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Sample records for sediment distribution coefficients

  1. Distribution coefficient of plutonium between sediment and seawater

    International Nuclear Information System (INIS)

    Duursma, E.K.; Parsi, P.

    1974-01-01

    Using plutonium 237 as a tracer, a series of experiments were conducted to determine the distribution coefficient of plutonium onto sediments both under oxic and anoxic conditions, where the plutonium was added to seawater in three different valence states: III, IV and VI

  2. Sediment pore water distribution coefficients of PCB congeners in enriched black carbon sediment

    International Nuclear Information System (INIS)

    Martinez, Andres; O'Sullivan, Colin; Reible, Danny; Hornbuckle, Keri C.

    2013-01-01

    More than 2300 sediment pore water distribution coefficients (K PCBids ) of 93 polychlorinated biphenyls (PCBs) were measured and modeled from sediments from Indiana Harbor and Ship Canal. K PCBids were calculated from previously reported bulk sediment values and newly analyzed pore water. PCBs in pore waters were measured using SPME PDMS-fiber and ∑PCB ranged from 41 to 1500 ng L −1 . The resulting K PCBids were ∼1 log unit lower in comparison to other reported values. A simple model for the K PCBid consisted of the product of the organic carbon fraction and the octanol–water partition coefficient and provided an excellent prediction for the measured values, with a mean square error of 0.09 ± 0.06. Although black carbon content is very high in these sediments and was expected to play an important role in the distribution of PCBs, no improvement was obtained when a two-carbon model was used. -- Highlights: •PCB sediment-pore water distribution coefficients were measured and modeled. •Distribution coefficients were lower in comparison to other reported values. •Organic carbon fraction times the K OW yielded the best prediction model. •The incorporation of black carbon into a model did not improve the results. -- The organic carbon fraction times the octanol–water partition coefficient yielded the best prediction model for the sediment pore water distribution coefficient of PCBs

  3. Determination of distribution coefficient (Kd's) of some artificial and naturally occurring radionuclide in fresh and marine coastal water sediment

    International Nuclear Information System (INIS)

    Al-Masri, M. S.; Mamish, S; Haleem, M. A.

    2004-12-01

    Distribution coefficients of artificial and natural radionuclides in fresh and marine water sediment are used in modeling radionuclide dispersion in water system, and the radiation risk and environmental investigating of impact of radioactive emissions, due to routine operations of nuclear plants or disposal and burial of radioactive waste in the environment. In the present work, distribution coefficient of uranium, lead, polonium, radium (naturally occurring radionuclides that may be emitted into the Syrian environment by the phosphate and oil industry with relatively high concentrations) and caesium 137 and strontium 85, in fresh water sediment (Euphrates River, Orantos River and Mzzerib Lake) and marine coastal water (Lattakia, Tartous and Banias). Distribution coefficients were found to vary between (5.8-17.18)*10 3 , (2.2-8.11)*10 3 , (0.22-2.08)*10 3 , (0.16-0.19)*10 3 , (0.38-0.69)*10 3 and 49-312 for polonium, lead, uranium, radium, cesium and strontium respectively. Results have indicated that most measurement distribution coefficients in the present study were lower than those values reported in IAEA documents for marine coastal sediment. In addition, variations of Kd's with aqueous phase composition and sediment elemental and mineralogical composition and its total organic materials content have been studied, where liner correlation coefficients for each isotope with different parameters have been determined. The obtained data reported in this study can be used for radioactive contaminants dispersion and transfer in Syrian river, lake and coast to assess risks to public due to discharges of the phosphate and oil industry into the Syrian environment. (Authors)

  4. Radionuclide adsorption distribution coefficients measured in Hanford sediments for the low level waste performance assessment project

    International Nuclear Information System (INIS)

    Kaplan, D.I.; Serne, R.J.; Owen, A.T.

    1996-08-01

    Preliminary modeling efforts for the Hanford Site's Low Level Waste-Performance Assessment (LLW PA) identified 129 I, 237 Np, 79 Se, 99 Tc, and 234 , 235 , 238 U as posing the greatest potential health hazard. It was also determined that the outcome of these simulations was very sensitive to the parameter describing the extent to which radionuclides sorb to the subsurface matrix, i.e., the distribution coefficient (K d ). The distribution coefficient is a ratio of the radionuclide concentration associated with the solid phase to that in the liquid phase. The objectives of this study were to (1) measure iodine, neptunium, technetium, and uranium K d values using laboratory conditions similar to those expected at the LLW PA disposal site, and (2) evaluate the effect of selected environmental parameters, such as pH, ionic strength, moisture concentration, and radio nuclide concentration, on K d values of selected radionuclides. It is the intent of these studies to develop technically defensible K d values for the PA. The approach taken throughout these studies was to measure the key radio nuclide K d values as a function of several environmental parameters likely to affect their values. Such an approach provides technical defensibility by identifying the mechanisms responsible for trends in K d values. Additionally, such studies provide valuable guidance regarding the range of K d values likely to be encountered in the proposed disposal site

  5. Determination of distribution coefficients for 134 Cs, 60 Co and 234 Th radionuclides in Pinheiro river sediment

    International Nuclear Information System (INIS)

    Lima, M.F.

    1992-01-01

    The distribution coefficients (K α) were determined in order to foresee the fate of the radionuclides discharged to the environment. Based upon the source-term released by IPEN's facilities in Pinheiros River during the year of 1988, three radionuclides were chosen as being the more critical, according to the radiation protection standards: 137 Cs, 60 Co and 232 Th. Their K α were determined experimentally in laboratory by using the corresponding radioactive tracers 134 Cs, 60 Co and 234 Th. Three different experimental methodologies were used: the static method, the shaken method and the dynamic method. The parameters studied were the effects of pH, aerobic condition and time of contact. The results obtained experimentally for the Kds confirm the predictions that: the cesium is slowly retained by the sediment along the Pinheiros River, the cobalt is an unstable element, therefore its retention by the sediment is affected by variations in the pH values, and finally, the thorium is almost completely retained in the vicinity of the discharge point. (author)

  6. Determination of the distribution coefficients for the radionuclides 134Cs, 60Co and 234Th in the Pinheiros river sediment

    International Nuclear Information System (INIS)

    Lima, Marina Ferreira

    1992-01-01

    The distribution coefficients (Kd) were determined in order to foresee the fate of the radionuclides discharged to the environment. Based upon the source-term released by IPEN's facilities in Pinheiros River during the year of 1988, three radionuclides were chosen as being the more critical, according to the radiation protection standards: 137 Cs, 60 Co and 232 Th. Their Kd were determined experimentally in laboratory by using the corresponding radioactive tracers 134 Cs, 60 Co and 234 Th. Three different experimental methodologies were used: the static method. the shaken method and the dynamic method. The parameters studied were the effects of pH, aerobic condition and time of contact. No considerable changes were observed for the cesium Kd with the variation of pH and aerobic condition, the kd extreme values being 20 ml/g and 30 ml/g for the pH range between 4 and 8. The study of the time of contact showed that the equilibrium between the cesium concentration in the water and sediment was achieved in a few days. For the cobalt, the pH effect was considerable, since the Kd increased from 46 ml/g for pH 4 to 2,25x10 3 ml/g for pH 8. The Kd observed with the agitation with air was around 420 ml/g, rising to 670 ml/g with the agitation with N 2 . The results obtained in the study of the time of contact effect showed that the equilibrium between the cobalt concentration in the water and sediment was not achieved even after 15 days of contact. For the thorium, also, the pH effect was considerable, since the Kd increased fram 1,40 x 10 5 ml/g for pH 4 to 2,55 x 10 6 ml/g for pH 8. No effect was observed, on the other hand, for the kd values obtained in the experiment carried out with air agitation or N 2 agitation, around 2,75 x 10 6 ml/g. The results obtained in the study of the time of contact effect showed that the equilibrium between the thorium concentration in the water and sediment was achieved after just one hour of contact. The results obtained can be

  7. Determination of sedimentation rates and absorption coefficient of ...

    African Journals Online (AJOL)

    DR. MIKE HORSFALL

    particles have pores that can absorb radiation. Gamma rays have been used to study the absorption coefficients of cobalt(II) insoluble compounds (Essien and Ekpe, 1998), densities of marine sediments. (Gerland and Villinger, 1995) and soil particle-size distribution (Vaz et al., 1992). In this study, sedimentation rates of ...

  8. Geochemical and physical properties, distribution coefficients of soils and sediments at the Olkiluoto Island and in the reference area in 2010-2011

    International Nuclear Information System (INIS)

    Lahdenperae, A.-M.

    2014-04-01

    The report summarises the chemical, physical and mineralogical data and the calculated 'in situ' distribution coefficients (K d ) values of the indigenous elements from the different types of soil and sediment samples at the Olkiluoto Island and in the Reference area that were taken in 2010-2011. The data has been collected in order to extend the understanding of the site evolution and for radionuclide transport analyses and modelling. 'In situ' distribution coefficients, K d values are used to indicate the relevant mobility of elements and radionuclides. This report is part of the entirety of soil and sediment data from different soil types, soil layers and environmental conditions collected earlier for the biosphere site description and development. Soil and sediment samples were taken at various depths of humus, peat, gyttja, sandy/fine sandy till and cropland soils. The analyses procedure varied to some extent between the samples. In all samples were analysed pH, LOI, C, N, and the total concentrations of the elements using HNO 3 -HF extraction. The 'in situ' K d values were calculated using the formula by Sheppard et al.. For selected samples the easily leachable fraction was analysed by NH 4 Ac (pH 4.5). Bulk density and mineralogy was determined for a few samples. Grain size distribution was measured only from till samples. The results are discussed and the physical-chemical data and distribution coefficients of the results are presented. The cation exchange capacity and base saturation are calculated for the sandy/fine sandy till samples from Olkiluoto. The K d values of the important indigenous elements Ag, Cl, Cs, I, Mo, Ni, Se and Sr are of main interest in biosphere development due to the longest half-lives of the associated radionuclides, thus having long interaction times. The K d data are inherently extremely variable due to nature of practical quantity in question, aggregating a number of processes into a single value, but the data also vary

  9. Geochemical and physical properties, distribution coefficients of soils and sediments at the Olkiluoto Island and in the reference area in 2010-2011

    Energy Technology Data Exchange (ETDEWEB)

    Lahdenperae, A.-M. [Saanio and Riekkola Oy, Helsinki (Finland)

    2014-04-15

    The report summarises the chemical, physical and mineralogical data and the calculated 'in situ' distribution coefficients (K{sub d}) values of the indigenous elements from the different types of soil and sediment samples at the Olkiluoto Island and in the Reference area that were taken in 2010-2011. The data has been collected in order to extend the understanding of the site evolution and for radionuclide transport analyses and modelling. 'In situ' distribution coefficients, K{sub d} values are used to indicate the relevant mobility of elements and radionuclides. This report is part of the entirety of soil and sediment data from different soil types, soil layers and environmental conditions collected earlier for the biosphere site description and development. Soil and sediment samples were taken at various depths of humus, peat, gyttja, sandy/fine sandy till and cropland soils. The analyses procedure varied to some extent between the samples. In all samples were analysed pH, LOI, C, N, and the total concentrations of the elements using HNO{sub 3}-HF extraction. The 'in situ' K{sub d} values were calculated using the formula by Sheppard et al.. For selected samples the easily leachable fraction was analysed by NH{sub 4}Ac (pH 4.5). Bulk density and mineralogy was determined for a few samples. Grain size distribution was measured only from till samples. The results are discussed and the physical-chemical data and distribution coefficients of the results are presented. The cation exchange capacity and base saturation are calculated for the sandy/fine sandy till samples from Olkiluoto. The K{sub d} values of the important indigenous elements Ag, Cl, Cs, I, Mo, Ni, Se and Sr are of main interest in biosphere development due to the longest half-lives of the associated radionuclides, thus having long interaction times. The K{sub d} data are inherently extremely variable due to nature of practical quantity in question, aggregating a number of

  10. Development of database on the distribution coefficient. 1. Collection of the distribution coefficient data

    Energy Technology Data Exchange (ETDEWEB)

    Takebe, Shinichi; Abe, Masayoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    The distribution coefficient is very important parameter for environmental impact assessment on the disposal of radioactive waste arising from research institutes. The literature survey in the country was mainly carried out for the purpose of selecting the reasonable distribution coefficient value on the utilization of this value in the safety evaluation. This report was arranged much informations on the distribution coefficient for inputting to the database for each literature, and was summarized as a literature information data on the distribution coefficient. (author)

  11. Sediment distribution coefficients (KD) and concentration factors (CF) in fish for natural radionuclides in a pond of a tropical region and their contributions to estimations of internal absorbed dose rate in fish

    International Nuclear Information System (INIS)

    Souza Pereira, Wagner de; Kelecom, Alphonse

    2008-01-01

    Attention has been paid only recently to the protection of biota against radiation effects. Protection is being considered through modeling of the calculation of absorbed dose rate. In these models, the inputs are the fluxes of radionuclides of environmental concern and their resulting distribution between environmental compartments. Such distribution is estimated for dispersion models. In freshwater systems and when fish is used as biomaker, relevant environmental transfer parameters are transfer between sediment and water (sediment distribution coefficients KD, in l kg -1 ), and between water and fish (concentration factor CF, in l kg -1 ). These coefficients are under the influence of a number o physical, chemical and biological factors, and display following the literature a great variability. The present work establishes the KD's and CF's for uranium, thorium, radium and lead for two ponds: one that receives treated effluents from an ore treatment unit (UTM) situated at Pocos de Caldas, Minas Gerais, Brazil and the other pond from the uranium concentration unit (URA) situated at Caetite, Bahia, Brazil, and for fish used as biomarker. It intends also to compare these parameters with the values recommended by IAEA. Depending on considered radionuclide and on the site, CF's (l kg -1 ) observed values were of the same magnitude as, or one order of magnitude lower than recommended by IAEA. KD's (l kg -1 ) observed values were found of the same magnitude as those recommended by IAEA, approximately 10 times lower or up to 100 times higher than recommended by IAEA, again depending on the radionuclides and on the site. It can be concluded that local parameters should be established in order to obtain a more accurate estimative of biota exposition from man activities. (author)

  12. Development of a predictive model for distribution coefficient (Kd) of 13'7Cs and 60Co in marine sediments using multiple linear regression analysis

    International Nuclear Information System (INIS)

    Kumar, Ajay; Ravi, P.M.; Guneshwar, S.L.; Rout, Sabyasachi; Mishra, Manish K.; Pulhani, Vandana; Tripathi, R.M.

    2018-01-01

    Numerous common methods (batch laboratory, the column laboratory, field-batch method, field modeling and K 0c method) are used frequently for determination of K d values. Recently, multiple regression models are considered as new best estimates for predicting the K d of radionuclides in the environment. It is also well known fact that the K d value is highly influenced by physico-chemical properties of sediment. Due to the significant variability in influencing parameters, the measured K d values can range over several orders of magnitude under different environmental conditions. The aim of this study is to develop a predictive model for K d values of 137 Cs and 60 Co based on the sediment properties using multiple linear regression analysis

  13. Apparent distribution coefficients of transuranium elements in UK coastal waters

    International Nuclear Information System (INIS)

    Kershaw, P.J.; Pentreath, R.J.; Harvey, B.R.; Lovett, M.B.; Boggis, S.J.

    1986-01-01

    The authorized inputs of low-level radioactive waste into the Irish Sea from the British Nuclear Fuels plc reprocessing plant at Sellafield may be used to advantage to study the distribution and behaviour of artificial radionuclides in the marine environment. Apparent distribution coefficients (Ksub(d)) for the transuranium elements Np, Pu, Am and Cm have been determined by the analysis of environmental samples collected from UK coastal waters. The sampling methodology for obtaining suspended sediment-seawater Ksub(d)s by filtration is described and critically evaluated. Artefacts may be introduced in the sample collection stage. Ksub(d) values have also been determined for seabed sediment-interstitial waters and the precautions taken to preserve in-situ chemical conditions are described. Variations in Ksub(d) values are discussed in relation to distance from Sellafield, suspended load, redox conditions and oxidation state changes. (author)

  14. Study on the distribution coefficient during environmental impact evaluation in Chinese inland nuclear power plants

    International Nuclear Information System (INIS)

    Xu Haifeng; Shang Zhaorong; Chen Fangqiang

    2012-01-01

    Description the radionuclide distribution coefficient of the important factors in the river sediment systems, at home and abroad the main method of measuring the K d value and progress in China's inland nuclear power plant environmental impact assessment of workers to carry out the distribution coefficient K d value measurement ideas put forward recommendations. (authors)

  15. Effects of calcium and magnesium on strontium distribution coefficients

    Science.gov (United States)

    Bunde, R.L.; Rosentreter, J.J.; Liszewski, M.J.; Hemming, C.H.; Welhan, J.

    1997-01-01

    The effects of calcium and magnesium on the distribution of strontium between a surficial sediment and simulated wastewater solutions were measured as part of an investigation to determine strontium transport properties of surficial sediment at the Idaho National Engineering Laboratory (INEL), Idaho. The investigation was conducted by the U.S. Geological Survey and Idaho State University, in cooperation with the U.S. Department of Energy. Batch experimental techniques were used to determine strontium linear sorption isotherms and distribution coefficients (K(d)'s) using simulated wastewater solutions prepared at pH 8.0??0.1 with variable concentrations of calcium and magnesium. Strontium linear sorption isotherm K(d)'s ranged from 12??1 to 85??3 ml/g, increasing as the concentration of calcium and magnesium decreased. The concentration of sorbed strontium and the percentage of strontium retained by the sediment were correlated to aqueous concentrations of strontium, calcium, and magnesium. The effect of these cation concentrations on strontium sorption was quantified using multivariate least-squares regression techniques. Analysis of data from these experiments indicates that increased concentrations of calcium and magnesium in wastewater discharged to waste disposal ponds at the INEL increases the availability of strontium for transport beneath the ponds by decreasing strontium sorption to the surficial sediment.

  16. The distribution coefficient concept and aspects on experimental distribution studies

    International Nuclear Information System (INIS)

    Allard, B.; Andersson, K.; Torstenfelt, B.

    1983-01-01

    Aspects on the distribution coefficient concept, sorption mechanisms and measurements of sorption phenomena are given. The distribution constant was shown to be pH-dependent. The temperature dependence of the sorption has been studied. The influence of the liquid/solid ratio has been studied for Cs and Sr. (G.B.)

  17. Distribution coefficients for plutonium and americium on particulates in aquatic environments

    International Nuclear Information System (INIS)

    Sanchez, A.L.; Schell, W.R.; Sibley, T.H.

    1982-01-01

    The distribution coefficients of two transuranic elements, plutonium and americium, were measured experimentally in laboratory systems of selected freshwater, estuarine, and marine environments. Gamma-ray emitting isotopes of these radionuclides, 237 Pu and 241 Am, were significantly greater than the sorption Ksub(d) values, suggesting some irreversibility in the sorption of these radionuclides onto sediments. The effects of pH and of sediment concentration on the distribution coefficients were also investigated. There were significant changes in the Ksub(d) values as these parameters were varied. Experiments using sterilized and nonsterilized samples for some of the sediment/water systems indicate possible bacterial effects on Ksub(d) values. (author)

  18. Soil nuclide distribution coefficients and their statistical distributions

    International Nuclear Information System (INIS)

    Sheppard, M.I.; Beals, D.I.; Thibault, D.H.; O'Connor, P.

    1984-12-01

    Environmental assessments of the disposal of nuclear fuel waste in plutonic rock formations require analysis of the migration of nuclides from the disposal vault to the biosphere. Analyses of nuclide migration via groundwater through the disposal vault, the buffer and backfill, the plutonic rock, and the consolidated and unconsolidated overburden use models requiring distribution coefficients (Ksub(d)) to describe the interaction of the nuclides with the geological and man-made materials. This report presents element-specific soil distribution coefficients and their statistical distributions, based on a detailed survey of the literature. Radioactive elements considered were actinium, americium, bismuth, calcium, carbon, cerium, cesium, iodine, lead, molybdenum, neptunium, nickel, niobium, palladium, plutonium, polonium, protactinium, radium, samarium, selenium, silver, strontium, technetium, terbium, thorium, tin, uranium and zirconium. Stable elements considered were antimony, boron, cadmium, tellurium and zinc. Where sufficient data were available, distribution coefficients and their distributions are given for sand, silt, clay and organic soils. Our values are recommended for use in assessments for the Canadian Nuclear Fuel Waste Management Program

  19. Diffusion-Coefficients of Sulfate and Methane in Marine-Sediments - Influence of Porosity

    DEFF Research Database (Denmark)

    IVERSEN, N.; JØRGENSEN, BB

    1993-01-01

    diffusion coefficients can be related to the diffusion coefficient in free solution by D(s) = D(o)/theta2, where theta is the tortuosity of the sediment. The sediment tortuosity calculated from this equation showed a linear relationship with sediment porosity (phi) over the porosity range of 0.4-0.9. From...

  20. An Investigation of the Sampling Distribution of the Congruence Coefficient.

    Science.gov (United States)

    Broadbooks, Wendy J.; Elmore, Patricia B.

    This study developed and investigated an empirical sampling distribution of the congruence coefficient. The effects of sample size, number of variables, and population value of the congruence coefficient on the sampling distribution of the congruence coefficient were examined. Sample data were generated on the basis of the common factor model and…

  1. Determination of sedimentation rates and absorption coefficient of ...

    African Journals Online (AJOL)

    2+ has a higher sedimentation rate of 5.10x10-2 s-1 while Ni2+ has the lowest sedimentation rates of 1.10 x10-3. The rate of sedimentation of the metal carbonates decreased in the order: Zn2+ > Cd2+ > Cu2+ > Co2+ > Ni2+. The order ...

  2. Coefficient Omega Bootstrap Confidence Intervals: Nonnormal Distributions

    Science.gov (United States)

    Padilla, Miguel A.; Divers, Jasmin

    2013-01-01

    The performance of the normal theory bootstrap (NTB), the percentile bootstrap (PB), and the bias-corrected and accelerated (BCa) bootstrap confidence intervals (CIs) for coefficient omega was assessed through a Monte Carlo simulation under conditions not previously investigated. Of particular interests were nonnormal Likert-type and binary items.…

  3. Radionuclides distribution coefficient of soil to soil-solution

    International Nuclear Information System (INIS)

    1990-06-01

    The present book addresses various issues related with the coefficient of radionuclides distribution between soil and soil solution. It consists of six sections and two appendices. The second section, following an introductory one, describes the definition of the coefficient and a procedures of its calculation. The third section deals with the application of the distribution coefficient to the prediction of movements of radionuclides through soil. Various methods for measuring the coefficient are described in the fourth section. The next section discusses a variety of factors (physical and chemical) that can affect the distribution coefficient. Measurements of the coefficient for different types of oils are listed in the sixth section. An appendix is attached to the book to show various models that can be helpful in applying the coefficient of distribution of radionuclides moving from soil into agricultural plants. (N.K.)

  4. An Investigation of the Sampling Distributions of Equating Coefficients.

    Science.gov (United States)

    Baker, Frank B.

    1996-01-01

    Using the characteristic curve method for dichotomously scored test items, the sampling distributions of equating coefficients were examined. Simulations indicate that for the equating conditions studied, the sampling distributions of the equating coefficients appear to have acceptable characteristics, suggesting confidence in the values obtained…

  5. Unconsolidated sediment distribution patterns in the KwaZulu-Natal ...

    African Journals Online (AJOL)

    Seasonal changes in sediment distribution patterns are small, being restricted to seaward fining on the inner shelf off the fluvial sources. Sediment distribution reflects a partitioning between sediment populations that are currentinfluenced and relict (palimpsest) populations associated with submerged shorelines.

  6. measurements of distribution coefficients and lipophilicity values

    African Journals Online (AJOL)

    Preferred Customer

    octanol and water, followed by measuring the distribution of the solute in ... Instrumentation and apparatus: HPLC-UV-DAD and HPLC–ESI-MS experiments .... process in the determination of KD and log P values for the HFSLM extracts. ..... Perrin, D.D.; Dempsey, B. Buffers for pH and Metal Ion Control, Chapman and Hall:.

  7. Sediment-to-Water Partition Coefficients: the Influence of Physicochemical and Seasonal Factors in Eastern Ontario

    Energy Technology Data Exchange (ETDEWEB)

    Yankovich, Tamara L. [International Atomic Energy Agency, P.O. Box 100, 1400 Vienna (Austria); Shultz, Carmen; Hartwig, Dale; Wills, C. Anne [Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, Ontario, K0J 1J0 (Canada); Beresford, Nicholas A. [NERC Centre for Ecology and Hydrology, Lancaster Environment Center, Library Av., Bailrigg, Lancaster, LA1 4AP (United Kingdom); School of Environment and Life Sciences, University of Salford, Manchester, M4 4WT (United Kingdom); Wood, Michael D. [School of Environment and Life Sciences, University of Salford, Manchester, M4 4WT (United Kingdom)

    2014-07-01

    Sediments often represent an important reservoir for contaminants, such as radionuclides and metals, in aquatic ecosystems. Consequently, lake, stream, and river sediments can potentially act as significant contributors to the total contaminant exposure and radiological doses received by wildlife. Exposure to contaminated sediments is dependent upon several factors. These include net contaminant inputs to a system through time, the physicochemical attributes of the system, the tendency of each contaminant to partition into the sediments relative to water, the spatial distribution of contaminants in the sediments, and the behaviour or life-style of the biota inhabiting a water body. Increased understanding of such factors and their interactions will lead to improved predictions of the radionuclide exposure received by aquatic biota, particularly benthic organisms. Despite the complexity and the dynamic nature of sediments in general, for practical purposes, in environmental impact assessments (EIAs), it is often assumed that radionuclide activity concentrations in various compartments are at steady state with respect to one another. Therefore, ratios can be used to estimate concentrations in one compartment given a known concentration in another. In the case of sediments, sediment-to-water partition coefficients (K{sub d}) are often applied to estimate the contaminant concentration sorbed to particulate matter relative to the concentration measured in the surface water. However, K{sub d} values often range by several orders of magnitude between sampling locations due to site-specific differences in physicochemical conditions in surface waters, seasonal factors, as well as differences in sediment attributes that can affect contaminant partitioning between the dissolved and particulate phases. Consequently, in conducting EIAs, it becomes necessary to either apply generic K{sub d} values that ensure contaminant concentrations in sediments to which biota are exposed are

  8. Questionnaire on the measurement condition of distribution coefficient

    International Nuclear Information System (INIS)

    Takebe, Shinichi; Kimura, Hideo; Matsuzuru, Hideo

    2001-05-01

    The distribution coefficient is used for various transport models to evaluate the migration behavior of radionuclides in the environment and is very important parameter in environmental impact assessment of nuclear facility. The questionnaire was carried out for the purpose of utilizing for the proposal of the standard measuring method of distribution coefficient. This report is summarized the result of questionnairing on the sampling methods and storage condition, the pretreatment methods, the analysis items in the physical/chemical characteristics of the sample, and the distribution coefficient measuring method and the measurement conditions in the research institutes within country. (author)

  9. Confidence bounds for normal and lognormal distribution coefficients of variation

    Science.gov (United States)

    Steve Verrill

    2003-01-01

    This paper compares the so-called exact approach for obtaining confidence intervals on normal distribution coefficients of variation to approximate methods. Approximate approaches were found to perform less well than the exact approach for large coefficients of variation and small sample sizes. Web-based computer programs are described for calculating confidence...

  10. Distributing Correlation Coefficients of Linear Structure-Activity/Property Models

    Directory of Open Access Journals (Sweden)

    Sorana D. BOLBOACA

    2011-12-01

    Full Text Available Quantitative structure-activity/property relationships are mathematical relationships linking chemical structure and activity/property in a quantitative manner. These in silico approaches are frequently used to reduce animal testing and risk-assessment, as well as to increase time- and cost-effectiveness in characterization and identification of active compounds. The aim of our study was to investigate the pattern of correlation coefficients distribution associated to simple linear relationships linking the compounds structure with their activities. A set of the most common ordnance compounds found at naval facilities with a limited data set with a range of toxicities on aquatic ecosystem and a set of seven properties was studied. Statistically significant models were selected and investigated. The probability density function of the correlation coefficients was investigated using a series of possible continuous distribution laws. Almost 48% of the correlation coefficients proved fit Beta distribution, 40% fit Generalized Pareto distribution, and 12% fit Pert distribution.

  11. Energy distribution for Coefficients of Redundant Signal Representations of Music

    DEFF Research Database (Denmark)

    Endelt, Line Ørtoft; la Cour-Harbo, Anders

    2005-01-01

    different time-frequency dictionaries. We have applied these methods to music to examine their ability to express music signals in a sparse manner for a number of dictionaries and window lengths. The evaluation is based on the m-term approximation needed to represent 90 %, 95 %, 99 % and 99......In this paper we investigate how the energy is distributed in the coefficients vector of various redundant signal representations of music signals. The representations are found using Basis Pursuit, Matching Pursuit, Alternating Projections, Best Orthogonal Basis and Method of Frames, with five.......9 % of the energy in the coefficients, also the time consummation for finding the representations are considered. The distribution of energy in the coefficients of the representations found using Basis Pursuit, Matching Pursuit, Alternating Projections and Best Orthogonal Basis depends mainly on the signal...

  12. Estimates of the Sampling Distribution of Scalability Coefficient H

    Science.gov (United States)

    Van Onna, Marieke J. H.

    2004-01-01

    Coefficient "H" is used as an index of scalability in nonparametric item response theory (NIRT). It indicates the degree to which a set of items rank orders examinees. Theoretical sampling distributions, however, have only been derived asymptotically and only under restrictive conditions. Bootstrap methods offer an alternative possibility to…

  13. Correlation of Cadmium Distribution Coefficients to Soil Characteristics

    DEFF Research Database (Denmark)

    Holm, Peter Engelund; Rootzen, Helle; Borggaard, Ole K.

    2003-01-01

    on whole soil samples have shown that pH is the main parameter controlling the distribution. To identify further the components that are important for Cd binding in soil we measured Cd distribution coefficients (K-d) at two fixed pH values and at low Cd loadings for 49 soils sampled in Denmark. The Kd...... values for Cd ranged from 5 to 3000 L kg(-1). The soils were described pedologically and characterized in detail (22 parameters) including determination of contents of the various minerals in the clay fraction. Correlating parameters were grouped and step-wise regression analysis revealed...... interlayered clay minerals [HIM], chlorite, quartz, microcline, plagioclase) were significant in explaining the Cd distribution coefficient....

  14. Distribution of temperature coefficient density for muons in the atmosphere

    Directory of Open Access Journals (Sweden)

    Kuzmenko V.S.

    2017-12-01

    Full Text Available To date, several dozens of new muon detectors have been built. When studying cosmic-ray intensity variations with these detectors, located deep in the atmosphere, it is necessary to calculate all characteristics, including the distribution of temperature coefficient density for muons in the atmosphere, taking into account their specific geometry. For this purpose, we calculate the density of temperature coefficients of muon intensity in the atmosphere at various zenith angles of detection at sea level and at various depths underground for different absorption ranges of primary protons and pions in the atmosphere.

  15. Sediment sources and their Distribution in Chwaka Bay, Zanzibar ...

    African Journals Online (AJOL)

    This work establishes sediment sources, character and their distribution in Chwaka Bay using (i) stable isotopes compositions of organic carbon (OC) and nitrogen, (ii) contents of OC, nitrogen and CaCO3, (iii) C/N ratios, (iv) distribution of sediment mean grain size and sorting, and (v) thickness of unconsolidated sediments.

  16. Measurement of the distribution coefficient between soil and Cesium-137

    International Nuclear Information System (INIS)

    Tejada V, S.; Hernandez P, M.

    1996-01-01

    The measurement of the distribution coefficient of Cs-137 is currently performed by batch method between radioisotope solution and which was collected from the Mexican Disposal Site, near the town of Maquixco, in the state of Mexico. The Kd values were obtained in activity concentration of Cs-137 of 100 Bq. The solution is shaken for seven days at 25 o C when the maximum amount of radionuclide is absorbed by the soil. The radionuclide in solution is measured by gamma spectrometry. The results obtained from batch method show that the distribution coefficients were from 144 to 660 ml/g for fine soil particles. This work is currently done as part of the site characterization studies for the disposal of low level rad-waste. (authors). 10 refs., 2 tabs

  17. Estimation of the effective distribution coefficient from the solubility constant

    International Nuclear Information System (INIS)

    Wang, Yug-Yea; Yu, C.

    1994-01-01

    An updated version of RESRAD has been developed by Argonne National Laboratory for the US Department of Energy to derive site-specific soil guidelines for residual radioactive material. In this updated version, many new features have been added to the, RESRAD code. One of the options is that a user can input a solubility constant to limit the leaching of contaminants. The leaching model used in the code requires the input of an empirical distribution coefficient, K d , which represents the ratio of the solute concentration in soil to that in solution under equilibrium conditions. This paper describes the methodology developed to estimate an effective distribution coefficient, Kd, from the user-input solubility constant and the use of the effective K d for predicting the leaching of contaminants

  18. Study of distribution coefficients of admixtures in tellurium

    International Nuclear Information System (INIS)

    Kuchar, L.; Drapala, J.; Kuchar, L. jr.

    1986-01-01

    Limit areas of tellurium-admixture binary systems were studied and the values determined of steady-state distribution coefficients of admixtures. A second order polynomial was used to express equations of solidus and liquidus curves for Te-Se, Te-S, Te-Hg systems; the curves are graphically represented. The most effective method for preparing high-purity tellurium is zonal melting with material removal. (M.D.). 4 figs., 4 tabs., 16 refs

  19. Distribution and transportation of suspended sediment

    International Nuclear Information System (INIS)

    Schubel, J.R.

    1975-01-01

    A number of studies of the distribution and character of suspended matter in the waters of the Atlantic shelf have documented the variations in the concentration of total suspended matter in both time and space. Very little is known, however, about the ultimate sources of inorganic suspended matter, and even less is known about the routes and rates of suspended sediment transport in shelf waters. Suspended particulate matter constitutes a potential vehicle for the transfer of energy-associated contaminants, radionuclides and oil, back to the coast and therefore to man. The concentrations of total suspended matter in shelf waters are typically so low, however, that the mechanism is ineffective. Studies of suspended particulate matter have a high scientific priority, but in this investigator's opinion the state of knowledge is adequate for preparation of the environmental impact statements that would be required for siting of offshore nuclear power plants and for oil drilling on the Atlantic Continental Shelf

  20. Estimating the in situ sediment-porewater distribution of PAHs and chlorinated aromatic hydrocarbons in anthropogenic impacted sediments

    Energy Technology Data Exchange (ETDEWEB)

    Hans Peter H. Arp; Gijs D. Breedveld; Gerard Cornelissen [Norwegian Geotechnical Institute (NGI), Oslo (Norway). Department of Environmental Engineering

    2009-08-15

    It has become increasingly apparent that the in situ sediment-porewater distribution behavior of organic compounds within anthropogenic impacted sediments is quite diverse, and challenging to generalize. Traditional models based on octanol-water partitioning generally overestimate native porewater concentrations, and modern approaches accounting for multiple carbon fractions, including black carbon, appear sediment specific. To assess the diversity of this sorption behavior, we collected all peer-reviewed total organic carbon (TOC)-normalized in situ sediment-porewater distribution coefficients, K{sub TOC}, for impacted sediments. This entailed several hundreds of data for PAHs, PCBs, PCDD/Fs, and chlorinated benzenes, covering a large variety of sediments, locations, and experimental methods. Compound-specific KTOC could range up to over 3 orders of magnitude. Output from various predictive models for individual carbonaceous phases found in impacted sediments, based on peer-reviewed polyparameter linear free energy relationships (PP-LFERs), Raoult's Law, and the SPARC online-calculator, were tested to see if any of the models could consistently predict literature K{sub TOC} values within a factor of 30 (i.e. about 1.5 orders of magnitude, or half the range of K{sub TOC} values). The Raoult's Law model and coal tar PP-LFER achieved the sought-after accuracy for all tested compound classes, and are recommended for general, regional-scale modeling purposes. As impacted sediment-porewater distribution models are unlikely to get more accurate than this, this review underpins that the only way to accurately obtain accurate porewater concentrations is to measure them directly, and not infer them from sediment concentrations. 86 refs., 2 figs., 3 tabs.

  1. Sediment-water distribution of perfluorooctane sulfonate (PFOS) in Yangtze River Estuary

    International Nuclear Information System (INIS)

    Pan Gang; You Chun

    2010-01-01

    Analysis of Perfluorooctane sulfonate (PFOS) distribution in water and sediment in Yangtze River Estuary showed that the estuary was a sink for PFOS. Salinity was an important parameter in controlling the sediment-water interactions and the fate or transport of PFOS in the aquatic environment. As the salinity (S per mille ) increased from 0.18 to 3.31, the distribution coefficient (K d ) between sediment and water linearly increased from 0.76 to 4.70 L g -1 . The study suggests that PFOS may be carried with the river water and transported for long distances before it reaches to the sea and largely scavenged to the sediment in the estuaries due to the dramatic change in salinity. - PFOS may be largely scavenged to the sediment in estuaries due to the dramatic change in salinity during its transport from lands to oceans.

  2. Distributions of radionuclides among green alga (Ulva pertusa), sea water and marine sediment

    International Nuclear Information System (INIS)

    Nakamura, Ryoichi; Suzuki, Yuzuru; Ueda, Taishi

    1976-01-01

    Distributions of radionuclides ( 60 Co, 137 Cs, 95 Zr- 95 Nb and 106 Ru- 106 Rh) among green alga (Ulva pertusa), sea water and marine sediment were examined by radioisotope tracer experiment in order to estimate the influence of sediment on the accumulation of radionuclides by the alga. By the application of the compartment model to the experimental results, exponential formulas of distributions were obtained. Through comparison of the transfer coefficients of radionuclides calculated from the exponential formulas, the influence of the sediment on the accumulation of the radionuclides by the green alga was determined to be the largest for 60 Co, followed by 95 Zr,- 95 Nb, 106 Ru- 106 Rh and 137 Cs in this order. The activity ratios of 95 Zr- 95 Nb and 106 Ru- 106 Rh calculated from the transfer coefficients are larger for the alga than for the sediment, inversely those of 60 Co and 137 Cs show higher values for the sediment than for the alga. Especially, in the case of 60 Co, the activity ratio for the sediment is approximately 20 times greater than that for the alga. Biological half lives in green alga estimated from the transfer coefficients were 10 days for 60 Co, 7 days for 137 Cs, 26 days for 95 Zr- 95 Nb and 24 days for 95 Zr- 95 Nb and 24 days for 106 Ru- 106 Rh. (auth.)

  3. Distribution of Radioisotopes between Phytoplankton, Sediment and Sea Water in a Dialysis Compartment System

    International Nuclear Information System (INIS)

    Dawson, R.; Duursma, E.K.

    1976-01-01

    The distribution of the radioisotopes 36 Cl, 54 Mn, 59 Fe, 60 Co, 65 Zn, 90 Sr, 106 Ru, 109 Cd, 110 mAg, 137 Cs, 144 Ce, 147 Pm and 204 Tl between sea water, Mediterranean sediment in suspension, and the phytoplankton species Phaeodactylum tricornutum was studied by using a competitive technique in which the various phases were separated by dialysis membranes. The radioisotopes were introduced into the sea water compartment and the radionuclide uptake by sediment and phytoplankton occurred in the adjoining compartments after the isotopes had diffused through the membranes. The diffusion through membranes is time dependent and related to the hydrated ion radii of the elements in solution. Chelation of the elements by organic matter from sewage may hamper this diffusion, although the complexing molecules themselves can pass through the membrane. The laboratory experiments showed that the uptake of radionuclides by sediments and phytoplankton in suspension did not occur independently of each other but in competition relative to the different affinities to the sediment and phytoplankton and relative to the concentrations of the particulate materials themselves. On examination of the distribution coefficients, the isotopes 90Sr, 110m Ag, 204 Ti and in particular 109 Cd, had higher affinities towards Phaeodactylum tricornutum than towards the Mediterranean sediment. The isotopes 54 Mn, 60 Co and 137 Cs had lower distribution coefficients with the phytoplankton than with sediment and in the case of 59 Fe, 65 Zn, l06 Ru, l 4 Ce and 147 Pm, the distribution coefficients were similar for both phytoplankton and sediment. Taking into account that many more factors play a role in the natural aquatic environment, the distribution pattern between water, plankton and sediment in suspension can be approximated by calculating the percentage distribution in the 3 phases. Those percentages are dependent on 2 parameters, being the distribution coefficients and the concentrations of the

  4. Radioactive pollution of the Chernobyl cooling pond bottom sediments. II. Distribution of 137Cs, 241Am, 90Sr in a solid phase

    Directory of Open Access Journals (Sweden)

    L. S. Pirnach

    2011-12-01

    Full Text Available The second part of complex research of the Chernobyl cooling pond bottom sediments are presented Data about vertical distribution of radioactive pollution 137Cs, 241Am, 90Sr in a solid phase of sediments are received. Distribution coefficients 137Cs and 90Sr, selectivity coefficients of their exchange with similar cations and physical-chemical forms are defined. Results of research of radionuclide chemical recovery from the sediment samples are analyzed.

  5. Comparison between theoretical basis and practical application of distribution coefficient

    International Nuclear Information System (INIS)

    Nevissi, A.E.

    1986-01-01

    In situ measurements of Ksub(d) for stable elements Cadmium, Chromium, Copper, Manganese, Lead, Zinc, Nickel, Arsenic and Cobalt were conducted in Puget Sound suspended particulate matter (SPM), bottom sediments, sediment traps, and zooplankton. Trace metal content of SPM increases as the total concentration of SPM decreases, whereas trace metal content of bottom sediments increases with sediment clay content. Based on the published data for trace metals, Ksub(d) values for oceanic red-clay sediments have been calculated as an alternative to laboratory experiments with radionuclides. (author)

  6. Confidence bounds and hypothesis tests for normal distribution coefficients of variation

    Science.gov (United States)

    Steve Verrill; Richard A. Johnson

    2007-01-01

    For normally distributed populations, we obtain confidence bounds on a ratio of two coefficients of variation, provide a test for the equality of k coefficients of variation, and provide confidence bounds on a coefficient of variation shared by k populations.

  7. Distribution of lead, Pb 210 in Kuala Muda sediment

    International Nuclear Information System (INIS)

    Jalal Sharib; Zaharudin Ahmad; Yii Mei Wo; Ahmad Sanadi Abu Bakar; Norfaizal Mohamed; Kamarozaman Ishak; Zulkifli Daud

    2008-08-01

    Activity of lead-210, Pb 210 concentration and their distributions in the core sediment from coastal area of Kuala Muda, Kedah was carried out using alpha spectrometry system. The sampling of core sediment for this study was carried out in stages from June 2007 - Nov 2007 as part of Post-Tsunami Environment Impact Assessment Project. The results show that the distribution of lead-210 activity, Pb 210 in core sediment is not consistent and the profiles show no discernable trend. This fluctuation is due to high sedimentation rates and sample disturbance. Compared to previous measurement of nearby area, current results show some increase of Pb 210 activity. (Author)

  8. Analysis of Grain Size Distribution and Hydraulic Conductivity for a Variety of Sediment Types with Application to Wadi Sediments

    KAUST Repository

    Rosas Aguilar, Jorge

    2013-05-01

    Grain size distribution, porosity, and hydraulic conductivity from over 400 unlithified sediment samples were analized. The measured hydraulic conductivity values were then compared to values calculated using 20 different empirical equations commonly used to estimate hydraulic conductivity from grain size analyses. It was found that most of the hydraulic conductivity values estimated from the empirical equations correlated very poorly to the measured hydraulic conductivity values. Modifications of the empirical equations, including changes to special coefficients and statistical off sets, were made to produce modified equations that considerably improve the hydraulic conductivity estimates from grain size data for beach, dune, off shore marine, and wadi sediments. Expected hydraulic conductivity estimation errors were reduced. Correction factors were proposed for wadi sediments, taking mud percentage and the standard deviation (in phi units) into account.

  9. Determination of diffusion coefficients in cohesive and sandy sediment from the area of Gorleben

    International Nuclear Information System (INIS)

    Klotz, D.

    1989-01-01

    The cohesive and sandy sediments stem from shaft driving at the Gorleben salt done. For the cohesive materials, HTD was used as a tracer substance, while I-131 - was used for the sandy materials. Diffusion coefficients of HTD in cohesive materials in their natural texture are in the range of 2x10 -6 to 5x10 -6 cm 2 /s, those of I-131 - in the investigated uniform fine and middle sands are approximately 3x10 -6 cm 2 /s. (DG) [de

  10. Distribution of polycyclic aromatic hydrocarbons in water and surface sediments from Daya Bay, China

    International Nuclear Information System (INIS)

    Zhou, J.L.; Maskaoui, K.

    2003-01-01

    Findings indicate an urgent need to establish a monitoring program for persistent organic pollutants in water and sediment. - Marine culture is thriving in China and represents a major component of the regional economy in coastal zones, yet the environmental quality of many of those areas has never been studied. This paper attempts to investigate the quality status of Daya Bay, a key aquaculture area in China. The levels of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in water and sediment samples of the bay. The total concentrations of 16 PAHs varied from 4228 to 29325 ng l -1 in water, and from 115 to 1134 ng g -1 dry weight in sediments. In comparison to many other marine systems studied, the PAH levels in Daya Bay waters were relatively high, and at six sites they were sufficiently high (>10 μg l -1 ) to cause acute toxicity. The PAH composition pattern in sediments suggest dominance by medium to high molecular weight compounds, and the ratio of certain related PAHs indicate important pyrolytic and petrogenic sources. Further analysis showed that the distribution coefficient (K D ) increased with the particular organic carbon content of sediments, consistent with the PAH partition theory. The organic carbon normalised distribution coefficient (K oc ) also increased with the compounds' octanol/water partition coefficient (K ow ), confirming the potential applicability of the linear free energy relationships in the modelling and prediction of PAH behaviour in marine environments

  11. The distribution and adsorption behavior of aliphatic amines in marine and lacustrine sediments

    Science.gov (United States)

    Wang, Xu-chen; Lee, Cindy

    1990-10-01

    The methylated amines—monomethyl-, dimethyl-, and trimethyl amine (MMA, DMA, TMA)—are commonly found in aquatic environments, apparently as a result of decomposition processes. Adsorption of these amines to clay minerals and organic matter significantly influences their distribution in sediments. Laboratory measurements using 14C-radiolabelled amines and application of a linear partitioning model resulted in calculated adsorption coefficients of 2.4-4.7 (MMA), 3.3 (DMA), and 3.3-4.1 (TMA). Further studies showed that adsorption of amines is influenced by salinity of the porewaters, and clay mineral and organic matter content of the sediment solid phase. Concentrations of monomethyl- and dimethyl amine were measured in the porewaters and the solid phase of sediment samples collected from Flax Pond and Lake Ronkonkoma (NY), Long Island Sound, and the coastal Peru upwelling area. These two amines were present in all sediments investigated. A clear seasonal increase in the solid-phase concentration of MMA and DMA in Flax Pond sediments was likely related to the annual senescence of salt marsh grasses, either directly as a source of these compounds or indirectly by providing additional exchange capacity to the sediments. The distribution of amines in the solid and dissolved phases observed in all sediments investigated suggests that the distribution of these compounds results from a balance among production, decomposition, and adsorption processes.

  12. Sediment distribution in the offshore regions of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Veerayya, M.; Murty, C.S.; Varadachari, V.V.R.

    Sediment samples collected from the offshore areas of some of the beaches (Calangute, Baina and Colva) along the coast of Goa, have been studied for their particle size and areal distributions. These areas are dominated by sediments in the sand size...

  13. Sediment distribution and composition on the shallow water ...

    African Journals Online (AJOL)

    Sediments of the shallow water carbonate basin in Zanzibar channel were investigated for composition and grain size distribution. The surface sediment composition was dominated by carbonate sands (with CaCO3 > 30%), except in the area adjacent to mainland coastline and a thin lobe which projects from Ruvu River to ...

  14. Radionuclides in marine sediments - Distribution and processes

    Energy Technology Data Exchange (ETDEWEB)

    Rudjord, A.L. [Norwegian Radiation Protection Authority, Oesteraas (Norway); Oughton, D. [Agricultural Univ., Aas (Norway); Bergan, T.D.; Christensen, G. [IFE, Kjeller (Norway)

    2001-04-01

    The NO-1 part of EKO-1 involved both laboratory and field studies. The laboratory studies have been discribed earlier in this report. The following is a summary of the field studies. At station 26 (Norwegian Sea) the sediments seem to be influenced by radiocesium from the Chernobyl accident. This may be due to direct fallout deposition to the sea surface and followed by a rapid sinking and sedimentation. At station 16 (North Sea) some influence from Sellafield plutonium is suggested, as the plutonium ratio is significantly higher (0.07-0.09) than would be expected from global fallout (0.03). Sedimentation rates based on analysis of {sup 210}Pb or {sup 210}Po varied between 0.03 cm/year - 0.25 cm/year. A surprisingly low sedimentation rate was found in the tenisey Bay (0.05 cm/year). It is possible that the dating method is less suited in this area, due to the long winter ice cover. In general, the rough estimates on K{sub d} values for {sup 137}Cs obtained empirically are highter than K{sub d} values obtained from the alboratory studies. This may be due to the fact that the 2 cm surface sediment in most cases has accumulated over many years, carrying contamination from the early eighties when levels of {sup 137}Cs in the sea water were higher. The {sup 137}Cs in the sediments it now fixed, or being remobilized only very slowly. Burial of the contamination by sedimentation may also make it unavailable for exchange with free water masses. (EHS)

  15. Radionuclides in marine sediments - Distribution and processes

    International Nuclear Information System (INIS)

    Rudjord, A.L.; Oughton, D.; Bergan, T.D.; Christensen, G.

    2001-01-01

    The NO-1 part of EKO-1 involved both laboratory and field studies. The laboratory studies have been discribed earlier in this report. The following is a summary of the field studies. At station 26 (Norwegian Sea) the sediments seem to be influenced by radiocesium from the Chernobyl accident. This may be due to direct fallout deposition to the sea surface and followed by a rapid sinking and sedimentation. At station 16 (North Sea) some influence from Sellafield plutonium is suggested, as the plutonium ratio is significantly higher (0.07-0.09) than would be expected from global fallout (0.03). Sedimentation rates based on analysis of 210 Pb or 210 Po varied between 0.03 cm/year - 0.25 cm/year. A surprisingly low sedimentation rate was found in the tenisey Bay (0.05 cm/year). It is possible that the dating method is less suited in this area, due to the long winter ice cover. In general, the rough estimates on K d values for 137 Cs obtained empirically are highter than K d values obtained from the alboratory studies. This may be due to the fact that the 2 cm surface sediment in most cases has accumulated over many years, carrying contamination from the early eighties when levels of 137 Cs in the sea water were higher. The 137 Cs in the sediments it now fixed, or being remobilized only very slowly. Burial of the contamination by sedimentation may also make it unavailable for exchange with free water masses. (EHS)

  16. Plutonium-239 sorption and transport on/in unsaturated sediments. Comparison of batch and column experiments for determining sorption coefficients

    International Nuclear Information System (INIS)

    Jinchuan Xie; Jiachun Lu; Xiaohua Zhou; Xuhui Wang; Mei Li; Lili Du; Yueheng Liu; Guoqing Zhou

    2013-01-01

    Sorption (distribution) coefficients of plutonium were most often derived by static batch experiments. However, it is not clear how unsaturated flow conditions including moisture content and pore water velocity change the sorption coefficients. Transport experiments of plutonium through the unsaturated sediments packed into the columns were then performed in order to determine the sorption coefficients (column-K ds ). Static batch experiments were also conducted to obtain batch-K ds and then compare the differences between batch-K ds and column-K ds . The results show that unsaturated flow conditions had no significant effect on column-K ds , and the average column-K d value was 1.74 ± 0.02 m 3 /kg. By comparison, batch-K d values spanned several orders of magnitude, regardless of the specified liquid-solid conditions. Moreover, the batch-K d (22.7 m 3 /kg) at the standard L/S (4 mL/g) recommended by ASTM D 4319 was over an order of magnitude larger than the average column-K d . (author)

  17. Distribution coefficient Kd in surface soils collected in Aomori prefecture

    International Nuclear Information System (INIS)

    Tsukada, Hirofumi; Hasegawa, Hidenao; Hisamatsu, Shun'ichi; Inaba, Jiro

    2000-01-01

    Soil-solution distribution coefficients (Kds), which are the ratio of an element concentration in a soil solid phase to that in a solution phase, for 32 elements in Andosols, Wet Andosols and Gleyed Andosols collected throughout Aomori Prefecture were determined. A dried soil sample was mixed with a 10-fold amount of pure water in a PPCO centrifuge tube, and then gently shaken for 24 h. The Kd values were obtained by measurement of element concentrations in solid and solution phases (batch method). The Kd values in this work were up to three orders of magnitude higher than the IAEA reported values, and their 95% confidence intervals were within two orders of magnitude. Most Kd values of elements were decreasing with increasing electrical conductivity of the solution phase. The Kd of Ca had a good correlation with that of Sr. However, the correlation between the Kds of K and Cs was not good. The Kd values were also determined by another method. The soil solutions were separated from the fresh soil samples by means of high speed centrifuging. The Kd values were calculated from the element concentration in solid phase and soil solution (centrifugation method). The Kd values obtained by the centrifugation method agreed within one order of magnitude with those by the batch method, and both variation patterns in elements correlated well. (author)

  18. Sediment Size Distribution at Three Rivers with Different Types of ...

    African Journals Online (AJOL)

    ADOWIE PERE

    sediment size distribution based on land use is very crucial in river maintenance. ... a basis for river catchment management study and can be used by river management .... small. In this case, the difference between upstream and downstream ...

  19. Distribution of organic carbon in sediments from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Paropkari, A.L.; Mascarenhas, A.; PrakashBabu, C.

    Many earlier studies on the distribution of organic carbon in the Arabian Sea, sediments have projected contradictory opinions on the factors favouring accumulation and preservation of organic carbon in the Arabian Sea. An attempt is made...

  20. Measurement of distribution coefficients using a radial injection dual-tracer test

    International Nuclear Information System (INIS)

    Pickens, J.F.; Jackson, R.E.; Inch, K.J.; Merritt, W.F.

    1981-01-01

    The dispersive and adsorptive properties of a sandy aquifer were evaluated by using a radial injection dual-tracer test with 131 I as the nonreactive tracer and 85 Sr as the reactive tracer. The tracer migration was monitored by using multilevel point-sampling devices located at various radial distances and depths. Nonequilibrium physical and chemical adsorption effects for 85 Sr were treated as a spreading or dispersion mechanism in the breakthrough curve analysis. The resulting effective dispersivity values for 85 Sr were typically a factor of 2 to 5 larger than those obtained for 131 I. The distribution coefficient (K/sub d//sup Sr/) values obtained from analysis of the breakthrough curves at three depths and two radial distances ranged from 2.6 to 4.5 ml/g. These compare favorably with values obtained by separation of fluids from solids in sediment cores, by batch experiments on core sediments and by analysis of a 25-year-old radioactive waste plume in another part of the same aquifer. Correlations of adsorbed 85 Sr radioactivity with grain size fractions demonstrated preferential adsorption to the coarsest fraction and to the finest fraction. The relative amounts of electrostatically and specifically adsorbed 85 Sr on the aquifer sediments were determined with desorption experiments on core sediments using selective chemical extractants. The withdrawal phase breakthrough curves for the well, obtained immediately following the injection phase, showed essentially full tracer recoveries for both 131 I and 85 Sr. Relatively slow desorption of 85 Sr provided further indication of the nonequilibrium nature of the adsorption-desorption phenomena

  1. [Distribution of polycyclic aromatic hydrocarbons in water and sediment from Zhoushan coastal area, China].

    Science.gov (United States)

    Jiang, Min; Tuan, Le Huy; Mei, Wei-Ping; Ruan, Hui-Hui; Wu, Hao

    2014-07-01

    The spatial and temporal distribution of 16 polycyclic aromatic hydrocarbons (PAHs) has been investigated in water and sediments of Zhoushan coastal area every two months in 2012. The concentrations of total PAHs ranged from 382.3 to 816.9 ng x L(-1), with the mean value of 552.5 ng x L(-1) in water; whereas it ranged from 1017.9 to 3047.1 ng x g(-1), with the mean value of 2 022.4 ng x g(-1) in sediment. Spatial distribution showed that Yangshan and Yanwoshan offshore area had the maximum and minimum of total PAHs contents in water, while the maximum and minimum occurred at Yangshan and Zhujiajian Nansha offshore area in sediment. Temporal distribution revealed that total PAHs contents in water reached the maximum and minimum values in October and June, however in sediments these values were found in August and June, respectively. The PAHs pollution was affected by oil emission, charcoal and coal combustion. Using the biological threshold and exceeded coefficient method to assess the ecological risk of PAHs in Zhoushan coastal area, the result showed that sigma PAHs had a lower probability of potential risk, while there was a higher probability of potential risk for acenaphthylene monomer, and there might be ecological risk for acenaphthene and fluorene. Distribution of PAHs between sediment and water showed that Zhoushan coastal sediment enriched a lot of PAHs, meanwhile the enrichment coefficient (K(d) value) of sediment in Daishan island was larger than that in Zhoushan main island.

  2. Field experiment determinations of distribution coefficients of actinide elements in alkaline lake environments

    International Nuclear Information System (INIS)

    Simpson, H.J.; Trier, R.M.; Li, Y.H.; Anderson, R.F.

    1984-01-01

    Radionuclide concentrations of a number of elements (Am, Pu, U, Pa, Th, Ac, Ra, Po, Pb, Cs, and Sr) have been measured in the water and sediments of a group of alkaline lakes in the western USA. These data demonstrate greatly enhanced soluble phase concentrations of elements with oxidation states of III, IV, V, and VI as the result of carbonate complexing. Dissolved concentrations of isotopes of U, Pa, and Th in a lake with pH = 10 and a total inorganic carbon concentration of 4 x 10 -1 moles/1 were greater than those in sea water (pH = 8, ΣCO 2 = 2 x 10 -3 moles/1) by order of magnitude for 233 U, 238 U (--10 2 ), 231 Pa, 228 Th, 230 Th (--10 3 ) and 22 Th (--10 5 ). Concentrations of fallout /sup 239,240/Pu in the more alkaline lakes were equivalent to effective distribution coefficients of --10 3 , about a factor of 10 2 lower than in most other natural lakes, rivers, estuaries and coastal marine waters. Measurements of radionuclides in natural systems are essential for assessment of the likely fate of radionuclides which may be released from high level waste repositories to ground water. Laboratory-scale experiments using tracer additions of radionuclides to mixtures of water and sediment yielded distribution coefficients which were significantly different from those derived from field measurements (10 1 -10 2 lower for Po and Pu). Order of magnitude calculations from thermodynamic data of expected maximum U and Th concentrations, limited by pure phase solubilities, suggest that carbonate complexing can enhance solubility by many orders of magnitude in natural waters, even at relatively low carbonate ion concentrations

  3. Global Distribution of Net Electron Acceptance in Subseafloor Sediment

    Science.gov (United States)

    Fulfer, V. M.; Pockalny, R. A.; D'Hondt, S.

    2017-12-01

    We quantified the global distribution of net electron acceptance rates (e-/m2/year) in subseafloor sediment (>1.5 meters below seafloor [mbsf]) using (i) a modified version of the chemical-reaction-rate algorithm by Wang et al. (2008), (ii) physical properties and dissolved oxygen and sulfate data from interstitial waters of sediment cores collected by the Ocean Drilling Program, Integrated Ocean Drilling Program, International Ocean Discovery Program, and U.S. coring expeditions, and (iii) correlation of net electron acceptance rates to global oceanographic properties. Calculated net rates vary from 4.8 x 1019 e-/m2/year for slowly accumulating abyssal clay to 1.2 x 1023 e-/m2/year for regions of high sedimentation rate. Net electron acceptance rate correlates strongly with mean sedimentation rate. Where sedimentation rate is very low (e.g., 1 m/Myr), dissolved oxygen penetrates more than 70 mbsf and is the primary terminal electron acceptor. Where sedimentation rate is moderate (e.g., 3 to 60 m/Myr), dissolved sulfate penetrates as far as 700 mbsf and is the principal terminal electron acceptor. Where sedimentation rate is high (e.g., > 60 m/Myr), dissolved sulfate penetrates only meters, but is the principal terminal electron acceptor in subseafloor sediment to the depth of sulfate penetration. Because microbial metabolism continues at greater depths than the depth of sulfate penetration in fast-accumulating sediment, complete quantification of subseafloor metabolic rates will require consideration of other chemical species.

  4. Occurrence and spatial distribution of microplastics in sediments from Norderney

    International Nuclear Information System (INIS)

    Dekiff, Jens H.; Remy, Dominique; Klasmeier, Jörg; Fries, Elke

    2014-01-01

    The spatial distribution of small potential microplastics (SPM) ( 1 mm) was also examined. Small microparticles were extracted from 36 one kg sediment samples and analysed by visual microscopic inspection and partly by thermal desorption pyrolysis gas chromatography/mass spectrometry. The smallest particle size that could be analysed with this method was estimated to be 100 μm. The mean number of SPM at the three sampling sites (n = 12) was 1.7, 1.3 and 2.3 particles per kg dry sediment, respectively. SPM were identified as polypropylene, polyethylene, polyethylene terephthalate, polyvinylchloride, polystyrene and polyamide. The organic plastic additives found were benzophenone, 1,2-benzenedicarboxylic acid, dimethyl phthalate, diethylhexyl phthalate, dibutyl phthalate, diethyl phthalate, phenol and 2,4-di-tert-butylphenol. Particles were distributed rather homogenously and the occurrence of SPM did not correlate with that of VPD. -- Highlights: • The small-scale variability of small potential microplastics (<1 mm) occurrence in beach sediments was studied. • Within 500 m, small potential microplastics (<1 mm) were distributed rather homogeneously in investigated beach sediments. • The occurrence of small potential microplastics (<1 mm) did not correlate with that of visible plastic debris. • Procedural contamination of sediments by fibres (blank) constitutes an analytical problem. • These findings must be considered when setting up standardized monitoring protocols. -- On a small scale within 500 m, small microplastics are distributed rather homogeneously in sediments from the North Sea island of Norderney

  5. Predicting sediment sorption coefficients for linear alkylbenzenesulfonate congeners from polyacrylate-water partition coefficients at different salinities.

    NARCIS (Netherlands)

    Rico Rico, A.; Droge, S.T.J.|info:eu-repo/dai/nl/304834017; Hermens, J.L.M.|info:eu-repo/dai/nl/069681384

    2010-01-01

    The effect of the molecular structure and the salinity on the sorption of the anionic surfactant linear alkylbenzenesulfonate (LAS) to marine sediment has been studied. The analysis of several individual LAS congeners in seawater and of one specific LAS congener at different dilutions of seawater

  6. Distribution of uranium in marine sediments

    International Nuclear Information System (INIS)

    Ordonez R, E.; Ramirez T, J.J.; Lopez M, J.; Aspiazu, J.; Ruiz F, A.C.; Valero C, N.

    2008-01-01

    The marine sediments obtained by means of a sampling nucleus in the Gulf of Tehuantepec, Mexico, they have been object of crystallographic and morphological characterization. The PIXE analysis of some samples in study is shown. The normal methodology to carry out the alpha spectroscopy indicates that the sample should be dissolved, but due to the nature of the marine sediments, it thinks about the necessity to make a fractional separation of the sample components. In each stratum of the profile it separates the organic part and the mineral to recover the uranium. It was observed that in the organic phase, the uranium is in two oxidation states (IV and Vl), being necessary the radiochemical separation with a liquid/liquid column chromatographic that uses the di-2-ethyl hexyl phosphoric acid as stationary phase. The uranium compounds extracts are electrodeposited in fine layers on stainless steel disks to carry out the analysis by alpha spectroscopy. The spectroscopic analysis of the uranium indicates us that for each stratum one has a difference marked in the quotient of activities of 234 U/ 238 U that depends on the nature of the studied fraction. These results give us a clear idea about how it is presented the effect of the uranium migration and other radioelements in the biosphere, with what we can determine which are the conditions in that these have their maximum mobility and to know their diffusion patterns in the different media studied. (Author)

  7. Effects of Aging Quartz Sand and Hanford Site Sediment with Sodium Hydroxide on Radionuclide Sorption Coefficients and Sediment Physical and Hydrologic Properties: Final Report for Subtask 2a

    Energy Technology Data Exchange (ETDEWEB)

    DI Kaplan; JC Ritter; KE Parker

    1998-12-04

    Column and batch experiments were conducted in fiscal year 1998 at Pacific Northwest National Laboratory to evaluate the effect of varying concentrations of NaOH on the sorptive, physical, and hydraulic properties of two media, a quartz sand and a composite subsurface sediment from the 200-East Area of the Hanford Site. The NaOH solutions were used as a simplified effluent from a low-activity glass waste form. These experiments were conducted over a limited (O-to 10-month) contact time, with respect to the 10,000-to 100,000-year scenarios described in the Immobilized Low-Activity Waste- Performance Assessment (ILAW-PA). Wheq these two solids were put in contact with the NaOH solutions, dissolution was evident by a substantial increase in dissolved Si concentrations in the leachates. Incremental increases in NaOH con- centrations, resulted in corresponding increases in Si concentrations. A number of physical and hydraulic properties also changed as the NaOH concentrations were changed. It was observed that quartz sand was less reactive than the composite sediment. Further, moisture- retention measurements were made on the quartz sand and composite sedimen$ which showed that the NaOH-treated solids retained more water than the non-NaOH-treated solids. Because the other chemical, physical, and hydraulic measurements did not change dramatically after the high-NaOH treatments, the greater moisture retention of the high-NaOH treatments was attributed to a "salt effect" and not to the formation of small particles during the dissolution (weathering). The distribution coefficients (IQ) for Cs and Sr were measured on the NaOH-treated sediments, with decreases from -3,000 to 1,000 and 1,300 to 300 mL/g noted, respectively, at the 0.01-to 1.O-M NaOH levels. There was no apparent trend for the Sr & values with contact time. The lack of such a trend sug- gests that dissolution of sediment particles is not controlling the drop in IQ rather, it is the competition of the added Na

  8. Use of spatially distributed time-integrated sediment sampling networks and distributed fine sediment modelling to inform catchment management.

    Science.gov (United States)

    Perks, M T; Warburton, J; Bracken, L J; Reaney, S M; Emery, S B; Hirst, S

    2017-11-01

    Under the EU Water Framework Directive, suspended sediment is omitted from environmental quality standards and compliance targets. This omission is partly explained by difficulties in assessing the complex dose-response of ecological communities. But equally, it is hindered by a lack of spatially distributed estimates of suspended sediment variability across catchments. In this paper, we demonstrate the inability of traditional, discrete sampling campaigns for assessing exposure to fine sediment. Sampling frequencies based on Environmental Quality Standard protocols, whilst reflecting typical manual sampling constraints, are unable to determine the magnitude of sediment exposure with an acceptable level of precision. Deviations from actual concentrations range between -35 and +20% based on the interquartile range of simulations. As an alternative, we assess the value of low-cost, suspended sediment sampling networks for quantifying suspended sediment transfer (SST). In this study of the 362 km 2 upland Esk catchment we observe that spatial patterns of sediment flux are consistent over the two year monitoring period across a network of 17 monitoring sites. This enables the key contributing sub-catchments of Butter Beck (SST: 1141 t km 2 yr -1 ) and Glaisdale Beck (SST: 841 t km 2 yr -1 ) to be identified. The time-integrated samplers offer a feasible alternative to traditional infrequent and discrete sampling approaches for assessing spatio-temporal changes in contamination. In conjunction with a spatially distributed diffuse pollution model (SCIMAP), time-integrated sediment sampling is an effective means of identifying critical sediment source areas in the catchment, which can better inform sediment management strategies for pollution prevention and control. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Development of database on the distribution coefficient. 2. Preparation of database

    Energy Technology Data Exchange (ETDEWEB)

    Takebe, Shinichi; Abe, Masayoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    The distribution coefficient is very important parameter for environmental impact assessment on the disposal of radioactive waste arising from research institutes. 'Database on the Distribution Coefficient' was built up from the informations which were obtained by the literature survey in the country for these various items such as value , measuring method and measurement condition of distribution coefficient, in order to select the reasonable distribution coefficient value on the utilization of this value in the safety evaluation. This report was explained about the outline on preparation of this database and was summarized as a use guide book of database. (author)

  10. Development of database on the distribution coefficient. 2. Preparation of database

    Energy Technology Data Exchange (ETDEWEB)

    Takebe, Shinichi; Abe, Masayoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    The distribution coefficient is very important parameter for environmental impact assessment on the disposal of radioactive waste arising from research institutes. 'Database on the Distribution Coefficient' was built up from the informations which were obtained by the literature survey in the country for these various items such as value , measuring method and measurement condition of distribution coefficient, in order to select the reasonable distribution coefficient value on the utilization of this value in the safety evaluation. This report was explained about the outline on preparation of this database and was summarized as a use guide book of database. (author)

  11. Optimal control of suspended sediment distribution model of Talaga lake

    Science.gov (United States)

    Ratianingsih, R.; Resnawati, Azim, Mardlijah, Widodo, B.

    2017-08-01

    Talaga Lake is one of several lakes in Central Sulawesi that potentially to be managed in multi purposes scheme because of its characteristic. The scheme is addressed not only due to the lake maintenance because of its sediment but also due to the Algae farming for its biodiesel fuel. This paper governs a suspended sediment distribution model of Talaga lake. The model is derived from the two dimensional hydrodynamic shallow water equations of the mass and momentum conservation law of sediment transport. An order reduction of the model gives six equations of hyperbolic systems of the depth, two dimension directional velocities and sediment concentration while the bed elevation as the second order of turbulent diffusion and dispersion are neglected. The system is discreted and linearized such that could be solved numerically by box-Keller method for some initial and boundary condition. The solutions shows that the downstream velocity is play a role in transversal direction of stream function flow. The downstream accumulated sediment indicate that the suspended sediment and its changing should be controlled by optimizing the downstream velocity and transversal suspended sediment changing due to the ideal algae growth need.

  12. Confidence bounds and hypothesis tests for normal distribution coefficients of variation

    Science.gov (United States)

    Steve P. Verrill; Richard A. Johnson

    2007-01-01

    For normally distributed populations, we obtain confidence bounds on a ratio of two coefficients of variation, provide a test for the equality of k coefficients of variation, and provide confidence bounds on a coefficient of variation shared by k populations. To develop these confidence bounds and test, we first establish that estimators based on Newton steps from n-...

  13. Cadmium distribution in coastal sediments and mollusks of the US

    International Nuclear Information System (INIS)

    Apeti, Dennis A.; Lauenstein, Gunnar G.; Riedel, Gerhardt F.

