WorldWideScience

Sample records for surface sediment cores

  1. Sediment Core Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides instrumentation and expertise for physical and geoacoustic characterization of marine sediments.DESCRIPTION: The multisensor core logger measures...

  2. Surface (sea floor) and near-surface (box cores) sediment mineralogy in Baffin Bay as a key to sediment provenance and ice sheet variations

    Science.gov (United States)

    Andrews, John T.; Eberl, D.D.

    2011-01-01

    To better understand the glacial history of the ice sheets surrounding Baffin Bay and to provide information on sediment pathways, samples from 82 seafloor grabs and core tops, and from seven box cores were subjected to quantitative X-ray diffraction weight percent (wt.%) analysis of the 2000 m) all show an abrupt drop in calcite wt.% (post-5 cal ka BP?) following a major peak in detrital carbonate (mainly dolomite). This dolomite-rich detrital carbonate (DC) event in JR175BC06 is possibly coeval with the Younger Dryas cold event. Four possible glacial-sourced end members were employed in a compositional unmixing algorithm to gain insight into down core changes in sediment provenance at the deep central basin. Estimates of the rates of sediment accumulation in the central basin are only in the range of 2 to 4 cm/cal ka, surprisingly low given the glaciated nature of the surrounding land.

  3. An optimized method for the analysis of cyclic and linear siloxanes and their distribution in surface and core sediments from industrialized bays in Korea.

    Science.gov (United States)

    Lee, Sang-Yoon; Lee, Sunggyu; Choi, Minkyu; Kannan, Kurunthachalam; Moon, Hyo-Bang

    2018-05-01

    Environmental contamination by siloxanes is a matter of concern due to their widespread consumption in personal care as well as industrial products and potential toxicity. Nevertheless, methods for simultaneous determination of cyclic and linear siloxanes in sediment are lacking. In this study, we developed an optimized analytical method to determine cyclic and linear siloxanes based on gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). This method was applied to determine concentrations of 19 siloxane compounds in surface and core sediments from industrialized bays in Korea to assess contamination status, spatial distribution, and historical trends. Total concentrations of siloxanes ranged from 15.0 to 11730 (mean: 712) ng/g dry weight, which were similar to or higher than those reported in other countries. The highest concentrations of siloxanes were found in rivers/streams that discharge into coastal waters and bays close to industrial complexes, indicating that industrial activities are major sources of siloxane contamination. Cyclic siloxanes such as D5 and D6 were predominant in surface and core sediments. A significant correlation existed between the concentrations of cyclic and linear siloxanes, suggesting similar sources in the marine coastal environment. The historical record of cyclic siloxanes in core sediments revealed a clear increasing trend since the 1970s. This finding is consistent with the history of local industrialization and global production of siloxanes. This is the first study of historical trends in siloxanes in the coastal environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Characteristics of Air Core and Surface Velocity for Water Flow in a Vortex Sediment-Extraction Chamber Measured by Using Photo Images and PTV Technique.

    Science.gov (United States)

    Yao, Hou Chang; Chyan Deng, Jan; Chao, Hsu Yu; Chih Yuan, Yang

    2017-04-01

    A vortex sediment-extraction chamber, consisted of cylindrical chamber, inflow system, bottom orifice and overflow weir, is used to separate sediment from sediment-laden water flow. A tangential inflow is introduced into a cylindrical chamber with a bottom orifice; thus, a strong vortex flow is produced there. Under actions of gravity and centrifugal force, heavier sediment particles are forced to move towards the bottom orifice, and relatively clear water flows over through the top overflow weir. The flow field in the cylindrical chamber consists of forced vortex and free vortex. When the bottom orifice is opened during the sediment-extraction process, an air core appears and changes with different settings. In this study, the air core and water surface velocity in the cylindrical chamber were measured by using a photo image process and particle tracking velocimetry (PTV), as well as numerically simulated by using a commercial software, Flow-3D.Laboratory experiments were conducted in a vortex chamber, having height of 130 cm and diameter of 48 cm. Five kinds of bottom orifice size from 1.0 cm to 3.0 cm and four kinds of inflow water discharge from 1,300cm3/s to 1,700 cm3/s were used while the inflow pipe of 3 cm in diameter was kept the same for all experiments. The characteristics of the air core and water surface velocity, and the inflow and outflow ratios under different experimental arrangements were observed and discussed so as to provide a better design and application for a vortex sediment-extraction chamber in the future.

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

    Science.gov (United States)

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

  6. Geochemistry of sediment cores of the western equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, P.S.N.; Cronan, D.S.; Rao, Ch.M.; Paropkari, A.L.; Topgi, R.S.; Guptha, M.V.S.; Colley, N.

    Geochemical investigations including partition analysis have been carried out on nine sediment cores from the western equatorial Indian Ocean. The results show that a core from the Arabian Sea exhibits a greater terrigenous influence than cores from...

  7. Barium and calcium analyses in sediment cores using µ-XRF core scanners

    Science.gov (United States)

    Acar, Dursun; Çaǧatay, Namık; Genç, S. Can; Eriş, K. Kadir; Sarı, Erol; Uçarkus, Gülsen

    2017-04-01

    Barium and Ca are used as proxies for organic productivity in paleooceanographic studies. With its heavy atomic weight (137.33 u), barium is easily detectable in small concentrations (several ppm levels) in marine sediments using XRF methods, including the analysis by µ-XRF core scanners. Calcium has an intermediate atomic weight (40.078 u) but is a major element in the earth's crust and in sediments and sedimentary rocks, and hence it is easily detectable by µ-XRF techniques. Normally, µ-XRF elemental analysis of cores are carried out using split half cores or 1-2 cm thich u-channels with an original moisture. Sediment cores show variation in different water content (and porosity) along their length. This in turn results in variation in the XRF counts of the elements and causes error in the elemental concentrations. We tried µ-XRF elemental analysis of split half cores, subsampled as 1 cm thick u-channels with original moisture and 0.3 mm-thin film slices of the core with original wet sample and after air drying with humidity protector mylar film. We found considerable increase in counts of most elements, and in particular for Ba and Ca, when we used 0.3 mm thin film, dried slice. In the case of Ba, the counts increased about three times that of the analysis made with wet and 1 cm thick u-channels. The higher Ba and Ca counts are mainly due to the possible precipitation of Ba as barite and Ca as gypsum from oxidation of Fe-sulphides and the evaporation of pore waters. The secondary barite and gypsum precipitation would be especially serious in unoxic sediment units, such as sapropels, with considerable Fe-sulphides and bio-barite.It is therefore suggested that reseachers should be cautious of such secondary precipitation on core surfaces when analyzing cores that have long been exposed to the atmospheric conditions.

  8. The contribution of bank and surface sediments to fluvial sediment ...

    African Journals Online (AJOL)

    Sediment source studies involving a simple mixing model was undertaken in the Pra River Basin in Ghana using a single tracer 210Pb to determine the relative contribution of surface and bank sediments to the fluvial sediment transport. Sediment source tracing was performed on the basis of sub-basins by comparing the ...

  9. Organophosphate esters in sediment cores from coastal Laizhou Bay of the Bohai Sea, China.

    Science.gov (United States)

    Wang, Yan; Wu, Xiaowei; Zhang, Qiaonan; Hou, Minmin; Zhao, Hongxia; Xie, Qing; Du, Juan; Chen, Jingwen

    2017-12-31

    Concentrations and vertical distributions of organophosphate esters (OPEs) were investigated in the sediment cores collected from the Laizhou Bay, Bohai Sea of China. The total concentrations of OPEs in the sediment core (CA) collected near the Yellow River Estuary were in the range of 11.8-102ng/g, while the total concentrations in the sediment core (CB) near a mariculture area were 6.65-41.5ng/g. Significantly high concentrations of OPEs were found in the sediments near the Yellow River Estuary than those in the mariculture area. Vertical distributions in the sediment cores demonstrated a recent increase of OPE emissions, especially for tri-n-butyl phosphate (TnBP), tris (2-chloroethyl) phosphate (TCEP), and tris (2-chloroisopropyl) phosphate (TCPP). Generally, TCEP and TCPP were the dominant congeners in the sediment cores, while the profiles of TnBP were increase in the surface 0-20cm layers of the CA core. OPEs in the CA core may be remarkably influenced by the discharge of Yellow River, whereas OPEs in the CB core may originate from the transport through seawater. The remarkable increase of OPE flame retardants in the surface sediments raises the concern about their emissions and risks to the environment and indicates the need for further monitoring. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Microplastics in Sediment Cores from Asia and Africa as Indicators of Temporal Trends in Plastic Pollution.

    Science.gov (United States)

    Matsuguma, Yukari; Takada, Hideshige; Kumata, Hidetoshi; Kanke, Hirohide; Sakurai, Shigeaki; Suzuki, Tokuma; Itoh, Maki; Okazaki, Yohei; Boonyatumanond, Ruchaya; Zakaria, Mohamad Pauzi; Weerts, Steven; Newman, Brent

    2017-08-01

    Microplastics (plastics. Microplastics composed of variety of polymers, including polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethyleneterphthalates (PET), polyethylene-polypropylene copolymer (PEP), and polyacrylates (PAK), were identified in the sediment. We measured microplastics between 315 µm and 5 mm, most of which were in the range 315 µm-1 mm. The abundance of microplastics in surface sediment varied from 100 pieces/kg-dry sediment in a core collected in the Gulf of Thailand to 1900 pieces/kg-dry sediment in a core collected in a canal in Tokyo Bay. A far higher stock of PE and PP composed microplastics in sediment compared with surface water samples collected in a canal in Tokyo Bay suggests that sediment is an important sink for microplastics. In dated sediment cores from Japan, microplastic pollution started in 1950s, and their abundance increased markedly toward the surface layer (i.e., 2000s). In all sediment cores from Japan, Thailand, Malaysia, and South Africa, the abundance of microplastics increased toward the surface, suggesting the global occurrence of and an increase in microplastic pollution over time.

  11. 210Pb in a tropical coastal lagoon sediment core

    International Nuclear Information System (INIS)

    Paez-Osuna, F.; Mandelli, E.F.

