect

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.

NONE

1998-12-01

335

Sediment budget for a polluted Hawaiian reef using hillslope monitoring and process mapping (Invited)  

NASA Astrophysics Data System (ADS)

Pollution from coastal watersheds threatens the ecology of the nearshore, including tropical reefs. Suspended sediment concentrations off the reefs of Molokai, Hawaii, chronically exceed a toxic 10 mg/L, threatening reef ecosystems. We hypothesize that historic conversion of hillslope processes from soil creep to overland flow increased both magnitude and frequency of erosion. To create a process sediment budget, we used surficial and ecological mapping, hillslope and stream gages, and novel sensors to locate, quantify and model the generation of fine sediments polluting the reef. Ecological and geomorphic mapping from LiDAR and multi-spectral imagery located overland flow areas with vegetation cover below a threshold preventing erosion. Here, feral goat grazing exposed volcanic soils whose low matrix hydraulic conductivities (1-25 mm/hour) promote Horton overland flow. We instrumented steep, barren hillslopes with soil moisture sensors, overland flow meters, Parshal flumes, ISCO sediment samplers, and a rain gage and conducted repeat Tripod LiDAR and infiltration tests. To characterize soil resistance to overland flow erosion, we used a Cohesive Strength Meter (CSM) to simulate water stress. At the 13.5 km 2 watershed mouth we used a USGS stream gage with an ISCO sediment sampler to estimate total load. Over 3 years, storms triggered overland flow during rainfall intensities above 10-15 mm/hr. Overland flow meters indicate such flows can be up to 3 cm deep, with a tendency to deepen downslope. CSM tests indicate that these depths are insufficient to erode soils where vegetation is dense, but far above threshold values of 2-3 mm for bare soils. Sediment ratings curves for both hillslope and downstream catchment gages show clock-wise hysteresis during the first intense storms in the fall, becoming linear later in the season. During fall storms, sediment concentration is often 10X higher at a given stage. Revised annual lowering rates from experimental hillslopes are 1.5 cm/a (erosion pins), 1.4 cm/a (suspended sediment) and 1.6 cm/a (repeat Tripod LiDAR). These rates are at least 100-fold greater than the long-term river lowering rate of 0.13 mm/a. A sediment budget constructed by extrapolating hillslope lowering rates to the portions of the catchments mapped as unvegetated overland flow predicts a total yearly flux of ~ 6500 t, in agreement with the measured total of ~6200 t. Decadal records illustrate that rainfall intensities sufficient to generate overland flow occur for at least 8-10 hours every year, coincident with 1-3 large storm events. We hypothesize that high lowering rates reflect a combination of long-duration overland flow events, and availability of weathered soils that can be entrained by thin flow. It appears that generation of loose, seasonally weathered silt is a 1st order control on the amount of sediment exported to the reef. If climate change increases storm frequency or duration, or decreases vegetation cover, sediment loading to reefs could increase dramatically.

Stock, J. D.; Rosener, M.; Schmidt, K. M.; Hanshaw, M. N.; Brooks, B. A.; Tribble, G.; Jacobi, J.

2010-12-01

336

Interlaminated ice-proximal glacimarine sediments in Muir Inlet, Alaska  

USGS Publications Warehouse

Muir Inlet in Glacier Bay, Alaska, is a glacial fjord receiving a tremendous volume of sediment annually. The rate of sediment accumulation is greatest proximal to Muir Glacier (about 9 m yr-1) and decreases away from the glacier. The primary sediment sources are meltwater streams discharging at subglacial and ice-marginal positions to form overflows, interflows, and underflows (continuous turbidity currents). Overflows and interflows interact with diurnal tidal currents and their volume and sediment concentration varies diurnally and annually with meltwater discharge. These effects produce cyclic deposits of a thin fine-grained sand or silt lamina that grades normally to a thicker poorly to very poorly sorted mud lamina. This lamina couplet is termed a cyclopel. Underflows are suggested to occur in this glacimarine environment because of conditions unique to subglacial fluvial systems. Underflow deposits occur only in proximal positions (177 ??m) is ubiquitous, though low (<5% by weight), and occurs as isolated particles, frozen pellets, or as lenses that in cores may have a lamina appearance. Proximally, ice-rafted debris is difficult to identify because proximal sediment is often as coarse-grained. Deposited sediment may be reworked by tidal currents, and sediment gravity flows. Depositional processes operating in Muir Inlet produce interlaminated sand/silt/clay that characterizes sediment proximal to a glacier and fines seaward to mud. Sediment is classified into one of three sediment types: 1. (1) Type I sediment is very fine grained (mean 8.65-7.17 ??), low in sand (0.1-11.2%), and very poorly to poorly sorted. It is the dominant sediment type in Muir Inlet, and is transported by plumes and deposited by suspension settling. 2. (2) Type II sediment is fine- to coarse-grained (mean 6.70-3.12 ??), low to high in sand (5.1-86.6%), and very poorly to moderately sorted. It represents reworked sediment, proximal plume deposits, or coarse-grained laminae of cyclopels. 3. (3) Type III sediment is coarse-grained (mean 3.89-2.38 ??), high in sand (58.0-100.0%), and poorly to well sorted. It is deposited by sediment gravity flows or underflows. ?? 1984.

