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1

Total PCBs in Liverpool Bay sediments  

Microsoft Academic Search

The concentrations of 55 congeners of PCBs were determined in < 500 ?m particles of 66 superficial sediment samples from Liverpool Bay. Total PCBs were significantly (p < 0.001) correlated with the amount of fine particles (r2 = 0.81) and with the organic carbon content (r2 = 0.80). The mean, maximum and minimum total PCB values were 3938, 37,880 and

V. F. Camacho-Ibar; J. McEvoy

1996-01-01

2

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...

3

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

4

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...

5

The measurement of total sediment load in alluvial streams  

USGS Publications Warehouse

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

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

1953-01-01

6

Process Based Modeling of Total Longshore Sediment Transport  

Microsoft Academic Search

HAAS, K.A. and HANES, D.M., 2004. Process based modeling of total longshore sediment transport. Journal of Coastal Research, 20(3), 853-861. West Palm Beach (Florida), ISSN 0749-0208. Waves, currents, and longshore sand transport are calculated locally as a function of position in the nearshore region using process based numerical models. The resultant longshore sand transport is then integrated across the nearshore

Kevin A. Haas; Daniel M. Hanes

2004-01-01

7

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...

8

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

Microsoft Academic Search

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

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

1998-01-01

9

Total Sediment Load from SEMEP Using Depth-Integrated Concentration Measurements  

E-print Network

collected from 14 rivers, the accuracy of sediment discharge calculations depend on the ratio of the shear expansion; Rouse number. Introduction Sediment transport in rivers is complex, and accurate estimates. This article focuses specifically on methods to estimate the total sediment discharge in rivers from field

Julien, Pierre Y.

10

Total Maximum Daily Loads, Sediment Budgets, and Tracking Restoration  

E-print Network

for northern coastal California watersheds is the impairment of salmonid habitat. Most of the North Coast a water quality restoration plan for the watershed. Sediment budgets are useful tools to evaluate sediment Coast Region of the California Regional Water Quality Control Board, several salmonid species are listed

Standiford, Richard B.

11

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

NASA Astrophysics Data System (ADS)

Soil respiration (SR) constitutes the largest flux of CO2 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 (SRMAT), 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 (Q10). 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 SRMAT corrected for a factor related to P/PET. Our finding indicates that it can be sufficient to measure SRMAT for obtaining a well constrained estimate of its annual total. This should substantially increase our capacity for assessing the spatial distribution of soil CO2 emissions across ecosystems, landscapes and regions, and thereby contribute to improving the spatial resolution of a major component of the global carbon cycle.

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.; Curiel Yuste, J.; Tang, J.; Vargas, R.; Janssens, I. A.

2010-07-01

12

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

NASA Astrophysics Data System (ADS)

Soil respiration (SR) constitutes the largest flux of CO2 from terrestrial ecosystems to the atmosphere. 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 72 site-years for 58 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 convergence is to be theoretically expected for non water-limited ecosystems within most of the globally occurring range of annual temperature variability and sensitivity (Q10). 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 is sufficient to measure SR MAT for obtaining a highly constrained estimate of its annual total. This should substantially increase our capacity for assessing the spatial distribution and interannual variation of soil CO2 emissions across ecosystems, landscapes and regions, and thereby contribute to improving the spatio-temporal resolution of a major component of the global carbon cycle.

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.; Curiel Yuste, J.; Tang, J.; Vargas, R.; Janssens, I. A.

2009-12-01

13

Simplified methods for computing total sediment discharge with the modified Einstein procedure  

USGS Publications Warehouse

A procedure was presented in 1950 by H. A. Einstein for computing the total discharge of sediment particles of sizes that are in appreciable quantities in the stream bed. This procedure was modified by the U.S. Geological Survey and adapted to computing the total sediment discharge of a stream on the basis of samples of bed sediment, depth-integrated samples of suspended sediment, streamflow measurements, and water temperature. This paper gives simplified methods for computing total sediment discharge by the modified Einstein procedure. Each of four homographs appreciably simplifies a major step in the computations. Within the stated limitations, use of the homographs introduces much less error than is present in either the basic data or the theories on which the computations of total sediment discharge are based. The results are nearly as accurate mathematically as those that could be obtained from the longer and more complex arithmetic and algebraic computations of the Einstein procedure.

Colby, Bruce R.; Hubbell, David Wellington

1961-01-01

14

Sediment and total phosphorous contributors in Rock River watershed.  

PubMed

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 production could exacerbate these already stressed water bodies. In this study we expand on the previous studies relating landscape variables such as land cover, soil type and slope with changes in pollutant concentrations and loading in the Great Lakes region. The Rock River watershed in Wisconsin, USA was chosen due to its diverse land use, numerous lakes and reservoirs susceptible to TSS and TP pollution, and the availability of long-term streamflow, TSS and TP data. Eight independent subwatersheds in the Rock River watershed were identified using United States Geological Survey (USGS) monitoring sites that monitor flow, TSS and TP. For each subwatershed, we calculated land use, soil type, and terrain slope metrics or variables. TSS and TP from the different subwatersheds were compared using Analysis of Variance (ANOVA), and associations and relationships between landscape metrics and water quality (TSS and TP) were evaluated using the partial least square (PLS) regression. Results show that urban land use and agricultural land growing corn rotated with non-leguminous crops are associated with TSS and TP in streams. This indicates that increasing the amount of corn rotated with non-leguminous crops within a subwatershed could increase degradation of water quality. Results showed that increase in corn-soybean rotation acreage within the watershed is associated with reduction in stream's TSS and TP. Results also show that forest and water bodies were associated with reduction in TSS and TP. Based on our results we recommend adoption of the Low Impact Development (LID) approach in urban dominated subwatersheds. This approach attempts to replicate the pre-development hydrological regime by reducing the ratio of impervious area to natural cover wherever possible, as well as recycling or treating stormwater runoff using filter strips, ponds and wetlands. In agriculturally dominated subwatersheds, we recommend increasing corn-soybean rotation, keeping corn on areas with gentle slope and soils with lower erodibility. PMID:24384283

Mbonimpa, Eric G; Yuan, Yongping; Nash, Maliha S; Mehaffey, Megan H

2014-01-15

15

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

16

29 CFR 779.253 - What is included in computing the total annual inflow volume.  

Code of Federal Regulations, 2011 CFR

...included in computing the total annual inflow volume. 779.253 Section 779.253 Labor...included in computing the total annual inflow volume. The goods which the establishment...State lines must “amount in total annual volume to $250,000 or more.” It will...

2011-07-01

17

29 CFR 779.253 - What is included in computing the total annual inflow volume.  

Code of Federal Regulations, 2012 CFR

...included in computing the total annual inflow volume. 779.253 Section 779.253 Labor...included in computing the total annual inflow volume. The goods which the establishment...State lines must “amount in total annual volume to $250,000 or more.” It will...

2012-07-01

18

29 CFR 779.253 - What is included in computing the total annual inflow volume.  

Code of Federal Regulations, 2014 CFR

...included in computing the total annual inflow volume. 779.253 Section 779.253 Labor...included in computing the total annual inflow volume. The goods which the establishment...State lines must “amount in total annual volume to $250,000 or more.” It will...

2014-07-01

19

29 CFR 779.253 - What is included in computing the total annual inflow volume.  

Code of Federal Regulations, 2013 CFR

...included in computing the total annual inflow volume. 779.253 Section 779.253 Labor...included in computing the total annual inflow volume. The goods which the establishment...State lines must “amount in total annual volume to $250,000 or more.” It will...

2013-07-01

20

29 CFR 779.253 - What is included in computing the total annual inflow volume.  

Code of Federal Regulations, 2010 CFR

...included in computing the total annual inflow volume. 779.253 Section 779.253 Labor...included in computing the total annual inflow volume. The goods which the establishment...State lines must “amount in total annual volume to $250,000 or more.” It will...

2010-07-01

21

Characteristics of sediment data and annual suspended-sediment loads and yields for selected lower Missouri River mainstem and tributary stations, 1976-2008  

USGS Publications Warehouse

Suspended-sediment data from 18 selected surface-water monitoring stations in the lower Missouri River Basin downstream from Gavins Point Dam were used in the computation of annual suspended-sediment and suspended-sand loads for 1976 through 2008. Three methods of suspended-sediment load determination were utilized and these included the subdivision method, regression of instantaneous turbidity with suspended-sediment concentrations at selected stations, and regression techniques using the Load Estimator (LOADEST) software. Characteristics of the suspended-sediment and streamflow data collected at the 18 monitoring stations and the tabulated annual suspended-sediment and suspended-sand loads and yields are presented.

Heimann, David C.; Rasmussen, Patrick P.; Cline, Teri L.; Pigue, Lori M.; Wagner, Holly R.

2010-01-01

22

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

Microsoft Academic Search

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

Achim Brauer; Christoph Endres; Jörg F. W Negendank

1999-01-01

23

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

USGS Publications Warehouse

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

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

2013-01-01

24

16 CFR 801.11 - Annual net sales and total assets.  

Code of Federal Regulations, 2010 CFR

...d) or 801.50(c) the annual net sales and total assets...specified in paragraph (c) of this section...1) That the annual net sales and total assets...nonduplicative annual net sales and nonduplicative...of B2 and C3. (c) Subject to the...

2010-01-01

25

16 CFR 801.11 - Annual net sales and total assets.  

Code of Federal Regulations, 2011 CFR

...d) or 801.50(c) the annual net sales and total assets...specified in paragraph (c) of this section...1) That the annual net sales and total assets...nonduplicative annual net sales and nonduplicative...of B2 and C3. (c) Subject to the...

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

1998-01-01

27

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

PubMed

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) micrograms/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 microgram 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. PMID:9469852

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

1998-02-01

28

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

Microsoft Academic Search

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 (3 km) distances from the drilling

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

2007-01-01

29

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

Microsoft Academic Search

Concentrations of total Hg in sediments near six drilling sites in the Gulf of Mexico were elevated well above average background\\u000a values of 40–80 ng\\/g. The excess Hg was associated with barite from discharged drilling mud. In contrast with total Hg, concentrations\\u000a of methylmercury (MeHg) in these sediments did not vary significantly at nearfield (3 km) distances\\u000a from the drilling sites. Observed

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

2007-01-01

30

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...

31

SEDIMENTS, SEC 2 * PHYSICAL AND BIOGEOCHEMICAL PROCESSES * RESEARCH ARTICLE Total and size-fractionated mass of road-deposited sediment  

E-print Network

-fractionated mass of road-deposited sediment in the city of Prince George, British Columbia, Canada: implications, in British Columbia, Canada. The objectives of this study were: (1) to determine the total mass of RDS within, although there were some hotspots which may reflect land use activities such as light-industry and pulp

Owens, Philip

32

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

33

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

USGS Publications Warehouse

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

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

2001-01-01

34

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

35

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...

36

Distribution of total mercury and methylmercury in lake sediments in Arctic Ny-Ålesund  

Microsoft Academic Search

The toxicities and bioavailabilities of total mercury (THg) and methylmercury (MeHg) in aquatic systems have made them the subjects of recent research. In this study, we collected a lake sediment core from Ny-Ålesund in Svalbard and analyzed the distributions of THg and MeHg in the sediments. The increased trend of THg was caused by anthropogenic contamination since the 14th century

Shan Jiang; Xiaodong Liu; Qianqian Chen

2011-01-01

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

New approaches for automated data processing of annually laminated sediments  

NASA Astrophysics Data System (ADS)

Laminated sediments, like evaporites and biogenic lake sediments, provide high-resolution paleo-climate records. Yet detection and counting of laminae causes still problems because sedimentary structures are often disturbed. In the past laminated rocks often were analysed manually - a tedious and subjective work. The present study describes four automated approaches for lamina detection based on 1d grey-scale vectors. Best results are obtained with a newly developed algorithm, called Adaptive Template Method (ATM) in combination with the Hilbert transform. ATM improves the signal to noise ratio of the grey-value signal. Its basic idea is to extract first a characteristic waveform, the template, which describes the typical grey-value variation transverse to the laminae. This is a kind of "template learning" process, which in practice is done by an appropriate averaging method. This template is in a second step used for processing the whole sample. One calculates the overlap of the template with the actual signal, the grey-value variation along the core, as function of position in core direction. This method generates a new signal with maxima at positions, where the template optimally matches the original signal. The new time-series is called AT-transform. It is smoother than the initial data sequence. High frequency noise and local trend effects are suppressed. Afterwards, the AT-transform can be analysed with the Hilbert transformation for extracting phase information. The data processing methods are tested both on artificial data sequences and on a seasonally laminated sedimentary record of the Oligocene Baruth Maar (Germany). Although ATM is no panacea for highly disturbed signals, our comparison with other approaches shows that it provides the best results. The combination of ATM and the Hilbert transform allows to detect clearly long-term oscillations in the sedimentation patterns and thus cycles in climatic variations.

Rupf, I.; Radons, G.

2004-11-01

39

Improving 14C-based chronologies of non-annually resolved sediment series by assessing the biogenic fraction flux instead of sedimentation rate  

NASA Astrophysics Data System (ADS)

The last decade was a period of unprecedented development of annually-resolved natural archives of past environmental conditions, such as speleothems, varve lake sediment, ice core or corals. Nevertheless, such geosystems are not present everywhere in the world and the interest for non-annually resolved natural archives remains important in the aim of reconstructing past climatic and environmental condition, both in marine and continental areas. In particular it has been shown that sediment - from lakes, fjords, or continental margins - which are made of a mixture of biogenic and detrital fractions, may be used to reconstruct past detrital discharge and thus hydrological patterns. Thanks to the recent developments in core logging geochemical techniques - XRF core scanning - such sediment sequences are susceptible to deliver highly resolute climatic of environmental signals, provided they may be accurately dated. In this paper we present a new method, applied to the establishment of age-depth relationships of two of such sequences taken in Lake Bourget, NW French Alps. Our method is classically based on 14C ages, but those ages were stratigraphically placed as a function of "biogenic carbonate accumulation" instead of depth below lake floor, which is classically done. Lake Bourget is a fjord-type lake in which river Rhône, one of the main European Alps rivers, sporadically enters during its major floods. Such events bring a silicate-rich detrital fraction which dilutes the biogenic carbonates constituting the main sediment fraction in normal conditions. Two long cores covering most of the Holocene period were retrieved in Lake Bourget and sampled for 14C dating following a sampling-step of less than 1000 years. Using high resolution XRF core scanning results calibrated by 150 major elements discrete measurements, we assessed carbonate and detrital fraction contents following a 5mm- to 1cm-step. We also assessed the evolution of dry density as a function of depth by measuring the dry weight of volume-known samples. Combining those information we were able to compute the weight of carbonate accumulation above each depth per surface unit (carbonate accumulation depth). 14C ages were subsequently replaced as a function of this "carbonate accumulation depth". It then appeared that all the ages were aligned along a linear curve. On the contrary, the age-depth relationship presents many disruptions due to changes in detrital flux. We hence demonstrate that biogenic carbonate flux varies of one order of magnitude less than total sediment flux. We finally applied a classic age-depth modelling to take account of low amplitude change in carbonate accumulation and thus establish an independent chronology of each sediment sequence. The chronology hence obtained takes account of instantaneous changes in detrital supply and is thus more accurate than classic age-depth relationship. The agreement of detrital signals as a function of time in our two independently dated sequences argues for the accuracy of our method. Such a method should improve age-modelling of any non-annually laminated sediment sequence which is made of a mixture of biogenic (carbonate, diatoms, organic matter etc.) and detrital fractions, whatever it is of freshwater or marine origin.

Arnaud, F.

2009-04-01

40

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

PubMed

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

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

2014-01-21

41

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

PubMed Central

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

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

2014-01-01

42

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

PubMed

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

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

2015-01-01

43

Distribution and possible sources of total mercury in sediments from the Newark Bay Estuary, New Jersey  

SciTech Connect

A screening survey conducted by investigators of total mercury (Hg) concentrations in freshwater fishes from New Jersey rivers and lakes revealed elevated concentrations (>0.5 mg/kg wet weight) in the edible tissues of several species. The highest Hg concentrations were measured in largemouth bass (Micropterus salmoides) and chain pickerel(Esox niger) from waterbodies in the northeastern portion of the state that are heavily affected by agriculture, industry, and urbanization, and in waterbodies throughout the state with low pH(>5.0). Similar results have been reported in saltwater fishes collected from the Raritan River, Passaic River, and Newark Bay. Mercury is among the most toxic of metals and one of the most persistent in sediments and organisms. This paper reports the results of total Hg analysis conducted on samples of surface and buried sediments from 72 cores collected from Newark Bay and its major tributaries between 1991 and 1993. 18 refs., 2 figs., 1 tab

Iannuzzi, T.J. [Hart Environmental Engineering Corp., Portland, ME (United States); Wenning, R.J. [Hart Environmental Engineering Corp., North Ryde (Australia)

1995-12-01

44

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

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

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

47

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

48

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

49

Total mercury in sediments and in Brazilian Ariidae catfish from two estuaries under different anthropogenic influence.  

PubMed

Santos-São Vicente estuary, located in São Paulo State, Brazil, has a history of contamination by inorganic chemicals such as mercury (Hg). In the 1980s the Cubatão was considered one of the most polluted sites in the world as a consequence of the intense industrial activities located in the city close to the estuary. To provide data and evaluate the local biota, total mercury (THg) contents were determined in sediments and in fish, Cathorops spixii, from different areas of the Santos-São Vicente estuary. For comparison, samples were also collected in a non-polluted system with similar hydrochemistry characteristics, the Cananeia estuary. The water characteristics and THg levels in sediment and fish samples confirmed a high human influence in the Santos-São Vicente estuary. The lowest THg values, observed in Cananeia, were evidence of low anthropogenic influence. High values observed in Santos-São Vicente show the necessity for a monitoring program. PMID:22030105

Azevedo, Juliana S; Braga, Elisabete S; Favaro, Deborah T; Perretti, Adriana R; Rezende, Carlos Eduardo; Souza, Cristina Maria M

2011-12-01

50

Influence of different temporal sampling strategies on estimating total phosphorus and suspended sediment concentration and transport in small streams  

USGS Publications Warehouse

Various temporal sampling strategies are used to monitor water quality in small streams. To determine how various strategies influence the estimated water quality, frequently collected water quality data from eight small streams (14 to 110 km2) in Wisconsin were systematically subsampled to simulate typically used strategies. These subsets of data were then used to estimate mean, median, and maximum concentrations, and with continuous daily flows used to estimate annual loads (using the regression method) and volumetrically weighted mean concentrations. For each strategy, accuracy and precision in each summary statistic were evaluated by comparison with concentrations and loads of total phosphorus and suspended sediment estimated from all available data. The most effective sampling strategy depends on the statistic of interest and study duration. For mean and median concentrations, the most frequent fixed period sampling economically feasible is best. For maximum concentrations, any strategy with samples at or prior to peak flow is best. The best sampling strategy to estimate loads depends on the study duration. For one-year studies, fixed period monthly sampling supplemented with storm chasing was best, even though loads were overestimated by 25 to 50 percent. For two to three-year load studies and estimating volumetrically weighted mean concentrations, fixed period semimonthly sampling was best.

Robertson, D.M.

2003-01-01

51

Stability of the total and functional microbial communities in river sediment mesocosms exposed to anthropogenic disturbances.  

PubMed

River systems are exposed to anthropogenic disturbances, including chemical pollution and eutrophication. This may affect the phylogenetic diversity as well as the abundance of various functional groups within sediment-associated microbial communities. To address such potential effects, mesocosms filled with Ebro delta sediment covered with river water were exposed to chlorinated organic compounds or to a high nutrient concentration as used for fertilization. Changes in the abundance of selected functional microbial groups, i.e. total aerobes, nitrate, sulfate and iron reducers, organohalide-respiring microorganisms as well as methanogens, were examined using culture-dependent most probable number and culture-independent PCR methods targeting phylogenetic as well as functional gene markers. It was concluded that the abundance of functional groups was neither affected by pollution with 1,2-dichloroethane and tetrachloroethene nor by elevated nutrient loads, although changes in the bacterial community composition were observed using 16S rRNA gene-targeted fingerprint techniques. This study reinforced the notion that complementary culture-dependent and molecular methods, focusing on different fractions of the microbial community (cultivable, active or total), should be used in combination for a comprehensive description of phylogenetic diversity and functional potential. PMID:20618856

Van der Zaan, Bas; Smidt, Hauke; De Vos, Willem M; Rijnaarts, Huub; Gerritse, Jan

2010-10-01

52

Regionalizing mean annual flow and daily flow variability for basin-scale sediment and nutrient modelling  

NASA Astrophysics Data System (ADS)

River discharges vary strongly through time and space, and quantifying this variability is fundamental to understanding and modelling river processes. The river basin is increasingly being used as the unit for natural resource planning and management; to facilitate this, basin-scale models of material supply and transport are being developed. For many basin-scale planning activities, detailed rainfall-runoff modelling is neither necessary nor tractable, and models that capture spatial patterns of material supply and transport averaged over decades are sufficient. Nevertheless, the data to describe the spatial variability of river discharge across large basins for use in such models are often limited, and hence models to predict river discharge at the basin scale are required. We describe models for predicting mean annual flow and a non-dimensional measure of daily flow variability for every river reach within a drainage network. The models use sparse river gauging data, modelled grid surfaces of mean annual rainfall and mean annual potential evapotranspiration, and a network accumulation algorithm. We demonstrate the parameterization and application of the models using data for the Murrumbidgee basin, in southeast Australia, and describe the use of these predictions in modelling sediment transport through the river network. The regionalizations described contain less uncertainty, and are more sensitive to observed spatial variations in runoff, than regionalizations based on catchment area and rainfall alone.

Wilkinson, Scott N.; Young, William J.; Derose, Ron C.

2006-08-01

53

Mercury speciation and total organic carbon in marine sediments along the Mediterranean coast of Israel.  

PubMed

Along the Israeli Mediterranean Coast, three areas are considered "hot spots" of mercury (Hg) pollution: (1) Northern Haifa Bay (NHB), (2) the lower Qishon River at the southern part of Haifa Bay, and (3) a marine outfall of activated sewage sludge at the southern coast off Palmachim (sewage-sludge disposal site [SDS]). Even though the total Hg (HgT) concentrations in the sediments at the three areas are of the same order of magnitude (250-500 ?g kg(-1)), Hg was shown to bioaccumulate in fish and benthic fauna from Haifa Bay but not in benthic fauna or in commercial fish caught along the southern Mediterranean Coast of Israel near the SDS outfall. The primary goal of this study was to measure the concentrations of Hg species (HgT, methyl-Hg [MeHg], and Hg in different biogeochemical fractions)-in conjunction with organic carbon-in sediments of NHB and the lower Qishon River to assess its impact on Hg transitions among the species as characterized by different bioavailability and bioaccessibility. HgT concentrations in NHB and the Qishon River ranged from 249 to 347 and 165 to 667 ?g kg(-1), respectively. MeHg was significantly higher in the Qishon River (6.3-34.0 ?g kg(-1)) than in NHB (0.22-0.70 ?g kg(-1)) as were total organic carbon (TOC) concentrations (average 2.5 vs. 0.13 %). The relative Hg distribution in the biogeochemical fractions in NHB was 2.3 % in the most bioaccessible fractions (F1 + F2), 55 % in the organo-chelated species fraction (F3), 42 % in the strong-complexed species fraction (F4), and 0.7 % in the mercuric-sulfide fraction (F5). In the Qishon River, the bioavailable F1 + F2 and F3 fractions were lower than in NHB (<0.01 and 23 %, respectively) and the more refractory F4 and F5 fractions higher (73 and 3.3 %, respectively). The fractionation of Hg in Qishon River sediments was similar to the distribution found in polluted stations at the SDS. TOC and MeHg were positively and negatively correlated, respectively, in Qishon River and NHB sediments. Methylation depended on TOC availability when its concentration was in the range of 2-4 wt%. It is possible that TOC in the sediment controlled Hg speciation: Hg in F3 decreased and in F4 increased with increasing TOC concentrations. In contrast, MeHg/HgT was significantly positively correlated with TOC and Hg in the stable F4 fraction and negatively correlated with Hg in the F3 fraction. It was therefore assumed that higher TOC concentrations enhanced microbial activity and decomposition of organic matter. Hg was released from the F3 fraction and was either transferred to the F4 fraction or made available for methylation processes. PMID:22961217

Shoham-Frider, Efrat; Azran, Shlomi; Kress, Nurit

2012-11-01

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

Vertical distribution of total mercury and methylmercury in sediment of the Fugong mangrove area at Jiulong River Estuary, Fujian, China.  

PubMed

The concentrations and vertical distributions of total mercury (Hg) and methylmercury (methyl Hg) in the sediment of the Fugong mangrove area, located at the Jiulong River Estuary, Fujian, China, were investigated. The concentrations of total mercury were between 0.12-0.17 and 0.11-40.14 microg/g, while concentrations of methylmercury were between 0.15-1.8 and 0.081-0.58 ng/g (as mercury), in the dry and rainy seasons, respectively. The total mercury concentration was not correlated with the sampling depth. As the depth increased, methylmercury concentrations first increased to their maximum level at a depth of 10-25 cm, and then decreased; this was similar to the vertical distribution characteristics of methylmercury/total mercury ratios. The mangrove ecosystem was considered as a source of methylmercury for adjacent areas, due to the higher average methylmercury concentration in the mangrove sediment than other sediments nearby. Statistically significant logarithmic correlations, conic correlations, and negative correlations were observed for methylmercury and sulfide concentration, sediment organic matter, and sediment pH, respectively. PMID:23833815

Liang, Ying; Yuan, Dongxing; Chen, Yaojin; Liu, Xiyao

2013-06-01

56

Historical landscape change in Cappadocia (central Turkey): a palaeoecological investigation of annually laminated sediments from Nar lake  

Microsoft Academic Search

Coupled multiproxy indicators (pollen, stable isotopes and charcoal) reconstructed from annually laminated lake sediments from Nar Gölü in Cappadocia (central Turkey) complemented by documentary and archaeological evidence provide a detailed record of environmental changes and their causes from late Antiquity (AD 300) to the present day. Stable isotope data indicate marked shifts in the variability in summer drought intensity and

Ann England; Warren J. Eastwood; C. Neil Roberts; Rebecca Turner; John F. Haldon

2008-01-01

57

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

NASA Technical Reports Server (NTRS)

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

Krzyscin, Janusz W.