    2009-01-01

    Cadmium (Cd) concentrations in the coastal United States were assessed using the National Status and Trends (NS and T) Mussel Watch dataset, which is based on the analysis of sediments and bivalves collected from 280 sites since 1986. Using the 1997 sediment data, Pearson correlation (r = 0.44, p < 0.0001) suggested that Cd distributions in sediment can, be to some extent, explained by the proximity of sites to population centers. The 2003 tissue data indicated that 'high' Cd concentrations (greater than 5.6 μg/g dry weights [dw] for mussel and 5.4 μg/g dw for oysters) were related to salinity along the East and Gulf coasts. Along the West coast, however, these 'high' sites appeared to be related to upwelling phenomenon. Additionally, sedimentary diagenesis was found to be the most likely explanation of why sediment and mollusk Cd content were not well correlated.

  14. A Qualitative and Quantitative Study of the Distribution of Pelagic Sediment in the Atlantic Basin

    National Research Council Canada - National Science Library

    Webb, Helen

    1997-01-01

    By numerically modeling pelagic sedimentation as a diffusive process, we study sedimentation effects in terms of stochastic parameters including seafloor RMS height, abyssal hill spacing, and slope distribution...

  15. EXPERIMENTAL STUDY ON SEDIMENT DISTRIBUTION AT CHANNEL BIFURCATION

    Institute of Scientific and Technical Information of China (English)

    G.M. Tarekul ISLAM; M.R. KABIR; Ainun NISHAT

    2002-01-01

    This paper presents the experimental results on the distribution of sediments at channel bifurcation.The experiments have been conducted in a physical model of channel bifurcation. It consists of a straight main channel which bifurcates into two branch channels of different widths. The test rig is a mobile bed with fixed bank. Four different noses have been used to study the phenomenon. For each nose, three upstream discharges viz. 20 l/s, 30 l/s and 40 l/s have been employed. From the measured data, discharges and sediment transport ratios per unit width are calculated in the downstream branches.These data have been set to the general nodal point relation and a set of equations has been developed to describe the distribution of sediments to the downstream branches for different nose angles.

  16. Inventory calculations in sediment samples with heterogeneous plutonium activity distribution

    International Nuclear Information System (INIS)

    Eriksson, M.; Dahlgaard, H.

    2002-01-01

    A method to determine the total inventory of a heterogeneously distributed contamination of marine sediments is described. The study site is the Bylot Sound off the Thule Airbase, NW Greenland, where marine sediments became contaminated with plutonium in 1968 after a nuclear weapons accident. The calculation is based on a gamma spectrometric screening of the 241 Am concentration in 450 one-gram aliquots from 6 sediment cores. A Monte Carlo programme then simulates a probable distribution of the activity, and based on that, a total inventory is estimated by integrating a double exponential function. The present data indicate a total inventory around 3.5 kg, which is 7 times higher than earlier estimates (0.5 kg). The difference is partly explained by the inclusion of hot particles in the present calculation. A large uncertainty is connected to this estimate, and it should be regarded as preliminary. (au)

  17. Measurement and prediction of aromatic solute distribution coefficients for aqueous-organic solvent systems. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J.R.; Luthy, R.G.

    1984-06-01

    Experimental and modeling activities were performed to assess techniques for measurement and prediction of distribution coefficients for aromatic solutes between water and immiscible organic solvents. Experiments were performed to measure distribution coefficients in both clean water and wastewater systems, and to assess treatment of a wastewater by solvent extraction. The theoretical portions of this investigation were directed towards development of techniques for prediction of solute-solvent/water distribution coefficients. Experiments were performed to assess treatment of a phenolic-laden coal conversion wastewater by solvent extraction. The results showed that solvent extraction for recovery of phenolic material offered several wastewater processing advantages. Distribution coefficients were measured in clean water and wastewater systems for aromatic solutes of varying functionality with different solvent types. It was found that distribution coefficients for these compounds in clean water systems were not statistically different from distribution coefficients determined in a complex coal conversion process wastewater. These and other aromatic solute distribution coefficient data were employed for evaluation of modeling techniques for prediction of solute-solvent/water distribution coefficients. Eight solvents were selected in order to represent various chemical classes: toluene and benzene (aromatics), hexane and heptane (alkanes), n-octanol (alcohols), n-butyl acetate (esters), diisopropyl ether (ethers), and methylisobutyl ketone (ketones). The aromatic solutes included: nonpolar compounds such as benzene, toluene and naphthalene, phenolic compounds such as phenol, cresol and catechol, nitrogenous aromatics such as aniline, pyridine and aminonaphthalene, and other aromatic solutes such as naphthol, quinolinol and halogenated compounds. 100 references, 20 figures, 34 tables.

  18. Pesticides distribution in surface waters and sediments of lotic and ...

    African Journals Online (AJOL)

    An investigation on the availability and distribution of Lindane (HCHs) and Total organochlorine phosphate (TOCP) in the surface waters and sediments of selected water bodies in Agbede wetlands was carried out from December, 2012 to May, 2014 in order to cover seasonal trends in both matrixes. A Gas Chromatograph ...

  19. Radar meteors range distribution model. IV. Ionization coefficient

    Czech Academy of Sciences Publication Activity Database

    Pecinová, Drahomíra; Pecina, Petr

    2008-01-01

    Roč. 38, č. 1 (2008), s. 12-20 ISSN 1335-1842 R&D Projects: GA ČR GA205/03/1405 Institutional research plan: CEZ:AV0Z10030501 Keywords : physics of meteors * radar meteors * range distribution Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  20. Copper and zinc distribution coefficients for sandy aquifer materials

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Astrup, Thomas; Boddum, J. K.

    2000-01-01

    Distribution coe�cients (Kd) were measured for copper (Cu) and zinc (Zn) in laboratory batch experiments for 17 sandy aquifer materials at environmentally relevant solute concentrations (Cu: 5±300 mg/l, Zn: 20±3100 mg/l). The Kd values ranged two to three orders of magnitude (Cu: 70±10,800 l/ kg...

  1. A simple distributed sediment delivery approach for rural catchments

    Science.gov (United States)

    Reid, Lucas; Scherer, Ulrike

    2014-05-01

    The transfer of sediments from source areas to surface waters is a complex process. In process based erosion models sediment input is thus quantified by representing all relevant sub processes such as detachment, transport and deposition of sediment particles along the flow path to the river. A successful application of these models requires, however, a large amount of spatially highly resolved data on physical catchment characteristics, which is only available for a few, well examined small catchments. For the lack of appropriate models, the empirical Universal Soil Loss Equation (USLE) is widely applied to quantify the sediment production in meso to large scale basins. As the USLE provides long-term mean soil loss rates, it is often combined with spatially lumped models to estimate the sediment delivery ratio (SDR). In these models, the SDR is related to data on morphological characteristics of the catchment such as average local relief, drainage density, proportion of depressions or soil texture. Some approaches include the relative distance between sediment source areas and the river channels. However, several studies showed that spatially lumped parameters describing the morphological characteristics are only of limited value to represent the factors of influence on sediment transport at the catchment scale. Sediment delivery is controlled by the location of the sediment source areas in the catchment and the morphology along the flow path to the surface water bodies. This complex interaction of spatially varied physiographic characteristics cannot be adequately represented by lumped morphological parameters. The objective of this study is to develop a simple but spatially distributed approach to quantify the sediment delivery ratio by considering the characteristics of the flow paths in a catchment. We selected a small catchment located in in an intensively cultivated loess region in Southwest Germany as study area for the development of the SDR approach. The

  2. Distribution, sedimentation, and bioavailability of particulate phosphorus in the mainstream of the Three Gorges Reservoir.

    Science.gov (United States)

    Tang, Xianqiang; Wu, Min; Li, Rui

    2018-09-01

    The transportation and sedimentation of particulate phosphorus (PP) in a huge reservoir such as the Three Gorges Reservoir (TGR) are closely related to the phosphorus distribution characteristics and nutritional status of the water body. In this study, the PP distribution, sedimentation, and bioavailability in the mainstream section of the TGR were investigated through a field survey, indoor simulated settlement experiment, and historical data analysis. The results indicated that PP was the major component of the total phosphorus (TP) and that the Three Gorges Dam (TGD) trapped nearly 76.25% of suspended sediment (SS) and 75.35% of PP in the TGR, even during the flood season. A decline in flow velocity promoted the deposition of PP; additionally, PP concentrations gradually dropped from 0.35 mg/L in Chongqing to 0.02 mg/L in Zigui. The static PP sedimentation process adequately fitted a pseudo-second-order kinetic equation with a maximum correlation coefficient of 0.97. Moreover, more than half of the PP sedimentation process was achieved in less than 60 min for samples collected from the upper river reaches within simulated sedimentation process. The median particle size of SS and absolute value of the water column's zeta potential were negatively and positively related to the t 12 values of PP sedimentation, respectively. Compared with the concentration and particle size of SS obtained in the pre-TGR period, the values in the mainstream section of the TGR were lower. However, the TP and Fe/Al-P contents in SS increased several times. Due to the combined effects of flow velocity reduction and SS trapping, the water transparency and bioavailability of water column phosphorus were enhanced. Thus, the risk of water bloom outburst significantly increased when the impounded water level of 175 m in the TGR became the normal state. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Sediment studies at Bikini Atoll part 1. distribution of fine and coarse components in surface sediments

    International Nuclear Information System (INIS)

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

    1997-01-01

    In 1979, 21 years after the moratorium on nuclear testing in the Marshall Islands, surface sediment samples (to depths of 2 and 4 cm) were collected from 87 locations over the floor of Bikini lagoon. The main purpose for the collections was to map the distribution of long- lived man-made radionuclides associated with the bottom material. In addition the samples were processed to estimate the fraction of fine and coarse components to show what modifications occurred since the sediment composition was first described in samples collected before testing in 1946. In this report a comparison is made of the amount and distribution of fine material associated with the lagoon surface sediment before and after the testing of nuclear devices. Nuclear testing produced more finely divided material in-the surface sediment layer over large areas of the lagoon and especially in regions of the lagoon and reef adjacent to test sites. Five cratering events at Bikini Atoll generated sufficient material to account for the inventory of new fine material found over the bottom surface of the lagoon. Although the fraction of fine material in the bottom sediments was altered by the nuclear events, the combined processes of formation, transport and deposition were not sufficiently dynamic to alter the geographical features of the major sedimentary components over most of the lagoon floor

  4. Sediment studies at Bikini Atoll part 1. distribution of fine and coarse components in surface sediments

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-01-01

    In 1979, 21 years after the moratorium on nuclear testing in the Marshall Islands, surface sediment samples (to depths of 2 and 4 cm) were collected from 87 locations over the floor of Bikini lagoon. The main purpose for the collections was to map the distribution of long- lived man-made radionuclides associated with the bottom material. In addition the samples were processed to estimate the fraction of fine and coarse components to show what modifications occurred since the sediment composition was first described in samples collected before testing in 1946. In this report a comparison is made of the amount and distribution of fine material associated with the lagoon surface sediment before and after the testing of nuclear devices. Nuclear testing produced more finely divided material in-the surface sediment layer over large areas of the lagoon and especially in regions of the lagoon and reef adjacent to test sites. Five cratering events at Bikini Atoll generated sufficient material to account for the inventory of new fine material found over the bottom surface of the lagoon. Although the fraction of fine material in the bottom sediments was altered by the nuclear events, the combined processes of formation, transport and deposition were not sufficiently dynamic to alter the geographical features of the major sedimentary components over most of the lagoon floor.

  5. Evaluation of distribution patterns and decision of distribution coefficients of trace elements in high-purity aluminium by INAA

    International Nuclear Information System (INIS)

    Hayakawa, Yasuhiro; Suzuki, Shogo; Hirai, Shoji

    1986-01-01

    Recently, a high-purity aluminium has been used in semi-coductor device, so on. It was required that trace impurities should be reduced and that its content should be quantitatively evaluated. In this study, distribution patterns of many trace impurities in 99.999 % aluminium ingots, which was purified using a normal freezing method, were evaluated by an INAA. The effective distribution coefficient k for each detected elements was calculated using a theoretical distribution equation in the normal freezing method. As a result, the elements of k 1 was Hf. Especially, La, Sm, U and Th could be effectively purified, but Sc and Hf could be scarcely purified. Further more, it was found that the slower freezing gave the effective distribution coefficient close to the equilibrium distribution coefficient, and that the effective distribution coefficient became smaller with the larger atomic radius. (author)

  6. On the size distribution of cities: an economic interpretation of the Pareto coefficient.

    Science.gov (United States)

    Suh, S H

    1987-01-01

    "Both the hierarchy and the stochastic models of size distribution of cities are analyzed in order to explain the Pareto coefficient by economic variables. In hierarchy models, it is found that the rate of variation in the productivity of cities and that in the probability of emergence of cities can explain the Pareto coefficient. In stochastic models, the productivity of cities is found to explain the Pareto coefficient. New city-size distribution functions, in which the Pareto coefficient is decomposed by economic variables, are estimated." excerpt

  7. Transport coefficients in Lorentz plasmas with the power-law kappa-distribution

    International Nuclear Information System (INIS)

    Jiulin, Du

    2013-01-01

    Transport coefficients in Lorentz plasma with the power-law κ-distribution are studied by means of using the transport equation and macroscopic laws of Lorentz plasma without magnetic field. Expressions of electric conductivity, thermoelectric coefficient, and thermal conductivity for the power-law κ-distribution are accurately derived. It is shown that these transport coefficients are significantly modified by the κ-parameter, and in the limit of the parameter κ→∞ they are reduced to the standard forms for a Maxwellian distribution

  8. Self-similar optical pulses in competing cubic-quintic nonlinear media with distributed coefficients

    International Nuclear Information System (INIS)

    Zhang Jiefang; Tian Qing; Wang Yueyue; Dai Chaoqing; Wu Lei

    2010-01-01

    We present a systematic analysis of the self-similar propagation of optical pulses within the framework of the generalized cubic-quintic nonlinear Schroedinger equation with distributed coefficients. By appropriately choosing the relations between the distributed coefficients, we not only retrieve the exact self-similar solitonic solutions, but also find both the approximate self-similar Gaussian-Hermite solutions and compact solutions. Our analytical and numerical considerations reveal that proper choices of the distributed coefficients could make the unstable solitons stable and could restrict the nonlinear interaction between the neighboring solitons.

  9. Microplastic Distribution at Different Sediment Depths in an Urban Estuary

    Directory of Open Access Journals (Sweden)

    Kathryn A. Willis

    2017-12-01

    Full Text Available As plastic production increases, so to do the threats from plastic pollution. Microplastics (defined as plastics <5 mm are a subset of marine debris about which we know less than we do of larger debris items, though they are potentially ubiquitous in the marine environment. To quantify the distribution and change in microplastic densities through time, we sampled sediment cores from an estuary in Tasmania, Australia. We hypothesized that the type, distribution and abundance of microplastics observed would be associated with increasing plastic production, coastal population growth, and proximity to urban water outflows and local hydrodynamics. Sediments ranging from the year 1744 to 2004 were sub-sampled from each core. We observed microplastics in every sample, with greater plastic frequencies found in the upper (more recent sediments. This time trend of microplastic accumulation matched that of global plastic production and coastal population growth. We observed that fibers were the most abundant type of microplastic in our samples. These fibers were present in sediments that settled prior to the presence of plastics in the environment. We propose a simple statistical model to estimate the level of contamination in our samples. We suggest that the current trend in the literature suggesting very high loads of fibers, particularly in remote locations such as the deep seafloor, may be largely due to contamination.

  10. Content, distribution and fate of 33 elements in sediments of rivers receiving wastewater in Hanoi, Vietnam

    International Nuclear Information System (INIS)

    Marcussen, Helle; Dalsgaard, Anders; Holm, Peter E.

    2008-01-01

    Untreated industrial and domestic wastewater from Hanoi city is discharged into rivers that supply water for various agricultural and aquacultural food production systems. The aim of this study was to assess the content, distribution and fate of 33 elements in the sediment and pore water of the main wastewater receiving rivers. The sediment was polluted with potentially toxic elements (PTEs) with maximum concentrations of 73 As, 427 Cd, 281 Cr, 240 Cu, 218 Ni, 363 Pb, 12.5 Sb and 1240 Zn mg kg -1 d.w. Observed distribution coefficients (log 10 K d,obs ) were calculated as the ratio between sediment (mg kg -1 d.w.) and pore water (mg L -1 ) concentrations. Maxima log 10 K d,obs were >4.26 Cd, >6.60 Cu, 4.78 Ni, 7.01 Pb and 6.62 Zn. The high values show a strong PTE retention and indicate the importance of both sorption and precipitation as retention mechanisms. Sulphide precipitation was a likely mechanism due to highly reduced conditions. - Sorption and precipitation processes are important in retention of potentially toxic elements in Hanoi river sediment and prevent elements entering food production systems

  11. Performance Probability Distributions for Sediment Control Best Management Practices

    Science.gov (United States)

    Ferrell, L.; Beighley, R.; Walsh, K.

    2007-12-01

    Controlling soil erosion and sediment transport can be a significant challenge during the construction process due to the extent and conditions of bare, disturbed soils. Best Management Practices (BMPs) are used as the framework for the design of sediment discharge prevention systems in stormwater pollution prevention plans which are typically required for construction sites. This research focuses on commonly-used BMP systems for perimeter control of sediment export: silt fences and fiber rolls. Although these systems are widely used, the physical and engineering parameters describing their performance are not well understood. Performance expectations are based on manufacturer results, but due to the dynamic conditions that exist on a construction site performance expectations are not always achievable in the field. Based on experimental results product performance is shown to be highly variable. Experiments using the same installation procedures show inconsistent sediment removal performances ranging from (>)85 percent to zero. The goal of this research is to improve the determination of off-site sediment yield based on probabilistic performance results of perimeter control BMPs. BMPs are evaluated in the Soil Erosion Research Laboratory (SERL) in the Civil and Environmental Engineering department at San Diego State University. SERL experiments are performed on a 3-m by 10-m tilting soil bed with a soil depth of 0.5 meters and a slope of 33 percent. The simulated storm event consists of 17 mm/hr for 20 minutes followed by 51 mm/hr for 30 minutes. The storm event is based on an ASTM design storm intended to simulate BMP failures. BMP performance is assessed based on experiments where BMPs are installed per manufacture specifications, less than optimal installations, and no treatment conditions. Preliminary results from 30 experiments are presented and used to develop probability distributions for BMP sediment removal efficiencies. The results are then combined with

  12. [Heavy metals distribution characteristics and ecological risk evaluation in surface sediments of dammed Jinshan lake].

    Science.gov (United States)

    Zhou, Xiao-Hong; Liu, Long-Mei; Chen, Xi; Chen, Zhi-Gang; Zhang, Jin-Ping; Li, Yi-Min; Liu, Biao

    2014-11-01

    In order to reveal the pollution loading of heavy metals in Dammed Jinshan lake, six heavy metals (As, Cu, Pb, Cd, Zn, Cr) from 18 sediment samples were analyzed using ICP, and the distribution characteristics of heavy metals in the sediment were comprehensively evaluated through concentration coefficient, geo-acumulation indexes, potential ecological risk evaluation and traceability analysis. The results showed that (1) the average contents of As, Pb, Cu, Zn, Cr, Cd were 23.22, 26.20, 24.42, 143.12, 245.30 and 0.67 mg x kg(-1), respectively, in the surface sediments of dammed Jinshan Lake. The average contents of Pb and Cu were lower than the primary standard and secondary standards of soil environmental quality standards. The average contents of Zn and Cr were lower than the primary standard and higher than the secondary standards of soil environmental quality standards. The average contents of As and Cd were higher than the primary and secondary standards of soil environmental quality standards. From the spatial distribution, the contents of Pb and Zn were the highest at sampling site No. 1, which was located at the Beigushan Square. The contents of As,Cu, Cr, Cd were the highest at sampling sites Nos. 12, 3, 14, and 7, respectively; (2) The order of concentration coefficient was As > Cr > Cd > Pb > Zn > Cu, which indicated that the enrichment amount of As was the highest and that of Cu was the lowest; (3) Based on the geo-acumulation indexes, the Cu is clean and Pb, Zn, Cd is the light pollution and As, Cr moderate pollution; (4) The order of Potential ecological risk coefficient was Cd > As > Cr > Pb > Cu > Zn, Cr, Pb, Cu, Zn were of light ecological risk and As, Cd were of medium ecological risk. From the spatial distribution, the sampling sites Nos. 1, 6, 7 and 12 had medium potential ecological risk, and the rest sample points had slight potential ecological risk; (5) The principal component analysis (PCA) revealed that the main reason for the differences

  13. Distribution coefficients of different soil types at Olkiluoto repository site and its surroundings, southwestern Finland

    Energy Technology Data Exchange (ETDEWEB)

    Lahdenperae, Anne-Maj [Saanio and Riekkola Oy, Laulukuja 4, FI-00420 Helsinki (Finland); Ikonen, Ari T.K. [Environmental Research and Assessment EnviroCase, Ltd., Hallituskatu 1 D 4, 28100 Pori (Finland)

    2014-07-01

    In Finland, the Olkiluoto Island on the western coast has been selected as a repository site for the spent nuclear fuel. Due to shallow sea areas around the island, the post-glacial crustal rebound (around 6 mm/y) is changing the landscape significantly; during the next thousands of years new soil types are emerging, the present bays will narrow and form future lakes and mires assumedly similar to those farther inland at present. The effects of terrain development are important in long-term safety assessments for the repository, especially in the biosphere assessments addressing radiation exposure of people and biota in scenarios of radionuclide releases. 'In situ' distribution coefficients, K{sub d} values are used to indicate the relevant mobility of radionuclides of concern from nuclear waste. These radionuclides have very long half-lives and long interaction times with soils, ranging from centuries to millennia. By measuring the desorption K{sub d} values of the indigenous stable elements (Ag, Cl, Cs, I, Mo, Nb, Ni, Se and Sr) from field moist samples are a valid description of slow retention processes. The 'in situ' K{sub d} desorption values are calculated for humus, peat and different mineral soil samples taken from the Olkiluoto Island and the Reference Area used as an analogue of the future terrain. The solids are extracted alternatively by HNO{sub 3}-HF and NH{sub 4}Ac (pH 4.5). The K{sub d} values are highly dependent on environmental factors, including but not limited to pH, soil type, soil horizon, soil body, texture, element chemical form, organic matter, carbon content and biological activity. This is discussed in the contribution; e.g., for several elements pH and K{sub d} values correlate - the finer the soil or sediment, the higher the K{sub d} values - and humus and peat samples have a clear correlation with the organic matter and carbon contents. The contribution also compares the 'in situ' K{sub d} values to

  14. Estimation of sediment friction coefficient from heating upon APC penetration during the IODP NanTroSEIZE

    Science.gov (United States)

    Kinoshita, M.; Kawamura, K.; Lin, W.

    2015-12-01

    During the Nankai Trough Seismogenic Zone Experiments (NanTroSEIZE) of the Integrated Ocean Drilling Program (IODP), the advanced piston corer temperature (APC-T) tool was used to determine in situ formation temperatures while piston coring down to ~200 m below sea floor. When the corer is fired into the formation, temperature around the shoe abruptly increases due to the frictional heating. The temperature rise due to the frictional heat at the time of penetration is 10 K or larger. We found that the frictional temperature rise (=maximum temperature) increases with increasing depth, and that its intersection at the seafloor seems non-zero. Frictional heat energy is proportional to the maximum temperature rise, which is confirmed by a FEM numerical simulation of 2D cylindrical system. Here we use the result of numerical simulation to convert the observed temperature rise into the frictional heat energy. The frictional heat energy is represented as the product of the shooting length D and the shear stress (τ) between the pipe and the sediment. Assuming a coulomb slip regime, the shear stress is shows as: τ= τ0 + μ*(Sv-Pp), where τ0 is the cohesive stress, μ the dynamic frictional coefficient between the pipe and the sediment, Sv the normal stress at the pipe, and Pp the pore pressure. This can explain the non-zero intersection as well as depth-dependent increase for the frictional heating observed in the APC-T data. Assuming a hydrostatic state and by using the downhole bulk density data, we estimated the friction coefficient for each APC-T measurement. For comparison, we used the vane-shear strength measured on core samples to estimate the friction coefficients. The frictional coefficients μ were estimated as ranging 0.01 - 0.06, anomalously lower than expected for shallow marine sediments. They were lower than those estimated from vane-shear data, which range 0.05 to 0.2. Still, both estimates exhibit a significant increase in the friction coefficient at

  15. Procedures and apparatus for measuring diffusion and distribution coefficients in compacted clays

    Energy Technology Data Exchange (ETDEWEB)

    Hume, H B

    1993-12-01

    Diffusion and distribution coefficients are needed to assess the migration of radionuclides through the compacted clay-based buffer and backfill materials proposed for use in a nuclear fuel waste disposal vault. This report describes the techniques used to measure these coefficients. Both steady-state and transient diffusion experiments are discussed. The procedures used to prepare the clay plug, assemble the cell, conduct the experiment and calculate the results are described. In addition, methods for obtaining distribution coefficients for radionuclides on both loose and compacted clays are discussed. (author). 18 refs., 3 tabs., 16 figs.

  16. Procedures and apparatus for measuring diffusion and distribution coefficients in compacted clays

    International Nuclear Information System (INIS)

    Hume, H.B.

    1993-12-01

    Diffusion and distribution coefficients are needed to assess the migration of radionuclides through the compacted clay-based buffer and backfill materials proposed for use in a nuclear fuel waste disposal vault. This report describes the techniques used to measure these coefficients. Both steady-state and transient diffusion experiments are discussed. The procedures used to prepare the clay plug, assemble the cell, conduct the experiment and calculate the results are described. In addition, methods for obtaining distribution coefficients for radionuclides on both loose and compacted clays are discussed. (author). 18 refs., 3 tabs., 16 figs

  17. Solid/liquid partition coefficients (Kd) for selected soils and sediments at Forsmark and Laxemar-Simpevarp

    Energy Technology Data Exchange (ETDEWEB)

    Sheppard, Steve; Long, Jeff; Sanipelli, Barb [ECOMatters Inc., Pinawa (Canada); Sohlenius, Gustav [Geological Survey of Sweden (SGU), Uppsala (Sweden)

    2009-03-15

    Soil and sediment solid/liquid partition coefficients (Kd) are used to indicate the relative mobility of radionuclides and elements of concern from nuclear fuel waste, as well as from other sources. The Kd data are inherently extremely variable, but also vary systematically with key environmental attributes. For soil Kd, the key variables are pH, clay content and organic carbon content. For sediment Kd, water type (freshwater versus marine) and sediment type (benthic versus suspended) are important. This report summarized Kd data for soils and sediments computed from indigenous stable element concentrations measured at the Forsmark and Laxemar-Simpevarp sites. These were then compared to several literature sources of Kd data for Ce, Cl, Co, Cr, Cs, Fe, Ho, I, La, Mn, Mo, Nb, Nd, Ni, Np, Pa, Pb, Pu, Ra, Sb, Se, Sm, Sn, Sr, Tc, Th, Tm, U and Yb. The Kd data computed from indigenous stable element concentrations may be especially relevant for assessment of long-lived radionuclides from deep disposal of waste, because the long time frame for the potential releases is more consistent with the steady state measured using indigenous stable elements. For almost every one of these elements in soils, a statistically meaningful regression equation was developed to allow estimation of Kd for any soil given a modest amount of information about the soil. Nonetheless, the median residual geometric standard deviation (GSD) was 4.3-fold, implying confidence bounds of about 18-fold above and below the best estimate Kd. For sediment, the values are categorised simply by water type and sediment type. The median GSD for sediment Kd as measured at the Forsmark and Laxemar-Simpevarp sites was 2.5-fold, but the median GSD among literature values was as high as 8.6-fold. Clearly, there remains considerable uncertainty in Kd values, and it is important to account for this in assessment applications

  18. Solid/liquid partition coefficients (Kd) for selected soils and sediments at Forsmark and Laxemar-Simpevarp

    International Nuclear Information System (INIS)

    Sheppard, Steve; Long, Jeff; Sanipelli, Barb; Sohlenius, Gustav

    2009-03-01

    Soil and sediment solid/liquid partition coefficients (Kd) are used to indicate the relative mobility of radionuclides and elements of concern from nuclear fuel waste, as well as from other sources. The Kd data are inherently extremely variable, but also vary systematically with key environmental attributes. For soil Kd, the key variables are pH, clay content and organic carbon content. For sediment Kd, water type (freshwater versus marine) and sediment type (benthic versus suspended) are important. This report summarized Kd data for soils and sediments computed from indigenous stable element concentrations measured at the Forsmark and Laxemar-Simpevarp sites. These were then compared to several literature sources of Kd data for Ce, Cl, Co, Cr, Cs, Fe, Ho, I, La, Mn, Mo, Nb, Nd, Ni, Np, Pa, Pb, Pu, Ra, Sb, Se, Sm, Sn, Sr, Tc, Th, Tm, U and Yb. The Kd data computed from indigenous stable element concentrations may be especially relevant for assessment of long-lived radionuclides from deep disposal of waste, because the long time frame for the potential releases is more consistent with the steady state measured using indigenous stable elements. For almost every one of these elements in soils, a statistically meaningful regression equation was developed to allow estimation of Kd for any soil given a modest amount of information about the soil. Nonetheless, the median residual geometric standard deviation (GSD) was 4.3-fold, implying confidence bounds of about 18-fold above and below the best estimate Kd. For sediment, the values are categorised simply by water type and sediment type. The median GSD for sediment Kd as measured at the Forsmark and Laxemar-Simpevarp sites was 2.5-fold, but the median GSD among literature values was as high as 8.6-fold. Clearly, there remains considerable uncertainty in Kd values, and it is important to account for this in assessment applications

  19. The stochastic distribution of available coefficient of friction on quarry tiles for human locomotion.

    Science.gov (United States)

    Chang, Wen-Ruey; Matz, Simon; Chang, Chien-Chi

    2012-01-01

    The available coefficient of friction (ACOF) for human locomotion is the maximum coefficient of friction that can be supported without a slip at the shoe and floor interface. A statistical model was introduced to estimate the probability of slip by comparing the ACOF with the required coefficient of friction, assuming that both coefficients have stochastic distributions. This paper presents an investigation of the stochastic distributions of the ACOF of quarry tiles under dry, water and glycerol conditions. One hundred friction measurements were performed on a walkway under the surface conditions of dry, water and 45% glycerol concentration. The Kolmogorov-Smirnov goodness-of-fit test was used to determine if the distribution of the ACOF was a good fit with the normal, log-normal and Weibull distributions. The results indicated that the ACOF appears to fit the normal and log-normal distributions better than the Weibull distribution for the water and glycerol conditions. However, no match was found between the distribution of ACOF under the dry condition and any of the three continuous distributions evaluated. Based on limited data, a normal distribution might be more appropriate due to its simplicity, practicality and familiarity among the three distributions evaluated.

  20. The rate coefficients of unimolecular reactions in the systems with power-law distributions

    Science.gov (United States)

    Yin, Cangtao; Guo, Ran; Du, Jiulin

    2014-08-01

    The rate coefficient formulae of unimolecular reactions are generalized to the systems with the power-law distributions based on nonextensive statistics, and the power-law rate coefficients are derived in the high and low pressure limits, respectively. The numerical analyses are made of the rate coefficients as functions of the ν-parameter, the threshold energy, the temperature and the number of degrees of freedom. We show that the new rate coefficients depend strongly on the ν-parameter different from one (thus from a Boltzmann-Gibbs distribution). Two unimolecular reactions, CH3CO→CH3+CO and CH3NC→CH3CN, are taken as application examples to calculate their power-law rate coefficients, which obtained with the ν-parameters slightly different from one can be exactly in agreement with all the experimental studies on these two reactions in the given temperature ranges.

  1. Distribution of Technetium-99 in sub-tidal sediments of the Irish Sea

    Science.gov (United States)

    McCubbin, David; Leonard, Kinson S.; McDonald, Paul; Bonfield, Rachel; Boust, Dominique

    2006-03-01

    To date, relatively little attention has been given to the accumulation of 99Tc discharged from Sellafield in the subtidal sediments of the Irish Sea. The potential implications for secondary seafood contamination from contaminated sediment has driven the UK Food Standards Agency to commission further research into this pathway. The work reported here reviews existing data and provides new measurements of 99Tc specific activity in surface and sub-surface sediments of the Irish Sea, together with environmental Kd values. The results are used to assess the spatial and temporal evolution of 99Tc in the seabed after 8 years of enhanced Sellafield discharges (between 1994 and 2002), of the aforementioned radionuclide. The information is discussed with reference to other studies, in an attempt to infer the processes controlling 99Tc uptake and release from seabed sediments. The average environmental Kd value for 99Tc in the Irish Sea (1.9×10 3) was more than an order of magnitude greater than the presently recommended value of 10 2 [IAEA, 2004. Sediment distribution coefficients and concentration factors for biota in the marine environment. Technical Report Series No. 422, IAEA, Vienna]. Comparison with results from laboratory studies indicates that the observed distribution may represent metastable binding rather than thermodynamic equilibrium. Activities in surface sediments decreased with increasing distance from Sellafield but were also dependent upon the nature of the underlying substrate, being greater on muddy material. Preliminary measurements of grain-size distribution indicated that the observed variation in activities was probably not due to surface area effects. There is an emerging body of evidence from other studies that indicate the differences were most likely due to variations in redox regimes between the different substrates. Vertical profiles were significantly irregular, probably due to the effects of variable sediment mixing processes. Comparison of

  2. 137Cs and 210Pb distribution in Manila Bay sediment

    International Nuclear Information System (INIS)

    Sta. Maria, Efren J.; Madrid, Jordan F.; Olivares, Ryan U.; Bulos, Adelina DM; Dayaon, Jennyvi P.; Asa, Anie Day DC; Sombrito, Elvira Z.

    2011-01-01

    Two radionuclides were measured in surface sediment samples taken from geographically distributed sections of Manila Bay, namely cesium-137 ( 137 Cs) and lead-210 ( 210 Pb). Results indicated a noticeable change in the radioactivity concentration levels in sediments collected in 2005 and 2010, with a median concentration of 1.0 and 2.64 Bq kg -1 , respectively. Higher levels of 137 Cs radioactivity were measured in the northern and inner portion of the bay adjacent to major river systems, agricultural and highly industrialized urban areas. 137 Cs isotope increased in activity in most of the samples especially in the northwestern areas of Bataan and Pampanga with five times more than the activity from the first sampling measurements. Nevertheless, radioactivity concentrations observed in surface sediments along the bay are within the range of radioactivity in several areas monitored in the Northern Hemisphere. The country has been frequented by tropical cyclones and storms that have caused erosion, which may have introduced elevated material input in the bay. In addition, wind-driven circulation especially in the shallower areas of the bay is a possibility for the substantial sediment movement and accumulation along this coast. Conversely, areas with higher 137 Cs have lower values of 210 Pb. In an undisturbed environment, 210 Pb deposition values are assumed nearly constant. Hence, changes in the radioactivity concentration levels of these radionuclides can be an indicator of pollution input from land-based sources, sediment movement and reworking in the coastal areas. At present, there is very limited information on the radioactivity level of various radioisotopes in Manila Bay.The data obtained are benchmark values against which changes that will be occurring in the bay can be assessed. (author)

  3. Use of the lognormal distribution for the coefficients of friction and wear

    International Nuclear Information System (INIS)

    Steele, Clint

    2008-01-01

    To predict the reliability of a system, an engineer might allocate a distribution to each input. This raises a question: how to select the correct distribution? Siddall put forward an evolutionary approach that was intended to utilise both the understanding of the engineer and available data. However, this method requires a subjective initial distribution based on the engineer's understanding of the variable or parameter. If the engineer's understanding is limited, the initial distribution will be misrepresentative of the actual distribution, and application of the method will likely fail. To provide some assistance, the coefficients of friction and wear are considered here. Basic tribology theory, dimensional issues and the central limit theorem are used to argue that the distribution for each of the coefficients will typically be like a lognormal distribution. Empirical evidence from other sources is cited to lend support to this argument. It is concluded that the distributions for the coefficients of friction and wear would typically be lognormal in nature. It is therefore recommended that the engineer, without data or evidence to suggest differently, should allocate a lognormal distribution to the coefficients of friction and wear

  4. The distribution dynamics and desorption behaviour of mobile pharmaceuticals and caffeine to combined sewer sediments.

    Science.gov (United States)

    Hajj-Mohamad, M; Darwano, H; Duy, S Vo; Sauvé, S; Prévost, M; Arp, H P H; Dorner, S

    2017-01-01

    Pharmaceuticals are discharged to the environment from wastewater resource recovery facilities, sewer overflows, and illicit sewer connections. To understand the fate of pharmaceuticals, there is a need to better understand their sorption dynamics to suspended sediments (SS) and settled sediments (StS) in sewer systems. In this study, such sorption dynamics to both SS and StS were assessed using a batch equilibrium method under both static and dynamic conditions. Experiments were performed with natively occurring and artificially modified concentrations of sewer pharmaceuticals (acetaminophen, theophylline, carbamazepine, and a metabolite of carbamazepine) and caffeine. Differences in apparent distribution coefficients, K d,app , between SS and StS were related to differences in their organic carbon (OC) content, and the practice of artificially modifying the concentration. K d,app values of modified contaminant concentrations and high OC sediments were substantially higher. Pseudo-second order desorption rates for these mobile compounds were also quantified. Successive flushing events to simulate the addition of stormwater to sewer networks revealed that aqueous concentrations would not necessarily decrease, because the added water will rapidly return to equilibrium concentrations with the sediments. Sorption and desorption kinetics must be considered in addition to dilution, to avoid underestimating the influence of dilution on concentrations of pharmaceuticals discharged to the environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Measurement of distribution coefficients of U series radionuclides on soils under shallow land environment (2). pH dependence of distribution coefficients

    International Nuclear Information System (INIS)

    Sakamoto, Yoshiaki; Takebe, Shinichi; Ogawa, Hiromichi; Inagawa, Satoshi; Sasaki, Tomozou

    2001-01-01

    In order to study sorption behavior of U series radionuclides (Pb, Ra, Th, Ac, Pa and U) under aerated zone environment (loam-rain water system) and aquifer environment (sand-groundwater system) for safety assessment of U bearing waste, pH dependence of distribution coefficients of each element has been obtained. The pH dependence of distribution coefficients of Pb, Ra, Th, Ac and U was analyzed by model calculation based on aqueous speciation of each element and soil surface charge characteristics, which is composed of a cation exchange capacity and surface hydroxyl groups. From the model calculation, the sorption behavior of Pb, Ra, Th, Ac and U could be described by a combination of cation exchange reaction and surface-complexation model. (author)

  6. Distribution functions to estimate radionuclide solid-liquid distribution coefficients in soils: the case of Cs

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez-Guinart, Oriol; Rigol, Anna; Vidal, Miquel [Analytical Chemistry department, Faculty of Chemistry, University of Barcelona, Mart i Franques 1-11, 08028, Barcelona (Spain)

    2014-07-01

    In the frame of the revision of the IAEA TRS 364 (Handbook of parameter values for the prediction of radionuclide transfer in temperate environments), a database of radionuclide solid-liquid distribution coefficients (K{sub d}) in soils was compiled with data coming from field and laboratory experiments, from references mostly from 1990 onwards, including data from reports, reviewed papers, and grey literature. The K{sub d} values were grouped for each radionuclide according to two criteria. The first criterion was based on the sand and clay mineral percentages referred to the mineral matter, and the organic matter (OM) content in the soil. This defined the 'texture/OM' criterion. The second criterion was to group soils regarding specific soil factors governing the radionuclide-soil interaction ('cofactor' criterion). The cofactors depended on the radionuclide considered. An advantage of using cofactors was that the variability of K{sub d} ranges for a given soil group decreased considerably compared with that observed when the classification was based solely on sand, clay and organic matter contents. The K{sub d} best estimates were defined as the calculated GM values assuming that K{sub d} values were always log-normally distributed. Risk assessment models may require as input data for a given parameter either a single value (a best estimate) or a continuous function from which not only individual best estimates but also confidence ranges and data variability can be derived. In the case of the K{sub d} parameter, a suitable continuous function which contains the statistical parameters (e.g. arithmetical/geometric mean, arithmetical/geometric standard deviation, mode, etc.) that better explain the distribution among the K{sub d} values of a dataset is the Cumulative Distribution Function (CDF). To our knowledge, appropriate CDFs has not been proposed for radionuclide K{sub d} in soils yet. Therefore, the aim of this works is to create CDFs for

  7. Empirical Sampling Distributions of Equating Coefficients for Graded and Nominal Response Instruments.

    Science.gov (United States)

    Baker, Frank B.

    1997-01-01

    Examined the sampling distributions of equating coefficients produced by the characteristic curve method for tests using graded and nominal response scoring using simulated data. For both models and across all three equating situations, the sampling distributions were generally bell-shaped and peaked, and occasionally had a small degree of…

  8. A comparative study of distribution coefficients (Kd) for naturally occurring Uranium (U) and Thorium (Th) in two different aquatic environments

    International Nuclear Information System (INIS)

    Kumar, Ajay; Karpe, Rupali; Rout, Sabyasachi; Narayanan, Usha; Ravi, P.M.

    2012-01-01

    The uranium and thorium contents and their mobility in aqueous systems are mainly controlled by the pH, alkalinity, the oxidation reduction potential (ORP) and the type of complexing agents present, such as carbonates, phosphates, vanadates, fluorides, sulfates and silicates, etc. A comparative study of distribution coefficients (K d ) for U and Th in sediment-seawater and soil-groundwater system has been carried out. K d was determined using a batch method. In this method, 5 g dried sediment samples was placed in each of seven empty conical flasks and equilibrated for 7 days with 150 mL of sea water containing 10, 20, 30, 40, 50, 75 and 100 mg/L of uranium and thorium contents followed by shaking using end-over end shaker at 25°C. After equilibration time, the samples of each set were centrifuged, filtered through 0.45 μm filter paper and supernatant analyzed for uranium and thorium. In the similar way, experiments were conducted for soil-groundwater system. The concentration of uranium in aliquots of equilibrium solution was measured using laser fluorimeter and Th was determined using anion exchange column followed by co-precipitation with ferric hydroxide and estimated by gross alpha counter. Physico-chemical parameters of soil, sediments, seawater and groundwater were also studied. In this study, K d values have been reported as the mean from two sets of experimental determinations. Based on the resulting data set, it can be concluded that K d values of uranium and thorium are not only dependent on properties of adsorbed phases but also on the kinds of minerals present in that medium. The results of K d values obtained indicated that the sediments have better sorption properties than soil

  9. Shallow gas charged sediments off the Indian west coast: Genesis and distribution

    Digital Repository Service at National Institute of Oceanography (India)

    Mazumdar, A.; Peketi, A.; Dewangan, P.; Badesab, F.K.; Ramprasad, T; Ramana, M.V.; Patil, D.J.; Dayal, A.M.

    Geophysical and geochemical surveys were carried out off Goa, central west coast of India, to understand the genesis and distribution of shallow gases in marine sediments. Shallow gas charged sediments within the water depths of approx. 15 to 40 m...

  10. Vertical distribution of 137Cs in lake sediments in post-Chernobyl period

    International Nuclear Information System (INIS)

    Gorgun, T.V.; Putyrskaya, V.V.; Klemt, E.; Goncharova, N.V.

    2011-01-01

    The vertical distribution of 137 Cs was studied in one of the glacial lakes situated in the region of Tuchola Forest National Park (Poland). Radiocaesium was used for sedimentation rates estimation and dating of the sediment layers of the lake.

  11. Standard test method for distribution coefficients of inorganic species by the batch method

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method covers the determination of distribution coefficients of chemical species to quantify uptake onto solid materials by a batch sorption technique. It is a laboratory method primarily intended to assess sorption of dissolved ionic species subject to migration through pores and interstices of site specific geomedia. It may also be applied to other materials such as manufactured adsorption media and construction materials. Application of the results to long-term field behavior is not addressed in this method. Distribution coefficients for radionuclides in selected geomedia are commonly determined for the purpose of assessing potential migratory behavior of contaminants in the subsurface of contaminated sites and waste disposal facilities. This test method is also applicable to studies for parametric studies of the variables and mechanisms which contribute to the measured distribution coefficient. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement a...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-04-01

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

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

    International Nuclear Information System (INIS)

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

    1995-04-01

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

  14. Biot's coefficient as an indicator of strength and porosity reduction: Calcareous sediments from Kerguelen Plateau

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Borre, Mai Kirstine; Fabricius, Ida Lykke

    2010-01-01

    β to fall, even when porosity remains constant. Biot's coefficient correlates with strength-indicating properties: compressional and shear modulus, oedometer modulus, yield strength, strain from direct loading and creep strain. Our data indicate that β may be used for predicting the diagenetic...... Biot's coefficient, β. In calcareous ooze, β is one. Mechanical compaction reduces porosity, but only leads to a minor decrease in β. Recrystallization renders particles smoother, but does not lead to reduction in β unless it gives rise to pore stiffening cementation. Pore stiffening cementation causes...

  15. Distribution of trace elements in the coastal sea sediments of Maslinica Bay, Croatia

    Science.gov (United States)

    Mikulic, Nenad; Orescanin, Visnja; Elez, Loris; Pavicic, Ljiljana; Pezelj, Durdica; Lovrencic, Ivanka; Lulic, Stipe

    2008-02-01

    Spatial distributions of trace elements in the coastal sea sediments and water of Maslinica Bay (Southern Adriatic), Croatia and possible changes in marine flora and foraminifera communities due to pollution were investigated. Macro, micro and trace elements’ distributions in five granulometric fractions were determined for each sediment sample. Bulk sediment samples were also subjected to leaching tests. Elemental concentrations in sediments, sediment extracts and seawater were measured by source excited energy dispersive X-ray fluorescence (EDXRF). Concentrations of the elements Cr, Cu, Zn, and Pb in bulk sediment samples taken in the Maslinica Bay were from 2.1 to over six times enriched when compared with the background level determined for coarse grained carbonate sediments. A low degree of trace elements leaching determined for bulk sediments pointed to strong bonding of trace elements to sediment mineral phases. The analyses of marine flora pointed to higher eutrophication, which disturbs the balance between communities and natural habitats.

  16. A methodology to quantify the stochastic distribution of friction coefficient required for level walking.

    Science.gov (United States)

    Chang, Wen-Ruey; Chang, Chien-Chi; Matz, Simon; Lesch, Mary F

    2008-11-01

    The required friction coefficient is defined as the minimum friction needed at the shoe and floor interface to support human locomotion. The available friction is the maximum friction coefficient that can be supported without a slip at the shoe and floor interface. A statistical model was recently introduced to estimate the probability of slip and fall incidents by comparing the available friction with the required friction, assuming that both the available and required friction coefficients have stochastic distributions. This paper presents a methodology to investigate the stochastic distributions of the required friction coefficient for level walking. In this experiment, a walkway with a layout of three force plates was specially designed in order to capture a large number of successful strikes without causing fatigue in participants. The required coefficient of friction data of one participant, who repeatedly walked on this walkway under four different walking conditions, is presented as an example of the readiness of the methodology examined in this paper. The results of the Kolmogorov-Smirnov goodness-of-fit test indicated that the required friction coefficient generated from each foot and walking condition by this participant appears to fit the normal, log-normal or Weibull distributions with few exceptions. Among these three distributions, the normal distribution appears to fit all the data generated with this participant. The average of successful strikes for each walk achieved with three force plates in this experiment was 2.49, ranging from 2.14 to 2.95 for each walking condition. The methodology and layout of the experimental apparatus presented in this paper are suitable for being applied to a full-scale study.

  17. Analysis of Grain Size Distribution and Hydraulic Conductivity for a Variety of Sediment Types with Application to Wadi Sediments

    KAUST Repository

    Rosas Aguilar, Jorge

    2013-01-01

    Grain size distribution, porosity, and hydraulic conductivity from over 400 unlithified sediment samples were analized. The measured hydraulic conductivity values were then compared to values calculated using 20 different empirical equations

  18. Distribution of clay minerals in marine sediments off Chennai, Bay of Bengal, India: Indicators of sediment sources and transport processes .

    Digital Repository Service at National Institute of Oceanography (India)

    Veerasingam, S.; Venkatachalapathy, R.; Ramkumar, T.

    Clay mineralogy, texture size and statistical analyses were carried out on surface sediments from the continental shelf of Chennai, Bay of Bengal, India. The purpose of this study is to characterize the clay mineral distribution and its relation...

  19. On the construction of bivariate exponential distributions with an arbitrary correlation coefficient

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    In this paper we use a concept of multivariate phase-type distributions to define a class of bivariate exponential distributions. This class has the following three appealing properties. Firstly, we may construct a pair of exponentially distributed random variables with any feasible correlation...... coefficient (also negative). Secondly, the class satisfies that any linear combination (projection) of the marginal random variables is a phase {type distributions, The latter property is potentially important for the development hypothesis testing in linear models. Thirdly, it is very easy to simulate...

  20. Inverse modelling of fluvial sediment connectivity identifies characteristics and spatial distribution of sediment sources in a large river network.

    Science.gov (United States)

    Schmitt, R. J. P.; Bizzi, S.; Kondolf, G. M.; Rubin, Z.; Castelletti, A.

    2016-12-01

    Field and laboratory evidence indicates that the spatial distribution of transport in both alluvial and bedrock rivers is an adaptation to sediment supply. Sediment supply, in turn, depends on spatial distribution and properties (e.g., grain sizes and supply rates) of individual sediment sources. Analyzing the distribution of transport capacity in a river network could hence clarify the spatial distribution and properties of sediment sources. Yet, challenges include a) identifying magnitude and spatial distribution of transport capacity for each of multiple grain sizes being simultaneously transported, and b) estimating source grain sizes and supply rates, both at network scales. Herein, we approach the problem of identifying the spatial distribution of sediment sources and the resulting network sediment fluxes in a major, poorly monitored tributary (80,000 km2) of the Mekong. Therefore, we apply the CASCADE modeling framework (Schmitt et al. (2016)). CASCADE calculates transport capacities and sediment fluxes for multiple grainsizes on the network scale based on remotely-sensed morphology and modelled hydrology. CASCADE is run in an inverse Monte Carlo approach for 7500 random initializations of source grain sizes. In all runs, supply of each source is inferred from the minimum downstream transport capacity for the source grain size. Results for each realization are compared to sparse available sedimentary records. Only 1 % of initializations reproduced the sedimentary record. Results for these realizations revealed a spatial pattern in source supply rates, grain sizes, and network sediment fluxes that correlated well with map-derived patterns in lithology and river-morphology. Hence, we propose that observable river hydro-morphology contains information on upstream source properties that can be back-calculated using an inverse modeling approach. Such an approach could be coupled to more detailed models of hillslope processes in future to derive integrated models

  1. New empirical relationship between grain size distribution and hydraulic conductivity for ephemeral streambed sediments

    KAUST Repository

    Rosas, Jorge

    2014-07-19

    Grain size distribution, porosity, and hydraulic conductivity were determined for 39 sediment samples collected from ephemeral streams (wadis) in western Saudi Arabia. The measured hydraulic conductivity values were then compared to values calculated using 20 different empirical equations commonly used to estimate hydraulic conductivity from grain size analyses. It was found that most of the hydraulic conductivity values estimated from the empirical equations correlated very poorly with the measured hydraulic conductivity values. Modifications of the empirical equations, including changes to special coefficients and statistical offsets, were made to produce modified equations that considerably improved the hydraulic conductivity estimates from grain size data for wadi sediments. The Chapuis, Hazen, Kozeny, Slichter, Terzaghi, and Barr equations produced the best correlations, but still had relatively high predictive errors. The Chapius equation was modified for wadi sediments by incorporating mud percentage and the standard deviation (in phi units) into a new equation that reduced the predicted hydraulic conductivity error to ±14.1 m/day. The equation is best applied to ephemeral stream samples that have hydraulic conductive values greater than 2 m/day.

  2. New empirical relationship between grain size distribution and hydraulic conductivity for ephemeral streambed sediments

    KAUST Repository

    Rosas, Jorge; Jadoon, Khan; Missimer, Thomas M.

    2014-01-01

    Grain size distribution, porosity, and hydraulic conductivity were determined for 39 sediment samples collected from ephemeral streams (wadis) in western Saudi Arabia. The measured hydraulic conductivity values were then compared to values calculated using 20 different empirical equations commonly used to estimate hydraulic conductivity from grain size analyses. It was found that most of the hydraulic conductivity values estimated from the empirical equations correlated very poorly with the measured hydraulic conductivity values. Modifications of the empirical equations, including changes to special coefficients and statistical offsets, were made to produce modified equations that considerably improved the hydraulic conductivity estimates from grain size data for wadi sediments. The Chapuis, Hazen, Kozeny, Slichter, Terzaghi, and Barr equations produced the best correlations, but still had relatively high predictive errors. The Chapius equation was modified for wadi sediments by incorporating mud percentage and the standard deviation (in phi units) into a new equation that reduced the predicted hydraulic conductivity error to ±14.1 m/day. The equation is best applied to ephemeral stream samples that have hydraulic conductive values greater than 2 m/day.

  3. The stochastic distribution of available coefficient of friction for human locomotion of five different floor surfaces.

    Science.gov (United States)

    Chang, Wen-Ruey; Matz, Simon; Chang, Chien-Chi

    2014-05-01

    The maximum coefficient of friction that can be supported at the shoe and floor interface without a slip is usually called the available coefficient of friction (ACOF) for human locomotion. The probability of a slip could be estimated using a statistical model by comparing the ACOF with the required coefficient of friction (RCOF), assuming that both coefficients have stochastic distributions. An investigation of the stochastic distributions of the ACOF of five different floor surfaces under dry, water and glycerol conditions is presented in this paper. One hundred friction measurements were performed on each floor surface under each surface condition. The Kolmogorov-Smirnov goodness-of-fit test was used to determine if the distribution of the ACOF was a good fit with the normal, log-normal and Weibull distributions. The results indicated that the ACOF distributions had a slightly better match with the normal and log-normal distributions than with the Weibull in only three out of 15 cases with a statistical significance. The results are far more complex than what had heretofore been published and different scenarios could emerge. Since the ACOF is compared with the RCOF for the estimate of slip probability, the distribution of the ACOF in seven cases could be considered a constant for this purpose when the ACOF is much lower or higher than the RCOF. A few cases could be represented by a normal distribution for practical reasons based on their skewness and kurtosis values without a statistical significance. No representation could be found in three cases out of 15. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  4. Distribution coefficients of purine alkaloids in water-ammonium sulfate-alkyl acetate-dialkyl phthalate systems

    Science.gov (United States)

    Korenman, Ya. I.; Krivosheeva, O. A.; Mokshina, N. Ya.

    2012-12-01

    The distribution of purine alkaloids (caffeine, theobromine, theophylline) was studied in the systems: alkyl acetates-dialkyl phtalate-salting-out agent (ammonium sulfate). The quantitative characteristics of the extraction-distribution coefficients ( D) and the degree of extraction ( R, %) are calculated. The relationships between the distribution coefficients of alkaloids and the length of the hydrocarbon radical in the molecule of alkyl acetate (dialkyl phtalate) are determined. The possibility of predicting the distribution coefficients is demonstrated.

  5. On the Construction of Bivariate Exponential Distributions with an Arbitrary Correlation Coefficient

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    2010-01-01

    coefficient (also negative). Secondly, the class satisfies that any linear combination (projection) of the marginal random variables is a phase-type distribution. The latter property is partially important for the development of hypothesis testing in linear models. Finally, it is easy to simulate...

  6. Estimation of the location parameter of distributions with known coefficient of variation by record values

    Directory of Open Access Journals (Sweden)

    N. K. Sajeevkumar

    2014-09-01

    Full Text Available In this article, we derived the Best Linear Unbiased Estimator (BLUE of the location parameter of certain distributions with known coefficient of variation by record values. Efficiency comparisons are also made on the proposed estimator with some of the usual estimators. Finally we give a real life data to explain the utility of results developed in this article.

  7. Estimation of the distribution coefficient by combined application of two different methods

    International Nuclear Information System (INIS)

    Vogl, G.; Gerstenbrand, F.

    1982-01-01

    A simple, non-invasive method is presented which permits determination of the rBCF and, in addition, of the distribution coefficient of the grey matter. The latter, which is closely correlated with the cerebral metabolism, has only been determined in vitro so far. The new method will be a means to check its accuracy. (orig.) [de

  8. A simple approximation to the bivariate normal distribution with large correlation coefficient

    NARCIS (Netherlands)

    Albers, Willem/Wim; Kallenberg, W.C.M.

    1994-01-01

    The bivariate normal distribution function is approximated with emphasis on situations where the correlation coefficient is large. The high accuracy of the approximation is illustrated by numerical examples. Moreover, exact upper and lower bounds are presented as well as asymptotic results on the

  9. Geochemistry and distribution of sediments in the East Indian shelf ...

    Indian Academy of Sciences (India)

    29

    trace element geochemistry yielded interesting results about the sediment .... sediments and the core samples are as given in Table 1. ..... radioactive lead, thorium and uranium showed higher concentration in C3 than in C1 ...... Plant Soil, 267,.

  10. Vertical distribution of 241Pu in the southern Baltic Sea sediments

    International Nuclear Information System (INIS)

    Strumińska-Parulska, Dagmara I.

    2014-01-01

    Highlights: • The unique study on 241 Pu in sediments from the southern Baltic Sea was presented. • 241 Pu was determined using alpha spectrometry by indirect method. • The biggest amount of 241 Pu existed in the surface layers of all analyzed sediments. • The highest 241 Pu amount comes from the Chernobyl accident. - Abstract: The vertical distribution of plutonium 241 Pu in marine sediments can assist in determining the deposition history and sedimentation process of analyzed regions. In addition, 241 Pu/ 239+240 Pu activity ratio could be used as a sensitive fingerprint for radioactive source identification. The present preliminary studies on vertical distribution of 241 Pu in sediments from four regions of the southern Baltic Sea are presented. The distribution of 241 Pu was not uniform and depended on sediment geomorphology and depth as well as location. The highest concentrations of plutonium were found in the surface layers of all analyzed sediments and originated from the Chernobyl accident

  11. [Distribution Characteristics and Pollution Status Evaluation of Sediments Nutrients in a Drinking Water Reservoir].

    Science.gov (United States)

    Huang, Ting-lin; Liu, Fei; Shi, Jian-chao

    2016-01-15

    The main purpose of this paper is to illustrate the influence of nutrients distribution in sediments on the eutrophication of drinking water reservoir. The sediments of three representative locations were field-sampled and analyzed in laboratory in March 2015. The distribution characteristics of TOC, TN and TP were measured, and the pollution status of sediments was evaluated by the comprehensive pollution index and the manual for sediment quality assessment. The content of TOC in sediments decreased with depth, and there was an increasing trend of the nitrogen content. The TP was enriched in surface sediment, implying the nutrients load in Zhoucun Reservoir was aggravating as the result of human activities. Regression analysis indicated that the content of TOC in sediments was positively correlated with contents of TN and TP in sediments. The TOC/TN values reflected that the vascular land plants, which contain cellulose, were the main source of organic matter in sediments. The comprehensive pollution index analysis result showed that the surface sediments in all three sampling sites were heavily polluted. The contents of TN and TP of surface sediments in three sampling sites were 3273-4870 mg x kg(-1) and 653-2969 mg x kg(-1), and the content of TOC was 45.65-83.00 mg x g(-1). According to the manual for sediment quality assessment, the TN, TP and TOC contents in sediments exceed the standard values for the lowest level of ecotoxicity, so there is a risk of eutrophication in Zhoucun Reservoir.

  12. Distribution of physicians and hospital beds based on Gini coefficient and Lorenz curve: A national survey

    Directory of Open Access Journals (Sweden)

    Satar Rezaei

    2016-06-01

    Full Text Available Introduction: Inequality is prevalent in all sectors, particularly in distribution of and access to resources in the health sector. The aim of current study was to investigate the distribution of physicians and hospital beds in Iran in 2001, 2006 and 2011. Methods: This retrospective, cross-sectional study evaluated the distribution of physicians and hospital beds in 2001, 2006 and 2011 using Gini coefficient and Lorenz curve. The required data, including the number of physicians (general practitioners and specialists, number of hospital beds and number of hospitalized patients were obtained from the statistical yearbook of Iranian Statistical Center (ISC. The data analysis was performed by DASP software. Results: The Gini Coefficients for physicians and hospital beds based on population in 2001 were 0.19 and 0.16, and based on hospitalized patients, were 0.48 and 0.37, respectively. In 2006, these values were found to be 0.18 and 0.15 based on population, and 0.21 and 0.21 based on hospitalized patients, respectively. In 2011, however, the Gini coefficients were reported to be 0.16 and 0.13 based on population, and 0.47 and 0.37 based on hospitalized patients, respectively. Although distribution status had improved in 2011compared with 2001 in terms of population and number of hospitalized patients, there was more inequality in distribution based on the number of hospitalized patients than based on population. Conclusion: This study indicated that inequality in distribution of physicians and hospital beds was declined in 2011 compared with 2001. This distribution was based on the population, so it is suggested that, in allocation of resource, the health policymakers consider such need indices as the pattern of diseases and illness-prone areas, number of inpatients, and mortality.

  13. Distribution coefficient of radionuclides on rocks for performance assessment of high-level radioactive waste repository

    International Nuclear Information System (INIS)

    Shibutani, Tomoki; Shibata, Masahiro; Suyama, Tadahiro

    1999-11-01

    Distribution coefficients of radionuclides on rocks are selected for safety assessment in the 'Second Progress Report on Research and Development for the geological disposal of HLW in Japan (H12 Report)'. The categorized types of rock are granitic rocks (crystalline and acidic rocks), basaltic rocks (crystalline and basic rocks), psammitic rocks (neogene sedimentary (soft)), and tuffaceous-pelitic rocks (pre-neogene sedimentary rocks (hard)). The types of groundwater are FRHP (fresh reducing high-pH), FRLP (fresh reducing low-pH), SRHP (saline reducing high-pH), SRLP (saline reducing low-pH), MRNP (mixing reducing neutral-pH) and FOHP (fresh oxidizing high-pH) groundwater. The elements to be surveyed are Ni, Se, Zr, Nb, Tc, Pd, Sn, Cs, Sm, Pb, Ra, Ac, Th, Pa, U, Np, Pu, Am and Cm. Distribution coefficients are collected from literatures describing batch sorption experimental results, and are selected under consideration of conservativity. (author)

  14. Influence of radon diffusion on the 210Pb distribution in sediments

    International Nuclear Information System (INIS)

    Imboden, D.M.; Stiller, M.

    1982-01-01

    A mathematical model is presented which describes the distribution of radon 222 in sediments having a constant or variable depth distribution of radium 226. The model is extended to the distribution of lead 210, taking into account the mobility of radon (the precursor of 210 Pb) within the sediment column. The 210 Pb model is compared, at constant radium activity, with the conventional approach which disregards the radon diffusion when estimating sedimentation rates by the 210 Pb method. The ratio between apparent and real sedimentation rate, s'/s, expressed as a function of three dimensionless parameters, demonstrates the importance of the radon diffusion effect. This effect is particularly important for sediments with small initial excess 210 Pb activity, small sedimentation rate, large radon diffusivity, or a combination of these factors. Applied to Lake Geneva, the sedimentation is estimated to be larger by 30--50% than the original value by Krishnaswami et al, (1971). In sediments which are mixed at the surface (physical mixing or bioturbation), the 210 PB activity in the mixed layer is diminished compared to that in the settling sediment material (Robbins et al., 1977), and radon diffusion makes the activity difference even larger, especially for low initial excess 210 Pb activity, small sedimentation rate, and large mixing intensity. This result may be of importance for the balance of 210 Pb in an aquatic system if the calculations are based on activities measured in the sediment

  15. Distribution Coefficient Kd of Cesium in Soils from Areas in Perak

    International Nuclear Information System (INIS)

    Azian Hashim; Mohd Suhaimi Hamzah; Shamsiah Abdul Rahman; Nazaratul Ashifa Abdullah Salim; Md Suhaimi Elias; Shakirah Shukor; Muhd Azfar Azman; Siti Aminah Omar

    2015-01-01

    This is the paper reports on the study of distribution coefficient or Kd value in soil collected from the Western of Perak, which is Manjung, Setiawan, and Lahat with two different depths using lab batch method. Particle sizes were analyzed using the conventional technique known as pipette method. pH of the sample were 2-3. Determinations for cesium were performed using Inductively Coupled Plasma-Mass (ICP-MS). From the results, distribution factor for cesium, Kd value, was found to be influenced by the particle size of soil. (author)

  16. Transformation of correlation coefficients between normal and lognormal distribution and implications for nuclear applications

    Energy Technology Data Exchange (ETDEWEB)

    Žerovnik, Gašper, E-mail: gasper.zerovnik@ijs.si [Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Trkov, Andrej, E-mail: andrej.trkov@ijs.si [Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Smith, Donald L., E-mail: donald.l.smith@anl.gov [Argonne National Laboratory, 1710 Avenida del Mundo, Coronado, CA 92118-3073 (United States); Capote, Roberto, E-mail: roberto.capotenoy@iaea.org [NAPC–Nuclear Data Section, International Atomic Energy Agency, PO Box 100, Vienna-A-1400 (Austria)

    2013-11-01

    Inherently positive parameters with large relative uncertainties (typically ≳30%) are often considered to be governed by the lognormal distribution. This assumption has the practical benefit of avoiding the possibility of sampling negative values in stochastic applications. Furthermore, it is typically assumed that the correlation coefficients for comparable multivariate normal and lognormal distributions are equivalent. However, this ideal situation is approached only in the linear approximation which happens to be applicable just for small uncertainties. This paper derives and discusses the proper transformation of correlation coefficients between both distributions for the most general case which is applicable for arbitrary uncertainties. It is seen that for lognormal distributions with large relative uncertainties strong anti-correlations (negative correlations) are mathematically forbidden. This is due to the asymmetry that is an inherent feature of these distributions. Some implications of these results for practical nuclear applications are discussed and they are illustrated with examples in this paper. Finally, modifications to the ENDF-6 format used for representing uncertainties in evaluated nuclear data libraries are suggested, as needed to deal with this issue.

  17. Transformation of correlation coefficients between normal and lognormal distribution and implications for nuclear applications

    International Nuclear Information System (INIS)

    Žerovnik, Gašper; Trkov, Andrej; Smith, Donald L.; Capote, Roberto

    2013-01-01

    Inherently positive parameters with large relative uncertainties (typically ≳30%) are often considered to be governed by the lognormal distribution. This assumption has the practical benefit of avoiding the possibility of sampling negative values in stochastic applications. Furthermore, it is typically assumed that the correlation coefficients for comparable multivariate normal and lognormal distributions are equivalent. However, this ideal situation is approached only in the linear approximation which happens to be applicable just for small uncertainties. This paper derives and discusses the proper transformation of correlation coefficients between both distributions for the most general case which is applicable for arbitrary uncertainties. It is seen that for lognormal distributions with large relative uncertainties strong anti-correlations (negative correlations) are mathematically forbidden. This is due to the asymmetry that is an inherent feature of these distributions. Some implications of these results for practical nuclear applications are discussed and they are illustrated with examples in this paper. Finally, modifications to the ENDF-6 format used for representing uncertainties in evaluated nuclear data libraries are suggested, as needed to deal with this issue

  18. Cadmium, lead and organic matter distribution in coastal sediment from the Adriatic Sea

    International Nuclear Information System (INIS)

    Ujevic, I.; Bogner, D.; Baric, A.

    1999-01-01

    The spatial distribution of Cd, and Pb has been studied in surface sediments of the eastern Adriatic coastal region. In addition, Pb concentration has been determined in long sediment cores dating back to pre-industrial time. The results indicate that trace metal concentrations in surface sediment layer depend both on pollution sources, and on local characteristics of the marine and terrestrial environment. Generally, most of the concentrations are not high revealing that the coastal area is not heavily polluted. Granulometric and geochemical data indicate the existence of some differences between sediments formed in the vicinity of fresh water input and sediments from areas without fresh water input. (author)

  19. Are distribution coefficients measured from batch experiments meaningful for quantifying retention in compacted material?

    Energy Technology Data Exchange (ETDEWEB)

    Goutelard, F.; Charles, Y.; Page, J. [CEA/DEN/DPC/SECR/L3MR batiment 450, 91191 Gif sur Yvette (France)

    2005-07-01

    Full text of publication follows: To quantify the ability of a clayey material to act as a barrier for radionuclides migration, reliable data on retention properties must be available. The most common method for determining the distribution coefficient, quantifying the radionuclide adsorption, is the batch technique applied to powdered solid. Are these data meaningful for highly compacted minerals? This question is still under debate in literature [1,2]. The aim of the present study is to compare distribution coefficient (KD) value for Cs and Ni onto compacted and dispersed for both Bentonite MX80 and Callovo-Oxfordian clayey material in a simulated site water. Firstly, classical batch sorption experiments are carried on dispersed materials pre-conditioned with the simulated site water at pH 7.3. Radiotracer {sup 137}Cs and {sup 58}Ni are used to investigate the constant-pH isotherm sorption. The bottleneck for measuring distribution coefficient onto highly compacted material lies in a careful monitoring of chemical conditions because they are driven by diffusion processes. For this study, we have chosen to use in-diffusion experiments [3]. Sample size is optimized to reach for high retention level (300 mL/g) the steady state in a reasonable time (3 to 6 month). In order to describe the response surface of compacted distribution coefficient on bentonite MX80, a 2 variables Doehlert matrix has been chosen. In this experimental design, the two variables are density and dispersed distribution coefficient. Bentonite is pre-conditioning before compaction to a density ranging from 1.2 to 1.85 kg/l. The pellet is confined in a cylindrical stainless steel filter (150 {mu}L) closed to both ends. The cell is placed in a tightly closed bottle containing the working solution. After a re-equilibration period (at least 3 weeks), {sup 133}Cs and {sup 59}Ni stable isotope are introduced for monitoring the KD level (between 150 mL/g to 330 mL/g). Radiotracer {sup 137}Cs and {sup 58

  20. Are distribution coefficients measured from batch experiments meaningful for quantifying retention in compacted material?

    International Nuclear Information System (INIS)

    Goutelard, F.; Charles, Y.; Page, J.

    2005-01-01

    Full text of publication follows: To quantify the ability of a clayey material to act as a barrier for radionuclides migration, reliable data on retention properties must be available. The most common method for determining the distribution coefficient, quantifying the radionuclide adsorption, is the batch technique applied to powdered solid. Are these data meaningful for highly compacted minerals? This question is still under debate in literature [1,2]. The aim of the present study is to compare distribution coefficient (KD) value for Cs and Ni onto compacted and dispersed for both Bentonite MX80 and Callovo-Oxfordian clayey material in a simulated site water. Firstly, classical batch sorption experiments are carried on dispersed materials pre-conditioned with the simulated site water at pH 7.3. Radiotracer 137 Cs and 58 Ni are used to investigate the constant-pH isotherm sorption. The bottleneck for measuring distribution coefficient onto highly compacted material lies in a careful monitoring of chemical conditions because they are driven by diffusion processes. For this study, we have chosen to use in-diffusion experiments [3]. Sample size is optimized to reach for high retention level (300 mL/g) the steady state in a reasonable time (3 to 6 month). In order to describe the response surface of compacted distribution coefficient on bentonite MX80, a 2 variables Doehlert matrix has been chosen. In this experimental design, the two variables are density and dispersed distribution coefficient. Bentonite is pre-conditioning before compaction to a density ranging from 1.2 to 1.85 kg/l. The pellet is confined in a cylindrical stainless steel filter (150 μL) closed to both ends. The cell is placed in a tightly closed bottle containing the working solution. After a re-equilibration period (at least 3 weeks), 133 Cs and 59 Ni stable isotope are introduced for monitoring the KD level (between 150 mL/g to 330 mL/g). Radiotracer 137 Cs and 58 Ni are used to quantify the

  1. The distribution of copper in stream sediments in an anomalous stream near Steinkopf, Namaqualand

    International Nuclear Information System (INIS)

    De Bruin, D.