    1985-01-01

    Excess 210 Pb in a core from a Mexican Coastal Lagoon, which has no connection with the sea shows a small but measurable decay over the length of the core; when different approaches were compared significant differences in the values for the sedimentation rate are obtained. The best coefficient correlation was calculated when corrected 210 Pb activity for the uneven distribution of organic matter and cumulative inorganic weight is considered. Time frames in the sedimentary column were in agreement between the 210 Pb calculated time and the appearance of shell fragments probably associated with the disturbances caused by the 1961 hurricane Tara. The surface accumulation rate is equivalent to a mean deposition of 262.5 g m -2 yr -1 of organic matter which is minor but comparable to some salt marshes of United States. (author)

  12. Historical records of organic pollutants in sediment cores.

    Science.gov (United States)

    Bigus, Paulina; Tobiszewski, Marek; Namieśnik, Jacek

    2014-01-15

    Analyses of sediment core samples are primary sources of historical pollution trends in aquatic systems. Determining organic compounds, such as POPs, in the dated sediments enables the estimation of their temporal concentration changes and the identification of the contaminant origin in local regions. Wars, large-scale fires, economical transitions, and bans on certain chemicals are reflected in the sediment organic compound concentrations. The high POP concentrations in surficial sediments suggest that these chemicals, even after being banned, remain in the environment. Furthermore, vertical profiles can help in understanding the sedimentation process and in estimating effective countermeasures against pollution. Moreover, studies published during the period 1991-2013 on PAHs, PCBs, OCPs, dioxins and dioxin-like compound concentrations in sediment core samples are reviewed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Radiocarbon dating of sediment cores from Hachinohe, the Kamikita Plain

    International Nuclear Information System (INIS)

    Hitoki, Eri; Nakamura, Toshio; Matsumoto, Yui; Tsuji, Sei-ichiro; Fujine, Hisashi

    2013-01-01

    We investigated stratigraphy and chronology by analyses of Holocene sediments and radiocarbon dating of sediment cores from the Kamikita Plain. On the Kamikita Plain, which faces the Pacific coast of Northeast Japan, marine and fluvial terraces covered with tephras derived from Towada and Hakkoda volcanoes are well developed. We clarified that Towada Chuseri tephra and fluvial deposits consisted of volcanic sediments influenced an alluvial depositional system in the Kamikita Plain after a maximum of the Jomon Transgression. (author)

  14. Differential sedimentation versus coring artifacts: a comparison of two widely used piston-coring methods

    NARCIS (Netherlands)

    Lotter, A.F.; Merkt, J.; Sturm, M.

    1997-01-01

    In order to compare two widely used piston-coring techniques, parallel cores were taken with both a Kullenberg and a Livingstone corer in the deepest part of Soppensee (25 m), a small eutrophic Swiss lake containing varved sediments. The cores were taken within a horizontal distance of 3 m and

  15. Assessment of heavy metals pollution in sediments and surface ...

    African Journals Online (AJOL)

    Samples were analyzed for their concentrations of these metals, using the atomic absorption spectrophotometer (AAS). The results of heavy metals show that the average contents of Fe (5.3%), Cr (70 ppm), Cd (0.4ppm) and Co (40ppm) in surface sediments are only slightly higher than corresponding contents in body core ...

  16. 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)

  17. Fluvial landscapes evolution in the Gangkou River basin of southern Taiwan: Evidence from the sediment cores

    Science.gov (United States)

    Chen, Jia-Hong; Chyi, Shyh-Jeng; Yen, Jiun-Yee; Lin, Li-Hung; Yen, I.-Chin; Yu, Neng-Ti; Ho, Lih-Der; Jen, Chia-Hung

    2017-04-01

    The Gangkou River basin is the largest basin in the eastern Hengchun Peninsula of Taiwan. Its main river length is 31km and the basin area is 102sq. km. The width of the active channel is relatively narrow, but the valley from the middle to downstream is remarkably wide, indicating a feature of underfit stream. We drilled two sediment cores in the downstream area, including a 30m core (core-A) from a higher terrace, which is 14m above mean sea level, and a 20m core (core-B) from a lower terrace, which is 4m above mean sea level. Most of the sediments in the core-A are mud, which represents the flood plain facies, and 14C dates in the core-A range from 11ka to 7ka BP. Furthermore, the sediment layers reveal signals of marine events at the core depths of 5m to 11m by X-ray fluorescence. In the core-B, there is an erosional surface at the core depth of 5m. The age of the fluvial gravel layer above the erosional surface is about 0.4ka BP, and the mud layer top the surface is about 8.5ka BP. The preliminary results show that (1) as the tectonic uplift rate induced by the marine terraces around the basin is 1.0 to 2.5 mm/yr, and the accumulation rate of the mud layer in the basin is 6.7 to 8.7 mm/yr, the sediments infilling (more than 30-meters-thick) in the downstream area of the basin should be the results of the lower tectonic uplifting and the higher post-glacial sea level rise and; (2) the marine sediment layer with 14C dates of 7.5ka to 8.5ka BP is very likely the remain of the maximum flooding surface (MFS) in the early Holocene. These results indicate that the fluvial landscapes evolution of the basin was controlled by the sea-level; (3) the erosional surface in the core-B indicates the Gangkou River continuously erode the infilling sediments from 7ka to 0.4ka BP. Previous studies show that the sea-level around Taiwan gradually declined from its high stand since 6ka, we proposed that the continuous erosion was probably the results of tectonic uplifting and

  18. Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated, Threaded-rod.

    Science.gov (United States)

    Schwing, Patrick T; Romero, Isabel C; Larson, Rebekka A; O'Malley, Bryan J; Fridrik, Erika E; Goddard, Ethan A; Brooks, Gregg R; Hastings, David W; Rosenheim, Brad E; Hollander, David J; Grant, Guy; Mulhollan, Jim

    2016-08-17

    Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, this resolution provides records at the annual to decadal scale, at best. An extrusion method, using a calibrated, threaded-rod is presented here, which allows for millimeter-scale subsampling of aquatic sediment cores of varying diameters. Millimeter scale subsampling allows for sub-annual to monthly analysis of the sedimentary record, an order of magnitude higher than typical sampling schemes. The extruder consists of a 2 m aluminum frame and base, two core tube clamps, a threaded-rod, and a 1 m piston. The sediment core is placed above the piston and clamped to the frame. An acrylic sampling collar is affixed to the upper 5 cm of the core tube and provides a platform from which to extract sub-samples. The piston is rotated around the threaded-rod at calibrated intervals and gently pushes the sediment out the top of the core tube. The sediment is then isolated into the sampling collar and placed into an appropriate sampling vessel (e.g., jar or bag). This method also preserves the unconsolidated samples (i.e., high pore water content) at the surface, providing a consistent sampling volume. This mm scale extrusion method was applied to cores collected in the northern Gulf of Mexico following the Deepwater Horizon submarine oil release. Evidence suggests that it is necessary to sample at the mm scale to fully characterize events that occur on the monthly time-scale for continental slope sediments.

  19. Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated, Threaded-rod

    Science.gov (United States)

    Schwing, Patrick T.; Romero, Isabel C.; Larson, Rebekka A.; O'Malley, Bryan J.; Fridrik, Erika E.; Goddard, Ethan A.; Brooks, Gregg R.; Hastings, David W.; Rosenheim, Brad E.; Hollander, David J.; Grant, Guy; Mulhollan, Jim

    2016-01-01

    Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, this resolution provides records at the annual to decadal scale, at best. An extrusion method, using a calibrated, threaded-rod is presented here, which allows for millimeter-scale subsampling of aquatic sediment cores of varying diameters. Millimeter scale subsampling allows for sub-annual to monthly analysis of the sedimentary record, an order of magnitude higher than typical sampling schemes. The extruder consists of a 2 m aluminum frame and base, two core tube clamps, a threaded-rod, and a 1 m piston. The sediment core is placed above the piston and clamped to the frame. An acrylic sampling collar is affixed to the upper 5 cm of the core tube and provides a platform from which to extract sub-samples. The piston is rotated around the threaded-rod at calibrated intervals and gently pushes the sediment out the top of the core tube. The sediment is then isolated into the sampling collar and placed into an appropriate sampling vessel (e.g., jar or bag). This method also preserves the unconsolidated samples (i.e., high pore water content) at the surface, providing a consistent sampling volume. This mm scale extrusion method was applied to cores collected in the northern Gulf of Mexico following the Deepwater Horizon submarine oil release. Evidence suggests that it is necessary to sample at the mm scale to fully characterize events that occur on the monthly time-scale for continental slope sediments. PMID:27585268

  20. Characterization of polychlorinated biphenyls in surface sediments ...

    African Journals Online (AJOL)

    The distribution and concentrations of 6 indicator polychlorinated biphenyl (PCB) congeners, nos. 28, 52, 101, 138, 153 and 180, were determined in surface sediments from the North End Lake in Port Elizabeth, South Africa. Forty-two surficial sediment samples were collected from different locations covering the region that ...

  1. PCBs and OCPs in sediment cores from the Lower St. Lawrence Estuary, Canada: evidence of fluvial inputs and time lag in delivery to coring sites.