1994-01-01

58

Variation and distribution of total mercury in water, sediment and soil from northern Lake Victoria, East Africa  

Microsoft Academic Search

Lake Victoria, the world's largest tropical freshwater lake, is an important resource, ecologi- cally and economically. THg distribution in the northern parts of the lake are not well known, so to answer this gap, patterns in total mercury (THg) in water, soil and two dated sediment cores from north- ern Lake Victoria were determined. Water THg concentrations ranged from 0.7

L. M. CAMPBELL; R. E. HECKY; R. MUGGIDE; D. G. DIXON

2003-01-01

59

Variation and distribution of total mercury in water, sediment and soil from northern Lake Victoria, East Africa  

Microsoft Academic Search

Lake Victoria, the world's largest tropical freshwater lake, is an important resource, ecologically and economically. THg distribution in the northern parts of the lake are not well known, so to answer this gap, patterns in total mercury (THg) in water, soil and two dated sediment cores from northern Lake Victoria were determined. Water THg concentrations ranged from 0.7 to 5.8

L. M. Campbell; R. E. Hecky; R. Muggide; D. G. Dixon; P. S. Ramlal

2003-01-01

60

Adjustment of Total Suspended Solids Data for Use in Sediment Studies G. Douglas Glysson (1), John R. Gray (2), and Lisa M. Conge (2)  

E-print Network

processes, and recreational uses of rivers, lakes, and estuaries. A significant amount of suspended-sediment1 Adjustment of Total Suspended Solids Data for Use in Sediment Studies G. Douglas Glysson (1@usgs.gov Abstract: The U.S. Environmental Protection Agency identifies fluvial sediment as the single most

Torgersen, Christian

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

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

Code of Federal Regulations, 2013 CFR

... Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM (CONTINUED) TRUTH IN LENDING (REGULATION Z) Pt. 226, App. K Appendix K to Part 226—Total Annual Loan Cost Rate Computations for...

2013-01-01

63

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

Code of Federal Regulations, 2014 CFR

... Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM (CONTINUED) TRUTH IN LENDING (REGULATION Z) Pt. 226, App. K Appendix K to Part 226—Total Annual Loan Cost Rate Computations for...

2014-01-01

64

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

65

Microscopic observation of laminated sediment in thin section using diatom assemblages to reconstruct annual paleoenvironmental changes  

NASA Astrophysics Data System (ADS)

Eastern Hokkaido is a severe earthquake and tsunami district. Lake Harutori, located in eastern Hokkaido, records 22 traces of huge tsunamis in lake sediment since 9500 years ago. The latest event was occurred in 17th century (e.g. Nanayama et al., 2003). However, the strict age is still unknown, because the autochthon Ainu culture did not have literature. In lake sediment, there is laminated structure between tsunami deposits, and also on the 17th huge tsunami deposit. If this laminated structure was recognized as annual varve, it will be able to decide the strict age and reconstruct the paleoenvironment in high resolution. Large thin section 165 mm length was made included 17th tsunami deposits, laminated silt layer and age known tephra and observed lithofacies and diatoms with 1,000 magnification light microscope. The thin section comprised from 80 mm thick tsunami deposit in bottom, 60 mm thick laminated silt layer, 15 mm tephra as known as Ta-b fallen in 1667A.D. and 10 mm laminated silt layer at the top. As the result of optical observation to laminated silt layer, 31 laminated structures were recognized. Inferred from diatom assemblages, 37 cyclic productions were recognized. Diatom components were apparently changed from bottom to top and were seemed to influence by the changes of lake water conditions after tsunami inundation. These results indicate that the start of accumulation of laminated silt layer and/or the end of confusion of lake water by tsunami current was around 1630 A.D.; 37 years before 1667 A.D.. This earthquake was separated from the 1611 Keicho Sanriku earthquake was well known in this era and the hypocenters of these earthquakes need to reexam.

Ishikawa, S.; Kaoru, K.

2013-12-01

66

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

67

A Comparison of Load Estimates Using Total Suspended Solids and Suspended-Sediment Concentration Data  

E-print Network

-sediment mixture within the sample to derive concentration values (ASTM, 2000). The TSS method, which originated of the strong tendency for SSC to exceed TSS at larger values of SSC (Gray and others, 2000), suspended solid-phase

Torgersen, Christian

68

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

PubMed

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

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

2007-09-01

69

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

NASA Astrophysics Data System (ADS)

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

Wobbe, Florian; Lindeque, Ansa; Gohl, Karsten

2014-12-01

70

Patterns of floodplain sediment deposition along the regulated lower Roanoke River, North Carolina: Annual, decadal, centennial scales  

NASA Astrophysics Data System (ADS)

The lower Roanoke River on the Coastal Plain of North Carolina is not embayed and maintains a floodplain that is among the largest on the mid-Atlantic Coast. This floodplain has been impacted by substantial aggradation in response to upstream colonial and post-colonial agriculture between the mid-eighteenth and mid-nineteenth centuries. Additionally, since the mid-twentieth century stream flow has been regulated by a series of high dams. We used artificial markers (clay pads), tree-ring (dendrogeomorphic) techniques, and pollen analyses to document sedimentation rates/amounts over short-, intermediate-, and long-term temporal scales, respectively. These analyses occurred along 58 transects at 378 stations throughout the lower river floodplain from near the Fall Line to the Albemarle Sound. Present sediment deposition rates ranged from 0.5 to 3.4 mm/y and 0.3 to 5.9 mm/y from clay pad and dendrogeomorphic analyses, respectively. Deposition rates systematically increased from upstream (high banks and floodplain) to downstream (low banks) reaches, except the lowest reaches. Conversely, legacy sediment deposition (A.D. 1725 to 1850) ranged from 5 to about 40 mm/y, downstream to upstream, respectively, and is apparently responsible for high banks upstream and large/wide levees along some of the middle stream reaches. Dam operations have selectively reduced levee deposition while facilitating continued backswamp deposition. A GIS-based model predicts 453,000 Mg of sediment is trapped annually on the floodplain and that little watershed-derived sediment reaches the Albemarle Sound. Nearly all sediment in transport and deposited is derived from the channel bed and banks. Legacy deposits (sources) and regulated discharges affect most aspects of present fluvial sedimentation dynamics. The lower river reflects complex relaxation conditions following both major human alterations, yet continues to provide the ecosystem service of sediment trapping.

Hupp, C. R.; Schenk, E. R.; Kroes, D. E.; Willard, D. A.; Townsend, P. A.; Peet, R. K.

2015-01-01

71

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

USGS Publications Warehouse

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

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

2011-01-01

72

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

73

Total Mercury, Methylmercury, Methylmercury Production Potential, and Ancillary Streambed-Sediment and Pore-  

E-print Network

Total Mercury, Methylmercury, Methylmercury Production Potential, and Ancillary Streambed Oak Creek, Wisconsin (center). (All photographs by the authors.) #12;Total Mercury, Methylmercury.E., 2008, Total mercury, methylmercury, methylmercury production potential, and ancillary streambed

74

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

75

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...

76

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

Microsoft Academic Search

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

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

2007-01-01

77

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

78

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

79

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

Microsoft Academic Search

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

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

2005-01-01

80

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

81

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

SciTech Connect

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

Purser, Michael D.; Rhodes, Jonathan J.

1999-01-01

82

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

83

Statistical modelling and power analysis for detecting trends in total suspended sediment loads  

NASA Astrophysics Data System (ADS)

The export of sediments from coastal catchments can have detrimental impacts on estuaries and near shore reef ecosystems such as the Great Barrier Reef. Catchment management approaches aimed at reducing sediment loads require monitoring to evaluate their effectiveness in reducing loads over time. However, load estimation is not a trivial task due to the complex behaviour of constituents in natural streams, the variability of water flows and often a limited amount of data. Regression is commonly used for load estimation and provides a fundamental tool for trend estimation by standardising the other time specific covariates such as flow. This study investigates whether load estimates and resultant power to detect trends can be enhanced by (i) modelling the error structure so that temporal correlation can be better quantified, (ii) making use of predictive variables, and (iii) by identifying an efficient and feasible sampling strategy that may be used to reduce sampling error. To achieve this, we propose a new regression model that includes an innovative compounding errors model structure and uses two additional predictive variables (average discounted flow and turbidity). By combining this modelling approach with a new, regularly optimised, sampling strategy, which adds uniformity to the event sampling strategy, the predictive power was increased to 90%. Using the enhanced regression model proposed here, it was possible to detect a trend of 20% over 20 years. This result is in stark contrast to previous conclusions presented in the literature.

Wang, You-Gan; Wang, Shen S. J.; Dunlop, Jason

2015-01-01

84

Temporal trends in spheroidal carbonaceous particle deposition derived from annual sediment traps and lake sediment cores and their relationship with non-marine sulphate.  

PubMed

Spheroidal carbonaceous particles (SCPs) provide an unambiguous indication of atmospherically deposited contamination from industrial sources. SCP data from a 12 year annual sediment trapping and coring programme at 14 lakes based on the UK Acid Waters Monitoring Network, were used to consider temporal trends in deposition and to compare these with measured non-marine sulphate fluxes. Results show good temporal coherence across a broad area of northern UK and that SCP deposition levels and are now at their lowest since the 1940s, in agreement with modelled sulphate data. SCP fluxes show reasonable linearity with measured non-marine sulphate depositional fluxes from the nearest UK Acid Deposition Monitoring Network sites, especially over the post-flue-gas desulphurisation period, but comparisons prior to 1972 are not possible due to lack of data. We speculate on whether palaeolimnological SCP data might be used to reconstruct the history of non-marine sulphate fluxes from industrial sources. PMID:15944046

Rose, N L; Monteith, D T

2005-09-01

85

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

86

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

87

TOTAL MAXIMUM DAILY LOAD WATER QUALITY MONITORING FOR SEDIMENT IN WILDHORSE CREEK, NORTHEAST OREGON  

Technology Transfer Automated Retrieval System (TEKTRAN)

In 1998 over 40 stream segments in the Umatilla River Basin were listed as “water quality limited” on Oregon Department of Environmental Quality’s (ODEQ) 303(d) list under the Clean Water Act. A unique multi-agency cooperative effort led to the Umatilla River Basin Total Maximum Daily Load (TMDL) a...

88

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 ...

89

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

90

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

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

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

E-print Network

Modeling the influence of river rehabilitation scenarios on bed material sediment flux in a large and calibrated sediment transport formulae were used to assess the decadal impact of major river rehabilitation. Total annual average bed material sediment flux estimates were made at six gauged river cross sections

Singer, Michael

93

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

94

A chronology of the PY608E-PC sediment core (Lake Pumoyum Co, southern Tibetan Plateau) based on radiocarbon dating of total organic carbon  

NASA Astrophysics Data System (ADS)

Paleoclimatic records from the Tibetan Plateau provide important clues for understanding the Asian monsoon and Asian climate systems. To reconstruct climatic and environmental changes in the southern Tibetan Plateau, a 3.77-m-long sediment core (PY608E-PC) was taken from the southeastern part of Lake Pumoyum Co in August 2006. Because terrestrial plant residues are extremely rare in this core, we performed radiocarbon dating on the total organic carbon fraction. We also estimated the old carbon effect and radiocarbon reservoir age of the total organic carbon fraction. Using these estimates, we propose a new radiocarbon chronology for past climatic changes from ca. 12,500 to 700 cal BP. The linear sedimentation rate of the core was founded to be constant at 32.0 cm/kyr, indicating stable sedimentation conditions in Lake Pumoyum Co from the period of the Younger Dryas to the Holocene.

Watanabe, Takahiro; Nakamura, Toshio; Matsunaka, Tetsuya; Nara, Fumiko Watanabe; Zhu, Liping; Wang, Junbo; Kakegawa, Takeshi; Nishimura, Mitsugu

2013-01-01

95

Using Total Quality To Better Manage an Institutional Research Office. AIR 1991 Annual Forum Paper.  

ERIC Educational Resources Information Center

Responding to the call for higher education to adopt a new paradigm in managing its administrative processes, an Institutional Research Office at Delaware County Community College (DCCC) in Pennsylvania made a two-year effort to use a Total Quality approach in its management. Total Quality Management is a Japanese movement based on the teachings…

Heverly, Mary Ann

96

Polluted harbor sediment and the annual reproductive cycle of the female flounder, Platichthys fiesus (L.)  

SciTech Connect

Compounds such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs),and pesticides are metabolized by enzyme systems, which are also involved in steroid metabolism. Disturbances of reproduction may therefore occur through the interference of these compounds with the endocrine system. Several aspects of reproduction were studied in the flounder, Platichthys fiesus (L.), an euryhaline flatfish which inhabits coastal waters and is therefore a suitable biomonitor for the effects of chemical pollutants. Fish were kept during three years in mesocosm systems of which the first provided a control, while the second one contained polluted sediment, derived from the Rotterdam harbor. In November, all ovaries from both mesocosms contained vitellogenic oocytes. In May, all the control fish were previtellogenic, while the ovaries of fish from the polluted mesocosm contained, besides previtellogenic oocytes, a large number of vitellogenic oocytes, indicating that an estrogenic induction had occurred. The in vitro tissue incubations with androstenedione as precursor revealed that the ovarian capacity to synthesize testosterone (T), estrone (E{sub 2}) and 17{beta}-estradiol (E{sub 2}) didn`t differ between both mesocosms. In May, however, the levels of T and E{sub 2} as well as the level of the yolk-precursor vitellogenin were significantly higher in the polluted mesocosm. The conclusion from this study was that polluted harbor sediment contains compounds that effect normal reproductive development, i.e. the induction of premature vitellogenesis.

Janssen, P.A.H.; Lambert, J.G.D.; Goos, H.J.T. [Department of Experimental Zoology, Utrecht (Netherlands). Research Group Comparative Endocrinology; Wezel, A.P. van; Opperhuizen, A. [National Inst. for Coastal and Marine Management, The Hague (Netherlands). Dept. of Ecotoxicology

1995-12-31

97

Journal of Coastal Research 20 3 853861 West Palm Beach, Florida Summer 2004 Process Based Modeling of Total Longshore Sediment  

E-print Network

Journal of Coastal Research 20 3 853­861 West Palm Beach, Florida Summer 2004 Process Based Research, 20(3), 853­861. West Palm Beach (Florida), ISSN 0749-0208. Waves, currents, and longshore sand upon the sediment size, the shape of the beach profile, and the particular local sediment flux formula

Kirby, James T.

98

Dioxin Chronology and Fluxes in Sediments of the Houston Ship Channel, Texas: Influences of Non-steady State Sediment Transport and Total Organic Carbon  

NASA Astrophysics Data System (ADS)

Polychlorinated dibenzo-p-dioxins and dibenzofurans (dioxins) are persistent contaminants that bio-accumulate and pose serious risks to biota and humans. The primary objective of this study was to determine the history and mechanisms of dioxin accumulation in sediments of the Houston Ship Channel (HSC) using analytical data on natural and anthropogenic radionuclides (7Be, 137Cs and 210Pb) and dioxins. Results showed that present-day sedimentary dioxin accumulation rates are orders of magnitude higher than atmospheric inputs to the HSC, as determined from a wetland sediment core (FW1) and direct measurements. Most stations showed dioxin peaks in the near surface, indicating continuing inputs despite federal regulations. Stations with high dioxin inventories (11270 > 11193 > 16499 > 15979 > 11261) reflect accentuated accumulation in the HSC as one moves west towards Buffalo Bayou (11270, 15979), at the confluence of the HSC and the San Jacinto River (11261) and upstream in the San Jacinto River (11193). While station 11270 had the highest dioxin inventory, and nearby station 11261 had the highest sediment accumulation rates and dioxin fluxes, present-day dioxin fluxes at 11270 are less than average fluxes and inventories for station 11261 are less than average inventories, for all sites. These results support the interpretation that the HSC is influenced by episodic sediment resuspension, erosion and lateral transport processes driven by tides, wind, shipping and dredging, which can cause intermittently high accumulations of dioxins.

Yeager, K.; Santschi, P.; Raifai, H.; Suarez, M.; Brinkmeyer, R.; Hung, C.; Schindler, K.; Andres, M.; Weaver, E.

2007-05-01

99

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

NASA Astrophysics Data System (ADS)

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 (45.0°S, 169.7°E, 370 m asl, 547 spectra March 1993 through April 1997), and Wollongong, Australia (34.45°S, 150.88°E, 30 m asl, 358 spectra May 1996 through April 1997). The annual mean column amounts are 9.15×1015 molecules cm-2 above Lauder and 9.84×1015 molecules cm-2 above Wollongong, corresponding to tropospheric mixing ratios of 480 and 490 parts per trillion by volume, respectively, with the assumed mixing ratio vertical profiles. The secular trend in total column OCS is less than 1% per year. Variability of all measurements about the means implies an atmospheric lifetime for OCS of at least 2.8 years. Comparison with earlier measurements in the northern hemisphere yields a north/south interhemispheric ratio in the range 1.1-1.2. There are peak-to-peak apparent annual cycles in total column OCS of 6% at Lauder and 18% at Wollongong with a late summer maximum. Seasonal tropopause height variation accounts for a 5-6% amplitude, and the remainder of the amplitude in Wollongong is assumed to be due to changes in the tropospheric mixing ratio.

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

1998-04-01

100

Seasonal variation of total and biochemically available concentrations of PAHs in a floodplain lake sediment has no effect on the benthic invertebrate community.  

PubMed

Floodplain areas in the Netherlands are moderately to heavily contaminated with trace metals and organic contaminants. The impact of this sediment pollution on benthic invertebrates is best described with so-called 'bioavailable' concentrations instead of total concentrations. Studies into the effect of contaminants on biota are usually a snapshot in time, with one or two samples in a year. In such studies, effect of seasonal variation cannot be detected. Objective of this study was to investigate the temporal variation of sediment PAH contamination in one floodplain lake, and possible consequences for the benthic invertebrate community. This was done by sampling biota, abiotic variables and sediment contaminants every four weeks during one year. We observed a limited seasonal variation in total and bioavailable concentrations of PAHs. Multivariate analysis revealed that the PAH contamination is not a significant factor for the benthic invertebrate community in this floodplain lake. Bioavailable concentrations of PAHs were low and no effects could be expected based on the measured values. No increase of available PAHs was observed in periods where conditions for degradation were absent (low temperature, anaerobic). These results also indicate that in such floodplain lake systems, with historical pollution, the timing of sampling to assess sediment contamination with organic pollutants is of limited importance. This can be useful for planning sampling in risk assessment studies. PMID:19167023

De Lange, H J; Peeters, E T H M; Harmsen, J; Maas, H; De Jonge, J

2009-04-01

101

Alternate bearing influences annual nutrient consumption and the total nutrient content of mature pistachio trees  

Microsoft Academic Search

The influence of alternate bearing on nutrient utilization and total tree nutrient content was investigated in mature pistachio\\u000a (Pistacia vera L. cv Kerman trees). Removal of N, P and Zn in fruit and abscised leaves of cropping (‘on’) trees averaged 5, 6, and 2 times,\\u000a respectively, the removal in abscised leaflets of the non-fruiting, ‘off’ year trees. One hundred and

Patrick H. Brown; Steven A. Weinbaum; Geno A. Picchioni

1995-01-01

102

Microgram scale determination of total lipid carbon in valuable sediments using a thin-layer chromatography/flame ionization detector analyzer  

SciTech Connect

Rapid and small size analytical methods of extractable lipid carbon in sediments are presented by applying a thin-layer chromatography/flame ionization detection system (TLC/FID analyzer, Iatroscan TH-10), using silica-coated Chromarod without development. A minimum of 60 samples of total lipid carbon can be analyzed in 10 min. The sample size used averaged 2.5 ..mu..g of lipid carbon, with an allowable reproducibility (standard deviation +/- 10%). The good correlation of total lipid carbon, in a 1400-m core sediment sample of Lake Biwa, is obtained both by this method and by the wet oxidation method. The wet oxidation method has been developed by modifying Menzel and Vaccaro's method, which is the determination of dissolved organic carbon.

Ogura, K.; Ishimura, Ml; Hisatake, J.

1987-05-01

103

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

104

Microgram scale determination of total lipid carbon in valuable sediments using a thin-layer chromatography\\/flame ionization detector analyzer  

Microsoft Academic Search

Rapid and small size analytical methods of extractable lipid carbon in sediments are presented by applying a thin-layer chromatography\\/flame ionization detection system (TLC\\/FID analyzer, Iatroscan TH-10), using silica-coated Chromarod without development. A minimum of 60 samples of total lipid carbon can be analyzed in 10 min. The sample size used averaged 2.5 ..mu..g of lipid carbon, with an allowable reproducibility

Kazuko. Ogura; Masako. Ishimura; Junko. Hisatake

1987-01-01

105

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

PubMed

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

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

2012-09-01

106

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

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. PMID:24531187

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

2014-01-01

108

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

E-print Network

Cold seeps are areas of high biomass in the deep-sea, the impacts of these food-rich environments upon the sediment community is unknown in the Gulf of Mexico. The structure and function of benthic communities was investigated at food-rich and food...

Nunnally, Clifton Charles

2004-11-15

109

Suspended-sediment loads and reservoir sediment trap efficiency for Clinton Lake, Kansas, 2010-12  

USGS Publications Warehouse

Continuous streamflow and turbidity data collected from October 1, 2010, to September 30, 2012, at a site upstream and downstream from Clinton Lake, Kansas, were used to compute the total suspended-sediment load delivered to and released from the reservoir as well as the sediment trap efficiency for the reservoir. Ongoing sedimentation is inhibiting the ability of Clinton Lake to serve several purposes including flood control, water supply, and recreation. The inflow suspended-sediment load was substantially larger than the outflow load and most of the suspended-sediment load was delivered during short-term, high-discharge periods. Respectively, the total 2-year inflow and outflow suspended-sediment loads were computed to be 44.4 and 1.49 million pounds. Sediment trap efficiency for the reservoir was estimated to be 97 percent. The mean annual suspended-sediment yield from the upstream basin was estimated to be 60,500 pounds per square mile. Because this study was completed during a drought, the estimated inflow suspended-sediment load and suspended-sediment yield likely are substantially less than what would occur during a period of average or above average precipitation and runoff.

Juracek, Kyle E.

2013-01-01

110

Total and labile metals in surface sediments of the tropical river-estuary system of Marabasco (Pacific coast of Mexico): Influence of an iron mine.  

PubMed

Marabasco is a tropical river-estuary system comprising the Marabasco river and the Barra de Navidad Lagoon. The river is impacted by the Peña Colorada iron mine, which produces 3.5 million tons of pellets per year. Thirteen surface sediment samples were collected in May 2005 (dry season) in order to establish background levels of Al, Cd, Co, Cu, Fe, Ni, Pb, and Zn in the system and to ascertain the potential mobility of metals in the sediments. Analyses were carried out in the fraction finer than 63 microm, and labile metals extracted according the BCR procedure. Certified reference materials were used for validation of methods. Total concentrations of Cd, Co, Cu, Ni, Pb, and Zn were in the range of 0.05-0.34, 6-95, 0.7-31, 9-26, 2-18, and 53-179 mgkg(-1), respectively; Al and Fe ranges of 24-127, and 26-69 mgg(-1) correspondingly. Cadmium was found to be significantly labile in the sediments (20-100%), followed by Co (0-35%), Ni (3-16%) and Zn (0-25%), whereas the labile fraction for Cu, Fe and Pb was almost negligible (<4%). According with the total metal concentrations, background levels and normalised enrichment factors (NEF) of the metals studied, the impact of the Peña Colorada iron mine on the Marabasco system is lower than expected when compared with other similar World systems influenced by mining activities. PMID:17997460

Marmolejo-Rodríguez, Ana Judith; Prego, Ricardo; Meyer-Willerer, Alejandro; Shumilin, Evgueni; Cobelo-García, Antonio

2007-01-01

111

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

112

Estimating sediment discharge: Appendix D  

USGS Publications Warehouse

Sediment-discharge measurements usually are available on a discrete or periodic basis. However, estimates of sediment transport often are needed for unmeasured periods, such as when daily or annual sediment-discharge values are sought, or when estimates of transport rates for unmeasured or hypothetical flows are required. Selected methods for estimating suspended-sediment, bed-load, bed- material-load, and total-load discharges have been presented in some detail elsewhere in this volume. The purposes of this contribution are to present some limitations and potential pitfalls associated with obtaining and using the requisite data and equations to estimate sediment discharges and to provide guidance for selecting appropriate estimating equations. Records of sediment discharge are derived from data collected with sufficient frequency to obtain reliable estimates for the computational interval and period. Most sediment- discharge records are computed at daily or annual intervals based on periodically collected data, although some partial records represent discrete or seasonal intervals such as those for flood periods. The method used to calculate sediment- discharge records is dependent on the types and frequency of available data. Records for suspended-sediment discharge computed by methods described by Porterfield (1972) are most prevalent, in part because measurement protocols and computational techniques are well established and because suspended sediment composes the bulk of sediment dis- charges for many rivers. Discharge records for bed load, total load, or in some cases bed-material load plus wash load are less common. Reliable estimation of sediment discharges presupposes that the data on which the estimates are based are comparable and reliable. Unfortunately, data describing a selected characteristic of sediment were not necessarily derived—collected, processed, analyzed, or interpreted—in a consistent manner. For example, bed-load data collected with different types of bed-load samplers may not be comparable (Gray et al. 1991; Childers 1999; Edwards and Glysson 1999). The total suspended solids (TSS) analytical method tends to produce concentration data from open-channel flows that are biased low with respect to their paired suspended-sediment concentration values, particularly when sand-size material composes more than about a quarter of the material in suspension. Instantaneous sediment-discharge values based on TSS data may differ from the more reliable product of suspended- sediment concentration values and the same water-discharge data by an order of magnitude (Gray et al. 2000; Bent et al. 2001; Glysson et al. 2000; 2001). An assessment of data comparability and reliability is an important first step in the estimation of sediment discharges. There are two approaches to obtaining values describing sediment loads in streams. One is based on direct measurement of the quantities of interest, and the other on relations developed between hydraulic parameters and sediment- transport potential. In the next sections, the most common techniques for both approaches are briefly addressed.