    1987-01-01

    Anomalous copper concentrations detected by the regional stream-sediment programme of the Geological Survey was investigated in a stream near Steinkopf, Namaqualand. A follow-up disclosed the presence of malachite mineralization. However, additional stream-sediment samples collected from the 'anomalous' stream revealed an erratic distribution of copper and also that the malachite mineralization had no direct effect on the copper distribution in the stream sediments. Low partial-extraction yields, together with X-ray diffraction analyses, indicated that dispersion is mainly mechanical and that the copper occurs as cations in the lattice of the biotite fraction of the stream sediments. (author). 8 refs., 5 figs., 1 tab

  2. The distribution of copper in stream sediments in an anomalous stream near Steinkopf, Namaqualand

    Energy Technology Data Exchange (ETDEWEB)

    De Bruin, D

    1987-01-01

    Anomalous copper concentrations detected by the regional stream-sediment programme of the Geological Survey was investigated in a stream near Steinkopf, Namaqualand. A follow-up disclosed the presence of malachite mineralization. However, additional stream-sediment samples collected from the 'anomalous' stream revealed an erratic distribution of copper and also that the malachite mineralization had no direct effect on the copper distribution in the stream sediments. Low partial-extraction yields, together with X-ray diffraction analyses, indicated that dispersion is mainly mechanical and that the copper occurs as cations in the lattice of the biotite fraction of the stream sediments. (author). 8 refs., 5 figs., 1 tab.

  3. 12 Trace Metals Distribution in Fish Tissues, Bottom Sediments and ...

    African Journals Online (AJOL)

    `123456789jkl''''#

    Abstract. Water samples, bottom sediments, Tilapia, and Cat Fish from Okumeshi River in Delta state of Nigeria were analysed ... Keywords: Trace metals, Fish Tissues, Water, Bottom sediments, Okumeshi River. Introduction ..... Grey Mangroove Avicemmia marina (Forsk). ... sewage treatment plant oulet pipe extension on.

  4. The numerical model of the sediment distribution pattern at Lampulo National fisheries port

    Science.gov (United States)

    Irham, M.; Setiawan, I.

    2018-01-01

    The spatial distribution of sediment pattern was studied at Lampulo Fisheries Port, Krueng Aceh estuarial area, Banda Aceh. The research was conducted using the numerical model of wave-induced currents at shallow water area. The study aims to understand how waves and currents react to the pattern of sediment distribution around the beach structure in that region. The study demonstrated that the port pool area had no sedimentation and erosion occurred because the port was protected by the jetty as the breakwater to defend the incoming waves toward the pool. The protected pool created a weak current circulation to distribute the sediments. On the other hand, the sediments were heavily distributed along the beach due to the existence of longshore currents near the shoreline (outside the port pool area). Meanwhile, at the estuarial area, the incoming fresh water flow responded to the coastal shallow water currents, generating Eddy-like flow at the mouth of the river.

  5. Cadmium distribution in sediment profiles of the six main rivers in southern Taiwan

    International Nuclear Information System (INIS)

    Tsai Lijyur; Yu Kuangchung; Ho, S.-T.

    2007-01-01

    Dynamic cadmium distribution has been studied in six main rivers flowing through the largest, most highly developed and polluted area of southern Taiwan. Sediment profile samples were also analyzed for Cu, Cr, Zn, Ni, Pb, Co, Mn, Fe, carbonates, Mn-oxides, Fe-oxides and organic matter in order to characterize the geochemical environment and to identify the pollutant sources. Higher Cd concentrations (about 3.5 mg/kg) at depths of 0-10 cm have been detected in the samples of Yenshui, Ell-ren and Potzu rivers, associated to the history of industrial activity in their catchments. According to the linear correlation coefficient (r) between Cd and the geochemical components, carbonates are the primary Cd binding phase in the Ell-ren river (r = 0.85), and Cd comes from the same pollutant sources of those containing Cr, Ni, Cu and Zn (r > 0.80). Cadmium concentration in the Potzu and Peikang river sediments is probably due to waste deposits rich in Cr and Cu (0.54 < r < 0.65). In the case of the Yenshui river, there is only a weak indication that cadmium derives from waste material containing Cr, Ni, Cu, Zn, and Pb (r around 0.40). On the other hand, in the Tsengwen and Chishui sediments cadmium concentrations seem to represent natural background. Generally, the Ell-ren and Yenshui rivers show strong heavy metal pollution, while no important heavy metal contamination has been found in the Tsengwen, Potzu, Chishui, and Peikang rivers

  6. Engineering magnetic polariton system with distributed coefficients: Applications to soliton management

    International Nuclear Information System (INIS)

    Kuetche, Victor K.; Nguepjouo, Francis T.; Kofane, Timoleon C.

    2014-01-01

    In the wake of the recent design of a powerful method for generating higher-dimensional evolution systems with distributed coefficients Kuetche (2014) [15] illustrated on the dynamics of the current-fed membrane of zero Young’s modulus, we construct the general Lax-representation of a new higher-dimensional coupled evolution equations with varying coefficients. Discussing the physical meanings of these equations, we show that the coupled system above describes the propagation of magnetic polaritons within saturated ferrites, resulting structurally from the fast-near adiabatic magnetization dynamics combined to the Maxwell’s equations. Accordingly, we address some practical issues of the nonautonomous soliton managements underlying in the fast remagnetization process of data inputs within magnetic memory devices

  7. Estimation of soil-soil solution distribution coefficient of radiostrontium using soil properties.

    Science.gov (United States)

    Ishikawa, Nao K; Uchida, Shigeo; Tagami, Keiko

    2009-02-01

    We propose a new approach for estimation of soil-soil solution distribution coefficient (K(d)) of radiostrontium using some selected soil properties. We used 142 Japanese agricultural soil samples (35 Andosol, 25 Cambisol, 77 Fluvisol, and 5 others) for which Sr-K(d) values had been determined by a batch sorption test and listed in our database. Spearman's rank correlation test was carried out to investigate correlations between Sr-K(d) values and soil properties. Electrical conductivity and water soluble Ca had good correlations with Sr-K(d) values for all soil groups. Then, we found a high correlation between the ratio of exchangeable Ca to Ca concentration in water soluble fraction and Sr-K(d) values with correlation coefficient R=0.72. This pointed us toward a relatively easy way to estimate Sr-K(d) values.

  8. Copper, zinc, molybdenum and uranium distribution in bottom sediments of the Black Sea

    International Nuclear Information System (INIS)

    Zhorov, V.A.; Sovga, E.E.; Solov'eva, L.B.; Oguslavskij, P.G.; Babinets, A.E.; AN Ukrainskoj SSR, Kiev. Inst. Geologicheskikh Nauk)

    1983-01-01

    The results of investigations of bottom sediments of the Black Sea by four expeditions aboard scientific ships ''Academician Vernadsky'', ''Michael Lomonosov'', ''Academician Vavilov'' in 1972-1978, are presented. 70 columns of bottom sediments are studied, about 200 samples are analyzed for Cu, Zn, Mo and U using chemical methods with photometric ending. Charts of Cu, Zn, Mo and U distribution in modern, ancient Black Sea and neoeuxenic sediments of the basin are prepared. Preferable uranium concentration in modern sediments, copper and molybdenum - in sapropelic muds of ancient Black Sea sediments and zinc - in neoeuxenic layers, is shown. Uranium geochemical behaviour is determined by physico-chemical regime of the basin, the presence of restoring situation which promotes the formation of uranium sorption-active forms in the upper layer of modern sediments. Neither sapropelite (organic matter), nor the peculiarities of lithological composition of sediments affect uranium behaviour

  9. Fractions and Distribution of Phosphorus in Sediments of the Yarlung Zangbo River Basin

    Science.gov (United States)

    Huang, W.; An, R.; Huang, Y.; Pu, X.; Li, R.; Li, J.

    2017-12-01

    The Yarlung Zangbo River is one of the highest rivers in the world. The ecological environment of the river basin has its specificity. It locates in the remote area of China, and the ecological environment is very fragile. The fundamental data of phosphorus content in sediments of the Yarlung Zangbo River Basin are very scarce. In order to clarify the distribution law of phosphorus in the sediments of this area and provide the fundamental data for the study of phosphorus transport in the Yarlung Zangbo River, the authors collected the sediment samples from the mainstream and its tributaries in the research area. Their particle size distributions, specific surface areas, contents of total phosphorus, organic phosphorus and different forms of inorganic phosphorus were analyzed. Then, the fractions and spatial distribution of these forms phosphorus were studied. The results showed that the fractions and distribution characteristics of phosphorus in each form are significant different in the sediments of the Yarlung Zangbo River. The phosphorus contents in the soil erosion deposits and river bed sediment samples are also different. The phosphorus content in sediment is significantly correlated with the sediment characteristics. Keywords: the Yarlung Zangbo River; sediments; fractions of phosphorus; distribution characteristics

  10. Cumulative history recorded in the depth distribution of radiocesium in sediments deposited on a sandbar

    International Nuclear Information System (INIS)

    Tanaka, Kazuya; Kondo, Hiroaki; Sakaguchi, Aya; Takahashi, Yoshio

    2015-01-01

    We collected sediments deposited on a sandbar from the surface to 20 cm in depth in the Abukuma River to clarify the history of radiocesium derived from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. We analyzed the "1"3"7Cs concentration in the sediments from size-fractioned samples as well as bulk samples. The depth distribution of "1"3"7Cs showed the highest concentration in the deepest sediment layer (18–20 cm) studied, which indicates that sediments with a lower "1"3"7Cs concentration were transported and deposited on sediments having a higher "1"3"7Cs concentration. At the same time, the depth distribution suggests a decrease in radioactivity in provenance areas of the sediments. Analysis of the size-fractioned sediments indicated that the three sediment layers at 4–6 cm, 16–18 cm and 18–20 cm intervals had similar size distribution of "1"3"7Cs and grain size composition although the concentration levels of "1"3"7Cs were different according to their bulk concentrations. The size distribution of "1"3"7Cs also supported the possibility that the decrease in "1"3"7Cs concentration in bulk sediments above 18 cm is due to a decrease in the level of radioactivity in the catchment area. A comparison of the size distribution of "1"3"7Cs between the sediment layers above and below 18 cm suggested that the "1"3"7Cs concentration in the transported fine sediment particles decreased more with time than the "1"3"7Cs concentration in the coarse particles, reflecting the selective transport of the finer particles. The results of this study demonstrated that sediment layers deposited on a sandbar retained the cumulative history of the fluvial transport of radiocesium after the FDNPP accident. - Highlights: • We investigated the history of "1"3"7Cs recorded in sediments in the Abukuma River. • "1"3"7Cs concentration was the highest in the deepest sediment layer studied. • The depth distribution suggests a decrease in radioactivity in

  11. A Spatially Distributed Conceptual Model for Estimating Suspended Sediment Yield in Alpine catchments

    Science.gov (United States)

    Costa, Anna; Molnar, Peter; Anghileri, Daniela

    2017-04-01

    Suspended sediment is associated with nutrient and contaminant transport in water courses. Estimating suspended sediment load is relevant for water-quality assessment, recreational activities, reservoir sedimentation issues, and ecological habitat assessment. Suspended sediment concentration (SSC) along channels is usually reproduced by suspended sediment rating curves, which relate SSC to discharge with a power law equation. Large uncertainty characterizes rating curves based only on discharge, because sediment supply is not explicitly accounted for. The aim of this work is to develop a source-oriented formulation of suspended sediment dynamics and to estimate suspended sediment yield at the outlet of a large Alpine catchment (upper Rhône basin, Switzerland). We propose a novel modelling approach for suspended sediment which accounts for sediment supply by taking into account the variety of sediment sources in an Alpine environment, i.e. the spatial location of sediment sources (e.g. distance from the outlet and lithology) and the different processes of sediment production and transport (e.g. by rainfall, overland flow, snowmelt). Four main sediment sources, typical of Alpine environments, are included in our model: glacial erosion, hillslope erosion, channel erosion and erosion by mass wasting processes. The predictive model is based on gridded datasets of precipitation and air temperature which drive spatially distributed degree-day models to simulate snowmelt and ice-melt, and determine erosive rainfall. A mass balance at the grid scale determines daily runoff. Each cell belongs to a different sediment source (e.g. hillslope, channel, glacier cell). The amount of sediment entrained and transported in suspension is simulated through non-linear functions of runoff, specific for sediment production and transport processes occurring at the grid scale (e.g. rainfall erosion, snowmelt-driven overland flow). Erodibility factors identify different lithological units

  12. Significance of antifouling paint flakes to the distribution of dichlorodiphenyltrichloroethanes (DDTs) in estuarine sediment

    International Nuclear Information System (INIS)

    Wu, Chen-Chou; Bao, Lian-Jun; Tao, Shu; Zeng, Eddy Y.

    2016-01-01

    Recently published literature indicated that dichlorodiphenyltrichloroethane (DDT)-containing antifouling paint flakes were heterogeneously distributed within estuarine sediments. However, the significance of antifouling paint flakes in the fate and transport of DDT compounds and other organic pollutants in estuarine sediment is yet to be adequately addressed. To fill this knowledge gap, estuarine sediment and paint flakes from cabin and boat surfaces were collected from a fishery base in Guangdong Province of South China and analyzed for DDT compounds. Coarse fractioned samples collected from the vicinity of boat maintenance facilities contained appreciable amounts of colorful particles, which were identified as paint flakes by Fourier transform infrared spectroscopy. The highest concentrations of DDXs (sum of DDTs and its metabolites) occurred in the heavy-density (>1.7 g cm"−"3) fraction of coarse-size (200–2000 μm) sediments from near the boat maintenance facilities, suggesting the importance of paint flakes in the distribution pattern of “hot spots” in estuarine sediment. Moreover, the desorption rates of DDT compounds from paint flakes and the heavy-density fraction of coarse-size sediment were both extremely slow. Apparently, unevenly distributed paint flakes in sediment can artificially inflate the sorption capacity of heavy-density sediment for DDT compounds, and therefore can substantially change the environmental fate and behavior of hydrophobic organic chemicals in estuarine sediment. Finally, commonly used source diagnostic indices of DDT compounds were mostly grain-size and density dependent in sediment, as a result of the occurrence of paint flakes, which may strongly compromise the outcome of any source diagnostics efforts. - Highlights: • Concentrations of DDTs were elevated in coarse and high-density fractions. • The desorption rates of DDTs from coarse and high-density fraction were extreme slow. • DDTs-containing antifouling

  13. Calculated distribution of radionuclides in soils and sediments

    International Nuclear Information System (INIS)

    Puigdomenech, I.; Bergstroem, U.

    1994-12-01

    The description of the accumulation of radionuclides in some biospheric compartments is in general based on a sorption distribution coefficient K d . This value is very decisive for the concentration of long-lived radionuclides in reservoirs that are important from the dose point of view. Sorption is due to several processes such as ion-exchange and a variety of physical and chemical interactions which are difficult to interpret with the current K d -methodology. In addition, many of the K d values are obtained from laboratory or geospheric conditions not comparable to conditions prevailing in the biosphere. The main objective with this work is to deepen the knowledge about the theoretical background of K d -values. To achieve this purpose, available theoretical models for ion-exchange and surface complexation have been adapted for simulation under biospheric conditions. The elements treated are cesium, radium, neptunium, uranium and plutonium The results show that a triple layer surface complexation model may be used in estimating K d -values for actinides as a function of important chemical parameters such as pH and E H . It is concluded that by estimating some equilibrium constants and making some careful approximations, surface complexation models can be used for performance assessment of radioactive waste repositories. 72 refs, 7 figs

  14. Delaware Bay, Delaware Sediment Distribution 2003 to 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The area of coverage consists of 38 square miles of benthic habitat mapped from 2003 to 2004 along the middle to lower Delaware Bay Coast. The bottom sediment map...

  15. Geographic information system-coupling sediment delivery distributed modeling based on observed data.

    Science.gov (United States)

    Lee, S E; Kang, S H

    2014-01-01

    Spatially distributed sediment delivery (SEDD) models are of great interest in estimating the expected effect of changes on soil erosion and sediment yield. However, they can only be applied if the model can be calibrated using observed data. This paper presents a geographic information system (GIS)-based method to calculate the sediment discharge from basins to coastal areas. For this, an SEDD model, with a sediment rating curve method based on observed data, is proposed and validated. The model proposed here has been developed using the combined application of the revised universal soil loss equation (RUSLE) and a spatially distributed sediment delivery ratio, within Model Builder of ArcGIS's software. The model focuses on spatial variability and is useful for estimating the spatial patterns of soil loss and sediment discharge. The model consists of two modules, a soil erosion prediction component and a sediment delivery model. The integrated approach allows for relatively practical and cost-effective estimation of spatially distributed soil erosion and sediment delivery, for gauged or ungauged basins. This paper provides the first attempt at estimating sediment delivery ratio based on observed data in the monsoon region of Korea.

  16. Vertical distribution of (241)Pu in the southern Baltic Sea sediments.

    Science.gov (United States)

    Strumińska-Parulska, Dagmara I

    2014-12-15

    The vertical distribution of plutonium (241)Pu in marine sediments can assist in determining the deposition history and sedimentation process of analyzed regions. In addition, (241)Pu/(239+240)Pu activity ratio could be used as a sensitive fingerprint for radioactive source identification. The present preliminary studies on vertical distribution of (241)Pu in sediments from four regions of the southern Baltic Sea are presented. The distribution of (241)Pu was not uniform and depended on sediment geomorphology and depth as well as location. The highest concentrations of plutonium were found in the surface layers of all analyzed sediments and originated from the Chernobyl accident. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Transport coefficients and orientational distributions of dilute colloidal dispersions composed of hematite particles (for an external magnetic field parallel to the angular velocity vector of simple shear flow)

    International Nuclear Information System (INIS)

    Satoh, Akira; Hayasaka, Ryo; Majima, Tamotsu

    2008-01-01

    We have treated a dilute dispersion composed of ferromagnetic rodlike particles with a magnetic moment normal to the particle axis, such as hematites, to investigate the influences of the magnetic field strength, shear rate, and random forces on the orientational distribution of rodlike particles and also on transport coefficients, such as viscosity and diffusion coefficient. In the present analysis, these rodlike particles are assumed to conduct the rotational Brownian motion in a simple shear flow as well as an external magnetic field. The results obtained here are summarized as follows. In the case of a strong magnetic field and a smaller shear rate, the rodlike particle can freely rotate in the xy-plane with the magnetic moment continuing to point the magnetic field direction. On the other hand, for a strong shear flow, the particle has a tendency to incline in the flow direction with the magnetic moment pointing to the magnetic field direction. In the case of the magnetic field applied normal to the direction of the sedimentation, the diffusion coefficient gives rise to smaller values than expected, since the rodlike particle sediments with the particle axis inclining toward directions normal to the movement direction and, of course, toward the direction along that direction

  18. Temporal distribution of sediment yield from catchments covered by different pine plantation areas

    Directory of Open Access Journals (Sweden)

    Tyas Mutiara Basuki

    2018-04-01

    Full Text Available Soil erosion and sedimentation are environmental problems faced by tropical countries. Many researches on soil erosion-sedimentation have been conducted with various results. Quantifying soil erosion-sedimentation and its temporal distribution are important for watershed management. Therefore, a study with the objective to quantify the amount of suspended sediment from catchments under various pine plantation areas was conducted. The research was undertaken during 2010 to 2017 in seven catchments with various percentage of pine coverage in Kebumen Regency, Central Java Province. The rainfall data were collected from two rainfall stations. A tide gauge was installed at the outlet of each catchment to monitor stream water level. The water samples for every stream water level increment were analyzed to obtain sediment concentration. The results showed that monthly suspended sediment of the catchments was high in January to April and October to December, and low in May to September. The annual suspended sediment fluctuated during the study period. Non-linear correlations were observed between suspended sediment and rainfall as well as suspended sediment and percentage pine areas. The line trend between suspended sediment and percentage of pine areas showed that the increase in pine areas decreased suspended sediment, with the slope of the graph is sharp at the percentage of pine areas from 8% to 40%, then is gentle for pine plantation areas more than 40%.

  19. Particle size distribution of main-channel-bed sediments along the upper Mississippi River, USA

    Science.gov (United States)

    Remo, Jonathan; Heine, Ruben A.; Ickes, Brian

    2016-01-01

    In this study, we compared pre-lock-and-dam (ca. 1925) with a modern longitudinal survey of main-channel-bed sediments along a 740-km segment of the upper Mississippi River (UMR) between Davenport, IA, and Cairo, IL. This comparison was undertaken to gain a better understanding of how bed sediments are distributed longitudinally and to assess change since the completion of the UMR lock and dam navigation system and Missouri River dams (i.e., mid-twentieth century). The comparison of the historic and modern longitudinal bed sediment surveys showed similar bed sediment sizes and distributions along the study segment with the majority (> 90%) of bed sediment samples having a median diameter (D50) of fine to coarse sand. The fine tail (≤ D10) of the sediment size distributions was very fine to medium sand, and the coarse tail (≥ D90) of sediment-size distribution was coarse sand to gravel. Coarsest sediments in both surveys were found within or immediately downstream of bedrock-floored reaches. Statistical analysis revealed that the particle-size distributions between the survey samples were statistically identical, suggesting no overall difference in main-channel-bed sediment-size distribution between 1925 and present. This was a surprising result given the magnitude of river engineering undertaken along the study segment over the past ~ 90 years. The absence of substantial differences in main-channel-bed-sediment size suggests that flow competencies within the highly engineered navigation channel today are similar to conditions within the less-engineered historic channel.

  20. The distribution and partitioning of common antibiotics in water and sediment of the Pearl River Estuary, South China.

    Science.gov (United States)

    Liang, Ximei; Chen, Baowei; Nie, Xiangping; Shi, Zhen; Huang, Xiaoping; Li, Xiangdong

    2013-09-01

    Antibiotics released into the aquatic environment play an important role in the spread of antibiotic resistance. In the Pearl River Estuary (PRE) and the coastal zone, the concentrations of antibiotics decreased from the Pearl River to the estuary, suggesting that antibiotics primarily originated from river tributaries and terrigenous sources. Within the PRE area, the concentrations of antibiotics in water were higher in the west coast than the east side, reflecting the high density of anthropogenic activities and hydraulic conditions along the west riverbank. Seasonal variations were also observed for most of detected antibiotics in water. The pseudo-partitioning coefficient of norfloxacin had a good correlation with the TOC content of sediments, as did erythromycin-H2O with the pH of water. The results suggest that environmental conditions can significantly affect the distribution of antibiotics between water and sediment. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Impacts of Hydrate Distribution on the Hydro-Thermo-Mechanical Properties of Hydrate-Bearing Sediments

    Science.gov (United States)

    Dai, S.; Seol, Y.

    2015-12-01

    In general, hydrate makes the sediments hydraulically less conductive, thermally more conductive, and mechanically stronger; yet the dependency of these physical properties on hydrate saturation varies with hydrate distribution and morphology. Hydrate distribution in sediments may cause the bulk physical properties of their host sediments varying several orders of magnitude even with the same amount of hydrate. In natural sediments, hydrate morphology is inherently governed by the burial depth and the grain size of the host sediments. Compare with patchy hydrate, uniformly distributed hydrate is more destructive to fluid flow, yet leads to higher gas and water permeability during hydrate dissociation due to the easiness of forming percolation paths. Water and hydrate have similar thermal conductivity values; the bulk thermal conductivity of hydrate-bearing sediments depends critically on gas-phase saturation. 60% of gas saturation may result in evident thermal conductivity drop and hinder further gas production. Sediments with patchy hydrate yield lower stiffness than that with cementing hydrate but higher stiffness than that with pore filling and loading bearing hydrate. Besides hydrate distribution, the stress state and loading history also play an important role in the mechanical behavior of hydrate-bearing sediments.

  2. Mineral assemblages and their distribution patterns in the sediments of the Gulf of Bohai Sea

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L; Luan, Z; Zheng, T; Xu, W; Dong, T

    1980-01-01

    This paper presents the results of a study on the mineral assemblages and their distribution patterns in the sediments of the Gulf of Bohai Sea. The 212 bottom-surface sediment samples were collected from the Gulf of Bohai Sea and its tributaries.

  3. A Random Forest Approach to Predict the Spatial Distribution of Sediment Pollution in an Estuarine System

    Science.gov (United States)

    Modeling the magnitude and distribution of sediment-bound pollutants in estuaries is often limited by incomplete knowledge of the site and inadequate sample density. To address these modeling limitations, a decision-support tool framework was conceived that predicts sediment cont...

  4. Influence of Sewer Sediments on Flow Friction and Shear Stress Distribution

    DEFF Research Database (Denmark)

    Perrusquia, G.; Petersen, O.; Larsen, Torben

    1995-01-01

    Most sewers contain more or less deposited sediments. The paper discusses the distribution of the boundary shear stresses and the hydraulic resistance in part-full sewer pipes with such deposited sediments. The discussion is based on a series of numerical experiments using a validated numerical...

  5. Sediment-water distribution of contaminants of emerging concern in a mixed use watershed

    Science.gov (United States)

    This study evaluated the occurrence and distribution of 15 contaminants of emerging concern (CEC) in stream water and sediments in the Zumbro River watershed in Minnesota and compared these with sub-watershed land uses. Sixty pairs of sediment and water samples were collected across all seasons from...

  6. Influence of break structures on the distribution of radionuclides in bottom sediments of the Kyiv reservoir

    International Nuclear Information System (INIS)

    Shestopalov, V.M.; Lyal'ko, V.I.; Fedorovskij, A.D.; Sirenko, L.A.; Khodorovskij, A.Ya.

    2000-01-01

    We study the distribution of radionuclides in bottom sediments of the Kyiv reservoir on the basis of research of adjacent territory break - block structures with deciphering space-born images and ground measurements and forecast the occurrence of extreme situations due to the redistribution of bottom water flows and sediments of radionuclides

  7. Process-based distributed modeling approach for analysis of sediment dynamics in a river basin

    Directory of Open Access Journals (Sweden)

    M. A. Kabir

    2011-04-01

    Full Text Available Modeling of sediment dynamics for developing best management practices of reducing soil erosion and of sediment control has become essential for sustainable management of watersheds. Precise estimation of sediment dynamics is very important since soils are a major component of enormous environmental processes and sediment transport controls lake and river pollution extensively. Different hydrological processes govern sediment dynamics in a river basin, which are highly variable in spatial and temporal scales. This paper presents a process-based distributed modeling approach for analysis of sediment dynamics at river basin scale by integrating sediment processes (soil erosion, sediment transport and deposition with an existing process-based distributed hydrological model. In this modeling approach, the watershed is divided into an array of homogeneous grids to capture the catchment spatial heterogeneity. Hillslope and river sediment dynamic processes have been modeled separately and linked to each other consistently. Water flow and sediment transport at different land grids and river nodes are modeled using one dimensional kinematic wave approximation of Saint-Venant equations. The mechanics of sediment dynamics are integrated into the model using representative physical equations after a comprehensive review. The model has been tested on river basins in two different hydro climatic areas, the Abukuma River Basin, Japan and Latrobe River Basin, Australia. Sediment transport and deposition are modeled using Govers transport capacity equation. All spatial datasets, such as, Digital Elevation Model (DEM, land use and soil classification data, etc., have been prepared using raster "Geographic Information System (GIS" tools. The results of relevant statistical checks (Nash-Sutcliffe efficiency and R–squared value indicate that the model simulates basin hydrology and its associated sediment dynamics reasonably well. This paper presents the

  8. Distribution coefficients for radionuclides in aquatic environments. Volume 2. Dialysis experiments in marine environments

    International Nuclear Information System (INIS)

    Sibley, T.H.; Nevissi, A.E.; Schell, W.R.

    1981-05-01

    The overall objective of this research program was to obtain new information that can be used to predict the fate of radionuclides that may enter the aquatic environment from nuclear power plants, waste storage facilities or fuel reprocessing plants. Important parameters for determining fate are the distribution of radionuclides between the soluble and particulate phases and the partitioning of radionuclides among various suspended particulates. This report presents the results of dialysis experiments that were used to study the distribution of radionuclides among suspended sediments, phytoplankton, organic detritus, and filtered sea water. Three experiments were conducted to investigate the adsorption kinetics and equilibrium distribution of (59)Fe, (60)Co, (65)Zn, (106)Ru, (137)Cs, (207)Bi, (238)Pu, and (241)Am in marine system. Diffusion across the dialysis membranes depends upon the physico-chemical form of the radionuclides, proceeding quite rapidly for ionic species of (137)Cs and (60)Co but much more slowly for radionuclides which occur primarily as colloids and solid precipitates such as (59)Fe, (207)Bi, and (241)Am. All the radionuclides adsorb to suspended particulates although the amount of adsorption depends upon the specific types and concentration of particulates in the system and the selected radionuclide. High affinity of some radionuclides - e.g., (106)Ru and (241)Am - for detritus and phytoplankton suggests that suspended organics may significantly affect the eventual fate of those radionuclides in marine ecosystems

  9. STUDY OF REFLECTION COEFFICIENT DISTRIBUTION FOR ANTI-REFLECTION COATINGS ON SMALL-RADIUS OPTICAL PARTS

    Directory of Open Access Journals (Sweden)

    L. A. Gubanova

    2015-03-01

    Full Text Available The paper deals with findings for the energy reflection coefficient distribution of anti- reflection coating along the surface of optical elements with a very small radius (2-12 mm. The factors influencing the magnitude of the surface area of the optical element, in which the energy reflection coefficient is constant, were detected. The main principles for theoretical models that describe the spectral characteristics of the multilayer interference coatings were used to achieve these objectives. The relative size of the enlightenment area is defined as the ratio of the radius for the optical element surface, where the reflection is less than a certain value, to its radius (ρ/r. The result of research is the following: this size is constant for a different value of the curvature radius for the optical element made of the same material. Its value is determined by the refractive index of material (nm, from which the optical element was made, and the design of antireflection coatings. For single-layer coatings this value is ρ/r = 0.5 when nm = 1.51; and ρ/r = 0.73 when nm = 1.75; for two-layer coatings ρ/r = 0.35 when nm = 1.51 and ρ/r = 0.41 when nm = 1.75. It is shown that with increasing of the material refractive index for the substrate size, the area of minimum reflection coefficient is increased. The paper considers a single-layer, two-layer, three-layer and five-layer structures of antireflection coatings. The findings give the possibility to conclude that equal thickness coverings formed on the optical element surface with a small radius make no equal reflection from the entire surface, and distribution of the layer thickness needs to be looked for, providing a uniform radiation reflection at all points of the spherical surface.

  10. Evaluation of distribution coefficients for the prediction of strontium and cesium migration in a uniform sand

    International Nuclear Information System (INIS)

    Reynolds, W.D.; Gillham, R.W.; Cherry, J.A.

    1982-01-01

    The validity of using a distribution coefficient (Ksub(d)) in the mathematical prediction of strontium and cesium transport through uniform saturated sand was investigated by comparing measured breakthrough curves with curves of simulations using the advection-dispersion and the advection equations. Values for Ksub(d) were determined by batch equilibration tests and, indirectly, by fitting the mathematical model to breakthrough data from column experiments. Although the advection-dispersion equation accurately represented the breakthrough curves for two nonreactive solutes (chloride and tritium), neither it nor the advection equation provided close representations of the strontium and cesium curves. The simulated breakthrough curves for strontium and cesium were nearly symmetrical, whereas the data curves were very asymmetrical, with long tails. Column experiments with different pore-water velocities indicated that the shape of the normalized breakthrough curves was not sensitive to velocity. This suggests that the asymmetry of the measured curves was the result of nonlinear partitioning of the cations between the solid and liquid phases, rather than nonequilibrium effects. The results indicate that the distribution coefficient, when used in advection-dispersion models for prediction of the migration of strontium and cesium in field situations, can result in significant error

  11. Spatial distribution of coefficients for determination of global radiation in Serbia

    Directory of Open Access Journals (Sweden)

    Nikolić Jugoslav L.

    2012-01-01

    Full Text Available The aim of this paper is a creation of the spatial distribution of the corresponding coefficients for the indirect determination of global radiation using all direct measurements data of this shortwave radiation balance component in Serbia in the standard climate period (1961-1990. Based on the global radiation direct measurements data recorded in the past and routine measurements/observations of cloudiness and sunshine duration, the spatial distribution coefficients maps required for calculation of global radiation were produced on the basis of sunshine/cloudiness in an arbitrary point on the territory of Serbia. Besides, a specific verification of the proposed empirical formula was performed. This paper contributes to a wide range of practical applications as direct measurements of global radiation are relatively rare, and are not carried out in Serbia today. Significant application is possible in the domain of renewable energy sources. The development of method for determination of the global radiation has an importance from the aspect of the environmental protection; however it also has an economic importance through applications in numerous commercial projects, as it does not require special measurements or additional financial investments.

  12. Estimation of distribution coefficient for uranium in soil around a waste disposal site at Trombay

    International Nuclear Information System (INIS)

    Mishra, S.; Chaudhary, D.K.; Sandeep, P.; Pandit, G.G.

    2014-01-01

    Soil contamination arising from the disposed waste from industrial origin is of major concern now a days. There is a possibility of run off as well as Ieaching of contaminants from the sites to nearby aquatic bodies through rain water. Distribution coefficient, K d in soil is an important parameter to predict the migration of contaminants. However it requires precise measurement not only for the accurate prediction of contaminant transport but also for describing the sorption behavior in a particular environment. The variation of K d values for a radionuclide is due to differences in geochemical conditions, soil materials, nature of water and methods used for the measurements. For the present study soil samples have been collected near a waste disposal site at Trombay and the sorption of uranium has been studied by measuring the distribution coefficient (K d ) by laboratory batch method. In our earlier studies, we could notice substantial effect of ionic composition of ground water on the K d values of uranium. In this study we have used rain water as the sorption media and the measured K d value s were compared with previous values for different soil and water characteristics from different regions of India

  13. Lithology and surficial sediment distribution: northern Hatteras Abyssal Plain

    International Nuclear Information System (INIS)

    Dickson, S.M.; Laine, E.P.; Friedrich, N.E.

    1985-01-01

    Surficial sediments of the LLWODP study area E-N3 have several common characteristics and a few anomalous features. All of the 26 surficial samples examined are Holocene in age. In E-N3, the Holocene sequence ranges from 12-90 cm. The sequence is composed primarily of brown foraminiferal lutite. The lutites show evidence of burrowing by benthic animals in the form of burrows infilled with sediment of a different color. Below the bioturbated lutites is a dark brown, iron-enriched horizon stratigraphically near (within a few centimeters of) the Pleistocene/Holocene boundary. The vertical extent of this unit, which ranges from 2-22 cm, varies systematically within the study area. The maximum thickness is found in a region most removed from the terrigenous sediment entry points. Fine-grained turbidity currents, an abyssal current, and a debris flow created the uncommon features of the surficial sediments. The areal extent of these deposits is estimated as 10% of the E-N3 region below 5300 m. The largest turbidite is probably greater than 2000 km 2 in extent. However, evidence of coarse-grained turbidity current activity in the Holocene is absent. Hemipelagic deposition during the Holocene has resulted in a texturally uniform sequence of surficial sediments. 22 references, 10 figures, 6 tables

  14. Sediment-hosted contaminants and distribution patterns in the Mississippi and Atchafalaya River Deltas

    Science.gov (United States)

    Flocks, James G.; Kindinger, Jack G.; Ferina, Nicholas; Dreher, Chandra

    2002-01-01

    The Mississippi and Atchafalaya Rivers transport very large amounts of bedload and suspended sediments to the deltaic and coastal environments of the northern Gulf of Mexico. Absorbed onto these sediments are contaminants that may be detrimental to the environment. To adequately assess the impact of these contaminants it is first necessary to develop an understanding of sediment distribution patterns in these deltaic systems. The distribution patterns are defined by deltaic progradational cycles. Once these patterns are identified, the natural and industrial contaminant inventories and their depositional histories can be reconstructed. Delta progradation is a function of sediment discharge, as well as channel and receiving-basin dimensions. Fluvial energy controls the sediment distribution pattern, resulting in a coarse grained or sandy framework, infilled with finer grained material occupying the overbank, interdistributary bays, wetlands and abandoned channels. It has been shown that these fine-grained sediments can carry contaminants through absorption and intern them in the sediment column or redistribute them depending on progradation or degradation of the delta deposit. Sediment distribution patterns in delta complexes can be determined through high-resolution geophysical surveys and groundtruthed with direct sampling. In the Atchafalaya and Mississippi deltas, remote sensing using High-Resolution Single-Channel Seismic Profiling (HRSP) and Sidescan Sonar was correlated to 20-ft vibracores to develop a near-surface geologic framework that identifies variability in recent sediment distribution patterns. The surveys identified bedload sand waves, abandoned-channel back-fill, prodelta and distributary mouth bars within the most recently active portions of the deltas. These depositional features respond to changes in deltaic processes and through their response may intern or transport absorbed contaminants. Characterizing these features provides insight into the

  15. Distribution of some biochemical compounds in the sediments of the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Dhople, V.M.

    Surficial sediment samples collected from the continental shelf and slope of the Bay of Bengal were studied for the distribution of organic carbon and its constituent fractions such as carbohydrates, proteins, amino acids and lipids. Organic carbon...

  16. Distribution of total phosphorus in the shelf sediments off the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, P.S.N.; Reddy, C.V.G.; Varadachari, V.V.R.

    The total phosphorus content in the sediment samples collected from different stations on the continental shelf along five sections normal to the coast near Bombay, Karwar, Mangalore, Cochin and Alleppey has been determined and the distribution...

  17. Distribution of phosphorus in the marine sediments off the east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, P.S.N.; Reddy, C.V.G.

    Sediment samples collected from the shelf and slope regions off the East Coast of India between "Swatch of no ground" in the north and Karaikal in the south, have been analysed for their total phosphorus content and its distribution studied...

  18. Sediment spatial distribution evaluated by three methods and its relation to some soil properties

    Energy Technology Data Exchange (ETDEWEB)

    Bacchi, O O.S. . [Centro de Energia Nuclear na Agricultura-CENA/USP, Laboratorio de Fisica do Solo, Piracicaba, SP (Brazil); Reichardt, K [Centro de Energia Nuclear na Agricultura-CENA/USP, Laboratorio de Fisica do Solo, Piracicaba, SP (Brazil); Departamento de Ciencias Exatas, Escola Superior de Agricultura ' Luiz de Queiroz' ESALQ/USP, Piracicaba, SP (Brazil); Sparovek, G [Departamento de Solos e Nutricao de Plantas, Escola Superior de Agricultura ' Luiz de Queiroz' ESALQ/USP, Piracicaba, SP (Brazil)

    2003-02-15

    An investigation of rates and spatial distribution of sediments on an agricultural field cultivated with sugarcane was undertaken using the {sup 137}Cs technique, USLE and WEPP models. The study was carried out on the Ceveiro watershed of the Piracicaba river basin, state of Sao Paulo, Brazil, experiencing severe soil degradation due to soil erosion. The objectives of the study were to compare the spatial distribution of sediments evaluated by the three methods and its relation to some soil properties. Erosion and sedimentation rates and their spatial distribution estimated by the three methods were completely different. Although not able to show sediment deposition, the spatial distribution of erosion rates evaluated by USLE presented the best correlation with other studied soil properties. (author)

  19. [Effects of Fulvic Acid on Absorption and Form Distribution of Heavy Metals on Sediments].

    Science.gov (United States)

    Li, Yu-qing; He, Jiang; Lü, Chang-wei; Fan, Ming-de; Wang, Wei; Zhang, Rui-qing; Xie, Zhi- lei; Wang, Jing-hua; Yu, Bo; En, He; Ding, Tao

    2016-03-15

    Based on the extracted fulvic acid (FA) from Lake Wuliangsuhai sediments by sequential alkali extraction, this work studied the effects of FA on the adsorption and fraction distribution of heavy metals (HM) on sediments using original sediments and sediments treated with 30% H₂O₂ as adsorbents. The results showed both organic matter and FA had effects on the HM adsorption onto sediments; The treatments of FA-free conditions and the sediments treated by H₂O₂ showed relatively strong influence on Cu²⁺ adsorption, which decreased the Cu²⁺ adsorption by 17.85%. With the increasing FA addition, the adsorption percentage of HM on both types of sediments showed gradually decreasing trends, with the order of Cu²⁺ > Cd²⁺ > Zn²⁺ > Pb²⁺; when the FA content was more than 5% , FA became the governing factor on the decreasing adsorption percentage of HM. With increasing FA addition, forms distribution of HM showed significant changes in both types of sediments; i. e. FA additions showed significant negative and positive correlations with percentages of metals bound to carbonates and organic matter, respectively, since the FA addition increased the H⁺ concentration of the system, in which H⁺ could activate the metals bound to carbonate from the sediments. As an organophilic weak element, the fraction percentage of Cd bound to organic matter was the lowest with the minimal changes.

  20. Lead distribution in coastal and estuarine sediments around India

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, S.; Chakraborty, P.; Nath, B.N.

    . Trace element geochemical associations in the Arabian Gulf. Mar. Pollut. Bull. 17, 353–356. doi:10.1016/0025-326X(86)90247-X Achyuthan, H., Richardmohan, D., Srinivasalu, S., 2002a. Trace metals concentrations in the sediment cores of estuary... in the coastal sediment of chennai coast. IIOAB J. 3, 12–18. Ray, A.K., Tripathy, S.C., Patra, S., Sarma, V. V, 2006. Assessment of Godavari estuarine mangrove ecosystem through trace metal studies. Environ. Int. 32, 219–223. Reddy, M.S., Basha, S., Sravan...

  1. Temporal and spatial distribution of beryllium-7 in the sediments of Chesapeake Bay

    International Nuclear Information System (INIS)

    Dibb, J.E.; Rice, D.L.

    1989-01-01

    The sediment inventory of 7 Be was determined at six stations in the main stem of Chesapeake Bay nine times between April, 1986, and September, 1987. The inventories ranged from -2 . Comparison to the atmospherically supported 7 Be inventory (range 2-4 dpm cm -2 ) showed significant focusing of 7 Be in the sediments in the zone of the turbidity maximum during the summer, and suggested that the spatial distribution of 7 Be in the lower Bay apparently had a recurrence frequency greater than the sampling frequency in this investigation. The temporal pattern of 7 Be accumulation at the six stations over the first year of this investigation allowed estimation of sedimentation rates, which suggested that the processes governing the distribution of 7 Be in Chesapeake Bay sediments were similar to the processes determining sedimentation patterns over about the past 100 years. (author)

  2. Critical electrode size in measurement of d33 coefficient of films via spatial distribution of piezoelectric displacement

    International Nuclear Information System (INIS)

    Wang Zhihong; Miao Jianmin

    2008-01-01

    Spatial distributions of piezoelectric displacement response across the top electrode have been used in this paper to measure the piezoelectric coefficient d 33 of films based on the converse piezoelectric effect. The technical details and features of a scanning laser Doppler vibrometer have been summarized and discussed for accurately obtaining the spatial displacement distributions. Three definitions, including the apparent, the effective and the constrained piezoelectric coefficient d 33 of films, have been clarified and used to better understand the fundamental phenomenon behind the measured displacement distributions. Finite element analysis reveals that both the apparent and the effective piezoelectric coefficients depend on the electrode radius of test capacitor as well as film thickness. However, there exists a critical electrode size for apparent piezoelectric coefficients and a critical test capacitor aspect ratio for effective piezoelectric coefficient. Beyond their respective critical values, both coefficients converge to the constrained piezoelectric coefficient irrespective of film thickness. The finding of the critical electric size makes it possible to consistently measure the constrained piezoelectric coefficient of films by using the spatial distributions of the piezoelectric displacement response and becomes the fundamental criterion of this measurement method

  3. Estimation of uranium and cobalt-60 distribution coefficients and uranium-235 enrichment at the Combustion Engineering Company site in Windsor, Connecticut

    International Nuclear Information System (INIS)

    Wang, Y.; Orlandini, K.A.; Yu, C.

    1996-05-01

    Site-specific distribution coefficients for uranium isotopes and cobalt-60 (Co-60) and the fraction of uranium-235 (U-235) enrichment by mass were estimated for environmental samples collected from the Combustion Engineering Company site in Windsor, CT. This site has been identified for remedial action under the US Department of Energy's (DOE) Formerly Utilized Sites Remedial Action Program. The authority of DOE at the Combustion Engineering site is limited to (1) Building 3; (2) other activities or areas associated exclusively with Building 3 (such as sewer lines); or (3) contamination that is exclusively highly enriched uranium. In this study, 16 samples were collected from the Combustion Engineering site, including 8 soil, 4 sediment, 3 water, and 1 water plus sludge sample. These samples were analyzed for isotopic uranium by alpha spectrometry and for Co-60 by gamma spectrometry. The site-specific distribution coefficient for each isotope was estimated as the ratio of extractable radionuclide activity in the solid phase to the activity in the contact solution following a 19-day equilibration. The uranium activity measurements indicate that uranium-234 (U-234) and uranium-238 (U-238) were in secular equilibrium in two soil samples and that soil and sediment samples collected from other sampling locations had higher U-234 activity than U-238 activity in both the solid and solution phases. The site-specific distribution coefficient (Kd) ranged from 82 to 44,600 mL/g for U-238 and from 102 to 65,900 mL/g for U-234. Calculation of U-235 enrichment by mass indicated that four soil samples had values greater than 0.20; these values were 0.37, 0.38, 0.46, and 0.68. Cobalt-60 activity was detected in only three sediment samples. The measured Co-60 activity in the solid phase ranged from 0.15 to 0.45 pCi/g and that in the water phase of all three samples combined was 4 pCi/L. The Kd value for Co-60 in the site brook sediment was calculated to be 70 mL/g

  4. Temporal and spatial distributions of sediment total organic carbon in an estuary river.

    Science.gov (United States)

    Ouyang, Y; Zhang, J E; Ou, L-T

    2006-01-01

    Understanding temporal and spatial distributions of naturally occurring total organic carbon (TOC) in sediments is critical because TOC is an important feature of surface water quality. This study investigated temporal and spatial distributions of sediment TOC and its relationships to sediment contaminants in the Cedar and Ortega Rivers, Florida, USA, using three-dimensional kriging analysis and field measurement. Analysis of field data showed that large temporal changes in sediment TOC concentrations occurred in the rivers, which reflected changes in the characteristics and magnitude of inputs into the rivers during approximately the last 100 yr. The average concentration of TOC in sediments from the Cedar and Ortega Rivers was 12.7% with a maximum of 22.6% and a minimum of 2.3%. In general, more TOC accumulated at the upper 1.0 m of the sediment in the southern part of the Ortega River although the TOC sedimentation varied with locations and depths. In contrast, high concentrations of sediment contaminants, that is, total polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), were found in sediments from the Cedar River. There was no correlation between TOC and PAHs or PCBs in these river sediments. This finding is in contradiction to some other studies which reported that the sorption of hydrocarbons is highly related to the organic matter content of sediments. This discrepancy occurred because of the differences in TOC and hydrocarbon source input locations. It was found that more TOC loaded into the southern part of the Ortega River, while almost all of the hydrocarbons entered into the Cedar River. This study suggested that the locations of their input sources as well as the land use patterns should also be considered when relating hydrocarbons to sediment TOC.

  5. Sources, distribution, and mobility of plutonium and radiocesium in soils, sediments and water of the Hudson River Estuary and watershed

    International Nuclear Information System (INIS)

    Linsalata, P.

    1984-01-01

    Results of 239 240 Pu, 238 Pu and 137 Cs measurements are reported for soil cores sampled within the watershed, for many sediment cores and surface dredge samples taken along the length of the Hudson River Estuary and for water samples collected on a continuous basis in both fresh and estuarine reaches. Accumulations of 239 240 Pu and 137 Cs measured within sediment cores taken from discrete regions of the river-estuary were summed to arrive at total sediment inventories of 1.6 +/- 0.7 Ci and 53 +/- 20 Ci, respectively. The variability observed in the sediment accumulation of radionuclides is discussed in terms of the physical and chemical characteristics of the river-estuary. Plutonium-239,240 and 137 Cs were similary distributed in sediments and water sampled from fresh water reaches of the Hudson with activity ratios (i.e., 239 240 Pu/ 1 2number 7 Cs) ranging from 0.01 to 0.03. Distribution coefficients, which were determined both in vitro and in situ were similar for both nuclides (i.e., from 1 x 10 5 to 3 x 10 5 L.kg -1 ) in fresh water, but diverged significantly (as a result of increased 137 Cs solubility) in brackish waters that exhibited chlorinities in excess of 1-2 g Cl - .L -1 . The concentrations of 239 240 Pu and 137 Cs observed in fresh water samples were primarily functions of the suspended load. Approximately 60-70% of the annual downstream transport of 239 240 Pu and 137 Cs calculated during 1980 and 1981 (i.e., 4 +/- 0.5 mCi and 515 +/- 84 mCi, respectively) was associated with suspended particulates greater than or equal to 0.45 μm. An empirical model was developed to determine the rates of vertical migration of these nuclides in soils of the watershed

  6. Evaluation of an Empirical Reservoir Shape Function to Define Sediment Distributions in Small Reservoirs

    Directory of Open Access Journals (Sweden)

    Bogusław Michalec

    2015-08-01

    Full Text Available Understanding and defining the spatial distribution of sediment deposited in reservoirs is essential not only at the design stage but also during the operation. The majority of research concerns the distribution of sediment deposition in medium and large water reservoirs. Most empirical methods do not provide satisfactory results when applied to the determination of sediment deposition in small reservoirs. Small reservoir’s volumes do not exceed 5 × 106 m3 and their capacity-inflow ratio is less than 10%. Long-term silting measurements of three small reservoirs were used to evaluate the method described by Rahmanian and Banihashemi for predicting sediment distributions in small reservoirs. Rahmanian and Banihashemi stated that their model of distribution of sediment deposition in water reservoir works well for a long duration operation. In the presented study, the silting rate was used in order to determine the long duration operation. Silting rate is a quotient of volume of the sediment deposited in the reservoir and its original volume. It was stated that when the silting rate had reached 50%, the sediment deposition in the reservoir may be described by an empirical reservoir depth shape function (RDSF.

  7. Evolution of the sedimentation technique for particle size distribution analysis

    International Nuclear Information System (INIS)

    Maley, R.

    1998-01-01

    After an introduction on the significance of particle size measurements, sedimentation methods are described, with emphasis on the evolution of the gravitational approach. The gravitational technique based on mass determination by X-ray adsorption allows fast analysis by automation and easy data handling, in addition to providing the accuracy required by quality control and research applications [it

  8. Distribution of radionuclides and elements in Cubatao River sediments

    International Nuclear Information System (INIS)

    Silva, P.S.C.; Mazzilli, B.P.; Favaro, D.I.T.

    2006-01-01

    Cubatao River is located in Santos Basin, Sao Paulo State, Brazil. This region is characterized by the occurrence of estuaries and mangrove. Due to its location, near the coastal line, it is also an important industrial area, where phosphate fertilizer plants, petrol refineries, and chemical and steel industries are present. Such human activities contribute to the enhancement of elemental composition in sediments and, in some cases, also increase the radionuclide concentrations, the so called Technologically Enhanced Natural Occurring Radioactive Materials (TENORM). The contamination of land and sediments by TENORM is of major concern. The activity concentration of U and Th series radionuclides was determined in five sediment samples from Cubatao River. The activity concentration ratio was also determined. Equilibrium was observed for the ratio 234 U/ 238 U. The activity ratios of Th/ 238 U, 228 Ra/ 226 Ra and 210 Pb/ 226 Ra were higher than the unity. In the first two cases, the observed values are due to the higher activity of Th in the sediment and in the last case are probably due to the atmospheric deposition of 210 Pb. (author)

  9. SCS-CN based time-distributed sediment yield model

    Science.gov (United States)

    Tyagi, J. V.; Mishra, S. K.; Singh, Ranvir; Singh, V. P.

    2008-05-01

    SummaryA sediment yield model is developed to estimate the temporal rates of sediment yield from rainfall events on natural watersheds. The model utilizes the SCS-CN based infiltration model for computation of rainfall-excess rate, and the SCS-CN-inspired proportionality concept for computation of sediment-excess. For computation of sedimentographs, the sediment-excess is routed to the watershed outlet using a single linear reservoir technique. Analytical development of the model shows the ratio of the potential maximum erosion (A) to the potential maximum retention (S) of the SCS-CN method is constant for a watershed. The model is calibrated and validated on a number of events using the data of seven watersheds from India and the USA. Representative values of the A/S ratio computed for the watersheds from calibration are used for the validation of the model. The encouraging results of the proposed simple four parameter model exhibit its potential in field application.

  10. Diatom distribution in the surficial sediments of Lake Fuxian, Yunnan ...

    African Journals Online (AJOL)

    ajl yemi

    2011-11-30

    Nov 30, 2011 ... The diatom abundances per gram dry weight sediment vary between 18.4 × 106 and 66.9 × 106 valves (Figure 2). Abundances per gram dry weight of the eight most abundant diatom taxa are shown in Figure 3. The DCA diagram shows centroids of ecoregions in the ordination space of the first axes.

  11. Relation between distribution coefficient of radioactive strontium and solid-liquid distribution ratio of background stable strontium

    International Nuclear Information System (INIS)

    Igarashi, Toshifumi; Mahara, Yasunori; Okamura, Masaki; Ashikawa, Nobuo.

    1992-01-01

    Distribution coefficients (K d ) of nuclides, which are defined as the ratio of the adsorbed concentration to the solution concentration, are important in predicting nuclide migration in the subsurface environment. This study was undertaken to contrust an effective method of determining the most pertinent K d value for simulating in situ distribution phenomena between the solid and liquid phases, by using background stable isotopes. This paper describes the applicability of this method to Sr by carrying out a batch Sr adsorption experiment where stable Sr coexisted with the radioactive isotope, 85 Sr, and by comparing the concentration distribution ratio of the background stable Sr with the K d value obtained by the batch experiment. The results showed that the K d of 85 Sr (K d85 ) agreed well with the K d of the coexisting stable Sr (K ds ) and that the two values decreased with an increase in the concentration of the stable Sr, when sand was used as an adsorbent. In addition, the K d85 corresponded to the ratio of the exchangeable solid-phase concentration of background stable Sr to the concentration of the background stable Sr in groundwater when the concentration of the coexisting stable Sr approached the background level. On the other hand, when powdered rock samples were used, the K d85 did not agree with the K ds , and the concentration distribution ratio of the background stable Sr was greater than the K d85 . This discrepancy might be due to the disequilibrium resulting from grinding the rock matrices. This suggests that measurement of the background stable Sr distribution ratio between the solid and liquid phases can be an effective method of estimating the K d of radioactive Sr when the groundwater is in satisfactory contact with the adsorption medium. (author)

  12. [Assessment of ecosystem in giant panda distribution area based on entropy method and coefficient of variation].

    Science.gov (United States)

    Yan, Zhi Gang; Li, Jun Qing

    2017-12-01

    The areas of the habitat and bamboo forest, and the size of the giant panda wild population have greatly increased, while habitat fragmentation and local population isolation have also intensified in recent years. Accurate evaluation of ecosystem status of the panda in the giant panda distribution area is important for giant panda conservation. The ecosystems of the distribution area and six mountain ranges were subdivided into habitat and population subsystems based on the hie-rarchical system theory. Using the panda distribution area as the study area and the three national surveys as the time node, the evolution laws of ecosystems were studied using the entropy method, coefficient of variation, and correlation analysis. We found that with continuous improvement, some differences existed in the evolution and present situation of the ecosystems of six mountain ranges could be divided into three groups. Ecosystems classified into the same group showed many commonalities, and difference between the groups was considerable. Problems of habitat fragmentation and local population isolation became more serious, resulting in ecosystem degradation. Individuali-zed ecological protection measures should be formulated and implemented in accordance with the conditions in each mountain system to achieve the best results.

  13. Calculation of age-dependent dose conversion coefficients for radionuclides uniformly distributed in air

    International Nuclear Information System (INIS)

    Hung, Tran Van; Satoh, Daiki; Takahashi, Fumiaki; Tsuda, Shuichi; Endo, Akira; Saito, Kimiaki; Yamaguchi, Yasuhiro

    2005-02-01

    Age-dependent dose conversion coefficients for external exposure to photons emitted by radionuclides uniformly distributed in air were calculated. The size of the source region in the calculation was assumed to be effectively semi-infinite in extent. Firstly, organ doses were calculated with a series of age-specific MIRD-5 type phantoms using MCNP code, a Monte Carlo transport code. The calculations were performed for mono-energetic photon sources of twelve energies from 10 keV to 5 MeV and for phantoms of newborn, 1, 5, 10 and 15 years, and adult. Then, the effective doses to the different age-phantoms from the mono-energetic photon sources were estimated based on the obtained organ doses. The calculated effective doses were used to interpolate the conversion coefficients of the effective doses for 160 radionuclides, which are important for dose assessment of nuclear facilities. In the calculation, energies and intensities of emitted photons from radionuclides were taken from DECDC, a recent compilation of decay data for radiation dosimetry developed at JAERI. The results are tabulated in the form of effective dose per unit concentration and time (Sv per Bq s m -3 ). (author)

  14. Distribution coefficients for chemical components of a coal-oil/water system

    Energy Technology Data Exchange (ETDEWEB)

    Picel, K C; Stamoudis, V C; Simmons, M S

    1988-09-01

    Distribution coefficients (K/sub D/) were measured by equilibrating a coal oil comparative reference material (CRM-1) with water and then separating the oil and water phases. Aqueous phase concentrations were determined by direct analysis of this phase, while organic phase concentrations were determined from the original oil composition by difference. The log K/sub D/ values obtained for acidic and basic components were generally <3, while those for the neutral components ranged from 3 to 6. For aromatic hydrocarbons, strong correlations were observed between log K/sub D/ and log S/sub w/ (water solubility), and between log K/sub D/ and log K/sub o//sub w/ (octanol/water partition coefficient). Alkylated benzenes had significantly higher K/sub D/s than did unsubstituted aromatics of similar molecular weight. Examination of homologs revealed an increase of 0.307 log K/sub D/ units per additional carbon atom for polynuclear aromatic hydrocarbons having from 10 to 16 carbons. Alkyl substituent effects determined for various sets of homologs ranged from 0.391 to 0.466 log K/sub d/ units per -CH/sub 2/- group added. 38 refs., 5 figs., 7 tabs.

  15. Solvent Extraction Batch Distribution Coefficients with Savannah River Site Dissolved Salt Cake

    International Nuclear Information System (INIS)

    Walker, D.D.

    2002-01-01

    Researchers characterized high-level waste derived from dissolved salt cake from the Savannah River Site (SRS) tank farm and measured the cesium distribution coefficients (DCs) for extraction, scrub, and stripping steps of the caustic-side solvent extraction (CSSX) flowsheet. The measurements used two SRS high-level waste samples derived entirely or in part from salt cake. The chemical compositions of both samples are reported. Dissolved salt cake waste contained less Cs-137 and more dianions than is typical of supernate samples. Extraction and scrub DCs values for both samples exceeded process requirements and agreed well with model predictions. Strip DCs values for the Tank 46F sample also met process requirements. However, strip DCs values could not be calculated for the Tank 38H sample due to the poor material balance for Cs-137. Potential explanations for the poor material balance are discussed and additional work to determine the cause is described

  16. Sorption distribution coefficients of uranium, thorium and radium of selected Malaysian peat soils

    International Nuclear Information System (INIS)

    Mohd Zaidi Ibrahim; Zalina Laili; Muhamat Omar; Phillip, Esther

    2010-01-01

    A study on sorption of uranium, thorium and radium on Malaysian peat soils was conducted to determine their distribution coefficient (K d ) values. Batch studies were performed to investigate the influence of pH and the concentrations of radionuclides. Peat soil samples used in this study were collected from Bachok, Batu Pahat, Dalat, Hutan Melintang and Pekan. The peat samples from different location have different chemical characteristics and K d values. No correlation was found between chemical characteristics and the K d values for radium and thorium, but K d value for uranium was found correlated with humic and organic content. The K d value was found to be influenced by soluble humic substances or humic substances leach out from peat soils. (author)

  17. Evaluating and categorizing the reliability of distribution coefficient values in the sorption database

    International Nuclear Information System (INIS)

    Ochs, Michael; Saito, Yoshihiko; Kitamura, Akira; Shibata, Masahiro; Sasamoto, Hiroshi; Yui, Mikazu

    2007-03-01

    Japan Atomic Energy Agency (JAEA) has developed the sorption database (JNC-SDB) for bentonite and rocks in order to assess the retardation property of important radioactive elements in natural and engineered barriers in the H12 report. The database includes distribution coefficient (K d ) of important radionuclides. The K d values in the SDB are about 20,000 data. The SDB includes a great variety of K d and additional key information from many different literatures. Accordingly, the classification guideline and classification system were developed in order to evaluate the reliability of each K d value (Th, Pa, U, Np, Pu, Am, Cm, Cs, Ra, Se, Tc on bentonite). The reliability of 3740 K d values are evaluated and categorized. (author)

  18. A new approach to evaluate factors controlling elemental sediment–seawater distribution coefficients (K{sub d}) in coastal regions, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Takata, Hyoe, E-mail: takata@kaiseiken.or.jp [Marine Ecology Research Institute, Central Laboratory, Onjuku, Chiba (Japan); National Institute of Radiological Sciences, Chiba City, Chiba (Japan); Aono, Tatsuo; Tagami, Keiko; Uchida, Shigeo [National Institute of Radiological Sciences, Chiba City, Chiba (Japan)

    2016-02-01

    In numerical models to simulate the dispersion of anthropogenic radionuclides in the marine environment, the sediment–seawater distribution coefficient (K{sub d}) for various elements is an important parameter. In coastal regions, K{sub d} values are largely dependent on hydrographic conditions and physicochemical characteristics of sediment. Here we report K{sub d} values for 36 elements (Na, Mg, Al, K, Ca, V, Mn, Fe, Co, Ni, Cu, Se, Rb, Sr, Y, Mo, Cd, I, Cs, rare earth elements, Pb, {sup 232}Th and {sup 238}U) in seawater and sediment samples from 19 Japanese coastal regions, and we examine the factors controlling the variability of these K{sub d} values by investigating their relationships to hydrographic conditions and sediment characteristics. There was large variability in K{sub d} values for Al, Mn, Fe, Co, Ni, Cu, Se, Cd, I, Pb and Th. Variations of K{sub d} for Al, Mn, Fe, Co, Pb and Th appear to be controlled by hydrographic conditions. Although K{sub d} values for Ni, Cu, Se, Cd and I depend mainly on grain size, organic matter content, and the concentrations of hydrous oxides/oxides of Fe and Mn in sediments, heterogeneity in the surface characteristics of sediment particles appears to hamper evaluation of the relative importance of these factors. Thus, we report a new approach to evaluate the factors contributing to variability in K{sub d} for an element. By this approach, we concluded that the K{sub d} values for Cu, Se, Cd and I are controlled by grain size and organic matter in sediments, and the K{sub d} value for Ni is dependent on grain size and on hydrous oxides/oxides of Fe and Mn. - Highlights: • K{sub d}s for 36 elements were determined in 19 Japanese coastal regions. • K{sub d}s for several elements appeared to be controlled by multiple factors in sediments. • We evaluated these factors based on physico-chemical characteristics of sediments.

  19. The problem of predicting the size distribution of sediment supplied by hillslopes to rivers

    Science.gov (United States)

    Sklar, Leonard S.; Riebe, Clifford S.; Marshall, Jill A.; Genetti, Jennifer; Leclere, Shirin; Lukens, Claire L.; Merces, Viviane

    2017-01-01

    Sediments link hillslopes to river channels. The size of sediments entering channels is a key control on river morphodynamics across a range of scales, from channel response to human land use to landscape response to changes in tectonic and climatic forcing. However, very little is known about what controls the size distribution of particles eroded from bedrock on hillslopes, and how particle sizes evolve before sediments are delivered to channels. Here we take the first steps toward building a geomorphic transport law to predict the size distribution of particles produced on hillslopes and supplied to channels. We begin by identifying independent variables that can be used to quantify the influence of five key boundary conditions: lithology, climate, life, erosion rate, and topography, which together determine the suite of geomorphic processes that produce and transport sediments on hillslopes. We then consider the physical and chemical mechanisms that determine the initial size distribution of rock fragments supplied to the hillslope weathering system, and the duration and intensity of weathering experienced by particles on their journey from bedrock to the channel. We propose a simple modeling framework with two components. First, the initial rock fragment sizes are set by the distribution of spacing between fractures in unweathered rock, which is influenced by stresses encountered by rock during exhumation and by rock resistance to fracture propagation. That initial size distribution is then transformed by a weathering function that captures the influence of climate and mineralogy on chemical weathering potential, and the influence of erosion rate and soil depth on residence time and the extent of particle size reduction. Model applications illustrate how spatial variation in weathering regime can lead to bimodal size distributions and downstream fining of channel sediment by down-valley fining of hillslope sediment supply, two examples of hillslope control on

  20. Pesticides in stream sediment and aquatic biota: distribution, trends, and governing factors

    Science.gov (United States)

    Nowell, Lisa H.; Capel, Peter D.

    1999-01-01

    More than 20 years after the ban of DDT and other organochlorine pesticides, pesticides continue to be detected in air, rain, soil, surface water, bed sediment, and aquatic and terrestrial biota throughout the world. Recent research suggests that low levels of some of these pesticides may have the potential to affect the development, reproduction, and behavior of fish and wildlife, and possibly humans. Pesticides in Stream Sediment and Aquatic Biota: Distribution, Trends, and Governing Factors assesses the occurrence and behavior of pesticides in bed sediment and aquatic biota-the two major compartments of the hydrologic system where organochlorine pesticides are most likely to accumulate. This book collects, for the first time, results from several hundred monitoring studies and field experiments, ranging in scope from individual sites to the entire nation. Comprehensive tables provide concise summaries of study locations, pesticides analyzed, and study outcomes. Comprehensive and extensively illustrated, Pesticides in Stream Sediment and Aquatic Biota: Distribution, Trends, and Governing Factors evaluates the sources, environmental fate, geographic distribution, and long-term trends of pesticides in bed sediment and aquatic biota. The book focuses on organochlorine pesticides, but also assesses the potential for currently used pesticides to be found in bed sediment and aquatic biota. Topics covered in depth include the effect of land use on pesticide occurrence, mechanisms of pesticide uptake and accumulation by aquatic biota, and the environmental significance of observed levels of pesticides in stream sediment and aquatic biota.

  1. Trace elements distribution in bottom sediments from Amazon River estuary

    International Nuclear Information System (INIS)

    Lara, L.B.L.S.; Nadai Fernandes, E. de; Oliveira, H. de; Bacchi, M.A.

    1994-01-01

    The Amazon River discharges into a dynamic marine environment where there have been many interactive processes affecting dissolved and particulate solids, either those settling on the shelf or reaching the ocean. Trace elemental concentration, especially of the rare earth elements, have been determined by neutron activation analysis in sixty bottom sediment samples of the Amazon River estuary, providing information for the spatial and temporal variation study of those elements. (author). 16 refs, 6 figs, 3 tabs

  2. Coefficients of distribution and accumulation of K, Rb, Cs and 137Cs in the intensive poultry breeding cycle

    International Nuclear Information System (INIS)

    Djuric, G.; Ajdacic, N.; Institut za Nuklearne Nauke Boris Kidric, Belgrade

    1984-01-01

    The concentration of K,Rb,Cs and the activity level of Cs-137 in samples from the intensive poultry breeding cycle (feed, meat, eggs), under the condition of chronic alimentary contamination is presented. Concentrations of Cs and Rb were determined by non-destructive neutron activation analysis, concentration of K by atomic absorption flame photometry and activity of Cs-137 by gamma spectrometric analysis. On the basis of these results, coefficients of distribution and accumulation were calculated. The distribution coefficients of the analysed stable isotopes in meat have values close to 1, whereas for various parts of egg these coefficients vary between 0.5 and 1.5. Significant differences in Cs-137 distribution in various parts of egg were established. The values of accumulation coefficients indicate that all analysed elements selectively accumulate in the meat of young birds (broilers), and Cs-137 accumulates in the egg white as well. (orig.)

  3. Distribution, provenance and early diagenesis of major and trace metals in sediment cores from the Mandovi estuary, western India

    Digital Repository Service at National Institute of Oceanography (India)

    Prajith, A.; Rao, V.P.; Chakraborty, P.

    Major elements and trace metals were analyzed in four sediment cores recovered along a transect in the Mandovi estuary for their distribution, provenance and early diagenesis. The sediments were clayey silts in cores from the upper/lower estuary...

  4. Distribution of Fe, Mn, Ni, Co, Cu and Zn in non-lithogenous fractions of sediments of Gulf of Kutch

    Digital Repository Service at National Institute of Oceanography (India)

    Paropkari, A; Topgi, R.S.; Rao, Ch.M.; Murty, P.S.N.

    Contributions made by non-lithogenous fractions of sediments constitute a significant portion of the concentrations of the elements associated with the total sediment samples. The minor differences found in their distribution patterns can...

  5. Carrier Mediated Distribution System (CAMDIS): a new approach for the measurement of octanol/water distribution coefficients.