Mackiewicz, N. E.; Powell, R. D.; Carlson, P. R.; Molnia, B. F.

1984-01-01

337

35th Annual Official Education Construction Report  

ERIC Educational Resources Information Center

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…

Agron, Joe

2009-01-01

338

Sediment transport due to extreme events: The Hudson River estuary after tropical storms Irene and Lee  

NASA Astrophysics Data System (ADS)

Storms Irene and Lee in 2011 produced intense precipitation and flooding in the U.S. Northeast, including the Hudson River watershed. Sediment input to the Hudson River was approximately 2.7 megaton, about 5 times the long-term annual average. Rather than the common assumption that sediment is predominantly trapped in the estuary, observations and model results indicate that approximately two thirds of the new sediment remained trapped in the tidal freshwater river more than 1 month after the storms and only about one fifth of the new sediment reached the saline estuary. High sediment concentrations were observed in the estuary, but the model results suggest that this was predominantly due to remobilization of bed sediment. Spatially localized deposits of new and remobilized sediment were consistent with longer term depositional records. The results indicate that tidal rivers can intercept (at least temporarily) delivery of terrigenous sediment to the marine environment during major flow events.

Ralston, David K.; Warner, John C.; Geyer, W. Rockwell; Wall, Gary R.

2013-10-01

339

Sediment Load during Flood Events for Illinois Streams. Long Term Resource Monitoring Program.  

National Technical Information Service (NTIS)

A large percentage of the annual sediment yield from a watershed is transported by a stream during a small number of floods that occur in a relatively short period of time in a year. The sediment load during flood events are examined and relations between...

M. Demissie

1995-01-01

340

Trace metal profiles in the varved sediment of an Arctic lake  

Microsoft Academic Search

Varved (annually-laminated) sediments offer a rare and physically undisturbed archive of past trace metal deposition and limnological conditions. Here, a high-resolution 1,300 year record of metal accumulation is presented from a varved lake sediment on Devon Island in the Canadian High Arctic. Down-core concentration profiles of Cd, Cu and Zn were positively correlated (P

P. M. Outridge; G. A. Stern; P. B. Hamilton; J. B. Percival; R. McNeely; W. L. Lockhart

2005-01-01

341

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

Microsoft Academic Search

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

S. G. McLin; D. W. Lyons

2002-01-01

342

Sediment discharge to the ocean from small mountainous rivers: The New Guinea example  

Microsoft Academic Search

The small mountainous rivers draining the large island of New Guinea (area = 800,000 km2) discharge approximately 1.7 × 109 t of sediment annually, about the same as the combined estimated loads of rivers draining North America. Sediment yields are particularly high for rivers that drain the high mountains of eastern New Guinea, where drainage basins are high and drainage

John D. Milliman

1995-01-01

343

Mercury and methylmercury in Hudson River sediment: impact of tidal resuspension on partitioning and methylation  

Microsoft Academic Search

The Hudson River estuary is highly polluted with heavy metals, polychlorinated biphenyls (PCBs) and PAHs. The sediment of the estuary is subjected to substantial erosion and redeposition resulting in a complex redistribution of sediment annually. Understanding the fate of heavy metals during tidal resuspension is crucial to assessing the long-term fate of pollutants in the estuary. We examined the impact

Andrew Heyes; Carrie Miller; Robert P. Mason

2004-01-01

344

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

345

Benthic response to the sedimentation of particulate organic matter at the BIOTRANS station, 47°N, 20°W  