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

2008-01-01

113

Total reductive dechlorination of chlorobenzenes to benzene by a methanogenic mixed culture enriched from Saale river sediment  

Microsoft Academic Search

A methanogenic mixed culture enriched from Saale river sediment was able to transform all chlorobenzenes by reductive dechlorination\\u000a via monochlorobenzene to unsubstituted benzene after a short lag phase of only 1 week. The formation of benzene was confirmed\\u000a by GC\\/MS in pentane extracts of the sludge samples, as well as in the headspace gas of the batch cultures. The spectra

J. Nowak; N. H. Kirsch; W. Hegemann; H.-J. Stan

1996-01-01

114

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

115

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

116

Estimating the Contributions of Surface Wash-off and Channel Erosion to Total Sediment and Solute Loads in a Small Mixed Land Use Watershed  

NASA Astrophysics Data System (ADS)

Watershed sediment and solute loads originate from many different sources. These can include point sources, soil erosion, impervious surface wash-off, channel bank and bed erosion, and other sources depending on the land use activities within the watershed. However, the difficulties encountered in quantifying the contributions of specific nonpoint sources to watershed loads magnifies the uncertainty in watershed management efforts aimed at mitigating the pollutants. The goal of this research is to quantify the contribution of wash-off from residentially developed land and stream channel erosion to total watershed sediment and solute loadings within a 103 ha tributary watershed of Potash Brook, in Chittenden County, Vermont. To do so we deployed autosamplers at two stream cross sections and within two representative storm drain outfalls to sample TSS, TN, NO3-, TKN, TP, and Cl-. Samples were collected during storm events on a flow weighted composite basis, and by periodic base flow sampling. In stream sampling was conducted over a total 5 years and storm drain sampling covered a total of 2 years. Preliminary analysis of these data suggests that surface wash-off from developed portions of the watershed can generate greater than 90% of the TSS and greater than 50% of the Cl- loads measured at the watershed outlet sampling location. Currently, these data are being incorporated into an EPA-SWMM model of the watershed coupled with an evolutionary strategies parameter search algorithm. The model generated and measured wash-off data will be used with the measured load data at the watershed outlet to estimate the contribution of the stream channel by difference over all sampled events.

Nipper, J.; Bowden, W. B.

2009-12-01

117

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

USGS Publications Warehouse

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

Simon, Nancy S.; Ingle, Sarah N.

2011-01-01

118

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

119

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

120

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

NASA Astrophysics Data System (ADS)

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

Chang, A.; Pedersen, T. F.

2009-04-01

121

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...

122

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

USGS Publications Warehouse

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

Juracek, Kyle E.

2010-01-01

123

Challenges in Measuring and Predicting Medium Term (Weeks to Annual) Aeolian Sediment Transport in Beach-Dune Systems  

NASA Astrophysics Data System (ADS)

Coastal dune budgets depend on sediment input by wind from the beach. Calculation of aeolian transport is thus a primary factor to understand coastal dune evolution and beach-dune coupled dynamics. However, measuring aeolian sediment transport in coastal areas presents fundamental technical and conceptual limitations that make numerical modeling difficult. Wind tunnel experiments isolate and reduce the number of variables to study, which is a necessary procedure to clearly manifest mechanistic relationships between cause and effect. But even with refinement and inclusion of new variables, traditional sediment transport formulas derived from wind tunnel experiments do not usually work well in natural areas. Short-term experiments may include precise instrumentation to obtain high frequency, detail time series of variables involved in aeolian transport, but inferring information at larger scales is problematic without knowledge of the timing and magnitude of particular transport events. There are two primary problems in attempting to predict sediment inputs to coastal dunes over periods of weeks, months or years: 1) to determine an appropriate set of predictive equations that incorporate complexities such as surface moisture content, beach width and the presence of vegetation; and 2) to provide quantitative data on these variables for input into the model at this time scale. Remote sensing techniques and the use of GIS software open the possibility to monitor key parameters regulating sediment transport dynamics at high spatial and temporal resolution over time scales beyond short-term experiments. These were applied at Greenwich Dunes, Prince Edward Island National Park (Canada), in an attempt to measure factors affecting aeolian sediment input to the foredune at a medium scale. Three digital cameras covering different sections of the beach and foredune provide time series on shoreline position, fetch distances, vegetation cover, ice/snow presence, or superficial moisture content. The rectification of oblique images to UTM maps allows to keep the spatial variability of these factors, and thus to perform detailed analysis on their complex evolution. Auxiliary instrumentation such as anemometers, safires, or erosion-deposition pins completes the basic set up. Data is processed using ArcGIS 9.2 and PCI Geomatica 9.1, and managed by an ArcCatalog Geodatabase. The coupling of new technologies (digital imagery) with traditional instrumentation (e.g. anemometers), and the extensive GIS capabilities both in the spatial and temporal domain, permits a new set of questions in aeolian coastal research. The overall goal is to obtain information on what is the frequency and magnitude of transport events at the beach or what are the key parameters regulating them. Challenges remain in improving methodologies to measure sediment transport rates. Ironically enough, we are able to obtain high quality time series on the factors affecting aeolian transport at the beach, but actual transport rates are measured with rather rudimentary techniques or instrumentation not adapted to meso-scale monitoring. This information is needed to test new approaches in modeling and understanding aeolian sediment input from the beach to the foredunes.

Delgado-Fernandez, I.

2009-05-01

124

Understanding Stream Channel Sediment Source Contributions For The Paradise Creek Watershed In Northern Idaho  

NASA Astrophysics Data System (ADS)

Excess sediment from agricultural areas has been a major source of impairment for water bodies, resulting in the implementation of mitigation measures across landscapes. Watershed scale reductions often target upland erosion as key non-point sources for sediment loading. Stream channel dynamics, however, also play a contributing role in sediment loading in the form of legacy sediments, channel erosion and deposition, and buffering during storm events. In-stream contributions are not well understood, and are a potentially important consideration for Total Maximum Daily Loads (TMDLs). The objective of this study is to differentiate stream bank and stream bed sediment contributions and better understand the role of legacy sediments. The study area is the Paradise Creek Watershed in northern Idaho. We modeled sediment yield to the channel system using the Water Erosion Prediction Project (WEPP) model, and subsequent channel erosion and deposition using CONCEPTs. Field observations of cross-sections along the channel system over a 5-year period were collected to verify model simulations and to test the hypothesis that the watershed load was composed predominantly of legacy sediments. Our modeling study shows that stream channels contributed to 39% of the total annual sediment load for the basin, with a 19-year time lag between sediments entering the stream to leaving the watershed outlet. Observations from long-term cross sectional data in the watershed, and a sediment fingerprinting analysis will be presented to better understand sediment contributions from within the stream channel system.

Rittenburg, R.; Boll, J.; Brooks, E. S.

2013-12-01

125

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

PubMed

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

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

2014-10-01

126

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

127

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

128

Monoclonal antibody detection of chlorinated benzenes on contaminated sediments. Annual report, 1 May 1992-30 April 1993  

SciTech Connect

The modified soil ELISA, which eliminates the need for contaminant extraction prior to analysis, was demonstrated using crushed brick as a model soil matrix. Preliminary data were collected which tested for 1,2 -dichlorobenzene and 4-chloroaniline. Monoclonal antibodies were produced to three chlorobenzenes (chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene). Cross-reactivity experiments conducted with the antibodies to 4-chloroaniline showed strong differentiation between the target analyte and closely related chlorinated benzyl compounds. The antibodies to the chlorobenzenes continue to be used in developing a nonextractive soil immunoassay for chlorobenzenes. Immunoassay, Sediment testing, ELISA.

Mossman, D.J.; Feldbush, T.L.

1993-05-27

129

Sedimentation and occurrence and trends of selected nutrients, other chemical constituents, and cyanobacteria in bottom sediment, Clinton Lake, northeast Kansas, 1977-2009  

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, cyanobacterial akinetes, and the radionuclide cesium-137 in the bottom sediment of Clinton Lake, northeast Kansas. The total estimated volume and mass of bottom sediment deposited from 1977 through 2009 in the conservation (multi-purpose) pool of the reservoir was 438 million cubic feet and 18 billion pounds, respectively. The estimated sediment volume occupied about 8 percent of the conservation-pool, water-storage capacity of the reservoir. Sedimentation in the conservation pool has occurred about 70 percent faster than originally projected at the time the reservoir was completed. Water-storage capacity in the conservation pool has been lost to sedimentation at a rate of about 0.25 percent annually. Mean annual net sediment deposition since 1977 in the conservation pool of the reservoir was estimated to be 563 million pounds per year. Mean annual net sediment yield from the Clinton Lake Basin was estimated to be 1.5 million pounds per square mile per year. Typically, the bottom sediment sampled in Clinton Lake was at least 99 percent silt and clay. The mean annual net loads of total nitrogen and total phosphorus deposited in the bottom sediment of Clinton Lake were estimated to be 1.29 million pounds per year and 556,000 pounds per year, respectively. The estimated mean annual net yields of total nitrogen and total phosphorus from the Clinton Lake Basin were 3,510 pounds per square mile per year and 1,510 pounds per square mile per year, respectively. Throughout the history of Clinton Lake, total nitrogen concentrations in the deposited sediment generally were uniform and indicated consistent inputs to the reservoir over time. Likewise, total phosphorus concentrations in the deposited sediment generally were uniform. Although, for two of three coring sites, a possible positive trend in phosphorus deposition was indicated. The Wakarusa River possibly was a larger contributor of nitrogen and phosphorus to Clinton Lake than was Rock Creek. As a principal limiting factor for primary production in most freshwater environments, phosphorus is of particular importance because increased inputs can contribute to accelerated reservoir eutrophication and the production of algal toxins and taste-and-odor compounds. Trace-element concentrations in the bottom sediment of Clinton Lake generally were uniform over time. As is typical for eastern Kansas reservoirs, arsenic, chromium, and nickel concentrations typically exceeded the threshold-effects guidelines, which represent the concentrations above which toxic biological effects occasionally occur. Zinc concentrations frequently exceeded the threshold-effects guideline. 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. Cyanobacterial akinetes (cyanobacteria resting stage) in the bottom sediment of Clinton Lake, combined with historical water-quality data on chlorophyll-a and total phosphorus concentrations, indicated that the reservoir likely has been eutrophic throughout most of its history. A statistically significant increase in cyanobacterial akinetes in the bottom sediment indicated that Clinton Lake may have become more eutrophic over the life of the reservoir. The increase in cyanobacterial akinetes may, in part, be related to a possible increase in total phosphorus concentrations.

Juracek, Kyle E.

2011-01-01

130

12 CFR Appendix L to Part 226 - Assumed Loan Periods for Computations of Total Annual Loan Cost Rates  

Code of Federal Regulations, 2014 CFR

... Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM (CONTINUED) TRUTH IN LENDING (REGULATION Z) Pt. 226, App. L Appendix L to Part 226—Assumed Loan Periods for Computations of Total...

2014-01-01

131

12 CFR Appendix L to Part 226 - Assumed Loan Periods for Computations of Total Annual Loan Cost Rates  

Code of Federal Regulations, 2010 CFR

...to Part 226 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM TRUTH IN LENDING (REGULATION Z) Pt. 226, App. L Appendix L to Part 226—Assumed Loan Periods for Computations of Total...

2010-01-01

132

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

133

Concentration and annual accumulation values of heavy metals in lake sediments: Their significance in studies of the history of heavy metal pollution  

Microsoft Academic Search

The first part of the paper discusses the significance of using either concentration or accumulation values for expressing the results of investigations of lake sediment cores aimed at studying the history of heavy metal pollution. Neither the values for heavy metal concentration in the lake sediment, whether expressed per gram dry sediment or per gram soluble (organic) sediment, nor the

Ingemar Renberg

1986-01-01

134

Evaluation of the effects of agricultural conservation practices on sediment yield in the Colusa Basin, California  

NASA Astrophysics Data System (ADS)

The Soil and Water Assessment Tool (SWAT) was used to assess the impact of agricultural best management practices (BMPs) on sediment runoff from almond orchards in the lower Colusa Basin Drain watershed in the Sacramento Valley, California. This study used modeling techniques that include varying hydrologic parameters for both upland areas and small channels to quantify the effects of BMPs water quality. The BMPs simulated in this study are commonly used in almond orchards and include strip cropping, cover cropping, vegetative filter strips, grassed waterways and channel stabilization. The effectiveness of each BMP was simulated for an above average, below average and average rainfall year. Comparison of annual total watershed sediment loads for each BMP simulation showed that overall, channel stabilization and grassed waterways, which target in stream sediment erosion and transport, are the most effective BMPs with an estimated respective reduction in sediment load of 18% and 35% for a below average precipitation year, 13% and 26% for an above average precipitation year, and 17% and 30% for an average precipitation year. Simulations of BMPs designed to reduce sediment transport in upland areas, which include strip cropping and vegetative filter strips, estimated a reduction in total annual sediment load of less than 1% at the watershed outlet. These results indicated that in-stream sediment transport is the dominant sediment transport process in this watershed. Implementation of channel stabilization measures or grassed waterways on almond orchards is estimated to result in an annual reduction of total sediment load of 41,874 kg or 72,753 kg of sediment per square kilometer of almond orchard for an above average precipitation year.

Gatzke, S. E.; Zhang, M.

2009-12-01

135

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. PMID:16346037

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

1982-01-01

136

Long-term runoff and sediment yields from small semi-arid watersheds in southern Arizona  

Technology Transfer Automated Retrieval System (TEKTRAN)

This study presents analysis of 34 years of precipitation, runoff and sediment data collected from 8 small (1.1 to 4.0 ha) semi-arid rangeland watersheds in southern Arizona, USA. Average annual precipitation ranged between 354 mm and 458 mm with 53% of the total rainfall occurring from July throug...

137

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

138

Sediment and Carbon Budgets for Chesapeake Bay and its Watershed: Impacts of Land Clearance and Climate Variability  

NASA Astrophysics Data System (ADS)

Sediment and total organic carbon (TOC) flux from continents to oceans are factors for understanding carbon sinks in continental margins sediments in particular, and the global carbon cycle, in general. However, most estimates of river-borne sediment and TOC suffer from a lack of long-term instrumental records and a poor understanding of the impacts of human activities on sediment processes. We constructed sediment and TOC budgets for northern Chesapeake Bay and its watershed, an intensely monitored (>20 years), large (~18,000 km2 surface area, 166,000 km2 watershed area) mid-latitude (37-39° N) estuary, for both pre- (1000 AD to 1850 AD) and post-colonial (1850 to present) maximum land clearance intervals. The bay's main channel and tidal tributaries have been catchments for riverine sediment for 8,000 years such that their stratigraphic records provide a detailed history of sediment and carbon flux. Similarly, total suspended solid (TSS) and organic carbon data from monitoring programs and modeling of land-use change in the bay's watershed provide spatially-robust, independent estimates of sediment and carbon yield. Sediment core records indicate that land clearance increased mean annual riverine sediment (total sediment minus that from shoreline erosion) delivered to the northern bay channel and tributaries by 3 to 5-fold. Post-land clearance estimates from the sediment record compare favorably to independent values derived from monitoring riverine TSS and from modeling of land-surface erosion. Using an empirically-derived estimate of 3.7% for carbon content in present day mid-Atlantic sediments, we observed a 3-fold increase in terrestrially-derived carbon flux since the 1800s. In addition to the effects of land clearance, interannual variability in regional precipitation and freshwater discharge during the past 20 years results in annual carbon flux variation of more than 20% around the mean condition.

Cronin, T. M.; Saenger, C.; Willard, D. A.

2004-05-01

139

Whole-Cell versus Total RNA Extraction for Analysis of Microbial Community Structure with 16S rRNA-Targeted Oligonucleotide Probes in Salt Marsh Sediments  

PubMed Central

rRNA-targeted oligonucleotide probes have become powerful tools for describing microbial communities, but their use in sediments remains difficult. Here we describe a simple technique involving homogenization, detergents, and dispersants that allows the quantitative extraction of cells from formalin-preserved salt marsh sediments. Resulting cell extracts are amenable to membrane blotting and hybridization protocols. Using this procedure, the efficiency of cell extraction was high (95.7% ± 3.7% [mean ± standard deviation]) relative to direct DAPI (4?,6?-diamidino-2-phenylindole) epifluorescence cell counts for a variety of salt marsh sediments. To test the hypothesis that cells were extracted without phylogenetic bias, the relative abundance (depth distribution) of five major divisions of the gram-negative mesophilic sulfate-reducing delta proteobacteria were determined in sediments maintained in a tidal mesocosm system. A suite of six 16S rRNA-targeted oligonucleotide probes were utilized. The apparent structure of sulfate-reducing bacteria communities determined from whole-cell and RNA extracts were consistent with each other (r2 = 0.60), indicating that the whole-cell extraction and RNA extraction hybridization approaches for describing sediment microbial communities are equally robust. However, the variability associated with both methods was high and appeared to be a result of the natural heterogeneity of sediment microbial communities and methodological artifacts. The relative distribution of sulfate-reducing bacteria was similar to that observed in natural marsh systems, providing preliminary evidence that the mesocosm systems accurately simulate native marsh systems. PMID:10877803

Frischer, Marc E.; Danforth, Jean M.; Healy, Michele A. Newton; Saunders, F. Michael

2000-01-01

140

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

141

Analysis of sediment retention in western riverine wetlands: the Yampa River watershed, Colorado, USA.  

PubMed

We quantified annual sediment deposition, bank erosion, and sediment budgets in nine riverine wetlands that represented a watershed continuum for 1 year in the unregulated Yampa River drainage basin in Colorado. One site was studied for 2 years to compare responses to peak flow variability. Annual mean sediment deposition ranged from 0.01 kg/m(2) along a first-order subalpine stream to 21.8 kg/m(2) at a sixth-order alluvial forest. Annual mean riverbank erosion ranged from 3 kg/m-of-bank at the first-order site to 1000 kg/m at the 6(th)-order site. Total sediment budgets were nearly balanced at six sites, while net export from bank erosion occurred at three sites. Both total sediment deposition (R(2) = 0.86, p < 0.01) and bank erosion (R(2) = 0.77, p < 0.01) were strongly related to bankfull height, and channel sinuosity and valley confinement helped to explain additional variability among sites. The texture and organic fraction of eroded and deposited sediment were relatively similar in most sites and varied among sites by watershed position. Our results indicate that bank erosion generally balances sediment deposition in riverine wetlands, and we found no distinct zones of sediment retention versus export on a watershed continuum. Zones of apparent disequilibrium can occur in unregulated rivers due to factors such as incised channels, beaver activity, and cattle grazing. A primary function of many western riverine wetlands is sediment exchange, not retention, which may operate by transforming materials and compounds in temporary sediment pools on floodplains. These results are considered in the context of the Hydrogeomorphic approach being implemented by the U.S. government for wetland resource management. PMID:15170244

Arp, Christopher D; Cooper, David J

2004-03-01

142

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

143

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

NASA Astrophysics Data System (ADS)

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

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

2008-07-01

144

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

145

SEDIMENT REMOVAL  

EPA Science Inventory

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

146

Sediment transport in a large impounded river: The lower Ebro, NE Iberian Peninsula  

NASA Astrophysics Data System (ADS)

The sediment transport of the highly regulated lower Ebro River is estimated on the basis of a measuring programme carried out between 2002 and 2004. Total sediment transport, including both suspended load and bedload, was measured upstream and downstream from the Mequinenza and Riba-roja reservoirs, with special attention to the transport during floods. Annual total load upstream from the dams is estimated at around 1.64·10 6 t, of which at least 99% is transported in suspension. Annual total load downstream from the dams is estimated at around 0.45·10 6 t, of which 60% is transported in suspension and the remaining 40% as bedload (mean D50-bl in the range of 32 mm). Total load represents 3% of what was transported at the beginning of the 20th century in the delta plain. Sediment yield is three to four times lower below the dams, a fact that is caused by the trapping of sediment within the reservoirs (around 90% in the case of suspended sediment and 100% in the case of bedload). As a consequence, sediment that is transported downstream from the dams is all entrained from the riverbed and eroded from the banks. The sediment deficit causes a mean riverbed incision of 30 mm per year, as estimated from bedload measurements and by means of scour chains and painted pebbles located between the lowermost dam and the measuring section 28 km downstream. Since floods have been reduced on average by 25% but sediment supply from upstream has been reduced to almost nothing, the river channel of the lower Ebro River will continue exporting sediment both during floods (> 2000 m 3/s, mostly bedload) and frequent high flows (1000 m 3/s to 2000 m 3/s), making the incision progressive unless restoration steps are taken.

Vericat, Damia; Batalla, Ramon J.

2006-09-01

147

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

148

Annual Report 2005 Annual Report  

E-print Network

Annual Report 2005 Annual Report Annual Report Annual Report CSCS Swiss National Supercomputing Centre ual Report Annual Report Annual Report Annual Report Annual Report nnual Report Annual Report Annual Report Annual Report nual ReportAnnual Report Report port al ReportAnnual #12;Annual Report 2005

149

Annual Report 2006 Annual Report  

E-print Network

2 Annual Report 2006 Annual Report Annual Report Annual Report CSCS Swiss National Supercomputing Centre ual Report Annual Report Annual Report Annual Report Annual Report nnual Report Annual Report Annual Report Annual Report nual ReportAnnual Report Report port al ReportAnnual #12;Annual Report 2006

150

Annual Report 2009 Annual Report  

E-print Network

2 Annual Report 2009 Annual Report Annual Report Annual Report CSCS Swiss National Supercomputing Centre ual Report Annual Report Annual Report Annual Report Annual Report nnual Report Annual Report Annual Report Annual Report nual ReportAnnual Report Report port al ReportAnnual #12;AnnualReport2009

151

Annual Report 2008 Annual Report  

E-print Network

2 Annual Report 2008 Annual Report Annual Report Annual Report CSCS Swiss National Supercomputing Centre ual Report Annual Report Annual Report Annual Report Annual Report nnual Report Annual Report Annual Report Annual Report nual ReportAnnual Report Report port al ReportAnnual #12;Annual Report 2008

152

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

NASA Astrophysics Data System (ADS)

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.

McKee, Lester J.; Ganju, Neil K.; Schoellhamer, David H.

2006-05-01

153

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

154

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

155

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

156

Annual report of 1991 groundwater monitoring data for the Kerr Hollow Quarry and Chestnut Ridge Sediment Disposal Basin at the Y-12 Plant: Reporting and statistical evaluation of the subsequent year (sixth) data  

SciTech Connect

This annual report has historically been prepared to meet the annual reporting requirements of the Tennessee Department of and Environment and Conservation (TDEC), Hazardous Waste Management Regulation 1200-1-11-.05 (6)(e), for detection monitoring data collected on Resource Conservation and Recovery Act (RCRA) wells in place around facilities which are accorded interim status. The regulatory authority for these units at the Y-12 Plant is currently in transition. A Federal Facility Agreement (FFA) with an effective date of January 1, 1992, has been negotiated with the Department of Energy (DOE) for the Oak Ridge Reservation. This agreement provides a framework for remediation of the Oak Ridge Reservation so that both RCRA and CERCLA requirements are integrated into the remediation process and provides for State, EPA, and DOE to proceed with CERCLA as the lead regulatory requirement and RCRA as an applicable or relevant and appropriate requirement. This report is presented for the RCRA certified wells for two interim status units at the Y-12 Plant. These units are Kerr Hollow Quarry and Chestnut Ridge Sediment Disposal Basin. Kerr Hollow is currently undergoing clean closure under RCRA. The Chestnut Ridge Sediment Disposal Basin (CRSDB) was closed in 1989 under a TDEC approved RCRA closure plan. The relevance of a RCRA Post-Closure Permit to either of these units is a matter of contention between DOE and TDEC since the FFA does not contemplate post-closure permits.

McMahon, L.W. [Oak Ridge National Lab., TN (United States); Mercier, T.M. [H and R Technical Associates, Inc., Oak Ridge, TN (United States)] [comps.

1992-02-01

157

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

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

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

2002-01-01

158

Sediment transport and deposition, Walnut and Pacheco Creeks, Contra Costa County, California, August 1965-April 1970  

USGS Publications Warehouse

Average annual sediment discharge in Pacheco Creek basin, Contra Costa County, Calif., was larger during August 1965-April 1970 than the historical annual sediment discharge (1909-62) by a factor of about 1.3. This increas in sediment discharge is attributed primarily to an increased frequency of peak streamflows and to a larger average annual streamflow during the 1965-70 period.

Porterfield, George

1972-01-01

159

Sediment deposition and trends and transport of phosphorus and other chemical constituents, Cheney Reservoir watershed, south-central Kansas  

USGS Publications Warehouse

Sediment deposition, water-quality trends, and mass transport of phosphorus, nitrogen, selected trace elements, and selected pesticides within the Cheney Reservoir watershed in south-central Kansas were investigated using bathymetric survey data and reservoir bottom-sediment cores. Sediment loads in the reservoir were investigated by comparing 1964 topographic data to 1998 bathymetric survey data. Approximately 7,100 acre-feet of sediment deposition occurred in Cheney Reservoir from 1965 through 1998. As of 1998, sediment had filled 27 percent of the reservoir's inactive conservation storage pool, which is less than the design estimate of 34 percent. Mean annual sediment deposition was 209 acre-feet per year, or 0.22 acre-feet per year per square mile, and the mean annual sediment load was 453 million pounds per year. During the 3-year period from 1997 through 1999, 23 sediment cores were collected from the reservoir, and subsamples were analyzed for nutrients (phosphorus and nitrogen species), selected trace elements, and selected organic pesticides. Mean concentrations of total phosphorus in reservoir bottom sediment ranged from 94 milligrams per kilogram at the upstream end of the reservoir to 710 milligrams per kilogram farther downstream near the reservoir dam. The mean concentration for all sites was 480 milligrams per kilogram. Total phosphorus concentrations were greatest when more silt- and clay-sized particles were present. The implications are that if anoxic conditions (inadequate oxygen) occur near the dam, phosphorus could be released from the sediment and affect the drinking-water supply. Analysis of selected cores also indicates that total phosphorus concentrations in the reservoir sediment increased over time and were probably the result of nonpoint-source activities in the watershed, such as increased fertilizer use and livestock production. Mean annual phosphorus loading to Cheney Reservoir was estimated to be 226,000 pounds per year on the basis of calculations from deposited sediment in the reservoir. Mean total phosphorus concentration in the surface-water inflow to Cheney Reservoir was 0.76 milligram per liter, mean annual phosphorus yield of the watershed was estimated to be 0.38 pound per year per acre, and both are based on sediment deposition in the reservoir. A comparison of the Cheney Reservoir watershed to the Webster Reservoir, Tuttle Creek Lake, and Hillsdale Lake watersheds showed that phosphorus yields were smallest in the Webster Reservoir watershed where precipitation was less than in the other watersheds. Mean concentrations of total ammonia plus organic nitrogen in bottom sediment from Cheney Reservoir ranged from 1,200 to 2,400 milligrams per kilogram as nitrogen. A regression analysis between total ammonia plus organic nitrogen as nitrogen and sediment particle size showed a strong relation between the two variables and suggests, as with phosphorus, that total ammonia plus organic nitrogen as nitrogen adsorbs to the silt- and clay-sized particles that are transported to the deeper parts of the reservoir. An analysis of trends with depth of total ammonia plus organic nitrogen as nitrogen did not indicate a strong relation between the two variables despite the increase in fertilizer use in the watershed during the past 40 years. Selected cores were analyzed for trace elements. Concentrations of arsenic, chromium, copper, and nickel at many sites exceeded levels where adverse effects on aquatic organisms sometimes occur. Larger concentrations of these elements also occurred in sediment closer to the reservoir dam where there is a larger percentage of silt and clay in the bottom sediment than farther upstream. However, the lack of industrial or commercial land use in the watershed suggests that these concentrations may be the result of natural conditions. Organochlorine insecticides were detected in the reservoir-bottom sediment in Cheney Reservoir. DDT and its degradation products DDD and DD

Mau, D.P.