    Science.gov (United States)

    Wagner, Bjoern; Fischer, Holger; Kansy, Manfred; Seelig, Anna; Assmus, Frauke

    2015-02-20

    Here we present a miniaturized assay, referred to as Carrier-Mediated Distribution System (CAMDIS) for fast and reliable measurement of octanol/water distribution coefficients, log D(oct). By introducing a filter support for octanol, phase separation from water is facilitated and the tendency of emulsion formation (emulsification) at the interface is reduced. A guideline for the best practice of CAMDIS is given, describing a strategy to manage drug adsorption at the filter-supported octanol/buffer interface. We validated the assay on a set of 52 structurally diverse drugs with known shake flask log D(oct) values. Excellent agreement with literature data (r(2) = 0.996, standard error of estimate, SEE = 0.111), high reproducibility (standard deviation, SD < 0.1 log D(oct) units), minimal sample consumption (10 μL of 100 μM DMSO stock solution) and a broad analytical range (log D(oct) range = -0.5 to 4.2) make CAMDIS a valuable tool for the high-throughput assessment of log D(oc)t. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Evolution of Sr distribution coefficient as a function of time, incubation conditions and measurement technique

    International Nuclear Information System (INIS)

    Wang Guo; Staunton, Siobhan

    2005-01-01

    A thorough understanding of the dynamics of radiostrontium in soil is required to allow accurate long-term predictions of its mobility. We have followed the soil solution distribution of 85 Sr as a function of time under controlled conditions over 4 months and studied the effect of soil moisture content and organic matter amendments. Data have been compared to redox conditions and soil pH. To fuel the ongoing debate on the validity of distribution coefficient (K d ) values measured in dilute suspension, we have compared values obtained from the activity concentration in soil solution obtained by centrifugation to data obtained in suspension with or without air-drying of the soil samples after incubation. The 85 Sr adsorption properties of soil, incubated without prior contamination were also measured. There is some time-dependent adsorption of Sr. This is partly due to changing soil composition due to the decomposition of added organic matter and anaerobic conditions induced by flooding. There is also a kinetic effect, but adsorption remains largely reversible. Most of the observed effects are lost when soil is suspended in electrolyte solution

  7. Trace element distributions in aquatic sediments of Danang - Hoian area, Vietnam

    Energy Technology Data Exchange (ETDEWEB)

    Thuy, H.T.T.; Tobschall, H.J. [Erlangen-Nuernberg Univ., Erlangen (Germany). Inst. fuer Geologie und Mineralogie; An, P.V. [University of Mining and Geology, Hanoi (Viet Nam)

    2000-05-01

    Distribution of the trace elements Cr, Cu, Ni, Pb and Zn in surficial sediments of the river/sea environment in Danang - Hoian area (Vietnam) was investigated to examine the degree of metal pollution caused by anthropogenic activities. Point sources from domestic and industrial wastes are identified as dominant contributors of trace element accumulation. Surficial sediments of Hoian River show extremely high total concentrations of Cu (Average Concentration 295 {mu}g/g), Ni (AC 112 {mu}g/g), Pb (AC 396 {mu}g/g) and Zn (AC 429 mug/g) that exceed assigned safety levels ER-M. Similarly, the sediments of Han River show high Pb (AC 188 {mu}g/g) and Zn (AC 282 {mu}g/g) contents. In marine sediments of Thanhbinh beach Pb is also enriched (138 {mu}g/g) above guideline levels. In contrast the sediments of the Cude River are dominated by trace element concentrations close to background values. (orig.)

  8. Distribution of 137Cs in surface seawater and sediment around Sabahs Sulu-Sulawesi Sea

    International Nuclear Information System (INIS)

    Mohd Izwan Abdul Aziz; Ahmad Sanadi Abu Bakar; Yii, Mei Wo; Nurrul Assyikeen Jaffary; Zaharudin Ahmad

    2010-01-01

    The studies on distribution of 137 Cs in surface seawater and sediment around Sabahs Sulu-Sulawesi Sea were carried out during Ekspedisi Pelayaran Saintifik Perdana (EPSP) in July 2009. About sixteen and twenty five sampling locations were identified for surface seawater and sediment respectively in Sabahs Sulu-Sulawesi Sea. Large volumes of seawater samples are collected and co-precipitation technique was employed to concentrate cesium content before known amounts of 134 Cs tracer were added as yield determinant. Grab sampler were used to collect surface sediment sample. The caesium precipitate and sediment were dried and finely ground before counted using gamma-ray spectrometry system at 661 keV. The activity of 137 Cs was found in surface seawater and sediment to be in the range 1.73 Bq/ m 3 to 5.50 Bq/ m 3 and 1.15 Bq/ kg to 4.53 Bq/ kg respectively. (author)

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

    Science.gov (United States)

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

    2000-01-01

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

  10. A geomorphological assessments of the distribution of sediment sinks along the lower Amazon River

    Science.gov (United States)

    Park, E.; Latrubesse, E. M.

    2017-12-01

    Floodplain sediment storage budget is examined along the 1,000 km reach of the lower Amazon River based on extensive sets of remote sensing data and field measurements. Incorporating the washload discharges at gauge stations at the main channel and major tributaries, we analyzed the roles of vast floodplain on the Amazon River seasonal variability in sediment discharges. Annual washload accumulation rate on floodplain along the reach in between Manacapuru and Obidos of is estimated to be 79 Mt over inter-annual average. Period that the net loss over to the floodplain of washload coincide with discharge rising phase of the Amazon River at Obidos, when the river water level rises to make hydrologic connections to floodplain. Only during the early falling phase (July-August), 3.6 Mt of washload net gain occurred in a year, which was less than 5% of the annual net loss to the floodplain. To assess the spatial distribution of sediment sinks along the lower Amazon, we incorporated various hydro-geomorphic factors regarding floodplain geomorphic styles and morphometric parameters, such floodplain width, levee heights, water-saturated area, suspended sediment distribution over floodplain and distribution of impeded floodplain. Impeded floodplain that contains numerous large rounded lakes is the definition of active sediment sinks along the lower Amazon, which seasonally stores most of the water and traps sediment from the river. The results of these hydro-geomorphic factors collectively indicate that the extent and magnitudes of sediment sinks becomes larger downstream (from Manacapuru to Monte Alegre), which is proportionally related to the development of the water-saturated floodplain. This indicates the nonlinear geomorphic evolution of the Amazon floodplain through its longitudinal profile since the late Holocene that downstream reaches are still to be infilled with sediments (incomplete floodplain) thus acting as sediment sinks.

  11. AN EMPIRICAL INVESTIGATION OF THE EFFECTS OF NONNORMALITY UPON THE SAMPLING DISTRIBUTION OF THE PROJECT MOMENT CORRELATION COEFFICIENT.

    Science.gov (United States)

    HJELM, HOWARD; NORRIS, RAYMOND C.

    THE STUDY EMPIRICALLY DETERMINED THE EFFECTS OF NONNORMALITY UPON SOME SAMPLING DISTRIBUTIONS OF THE PRODUCT MOMENT CORRELATION COEFFICIENT (PMCC). SAMPLING DISTRIBUTIONS OF THE PMCC WERE OBTAINED BY DRAWING NUMEROUS SAMPLES FROM CONTROL AND EXPERIMENTAL POPULATIONS HAVING VARIOUS DEGREES OF NONNORMALITY AND BY CALCULATING CORRELATION COEFFICIENTS…

  12. Heavy metals and metalloids in the surface sediments of the Xiangjiang River, Hunan, China: distribution, contamination, and ecological risk assessment.

    Science.gov (United States)

    Chai, Liyuan; Li, Huan; Yang, Zhihui; Min, Xiaobo; Liao, Qi; Liu, Yi; Men, Shuhui; Yan, Yanan; Xu, Jixin

    2017-01-01

    Here, we aim to determine the distribution, ecological risk and sources of heavy metals and metalloids in the surface sediments of the Xiangjiang River, Hunan Province, China. Sixty-four surface sediment samples were collected in 16 sites of the Xiangjiang River, and the concentrations of ten heavy metals and metalloids (Mn, Zn, Cr, V, Pb, Cu, As, Ni, Co, and Cd) in the sediment samples were investigated using an inductively coupled plasma mass spectrometer (ICP-MS) and an atomic fluorescence spectrophotometer (AFS), respectively. The results showed that the mean concentrations of the ten heavy metals and metalloids in the sediment samples followed the order Mn > Zn > Cr > V > Pb > Cu > As ≈ Ni >Co > Cd. The geoaccumulation index (I geo ), enrichment factor (EF), modified degree of contamination (mC d ), and potential ecological risk index (RI) revealed that Cd, followed by Pb, Zn, and Cu, caused severely contaminated and posed very highly potential ecological risk in the Xiangjiang River, especially in Shuikoushan of Hengyang, Xiawan of Zhuzhou, and Yijiawan of Xiangtan. The Pearson's correlation coefficient (PCC) analysis, principal component analysis (PCA), and hierarchical cluster analysis (HCA) indicated that the ten heavy metals and metalloids in the sampling sediments of the Xiangjiang River were classified into three groups: (1) Cd, Pb, Zn, and Cu which possibly originated from Shuikoushan, Xiawan, and Yijiawan clustering Pb-Zn mining and smelting industries; (2) Co, V, Ni, Cr, and Al from natural resources; and (3) Mn and As. Therefore, our results suggest that anthropogenic activities, especially mining and smelting, have caused severe contamination of Cd, Pb, Zn, and Cu and posed very high potential ecological risk in the Xiangjiang River.

  13. Uranium distribution in Baikal sediments using SSNTD method for paleoclimate reconstruction

    CERN Document Server

    Zhmodik, S M; Nemirovskaya, N A; Zhatnuev, N S

    1999-01-01

    First data on local distribution of uranium in the core of Lake Baikal floor sediments (Academician ridge, VER-95-2, St 3 BC, 53 deg. 113'12'N/108 deg. 25'01'E) are presented in this paper. They have been obtained using (n,f)-radiography. Various forms of U-occurrence in floor sediments are shown, i.e. evenly disseminated, associated with clayey and diatomaceous components; micro- and macroinclusions of uranium bearing minerals - microlocations with uranium content 10-50 times higher than U-concentrations associated with clayey and diatomaceous components. Relative and absolute U-concentration can be determined for every mineral. Signs of various order periodicity of U-distribution in the core of Lake Baikal floor sediments have been found. Using (n,f)-radiography method of the study of Baikal floor sediment permits gathering of new information that can be used at paleoclimate reconstruction.

  14. On the possible ''normalization'' of experimental curves of 230Th vertical distribution in abyssal oceanic sediments

    International Nuclear Information System (INIS)

    Kuznetsov, Yu.V.; Al'terman, Eh.I.; Lisitsyn, A.P.; AN SSSR, Moscow. Inst. Okeanologii)

    1981-01-01

    The possibilities of the method of normalization of experimental ionic curves in reference to dating of abyssal sediments and establishing their accumulation rapidities are studied. The method is based on using correlation between ionic curves extrema and variations of Fe, Mn, C org., and P contents in abyssal oceanic sediments. It has been found that the above method can be successfully applied for correction of 230 Th vertical distribution data obtained by low-background γ-spectrometry. The method leads to most reliable results in those cases when the vertical distribution curves in sediments of elements concentrators of 230 Th are symbasic between themselves. The normalization of experimental ionic curves in many cases gives the possibility to realize the sediment age stratification [ru

  15. Distribution, speciation, environmental risk, and source identification of heavy metals in surface sediments from the karst aquatic environment of the Lijiang River, Southwest China.

    Science.gov (United States)

    Xu, Daoquan; Wang, Yinghui; Zhang, Ruijie; Guo, Jing; Zhang, Wei; Yu, Kefu

    2016-05-01

    The distribution and speciation of several heavy metals, i.e., As, Cd, Cr, Cu, Hg, Pb, and Zn, in surface sediments from the karst aquatic environment of the Lijiang River, Southwest China, were studied comparatively. The mean contents of Cd, Cu, Hg, Pb, and Zn were 1.72, 38.07, 0.18, 51.54, and 142.16 mg/kg, respectively, which were about 1.5-6 times higher than their corresponding regional sediment background values. Metal speciation obtained by the optimized BCR protocol highlighted the bioavailable threats of Cd, Cu, and Zn, which were highly associated with the exchangeable fraction (the labile phase). Hierarchical cluster analysis indicated that in sediments, As and Cr were mainly derived from natural and industrial sources, whereas fertilizer application might lead to the elevated level of Cd. Besides, Cu, Hg, Pb, and Zn were related to traffic activities. The effects-based sediment quality guidelines (SQGs) showed that Hg, Pb, and Zn could pose occasional adverse effects on sediment-dwelling organisms. However, based on the potential ecological risk assessment (PER) and risk assessment code (RAC), Cd was the most outstanding pollutant and posed the highest ecological hazard and bioavailable risk among the selected metals. Moreover, the metal partitioning between water and sediments was quantified through the calculation of the pseudo-partitioning coefficient (K P), and result implied that the sediments in this karst aquatic environment cannot be used as stable repositories for the metal pollutants.

  16. Chlorophyll and sediment distribution study of the Gulf of Kutch using remote sensing

    Digital Repository Service at National Institute of Oceanography (India)

    Kunte, P.D.; Takahiro Osawa; Yasuhiro Sugimori

    This study is largely based on the resulting series of SeaWiFS images and OCM images of Gulf of Kutch, which shows chlorophyll distribution on about 160 (cloud-free) dates between October 1998 and August 2001 period and sediment distribution pattern...

  17. Heterogeneous distribution of prokaryotes and viruses at the microscale in a tidal sediment

    DEFF Research Database (Denmark)

    Carreira, Cátia; Larsen, Morten; Glud, Ronnie

    2013-01-01

    In this study we show for the first time the microscale (mm) 2- and 3-dimensional spatial distribution and abundance of prokaryotes, viruses, and oxygen in a tidal sediment. Prokaryotes and viruses were highly heterogeneously distributed with patches of elevated abundances surrounded by areas of ...

  18. The distribution and abundance of gamma emitting radionuclides in Lake Ontario sediments

    International Nuclear Information System (INIS)

    McKinley, R.S.

    1985-03-01

    The distribution of gamma emitting radionuclides in Lake Ontario sediments was investigated. Samples were collected using a systematic design in the vicinity of Pickering and Darlington, and supplemented by lakewide offshore samples. Naturally occurring 40 K was the predominant source of gamma activity. 60 Co was the only potentially CANDU released radionuclide which showed a distributional association with the Pickering 'A' NGS discharge

  19. Pu and 137Cs in the Yangtze River estuary sediments: distribution and source identification.

    Science.gov (United States)

    Liu, Zhiyong; Zheng, Jian; Pan, Shaoming; Dong, Wei; Yamada, Masatoshi; Aono, Tatsuo; Guo, Qiuju

    2011-03-01

    Pu isotopes and (137)Cs were analyzed using sector field ICP-MS and γ spectrometry, respectively, in surface sediment and core sediment samples from the Yangtze River estuary. (239+240)Pu activity and (240)Pu/(239)Pu atom ratios (>0.18) shows a generally increasing trend from land to sea and from north to south in the estuary. This spatial distribution pattern indicates that the Pacific Proving Grounds (PPG) source Pu transported by ocean currents was intensively scavenged into the suspended sediment under favorable conditions, and mixed with riverine sediment as the water circulated in the estuary. This process is the main control for the distribution of Pu in the estuary. Moreover, Pu is also an important indicator for monitoring the changes of environmental radioactivity in the estuary as the river basin is currently the site of extensive human activities and the sea level is rising because of global climate changes. For core sediment samples the maximum peak of (239+240)Pu activity was observed at a depth of 172 cm. The sedimentation rate was estimated on the basis of the Pu maximum deposition peak in 1963-1964 to be 4.1 cm/a. The contributions of the PPG close-in fallout Pu (44%) and the riverine Pu (45%) in Yangtze River estuary sediments are equally important for the total Pu deposition in the estuary, which challenges the current hypothesis that the riverine Pu input was the major source of Pu budget in this area.

  20. Sediment textural characteristics and elemental distribution in the core sediments, Pullivasal and Kurusadai Island, Gulf of Mannar, Southeast coast of India

    Directory of Open Access Journals (Sweden)

    P. Saravanan

    2017-12-01

    Full Text Available Two core samples were collected in order to assess the textual characteristics and elemental distribution of the sediments, from the lagoonal environment of Pullivasal and Kurusadai island, Gulf of Mannar, Southeast coast of India. The distribution of the organic matter and calcium carbonate is chiefly controlled by the coral debris, shell fragments and mangrove litters. The elemental distribution is controlled by natural process and other trace elements are controlled by anthropogenic land based activities. Keywords: Sediment texture, Coral islands, Gulf of Mannar, Core sediments, Elemental distribution

  1. Effect of water content on strontium retardation factor and distribution coefficient in Chinese loess.

    Science.gov (United States)

    Huo, Lijuan; Qian, Tianwei; Hao, Junting; Liu, Hongfang; Zhao, Dongye

    2013-12-01

    Geological burial and landfill are often employed for disposal of nuclear wastes. Typically, radionuclides from nuclear facilities transport through the unsaturated zone before reaching the groundwater aquifer. However, transport studies are often conducted under saturated and steady-state flow conditions. This research aimed to examine the effects of unsaturated flow conditions and soil water content (θ) on Sr sorption and retardation in Chinese loess through 1D column transport experiments. Reagent SrCl2 was used as a surrogate for the radioactive isotope ((90)Sr) in the experiment because of their analogous adsorption and transportation characteristics. The spatial distribution of Sr along the column length was determined by segmenting the soil bed and analysing the Sr content in each soil segment following each column breakthrough test. The single-region (SR) and two-region (TR) models were employed to interpret the transport data of Sr as well as a tracer (Br(-)), which resulted in the dispersion coefficient (D) and retardation factor (Rd) under a given set of unsaturated flow conditions. For the tracer, the SR and TR models offered nearly the same goodness of fitting to the breakthrough curves (R(2) ≈ 0.97 for both models). For the highly sorptive Sr, however, the TR model provided better fitting (R(2), 0.80-0.96) to the Sr retention profiles than the SR model (R(2), 0.20-0.89). The Sr retention curves exhibited physical non-equilibrium characteristics, particularly at lower water content of the soil. For the unsaturated soil, D and the pore water velocity (v) displayed a weak linear correlation, which is attributed to the altering dispersivity as the water content varies. A much improved linear correlation was observed between D and v/θ. The retardation factor of Sr increased from 69.1 to 174.2 as θ decreased from 0.46 to 0.26 (cm(3) cm(-3)), while the distribution coefficient (Kd) based on Rd remained nearly unchanged at various θ levels. These

  2. Classification of distribution coefficient data by mineral components and chemical forms

    International Nuclear Information System (INIS)

    Takeda, Seiji; Kimura, Hideo; Matsuzuru, Hideo

    1996-01-01

    The use of distribution coefficient (Kd) in radionuclide transport model has been reported in a number of papers. However, Kd data cover a wide range even for a specific element. In this study the Kd data of neptunium, uranium and selenium, which are included in sorption database (SDB, OECD/NEA) of radionuclides, were classified by a solid phase and a dominant species in a solution. The aqueous species of these elements were estimated by a geochemical model. The Kd data classified by the analyzed speciation were tested by a nonparametric statistical method. The results of tests proved that the Kd data of neptunium or uranium, which covered a wide range, were influenced by the supersaturation of Np(OH) 4 (s) or schoepite. The Kd data of neptunium could be classified by the dominant aqueous species, NpO 2 + , NpO 2 CO 3 - , NpO 2 OH(aq) and Np(OH) 4 (aq). The Kd data of these four dominant species which are not equilibrated with supersaturated Np(OH) 4 (s) are less than 100 ml/g. The analyzed aqueous species of uranium were UO 2 (OH) 2 (aq) and UO 2 (CO 3 ) n 2-2n (n=2,3) in hexavalent state. It is suggested that the distribution coefficient of neptunium and uranium depends on dominant aqueous species or charged species, i.e., cationic, anionic and nonionic forms. The dominant aqueous species of selenium are HSe - , HSeO 3 - , SeO 3 2- and SeO 4 2- . The result of the nonparametric statistical test shows that the Kd value of HSeO 3 - is higher than of other anionic forms. However, the influence of the species, HSe - , SeO 3 2- and SeO 4 2- , on Kd values is not clearly identified. Considering the dominant species, the Kd of elements are in ranges of 1 to 2 orders of magnitude being in general narrower than those classified by mineral and rock types. (author)

  3. Element composition of biota, water and sediment in the Forsmark area, Baltic Sea. Concentrations, bioconcentration factors and partitioning coefficients (Kd) of 48 elements

    International Nuclear Information System (INIS)

    Kumblad, Linda; Bradshaw, Clare

    2008-08-01

    In this study the elemental composition of biota, water and sediment from a shallow bay in the Forsmark region have been determined. The report presents data for 48 different elements (Al, As, Ba, Br, C, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Dy, Er, Eu, F, Fe, Gd, Hg, Ho, I, K, Li, Lu, Mg, Mn, N, Na, Nd, Ni, P, Pb, Pr, Ra, Rb, S, Se, Si, Sm, Tb, Th, Ti, Tm, V, Yb, Zn, Zr) in all major functional groups of the coastal ecosystem (phytoplankton, zooplankton, benthic microalgae, macroalgae, macrophytes, benthic herbivores, benthic filter feeders, benthic detrivores, planktivorous fish, benthic omnivorous fish, carnivorous fish, dissolved and particulate matter in the water and the sediment) during spring 2005. The overall aim of the study is to contribute to a better understanding of ecological properties and processes that govern uptake and transfer of trace elements, heavy-metals, radionuclides and other non-essential elements/contaminants in coastal environments of the Baltic Sea. In addition, the data was collected to provide site-specific Bioconcentration Factors (BCF), Biomagnification Factors (BMF), partitioning coefficients (K d ) and element ratios (relative to carbon) for use in ongoing SKB safety assessments. All these values, as well as the element concentration data from which they are derived, are presented here. As such, this is mainly a data report, although initial interpretations of the data also are presented and discussed. Reported data include element concentrations, CNP-stoichiometry, and multivariate data analysis. Elemental concentrations varied greatly between organisms and environmental components, depending on the function of the elements, and the habitat, ecosystem function, trophic level and morphology (taxonomy) of the organisms. The results show for instance that food intake and metabolism strongly influence the elemental composition of organisms. The three macrophytes had quite similar elemental composition (despite their taxonomic differences

  4. Element composition of biota, water and sediment in the Forsmark area, Baltic Sea. Concentrations, bioconcentration factors and partitioning coefficients (K{sub d}) of 48 elements

    Energy Technology Data Exchange (ETDEWEB)

    Kumblad, Linda; Bradshaw, Clare (Dept. of Systems Ecology, Stockholm Univ. (Sweden))

    2008-08-15

    In this study the elemental composition of biota, water and sediment from a shallow bay in the Forsmark region have been determined. The report presents data for 48 different elements (Al, As, Ba, Br, C, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Dy, Er, Eu, F, Fe, Gd, Hg, Ho, I, K, Li, Lu, Mg, Mn, N, Na, Nd, Ni, P, Pb, Pr, Ra, Rb, S, Se, Si, Sm, Tb, Th, Ti, Tm, V, Yb, Zn, Zr) in all major functional groups of the coastal ecosystem (phytoplankton, zooplankton, benthic microalgae, macroalgae, macrophytes, benthic herbivores, benthic filter feeders, benthic detrivores, planktivorous fish, benthic omnivorous fish, carnivorous fish, dissolved and particulate matter in the water and the sediment) during spring 2005. The overall aim of the study is to contribute to a better understanding of ecological properties and processes that govern uptake and transfer of trace elements, heavy-metals, radionuclides and other non-essential elements/contaminants in coastal environments of the Baltic Sea. In addition, the data was collected to provide site-specific Bioconcentration Factors (BCF), Biomagnification Factors (BMF), partitioning coefficients (K{sub d}) and element ratios (relative to carbon) for use in ongoing SKB safety assessments. All these values, as well as the element concentration data from which they are derived, are presented here. As such, this is mainly a data report, although initial interpretations of the data also are presented and discussed. Reported data include element concentrations, CNP-stoichiometry, and multivariate data analysis. Elemental concentrations varied greatly between organisms and environmental components, depending on the function of the elements, and the habitat, ecosystem function, trophic level and morphology (taxonomy) of the organisms. The results show for instance that food intake and metabolism strongly influence the elemental composition of organisms. The three macrophytes had quite similar elemental composition (despite their taxonomic

  5. Sedimentation

    Science.gov (United States)

    Cliff R. Hupp; Michael R. Schening

    2000-01-01

    Sedimentation is arguably the most important water-quality concern in the United States. Sediment trapping is cited frequently as a major function of riverine-forested wetlands, yet little is known about sedimcntation rates at the landscape scale in relation to site parameters, including woody vegetation type, elevation, velocity, and hydraulic connection to the river...

  6. Sources, distribution and export coefficient of phosphorus in lowland polders of Lake Taihu Basin, China.

    Science.gov (United States)

    Huang, Jiacong; Gao, Junfeng; Jiang, Yong; Yin, Hongbin; Amiri, Bahman Jabbarian

    2017-12-01

    Identifying phosphorus (P) sources, distribution and export from lowland polders is important for P pollution management, however, is challenging due to the high complexity of hydrological and P transport processes in lowland areas. In this study, the spatial pattern and temporal dynamics of P export coefficient (PEC) from all the 2539 polders in Lake Taihu Basin, China were estimated using a coupled P model for describing P dynamics in a polder system. The estimated amount of P export from polders in Lake Taihu Basin during 2013 was 1916.2 t/yr, with a spatially-averaged PEC of 1.8 kg/ha/yr. PEC had peak values (more than 4.0 kg/ha/yr) in the polders near/within the large cities, and was high during the rice-cropping season. Sensitivity analysis based on the coupled P model revealed that the sensitive factors controlling the PEC varied spatially and changed through time. Precipitation and air temperature were the most sensitive factors controlling PEC. Culvert controlling and fertilization were sensitive factors controlling PEC during some periods. This study demonstrated an estimation of PEC from 2539 polders in Lake Taihu Basin, and an identification of sensitive environmental factors affecting PEC. The investigation of polder P export in a watershed scale is helpful for water managers to learn the distribution of P sources, to identify key P sources, and thus to achieve best management practice in controlling P export from lowland areas. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Radionuclide distributions in sediment cores retrieved from marine radioactive waste dumpsites

    International Nuclear Information System (INIS)

    Bowen, V.T.; Livingston, H.D.

    1981-01-01

    The concentrations, distributions and inventories of 55 Fe, 60 Co, 137 Cs, 134 Cs, 238 Pu, sup(239,240)Pu, 241 Am, 244 Cm and 242 Cm were measured in sediment samples collected in 1975-1976 from some Atlantic and Pacific sites used by the United States of America from 1946-1970 to dump solidified radioactive waste. Criteria used to distinguish waste-contaminated sediments from fallout-contaminated sediments include deviations of nuclide concentrations, inventories, internuclide ratios and depth distributions. The detection of nuclides absent from fallout is a further indicator. The data set used in comparing dumpsite sediment radioactivity with non-dumpsite radioactivity comes from a population of 11 North Atlantic cores in the depth range 2000-4000 m. A further set of 19 cores from the central North Pacific provides an interesting contrast to the data set for the shallower sediments closer to the coasts. The principal conclusion drawn from consideration of a large body of data, especially for 15 sediment cores from the Atlantic dumpsite, is that contamination is extremely localized with respect to the sources from which the waste is believed to originate. The majority of cores from both dumpsites are indistinguishable from populations of cores contaminated only by world-wide fallout. Clearly, contaminated sediments from both dumpsites show evidence of the introduction of waste radioactivity below the sediment surface before subsequent redistribution by in-sediment processes. These findings have significance for the selection and monitoring of sites to be used in connection with the ocean disposal of radioactive waste. (author)

  8. Distribution of the dominant microbial communities in marine sediments containing high concentrations of gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Briggs, B.; Colwell, F.; Carini, P.; Torres, M. [Oregon State Univ., Corvallis, OR (United States); Hangsterfer, A.; Kastner, M. [California Univ., San Diego, CA (United States). Scripps Inst. of Oceanography; Brodie, E. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States). Center for Environmental Biotechnology; Daly, R. [California Univ., Berkeley, CA (United States); Holland, M. [GeoTek, Daventry, Northants (United Kingdom); Long, P.; Schaef, H. [Pacific Northwest National Laboratory, Richland, WA (United States). Environmental Technology; Delwiche, M. [Idaho National Laboratory, Idaho Falls, ID (United States). Biotechnology; Winters, W. [United States Geological Survey, Woods Hole, MA (United States). Woods Hole Science Center; Riedel, M. [McGill Univ., Montreal, PQ (Canada). Dept. of Earth and Planetary Sciences

    2008-07-01

    Methane produced by microorganisms represents a large portion of the methane that occurs in marine sediments where gas hydrates are present. The diverse communities that populate these formations have been documented by cultures or through molecular traces. Previous studies have explored the biogeography of hydrate-bearing systems by comparing clone libraries developed from sediments where hydrates are abundant with those developed from sediments that lack hydrates. There is a distinct microbial community present in sediments that have methane hydrates. This paper presented an investigation into finer-scale biogeography, in order to determine how factors such as the presence or absence of hydrates, grain size, and the depositional environment in marine sediments may control the number, type and distribution of microbial communities in sediments. The purpose of the study was to understand the controls on the distribution and activity of all microbes that contribute to the conversion of organic matter to methane. To this aim, DNA was extracted from deep marine sediments cored from continental slope locations including offshore India and the Cascadia Margin. The data from the study was used to refine computational models that require biological rate terms that are consistent with sediment conditions in order to accurately describe the dynamics of this large methane reservoir. The paper discussed the materials and methods used for the study, including the sample site, sample collection and microbiological analysis. Results were presented in terms of DNA extractions; microbial diversity; and biofilm analyses. It was concluded that the findings from the study complemented previously reported studies which indicated the presence of diverse microbial communities in sediments containing methane hydrates. 9 refs., 5 figs.

  9. Statistical Models for Sediment/Detritus and Dissolved Absorption Coefficients in Coastal Waters of the Northern Gulf of Mexico

    National Research Council Canada - National Science Library

    Green, Rebecca E; Gould, Jr., Richard W; Ko, Dong S

    2008-01-01

    ... (CDOM) absorption coefficients from physical hydrographic and atmospheric properties. The models were developed for northern Gulf of Mexico shelf waters using multi-year satellite and physical data...

  10. Determination coefficient distribution rhenium and tungsten using method extraction with solvent methyl ethyl ketone

    International Nuclear Information System (INIS)

    Riftanio Natapratama Hidayat; Maria Christina Prihatiningsih; Duyeh Setiawan

    2015-01-01

    Determination of the distribution coefficient (K d ) of the rhenium and tungsten conducted for the purpose of knowing the value of K d of the two elements. K d value determination is applied to the process of separation rhenium-188 from target of tungsten-188 for the purposes purification of radioisotopes that are made to meet the radionuclide and radiochemical purity. The K d value determination using solvent extraction with methyl ethyl ketone (MEK). Prior to the determination of K d values, determined beforehand the optimum conditions of extraction process based on the effect of agitation time, the volume of MEK, and the pH of the solution. Confirmation the results of the extraction was conducted using UV-Vis spectrophotometer with a complexing KSCN under acidic conditions and reductant SnCl 2 . The results showed that the optimum condition extraction process to feed each of 10 ppm is when the agitation for 10 minutes, the volume of MEK in 20 ml, and the pH below 5. Obtained the maximum recovery of rhenium are drawn to the organic phase as much as 9.545 ppm. However, the condition of the extraction process does not affect the migration of tungsten to the organic phase. Then the maximum K d values obtained at 2.7566 rhenium and tungsten maximum K d is 0.0873. Optimum conditions of extraction process can be further tested on radioactive rhenium and tungsten as an alternative to the separation of radioisotopes. (author)

  11. Distribution coefficients of caesium, chlorine, iodine, niobium, selenium and technetium on Olkiluoto soils

    International Nuclear Information System (INIS)

    Soederlund, M.; Lusa, M.; Virtanen, S.; Vaelimaa, I.; Hakanen, M.; Lehto, J.; Lahdenperae, A.-M.

    2014-02-01

    Retention of caesium, chlorine, iodine, niobium, selenium and technetium was investigated on soil samples from Olkiluoto using laboratory batch sorption experiments. Distribution coefficients were measured for both dried and sieved and untreated (wet, not sieved) mineral soil and humus in aerobic and anaerobic conditions. Mineralogical composition of the samples was determined by XRD-analysis. Caesium was sorbed efficiently on mineral soil samples and less efficiently on humus. Sorption decreased with decreasing cation exchange capacity and clay fraction content. The effect of competing cations decreased in the order Cs + >NH 4 + >K + >Ca 2+ >Na + . Chlorine was not retained by mineral soil samples, and the sorption was weak on humus. The sorption of iodine was the strongest on humus and the weakest on the untreated mineral soil samples in the anaerobic conditions. In the mineral soil samples, the sorption decreased with decreasing organic matter content and increasing pH. The retention of niobium on soil samples was the most efficient among the studied elements. The retention was high regardless of the aeration conditions. Sorption on humus was smaller. Selenium was retained efficiently on humus. Sorption on mineral soil samples was stronger in aerobic conditions. Sorption increased with time. Technetium was sorbed well on humus and anaerobic, untreated mineral soil samples. Sorption increased with increasing organic matter content and decreasing redox potential. The results from the sorption experiments are used in the site specific radionuclide migration modelling. (orig.)

  12. Selection of distribution coefficients for contaminant fate and transport calculations: Strontium as a case study

    International Nuclear Information System (INIS)

    Kaplan, D.I.; Krupka, K.M.; Serne, R.J.

    1997-01-01

    As part of an ongoing project funded by a cooperative effort involving the Office of Radiation and Indoor Air (ORIA) of the U.S. Environmental Protection Agency (EPA), the Office of Environmental Restoration (EM-40) of the Department of Energy (DOE), and the Nuclear Regulatory Agency (NRC), distribution coefficient (K d ) values are being compiled from the literature to develop provisional tables for cadmium, cesium, chromium, lead, plutonium, strontium, thorium, and uranium. The tables are organized according to important aqueous- and solid-phase parameters affecting the sorption of these contaminants. These parameters, which vary with contaminant, include pH and redox conditions; cation exchange capacity (CEC); presence of iron-oxide, aluminum-oxide, clay, and mica minerals; organic matter content; and solution concentrations of contaminants, competing ions, and complexing ligands. Sorption information compiled for strontium is used to illustrate our approach. The strontium data show how selected geochemical parameters (i.e., CEC, pH, and clay content) affect Strontium K d values and the selection of open-quote default close-quote K d values needed for modeling contaminant transport and risks at sites for which site specific data are lacking. Results of our evaluation may be used by site management and technical staff to assess contaminant fate, migration, and risk calculations in support of site remediation and waste management decisions

  13. Optimised method to estimate octanol water distribution coefficient (logD) in a high throughput format.

    Science.gov (United States)

    Low, Ying Wei Ivan; Blasco, Francesca; Vachaspati, Prakash

    2016-09-20

    Lipophilicity is one of the molecular properties assessed in early drug discovery. Direct measurement of the octanol-water distribution coefficient (logD) requires an analytical method with a large dynamic range or multistep dilutions, as the analyte's concentrations span across several orders of magnitude. In addition, water/buffer and octanol phases which have very different polarity could lead to matrix effects and affect the LC-MS response, leading to erroneous logD values. Most compound libraries use DMSO stocks as it greatly reduces the sample requirement but the presence of DMSO has been shown to underestimate the lipophilicity of the analyte. The present work describes the development of an optimised shake flask logD method using deepwell 96 well plate that addresses the issues related to matrix effects, DMSO concentration and incubation conditions and is also amenable to high throughput. Our results indicate that the equilibrium can be achieved within 30min by flipping the plate on its side while even 0.5% of DMSO is not tolerated in the assay. This study uses the matched matrix concept to minimise the errors in analysing the two phases namely buffer and octanol in LC-MS. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Distribution coefficients for Pb+2 and Cr+6 with variation in soil particle size

    International Nuclear Information System (INIS)

    Singhal, R.K.; Preetha, J.; Gurg, R.P.

    2003-01-01

    Simulated experiments were conducted in the laboratory to evaluate the impact of soil particle size on the distribution coefficient (K d ) for soil - water system for Pb as Pb +2 and Cr as Cr +6 . The variation in particle size leads to variation in mineralogical and organic carbon (OC) contents which in turn lead to variation in cation exchange capacity (CEC). The conditions were kept as close to that of the natural environment during the spiking of the soil. The spiked soil is fractionated in seven different fractions between 500 - 355 μm and 105 - > 75 μm contains relatively higher percentage of OC than the other fractions. The CEC of different fractions of the soil is determined by ammonium acetate method. Higher CEC was observed for particle in the range of 105 - > 75 μm. The analysis of Pb and Cr was carried out using Atomic Absorption Spectrometer after the complete destruction f the soil matrix. Among the various fractions, the K d values are higher for 75μm for Pb +2 and Cr +6 and their ranges are 4.3-9.6 x 10 5 ml/gm and 2.1-24.8 x 10 6 ml/gm, respectively. (author)

  15. Predicting cyclohexane/water distribution coefficients for the SAMPL5 challenge using MOSCED and the SMD solvation model

    Science.gov (United States)

    Diaz-Rodriguez, Sebastian; Bozada, Samantha M.; Phifer, Jeremy R.; Paluch, Andrew S.

    2016-11-01

    We present blind predictions using the solubility parameter based method MOSCED submitted for the SAMPL5 challenge on calculating cyclohexane/water distribution coefficients at 298 K. Reference data to parameterize MOSCED was generated with knowledge only of chemical structure by performing solvation free energy calculations using electronic structure calculations in the SMD continuum solvent. To maintain simplicity and use only a single method, we approximate the distribution coefficient with the partition coefficient of the neutral species. Over the final SAMPL5 set of 53 compounds, we achieved an average unsigned error of 2.2± 0.2 log units (ranking 15 out of 62 entries), the correlation coefficient ( R) was 0.6± 0.1 (ranking 35), and 72± 6 % of the predictions had the correct sign (ranking 30). While used here to predict cyclohexane/water distribution coefficients at 298 K, MOSCED is broadly applicable, allowing one to predict temperature dependent infinite dilution activity coefficients in any solvent for which parameters exist, and provides a means by which an excess Gibbs free energy model may be parameterized to predict composition dependent phase-equilibrium.

  16. A statistical approach to the interpretation of aliphatic hydrocarbon distributions in marine sediments

    Science.gov (United States)

    Rapp, J.B.

    1991-01-01

    Q-mode factor analysis was used to quantitate the distribution of the major aliphatic hydrocarbon (n-alkanes, pristane, phytane) systems in sediments from a variety of marine environments. The compositions of the pure end members of the systems were obtained from factor scores and the distribution of the systems within each sample was obtained from factor loadings. All the data, from the diverse environments sampled (estuarine (San Francisco Bay), fresh-water (San Francisco Peninsula), polar-marine (Antarctica) and geothermal-marine (Gorda Ridge) sediments), were reduced to three major systems: a terrestrial system (mostly high molecular weight aliphatics with odd-numbered-carbon predominance), a mature system (mostly low molecular weight aliphatics without predominance) and a system containing mostly high molecular weight aliphatics with even-numbered-carbon predominance. With this statistical approach, it is possible to assign the percentage contribution from various sources to the observed distribution of aliphatic hydrocarbons in each sediment sample. ?? 1991.

  17. The evaluation of the equilibrium partitioning method using sensitivity distributions of species in water and soil or sediment

    NARCIS (Netherlands)

    Beelen P van; Verbruggen EMJ; Peijnenburg WJGM; ECO

    2002-01-01

    The equilibrium partitioning method (EqP-method) can be used to derive environmental quality standards (like the Maximum Permissible Concentration or the intervention value) for soil or sediment, from aquatic toxicity data and a soil/water or sediment/water partitioning coefficient. The validity of

  18. The Effect of Nonzero Autocorrelation Coefficients on the Distributions of Durbin-Watson Test Estimator: Three Autoregressive Models

    Directory of Open Access Journals (Sweden)

    Mei-Yu LEE

    2014-11-01

    Full Text Available This paper investigates the effect of the nonzero autocorrelation coefficients on the sampling distributions of the Durbin-Watson test estimator in three time-series models that have different variance-covariance matrix assumption, separately. We show that the expected values and variances of the Durbin-Watson test estimator are slightly different, but the skewed and kurtosis coefficients are considerably different among three models. The shapes of four coefficients are similar between the Durbin-Watson model and our benchmark model, but are not the same with the autoregressive model cut by one-lagged period. Second, the large sample case shows that the three models have the same expected values, however, the autoregressive model cut by one-lagged period explores different shapes of variance, skewed and kurtosis coefficients from the other two models. This implies that the large samples lead to the same expected values, 2(1 – ρ0, whatever the variance-covariance matrix of the errors is assumed. Finally, comparing with the two sample cases, the shape of each coefficient is almost the same, moreover, the autocorrelation coefficients are negatively related with expected values, are inverted-U related with variances, are cubic related with skewed coefficients, and are U related with kurtosis coefficients.

  19. A Correction of Random Incidence Absorption Coefficients for the Angular Distribution of Acoustic Energy under Measurement Conditions

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2009-01-01

    Most acoustic measurements are based on an assumption of ideal conditions. One such ideal condition is a diffuse and reverberant field. In practice, a perfectly diffuse sound field cannot be achieved in a reverberation chamber. Uneven incident energy density under measurement conditions can cause...... discrepancies between the measured value and the theoretical random incidence absorption coefficient. Therefore the angular distribution of the incident acoustic energy onto an absorber sample should be taken into account. The angular distribution of the incident energy density was simulated using the beam...... tracing method for various room shapes and source positions. The averaged angular distribution is found to be similar to a Gaussian distribution. As a result, an angle-weighted absorption coefficient was proposed by considering the angular energy distribution to improve the agreement between...

  20. Spatial and temporal distribution of 210Po in sediments from Thane Creek Mumbai, India

    International Nuclear Information System (INIS)

    Pandit, G.G.; Bhangare, R.C.; Tiwari, M.; Ajmal, P.Y.; Sahu, S.K.; Puranik, V.D.

    2013-01-01

    The study of sediments in coastal areas has great importance for the understanding of the interaction between human activities and marine systems. The Polonium-210 activity has been commonly used as environmental tracer in many environmental studies especially in determination of the age of sediments in the aquatic systems. The determination of age of the sediments provides the chronological profile of contamination of the marine environment over the period of time. The temporal and spatial distribution of 210 Po in Thane creek sediments was observed in this study. The allochthonous activity of 210 Po in surface sediments across different locations was observed to be the highest amongst different layers which ranged between 22.5-56.3 Bq/kg. The total 210 Po activity in different layers of the sediments ranged between 15.3 to 88.9 Bq/kg. The two modeling approaches CRS and CIC were applied to determine age of the sediment at four locations in the creek. (author)

  1. Hyperspectral imaging of the microscale distribution and dynamics of microphytobenthos in intertidal sediments

    KAUST Repository

    Chennu, Arjun; Fä rber, Paul; Volkenborn, Nils; Alnajjar, Mohammad Ahmad; Janssen, Felix; de Beer, Dirk; Polerecky, Lubos

    2013-01-01

    We describe a novel, field-deployable hyperspectral imaging system, called Hypersub, that allows noninvasive in situ mapping of the microphytobenthos (MPB) biomass distribution with a high spatial (sub-millimeter) and temporal (minutes) resolution over areas of 1 × 1 m. The biomass is derived from a log-transformed and near-infrared corrected reflectance hyperspectral index, which exhibits a linear relationship (R2 > 0.97) with the chlorophyll a (Chl a) concentration in the euphotic zone of the sediment and depends on the sediment grain size. Deployments of the system revealed that due to factors such as sediment topography, bioturbation, and grazing, the distribution of MPB in intertidal sediments is remarkably heterogeneous, with Chl a concentrations varying laterally by up to 400% of the average value over a distance of 1 cm. Furthermore, due to tidal cycling and diel light variability, MPB concentrations in the top 1 mm of sediments are very dynamic, changing by 40–80% over a few hours due to vertical migration. We argue that the high-resolution hyperspectral imaging method overcomes the inadequate resolution of traditional methods based on sedimentary Chl a extraction, and thus helps improve our understanding of the processes that control benthic primary production in coastal sediments.

  2. Hyperspectral imaging of the microscale distribution and dynamics of microphytobenthos in intertidal sediments

    KAUST Repository

    Chennu, Arjun

    2013-10-03

    We describe a novel, field-deployable hyperspectral imaging system, called Hypersub, that allows noninvasive in situ mapping of the microphytobenthos (MPB) biomass distribution with a high spatial (sub-millimeter) and temporal (minutes) resolution over areas of 1 × 1 m. The biomass is derived from a log-transformed and near-infrared corrected reflectance hyperspectral index, which exhibits a linear relationship (R2 > 0.97) with the chlorophyll a (Chl a) concentration in the euphotic zone of the sediment and depends on the sediment grain size. Deployments of the system revealed that due to factors such as sediment topography, bioturbation, and grazing, the distribution of MPB in intertidal sediments is remarkably heterogeneous, with Chl a concentrations varying laterally by up to 400% of the average value over a distance of 1 cm. Furthermore, due to tidal cycling and diel light variability, MPB concentrations in the top 1 mm of sediments are very dynamic, changing by 40–80% over a few hours due to vertical migration. We argue that the high-resolution hyperspectral imaging method overcomes the inadequate resolution of traditional methods based on sedimentary Chl a extraction, and thus helps improve our understanding of the processes that control benthic primary production in coastal sediments.

  3. Radiocesium distribution on sea sediment and in benthic organisms in the north-east Japan coast

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Tsuneo; Ambe, Daisuke; Kaeriyama, Hideki; Shigenobu, Yuya; Fujimoto, Ken; Saito, Hajime; Miki, Shiduho; Setou, Takashi; Morita, Takami; Watanabe, Tomowo [National Research Institute of Fisheries Sciences, Fisheries Research Agency, 2-12-4, Fukuura, Kanazawaward, Yokohama, Kanagawa, 236-8648 (Japan); Sawada, Hideki [National Resarch Institute of Fisheries Engineering, Fisheries Research Agency, 7620-7, Hasaki, Kamisu-shi, Ibaraki, 314-0408 (Japan)

    2014-07-01

    A large amount of radioactive materials, especially radiocesium, were discharged into the western North Pacific Ocean by the Fukushima Daiichi Nuclear Power Plant (FDNPP) disaster following the Great East Japan Earthquake and tsunami on 11 March 2011. Although radiocesium concentrations in sea water had quickly diminished via water mixing processes, significant amount still existed on sea floors near Fukushima Prefecture. To assess present distributions and/or spatio-temporal variations of sea sediment radiocesium and its potential affection to benthic ecosystems, we had conducted 5'x5' 2-D observation of sea sediment radiocesium concentrations repeatedly from Feb. 2012 to Jul. 2013. Off Fukushima Prefecture, the higher concentration area of radioactive cesium was often observed in the south area from the FDNPP and a north-south high value band was tended to be along the isobaths around 100 m where the concentration values up to thousands Bq/kg-dry order were observed. The concentrations generally decreased eastward from the high concentration band. At many surveyed positions, the vertical profiles of the radiocesium concentrations in sea sediment showed an exponentially decreasing in deeper layer. The influence of the FDNPP was suggested to generally reach up to 10 cm depth from sediment-surface. A negative correlation was found between the radiocesium concentration and median grain size of the sediment, suggesting that the adsorption capability of sediment for cesium associated with grain size possibly has a large contribution to the formation process of the spatial distribution pattern of the radiocesium concentration. In contrast to the land sediment, Chemical reaching experiment results showed that the radiocesium concentration in the organic component of bottom sediment has higher value than that of bulk sediment, suggesting that non-exchangeable adsorption cite of mineral component of marine sediments had already occupied by stable cesium (~2 nM in

  4. Trace metal distributions in Posidonia oceanica and sediments from Taranto Gulf (Ionian Sea, Southern Italy

    Directory of Open Access Journals (Sweden)

    A. DI LEO

    2013-03-01

    Full Text Available Distribution of metals (Hg, Pb, Sn, Cu, Cd and Zn was determined in sediments and in different tissues of Posidonia oceanica collected from San Pietro Island, Taranto Gulf (Ionian Sea, Southern Italy. In seagrass, results, compared with metal concentrations in sediments, showed that the highest concentrations of Hg, Pb, Sn and Cu were found in the roots, while in the green leaves were found the highest levels of Cd and Zn. Instead the lowest metal concentrations were found in the basal part of the leaf. Levels of  metals in the leaves were similar to those found by other authors in uncontaminated areas of the Mediterranean Sea. Mercury levels in roots were correlated to levels in sediments. This could demonstrate the plant memorizes sediments contamination . This study reinforces the usefulness and the relevance of Posidonia oceanica as an indicator of spatial metal contamination and an interesting tool for environmental quality evaluation.

  5. Stochastic distribution of the required coefficient of friction for level walking--an in-depth study.

    Science.gov (United States)

    Chang, Wen-Ruey; Matz, Simon; Chang, Chien-Chi

    2012-01-01

    This study investigated the stochastic distribution of the required coefficient of friction (RCOF) which is a critical element for estimating slip probability. Fifty participants walked under four walking conditions. The results of the Kolmogorov-Smirnov two-sample test indicate that 76% of the RCOF data showed a difference in distribution between both feet for the same participant under each walking condition; the data from both feet were kept separate. The results of the Kolmogorov-Smirnov goodness-of-fit test indicate that most of the distribution of the RCOF appears to have a good match with the normal (85.5%), log-normal (84.5%) and Weibull distributions (81.5%). However, approximately 7.75% of the cases did not have a match with any of these distributions. It is reasonable to use the normal distribution for representation of the RCOF distribution due to its simplicity and familiarity, but each foot had a different distribution from the other foot in 76% of cases. The stochastic distribution of the required coefficient of friction (RCOF) was investigated for use in a statistical model to improve the estimate of slip probability in risk assessment. The results indicate that 85.5% of the distribution of the RCOF appears to have a good match with the normal distribution.

  6. Global distribution of radiolytic H2 production in marine sediment and implications for subsurface life

    Science.gov (United States)

    Sauvage, J.; Flinders, A. F.; Spivack, A. J.; D'Hondt, S.

    2017-12-01

    We present the first global estimate of radiolytic H2production in marine sediment. Knowledge of microbial electron donor production rates is critical to understand the bioenergetics of Earth's subsurface ecosystems In marine sediment, radiolysis of water by radiation from naturally occurring radionuclides leads to production of reduced (H2) and oxidized (H2O2, O2) species. Water radiolysis is catalyzed by marine sediment. The magnitude of catalysis depends on sediment composition and radiation type. Deep-sea clay is especially effective at enhancing H2 yields, increasing yield by more than an order of magnitude relative to pure water. This previously unrecognized catalytic effect of geological materials on radiolytic H2 production is important for fueling microbial life in the subseafloor, especially in sediment with high catalytic power. Our estimate of radiolytic H2 production is based on spatially integrating a previously published model and uses (i) experimentally constrained radiolytic H2 yields for the principal marine sediment types, (ii) bulk sediment radioactive element content of sediment cores in three ocean basins (N. Atlantic, N. and S. Pacific), and global distributions of (iii) seafloor lithology, (iv) sediment porosity, and (v) sediment thickness. We calculate that global radiolytic H2 production in marine sediment is 1.6E+12 mol H2 yr-1. This production rate is small relative to the annual rate of photosynthetic organic-matter production in the surface ocean. The globally integrated ratio of radiolytic H2 production relative to photosynthetic primary production is 4.1E-4, based on electron equivalences. Although small relative to global photosynthetic biomass production, sediment-catalyzed production of radiolytic products is significant in the subseafloor. Our analysis of 9 sites in the N. Atlantic, N. and S. Pacific suggests that H2 is the primary microbial fuel in organic-poor sediment older than a few million years; at these sites, calculated

  7. Vertical distribution of radioactive particles in Ottawa River sediment near the Chalk River Laboratories

    International Nuclear Information System (INIS)

    Lee, D.R.; Hartwig, D.S.

    2011-01-01

    Previously, we described an area of above-background levels of radioactivity in the bed of the Ottawa River near the Chalk River Laboratories. The area was about 200 m wide by 400 m long and in water 8 to 30 m deep. The source of the radioactivity was associated with the location of cooling-water discharge. Particles of radioactive material were later recovered from the upper 10-15 cm of sediment and were determined to be sand-sized grains of nuclear fuel and corrosion products. This report provides an examination of the vertical distribution of radioactive particles in the riverbed. Twenty-three dredge samples (representing 1.2 m 2 of riverbed) were collected near the Process Outfall. Each dredge sample was dissected in horizontal intervals 1-cm-thick. Each interval provided a 524 cm 3 sample of sediment that was carefully examined for particulate radioactivity. Approximately 80% of the radioactivity appeared to be associated with discrete particles. Although the natural sediment in the general area is cohesive, silty clay and contains less than 10% sand, the sediment near the Outfall was found to be rich in natural sand, presumably from sources such as winter sanding of roads at the laboratories. The radioactive particles were almost entirely contained in the top-most 10 cm of the river bed. The majority of the particles were found several centimetres beneath the sediment surface and the numbers of particles and the radioactivity of the particles peaked 3 to 7 cm below the sediment surface. Based on the sediment profile, there appeared to have been a marked decrease in the deposition of particulate radioactivity in recent decades. The vertical distribution of radioactive particles indicated that sedimentation is resulting in burial and that the deposition of most of the particulate radioactivity coincided with the operation of Chalk River's NRX reactor from 1947 to 1992. (author)

  8. Speciation distribution and mass balance of copper and zinc in urban rain, sediments, and road runoff.

    Science.gov (United States)

    Zuo, Xiaojun; Fu, Dafang; Li, He

    2012-11-01

    Heavy metal pollution in road runoff had caused widespread concern since the last century. However, there are little references on metal speciation in multiple environmental media (e.g., rain, road sediments, and road runoff). Our research targeted the investigation of metal speciation in rain, road sediments, and runoff; the analysis of speciation variation and mass balance of metals among rain, road sediments, and runoff; the selection of main factors by principal component analysis (PCA); and the establishment of equation to evaluate the impact of rain and road sediments to metals in road runoff. Sequential extraction procedure contains five steps for the chemical fractionation of metals. Flame atomic absorption spectrometry (Shimadzu, AA-6800) was used to determine metal speciation concentration, as well as the total and dissolved fractions. The dissolved fractions for both Cu and Zn were dominant in rain. The speciation distribution of Zn was different from that of Cu in road sediments, while speciation distribution of Zn is similar to that of Cu in runoff. The bound to carbonates for both Cu and Zn in road sediments were prone to be dissolved by rain. The levels of Cu and Zn in runoff were not obviously influenced by rain, but significantly influenced by road sediments. The masses for both Cu and Zn among rain, road sediments, and road runoff approximately meet the mass balance equation for all rainfall patterns. Five principal factors were selected for metal regression equation based on PCA, including rainfall, average rainfall intensity, antecedent dry periods, total suspended particles, and temperature. The established regression equations could be used to predict the effect of road runoff on receiving environments.

  9. Vertical distribution of dehalogenating bacteria in mangrove sediment and their potential to remove polybrominated diphenyl ether contamination.

    Science.gov (United States)

    Pan, Ying; Chen, Juan; Zhou, Haichao; Farzana, Shazia; Tam, Nora F Y

    2017-11-30

    The removal and degradation of polybrominated diphenyl ethers (PBDEs) in sediments are not clear. The vertical distribution of total and dehalogenating bacteria in sediment cores collected from a typical mangrove swamp in South China and their intrinsic degradation potential were investigated. These bacterial groups had the highest abundances in surface sediments (0-5cm). A 5-months microcosm experiment also showed that surface sediments had the highest rate to remove BDE-47 than deeper sediments (5-30cm) under anaerobic condition. The deeper sediments, being more anaerobic, had lower population of dehalogenating bacteria leading to a weaker BDE-47 removal potential than surface sediments. Stepwise multiple regression analysis indicated that Dehalococcoides spp. were the most important dehalogenating bacteria affecting the anaerobic removal of BDE-47 in mangrove sediments. This is the first study reporting that mangrove sediments harbored diverse groups of dehalogenating bacteria and had intrinsic potential to remove PBDE contamination. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Studies on distribution coefficient (Kd) of naturally occurring radionuclides in geological matrices

    International Nuclear Information System (INIS)

    Pandit, G.G.

    2014-01-01

    Accurate prediction of fate and transport of toxic and radioactive metals in the subsurface of uranium tailing pond sites is critical to the assessment of environmental impact and to the development of effective remediation technologies. The mobility of radionuclides and toxic metals is enhanced by acidification of tailings due to sulphide oxidation catalysed by microbial activity. Due to infiltration of water, there is a possibility of leaching of these radionuclides and toxic metals from the tailings pond to the ground water. Sorption onto mineral surfaces is an important mechanism for reducing radionuclide concentrations along ground water flow paths and retarding radionuclide migration to the accessible environment. Reactive transport of ground water contaminants often assume that the reaction governing the retardation of a particular contaminant or radionuclide can be described by simple partitioning constant, K d . This constant is assumed to account for all the reversible sorption processes affecting transport of the contaminant. Experimental determination of site-specific K d values is absolutely essential for the accurate estimation of reactive transport of these contaminants. The results of such studies would be helpful to model migration of these pollutants and to estimate the radiation dose to members of the public through groundwater drinking pathway at different distances from the tailings pond. In the present study it is clearly observed that K d values of most of the radionuclides are strongly dependent on different soil and ground water parameters. The relationships generated between distribution coefficient values of different radionuclides and different soil and ground water parameters can be used to generate look up table. And these relationships can also be used for the prediction of K d values of different radionuclides by using the different physico-chemical parameters of soil and ground water of the particular location

  11. Distribution of strontium in sediments of the Minicoy atoll, Lakshadweep

    Digital Repository Service at National Institute of Oceanography (India)

    Mascarenhas, A.; Siddiquie, H.N.; Topgi, R.S.

    it is lower near the island. Distribution of Sr indicates an inverse relation with magnesium (r = -0.37). Sr/Ca x 1000 ratios on the reef and lagoon range from 4.9 to 8.7; being higher in the lagoon and lower on the reef. Low Sr values on the reef and higher...

  12. Estimation Of The Spatial Distribution Of Crop Coefficient (Kc) From Landsat Satellite Imagery

    International Nuclear Information System (INIS)

    Abou EI-Magd, I.H.

    2009-01-01

    Single crop coefficient factor (K c ) is an essential component for crop water allocation for efficient irrigation scheduling and irrigation water management. Kc is basically defined as the ratio of actual evapotranspiration and grass/alfalfa reference evapotranspiration and always measured by lysimeter in localized area in the field, which then generalized on the whole irrigated land. The lack of precise information about the crop coefficient particularly in our country together with both small sized fields and heterogeneity of agricultural crops calls for developing a new methodology for computing a real time crop coefficient from remotely sensed data. This paper discusses the methodology developed for obtaining a real time single crop coefficient from Landsat Satellite ETM + 7 imageries. The methodology was applied and optimized on one irrigation field with two different dates and crop cover in the northern Delta of Egypt

  13. Spatial distribution of trace metals in sediments from urban streams of Semarang, Central Java, Indonesia.

    NARCIS (Netherlands)

    Widianarko, B.; Verweij, R.A.; van Gestel, C.A.M.; van Straalen, N.M.

    2000-01-01

    Elevated environmental concentrations of metals are usually associated with the impact of urbanization. The present study is focused on metal contamination in urban sediments. A field survey was carried out to determine the distribution of four metals, i.e., cadmium (Cd), lead (Pb), copper (Cu), and

  14. Urbanization effects on sediment and trace metals distribution in an urban winter pond (Netanya, Israel)

    NARCIS (Netherlands)

    Zohar, I.; Teutsch, N.; Levin, N.; Mackin, G.; de Stigter, H.; Bookman, R.

    2017-01-01

    PurposeThis paper aims to elucidate urban development-induced processes affecting the sediment and the distribution of contaminating metals in a seasonal pond located in the highly populated Israeli Coastal Plain. The paper demonstrates how an integrated approach, including geochemical,

  15. INFLUENCE OF SEDIMENT SUPPLY, LITHOLOGY, AND WOOD DEBRIS ON THE DISTRIBUTION OF BEDROCK AND ALLUVIAL CHANNELS

    Science.gov (United States)

    Field surveys in the Willapa River basin, Washington State, indicate that the drainage area?channel slope threshold describing the distribution of bedrock and alluvial channels is influenced by the underlying lithology and that local variations in sediment supply can overwhelm ba...

  16. Textural parameters distribution in sediments surface of the Uruguay river background between km 221 and 254

    International Nuclear Information System (INIS)

    Capeluto, W.; Campos, T. de los

    2010-01-01

    The aim of this paper is to analyze the distribution of textural statistical parameters and spatial variation in the morphology of the sediment areas. The geology of the area comprises alluvial and alluvial deposits of variable thicknesses overlying deposits of Fray Bent os, Salto and Guichon formations that occasionally emerge in the river bed

  17. Measurement of Turbulent Skin Friction Drag Coefficients Produced by Distributed Surface Roughness of Pristine Marine Coatings

    DEFF Research Database (Denmark)

    Zafiryadis, Frederik; Meyer, Knud Erik; Gökhan Ergin, F.

    drag coefficients as well as roughness Reynolds numbers for the various marine coatings across the range of Rex by fitting of the van Driest profile. The results demonstrate sound agreement with the present ITTC method for determining skin friction coefficients for practically smooth surfaces at low...... Reynolds numbers compared to normal operation mode for the antifouling coatings. Thus, better estimates for skin friction of rough hulls can be realised using the proposed method to optimise preliminary vessel design....

  18. Spatial and vertical distribution of polycyclic aromatic hydrocarbons in mangrove sediments

    Energy Technology Data Exchange (ETDEWEB)

    Ke, L.; Yu, K.S.H.; Wong, Y.S.; Tam, N.F.Y. [Department of Biology and Chemistry, Center of Coastal Pollution and Conservation, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong SAR (China)

    2005-03-20

    The distribution and historical changes of polycyclic aromatic hydrocarbons (PAHs) contamination in mangrove sediments in Hong Kong SAR were investigated. Surface sediments (2-3 cm) collected from four mangrove swamps exhibited significant spatial variations in concentrations of total PAH (with |PAHs ranging from 56 to 3758 ng g{sup -1} dry wt), as well as the composition of 16 USEPA priority PAH compounds. Within a small swamp with an area of 0.68 ha, the total PAH concentrations also differed from sampling site to site, indicating that the PAH contamination is localized and confined to a very small area within the same swamp. Discharges from municipal and industrial wastewater, urban runoff, oil leakage from boats and ships, and accidental oil spill are possible sources of the PAH contamination. The sediment depth profiles reveal that the surface sediment layer (0-5 cm) had lower total PAH concentrations than that in the bottom layer (15-20 cm), and PAH composition also changed with the sediment layers. Based on the estimated annual sediment deposition rate in Hong Kong SAR of around 0.4-0.5 cm, the present findings suggest that the PAH contamination was most serious between 1958 and 1979 but started to decline thereafter. Such decline was probably due to changes in petroleum usage in urban areas and a better control of wastewater discharges from 1980 onwards in this region.

  19. Moessbauer investigation of characteristic distribution of iron oxides in sediments from the Antarctica

    International Nuclear Information System (INIS)

    Kuzmann, E.; Homonnay, Z.; Vertes, A.; Garg, V.K.; De Oliveira, A.C.; De Souza Junior, P.A.; Schuch, L.A.

    2000-01-01

    Sediments from the Admirally Bay, King George Island, Antarctica, were investigated by 57 Fe Moessbauer spectroscopy, X-ray diffractometry, and radiometry. Quartz, feldspar, chlorite, calcite, dolomite, mica, kaolinite, hematite and magnetite were identified as constituent minerals in the sediment samples. The phase composition and the iron distribution among the crystallographic sites of iron-bearing minerals (silicates, magnetite and hematite) of samples from different location have been derived from the complex Moessbauer spectra. At different locations sediments has significant characteristic differences in the mineral composition, in the iron distribution among the crystallographic site of silicates, and in the specific radioactivity of Cs radionuclides. These results indicate differences in the rock formation and alteration by the sediments in this maritime part of Antarctica. There is a much higher amount of iron oxides in the sediments from south part of the geological fault across the Admirally Bay than in the north part. This can be associated with much more alteration in the rocks in the south part compared to the northern one. This finding can contribute to the question of the history of the formation and alteration of volcanic rocks in the border of Antarctica. (author)

  20. Hysteresis in suspended sediment to turbidity relations due to changing particle size distributions

    Science.gov (United States)

    Landers, Mark N.; Sturm, Terry W.

    2013-01-01

    Turbidity (T) is the most ubiquitous of surrogate technologies used to estimate suspended-sediment concentration (SSC). The effects of sediment size on turbidity are well documented; however, effects from changes in particle size distributions (PSD) are rarely evaluated. Hysteresis in relations of SSC-to-turbidity (SSC~T) for single stormflow events was observed and quantified for a data set of 195 concurrent measurements of SSC, turbidity, discharge, velocity, and volumetric PSD collected during five stormflows in 2009–2010 on Yellow River at Gees Mill Road in metropolitan Atlanta, Georgia. Regressions of SSC-normalized turbidity (T/SSC) on concurrently measured PSD percentiles show an inverse, exponential influence of particle size on turbidity that is not constant across the size range of the PSD. The majority of the influence of PSD on T/SSC is from particles of fine-silt and smaller sizes (finer than 16 microns). This study shows that small changes in the often assumed stability of the PSD are significant to SSC~T relations. Changes of only 5 microns in the fine silt and smaller size fractions of suspended sediment PSD can produce hysteresis in the SSC~T rating that can increase error and produce bias. Observed SSC~T hysteresis may be an indicator of changes in sediment properties during stormflows and of potential changes in sediment sources. Trends in the PSD time series indicate that sediment transport is capacity-limited for sand-sized sediment in the channel and supply-limited for fine silt and smaller sediment from the hillslope.

  1. Artificial neural network application for predicting soil distribution coefficient of nickel

    International Nuclear Information System (INIS)

    Falamaki, Amin

    2013-01-01

    The distribution (or partition) coefficient (K d ) is an applicable parameter for modeling contaminant and radionuclide transport as well as risk analysis. Selection of this parameter may cause significant error in predicting the impacts of contaminant migration or site-remediation options. In this regards, various models were presented to predict K d values for different contaminants specially heavy metals and radionuclides. In this study, artificial neural network (ANN) is used to present simplified model for predicting K d of nickel. The main objective is to develop a more accurate model with a minimal number of parameters, which can be determined experimentally or select by review of different studies. In addition, the effects of training as well as the type of the network are considered. The K d values of Ni is strongly dependent on pH of the soil and mathematical relationships were presented between pH and K d of nickel recently. In this study, the same database of these presented models was used to verify that neural network may be more useful tools for predicting of K d . Two different types of ANN, multilayer perceptron and redial basis function, were used to investigate the effect of the network geometry on the results. In addition, each network was trained by 80 and 90% of the data and tested for 20 and 10% of the rest data. Then the results of the networks compared with the results of the mathematical models. Although the networks trained by 80 and 90% of the data the results show that all the networks predict with higher accuracy relative to mathematical models which were derived by 100% of data. More training of a network increases the accuracy of the network. Multilayer perceptron network used in this study predicts better than redial basis function network. - Highlights: ► Simplified models for predicting K d of nickel presented using artificial neural networks. ► Multilayer perceptron and redial basis function used to predict K d of nickel in

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

    Directory of Open Access Journals (Sweden)

    K. L. Spencer

    2002-01-01

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

  3. Distribution of the rare earth elements in the surface sediments from the lower Wuding River of China

    International Nuclear Information System (INIS)

    Longjiang, M.; Duowen, M.; Ke, H.; Jinghong, Y.

    2010-01-01

    The abundance and distribution of rare earth elements (REE) and their signatures in the Wuding River of China were studied from samples of surface sediments and related to the geological formation in its watershed. The total REE (ΣREE) average concentrations of the Wuding River sediments (144.56 μg g -1 ), is lower than that in the Yangtze River sediments (167.10 μg g -1 ), getting closer to the values of the Yellow River sediments (137.76 μg g -1 ), being equivalent to the values of the UCC (the upper continental crust) (146.37 μg g-1). The chondrite-normalized REEs indicated LREE enrichment and flat HREE depletion and also showed a slightly negative Eu-anomaly. A similar chondrite-normalized REE distribution pattern between the Wuding River sediments and Yellow River sediments demonstrated the Wuding River sediments are the important material sources of the Yellow River sediments. UCC-normalized REE patterns between the Wuding River sediments and the Yellow River sediments were almost equivalent and close to the UCC. These implied the Wuding River sediments and the Yellow River sediments are subjected mostly to physical weathering due to higher erosion rates. Consequently, they can be used to trace the UCC compositions. (author)

  4. Ionization constants by curve fitting: determination of partition and distribution coefficients of acids and bases and their ions.

    Science.gov (United States)

    Clarke, F H; Cahoon, N M

    1987-08-01

    A convenient procedure has been developed for the determination of partition and distribution coefficients. The method involves the potentiometric titration of the compound, first in water and then in a rapidly stirred mixture of water and octanol. An automatic titrator is used, and the data is collected and analyzed by curve fitting on a microcomputer with 64 K of memory. The method is rapid and accurate for compounds with pKa values between 4 and 10. Partition coefficients can be measured for monoprotic and diprotic acids and bases. The partition coefficients of the neutral compound and its ion(s) can be determined by varying the ratio of octanol to water. Distribution coefficients calculated over a wide range of pH values are presented graphically as "distribution profiles". It is shown that subtraction of the titration curve of solvent alone from that of the compound in the solvent offers advantages for pKa determination by curve fitting for compounds of low aqueous solubility.

  5. Distribution and mortality of diapause eggs from calanoid copepods in relation to sedimentation regimes

    DEFF Research Database (Denmark)

    Sichlau, Mie Hylstofte; Hansen, Jørgen L.S.; Andersen, Thorbjørn J.

    2011-01-01

    Distribution, abundance and age of diapause eggs from three species of calanoid copepods (in particular from Acartia spp. most likely Acartia tonsa, and Centropages hamatus and less numerous from Temora longicornis) were recorded in sediment profiles by enumerating hatched nauplii from incubated...... between the stations. Dating of the sediment cores suggested a ~70-year maximum age of viable eggs on the northernmost stations, and ~28 year at the southernmost stations. The eggs exhibited a significantly higher mortality rate at the southernmost stations compared with the northernmost, 0.35–0.53 year−1...

  6. Sediments as indicators of artificial radionuclide distribution west of La Hague

    International Nuclear Information System (INIS)

    Guegueniat, P.; Auffret, J.P.; Ballada, J.

    1981-01-01

    Four-year investigations of the coastal surface sediments and associated radionuclides in the English Channel show complex distribution patterns around La Hague. Plutonium ratios in the particulate fraction confirm the general understanding gathered from long-term gamma studies - mainly that accumulation of La Hague generated radionuclides is in the Bay of Mont-Saint-Michel and along the Normandy-Brittany Coast. The oil from the Amoco Cadiz accident caused a significant increase in coastal sediment activity of 144 Ce. Experimental studies with plutonium and hydrocarbons indicate that plutonium is more difficult to desorb than 144 Ce. (author)

  7. Distribution and Potential Toxicity of Trace Metals in the Surface Sediments of Sundarban Mangrove Ecosystem, Bangladesh

    Science.gov (United States)

    Kumar, A.; Ramanathan, A.; Mathukumalli, B. K. P.; Datta, D. K.