    Science.gov (United States)

    Lebeuf, Michel; Nunes, Teresa

    2005-03-15

    Three sediment cores were collected along the longitudinal axis of the Laurentian Trough in the Lower St. Lawrence Estuary (LSLE) and an additional one at the junction of the Estuary and the Gulf of St. Lawrence. After core-slicing, each sediment layer was analyzed for polychlorinated biphenyls (PCBs) and some organochlorine pesticides (OCPs) including p,p'-dichlorodiphenyltrichloroethane (DDT) and its metabolites, hexachlorobenzene (HCB) and Mirex. 210Pb activity was also measured in these sediments, which allowed us to confirm that these cores were too much affected by the overall impact of surface mixing to be dated. Nevertheless, POP sedimentary profiles in cores from the LSLE upstream stations showed well-defined subsurface peak concentrations. Apparently, the peak inputs of POPs to these sediment cores had occurred after the years of maximum sales and production of these chemicals in North America, suggesting a time lag in the delivery of POPs to the LSLE sediments. Concentrations of POPs in the LSLE surface sediments as well as POP inventories in sediment cores decreased in the seaward direction, confirming that the head of the LSLE acts as a sink for sediments and associated constituents. Surface concentrations of sigmaPCBs, sigmaDDTs, and HCB in the most upstream core were on average similar to those reported in two fluvial lakes of the St. Lawrence River but were between 12 and 39 times lower than those from Lake Ontario. For Mirex, the surface concentration in that core was 5 and 130 times lower than the average values found in the fluvial lakes and Lake Ontario, respectively. Differences between Lake Ontario sediment cores and the most upstream core from the LSLE were much smaller on the basis of POP inventories than surface concentrations of POPs, but were still important. The total burdens of POPs in LSLE sediments below the 200 m isobath were 8704 kg for sigmaPCBs, 1825 kg for sigmaDDTs, 319 kg for HCB, and 27.5 kg for Mirex. These values represent

  2. Environmental mineralogy of unconsolidated surface sediments ...

    African Journals Online (AJOL)

    Environmental mineralogy of unconsolidated surface sediments associated with the 2001 landslides on volcanic cones, Mabeta New Layout, Limbe, Cameroon. George Ekosse, Veronica Ngole, Yinda Sendze, Samuel Ayonghe ...

  3. Core sediment biogeochemistry in specific zones of Cochin ...

    Indian Academy of Sciences (India)

    Field J A and Lettinga G 1987 The methanogenic toxic- ity and anaerobic degradability of a hydrolysable tannin;. Water Res. 21 367–374. Finar I L 1976 Organic Chemistry, Vol. 1, Longman,. Singapore. Geetha R, Chandramohanakumar N and Mathews L 2008. Geochemical reactivity of surficial and core sediment of a.

  4. Core sediment biogeochemistry in specific zones of Cochin ...

    Indian Academy of Sciences (India)

    Geochemical composition is a set of data for predicting the climatic condition existing in an ecosystem. Both the surficial and core sediment geochemistry are helpful in monitoring, assessing and evaluating the marine environment. The aim of the research work is to assess the relationship between the biogeochemical ...

  5. Holocene sediment accumulation in the Aespoe area. A study of a sediment core

    Energy Technology Data Exchange (ETDEWEB)

    Risberg, Jan [Stockholm Univ. (Sweden). Dept. of Quaternary Research

    2002-12-01

    A sediment core was collected in 1993 in the archipelago above the tunnel between the Aespoe Island and Simpevarp nuclear power plant. The sediment sequence consists of four types of accumulations: brownish clay, bluish clay, sand mixed with gravel and gyttja. The sequence was studied according to its content of siliceous microfossils (mainly diatoms), mineral magnetic characteristics, clay mineralogy and it was dated by the AMS technique on bulk sediment samples. According to the diatom content, both types of clay were probably deposited during the brackish water Yoldia Sea stage. The clay is relatively uniform, except an abrupt increase in the mineral magnetic parameters HIRM and S-ratio at around 810 cm depth, which probably is the result from a change in the material source. The clay mineralogy, with enhanced chlorite values, indicates a relatively uniform material. A major change occurs at the transition from the bluish to brownish clay, where all magnetic concentrations drop dramatically as the result from a major shift in material source and/or sedimentation environment. The thin layer of sand and gravel is indicative of a major hiatus in the stratigraphy. Mineral magnetic concentrations increase slightly as the result from mixing with single domain ground surface generated particles. Based on a Yoldia Sea age for the underlying clay and deposition in the Litorina Sea 3000 years BP for the superimposed gyttja, it is suggested that the length of the hiatus is about 7000 years. It is not until the studied site became protected enough by rising land areas, that organic rich gyttja started to accumulate.It is likely that this scenario was established when sea level was situated at around 10 m above present day. Since then it seems, as determined from the mineral magnetic graphs, that the sedimentary conditions have been relatively uniform. More pronounced fluctuations in mineral magnetic concentrations (especially ARM/SIRM ratios)in the upper 2 m of the core

  6. Holocene sediment accumulation in the Aespoe area. A study of a sediment core

    International Nuclear Information System (INIS)

    Risberg, Jan

    2002-12-01

    A sediment core was collected in 1993 in the archipelago above the tunnel between the Aespoe Island and Simpevarp nuclear power plant. The sediment sequence consists of four types of accumulations: brownish clay, bluish clay, sand mixed with gravel and gyttja. The sequence was studied according to its content of siliceous microfossils (mainly diatoms), mineral magnetic characteristics, clay mineralogy and it was dated by the AMS technique on bulk sediment samples. According to the diatom content, both types of clay were probably deposited during the brackish water Yoldia Sea stage. The clay is relatively uniform, except an abrupt increase in the mineral magnetic parameters HIRM and S-ratio at around 810 cm depth, which probably is the result from a change in the material source. The clay mineralogy, with enhanced chlorite values, indicates a relatively uniform material. A major change occurs at the transition from the bluish to brownish clay, where all magnetic concentrations drop dramatically as the result from a major shift in material source and/or sedimentation environment. The thin layer of sand and gravel is indicative of a major hiatus in the stratigraphy. Mineral magnetic concentrations increase slightly as the result from mixing with single domain ground surface generated particles. Based on a Yoldia Sea age for the underlying clay and deposition in the Litorina Sea 3000 years BP for the superimposed gyttja, it is suggested that the length of the hiatus is about 7000 years. It is not until the studied site became protected enough by rising land areas, that organic rich gyttja started to accumulate.It is likely that this scenario was established when sea level was situated at around 10 m above present day. Since then it seems, as determined from the mineral magnetic graphs, that the sedimentary conditions have been relatively uniform. More pronounced fluctuations in mineral magnetic concentrations (especially ARM/SIRM ratios)in the upper 2 m of the core

  7. Nondestructive X-Ray Computed Tomography Analysis of Sediment Cores: A Case Study from the Arctic Ocean

    Science.gov (United States)

    Oti, E.; Polyak, L. V.; Cook, A.; Dipre, G.

    2014-12-01

    Investigation of marine sediment records can help elucidate recent changes in the Arctic Ocean circulation and sea ice conditions. We examine sediment cores from the western Arctic Ocean, representing Late to Early Quaternary age (potentially up to 1 Ma). Previous studies of Arctic sediment cores indicate that interglacial/interstadial periods with relatively high sea levels and reduced ice cover are characterized by vigorous bioturbation, while glacial intervals have little to no bioturbation. Traditional methods for studying bioturbation require physical dissection of the cores, effectively destroying them. To treat this limitation, we evaluate archival sections of the cores using an X-ray Computed Tomography (XCT) scanner, which noninvasively images the sediment cores in three dimensions. The scanner produces density sensitive images suitable for quantitative analysis and for identification of bioturbation based on size, shape, and orientation. We use image processing software to isolate burrows from surrounding sediment, reconstruct them three-dimensionally, and then calculate their surface areas, volumes, and densities. Preliminary analysis of a core extending to the early Quaternary shows that bioturbation ranges from 0 to approximately 20% of the core's volume. In future research, we will quantitatively define the relationship between bioturbation activity and glacial regimes. XCT examination of bioturbation and other sedimentary features has the potential to shed light on paleoceanographic conditions such as sedimentation patterns and food flux. XCT is an alternative, underexplored investigation method that bears implications not only for illustrating paleoclimate variations but also for preserving cores for future, more advanced technologies.

  8. Geotechnical properties of surface sediments in the INDEX area

    Digital Repository Service at National Institute of Oceanography (India)

    Khadge, N.H.

    As a part of the environmental impact assessment studies, geotechnical properties of sediments were determined in the Central Indian Basin. The undrained shear strength and index properties of the siliceous sediments were determined on 20 box cores...

  9. Surface sedimentation at permeable pavement systems

    DEFF Research Database (Denmark)

    Støvring, Jan; Dam, Torben; Jensen, Marina Bergen

    2018-01-01

    of restorative cleaning (RC), nine recently built PP systems were tested for their infiltration capacity with and without restorative cleaning (RC) over an interval of 12–14.5 months. The results were related to each site’s unique history of sedimentation. RC significantly improved permeability, but when...... revisited after approximately one year, the permeability of cleaned surfaces was not significantly better for the RC spots than from their uncleaned neighbouring areas. Relating permeability to the contextual issues revealed that PP perimeter, adjacent bare soil and mismanagement strongly affected...... the sedimentation process. At two of the sites, sedimentation processes were so advanced that surface permeability was below the level of service (five-year design storm)....

  10. Methanotrophy in surface sediments of streams

    Science.gov (United States)

    Bagnoud, Alexandre; Pramateftaki, Paraskevi; Peter, Hannes; Battin, Tom

    2017-04-01

    Because streams are often found to be supersaturated in methane (CH4), they are considered as atmospheric sources of this greenhouse gas. However, little is known about the processes driving CH4 cycling in these environments, i.e. production, consumption and fluxes. CH4 is thought to be produced in deeper anoxic sediments, before it migrates up to reach the oxic stream water, where it can be oxidized by methanotrophs. In order to gain insights into this process, we investigated 14 different streams across Switzerland. We characterized the chemistry of surface and sediment waters by measuring dissolved chemical profiles. We also sampled surface sediments and determined methanotrophic rates with laboratory incubations and Michaelis-Menten modeling. Interestingly, rates were strongly correlated with the CH4 concentrations in stream waters, rather than in sediment waters. This indicates that methantrophic populations feed on CH4 from the surface streamwater, even though CH4 concentrations are higher in the sediment waters. Methanotrophy rates were also correlated with Crenothrix counts (based on 16S rRNA sequencing), a strict methanotroph, while this latter was correlated with pmoA counts (based on quantitative PCR), a gene involved in methanotrophy. These results show that Crenothrix genera are the most active methanotrophs in surface sediments of streams, and can represent more than 2% of microbial communities. Remarkably, the dominating Crenothrix species was detected in all 14 samples. This work allows the assessment of in situ methanotrophic rates, of the environmental parameters driving this process, and of the microbial populations carrying it out, and thus brings useful insights about carbon cycling in streams.