2001-01-01

160

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

PubMed

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

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

2014-03-15

161

Accumulations of total metal in dominant shrimp species (Palaemon adspersus, Palaemon serratus, Parapenaeus longirostris) and bottom surface sediments obtained from the Northern Inner Shelf of the Sea of Marmara.  

PubMed

The aim of this study is to determine the total metal (aluminum, copper, manganese, nickel, lead, zinc, cadmium, iron, mercury) contents of dominant shrimp species and sediments present at 1-50 m depths of the Northern Inner Shelf of the Sea of Marmara. Shrimp and sediment samples were collected from four regions (Büyükçekmece, Silivri, Tekirda?, Sarköy) and from different depths (1, 5, 10, 20, 30, 50 m) at each region in September and November of 2003. Three shrimp species [Palaemon adspersus (Rathke, 1937), Palaemon serratus (Pennant, 1777), Parapenaeus longirostris (H. Lucas, 1846)] were identified to be dominant as a result of the examination on the obtained samples. Heavy metal contents of these three species were determined and the results were compared with the acceptable treshold values of the Seafood Standards and also with available literatures. The Cu contents were found to be higher than the treshold limits in all samples except P. longirostris from Silivri, also the Cd contents in all samples except P. adspersus from Büyükçekmece, the Zn contents only in P. adspersus and P. longirostris from Tekirda?, and the Pb contents in all species from all regions. These high values are the indicator of industrial pollution. There is not any data in the Seafood Standards about Mn, Ni, Fe and Al contents in shrimp species. The values of these metal contents were given in the present study. The examination of total metal distributions in bottom surface sediment samples in the Northern Inner Shelf of the Sea of Marmara showed that the determined values were higher than the shale average at some depths of examined stations. PMID:17406997

Kurun, A; Balkis, H; Balkis, N

2007-12-01

162

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...

163

Nitrogen turnover in drying sediments of an Amazon floodplain lake.  

PubMed

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

Koschorreck, Matthias

2005-05-01

164

Predicting the spatial patterns of hillslope sediment delivery to river channels in the Murrumbidgee catchment, Australia  

NASA Astrophysics Data System (ADS)

SummarySediment yield data derived from long-term sedimentation rates in 26 small farm dams in SE Australia were used to calibrate a spatially distributed soil erosion and sediment delivery model (WATEM/SEDEM) that takes into account contribution from gully erosion in areas of concentrated flow. For three different land use categories (poor, moderate and good vegetative cover), a sediment transport capacity coefficient was calibrated. All other parameters being equal, it was found that sediment transport capacity for cropland is 2 times higher than for degraded pasture and 20 times higher than for native forest and good pasture. Model efficiencies for the prediction of specific and total sediment yield are 0.56 and 0.89, respectively. These model efficiencies are much higher compared to those obtained when intense erosion in concentrated flow areas is not considered explicitly. Several of the catchments that were used for the calibration have very high sediment yield rates, which are attributed to the presence of gullies. The good performance of WATEM/SEDEM to all catchments suggests that the model accounts well for gully erosion. Next, the calibrated WATEM/SEDEM was applied to the Murrumbidgee River basin (30,000 km 2). A mean annual sediment input into the river channels from the hillslopes of 478,000 t was predicted. The spatial pattern of hillslope-derived suspended sediment delivery in the Murrumbidgee indicates that most of the sediment originates from a few tributaries downstream of Burrinjuck Reservoir. Given the fact that high-resolution datasets (including digital elevation models) are becoming available at reasonable cost, WATEM/SEDEM provides a powerful tool to predict hillslope sediment delivery under different environments including the spatial patterns of hillslope generated sediment fluxes.

Verstraeten, Gert; Prosser, Ian P.; Fogarty, Peter

2007-02-01

165

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

166

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

167

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

168

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

EPA Science Inventory

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

169

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

170

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

171

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

SciTech Connect

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

S.G.McLin; D.W. Lyons

2002-05-05

172

Identifying Drivers of Interannual Variability in Seasonal Sedimentation Patterns in the Corsica River (MD)  

NASA Astrophysics Data System (ADS)

The Corsica River, located on Maryland's eastern shore, has been the site of restoration efforts targeted to sediment and nutrient load reduction. While a long-term (~100-y) sediment budget has recently been established, processes that operate over shorter time scales more relevant to management may be more useful. In addition, a shorter-term sediment budget is needed to assess the potential impact of restoration efforts. To address these needs, bottom sediments have been collected to determine end-of-summer conditions for the last 6 years (2006-2011) and analyzed for their chemical and textural properties. Short-term (annual) deposition rates and biological mixing coefficients are calculated via the naturally occurring radioisotopes 7Be and 234Th (half-lives 53.3 and 24.1 d, respectively). Deposition rates are then used to determine the total mass deposit on an annual time scale for comparison across years to assess sedimentation patterns, as well as the interannual variability of observations. For example, deposition is greatest immediately upstream of a sill present near the mouth in one year but is located much farther upstream in the following year. Deposition patterns are compared to relatively simple indicators of physical forcing, such as rainfall and wind direction and magnitude, to identify potential drivers of interannual variability with the ultimate goal of deriving a predictive climatology of sedimentation.

Palinkas, C. M.; Cornwell, J.

2011-12-01

173

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

174

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

175

Three-year sediment transport in a highly erodible catchment: The River Isabena (Ebro Basin, Southern Pyrenees)  

NASA Astrophysics Data System (ADS)

Quantifying suspended sediment load is important in catchments containing highly erodible materials, especially in those that drain into reservoirs since high suspended yields generates and exacerbates reservoirs siltation. Suspended sediment records are also essential for the calibration and validation of numerical models that aim to reproduce past soil erosion and sediment dynamics and to generate reliable data for management purposes. The River Isabena is a mesoscale (445 km2) mountainous catchment located in the Southern Central Pyrenees in the Iberian Peninsula. The river experiences frequent floods, a characteristic that, together with the high connectivity between its network and the sediment sources, keeps sediment transport rates relatively high; instantaneous suspended sediment concentration occasionally attains 300 g l-1. The main sources of fine sediment are badland areas on marls (occupying less than 1% of the catchment area). The river flows into the Barasona Reservoir that experiences historical siltation problems. In order to quantify the suspended sediment transport in the Isabena basin, water and suspended sediment were monitored during the period 2005-2007. Discharge was sampled at the downstream end of the catchment. Suspended sediment transport was measured continuously at the same section by combining high-range turbidimeter readings and water samples (obtained regularly using and automatic sampler and manually -DH54 sampler- during floods). A total of 80 floods have been sampled during the study period. Total sediment yield has been estimated at 552,760 tones, representing an annual average of 184,253 t yr-1, and an averaged specific sediment yield (hereafter SSY) of 414 t km-2 yr-1. Most studies that showed a similar range of SSY are restricted to small mountainous catchments (

López-Tarazón, J. A.; Batalla, R. J.; Vericat, D.

2009-04-01

176

Fine-suspended sediment and water budgets for a large, seasonally dry tropical catchment: Burdekin River catchment, Queensland, Australia  

NASA Astrophysics Data System (ADS)

Burdekin River catchment (˜130,400 km2) is a seasonally dry tropical catchment located in north-east Queensland, Australia. It is the single largest source of suspended sediment to the Great Barrier Reef (GBR). Fine sediments are a threat to ecosystems on the GBR where they contribute to elevated turbidity (reduced light), sedimentation stress, and potential impacts from the associated nutrients. Suspended sediment data collected over a 5 year period were used to construct a catchment-wide sediment source and transport budget. The Bowen River tributary was identified as the major source of end-of-river suspended sediment export, yielding an average of 530 t km-2 yr-1 during the study period. Sediment trapping within a large reservoir (1.86 million ML) and the preferential transport of clays and fine silts downstream of the structure were also examined. The data reveal that the highest clay and fine silt loads—which are of most interest to environmental managers of the GBR—are not always sourced from areas that yield the largest total suspended sediment load (i.e., all size fractions). Our results demonstrate the importance of incorporating particle size into catchment sediment budget studies undertaken to inform management decisions to reduce downstream turbidity and sedimentation. Our data on sediment source, reservoir influence, and subcatchment and catchment yields will improve understandings of sediment dynamics in other tropical catchments, particularly those located in seasonally wet-dry tropical savannah/semiarid climates. The influence of climatic variability (e.g., drought/wetter periods) on annual sediment loads within large seasonally dry tropical catchments is also demonstrated by our data.

Bainbridge, Zoë T.; Lewis, Stephen E.; Smithers, Scott G.; Kuhnert, Petra M.; Henderson, Brent L.; Brodie, Jon E.

2014-11-01

177

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

EPA Science Inventory

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

178

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

179

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

SciTech Connect

'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 and subsequent desorption of such hydroxylated aromatics by soils and sediments. The principal objectives of this study are to investigate: (1) the role of abiotic/enzymatic coupling reactions on the immobilization of HAC''s; (2) the effects of environmental factors on such immobilization; and (3) preliminary engineering approaches utilizing enhanced abiotic/enzymatic coupling reactions to immobilize hydroxylated aromatics in-situ. Information gathered from the study will be useful in quantifying the behavior of this class of organic compounds in various subsurface contamination scenarios relevant to DOE facilities, and in specifying strategies for the selection and design of remediation technologies. Over the first two years of this three-year project, the authors have developed a significantly improved understanding of the mechanisms of hydroxylated aromatic compound sorption and immobilization by natural soils and sediments. Immobilization in this context is attributed to oxidative coupling of the hydroxylated aromatics subsequent to their sorption to a soil or sediment, and is quantified in terms of the amount of a sorbed target compound retained by a sorbent after a series of sequential water and solvent extractions. The presence of oxygen, metal oxides, and organic matter, all of which can potentially catalyze/facilitate the abiotic oxidative coupling of HAC''s, were investigated during these first two years. Three different HAC''s: phenol, trichlorophenol and o-cresol were included in the experimental program. Inorganic soil matrices were represented by a glacial wash sand (Wurtsmith sand) having very low organic content. Because the chemical nature of soil organic matter may potentially affect the extent of coupling or immobilization, sorbents having different organic matter compositions are being investigated. Two of the three studied to date are near-surface soils, characterized by geologically younger organic material (Fox Forest soil and Fox Grassland soil). The third sorbent is an older and diagenetically altered soil (Lachine Shale). Sorbent preparation, characterization and experimental protocol development were completed in the first year of the study while the second year of the project has focused primarily on experiments with natural systems, as planned. Preliminary work with engineered systems has been initiated earlier than scheduled in order to integrate and relate all aspects of the study.'

Weber, W.J. [Univ. of Michigan, Ann Arbor, MI (US); Bhandari, A. [Kansas State Univ., Manhattan, KS (US)

1998-06-01

180

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

181

Annual Report Name of Alumni Group  

E-print Network

Annual Report for _____________________________________ Name of Alumni Group Clemson Alumni ______________________________________ Signature ______________________________________ Date Annual reports are due to an Engagement Liaison by July 31, 2013 #12;ANNUAL REPORT OF ACTIVITIES Name of Event Brief Description Total # in Attendance

Duchowski, Andrew T.

182

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

183

Terrestrial Sediment and Nutrient Discharge, and Their Potential Influence on Coral Reefs, Puerto Rico  

NASA Astrophysics Data System (ADS)

Sediment and nutrient discharge to the insular shelf of Puerto Rico (18 degrees latitude), augmented by anthropogenic activity, is believed to have contributed to widespread degradation of coral reefs of Puerto Rico during the 20th century. Sediment deposition degrades coral reefs because it reduces the area of sea floor suitable for growth of new coral, diminishes the amount of light available for photosynthesis by symbiotic algae that live within individual coral animals, and in extreme cases, buries coral colonies. Land-use history and data from 30 water-discharge, 9 daily and 15 intermittent sediment-concentration, and 24 water-quality gaging stations were analyzed to investigate the timing and intensity of terrestrial sediment and nutrient discharge into coastal waters. Watersheds in Puerto Rico generally are small (10's to 100's of square km), channel gradients are steep, and stream valleys are deeply incised and narrow. Major storms are usually brief (<24 h) but intense such that the majority of the annual sediment discharge occurs in a few days. From 1960 through 2000 the highest mean daily discharge for a water year (October - September) accounted for 20 to 60 percent of the total annual sediment discharge. Major storms, with a return frequency of approximately a decade, were capable of discharging up to 30 times the median annual sediment-discharge volume. Prior to agricultural and industrial development, coastal waters are believed to have been relatively transparent, with strong currents and seasonal high-energy swells assisting corals in the removal of minor amounts of sediment deposited after storms. Land clearing and modification, first for agriculture and later for urban development, have increased sediment and nutrient influx to the coast during the 19th and 20th centuries. Although forest cover has increased to approximately 30 percent of the surface of Puerto Rico during the past 60 years, sediment eroded from hillslopes during the agricultural period is still being episodically transported from upland valleys to downstream floodplains and the coast. In response to better land management, the quality of water has improved significantly since the 1980s. Nitrogen and phosphorous concentrations in river waters are now well within regulatory limits, although current concentrations are as much as 10 times the estimated pre-settlement levels. Concentrations of pathogens also are improved but continue to be near or above regulatory limits. Unlike sediment discharge, which is episodic and intense, the discharge of river-borne nutrients and pathogens is a less intense but chronic stressor to coral reefs located near the mouths of rivers.

Larsen, M. C.; Webb, R. M.; Warne, A. G.

2004-12-01

184

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

USGS Publications Warehouse

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

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

2006-01-01

185

Sediment Problems and Sediment Management in Asian River Basins (Proceedings of the IAHS workshop, Hyderabad, India, September 2009). IAHS Publ., accepted  

E-print Network

1 Sediment Problems and Sediment Management in Asian River Basins (Proceedings of the IAHS workshop, Hyderabad, India, September 2009). IAHS Publ., accepted River sediment monitoring for baseline and change the river bed sediment and water body. Further downstream, annual inundation of agricultural clearings

Chappell, Nick A

186

Sediment Problems and Sediment Management in Asian River Basins (Proceedings of the Workshop held at Hyderabad, India, September 2009) (IAHS Publ. 349, 2011).  

E-print Network

Sediment Problems and Sediment Management in Asian River Basins (Proceedings of the Workshop held at Hyderabad, India, September 2009) (IAHS Publ. 349, 2011). 92 River sediment monitoring for baseline river in suspension to contaminate the river bed sediment and water body. Further downstream, annual

Chappell, Nick A

187

Sediment Problems and Sediment Management in Asian River Basins (Proceedings of the ICCE Workshop held at Hyderabad, India, September 2009). IAHS Publ. 349, 2011.  

E-print Network

1 Sediment Problems and Sediment Management in Asian River Basins (Proceedings of the ICCE Workshop held at Hyderabad, India, September 2009). IAHS Publ. 349, 2011. River sediment monitoring for baseline river in suspension to contaminate the river bed sediment and water body. Further downstream, annual

Chappell, Nick A

188

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

NASA Astrophysics Data System (ADS)

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

Estrany, J.; Garcia, C.

2012-04-01

189

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...

190

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

191

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

PubMed Central

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

192

Sediment Setback  

E-print Network

. Ultraviolet light, or sunlight, naturally kills bacteria; therefore, suspended sediment in the area's water is particularly problematic because of its ability to diminish the water's light absorption. Sediment can also spread absorbed hazardous chemicals... Sediment SetbackStory by Amanda Crawford Since 1942, Fort Hood has been home to theU.S. Army's III Mobile Armored Corps. It is the only U.S. military post able to station and train two armored divisions at once. At this base, troops execute...

Crawford, Amanda

2005-01-01

193

Mechanisms of flow through compressible porous beds in sedimentation, filtration, centrifugation, deliquoring, and ceramic processing. [Annual report], February 1, 1991--January 31, 1992  

SciTech Connect

The University of Houston research program is aimed at the specific area of solid/liquid separation including sedimentation, thickening, cake filtration, centrifugation, expression, washing, deep-bed filtration, screening, and membrane separation. Unification of the theoretical approaches to the various solid/liquid separation operations is the principle objective of the research. Exploring new aspects of basic separation mechanisms, verification of theory with experiment, development of laboratory procedures for obtaining data for design, optimizing operational methods, and transferring the results to industry are a part of the Houston program. New methodology developed in our program now permits an engineer or scientist to handle thickening, cake filtration, centrigual filtration, and expression in a unified manner. The same fundamental equations are simply adapted to the differing parameters and conditions related to the various modes of separation. As the system is flexible and adaptable to computational software, new developments can continually be added. Discussions of the various research projects in this report have been kept to a minimum and are principally qualitative. The length of the report would be excessive if each topic were covered in depth. Although the number of research topics may appear larger than one would expect, many are closely interconnected and reflect our philosophy of working in apparently diverse fields such as ceramics, mining, wastewater, food, chemical processing, and oil well operations.

Tiller, F.M.

1992-06-01

194

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

195

Intermediate-Scale Experiments to Evaluate Silt Fence Designs to Control Sediment Discharge from Highway  

E-print Network

.5 billion metric tons of sediment into streams and rivers annually Landphair et al. 1997 . SedimentIntermediate-Scale Experiments to Evaluate Silt Fence Designs to Control Sediment Discharge from Abstract: Soil erosion occurring at highway construction sites can contribute large amounts of sediment

Clement, Prabhakar

196

Research papers Rapid sediment removal from the Columbia River plume near field  

E-print Network

Research papers Rapid sediment removal from the Columbia River plume near field Daniel J. Nowacki a Keywords: River plumes Columbia River Sediment transport a b s t r a c t We compute rates of sediment to 20 billion metric tons of sediment delivered annually by rivers worldwide (Milliman and Syvitski

197

2001 annual report 2001 annual report  

E-print Network

2001 annual report 2001 annual report 2001 annual report 2001 annual report 2001 annual report 2001 annual report 2001 annual report 2001 annual reportelectrical & computer engineering 2001 annual report the university of new mexico department of 2001 annual report 2001 annual report 2001 annual report 2001 annual

New Mexico, University of

198

Effective discharge for suspended sediment transport of the Ganga River and its geomorphic implication  

NASA Astrophysics Data System (ADS)

Effective discharge (Qe) for suspended sediment transport in the alluvial reaches of the Ganga River in the western Ganga plains (WGP) has been computed using ‘analytical' and an alternative ‘magnitude-frequency' approach. Thirty years of mean monthly discharge data from various sites of the Ganga River have been assessed, and the abundance of discharge occurrence has been determined. Our analysis shows that less than 40% of the flow causes effective sediment transport in the Ganga, and this can be considered as the effective discharge for suspended sediment transport. Alternatively, 50% of the sediment load for all studied sites is moved by a discharge varying between 14 and 40% of the total discharge. Effective discharges calculated over the period of record are well below the bankfull discharges (Qb). A few events are close to the bankfull level, but with a high return period (RI > 40 years), and therefore, not effective to transport most of the available sediments. Our computation shows that the mean annual discharge (RI = 2.33 yrs) can transport only 0 to 10% of the total available sediments. The computation of effective discharge also provided important insights to understand the linkage between hydrology and channel morphology. Sediment storage and removal processes, which are reflected in sediment budget, cause changes in cross-sectional area/channel bathymetry at various sites but the channel margins are not affected. A high ratio of bankfull to effective discharge (Qb/Qe) forces the flow lines to be concentrated to the thalweg position and channels are incised. Our study also implies that incision and aggradation of the river valley during a relatively long period are caused by changes in effective discharge. We argue that the valley incision and filling episodes in the western Ganga plains at Late Quaternary timescales in response to monsoonal fluctuations were primarily affected by changes in the effective discharges of the rivers.

Roy, N. G.; Sinha, R.

2014-12-01

199

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

USGS Publications Warehouse

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

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

1998-01-01

200

An Investigation of Effective Discharge for Suspended Sediment by Level III Ecoregion  

NASA Astrophysics Data System (ADS)

The concept of dominant discharge in alluvial channels was first introduced by Wolman and Miller (1960). In their examination of magnitude and frequency of geomorphic forces, they proposed that the flow transporting the greatest amount of sediment and controlling channel form was not the highest magnitude discharge experienced by a river channel as commonly perceived, but in reality a relatively frequent event. This "effective discharge" can be calculated using flow and sediment-transport data to establish the increment of discharge that transports the largest fraction of the annual sediment load over a period of years. Because of the availability of suspended-sediment data, the dearth of bed-load data and the need to establish water-quality criteria for suspended sediment, this study focuses on the "effective discharge" for suspended sediment only. In the decades since Wolman and Miller's work, the term "dominant discharge" has been associated with two other flows: bankfull discharge, and flow of a given recurrence interval. Pickup and Warner (1976) state the average dominant discharge is the 1.58 year event on the annual flood series, although in other literature the recurrence interval is cited to generally fall between 1.0 and 2.5 years. Conversely, other authors refute that a flow of a universally applicable recurrence interval represents the effective discharge. However, the recent focus on river restoration and rehabilitation projects has meant magnitude-frequency analysis has become more widely applied for designing stable channels, and in many cases the 1.5 year flood has been considered equivalent to the bankfull and effective discharges. The purpose of this paper is to determine the effective discharge for suspended sediment in various ecoregions of the continental United States and to test whether the 1.5 year discharge is a reasonable estimate of this channel-forming flow. To date, the effective discharges for suspended sediment have been calculated for seven ecoregions: Coast Range (1) Sierra Nevada (5), Snake River Basin (12), Arizona-New Mexico Plateau (22), Flint Hills (28), Central Irregular Plains (40) and the Mississippi Valley Loess Plains (74). Mean daily flow data for a substantial period of record were divided into 33 logarithmic classes and the percentage occurrence of each of these was computed. The total annual suspended sediment transport was then calculated for each class, using suspended-sediment rating equations generated through regression of instantaneous discharge and suspended sediment concentration historic sample data. The geometric midpoint of the class transporting the greatest annual sediment load was considered to be the effective discharge. Results to date demonstrate in environments as diverse the Sierra Nevada Mountains and the Mississippi Valley Loess Plains, the effective discharge for suspended sediment is close to the 1.5 year flow. In the former ecoregion, the mean recurrence interval of suspended sediment effective discharge was 1.526 years. The eventual aim of this project is to calculate effective discharges for all 2929 USGS gaging stations with sufficient instantaneous suspended sediment and associated discharges measurements. These sites cover all 84 level III ecoregions, permitting environmental and geographic patterns of effective discharge recurrence interval. Calculations will be repeated using higher temporal resolution (15 minute) flow data.

Heins, A.; Simon, A.

2002-12-01

201

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

202

Cosmogenic nuclide-derived sediment budget of the Amazon basin  

NASA Astrophysics Data System (ADS)

Sediment gauging suggests that the annual sediment mass discharged into the main Amazon basin from the Andes and the cratonic shields is not in steady state with the mass discharged to the Atlantic Ocean. Here we use sediment production rates from cosmogenic 10Be in sediment to compare these with transport rates from river load gauging. About 1 million km2 or 95% of the total Andean area draining to the Amazon provide sediment to the central Amazon river with an averaged 10Be nuclide concentration of 5.0 +- 0.5x1e4 at/g(Qz). Average nuclide concentrations for Brazilian shield headwaters amount to 15.3 +- 1.2x1e4 at/g(Qz), and to 38.6 +- 2.4x1e4 at/g(Qz) for the Guyana shield headwaters, respectively. For the Andes, nuclide concentrations translate to an integrated Andean denudation rate of 0.35 ± 0.05 mm/yr. Sediment from the headwaters of the Brazilian and Guyana shields translate into very low denudation rates (0.02 and 0.01 mm/yr, respectively), as is expected for tectonically stable tropical highlands. These headwater 10Be nuclide concentrations and derived denudation rates can now be compared with those derived from central Amazon stream sediment including the main Amazon, which was sampled over ~1000 km from Manaus to Óbidos. Cosmogenic nuclide concentration analyses of several grain sizes (from 125 up to 800 µm) show large variations; we found that coarse-grained material records the nuclide signal of the cratonic shield areas, whereas the Andean signal is best represented by the fine sand fraction, which is preserved virtually unaltered over 1000s of km of sediment transport. In all central Amazon trunk stream samples and tributaries, the fine grain size fraction (125-250 µm) contains 10Be at 6.5 +- 1.2x1e4 at/g(Qz), which is similar to that of the Andean source areas. The integrated denudation rate from this fraction is 0.23 +- 0.04 mm/yr for the entire Amazon basin at Óbidos, which compares well with the mean Andean denudation rate of 0.35 +- 0.05 mm/yr. Coarse grain sizes (>500 µm) record the very low denudation rate of the cratonic shields. Given these low rates, the shields discharge only small amounts of sediment into the Amazon trunk stream. Multiplied with the area of the providing hinterland, we can use these erosion rates to calculate sediment mass budgets. The flux of sediment expected from cosmogenic nuclide-based denudation rates amounts to 540 Mt/yr at Óbidos. This flux compares to the total load of 1100 Mt/yr at Óbidos[1,2,3] as estimated from sediment gauging. This disparity is unexpected, as today at least 40% of the sediment discharged from the Andes is stored in floodplains[4]; a process not detected with cosmogenic 10Be. The longer denudation integration time scale of 8 kyr for cosmogenic nuclides possibly includes a period of drier climate than the wet conditions during the late Holocene, where a wetter modern climate possibly favors more rapid erosion in the Andes and more efficient sediment transport in the large rivers. 1 Gaillardet et al. (1997), Chemical Geology (142), 141-173. 2 Dunne et al. (1998), GSA Bulletin (110), 450-467. 3 Guyot et al. (2005), IAHS Publications (291), 1-8. 4 Guyot et al. (1996), IAHS Publications (236), 55-63.