NASA Astrophysics Data System (ADS)

The benthic response to the sedimentation of particulate organic matter (POM) was investigated during 1985-1990 at 47°N, 20°W (BIOTRANS station). The first noticeable annual sedimentation of phytodetritus, as indicated by chlorophyll a concentrations in the sediment, occurred as early as late April-early May. Maximum amounts were found in June-July. Two different sedimentation pulses to the sea bed are described that demonstrate interannual variation: the occurrence of salp faecal pellets early in the year 1988 and the massive fall out of a plankton bloom in summer 1986, which deposited approximately 15 mmol C m -2. The benthic reaction to POM pulses was quite diverse. The mega-, macro- and meiobenthos showed no change in biomass, whereas bacterial biomass doubled between March and July. This corresponds to a seasonal maximum of total adenylate biomass. The relative abundance of Foraminifera among the meiobenthos increased during the summer. Benthic activity (ATP, ratio ATP/ETSA), as well as in situ sediment community oxygen consumption rates (SCOC), showed distinct seasonal maxima in July-August of 0.75 mmol C m -2 day -1. Based on SCOC and the carbon demand for growth, a benthic carbon consumption of 0.94 mmol C m -2 day -1 was estimated. This represents about 1.1% of spring bloom primary production and 9.6% of the export flux beneath the 150 m layer, measured during the North Atlantic Bloom Experiment. Bacteria and protozoans colonizing the epibenthic phytodetrital layer were responsible for 60-80% of the seasonal increase in SCOC. The strong reaction of the smaller benthic size groups (bacteria, protozoans) to POM pulses stresses their particular importance for sediment-water interface flux rates.

Pfannkuche, O.

346

Environmental monitoring of Columbia River sediments: Grain-size distribution and contaminant association  

SciTech Connect

Based on the results of this study and literature review, the following conclusions can be made: Sediment grain size and TOC (total organic carbon) influence contaminant fate and transport (in general, sediments with higher TOC content and finer grain-size distribution can have higher contaminant burdens than sediments from a given river section that have less TOC and greater amounts of coarse-grained sediments). Physiochemical sediment characteristics are highly variable among monitoring sites along the Columbia River. Sediment grain characterization and TOC analysis should be included in interpretations of sediment-monitoring data.

Blanton, M.L.; Gardiner, W.W.; Dirkes, R.L.

1995-04-01

347

Ripening of clayey dredged sediments during temporary upland disposal a bioremediation technique  

Microsoft Academic Search

Background and Goal  In the Netherlands about 40 million m3 of sediment has to be dredged annually for both maintenance and environmental reasons. Temporary upland disposal is the most\\u000a widely adopted alternative for dredged sediments worldwide. For good management of temporary disposal sites, knowledge is\\u000a needed on the processes controlling the behavior of the sediments during disposal. Therefore, a review of

Johan Vermeulen; Tim Grotenhuis; Jan Joziasse; Wim Rulkens

2003-01-01

348

Soil erosion and sediment yield modeling using RS and GIS techniques: a case study, Iran  

Microsoft Academic Search

Water erosion is a serious and continuous environmental problem in many parts of the world. The need to quantify the amount\\u000a of erosion, sediment delivery, and sediment yield in a spatially distributed form has become essential at the watershed scale\\u000a and in the implementation of conservation efforts. In this study, an effort to predict potential annual soil loss and sediment

Saleh Arekhi; Yaghoub Niazi; Aman Mohammad Kalteh

349

The effects of the deposit feeding polychaete Pectinaria gouldii on the intertidal sediments of Barnstable Harbor  

Microsoft Academic Search

ABS ACT r Under laboratory conditions, individual Pectinmin god&i worked 6 g of sediment\\/day. This rate was related directly to sediment temperature and inversely to scdimcnt pigment concentration. At this rate, corrected for the effects of daily tidal cxposurc and annual tcmpcraturc fluctuations, the worm population in the flat studied (10 worms\\/m') would completely work all sediment in the 6-cm

DONALD C. JR GORDON

1966-01-01

350

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

PubMed Central

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.

King, Gary M.; Klug, Michael J.

1980-01-01

351

Is extreme annual precipitation really changing?  