  11. Radiometric studies of sediments cores from Gulf of Mannar

    International Nuclear Information System (INIS)

    Ray, S.B.; Rajagopalan, G.; Somayajulu, B.L.K.

    1990-01-01

    Gulf of Mannar sediments contain 19.2 to 61.4% CaCO 3 , 1.9 to 5.2% organic matter, 7.2 to 18.8 ppm U and 3.0 to 16.7 ppm 232 Th, the last two on a calciu m carbonate free basis. 234 U/ 238 U activity ratio ranges from 1.09 to 1.19(mean 1.14±0.02), indicating the authigenic nature of U in the sediments. High U concentrations prevail throughout the cores (length∼ 150cm) analysed in this study. The 14 C- based deposition rates are 60.1 and 114cm (10 3 y) -1 for the shallow (water depth 3 y) -1 for the cores from the deeper (water depth > 2000m) regions. The authigenic deposition rates of U in the cores from shallow water regions are 130 and 314 μg cm -2 (10 3 y) -1 during the past < 3000y which compare well with such rates derived from anoxic coastal regions of the Atlantic and Pacific oceans. (author). 31 refs., 2 figs., 1 tab

  12. The GIK-Archive of sediment core radiographs with documentation

    Science.gov (United States)

    Grobe, Hannes; Winn, Kyaw; Werner, Friedrich; Driemel, Amelie; Schumacher, Stefanie; Sieger, Rainer

    2017-12-01

    The GIK-Archive of radiographs is a collection of X-ray negative and photographic images of sediment cores based on exposures taken since the early 1960s. During four decades of marine geological work at the University of Kiel, Germany, several thousand hours of sampling, careful preparation and X-raying were spent on producing a unique archive of sediment radiographs from several parts of the World Ocean. The archive consists of more than 18 500 exposures on chemical film that were digitized, geo-referenced, supplemented with metadata and archived in the data library PANGAEAstyle="position:relative; bottom:0.5em; " class="text">®. With this publication, the images have become available open-access for use by the scientific community at https://doi.org/10.1594/PANGAEA.854841.

  13. Urbanization increased metal levels in lake surface sediment and catchment topsoil of waterscape parks

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hong-Bo [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Yu, Shen, E-mail: syu@iue.ac.cn [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Li, Gui-Lin [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Liu, Yi; Yu, Guang-Bin [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Deng, Hong [Department of Environmental Sciences, Tiantong National Station of Forest Ecosystem, Key Laboratory of Urbanization and Ecological Restoration, East China Normal University, Shanghai 200062 (China); Wu, Sheng-Chun [State Key Laboratory in Marine Pollution, Biology and Chemistry Department, City University of Hong Kong, Hong Kong (China); Wong, Ming-Hung [Croucher Institute for Environmental Sciences, Hong Kong Baptist University, Hong Kong (China)

    2012-08-15

    Lake surface sediment is mainly derived from topsoil in its catchment. We hypothesized that distribution of anthropogenic metals would be homogenous in lake surface sediment and the lake's catchment topsoil. Anthropogenic metal distributions (cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn)) in fourteen waterscape parks were investigated in surface sediments and catchment topsoils and possible source homogeneity was tested using stable Pb isotopic ratio analysis. The parks were located along an urbanization gradient consisting of suburban (SU), developing urban (DIU), developed urban (DDU), and central urban core (CUC) areas in Shanghai, China. Results indicated that surface lake sediments and catchment topsoils in the CUC parks were highly contaminated by the investigated anthropogenic metals. Total metal contents in surface sediment and topsoil gradually increased along the urbanization gradient from the SU to CUC areas. Generally, the surface sediments had greater total metal contents than their catchment topsoils. These results suggest that urbanization drives the anthropogenic metal enrichment in both surface sediment and its catchment topsoil in the waterscape parks. Soil fine particles (< 63 {mu}m) and surface sediments had similar enrichment ratios of metals, suggesting that surface runoff might act as a carrier for metals transporting from catchment to lake. Stable Pb isotope ratio analysis revealed that the major anthropogenic Pb source in surface sediment was coal combustion as in the catchment topsoil. Urbanization also correlated with chemical fractionation of metals in both surface sediment and catchment topsoil. From the SU to the CUC parks, amounts of labile metal fractions increased while the residual fraction of those metals remained rather constant. In short, urbanization in Shanghai drives anthropogenic metal distribution in environmental matrices and the sources were homogenous. -- Highlights: Black-Right-Pointing-Pointer Obvious

  14. Urbanization increased metal levels in lake surface sediment and catchment topsoil of waterscape parks

    International Nuclear Information System (INIS)

    Li, Hong-Bo; Yu, Shen; Li, Gui-Lin; Liu, Yi; Yu, Guang-Bin; Deng, Hong; Wu, Sheng-Chun; Wong, Ming-Hung

    2012-01-01

    Lake surface sediment is mainly derived from topsoil in its catchment. We hypothesized that distribution of anthropogenic metals would be homogenous in lake surface sediment and the lake's catchment topsoil. Anthropogenic metal distributions (cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn)) in fourteen waterscape parks were investigated in surface sediments and catchment topsoils and possible source homogeneity was tested using stable Pb isotopic ratio analysis. The parks were located along an urbanization gradient consisting of suburban (SU), developing urban (DIU), developed urban (DDU), and central urban core (CUC) areas in Shanghai, China. Results indicated that surface lake sediments and catchment topsoils in the CUC parks were highly contaminated by the investigated anthropogenic metals. Total metal contents in surface sediment and topsoil gradually increased along the urbanization gradient from the SU to CUC areas. Generally, the surface sediments had greater total metal contents than their catchment topsoils. These results suggest that urbanization drives the anthropogenic metal enrichment in both surface sediment and its catchment topsoil in the waterscape parks. Soil fine particles (< 63 μm) and surface sediments had similar enrichment ratios of metals, suggesting that surface runoff might act as a carrier for metals transporting from catchment to lake. Stable Pb isotope ratio analysis revealed that the major anthropogenic Pb source in surface sediment was coal combustion as in the catchment topsoil. Urbanization also correlated with chemical fractionation of metals in both surface sediment and catchment topsoil. From the SU to the CUC parks, amounts of labile metal fractions increased while the residual fraction of those metals remained rather constant. In short, urbanization in Shanghai drives anthropogenic metal distribution in environmental matrices and the sources were homogenous. -- Highlights: ► Obvious urbanization effect on metal

  15. Distribution of iron, manganese, cobalt and nickel in sediment cores of the northeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, Ch.M.; Setty, M.G.A.P.

    of manganese and iron hydroxides, clay minerals, and organic matter present in the sediment. Since the cores represent differing environments, the inter-relationship and the factors governing adsorption and fixing them in the sediment vary considerably. Mn...

  16. Chlorinated hydrocarbon pesticides and polychlorinated biphenyls in sediment cores from San Francisco Bay

    Science.gov (United States)

    Venkatesan, M.I.; De Leon, R. P.; VanGeen, A.; Luoma, S.N.

    1999-01-01

    Sediment cores of known chronology from Richardson and San Pablo Bays in San Francisco Bay, CA, were analyzed for a suite of chlorinated hydrocarbon pesticides and polychlorinated biphenyls to reconstruct a historic record of inputs. Total DDTs (DDT = 2,4'- and 4,4'-dichlorodiphenyltrichloroethane and the metabolites, 2,4'- and 4,4'-DDE, -DDD) range in concentration from 4-21 ng/g and constitute a major fraction (> 84%) of the total pesticides in the top 70 cm of Richardson Bay sediment. A subsurface maximum corresponds to a peak deposition date of 1969-1974. The first measurable DDT levels are found in sediment deposited in the late 1930's. The higher DDT inventory in the San Pablo relative to the Richardson Bay core probably reflects the greater proximity of San Pablo Bay to agricultural activities in the watershed of the Sacramento and San Joaquin rivers. Total polychlorinated biphenyls (PCBs) occur at comparable levels in the two Bays (inventories in San Pablo Bay are about a factor of four higher in the last four decades than in Richardson Bay, suggesting a distribution of inputs not as strongly weighed towards the upper reaches of the estuary as DDTs. The shallower subsurface maximum in PCBs compared to DDT in the San Pablo Bay core is consistent with the imposition of drastic source control measures four these constituents in 1970 and 1977 respectively. The observed decline in DDT and PCB levels towards the surface of both cores is consistent with a dramatic drop in the input of these pollutants once the effect of sediment resuspension and mixing is taken into account.

  17. Geochemical assessment of metal pollution and ecotoxicology in sediment cores along Karachi Coast, Pakistan.

    Science.gov (United States)

    Mashiatullah, Azhar; Chaudhary, Muhammad Zaman; Ahmad, Nasir; Ahmad, Nisar; Javed, Tariq; Ghaffar, Abdul

    2015-05-01

    This paper is an attempt to compare the pollution status in two sediment cores, one from a polluted site (Ghizri Creek) and another from a relatively unpolluted site (Sandspit). Sediment cores (45 cm in length) from coastal locations were characterized in terms of grain size, sediment composition, pH, organic matter, calcium carbonate, and metal element contents. Metal elements, including Al, Ca, Cr, Co Cu, Fe, K, Mg, Mn, Ni, Pb, V, Ti, and Zn, were determined using PIXE. Grain size analysis and sediment composition demonstrated a sandy nature of both cores. Acidic trend in sediment core I was predominant from bottom to top, whereas neutral pH was observed throughout core II. TOC values varied in the range of 1.23-2.68 and 1.14-2.60% in core I and core II, respectively; however, there was an increasing trend in TOC level from bottom to top. The values of enrichment factor for Zn, Cu, Co, Ni, Pb, and Cr were slightly higher in core I than core II. The average geo-accumulation index values for core I and core II showed that sediments were moderately Co- and Pb-polluted but not polluted with Mg, Al, Ca, K, Cr, Cu, Fe, Mn, Ni, Ti, V, and Zn. The degree of contamination was however considerably higher in core I relative to core II. The pollution load index values, although showing an increasing trend from bottom to top in both cores, overall rendered the marine sediment pollution free. The metal toxicology results demonstrated that heavy metal pollution, except Cr, may pose low to moderate risk to marine biota. The sum of toxic unit values however indicated that sediment core I was relatively more polluted than that of core II.