Wittmann, Dr.; von Blanckenburg, Dr.; Guyot, Dr.; Maurice, Dr.; Kubik, Dr.

2009-04-01

203

Water Resources Center Annual Technical Report  

E-print Network

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

204

Institute of Water Resources Annual Technical Report  

E-print Network

Pollution, Surface Water, Water Quality Descriptors: Bacteria, Suspended Sediments, Water Quality Monitoring Pollution, Surface Water, WInstitute of Water Resources Annual Technical Report FY 2002 Introduction In fiscal year 2002

205

IMPACTS OF HUMAN ACTIVITIES ON THE SEDIMENT REGIME OF THE HANJIANG RIVER  

NASA Astrophysics Data System (ADS)

The Han River is the longest tributary of Yangtze River. It merges with the Yangtze at Wuhan city. It plays a critical role in promoting the socio-economic development of the Hanjiang River basin. With population increase and economic growth, the development of water resources and hydropower resources of the Hanjiang River has been intensified by dam building, and consequently the sediment regime of the Hanjiang River has been altered to some extent. To assess dam-induced alterations in the sediment regime of the Hanjiang River quantitatively, this paper selected three key hydrological stations as case study sites above and below the Danjiangkou reservoir respectively. The Danjiangkou reservoir is a seasonal-storage reservoir and was built in 1967. It is located at the end of the upper reach of the Hanjiang, and its catchment area accounts for 60% of the river basin total. The reservoir has a normal pool level of 157m and a capacity of 17.45 billion m3. It is also the water source of the central route of China’s South-North water transfer project. Currently the second-stage engineering works are underway with an aim of increasing the normal pool level to 170m and the storage capacity to 29.05 billion m3, and expected to be completed by 2010. Baihe station, above the Danjiangkou reservoir, is the upper controlling station for water and sediment discharges to the Danjiangkou reservoir, located at the upper reach of the Hanjiang River. Huangzhuang is located at the end point of the middle reach of the Hanjiang River, 223 km below the Danjiangkou reservoir. Xiantao, below the Danjiangkou, is the most downstream station on the Hanjiang River, and controls water and sediment discharges to the main stem of the Yangtze River from the Hanjiang River. The whole study period was divided into 2 subperiods by the year when the reservoirs started to store water. On the basis of 54-year long time series of daily sediment data from three stations, the alterations of their annual, seasonal, monthly and daily sediment load, and the relationships between water quantity and sediment load were analyzed and compared. The results revealed: the Danjiangkou reservoir imposed significant effects to the river sediment regime and the impacts varied with the distance between the target reservoir and the study site; deforestation resulted in an increase in annual, wet seasonal and dry seasonal sediment load; the trapping of sediment in reservoirs together with soil and water conservation caused a significant reduction in annual, seasonal, monthly and daily sediment load downstream; the reservoir operation mode of “retain high floods in wet seasons” altered the distribution of monthly and daily sediment load downstream, i.e. the percentages of sediment load in high flow months decreasing and the ones in low flow months increasing, and caused an reduction in the percentages of high daily sediment concentration and sediment load downstream; the relationship between water and sediment significantly changed. The output of this paper could provide reference for the assessment of the impacts of human activities on the long-term health and stability of the Hanjiang River ecosystem.

Wang, H.

2009-12-01

206

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

207

Aerobic respiration in pelagic marine sediments  

Microsoft Academic Search

Analyses for dissolved oxygen, nitrate and total CO 2 in the interstitial water have been combined with solid phase sediment analyses of carbon and nitrogen to calculate the rates of reaction and stoichiometry of decomposing organic matter in central Equatorial Pacific pelagic sediments. The diagenesis is dominated by aerobic respiration and nitrification. Organic carbon and total nitrogen decrease exponentially with

Varis Grundmanis; James W. Murray

1982-01-01

208

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

Karen Williams

209

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

E-print Network

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

Paris-Sud XI, Université de

210

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

NASA Astrophysics Data System (ADS)

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

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

2007-01-01

211

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

212

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

213

76 FR 69239 - Annual Retail Trade Survey  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2011-11-08

214

75 FR 63804 - Annual Retail Trade Survey  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2010-10-18

215

77 FR 64463 - Annual Retail Trade Survey  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2012-10-22

216

Yaquina Bay, Oregon, Intertidal Sediment Temperature Database, 1998 - 2006.  

EPA Science Inventory

Detailed, long term sediment temperature records were obtained and compiled in a database to determine the influence of daily, monthly, seasonal and annual temperature variation on eelgrass distribution across the intertidal habitat in Yaquina Bay, Oregon. Both currently and hi...

217

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

218

Linking suspended sediment transport metrics with fish functional traits in the Northwestern Great Plains (Invited)  

NASA Astrophysics Data System (ADS)

Loss of ecological integrity due to excessive suspended sediment in rivers and streams is a major cause of water quality impairment in the United States. Although 32 states have developed numeric criteria for turbidity or suspended solids, or both according to the USEPA (2006), criteria is typically written as a percent exceedance above background and what constitutes background is not well defined. Defining a background level is problematic considering suspended sediments and related turbidity levels change with flow stage and season, and limited scientific data exists on relationships between sediment exposure and biotic response. Current assessment protocols for development of sediment total maximum daily loads (TMDLs) lack a means to link temporally-variable sediment transport rates with specific losses of ecological functions as loads increase. This study, within the in Northwestern Great Plains Ecoregion, co-located 58 USGS gauging stations with existing flow and suspended sediment data, and fish data from federal and state agencies. Suspended sediment concentration (SSC) transport metrics were quantified into exceedance frequencies of a given magnitude, duration as the number of consecutive days a given concentration was equaled or exceeded, dosage as concentration x duration, and mean annual suspended sediment yields. A functional traits-based approach was used to correlate SSC transport metrics with site occurrences of 20 fish traits organized into four main groups: preferred rearing mesohabitat, trophic structure, feeding habits, and spawning behavior. Negative correlations between SSC metrics and trait occurrences were assumed to represent potential conditions for impairment, specifically identifying an ecological loss by functional trait. Potential impairment conditions were linked with presence of the following traits: habitat preferences for stream pool and river shallow waters; feeding generalists, omnivores, piscivores; and several spawning behaviors. Using these results, TMDL targets were proposed such as < 19 mg/l SSC and 1,500 mg/l-day dosage at the 95% recurrence frequency for feeding generalists and omnivores. In general, traits correlated with: 1) a broad range of SSC exceedance frequencies and flow stages, 2) exceedance frequencies near 90-95% occurring at moderate flow stages; and 3) exceedance frequencies near 0.01-10 % occurring during floods. Unstable channels were found to be greater in transported suspended sediment than stable channels over a range of concentration exceedance frequencies, and likely influence physical habitat quality. Pool-preference and gravel spawner traits were greater in stable channels than unstable channels. Overall, a functional traits-based approach utilizing concentration-duration-frequency characteristics of suspended sediment transport was successful in identifying potential “targets” for biological impairment due to excessive sediment, and will aid in developing sediment TMDLs.

Schwartz, J. S.; Simon, A.; Klimetz, L.

2009-12-01

219

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

NASA Astrophysics Data System (ADS)

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

Dubinski, I. M.

2012-12-01

220

Notes on sedimentation activities calendar year 1992  

USGS Publications Warehouse

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

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

1994-01-01

221

Notes on sedimentation activities calendar year 1991  

USGS Publications Warehouse

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

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

1992-01-01

222

Notes on sedimentation activities calendar year 1990  

USGS Publications Warehouse

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

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

1991-01-01

223

Dissolved and particulate carbohydrates in contrasting marine sediments  

Microsoft Academic Search

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 Cox). When these results are compared with results from other coastal sediments and a

D. J. BURDIGE; A Skoog; K. GARDNER

2000-01-01

224

Sedimental Reasons  

NSDL National Science Digital Library

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

225

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, Sandra M.; Bergamaschi, B.A.; Hernes, P.J.; Kavvas, M.L.

2011-01-01

226

Nitrogen Turnover in Drying Sediments of an Amazon Floodplain Lake  

Microsoft Academic Search

In the Amazon floodplain large areas are subject to annual cycles of drying and rewetting. The turnover of nitrogen in the periodically drying sediments is an important regulator of floodplain fertility. In the present study the transition of a lake sediment from flooded to dry conditions was studied with respect to microbial nitrogen turnover. Soil nitrogen pools, as well as

Matthias Koschorreck

2005-01-01

227

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

228

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

USGS Publications Warehouse

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

Hindall, S.M.

1991-01-01

229

The prediction of sediment yields from small blackland watersheds  

E-print Network

to predict sediment yields directly. These are the methods that fall into tha second category mentioned in the beginning paragraph of the literature reviom. Anderson (3) developed one such equation in shich he related the annual suspended sediment... using these variables and measured suspended sediment discharge. The six important prodictor variables mere: (1) relative rain area; (2) acres of mildfire per square mile of matershed area mithin the ten year poriod 10 prior to analysis; (3) acres...

Williams, Jimmy Ray

2012-06-07

230

76 FR 64894 - Annual Wholesale Trade Survey  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2011-10-19

231

78 FR 68023 - Annual Wholesale Trade Survey  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2013-11-13

232

Fremont Lake, Wyoming--some aspects of the inflow of water and sediment  

USGS Publications Warehouse

Fremont Lake is a large (20.6 sq km), deep lake (185 m) in western Wyoming. Average annual inflow of water is about 5.1 cu meters/sec, and this discharge is equaled or exceeded about 23% of the time. Annual instantaneous peak flows of Pine Creek usually exceed 30 cu m/sec and the 100-year flood is about 80 cu m/sec. About 800 tons of sediment are delivered to the lake annually; annual deposition of sediment in the northern lake area throughout the last 10,000 years about equals contemporary values of sediment inflow. Only small quantities of fine-gradient sediment are transported beyond the delta at the northern end of the lake. Current rates of deposition in the delta are about 1 to 3 mm/yr. Sediment in the delta generally is sand size; elsewhere in the lake, sediment generally is clay and silt size. (USGS)

Emmett, W.W.; Averett, R.C.

1989-01-01

233

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

234

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. ...

235

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

236

Erosion, transport and deposition of sediments by the tropical rivers of India  

Microsoft Academic Search

Some major tropical rivers of India — the Cauvery, Krishna and Godavari — were sampled to characterize their sediment transport. On the basis of our observations their sediment loads have been computed and compared with those of the major rivers of the world. Monthly and annual variations in sediment transport as a function of time and space have been observed.

P. VAIIH; V. SUBRAMANIAN

237

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

238

CAPS Annual 2010 Annual Report  

E-print Network

CAPS Annual 2010 1 Annual Report 2010 Centre for Astrophysics and Planetary Science School................................................,,,, 18 Miscellaneous Communications .................................... 22 Contents of Annual Report of Physical Sciences University of Kent http://astro.kent.ac.uk #12;CAPS Annual 2010 2 Contents Page Mission

Banaji,. Murad

239

Mercury Concentrations in Coastal Sediment from Younger Lagoon, Central California  

NASA Astrophysics Data System (ADS)

Younger Lagoon Reserve, located in northern Monterey Bay, is one of the few relatively undisturbed wetlands that remain along the Central Coast of California. This lagoon system provides protected habitat for more than 100 bird species and for populations of fish, mammals, and invertebrates. Total mercury (HgT) concentrations in water within Younger Lagoon appear to vary with rainfall conditions and range from about 5-15 pM. These concentrations are similar to HgT in water from six nearby lagoon systems. However, Younger Lagoon contains elevated concentrations of dissolved organic carbon (~1 mM) and monomethylmercury (MMHg, ~1 pM) relative to our comparison lagoon sites (DOC < 0.5 mM and MMHg < 0.5 pM). We attribute Younger Lagoon's high DOC and MMHg to its restricted connection to the ocean and minor riverine contribution. Coastal lagoons in this region typically form at the mouth of streams. They behave as small estuaries during the wet season when surface water discharge keeps the mouth of the stream open to the ocean, and then transition into lagoons in the dry season when a sand berm develops and effectively cuts off surface water exchange. At Younger Lagoon, the sand berm remains intact throughout the year, breaching only during particularly high tides or intense rain events. Therefore, the lagoon's connection to nearshore seawater is primarily via surface water - groundwater interaction through the sand berm. Because Younger Lagoon is largely isolated from a surface water connection with the ocean, runoff from upgradient urban and agricultural land has an enhanced impact on water (and presumably sediment) quality. As a result, the lagoon is eutrophic and experiences annual algal blooms. Groundwater surveys suggest surface water, groundwater, and coastal seawater are hydraulically connected at Younger Lagoon, and mixing among these water masses appears to influence water geochemistry. To date, no chemical analyses have been conducted on sediment from Younger Lagoon. To address this data gap we collected sediment samples during a February 2013 field campaign. One set of sediment samples is from the bottom of the lagoon along a transect perpendicular to the shoreline and another set is from an approximately 1 m depth profile on the lagoon side of the sand berm (depth of the groundwater table at the time of collection). These samples are being analyzed for HgT, MMHg, and total organic carbon (TOC) and will provide a first glimpse into the distribution of mercury species and organic carbon in sediments from the Younger Lagoon Reserve. We will also collect and analyze sediment samples from another lagoon site with comparable watershed characteristics.

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

2013-12-01

240

U and Th speciation in river sediments  

Microsoft Academic Search

A study of the distribution of some natural radionuclides in different chemical fractions of river bottom sediments has been carried out. The study has shown that the majority of the total U in sediments is located in the non-residual fractions, while Th is more likely to be present in the residual ones. This difference between U and Th reflects largely

A. Martínez-Aguirre; M. Garcia-León; M. Ivanovich

1995-01-01

241

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

USGS Publications Warehouse

This paper presents a broad but undetailed picture of fluvial sediments in streams, reservoirs, and lakes and includes a discussion of the processes involved in the movement of sediment by flowing water. Sediment is fragmental material that originates from the chemical or physical disintegration of rocks. The disintegration products may have many different shapes and may range in size from large boulders to colloidal particles. In general, they retain about the same mineral composition as the parent rocks. Rock fragments become fluvial sediment when they are entrained in a stream of water. The entrainment may occur as sheet erosion from land surfaces, particularly for the fine particles, or as channel erosion after the surface runoff has accumulated in streams. Fluvial sediments move in streams as bedload (particles moving within a few particle diameters of the streambed) or as suspended sediment in the turbulent flow. The discharge of bedload varies with several factors, which may include particle size and a type of effective shear on the surface of the streambed. The discharge of suspended sediment depends partly on concentration of moving sediment near the streambed and hence on discharge of bedload. However, the concentration of fine sediment near the streambed varies widely, even for equal flows, and, therefore, the discharge of fine sediment normally cannot be computed theoretically. The discharge of suspended sediment also depends on velocity, turbulence, depth of flow, and fall velocity of the particles. In general, the coarse sediment transported by a stream moves intermittently and is discharged at a rate that depends on properties of the flow and of the sediment. If an ample supply of coarse sediment is available at the surface of the streambed, the discharge of the coarse sediment, such as sand, can be roughly computed from properties of the available sediment and of the flow. On the other hand, much of the fine sediment in a stream usually moves nearly continuously at about the velocity of the flow, and even low flows can transport large amounts of fine sediment. Hence, the discharge of fine sediments, being largely dependent on the availability of fine sediment upstream rather than on the properties of the sediment and of the flow at a cross section, can seldom be computed from properties, other than concentrations based directly on samples, that can be observed at the cross section. Sediment particles continually change their positions in the flow; some fall to the streambed, and others are removed from the bed. Sediment deposits form locally or over large areas if the volume rate at which particles settle to the bed exceeds the volume rate at which particles are removed from the bed. In general, large particles are deposited more readily than small particles, whether the point of deposition is behind a rock, on a flood plain, within a stream channel, or at the entrance to a reservoir, a lake, or the ocean. Most samplers used for sediment observations collect a water-sediment mixture from the water surface to within a few tenths of a foot of the streambed. They thus sample most of the suspended sediment, especially if the flow is deep or if the sediment is mostly fine; but they exclude the bedload and some of the suspended sediment in a layer near the streambed where the suspended-sediment concentrations are highest. Measured sediment discharges are usually based on concentrations that are averages of several individual sediment samples for a cross section. If enough average concentrations for a cross section have been determined, the measured sediment discharge can be computed by interpolating sediment concentrations between sampling times. If only occasional samples were collected, an average relation between sediment discharge and flow can be used with a flow-duration curve to compute roughly the average or the total sediment discharges for any periods of time for which the flow-duration c

Colby, B.R.

1963-01-01

242

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, L.E., Jr.

2000-01-01

243

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

244

Anthropogenic sediment resuspension mechanisms in a shallow microtidal estuary  

USGS Publications Warehouse

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

Schoellhamer, D.H.

1996-01-01

245

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

USGS Publications Warehouse

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

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

2009-01-01

246

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

247

Water and sediment transport modeling of a large temporary river basin in Greece.  

PubMed

The objective of this research was to study the spatial distribution of runoff and sediment transport in a large Mediterranean watershed (Evrotas River Basin) consisting of temporary flow tributaries and high mountain areas and springs by focusing on the collection and use of a variety of data to constrain the model parameters and characterize hydrologic and geophysical processes at various scales. Both monthly and daily discharge data (2004-2011) and monthly sediment concentration data (2010-2011) from an extended monitoring network of 8 sites were used to calibrate and validate the Soil and Water Assessment Tool (SWAT) model. In addition flow desiccation maps showing wet and dry aquatic states obtained during a dry year were used to calibrate the simulation of low flows. Annual measurements of sediment accumulation in two reaches were used to further calibrate the sediment simulation. Model simulation of hydrology and sediment transport was in good agreement with field observations as indicated by a variety of statistical measures used to evaluate the goodness of fit. A water balance was constructed using a 12year long (2000-2011) simulation. The average precipitation of the basin for this period was estimated to be 903mmyr(-1). The actual evapotranspiration was 46.9% (424mmyr(-1)), and the total water yield was 13.4% (121mmyr(-1)). The remaining 33.4% (302mmyr(-1)) was the amount of water that was lost through the deep groundwater of Taygetos and Parnonas Mountains to areas outside the watershed and for drinking water demands (6.3%). The results suggest that the catchment has on average significant water surplus to cover drinking water and irrigation demands. However, the situation is different during the dry years, where the majority of the reaches (85% of the river network are perennial and temporary) completely dry up as a result of the limited rainfall and the substantial water abstraction for irrigation purposes. There is a large variability in the sediment yield within the catchment with the highest annual sediment yield (3.5tha(-1)yr(-1)) to be generated from the western part of the watershed. The developed methodology facilitated the simulation of hydrology and sediment transport of the catchment providing consistent results and suggesting its usefulness as a tool for temporary rivers management. PMID:25497675

Gamvroudis, C; Nikolaidis, N P; Tzoraki, O; Papadoulakis, V; Karalemas, N

2015-03-01

248

Elwha River Restoration: Sediment Management  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

249

Sediment deposition and selected water-quality characteristics in Cedar Lake and Lake Olathe, Northeast Kansas, 2000  

USGS Publications Warehouse

The Lake Olathe watershed, located in northeast Kansas, was investigated using bathymetric survey data and reservoir bottom-sediment cores to determine sediment deposition, water-quality trends, and transport of nutrients (phosphorus and nitrogen species), selected trace elements, selected pesticides, and diatoms as indicators of eutrophic (organic-enriched and depleted oxygen supply) conditions. To determine sediment deposition and loads, bathymetric data from Cedar Lake and Lake Olathe, both located in the Lake Olathe watershed, were collected in 2000 and compared to historical topographic data collected when the lakes were built. Approximately 338 acre-feet of sediment deposition has occurred in Cedar Lake since dam closure in 1938, and 317 acre-feet has occurred at Lake Olathe since 1956. Mean annual sediment deposition was 5.45 acre-feet per year (0.89 acre-feet per year per square mile) for Cedar Lake and 7.0 acre-feet per year (0.42 acre-feet per year per square mile) for Lake Olathe. Mean annual sediment loads for the two reservoirs were 9.6 million pounds per year for Cedar Lake and 12.6 million pounds per year for Lake Olathe. Mean concentrations of total phosphorus in bottom-sediment samples from Cedar Lake ranged from 1,370 to 1,810 milligrams per kilogram, and concentrations in bottom-sediment samples from Lake Olathe ranged from 588 to 1,030 milligrams per kilogram. The implication of large total phosphorus concentrations in the bottom sediment of Cedar Lake is that inflow into Cedar Lake is rich in phosphorus and that adverse water-quality conditions could affect water quality in downstream Lake Olathe through discharge of water from Cedar Lake to Lake Olathe via Cedar Creek. Mean annual phosphorus loads transported from the Lake Olathe watershed were estimated to be 14,700 pounds per year for Cedar Lake and 9,720 pounds per year for Lake Olathe. The mean annual phosphorus yields were estimated to be 3.74 pounds per acre per year for Cedar Lake and 0.91 pound per acre per year for Lake Olathe. Phosphorus yields in the Cedar Lake watershed were largest of the six Kansas impoundment watersheds recently studied. Concentrations of total ammonia plus organic nitrogen as nitrogen in bottom sediment increased from upstream to downstream in both Cedar Lake and Lake Olathe. Mean concentrations of total ammonia plus organic nitrogen as nitrogen (N) ranged from 2,000 to 2,700 milligrams per kilogram in bottom-sediment samples from Cedar Lake and from 1,300 to 2,700 milligrams per kilogram in samples from Lake Olathe. There was no statistical significance between total ammonia plus organic nitrogen as nitrogen and depth of bottom sediment. Concentrations of six trace elements in bottom sediment from Cedar Lake and Lake Olathe (arsenic, chromium, copper, lead, nickel, and zinc) exceeded the U.S. Environmental Protection Agency Threshold Effects Levels (TELs) sediment-quality guidelines for aquatic organisms in sediment except for one lead concentration. Probable Effects Levels (PELs) for trace elements, however, were not exceeded at either lake. Organochlorine and organophosphate insecticides were not detected in bottom-sediment samples from either Cedar Lake or Lake Olathe, but the acetanilide herbicides alachlor and metolachlor were detected in sediment from both lakes. The U.S. Environmental Protection Agency has not proposed TEL or PEL guideline concentrations for bottom sediment for any of the organophosphate, acetanilide, or triazine pesticides. The diatoms (microscopic, single-celled organisms) Cyclotella bodanica, an indicator of low organic-enriched water, and Cyclotella meneghiniana, an indicator of organic-enriched water, were both present in bottom sediment from Lake Olathe. The presence of both of these diatoms suggests varying periods of low and high eutrophication in Lake Olathe from 1956 to 2000. The concentrations of two species in bottom sediment from Cedar Lake, Aulacoseira cf alpigena and Cyclotella meneg

Mau, D.P.

2002-01-01

250

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. PMID:16346332

Smith, Richard L.; Oremland, Ronald S.

1983-01-01

251

Sedimentation rate determination by radionuclides mass balances  

NASA Astrophysics Data System (ADS)

In the past, uranium mining activity took place in the area around Limoges, France. Even nowadays, this activity results in an increase in the input and availability of radionuclides in aquifer reservoirs, making of this area a suitable site to better understand the behaviour of radionuclides in the surficial environment. Water was sampled monthly over the entire year 2001 in a brook that collects mine water and in a lake fed by this brook. Samples were filtered through 0.45?m filters to remove particles. Activities of 238U, 226Ra, 210Pb, 228Th and 228Ra were measured on particulate (>0.45?m), dissolved (<0.45?m) and total (unfiltered) fractions by gamma spectrometry in the well of a high efficiency, low background, germanium detector settled in an underground laboratory, protected from cosmic rays by 1700 m of rocks (LSM, CNRS-CEA, French Alps). Activities measured in particulate and dissolved fractions were summed and compared to the one measured in unfiltered water to test the filtration yield. No significant loss or contamination were detected. In the brook water, 70% of 238U, 60% of 226Ra and 80% of 210Pb are associated with particles. Activities associated with particles decrease drastically along with the velocity of current when the stream enters the lake. An annual mass balance of radionuclides carried by particles from the stream to the lake was used to determine the sedimentation rate in the lake. The flux of particles deduced from mass balance calculations based on five isotopes corresponds to the thickness of sediment accumulated since the creation of this artificial lake (that is, 1976). This study emphasises the usefulness of radionuclides as tracers for environmental investigations.

Cazala, C.; Reyss, J. L.; Decossas, J. L.; Royer, A.

2003-04-01

252

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

253

Importance of elemental mercury in lake sediments.  

PubMed

Mercury (Hg) redox changes in sediments are poorly studied and understood, even though they potentially control Hg availability for methylation and can alter sediment-water Hg exchange. Elemental Hg (Hg(0)) concentrations in sediments of two Canadian Shield lakes were assessed by thermodesorption. Hg(0) concentrations in sediments varied between 6.3 and 60.3 pg g(-1) (wet weight) which represented 7.4-28.4% of total mercury (HgT) concentration. Hg(0) concentrations were similar in both lakes. Hg(0) was rapidly adsorbed on sediments in controlled adsorption experiments and surface sediments sampled in summer had a stronger affinity for Hg(0) than deeper sediments and sediments sampled in fall. This adsorption was positively correlated to organic matter content and negatively related to particle grain size, pH and oxygen concentration in overlying water. This study demonstrates that Hg(0) is a prevalent species in sediments, but not in porewater, because of the high sorptive capacity of sediments towards Hg(0). Its potential availability towards Hg methylating bacteria remains to be determined. PMID:19091379

Bouffard, Ariane; Amyot, Marc

2009-02-01

254

Contaminated Sediments in Water  

MedlinePLUS

... Contact Us Water: Contaminated Sediments You are here: Water Pollution Prevention & Control Sediments Contaminated Sediments in Water Contaminated ... Water Education & Training Grants & Funding Laws & Regulations Our Waters Pollution Prevention & Control Applications & Databases Low Impact Development Impaired ...