    2014-12-01

    The distribution, enrichment and ecotoxocity potential of Bangladesh part of Sundarban mangrove was investigated for eight trace metals (As, Cd, Cr, Cu, Fe, Mn, Pb and Zn) using sediment quality assessment indices. The average concentration of trace metals in the sediments exceeded the crustal abundance suggesting sources other than natural in origin. Additionally, the trace metals profile may be a reflection of socio-economic development in the vicinity of Sundarban which further attributes trace metals abundance to the anthropogenic inputs. Geoaccumulation index suggests moderately polluted sediment quality w.r.t. Ni and As and background concentrations for Al, Fe, Mn, Cu, Zn, Pb, Co, As and Cd. Contamination factor analysis suggested low contamination by Zn, Cr, Co and Cd, moderate by Fe, Mn, Cu and Pb while Ni and As show considerable and high contamination, respectively. Enrichment factors for Ni, Pb and As suggests high contamination from either biota or anthropogenic inputs besides natural enrichment. As per the three sediment quality guidelines, Fe, Mn, Cu, Ni, Co and As would be more of a concern with respect to ecotoxicological risk in the Sundarban mangroves. The correlation between various physiochemical variables and trace metals suggested significant role of fine grained particles (clay) in trace metal distribution whereas owing to low organic carbon content in the region the organic complexation may not be playing significant role in trace metal distribution in the Sundarban mangroves.

  8. The Influence of Biot’s Coefficient on the Estimation of Effective Stress on Deep Sea Sediments

    DEFF Research Database (Denmark)

    Awadalkarim, Ahmed; Fabricius, Ida Lykke

    In this paper we addresse the changes in physical properties of the Eocene and Paleocene shale from the Atlantic Basin, as a function of burial diagenesis. We also showed the influence of using correct Biot’s coefficient (β) on the estimation of vertical effective stress. We correlated our porosity...

  9. The influence of wave energy and sediment transport on seagrass distribution

    Science.gov (United States)

    Stevens, Andrew W.; Lacy, Jessica R.

    2012-01-01

    A coupled hydrodynamic and sediment transport model (Delft3D) was used to simulate the water levels, waves, and currents associated with a seagrass (Zostera marina) landscape along a 4-km stretch of coast in Puget Sound, WA, USA. A hydroacoustic survey of seagrass percent cover and nearshore bathymetry was conducted, and sediment grain size was sampled at 53 locations. Wave energy is a primary factor controlling seagrass distribution at the site, accounting for 73% of the variability in seagrass minimum depth and 86% of the variability in percent cover along the shallow, sandy portions of the coast. A combination of numerical simulations and a conceptual model of the effect of sea-level rise on the cross-shore distribution of seagrass indicates that the area of seagrass habitat may initially increase and that wave dynamics are an important factor to consider in predicting the effect of sea-level rise on seagrass distributions in wave-exposed areas.

  10. A global survey of the distribution of free gas in marine sediments

    Science.gov (United States)

    Fleischer, Peter; Orsi, Tim; Richardson, Michael

    2003-10-01

    Following the work of Aubrey Anderson in the Gulf of Mexico, we have attempted to quantify the global distribution of free gas in shallow marine sediments, and have identified and indexed over one hundred documented cases in the scientific and engineering literature. Our survey confirms previous assumptions, primarily that gas bubbles are ubiquitous in the organic-rich muds of coastal waters and shallow adjacent seas. Acoustic turbidity as recorded during seismo-acoustic surveys is the most frequently cited evidence used to infer the presence of seafloor gas. Biogenic methane predominates within these shallow subbottom deposits. The survey also reveals significant imbalances in the geographic distribution of studies, which might be addressed in the future by accessing proprietary data or local studies with limited distribution. Because of their global prevalence, growing interest in gassy marine sediments is understandable as their presence has profound scientific, engineering and environmental implications.

  11. Seasonal and spatial distribution of metals in surface sediment of an urban estuary

    International Nuclear Information System (INIS)

    Buggy, Conor J.; Tobin, John M.

    2008-01-01

    Aquatic pollution by metals is of concern because of various toxic effects to marine life. The Tolka Estuary, Co. Dublin, Ireland, is a typical Irish urban estuary. It has a significant metal loading originating from the urban environment. Results of a 25 month analysis of cadmium, copper, lead and zinc spatial and temporal distribution over 10 sample locations in this estuary are presented in this paper. Metal concentrations were analysed using differential pulse polarography. Significant seasonal and spatial trends in metal distribution were observed over the 25 months. Sediment metal concentrations gradually increased (30-120%) in spring to a maximum at the end of summer which was followed by a decrease in winter months (30-60%). Sediment organic matter (OM) concentrations exhibited similar seasonal trends and a positive correlation between OM and metal distributions was observed, implying OM had an influence on metal distributions over time. - Assessment and correlation of the seasonal and spatial distribution of metals and organic matter in surface sediment of an urban estuary

  12. Vertical distribution and community composition of anammox bacteria in sediments of a eutrophic shallow lake.

    Science.gov (United States)

    Qin, H; Han, C; Jin, Z; Wu, L; Deng, H; Zhu, G; Zhong, W

    2018-07-01

    The aim of this study was to explore the vertical distribution traits of anaerobic ammonium-oxidizing (anammox) bacterial relative abundance and community composition along the oxic/anoxic sediment profiles in a shallow lake. The Illumina Miseq-based sequencing and quantitative polymerase chain reactions were utilized to analyse relative abundance of anammox hydrazine synthase (hzsB) gene in comparison with bacterial 16S rRNA genes, anammox bacterial relative abundance (the number of anammox sequences divided by total number of sequences), community composition and diversity in sediments. The relative abundance of hzsB gene at the low-nitrogen (LN) site in the lake sediments showed that the vertical distribution of anammox bacteria increased to a peak, then decreased with increasing depth. Moreover, the relative abundance of hzsB gene at the high-nitrogen site was significantly lower than that at the LN site. Additionally, the community composition results showed that Candidatus Brocadia sp. was the dominant genus. In addition, the anammox bacterial diversity was also site specific. Redundancy analysis showed that the total N and the NH 4 + -N content might be the most important factors affecting anammox bacterial community composition in the studied sites. The results revealed the specific vertical variance of anammox bacterial distribution and community composition in oxic/anoxic sediments of a eutrophic shallow lake. This is the first study to demonstrate that anammox bacteria displayed the particular distribution in freshwater sediments, which implied a strong response to the anthropogenic eutrophication. © 2018 The Society for Applied Microbiology.

  13. Distribution of 137Cs and 226Ra in the sediments of Aswan High Dam lake

    International Nuclear Information System (INIS)

    Ismail, S.S.; Unfried, E.; Grass, F.

    1994-01-01

    Sediment samples of the High Dam lake were investigated for their 137 Cs, 226 Ra, 228 Th, and 40 K content, using low-level γ-spectroscopy. The results show that at the beginning of the lake (500 km from the High Dam), where sediments consist mostly of sand, the level of 137 Cs is very low (0.1 Bq*kg -1 ). The maximum value (22.3 Bq*kg -1 ) was found 40 km from the wall of the High Dam, where the composition of the sediments is nearly 50% clays. The distribution of the natural nuclides 226 Ra, 228 Th and 40 K shows a different trend. (author) 9 refs.; 9 figs.; 1 tab

  14. Plutonium distribution and remobilization in sediments of the Rhone River mouth (North-Western Mediterranean)

    International Nuclear Information System (INIS)

    Lansard, B.

    2004-06-01

    The aim of the present study was to describe the distribution and remobilization of plutonium (Pu) in the sediments off the Rhone river mouth. Most of the 238 Pu and 239,240 Pu isotopes introduced into the Rhone River were discharged by the liquid effluents released from the Marcoule reprocessing plant, located 120 km upstream the river mouth. Due to its high affinity for particles and its long half life, 238 Pu is a promising tracer to follow the dispersion of particulate matter from the Rhone River to the Mediterranean Sea. During the 3 REMORA cruises, sediment samples were specifically collected in the Rhone pro-delta area and more offshore on the whole continental shelf of the Gulf of Lions. The measurements of alpha emitters gave a first detailed spatial distribution of Pu isotope concentrations in surface sediments off the Rhone mouth. Using 137 Cs concentrations and their correlations with Pu isotopes, we were able to give a first estimate of Pu inventories for the sediments of the study area. In 2001, plutonium inventories were estimated to 92 ± 7 GBq of 238 Pu and 522 ± 44 GBq of 239,240 Pu for an area of 500 km 2 in front of the Rhone River mouth. Roughly, 50 % of these inventories are trapped in an area of 100 km 2 corresponding to the extent of the Rhone pro-delta zone. In spring 2002, an ADCP, with current velocity and wave measurements, was moored off the Rhone River mouth. This unique in situ dataset highlights the major role of South-East swells in the erosion of pro-deltaic sediments and their dispersion to the South-Westward direction. Plutonium remobilization was examined using a new experimental design based on sediment resuspension processes studied within a linear recirculating flume. For Gulf of Lions sediments and for a given hydrodynamic stress, remobilization fluxes raised a maximum of 0.08 Bq.m -2 .h -1 for 238 Pu and 0.64 Bq.m -2 .h -1 for 239,240 Pu. A first plutonium budget determined for the study area indicates that at least 85

  15. On the Use of Fine Distributed Moderating Material to Enhance Feedback Coefficients in Fast Reactors

    International Nuclear Information System (INIS)

    Merk, B.

    2012-01-01

    Conclusions and outlook: • Use of moderating material to enhance feedback coefficients in SFR: • Creation of a new degree of freedom for SFR design; • Good opportunities for the compensation of the effects due to transmutation fuels; • No major influence on Am incinieration; • Major problem is the thermal stability; • Stability up to ~1300°C by use of YH

  16. Calculation of the fuel temperature coefficient of reactivity considering non-uniform radial temperature distribution in the fuel rod

    Energy Technology Data Exchange (ETDEWEB)

    Pazirandeh, Ali [Islamic Azad Univ., Tehran (Iran, Islamic Republic of). Science and Research Branch; Hooshyar Mobaraki, Almas

    2017-07-15

    The safe operation of a reactor is based on feedback models. In this paper we attempted to discuss the influence of a non-uniform radial temperature distribution on the fuel rod temperature coefficient of reactivity. The paper demonstrates that the neutron properties of a reactor core is based on effective temperature of the fuel to obtain the correct fuel temperature feedback. The value of volume-averaged temperature being used in the calculations of neutron physics with feedbacks would result in underestimating the probable event. In the calculation it is necessary to use the effective temperature of the fuel in order to provide correct accounting of the fuel temperature feedback. Fuel temperature changes in different zones of the core and consequently reactivity coefficient change are an important parameter for analysis of transient conditions. The restricting factor that compensates the inserted reactivity is the temperature reactivity coefficient and effective delayed neutron fraction.

  17. Caesium-137 distribution, inventories and accumulation history in the Baltic Sea sediments.

    Science.gov (United States)

    Zaborska, Agata; Winogradow, Aleksandra; Pempkowiak, Janusz

    2014-01-01

    The Baltic Sea is susceptible to pollution by hazardous substances due to limited water exchange, shallowness, and the large catchment area. Radionuclides, particularly (137)Cs, are one of the most hazardous anthropogenic substances present in the Baltic environment. This study was conducted to present (137)Cs present contamination that should further be a subject of reliable monitoring when the new Nuclear Power Plant is put into operation in the northern Poland. The sea-wide, up to date distribution of (137)Cs activities and inventories in the Baltic Sea bottom sediments are presented. The (137)Cs activity concentrations were measured in 30 cm long sediment cores collected at 22 sampling stations. Sediment accumulation rates were quantified by (210)Pb geochronology to follow the history of (137)Cs accumulation. The (137)Cs inventories and fluxes were calculated. Most of the Baltic Sea sediments accumulated (137)Cs in the range from 750 to 2675 Bq m(-2). The Bothnian Bay is severely contaminated by (137)Cs with inventories up to 95,191 Bq m(-2). This region is moreover characterized by extremely large patchiness of (137)Cs inventories. The (137)Cs annual fluxes are highest at the two stations located at the Bothnian Bay (342 Bq m(-2) and 527 Bq m(-2)) due to large Chernobyl (137)Cs contamination of that region and high sediment accumulation rates. When these stations are excluded, the recent, annual mean value of (137)Cs load to the Baltic Sea deposits is 38 ± 22 Bq m(-2). The distribution of radio-caesium inventories over the Baltic Sea nowadays reflects the pattern of Chernobyl contamination. The radio-caesium deposited in surface sediments is not permanently buried, but may be resuspended and redeposited by currents, bioturbation or anthropogenic activities. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. The spatial and temporal distribution of heavy metals in sediments of Victoria Harbour, Hong Kong

    International Nuclear Information System (INIS)

    Tang, Chloe Wing-yee; Ip, Carman Ching-man; Zhang Gan; Shin, Paul K.S.; Qian Peiyuan; Li Xiangdong

    2008-01-01

    Victoria Harbour has received substantial loadings of pollutants from industrial and municipal wastewater discharged since the 1950s. Inputs of contaminants have declined dramatically during the last two decades as a result of better controls at the source and improved wastewater treatment facilities. To assess the spatial and temporal changes of metal contaminants in sediments in Victoria Harbour, core and grab sediments were collected. The central harbour areas were generally contaminated with heavy metals. The spatial distribution of trace metals can probably be attributed to the proximity of major urban and industrial discharge points, and to the effect of tidal flushing in the harbour. In the sediment cores, the highest concentrations of trace metals were observed to have accumulated during the 1950s-1980s, corresponding with the period of rapid urban and industrial development in Hong Kong. From the late 1980s, there has been a major decline in the concentrations of trace metals, due to a reduction in industrial activities and to the enactment of wastewater pollution controls in the territory. The Pb isotopic compositions of the sediments revealed the anthropogenic inputs of Pb to the harbour. The 206 Pb/ 207 Pb ratios varied from 1.154 to 1.190, which were lower than those of background geological materials in Hong Kong ( 206 Pb/ 207 Pb: 1.201-1.279). The data also indicated that the Pb in the harbour sediments most likely originated from mixed sources, including the leaded gasoline used in the past and other anthropogenic sources

  19. Distribution and assessment of sediment toxicity in Tamaki Estuary, Auckland, New Zealand

    Science.gov (United States)

    Abrahim, G. M. S.; Parker, R. J.; Nichol, S. L.

    2007-07-01

    Heavy metal levels in surface sediments from Tamaki Estuary demonstrate significant up estuary increases in Cu, Pb, Zn, Cd and mud concentrations. Increased metal levels towards the head of the estuary are linked to local catchment sources reflecting the historical development, industrialisation and urbanisation of catchment areas surrounding the upper estuary. The relatively narrow constriction in the middle estuary (Panmure area), makes it susceptible to accumulation of upper estuary pollutants, since the constriction reduces circulation and extends the time required for fine waterborne sediments in the upper estuary to exchange with fresh coastal water. As a result fine fraction sediments trapped in the upper estuary facilitate capture and retention of pollutants at the head of the estuary. The increase in sandy mud poor sediments towards the mouth of the estuary is associated with generally low metal concentrations. The estuary’s geomorphic shape with a mid estuary constriction, sediment texture and mineralogy and catchment history are significant factors in understanding the overall spatial distribution of contaminants in the estuary. Bulk concentration values for Cu, Pb, Zn, and Cd in all the studied surface samples occur below ANZECC ISQG-H toxicity values. Cd and Cu concentrations are also below the ISQG-L toxicity levels for these elements. However, Pb and Zn concentrations do exceed the ISQG-L values in some of the surface bulk samples in the upper estuary proximal to long established sources of catchment pollution.

  20. Distribution and temporal variation of trace metal enrichment in surface sediments of San Jorge Bay, Chile.

    Science.gov (United States)

    Valdés, Jorge; Román, Domingo; Guiñez, Marcos; Rivera, Lidia; Morales, Tatiana; Morales, Tomás; Avila, Juan; Cortés, Pedro

    2010-08-01

    Cu, Pb, and Hg concentrations were determined in surface sediment samples collected at three sites in San Jorge Bay, northern Chile. This study aims to evaluate differences in their spatial distribution and temporal variability. The highest metal concentrations were found at the site "Puerto", where minerals (Cu and Pb) have been loaded for more than 60 years. On the other hand, Hg does not pose a contamination problem in this bay. Cu and Pb concentrations showed significant variations from 1 year to another. These variations seem to be a consequence of the combination of several factors, including changes in the loading and/or storage of minerals in San Jorge Bay, the dredging of bottom sediments (especially at Puerto), and seasonal changes in physical-chemical properties of the water column that modify the exchange of metals at the sediment-water interface. Differences in the contamination factor and geoaccumulation index suggest that pre-industrial concentrations measured in marine sediments of this geographical zone, were better than geological values (average shale, continental crust average) for evaluating the degree of contamination in this coastal system. Based on these last two indexes, San Jorge Bay has a serious problem of Cu and Pb pollution at the three sampling locations. However, only Cu exceeds the national maximum values used to evaluate ecological risk and the health of marine environments. It is suggested that Chilean environmental legislation for marine sediment quality--presently under technical discussion--is not an efficient tool for protecting the marine ecosystem.

  1. Salinity drives archaeal distribution patterns in high altitude lake sediments on the Tibetan Plateau.

    Science.gov (United States)

    Liu, Yongqin; Priscu, John C; Xiong, Jinbo; Conrad, Ralf; Vick-Majors, Trista; Chu, Haiyan; Hou, Juzhi

    2016-03-01

    Archaeal communities and the factors regulating their diversity in high altitude lakes are poorly understood. Here, we provide the first high-throughput sequencing study of Archaea from Tibetan Plateau lake sediments. We analyzed twenty lake sediments from the world's highest and largest plateau and found diverse archaeal assemblages that clustered into groups dominated by methanogenic Euryarchaeota, Crenarchaeota and Halobacteria/mixed euryarchaeal phylotypes. Statistical analysis inferred that salinity was the major driver of community composition, and that archaeal diversity increased with salinity. Sediments with the highest salinities were mostly dominated by Halobacteria. Crenarchaeota dominated at intermediate salinities, and methanogens were present in all lake sediments, albeit most abundant at low salinities. The distribution patterns of the three functional types of methanogens (hydrogenotrophic, acetotrophic and methylotrophic) were also related to changes in salinity. Our results show that salinity is a key factor controlling archaeal community diversity and composition in lake sediments on a spatial scale that spans nearly 2000 km on the Tibetan Plateau. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Spatial and Temporal Variability in Sediment P Distribution and Speciation in Coastal Louisiana

    Science.gov (United States)

    Bowes, K.; White, J. R.; Maiti, K.

    2017-12-01

    Excess loading of phosphorus (P) and nitrogen (N) into aquatic systems leads to degradation of water quality and diminished important ecosystem services. In the Northern Gulf of Mexico (NGOM), excess P and N loading has led to a seasonally present hypoxic area with less than 2 mg/L O2 in bottom waters, approximating 26,000 km2 in 2017. A sequential extraction (SEDEX) method was performed on surficial sediments from five different coastal and shelf sites as a function of distance from the Mississippi River mouth in the NGOM. To better quantify temporal variability in P distribution and speciation, samples were collected during both low (August) and high (May) river flow regimes. Sequential extraction techniques have been successful in separating pools of P into exchangeable or loosely sorbed P, Fe-P, Authigenic-P, Detrital-P, and Organic-P. Preliminary results suggest Authigenic-P is approximately 3-6 times more concentrated in NGOM sediments than all other P pools. Fractionation results did not show a consistent trend with sediment depth. Sediment samples had an average moisture content of 58.72% ± 12.06% and an average bulk density of 0.582 ± 0.275 g/cm3. Continued analysis of P speciation and cycling in NGOM sediments is critical in understanding the driving force behind coastal eutrophication and informing effective nutrient management strategies.

  3. Spatial distribution and risk assessment of heavy metals in sediments of Shuangtaizi estuary, China

    International Nuclear Information System (INIS)

    Li, Chen; Song, Chengwen; Yin, Yanyan; Sun, Menghan; Tao, Ping; Shao, Mihua

    2015-01-01

    Highlights: • Five heavy metals are analyzed in the sediments from Shuangtaizi estuary. • Particle size of the sediment effects the concentration of heavy metals. • Pb, Cu, Zn and Hg pose low ecological risks in the Shuangtaizi estuary. • Heavy metal pollution in Shuangtaizi estuary is mainly dominated by Cd. - Abstract: In order to evaluate the spatial distribution and potential ecological risk of Pb, Cu, Zn, Cd, and Hg, the surface sediments were collected from 18 sites in the Shuangtaizi estuary. The concentrations of Pb, Cu, Zn, Cd, and Hg were analyzed by atomic absorption spectrophotometry and atomic fluorescence spectrometry after digestion. The particle sizes of the sediments were analyzed using a laser diffraction particle size analyzer. The results show that the heavy metal contents in the sediments are observed in the following order: Zn (18.25–126.75 mg/kg) > Pb (4.38–9.65 mg/kg) > Cu (1.80–17.68 mg/kg) > Cd (0.241–0.764 mg/kg) > Hg (0.007–0.021 mg/kg). In comparison with the concentrations of heavy metals in other regions, the concentrations of Pb, Cu, and Zn in the Shuangtaizi estuary are generally low, and the Cd concentrations are close to those reported in other regions. Both the potential ecological risk index and the geoaccumulation index reveal that the heavy metal pollution in Shuangtaizi estuary is mainly dominated by Cd

  4. Performance of intraclass correlation coefficient (ICC) as a reliability index under various distributions in scale reliability studies.

    Science.gov (United States)

    Mehta, Shraddha; Bastero-Caballero, Rowena F; Sun, Yijun; Zhu, Ray; Murphy, Diane K; Hardas, Bhushan; Koch, Gary

    2018-04-29

    Many published scale validation studies determine inter-rater reliability using the intra-class correlation coefficient (ICC). However, the use of this statistic must consider its advantages, limitations, and applicability. This paper evaluates how interaction of subject distribution, sample size, and levels of rater disagreement affects ICC and provides an approach for obtaining relevant ICC estimates under suboptimal conditions. Simulation results suggest that for a fixed number of subjects, ICC from the convex distribution is smaller than ICC for the uniform distribution, which in turn is smaller than ICC for the concave distribution. The variance component estimates also show that the dissimilarity of ICC among distributions is attributed to the study design (ie, distribution of subjects) component of subject variability and not the scale quality component of rater error variability. The dependency of ICC on the distribution of subjects makes it difficult to compare results across reliability studies. Hence, it is proposed that reliability studies should be designed using a uniform distribution of subjects because of the standardization it provides for representing objective disagreement. In the absence of uniform distribution, a sampling method is proposed to reduce the non-uniformity. In addition, as expected, high levels of disagreement result in low ICC, and when the type of distribution is fixed, any increase in the number of subjects beyond a moderately large specification such as n = 80 does not have a major impact on ICC. Copyright © 2018 John Wiley & Sons, Ltd.

  5. A visual basic program to generate sediment grain-size statistics and to extrapolate particle distributions

    Science.gov (United States)

    Poppe, L.J.; Eliason, A.H.; Hastings, M.E.

    2004-01-01

    Measures that describe and summarize sediment grain-size distributions are important to geologists because of the large amount of information contained in textural data sets. Statistical methods are usually employed to simplify the necessary comparisons among samples and quantify the observed differences. The two statistical methods most commonly used by sedimentologists to describe particle distributions are mathematical moments (Krumbein and Pettijohn, 1938) and inclusive graphics (Folk, 1974). The choice of which of these statistical measures to use is typically governed by the amount of data available (Royse, 1970). If the entire distribution is known, the method of moments may be used; if the next to last accumulated percent is greater than 95, inclusive graphics statistics can be generated. Unfortunately, earlier programs designed to describe sediment grain-size distributions statistically do not run in a Windows environment, do not allow extrapolation of the distribution's tails, or do not generate both moment and graphic statistics (Kane and Hubert, 1963; Collias et al., 1963; Schlee and Webster, 1967; Poppe et al., 2000)1.Owing to analytical limitations, electro-resistance multichannel particle-size analyzers, such as Coulter Counters, commonly truncate the tails of the fine-fraction part of grain-size distributions. These devices do not detect fine clay in the 0.6–0.1 μm range (part of the 11-phi and all of the 12-phi and 13-phi fractions). Although size analyses performed down to 0.6 μm microns are adequate for most freshwater and near shore marine sediments, samples from many deeper water marine environments (e.g. rise and abyssal plain) may contain significant material in the fine clay fraction, and these analyses benefit from extrapolation.The program (GSSTAT) described herein generates statistics to characterize sediment grain-size distributions and can extrapolate the fine-grained end of the particle distribution. It is written in Microsoft

  6. Spatial distributions and temporal trends in polybrominated diphenyl ethers in Detroit River suspended sediments.

    Science.gov (United States)

    Marvin, Chris; Waltho, Jasmine; Jia, Julia; Burniston, Debbie

    2013-05-01

    Suspended sediments from the Detroit River were collected using sediment traps at sites ranging from western Lake Erie to southern Lake St. Clair to assess spatial distributions and temporal trends of polybrominated diphenyl ethers (PBDEs). The distribution of PBDEs in suspended sediments in the Detroit River appeared influenced by shoreline-based contemporary urban and industrial activities, which stood in contrast to PCBs that were associated with areas of historic industrial activity. Temporal trend data indicate that total PBDE concentrations decreased in the period after 2000 in response to cessation of production of the penta- and octa BDE formulations. Concentrations of total PBDEs ranged from roughly 7 ng g(-1) (4 ng g(-1) BDE 209) in southern Lake St. Clair to several hundred ng g(-1) (60-180 ng g(-1) BDE 209) in the lower reaches of the Detroit River. The widespread occurrence of PBDEs in Detroit River suspended sediments suggests that large urban areas can act as diffuse sources of these chemicals that are used in modern industrial applications and consumer products. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  7. Predicting the distribution of bed material accumulation using river network sediment budgets

    Science.gov (United States)

    Wilkinson, Scott N.; Prosser, Ian P.; Hughes, Andrew O.

    2006-10-01

    Assessing the spatial distribution of bed material accumulation in river networks is important for determining the impacts of erosion on downstream channel form and habitat and for planning erosion and sediment management. A model that constructs spatially distributed budgets of bed material sediment is developed to predict the locations of accumulation following land use change. For each link in the river network, GIS algorithms are used to predict bed material supply from gullies, river banks, and upstream tributaries and to compare total supply with transport capacity. The model is tested in the 29,000 km2 Murrumbidgee River catchment in southeast Australia. It correctly predicts the presence or absence of accumulation in 71% of river links, which is significantly better performance than previous models, which do not account for spatial variability in sediment supply and transport capacity. Representing transient sediment storage is important for predicting smaller accumulations. Bed material accumulation is predicted in 25% of the river network, indicating its importance as an environmental problem in Australia.

  8. The Applicability of the Distribution Coefficient, KD, Based on Non-Aggregated Particulate Samples from Lakes with Low Suspended Solids Concentrations.

    Directory of Open Access Journals (Sweden)

    Aine Marie Gormley-Gallagher

    Full Text Available Separate phases of metal partitioning behaviour in freshwater lakes that receive varying degrees of atmospheric contamination and have low concentrations of suspended solids were investigated to determine the applicability of the distribution coefficient, KD. Concentrations of Pb, Ni, Co, Cu, Cd, Cr, Hg and Mn were determined using a combination of filtration methods, bulk sample collection and digestion and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS. Phytoplankton biomass, suspended solids concentrations and the organic content of the sediment were also analysed. By distinguishing between the phytoplankton and (inorganic lake sediment, transient variations in KD were observed. Suspended solids concentrations over the 6-month sampling campaign showed no correlation with the KD (n = 15 for each metal, p > 0.05 for Mn (r2 = 0.0063, Cu (r2 = 0.0002, Cr (r2 = 0.021, Ni (r2 = 0.0023, Cd (r2 = 0.00001, Co (r2 = 0.096, Hg (r2 = 0.116 or Pb (r2 = 0.164. The results implied that colloidal matter had less opportunity to increase the dissolved (filter passing fraction, which inhibited the spurious lowering of KD. The findings conform to the increasingly documented theory that the use of KD in modelling may mask true information on metal partitioning behaviour. The root mean square error of prediction between the directly measured total metal concentrations and those modelled based on the separate phase fractions were ± 3.40, 0.06, 0.02, 0.03, 0.44, 484.31, 80.97 and 0.1 μg/L for Pb, Cd, Mn, Cu, Hg, Ni, Cr and Co respectively. The magnitude of error suggests that the separate phase models for Mn and Cu can be used in distribution or partitioning models for these metals in lake water.

  9. Study of the mineralogic composition influence of the ground of Goiania, Brazil, in the distribution coefficient of the 137 Cs

    International Nuclear Information System (INIS)

    Anon

    2000-01-01

    Interactions between the soil and a solute in a liquid effluent depend on the characteristics of this solute as well as on the nature of the soil. The soil distribution coefficient K d in non altered natural systems can be estimated by the summation of the K d 's of its individual mineral components. In thesis this approach allows an evaluation of the distribution coefficient on the basis of the qualitative and quantitative identification of the mineral constituents of a given soil. This work reported here aimed at gathering preliminary data and at pointing the relevance of the approach in studies of radionuclide sorption by soils. A sample of the Goiania soil was collected and analyzed by X Ray diffractometry. The thus identified mineral components were subsequently submitted to individual batch tests, using 137 Cs as tracer. The mineral species tested were: kaolinite, gibbsite, goethite, hematite, muscovite, quartz and zirconite. The values obtained for K d are presented and discussed. (author)

  10. A microfluidic platform for the rapid determination of distribution coefficients by gravity assisted droplet-based liquid-liquid extraction

    DEFF Research Database (Denmark)

    Poulsen, Carl Esben; Wootton, Robert C. R.; Wolff, Anders

    2015-01-01

    The determination of pharmacokinetic properties of drugs, such as the distribution coefficient, D, is a crucial measurement in pharmaceutical research. Surprisingly, the conventional (gold standard) technique used for D measurements, the shake-flask method, is antiquated and unsuitable...... for the testing of valuable and scarce drug candidates. Herein we present a simple micro fluidic platform for the determination of distribution coefficients using droplet-based liquid-liquid extraction. For simplicity, this platform makes use of gravity to enable phase separation for analysis and is 48 times...... the apparent acid dissociation constant, pK', as a proxy for inter-system comparison. Our platform determines a pK' value of 7.24 ± 0.15, compared to 7.25 ± 0.58 for the shake-flask method in our hands and 7.21 for the shake-flask method in literature. Devices are fabricated using injection moulding, the batch...

  11. Angular distribution coefficients for γ-ray polarization produced in polarized capture reactions

    International Nuclear Information System (INIS)

    Wulf, E.A.; Guillemette, J.; Weller, H.R.; Seyler, R.G.

    1999-01-01

    The previous publications have dealt with the angular momentum formalism of both linear and circularly polarized photons in (γ, x) reactions on both polarized and unpolarized targets, and the inverse (capture) reactions initiated by polarized beams. In the present work, utilizing the general formalism of Welton, the authors deal with the linear polarization of the γ-rays which are produced in capture reactions on unpolarized targets, including the possibility of having incident polarized spin 1/2 projectiles. These capture reactions are denoted by a(rvec x, rvec L)c, where rvec x is the incident polarized spin 1/2 projectile and rvec L represents the outgoing polarized γ-ray. They present here the formalism in a convenient form, display a sample table of coefficients, and illustrate its use by means of several examples. A FORTRAN code will be made available for generating similar coefficients for other reactions

  12. Distribution coefficients for 85Sr and 137Cs in Japanese agricultural soils and their correlations with soil properties

    International Nuclear Information System (INIS)

    Kamei-Ishikawa, N.; Uchida, S.; Tagami, K.

    2008-01-01

    In this work, soil-soil solution distribution coefficients (K d ) of Sr and Cs were obtained for 112 Japanese agricultural soil samples (50 paddy soil and 62 upland soil samples) using batch sorption test. The relationships between Sr- or Cs-K d values and soil properties were discussed. Furthermore, the amount of Cs fixed in soil was estimated for 22 selected soil samples using a sequential extraction method. Then, cross effects of some soil properties for Cs fixation were evaluated. (author)

  13. Distribution of stress in greenhouses frames estimated by aerodynamic coefficients of Brazilian and European standards

    Directory of Open Access Journals (Sweden)

    José Gabriel Vieira Neto

    2016-04-01

    Full Text Available ABSTRACT Widely disseminated in both national and international scenarios, greenhouses are agribusiness solutions which are designed to allow for greater efficiency and control of the cultivation of plants. Bearing this in mind, the construction of greenhouses should take into consideration the incidence of wind, and other such aspects of comfort and safety, and ensure they are factored into the design of structural elements. In this study, we evaluated the effects of pressure coefficients established by the European standard EN 13031-1 (2001 and the Brazilian standard ABNT (1988, which are applicable to the structures of greenhouses with flat roofs, taking into account the following variables: roof slope, external and internal pressure coefficients and height-span ratio of the structure. Using the ANSYSTM computer program, zones of columns and roof were discretized by the Beam44 finite element to identify the maximum and minimum stress portions connected to the aerodynamic coefficients. With this analysis, we found that, in the smallest roof slope (a equal to 20°, the frame stress was quite similar for standards adopted. On the other hand, for the greatest inclination (a equal to 26°, the stress was consistently lower under the Brazilian standard. In view of this, we came to the conclusion that the differences between stresses when applying both standards were more significant at the higher degrees of height-span ratio and roof slope.

  14. Caesium-137 distribution, inventories and accumulation history in the Baltic Sea sediments

    International Nuclear Information System (INIS)

    Zaborska, Agata; Winogradow, Aleksandra; Pempkowiak, Janusz

    2014-01-01

    The Baltic Sea is susceptible to pollution by hazardous substances due to limited water exchange, shallowness, and the large catchment area. Radionuclides, particularly 137 Cs, are one of the most hazardous anthropogenic substances present in the Baltic environment. This study was conducted to present 137 Cs present contamination that should further be a subject of reliable monitoring when the new Nuclear Power Plant is put into operation in the northern Poland. The sea-wide, up to date distribution of 137 Cs activities and inventories in the Baltic Sea bottom sediments are presented. The 137 Cs activity concentrations were measured in 30 cm long sediment cores collected at 22 sampling stations. Sediment accumulation rates were quantified by 210 Pb geochronology to follow the history of 137 Cs accumulation. The 137 Cs inventories and fluxes were calculated. Most of the Baltic Sea sediments accumulated 137 Cs in the range from 750 to 2675 Bq m −2 . The Bothnian Bay is severely contaminated by 137 Cs with inventories up to 95,191 Bq m −2 . This region is moreover characterized by extremely large patchiness of 137 Cs inventories. The 137 Cs annual fluxes are highest at the two stations located at the Bothnian Bay (342 Bq m −2 and 527 Bq m −2 ) due to large Chernobyl 137 Cs contamination of that region and high sediment accumulation rates. When these stations are excluded, the recent, annual mean value of 137 Cs load to the Baltic Sea deposits is 38 ± 22 Bq m −2 . The distribution of radio-caesium inventories over the Baltic Sea nowadays reflects the pattern of Chernobyl contamination. The radio-caesium deposited in surface sediments is not permanently buried, but may be resuspended and redeposited by currents, bioturbation or anthropogenic activities. -- Highlights: • 137 Cs contamination in the Baltic Sea was studied before the new NPP is put into operation. • Bothnian Sea sediments are severely contaminated by 137 Cs (inventories up to 95,191 Bq m

  15. Temporal and spatial distributions of contaminants in sediments of Santa Monica Bay, California

    Science.gov (United States)

    Bay, S.M.; Zeng, E.Y.; Lorenson, T.D.; Tran, K.; Alexander, Corrine

    2003-01-01

    Contaminant inputs from wastewater discharge, a major source of contamination to Santa Monica Bay (SMB), have declined drastically during the last three decades as a result of improved treatment processes and better source control. To assess the concomitant temporal changes in the SMB sediments, a study was initiated in June 1997, in which 25 box cores were collected using a stratified random sampling design. Five sediment strata corresponding to the time intervals of 1890-1920, 1932-1963, 1965-1979, 1979-1989, and 1989-1997 were identified using 210Pb dating techniques. Samples from each stratum were analyzed for metals, 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites (DDTs), polychlorinated biphenyls (PCBs), and total organic carbon (TOC). Samples from the 1965-1979, 1979-1989, and 1989-1997 strata were also analyzed for polycyclic aromatic hydrocarbons (PAHs) and linear alkylbenzenes (LABs). Sediment metal concentrations increased from 1890-1979 and were similar during the time intervals of 1965-1979, 1979-1989, and 1989-1997, although the mass emissions of trace metals from sewage inputs declined substantially during the same time period. Trace organic contamination in SMB was generally highest in sediments corresponding to deposition during the years of 1965-1979 or 1979-1989 and showed a decline in concentration in the 1989-1997 stratum. Temporal trends of contamination were greatest in sediments collected from areas near the Hyperion Treatment Plant (HTP) outfall system and on the slope of Redondo Canyon. The highest contaminant concentrations were present in sediments near the HTP 7-mile outfall in the 1965-1979 stratum. Elevated trace metal and organic concentrations were still present in the 1989-1997 stratum of most stations, suggesting that sediment contaminants have moved vertically in the sediment column since sludge discharges from the 7-mile outfall (a dominant source of contamination to the bay) ceased in 1987. The

  16. Experimental determination of the distribution coefficient (Kd) of lead and barium in soils of semiarid region of Bahia, Brazil

    International Nuclear Information System (INIS)

    Santos, Mariana M.; Fernandes, Heloisa H.F; Pontedeiro, Elizabeth M.; Su, Jian

    2013-01-01

    To determine the concentration of heavy metals and other contaminants in soils, aimed at evaluating the environmental impact, the use of the distribution coefficient is required (Kd), defined as the relationship between the concentrations adsorbed and in solution. The objective of this study was to determine the rates for the Lead and Barium metals in soil collected in Caetite, the state of Bahia, in two different depths. The importance of determining the distribution coefficient lies in the fact that being performed using a tropical soil. For the isotherms of Kd was used batch test method by adsorption to obtain the final concentrations. The first step was to determine the best ratio soil: solution obtained after equilibration time and finally the equilibrium concentration of the contaminant. Were also calculated percentages of the metal adsorbed by the soil and the amount of solute by the adsorbent. With the values obtained in experiments and using Mathematica 8.0 software, were made graphics equilibrium concentration versus quantity adsorbed (C vs. S). It can also plot isotherms for different models of Kd: linear, Langmuir and Freundlich in order to determine which adsorption model would fit best to the measured data and thus determine the distribution coefficient of the metal in the soil analyzed. The Freundlich isotherm was better adapted to the points of the two metals in both soils

  17. Measurement of aerosol size distribution by impaction and sedimentation An experimental study and data reduction

    International Nuclear Information System (INIS)

    Diouri, Mohamed.

    1981-09-01

    This study concerns essentially solid aerosols produced by combustion and more particulary the aerosol liberated by a sodium fire taken into account in safety studies related to sodium cooled nuclear reactors. The accurate determination of the aerosol size distribution depends on the selection device use. An experimental study of the parameters affecting the solid aerosol collection efficiency was made with the Andersen Mark II cascade impactor (blow off and bounce, electrical charge of particles, wall-loss). A sedimentation chamber was built and calibrated for the range between 4 and 10 μm. The second part describes a comparative study of different data reduction methods for the impactor and a new method for setting up the aerosol size distribution with data obtained by the sedimentation chamber [fr

  18. Distribution and origin of hydrocarbons in water and sediment in Sao Sebastiao, SP, Brazil

    International Nuclear Information System (INIS)

    Zanardi, Eliete; Bicego, Marcia Caruso; Miranda, Luiz Bruner de; Weber, Rolf Roland

    1999-01-01

    This study describes the dissolved/dispersed petroleum hydrocarbons (DDPH) in surface water and the origin and distribution of aliphatic and aromatic hydrocarbons in samples from the surface bottom sediments. The main objective was to verify the anthropogenic contribution on the adjacent inner shelf of Sao Sebastiao, taking into account the distribution of hydrographic properties and knowledge of the main circulation. The DDPH concentration range of the 20 samples were from 0.35 to 2.50 m u g . L -1 , characterising this region as slightly affected by the contribution of petroleum hydrocarbons. Considering sediment hydrocarbon results, sites located in the inner shelf were divided into three groups: one with mainly biogenic hydrocarbons, a second one with biogenic and petroleum hydrocarbons and a third with significant contribution of petroleum hydrocarbons. These results show an influence of human activities in the Sao Sebastiao Channel on the surrounding areas of the inner shelf. (Author)

  19. Distribution and origin of hydrocarbons in water and sediment in Sao Sebastiao, SP, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Zanardi, Eliete [Universidade de Sao Paulo, Instituto Oceanografico, Sao Paulo, SP (Brazil); Bicego, Marcia Caruso; Miranda, Luiz Bruner de; Weber, Rolf Roland [Miami Univ., RSMAS/NAC, Miami, FL (United States)

    1999-04-01

    This study describes the dissolved/dispersed petroleum hydrocarbons (DDPH) in surface water and the origin and distribution of aliphatic and aromatic hydrocarbons in samples from the surface bottom sediments. The main objective was to verify the anthropogenic contribution on the adjacent inner shelf of Sao Sebastiao, taking into account the distribution of hydrographic properties and knowledge of the main circulation. The DDPH concentration range of the 20 samples were from 0.35 to 2.50 {sup m}u{sup g}. L{sup -1}, characterising this region as slightly affected by the contribution of petroleum hydrocarbons. Considering sediment hydrocarbon results, sites located in the inner shelf were divided into three groups: one with mainly biogenic hydrocarbons, a second one with biogenic and petroleum hydrocarbons and a third with significant contribution of petroleum hydrocarbons. These results show an influence of human activities in the Sao Sebastiao Channel on the surrounding areas of the inner shelf. (Author)

  20. Distribution of trace elements in sediment and soil from river Vardar Basin, Macedonia/Greece.

    Science.gov (United States)

    Popov, Stanko Ilić; Stafilov, Trajče; Šajn, Robert; Tănăselia, Claudiu

    2016-01-01

    A systematic study was carried out to investigate the distribution of 59 elements in the sediment and soil samples collected from the river Vardar (Republic of Macedonia and Greece) and its major tributaries. The samples were collected from 28 sampling sites. Analyses were performed by inductively coupled plasma-mass spectrometry. R-mode factor analysis (FA) was used to identify and characterise element associations. Seven associations of elements were determined by the method of multivariate statistics. Every factor (Factors 1-3 and 6 and 7 as geogenic and Factors 4 and 5 as anthropogenic associations of elements) are examined and explained separately. The distribution of various elements showed that there is a presence of anthropogenic elements (Ag, Cd, Cu, Ge, Pb, Sn and Zn) introduced in the river sediments and soils from the mining, metallurgical, industrial and agricultural activities in Vardar River Basin, which covers most of the Republic of Macedonia and Central-northern part of Greece.

  1. Spatial and historical distribution of organic phosphorus driven by environment conditions in lake sediments.

    Science.gov (United States)

    Lü, Changwei; He, Jiang; Wang, Bing

    2018-02-01

    The chemistry of sedimentary organic phosphorus (OP) and its fraction distribution in sediments are greatly influenced by environmental conditions such as terrestrial inputs and runoffs. The linkage of OP with environmental conditions was analyzed on the basis of OP spatial and historical distributions in lake sediments. The redundancy analysis and OP spatial distribution results suggested that both NaOH-OP (OP extracted by NaOH) and Re-OP (residual OP) in surface sediments from the selected 13 lakes reflected the gradient effects of environmental conditions and the autochthonous and/or allochthonous inputs driven by latitude zonality in China. The lake level and salinity of Lake Hulun and the runoff and precipitation of its drainage basin were reconstructed on the basis of the geochemistry index. This work showed that a gradient in weather conditions presented by the latitude zonality in China impacts the OP accumulation through multiple drivers and in many ways. The drivers are mainly precipitation and temperature, governing organic matter (OM) production, degradation rate and transportation in the watershed. Over a long temporal dimension (4000years), the vertical distributions of Re-OP and NaOH-OP based on a dated sediment profile from HLH were largely regulated by the autochthonous and/or allochthonous inputs, which depended on the environmental and climate conditions and anthropogenic activities in the drainage basin. This work provides useful environmental geochemistry information to understand the inherent linkage of OP fractionation with environmental conditions and lake evolution. Copyright © 2017. Published by Elsevier B.V.

  2. Vertical distributions of PAHs in the sediments of four lakes in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Fukushima, Takehiko; Watanabe, Seigo; Kamiya, Koichi [Tsukuba Univ., Ibaraki (Japan). Graduate School of Life and Environment; Ozaki, Noriatsu [Hiroshima Univ., Higashihiroshima (Japan). Graduate School of Engineering

    2012-12-15

    Purpose: The purpose of this study was to elucidate historical trends, spatial variations, and the sources of polycyclic aromatic hydrocarbons (PAHs) pollution in several Japanese lakes. Materials and methods: The vertical distributions of PAHs in the core samples of sediments taken at several points in lakes Kasumigaura, Suwa, Kizaki, and Shinji were determined using a gas chromatograph equipped with a mass selective detector and combined with chronological information and the physical/elemental properties of the sediment. Results and discussion: Seventeen related compounds (congeners) typically had concentration peaks at sediment depths corresponding to the 1960s to 1970s. In Lake Shinji and one bay of Lake Kasumigaura, there was a tendency for PAH concentrations to increase downstream; in contrast, another bay of Lake Kasumigaura showed the reverse trend. During big flood events, the fluxes of PAHs increased due to large inputs of particulate matter, although PAH concentrations were reduced. For the four study lakes and other similar lakes, PAH concentrations of surface sediments were approximately proportional to population densities in the respective watersheds, while the total input of PAHs to the lakes were correlated with their population and watershed area. The source apportionment analysis using isomer ratios for the congener profiles indicated that the principal sources of the PAHs in the lake sediments were gasoline and/or diesel engine exhausts and biomass burning. Conclusions: The observed concentration peaks showed a deterioration of the chemical quality of atmospheric conditions around 1960-1970 and a recent tendency for their amelioration. Between-lake differences suggest that the influence of human activity in the watersheds influences sediment PAH concentrations. The PAH sources were identified to be of pyrogenic origin. (orig.)

  3. Spatiotemporal distributions of Fukushima-derived radionuclides in nearby marine surface sediments

    Energy Technology Data Exchange (ETDEWEB)

    Kusakabe, M.; Oikawa, S.; Takata, H.; Misonoo, J. [Marine Ecology Research Institute, Tokyo (Japan)

    2013-07-01

    Spatiotemporal distributions of anthropogenic radionuclides in marine surface sediments off Miyagi, Fukushima, and Ibaraki Prefectures were analyzed on the basis of data collected during the monitoring program launched by the Japanese Ministry of Education, Sports, Science and Technology in 2011 right after the Fukushima Dai-ichi Nuclear Power Plant accident began. Concentrations of {sup 137}Cs in the surface sediments varied spatially by two orders of magnitude, from 1.7 to 580 Bq kg-dry{sup -1}, and there was no obvious correlation between {sup 137}Cs concentration and the proximity of the sampling location to the accident site. The total inventory of {sup 137}Cs accumulated in the upper 3 cm of surface sediments in the monitoring area was estimated to be 3.78 x 10{sup 13} Bq, that is, 0.1-2% of the total {sup 137}Cs flux from the plant to the ocean as a result of the accident (the percentage depends on the model used to estimate the total flux). The spatial variations of {sup 137}Cs concentration and inventory depended on two main factors: the {sup 137}Cs concentration in the overlying water during the first several months after the accident and the physical characteristics of the sediments (water content and bulk density). The temporal variations of the concentrations of other anthropogenic radionuclides ({sup 90}Sr, {sup 95}Nb, {sup 110} {sup m}Ag, {sup 125}Sb, {sup 129}Te, and {sup 129} {sup m}Te) in the sediments were also investigated. Activity ratios of these nuclides to {sup 137}Cs suggest that the nuclides themselves were not homogenized before they were removed from seawater to the sediments.

  4. Distribution coefficients (Kd's) for use in risk assessment models of the Kara Sea.

    Science.gov (United States)

    Carroll, J; Boisson, F; Teyssie, J L; King, S E; Krosshavn, M; Carroll, M L; Fowler, S W; Povinec, P P; Baxter, M S

    1999-07-01

    As a prerequisite for most evaluations of radionuclide transport pathways in marine systems, it is necessary to obtain basic information on the sorption potential of contaminants onto particulate matter. Kd values for use in modeling radionuclide dispersion in the Kara Sea have been determined as part of several international programs addressing the problem of radioactive debris residing in Arctic Seas. Field and laboratory Kd experiments were conducted for the following radionuclides associated with nuclear waste: americium, europium, plutonium, cobalt, cesium and strontium. Emphasis has been placed on two regions in the Kara Sea: (i) the Novaya Zemlya Trough (NZT) and (ii) the mixing zones of the Ob and Yenisey Rivers (RMZ). Short-term batch Kd experiments were performed at-sea on ambient water column samples and on samples prepared both at-sea and in the laboratory by mixing filtered bottom water with small amounts of surficial bottom sediments (particle concentrations in samples = 1-30 mg/l). Within both regions, Kd values for individual radionuclides vary over two to three orders of magnitude. The relative particle affinities for radionuclides in the two regions are americium approximately equal to europium > plutonium > cobalt > cesium > strontium. The values determined in this study agree with minimum values given in the IAEA Technical Report [IAEA, 1985. Sediment Kd's and Concentration Factors for Radionuclides in the Marine Environment. Technical Report No. 247. International Atomic Energy Agency, Vienna.]. Given the importance of Kd's in assessments of critical transport pathways for radionuclide contaminants, we recommend that Kd ranges of values for specific elements rather than single mean values be incorporated into model simulations of radionuclide dispersion.

  5. Maximal planar networks with large clustering coefficient and power-law degree distribution

    International Nuclear Information System (INIS)

    Zhou Tao; Yan Gang; Wang Binghong

    2005-01-01

    In this article, we propose a simple rule that generates scale-free networks with very large clustering coefficient and very small average distance. These networks are called random Apollonian networks (RANs) as they can be considered as a variation of Apollonian networks. We obtain the analytic results of power-law exponent γ=3 and clustering coefficient C=(46/3)-36 ln (3/2)≅0.74, which agree with the simulation results very well. We prove that the increasing tendency of average distance of RANs is a little slower than the logarithm of the number of nodes in RANs. Since most real-life networks are both scale-free and small-world networks, RANs may perform well in mimicking the reality. The RANs possess hierarchical structure as C(k)∼k -1 that are in accord with the observations of many real-life networks. In addition, we prove that RANs are maximal planar networks, which are of particular practicability for layout of printed circuits and so on. The percolation and epidemic spreading process are also studied and the comparisons between RANs and Barabasi-Albert (BA) as well as Newman-Watts (NW) networks are shown. We find that, when the network order N (the total number of nodes) is relatively small (as N∼10 4 ), the performance of RANs under intentional attack is not sensitive to N, while that of BA networks is much affected by N. And the diseases spread slower in RANs than BA networks in the early stage of the suseptible-infected process, indicating that the large clustering coefficient may slow the spreading velocity, especially in the outbreaks

  6. Sediment Sources and Transport Pathway Identification Based on Grain-Size Distributions on the SW Coast of Portugal

    Directory of Open Access Journals (Sweden)

    Xiaoqin Du

    2015-01-01

    Full Text Available Espichel-Sines is an embayed coast in SW Portugal, consisting of two capes at both extremities, a tidal inlet and associated ebb tidal delta, a barrier spit, sandy beaches, sea cliffs, and a submarine canyon. Beach berm, backshore, near shore and inner shelf sediment samples were taken. Samples were analyzed for their grain-size compositions. This study ranks the hypothetical sediment sources influences on the sediment distributions in the study area using the multivariate Empirical Orthogonal Function (EOF techniques. Transport pathways in this study were independently identified using the grain size trend analysis (GSTA technique to verify the EOF findings. The results show that the cliff-erosion sediment is composed of pebbles and sand and is the most important sediment source for the entire embayment. The sediment at the inlet mouth is a mixture of pebbles, sand, silt, and clay, which is a minor sediment source that only has local influence. The overall grain-size distributions on the shelf are dominated by the sand except for the high mud content around the tidal delta front in the northern embayment. Sediment transport patterns on the inner shelf at the landward and north sides of the canyon head are landward and northward along the barrier spit, respectively. On the south side of the canyon head, the prevailing sediment transport is seaward. Sediment transport occurs in both directions along the shore.

  7. Local controls on sediment accumulation and distribution in a fjord in the West Antarctic Peninsula: implications for palaeoenvironmental interpretations

    Directory of Open Access Journals (Sweden)

    Yuribia P. Munoz

    2016-08-01

    Full Text Available We analyse surface sediment and its distribution in Flandres Bay, West Antarctic Peninsula, in order to understand modern day sediment dispersal patterns in a fjord with retreating, tidewater glaciers. The surface sediment descriptions of 41 cores are included in this study. The sediment facies described include muddy diatomaceous ooze, diatomaceous mud, pebbly mud, sandy mud and mud, with scattered pebbles present in most samples. In contrast to a traditional conceptual model of glacial sediment distribution in fjords, grain size in Flandres Bay generally coarsens from the inner to outer bay. The smallest grain size sediments were found in the bay head and are interpreted as fine-grained deposits resulting from meltwater plumes and sediment gravity flows occurring close to the glacier front. The middle of the bay is characterized by a high silt percentage, which correlates to diatom-rich sediments. Sediments in the outer bay have a high component of coarse material, which is interpreted as being the result of winnowing from currents moving from the Bellingshausen Sea into the Gerlache Strait. Palaeoenvironmental reconstructions of glacial environments often use grain size as an indicator of proximity to the ice margin. After a detailed analysis of a large number of cores collected in the study area, our findings highlight the variability in sedimentation patterns within a fjord and provide a valuable evidence of the complexity that may occur in the sedimentary record.

  8. Biogeographical distribution and diversity of bacterial communities in surface sediments of the South China Sea.

    Science.gov (United States)

    Li, Tao; Wang, Peng

    2013-05-01

    This paper aims at an investigation of the features of bacterial communities in surface sediments of the South China Sea (SCS). In particular, biogeographical distribution patterns and the phylogenetic diversity of bacteria found in sediments collected from a coral reef platform, a continental slope, and a deep-sea basin were determined. Bacterial diversity was measured by an observation of 16S rRNA genes, and 18 phylogenetic groups were identified in the bacterial clone library. Planctomycetes, Deltaproteobacteria, candidate division OP11, and Alphaproteobacteria made up the majority of the bacteria in the samples, with their mean bacterial clones being 16%, 15%, 12%, and 9%, respectively. By comparison, the bacterial communities found in the SCS surface sediments were significantly different from other previously observed deep-sea bacterial communities. This research also emphasizes the fact that geographical factors have an impact on the biogeographical distribution patterns of bacterial communities. For instance, canonical correspondence analyses illustrated that the percentage of sand weight and water depth are important factors affecting the bacterial community composition. Therefore, this study highlights the importance of adequately determining the relationship between geographical factors and the distribution of bacteria in the world's seas and oceans.

  9. Seasonal and spatial distributions of tributyltin in surface sediment of the Tolka Estuary, Dublin, Ireland

    International Nuclear Information System (INIS)

    Buggy, Conor J.; Tobin, John M.

    2006-01-01

    Aquatic pollution by tributyltin (TBT) is of concern because of its high toxicity to marine life. TBT loadings of estuarine sediments may remain elevated because of long flushing times in estuaries due to their enclosed physicality. The Tolka Estuary, Co. Dublin, Ireland, is a typical Irish urban estuary. It has a significant pollution loading. The results of 12 months' analysis of TBT spatial and temporal distributions in this estuary are presented in this paper. Data from a total of 10 sample points are presented. The concentrations of TBT in the sediment were analysed using differential pulse polarography. Significant seasonal and spatial trends in TBT distribution were observed over the 12-month period. TBT concentrations ranged from 0.1 ppb in winter to 8.6 ppb in summer with a 1.5 ppb average. Organic matter (OM) concentrations of sediment exhibited similar seasonal trends and a positive correlation between OM and TBT distributions was observed. - TBT concentrations varied with seasons and correlated well with organic matter

  10. Seasonal and spatial distributions of tributyltin in surface sediment of the Tolka Estuary, Dublin, Ireland

    Energy Technology Data Exchange (ETDEWEB)

    Buggy, Conor J. [Department of Biotechnology, Dublin City University, Glasnevin, Dublin (Ireland); Tobin, John M. [Department of Biotechnology, Dublin City University, Glasnevin, Dublin (Ireland)]. E-mail: john.tobin@dcu.ie

    2006-09-15

    Aquatic pollution by tributyltin (TBT) is of concern because of its high toxicity to marine life. TBT loadings of estuarine sediments may remain elevated because of long flushing times in estuaries due to their enclosed physicality. The Tolka Estuary, Co. Dublin, Ireland, is a typical Irish urban estuary. It has a significant pollution loading. The results of 12 months' analysis of TBT spatial and temporal distributions in this estuary are presented in this paper. Data from a total of 10 sample points are presented. The concentrations of TBT in the sediment were analysed using differential pulse polarography. Significant seasonal and spatial trends in TBT distribution were observed over the 12-month period. TBT concentrations ranged from 0.1 ppb in winter to 8.6 ppb in summer with a 1.5 ppb average. Organic matter (OM) concentrations of sediment exhibited similar seasonal trends and a positive correlation between OM and TBT distributions was observed. - TBT concentrations varied with seasons and correlated well with organic matter.

  11. Major and trace element distribution in soil and sediments from the Egyptian central Nile Valley

    Science.gov (United States)

    Badawy, W. M.; Ghanim, E. H.; Duliu, O. G.; El Samman, H.; Frontasyeva, M. V.

    2017-07-01

    The distributions of 32 major and trace elements in 72 surface soil and sediment samples collected from the Asyut to Cairo Nile river section were determined by epithermal neutron activation analysis and compared with corresponding data for the Upper Continental Crust, North American Shale Composite, Average Soil and Average Sediment as well as suspended sediments from Congo and Upper Niger Rivers, in order to establish to which extent the Nile sedimentary material can be related to similar material all over the world as well as to local geology. Their relative distributions indicate the presence of detrital material of igneous origin, most probably resulting from weathering of the Ethiopian Highlands and transported by the Blue Nile, the Nile main tributary. The distributions of nickel, zinc, and arsenic contents suggest that the lower part of the Nile and its surroundings including the Nile Delta is not seriously polluted with heavy metals, so that, in spite of a human activity, which lasted four millennia, the Nile River continues to be less affected by any anthropogenic contamination.

  12. Abundance and distribution of microplastics within surface sediments of a key shellfish growing region of Canada.

    Science.gov (United States)

    Kazmiruk, T N; Kazmiruk, V D; Bendell, L I

    2018-01-01

    The abundance and distribution of microplastics within 5 sediment size classes (>5000 μm, 1000-5000 μm, 250-1000 μm, 250-0.63 μm and Microplastics were found at all sampling locations indicating widespread contamination of this region with these particles. Three types of microplastics were recovered: microbeads, which occurred in the greatest number (up to 25000/kg dry sediment) and microfibers and microfragments, which were much less in number compared with microbeads and occurred in similar amounts (100-300/kg dry sediment). Microbeads were recovered primarily in the microplastics were spatially dependent with principal component analysis (PCA) indicating that 84 percent of the variation in abundance and distribution was due to the presence of high numbers of microbeads at three locations within the study region. At these sites, microbeads expressed as a percent component of the sediment by weight was similar to key geochemical components that govern trace metal behavior and availability to benthic organisms. Microbeads have been shown to accumulate metals from the aquatic environment, hence in addition to the traditional geochemical components such as silt and organic matter, microplastics also need to be considered as a sediment component that can influence trace metal geochemistry. Our findings have shown that BC's premier oyster growing region is highly contaminated with microplastics, notably microbeads. It would be prudent to assess the degree to which oysters from this region are ingesting microplastics. If so, it would have direct implications for Canada's oyster farming industry with respect to the health of the oyster and the quality of product that is being farmed and sets an example for other shellfish growing regions of the world.

  13. Distribution and contamination status of chromium in surface sediments of northern Kaohsiung Harbor, Taiwan.

    Science.gov (United States)

    Dong, Cheng-Di; Chen, Chiu-Wen; Chen, Chih-Feng

    2013-07-01

    The distribution, enrichment, accumulation, and potential ecological risk of chromium (Cr) in the surface sediments of northern Kaohsiung Harbor, Taiwan, China were investigated. Sediment samples from ten locations located between the river mouths and harbor entrance of northern Kaohsiung Harbor were collected quarterly in 2011 and characterized for Cr, aluminum, water content, organic matter, total nitrogen, total phosphorous, total grease, and grain size. Results showed that the Cr concentrations varied from 27.0 to 361.9 mg/kg with an average of (113.5 +/- 87.0) mg/kg. High Cr concentration was observed near the Jen-Gen River mouth. The mean Cr concentration was high at 255.5 mg/kg, which was at least 2 to 7 times than that of other sites. This might imply significant Cr contribution from upstream receiving tanneries wastewater into the Jen-Gen River. The spatial distribution of Cr reveals relatively high in the river mouth region, especially in Jen-Gen River, and gradually diminishes toward the harbor entrance region. This indicates that the major sources of Cr pollution from upstream industrial and municipal wastewaters discharged along the river bank; and Cr may drift with sea current and be dispersed into open sea. Moreover, Cr concentrations correlated closely to the physical-chemical properties of the sediments, which suggested the influence of industrial and municipal wastewaters discharged from the neighboring industrial parks and river basins. Results from the enrichment factor and geo-accumulation index analyses imply that the Jen-Gen River sediments can be characterized as moderate enrichment and none to medium accumulation of Cr, respectively. However, results of potential ecological risk index indicate that the sediment has low ecological potential risk. The results can provide valuable information to developing future strategies for the management of river mouth and harbor.

  14. Colocalization coefficients evaluating the distribution of molecular targets in microscopy methods based on pointed patterns

    Czech Academy of Sciences Publication Activity Database

    Pastorek, Lukáš; Sobol, Margaryta; Hozák, Pavel

    2016-01-01

    Roč. 146, č. 4 (2016), s. 391-406 ISSN 0948-6143 R&D Projects: GA TA ČR(CZ) TE01020118; GA ČR GA15-08738S; GA MŠk(CZ) ED1.1.00/02.0109; GA MŠk(CZ) LM2015062 Grant - others:Human Frontier Science Program(FR) RGP0017/2013 Institutional support: RVO:68378050 Keywords : Colocalization * Quantitative analysis * Pointed patterns * Transmission electron microscopy * Manders' coefficients * Immunohistochemistry Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.553, year: 2016

  15. A Bayesian Framework for Estimating the Concordance Correlation Coefficient Using Skew-elliptical Distributions.

    Science.gov (United States)

    Feng, Dai; Baumgartner, Richard; Svetnik, Vladimir

    2018-04-05

    The concordance correlation coefficient (CCC) is a widely used scaled index in the study of agreement. In this article, we propose estimating the CCC by a unified Bayesian framework that can (1) accommodate symmetric or asymmetric and light- or heavy-tailed data; (2) select model from several candidates; and (3) address other issues frequently encountered in practice such as confounding covariates and missing data. The performance of the proposal was studied and demonstrated using simulated as well as real-life biomarker data from a clinical study of an insomnia drug. The implementation of the proposal is accessible through a package in the Comprehensive R Archive Network.

  16. Environmental controls on the speciation and distribution of mercury in surface sediments of a tropical estuary, India

    International Nuclear Information System (INIS)

    Chakraborty, Parthasarathi; Babu, P.V. Raghunadh

    2015-01-01

    Highlights: • Physico-chemical parameters of water column control Hg speciation in sediments. • Sediments from the middle of the estuary were contaminated by Hg. • Concentrations of Hg were less during the monsoon and post monsoon period. • Salinity, pH of water column may change Hg speciation of the bottom sediments. • TOC in sediments control Hg partitioning in the system. - Abstract: Distribution and speciation of mercury (Hg) in the sediments from a tropical estuary (Godavari estuary) was influenced by the changing physico-chemical parameters of the overlying water column. The sediments from the upstream and downstream of the estuary were uncontaminated but the sediments from the middle of the estuary were contaminated by Hg. The concentrations of Hg became considerably less during the monsoon and post monsoon period. Total Hg concentrations and its speciation (at the middle of the estuary) were dependent on the salinity of the overlying water column. However, salinity had little or no effect on Hg association with organic phases in the sediments at downstream. Increasing pH of the overlying water column corresponded with an increase in the total Hg content in the sediments. Total organic carbon in the sediments played an important role in controlling Hg partitioning in the system. Uncomplexed Hg binding ligands were available in the sediments

  17. Comparison of phosphorus fraction distribution and influencing factors of suspended and surface sediments in the Tiaoxi watershed, China.

    Science.gov (United States)

    Ye, Hongmeng; Yuan, Xuyin; Han, Lei; Yin, Heng; Jin, Jing

    2017-05-01

    Suspended and surface sediments from the Tiaoxi watershed, fed by the Xitiaoxi and Dongtiaoxi rivers, were analyzed for total phosphorus (TP) and the inorganic P fractions of loosely adsorbed P that were extractable with NH 4 Cl (NH 4 Cl-P), reductant P (BD-P), metal oxide-bound P extractable with NaOH (NaOH-P), and calcium-bound, HCl-extractable P (HCl-P), while other physicochemical compositions were also determined. The spatial variations of P fractions in these sediments were investigated, and the major factors influencing the various fractions were explored by multivariate statistics. Compared to surface sediments, suspended sediments contained considerably higher concentrations of total nitrogen, TP, organic matter, Al, Fe, Mn and biologically available P (BAP, given as NH 4 Cl-P, BD-P and NaOH-P combined) and lower concentrations of Si, Ca and HCl-P in the studied catchments. Dongtiaoxi sediments had higher TP, inorganic phosphorus and HCl-P concentrations and a lower BAP content compared with Xitiaoxi sediments, trends that were associated with local geological backgrounds, landscapes and anthropogenic characteristics. The results of principal component analysis showed different effects of sediment properties on P fraction distributions for Xitiaoxi and Dongtiaoxi sediments. The sediment components and structure exert a strong influence on BAP in Xitiaoxi sediments, in contrast to Dongtiaoxi sediments, where P fractions are mainly affected by urbanization and other anthropogenic activities such as shipping.

  18. Variation of the distribution coefficient (Kd) of selenium in soils under various microbial states

    International Nuclear Information System (INIS)

    Fevrier, L.; Martin-Garin, A.; Leclerc, E.

    2007-01-01

    This study aimed to (i) evaluate whether the K d value of selenium is dependent upon the soil microbial activity and (ii) define the limitation of the use of the K d concept to describe selenium behaviour in soils when assessing the long-term radiological waste disposal risk. K d coefficients, as well as information on selenite speciation in the soil-solution, were derived from short- and long-term batch experiments with a calcareous silty clay soil in various microbial states. Soil microbial activity induced (i) an increase of the K d value from 16 l kg -1 in sterile conditions to 130 l kg -1 when the soil was amended with glucose and nitrate, and (ii) changes in selenium speciation both in the solution (presence of seleno-species other than free Se(IV)) and in the solid phase (Se linked to microorganisms). Although the K d coefficient adequately reflects the initial fractionation between soil-solid and soil-solution, it does not allow for speciation and microbial processes, which could affect reversibility, mobility and the long-term accumulation and uptake into crops

  19. Phosphorus fractionation and distribution in sediments from wetlands and canals of a water conservation area in the Florida Everglades

    Science.gov (United States)

    Qingren Wang; Yuncong Li; Ying. Ouyang

    2011-01-01

    Phosphorus (P) fractionation and distribution in sediments are of great concern in the Florida Everglades ecosystem because potential eutrophication of surface waters usually results from P external loading and stability. Intact core sediment samples were collected to a depth of 35 cm from wetlands and canals across Water Conservation Area 3 (WCA‐3) of the Florida...

  20. Particle size analysis of sediments used in studies of the distribution of oil-derived contaminants from the ''Sea Empress''

    International Nuclear Information System (INIS)

    1998-01-01

    Following the Sea Empress oil-spill, sediment samples were collected around the approaches to Milford Haven and analysed for PAHs. In order to facilitate the interpretation of these results it was decided to analyse the particle size distribution of the sediments. This report presents the results of particle-size measurements of 150 of those offshore samples. (author)

  1. Spatial distribution of heavy metals in sediments from the Gulf of Paria, Trinidad

    International Nuclear Information System (INIS)

    Norville, W.

    2005-01-01

    The Gulf of Paria receives heavy metal input from urban runoff, industrial and agricultural activity, sewage and domestic wastes: both from the west coast and from inland areas of Trinidad. Non-residual concentrations of nine metals, as well as total mercury concentrations, were used to determine spatial distributions of heavy metals in sediments in the Gulf of Paria. Surficial sediment samples were collected at 37 stations, which included the mouths of 11 major rivers that flow into the Gulf of Paria. Stations were sampled twice during the wet season (July 1998 and November/ December 1998) and twice during the dry season (March 1999 and April 1999). Sediments were analyzed for aluminium (Al), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), nickel (Ni), zinc (Zn) and mercury (Hg). Total Organic Carbon (TOC) and grain size analyses were also performed on the sediments. Principal component analysis showed that sediments from river mouths subject to greatest land use and anthropogenic input, were distinct from other sediments in the Gulf of Paria. This was due to higher Pb, Zn, Cu and Hg concentrations (3.53-73.30 μ g-', 45.8-313.9 μg g-', 8.43-39.71 μg g' and 0.03-0.10 μg g-', respectively). Sediments further from the coast were also distinct due to their higher Al, Fe, Cr and Mn concentrations (1.37-3.16 mg g-', 9.51-18.91 mg g-',17.22-28.41 μg g-' and 323.6--1,564.2 pg g-', respectively). Cd and Pb were higher in the wet season while Ni was higher in the dry season. Pb, Zn, Cu and Hg were correlated with each other and with TOC. Correlation was also observed between Al, Fe, Cr, Mn and Ni. Al, Fe, Cr and Mn were correlated with percentage clay in sediments. The results suggest that Pb, Zn, Cu and Hg are preferentially removed by organic matter, which settles at the river-mouths, while Al, Fe, Cr, Mn, and Ni become associated with clay minerals and are transported away from the coast.(From the author) [es

  2. Distribution of basic sediments (bedload transport) on changes in coastal coastline Donggala, Central Sulawesi Province, Indonesia

    Science.gov (United States)

    Amiruddin

    2018-03-01

    This study entitled "Distribution of Bedload Transport Against Coastline Changes in Donggala Coast", the formulation of the problem (1) how much of the estimated bedload transport in Donggala Bodies; (2) where were the location of erosion and sedimentation strong point based on the estimation of bed load transport; (3) the extent to which the prediction of shoreline change rate of transport of sediments in coastal areas Donggala. This study aims to: (1) the calculation of estimated bed load transport in Donggala waters; (2) determining the location of the point of erosion and sedimentation strong basis of estimated bedload transport; (3) the prediction of shoreline change rate of transport of sediments in coastal areas Donggala.The survey method used in this research to collect primary data include: (1) decision point waypoint coordinates of each location of measurement; (2) measurement of height, period and direction of the waves; (3) a large measurement of sediment transport; (4) The angle measurement coastline, angle of attack and wave direction, and secondary data include: (1) information from the public; (2) the physical condition data field. The results showed that: (1) general estimate sediment transport base in each location data collection is varied. This is due to the different points of the coastline as well as the angle of attack of the shoreline waters broke Donggala; (2) strong abrasion at the study site occurs at the point Ts4 (622.75 m3/yr) and TS11 (755.25 m3/yr) located in the Village Tosale and point Tw7 and Tw17 (649.25 m3/yr) in Village of Towale. As for the strong sedimentation occurs at the point Ts3 (450.50 m3/yr) located in the Village Tosale and Tg3 point (357.75 m3/yr) located in the Village Tolonggano; (3) of the predicted outcome coastline changes based on the input data estimate sediment transport, beaches and waves parameters is seen that the changes in the location prophyl coastline tends toward research into or undergo a process of

  3. Bed turbulent kinetic energy boundary conditions for trapping efficiency and spatial distribution of sediments in basins.