  18. XRF core scanners as a quick and good screening tool for detecting pollution in sediment cores

    Directory of Open Access Journals (Sweden)

    Belén Rubio

    2014-05-01

    Full Text Available The capabilities of X-Ray Fluorescence (XRF core scanners, to acquire high-resolution geochemical data sets in relatively short time, have made them an increasingly popular geochemical screening tool to study sediment cores for palaeoclimatologic and palaeoceanographic purposes (Peck et al., 2007; Rebolledo et al., 2008. These scanners are able to obtain optical images, X-ray radiographs, and continuous geochemical data with a maximum resolution of 200 µm directly from sediment cores (Croudace et al., 2006. Geochemical results are obtained as peak areas of counts per second that are proportional to element concentrations in the sediment, and thus the assumed semi-quantitative nature of these analyses have hampered the use of this type of instruments to monitor and detect pollution at large; where the availability of a fast screening tool that could substantially cut analytical and time costs will certainly be an advantage. This study explores the sensitivity of a ITRAX core scanner (Cox Analytical Systems on sedimentary records from estuarine-like environments in NW (Rías Baixas Galicia and SW Spain (Ría de Huelva. The Galician Rías Baixas sediments are characterized by high contents of organic matter, but in general terms, are not heavily polluted. We have selected one core in the Marín harbour (Ría de Pontevedra and another in the intertidal area of San Simón Bay (inner Ría de Vigo, close to a ceramic factory, which is relatively highly polluted by lead. By the contrary, the Ría de Huelva is one of the most polluted areas in western Europe because of the high acid mining activity together with the chemical industries located in its margins. We have selected a core in the Padre Santo Channel in the confluence of the Odiel and Tinto rivers. ITRAX sensitivity was obtained by establishing equivalences between peak areas and concentrations obtained by traditional analytical techniques such as ICP-MS, ICP-OES and/or conventional XRF of

  19. A database of paleoceanographic sediment cores from the North Pacific, 1951-2016

    Science.gov (United States)

    Borreggine, Marisa; Myhre, Sarah E.; Mislan, K. Allison S.; Deutsch, Curtis; Davis, Catherine V.

    2017-09-01

    We assessed sediment coring, data acquisition, and publications from the North Pacific (north of 30° N) from 1951 to 2016. There are 2134 sediment cores collected by American, French, Japanese, Russian, and international research vessels across the North Pacific (including the Pacific subarctic gyre, Alaskan gyre, Japan margin, and California margin; 1391 cores), the Sea of Okhotsk (271 cores), the Bering Sea (123 cores), and the Sea of Japan (349 cores) reported here. All existing metadata associated with these sediment cores are documented here, including coring date, location, core number, cruise number, water depth, vessel metadata, and coring technology. North Pacific sediment core age models are built with isotope stratigraphy, radiocarbon dating, magnetostratigraphy, biostratigraphy, tephrochronology, % opal, color, and lithological proxies. Here, we evaluate the iterative generation of each published age model and provide comprehensive documentation of the dating techniques used, along with sedimentation rates and age ranges. We categorized cores according to the availability of a variety of proxy evidence, including biological (e.g., benthic and planktonic foraminifera assemblages), geochemical (e.g., major trace element concentrations), isotopic (e.g., bulk sediment nitrogen, oxygen, and carbon isotopes), and stratigraphic (e.g., preserved laminations) proxies. This database is a unique resource to the paleoceanographic and paleoclimate communities and provides cohesive accessibility to sedimentary sequences, age model development, and proxies. The data set is publicly available through PANGAEA at https://doi.org/10.1594/PANGAEA.875998.

  20. A database of paleoceanographic sediment cores from the North Pacific, 1951–2016

    Directory of Open Access Journals (Sweden)

    M. Borreggine

    2017-09-01

    Full Text Available We assessed sediment coring, data acquisition, and publications from the North Pacific (north of 30° N from 1951 to 2016. There are 2134 sediment cores collected by American, French, Japanese, Russian, and international research vessels across the North Pacific (including the Pacific subarctic gyre, Alaskan gyre, Japan margin, and California margin; 1391 cores, the Sea of Okhotsk (271 cores, the Bering Sea (123 cores, and the Sea of Japan (349 cores reported here. All existing metadata associated with these sediment cores are documented here, including coring date, location, core number, cruise number, water depth, vessel metadata, and coring technology. North Pacific sediment core age models are built with isotope stratigraphy, radiocarbon dating, magnetostratigraphy, biostratigraphy, tephrochronology, % opal, color, and lithological proxies. Here, we evaluate the iterative generation of each published age model and provide comprehensive documentation of the dating techniques used, along with sedimentation rates and age ranges. We categorized cores according to the availability of a variety of proxy evidence, including biological (e.g., benthic and planktonic foraminifera assemblages, geochemical (e.g., major trace element concentrations, isotopic (e.g., bulk sediment nitrogen, oxygen, and carbon isotopes, and stratigraphic (e.g., preserved laminations proxies. This database is a unique resource to the paleoceanographic and paleoclimate communities and provides cohesive accessibility to sedimentary sequences, age model development, and proxies. The data set is publicly available through PANGAEA at https://doi.org/10.1594/PANGAEA.875998.

  1. Dynamics of sediments along with their core properties in the Monastir-Bekalta coastline (Tunisia, Central Mediterranean)

    Science.gov (United States)

    Khiari, Nouha; Atoui, Abdelfattah; Khalil, Nadia; Charef, Abdelkrim; Aleya, Lotfi

    2017-10-01

    The authors report on two campaigns of high-resolution samplings along the shores of Monastir Bay in Tunisia: the first being a study of sediment dynamics, grain size and mineral composition in surface sediment, and the second, eight months later, using four sediment cores to study grain-size distribution in bottom sediments. Particle size analysis of superficial sediment shows that the sand in shallow depths is characterized by S-shaped curves, indicating a certain degree of agitation, possible transport by rip currents near the bottom and hyperbolic curves illustrating heterogeneity of sand stock. The sediments settle in a relatively calm environment. Along the bay shore (from 0 to 2 m depth), the bottom is covered by medium sand. Sediment transport is noted along the coast; from north to south and from south to north, caused by longshore drift and a rip current in the middle of the bay. These two currents are generated by wind and swell, especially by north to northeast waves which transport the finest sediment. Particle size analysis of bottom sediment indicates a mean grain size ranging from coarse to very fine sands while vertical distribution of grain size tends to decrease from surface to depth. The increase in particle size of sediment cores may be due to the coexistence of terrigenous inputs along with the sedimentary transit parallel to the coast due to the effect of longshore drift. Mineralogical analysis shows that Monastir's coastal sands and bottom sediment are composed of quartz, calcite, magnesium calcite, aragonite and hematite. The existence of a low energy zone with potential to accumulate pollutants indicates that managerial action is necessary to help preserve Monastir Bay.

  2. Concentration of Antifouling Biocides and Metals in Sediment Core Samples in the Northern Part of Hiroshima Bay

    Directory of Open Access Journals (Sweden)

    Noritaka Tsunemasa

    2014-06-01

    Full Text Available Accumulation of Ot alternative antifoulants in sediment is the focus of this research. Much research had been done on surface sediment, but in this report, the accumulation in the sediment core was studied. The Ot alternative antifoulants, Diuron, Sea-Nine211, and Irgarol 1051, and the latter’s degradation product, M1, were investigated in five samples from the northern part of Hiroshima Bay. Ot compounds (tributyltin (TBT and triphenyltin (TPT were also investigated for comparison. In addition, metal (Pb, Cu, Zn, Fe and Mn levels and chronology were measured to better understand what happens after accumulation on the sea floor. It was discovered that Ot alternative antifoulant accumulation characteristics in sediment were like Ot compounds, with the concentration in the sediment core being much higher than surface sediment. The concentration in sediment seems to have been affected by the regulation of Ot compounds in 1990, due to the concentration of Ot alternative antifoulants and Ot compounds at the survey point in front of the dock, showing an increase from almost the same layer after the regulation.

  3. Rise and fall of mercury (Hg) pollution in sediment cores of the Thames Estuary, London, UK

    OpenAIRE

    Vane, Christopher H.; Beriro, Darren J.; Turner, Grenville H.

    2015-01-01

    Fifty six sediment cores were collected along a 100 km longitudinal transect of the Thames estuary. Total Hg ranged from 0.01 to 12.07 mg/kg, with a mean of 2.10 mg/kg (n=351). Concentrations of the toxic metal decreased downstream from London to the outer estuary and were positively correlated to total organic carbon (TOC) content. Many Hg profiles showed a clear rise, peak and fall, reflecting changing anthropogenic input through time. Surface concentrations averaged 1.27 mg/kg, confirming ...