255

Mercury Concentration and Monomethylmercury Production in Sediment: Effect of Dredged Sediment Reuse on Bioconcentration for Ragworms  

Microsoft Academic Search

The effect of dredged sediment reuse on the production and bioconcentration of monomethylmercury (MMHg) was investigated by\\u000a examining sediments and ragworms found in dredge material banks and surrounding sites in the Venice Lagoon, Italy. Total Hg\\u000a concentrations in the surface 20 cm of sediments were higher in the banks than in the surrounding sites, but MMHg concentrations\\u000a were similar, which suggests

Seunghee Han; Magali Porrachia; Elisa Volpato; Joris Gieskes; Dimitri D. Deheyn

2011-01-01

256

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

257

TOTAL Full-TOTAL Full-  

E-print Network

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Portman, Douglas

258

Climate and environmental changes over the past 150 years inferred from the sediments of Chaiwopu Lake, central Tianshan Mountains, northwest China  

NASA Astrophysics Data System (ADS)

We used a 55-cm sediment core from shallow Chaiwopu Lake in the central Tianshan Mountains of Xinjiang, northwest China, to investigate climate and environmental changes in this arid region over the past ~150 years. The core was dated using 137Cs. We compared temporal changes in several sediment variables with recent meteorological and tree-ring records. Organic matter had a positive correlation with the Palmer Drought Severity Index in the central Tianshan Mountains, and the ?13C of organic matter had a positive correlation with regional temperature. We applied constrained incremental sum-of-squares cluster analysis to element concentrations in the core and identified three distinct zones: (1) 55-46 cm, ~1860-1910, (2) 46-26 cm, ~1910-1952, and (3) 26-0 cm, 1952-present. Between 1880 and 1910 AD, following the Little Ice Age (LIA), the sediment environment was relatively stable, climate was cold and dry, and the lake water displayed high salinity, in contrast to conditions during the LIA. During the LIA, westerlies carried more water vapor into Central Asia when the North Atlantic Oscillation was in a negative phase, and encountered the enhanced Siberia High, which probably led to increased precipitation. In the period 1910-1950 AD, the lake was shallow and the regional climate was unstable, with high temperatures and humidity. In the last ~15-20 years, human activities caused an increase in sediment magnetic susceptibility, and heavy metal and total phosphorus concentrations in the sediment were substantially enriched. Mean annual temperature displays a warming trend over the past 50 years, and the lowest temperature was observed in the 1950s. There has been an increase in annual total precipitation since the 1990s. The combined influences of climate and human activity on the lake environment during this period were faithfully recorded in sediments of Chaiwopu Lake. This study provides a scientific basis for environmental management and protection.

Ma, Long; Wu, Jinglu; Abuduwaili, Jilili

2013-04-01

259

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

USGS Publications Warehouse

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

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

2012-01-01

260

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. PMID:21890672

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

2011-01-01

261

Turbidity-based sediment monitoring in northern Thailand: Hysteresis, variability, and uncertainty  

NASA Astrophysics Data System (ADS)

Annual total suspended solid (TSS) loads in the Mae Sa Catchment in northern Thailand, determined with an automated, turbidity-based monitoring approach, were approximately 62,000, 33,000, and 14,000 Mg during the three years of observation. These loads were equivalent to basin yields of 839 (603-1170), 445 (217-462), and 192 (108-222) Mg km-2 for the 74.16-km2 catchment during 2006, 2007, and 2008, respectively. The yearly uncertainty ranges indicate our loads may be underestimated by 38-43% or overestimated by 28-33%. In determining the annual loads, discharge (Q) and turbidity (T) values were compared against 333 hand-sampled total suspended solid concentrations (TSS) measured during 18 runoff events and other flow conditions across the three-year period. Annual rainfall varied from 1632 to 1934 mm; and catchment runoff coefficients (annual runoff/annual rainfall) ranged from 0.25 to 0.41. Measured TSS ranged from 8 to 15,900 mg l-1; the low value was associated with dry-season base flow; the latter, a wet-season storm. Storm size and location played an important role in producing clockwise, anticlockwise, and complex hysteresis in the Q-TSS relationship. Turbidity alone was a good estimator for turbidity ranges of roughly 10-2800 NTU (or concentrations approximately 25-4000 mg l-1). However, owing to hysteresis and high sediment concentrations that surpass the detection limits of the turbidity sensor during many annual storms, TSS was estimated best using a complex multiple regression equation based on high/low ranges of turbidity and Q as independent variables. Turbidity was not a good predictor of TSS fractions >2000 ?m. Hysteresis in the monthly Q-TSS relationship was generally clockwise over the course of the monsoon season, but infrequent large dry-season storms disrupted the pattern in some years. The large decrease in annual loads during the study was believed to be related to depletion of fine sediment delivered to the stream by several landslides occurring the year prior to the study. The study indicated the importance of monitoring Q and turbidity at fine resolutions (e.g., sub-hourly) to capture the TSS dynamics and to make accurate load estimations in this flashy headwater stream where hysteresis in the Q-TSS signature varied at several time scales.

Ziegler, Alan D.; Benner, Shawn G.; Tantasirin, Chatchai; Wood, Spencer H.; Sutherland, Ross A.; Sidle, Roy C.; Jachowski, Nicholas; Nullet, Mike A.; Xi, Lu Xi; Snidvongs, Anond; Giambelluca, Thomas W.; Fox, Jefferson M.

2014-11-01

262

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

USGS Publications Warehouse

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

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

2001-01-01

263

Development of a reference artificial sediment for chemical testing adapted to the MELA sediment contact assay.  

PubMed

Most persistent organic pollutants, due to their hydrophobic properties, accumulate in aquatic sediments and represent a high risk for sediment quality. To assess the toxicity of hydrophobic pollutants, a novel approach was recently proposed as an alternative to replace, refine and reduce animal experimentation: the medaka embryo-larval sediment contact assay (MELAc). This assay is performed with Japanese medaka embryos incubated on a natural sediment spiked with the compound being tested. With the aim of improving this assay, our study developed a reference exposure protocol with an artificial sediment specifically designed to limit natural sediment composition uncertainties and preparation variability. The optimum composition of the new artificial sediment was tested using a model polycyclic aromatic hydrocarbon (PAH), fluoranthene. The sediment was then validated with two other model PAHs, benz[a]anthracene and benzo[a]pyrene. Various developmental end points were recorded, including survival, embryonic heartbeat, hatching delay, hatching success, larval biometry and abnormalities. The final artificial sediment composition was set at 2.5 % dry weight (dw) Sphagnum peat, 5 % dw kaolin clay and 92.5 % dw silica of 0.2- to 0.5-mm grain size. In contrast with natural sediments, the chemical components of this artificial matrix are fully defined and readily identifiable. It is totally safe for fish embryos and presents relatively high sorption capacities for hydrophobic compounds. Studies with other hydrophobic and metallic contaminants and mixtures should be performed to further validate this artificial sediment. PMID:24526399

Le Bihanic, Florane; Perrichon, Prescilla; Landi, Laure; Clérandeau, Christelle; Le Menach, Karyn; Budzinski, Hélène; Cousin, Xavier; Cachot, Jérôme

2014-12-01

264

The Ribagorda sand gully (east-central Spain): Sediment yield and human-induced origin  

NASA Astrophysics Data System (ADS)

Gullies are developed under different climatic conditions and lithologies; however, those formed on sands have been scarcely described. This paper reports the study of the Ribagorda sand gully, 2.57 ha in area (east-central Spain). The main objectives were to characterize and quantify its geomorphic dynamics and to trace its origin. We described the landforms of the gully and measured the surface strength of the sand. We monitored, for six years, the filling of the storage areas of three check dams built downstream from the gully, and related it with rainfall characteristics. We also described the nature of the sediments trapped by the dams and estimated the amount of sediment eroded since the gully formation. Finally, we consulted historical records and maps to determine past land uses and transformations that may have affected the origin of the gully. The study shows a high diversity of landforms, denoting active processes, consistent with a measured mean annual sediment yield of 114 Mg ha- 1 yr- 1. A statistically significant relationship exists between the mass of sediment (Mg) and: 1) the total rainfall (mm) (P = 0.0007) or 2) the analysed rainfall intensities. Among five identified facies in the sedimentary wedge, the sandy ones are predominant. The total amount of sediment eroded by the Ribagorda gully since its origin was 962,800 Mg. The results are unequivocal signs of an intense geomorphic activity within the gully, with an alluvial-fan type deposition in the dams. We interpret that the Ribagorda gully was initiated by deforestation after the 13th century, when forests began to be intensively logged, and before the 18th century, when the gully was first indirectly described in print. The age, origin, evolution and dynamics of this gully indicate that this landscape is currently evolving towards a new steady state, after human disturbances over centuries. Given the gully evolution and local extent, we suggest that no correction measures are needed for its management.

Martín-Moreno, C.; Fidalgo Hijano, C.; Martín Duque, J. F.; González Martín, J. A.; Zapico Alonso, I.; Laronne, J. B.

2014-11-01

265

A century-scale record of the preservation of chlorophyll and its transformation products in anoxic sediments  

NASA Astrophysics Data System (ADS)

We have determined the chlorophyll pigment composition by liquid chromatography (LC) and LC/MS/MS in a 1.45-m long freeze core, representing 157 years of annually varved sedimentation, from Saanich Inlet, B.C, Canada. We investigated the very early diagenetic processes of chlorophyll a alteration in these anoxic sediments and the possible implications for palaeoproductivity studies. Excellent preservation of pigments is indicated by high total pigment concentrations, and the presence of labile compounds such as chlorophyllide a. The lack of systematic down core changes in both the total pigment concentration and the chlorin composition indicates that no detectable alteration of the pigment composition has occurred during the past 157 years. The sedimentary pigment composition is the result of processes occurring in the water column, or within few months after deposition. Chlorophyll derivatives corresponding to different diagenetic processes have distinct down core profiles. Profiles of compounds related to grazing activity steryl pyrophaeophorbide esters (SPE) and pyrophaeophytin a, are very similar. In contrast, dephytylated compounds (chlorophyllide a and phaeophorbide a), which are related to chlorophyllase activity during the degradation of ungrazed diatom cells, show an independent pattern. Quantifying pigment composition in Saanich Inlet sediments can help constrain processes regarding the transport of algal pigments to the sediments.

Villanueva, Joan; Hastings, David W.

2000-07-01

266

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

267

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

268

Sediment yields from unit-source semi-arid watersheds at Walnut Gulch 1893  

Technology Transfer Automated Retrieval System (TEKTRAN)

This study reports sediment yields from seven small (0.18 to 5.42 ha) watersheds in southern Arizona measured from 1995 to 2005. Sediment concentrations and total event sediment yields were related to storm-runoff characteristics, and statistical relationships were developed to estimate sediment yi...

269

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

270

Notes on sedimentation activities calendar year 1987  

USGS Publications Warehouse

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

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

1988-01-01

271

Notes on sedimentation activities calendar year 1984  

USGS Publications Warehouse

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

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

1985-01-01

272

Notes on sedimentation activities calendar year 1988  

USGS Publications Warehouse

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

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

1989-01-01

273

Notes on sedimentation activities calendar year 1989  

USGS Publications Warehouse

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

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

1990-01-01

274

Notes on sedimentation activities calendar year 1985  

USGS Publications Warehouse

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

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

1986-01-01

275

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

276

Sediment characteristics of Tennessee streams and reservoirs  

USGS Publications Warehouse

Measured suspended-sediment data and reservoir sedimentation data have been analyzed to determine sediment yields and transport characteristics of Tennessee streams. Measured suspended-sediment is mostly silt and clay size material even in the sand-bed channels of western Tennessee. Unmeasured load accounts for less than 10 percent of the total sediment load in western Tennessee. Unmeasured load in middle and eastern Tennessee streams is believed to be only a small percentage of total load because bed material is generally coarse and quite variable. Sediment of total load because bed material is generally coarse and quite variable. Sediment yields for middle and eastern Tennessee basins generally are less than 800 tons per square mile per year ((tons/mi2)/yr), however, highly disturbed basins can have yields from 1,000 to 3,000 (tons/mi2)/yr. Yields for the heavily agricultural and channelized basins of western Tennessee generally range from 700 to 1,000 (tons/mi2)/yr. Yields for the Hatchie River in western Tennessee are less than 200 (tons/mi2)/yr reflecting the lack of floodplain agriculture and channelization. (USGS)

Trimble, Stanley W.; Carey, William P.

1984-01-01

277

Benthic respiration measured by total carbonate production  

Microsoft Academic Search

Abstract The suitability of total carbonate production,instead of oxygen consumption,as a measure,of benthic respiration has been investigated. In situ fluxes of total carbonate, oxygen, calcium, total alkalinity, nutrients, and sulfide across the sediment-water interface were measured in diver- operated benthic flux chambers. Two chambers,were run in parallel to test the influence of oxygen and pH levels on total carbonate production.

LEIF G. ANDERSON; PER O. J. HALL; ÅKE IVERFELDT; MICHIEL M. RUTGERS VAN DER LOEFF; BJØRN SUNDBY; STIG F. G. WESTERLUND

1986-01-01

278

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

279

Suspended sediment and carbonate transport in the Yukon River Basin, Alaska: Fluxes and potential future responses to climate  

E-print Network

Suspended sediment and carbonate transport in the Yukon River Basin, Alaska: Fluxes and potential , respectively, with 50% of the suspended sediment load originating in the Tanana River Basin and 88% of the carbonate load originating in the White River Basin. About half the annual suspended sediment export

280

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

281

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

282

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

E-print Network

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

Hall, Sharon J.

283

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

USGS Publications Warehouse

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

Payne, G.A.

1994-01-01

284

Availability of organic chemicals for biodegradation in settled bottom sediments.  

PubMed

Biodegradation rates for dodecyltrimethylammonium chloride (TMAC), a quaternary ammonium compound, and phenol were measured in settled sediments to determine if adsorbed chemicals were directly available for biodegradation by sediment-associated bacteria. In settled sediment cores, biodegradation rates for TMAC, which is charged at environmental pH, was a function of the amount of unadsorbed chemical; adsorbed material was not directly degraded by the sediment-associated bacteria. However, the rate of biodegradation of adsorbed phenol, a relatively hydrophobic and neutral chemical, was apparently a function of the total concentration of material present, suggesting that at least a fraction of the adsorbed material was directly degraded. These results indicate that chemical structure and, possibly, the mechanism of adsorption may influence biodegradation in sediments. Studies on TMAC biodegradation in completely mixed sediment/water slurries (up to 10 g/liter sediment) showed that TMAC biodegradation in slurries differed from that in settled sediments. Biodegradation in slurries was a function of the total amount of material present, both adsorbed and unadsorbed. These results suggest that biodegradation in settled sediments may be influenced by high concentrations of sediment present and/or the lack of mixing. Thus mixed, low-sediment-level slurries may not be realistic surrogates for modeling biodegradation processes in settled bottom sediments. PMID:3359954

Shimp, R J; Young, R L

1988-02-01

285

Sediment delivery by ungaged tributaries of the Colorado River in Grand Canyon, Arizona  

USGS Publications Warehouse

Sediment input to the Colorado River in Grand Canyon, Arizona, is a valuable resource required to sustain both terrestrial and aquatic ecosystems. A total of 768 ungaged tributaries deliver sediment to the river between Glen Canyon Dam and the Grand Wash Cliffs (river miles -15 to 276). The 32 tributaries between the dam and Lee's Ferry produce only streamflow floods, whereas 736 tributaries in Grand Canyon produce streamflow floods and debris flows. We used three techniques to estimate annual streamflow sediment yield from ungaged tributaries to the Colorado River. For the Glen Canyon and Marble Canyon reaches (river miles -15 to 61.5), respectively, these techniques indicate that 0.065.106 and 0.610.106 Mg/yr (0.68.106 Mg/yr of total sediment) enters the river. This amount is 20 percent of the sediment yield of the Paria River, the only gaged tributary in this reach and a major sediment contributor to the Colorado River. The amount of sand delivered ranges from 0.10.106 to 0.51.106 Mg/yr, depending on the sand content of streamflow sediment. Sand delivered in Glen Canyon is notably coarser (D50 = 0.24 mm) than sand in other reaches (D50 = 0.15 mm). A relation is given for possible variation of this sediment delivery with climate. Debris flows transport poorly-sorted sediment onto debris fans in the Colorado River. In the pre-dam era, debris fans were completely reworked during Colorado River floods, liberating all fine-grained sediment to the river; in the post-dam river on average only 25 percent of debris-fan volume is reworked, leading to storage of sand in the matrix of debris fans. We develop a sediment-yield model for debris flows that uses a logistic-regression model of debris-flow frequency in Grand Canyon, a regression model of debris-flow volumes, particle- size distributions of intact debris-flow deposits, and debris-fan reworking. On average, debris flows deliver between 0.14.106 and 0.30.106 Mg/yr of sediment to debris fans throughout Grand Canyon. Together, streamflow and debris flow deliver nearly 2.8.106 Mg/yr of sediment to the Colorado River from ungaged tributaries. In the post-dam era of minimal debris-fan reworking, the combined sand delivery rate in Glen and Marble Canyons averages 0.32.106 Mg/yr, which is 20 percent of the sand delivery of the Paria River and double the 0.17.106 Mg/yr of sand estimated for this reach in the 1995 environmental impact statement for operation of Glen Canyon Dam.

Webb, Robert H.; Griffiths, Peter G.; Melis, Theodre S.; Hartley, Daniel R.

2000-01-01

286

New Jersey Water Resources Research Institute Annual Technical Report  

E-print Network

New Jersey Water Resources Research Institute Annual Technical Report FY 2008 New Jersey Water Resources Research Institute Annual Technical Report FY 2008 1 #12;Introduction The New Jersey Water analytical technique to determine the source of fine-grained sediments in New Jersey streams. Galster

287

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

288

A DERIVED-DISTRIBUTION APPROACH TO DAILY LOADS OF SEDIMENT IN COASTAL PLAIN STREAMFLOW  

Technology Transfer Automated Retrieval System (TEKTRAN)

Estimates of allowable total maximum daily loads (TMDLs) of sediment must be developed for selected streams and rivers across the US. The sediment TMDLs are required to quantify total daily assimilative loads for those streams which are deemed to have impaired water quality due to sediment, and are ...

289

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

290

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

PubMed

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

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

2015-01-01

291

Hydrodynamic forcing and sediment character in Boston Harbor  

USGS Publications Warehouse

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

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

1998-01-01

292

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

293

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

294

Roles and Patterns of Hurricane Sedimentation in an Estuarine Marsh Landscape  

NASA Astrophysics Data System (ADS)

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

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

1995-06-01

295

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

296

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

297

2013 Annual Report | 1 2013 ANNUAL REPORT  

E-print Network

2013 Annual Report | 1 2013 ANNUAL REPORT ERIC FRIEDHEIM TOURISM INSTITUTE RESEARCH | CONSULTING | EDUCATION & TRAINING www.uftourism.org #12;2013 Annual Report | 22 Annual Report | 20132013 Annual Report | 2 Cover Page: Historic City of St. Augustine, Florida #12;CONTENTS Annual Report | 2013 3 Message

Pilyugin, Sergei S.

298

ANNUAL REPORT 2001 49 Annual Financial Statements  

E-print Network

ANNUAL REPORT 2001 49 Annual Financial Statements University Annual Financial Statements #12 are recognised in the Statement of Financial Position. #12;ANNUAL REPORT 2001 51 Annual Financial Statements;50 UNIVERSITY OF CANTERBURY Annual Financial Statements University Statement of accounting policies For the year

Hickman, Mark

299

ANNUAL REPORT 2002 57 Annual Financial Statements  

E-print Network

ANNUAL REPORT 2002 57 Annual Financial Statements University Annual Financial Statements #12 are recognised in the Statement of Financial Position. #12;ANNUAL REPORT 2002 59 Annual Financial Statements;58 UNIVERSITY OF CANTERBURY Annual Financial Statements University Statement of accounting policies For the year

Hickman, Mark

300

40 CFR Appendix 3 to Subpart A of... - Procedure for Mixing Base Fluids With Sediments  

Code of Federal Regulations, 2011 CFR

...American Society for Testing and Materials (ASTM). 1996. Standard Guide for Collection, Storage, Characterization, and Manipulation of Sediments for Toxicological Testing. ASTM E 1391-94. Annual Book of ASTM Standards, Volume 11.05, pp....

2011-07-01

301

Estimating long-term sediment export using a seasonal rainfall-dependent hydrological model in the Glonn River basin, Germany  

NASA Astrophysics Data System (ADS)

In European catchments, rainfall and overland flow trigger erosive processes that could result in soil detachment and transportation. However, estimation of both erosive rainfalls and sediment yields is very challenging, especially in historical times when only precipitations at seasonal or annual scales are available. This motivated us to develop a parsimonious hydroclimatological model (ASCLIM, Annual Sediment CLImatological Model) for predicting catchment scale sediment yield when temporal and spatial high-resolution precipitation data are not available. The model was developed by using the annual data of suspended-sediment yield from Glonn basin (1981-1995, gauge of Hohenkammer, Germany) and seasonal rainfall data from a NOAA data set. The correlation coefficient between predicted and observed sediment yields was 0.94 and the efficiency index was 0.89. Once parameterized, the model was able to capture annual sediment yield variability better than the Langbein-Schumm and the Fournier Index equations, also based on limited sets of inputs. The model holds potential for historical reconstruction of sediment yields in the Glonn catchment (assuming constant land cover) and for simulating sediment fluxes from catchments with similar characteristics. Our application highlights the control of rainfall seasonality on sediment export and demonstrates that our sediment yield proxy could be considered as a good tool for the expectation and planning of soil conservation. Moreover, considering that we used modeled data to reconstruct past sediment loss, we could expect that using projected future rainfall data our proxy could be able to assess future scenarios.

Diodato, Nazzareno; de Vente, Joris; Bellocchi, Gianni; Guerriero, Luigi; Soriano, Marcella; Fiorillo, Francesco; Revellino, Paola; Guadagno, Francesco M.

2015-01-01

302

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

PubMed

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

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

2015-01-01

303

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

304

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

305

Preliminary evaluation of a sediment pond draining a surface mined watershed  

SciTech Connect

Runoff and sediment data for a reclaimed surface mined watershed and its sediment pond were analyzed to determine the pond trap efficiency and influent/effluent sediment and flow relationships. Reclamation practices on the watershed included topsoiling, a good vegetative cover, a rock chute, diversions, and dry dams. Relationships were developed to predict the total pond flow and the sediment concentration when the flow rate on the hydrograph recession was one-half the storm peak rate, and to predict the peak pond influent sediment concentration as a function of the same recession concentration. The trap efficiency for the study sediment pond averaged 93.7 percent as determined by storm influent/effluent sediment masses. The average storm influent sediment concentration was 23 times larger than the average effluent pond sediment concentration of 372 mg/1, and the average peak storm effluent sediment concentration was 1.55 times greater than the average effluent sediment concentration.

Bonta, J.V.; Hamon, W.R.

1980-12-01

306

Changes in sediment volume in Alder Lake, Nisqually River Basin, Washington, 1945-2011  

USGS Publications Warehouse

The Nisqually River drains the southwest slopes of Mount Rainier, a glaciated stratovolcano in the Cascade Range of western Washington. The Nisqually River was impounded behind Alder Dam when the dam was completed in 1945 and formed Alder Lake. This report quantifies the volume of sediment deposited by the Nisqually and Little Nisqually Rivers in their respective deltas in Alder Lake since 1945. Four digital elevation surfaces were generated from historical contour maps from 1945, 1956, and 1985, and a bathymetric survey from 2011. These surfaces were used to compute changes in sediment volume since 1945. Estimates of the volume of sediment deposited in Alder Lake between 1945 and 2011 were focused in three areas: (1) the Nisqually River delta, (2) the main body of Alder Lake, along a 40-meter wide corridor of the pre-dam Nisqually River, and (3) the Little Nisqually River delta. In each of these areas the net deposition over the 66-year period was 42,000,000 ± 4,000,000 cubic meters (m3), 2,000,000 ± 600,000 m3, and 310,000 ± 110,000 m3, respectively. These volumes correspond to annual rates of accumulation of 630,000 ± 60,000 m3/yr, 33,000 ± 9,000 m3/yr, and 4,700 ± 1,600 m3/yr, respectively. The annual sediment yield of the Nisqually (1,100 ± 100 cubic meters per year per square kilometer [(m3/yr)/km2]) and Little Nisqually River basins [70 ± 24 (m3/yr)/km2] provides insight into the yield of two basins with different land cover and geomorphic processes. These estimates suggest that a basin draining a glaciated stratovolcano yields approximately 15 times more sediment than a basin draining forested uplands in the Cascade Range. Given the cumulative net change in sediment volume in the Nisqually River delta in Alder Lake, the total capacity of Alder Lake since 1945 decreased about 3 percent by 1956, 8 percent by 1985, and 15 percent by 2011.

Czuba, Jonathan A.; Olsen, Theresa D.; Czuba, Christiana R.; Magirl, Christopher S.; Gish, Casey C.

2012-01-01

307

A reconnaissance of stream sediment in the Erie-Niagara basin, New York  

USGS Publications Warehouse

This reconnaissance study of erosion and deposition of sediment in the Erie-Niagara basin indicates that the highest sediment yields, on the order of 1,000 tons per square mile per year, occur in streams that drain upland areas. In contrast, for example, from the lowland part of the Tonawanda Creek basin, the annual sediment yields are on the order of 100 tons per square mile per year. The estimated average annual sediment yields of streams in the basin range from 50 tons per square mile for Little Tonawanda Creek at Linden, to 1,500 tons per square mile for Cazenovia Creek at Ebenezer. These estimates are based on measured instantaneous sediment discharge at selected stream stations, the sediment loads of which ranged from 1,100 tons per year for Little Tonawanda Creek at Linden to 610,000 tons per year for Cattaraugus Creek at Gowanda. The accuracy of the estimates of average annual sediment discharge could be considerably improved by the collection of additional data. Nevertheless, the estimates are believed to be indicative of the magnitude of sediment yields and provide a general description of stream-sediment movement in the study area. Peak suspended-sediment concentrations in the range of 2,600 to 5,300 ppm (parts per million) were observed at three stations in the Cattaraugus Creek basin, as well as at Buffalo Creek at Gardenville, Cazenovia Creek at Ebenezer, and Cayuga Creek near Lancaster.