NASA Astrophysics Data System (ADS)

The majority of scientists generally agree that the earth's climate is changing. This change, attributed mainly to man-made greenhouse gas emissions and causing the so-called global warming, does not only affect earth's temperature but also other climatic variables like precipitation. If fact numerous studies claim that have spot or verified changes in various aspects of precipitation, e.g., in the behaviour of daily extremes or in the annual total values. Here, we focus on an aspect of precipitation that has been studied less. i.e., the extreme annual total values. Particularly, we study the minimum and the maximum annual total values of several interannual periods ranging from 10 to 50 years. We aim to assess if the behaviour of the minimum or the maximum n-year annual total has changed over the last century.

Papalexiou, Simon Michael; Montanari, Alberto

2014-05-01

352

Evaluation of the AnnAGNPS model for predicting runoff and sediment yield in a small Mediterranean agricultural watershed  

NASA Astrophysics Data System (ADS)

Four experimental watersheds with contrasting land uses located in Navarre (Spain), and maintained by the local government have been monitored and studied since 1996 (La Tejería and Latxaga) and 2001 (Oskotz principal and Oskotz woodland). As a result, a detailed description and a general characterization of the hydrological and erosion behaviour of these watersheds were published recently by the same authors of this current research. This information is of great utility for evaluation of modelling tools; however, we have been done few efforts until now in this research line. The Annualized Agricultural Non Point Source Pollution Model (AnnAGNPS) is a well known and widely used model developed by the USDA-ARS and the USDA- NRCS, to assess the hydrologic and water quality responses of watersheds. More precisely, it is a distributed parameter, physically based, continuous simulation, and daily time step model. The purpose of this study is then to evaluate the AnnAGNPS model capability to simulate runoff and sediment yield with data sets from one of our agricultural watershed: Latxaga. Latxaga watershed covers an area of 207 ha and is located in the central eastern part of Navarre. Its climate is humid Sub-Mediterranean, with an average annual precipitation of 835 mm, and an average annual temperature of 12.8 °C. Geologically, the area is underlined by clay marls and sandstones. Prevailing soils are alkaline with a fine texture top-layer. Regarding land use, 80-90% of the total area is cultivated with winter grain crops. The model was calibrated using two years (2003 and 2004) of continuous 10-min/daily data, whereas another whole year (2005) was used for model validation. The calibration process was carried out by modifying Curve Number (CN) values obtained by standard procedure. CN represents a key factor in obtaining accurate prediction of runoff and sediment yield; besides it is the most important input parameter to which the runoff is sensitive. The target variable was total annual runoff and its temporal evolution during each year. Model performance assessment after calibration was carried out by qualitative (by visual comparison of graphics) and quantitative approaches (using Nash and Sutcliffe's coefficient of efficiency E for monthly values, coefficient of determination R2 and coefficient of residual mass CRM). The initial values of CN, unique for each land use, were modified; in spite of achieving a satisfactory capability in simulating runoff/sediment yield, CN was anyway splitted up, adjusting the values to the main different stages of each crop. In that way, the model performance dramatically improved. Then, the predicted and measured annual average runoff after calibration were respectively 70.17 and 70.78 mm/ha/year, with R2= 0.78 and E = 0.77. However, annual sediment yields and peak flows were over predicted respectively by 42% and 26%. Sediment yield were over estimated especially during dry season and the beginning of wet season where (sometimes) some runoff was predicted even though none was in fact recorded. This suggests that during summer/autumn period the hydrologic component of the model was not able to satisfactorily reproduce the interaction between the drier antecedent conditions/high water holding capacity of soils before any event and the small total volume -though high intensity- of the rainfalls. Regarding model validation, a satisfactory estimation of runoff with E> 0.57 was also obtained. Finally, it can be stated that AnnAGNPS arises as a promising management tool for our agricultural watersheds.

Chahor, Youssef; Casalí, Javier; Goñi, Mikel; Giménez, Rafael; Campo, Miguel A.; Del Valle de Lersundi, Jokin

2010-05-01

353

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.

2001-01-01

354

Hydraulics characteristics of tipping sediment flushing gate.  