  4. Colloid mobilization in an undisturbed sediment core under semiarid recharge rates

    Science.gov (United States)

    Liu, Ziru; Flury, Markus; Harsh, James B.; Mathison, Jon B.; Vogs, Carolina

    2013-08-01

    The semiarid US Department of Energy Hanford site has a deep vadose zone with low recharge rates. Contaminants originating from nuclear waste processing are expected to move slowly through the vadose zone. The movement of certain contaminants can be facilitated by colloids. We hypothesized that the low recharge rates and low water contents in semiarid regions, however, tend to inhibit movement of colloidal particles, thereby reducing the risk for colloid-facilitated contaminant transport. The goal of this study was to investigate whether in situ natural colloids can be mobilized and transported in undisturbed, deep vadose zone sediments at the Hanford site under typical, semiarid recharge rates. We sampled an undisturbed sediment core (i.d. 50 cm, 59.5 cm height) from a depth of 17 m below ground at the Hanford 200 Area. The core was set up as a laboratory lysimeter and exposed to an infiltration rate of 18 mm/yr by applying simulated pore water onto the surface. Particle concentrations were quantified in the column outflow, and selected samples were examined microscopically and for elemental composition (transmission electron microscopy and energy dispersive X-ray). Measured water contents and potentials were used to calibrate a numerical model (HYDRUS-1D), which was then applied to simulate colloid mobilization from the sediment core. During 5.3 years of monitoring, natural colloids like silicates, aluminosilicates, and Fe-oxides were observed in the core outflow, indicating the continuous mobilization of in situ colloids. The total amount of particles mobilized during 5.3 years corresponded to 1.1% of the total dispersible colloids inside the core. Comparison of the amounts of colloids released with weathering rates suggests that mineral weathering can be a major source of the mobilized colloids. The fitted colloid release rate coefficient was 6 to 7 orders of magnitude smaller than coefficients reported from previous studies, where disturbed Hanford sediments

  5. Late Holocene climate change recorded in proxy records from a Bransfield Basin sediment core, Antarctic Peninsula

    Directory of Open Access Journals (Sweden)

    Alex Barnard

    2014-06-01

    Full Text Available The glacimarine environment of the Antarctic Peninsula region is one of the fastest warming places on Earth today, but details of changes in the recent past remain unknown. Large distances and widespread variability separate late Holocene palaeoclimate reconstructions in this region. This study focuses on a marine sediment core collected from ca. 2000 m below sea level in the Central Bransfield Strait that serves as a key for understanding changes in this region. The core yielded a high sedimentation rate and therefore provides an exceptional high-resolution sedimentary record composed of hemipelagic sediment, with some turbidites. An age model has been created using radiocarbon dates that span the Late Holocene: 3560 cal yr BP to present. This chronostratigraphic framework was used to establish five units, which are grouped into two super-units: a lower super-unit (3560–1600 cal yr BP and an upper super-unit (1600 cal yr BP–present, based on facies descriptions, laser particle size analysis, x-ray analysis, multi-sensor core logger data, weight percentages and isotopic values of total organic carbon and nitrogen. We interpret the signal contained within the upper super-unit as an increase in surface water irradiance and/or shortening of the sea-ice season and the five units are broadly synchronous with climatic intervals across the Antarctic Peninsula region. While the general trends of regional climatic periods are represented in the Bransfield Basin core we have examined, each additional record that is obtained adds variability to the known history of the Antarctic Peninsula, rather than clarifying specific trends.

  6. Don Quixote Pond Sediments: Surface and Subsurface Chemistry and Mineralogy

    Science.gov (United States)

    Englert, P. A. J.; Bishop, J. L.; Patel, S.; Gibson, E. K.; Koeberl, C.

    2014-12-01

    Don Quixote Pond, like Don Juan Pond in the South Fork of Wright Valley, Antarctica, is a model for calcium and chlorine weathering and distribution on Mars. It is located in the western part of the North Fork about 100 m above Mean Seawater Level; its brine is seasonally frozen [1]. Field observations show zones of discoloration which grow lighter with distance from the pond edges. Four sediment cores, a set of radial surface samples, special surface samples, and samples of local rocks were obtained [2]. We report on chemical and mineral analyses of traverse samples and on two cores. Core DQ20 is a northeastern shoreline core. Its soluble salt concentration exceeds 200 micromoles/g in the top 5 cm, and then falls to less than 70 micromoles/g at the permafrost depth of 15 cm. These concentrations are low when compared to similarly positioned locations at Don Juan Pond and to cores from Prospect Mesa close to Lake Vanda, Wright Valley. Halite, soda niter, tachyhydrite and/bischovite are suggested from the ionic molar relationships Measured halite concentrations of surface samples, collected along a traverse of 35 m from the pond outwards, range from over 5% to trace amounts, decreasing with distance. Gypsum is also present in almost all of these samples ranging from 0.2% to 2.6%, but does not exhibit a trend. However, in core DQ35, located at a distance of 15 m along the traverse, gypsum decreases from 2.5% to 0.6% from the surface to the permafrost depth of 12 cm. While DQ35 and radial samples show high quartz and albite abundance, samples that contained visible encrustations and evaporites are low in these minerals and rich in highly diverse alteration products. Don Juan Basin ponds may have formed by a complex surface water mobilization of weathering products [3] and local groundwater action [4,5]. In contrast, Don Quixote pond mineralogy and chemistry may be consistent with a less complex shallow and deep groundwater system origin [1]. [1] Harris H

  7. Determination of heavy metals and other elements by Neutron Activation Analysis in sediment cores of laguna Mar Chiquita (Cordoba, Argentina)

    International Nuclear Information System (INIS)

    Larizzatti, Flavio Eduardo

    2001-01-01

    Laguna Mar Chiquita is one of the largest water bodies of South America. It is a big lake of saline waters, and its geographic localization is SOMS' S, 62 deg 30' W, about 150 km Northwest of Cordoba, Argentina. Due to its large variability of hydrological budget, surface and water levels produced periods of low stands (LLP) and high stands (HLP). This fluctuation of water level also produces substantial changes in the water salinity. The principal tributary of the Laguna Mar Chiquita is Dulce River and also receives water from two other rivers: Suquia and Xanaes. The Suquia River drains in a small satellite lake, the Laguna del Plata. The purpose of the present work was to investigate the sediment composition of the Laguna Mar Chiquita (2 sediment cores) and del Plata (one sediment core) by using Neutron Activation Analysis (NAA) technique. The three 60 cm long sediment cores, sliced each 2 cm, were analyzed and 26 elements were determined (As, Ba, Br, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Lu, Na, Nd, Rb, Sb, Sc, Se, Sm, Ta, Tb, Th, U, Yb, Zn e Zr). Other complementary techniques were utilized: macro elements (Al, Ca, Fe, K, Mg, Mn, Na, P, Si, Ti) were determined by X-ray fluorescence, and the mineralogical composition of the sediments was determined by X-ray diffraction. The results obtained did not show any indication of anthropic contribution in the sediment composition, and concentration of the majority of the elements analyzed is uniform along the entire profile of the analyzed core. Statistical analysis of elemental concentrations (Cluster Analysis) reflects that in Laguna del Plata the fine fractions of the sediments is dominated by detrital minerals, while in the Laguna Mar Chiquita, the neo formed minerals are the principal components. In both lakes, it was possible to identify compositional variations in the sediment segments, which may correspond to temporal fluctuations in the sedimentation conditions. The statistical analysis associated to sedimentation

  8. Geochemistry of phosphorus in sediment cores from Sishili Bay, China.

    Science.gov (United States)

    Zhang, Yong; Gao, Xuelu; Wang, Changyou; Chen, Chen-Tung Arthur; Zhou, Fengxia; Yang, Yuwei

    2016-12-15

    This paper presents the distribution of total phosphorus (P), inorganic P (IP) and organic P in sediment cores from Sishili Bay, China. Their concentrations (μmolg -1 ) ranged from 15.04 to 21.59, 12.43 to 18.27 and 0.15 to 5.11, respectively, showing 87.6-96.9% of TP is IP. The distribution of the fractionation of IP , obtained by a sequential extraction technique, was 1.9-3.2% for soluble and loosely bound P (Ex-P), 8.5-13.1% for Al-bound from (Al-P), 7.4-9.5% for Fe-bound P (Fe-P), 5.0-12.4% for reductant-soluble P (Oc-P), 9.7-15.6% for CaCO 3 -bound P (ACa-P) and 45.9-54.6% for detritus P (Det-P). The P distribution and concentration was consistent with other Chinese coastal seas. No significant difference was found for the sedimentary P forms between scallop cultivation area and background area, indicating that shellfish aquaculture did not have significant effect on the depositional environment in the studied area, at least in case of P. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. [Distributions of phosphorus fractions in suspended sediments and surface sediments of Tiaoxi mainstreams and cause analysis].

    Science.gov (United States)

    Chen, Hai-Long; Yuan, Xu-Yin; Wang, Huan; Li, Zheng-Yang; Xu, Hai-Yan

    2015-02-01

    Phosphorus is a primary nutrient showing the water quality status of river and inducing eutrophication, and a different phosphorus fraction can make diverse contributions to water quality. Four phosphorus forms of suspended sediments and surface sediments in Tiaoxi mainstreams were measured using a sequential extraction procedure, and the distributions of their forms were discussed. The results showed that the tropic status of Xitiaoxi River was inferior to that of Dongtiaoxi River as a whole, and the water quality in the middle reach of Dongtiaoxi River was better than that in the upper and lower reaches. The contents of nutrient elements in suspended sediments were significantly higher than those in surface sediment, which indicated an enrichment of nutrient in fine sediment. The percentages of the loosely absorbed phosphorus ( NH4Cl-P), the reductant phosphorus (BD-P) and the metal oxide bound phosphorus (NaOH-P) in the suspended sediment were higher than those in surface sediment, while the percentage of the calcium bound phosphorus (HCl-P) showed a reverse trend. Correlation analyses between phosphorus forms and chemical compositions of suspended sediments and surface sediments were performed. The results showed the phosphorus forms in suspended sediments and surface sediments of Xitiaoxi River had weak relationships with mineral components, while those in the Dongtiaoxi River had strong relationships with mineral, especially OM and clay mineral. The cause was associated with the geological setting and material sources in Tiaoxi watershed.

  10. Heavy metal concentrations in sediment cores from the northern Baltic Sea: Declines over the last two decades

    International Nuclear Information System (INIS)

    Vallius, Henry

    2014-01-01

    Highlights: • Trends in Hg, Cd, Cu, Pb, Zn, and As concentrations were investigated in Baltic Sea sediment cores. • Heavy metal deposition in surface sediment of the northern and eastern Baltic Sea is declining. • Arsenic concentrations in sediments from the Bothnian Bay remain at high levels. • Cd and Hg concentrations still occur at unacceptably high levels. - Abstract: The Baltic Sea has received considerable loads of pollutants due to industrialization in Eastern Europe. Concern for the Baltic’s ecological health eventually led to legislation and voluntary measures to limit pollution during the last decades of the 20th century. Heavy metal concentrations in open sea surface sediments reflected these steps to limit contaminant loads almost immediately, suggesting the possibility that the trend would continue in the ensuing years. Recent seafloor samples reveal that the declines have persisted over the past two decades. Currently, almost all heavy metal species have declined in surface sediments to levels approaching the safe limits for humans and the environment. Cadmium and mercury however remain at relatively high concentrations in many areas. Arsenic concentrations, which occur at safe levels within the Gulf of Finland persist at unacceptably high levels in surface sediments of the Bothnian Bay, and thus pose a potential threat to marine life in the area

  11. Sediment Transport Model for a Surface Irrigation System

    OpenAIRE

    Mailapalli, Damodhara R.; Raghuwanshi, Narendra S.; Singh, Rajendra

    2013-01-01

    Controlling irrigation-induced soil erosion is one of the important issues of irrigation management and surface water impairment. Irrigation models are useful in managing the irrigation and the associated ill effects on agricultural environment. In this paper, a physically based surface irrigation model was developed to predict sediment transport in irrigated furrows by integrating an irrigation hydraulic model with a quasi-steady state sediment transport model to predict sediment load in fur...