Archer, R.J.; La Sala, A.M., Jr.

1968-01-01

308

Sediment provenance in the Minnesota River basin- Using lakes to determine river sediment source types  

NASA Astrophysics Data System (ADS)

The Minnesota River and its tributaries have suspended sediment loads that exceed EPA standards. Lake Pepin, a natural reservoir for the Minnesota River, Upper Mississippi River, and St. Croix River watersheds, currently has an accumulation rate of approximately 10 times pre-settlement rates and is the focus of restoration efforts. The Minnesota River watershed is >80% row-crop agriculture and has a significant amount of tile and ditch drainage networks. Although it only accounts for 38% of the Lake Pepin watershed, it contributes 80-90% of all sediment that reaches Lake Pepin. Before effective mitigation programs can begin in the watershed, sediment sources must be identified. The main sources for river sediments, as constrained by this study, are: (1) bank and bluff erosion of sharply incised stream channels and near-channel gully and ravine erosion at the bluff/upland interface, all of which are referred to as non-field sources, and (2) topsoil erosion from agricultural fields. Our goal is to apply a new sediment-tracing technique using the atmospherically deposited radionuclides 210Pb and 137Cs to apportion sediment to one of these original landscape positions. 210Pb and 137Cs are good fingerprinting radioisotopes because they are atmospherically deposited and are highly particle reactive, thus sediments from sources with significant atmospheric exposure, such as fields, have higher concentrations. Conversely, sediments from sources with minimal atmospheric exposure, such as banks, have negligible concentrations. The total amount of 210Pb and 137Cs in river sediments is determined by measuring concentrations on sediments deposited in backwaters and artificial impoundments. The signature of the radionucludes from field sources is determined by measuring flux in a series of reference lakes that have no significant channelized inputs. The reference lake system works on the assumption that the same processes that carry field sediment to lakes are the same in river systems. Sediment fingerprints are compared by using a simple mixing model to apportion sources. Preliminary results indicate that >70% of the total suspended sediments in the highly agricultural Minnesota River tributary watersheds are from near-channel, non-field sources. This agrees with the Lake Pepin sediment cores, which integrate the entire watershed, with 75% from non-field sources. Because the Lake Pepin sediment accumulation rate has increased ten-fold since European settlement in Minnesota and the non-field contribution is >70%, it can be inferred that the increase in suspended sediment is not a natural phenomenon.

Blumentritt, D.; Schottler, S.; Engstrom, D.

2007-12-01

309

Sediment patches, sediment supply, and channel morphology  

Microsoft Academic Search

Bed surface particle size patchiness may play a central role in bedload and morphologic re- sponse to changes in sediment supply in gravel-bed rivers. Here we test a 1-D model (from Parker ebook) of bedload transport, surface grain size, and channel profile with two previously published flume studies that documented bed surface response, and specifically patch development, to reduced sediment

W. E. Dietrich; P. A. Nelson; E. Yager; J. G. Venditti; M. P. Lamb; L. Collins

310

96-hour sediment bioassay of Duluth and Superior Harbor basins (Minnesota) using Hexagenia limbata, Asellus communis, Daphnia magna, and Pimephales promelas as test organisms  

Microsoft Academic Search

The environmental effects of sediments upon water quality and the aquatic ecosystem are currently being investigated by bulk sediment analysis or elutriate procedures, with neither procedure being totally adequate. Using a sediment bioassay procedure developed at the Central Regional Laboratory, U.S. EPA, Region V by Prater and Anderson (1977), sediment bioassays were conducted on eight sediments collected from Duluth and

B. L. Prater; M. A. Anderson

1977-01-01

311

Use of hydroacoustic measurements to characterize bottom sediments and guide sampling and remediation of organic contaminants in lake sediments.  

PubMed

Sampling of bed sediment for contamination characterization is often limited by the heterogeneity in sediment properties and distribution. In this study, we explored the use of hydroacoustic measurements to characterize sediment properties and guide sediment sampling in a small lake contaminated by organochlorine pesticides (OCPs) and PCBs. A dual frequency hydroacoustic survey was conducted to characterize sediment properties, distribution, and thickness in McGrath Lake, near Ventura, CA. Based upon these results, sediment core samples were collected from 15 sites on the lake, and sectioned into 20 cm intervals for sediment characterization and analysis of OCPs and PCBs. Very high concentrations of total DDT and total chlordane were found in the sediments, with mean values of 919 and 34.9 ng g(-1), respectively. Concentrations of OCPs were highest at 60-80 cm depth near the inflow at the north end of the lake. Total PCB concentrations were much lower (mean concentration of 4.5 ng g(-1)). Using the hydroacoustic and chemical data, it was estimated that nearly 30,000 m(3) of DDT- and chlordane-contaminated sediment (above effects range median values) was present in the uppermost 1.2 m of sediment in the lake. A hydroacoustic survey can be a valuable tool used to delineate sediment distribution in a lake, identify areas with deeper organic sediment where hydrophobic contaminants would likely be found, and guide sampling. Sampling and chemical analyses are nonetheless needed to quantify contaminant levels in bottom sediments. When combined with hydroacoustic measurements, this approach can reasonably estimate the distributions and volumes of contaminated sediment important in the development of remediation strategies. PMID:23644565

Anderson, Michael A; Conkle, Jeremy L; Pacheco, Porfirio; Gan, Jay

2013-08-01

312

Silicate weathering in anoxic marine sediments  

NASA Astrophysics Data System (ADS)

Two sediment cores retrieved at the northern slope of Sakhalin Island, Sea of Okhotsk, were analyzed for biogenic opal, organic carbon, carbonate, sulfur, major element concentrations, mineral contents, and dissolved substances including nutrients, sulfate, methane, major cations, humic substances, and total alkalinity. Down-core trends in mineral abundance suggest that plagioclase feldspars and other reactive silicate phases (olivine, pyroxene, volcanic ash) are transformed into smectite in the methanogenic sediment sections. The element ratios Na/Al, Mg/Al, and Ca/Al in the solid phase decrease with sediment depth indicating a loss of mobile cations with depth and producing a significant down-core increase in the chemical index of alteration. Pore waters separated from the sediment cores are highly enriched in dissolved magnesium, total alkalinity, humic substances, and boron. The high contents of dissolved organic carbon in the deeper methanogenic sediment sections (50-150 mg dm-3) may promote the dissolution of silicate phases through complexation of Al3+ and other structure-building cations. A non-steady state transport-reaction model was developed and applied to evaluate the down-core trends observed in the solid and dissolved phases. Dissolved Mg and total alkalinity were used to track the in-situ rates of marine silicate weathering since thermodynamic equilibrium calculations showed that these tracers are not affected by ion exchange processes with sediment surfaces. The modeling showed that silicate weathering is limited to the deeper methanogenic sediment section whereas reverse weathering was the dominant process in the overlying surface sediments. Depth-integrated rates of marine silicate weathering in methanogenic sediments derived from the model (81.4-99.2 mmol CO2 m-2 year-1) are lower than the marine weathering rates calculated from the solid phase data (198-245 mmol CO2 m-2 year-1) suggesting a decrease in marine weathering over time. The production of CO2 through reverse weathering in surface sediments (4.22-15.0 mmol CO2 m-2 year-1) is about one order of magnitude smaller than the weathering-induced CO2 consumption in the underlying sediments. The evaluation of pore water data from other continental margin sites shows that silicate weathering is a common process in methanogenic sediments. The global rate of CO2 consumption through marine silicate weathering estimated here as 5-20 Tmol CO2 year-1 is as high as the global rate of continental silicate weathering.

Wallmann, K.; Aloisi, G.; Haeckel, M.; Tishchenko, P.; Pavlova, G.; Greinert, J.; Kutterolf, S.; Eisenhauer, A.

2008-06-01

313

[Spatial distribution and contamination evaluation of heavy metals in the intertidal surface sediments of Eastern Chongming].  

PubMed

Using the ArcGIS geostatistical analysis module, this work investigated the spatial distribution pattern of heavy metals (Cu, Pb, Zn, Cr, Cd) and their deposition fluxes in the intertidal surface sediments of Eastern Chongming based on the analysis of grain size, heavy metal concentrations and organic carbon content. The spatial interpolation (Kriging) was performed to estimate the deposition fluxes, and the contamination status of heavy metals was evaluated using geoaccumulation index and potential ecological risk index. The results showed that the average contents of Cu, Pb, Zn, Cr and Cd were 42, 27, 69, 71 and 0.23 microg x g(-1), respectively, all of which exceeded the background value in the Shanghai tidal flat. The contents of heavy metals showed a landward as well as northward increasing trend due to the influences of sediment grain size and organic carbon content. The annual deposition of Cu, Pb, Zn, Cr and Cd in Eastern Chongming were 187, 121, 395, 312 and 1.04 t, respectively; the total deposition flux of these heavy metals was 11 g x (m2 x a)-1. Although the overall contamination level of heavy metals in Eastern Chongming was relatively low, Cd, Pb and Cu had a potential pollution threat to the sediment environment. PMID:23002615

Li, Ya-Juan; Yang, Shi-Lun; Hou, Li-Jun; Zhou, Ju-Zhen; Liu, Ying-Wen

2012-07-01

314

Recent decadal growth of the Atchafalaya River Delta complex: Effects of variable riverine sediment input and vegetation succession  

NASA Astrophysics Data System (ADS)

The Mississippi River Delta Plain has experienced substantial wetland loss from subsidence, erosion, and sea level rise, threatening coastal communities and the ecosystems that support them. The Atchafalaya River, the largest distributary of the Mississippi River, has one of the few prograding delta features along the ~ 200-km deltaic coastline. Understanding changes in the Atchafalaya River Delta complex (ARDC) development has critical implications for future prediction and management strategy for the Mississippi River Delta Plain. This study was organized to answer two major questions: (1) how did development of the ARDC respond to fluctuation in riverine sediment supply over the period 1989-2010, and (2) has vegetation succession helped stabilize subaerial land? The study quantified annual total suspended sediment yields to the two ARDC subdeltas—Atchafalaya River subdelta (ARSD) and Wax Lake outlet subdelta (WLSD)—classified delta land cover using satellite imagery over ~ 5-year intervals into three classes: barren land, vegetation, and open water and investigated the relationship of delta land change with sediment yield and vegetation succession. Over the entire 21-year study period, we found a net land gain of 59 km2, with the ARSD accounting for 58% of this gain and WLSD 42%. Sediment yield to the subdeltas decreased from an average annual of 38 megatonnes (MT) for ARSD and 18 MT for WLSD during 1989-1995 to an average annual of 24 MT for ARSD and 17 MT for WLSD during 2004-2010, corresponding to the decrease in riverine suspended sediment concentration. Concurrently, total land growth rate decreased from 2.4 km2 y- 1 to 1.6 km2 y- 1 for ARSD and 3.2 km2 y- 1 to 0.6 km2 y- 1 for WLSD. However, the ARDC had a net land loss of 2.1 km2 during 1999-2004 because of tropical system effects in conjunction with the lack of large river floods (defined as discharge > 13,800 m3 s- 1). On average, more than 60% of newly vegetated land remained vegetated in subsequent years, and when compared with barren areas, vegetated land was less likely (7.3% vs. 32%) to be converted to water, indicating vegetative stabilization effect. However, during the period without a major flood, vegetation buffering against tropical system erosion was limited. This indicates that over the period 1989 to 2010 land growth of the ARDC was dictated by large flood events.

Rosen, Timothy; Xu, Y. Jun

2013-07-01

315

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

316

The paleoenvironmental and climatic recorded in core sediments of Lake Abashiri in the east part of Hokkaido, Japan  

NASA Astrophysics Data System (ADS)

In the coastal area of the Sea of Okhotsk in the east part of Hokkaido located to for subarctic zone, many brackish-water lakes are distributed. Especially, the Okhotsk brackish-water lake group around Abashiri City is constituted by major lake in Japan such as Lake Abashiri, Lake Mokoto, Lake Tofutsu, and Lake Notoro. The each lake shows a different present environment and history. Therefore, the change that is common in those lakes seems to be the change concerning the climate. In this study, paleoenvironmental and climatic changes after the Little Ice Age in Abashiri region is discussed by sedimentologic and geochemical high-resolution analysis of the 4m-sediment cores collected from the Lake Abashiri. The water column of Lake Abashiri has a distinct halocline around 5m depths, and is divided into oligohaline epilimnion and polyhaline hypolimnion by its pycnocline. The hypolimnion in Lake Abashiri shows the euxinic conditions throughout the annual. Therefore, surface sediment of below water depth 5m shows the black organic mud with the lamination. The 10AB-5C core collected from Lake Abashiri shows the length of 332cm. This core is composed of muddy sediment with a distinct lamination through all horizons. The Ta-a tephra (AD 1739) and Ko-c2 tephra (AD 1694) are found at the horizon of 250 cm, and 291 cm, respectively. Sedimentation rate based on these ages was 0.92cm/yr between Ko-c2 tephra and Ta-a tephra, and was 0.91cm/yr between surface and Ta-a tephra. The result of observation used by Soft X-ray photograph, the lamina-set of high, low, intermediate density layers was observed. The lamina set of 44 was recognized between Ko-c2 tephra and Ta-a tephra. This is suggested that this set is annual lamina (varve). If its so, it is considered that high density layer indicate the high precipitation term of summer season judging from precipitation pattern in Abashiri Area. Particularly, the year of flood events tend to show a thick and distinguished layer in lamina-set. The high-density lamina-set group is repeated with 20 to 30 year cycle. The horizon of high-density lamina-set group is correlated with the term showing several years continuously high precipitation. This lamina-set group is observed from 400 years ago, the climate system would have been continued. In order to clarify the formation process of the lamina set in Lake Abashiri, we are observed by a sediment trap. Sediment traps are set up above 2m from lake bottom in water mass under euxinic environment. Result of this observation, sediment flux is increased in early spring (ice melting) and late summer (flood) seasons. Sediment flux in early spring season is higher than late summer season. Total organic carbon (TOC) contents of trapped sediment are higher than surface sediments except for trapped sediment in early spring season. These are suggested that low-density layer indicate in early spring (ice melting) season. In winter (ice) and early summer seasons, the sediment flux is low, and TOC contents show the high value. This is suggested that the limited supply of inorganic sediment. In this time, the diatom lamina may been formed in lamina set.

Seto, K.; Katsuki, K.; Sonoda, T.; Kawajiri, T.; Watanabe, T.

2013-12-01

317

Mixed Sediment Modeling for Matagorda Ship Channel, Texas , M. Ferro1  

E-print Network

Mixed Sediment Modeling for Matagorda Ship Channel, Texas L. Lin1 , H. Li1 , M. Ferro1 , and C of Matagorda Ship Channel, Texas, in recent years has resulted in the need for annual dredging. The channel shoaling in the Ship channel is complicated as it involves the mixed sediment in the surrounding area

US Army Corps of Engineers

318

Recent changes of water discharge and sediment load in the Zhujiang (Pearl River) Basin, China  

Microsoft Academic Search

The paper is concerned with identifying changes in the time series of water and sediment discharge of the Zhujiang (Pearl River), China. The gradual trend test (Mann–Kendall test), and abrupt change test (Pettitt test), have been employed on annual water discharge and sediment load series (from the 1950s–2004) at nine stations in the main channels and main tributaries of the

Shurong Zhang; Xi Xi Lu; David L. Higgitt; Chen-Tung Arthur Chen; Jingtai Han; Huiguo Sun

2008-01-01

319

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

320

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

321

Mercury in sediment and fish from North Mississippi Lakes  

Microsoft Academic Search

Sediments and\\/or fish were collected from Sardis, Enid and Grenada Lakes, which are located in three different watersheds in North Mississippi, in order to assess mercury contamination. The mean total mercury concentration in sediments from Enid Lake in 1997 was 0.154 mg Hg\\/kg, while 1998 sediment concentrations in Sardis, Enid and Grenada Lakes were 0.112, 0.088 and 0.133 mg Hg\\/kg,

D. B. Huggett; J. A. Steevens; J. C. Allgood; C. B. Lutken; C. A. Grace; W. H. Benson

2001-01-01

322

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

323

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 approximately 4-5 times higher than predicted pre-settlement erosion rates. Additionally, modeling efforts provide insight into the nature of erosion and incision into glacial till. The Le Sueur River is best modeled as a detachment-limited bedrock channel where downstream coarsening from incision into the till is a critical factor in developing the longitudinal profile of the river.

Finnegan, N. J.; Gran, K. B.

2012-12-01

324

Let's Bet on Sediments  

NSDL National Science Digital Library

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

325

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

326

Fluvial sediment in Salem Fork watershed, West Virginia  

USGS Publications Warehouse

Suspended sediment discharged from the 8.32-square-mile Salem Fork study area in Harrison County, W. Va., averaged 3,500 tons per year during the first 4-year period of investigation and 1,770 tons per year during the second 4-year period. The difference as attributed to increased flow control, effected by the completion of detention structures and other conservation measures, the absence of appreciable sediment-producing construction activities, and a reduction of the amounts of rainfall and runoff during the second 4-year period. Particle-size distribution of the suspended sediment discharged from the watershed remained unchanged during the two 4-year periods. Although sand and some silt were deposited in upstream reservoirs, sands and other sediments were evidently entrained in the flow below the reservoirs. During the 7.75-year period, reservoir 11A had a trap efficiency of 88 percent. The average annual sediment yield of subwatershed 11A was 1.31 tons per acre, or 837 tons per square mile. Outflow from reservoir 11A occurred during 81 percent of the investigation 'period, October 1954 to June 1962, and 78 percent of the sediment discharge from the reservoir occurred during less than 6 percent of the investigation period. A comparison of particle-size distribution of inflow sediment with that of outflow sediment revealed that practically all sands and some silts entering reservoir 11A were deposited in the reservoir. Chemical analyses of inflow water and the particle-size analyses suggested that flocculation of fine sediments occurred in the reservoir. Analysis of the sediment data collected at the outflow of reservoir 9 during 1956-62 revealed that the average annual sediment discharge was 128,000 pounds per year. Limited particle-size data suggested that practically no sand was discharged from reservoir 9, even though the inflow contained sand. Average annual inflow to reservoirs 11A and 9 compared favorably with average annual runoff for the entire watershed-study area.

Flint, R.F.

1972-01-01

327

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

NASA Astrophysics Data System (ADS)

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

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

1984-04-01

328

2010 Summary Annual Report Summary Annual Report  

E-print Network

2010 Summary Annual Report Summary Annual Report This is a summary of the annual report 1, 2010 through December 31, 2010. The annual report has been filed with the Department of Labor Rights to Additional Information You have the right to receive a copy of the full annual report, or any

Ford, James

329

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

USGS Publications Warehouse

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

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

2000-01-01

330

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

USGS Publications Warehouse

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

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

2010-01-01

331

Implications of bedload sampling point on sediment budget assessment  

NASA Astrophysics Data System (ADS)

Past and present management of the Ebro catchment have altered water and sediment fluxes of the lower Ebro River and its delta. The construction of the Mequinensa and Riba-Roja dams during the 1960s disrupted the sediment transport continuity. As a result, the lower Ebro River and its delta are facing a dramatic reduction in sediment delivery. As part of the design of a sediment management plan, we constructed the sediment budget of the lowermost Ebro river (85.530 km2) in order to evaluate the present sediment deficit and the required restoration needs from the reservoirs. The sediment budget is based on bed load and suspended sediment field measurements. Bed load and suspended sediment samples were obtained at two different verticals; covering up to 50% of the total channel width. Special attention has been paid on the importance of the sampling point, and its implications on the sediment budget. Preliminary results indicate that approximately 130.000 tones of sediment passed at the outlet basin in 2008; which represents a reduction in sediment delivery up to 99% of its original yield (about 3 x 107 t/yr). Sediment was transported in a proportion of 89% as suspended and 11% as bed load. In contrast, 40 km upstream of the outlet basin, previous studies indicate that 40% of total load is transported as bed load. That fact could be associated to the effect of dams, the closer to the dams the higher the sediment deficit. In addition, results show that when using data from two different verticals, the estimate of the total sediment transported as bed load is one order of magnitude different (8.000 t versus 20.000 t). Furthermore, bed material passing through the first vertical is composed by sand (53%) and gravels (47%), while bed load at the second vertical is almost totally composed by gravels. Both factors (crossectional location and bed load texture) have severe implications on the assessment of the sediment budget; especially when results are to be used for river management, restoration and sediment yield assessment.

Rovira, A.; Martín-Vide, J. P.; Ibáñez, C.

2009-04-01

332

Sediment Mobilization in Ravines Draining Minnesota Cropland  

NASA Astrophysics Data System (ADS)

In recent years, studies have found that Lake Pepin, a naturally-dammed lake on the Mississippi River on the border of Minnesota and Wisconsin, is filling in with sediment at an alarming rate. Most of this sediment comes from the Minnesota River, which contributes about 80% of all the sediment being deposited in Lake Pepin, even though it contains only 35% of the upstream area. This study focuses on understanding sediment derived from ravine erosion in a tributary of the Minnesota River basin through event monitoring of two ravines in the Le Sueur River watershed. Ravines represent one of the key sediment sources in the Le Sueur watershed, with sediment mobilized through ravine widening and headcutting. In addition, sediment may be mobilized through riverbank and bluff erosion and erosion of the topsoil. A major effort is underway to reduce the amount of sediment in the Minnesota River and Lake Pepin, so we must discover what is causing the sediment to be mobilized and when. Dominant land use in the area is agricultural with over 90% of the crops consisting of row crops. Field drainage in these agricultural areas is heavily influenced by the installation of drainage ditches and drain tile. While this has increased crop yield, it has altered the natural drainage of the area. Southern Minnesota is covered by a thick layer of glacial till allowing the landscape to rapidly respond to hydrologic conditions within a relatively short amount of time, and those changes could include ravine widening or elongation. To better understand how ravines respond to different hydrologic events, we monitored ravines over the course of one monitoring season. From April-October 2013, three Sigma 930 automated samplers measured discharge and collected water samples for total suspended sediment analysis at three sites in two ravines. We tested whether the volume, intensity or seasonality of precipitation events is most important in mobilizing sediment in the ravines. Data are being analyzed to calculate sediment budgets and identify key hydrologic factors that control sediment movement out of these ravines and into the river.

Choquette, A. W.; Triplett, L.; Gran, K. B.

2013-12-01

333

Assessing Sedimentation Issues Within Aging Flood Control Reservoirs in Oklahoma  

NASA Astrophysics Data System (ADS)

Since 1948, the USDA-NRCS has constructed nearly 11,000 flood control dams across the United States, and many of the reservoirs are rapidly filling with sediment. To rehabilitate these structures, the impounded sediment must be assessed to determine the volume of accumulated sediment and the potential hazard this sediment may pose if reintroduced to the environment. An assessment of sedimentation issues within two reservoirs, Sugar Creek No. 12, Hinton, Oklahoma, and Sergeant Major No. 4, Cheyenne, Oklahoma, is presented. Sediment cores obtained using a vibracoring system were composed of alternating layers of gravel, sand, silt, and clay. Stratigraphic analysis coupled with 137Cs dating techniques enabled the discrimination of pre-construction sediment from post-construction deposition. An acoustic profiling system was unencumbered by the relatively shallow water depth at Sugar Creek No. 12 and the seismic horizons agreed well with the sediment core data. Total sediment volume determined from the acoustic survey and the sediment core data for comparable areas differed by only 1.4 percent. The seismic profiling system worked well in the relatively deeper lake of Sergeant Major No. 4 and showed good correspondence to the collected core data. Detailed chemical analyses showed that overall sediment quality was good at both locations and that chemical composition was spatially invariant. Implementation of these techniques will aid action agencies such as the USDA-NRCS in their assessment and effective management of aging flood control reservoirs.

Bennet, Sean J.; Cooper, Charles M.; Ritchie, Jerry C.; Dunbar, John A.; Allen, Peter M.; Caldwell, Larry W.; McGee, Thomas M.

2002-10-01

334

Mercury dynamics in lake sediments  

NASA Astrophysics Data System (ADS)

Triplicate porewater depth-profiles of pH and concentrations of total Hg (HgT), methylmercury (MeHg), Fe, Mn, sulfate, total sulfide, total zero-valent sulfur, organic C and major ions were determined at two sampling dates in a perennially oxygenated basin and a seasonally anoxic basin from Lake Tantaré, a Canadian Shield lake. The vertical distribution of HgT, MeHg, acid volatile sulfide, total S, Fe, Mn, Al and organic C were also determined in dated sediment cores from the same lake basins and from the deepest site of two other lakes, one also located in the Canadian Shield and the other in the Northeastern part of the Appalachian Mountains. Application of a one-dimensional transport-reaction equation to the dissolved HgT and MeHg profiles constrains the depth intervals (zones) where these species are produced or consumed in the sedimentary column and yields estimates of net reaction rates of HgT or MeHg in each of the zones as well as their fluxes at the sediment-water interface. Dissolved HgT and MeHg diffused from the overlying water into the sediments, except for MeHg at one of the sampling dates in the perennially oxygenated basin. About 97% and 50% of the MeHg flux to the sediments is presently deposited with settling particles in the perennially oxygenated and seasonally anoxic basins, respectively. Removal of porewater HgT and MeHg occurred at all dates and sampling sites. Comparison of the consumption zones of porewater HgT and MeHg with the profiles of ancillary parameters, coupled with thermodynamic calculations, suggest that pure Hg mineral phases do not form in the sediments, that HgT and MeHg adsorption onto authigenic Fe oxyhydroxides occurs in minor proportions, and that the association of HgT and MeHg to Fe sulfide phases or sulfidized organic matter is possible. Assuming that the net consumption of MeHg in the porewaters was essentially due to demethylation, an apparent first-order rate constant for MeHg demethylation of 0.04-0.8 d-1 was estimated. Production of porewater MeHg occurred only in the perennially oxygenated basin, at sediment depths where SO4 was consumed. Assuming that the net production of porewater MeHg was essentially due to methylation, an apparent first-order rate constant for Hg methylation ranging between 0.006 d-1 and 0.1 d-1 was calculated. These field-derived Hg methylation and MeHg demethylation rate constant values are within the range of those derived from Hg-spiked experiments. We also show that the post-depositional redistribution of total Hg during the early stages of sediment diagenesis is minor and that the solid-phase HgT record can be used to reconstruct the evolution of the anthropogenic HgT deposition.