    Science.gov (United States)

    Isenmann, Gilles; Dufresne, Matthieu; Vazquez, José; Mose, Robert

    2017-10-01

    The purpose of this study is to develop and validate a numerical tool for evaluating the performance of a settling basin regarding the trapping of suspended matter. The Euler-Lagrange approach was chosen to model the flow and sediment transport. The numerical model developed relies on the open source library OpenFOAM ® , enhanced with new particle/wall interaction conditions to limit sediment deposition in zones with favourable hydrodynamic conditions (shear stress, turbulent kinetic energy). In particular, a new relation is proposed for calculating the turbulent kinetic energy threshold as a function of the properties of each particle (diameter and density). The numerical model is compared to three experimental datasets taken from the literature and collected for scale models of basins. The comparison of the numerical and experimental results permits concluding on the model's capacity to predict the trapping of particles in a settling basin with an absolute error in the region of 5% when the sediment depositions occur over the entire bed. In the case of sediment depositions localised in preferential zones, their distribution is reproduced well by the model and trapping efficiency is evaluated with an absolute error in the region of 10% (excluding cases of particles with very low density).

  4. Distribution and sources of n-alkanes in surface sediments of Taihu Lake, China

    Directory of Open Access Journals (Sweden)

    Yu Yunlong

    2016-03-01

    Full Text Available The last study on n-alkanes in surface sediments of Taihu Lake was in 2000, only 13 surface sediment samples were analysed, in order to have a comprehensive and up-to-date understanding of n-alkanes in the surface sediments of Taihu Lake, 41 surface sediment samples were analyzed by GC-MS. C10 to C37 were detected, the total concentrations of n-alkanes ranged from 2109 ng g−1 to 9096 ng g−1 (dry weight. There was strong odd carbon predominance in long chain n-alkanes and even carbon predominance in short chain n-alkanes. When this finding was combined with the analysis results of wax n-alkanes (WaxCn, carbon preference index (CPI, unresolved complex mixture (UCM, hopanes and steranes, it was considered that the long chain n-alkanes were mainly from terrigenous higher plants, and that the short chain n-alkanes mainly originated from bacteria and algae in the lake, compared with previous studies, there were no obvious anthropogenic petrogenic inputs. Terrestrial and aquatic hydrocarbons ratio (TAR and C21−/C25+ indicated that terrigenous input was higher than aquatic sources and the nearshore n-alkanes were mainly from land-derived sources. Moreover, the distribution of short chain n-alkanes presented a relatively uniform pattern, while the long chain n-alkanes presented a trend that concentrations dropped from nearshore places to the middle of lake.

  5. Solid/liquid partition coefficients (K{sub d}) and plant/soil concentration ratios (CR) for selected soils, tills and sediments at Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Sheppard, Steve (ECOMatters Inc. (Canada)); Sohlenius, Gustav (Sveriges geologiska undersoekning (Sweden)); Omberg, Lars-Gunnar (ALS Scandinavia AB (Sweden)); Borgiel, Mikael (Sveriges Vattenekologer AB (Sweden)); Grolander, Sara (Facilia AB (Sweden)); Norden, Sara (Svensk Kaernbraenslehantering AB (Sweden))

    2011-11-15

    Solid/liquid partition coefficients (K{sub d}) are used to indicate the relative mobility of radionuclides and elements of concern from nuclear fuel waste, as well as from other sources. To indicate the uptake of radionuclides in biota concentration ratios (CR) between soil and biota are used. This report summarized K{sub d} data for regolith and marine sediments based on concentrations of 69 indigenous stable elements measured from samples collected at the Forsmark site and CR data concerning cereals growing on these soils. The samples included 50 regolith samples from agricultural land and wetlands, 8 samples of till collected at different depths, and two marine sediment samples. In addition, cereal grains, stems and roots were collected from 4 sites for calculation of CRs. The regolith samples represented the major 5 deposits, which can be used as arable land, at the site (clayey till, glacial clay, clay gyttja and peat (cultivated and undisturbed)). K{sub d} values were generally lower for peat compared to clay soils. There were also clear differences in K{sub d} resulting from differences in soil chemistry within each regolith type. Soil pH was the most important factor, and K{sub d} values for many elements were lower in acidic clay soils compared to basic clay soils. Although there were only a few samples of sandy till and marine sediment, the K{sub d} values were generally consistent with the corresponding regolith K{sub d} values. Of the different cereal parts the grain always had the lowest CR. In most cases, the root CR was significantly higher than the grain CR, whereas only for a few elements were the grain and stem CR values different

  6. Solid/liquid partition coefficients (Kd) and plant/soil concentration ratios (CR) for selected soils, tills and sediments at Forsmark

    International Nuclear Information System (INIS)

    Sheppard, Steve; Sohlenius, Gustav; Omberg, Lars-Gunnar; Borgiel, Mikael; Grolander, Sara; Norden, Sara

    2011-11-01

    Solid/liquid partition coefficients (K d ) are used to indicate the relative mobility of radionuclides and elements of concern from nuclear fuel waste, as well as from other sources. To indicate the uptake of radionuclides in biota concentration ratios (CR) between soil and biota are used. This report summarized K d data for regolith and marine sediments based on concentrations of 69 indigenous stable elements measured from samples collected at the Forsmark site and CR data concerning cereals growing on these soils. The samples included 50 regolith samples from agricultural land and wetlands, 8 samples of till collected at different depths, and two marine sediment samples. In addition, cereal grains, stems and roots were collected from 4 sites for calculation of CRs. The regolith samples represented the major 5 deposits, which can be used as arable land, at the site (clayey till, glacial clay, clay gyttja and peat (cultivated and undisturbed)). K d values were generally lower for peat compared to clay soils. There were also clear differences in K d resulting from differences in soil chemistry within each regolith type. Soil pH was the most important factor, and K d values for many elements were lower in acidic clay soils compared to basic clay soils. Although there were only a few samples of sandy till and marine sediment, the K d values were generally consistent with the corresponding regolith K d values. Of the different cereal parts the grain always had the lowest CR. In most cases, the root CR was significantly higher than the grain CR, whereas only for a few elements were the grain and stem CR values different

  7. Vertical random variability of the distribution coefficient in the soil and its effect on the migration of fallout radionuclides

    International Nuclear Information System (INIS)

    Bunzl, K.

    2002-01-01

    In the field, the distribution coefficient, K d , for the sorption of a radionuclide by the soil cannot be expected to be constant. Even in a well defined soil horizon, K d will vary stochastically in horizontal as well as in vertical direction around a mean value. The horizontal random variability of K d produce a pronounced tailing effect in the concentration depth profile of a fallout radionuclide, much less is known on the corresponding effect of the vertical random variability. To analyze this effect theoretically, the classical convection-dispersion model in combination with the random-walk particle method was applied. The concentration depth profile of a radionuclide was calculated one year after deposition assuming constant values of the pore water velocity, the diffusion/dispersion coefficient, and the distribution coefficient (K d = 100 cm 3 x g -1 ) and exhibiting a vertical variability for K d according to a log-normal distribution with a geometric mean of 100 cm 3 x g -1 and a coefficient of variation of CV 0.53. The results show that these two concentration depth profiles are only slightly different, the location of the peak is shifted somewhat upwards, and the dispersion of the concentration depth profile is slightly larger. A substantial tailing effect of the concentration depth profile is not perceivable. Especially with respect to the location of the peak, a very good approximation of the concentration depth profile is obtained if the arithmetic mean of the K d -values (K d = 113 cm 3 x g -1 ) and a slightly increased dispersion coefficient are used in the analytical solution of the classical convection-dispersion equation with constant K d . The evaluation of the observed concentration depth profile with the analytical solution of the classical convection-dispersion equation with constant parameters will, within the usual experimental limits, hardly reveal the presence of a log-normal random distribution of K d in the vertical direction in

  8. Thiosulfate and sulfite distributions in porewater of marine sediments related to manganese, iron, and sulfur geochemistry

    Science.gov (United States)

    Thamdrup, Bo; Finster, Kai; Fossing, Henrik; Hansen, Jens Würgler; Jørgensen, Bo Barker

    1994-01-01

    Depth distributions of thiosulfate (S 2O 32-) and sulfite (SO 32-) were measured in the porewaters of a Danish salt marsh and subtidal marine sediments by HPLC analysis after derivatization with DTNP [2,2'-dithiobis(5-nitropyridine)]. The distributions were compared to the redox zonation as indicated by Eh and Mn 2+, Fe 2+ and H 2S distributions. Concentrations of S 2O 32- varied from below detection (<50 nM) to 600 nM while SO 32- concentrations generally were 2-3 times higher, 100-1500 nM. Depth distributions of the two species were roughly similar. Lowest concentrations were found in the oxidized zone, including both the oxic surface layer and the suboxic zone of intense manganese and iron reduction, and concentrations tended to increase through the suboxic and into the reduced, sulfidic zone. The similarity of SO 32- and S 2O 32- profiles suggested a close coupling of the cycling of the two species. Rates of consumption were suggested as the main factor governing their distribution. Rapid turnover times for S 2O 32- and H 2S of 4 and 1.1 h, respectively, were estimated for the upper 0-1 cm of a subtidal sediment.

  9. 137Cs distribution and geochemistry of Lena River (Siberia) drainage basin lake sediments

    International Nuclear Information System (INIS)

    Johnson-Pyrtle, A.; Scott, M.R.; Laing, T.E.; Smol, J.P.

    2000-01-01

    The Lena River is the second largest river that discharges into the Arctic Ocean. It is therefore important to determine not only the direct impact its discharge has on the 137Cs concentration of the Arctic, but also the potential its drainage basin has as a 137Cs source. 137Cs surface sediment concentrations and inventory values, which range from 4.97 to 338 Bq kg -1 and 357 to 1732 Bq m -2 , respectively, were determined for the Lena River drainage basin lake samples, via gamma analysis. The average geochemical and mineralogical composition of a subset of samples was also determined using neutron activation analysis, X-ray diffraction and X-ray fluorescence spectrometry techniques. Results of these geochemical analyses allowed for the identification of key geochemical factors that influence the distribution of 137Cs in the Lena River drainage basin. 137Cs profiles indicate that Lena River drainage basin lacustrine sediments serve as a record of 137Cs fallout. Based on the downcore 137Cs, %illite, %smectite, %Al and %Mn distribution patterns, it was concluded that a small fraction of non-selectively bound 137Cs was remobilized at depth in some cores. Inconsistencies between the actual 137Cs fallout record and the 137Cs profiles determined for the lake sediments were attributed to 137Cs remobilization in subsurface sediments. In addition to establishing the agreement between the global atmospheric fallout record and the downcore 137Cs distribution patterns determined for these sediments, results indicate that 137Cs deposited during periods of maximum atmospheric release was buried and is not susceptible to surface erosion processes. However, mean 137Cs concentrations of the lacustrine surface sediments (125 Bq kg -1 ) are still significantly higher than those of the nearby Lena River estuary (11.22 Bq kg -1 ) and Laptev Sea (6.00 Bq kg -1 ). Our study suggests that the Lena River drainage basin has the potential to serve as a source of 137Cs to the adjacent Arctic

  10. Environmental occurrence and distribution of organic UV stabilizers and UV filters in the sediment of Chinese Bohai and Yellow Seas.

    Science.gov (United States)

    Apel, Christina; Tang, Jianhui; Ebinghaus, Ralf

    2018-04-01

    Organic UV stabilizers and UV filters are applied to industrial materials and cosmetics worldwide. In plastics they prevent photo-induced degradation, while in cosmetics they protect human skin against harmful effects of UV radiation. This study reports on the occurrence and distribution of organic UV stabilizers and UV filters in the surface sediment of the Chinese Bohai and Yellow Seas for the first time. In total, 16 out of 21 analyzed substances were positively detected. Concentrations ranged from sub-ng/g dw to low ng/g dw. The highest concentration of 25 ng/g dw was found for octocrylene (OC) in the Laizhou Bay. In the study area, characteristic composition profiles could be identified. In Korea Bay, the dominating substances were OC and ethylhexyl salicylate (EHS). All other analytes were below their method quantification limit (MQL). Around the Shandong Peninsula, highest concentrations of benzotriazole derivatives were observed in this study with octrizole (UV-329) as the predominant compound, reaching concentrations of 6.09 ng/g dw. The distribution pattern of UV-329 and bumetrizole (UV-326) were related (Pearson correlation coefficient r > 0.98, p « 0.01 around the Shandong Peninsula), indicating an identical input pathway and similar environmental behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. The study of distribution and forms of uranium occurrences in Lake Baikal sediments by the SSNTD method

    International Nuclear Information System (INIS)

    Zhmodik, S.M.; Verkhovtseva, N.V.; Soloboeva, E.V.; Mironov, A.G.; Nemirovskaya, N.A.; Ilic, R.; Khlystov, O.M.; Titov, A.T.

    2005-01-01

    Sediments of Lake Baikal drill cores VER-96-1 St8 TW2 (53 deg. 32 ' 15 ' 'E; 107 deg. 56 ' 25 ' 'N) (interval 181.8-235cm from the sediment surface) were studied by means of SSNTD with the aim of defining uranium occurrence in the sediments and the uranium concentration. The neutron-fission ((n,f)-autoradiographic) method allowed a detailed study of uranium distribution of these Lake Baikal sediments within the Academicheskiy Ridge. Layered accumulations of uranium-bearing grained phosphorite, uranium-bearing particles of organic material, and abnormal uranium concentration in diatomite of unknown origin were discovered

  12. Heavy Metallic Element Distribution in Cisadane River Estuary's Water and Sediment

    Directory of Open Access Journals (Sweden)

    M. Taufik Kaisupy

    2006-04-01

    Full Text Available Observation of heavy metallic elements in Cisadane River Estuary has been done in July and November 2005. The results show that heavy metallic elements content in seawater is lower and still below the treshold value stated by government for fisheries. There was an indication of heavy metallic elements on sediment. Distribution of Pb on July and of Cu on November 2005 were found higher near the coast and decrease towards the sea, and commonly were found in front of estuary such as Cisadane, Muara Saban and Tanjung Pasir. High Pb and Zn distributions on November 2005 were found only in front of Cisadane estuary. Cd distribution of Cisadane estuary was constant at all station but did not show any correlation with the distance of station and estuary. The Cd content on July and November 2005 is lower than 0,001 ppm. Generally, heavy metallic elements content have a uniform distribution at all stations inspite of its distance to estuary.

  13. Determination of distribution coefficients of some natural radionuclides (U, Ra, Pb, Po) between different types of Syrian soils and their solutions

    International Nuclear Information System (INIS)

    Al-Masri, M. S.; Al-Hamwi, A.; Amin, Y.; Al-Akel, B.

    2009-11-01

    In this study, distribution coefficients of some natural radionuclides ( 226 Ra, U, 210 Pb and 210 Po) between different types of soils in Syria and their solutions were determined. The distribution coefficients values ranged from (164-1933, 280-1722, 350-4749 and 101-117) l kg - 1 for 226 Ra, U, 210 Pb and 210 Po, respectively at pH = 4.0. While, the distribution coefficients values ranged from (207-6706, 673-2397, 149-2147 and 103- 292) l kg - 1 for 226 Ra, U, 210 Pb and 210 Po, respectively at pH = 5.5. In addition, the distribution coefficients values ranged from (167-1707, 126- 1239, 44-1122 and 125-1475) l kg - 1 for 226 Ra, U, 210 Pb and 210 Po, respectively at pH = 7.0. Moreover, the results showed that 210 Po distribution coefficients had the maximum values at pH 7. While 210 Pb distribution coefficients had the minimum values at same pH. In addition to, U distribution coefficients had the maximum values at pH 5.5. On the other hand, the effect of soil mineral content, CEC, ECE, pH and soluble ions on the distribution coefficients were investigated. In general, the results showed that there are logarithmic relationships between studied radionuclide activity in the soil and their distribution coefficients in all soil types (R 2 ranged from 0.59 to 1.00 at pH 4.0). On the other hand, there were no relationships between the distribution coefficients and soil pH. (authors)

  14. Spatial distribution of heavy metals in surficial sediments from Guanabara Bay: Rio de Janeiro, Brazil

    Science.gov (United States)

    Neto, José Antônio Baptista; Gingele, Franz Xaver; Leipe, Thomas; Brehme, Isa

    2006-04-01

    Ninety-two surface sediment samples were collected in Guanabara Bay, one of the most prominent urban bays in SE Brazil, to investigate the spatial distribution of anthropogenic pollutants. The concentrations of heavy metals, organic carbon and particle size were examined in all samples. Large spatial variations of heavy metals and particle size were observed. The highest concentrations of heavy metals were found in the muddy sediments from the north western region of the bay near the main outlets of the most polluted rivers, municipal waste drainage systems and one of the major oil refineries. Another anomalous concentration of metals was found adjacent to Rio de Janeiro Harbour. The heavy metal concentrations decrease to the northeast, due to intact rivers and the mangrove systems in this area, and to the south where the sand fraction and open-marine processes dominate. The geochemical normalization of metal data to Li or Al has also demonstrated that the anthropogenic input of heavy metals have altered the natural sediment heavy metal distribution.

  15. Impacts of Mesopotamian wetland re-flooding on the lipid biomarker distributions in sediments

    Science.gov (United States)

    Rushdi, Ahmed I.; DouAbul, Ali A. Z.; Al-Maarofi, Sama S.; Simoneit, Bernd R. T.

    2018-03-01

    Shallow sediment core samples from two locales in the Mesopotamian marshlands of Iraq were analyzed to characterize the extractable organic (lipid) compounds, and their sources and distributions after hydrological restoration by re-flooding of the marshes. Dried samples were extracted with a dichloromethane/methanol mixture before analysis by gas chromatography-mass spectrometry (GC-MS). The major compounds were n-alkanes, fatty acids and alcohols, steroids, terpenoids, hopanes, steranes, unresolved complex mixture (UCM), and plasticizers. The lipid compounds in Kurmashia (Al-Hammar marshes) were generally higher in concentration than in Abu Zirig (Central marshes), and decreased with core depths for both sites. This concentration decrease with core depth is attributed to transformation, biodegradation and variable input processes. The distribution patterns of the lipids in the sediment cores indicated that the Abu Zirig area was drier than Kurmashia before the re-flooding process. Furthermore, the concentration of the compounds in the surface sediment the Abu Zirig core was as high and similar to that in Kurmashia, reflecting the re-flooding impacts on the marsh and the revival of the wetland. The major sources of these lipids were from natural terrestrial vegetation (35-66% for Abu Zirig; 40-49% for Kurmashia), microbial (plankton) residues and bacteria (27-52% for Abu Zirig; 39-43% for Kurmashia), with a minor contribution from anthropogenic sources including plastic wastes and petroleum (6-13% for Abu Zirig; 9-18% for Kurmashia).

  16. Distribution of some biochemical compounds in sediments of the shelf and slope regions of the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Dhargalkar, V.K.; Braganca, A.

    Surficial sediment samples collected from the continental shelf and slope of the Bay of Bengal were studied for the distribution of organic carbon and its constituent fractions such as carbohydrates, proteins, amino acids and lipids. Organic carbon...

  17. Distribution and seasonal variation of trace metals in surface sediments of the Mandovi estuary, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Alagarsamy, R.

    The concentration and distribution of selected trace metals in surface sediments of the Mandovi estuary were studied to determine the extent of anthropogenic inputs from mining activities and to estimate the effects of monsoon on geochemical...

  18. Clay mineral distribution in the shelf sediments off the northern part of the east coast of india

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Reddy, N.P.C.; Rao, Ch.M.

    Forty-eight sediment samples from the continental shelf between Visakhapatnam and the Ganges were analysed by X-ray diffraction for the composition and distribution of clay minerals. Estuarine samples of the Hooghly are dominated by illite...

  19. The spatial and temporal distribution of heavy metals in sediments of Victoria Harbour, Hong Kong

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Chloe Wing-yee; Ip, Carman Ching-man [Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Zhang Gan [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Shin, Paul K.S. [Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Qian Peiyuan [Department of Biology and Coastal Marine Laboratory, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Li Xiangdong [Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)], E-mail: cexdli@polyu.edu.hk

    2008-07-01

    Victoria Harbour has received substantial loadings of pollutants from industrial and municipal wastewater discharged since the 1950s. Inputs of contaminants have declined dramatically during the last two decades as a result of better controls at the source and improved wastewater treatment facilities. To assess the spatial and temporal changes of metal contaminants in sediments in Victoria Harbour, core and grab sediments were collected. The central harbour areas were generally contaminated with heavy metals. The spatial distribution of trace metals can probably be attributed to the proximity of major urban and industrial discharge points, and to the effect of tidal flushing in the harbour. In the sediment cores, the highest concentrations of trace metals were observed to have accumulated during the 1950s-1980s, corresponding with the period of rapid urban and industrial development in Hong Kong. From the late 1980s, there has been a major decline in the concentrations of trace metals, due to a reduction in industrial activities and to the enactment of wastewater pollution controls in the territory. The Pb isotopic compositions of the sediments revealed the anthropogenic inputs of Pb to the harbour. The {sup 206}Pb/{sup 207}Pb ratios varied from 1.154 to 1.190, which were lower than those of background geological materials in Hong Kong ({sup 206}Pb/{sup 207}Pb: 1.201-1.279). The data also indicated that the Pb in the harbour sediments most likely originated from mixed sources, including the leaded gasoline used in the past and other anthropogenic sources.

  20. Antimony and arsenic exhibit contrasting spatial distributions in the sediment and vegetation of a contaminated wetland.

    Science.gov (United States)

    Warnken, Jan; Ohlsson, Rohana; Welsh, David T; Teasdale, Peter R; Chelsky, Ariella; Bennett, William W

    2017-08-01

    Antimony is a priority environmental contaminant that is relatively poorly studied compared to other trace metal(loid)s. In particular, the behaviour of antimony in wetland sediments, where anaerobic conditions often dominate, has received considerably less attention compared to well-drained terrestrial soil environments. Here we report the results of a spatial assessment of antimony in the sediments and vegetation of a freshwater wetland exposed to stibnite tailings for the past forty years. The concentration of antimony in the sediment decreased rapidly with distance from the tailings deposit, from a maximum of ∼22,000 mg kg -1 to ∼1000 mg kg -1 at a distance of ∼150 m. In contrast, arsenic was distributed more evenly across the wetland, indicating that it was more mobile under the prevailing hypoxic/anoxic conditions. Less clear trends were observed in the tissues of wetland plants, with the concentrations of antimony in waterlilies (2.5-195 mg kg -1 ) showing no clear trends with distance from the tailings deposit, and no correlation with sediment concentrations. Sedges and Melaleuca sp. trees had lower antimony concentrations (<25 mg kg -1 and 5 mg kg -1 , respectively) compared to waterlilies, but showed a non-significant trend of higher concentrations closer to the tailings. For all vegetation types sampled, antimony concentrations were consistently lower than arsenic concentrations (Sb:As = 0.27-0.31), despite higher concentrations of antimony in the sediment. Overall, the results of this study highlight clear differences in the behaviour of antimony and arsenic in freshwater wetlands, which should be considered during the management and remediation of such sites. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Quantitative distribution of metazoan meiofauna in continental margin sediments of the Skagerrak (Northeastern North Sea)

    Science.gov (United States)

    De Bovée, F.; Hall, P. O. J.; Hulth, S.; Hulthe, G.; Landén, A.; Tengberg, A.

    1996-02-01

    A quantitative survey of metazoan meiofauna in continental-margin sediments of the Skagerrak was carried out using virtually undisturbed sediment samples collected with a multiple corer. Altogether 11 stations distributed along and across the Norwegian Trench were occupied during three cruises. Abundance ranged from 155 to 6846 ind·10 cm -2 and revealed a sharply decreasing trend with increasing water depth. The densities were high on the upper part of the Danish margin (6846 ind·10 cm -2 at 194 m depth) and low in the central part of the deep Skagerrak (155 ind·10 cm -2 at 637 m depth). Also body lengths were significantly shorter on the Danish margin then elsewhere in the Skagerrak, indicating a greater importance of juveniles in this area. We suggest that the high densities may be explained by a stimulated renewal of the fauna, possibly induced by an adequate food supply. The low abundances found in sediments from the deepest part of the Norwegian Trench cannot be attributed to any lack of oxygen. We suggest that the low meiofaunal abundances are caused by a decrease in the food supply (accentuated in this area by lower sedimentation rates) and/or by the very high concentrations of dissolved manganese in the pore water of these sediments. The metazoan meiofauna was largely dominated by nematodes. Comparison of the respiration rates of the nematode population with the total benthic respiration (0.5 to 14%) suggests that the relative importance of metazoan meiofauna decreased with water depth.

  2. Cross-Sectional Information on Pore Structure and Element Distribution of Sediment Particles by SEM and EDS

    Directory of Open Access Journals (Sweden)

    Minghong Chen

    2017-01-01

    Full Text Available The interaction between pollutants and sediment particles often occurs on the particle surface, so surface properties directly affect surface reaction. The physical and chemical processes occurring on sediment particle surfaces are microscopic processes and as such need to be studied from a microscopic perspective. In this study, field emission scanning electron microscopy (SEM and energy dispersive X-ray spectrometer (EDS were adopted to observe and analyze the pore structure and element distribution of sediment particles. In particular, a special method of sample preparation was used to achieve the corresponding cross-sectional information of sediment particles. Clear images of a particle profile and pore microstructure were obtained by high-resolution SEM, while element distribution maps of sediment particles were obtained by EDS. The results provide an intuitive understanding of the internal microenvironment and external behavior of sediment particles, in addition to revealing a significant role of pore microstructure in the adsorption and desorption of pollutants. Thus, a combination of different experimental instruments and observation methods can provide real images and information on microscopic pore structure and element distribution of sediment particles. These results should help to improve our understanding of sediment dynamics and its environmental effects.

  3. Vertical distribution of total carbon, nitrogen and phosphorus in sediments of Drug Spring Lake, Wudalianchi

    Science.gov (United States)

    Zeng, Ying; Yang, Chen

    2018-02-01

    The content of total organic carbon, total nitrogen and total phosphorus in sediments of Drug Spring Lake was detected and their vertical distribution characteristic was analysed. Results showed that there were significant changes to the content of total organic carbon, total nitrogen and total phosphorus in different depth of the columnar sediments. Their highest content both appeared in the interval of 10cm to 25cm corresponding to the period of 1980s to 1990s, when the tourism of Wudalianchi scenic area began to develop. It reflected the impact of human activities on the Drug Spring Lake. That means the regulation was still not enough, although a series of pollution control measures adopted by the government in recent years had initial success.

  4. Variability in waterfowl distribution within hypertidal estuaries in relation to sediments

    International Nuclear Information System (INIS)

    Clark, N.A.; Evans, J.; Rehfisch, M.M.; Shepherd, M.

    1993-01-01

    The Severn and Mersey estuaries are two of Britain's most important sites for their waterfowl populations. It is therefore critical to fully understand the likely impacts of tidal power barrages on these populations in order to predict the long-term post-barrage populations that the estuaries could support. Previous studies have enabled four years of monitoring to be carried out on both estuaries using identical methodology. These studies have shown that there is a considerable degree of consistency in the waterfowl populations in some areas, although apparently less so in other areas. Studies of sediment mobility have not been carried out in ways which enable direct comparison of changes in sediment with changes in bird populations. This latest study was planned to permit such a comparison and to provide five years of detailed counts on the Severn and four years on the Mersey on the low tide distribution of waterfowl populations. (author)

  5. Distribution and Source of Sedimentary Polycyclic Aromatic Hydrocarbon (PAHs in River Sediment of Jakarta

    Directory of Open Access Journals (Sweden)

    Rinawati Rinawati

    2017-11-01

    Full Text Available In this study, the distribution and source identification of sedimentary PAHs from 13 rivers running through Jakarta City were investigated. Freeze-dried sediment samples were extracted by pressurized fluid extraction and purified by two-step of column chromatography. PAHs were identified and quantified by gas chromatography-mass spectrometry (GC-MS. High concentrations of PAHs, ranging from 1992 to 17635 ng/g-dw, were observed at all sampling locations. Ratios of alkylated PAHs to parent PAHs exhibited both petrogenic and pyrogenic signatures with predominantly petrogenic inputs. High hopanne concentrations (4238-40375 ng/g dry sediment supported the petrogenic input to Jakarta’s rivers. The high concentration of PAHs is indicator for organic micropollutant in the aquatic urban environment in Jakarta that may have the potential to cause adverse effect to the environment.

  6. Distribution and behavior of major and trace elements in Tokyo Bay, Mutsu Bay and Funka Bay marine sediments

    International Nuclear Information System (INIS)

    Honda, Teruyuki; Kimura, Ken-ichiro

    2003-01-01

    Fourteen major and trace elements in marine sediment core samples collected from the coasts along eastern Japan, i.e. Tokyo Bay (II) (the recess), Tokyo Bay (IV) (the mouth), Mutsu Bay and Funka Bay and the Northwest Pacific basin as a comparative subject were determined by the instrumental neutron activation analysis (INAA). The sedimentation rates and sedimentary ages were calculated for the coastal sediment cores by the 210 Pb method. The results obtained in this study are summarized as follows: (1) Lanthanoid abundance patterns suggested that the major origin of the sediments was terrigenous material. La*/Lu* and Ce*/La* ratios revealed that the sediments from Tokyo Bay (II) and Mutsu Bay more directly reflected the contribution from river than those of other regions. In addition, the Th/Sc ratio indicated that the coastal sediments mainly originated in the materials from the volcanic island-arcs, Japanese islands, whereas those from the Northwest Pacific mainly from the continent. (2) The correlation between the Ce/U and Th/U ratios with high correlation coefficients of 0.920 to 0.991 indicated that all the sediments from Tokyo Bay (II) and Funka Bay were in reducing conditions while at least the upper sediments from Tokyo Bay (IV) and Mutsu Bay were in oxidizing conditions. (3) It became quite obvious that the sedimentation mechanism and the sedimentation environment at Tokyo Bay (II) was different from those at Tokyo Bay (IV), since the sedimentation rate at Tokyo Bay (II) was approximately twice as large as that at Tokyo Bay (IV). The sedimentary age of the 5th layer (8∼10 cm in depth) from Funka Bay was calculated at approximately 1940∼50, which agreed with the time, 1943∼45 when Showa-shinzan was formed by the eruption of the Usu volcano. (author)

  7. Spatial and temporal distributions of polycyclic aromatic hydrocarbons in sediments from the Songhua River, China

    Science.gov (United States)

    Dong, D.; Guo, Z.; Liu, X.; Hua, X.; Liang, D.

    2013-12-01

    Polycyclic aromatic hydrocarbons (PAHs), a class of typical persistent organic pollutants, widely exist in the environment and are potentially harmful to human health. They can enter the waters through atmospheric deposition, soil leaching, shipping, sewage discharges and surface runoff. In recent years, many studies on the distributions of PAHs in major rivers, lakes and bays around the world have been carried out. In this study, 9 surface sediments (0-10cm) were sampled from the Songhua River in Jilin and Heilongjiang provinces. The contents of 16 PAHs in the US Environmental Protection Agency list of priority pollutants were determined and their spatial distributions were discussed. Sediment cores (50cm length) in three oxbow lakes in this area were also collected and cut into 2 cm thickness sub-samples. PAHs concentrations in these samples were determined and the cores were dated using a 210Pb geochronology technique. Finally, the sedimentary history of PAHs in the Songhua River since the 1920s was revealed. Results indicated that total concentration of the 16 PAHs analyzed in the surface sediments was 187-2079 ng/g (dry weight), and the mean was 1029 ng/g. Sediments collected from near urban areas (Jilin and Harbin City) contained higher PAHs content. Compared with the domestic and international rivers, the PAHs content in this river sediments is at a medium level. The PAHs profiles showed that 2-3 ring PAHs, especially naphthalene, were dominant in all of the samples. Sedimentary flux can reflect the accumulating history of pollutants better. The PAHs fluxes were low and varied little from the 1920s to 1970s, but higher PAH fluxes were found since the 1980s in each core (Fig. 1). The PAHs sedimentary flux near Harbin City (Shuangcheng) was found changed remarkably. We inferred that the PAHs might be influenced by hydrological conditions, population mobility and economic activity in this area. PAHs sedimentary record in the Songhua River revealed that the

  8. Sources and distribution of yttrium and rare earth elements in surface sediments from Tagus estuary, Portugal.

    Science.gov (United States)

    Brito, Pedro; Prego, Ricardo; Mil-Homens, Mário; Caçador, Isabel; Caetano, Miguel

    2018-04-15

    The distribution and sources of yttrium and rare-earth elements (YREE) in surface sediments were studied on 78 samples collected in the Tagus estuary (SW Portugal, SW Europe). Yttrium and total REE contents ranged from 2.4 to 32mg·kg -1 and 18 to 210mg·kg -1 , respectively, and exhibited significant correlations with sediment grain-size, Al, Fe, Mg and Mn, suggesting a preferential association to fine-grained material (e.g. aluminosilicates but also Al hydroxides and Fe oxyhydroxides). The PAAS (Post-Archean Australian Shale) normalized patterns display three distinct YREE fractionation pattern groups along the Tagus estuary: a first group, characterized by medium to coarse-grained material, a depleted and almost flat PAAS-normalized pattern, with a positive anomaly of Eu, representing one of the lithogenic components; a second group, characterized mainly by fine-grained sediment, with higher shale-normalized ratios and an enrichment of LREE relative to HREE, associated with waste water treatment plant (WWTP) outfalls, located in the northern margin; and, a third group, of fine-grained material, marked by a significant enrichment of Y, a depletion of Ce and an enrichment of HREE over LREE, located near an inactive chemical-industrial complex (e.g. pyrite roast plant, chemical and phosphorous fertilizer industries), in the southern margin. The data allow the quantification of the YREE contents and its spatial distribution in the surface sediments of the Tagus estuary, identifying the main potential sources and confirming the use of rare earth elements as tracers of anthropogenic activities in highly hydrodynamic estuaries. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. An employment of distribution coefficients for the valuation of the soils with regard to their radiological risks

    International Nuclear Information System (INIS)

    Carini, F.; Silva, S.; Fontana, P.

    1985-01-01

    As a preliminary step it has been demonstrated that the distribution coefficients may prove useful items in order to classify soils to a radioprotective purpose. We have obtained transfer factors from soils, which were different according to their principal chemical and physical features, into plants typical of the middle Po valley agriculture. By utilizing these factors as guiding indexes,it is possible, through cluster analysis, to determine a range of soils with regard to their radiological risk starting only from the pedologic parameters

  10. Determination of the distribution coefficient of 46 elements on tin dioxide in 0.1N HNO3-acetone media

    International Nuclear Information System (INIS)

    Jaffrezic-Renault, N.

    1977-01-01

    The use of radioactive indicators for the determination of the distribution coefficients of 46 elements on SnO 2 in 0.1N HNO 3 -acetone media is described. The determination has been carried out in static conditions: labelled element solution has been agitated with SnO 2 for two hours; the elements have been labelled with radioisotopes generally obtained by (n, γ) reaction, by irradiating a part of the used salt in EL 3 or OSIRIS reactor in the C.E.N. Saclay (France). Results show that the elements may be classified into several groups, according to their oxidation state. (T.I.)

  11. Existence and global exponential stability of periodic solution to BAM neural networks with periodic coefficients and continuously distributed delays

    International Nuclear Information System (INIS)

    Zhou Tiejun; Chen Anping; Zhou Yuyuan

    2005-01-01

    By using the continuation theorem of coincidence degree theory and Liapunov function, we obtain some sufficient criteria to ensure the existence and global exponential stability of periodic solution to the bidirectional associative memory (BAM) neural networks with periodic coefficients and continuously distributed delays. These results improve and generalize the works of papers [J. Cao, L. Wang, Phys. Rev. E 61 (2000) 1825] and [Z. Liu, A. Chen, J. Cao, L. Huang, IEEE Trans. Circuits Systems I 50 (2003) 1162]. An example is given to illustrate that the criteria are feasible

  12. Existence and global exponential stability of periodic solution to BAM neural networks with periodic coefficients and continuously distributed delays

    Science.gov (United States)

    Zhou, distributed delays [rapid communication] T.; Chen, A.; Zhou, Y.

    2005-08-01

    By using the continuation theorem of coincidence degree theory and Liapunov function, we obtain some sufficient criteria to ensure the existence and global exponential stability of periodic solution to the bidirectional associative memory (BAM) neural networks with periodic coefficients and continuously distributed delays. These results improve and generalize the works of papers [J. Cao, L. Wang, Phys. Rev. E 61 (2000) 1825] and [Z. Liu, A. Chen, J. Cao, L. Huang, IEEE Trans. Circuits Systems I 50 (2003) 1162]. An example is given to illustrate that the criteria are feasible.

  13. Distribution of heavy metals in riverine soils and sediments of the Turia River basin.

    Science.gov (United States)

    Andreu, Vicente; Gimeno-García, Eugenia; Pascual, Juan Antonio

    2014-05-01

    Water is a scarce and contested good, and a primary need for the population all over. Rivers are one of the mainsources of freshwater to people but, in the same way, receive both point source and difuse pollution, usually frorm wastewaters and agriculture. However, they are not independent bodies but they influence different associated ecosystems that compound the catchment. Soils of the river banks often acts as the last phase of the diffuse contamination pathways, favouring the contaminants input to the river waters. In this sense, the fluvial sedimentary phase usually acts as a sink of pollutants. Sediments can work as resevoirs that accumulate contaminants fixing them or allowing their decomposition or metabolization. However, environmental or human induced, such as variations in water pH, increases in the turbulence or intensity of the water flow, etc.could favour their release to the environment. In this work, the incidence and distribution of seven heavy metals was monitored in riverine soils and sediments of the Turia River. Along the river course, 22 zones were selected for sampling according different lithologies, land uses, size of populations and the proximity to waste waters treatment plants (WWTPs), from the headwaters to the mouth. The selected metals (Cd, Co, Cr, Cu, Pb, Ni and Zn) were analysed to determine its total and extractable contents in the sediments. Total content of metals was extracted by microwave acid digestion and the extractable fraction by treatment with EDTA. Atomic Absorption Spectrometry, using graphite furnace when necessary, was used for the determination of all metals. Highest values for sediments were mainly observed in zones 10 and 22, close to urban areas, reaching values of 172.86 mg/kg for Pb, or 58.34 mg/kg for Cr. However, zone 2 near in the headwaters of the Alfambra River and supposedly of reference for the River authorities shows the highest values of zinc with 96.96 mg/kg. Regarding the available

  14. Three-dimensional reconstruction of a radionuclide distribution within a medium of uniform coefficient of attenuation

    International Nuclear Information System (INIS)

    Diaz, J.E.

    1982-01-01

    The non-invasive, fully three-dimensional reconstruction of a radionuclide distribution is studied. The problem is considered in ideal form. Several solutions, ranging from the completely analytical to the completely graphical, are presented for both the non-attenuated and uniformly attenuated cases. A function is defined which, if enacted as a response to each detected photon, will yield, upon superposition, a faithful reconstruction of the radionuclide density. Two and three-dimensional forms of this functions are defined for both the non-attenuated and uniformly attenuated case

  15. Spatial Distribution of the Coefficient of Variation for the Paleo-Earthquakes in Japan

    Science.gov (United States)

    Nomura, S.; Ogata, Y.

    2015-12-01

    Renewal processes, point prccesses in which intervals between consecutive events are independently and identically distributed, are frequently used to describe this repeating earthquake mechanism and forecast the next earthquakes. However, one of the difficulties in applying recurrent earthquake models is the scarcity of the historical data. Most studied fault segments have few, or only one observed earthquake that often have poorly constrained historic and/or radiocarbon ages. The maximum likelihood estimate from such a small data set can have a large bias and error, which tends to yield high probability for the next event in a very short time span when the recurrence intervals have similar lengths. On the other hand, recurrence intervals at a fault depend on the long-term slip rate caused by the tectonic motion in average. In addition, recurrence times are also fluctuated by nearby earthquakes or fault activities which encourage or discourage surrounding seismicity. These factors have spatial trends due to the heterogeneity of tectonic motion and seismicity. Thus, this paper introduces a spatial structure on the key parameters of renewal processes for recurrent earthquakes and estimates it by using spatial statistics. Spatial variation of mean and variance parameters of recurrence times are estimated in Bayesian framework and the next earthquakes are forecasted by Bayesian predictive distributions. The proposal model is applied for recurrent earthquake catalog in Japan and its result is compared with the current forecast adopted by the Earthquake Research Committee of Japan.

  16. Spatiotemporal distribution of radioactive cesium released from Fukushima Daiichi Nuclear Power Station in the sediment of Tokyo Bay, Japan

    International Nuclear Information System (INIS)

    Nakagawa, Ryota; Ishida, Masanobu; Baba, Daisuke; Tanimoto, Satomi; Okamoto, Yuichi; Yamazaki, Hideo

    2013-01-01

    The spatial and temporal distribution of "1"3"4Cs and "1"3"7Cs released from Fukushima Daiichi Nuclear Power Station in the Tokyo Bay sediments were investigated. The total radioactivity of "1"3"4Cs and "1"3"7Cs detected in the Tokyo Bay sediment ranged from 240 to 870 Bq/kg-dry in the estuary of Arakawa River, but the activities detected in other sites were about 90 Bq/kg-dry or less. These results suggested that radioactive cesium, which precipitated to the ground, was carried to the river along with clay particles by rainfall and transported to the estuary. The vertical distribution of radioactive cesium showed that it invaded deeper than estimated based on the accumulation rate of the sediment. It was described that the vertical distribution of radioactive cesium was affected by physical mixing of sediments by tidal current, flood, and bioturbation of benthos. (author)

  17. Baryon Distribution in Galaxy Clusters as a Result of Sedimentation of Helium Nuclei.

    Science.gov (United States)

    Qin; Wu

    2000-01-20

    Heavy particles in galaxy clusters tend to be more centrally concentrated than light ones according to the Boltzmann distribution. An estimate of the drift velocity suggests that it is possible that the helium nuclei may have entirely or partially sedimented into the cluster core within the Hubble time. We demonstrate this scenario using the Navarro-Frenk-White profile as the dark matter distribution of clusters and assuming that the intracluster gas is isothermal and in hydrostatic equilibrium. We find that a greater fraction of baryonic matter is distributed at small radii than at large radii, which challenges the prevailing claim that the baryon fraction increases monotonically with cluster radius. It shows that the conventional mass estimate using X-ray measurements of intracluster gas along with a constant mean molecular weight may have underestimated the total cluster mass by approximately 20%, which in turn leads to an overestimate of the total baryon fraction by the same percentage. Additionally, it is pointed out that the sedimentation of helium nuclei toward cluster cores may at least partially account for the sharp peaks in the central X-ray emissions observed in some clusters.

  18. Study of distribution coefficient of some radionuclides in liquid-solid systems

    International Nuclear Information System (INIS)

    Ghafar, M.; Abdul-Hadi, A.; Al-Hassanieh, O.

    2001-10-01

    The distribution of the elements U, Th, Am, Eu, Cs, Sr and Ra in a solid-aqueous system. Natural phosphate in contact with groundwater, was investigated usingγ and α spectroscopy. The effect of various factors such as phase contact time, Ph, particle size of the solid phase, and the concentration of a element Ca, were studied. The obtained results show that, more than 98% of the actinide elements and europium are adsorbed by the solid phase under all conditions. The fission products Cs and Sr have different behaviours, depending on experiment conditions. The behaviour of Ra is closer to the actinides than to the fission products. There are small differences between the behaviour of the actinide elements, which can be interpreted by migration mechanism from the aqueous to the solid phase i.e. adsorption or precipitation. (author)

  19. Oscillation for equations with positive and negative coefficients and with distributed delay I: General results

    Directory of Open Access Journals (Sweden)

    Leonid Berezansky

    2003-02-01

    Full Text Available We study a scalar delay differential equation with a bounded distributed delay, $$ dot{x}(t+ int_{h(t}^t x(s,d_s R(t,s - int_{g(t}^t x(s,d_s T(t,s=0, $$ where $R(t,s$, $T(t,s$ are nonnegative nondecreasing in $s$ for any $t$, $$ R(t,h(t=T(t,g(t=0, quad R(t,s geq T(t,s. $$ We establish a connection between non-oscillation of this differential equation and the corresponding differential inequalities, and between positiveness of the fundamental function and the existence of a nonnegative solution for a nonlinear integral inequality that constructed explicitly. We also present comparison theorems, and explicit non-oscillation and oscillation results. In a separate publication (part II, we will consider applications of this theory to differential equations with several concentrated delays, integrodifferential, and mixed equations.

  20. Determination of the cesium distribution coefficient in Goiania and Abadia de Goias cities soils

    International Nuclear Information System (INIS)

    Marumo, J.T.; Suarez, A.A.

    1989-10-01

    In September, 1987, an unauthorized removal of a cesium-therapy unit and its violation caused an accident, where several places of Goiania's city, capital of Goias, Brazil, were contaminated. The removal of the radioactive wastes generated from decontamination process, was made to Abadia de Goias city (near Goiania), where an interim storage was constructed. Soil samples collected from the 57 th Street (Goiania) and from the interim storage permitted to determine, through static method, the cesium distribution coefficent for different cesium solution concentrations. Those results allows for some migration/retention evaluations in disposal site selection. Some soils parameters (water content, density, granulometric analysis etc) as well as clay minerals constituents were also determined. (author) [pt

  1. Predicting volume of distribution with decision tree-based regression methods using predicted tissue:plasma partition coefficients.

    Science.gov (United States)

    Freitas, Alex A; Limbu, Kriti; Ghafourian, Taravat

    2015-01-01

    Volume of distribution is an important pharmacokinetic property that indicates the extent of a drug's distribution in the body tissues. This paper addresses the problem of how to estimate the apparent volume of distribution at steady state (Vss) of chemical compounds in the human body using decision tree-based regression methods from the area of data mining (or machine learning). Hence, the pros and cons of several different types of decision tree-based regression methods have been discussed. The regression methods predict Vss using, as predictive features, both the compounds' molecular descriptors and the compounds' tissue:plasma partition coefficients (Kt:p) - often used in physiologically-based pharmacokinetics. Therefore, this work has assessed whether the data mining-based prediction of Vss can be made more accurate by using as input not only the compounds' molecular descriptors but also (a subset of) their predicted Kt:p values. Comparison of the models that used only molecular descriptors, in particular, the Bagging decision tree (mean fold error of 2.33), with those employing predicted Kt:p values in addition to the molecular descriptors, such as the Bagging decision tree using adipose Kt:p (mean fold error of 2.29), indicated that the use of predicted Kt:p values as descriptors may be beneficial for accurate prediction of Vss using decision trees if prior feature selection is applied. Decision tree based models presented in this work have an accuracy that is reasonable and similar to the accuracy of reported Vss inter-species extrapolations in the literature. The estimation of Vss for new compounds in drug discovery will benefit from methods that are able to integrate large and varied sources of data and flexible non-linear data mining methods such as decision trees, which can produce interpretable models. Graphical AbstractDecision trees for the prediction of tissue partition coefficient and volume of distribution of drugs.

  2. Spatial distribution of ammonia-oxidizing archaea and bacteria across eight freshwater lakes in sediments from Jiangsu of China

    Directory of Open Access Journals (Sweden)

    Xu Sun

    2014-03-01

    Full Text Available Ammonia-oxidizingarchaea (AOA and ammonia-oxidizing bacteria (AOB play an important role innitrogen transformation in freshwater sediments. However, it is still unclear towhat extent the distribution patterns of these microorganisms are affected bythe freshwater sediment across a large geographical scale. This study wasdesigned to gain insight into the heterogeneity distribution of AOA and AOB in32 freshwater sediments from a wide range of ecologic types. Real-time quantitative polymerasechain reaction PCR(qPCR combined with the terminal restrictionfragment length polymorphism(T-RFLP were employed to characterize the abundance, diversity, and communitystructure of the AOA and AOB in 32 freshwater sediments. AOA and AOB wereubiquitous in all sediments, and archaeal amoA far outnumbered bacterial amoA inmost sediments with lower organic matters. The abundance of AOA and AOB did notvary with the freshwater ecological type (macrophyte dominated region and algaedominated region. Based on  the T-RFLP of an amoA gene, this research found that organicmatters in pore water rather than other factors affect the AOA communitystructure in sediments, while the AOB were not significantly different in thefreshwater sediments. Phylogenetic analysis showed that all archaeal amoAsequences fell within either the Crenarchaeotal Group (CG I.1b or the CGI.1asubgroup, and all AOB clustered with genus Nitrosomonas or Nitrosospira. The data obtained inthis study elucidates the role of ammonia-oxidizing archaea andammonia-oxidizing bacteria in the nitrogen cycle of freshwater ecosystems.

  3. Unified solution of the Boltzmann equation for electron and ion velocity distribution functions and transport coefficients in weakly ionized plasmas

    Science.gov (United States)

    Konovalov, Dmitry A.; Cocks, Daniel G.; White, Ronald D.

    2017-10-01

    The velocity distribution function and transport coefficients for charged particles in weakly ionized plasmas are calculated via a multi-term solution of Boltzmann's equation and benchmarked using a Monte-Carlo simulation. A unified framework for the solution of the original full Boltzmann's equation is presented which is valid for ions and electrons, avoiding any recourse to approximate forms of the collision operator in various limiting mass ratio cases. This direct method using Lebedev quadratures over the velocity and scattering angles avoids the need to represent the ion mass dependence in the collision operator through an expansion in terms of the charged particle to neutral mass ratio. For the two-temperature Burnett function method considered in this study, this amounts to avoiding the need for the complex Talmi-transformation methods and associated mass-ratio expansions. More generally, we highlight the deficiencies in the two-temperature Burnett function method for heavy ions at high electric fields to calculate the ion velocity distribution function, even though the transport coefficients have converged. Contribution to the Topical Issue "Physics of Ionized Gases (SPIG 2016)", edited by Goran Poparic, Bratislav Obradovic, Dragana Maric and Aleksandar Milosavljevic.

  4. Comparison of the distribution coefficients of plutonium and other radionuclides in Lake Michigan to those in other systems

    International Nuclear Information System (INIS)

    Wahlgren, M.A.; Nelson, D.M.

    1976-01-01

    Filtration of Lake Michigan water samples has been carried out routinely since 1973, and some plutonium concentrations in the seston have been reported. During 1975 and 1976 a sufficient number of filter samples from various depths was obtained throughout the field seasons to establish whether or not a distribution coefficient also controls the uptake of plutonium by the formation of particulates and their settling from the surface waters. Samples from ANL station 5 (10 km SW of Grand Haven, Michigan, water depth 67 m), of the southern basin, and from the lower Great Lakes have been analyzed for dry weight, ash weight, total organic (loss of weight on ignition), amorphous silica, calcite, and residual minerals. Distribution coefficients were calculated on the basis of each of these solid components, and self-consistent values were observed for depth, season, or lake only, on the basis of dry weight of seston. The findings strongly suggest that the uptake of fallout plutonium (including inputs of new fallout during the summer of 1975) is dominated by a surface coating process common to all seston particle types. An insufficient number of 137 Cs analyses were obtained to correlate its uptake to a specific component of the seston, but its behavior is clearly different from that of plutonium

  5. Vertical distribution of tritium in core sediment of Mumbai Harbour Bay

    International Nuclear Information System (INIS)

    Rupali, C.K.; Joshi, Vikram; Jha, S.K.; Tripathi, R.M.; Sonali, B.; Priyanka, R.

    2014-01-01

    In the past few years there has been an increasing interest in the study of behavior of tritium in the environment, worldwide many countries have initiated monitoring of organically bound tritium in the environmental samples as part of their radiological assessments. Tritium ( 3 H) is ubiquitous in the aquatic environment and has a various sources of origin. It is transported to the earth's surface via hydrological cycle. 3 H is produced in variety of processes in nuclear power plants. Discharges to aquatic environment from these establishment results in locally enhanced water concentrations. Levels of 3 H have been further elevated due to atmospheric weapons testing between 1952 and 1962. Recent studies have demonstrated significant accumulation of tritium in both organic-rich sediments and food chain. The present study describes the vertical profile of tritium distribution in core sediment collected from Mumbai Harbour Bay (MHB). This will help in better understanding of the biogeochemical behavior and ecological impacts of tritium in the sediment

  6. Distribution of dehalogenation activity in subseafloor sediments of the Nankai Trough subduction zone.

    Science.gov (United States)

    Futagami, Taiki; Morono, Yuki; Terada, Takeshi; Kaksonen, Anna H; Inagaki, Fumio

    2013-04-19

    Halogenated organic matter buried in marine subsurface sediment may serve as a source of electron acceptors for anaerobic respiration of subseafloor microbes. Detection of a diverse array of reductive dehalogenase-homologous (rdhA) genes suggests that subseafloor organohalide-respiring microbial communities may play significant ecological roles in the biogeochemical carbon and halogen cycle in the subseafloor biosphere. We report here the spatial distribution of dehalogenation activity in the Nankai Trough plate-subduction zone of the northwest Pacific off the Kii Peninsula of Japan. Incubation experiments with slurries of sediment collected at various depths and locations showed that degradation of several organohalides tested only occurred in the shallow sedimentary basin, down to 4.7 metres below the seafloor, despite detection of rdhA in the deeper sediments. We studied the phylogenetic diversity of the metabolically active microbes in positive enrichment cultures by extracting RNA, and found that Desulfuromonadales bacteria predominate. In addition, for the isolation of genes involved in the dehalogenation reaction, we performed a substrate-induced gene expression screening on DNA extracted from the enrichment cultures. Diverse DNA fragments were obtained and some of them showed best BLAST hit to known organohalide respirers such as Dehalococcoides, whereas no functionally known dehalogenation-related genes such as rdhA were found, indicating the need to improve the molecular approach to assess functional genes for organohalide respiration.

  7. Sediment transport modelling in a distributed physically based hydrological catchment model

    Directory of Open Access Journals (Sweden)

    M. Konz

    2011-09-01

    Full Text Available Bedload sediment transport and erosion processes in channels are important components of water induced natural hazards in alpine environments. A raster based distributed hydrological model, TOPKAPI, has been further developed to support continuous simulations of river bed erosion and deposition processes. The hydrological model simulates all relevant components of the water cycle and non-linear reservoir methods are applied for water fluxes in the soil, on the ground surface and in the channel. The sediment transport simulations are performed on a sub-grid level, which allows for a better discretization of the channel geometry, whereas water fluxes are calculated on the grid level in order to be CPU efficient. Several transport equations as well as the effects of an armour layer on the transport threshold discharge are considered. Flow resistance due to macro roughness is also considered. The advantage of this approach is the integrated simulation of the entire basin runoff response combined with hillslope-channel coupled erosion and transport simulation. The comparison with the modelling tool SETRAC demonstrates the reliability of the modelling concept. The devised technique is very fast and of comparable accuracy to the more specialised sediment transport model SETRAC.

  8. Non-equilibrium flow and sediment transport distribution over mobile river dunes

    Science.gov (United States)

    Hoitink, T.; Naqshband, S.; McElroy, B. J.

    2017-12-01

    Flow and sediment transport are key processes in the morphodynamics of river dunes. During floods in several rivers (e.g., the Elkhorn, Missouri, Niobrara, and Rio Grande), dunes are observed to grow rapidly as flow strength increases, undergoing an unstable transition regime, after which they are washed out in what is called upper stage plane bed. This morphological evolution of dunes to upper stage plane bed is the strongest bed-form adjustment during non-equilibrium flows and is associated with a significant change in hydraulic roughness and water levels. Detailed experimental investigations, however, have mostly focused on fixed dunes limited to equilibrium flow and bed conditions that are rare in natural channels. Our understanding of the underlying sedimentary processes that result into the washing out of dunes is therefore very limited. In the present study, using the Acoustic Concentration and Velocity Profiler (ACVP), we were able to quantify flow structure and sediment transport distribution over mobile non-equilibrium dunes. Under these non-equilibrium flow conditions average dune heights were decreasing while dune lengths were increasing. Preliminary results suggest that this morphological behaviour is due to a positive phase lag between sediment transport maximum and topographic maximum leading to a larger erosion on the dune stoss side compared to deposition on dune lee side.

  9. Heavy Metallic Element Distribution in Cisadane River Estuary's Water and Sediment

    OpenAIRE

    M. Taufik Kaisupy; Abdul Rozak; Endang Rochyatun

    2006-01-01

    Observation of heavy metallic elements in Cisadane River Estuary has been done in July and November 2005. The results show that heavy metallic elements content in seawater is lower and still below the treshold value stated by government for fisheries. There was an indication of heavy metallic elements on sediment. Distribution of Pb on July and of Cu on November 2005 were found higher near the coast and decrease towards the sea, and commonly were found in front of estuary such as Cisadane, Mu...

  10. Impacts of flocculation on the distribution and diagenesis of iron in boreal estuarine sediments

    Directory of Open Access Journals (Sweden)

    T. Jilbert

    2018-03-01

    Full Text Available Iron (Fe plays a key role in sedimentary diagenetic processes in coastal systems, participating in various redox reactions and influencing the burial of organic carbon. Large amounts of Fe enter the marine environment from boreal river catchments associated with dissolved organic matter (DOM and as colloidal Fe oxyhydroxides, principally ferrihydrite. However, the fate of this Fe pool in estuarine sediments has not been extensively studied. Here we show that flocculation processes along a salinity gradient in an estuary of the northern Baltic Sea efficiently transfer Fe and OM from the dissolved phase into particulate material that accumulates in the sediments. Flocculation of Fe and OM is partially decoupled. This is likely due to the presence of discrete colloidal ferrihydrite in the freshwater Fe pool, which responds differently from DOM to estuarine mixing. Further decoupling of Fe from OM occurs during sedimentation. While we observe a clear decline with distance offshore in the proportion of terrestrial material in the sedimentary particulate organic matter (POM pool, the distribution of flocculated Fe in sediments is modulated by focusing effects. Labile Fe phases are most abundant at a deep site in the inner basin of the estuary, consistent with input from flocculation and subsequent focusing. The majority of the labile Fe pool is present as Fe (II, including both acid-volatile sulfur (AVS-bound Fe and unsulfidized phases. The ubiquitous presence of unsulfidized Fe (II throughout the sediment column suggests Fe (II-OM complexes derived from reduction of flocculated Fe (III-OM, while other Fe (II phases are likely derived from the reduction of flocculated ferrihydrite. Depth-integrated rates of Fe (II accumulation (AVS-Fe + unsulfidized Fe (II + pyrite for the period 1970–2015 are greater in the inner basin of the estuary with respect to a site further offshore, confirming higher rates of Fe reduction in near-shore areas

  11. Impacts of flocculation on the distribution and diagenesis of iron in boreal estuarine sediments

    Science.gov (United States)

    Jilbert, Tom; Asmala, Eero; Schröder, Christian; Tiihonen, Rosa; Myllykangas, Jukka-Pekka; Virtasalo, Joonas J.; Kotilainen, Aarno; Peltola, Pasi; Ekholm, Päivi; Hietanen, Susanna

    2018-03-01

    Iron (Fe) plays a key role in sedimentary diagenetic processes in coastal systems, participating in various redox reactions and influencing the burial of organic carbon. Large amounts of Fe enter the marine environment from boreal river catchments associated with dissolved organic matter (DOM) and as colloidal Fe oxyhydroxides, principally ferrihydrite. However, the fate of this Fe pool in estuarine sediments has not been extensively studied. Here we show that flocculation processes along a salinity gradient in an estuary of the northern Baltic Sea efficiently transfer Fe and OM from the dissolved phase into particulate material that accumulates in the sediments. Flocculation of Fe and OM is partially decoupled. This is likely due to the presence of discrete colloidal ferrihydrite in the freshwater Fe pool, which responds differently from DOM to estuarine mixing. Further decoupling of Fe from OM occurs during sedimentation. While we observe a clear decline with distance offshore in the proportion of terrestrial material in the sedimentary particulate organic matter (POM) pool, the distribution of flocculated Fe in sediments is modulated by focusing effects. Labile Fe phases are most abundant at a deep site in the inner basin of the estuary, consistent with input from flocculation and subsequent focusing. The majority of the labile Fe pool is present as Fe (II), including both acid-volatile sulfur (AVS)-bound Fe and unsulfidized phases. The ubiquitous presence of unsulfidized Fe (II) throughout the sediment column suggests Fe (II)-OM complexes derived from reduction of flocculated Fe (III)-OM, while other Fe (II) phases are likely derived from the reduction of flocculated ferrihydrite. Depth-integrated rates of Fe (II) accumulation (AVS-Fe + unsulfidized Fe (II) + pyrite) for the period 1970-2015 are greater in the inner basin of the estuary with respect to a site further offshore, confirming higher rates of Fe reduction in near-shore areas. Mössbauer 57Fe

  12. Research on sorption behavior of radionuclides under shallow land environment. Mechanism and standard methodologies for measurement of distribution coefficients of radionuclides

    International Nuclear Information System (INIS)

    Sakamoto, Yoshiaki; Tanaka, Tadao; Takebe, Shinichi; Nagao, Seiya; Ogawa, Hiromichi; Komiya, Tomokazu; Hagiwara, Shigeru

    2001-01-01

    This study consists of two categories' research works. One is research on sorption mechanism of radionuclides with long half-life, which are Technetium-99, TRU elements and U series radionuclides, on soil and rocks, including a development of database of distribution coefficients of radionuclides. The database on the distribution coefficients of radionuclides with information about measurement conditions, such as shaking method, soil characteristics and solution composition, has been already opened to the public (JAERI-DATABASE 20001003). Another study is investigation on a standard methodology of the distribution coefficient of radionuclide on soils, rocks and engineering materials in Japan. (author)

  13. Geochemistry and magnetic sediment distribution at the western boundary upwelling system of southwest Atlantic

    Science.gov (United States)

    Cruz, Anna P. S.; Barbosa, Catia F.; Ayres-Neto, Arthur; Munayco, Pablo; Scorzelli, Rosa B.; Amorim, Nívea Santos; Albuquerque, Ana L. S.; Seoane, José C. S.

    2018-02-01

    In order to investigate the chemical and magnetic characteristics of sediments of the western boundary upwelling system of Southwest Atlantic we analyzed magnetic susceptibility, grain size distribution, total organic carbon, heavy mineral abundance, Fe associated with Mössbauer spectra, and Fe and Mn of pore water to evaluate the deposition patterns of sediments. Four box-cores were collected along a cross-shelf transect. Brazil Current and coastal plume exert a primary control at the inner and outer shelf cores, which exhibited similar depositional patterns characterized by a high abundance of heavy minerals (mean 0.21% and 0.08%, respectively) and very fine sand, whereas middle shelf cores presented low abundances of heavy minerals (mean 0.03%) and medium silt. The inner shelf was dominated by sub-angular grains, while in middle and outer shelf cores well-rounded grains were found. The increasing Fe3+:Fe2+ ratio from the inner to the outer shelf reflects farther distance to the sediment source. The outer shelf presented well-rounded minerals, indicating abrasive processes as a result of transport by the Brazil Current from the source areas. In the middle shelf, cold-water intrusion of the South Atlantic Central Water contributes to the primary productivity, resulting in higher deposition of fine sediment and organic carbon accumulation. The high input of organic carbon and the decreased grain size are indicative of changes in the hydrodynamics and primary productivity fueled by the western boundary upwelling system, which promotes loss of magnetization due to the induction of diagenesis of iron oxide minerals.

  14. Zooming into Molecular Biomarker Distribution through Spatially Resolved Mass Spectrometry on Intact Sediment Sections

    Science.gov (United States)

    Wörmer, L.; Fuchser, J.; Alfken, S.; Elvert, M.; Schimmelmann, A.; Hinrichs, K. U.

    2016-02-01

    Marine microorganisms adapt to their habitat by structural modification of their membrane lipids. After sedimentation, and due to their persistence in the sedimentary record, the information archived in them remains available on geological time-scales. Thereby sedimentary lipid biomarkers become important informants of past environments. Conventional biomarker analysis is labor-intensive and requires cm-sized samples, temporal resolution is consequently low. We here present an approach, based on laser desorption ionization (LDI) coupled to ultra high resolution mass spectrometry, that avoids wet-chemical sample preparation and enables analysis directly on sediment sections at sub-mm spatial resolution. Our initial study targeted archaeal glycerol dialkyl glycerol tetraethers (GDGTs). GDGTS are ubiquitous and persistent components in marine sediments, and used in several, widely recognized paleoenvironmental proxies. Applied to an Eastern Mediterranean Sapropel layer, GDGT-profiles with previously unachieved temporal resolution were obtained, and pointed to a strong influence of high frequency cycles on sea-surface temperature and planktonic archaeal ecology. Spatial information furthermore revealed a new view on the fine-scale patchiness of lipid distribution. Following these pioneering studies, major developments are under way. A dedicated facility has been set up at MARUM/University of Bremen, which combines lipid biomarker and elemental analysis at sub-mm resolution (down to 50 µm). We present methods for other comprehensive lipid biomarkers (e.g. alkenones or sterols) that are currently being targeted; and the application of spatially resolved biomarker analysis to recent laminated sediments (Santa Barbara Basin), yielding informative profiles with subannual resolution. We also discuss criteria for analyte and sample selection, as well as the main potentialities and constraints of this new approach.

  15. Occurrence, compositional distribution, and toxicity assessment of pyrethroid insecticides in sediments from the fluvial systems of Chaohu Lake, Eastern China.

    Science.gov (United States)

    Wang, Ji-Zhong; Bai, Ya-Shu; Wu, Yakton; Zhang, Shuo; Chen, Tian-Hu; Peng, Shu-Chuan; Xie, Yu-Wei; Zhang, Xiao-Wei

    2016-06-01

    Surface sediment-associated synthetic pyrethroid insecticides (SPs) are known to pose high risks to the benthic organisms in Chaohu Lake, a shallow lake of Eastern China. However, the pollution status of the lake's tributaries and estuaries is still unknown. The present study was conducted to investigate the occurrence, compositional distribution, and toxicity of 12 currently used SPs in the surface sediments from four important tributaries, as well as in the sediment cores at their estuaries, using GC-MS for quantification. All SPs selected were detectable, with cypermethrin, es/fenvalerate, and permethrin dominant in both surface and core sediments, suggesting that these compounds were extensively applied. Urban samples contained the highest summed concentrations of the 12 SPs analyzed (Σ12SP) in both surface and core sediments compared with rural samples, suggesting that urban areas near aquatic environments posed high risks for SPs. The mean concentration of Σ12SP in surface sediments of each river was generally higher than that found in core sediments from its corresponding estuary, perhaps implying recent increases in SP usage. Surface sediments were significantly dominated by cypermethrin and permethrin, whereas core sediments were dominated by permethrin and es/fenvalerate. The compositional distributions demonstrated a spatial variation for surface sediments because urban sediments generally contained greater percentages of permethrin and cypermethrin, but rural sediments had significant levels of es/fenvalerate and cypermethrin. In all sediment cores, the percentage of permethrin gradually increased, whereas es/fenvalerate tended to decrease, from the bottom sediments to the top, indicating that the former represented fresh input, whereas the latter represented historical residue. Most urban samples would be expected to be highly toxic to benthic organisms due to the residue of SPs based on a calculation of toxic units (TUs) using toxicity data of the

  16. Electron energy distribution functions and transport coefficients relevant for air plasmas in the troposphere: impact of humidity and gas temperature

    Energy Technology Data Exchange (ETDEWEB)

    Gordillo-Vazquez, F J [Instituto de Astrofisica de Andalucia (IAA), CSIC, PO Box 3004, 18080 Granada (Spain); Donko, Z [Research Institute for Solid State Physics and Optics, H-1525 Budapest, PO Box, 49 (Hungary)

    2009-08-15

    A Boltzmann and Monte Carlo analysis of the electron energy distribution function (EEDF) and transport coefficients for air plasmas is presented for the conditions of the Earth troposphere where some transient luminous events (TLEs) such as blue jets, blue starters and gigantic jets have been observed. According to recent model results (Minschwaner et al 2004 J. Climate 17 1272) supported by the halogen occultation experiment, the relative humidity of the atmospheric air between 0 and 15 km can change between 15% and 100% depending on the altitude investigated and the ground temperature. The latter results cover a region of latitudes between -25 deg. S and +25 deg. N, that is, the Earth tropical region where lightning and TLE activity is quite high. The calculations shown here suggest that the relative humidity has a clear impact on the behaviour of the EEDF and magnitude of the transport coefficients of air plasmas at ground (0 km) and room temperature conditions (293 K). At higher altitudes (11 and 15 km), the influence of the relative humidity is negligible when the values of the gas temperature are assumed to be the 'natural' ones corresponding to those altitudes, that is, {approx}215 K (at 11 km) and {approx}198 K (at 15 km). However, it is found that a small enhancement (of maximum 100 K) in the background gas temperature (that could be reasonably associated with the TLE activity) would lead to a remarkable impact of the relative humidity on the EEDF and transport coefficients of air plasmas under the conditions of blue jets, blue starters and gigantic jets at 11 and 15 km. The latter effects are visible for relatively low reduced electric fields (E/N {<=} 25 Td) that could be controlling the afterglow kinetics of the air plasmas generated by TLEs. However, for much higher fields such as, for instance, 400 Td (representative of the fields in the streamer coronas and lightning leaders), the impact of increasing the relative humidity and gas

  17. Electron energy distribution functions and transport coefficients relevant for air plasmas in the troposphere: impact of humidity and gas temperature

    International Nuclear Information System (INIS)

    Gordillo-Vazquez, F J; Donko, Z

    2009-01-01

    A Boltzmann and Monte Carlo analysis of the electron energy distribution function (EEDF) and transport coefficients for air plasmas is presented for the conditions of the Earth troposphere where some transient luminous events (TLEs) such as blue jets, blue starters and gigantic jets have been observed. According to recent model results (Minschwaner et al 2004 J. Climate 17 1272) supported by the halogen occultation experiment, the relative humidity of the atmospheric air between 0 and 15 km can change between 15% and 100% depending on the altitude investigated and the ground temperature. The latter results cover a region of latitudes between -25 deg. S and +25 deg. N, that is, the Earth tropical region where lightning and TLE activity is quite high. The calculations shown here suggest that the relative humidity has a clear impact on the behaviour of the EEDF and magnitude of the transport coefficients of air plasmas at ground (0 km) and room temperature conditions (293 K). At higher altitudes (11 and 15 km), the influence of the relative humidity is negligible when the values of the gas temperature are assumed to be the 'natural' ones corresponding to those altitudes, that is, ∼215 K (at 11 km) and ∼198 K (at 15 km). However, it is found that a small enhancement (of maximum 100 K) in the background gas temperature (that could be reasonably associated with the TLE activity) would lead to a remarkable impact of the relative humidity on the EEDF and transport coefficients of air plasmas under the conditions of blue jets, blue starters and gigantic jets at 11 and 15 km. The latter effects are visible for relatively low reduced electric fields (E/N ≤ 25 Td) that could be controlling the afterglow kinetics of the air plasmas generated by TLEs. However, for much higher fields such as, for instance, 400 Td (representative of the fields in the streamer coronas and lightning leaders), the impact of increasing the relative humidity and gas temperature is only slightly

  18. Chaotic oscillations of the Klein-Gordon equation with distributed energy pumping and van der Pol boundary regulation and distributed time-varying coefficients

    Directory of Open Access Journals (Sweden)

    Bo Sun

    2014-09-01

    Full Text Available Consider the Klein-Gordon equation with variable coefficients, a van der Pol cubic nonlinearity in one of the boundary conditions and a spatially distributed antidamping term, we use a variable-substitution technique together with the analogy with the 1-dimensional wave equation to prove that for the Klein-Gordon equation chaos occurs for a class of equations and boundary conditions when system parameters enter a certain regime. Chaotic and nonchaotic profiles of solutions are illustrated by computer graphics.