  12. Normalization to lithium for the assessment of metal contamination in coastal sediment cores from the Aegean Sea, Greece.

    Science.gov (United States)

    Aloupi, M; Angelidis, M O

    2001-07-01

    Sediment cores from the harbour and the coastal zone of Mytilene, island of Lesvos, Greece, were used to study the metal contamination caused by the discharge of untreated urban effluents into the sea. In the harbour. the upper layers were highly enriched in Cd, Cu, Pb and Zn, while no metal enrichment was recorded in the cores from the wider coastal zone. The metal data were normalized to Li (conservative element) to compensate for the natural textural and mineralogical variability. It was found that only the upper 18 cm of the core collected from the harbour of Mytilene could be reported as metal contaminated. Also, through the normalization procedure, it was found that the surface layers of coastal sediments assumed 'clean' were enriched in Pb, probably as a result of atmospheric transportation of the metal from the nearby town.

  13. Diagenetic remobilization of rare earth elements in a sediment core from the central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Banakar, V.K.

    Rare earth elements (REE) distribution in a 36 cm long sediment box core from the Central Indian Basin is studied. REE concentration is generally higher in the upper oxic zone than in intermediate suboxic zone suggesting REE diffusion upwards...

  14. Archive of Geosample Information from the British Ocean Sediment Core Research Facility (BOSCORF)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The British Ocean Sediment Core Research Facility (BOSCORF), National Oceanography Centre, is a contributor to the Index to Marine and Lacustrine Geological Samples...

  15. Particle sizes of Pliocene and Pleistocene core sediments from IODP Expedition 323 in the Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data compilation includes the results of grain size analyses of core sediment collected by IODP during Expedition 323 in the Bering Sea. One dataset is included...

  16. Phosphate, carbonate and organic matter distribution in sediment cores off Bombay-Saurashtra coast, India

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.; Rao, Ch.M.

    Phosphate, organic matter and calcium carbonate content in five sediment cores (three from the outer shelf one from the slope and one from the basin) from the Arabian Sea have been determined. The distribution pattern indicates their close genetic...

  17. Biochemical and stable carbon isotope records of mangrove derived organic matter in the sediment cores

    Digital Repository Service at National Institute of Oceanography (India)

    Manju, M.N.; Resmi, P.; RatheeshKumar, C.S.; Gireeshkumar, T.R.; Chandramohanakumar, N.; Joseph, M.M.

    Core sediments from five mangrove ecosystems along northern Kerala Coast were collected to evaluate the nature and sources of organic matter in these ecosystems. General sedimentary parameters (pH, Eh, grain size and total organic carbon...

  18. Palynological investigation of the sediment cores from the Arabian Sea 2: Dinoflagellate cysts and acritarchs

    Digital Repository Service at National Institute of Oceanography (India)

    Saxena, R.K.; Chandra, A.; Setty, M.G.A.P.

    The present paper incorporates the study of dinoflagellate cysts and acritarchs recovered from five sediment cores from the Arabian Sea This assemblage is represented by 15 genera and 22 species Of these, 14 species belonging to 11 genera...

  19. 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

  20. Core sediment biogeochemistry in specific zones of Cochin ...

    Indian Academy of Sciences (India)

    land and ocean, where seawater is measurably diluted by the inflow of freshwater (Hobbie 2000). .... lignin were batch-extracted from the sediments with 0.05 M NaOH solution for 90 minutes and fil- tered. ...... metal accumulation in the sediments of the Cochin Estu- ary – Southwest coast of India; Environ. Monit. Assess.,.

  1. A description of sediment cores from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.

    environment; core no. 4 has oolitic layers with intercalations of clayey material and contains few fossils; and core no. 5 is characterized by two distinct lithologies, a definite stratigraphic break and a moderate concentration of fossils...

  2. Sediment Transport Model for a Surface Irrigation System

    Directory of Open Access Journals (Sweden)

    Damodhara R. Mailapalli

    2013-01-01

    Full Text Available Controlling irrigation-induced soil erosion is one of the important issues of irrigation management and surface water impairment. Irrigation models are useful in managing the irrigation and the associated ill effects on agricultural environment. In this paper, a physically based surface irrigation model was developed to predict sediment transport in irrigated furrows by integrating an irrigation hydraulic model with a quasi-steady state sediment transport model to predict sediment load in furrow irrigation. The irrigation hydraulic model simulates flow in a furrow irrigation system using the analytically solved zero-inertial overland flow equations and 1D-Green-Ampt, 2D-Fok, and Kostiakov-Lewis infiltration equations. Performance of the sediment transport model was evaluated for bare and cropped furrow fields. The results indicated that the sediment transport model can predict the initial sediment rate adequately, but the simulated sediment rate was less accurate for the later part of the irrigation event. Sensitivity analysis of the parameters of the sediment module showed that the soil erodibility coefficient was the most influential parameter for determining sediment load in furrow irrigation. The developed modeling tool can be used as a water management tool for mitigating sediment loss from the surface irrigated fields.

  3. Historical development of the Venice Lagoon contamination as recorded in radiodated sediment cores

    International Nuclear Information System (INIS)

    Pavoni, B.; Donazzolo, R.; Marcomini, A.; Orio, A.A.

    1987-01-01

    The use of radiodated sediment cores collected in the most contaminated area of the lagoon of Venice enabled the authors to reconstruct the historical evolution of the sediment pollution. The pollution is related to the development of specific activities in the industrial zone of Porto Marghera. Concentrations of heavy metals, organic carbon, total nitrogen, and total phosphorus were determined. The results reveal that the sediment contamination is mainly due to mercury and zinc. Also the total phosphorus and organic carbon accumulation was significant in the upper 10-20 cm of the cores. (U.K.)

  4. Factors influencing prokaryotic community structure composition in sub-surface coastal sediments

    Science.gov (United States)

    Molari, Massimiliano; Giovannelli, Donato; d'Errico, Giuseppe; Manini, Elena

    2012-01-01

    Despite the major influence of the marine sub-surface area in carbon cycling and global biogeochemistry, there is little known of prokaryotic distribution and community structure information of the marine sub-surface and the factors that influence sub-surface prokaryotic assemblages. We provide quantitative estimations of active Bacteria and Archaea down vertical profiles of sub-surface coastal sediments from the southern Adriatic Sea (Manfredonia Gulf). Prokaryotic biomass, carbon incorporation and the metabolically active fraction were compared with environmental, trophic, and predatory variables down 100-cm sediment cores sectioned into 21 layers. Multiple regression analysis was used to identify variables that can explain the variance of community compositions down vertical profiles. CARD-FISH analysis showed Bacteria dominance for the first 11 cm below sediment surface. The community then changed significantly at increasing depth, towards Archaea dominance. The models tested show that prokaryotic abundance in superficial marine sediments is controlled by organic trophic resources, while in sub-surface sediments, active prokaryotic abundance is driven by environmental factors and predatory pressure, suggesting that the shift in prokaryotic community structure could be coupled to a change in life-style of microbial assemblages.

  5. Distribution and assessment of heavy metal toxicity in sediment cores from Bizerte Lagoon, Tunisia.

    Science.gov (United States)

    Mna, Haïfa Ben; Oueslati, Walid; Helali, Mohamed Amine; Zaaboub, Noureddine; Added, Ayed; Aleya, Lotfi

    2017-07-01

    To examine the state of pollution of Bizerte Lagoon which is exposed to intense anthropogenic pressure, two sediment cores were taken at two sites, one undergoes the dual effects of both marine waters arriving from the Mediterranean Sea through the Channel, and also of freshwater from the Tinja River; the other core is located at the center of the lagoon where water depth is maximal (12 m). Heavy metal concentrations in the two cores were assessed, with calculated enrichment factors and geo-accumulation indexes. Core sediments were also studied for chemical speciation and their monosulfide contents were measured. Results from enrichment factors and geo-accumulation indexes show an accumulation of Cd, Zn, Cr, and Pb, while chemical speciation revealed a risk only from Cd and Mn. Comparison of sequential extraction values with those of acid volatile sulfides revealed that non-toxic effects may be caused by any of the studied metals in the sediment.

  6. HEAVY METALS IN SURFACE MUD SEDIMENT IN EKATERINBURG (RUSSIA

    Directory of Open Access Journals (Sweden)

    A. A. Seleznev

    2018-03-01

    Full Text Available Problem Statement. Now the most part of the world’s population lives in cities, thus, it is relevant the search for universal, low-cost and express methods for environmental geochemical investigations of an urban environment. The objective of the study is the assessment of content and properties of surface mud sediment at the urban territory (on the example of Ekaterinburg, Russia. Methods of the study. The 30 samples of surface mud sediment, soils and ground were collected in the residential area of the city. Particle size composition, measurements of heavy metals content, correlation analysis was conducted for the samples. Results. Surface mud sediment at the residential territories can be classified as surface facie of the recent anthropogenic sediment. Samples of the environmental compartments were collected at the territories of six blocks of houses of various years of construction, located in various parts of the city and at the various geological units. Five samples were collected in each block: 3 samples within the block and 2 samples – outside. The content of Pb, Zn, Cu, Ni, Co, and Mn was measured in particle size fractions of the samples. Particle size composition of the surface mud sediment in Ekaterinburg is similar to the particle size composition of the grounds formed on the sediments of Holocene age in Urals region. The positive statistically significant correlation was found between the couples of metals: Zn and Pb, Zn and Cu, Co and Ni. The distribution of concentrations of Pb, Zn and Cu over particle size fractions of surface mud sediment is heterogeneous. Pollution of the ground and soil in urban areas is due to the transition of heavy metals with particles of dust and fine sand. Typical geochemical association of metals for particle size fraction of surface mud sediment 0.002–0.01 mm – Mn-Zn-Ni-Cu-Pb-Co, that is similar to the association for sediments of surface puddles in local zones of relief, soils and bottom

  7. Biogeochemistry of mercury and methylmercury in sediment cores from Sundarban mangrove wetland, India--a UNESCO World Heritage Site.