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

2012-04-01

335

MERCURY IN SEDIMENT AND FISH FROM NORTH MISSISSIPPI LAKES.  

EPA Science Inventory

Sediments and/or fish were collected from Sardis, Enid and Grenada Lakes, which are located in three different watersheds in North Mississippi, in order to assess mercury contamination. The mean total mercury concentration in sediments from Enid Lake in 1997 was 0.154 mg Hg/kg, w...

336

Fluvial sediment in Hocking River subwatershed 1 (North Branch Hunters Run), Ohio  

USGS Publications Warehouse

From May 1956 to May 1962, Hocking River subwatershed 1 of Upper Hocking River Pilot Watershed had an average annual sediment yield from its contributing area of 0.94 square mile of 1,195 tons per square mile. Annual suspended-sediment yield at the outlet, expressed in tons per acre-foot of outflow, decreased from 0.45 in the 1957 water year to 0.10 in the 1962 water year, reflecting a decrease in sediment yield from the 1.04-squaremile drainage area above detention structure 1.

Flint, R.F.

1972-01-01

337

Spatial distribution of gamma radioactivity levels and radiological hazard indices in the East Coastal sediments of Tamilnadu, India with statistical approach  

NASA Astrophysics Data System (ADS)

Natural and artificial radionuclide pollutants of the marine environment have been recognized as a serious environmental concern. The natural radioactivity levels in beach sediment samples collected from Thazhankuda (Cuddalore) to Kodiyakkarai along East Coast of Tamilnadu have been determined. Sediment sample were collected by a Peterson grab sampler from 10 m water depths parallel to the shore line. The grab sampler collects 10 cm thick bottom sediment layer from the seabed along the 20 stations. The radioactivities of 20 samples have been measured with a NaI(Tl) detector. The average specific activities for 238U, 232Th, and 40K were found to be 3.67, 37.23 and 387.17 Bq kg-1 respectively. The results have been compared with other radioactivity measurements in different countries. It shows that the average activity of 238U and 40K is lower whereas 232Th is slightly greater than the compared worldwide average value. The radiation hazard due to the total natural radioactivity in the study area was estimated by different approaches such as the radium equivalent activity (Raeq), absorbed dose rate (DR), hazard indices, the annual gonadal dose equivalent (AGDE) and annual effective dose equivalent (AEDE) are compared with the international recommended values. Multivariate Statistical analyses (Pearson Correlation, Cluster and Factor analysis) were carried out between the parameters obtained from the radioactivity to know the existing relations and to study the spatial distribution of radionuclide.

Ravisankar, R.; Sivakumar, S.; Chandrasekaran, A.; Prince Prakash Jebakumar, J.; Vijayalakshmi, I.; Vijayagopal, P.; Venkatraman, B.

2014-10-01

338

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

USGS Publications Warehouse

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

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

2000-01-01

339

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

USGS Publications Warehouse

The U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers, Fort Worth District; City of Corpus Christi; Guadalupe-Blanco River Authority; San Antonio River Authority; and San Antonio Water System, developed, calibrated, and tested a Hydrological Simulation Program-FORTRAN (HSPF) watershed model to simulate streamflow and suspended-sediment concentrations and loads during 1958-2010 in the lower Nueces River watershed, downstream from Lake Corpus Christi to the Nueces Estuary in south Texas. Data available to simulate suspended-sediment concentrations and loads consisted of historical sediment data collected during 1942-82 in the study area and suspended-sediment concentration data collected periodically by the USGS during 2006-7 and 2010 at three USGS streamflow-gaging stations (08211000 Nueces River near Mathis, Tex. [the Mathis gage], 08211200 Nueces River at Bluntzer, Tex. [the Bluntzer gage], and 08211500 Nueces River at Calallen, Tex. [the Calallen gage]), and at one ungaged location on a Nueces River tributary (USGS station 08211050 Bayou Creek at Farm Road 666 near Mathis, Tex.). The Mathis gage is downstream from Wesley E. Seale Dam, which was completed in 1958 to impound Lake Corpus Christi. Suspended-sediment data collected before and after completion of Wesley E. Seale Dam provide insights to the effects of the dam and reservoir on suspended-sediment loads transported by the lower Nueces River downstream from the dam to the Nueces Estuary. Annual suspended-sediment loads at the Nueces River near the Mathis, Tex., gage were considerably lower for a given annual mean discharge after the dam was completed than before the dam was completed. Most of the suspended sediment transported by the Nueces River downstream from Wesley E. Seale Dam occurred during high-flow releases from the dam or during floods. During October 1964-September 1971, about 536,000 tons of suspended sediment were transported by the Nueces River past the Mathis gage. Of this amount, about 473,000 tons, or about 88 percent, were transported by large runoff events (mean streamflow exceeding 1,000 cubic feet per second). To develop the watershed model to simulate suspended-sediment concentrations and loads in the lower Nueces River watershed during 1958-2010, streamflow simulations were calibrated and tested with available data for 2001-10 from the Bluntzer and Calallen gages. Streamflow data for the Nueces River obtained from the Mathis gage were used as input to the model at the upstream boundary of the model. Simulated streamflow volumes for the Bluntzer and Calallen gages showed good agreement with measured streamflow volumes. For 2001-10, simulated streamflow at the Calallen gage was within 3 percent of measured streamflow. The HSPF model was calibrated to simulate suspended sediment using suspended-sediment data collected at the Mathis, Bluntzer, and Calallen gages during 2006-7. Model simulated suspended-sediment loads at the Calallen gage were within 5 percent of loads that were estimated, by regression, from suspended-sediment sample analysis and measured streamflow. The calibrated watershed model was used to estimate streamflow and suspended-sediment loads for 1958-2010, including loads transported to the Nueces Estuary. During 1958-2010, on average, an estimated 288 tons per day (tons/d) of suspended sediment were delivered to the lower Nueces River; an estimated 278 tons/d were delivered to the estuary. The annual suspended-sediment load was highly variable, depending on the occurrence of runoff events and high streamflows. During 1958-2010, the annual total sediment loads to the estuary varied from an estimated 3.8 to 2,490 tons/d. On average, 113 tons/d, or about 39 percent of the estimated annual suspended-sediment contribution, originated from cropland in the study watershed. Releases from Lake Corpus Christi delivered an estimated 94 tons/d of suspended sediment or about 33 percent of the 288 tons/d estimated to have been delivered to the lower Nueces River. Erosion of stream-channel bed and banks accou

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

2013-01-01

340

Complex land cover change, water and sediment yield in a degraded Andean environment  

NASA Astrophysics Data System (ADS)

SummaryRapid land use/-cover change has increasingly transformed the hydrological functioning of tropical Andean ecosystems. The hydrological response to forest cover change strongly depends on the initial state of the ecosystem. Relatively little is known about human-disturbed ecosystems where forest plantations have been established on highly degraded land. In this paper, we analyze the impact of forest change on water and sediment fluxes for a highly degraded Andean catchment. Different pathways of land cover change (1963-2007) are observed in the Jadan catchment, with deforestation taking place in remote uplands and recovery and reforestation in the middle and lower parts where agricultural and bare lands are prevalent. Time series analyses of streamflow and rainfall data (1979/1982-2005/2007) show significant shifts in the distribution of rainfall and flow data. Changes in discharge are not resulting from changes in precipitation, as the direction of change is opposite. The removal of native forest for rangeland or croplands (by -20 km2) is likely to have contributed to the increase in total annual water yield, through an increase in annual baseflow by 25 mm. The observed changes in peakflow are important as the 1st percentile highest flow rates were 54% lower, while the 1st percentile rainfall amounts increased by 52%. The observed decrease in peakflow cannot be explained by clearcut of native forest, but is likely to be related to reforestation of degraded lands as well as spontaneous recovery of vegetation on remaining grazing lands. Over the same time period, a major decrease in specific sediment yields and suspended sediment loads was observed. Although deforestation in the upper parts led to increased landslide activity, this change is not reflected in an increased sediment yield. Small upland rivers are often nearly completely blocked by landslide material, thereby reducing their potential to transport sediment. In contrast, the reduction in estimated erosion is likely to be caused by the reduction of the degraded areas in areal extent as well as to the (partial) recovery of the vegetation in these areas.

Molina, Armando; Vanacker, Veerle; Balthazar, Vincent; Mora, Diego; Govers, Gerard

2012-11-01

341

Suspended sediment regimes in contrasting reference-condition freshwater ecosystems: Implications for water quality guidelines and management.  

PubMed

Suspended sediment (SS), ranging from nano-scale particles to sand-sized sediments, is one of the most common contributors to water quality impairment globally. However, there is currently little scientific evidence as to what should be regarded as an appropriate SS regime for different freshwater ecosystems. In this article, we compare the SS regimes of ten systematically-selected contrasting reference-condition temperate river ecosystems that were observed through high-resolution monitoring between 2011 and 2013. The results indicate that mean SS concentrations vary spatially, between 3 and 29mgL(-1). The observed mean SS concentrations were compared to predicted mean SS concentrations based on a model developed by Bilotta et al. (2012). Predictions were in the form of probability of membership to one of the five SS concentration ranges, predicted as a function of a number of the natural environmental characteristics associated with each river's catchment. This model predicted the correct or next closest SS range for all of the sites. Mean annual SS concentrations varied temporally in each river, by up to three-fold between a relatively dry year (2011-2012) and a relatively wet year (2012-2013). This inter-annual variability could be predicted reasonably well for all the sites except the River Rother, using the model described above, but with modified input data to take into account the mean annual temperature (°C) and total annual precipitation (mm) in the year for which the mean SS prediction is to be made. The findings highlight the need for water quality guidelines for SS to recognise natural spatial and temporal variations in SS within rivers. The findings also demonstrate the importance of the temporal resolution of SS sampling in determining assessments of compliance against water quality guidelines. PMID:25290590

Grove, Magdalena K; Bilotta, Gary S; Woockman, Robert R; Schwartz, John S

2015-01-01

342

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

USGS Publications Warehouse

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

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

2008-01-01

343

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

USGS Publications Warehouse

The U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers-Fort Worth District, City of Corpus Christi, Guadalupe-Blanco River Authority, San Antonio River Authority, and San Antonio Water System, developed, calibrated, and tested a Hydrological Simulation Program ? FORTRAN (HSPF) watershed model to simulate streamflow and suspended-sediment concentrations and loads during 1958-2008 in the lower Nueces River watershed, downstream from Lake Corpus Christi to the Nueces Estuary in South Texas. Data available to simulate suspended-sediment concentrations and loads consisted of historical sediment data collected during 1942-82 in the study area and suspended-sediment concentration data collected periodically by the USGS during 2006-07 at three USGS streamflow-gaging stations, Nueces River near Mathis, Nueces River at Bluntzer, and Nueces River at Calallen. The Nueces River near Mathis station is downstream from Wesley E. Seale Dam, completed in 1958 to impound Lake Corpus Christi. Suspended-sediment data collected before and after completion of Wesley E. Seale Dam provide insights to the effects of the dam and reservoir on suspended-sediment loads transported by the lower Nueces River from downstream of the dam to the Nueces Estuary. Annual suspended-sediment loads at a site near the Nueces River at Mathis station were considerably lower, for a given annual mean discharge, after the dam was completed than before the dam was completed. Most of the suspended sediment transported by the Nueces River downstream from Wesley E. Seale Dam occurred during high-flow releases from the dam or during floods. During October 1964-September 1971, about 532,000 tons of suspended sediment were transported by the Nueces River near Mathis. Of this amount, about 473,000 tons, or about 89 percent, were transported by large runoff events (mean streamflow exceeding 1,000 cubic feet per second). To develop the watershed model to simulate suspended-sediment concentrations and loads in the lower Nueces River watershed during 1958-2008, streamflow simulations were calibrated and tested with available data for 2001-08 from the Nueces River at Bluntzer and Nueces River at Calallen stations. Streamflow data from the Nueces River near Mathis station were used as input to the model at the upstream boundary of the model. Simulated streamflow volumes for the Bluntzer and Calallen stations showed good agreement (within 6 percent) with measured streamflow volumes. The HSPF model was calibrated to simulate suspended sediment using suspended-sediment data collected at the Mathis, Bluntzer, and Calallen stations during 2006-07. The calibrated watershed model was used to estimate streamflow and suspended-sediment loads for 1958-2008, including loads transported to the Nueces Estuary. During 1958-2008, on average, an estimated 307 tons per day of suspended sediment were delivered to the lower Nueces River; an estimated 297 tons per day were delivered to the estuary. The annual suspended-sediment load was highly variable, depending on the occurrence of storm events and high streamflows. During 1958-2008, the annual total sediment loads to the estuary varied from an estimated 3.8 to 2,490 tons per day. On average, 117 tons per day, or about 38 percent of the estimated annual suspended-sediment contribution, originated from cropland in the study watershed. Releases from Lake Corpus Christi delivered an estimated 98 tons per day of suspended sediment or about 32 percent of the 307 tons per day estimated to have been delivered to the lower Nueces River. Erosion of stream-channel bed and banks accounted for 55 tons per day or about 18 percent of the estimated total suspended-sediment load. All other land categories, except cropland, accounted for an estimated 37 tons per day, or about 12 percent of the total. An estimated 9.6 tons per day of suspended sediment or about 3 percent of the suspended-sediment load delivered to the lower Nueces River

Ockerman, Darwin J.; Heitmuller, Franklin T.

2010-01-01

344

Seasonality of alkenone estimates as inferred from sediment trap data  

NASA Astrophysics Data System (ADS)

The seasonality of the Sea Surface Temperatures (SSTs) estimated from the alkenone- UK37' index has been a contentious issue since the development of the proxy. Using a compilation of sediment traps from 34 locations we show that the seasonality of maximum alkenone fluxes in sediment traps vary markedly across the oceans, depending on the characteristics of the local oceanographic settings, rather than driven just by latitude and light availability as could be inferred from net primary productivity patterns. The seasonality of the fluxes to sediments may also be altered due to the complexity of sedimentation processes. Nevertheless, the flux weighted UK'37 displays a global correlation with mean annual SSTs at 0 m that closely resembles that of the standard calibration equation derived from a Emiliania huxley culture and surface sediments. Thus, even though the UK37' export signals in some locations may be seasonally biased, and although a single consistent seasonal pattern of alkenone fluxes may not occur globally, the integrated sedimentation patterns of UK'37 in the water column represent annual averages of SST.

Rosell Mele, A.; Prahl, F. G.

2012-12-01

345

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

USGS Publications Warehouse

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

Clark, Gregory M.

1997-01-01

346

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

347

75 FR 63805 - Annual Wholesale Trade Survey  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2010-10-18

348

Decadal mercury trends in San Francisco Estuary sediments.  

PubMed

Monitoring sediment quality and total mercury concentrations over the period 1993-2001 at 26 stations in San Francisco Estuary has shown the seasonal cycling of mercury sediment concentrations, as well as a significant (P < 0.05) decrease in those concentrations at eight stations across the estuary. This decrease in sediment mercury concentrations is attributed to the transport of relatively cleaner sediment to the estuary from the Sacramento River and San Joaquin River watersheds. Despite the decreases observed in some parts of the estuary, no corresponding trend has been found in concurrent studies on sport fish and bivalves in the estuary. PMID:17161835

Conaway, Christopher H; Ross, John R M; Looker, Richard; Mason, Robert P; Flegal, A Russell

2007-09-01

349

Integrated Echo Sounder, GPS, and GIS for Reservior Sedimentation Studies: Examples From Two Arkansas Lakes  

NASA Astrophysics Data System (ADS)

Bathymetric and sedimentation surveys were conducted using a dual frequency (28/200 kHz) echo sounder system in two reservoirs (Lee Creek Reservoir and Lake Shepherd Springs) in the Ozark Plateau of northwestern Arkansas. Echo sounder survey data were merged within geographic information system (GIS) software to provide detailed visualization and analyses of current depths, pre-impoundment topography, distribution, thickness, and volume estimates of lacustrine sediment, time averaged sediment accumulation rates, long term average annual sediment flux, and water storage capacity. Calculated long term average sediment accumulation rates were used to model sediment infilling and projected lifetimes of each reservoir. Results from echo sounder surveys and GIS analyses suggest that the Lee Creek Reservoir has a projected lifetime of approximately 500 years compared to a projected lifetime for Lake Shepherd Springs of approximately 3,000 years. Estimated differences in projected lifetimes of these reservoirs reflected differences in initial reservoir volume and long term average annual sediment flux from the respective watersheds related to watershed area, physiography, land cover, and land use. The universal soil loss equation (USLE) model generated sediment fluxes an order of magnitude larger from the watersheds of both reservoirs compared to the geophysical data estimates. This study demonstrated the utility of merging geophysical survey (echo sounder) data within a GIS as an aid to understanding patterns of reservoir sedimentation. These data and analyses also provide a baseline relevant to understanding sedimentation processes and are necessary for development of long term management plans for these reservoirs and their watersheds.

Odhiambo, Ben K.; Boss, Stephen K.

2004-08-01

350

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

351

Variation in suspended sediment yield across the UK - A failure of the concept and interpretation of the sediment delivery ratio  

NASA Astrophysics Data System (ADS)

The sediment delivery ratio (SDR) has been a common approach developed to understand change in sediment yield and flux through a catchment. In this study we propose that the underlying concept of the sediment delivery ratio is flawed for a number of reasons: its linear extrapolation is physically meaningless; there is no evidence of the magnitude of storage required by the SDR approach on annual to decadal timescales; and the SDR approach assumes suspended sediment transport is conservative yet it is known to undergo both loss and production in-channel. This study considers the sediment yield from 192 UK catchments from 1974 to 2010 for catchment areas between 4 and 9948 km2 and shows that linear extrapolation of the SDR approach overpredicts source terms and underpredicts fluxes for large catchments. The SDR approach hides a range of behaviours of suspended sediment flux within catchments with patterns of net deposition, net increase or no change all apparent in UK catchments. The approach proved to be self-correlated which meant that it can result in spurious correlations when compared to catchment area. The change in yield with catchment area can be just as well understood as a change in sediment supply from channels rather than as a change in delivery from hillslope sources. We propose that suspended sediment flux change with catchment area be modelled as a more physically-meaningful Gompertz function (step function) rather than using the traditional SDR approach.

Worrall, Fred; Burt, Tim P.; Howden, Nicholas J. K.; Hancock, Gregory R.

2014-11-01

352

Globorotalia truncatulinoides (dextral) Mg/Ca as a proxy for Gulf of Mexico winter mixed-layer temperature: evidence from a sediment trap in the northern Gulf of Mexico  

USGS Publications Warehouse

Three years of weekly- to biweekly-resolved sediment-trap data show that almost 90% of the total flux of tests of the planktic foraminifer Globorotalia truncatulinoides to sediments in the northern Gulf of Mexico occurs in January and February. Comparison of ?18O from tests of non-encrusted Gl. truncatulinoides in sediment-trap samples with calculated calcification depths indicates that the non-encrusted individuals secrete their test in the winter surface-mixed layer, most likely at the bottom of the surface mixed zone. Mg/Ca-temperature estimates from non-encrusted Gl. truncatulinoides in sediment-trap samples are consistent with observed temperatures at the calcification depths inferred from the ?18O data. In contrast, Mg/Ca-temperature estimates from encrusted Gl. truncatulinoides in sediment-trap samples indicate the crust is formed in cooler (deeper) waters. A preliminary study in a core recovered near the sediment-trap site demonstrates that non-encrusted and encrusted forms of Gl. truncatulinoides in sediment samples show a similar offset in Mg/Ca values as observed in sediment-trap samples. A short (~ 100 years) Mg/Ca record from non-encrusted Gl. truncatulinoides indicates a warming trend that coincides with a warming trend in mean-annual sea-surface temperature recorded by Mg/Ca in Globigerinoides ruber (white) from the same core. These findings suggest Mg/Ca from non-encrusted Gl. truncatulinoides has clear potential as a proxy for past winter mixed-layer temperature.

Spear, Jessica W.; Poore, Richard Z.; Quinn, Terrence M.

2011-01-01

353

Concentrations of DDTs and dieldrin in Long Island Sound sediment.  

PubMed

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

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

2012-03-01

354

Sediment yield in eastern Montana; summary of data and proposed techniques for estimating sediment yields from small, ungaged watersheds  

USGS Publications Warehouse

Sediment-yield data for 121 sites in eastern Montana have been compiled from results of studies conducted by various Federal, State, and private agencies. Methods used to determine mean annual sediment yields included reservoir sedimentation surveys, suspended-sediment sampling in streams, and estimates of gross erosion and indirect estimation based on physical characteristics of the basin. Multiple-regression equations were developed and evaluated for their adequacy in estimating mean annual sediment yields from small, ungaged watersheds in eastern Montana. Sediment yields determined from reservoir surveys were used as the dependent variable because they were considered the most representative of long-term yields. Independent variables consisted of basin characteristics which could be measured from maps or obtained from published sources. Consequently, equations developed in this study do not require onsite data. Evaluation of equations indicated that the best prediction capability was obtained when reservoir basins were segregated into classes of similar vegetation/soil complex. The predictive capability of regression equations developed for each of three classes of vegetation/soil complex, as indicated by the coefficient of determination (R2), ranged from 0.59 to 0.96. Corresponding standard errors ranged from 95 to 20 percent. The equations are applicable for small drainage basins of 2 square miles or less within the study area. (USGS)

Lambing, J.H.

1984-01-01

355

Estimating Total Suspended Sediment Yield With Probability Sampling  

Microsoft Academic Search

ment record. The tested combinations of estimation technique and data collection method ranged from 70% below to 40% above the true value. Most of the estimates were less than 60% of the correct value. The variance of the estimators tended to increase as the accuracy improved, thus cancelling the benefits, and no approach emerged as the ideal choice for all

Robert B. Thomas

1985-01-01

356

ACUTE TOXICITY OF SEDIMENT FROM EAGLE HARBOR, WASHINGTON, TO THE INFAUNAL AMPHIPOD RHEPOXYNIUS ABRONIUS  

EPA Science Inventory

Creosote-contaminated sediment from one station (EH08) in Eagle Harbor, Washington, is among the most toxic sediment yet tested from U.S. estuaries and coastal waters. he total concentration of 13 polynuclear aromatic hydrocarbons in EH08 sediment was 6,461 mg/kg (dry wt.). he cn...

357

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

E-print Network

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

McGee, David

358

Distribution and fate of organochlorine pesticide residues in sediments from the selected rivers in Taiwan  

Microsoft Academic Search

The contamination of organochlorine pesticides (OCPs) in sediments from selected rivers in Taiwan was investigated to evaluate the pollution potentials and hazard in river sediments. Da-han River and Erh-jen River were selected as the target rivers due to their serious pollution. A total of 40 surface sediment samples were collected at five sampling stations along the rivers. Results showed that

Ruey-An Doong; Yuh-Chang Sun; Pei-Ling Liao; Ching-Kai Peng; Shian-Chee Wu

2002-01-01

359

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

EPA Science Inventory

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

360

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

EPA Science Inventory

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

361

Linkage of sediment supply and transport processes in Miyagawa Dam catchment, Japan  

Microsoft Academic Search

Linkages between sediment supply by episodic geomorphic processes (obtained from aerial photographs and field surveys) and sediment transport (estimated from changes in sediment deposition behind a large dam) were investigated in the Miyagawa Dam catchment, central Japan. A total of 6667 landslides were confirmed in the period from 1965 to 2000 on the basis of seven temporal pairs of aerial

Fumitoshi Imaizumi; Roy C. Sidle

2007-01-01

362

Millennial lag times in the Himalayan sediment routing system  

NASA Astrophysics Data System (ADS)

Any understanding of sediment routing from mountain belts to their forelands and offshore sinks remains incomplete without estimates of intermediate storage that decisively buffers sediment yields from erosion rates, attenuates water and sediment fluxes, and protects underlying bedrock from incision. We quantify for the first time the sediment stored in >38 000 mainly postglacial Himalayan valley fills, based on an empirical volume-area scaling of valley-fill outlines automatically extracted from digital topographic data. The estimated total volume of 690(/-242+452) km is mostly contained in few large valley fills >1 km, while catastrophic mass wasting adds another 177(±31) km. Sediment storage volumes are highly disparate along the strike of the orogen. Much of the Himalaya's stock of sediment is sequestered in glacially scoured valleys that provide accommodation space for ?44% of the total volume upstream of the rapidly exhuming and incising syntaxes. Conversely, the step-like long-wave topography of the central Himalayas limits glacier extent, and thus any significant glacier-derived storage of sediment away from tectonic basins. We show that exclusive removal of Himalayan valley fills could nourish contemporary sediment flux from the Indus and Brahmaputra basins for >1 kyr, though individual fills may attain residence times of >100 kyr. These millennial lag times in the Himalayan sediment routing system may sufficiently buffer signals of short-term seismic as well as climatic disturbances, thus complicating simple correlation and interpretation of sedimentary archives from the Himalayan orogen, its foreland, and its submarine fan systems.

Blöthe, Jan Henrik; Korup, Oliver

2013-11-01

363

Risk of Gastrointestinal Disease Associated with Exposure to Pathogens in the Sediments of the Lower Passaic River?  

PubMed Central

High levels of pathogenic microorganisms have been documented previously in waters of the Lower Passaic River in northern New Jersey. The purpose of this study was to characterize the microbial contamination of river sediments near combined sewer overflows (CSOs), a known source of pathogens. Concentrations of fecal coliform, total coliform, fecal Streptococcus, fecal Enterococcus, Pseudomonas aeruginosa, Staphylococcus aureus, Giardia lamblia, and Cryptosporidium parvum organisms were measured in 16 samples from three mudflat locations along the Lower Passaic River, as well as from an upstream location. Selected samples were also analyzed for antibiotic resistance. All of the samples contained high concentrations of total coliform, fecal coliform, fecal Streptococcus, and fecal Enterococcus organisms. Analysis of isolates of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli from several samples indicated that each strain was resistant to at least one antibiotic typically used in clinical settings. Eight of 16 samples contained Giardia, and one sample contained Cryptosporidium. With these sampling data, a quantitative microbial risk assessment was conducted to evaluate the probability of infection or illness resul