  19. Distribution, Source, and Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons in Surface Sediment of Liaodong Bay, Northeast China

    Science.gov (United States)

    Xu, Shuang; Tao, Ping; Li, Yuxia; Guo, Qi; Zhang, Yan; Wang, Man; Jia, Hongliang; Shao, Mihua

    2018-01-01

    Sixteen polycyclic aromatic hydrocarbons (PAHs) were determined in surface sediments from Liaodong Bay, northeast China. The concentration levels of total PAHs (Σ16PAHs) in sediment were 11.0˜249.6 ng·g-1 dry weight (dw), with a mean value of 89.9 ng·g-1 dry weight (dw). From the point of the spatial distribution, high PAHs levels were found in the western areas of Liaodong Bay. In the paper, sources of PAHs were investigated by diagnostic ratios, which indicated that pyrogenic sources were the main sources of PAHs in the sediment of Liaodong Bay. Therefore, selected PAH levels in sediments were compared with Sediments Quality Guidelines (ERM-ERL indexes) for evaluation probable toxic effects on marine organism.

  20. Diversity and distribution of catechol 2, 3-dioxygenase genes in surface sediments of the Bohai Sea.

    Science.gov (United States)

    He, Peiqing; Li, Li; Liu, Jihua; Bai, Yazhi; Fang, Xisheng

    2016-05-01

    Catechol 2, 3-dioxygenase (C23O) is the key enzyme for aerobic aromatic degradation. Based on clone libraries and quantitative real-time polymerase chain reaction, we characterized diversity and distribution patterns of C23O genes in surface sediments of the Bohai Sea. The results showed that sediments of the Bohai Sea were dominated by genes related to C23O subfamily I.2.A. The samples from wastewater discharge area (DG) and aquaculture farm (KL) showed distinct composition of C23O genes when compared to the samples from Bohai Bay (BH), and total organic carbon was a crucial determinant accounted for the composition variation. C6BH12-38 and C2BH2-35 displayed the highest gene copies and highest ratios to the 16S rRNA genes in KL, and they might prefer biologically labile aromatic hydrocarbons via aquaculture inputs. Meanwhile, C7BH3-48 showed the highest gene copies and highest ratios to the 16S rRNA genes in DG, and this could be selective effect of organic loadings from wastewater discharge. An evident increase in C6BH12-38 and C7BH3-48 gene copies and reduction in diversity of C23O genes in DG and KL indicated composition perturbations of C23O genes and potential loss in functional redundancy. We suggest that ecological habitat and trophic specificity could shape the distribution of C23O genes in the Bohai Sea sediments. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. Heavy metals seasonal variability and distribution in Lake Qaroun sediments, El-Fayoum, Egypt

    Science.gov (United States)

    Redwan, Mostafa; Elhaddad, Engy

    2017-10-01

    This study was carried out to investigate the seasonal variability and distribution of heavy metals ;HMs; (Fe, Mn, Co, Cr, Cu, Ni, Pb, Zn and V) in the bottom sediments of Lake Qaroun, in Egypt. The samples were collected from 10 sites in summer and winter seasons in 2015. Total metals concentrations were measured using inductively coupled plasma spectrometer. Multivariate techniques were applied to analyse the distribution and potential source of heavy metals. The mean seasonal concentrations follow a descending order of Fe > Mn > V > Zn > Cr > Ni > Cu > Co > Pb. The mean concentrations of HMs in sediments during summer were higher than the concentrations during winter and above the average world shale values, except for Pb, suggesting potential adverse toxicity to aquatic organisms. All metals showed enrichment during summer and winter at sites S3 and S5 in the southeastern parts of the lake due to the heavy discharge of contaminants from El-Bats and El-Wadi drains. Principal component analysis results suggested two principal components controlling HMs variability in sediments, which accounted for 63.9% (factor 1: Co, Cr, Cu, Ni, Zn, Pb and V), 15.9% (factor 2: Mn and Fe) during summer, and 76.7% (factor 1: Fe, Co, Cr, Cu, Ni, Zn, Pb and V), 13.8% (factor 2: Mn) during winter of the total variance. Geo-accumulation index (Igeo) showed some pollution risk at the southeastern and southern parts (sites S3 and S5). Dilution during winter, concentration during summer, impact of non-point sources from different agricultural, industrial, municipal sewage and fish farms in the southern part of Lake Qaroun, adsorption and salt dissolution reactions and lithogenic sources are the main controlling factors for HMs in the study area. Monitoring of contaminant discharge at Lake Qaroun should be introduced for future remediation and management strategies.

  2. Allowance for effects of thermodynamic nonideality in sedimentation equilibrium distributions reflecting protein dimerization.

    Science.gov (United States)

    Wills, Peter R; Scott, David J; Winzor, Donald J

    2012-03-01

    This reexamination of a high-speed sedimentation equilibrium distribution for α-chymotrypsin under slightly acidic conditions (pH 4.1, I(M) 0.05) has provided experimental support for the adequacy of nearest-neighbor considerations in the allowance for effects of thermodynamic nonideality in the characterization of protein self-association over a moderate concentration range (up to 8 mg/mL). A widely held but previously untested notion about allowance for thermodynamic nonideality effects is thereby verified experimentally. However, it has also been shown that a greater obstacle to better characterization of protein self-association is likely to be the lack of a reliable estimate of monomer net charge, a parameter that has a far more profound effect on the magnitude of the measured equilibrium constant than any deficiency in current procedures for incorporating the effects of thermodynamic nonideality into the analysis of sedimentation equilibrium distributions reflecting reversible protein self-association. Copyright © 2011 Elsevier Inc. All rights reserved.

  3. Impact of particles on sediment accumulation in a drinking water distribution system.

    Science.gov (United States)

    Vreeburg, J H G; Schippers, D; Verberk, J Q J C; van Dijk, J C

    2008-10-01

    Discolouration of drinking water is one of the main reasons customers complain to their water company. Though corrosion of cast iron is often seen as the main source for this problem, the particles originating from the treatment plant play an important and potentially dominant role in the generation of a discolouration risk in drinking water distribution systems. To investigate this thesis a study was performed in a drinking water distribution system. In two similar isolated network areas the effect of particles on discolouration risk was studied with particle counting, the Resuspension Potential Method (RPM) and assessment of the total accumulated sediment. In the 'Control Area', supplied with normal drinking water, the discolouration risk was regenerated within 1.5 year. In the 'Research Area', supplied with particle-free water, this will take 10-15 years. An obvious remedy for controlling the discolouration risk is to improve the treatment with respect to the short peaks that are caused by particle breakthrough.

  4. Vertical distribution and anaerobic biodegradation of polycyclic aromatic hydrocarbons in mangrove sediments in Hong Kong, South China

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chun-Hua [Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Zhou, Hong-Wei [Department of Environmental Health Science, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou (China); Wong, Yuk-Shan [Department of Biology, The Hong Kong University of Science and Technology (Hong Kong); Tam, Nora Fung-Yee, E-mail: bhntam@cityu.edu.hk [Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

    2009-10-15

    The vertical distribution of polycyclic aromatic hydrocarbons (PAHs) at different sediment depths, namely 0-2 cm, 2-4 cm, 4-6 cm, 6-10 cm, 10-15 cm and 15-20 cm, in one of the most contaminated mangrove swamps, Ma Wan, Hong Kong was investigated. It was the first time to study the intrinsic potential of deep sediment to biodegrade PAHs under anaerobic conditions and the abundance of electron acceptors in sediment for anaerobic degradation. Results showed that the total PAHs concentrations (summation of 16 US EPA priority PAHs) increased with sediment depth. The lowest concentration (about 1300 ng g{sup -1} freeze-dried sediment) and the highest value (around 5000 ng g{sup -1} freeze-dried sediment) were found in the surface layer (0-2 cm) and deeper layer (10-15 cm), respectively. The percentage of high molecular weight (HMW) PAHs (4 to 6 rings) to total PAHs was more than 89% at all sediment depths. The ratio of phenanthrene to anthracene was less than 10 while fluoranthene to pyrene was around 1. Negative redox potentials (Eh) were recorded in all of the sediment samples, ranging from - 170 to - 200 mv, with a sharp decrease at a depth of 6 cm then declined slowly to 20 cm. The results suggested that HMW PAHs originated from diesel-powered fishing vessels and were mainly accumulated in deep anaerobic sediments. Among the electron acceptors commonly used by anaerobic bacteria, sulfate was the most dominant, followed by iron(III), nitrate and manganese(IV) was the least. Their concentrations also decreased with sediment depth. The population size of total anaerobic heterotrophic bacteria increased with sediment depth, reaching the peak number in the middle layer (4-6 cm). In contrast, the aerobic heterotrophic bacterial count decreased with sediment depth. It was the first time to apply a modified electron transport system (ETS) method to evaluate the bacterial activities in the fresh sediment under PAH stress. The vertical drop of the ETS activity suggested that

  5. Vertical distribution and anaerobic biodegradation of polycyclic aromatic hydrocarbons in mangrove sediments in Hong Kong, South China

    International Nuclear Information System (INIS)

    Li, Chun-Hua; Zhou, Hong-Wei; Wong, Yuk-Shan; Tam, Nora Fung-Yee

    2009-01-01

    The vertical distribution of polycyclic aromatic hydrocarbons (PAHs) at different sediment depths, namely 0-2 cm, 2-4 cm, 4-6 cm, 6-10 cm, 10-15 cm and 15-20 cm, in one of the most contaminated mangrove swamps, Ma Wan, Hong Kong was investigated. It was the first time to study the intrinsic potential of deep sediment to biodegrade PAHs under anaerobic conditions and the abundance of electron acceptors in sediment for anaerobic degradation. Results showed that the total PAHs concentrations (summation of 16 US EPA priority PAHs) increased with sediment depth. The lowest concentration (about 1300 ng g -1 freeze-dried sediment) and the highest value (around 5000 ng g -1 freeze-dried sediment) were found in the surface layer (0-2 cm) and deeper layer (10-15 cm), respectively. The percentage of high molecular weight (HMW) PAHs (4 to 6 rings) to total PAHs was more than 89% at all sediment depths. The ratio of phenanthrene to anthracene was less than 10 while fluoranthene to pyrene was around 1. Negative redox potentials (Eh) were recorded in all of the sediment samples, ranging from - 170 to - 200 mv, with a sharp decrease at a depth of 6 cm then declined slowly to 20 cm. The results suggested that HMW PAHs originated from diesel-powered fishing vessels and were mainly accumulated in deep anaerobic sediments. Among the electron acceptors commonly used by anaerobic bacteria, sulfate was the most dominant, followed by iron(III), nitrate and manganese(IV) was the least. Their concentrations also decreased with sediment depth. The population size of total anaerobic heterotrophic bacteria increased with sediment depth, reaching the peak number in the middle layer (4-6 cm). In contrast, the aerobic heterotrophic bacterial count decreased with sediment depth. It was the first time to apply a modified electron transport system (ETS) method to evaluate the bacterial activities in the fresh sediment under PAH stress. The vertical drop of the ETS activity suggested that the

  6. Correlation functions for the distribution coefficients of U(IV) and Pu(III) ions between aqueous nitric acid and 30% TBP in an aliphatic diluent

    Energy Technology Data Exchange (ETDEWEB)

    Geldard, J.F.; Beyerlein, A.L.; Phillips, L.

    1985-09-01

    Distribution coefficient correlations for U(IV) and Pu(III) are obtained in terms of a modified form of the total nitrate ion salting strength that was successfully used to obtain distribution coefficient correlations for U(VI) and Pu(IV) in the earlier work of G.L. Richardson. The modification of salting strength was needed to account for the fact that the U(IV) distribution coefficients measured under conditions where U(VI) is present consistently fall below those obtained when it is absent. The correlations were incorporated into the mixer-settler computer model PUBG, and in the simulation of a 20-stage 1B partitioning contactor, calculated product stream concentrations were in excellent agreement with experiment. Earlier mixer-settler computer models, which failed to account for U(IV) distribution coefficients, predicted that U(IV) remained in the aqueous product stream, which is contrary to the experimental measurements.

  7. Correlation functions for the distribution coefficients of U(IV) and Pu(III) ions between aqueous nitric acid and 30% TBP in an aliphatic diluent

    International Nuclear Information System (INIS)

    Geldard, J.F.; Beyerlein, A.L.; Phillips, L.

    1985-01-01

    Distribution coefficient correlations for U(IV) and Pu(III) are obtained in terms of a modified form of the total nitrate ion salting strength that was successfully used to obtain distribution coefficient correlations for U(VI) and Pu(IV) in the earlier work of G.L. Richardson. The modification of salting strength was needed to account for the fact that the U(IV) distribution coefficients measured under conditions where U(VI) is present consistently fall below those obtained when it is absent. The correlations were incorporated into the mixer-settler computer model PUBG, and in the simulation of a 20-stage 1B partitioning contactor, calculated product stream concentrations were in excellent agreement with experiment. Earlier mixer-settler computer models, which failed to account for U(IV) distribution coefficients, predicted that U(IV) remained in the aqueous product stream, which is contrary to the experimental measurements

  8. Depth profile distribution of Cr, Cu, Co, Ni and Pb in the sediment cores of Mumbai Harbour Bay

    International Nuclear Information System (INIS)

    Madhuparna, D.; Hemalatha, P.; Raj, Sanu S.; Jha, S.K.; Tripathi, R.M.

    2014-01-01

    Estuarine and coastal sediments act as ultimate sink for trace metals that are discharged into the aquatic environment. Sources of environmental contaminants to the coastal system are numerous and may enter the estuarine environment via a number of pathways Mumbai Harbour Bay on the western coast of India, receives low level nuclear wastes and industrial and domestic sewage waste from the surrounding dwellings. Also, the bay is extensively exploited for various other local activities. The present study was carried out in the bay sediment cores to investigate the depth profile distribution of trace element concentration. Biologically significant toxic elements such as Cr, Cu, Co, Ni and Pb were estimated in the sediment cores to find out pattern of distribution in the sediment bed to follow the accumulation of elements with respect to depth

  9. Distribution of branched GDGTs in surface sediments from the Colville River, Alaska: Implications for the MBT'/CBT paleothermometer in Arctic marine sediments

    Science.gov (United States)

    Hanna, Andrea J. M.; Shanahan, Timothy M.; Allison, Mead A.

    2016-07-01

    Significant climate fluctuations in the Arctic over the recent past, and additional predicted future temperature changes, highlight the need for high-resolution Arctic paleoclimate records. Arctic coastal environments supplied with terrigenous sediment from Arctic rivers have the potential to provide annual to subdecadal resolution records of climate variability over the last few millennia. A potential tool for paleotemperature reconstructions in these marine sediments is the revised methylation index of branched tetraethers (MBT')/cyclization ratio of branched tetraethers (CBT) proxy based on branched glycerol dialkyl glycerol tetraethers (brGDGTs). In this study, we examine the source of brGDGTs in the Colville River, Alaska, and the adjacent Simpson Lagoon and reconstruct temperatures from Simpson Lagoon sediments to evaluate the applicability of this proxy in Arctic estuarine environments. The Colville catchment soils, fluvial sediments, and estuarine sediments contain statistically similar brGDGT distributions, indicating that the brGDGTs throughout the system are soil derived with little alteration from in situ brGDGT production in the river or coastal waters. Temperatures reconstructed from the MBT'/CBT indices for surface samples show good agreement with regional summer (June through September) temperatures, suggesting a seasonal bias in Arctic temperature reconstructions from the Colville system. In addition, we reconstruct paleotemperatures from an estuarine sediment core that spans the last 75 years, revealing an overall warming trend in the twentieth century that is consistent with trends observed in regional instrumental records. These results support the application of this brGDGT-based paleotemperature proxy for subdecadal-scale summer temperature reconstructions in Arctic estuaries containing organic material derived from sediment-laden, episodic rivers.

  10. Thiosulfate and Sulfite Distributions in Porewater of Marine-Sediments Related to Manganese, Iron, and Sulfur Geochemistry

    DEFF Research Database (Denmark)

    Thamdrup, B; Finster, Kai; Fossing, Henrik

    1994-01-01

    Depth distributions of thiosulfate (S2O32-) and sulfite (SO32-) were measured in the porewaters of a Danish salt marsh and subtidal marine sediments by HPLC analysis after derivatization with DTNP [2,2'-dithiobis(5-nitropyridine)]. The distributions were compared to the redox zonation as indicate...

  11. Distribution of biologic, anthropogenic, and volcanic constituents as a proxy for sediment transport in the San Francisco Bay Coastal System

    Science.gov (United States)

    McGann, Mary; Erikson, Li H.; Wan, Elmira; Powell, Charles; Maddocks, Rosalie F.; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

    2013-01-01

    Although conventional sediment parameters (mean grain size, sorting, and skewness) and provenance have typically been used to infer sediment transport pathways, most freshwater, brackish, and marine environments are also characterized by abundant sediment constituents of biological, and possibly anthropogenic and volcanic, origin that can provide additional insight into local sedimentary processes. The biota will be spatially distributed according to its response to environmental parameters such as water temperature, salinity, dissolved oxygen, organic carbon content, grain size, and intensity of currents and tidal flow, whereas the presence of anthropogenic and volcanic constituents will reflect proximity to source areas and whether they are fluvially- or aerially-transported. Because each of these constituents have a unique environmental signature, they are a more precise proxy for that source area than the conventional sedimentary process indicators. This San Francisco Bay Coastal System study demonstrates that by applying a multi-proxy approach, the primary sites of sediment transport can be identified. Many of these sites are far from where the constituents originated, showing that sediment transport is widespread in the region. Although not often used, identifying and interpreting the distribution of naturally-occurring and allochthonous biologic, anthropogenic, and volcanic sediment constituents is a powerful tool to aid in the investigation of sediment transport pathways in other coastal systems.

  12. Spatial distribution and risk assessment of heavy metals and As pollution in the sediments of a shallow lake.

    Science.gov (United States)

    Deng, Jiancai; Wang, Yuansheng; Liu, Xin; Hu, Weiping; Zhu, Jinge; Zhu, Lin

    2016-05-01

    The concentrations and spatial distributions of eight heavy metals in surface sediments and sediment core samples from a shallow lake in China were investigated to evaluate the extent of the contamination and potential ecological risks. The results showed that the heavy metal concentrations were higher in the northern and southwestern lake zones than those in the other lake zones, with lower levels of As, Hg, Zn, Cu, Pb, Cr, and Ni primarily observed in the central and eastern lake regions and Cd primarily confined to areas surrounding the lake. The concentrations of the eight heavy metals in the sediment profiles tended to decrease with increasing sediment depth. The contents of Ni, Cu, Zn, Pb, and Cd in the surface sediment were approximately 1.23-18.41-fold higher than their background values (BVs), whereas the contents of Cr, As, and Hg were nearly identical to their BVs. The calculated pollution load index (PLI) suggested that the surface sediments of this lake were heavily polluted by these heavy metals and indicated that Cd was a predominant contamination factor. The comprehensive potential ecological risk index (PERI) in the surface sediments ranged from 99.2 to 2882.1, with an average of 606.1. Cd contributed 78.7 % to the PERI, and Hg contributed 8.4 %. Multivariate statistical analyses revealed that the surface sediment pollution with heavy metals mainly originated from industrial wastewater discharged by rivers located in the western and northwestern portion of the lake.

  13. Evaluation of sorption distribution coefficient of Cs onto granite using sorption data collected in sorption database and sorption model

    International Nuclear Information System (INIS)

    Nagasaki, S.

    2013-01-01

    Based on the sorption distribution coefficients (K d ) of Cs onto granite collected from the JAERI Sorption Database (SDB), the parameters for a two-site model without the triple-layer structure were optimized. Comparing the experimentally measured K d values of Cs onto Mizunami granite carried out by JAEA with the K d values predicted by the model, the effect of the ionic strength on the K d values of Cs onto granite was evaluated. It was found that K d values could be determined using the content of biotite in granite at a sodium concentration ([Na]) of 1 x 10 -2 to 5 x 10 -1 mol/dm 3 . It was suggested that in high ionic strength solutions, the sorption of Cs onto other minerals such as microcline should also be taken into account. (author)

  14. Evaluation of sorption distribution coefficient of Cs onto granite using sorption data collected in sorption database and sorption model

    Energy Technology Data Exchange (ETDEWEB)

    Nagasaki, S., E-mail: nagasas@mcmaster.ca [McMaster Univ., Hamilton, Ontario (Canada)

    2013-07-01

    Based on the sorption distribution coefficients (K{sub d}) of Cs onto granite collected from the JAERI Sorption Database (SDB), the parameters for a two-site model without the triple-layer structure were optimized. Comparing the experimentally measured K{sub d} values of Cs onto Mizunami granite carried out by JAEA with the K{sub d} values predicted by the model, the effect of the ionic strength on the K{sub d} values of Cs onto granite was evaluated. It was found that K{sub d} values could be determined using the content of biotite in granite at a sodium concentration ([Na]) of 1 x 10{sup -2} to 5 x 10{sup -1} mol/dm{sup 3} . It was suggested that in high ionic strength solutions, the sorption of Cs onto other minerals such as microcline should also be taken into account. (author)

  15. The determination of the cesium distribution coefficient of the interim storage soil from Abadia de Goias, Go, Brazil

    International Nuclear Information System (INIS)

    Marumo, J.T.; Suarez, A.A.

    1989-01-01

    In September, 1987, an unauthorized removal of a cesium-therapy unit and its violation caused an accident, where several places of Goiania's city, capital of Goias, Brazil, were contaminated. The removal of the radioactive wastes generated from decontamination process, was made to Abadia de Goias city (near Goiania), where an interim storage was constructed. Soil samples collected from the 57th Street (Goiania) and from the interim storage permitted to determine, through static method, the cesium distribution coefficient for different cesium solution concentrations. Those results allows for some migration/retention evaluations in disposal site selection. Some soils parameters (water content, density, granulometric analysis, etc) as well as clay minerals constituents were also determined. (author) [pt

  16. Anthropogenic radionuclide fluxes and distribution in bottom sediments of the cooling basin of the Ignalina Nuclear Power Plant

    International Nuclear Information System (INIS)

    Marčiulionienė, D.; Mažeika, J.; Lukšienė, B.; Jefanova, O.; Mikalauskienė, R.; Paškauskas, R.

    2015-01-01

    Based on γ-ray emitting artificial radionuclide spectrometric measurements, an assessment of areal and vertical distribution of 137 Cs, 60 Co and 54 Mn activity concentrations in bottom sediments of Lake Drūkšiai was performed. Samples of bottom sediments from seven monitoring stations within the cooling basin were collected in 1988–1996 and 2007–2010 (in July–August). For radionuclide areal distribution analysis, samples from the surface 0–5 cm layer were used. Multi sample cores sliced 2 cm, 3 cm or 5 cm thick were used to study the vertical distribution of radionuclides. The lowest 137 Cs activity concentrations were obtained for two stations that were situated close to channels with radionuclide discharges, but with sediments that had a significantly smaller fraction of organic matter related to finest particles and consequently smaller radionuclide retention potential. The 137 Cs activity concentration was distributed quite evenly in the bottom sediments from other investigated monitoring stations. The highest 137 Cs activity concentrations in the bottom sediments of Lake Drūkšiai were measured in the period of 1988–1989; in 1990, the 137 Cs activity concentrations slightly decreased and they varied insignificantly over the investigation period. The obtained 238 Pu/ 239,240 Pu activity ratio values in the bottom sediments of Lake Drūkšiai represented radioactive pollution with plutonium from nuclear weapon tests. Higher 60 Co and 54 Mn activity concentrations were observed in the monitoring stations that were close to the impact zones of the technical water outlet channel and industrial rain drainage system channel. 60 Co and 54 Mn activity concentrations in the bottom sediments of Lake Drūkšiai significantly decreased when operations at both INPP reactor units were stopped. The vertical distribution of radionuclides in bottom sediments revealed complicated sedimentation features, which may have been affected by a number of natural and

  17. Utilization of bathymetry data to examine lead sediment contamination distributions in Lake Ontario

    Directory of Open Access Journals (Sweden)

    Chris H. Marvin

    2016-06-01

    Full Text Available Bathymetry data offer interesting opportunities for the analysis of contaminant distribution patterns. This research utilized lead surficial sediment sample data from Lake Ontario that were collected by the Canada Centre for Inland Waters in 1968 and 1998. Traditionally, two-dimensional analyses such as dot maps or proportional circle representation have been utilized to examine pollutant levels. Generating area estimates allows for expanded spatial analysis of contaminant distribution patterns. Lake-wide surfaces were derived using the ordinary kriging technique. These were then layered on bathymetry data to examine three-dimensional relationships between observed pollution patterns and lake-bottom features. Spatial variability was observed in both the 1968 and 1998 datasets. Contamination levels in 1998 dropped substantially, especially in areas that were previously the most heavily polluted and above the Probable Effect Level (4660.23 km2 or 26.72% of the common analysis area lake-bottom in 1998 versus 6189.07 km2 or 62.00% in 1968. Conversely, areas below the Threshold Effect Level increased from 922.09 km2 (5.29% in 1968 to 3484.22 km2 (19.98% in 1998. In both years, shallow and sill/ridge areas tended to have lower levels of contamination than deeper lake basins or contaminant inflow areas. The 1968 dataset likely provides a more detailed estimation surface as there were more points available for interpolation procedures. The kriging surfaces when combined with bathymetry, sedimentology information, and knowledge of physical processes provide a comprehensive illustration of the contaminant distributions whether they are high (1968 or when loadings are significantly reduced (1998. The results have implications for future sediment assessment programs and survey design on a lake-wide basis. The bathymetry data allowed for enhanced interpretation and an improved understanding of observed lead pollution patterns.

  18. Distribution of rare earth elements in the estuarine and coastal sediments of the Daliao River System, China

    International Nuclear Information System (INIS)

    Chunye Lin; Shaoqing Liu; Mengchang He; Ruiping Li

    2013-01-01

    The Daliao River System (DRS) estuary in Liaodong Bay features a highly industrial, urbanized, and agricultural catchment. The objective of this study was to determine the content, behavior, and distribution of the rare earth elements (REEs) in the estuarine and coastal sediments. To this end, 35 sediment samples were collected from the estuarine and coastal area and analyzed for REEs, Fe, Al, and Mn. The mean concentrations in mg kg -1 of the sediments were 33.4 (La), 64.1 (Ce), 7.9 (Pr), 29.0 (Nd), 5.4 (Sm), 1.2 (Eu), 4.2 (Gd), 0.78 (Tb), 4.0 (Dy), 0.84 (Ho), 2.3 (Er), 0.40 (Tm), 2.3 (Yb), and 0.37 (Lu). The REE concentrations in the sediments were significantly correlated with one another (r 2 = 0.959-0.988) and the concentrations of Fe, Al, and Mn (r 2 = 0.768-0.870). The total concentration ΣREE ranged from 73.5 to 203.5 mg kg -1 , with an average of 156.0 mg kg -1 being observed, and generally higher in the estuarine sediments than in the coastal sediments, most likely due to the salt-induced coagulation of river colloids and subsequently their accumulation at the estuarine bottom. The ratio of light REEs (ΣLREE) to heavy REEs (ΣHREE) was 9.4. Chondrite-normalized REE distributions were observed to be similar for the estuarine and coastal sediments, riverine suspended particles, and watershed soils of the DRS with higher LRRE enrichment than HREE and greater Eu depletion than Ce depletion. These results demonstrate that neither geochemical processes that carry soils to estuarine sediments nor long-term industrial and agricultural activities alter the distribution or fractionation of the REEs in the study area. (author)

  19. Environment-Dependent Distribution of the Sediment nifH-Harboring Microbiota in the Northern South China Sea

    Science.gov (United States)

    Yang, Jinying; Li, Jing; Luan, Xiwu; Zhang, Yunbo; Gu, Guizhou; Xue, Rongrong; Zong, Mingyue; Klotz, Martin G.

    2013-01-01

    The South China Sea (SCS), the largest marginal sea in the Western Pacific Ocean, is a huge oligotrophic water body with very limited influx of nitrogenous nutrients. This suggests that sediment microbial N2 fixation plays an important role in the production of bioavailable nitrogen. To test the molecular underpinning of this hypothesis, the diversity, abundance, biogeographical distribution, and community structure of the sediment diazotrophic microbiota were investigated at 12 sampling sites, including estuarine, coastal, offshore, deep-sea, and methane hydrate reservoirs or their prospective areas by targeting nifH and some other functional biomarker genes. Diverse and novel nifH sequences were obtained, significantly extending the evolutionary complexity of extant nifH genes. Statistical analyses indicate that sediment in situ temperature is the most significant environmental factor influencing the abundance, community structure, and spatial distribution of the sediment nifH-harboring microbial assemblages in the northern SCS (nSCS). The significantly positive correlation of the sediment pore water NH4+ concentration with the nifH gene abundance suggests that the nSCS sediment nifH-harboring microbiota is active in N2 fixation and NH4+ production. Several other environmental factors, including sediment pore water PO43− concentration, sediment organic carbon, nitrogen and phosphorus levels, etc., are also important in influencing the community structure, spatial distribution, or abundance of the nifH-harboring microbial assemblages. We also confirmed that the nifH genes encoded by archaeal diazotrophs in the ANME-2c subgroup occur exclusively in the deep-sea methane seep areas, providing for the possibility to develop ANME-2c nifH genes as a diagnostic tool for deep-sea methane hydrate reservoir discovery. PMID:23064334

  20. A preliminary investigation of the distribution of heavy metals in surface sediments of the Cona tidal marsh (Venice Lagoon)

    International Nuclear Information System (INIS)

    Bernardi, S.; Costa, F.; Vazzoler, S.; Zonta, R.

    1988-01-01

    Data are from the two series of surface sediment sampling in an interface area between the Venice Lagoon and the mainland. The distribution of heavy metals gives a correlation with polluted sourcesites-identified in the channel systems with a highly polluted input-and allows us to identify the localities of accumulation. Restricted to the estuary of the river tributary transporting a high concentration of pollutants into a tidal marsh area of the lagoon, the study shows the effect of the fresh water forcing to distribute heavy metals on surface sediments. Within the scope of this preliminary investigation, indications from sampling identify a sector of the 'palude of Cona' in this estuary, which is highly suitable for detailed studies on precesses affecting heavy-metal distributions in bottom surface sediments of shallow-water areas

  1. Evaluation of trace elements distribution in water, sediment, soil and cassava plant in Muria peninsula environment by NAA method

    International Nuclear Information System (INIS)

    Muryono, H.; Sumining; Agus Taftazani; Kris Tri Basuki; Sukarman, A.

    1999-01-01

    The evaluation of trace elements distribution in water, sediment, soil and cassava plant in Muria peninsula by NAA method were done. The nuclear power plant (NPP) and the coal power plant (CPP) will be built in Muria peninsula, so, the Muria peninsula is an important site for samples collection and monitoring of environment. River-water, sediment, dryland-soil and cassava plant were choosen as specimens samples from Muria peninsula environment. The analysis result of trace elements were used as a contributed data for environment monitoring before and after NPP was built. The trace elements in specimens of river-water, sediment, dryland-soil and cassava plant samples were analyzed by INAA method. It was found that the trace elements distribution were not evenly distributed. Percentage of trace elements distribution in river-water, sediment, dryland-soil and cassava leaves were 0.00026-0.037% in water samples, 0.49-62.7% in sediment samples, 36.29-99.35% in soil samples and 0.21-99.35% in cassava leaves. (author)

  2. Evaluation of trace elements distribution in water, sediment, soil and cassava plant in Muria peninsula environment by NAA method

    Energy Technology Data Exchange (ETDEWEB)

    Muryono, H.; Sumining; Agus Taftazani; Kris Tri Basuki; Sukarman, A. [Yogyakarta Nuclear Research Center, Yogyakarta (Indonesia)

    1999-10-01

    The evaluation of trace elements distribution in water, sediment, soil and cassava plant in Muria peninsula by NAA method were done. The nuclear power plant (NPP) and the coal power plant (CPP) will be built in Muria peninsula, so, the Muria peninsula is an important site for samples collection and monitoring of environment. River-water, sediment, dryland-soil and cassava plant were choosen as specimens samples from Muria peninsula environment. The analysis result of trace elements were used as a contributed data for environment monitoring before and after NPP was built. The trace elements in specimens of river-water, sediment, dryland-soil and cassava plant samples were analyzed by INAA method. It was found that the trace elements distribution were not evenly distributed. Percentage of trace elements distribution in river-water, sediment, dryland-soil and cassava leaves were 0.00026-0.037% in water samples, 0.49-62.7% in sediment samples, 36.29-99.35% in soil samples and 0.21-99.35% in cassava leaves. (author)

  3. Distribution and characteristics of organic micropollutants in surface sediments from Bohai Sea

    International Nuclear Information System (INIS)

    Liu Wenxin; Chen Jianglin; Lin Xiumei; Tao Shu

    2006-01-01

    Spatial distribution and compositional characteristics of PAHs, DDTs and PCBs in surface sediments from Bohai Sea were investigated. Proportion of LMW PAHs at Jinzhou Bay was significant, due probably to the petrogenic sources from neighboring oil wells and plants, while HMW PAHs were dominant in the other sea areas, inferred pyrogenic origins mainly from coal or petroleum combustion. The average ERL quotient for the PAH species in Qinhuangdao and Liaodong Bay indicated relatively stronger potential ecological risk. The concentration ratios of DDT to metabolites (DDD + DDE) exceeded 1.0 in the coastal areas of Qinhuangdao, Liaodong Bay and Bohai Bay, demonstrated some recent inputs of DDT nearby, and DDD as the major degradation product. The concentrations of PCBs were generally low, however, the contents of DDTs were greater than the ERL guidelines in the coastal areas of Qinhuangdao, Liaodong Bay and Bohai Bay, and suggested the potential ecological risk. - The recent inputs of DDT in surface sediments at some sites of Bohai Sea indicated potential ecological risk

  4. Distribution of pesticides and PCBs in sediments of agricultural drains in the Culiacan Valley, Sinaloa, Mexico.

    Science.gov (United States)

    García-de la Parra, Luz María; Cervantes-Mojica, L Juleny; González-Valdivia, Carolina; Martínez-Cordero, Francisco J; Aguilar-Zárate, Gabriela; Bastidas-Bastidas, Pedro; Betancourt-Lozano, Miguel

    2012-10-01

    Agriculture is one of the most important economic activities in Sinaloa, Mexico. The Culiacan Valley is an extensive agricultural region characterized by a variety of crops with high-yield productions. In this study, concentrations of organochlorine (OCPs) and organophosphorus (OPs) pesticides and polychlorobiphenyls (PCBs) were determined in sediments of the agricultural drainage system of Culiacan Valley. Overall, 32 compounds were detected, with concentrations widely ranging from 0.03 to 1 294 ng g(-1) dry weight. OCP concentrations (15) ranged from 0.1 to 20.19 ng g(-1) dw. OP concentrations (8) ranged from 0.03 to 1294 ng g(-1) dw, and diazinon was the compound with the highest concentration. PCB concentrations were also determined and varied from 0.05 to 3.29 ng g(-1) dw. Other compounds detected included permethrin, triadimefon, and fipronil. The central zone registered the higher concentrations and the greatest number of compounds, which could be related to the occurrence of horticultural fields in this zone. According to sediment quality guidelines, the compounds exceeding the probable effect level were γ-HCH, p,p'-DDT and p,p'-DDE, while the pesticides above the maximum permissible concentration were endosulfan, azinphos methyl, diazinon, dichlorvos, and permethrin. Although Sinaloa is an important agricultural crop producer in northwest Mexico, there are not many studies dealing with pesticide distribution in agricultural areas.

  5. Distributions of nitrated polycyclic aromatic hydrocarbons in the sediment of Osaka Bay, Japan.

    Science.gov (United States)

    Uno, Seiichi; Tanaka, Hiroyuki; Kokushi, Emiko; Bacolod, Eugene T; Koyama, Jiro

    2017-11-30

    The distributions of 15 nitrated polycyclic aromatic hydrocarbons (NPAHs) in sediments collected at 44 sites throughout Osaka Bay, Japan were examined. The highest total NPAHs, with a concentration of 1949ng/kg dry weight, were detected near the city of Amagasaki. Some sites near the cities of Osaka, Kishiwada, sand Sakai registered ng/kg levels of NPAHs, but individual NPAH concentrations were relatively lower than those in previous studies. The sources were estimated using principal component analysis, and NPAHs were derived from exhaust gases of automobiles and industries at some sites. However, our results suggest that it is difficult to estimate the source, especially in coastal areas near big cities and large industrial areas, because the generation pathways between parent polycyclic aromatic hydrocarbons (PAHs) and nitrated PAHs are slightly different, and the ratio of PAHs and NPAHs could not be accurately reflect the characters of sources in sediments especially at coastal areas with large-scale industrial zones. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Radionuclide distributions in sediments of marine areas used for dumping solidified radioactive wastes

    International Nuclear Information System (INIS)

    Bowen, V.T.; Livingston, H.D.

    A number of sediment samples, collected both by coring and by grabbing, from the shallow Pacific solid waste radioactive dump site and from the Atlantic dump site, have been analyzed carefully for a number of long-lived radionuclides. Both dump sites yielded samples that were expected to serve as controls, collected at considerable distance from any visually-located waste containers, as well as other samples that were collected close to identified waste drums, some of which showed evidence of physical disintegration. The Atlantic site shows evidence of wide-spread, general contamination, with 137 Cs and possibly with 241 Am. The Pacific site is perhaps less generally contaminated with 137 Cs, but shows evidence of widespread general contamination with several transuranic nuclides. Samples collected near to identified waste containers, at both sites, show that significant portions of leached radioactivity ( 137 Cs, 239 240 Pu, 238 Pu, 241 Am, 242 Cm, and 244 Cm) are immobilized by the sediments within very short distances, possibly measured in meters or tens of meters. The data also suggest considerable differences among the horizontal trajectories of the various leached transuranic elements. It is argued that careful study of nuclide distributions around such old waste containers would provide data of great value in helping to predict long-term behavior of radionuclides released to marine environments

  7. PAHs distribution in sediments associated with gas hydrate and oil seepage from the Gulf of Mexico.

    Science.gov (United States)

    Wang, Cuiping; Sun, Hongwen; Chang, Ying; Song, Zhiguang; Qin, Xuebo

    2011-12-01

    Six sediment samples collected from the Gulf of Mexico were analyzed. Total concentrations of the PAHs ranged from 52 to 403 ng g(-1) dry weight. The lowest PAH concentration without 5-6 rings PAHs appeared in S-1 sample associated with gas hydrate or gas venting. Moreover, S-1 sample had the lowest organic carbon content with 0.85% and highest reduced sulfur level with 1.21% relative to other samples. And, analysis of the sources of PAHs in S-1 sample indicated that both pyrogenic and petrogenic sources, converserly, while S-8, S-10 and S-11 sample suggested petrogenic origin. The distribution of dibenzothiophene, fluorine and dibenzofuran and the maturity parameters of triaromatic steranes suggested that organic matters in S-1 sample were different from that in S-8, S-10 and S-11 sample. This study suggested that organic geochemical data could help in distinguish the characteristic of sediment associated with gas hydrate or with oil seepage. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Effects of Void Uncertainties on Pin Power Distributions and the Void Reactivity Coefficient for a 10X10 BWR Assembly

    International Nuclear Information System (INIS)

    Jatuff, F.; Krouthen, J.; Helmersson, S.; Chawla, R.

    2004-01-01

    A significant source of uncertainty in Boiling Water Reactor physics is associated with the precise characterisation of the axially-dependent neutron moderation properties of the coolant inside the fuel assembly channel, and the corresponding effects on reactor physics parameters such as the lattice neutron multiplication, the neutron migration length, and the pin-by-pin power distribution. In this paper, the effects of particularly relevant void fraction uncertainties on reactor physics parameters have been studied for a BWR assembly of type Westinghouse SVEA-96 using the CASMO-4, HELIOS/PRESTO-2 and MCNP4C codes. The SVEA-96 geometry is characterised by the sub-division of the assembly into four different sub-bundles by means of an inner bypass with a cruciform shape. The study has covered the following issues: (a) the effects of different cross-section data libraries on the void coefficient of reactivity, for a wide range of void fractions; (b) the effects due to a heterogeneous vs. homogeneous void distribution inside the sub-bundles; and (c) the consequences of partly inserted absorber blades producing different void fractions in different sub-bundles. (author)

  9. Robust Exponential Synchronization for a Class of Master-Slave Distributed Parameter Systems with Spatially Variable Coefficients and Nonlinear Perturbation

    Directory of Open Access Journals (Sweden)

    Chengdong Yang

    2015-01-01

    Full Text Available This paper addresses the exponential synchronization problem of a class of master-slave distributed parameter systems (DPSs with spatially variable coefficients and spatiotemporally variable nonlinear perturbation, modeled by a couple of semilinear parabolic partial differential equations (PDEs. With a locally Lipschitz constraint, the perturbation is a continuous function of time, space, and system state. Firstly, a sufficient condition for the robust exponential synchronization of the unforced semilinear master-slave PDE systems is investigated for all admissible nonlinear perturbations. Secondly, a robust distributed proportional-spatial derivative (P-sD state feedback controller is desired such that the closed-loop master-slave PDE systems achieve exponential synchronization. Using Lyapunov’s direct method and the technique of integration by parts, the main results of this paper are presented in terms of spatial differential linear matrix inequalities (SDLMIs. Finally, two numerical examples are provided to show the effectiveness of the proposed methods applied to the robust exponential synchronization problem of master-slave PDE systems with nonlinear perturbation.

  10. Distribution, partitioning and sources of polycyclic aromatic hydrocarbons in the water–SPM–sediment system of Lake Chaohu, China

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Ning [MOE Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China); State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); He, Wei; Kong, Xiang-Zhen; Liu, Wen-Xiu; He, Qi-Shuang; Yang, Bin; Wang, Qing-Mei; Yang, Chen; Jiang, Yu-Jiao [MOE Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China); Jorgensen, Sven Erik [Section of Toxicology and Environmental Chemistry, Institute A, University of Copenhagen, University Park 2, DK 2100, Copenhagen Ø (Denmark); Xu, Fu-Liu, E-mail: xufl@urban.pku.edu.cn [MOE Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China); Zhao, Xiao-Li, E-mail: zhaoxiaoli_zxl@126.com [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China)

    2014-10-15

    The residual levels of polycyclic aromatic hydrocarbons (PAHs) in the water, suspended particular matter (SPM) and sediment from Lake Chaohu were measured with a gas chromatograph–mass spectrometer (GC–MS). The spatial–temporal distributions and the SPM–water partition of PAHs and their influencing factors were investigated. The potential sources and contributions of PAHs in the sediment were estimated by positive matrix factorization (PMF) and probabilistic stable isotopic analysis (PSIA). The results showed that the average residual levels of total PAHs (PAH16) in the water, SPM and sediment were 170.7 ± 70.8 ng/L, 210.7 ± 160.7 ng/L and 908.5 ± 1878.1 ng/g dry weight, respectively. The same spatial distribution trend of PAH16 in the water, SPM and sediment was found from high to low: river inflows > western lake > eastern lake > water source area. There was an obvious seasonal trend of PAH16 in the water, while no obvious seasonal trend was found in the SPM. The residues and distributions of PAHs in the water, SPM and sediment relied heavily on carbon content. Significant Pearson correlations were found between LogK{sub oc} and LogK{sub ow} as well as some hydro-meteorological factors. Three major sources of PAHs including coal and biomass combustions, and vehicle emissions were identified. - Highlights: • Highest residual level of total PAHs in the SPM was detected. • Similar spatial trend of PAH16 in the water, SPM and sediment. • PAHs distributions in the water-sediment system relied heavily on organic carbon. • Correlations between LogK{sub oc} and LogK{sub ow} as well as hydro-meteorological factors. • Coal and biomass combustions and vehicle emissions were three major sources of PAHs.

  11. Spatial distribution and pollution evaluation of heavy metals in Yangtze estuary sediment.

    Science.gov (United States)

    Liu, Ruimin; Men, Cong; Liu, Yongyan; Yu, Wenwen; Xu, Fei; Shen, Zhenyao

    2016-09-15

    To analyze the spatial distribution patterns and ecological risks of heavy metals, 30 sediment samples were taken in the Yangtze River Estuary (YRE) in May 2011. The content of Al, As, Cr, Cu, Fe, Mn, Ni and Pb increased as follows: inner-regionpollutants. What is more, the greatest contaminated area appeared at the river mouth of the south branch of YRE. In Tucker 3, considering the fractions of metals, Mn turned to be the severest pollutant and As did not contribute too much to the contamination of the YRE. That was most probably because that Mn was closely related to the carbonate-associated (CARB) and As was related to organic-associated (OM) which is more stable than CARB. The fractions played an important role in the contamination assessment of heavy metals. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Radionuclide distributions in deep-ocean sediment cores. Progress report, 1 October 1976 -- 31 December 1977

    International Nuclear Information System (INIS)

    Bowen, V.T.

    1978-04-01

    Disruption, in the past year, of the supply of 237 Pu tracer from Oak Ridge caused us to put more of effort into analyses of core samples previously collected, and into data collation, than into the laboratory experiments originally projected. Accompanying this report are two review papers, one for a Congressional Committee and one in press, a report in press of a device for conducting microbiological tracer experiments under controlled atmospheres, and a description of radionuclide distributions in sediments of Atlantic and Pacific solid waste dump sites. Described in the body of the report are experiments relating the time course of association of 237 Pu tracer with diatoms (dead or alive) or glass beads, to the constitution of the media, the history of the cells, or the presence of exometabolites. Also described are studies of the differential removal of 239 240 Pu, 241 Am, and 137 Cs from coastal seawater currents contaminated by waste released from a fuel-reprocessing facility

  13. Gamma-ray scanning of neutron activated geological sediments for studying elemental profile distributions

    International Nuclear Information System (INIS)

    Ellinger, M.; Janghorbani, M.; Starke, K.

    1976-01-01

    Gamma-ray scanning for application to elemental profile studies of geological samples was studied with a neutron activated Baltic Shield sediment. Profile distribution of seven elements were measured. The capabilities and limitations of gamma-ray scanning are discussed by comparing the results with profiles obtained after the mechanical subdivision of the sample and the activation of the appropriately sized separates. With respect to the merits and limitations of scanning gamma-ray spectrometry applied to activated complex matrices the following conclusions were drawn. Qualitatively, the scanning method yields the same information as the much more laborious method of mechanical sudbisubdivision. Quantitatively, it is significantly less accurate. The scanning method has the significant advantage of allowing preservation of the sample. This could be important for such speciments as lunar and archeological materials. The method reduces sample preparation time and the possibility of sample contamination. (T.G.)

  14. Distribution of 137Cs in samples of ocean bottom sediments of the baltic sea in 1982-1983

    International Nuclear Information System (INIS)

    Gedenov, L.I.; Flegontov, V.M.; Ivanova, L.M.; Kostandov, K.A.

    1986-01-01

    The concentration of Cs-137 in samples of ocean bottom sediments picked up in 1979 in the Gulf of Finland with a geological nozzle pipe varied within a wide interval of values. The results could indicate nonuniformity of the Cs-137 distribution in ocean bottom sediments as well as the penetration of significant amounts of Cs-137 to large depths. The main error resulted from the sampling technique employed because the upper part of the sediment could be lost. In 1982, a special ground-sampling device, with which the upper layer of sediments in the water layer close to the ocean bottom could be sampled, was tested in the Gulf of Finland and the Northeastern part of the Baltic Sea. The results of a layerwise determination of the Cs-137 concentration in samples of ocean bottom sediments of the Gulf of Finland and of the Baltic Sea are listed. The new soil-sampling device for picking samples of ocean sediments of undisturbed stratification will allow a correct determination of the radionuclide accumulation in the upper layers of ocean bottom sediments in the Baltic Sea

  15. Trace metal distribution in sediments of the Pearl River Estuary and the surrounding coastal area, South China

    International Nuclear Information System (INIS)

    Ip, Carman C.M.; Li Xiangdong; Zhang Gan; Wai, Onyx W.H.; Li, Y.-S.

    2007-01-01

    Surface sediments and sediment cores collected at the Pearl River Estuary (PRE) and its surrounding coastal area were analysed for total metal concentrations, chemical partitioning, and Pb isotopic compositions. The distribution of Cu, Cr, Pb, and Zn demonstrated a typical diffusion pattern from the land to the direction of the sea. Two hotspots of trace metal contamination were located at the mixed zone between freshwater and marine waters. The enrichment of metals in the sediments could be attributed to the deposition of the dissolved and particulate trace metals in the water column at the estuarine area. The similar Pb isotopic signatures of the sediments at the PRE and its surrounding coastal area offered strong evidence that the PRE was a major source of trace metals to the adjacent coastal area. Slightly lower 206 Pb/ 207 Pb ratios in the coastal sediments may indicate other inputs of Pb in addition to the PRE sources, including the inputs from Hong Kong and other parts of the region. - The distribution of trace metals in sediments reflected contaminant sources, physical and chemical deposition processes

  16. Concentration levels and spatial distribution of sulphur and metals in fine-grained sediments in western Finland

    Directory of Open Access Journals (Sweden)

    M. ÅSTRÖM

    2008-12-01

    Full Text Available On the coastal plains of Finland, widespread Holocene marine and lacustrine sediments have developed into acid sulphate soil as a result of extensive artificial drainage for agricultural purposes. This has caused a variety of environmental problems. The aim of this study was to determine the concentration levels and spatial distribution of sulphur, carbon and metals [titanium, vanadium, chromium, manganese (Mn, iron, cobalt (Co, nickel (Ni, copper (Cu, zinc (Zn] in these sediments, in order to increase the geochemical understanding of the parent materials from which acid sulphate soil develops. Sediment samples were collected at 317 sites from a depth of 1.5–3 m. While the sediments have high S (sulphide concentrations (median = 0.54% and thus a strong acidification potential, they carry transition metals mainly in smallsized silicates close to “background concentrations” far below contamination limits. The previously documented extensive release of Co, Cu, Mn, Ni and Zn from oxidised and acidified layers of these sediments (i.e. acid sulphate soil is thus not explained by anomalously high natural or anthropogenic metal concentrations of the soils/sediments, but by an inherent highly mobile metal pool. Spatial-distribution maps highlight areas of elevated S and Mn concentrations, where it is likely that ditching and subsequent oxidation will result in an exceptionally large release of protons and Mn respectively.;

  17. A Random Forest approach to predict the spatial distribution of sediment pollution in an estuarine system.

    Directory of Open Access Journals (Sweden)

    Eric S Walsh

    Full Text Available Modeling the magnitude and distribution of sediment-bound pollutants in estuaries is often limited by incomplete knowledge of the site and inadequate sample density. To address these modeling limitations, a decision-support tool framework was conceived that predicts sediment contamination from the sub-estuary to broader estuary extent. For this study, a Random Forest (RF model was implemented to predict the distribution of a model contaminant, triclosan (5-chloro-2-(2,4-dichlorophenoxyphenol (TCS, in Narragansett Bay, Rhode Island, USA. TCS is an unregulated contaminant used in many personal care products. The RF explanatory variables were associated with TCS transport and fate (proxies and direct and indirect environmental entry. The continuous RF TCS concentration predictions were discretized into three levels of contamination (low, medium, and high for three different quantile thresholds. The RF model explained 63% of the variance with a minimum number of variables. Total organic carbon (TOC (transport and fate proxy was a strong predictor of TCS contamination causing a mean squared error increase of 59% when compared to permutations of randomized values of TOC. Additionally, combined sewer overflow discharge (environmental entry and sand (transport and fate proxy were strong predictors. The discretization models identified a TCS area of greatest concern in the northern reach of Narragansett Bay (Providence River sub-estuary, which was validated with independent test samples. This decision-support tool performed well at the sub-estuary extent and provided the means to identify areas of concern and prioritize bay-wide sampling.

  18. Simulation of temporal and spatial distribution of required irrigation water by crop models and the pan evaporation coefficient method

    Science.gov (United States)

    Yang, Yan-min; Yang, Yonghui; Han, Shu-min; Hu, Yu-kun

    2009-07-01

    Hebei Plain is the most important agricultural belt in North China. Intensive irrigation, low and uneven precipitation have led to severe water shortage on the plain. This study is an attempt to resolve this crucial issue of water shortage for sustainable agricultural production and water resources management. The paper models distributed regional irrigation requirement for a range of cultivated crops on the plain. Classic crop models like DSSAT- wheat/maize and COTTON2K are used in combination with pan-evaporation coefficient method to estimate water requirements for wheat, corn, cotton, fruit-trees and vegetables. The approach is more accurate than the static approach adopted in previous studies. This is because the combination use of crop models and pan-evaporation coefficient method dynamically accounts for irrigation requirement at different growth stages of crops, agronomic practices, and field and climatic conditions. The simulation results show increasing Required Irrigation Amount (RIA) with time. RIA ranges from 5.08×109 m3 to 14.42×109 m3 for the period 1986~2006, with an annual average of 10.6×109 m3. Percent average water use by wheat, fruit trees, vegetable, corn and cotton is 41%, 12%, 12%, 11%, 7% and 17% respectively. RIA for April and May (the period with the highest irrigation water use) is 1.78×109 m3 and 2.41×109 m3 respectively. The counties in the piedmont regions of Mount Taihang have high RIA while the central and eastern regions/counties have low irrigation requirement.

  19. Distribution, enrichment and sources of thallium in the surface sediments of the southwestern coastal Laizhou Bay, Bohai Sea.

    Science.gov (United States)

    Zhuang, Wen; Gao, Xuelu

    2015-07-15

    The concentrations of thallium (Tl) in the surface sediments of the southwestern coastal Laizhou Bay and the rivers it connects were determined. In riverine sediments, the Tl concentrations ranged from 0.34 to 0.76 μg g(-1) in summer; in autumn, the corresponding data were 0.35-1.08 μg g(-1). In marine sediments, the Tl concentrations ranged from 0.36 to 0.58 μg g(-1) in summer; and from 0.30 to 0.56 μg g(-1) in autumn. The grain size, Al and Fe oxides were major factors affecting Tl distribution. Tl in the surface sediments of the studied area was mainly from the natural input with the non-natural input as a subsidiary source. The low concentrations of Tl made it hard to cause potential negative environmental effects in this area. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Distribution of natural and anthropogenic radionuclides in surficial sediments of Jakarta bay

    International Nuclear Information System (INIS)

    Ali Arman Lubis

    2006-01-01

    he concentration and distribution of natural and anthropogenic radionuclide in surficial sediments of Jakarta Bay were investigated with the aim of evaluating its level and environmental radioactivity. Sediments were sampled in 30 locations using Smith-McIntyre Grab sampler. Sediments were dried, homogenized and sealed for 1 month for equilibration and for the detection, analysis and data acquisition, a high purity germanium (HPGe) detector coupled with a high resolution multichannel analyzer (MCA) was used. Additionally, the grain sizes were analyzed by means of hydrometer. The result shows that the specific activity of 238 U, 226 Ra, 232 Th, 40 K and 137 Cs range from 6.71±1.01 Bq/kg to 28.63±4.29 Bq/kg, 6.46±0.97 Bq/kg to 28.21±4.23 Bq/kg, 16.62±2.49 Bq/kg to 40.46±6.07 Bq/kg, 115.80±12.16 Bq/kg to 358.69±30.49 Bq/kg, and 0.03±0.01 Bq/kg to 1.99±0.34 Bq/kg with the average value are 12.83±2.11 Bq/kg, 12.03±1.98 Bq/kg, 26.55±4.36 Bq/kg, 235.55±19.37 Bq/kg, and 0.77±0.13 Bq/kg, respectively. It shows that the activity of radionuclides in the research area are in natural level and the variation may be influenced by the grain size distribution in the sample. The absorbed dose rate and radium equivalent of gamma radiation was estimated to be 32.06±7.72 nano Grey/h and 68.14±11.20 Bq/kg, respectively. (author)

  1. Distributed specific sediment yield estimations in Japan attributed to extreme-rainfall-induced slope failures under a changing climate

    Directory of Open Access Journals (Sweden)

    K. Ono

    2011-01-01

    Full Text Available The objective of this study was to estimate the potential sediment yield distribution in Japan attributed to extreme-rainfall-induced slope failures in the future. For this purpose, a regression relationship between the slope failure probability and the subsequent sediment yield was developed by using sediment yield observations from 59 dams throughout Japan. The slope failure probability accounts for the effects of topography (as relief energy, geology and hydro-climate variations (hydraulic gradient changes due to extreme rainfall variations and determines the potential slope failure occurrence with a 1-km resolution. The applicability of the developed relationship was then validated by comparing the simulated and observed sediment yields in another 43 dams. To incorporate the effects of a changing climate, extreme rainfall variations were estimated by using two climate change scenarios (the MRI-RCM20 Ver.2 model A2 scenario and the MIROC A1B scenario for the future and by accounting for the slope failure probability through the effect of extreme rainfall on the hydraulic gradient. Finally, the developed slope failure hazard-sediment yield relationship was employed to estimate the potential sediment yield distribution under a changing climate in Japan.

    Time series analyses of annual sediment yields covering 15–20 years in 59 dams reveal that extreme sedimentation events have a high probability of occurring on average every 5–7 years. Therefore, the extreme-rainfall-induced slope failure probability with a five-year return period has a statistically robust relationship with specific sediment yield observations (with r2 = 0.65. The verification demonstrated that the model is effective for use in simulating specific sediment yields with r2 = 0.74. The results of the GCM scenarios suggest that the sediment yield issue will be critical in Japan in the future. When the spatially averaged sediment

  2. Size distribution and carbonate content of the sediments of the western shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, R.R.; Pylee, A.

    %). (2) The outer shelf (approximately 20 to 70 fms) is a zone of relict sediments, having relatively low rates of sedimentation and composed of fine to medium sands. Occasional patches of coarse iron stained sands and pebbles are also present...

  3. Organic carbon and humic acids in sediments of the Arabian Sea and factors governing their distribution

    Digital Repository Service at National Institute of Oceanography (India)

    Sardessai, S.

    acids are enriched on the slope compared to the inner and outer shelf. While upwelling, primary productivity and redox conditions at the bottom are known to influence organic matter accumulation in sediments, bacterial population and sediment texture...

  4. Distribution and origin of sediments on the northern Sunda Shelf, South China Sea

    Science.gov (United States)

    Wu, Shi-Guo; Wong, H. K.; Luo, You-Lang; Liang, Zhi-Rong

    1999-03-01

    Seventy-seven surface sediment samples and core samples from the outer Sunda Shelf were analyzed and a number of seismic profiles of the shelf were interpreted. The bottom sediments could be divided into six types: terrigenous sand, biogenic sand, silt-sand, clay-silt-sand, clayey silt and coral reef detritus. Our seismic data showed a thick, prograding Pleistocene deltaic sequence near the shelf-break and a thin Holocene sedimentary layer on the outer shelf. Eleven thermoluminescence (TL) ages were determined. The oldest relict sediments were derived from Late Pleistocene deposits. Based on sediment types, ages, and origins, five sedimentary areas were identified: area of modern Mekong sediments; insular shelf area receiving modern sediments from small Borneo rivers; shelf area near the Natuna-Anambas islands in the southeastern Gulf of Thailand Basin off the Malay Peninsula; area of relict sediments on the outer shelf north of the Natuna Islands, and typical coral reefs and detritus sediments.

  5. Distributions, abundances and activities of microbes associated with the nitrogen cycle in riparian and stream sediments of a river tributary.

    Science.gov (United States)

    Kim, Haryun; Bae, Hee-Sung; Reddy, K Ramesh; Ogram, Andrew

    2016-12-01

    River tributaries are ecologically important environments that function as sinks of inorganic nitrogen. To gain greater insight into the nitrogen cycle (N-cycle) in these environments, the distributions and activities of microbial populations involved in the N-cycle were studied in riparian and stream sediments of the Santa Fe River (SFR) tributaries located in northern Florida, USA. Riparian sediments were characterized by much higher organic matter content, and extracellular enzyme activities, including cellobiohydrolase, β-d-glucosidase, and phenol oxidase than stream sediments. Compared with stream sediments, riparian sediments exhibited significantly higher activities of nitrification, denitrification, dissimilatory nitrate reduction to ammonia (DNRA) and anaerobic ammonia oxidation; correspondingly, with higher copies of amoA (a biomarker for enumerating nitrifiers), nirS and nirK (for denitrifiers), and nrfA (for DNRA bacteria). Among N-cycle processes, denitrification showed the highest activities and the highest concentrations of the corresponding gene (nirK and nirS) copy numbers. In riparian sediments, substantial nitrification activities (6.3 mg-N kg soil -1 d -1 average) and numbers of amoA copies (7.3 × 10 7  copies g soil -1 average) were observed, and nitrification rates correlate with denitrification rates. The guild structures of denitrifiers and nitrifiers in riparian sediments differed significantly from those found in stream sediments, as revealed by analysis of nirS and archaeal amoA sequences. This study shows that riparian sediments serve as sinks for inorganic nitrogen loads from non-point sources of agricultural runoff, with nitrification and denitrification associated with elevated levels of carbon and nitrogen contents and extracellular enzyme activities. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Enhancing sediment distribution at the vicinity of power plant intakes using double rows of vanes and groins (Case study: New tebbin power plant

    Directory of Open Access Journals (Sweden)

    Sayed Mahgoub

    2013-12-01

    The study results showed that, in case of vanes absence, sediments with rates 1–2 m3/week were stuck within the sediment trap under the winter conditions. Also, the results indicated that the submerged vanes play an important role in preventing the sediment intrusion. Also, it was clear that using groins might lead to enhancing the sediment distribution at the intake vicinity.

  7. Rare earth elements determination and distribution patterns in sediments of a polluted marine environment by instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Yusof, A.M.

    2001-01-01

    Results obtained from the analysis of sediment core samples taken from a fairly polluted marine environment were analyzed for the REE contents to determine the concentrations of La, Ce, Sm, Eu, Tb, Dy and Yb using instrumental neutron activation analysis. Core samples were divided into strata of between 2 to 3 cm intervals and prepared in the powdered form before irradiating them in a neutron flux of about 5.0 x 10 12 n x cm -2 x s -1 in a Triga Mark II reactor. Down-core concentration profiles of La, Ce, Sm, Eu, Tb, Dy and Yb in 3 core sediments from three sites are obtained. The shale-normalized REE pattern from each site was examined and later used to explain the history of sedimentation by natural processes such as shoreline erosion and weathering products deposited on the seabed and furnishing some baseline data and/or pollution trend occurring within the study area. The shale-normalized REE patterns also showed that LREE in the sediment samples exhibit enrichment relative to HREE particularly, La and Sm showing enrichment compared to the ratios in shale. REE concentrations of 124 μg/g at the surface of sediment collected at two of the three sites were found to decrease to 58 and 95 μg/g, respectively. This was of particular interest when it is used to explain the anomalies occurring in the marine sediment as a result of geochemical processes over a long period of time. Changes in concentrations from surface to bottom of the sediments ratioed to Sm concentrations and the correlation between concentrations of Sm and these elements were also investigated and correlation coefficients were calculated for all REEs and sites. Validation of the method used was done using a Soil-7 SRM. (author)

  8. Nature of distribution of mercury in the sediments of the river Yamuna (tributary of the Ganges), India.

    Science.gov (United States)

    Subramanian, V; Madhavan, N; Saxena, Rajinder; Lundin, Lars-Christer

    2003-06-01

    Suspended Particulate Matter (SPM), surface (bed sediments) and short length cores of sediments collected from the largest tributary of the river Ganges, namely the river Yamuna, were analysed for total mercury as well as its fractionation in various size and chemical sites in the sediments following standard procedures. Also, attempts were made to determine the vertical distribution in sediments in relation to the recent timescale of a few decades. Our observations indicate that the SPM in general showed higher levels of total mercury compared to the surface sediments while at places the enhancement could be by a factor of 10, say around 25 microg g(-1) in the downstream region that integrates the industrial midstream and agricultural downstream terrain near its confluence with the Ganges. Surface sediments in the upstream direction near the Himalayan foothills and SPM in the lower reaches showed significant high Index of Geoaccumulation (Igeo) as defined by Müller. Size fractionation studies indicate that the finer fraction preferentially showed higher levels of mercury while in the lower reaches of the river, the total mercury is equitably distributed among all size fractions. The proportion of the residual fraction of mercury in relation to mobile fractions, in general decreases downstream towards its confluence with the Ganges river. In sediment cores, the vertical distribution show systematic peaks of mercury indicating that addition of this toxic metal to the aquatic system is in direct proportion to the increase in various types of human activities such as thermal power plants, land use changes (urbanisation) in the midstream region and intensive fertiliser application in lower reaches of this vast river basin.

  9. Anthropogenic impact on biogenic substance distribution and bacterial community in sediment along the Yarlung Tsangpo River on Tibet Plateau, China

    Science.gov (United States)

    Wang, C.; Peifang, W.; Wang, X.; Hou, J.; Miao, L.

    2017-12-01

    Lotic river system plays an important part in water-vapor transfer and biogenic substances migration and transformation. Anthropogenic activities, including wastewater discharging and river damming, have altered river ecosystem and continuum. However, as the longest alpine river in China and suffered from increasing anthropogenic activities, the Yarlung Tsangpo River has been rarely studied. Recently, more attention has also been paid to the bacteria in river sediment as they make vital contributions to the biogeochemical nutrient cycling. Here, the distribution of biogenic substances, including nitrogen, phosphorus, silicon and carbon, was explored in both water and sediment of the Yarlung Tsangpo River. By using the next generation 16S rRNA sequencing, the bacterial diversity and structure in river sediment were presented. The results indicated that the nutrient concentrations increased in densely populated sites, revealing that biogenic substance distribution corresponded with the intensity of anthropogenic activity along the river. Nitrogen, phosphorus, silicon and carbon in water and sediment were all retained by the Zangmu Dam which is the only dam in the mainstream of the river. Moreover, the river damming decreased the biomass and diversity of bacteria in sediment, but no significant alteration of community structure was observed upstream and downstream of the dam. The most dominant bacteria all along the river was Proteobacteria. Meanwhile, Verrucomicrobia and Firmicutes also dominated the community composition in upstream and downstream of the river, respectively. In addition, total organic carbon (TOC) was proved to be the most important environmental factor shaping the bacterial community in river sediment. Our study offered the preliminary insights into the biogenic substance distribution and bacterial community in sediment along an alpine river which was affected by anthropogenic activities. In the future, more studies are needed to reveal the

  10. Regional distribution patterns of chemical parameters in surface sediments of the south-western Baltic Sea and their possible causes

    Science.gov (United States)

    Leipe, T.; Naumann, M.; Tauber, F.; Radtke, H.; Friedland, R.; Hiller, A.; Arz, H. W.

    2017-12-01

    This study presents selected results of a sediment geochemical mapping program of German territorial waters in the south-western Baltic Sea. The field work was conducted mainly during the early 2000s. Due to the strong variability of sediment types in the study area, it was decided to separate and analyse the fine fraction (<63 μm, mud) from more than 600 surficial samples, combined with recalculations for the bulk sediment. For the contents of total organic carbon (TOC) and selected elements (P, Hg), the regional distribution maps show strong differences between the analysed fine fraction and the recalculated total sediment. Seeing that mud contents vary strongly between 0 and 100%, this can be explained by the well-known grain-size effect. To avoid (or at least minimise) this effect, further interpretations were based on the data for the fine fraction alone. Lateral transport from the large Oder River estuary combined with high abundances and activities of benthic fauna on the shallow-water Oder Bank (well sorted fine sand) could be some main causes for hotspots identified in the fine-fraction element distribution. The regional pattern of primary production as the main driver of nutrient element fixation (C, N, P, Si) was found to be only weakly correlated with, for example, the TOC distribution in the fine fraction. This implies that, besides surface sediment dynamics, local conditions (e.g. benthic secondary production) also have strong impacts. To the best of the authors' knowledge, there is no comparable study with geochemical analyses of the fine fraction of marine sediments to this extent (13,600 km2) and coverage (between 600 and 800 data points) in the Baltic Sea. This aspect proved pivotal in confidently pinpointing geochemical "anomalies" in surface sediments of the south-western Baltic Sea.

  11. Distribution of butyltins in the waters and sediments along the coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Garg, A.; Meena, R; Jadhav, S.; Bhosle, N.B.

    for sediments it varied between below detection limit to 14861 ng Sn g sup(-1) dry weight of sediment. On an average Chennai port recorded the highest level of butyltins in the sediments while Paradip recorded the highest level of butylins in the waters. A...

  12. Chloride, bromide and iodide distributions in Loch Lomond sediment interstitial water

    International Nuclear Information System (INIS)

    MacKenzie, A.B.; Shimmield, T.M.; Scott, R.D.; Davidson, C.M.; Hooker, P.J.

    1991-01-01

    The post glacial sediments of Loch Lomond contain a well defined band of marine deposited material which is overlain and underlain by freshwater deposited sediment. The chronology of the sedimentary sequence has been well established by radiocarbon dating and, in the southern basin of the Loch, the marine sediment band is of the order of 1 m thick and typically occurs at a depth of about 3 to 4 m beneath the sediment surface. Previous work has established that the marine deposited sediment contains enhanced concentrations of iodine and bromine relative to the contiguous freshwater sediments and that dissolution of halogen elements from the marine sediments generates a concentration gradient, with consequent diffusive transport, of these elements in the sediment interstitial water. This environment is thus highly suitable for investigation of the rate of transport of halogen elements through the sediment a topic of direct relevance to radioactive waste disposal in the context of far field migration of 129 I. Previous studies resulted in successful modelling of the diffusive transport of bromine in the interstitial water of the sediment on the basis of the observed concentration profile for total bromine in the water. This work was, however, of restricted value since (1) speciation was not determined (2) archived sediment was used and (3) samples were processed and analyzed under ambient laboratory conditions. The objective of the work described in this report was to collect a new core of Loch Lomond sediment and to carry out appropriate analyses to overcome the above limitations

  13. Biogeographical distribution and diversity of microbes in methane hydrate-bearing deep marine sediments, on the Pacific Ocean Margin

    DEFF Research Database (Denmark)

    Inagaki, F.; Nunoura, T.; Nakagawa, S.