PubMed

This paper highlights a preliminary study on the potential of a tipping flush gate to be used in an open storm drain to remove sediment. The investigation was carried out by using a plasboard model of the tipping flush gate installed in a rectangular flume. A steady flow experiment was carried out to determine the discharge coefficients and also the outflow relationship of the tipping flush gate. The velocity produced by the gate at various distances downstream of the gate during flushing operation was measured using a flowmeter and the velocity at all the points was higher than the recommended self-cleansing design available in the literature. A preliminary experiment on the efficiency of flushing was conducted using uniform sediment with d50 sizes of 0.81, 1.53 and 4.78 mm. Results generally showed that the number of flushes required to totally remove the sediment from the initial position by a distance of 1 m increased by an average of 1.50 times as the sediment deposit bed thickness doubled. An equation relating the number of flushes required to totally remove the sediment bed for 1 m with the sediment bed deposit thickness was also developed for the current study. PMID:24334888

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

2013-01-01

355

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

356

Evaluation of PCB and hexachlorobenzene biota-sediment accumulation factors based on ingested sediment in a deposit-feeding clam  

SciTech Connect

Contaminated sediment exposure experiments were conducted using a marine deposit-feeding clam (Macoma nasuta) to determine biota-sediment accumulation factors (BSAFs) based on ingested sediment and fecal organic carbon. Internal, or gut, BSAFs were determined for hexachlorobenzene and 13 polychlorinated biphenyl congeners and were compared to those found with the standard method of calculating BSAFs, which uses the organic carbon and contaminant concentration of the whole or external sediment. The results of these experiments indicated that gut BSAFs were consistently smaller and less variable across sediment types than the corresponding standard BSAFs. Although these results indicate that using ingested sediment concentrations and fecal total organic carbon to calculate gut BSAFs might improve the predictive ability of the standard BSAF model, the benefit is small when compared to the difficulty in measuring the contaminant concentration on ingested sediment and the organic carbon content of feces.

Boese, B.L.; Lee, H. II; Specht, D.T.; Randall, R. [National Health and Environmental Effects Research Lab., Newport, OR (United States); Pelletier, J. [Dyncorp, Newport, OR (United States)

1996-09-01

357

NONPOINT SEDIMENT PRODUCTION IN THE COLUSA BASIN DRAINAGE AREA, CALIFORNIA  

EPA Science Inventory

This investigation was carried out in two phases from October 1977 to March 1982. The details on field, laboratory, and computer simulation have been reported in four comprehensive annual reports. The production and transport of sediments from, through, and out of this basin are ...

358

Natural or controlled experiment? Disentangling anthropogenic and geologic contributions to the sediment load of the Le Sueur River, MN, USA  

NASA Astrophysics Data System (ADS)

Catastrophic draining of glacial Lake Agassiz at the end of the Pleistocene triggered a pulse of incision along the Minnesota River, MN, USA, that is currently propagating into tributary channels and elevating channel incision rates far above regional background levels. At the same time, installation of artificial drainage to remove excess soil water (tiling) in tributaries of the Minnesota has resulted in shorter and higher amplitude hydrographs during spring snow melt and storm events. Thus both natural and anthropogenic explanations exist for high sediment loads from tributaries to the Minnesota River, among them the Le Sueur River, which is currently impaired for turbidity under EPA Clean Water Act standards. Here we investigate the transient incision history of the Le Sueur River to aid in the development of Total Maximum Daily Loads (TMDLs) for sediment in the Le Sueur. Establishing TMDLs for the Le Sueur requires separation of anthropogenic and geologic contributions to current sediment loads. Towards this end, we ran a series of numerical simulations of the excavation of the Le Sueur River valley over the Holocene in order to constrain pre-settlement rates of sediment export. Our approach relies on coupling (with varying strength) a 2D numerical model for river meandering to various 1D numerical models for river incision. Fortuitously, both the initial profile of the Le Sueur (prior to the flood from Lake Agassiz) as well as the timing of the flood itself can be reasonably constrained from LiDAR data and previous Quaternary studies, respectively. Additionally, LiDAR-mapping of discontinuous, unpaired strath terraces combined with OSL and/or 14C dates on 18 strath terrace deposits pin pieces of the long profile of the Le Sueur River in time and space. By minimizing the model misfit for strath terrace ages, the current river elevation long profile, and the width between bluffs along the Le Sueur River valley, we identify a preferred valley excavation history. We converted the modeled pre-settlement erosion rate into an annual mass of silt and clay to compare with average annual total suspended solid load measurements at the mouth of the river. Results show that modern fine sediment loads from all sediment sources combined are appro