    2006-01-01

    The deep subseafloor biosphere is among the least-understood habitats on Earth, even though the huge microbial biomass therein plays an important role for potential long-term controls on global biogeochemical cycles. We report here the vertical and geographical distribution of microbes and their ......The deep subseafloor biosphere is among the least-understood habitats on Earth, even though the huge microbial biomass therein plays an important role for potential long-term controls on global biogeochemical cycles. We report here the vertical and geographical distribution of microbes...... of the uncultivated Deep-Sea Archaeal Group were consistently the dominant phylotype in sediments associated with methane hydrate. Sediment cores lacking methane hydrates displayed few or no Deep-Sea Archaeal Group phylotypes. Bacterial communities in the methane hydrate-bearing sediments were dominated by members...

  14. Spatial Distribution of the Coefficient of Variation and Bayesian Forecast for the Paleo-Earthquakes in Japan

    Science.gov (United States)

    Nomura, Shunichi; Ogata, Yosihiko

    2016-04-01

    We propose a Bayesian method of probability forecasting for recurrent earthquakes of inland active faults in Japan. Renewal processes with the Brownian Passage Time (BPT) distribution are applied for over a half of active faults in Japan by the Headquarters for Earthquake Research Promotion (HERP) of Japan. Long-term forecast with the BPT distribution needs two parameters; the mean and coefficient of variation (COV) for recurrence intervals. The HERP applies a common COV parameter for all of these faults because most of them have very few specified paleoseismic events, which is not enough to estimate reliable COV values for respective faults. However, different COV estimates are proposed for the same paleoseismic catalog by some related works. It can make critical difference in forecast to apply different COV estimates and so COV should be carefully selected for individual faults. Recurrence intervals on a fault are, on the average, determined by the long-term slip rate caused by the tectonic motion but fluctuated by nearby seismicities which influence surrounding stress field. The COVs of recurrence intervals depend on such stress perturbation and so have spatial trends due to the heterogeneity of tectonic motion and seismicity. Thus we introduce a spatial structure on its COV parameter by Bayesian modeling with a Gaussian process prior. The COVs on active faults are correlated and take similar values for closely located faults. It is found that the spatial trends in the estimated COV values coincide with the density of active faults in Japan. We also show Bayesian forecasts by the proposed model using Markov chain Monte Carlo method. Our forecasts are different from HERP's forecast especially on the active faults where HERP's forecasts are very high or low.

  15. Representative measurement of two-dimensional reactive phosphate distributions and co-distributed iron(II) and sulfide in seagrass sediment porewaters

    DEFF Research Database (Denmark)

    Pagès, Anaïs; Teasdale, Peter R.; Robertson, David

    2011-01-01

    The high degree of heterogeneity within sediments can make interpreting one-dimensional measurements difficult. The recent development and use of in situ techniques that measure two-dimensional distributions of porewater solutes have facilitated investigation of the role of spatial heterogeneity ...

  16. TU-F-18C-05: Evaluation of a Method to Calculate Patient-Oriented MGD Coefficients Using Estimates of Glandular Tissue Distribution

    International Nuclear Information System (INIS)

    Porras-Chaverri, M; Galavis, P; Bakic, P; Vetter, J

    2014-01-01

    Purpose: Evaluate mammographic mean glandular dose (MGD) coefficients for particular known tissue distributions using a novel formalism that incorporates the effect of the heterogeneous glandular tissue distribution, by comparing them with MGD coefficients derived from the corresponding anthropomorphic computer breast phantom. Methods: MGD coefficients were obtained using MCNP5 simulations with the currently used homogeneous assumption and the heterogeneously-layered breast (HLB) geometry and compared against those from the computer phantom (ground truth). The tissue distribution for the HLB geometry was estimated using glandularity map image pairs corrected for the presence of non-glandular fibrous tissue. Heterogeneity of tissue distribution was quantified using the glandular tissue distribution index, Idist. The phantom had 5 cm compressed breast thickness (MLO and CC views) and 29% whole breast glandular percentage. Results: Differences as high as 116% were found between the MGD coefficients with the homogeneous breast core assumption and those from the corresponding ground truth. Higher differences were found for cases with more heterogeneous distribution of glandular tissue. The Idist for all cases was in the [−0.8 − +0.3] range. The use of the methods presented in this work results in better agreement with ground truth with an improvement as high as 105 pp. The decrease in difference across all phantom cases was in the [9 − 105] pp range, dependent on the distribution of glandular tissue and was larger for the cases with the highest Idist values. Conclusion: Our results suggest that the use of corrected glandularity image pairs, as well as the HLB geometry, improves the estimates of MGD conversion coefficients by accounting for the distribution of glandular tissue within the breast. The accuracy of this approach with respect to ground truth is highly dependent on the particular glandular tissue distribution studied. Predrag Bakic discloses current

  17. Determination of the coefficient of uranium and thorium distribution in phosphogypsum for their use in sanitary landfills

    Energy Technology Data Exchange (ETDEWEB)

    Marchesi, Marcos Vinicius A.; Hama, Naruhiko; Jacomino, Vanusa M. F.; Ladeira, Ana Claudia Q.; Cota, Stela D. S., E-mail: mvmarchesi@hotmail.com, E-mail: sdsc@cdtn.br, E-mail: vmfj@cdtn.br, E-mail: ana.ladeira@cdtn.br, E-mail: naruhikohama@hotmail.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Nascimento, Marcos Roberto Lopes do; Taddei, Maria Helena, E-mail: pmarcos@cnen.gov.br, E-mail: mhtaddei@cnen.gov.br [Comissao Nacional de Energia Nuclear (LAPOC/CNEN), Pocos de Caldas, MG (Brazil). Laboratorio de Pocos de Caldas

    2013-07-01

    Phosphogypsum is a byproduct from the production of phosphoric acid, and contain radionuclides, heavy metals and metalloids from phosphate rock. It represents a risk to the environment if improperly stored. Because it is composed mainly of dihydrated calcium sulphate, phosphogypsum can be used in anaerobic environments such as those found in landfills to accelerate microbial processes of decomposition of municipal solid waste and thus increase the life of these facilities. One of the options of your application being studied is the use of phosphogypsum replacing the covers of soil/clay in landfills. Besides reducing the demand for soil and clay, this application would be an alternative to disposal of the waste, since the alternatives are not sufficient for more than five million tons produced per year in Brazil. To ensure the safety of this application, the potential environmental impact of contaminants in phosphogypsum should be evaluated. The rate of leaching of contaminants are being studied by determining the coefficient of distribution of the contaminants in the phosphogypsum. Batch tests were performed by mixing different proportions of slurry and phosphogypsum. This work presents the results for the chain of uranium and natural thorium.

  18. Determination of the coefficient of uranium and thorium distribution in phosphogypsum for their use in sanitary landfills

    International Nuclear Information System (INIS)

    Marchesi, Marcos Vinicius A.; Hama, Naruhiko; Jacomino, Vanusa M. F.; Ladeira, Ana Claudia Q.; Cota, Stela D. S.; Nascimento, Marcos Roberto Lopes do; Taddei, Maria Helena

    2013-01-01

    Phosphogypsum is a byproduct from the production of phosphoric acid, and contain radionuclides, heavy metals and metalloids from phosphate rock. It represents a risk to the environment if improperly stored. Because it is composed mainly of dihydrated calcium sulphate, phosphogypsum can be used in anaerobic environments such as those found in landfills to accelerate microbial processes of decomposition of municipal solid waste and thus increase the life of these facilities. One of the options of your application being studied is the use of phosphogypsum replacing the covers of soil/clay in landfills. Besides reducing the demand for soil and clay, this application would be an alternative to disposal of the waste, since the alternatives are not sufficient for more than five million tons produced per year in Brazil. To ensure the safety of this application, the potential environmental impact of contaminants in phosphogypsum should be evaluated. The rate of leaching of contaminants are being studied by determining the coefficient of distribution of the contaminants in the phosphogypsum. Batch tests were performed by mixing different proportions of slurry and phosphogypsum. This work presents the results for the chain of uranium and natural thorium

  19. Distribution of heavy metals in sediments of the Ciujung watersheds Banten

    International Nuclear Information System (INIS)

    Th Rina Mulyaningsih; Alfian; Sutisna

    2012-01-01

    Decrease of Ciujung river quality due to industry and community activities. leading to decreased quality of the river. As a result, river designation for raw drinking water, irrigation and fisheries are not suitable. Monitoring the quality of the river is one of the strategies for the environmental protection; therefore a suitable data should be required by government in a regional planning. A study of heavy metal distribution in the watershed Ciujung was carried out to determine its quality. Number of sediment samples was taken from several sampling points in the watershed, based on its pollutant sources identification. Sampling should be limited on main river (not including tributaries) from upstream to downstream river, there are 3] sampling points. Metal was analyzed using neutron activation analysis technique and AAS. The results showed that the distribution of metals Co, As, Sb, Cr, Fe, Mn, Zn, Pb, Cu, Ni and Cd fluctuate depending on the location. The highest concentrations of metals were found in downstream and industries-] area. Evaluation based on the enrichment factor, contamination factor and index of geo accumulation, ware concluded that the quality of upstream is still good has not contaminated / polluted. Industrial-], industrial-2 area and the downstream ware contaminated by Cd metal source from human activity (anthropogenic). Evaluation based on pollution load index indicates that the river has not been contaminated, but the downstream, industry-] and 2 areas has a value almost close IBT baseline level, therefore water quality monitoring in the future remains to be carried out. (author)

  20. Studies of alkyl porphyrin distributions in organic-rich sediments using LC-MS

    International Nuclear Information System (INIS)

    Eckardt, C.B.; Carter, J.F.; Keely, B.J.; Maxwell, J.R.; Kilpatrick, G.

    1992-01-01

    In recent years, structure elucidation of a wide variety of sedimentary tetrapyrroles has provided clear molecular evidence for the presence of primary photosynthetic communities in palaeo water columns. The reported structures indicate an origin from algal chlorophylls c for certain components, while an origin from photosynthetic bacteria is apparent from the carbon skeletons of other components. In particular, the structures of ≤C 34 porphyrin carboxylic acids in the Eocene Messel shale indicate an origin from Chloroblum bacteria. Since such bacteria are strict anaerobes, the presence of these species is evidence for anoxic conditions extending into the photic zone of Messel lake. By analogy, the presence in the more widely-occurring alkyl porphyrin distributions of components >C 33 would also suggest a Chlorobium chlorophyll origin. Hence, in this paper, the authors studied by LC-MS, the distributions of alkyl porphyrins in selected sediments and searched for the presence of such components, in order to determine photic zone anoxia in the respective palaeo environments

  1. Spatial distribution of heavy metals in sediments from the Gulf of Paria,Trinidad

    Directory of Open Access Journals (Sweden)

    Wendy Norville

    2005-05-01

    Full Text Available The Gulf of Paria receives heavy metal input from urban runoff,industrial and agricultural activity, sewage and domestic wastes:both from the west coast and from inland areas of Trinidad.Non-residual concentrations of nine metals,as well as total mercury concentrations,were used to determine spatial distributions of heavy metals in sediments in the Gulf of Paria.Surficial sediment samples were collected at 37 stations,which included the mouths of 11 major rivers that flow into the Gulf of Paria.Stations were sampled twice during the wet season (July 1998 and November/December 1998and twice during the dry season (March 1999 and April 1999.Sediments were analyzed for aluminium (Al,cadmium (Cd,chromium (Cr,copper (Cu,iron (Fe, lead (Pb,manganese (Mn,nickel (Ni,zinc (Znand mercury (Hg.Total Organic Carbon (TOCand grain size analyses were also performed on the sediments.Principal component analysis showed that sediments from river mouths subject to greatest land use and anthropogenic input,were distinct from other sediments in the Gulf of Paria.This was due to higher Pb,Zn,Cu and Hg concentrations (3.53-73.30 µg g-1 ,45.8-313.9 µg g-1 ,8.43-39.71 µg g-1 and 0.03-0.10 µg g-1 ,respectively.Sediments further from the coast were also distinct due to their higher Al,Fe,Cr and Mn concentrations (1.37-3.16 mg g-1 ,9.51-18.91 mg g-1 ,17.22-28.41 µg g-1 and 323.6 -1,564.2 µg g-1 ,respectively.Cd and Pb were higher in the wet season while Ni was higher in the dry season.Pb,Zn,Cu and Hg were correlated with each other and with TOC.Correlation was also observed between Al,Fe,Cr,Mn and Ni.Al,Fe,Cr and Mn were correlated with percentage clay in sediments.The results suggest that Pb,Zn, Cu and Hg are preferentially removed by organic matter,which settles at the river-mouths,while Al,Fe,Cr,Mn, and Ni become associated with clay minerals and are transported away from the coast.El Golfo de Paria recibe metales pesados de zonas urbanas,industriales y agr

  2. Hopane, sterane and n-alkane distributions in shallow sediments hosting high arsenic groundwaters in Cambodia

    International Nuclear Information System (INIS)

    Dongen, Bart E. van; Rowland, Helen A.L.; Gault, Andrew G.; Polya, David A.; Bryant, Charlotte; Pancost, Richard D.

    2008-01-01

    The presence of elevated As in ground waters exploited for drinking water and irrigation in South-East Asia is causing serious impacts on human health. A key mechanism that causes the mobilization of As in these waters is microbially mediated reductive transformation of As-bearing Fe(III) hydrated oxides and the role of degradable organic matter (OM) in this process is widely recognized. A number of different types of OM that drive As release in these aquifers have been suggested, including petroleum derived hydrocarbons naturally seeping into shallow sediments from deeper thermally mature source rocks. However, the amount of information on the characteristics of the OM in South-East Asian aquifers is limited. Here the organic geochemical analyses of the saturated hydrocarbon fractions and radiocarbon analysis, of two additional sites in SE Asia are reported. The results show that the OM in a given sedimentary horizon likely derives from multiple sources including naturally occurring petroleum. The importance of naturally occurring petroleum as one of the sources was clearly indicated by the n-alkane CPI of approximately 1, the presence of an unresolved complex mixture, and hopane (dominated by 17α(H),21β(H) hopanes) and sterane distribution patterns. The results also indicate that the OM in these aquifers varies tremendously in content, character and potential bioavailability. Furthermore, the presence of petroleum derived OM in sediments at both sites doubles the number of locations where their presence has been observed in association with As-rich, shallow aquifers, suggesting that the role of petroleum derived OM in microbially mediated As release might occur over a wider range of geographical locations than previously thought

  3. Can bathymetry be a discriminatory factor for the distribution of benthic foraminiferal morpho-groups in modern marine sediments?

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Khare, N.; Mayenkar, D.N.

    -symmetrical. The distribution profiles of these morpho-groups in the surface sediments apparently showed that angular-asymmetrical morpho-group is more or less abundant in deeper regions while, rounded-symmetrical morpho-group tends to flourish in relatively shallower regions...

  4. Major, trace, and rare earth elements in the sediments of the Central Indian Ocean Basin: Their source and distribution

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Jauhari, P.

    The distribution maps of elements show that highest concentrations of Mn, Cu, Ni, Zn, Co, and biogenic opal in the surface sediment occurs between 10 degrees S and 16 degrees S latitude, where diagenetic ferromanganese nodules rich in Mn, Cu, Ni...

  5. Distribution, partitioning and sources of polycyclic aromatic hydrocarbons in the water-SPM-sediment system of Lake Chaohu, China

    DEFF Research Database (Denmark)

    Qin, Ning; He, Wei; Kong, Xiang-Zhen

    2014-01-01

    in the water, while no obvious seasonal trend was found in the SPM. The residues and distributions of PAHs in the water, SPM and sediment relied heavily on carbon content. Significant Pearson correlations were found between LogKoc and LogKow as well as some hydro-meteorological factors. Three major sources...

  6. The Vertical Distribution of Sediment Archaeal Community in the “Black Bloom” Disturbing Zhushan Bay of Lake Taihu

    Science.gov (United States)

    Fan, Xianfang; Xing, Peng

    2016-01-01

    Using the Illumina sequencing technology, we investigated the vertical distribution of archaeal community in the sediment of Zhushan Bay of Lake Taihu, where the black bloom frequently occurred in summer. Overall, the Miscellaneous Crenarchaeotal Group (MCG), Deep Sea Hydrothermal Vent Group 6 (DHVEG-6), and Methanobacterium dominated the archaeal community. However, we observed significant difference in composition of archaeal community among different depths of the sediment. DHVEG-6 dominated in the surface layer (0–3 cm) sediment. Methanobacterium was the dominating archaeal taxa in the L2 (3–6 cm) and L3 (6–10) sediment. MCG was most abundant in the L4 (10–15 cm) and L5 (15–20 cm) sediment. Besides, DHVEG-6 was significantly affected by the concentration of total phosphorus (TP). And loss on ignition (LOI) was an important environmental factor for Methanobacterium. As the typical archaeal taxa in the surface layer sediment, DHVEG-6 and Methanobacterium might be more adapted to abundant substrate supply from cyanobacterial blooms and take active part in the biomass transformation. We propose that DHVEG-6 and Methanobacterium could be the key archaeal taxa correlated with the “black bloom” formation in Zhushan Bay. PMID:26884723

  7. Effects of oil dispersants on settling of marine sediment particles and particle-facilitated distribution and transport of oil components.

    Science.gov (United States)

    Cai, Zhengqing; Fu, Jie; Liu, Wen; Fu, Kunming; O'Reilly, S E; Zhao, Dongye

    2017-01-15

    This work investigated effects of three model oil dispersants (Corexit EC9527A, Corexit EC9500A and SPC1000) on settling of fine sediment particles and particle-facilitated distribution and transport of oil components in sediment-seawater systems. All three dispersants enhanced settling of sediment particles. The nonionic surfactants (Tween 80 and Tween 85) play key roles in promoting particle aggregation. Yet, the effects varied with environmental factors (pH, salinity, DOM, and temperature). Strongest dispersant effect was observed at neutral or alkaline pH and in salinity range of 0-3.5wt%. The presence of water accommodated oil and dispersed oil accelerated settling of the particles. Total petroleum hydrocarbons in the sediment phase were increased from 6.9% to 90.1% in the presence of Corexit EC9527A, and from 11.4% to 86.7% for PAHs. The information is useful for understanding roles of oil dispersants in formation of oil-sediment aggregates and in sediment-facilitated transport of oil and PAHs in marine eco-systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Superficial distribution of aromatic compounds and geomicrobiology of sediments from Suruí Mangrove, Guanabara Bay, RJ, Brazil

    OpenAIRE

    Fontana,Luiz F.; Silva,Frederico S. da; Figueiredo,Natália G. de; Brum,Daniel M.; Netto,Annibal D. Pereira; Gigueiredo Junior,Alberto G. de; Crapez,Mirian A.C.

    2010-01-01

    The distribution of selected aromatic compounds and microbiology were assessed in superficial sediments from Suruí Mangrove, Guanabara Bay. Samples were collected at 23 stations, and particle size, organic matter, aromatic compounds, microbiology activity, biopolymers, and topography were determined. The concentration of aromatic compounds was distributed in patches over the entire mangrove, and their highest total concentration was determinated in the mangrove's central area. Particle size d...

  9. [Accumulation, distribution and pollution assessment of heavy metals in surface sediment of Caohai plateau wetland, Guizhou province].

    Science.gov (United States)

    Zhang, Qing-Hai; Lin, Chang-Hu; Tan, Hong; Lin, Shao-Xia; Yang, Hong-Bo

    2013-03-01

    The objective of this paper is to investigate the concentrations and distribution characteristics of heavy metals in surface sediments of different areas in the Caohai plateau wetland. 16 samples of surface sediments were collected and 7 heavy metals were analyzed. Heavy metal pollution in surface sediments of different areas in the Caohai plateau wetland was estimated by the Tomlinson Pollution Load Index (PLI) method. The analyzed results indicated that the average contents of Cd, Hg, As, Pb, Cr, Cu, Zn were 0.985, 0.345, 15.8, 38.9, 38.6, 22.8 and 384 mg x kg(-1), respectively. The heavy metal distributions varied with regional environment changes, the order of average contents of Cd and Hg in different regions was E (the eastern region) > S (the southern region) > N (the northern region), the order of the average content of Pb was N > E > S, and that of Zn was S > E > N. The results also suggested a medium heavy metal pollution level in the surface sediment of the Caohai plateau wetland with the PLI(zone) reaching 1.17. The order of pollution level in surface sediments of different regions was E > S > N. The results showed medium pollution levels in E and Hg which reached the extreme intensity pollution level were also the major polluted elements in surface sediments of the Caohai plateau wetland. And also, results showed medium pollution levels of Cd and Pb in surface sediments of Caohai plateau wetland. Cluster analysis results showed similar pollution sources of Cd, Zn, Pb and Hg, which should be attached great importance in terms of the prevention of the Caohai plateau wetland.

  10. Vertical Distribution and Flux of Nutrients in the Sediments of the Mangrove Reclamation Region of Muara Angke Kapuk, Jakarta

    Directory of Open Access Journals (Sweden)

    Anna Ida Sunaryo Purwiyanto

    2012-12-01

    Full Text Available The reclaimed mangrove estuary in Muara Angke Kapuk is a reclaimed area that has not evaded the impacted of pollution and waste in the areas surrounding Cengkareng, Jakarta. This is apparent from the fact that almost all sediments under the mangrove trees are buried under heaps of plastic trash. However, the reclaimed region still has variety of organism, which indicating that the region still has an internal carrying capacity, especially nutrients from sediment. The purpose of this research was to examine the condition of sediment nutrients in this mangrove reclamation region. The research was conducted by taking water samples using a modification of the stratified cup at a sediment depth of 0-15 cm with depth intervals of 2.5 cm, and taking sediment samples using the sediment ring. Pore water samples were measured for dissolved oxygen (DO and concentrations of ammonia, nitrite, nitrate, and phosphate. Sediment samples were used to obtain porosity values. The data obtained is used to make vertical concentration profiles and analysis of vertical nutrient flux. Vertical nutrient flux analysis was performed with the aid of QUAL2K software version 2.11. The results showed different vertical distributions and flux of nutrients, where influx for ammonia and phosphate and an increase in line with increasing sediment depth, while nitrate efflux and a decreased concentration. The flux calculation of nitrite as transitory nutrient was not done, but the concentration decreased after a depth of 2.5 cm. This indicates that the high contamination on the surface does not prevent the natural chemical processes so the reclaimed region can still provide nutritional support for its organism.

  11. Impact of redox-stratification on the diversity and distribution of bacterial communities in sandy reef sediments in a microcosm

    Institute of Scientific and Technical Information of China (English)

    GAO Zheng; WANG Xin; Angelos K. HANNIDES; Francis J. SANSONE; WANG Guangyi

    2011-01-01

    Relationships between microbial communities and geochemical environments are important in marine microbial ecology and biogeochemistry.Although biogeochemical redox stratification has been well documented in marine sediments,its impact on microbial communities remains largely unknown.In this study,we applied denaturing gradient gel electrophoresis (DGGE) and clone library construction to investigate the diversity and stratification of bacterial communities in redox-stratified sandy reef sediments in a microcosm.A total of 88 Operational Taxonomic Units (OTU) were identified from 16S rRNA clone libraries constructed from sandy reef sediments in a laboratory microcosm.They were members of nine phyla and three candidate divisions,including Proteobacteria (Alpha-,Beta-,Gamma-,Delta-,and Epsilonproteobacteria),Actinobacteria,Acidobacteria,Bacteroidetes,Chloroflexi,Cyanobacteria,Firmicutes,Verrucomicrobia,Spirochaetes,and the candidate divisions WS3,SO31 and AO19.The vast majority of these phylotypes are related to clone sequences from other marine sediments,but OTUs of Epsilonproteobacteria and WS3 are reported for the first time from permeable marine sediments.Several other OTUs are potential new bacterial phylotypes because of their low similarity with reference sequences.Results from the 16S rRNA,gene clone sequence analyses suggested that bacterial communities exhibit clear stratification across large redox gradients in these sediments,with the highest diversity found in the anoxic layer (15-25 mm) and the least diversity in the suboxic layer (3-5 mm).Analysis of the nosZ,and amoA gene libraries also indicated the stratification of denitrifiers and nitrifiers,with their highest diversity being in the anoxic and oxic sediment layers,respectively.These results indicated that redox-stratification can affect the distribution of bacterial communities in sandy reef sediments.

  12. Distribution, sources and composition of antibiotics in sediment, overlying water and pore water from Taihu Lake, China

    International Nuclear Information System (INIS)

    Xu, Jian; Zhang, Yuan; Zhou, Changbo; Guo, Changsheng; Wang, Dingming; Du, Ping; Luo, Yi; Wan, Jun; Meng, Wei

    2014-01-01

    The occurrence of 15 antibiotics classified as sulphonamides, fluoroquinolones, macrolides, tetracyclines and trimethoprim in sediment, overlying water, and pore water matrices in Taihu Lake, China was studied. The total concentrations were from 4.1 μg/kg to 731 μg/kg, from 127 ng/L to 1210 ng/L, and from 1.5 ng/L to 216 ng/L in sediment, overlying water and pore water, respectively. Antibiotics in different locations originated from various sources, depending on human, agricultural and aquacultural activities. Composition analysis indicated that human-derived and animal-derived drugs significantly contributed to the total contamination of antibiotics in the lake, indicating the high complexity of contamination sources in Taihu Lake Basin. The in situ sediment–pore water partitioning coefficients were generally greater than sediment–overlying water partitioning coefficients, suggesting continuous inputs into the lake water. This study shows that antibiotics are ubiquitous in all compartments in Taihu Lake, and their potential hazards to the aquatic ecosystem need further investigation. - Highlights: • Antibiotics are ubiquitous in sediment, overlying water and pore water in Taihu Lake. • Antibiotics in Taihu Lake originated from human and nonhuman activities. • Ksp is higher than Ksw, indicating the continuous antibiotics input to lake water

  13. Distribution, sources and composition of antibiotics in sediment, overlying water and pore water from Taihu Lake, China

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jian [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Laboratory of Riverine Ecological Conservation and Technology, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Zhang, Yuan, E-mail: zhangyuan@craes.org.cn [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Laboratory of Riverine Ecological Conservation and Technology, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Zhou, Changbo [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Guo, Changsheng; Wang, Dingming [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Laboratory of Riverine Ecological Conservation and Technology, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Du, Ping [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Luo, Yi [College of Environmental Sciences and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, Tianjin 300071 (China); Wan, Jun; Meng, Wei [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Laboratory of Riverine Ecological Conservation and Technology, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China)

    2014-11-01

    The occurrence of 15 antibiotics classified as sulphonamides, fluoroquinolones, macrolides, tetracyclines and trimethoprim in sediment, overlying water, and pore water matrices in Taihu Lake, China was studied. The total concentrations were from 4.1 μg/kg to 731 μg/kg, from 127 ng/L to 1210 ng/L, and from 1.5 ng/L to 216 ng/L in sediment, overlying water and pore water, respectively. Antibiotics in different locations originated from various sources, depending on human, agricultural and aquacultural activities. Composition analysis indicated that human-derived and animal-derived drugs significantly contributed to the total contamination of antibiotics in the lake, indicating the high complexity of contamination sources in Taihu Lake Basin. The in situ sediment–pore water partitioning coefficients were generally greater than sediment–overlying water partitioning coefficients, suggesting continuous inputs into the lake water. This study shows that antibiotics are ubiquitous in all compartments in Taihu Lake, and their potential hazards to the aquatic ecosystem need further investigation. - Highlights: • Antibiotics are ubiquitous in sediment, overlying water and pore water in Taihu Lake. • Antibiotics in Taihu Lake originated from human and nonhuman activities. • Ksp is higher than Ksw, indicating the continuous antibiotics input to lake water.

  14. Features of distribution and quality of organic matter in the bottom sediments of the Great Peter Bay (Sea of Japan)

    Science.gov (United States)

    Nesterova, Olga; Tregubova, Valentina; Semal, Victoria; Vasenev, Ivan

    2017-04-01

    The nature and distribution of organic carbon in marine waters depends on: 1) biological productivity and revenue of the autochthonous organic matter to the bottom; 2) sediment grain-size composition and conditions of dumping, which in turn depends of hydrothermic regime, topography, speed River mist and received major erosion products; 3) living conditions of the benthos (the quantity consumed of OM, gas regime of habitats, physiological capacity of heterotrophs). Autochthonous OM of phytoplankton plays a dominant role in the processes of formation of humus in aquatic conditions. Bottom sediments at different distance from the shoreline to depths from 0.5 up to 480 m of the Sea of Japan, which are formed in various conditions of facies, were selected as the objects of study. There is no clear relationships to the amount of organic matter in bottom sediments on the characteristics of the distribution and nature of living matter in the oceans and seas. This is because the process of sedimentation and fossilization of organic matter on the seabed and the ocean floor depends on many factors (currents, depth). Humus of studied bottom sediments in composition can be attributed mainly to the humic type. Nonhydrolyzing rest is 70-90%. This is characteristic of bottom sediments formed in facial types of small bays, internal coastal shelf bights and the underwater slope. At a fraction of the carbon of humic acids in organic matter, ranging from 4 to 80% of the amount of humic and fulvic acids. Fulvic acids content is much less. This is due to more favourable conservation situation of humic acids in precipitation with high content of organic matter, whereas fulvic acids in aquatic environments are more labile and almost not dumped. Despite the fact humic acids are not the most stable component (s), however, with increased content of humic acids, the mobility of organic matter and removing it from the bottom sediments are reduced. Internal shelf facies of the Great Peter Bay

  15. Polybrominated diphenyl ethers (PBDEs) in sediments of the coastal East China Sea: Occurrence, distribution and mass inventory

    International Nuclear Information System (INIS)

    Li Yuanyuan; Lin Tian; Chen Yingjun; Hu Limin; Guo Zhigang; Zhang Gan

    2012-01-01

    Polybrominated diphenyl ethers (PBDEs) of sixty-three sediment samples from the coastal East China Sea (ECS), extending ∼1000 km from the Yangtze River Estuary to the south, were measured. The levels of BDE-209 and ∑PBDE 7 (sum of BDE-28, 47, 99, 100, 153, 154, 183) were 0.3–44.6 ng/g (dry weight) and nd-8.0 ng/g, respectively. BDE-209 was the predominant congener, followed by BDE-99/100. This was consistent with the historical and current usage of PBDE mixtures in China. The compositions and distribution of PBDEs suggest that the PBDEs in this area could be mainly from the coastal electronic waste dismantling/recycling and Yangtze River input. The poor correlations between TOC, grain size of sediments with PBDEs imply that the PBDE distribution is more related to their land-based inputs rather than the sediment characters in the area. The coastal ECS is an important sink of PBDEs (7.5 t/yr) in the world. - Highlights: ► First report on the levels, distribution and inventory of PBDEs in the inner shelf of the ECS. ► PBDEs were mainly from the coastal electronic waste dismantling/recycling and Yangtze River. ► PBDE distribution was related to the land-based inputs rather than the sediment characters. ► The coastal East China Sea is an important sink of the PBDEs in the world. - The levels, distribution, potential sources and mass inventory of PBDEs in sediments of the coastal East China Sea were revealed.

  16. Spectro-ellipsometric studies of sputtered amorphous Titanium dioxide thin films: simultaneous determination of refractive index, extinction coefficient, and void distribution

    CERN Document Server

    Lee, S I; Oh, S G

    1999-01-01

    Amorphous titanium dioxide thin films were deposited onto silicon substrates by using RF magnetron sputtering, and the index of refraction, the extinction coefficient, and the void distribution of these films were simultaneously determined from the analyses of there ellipsometric spectra. In particular, our novel strategy, which combines the merits of multi-sample fitting, the dual dispersion function, and grid search, was proven successful in determining optical constants over a wide energy range, including the energy region where the extinction coefficient was large. Moreover, we found that the void distribution was dependent on the deposition conditions, such as the sputtering power, the substrate temperature, and the substrate surface.

  17. Plutonium distribution and remobilization in sediments of the Rhone River mouth (North-Western Mediterranean); Distribution et remobilisation du plutonium dans les sediments du prodelta du Rhone (Mediterranee nord-occidentale)

    Energy Technology Data Exchange (ETDEWEB)

    Lansard, B

    2004-06-15

    The aim of the present study was to describe the distribution and remobilization of plutonium (Pu) in the sediments off the Rhone river mouth. Most of the {sup 238}Pu and {sup 239,240}Pu isotopes introduced into the Rhone River were discharged by the liquid effluents released from the Marcoule reprocessing plant, located 120 km upstream the river mouth. Due to its high affinity for particles and its long half life, {sup 238}Pu is a promising tracer to follow the dispersion of particulate matter from the Rhone River to the Mediterranean Sea. During the 3 REMORA cruises, sediment samples were specifically collected in the Rhone pro-delta area and more offshore on the whole continental shelf of the Gulf of Lions. The measurements of alpha emitters gave a first detailed spatial distribution of Pu isotope concentrations in surface sediments off the Rhone mouth. Using {sup 137}Cs concentrations and their correlations with Pu isotopes, we were able to give a first estimate of Pu inventories for the sediments of the study area. In 2001, plutonium inventories were estimated to 92 {+-} 7 GBq of {sup 238}Pu and 522 {+-} 44 GBq of {sup 239,240}Pu for an area of 500 km{sup 2} in front of the Rhone River mouth. Roughly, 50 % of these inventories are trapped in an area of 100 km{sup 2} corresponding to the extent of the Rhone pro-delta zone. In spring 2002, an ADCP, with current velocity and wave measurements, was moored off the Rhone River mouth. This unique in situ dataset highlights the major role of South-East swells in the erosion of pro-deltaic sediments and their dispersion to the South-Westward direction. Plutonium remobilization was examined using a new experimental design based on sediment resuspension processes studied within a linear recirculating flume. For Gulf of Lions sediments and for a given hydrodynamic stress, remobilization fluxes raised a maximum of 0.08 Bq.m{sup -2}.h{sup -1} for {sup 238}Pu and 0.64 Bq.m{sup -2}.h{sup -1} for {sup 239,240}Pu. A first

  18. A novel method for the investigation of liquid/liquid distribution coefficients and interface permeabilities applied to the water-octanol-drug system.

    Science.gov (United States)

    Stein, Paul C; di Cagno, Massimiliano; Bauer-Brandl, Annette

    2011-09-01

    In this work a new, accurate and convenient technique for the measurement of distribution coefficients and membrane permeabilities based on nuclear magnetic resonance (NMR) is described. This method is a novel implementation of localized NMR spectroscopy and enables the simultaneous analysis of the drug content in the octanol and in the water phase without separation. For validation of the method, the distribution coefficients at pH = 7.4 of four active pharmaceutical ingredients (APIs), namely ibuprofen, ketoprofen, nadolol, and paracetamol (acetaminophen), were determined using a classical approach. These results were compared to the NMR experiments which are described in this work. For all substances, the respective distribution coefficients found with the two techniques coincided very well. Furthermore, the NMR experiments make it possible to follow the distribution of the drug between the phases as a function of position and time. Our results show that the technique, which is available on any modern NMR spectrometer, is well suited to the measurement of distribution coefficients. The experiments present also new insight into the dynamics of the water-octanol interface itself and permit measurement of the interface permeability.

  19. Distributing Characteristics of Heavy Metal Elements in A Tributary of Zhedong River in Laowangzhai Gold Deposit, Yunnan (China): An Implication to Environmentology from Sediments

    Science.gov (United States)

    Yang, Shuran; Danĕk, Tomáš; Yang, Xiaofeng; Cheng, Xianfeng

    2016-10-01

    Five heavy metal contents from five sediments and seven sediment profiles in an upstream reach of Zhedong river in Laowangzhai gold deposit were investigated in this research, along with analysis of the horizontal distribution, the surface distribution, the vertical distribution and the interlayer distribution of five heavy metal contents: arsenic (As), mercury (Hg), copper (Cu), lead (Pb) and zinc (Zn). The potential ecological risk of five heavy metals was evaluated to help understanding pollution control of Laowangzhai deposit.

  20. Ion Exchange Distribution Coefficient Tests and Computer Modeling at High Ionic Strength Supporting Technetium Removal Resin Maturation

    Energy Technology Data Exchange (ETDEWEB)

    Nash, Charles A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hamm, L. Larry [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Smith, Frank G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); McCabe, Daniel J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2014-12-19

    The primary treatment of the tank waste at the DOE Hanford site will be done in the Waste Treatment and Immobilization Plant (WTP) that is currently under construction. The baseline plan for this facility is to treat the waste, splitting it into High Level Waste (HLW) and Low Activity Waste (LAW). Both waste streams are then separately vitrified as glass and poured into canisters for disposition. The LAW glass will be disposed onsite in the Integrated Disposal Facility (IDF). There are currently no plans to treat the waste to remove technetium, so its disposition path is the LAW glass. Due to the water solubility properties of pertechnetate and long half-life of 99Tc, effective management of 99Tc is important to the overall success of the Hanford River Protection Project mission. To achieve the full target WTP throughput, additional LAW immobilization capacity is needed, and options are being explored to immobilize the supplemental LAW portion of the tank waste. Removal of 99Tc, followed by off-site disposal, would eliminate a key risk contributor for the IDF Performance Assessment (PA) for supplemental waste forms, and has potential to reduce treatment and disposal costs. Washington River Protection Solutions (WRPS) is developing some conceptual flow sheets for supplemental LAW treatment and disposal that could benefit from technetium removal. One of these flowsheets will specifically examine removing 99Tc from the LAW feed stream to supplemental immobilization. To enable an informed decision regarding the viability of technetium removal, further maturation of available technologies is being performed. This report contains results of experimental ion exchange distribution coefficient testing and computer modeling using the resin SuperLig® 639a to selectively remove perrhenate from high ionic strength simulated LAW. It is advantageous to operate at higher concentration in order to treat the waste

  1. Distribution of metals and extent of contamination in sediments from the south-eastern Baltic Sea (Lithuanian zone

    Directory of Open Access Journals (Sweden)

    Nijolė Remeikaitė-Nikienė

    2018-04-01

    Full Text Available Summary: The distribution of metals (Pb, Cu, Cd, Ni, Cr, Zn in surface sediments and the potential pollution sources in the south-eastern part (SE of the Baltic Sea (Lithuanian zone were investigated in relation to the environmental characteristics (amount of fine-grained particles, TOC content in sediments, origin of sedimentary organic matter, salinity, water depth in 2011–2014. The higher metal concentrations were measured in sediments of the Curonian Lagoon and in the open waters. An approach using various environmental indices (enrichment factor EF, geoaccumulation index Igeo and contamination factor CF was used to quantitatively assess a contamination degree. The principal component analysis (PCA was applied in order to further scrutinize pollution from metal sources. The values of the contamination indices showed no/very low sediment contamination with Ni and Cr, minor–moderate contamination with Cu, Zn and Pb and moderate–considerable pollution with Cd. The strong relationships among metals suggested their similar distribution pattern and a combination of natural and anthropogenic sources. The higher metal concentrations coincided with an increasing amount of fine-grained fraction and organic carbon. In the territorial waters, the distribution of elements was related to the water depth. In addition, the binding of metals with insoluble iron sulphides might explain their high concentrations at the most remote and deepest stations. Keywords: Metals, Enrichment factor, Geoaccumulation index, Contamination factor, The Baltic Sea, The Curonian Lagoon

  2. Unravelling mixed sediment signals in the floodplains of the Rhine catchment using end member modelling of grain size distributions

    NARCIS (Netherlands)

    Erkens, G.; Toonen, W.H.J.; Cohen, K.M.; Prins, M.A.

    2013-01-01

    During sediment transport downstream, river systems mix sediments from different parts of their catchments. During deposition, sediments are often unmixed again in different depositional environments (facies). During fluvial transport, between erosion and deposition of sediment, the sediment is

  3. Measurements of distribution coefficient for U and Th on sand stone in synthesized sea water and distilled water

    International Nuclear Information System (INIS)

    Nakazawa, Toshiyuki; Okada, Kenichi; Saito, Yoshihiko; Shibata, Masahiro; Sasamoto, Hiroshi

    2005-01-01

    Japan Nuclear Cycle Development Institute (JNC) has developed the sorption database for bentonite and rocks in order to assess the retardation property of important radioactive elements in natural and engineered barriers in the H12 report. However, there are not enough distribution coefficient data for radioactive elements in saline type groundwater in the database. Thus the batch sorption tests were performed for uranium (U) and thorium (Th) in saline type groundwater. For these elements, there are little registration numbers in the JNC's sorption database, and also these elements are important to evaluate the safety of disposal system. The experiments for each radioactive element were performed on the following conditions; U: Kd measurements using the solutions (synthesized sea water and distilled water) reacted with sand stone as a function of carbonate concentration, under reducing conditions. Th: Kd measurements using the solutions (synthesized sea water and distilled water) reacted with sand stone. The results of the experiments are summarized below; In the case of U, Kd was approximately 6.5E-01 - 9.2E-01 m 3 /kg in synthesized sea water. On the other hand, Kd was 2.2E-02 - 2.4E-02 m 3 /kg in the high carbonate solution. And also, Kd was 6.5E-02 - 7.2E-02 m 3 /kg in synthesized sea water adjusted pH 10 and 3.4E-02 - 4.1E-02 m 3 /kg in distilled water adjusted pH 10, respectively. In the case of Th, Kd was measured in synthesized sea water adjusted to pH 10 and in distilled water adjusted to pH 10. At the sorption measurements of Th, precipitation might be occurred by very low solubility of Th. (author)

  4. Sediment distribution and hydrologic conditions of the Potomac aquifer in Virginia and parts of Maryland and North Carolina

    Science.gov (United States)

    McFarland, Randolph E.

    2013-01-01

    . Immature, high-gradient braided streams deposited longitudinal bars and channel fills across the Norfolk arch subarea. By contrast, across the Salisbury and Albemarle embayment subareas, mature, medium- to low-gradient meandering streams deposited medium- to coarse-grained channel fills and point bars segregated from fine-grained overbank deposits. The Virginia depositional complex merged northward across the Salisbury embayment subarea with another complex in Maryland. Here, additional sediments were received from schist source rocks that underwent three cycles of initial uplift and rapid erosion followed by crustal stability and erosional leveling. Because of the predominance of coarse-grained sediments, transmissivity, hydraulic conductivity, and regional velocities of lateral flow through the Potomac aquifer are greatest across the Norfolk arch depositional subarea, but decrease progressively northward with increasingly fine-grained sediments. Confining units hydraulically separate the Potomac aquifer from overlying aquifers, as indicated by large vertical hydraulic gradients. By contrast, most of the Potomac aquifer internally functions hydraulically as a single interconnected aquifer, as indicated by uniformly small vertical gradients. Most fine-grained sediments within the aquifer do not hydraulically separate overlying and underlying coarse-grained sediments. Across the Salisbury embayment depositional subarea, however, hydraulic separation among the vertically spaced subaquifers is imposed by the intervening confining units. The Potomac aquifer is the largest and most heavily used source of groundwater in the Virginia Coastal Plain. Water-level declines as great as 200 feet create the potential for saltwater intrusion. Conventional stratigraphic correlation has been generally ineffective at accurately characterizing complexly distributed fluvial sediments that compose the Potomac aquifer. Consequently, the aquifer’s internal hydraulic connectivity and overall

  5. The Spatial Distribution of Bed Sediment on Fluvial System: A Mini Review of the Aceh Meandering River

    Directory of Open Access Journals (Sweden)

    Muhammad Irham

    2016-08-01

    Full Text Available Dynamic interactions of hydrological and geomorphological processes in the fluvial system result in accumulated deposit on the bed because the capacity to carry sediment has been exceeded. The bed load of the Aceh fluvial system is primarily generated by mechanical weathering resulting in boulders, pebbles, and sand, which roll or bounce along the river bed forming temporary deposits as bars on the insides of meander bends, as a result of a loss of transport energy in the system. This dynamic controls the style and range of deposits in the Aceh River. This study focuses on the spatial distribution of bed-load transport of the Aceh River. Understanding the spatial distribution of deposits facilitates the reconstruction of the changes in controlling factors during accumulation of deposits. One of the methods can be done by sieve analysis of sediment, where the method illuminates the distribution of sediment changes associated with channel morphology under different flow regimes. Hence, the purpose of this mini review is to investigate how the sediment along the river meander spatially dispersed. The results demonstrate that channel deposits in the Aceh River are formed from four different type of materials: pebble deposited along upstream left bank; sand located on the upstream, downstream, and along meander belts; and silt and clay located along the cut bank of meander bends. Because of different depositional pattern, the distribution of the sediment along the river can be used as a surrogate to identify bank stability, as well as to predict critical geometry for meander bend initiation

  6. Radioactivity in Norwegian Waters: Distribution in seawater and sediments, and uptake in marine organisms

    International Nuclear Information System (INIS)

    Heldal, Hilde Elise

    2001-01-01

    Prior to the detonation of the first thermonuclear bomb, small amounts of radioactivity, for example in mineral water, were considered to be health enriching. Negative experiences related to thermonuclear bombs and several nuclear accidents have, however, changed people's attitude towards radioactivity during the past 40-50 years. Today, there is a common concern for regular and potential accidental releases of radioactivity from sources such as Sellafield. Although this is important, incorrect assessments of the effects of these releases (e.g. created by uncritical journalism) have the potential to harm the country's fisheries and economy. Therefore, it is of major importance to document up-to-date levels of radioactive contamination of the marine environment, and be able to place these into the proper perspectives. The main topics of the thesis may be summarised as follows: (1) Distribution of Caesium-137, Plutonium-238, Plutonium-239,240 and Americium-241 in sediments with emphasis on the Spitsbergen-Bear Island area, (2) Uptake of Caesium-137 in phytoplankton representative for the Barents and Norwegian Seas phytoplankton communities (laboratory experiments), (3) Bioaccumulation of Caesium-137 in food webs in the Barents and Norwegian Seas, (4) Geographical variations of Caesium-137 in harbour porpoises (Phocoena phocoena) along the Norwegian coast, (5) Transport times for Technetium-99 from Sellafield to various locations along the Norwegian coast and the Arctic Ocean

  7. Radioactivity in Norwegian Waters: Distribution in seawater and sediments, and uptake in marine organisms

    Energy Technology Data Exchange (ETDEWEB)

    Heldal, Hilde Elise

    2001-07-01

    Prior to the detonation of the first thermonuclear bomb, small amounts of radioactivity, for example in mineral water, were considered to be health enriching. Negative experiences related to thermonuclear bombs and several nuclear accidents have, however, changed people's attitude towards radioactivity during the past 40-50 years. Today, there is a common concern for regular and potential accidental releases of radioactivity from sources such as Sellafield. Although this is important, incorrect assessments of the effects of these releases (e.g. created by uncritical journalism) have the potential to harm the country's fisheries and economy. Therefore, it is of major importance to document up-to-date levels of radioactive contamination of the marine environment, and be able to place these into the proper perspectives. The main topics of the thesis may be summarised as follows: (1) Distribution of Caesium-137, Plutonium-238, Plutonium-239,240 and Americium-241 in sediments with emphasis on the Spitsbergen-Bear Island area, (2) Uptake of Caesium-137 in phytoplankton representative for the Barents and Norwegian Seas phytoplankton communities (laboratory experiments), (3) Bioaccumulation of Caesium-137 in food webs in the Barents and Norwegian Seas, (4) Geographical variations of Caesium-137 in harbour porpoises (Phocoena phocoena) along the Norwegian coast, (5) Transport times for Technetium-99 from Sellafield to various locations along the Norwegian coast and the Arctic Ocean.

  8. Radioactivity in Norwegian Waters: Distribution in seawater and sediments, and uptake in marine organisms

    Energy Technology Data Exchange (ETDEWEB)

    Heldal, Hilde Elise

    2001-07-01

    Prior to the detonation of the first thermonuclear bomb, small amounts of radioactivity, for example in mineral water, were considered to be health enriching. Negative experiences related to thermonuclear bombs and several nuclear accidents have, however, changed people's attitude towards radioactivity during the past 40-50 years. Today, there is a common concern for regular and potential accidental releases of radioactivity from sources such as Sellafield. Although this is important, incorrect assessments of the effects of these releases (e.g. created by uncritical journalism) have the potential to harm the country's fisheries and economy. Therefore, it is of major importance to document up-to-date levels of radioactive contamination of the marine environment, and be able to place these into the proper perspectives. The main topics of the thesis may be summarised as follows: (1) Distribution of Caesium-137, Plutonium-238, Plutonium-239,240 and Americium-241 in sediments with emphasis on the Spitsbergen-Bear Island area, (2) Uptake of Caesium-137 in phytoplankton representative for the Barents and Norwegian Seas phytoplankton communities (laboratory experiments), (3) Bioaccumulation of Caesium-137 in food webs in the Barents and Norwegian Seas, (4) Geographical variations of Caesium-137 in harbour porpoises (Phocoena phocoena) along the Norwegian coast, (5) Transport times for Technetium-99 from Sellafield to various locations along the Norwegian coast and the Arctic Ocean.

  9. Distribution, sources and ecological risk assessment of PAHs in surface sediments from the Luan River Estuary, China.

    Science.gov (United States)

    Zhang, Daolai; Liu, Jinqing; Jiang, Xuejun; Cao, Ke; Yin, Ping; Zhang, Xunhua

    2016-01-15

    The distribution, sources and risk assessment of 16 polycyclic aromatic hydrocarbons (PAHs) of surface sediments in the Luan River Estuary, China, have been investigated in the research. The results indicated that the total concentrations of 16 PAHs in surface sediments of the Luan River Estuary ranged from 5.1 to 545.1 ng g(-1)dw with a mean value of 120.8 ng g(-1)dw, which is relatively low in comparison with other estuaries around the world. The PAHs in the study area were mainly originated from pyrogenic sources. Besides, PAHs may be contaminated by petrogenic PAHs as indicated by the selected ratios of PAHs, the 2-tailed Pearson correlation analysis and principal components analysis at different sites. The result of the ecological risk assessment shows little negative effect for most individual PAHs in surface sediments of the Luan River Estuary, China. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Particle size distribution and characteristics of heavy metals in road-deposited sediments from Beijing Olympic Park.

    Science.gov (United States)

    Li, Haiyan; Shi, Anbang; Zhang, Xiaoran

    2015-06-01

    Due to rapid urbanization and industrialization, heavy metals in road-deposited sediments (RDSs) of parks are emitted into the terrestrial, atmospheric, and water environment, and have a severe impact on residents' and tourists' health. To identify the distribution and characteristic of heavy metals in RDS and to assess the road environmental quality in Chinese parks, samples were collected from Beijing Olympic Park in the present study. The results indicated that particles with small grain size (Pb>Cu>Zn. This study analyzed the mobility of heavy metals in sediments using partial sequential extraction with the Tessier procedure. The results revealed that the apparent mobility and potential metal bioavailability of heavy metals in the sediments, based on the exchangeable and carbonate fractions, decreased in the order: Cd>Zn≈Pb>Cu. Copyright © 2015. Published by Elsevier B.V.

  11. Distribution and sources of polycyclic aromatic hydrocarbons in surface sediments from the Bering Sea and western Arctic Ocean.

    Science.gov (United States)

    Zhao, Mengwei; Wang, Weiguo; Liu, Yanguang; Dong, Linsen; Jiao, Liping; Hu, Limin; Fan, Dejiang

    2016-03-15

    To analyze the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) and evaluate their potential ecological risks, the concentrations of 16 PAHs were measured in 43 surface sediment samples from the Bering Sea and western Arctic Ocean. Total PAH (tPAH) concentrations ranged from 36.95 to 150.21 ng/g (dry weight). In descending order, the surface sediment tPAH concentrations were as follows: Canada Basin>northern Chukchi Sea>Chukchi Basin>southern Chukchi Sea>Aleutian Basin>Makarov Basin>Bering Sea shelf. The Bering Sea and western Arctic Ocean mainly received PAHs of pyrogenic origin due to pollution caused by the incomplete combustion of fossil fuels. The concentrations of PAHs in the sediments of the study areas did not exceed effects range low (ERL) values. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Micro-spatial variation of elemental distribution in estuarine sediment and their accumulation in mangroves of Indian Sundarban.

    Science.gov (United States)

    Bakshi, Madhurima; Ram, S S; Ghosh, Somdeep; Chakraborty, Anindita; Sudarshan, M; Chaudhuri, Punarbasu

    2017-05-01

    This work describes the micro-spatial variation of elemental distribution in estuarine sediment and bioaccumulation of those elements in different mangrove species of the Indian Sundarbans. The potential ecological risk due to such elemental load on this mangrove-dominated habitat is also discussed. The concentrations of elements in mangrove leaves and sediments were determined using energy-dispersive X-ray fluorescence spectroscopy. Sediment quality and potential ecological risks were assessed from the calculated indices. Our data reflects higher concentration of elements, e.g., Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, and Pb, in the sediment, as compared to that reported by earlier workers. Biological concentration factors for K, Ca, Mn, Fe, Cu, and Zn in different mangroves indicated gradual elemental bioaccumulation in leaf tissues (0.002-1.442). Significant variation was observed for elements, e.g., Ni, Mn, and Ca, in the sediments of all the sites, whereas in the plants, significant variation was found for P, S, Cl, K, Ca, Mn, Fe, Cu, and Zn. This was mostly due to the differences in uptake and accumulation potential of the plants. Various sediment quality indices suggested the surface sediments to be moderately contaminated and suffering from progressive deterioration. Cu, Cr, Zn, Mn, and Ni showed higher enrichment factors (0.658-1.469), contamination factors (1.02-2.7), and geo-accumulation index (0.043-0.846) values. The potential ecological risk index values considering Cu, Cr, Pb, and Zn were found to be within "low ecological risk" category (20.04-24.01). However, Cr and Ni in the Sundarban mangroves exceeded the effect range low and probable effect level limits. Strong correlation of Zn with Fe and K was observed, reflecting their similar transportation and accumulation process in both sediment and plant systems. The plant-sediment elemental correlation was found to be highly non-linear, suggesting role of some physiological and edaphic factors in

  13. Heavy metals in soils and sediments from Dongting Lake in China: occurrence, sources, and spatial distribution by multivariate statistical analysis.

    Science.gov (United States)

    Zhang, Yaxin; Tian, Ye; Shen, Maocai; Zeng, Guangming

    2018-03-03

    Heavy metal contamination in soils/sediments and its impact on human health and ecological environment have aroused wide concerns. Our study investigated 30 samples of soils and sediments around Dongting Lake to analyze the concentration of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn in the samples and to distinguish the natural and anthropogenic sources. Also, the relationship between heavy metals and the physicochemical properties of samples was studied by multivariate statistical analysis. Concentration of Cd at most sampling sites were more than five times that of national environmental quality standard for soil in China (GB 15618-1995), and Pb and Zn levels exceeded one to two times. Moreover, Cr in the soil was higher than the national environmental quality standards for one to two times while in sediment was lower than the national standard. The investigation revealed that the accumulations of As, Cd, Mn, and Pb in the soils, and sediments were affected apparently by anthropogenic activities; however, Cr, Fe, and Ni levels were impacted by parent materials. Human activities around Dongting Lake mainly consisted of industrial activities, mining and smelting, sewage discharges, fossil fuel combustion, and agricultural chemicals. The spatial distribution of heavy metal in soil followed the rule of geographical gradient, whereas in sediments, it was significantly affected by the river basins and human activities. The result of principal component analysis (PCA) demonstrated that heavy metals in soils were associated with pH and total phosphorus (TP), while in sediments, As, Cr, Fe, and Ni were closely associated with cation exchange capacity (CEC) and pH, where Pb, Zn, and Cd were associated with total nitrogen (TN), TP, total carbon (TC), moisture content (MC), soil organic matter (SOM), and ignition lost (IL). Our research provides comprehensive approaches to better understand the potential sources and the fate of contaminants in lakeshore soils and sediments.

  14. Multivariate geostatistical modeling of the spatial sediment distribution in a large scale drainage basin, Upper Rhone, Switzerland

    Science.gov (United States)

    Schoch, Anna; Blöthe, Jan Henrik; Hoffmann, Thomas; Schrott, Lothar

    2018-02-01

    There is a notable discrepancy between detailed sediment budget studies in small headwater catchments ( 103 km2) in higher order catchments applying modeling and/or remote sensing based approaches for major sediment storage delineation. To bridge the gap between these scales, we compiled an inventory of sediment and bedrock coverage from field mapping, remote sensing analysis and published data for five key sites in the Upper Rhone Basin (Val d'Illiez, Val de la Liène, Turtmanntal, Lötschental, Goms; 360.3 km2, equivalent to 6.7% of the Upper Rhone Basin). This inventory was used as training and testing data for the classification of sediment and bedrock cover. From a digital elevation model (2 × 2 m ground resolution) and Landsat imagery we derived 22 parameters characterizing local morphometry, topography and position, contributing area, and climatic and biotic factors on different spatial scales, which were used as inputs for different statistical models (logistic regression, principal component logistic regression, generalized additive model). Best prediction results with an excellent performance (mean AUROC: 0.8721 ± 0.0012) and both a high spatial and non-spatial transferability were achieved applying a generalized additive model. Since the model has a high thematic consistency, the independent input variables chosen based on their geomorphic relevance are suitable to model the spatial distribution of sediment. Our high-resolution classification shows that 53.5 ± 21.7% of the Upper Rhone Basin are covered with sediment. These are by no means evenly distributed: small headwaters (analysis.

  15. Brominated flame retardants in mangrove sediments of the Pearl River Estuary, South China: spatial distribution, temporal trend and mass inventory.

    Science.gov (United States)

    Zhang, Zai-Wang; Sun, Yu-Xin; Sun, Kai-Feng; Xu, Xiang-Rong; Yu, Shen; Zheng, Tian-Ling; Luo, Xiao-Jun; Tian, Yun; Hu, Yong-Xia; Diao, Zeng-Hui; Mai, Bi-Xian

    2015-03-01

    Sediments were collected from three mangrove wetlands in the Pearl River Estuary (PRE) of South China to investigate spatial and temporal distributions of polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE). Concentrations of ΣPBDEs, DBDPE and BTBPE in mangrove sediments of the PRE ranged from 1.25-206, 0.364-34.9, and not detected-0.794 ng g(-1) dry weight, respectively. The highest concentrations of ΣPBDEs, DBDPE and BTBPE were found at the mangrove wetland from Shenzhen, followed by Zhuhai and Guangzhou, showing the dependence on the proximity to urban areas. PBDEs were the predominant brominated flame retardants (BFRs) in mangrove sediments. The concentrations of ΣPBDEs, DBDPE and BTBPE in sediment cores showed an increasing trend from the bottom to top layers, reflecting the increasing usage of these BFRs. The inventories of ΣPBDEs, DBDPE and BTBPE in mangrove sediments were 1962, 245, and 4.10 ng cm(-2), respectively. This is the first study to report the occurrence of DBDPE and BTBPE in mangrove ecosystems. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Distribution of polybrominated diphenyl ethers in sediments of the Pearl River Delta and adjacent South China Sea.

    Science.gov (United States)

    Mai, Bixian; Chen, Shejun; Luo, Xiaojun; Chen, Laiguo; Yang, Qingshu; Sheng, Guoying; Peng, Pingan; Fu, Jiamo; Zeng, Eddy Y

    2005-05-15

    Spatial and temporal distributions of polybrominated diphenyl ethers (PBDEs) in sediments of the Pearl River Delta (PRD) and adjacent South China Sea (SCS) of southern China were examined. A total of 66 surface sediment samples were collected and analyzed to determine the concentrations of 10 PBDE congeners (BDE-28, -47, -66, -100, -99, -154, -153, -138, -183, and -209). The concentrations of BDE-209 and SigmaPBDEs (defined as the sum of all targeted PBDE congeners except for BDE-209) ranged from 0.4 to 7340 and from 0.04 to 94.7 ng/g, respectively. The SigmaPBDEs concentrations were mostly transportation. The PBDE patterns in the SCS and Pearl River Estuary sediments were similar to those in sediments of the Zhujiang and Dongjiang Rivers, reflecting the widespread influence from local inputs. Analyses of two short sediment cores collected from the Pearl River Estuary showed that concentrations of BDE-209 rapidly increased in the upper layers of both cores, coincident with the growth of the electronics manufacturing capacities in the PRD region. The major sources of PBDEs were probably waste discharges from the cities of Guangzhou, Dongguan, and Shenzhen, the three fastest growing urban centers in the PRD.

  17. Distribution of metals in fauna, flora and sediments of wet detention ponds and natural shallow lakes

    DEFF Research Database (Denmark)

    Stephansen, D.A.; Nielsen, A.H.; Hvitved-Jacobsen, T.

    2014-01-01

    Fauna, flora, and sediment were collected from 9 wet detention ponds receiving stormwater runoff and 11 small natural shallow lakes. The fauna and flora samples were sorted into species or groups of species and, together with sediments, analyzed for aluminum, copper, iron, zinc, arsenic, cadmium,...

  18. Distribution of longshore sediment transport along the Indian coast based on empirical model

    Digital Repository Service at National Institute of Oceanography (India)

    Chandramohan, P.; Nayak, B.U.

    An empirical sediment transport model has been developed based on longshore energy flux equation. Study indicates that annual gross sediment transport rate is high (1.5 x 10 super(6) cubic meters to 2.0 x 10 super(6) cubic meters) along the coasts...

  19. Distribution of naturally occurring radionuclides activity concentration in East Malaysian marine sediment

    Energy Technology Data Exchange (ETDEWEB)

    Yii, M.W. [Malaysian Nuclear Agency (Nuclear Malaysia), Bangi, 43000 Kajang (Malaysia)], E-mail: yii@nuclearmalaysia.gov.my; Zaharudin, A.; Abdul-Kadir, I. [Malaysian Nuclear Agency (Nuclear Malaysia), Bangi, 43000 Kajang (Malaysia)

    2009-04-15

    Studies of naturally occurring radioactive materials (NORM) distribution of {sup 226}Ra, {sup 228}Ra and {sup 40}K in East Malaysia were carried out as part of a marine coastal environment project. The results of measurements will serve as baseline data and background reference level for Malaysia coastlines. Sediments from 21 coastal locations and 10 near shore locations were collected for analyses. The samples were dried, finely ground, sealed in a container and stored for a minimum of 30 days to establish secular equilibrium between {sup 226}Ra and {sup 228}Ra and their respective radioactive progenies. They were counted using a high-purity germanium (HPGe) spectrometer covering the respective progeny energy peak. For {sup 40}K, the presence of this was measured directly via its 1460 keV energy peak. The concentration of {sup 226}Ra, {sup 228}Ra and {sup 40}K in samples obtained from coastal Sarawak ranged between 23 and 41 (mean 30{+-}2) Bq/kg, 27 and 45 (mean 39{+-}4) Bq/kg and 142 and 680 (mean 462{+-}59) Bq/kg, respectively. Meanwhile, the concentration of {sup 226}Ra, {sup 228}Ra and {sup 40}K for samples obtained from coastal Sabah ranged between 16 and 30 (mean 23{+-}2) Bq/kg, 23 and 45 (mean 35{+-}4) Bq/kg and 402 and 842 (mean 577{+-}75) Bq/kg, respectively. For the Sarawak near shore stations, the concentration of {sup 226}Ra, {sup 228}Ra and {sup 40}K ranged between 11 and 36 (mean 22{+-}2) Bq/kg, 21 and 65 (mean 39{+-}5) Bq/kg and 149 and 517 (mean 309{+-}41) Bq/kg, respectively. Meanwhile, the concentration of {sup 226}Ra, {sup 228}Ra and {sup 40}K for samples obtained from Sabah ranged between 9 and 31 (mean 14{+-}2) Bq/kg, 10 and 48 (mean 21{+-}3) Bq/kg and 140 and 580 (mean 269{+-}36) Bq/kg, respectively. The calculated external hazard values of between 0.17 and 0.33 (less than unity) showed that there is little risk of external hazard to the workers handling the sediments.

  20. Distribution and abundance of archaeal and bacterial ammonia oxidizers in the sediments of the Dongjiang River, a drinking water supply for Hong Kong.

    Science.gov (United States)

    Sun, Wei; Xia, Chunyu; Xu, Meiying; Guo, Jun; Wang, Aijie; Sun, Guoping

    2013-01-01

    Ammonia-oxidizing archaea (AOA) and bacteria (AOB) play important roles in nitrification. However, limited information about the characteristics of AOA and AOB in the river ecosystem is available. The distribution and abundance of AOA and AOB in the sediments of the Dongjiang River, a drinking water source for Hong Kong, were investigated by clone library analysis and quantitative real-time PCR. Phylogenetic analysis showed that Group 1.1b- and Group 1.1b-associated sequences of AOA predominated in sediments with comparatively high carbon and nitrogen contents (e.g. total carbon (TC) >13 g kg(-1) sediment, NH4(+)-N >144 mg kg(-1) sediment), while Group 1.1a- and Group 1.1a-associated sequences were dominant in sediments with opposite conditions (e.g. TC <4 g kg(-1) sediment, NH4(+)-N <93 mg kg(-1) sediment). Although Nitrosomonas- and Nitrosospira-related sequences of AOB were detected in the sediments, nearly 70% of the sequences fell into the Nitrosomonas-like B cluster, suggesting similar sediment AOB communities along the river. Higher abundance of AOB than AOA was observed in almost all of the sediments in the Dongjiang River, while significant correlations were only detected between the distribution of AOA and the sediment pH and TC, which suggested that AOA responded more sensitively than AOB to variations of environmental factors. These results extend our knowledge about the environmental responses of ammonia oxidizers in the river ecosystem.

  1. Distribution of butyltins in the waters and sediments along the coast of India.

    Science.gov (United States)

    Garg, Anita; Meena, Ram M; Jadhav, Sangeeta; Bhosle, Narayan B

    2011-02-01

    Water and surface sediment samples were analyzed for butyltins (TBT, DBT, MBT) from various ports along the east and west coast of India. The total butyltin (TB) in water samples varied between ~1.7 and 342 ng S nl⁻¹, whereas for sediments it varied between below detection limit to 14861 ng S ng⁻¹ dry weight of sediment. On an average Chennai port recorded the highest level of butyltins in the sediments while Paradip recorded the highest level of butylins in the waters. A fairly good relationship between the TB in the sediment and overlying water samples, as well as between organic carbon and TB, implicates the importance of adsorption/desorption process in controlling the levels of TBT in these port areas. In India the data on organotin pollution is very sparse; most of the port areas have been surveyed for butyltins for the first time during this study. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Late Holocene distribution of lake sediment and peat in NE Uppland, Sweden

    International Nuclear Information System (INIS)

    Bergstroem, Elisabeth

    2001-02-01

    This report is part of a larger project conducted by SKB. The aim is to carry out investigations of eight lakes and one bog, with respect to stratigraphic and geographic distribution of sediment and peat. More than 150 corings were made with a Russian peat sampler. The bog was investigated regarding its isolation from the Baltic basin. This site is included in the shore displacement model elaborated from other sites situated at the same isobase for the Litorina Sea. Northern Uppland is an area with a smooth topography, which also affects the lake basins. The water depth is generally shallow, 1-3 metres. The bedrock mainly consists of granitoids. A few areas consist of meta volcanics, younger granites and pegmatites. The Quaternary deposits in Uppland are more or less calcareous, which is reflected in the rich flora with e. g. orchids and saw grass. Till is the most common deposit in the area covering considerable areas but rarely forming geomorphological features. Glaciofluvial deposits i. e. eskers, stretches in more or less S-N direction, being generally small. In northern Uppland, large areas are covered by mires. Most of them are affected by human activities in the form of ditching; some are used for cultivation or as pasture land. One site, Vissomossen, with a levelled isolation threshold at 27. 4 m a. s. l. , is mainly a fen, with a bog developing in the central part. Diatom analyses and AMS dates show that the basin was earlier a bay of the Litorina Sea and isolated 3500-3600 14 C years BP. The former lake basin was as large as the present extension of the mire. Accumulated material reveals that the lake during time has been filled in with sediment, overgrown and finally forming a mire. The result of the present study is summarized as an extended shore displacement model for northern Uppland, and it reflects an ongoing regression in the area. A decline in regression can be compared with the Litorina transgression 3 (L3), which in the Stockholm area is dated

  3. Late Holocene distribution of lake sediment and peat in NE Uppland, Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Bergstroem, Elisabeth [Stockholm Univ. (Sweden). Dept. of Physical Geography and Quaternary Geology

    2001-02-01

    This report is part of a larger project conducted by SKB. The aim is to carry out investigations of eight lakes and one bog, with respect to stratigraphic and geographic distribution of sediment and peat. More than 150 corings were made with a Russian peat sampler. The bog was investigated regarding its isolation from the Baltic basin. This site is included in the shore displacement model elaborated from other sites situated at the same isobase for the Litorina Sea. Northern Uppland is an area with a smooth topography, which also affects the lake basins. The water depth is generally shallow, 1-3 metres. The bedrock mainly consists of granitoids. A few areas consist of meta volcanics, younger granites and pegmatites. The Quaternary deposits in Uppland are more or less calcareous, which is reflected in the rich flora with e. g. orchids and saw grass. Till is the most common deposit in the area covering considerable areas but rarely forming geomorphological features. Glaciofluvial deposits i. e. eskers, stretches in more or less S-N direction, being generally small. In northern Uppland, large areas are covered by mires. Most of them are affected by human activities in the form of ditching; some are used for cultivation or as pasture land. One site, Vissomossen, with a levelled isolation threshold at 27. 4 m a. s. l. , is mainly a fen, with a bog developing in the central part. Diatom analyses and AMS dates show that the basin was earlier a bay of the Litorina Sea and isolated 3500-3600 {sup 14}C years BP. The former lake basin was as large as the present extension of the mire. Accumulated material reveals that the lake during time has been filled in with sediment, overgrown and finally forming a mire. The result of the present study is summarized as an extended shore displacement model for northern Uppland, and it reflects an ongoing regression in the area. A decline in regression can be compared with the Litorina transgression 3 (L3), which in the Stockholm area is

  4. Measurements of distribution coefficient for Sn, Pb and Th on sand stone and tuff in saline type groundwater

    International Nuclear Information System (INIS)

    Nakazawa, Toshiyuki; Okada, Kenichi; Muroi, Masayuki; Shibata, Masahiro; Sasamoto, Hiroshi

    2004-02-01

    Japan Nuclear Cycle Development Institute (JNC) has developed the sorption database for bentonite and rocks in order to assess the retardation capacities of important radioactive elements in natural and engineered barriers in the H12 report. However, there are not enough distribution coefficient data for radioactive elements in saline type groundwater in the database. Sn (tin), Pb (lead) and Th(thorium) are important radioactive elements for performance assessment of high level r