    Science.gov (United States)

    Chatterjee, Mousumi; Canário, João; Sarkar, Santosh Kumar; Branco, Vasco; Godhantaraman, Nallamuthu; Bhattacharya, Bhaskar Deb; Bhattacharya, Asokkumar

    2012-09-01

    This study was performed to elucidate the distribution, concentration trend and possible sources of total mercury (Hg(T)) and methylmercury (MeHg) in sediment cores (<63 μm particle size; n = 75) of Sundarban mangrove wetland, northeastern part of the Bay of Bengal, India. Total mercury was determined by atomic absorption spectrometry (AAS) in a Leco AMA 254 instrument and MeHg by gas chromatography-atomic fluorescence spectrometry (GC-AFS). A wide range of variation in Hg(T) (0.032-0.196 μg g(-1) dry wt.) as well as MeHg (0.04-0.13 ng g(-1) dry wt.) concentrations revealed a slight local contamination. The prevalent low Hg(T) levels in sediments could be explained by sediment transport by the tidal Hugli (Ganges) River that would dilute the Hg(T) values via sediment mixing processes. A broader variation of MeHg proportions (%) were also observed in samples suggesting that other environmental variables such as organic carbon and microbial activity may play a major role in the methylation process. An overall elevated concentration of Hg(T) in surface layers (0-4 cm) of the core is due to remobilization of mercury from deeper sediments. Based on the index of geoaccumulation (I (geo)) and low effects-range (ER-L) values, it is considered that the sediment is less polluted by Hg(T) and there is less ecotoxicological risk. The paper provides the first information of MeHg in sediments from this wetland environment and the authors strongly recommend further examination of Hg(T) fluxes for the development of a detailed coastal MeHg model. This could provide more refine estimates of a total flux into the water column.

  8. Surface and Core Electronic Structure of Oxidized Silicon Nanocrystals

    Directory of Open Access Journals (Sweden)

    Noor A. Nama

    2010-01-01

    Full Text Available Ab initio restricted Hartree-Fock method within the framework of large unit cell formalism is used to simulate silicon nanocrystals between 216 and 1000 atoms (1.6–2.65 nm in diameter that include Bravais and primitive cell multiples. The investigated properties include core and oxidized surface properties. Results revealed that electronic properties converge to some limit as the size of the nanocrystal increases. Increasing the size of the core of a nanocrystal resulted in an increase of the energy gap, valence band width, and cohesive energy. The lattice constant of the core and oxidized surface parts shows a decreasing trend as the nanocrystal increases in a size that converges to 5.28 Ǻ in a good agreement with the experiment. Surface and core convergence to the same lattice constant reflects good adherence of oxide layer at the surface. The core density of states shows highly degenerate states that split at the oxygenated (001-(1×1 surface due to symmetry breaking. The nanocrystal surface shows smaller gap and higher valence and conduction bands when compared to the core part, due to oxygen surface atoms and reduced structural symmetry. The smaller surface energy gap shows that energy gap of the nanocrystal is controlled by the surface part. Unlike the core part, the surface part shows a descending energy gap that proves its obedience to quantum confinement effects. Nanocrystal geometry proved to have some influence on all electronic properties including the energy gap.

  9. Simulating Sediment Sorting of Streambed Surfaces - It's the Supply, Stupid

    Science.gov (United States)

    Wilcock, P. R.

    2014-12-01

    The grain size of the streambed surface is an integral part of the transport system because it represents the grains immediately available for transport. If the rate and size of grains entrained from the bed surface differ from that delivered to the bed surface, the bed surface grain size will change. Although this balance is intuitively clear, its implications can surprise. The relative mobility of different sizes in a mixture change as transport rates increase. At small transport rates, smaller sizes are more mobile. As transport rate increases, the transport grain size approaches that of the bed. This presents a dilemma when using flumes to simulate surface sorting and transport. When sediment is fed into a flume, the same sediment is typically used regardless of feed rate. The transport grain size remains constant at all rates, which does not match the pattern observed in the field. This operational constraint means that sediment supply is coarser than transport capacity in feed flumes, increasingly so as transport rates diminish. This imbalance drives a coarsening of the stream bed as less mobile coarse grains concentrate on the surface as the system approaches steady-state. If sediment is recirculated in a flume, sediment supply and entrainment are perfectly matched. Surface coarsening is not imposed, but does occur via kinematic sieving. The coarsening of the transport (and supply) accommodates the rate-dependent change in mobility such that the bed surface grain size does not change with transport rate. Streambed armoring depends on both the rate and grain size of sediment supply - their implications do not seem to be fully appreciated. A coarsened bed surface does not indicate sorting of the bed surface during waning flows - it can persist with active sediment supply and transport. Neither sediment feed nor sediment recirculating flumes accurately mimic natural conditions but instead represent end members that bracket the dynamics of natural streams

  10. Heavy metal distribution in mangrove sediment cores from selected sites along western coast of India

    Directory of Open Access Journals (Sweden)

    P. Vidya

    2016-09-01

    Full Text Available Sediment cores were collected from four different mangrove areas of northern Kerala and southern Karnataka, western coast of India.  The cores were analysed for the concentration of five heavy metals (Pb, Ni, Zn, Cu Fe using Atomic Absorption Spectrometry.  The levels of heavy metals in the present study from all the four sediment cores were in the order Fe > Pb > Zn > Ni > Cu and the mean concentrations of each elements in different cores were comparable.  According to Sediment Quality Guidelines (SQG, the mangrove sediments analysed here were moderately contaminated with Ni and heavily contaminated with Pb.  The increased concentration of Ni and Pb in the sediments might be due to their atmospheric deposition or water discharge from different far away sources since the areas selected for study were not disturbed by direct anthropogenic impacts.  Elevated levels of Fe which is considered to be a common phenomenon in mangrove sediments have also been found in the present study.  Heavy metal levels in sediments showed statistically significant correlations with pH, calcium carbonate and organic matter.  This suggests the influence of physico-chemical parameters on the adsorption, deposition and persistence of heavy metals in mangrove sediments.  The heavy metal concentration and the pollution status of the mangroves of west coast, especially the areas selected in this work are less studied before. Hence the data provide from the present baseline study would be further helpful in remediation and management of mangrove ecosystem. 

  11. Radiocarbon dates of sediment cores from innercontinental shelf off Karwar, West Coast of India

    International Nuclear Information System (INIS)

    Nambiar, A.R.; Rao, B.R.J.

    1991-01-01

    Two samples of carbonized wood and one of shells from sediment cores off Karwar were dated by 14 C method. Radiometric ages of carbonized wood beds indicate transgression of the sea and submergence of coastal forests around 9000-10000 years before present in the Karwar area. The rate of sedimentation varies between 0.89 mm per year near the coast and o.44 mm per year away from the coast. (author). 8 refs

  12. Surface sediment characteristics and tower karst dissolution, Guilin, southern China

    Science.gov (United States)

    Tang, Tao

    2003-01-01

    Dissolution of extensive outcrops of limestone and dolostone in humid tropical and subtropical southern China produced numerous caves and residual hills that are referred as tower karst. This study identifies and relates the physical and chemical characteristics of the surface sediment with the limestone bedrock in Guilin to assess the influence of the limestone dissolution process on sediment composition. The results of this study indicated that (i) both limestone and dolostone of the region are very pure (99.5% and 98.5% of CaCO 3 and MgCO 3, respectively); (ii) the material composition of limestone and dolostone is different from that of soil and sediment of the region: constituents of surface sediments are highly related with the clastic sedimentary rocks, such as the mudstone, but show negative correlation with limestone and dolostone; (iii) the limestone formations are highly resistant to physical weathering and disintegration; their durability versus physical weathering and their high susceptibility to chemical dissolution account for why residual towers can form and persist; (iv) a dual-zone environmental structure exists vertically downward from the surface in Guilin: the zone of unconsolidated clastic sediments that is predominantly acidic, and the zone of karstified limestone that is predominantly basic. The evidence suggests that the environment and processes differ in these two zones. The chemical dissolution of limestone that formed tower karst of the region is not mainly responsible for the accumulation of clastic sediment on the surface.

  13. Modern sedimentation patterns in Laguna de Medina, Southern Spain, derived from lake surface and soil samples

    Science.gov (United States)

    van ´t Hoff, Jasmijn; Schröder, Tabea; Reicherter, Klaus; Held, Peter; Melles, Martin

    2016-04-01

    In September 2014 and March 2015, a 25.66 m long sediment core (Co1313) was retrieved from the centre of Laguna de Medina, a small endorheic salt lake in Cádiz, SW Spain. This record covers the last 9.000 years, thus providing an unique archive for Holocene climatic and environmental changes with extraordinary high temporal resolution. For a better understanding of the palaeoenvironmental proxies to be analysed on the sediment core, the modern processes of sediment formation in the lake and its catchment under known environmental conditions were investigated on a set of 46 lake sediment surface samples and 32 soil surface sediment samples from the lake and the close surroundings, respectively. These samples were analysed for bulk mineralogy (XRD), chemical composition (XRF), grain-size distribution (laser scanner), and carbonate, total organic carbon (TOC), nitrogen (TN) and sulphur (TS) contents (elemental analyser). Based on the mineralogical, geochemical and granulometrical data, the lake can be divided into four zones. The northern shore is characterized by particularly high quartz contents and coarse grain sizes. This reflects input from ancient terraces of the Guadalete River that are exposed in that area. The southern shore is characterised by high calcite contents due to sediment supply from the Cretaceous ´Capas rojaś, a series of Subbetic deep-water marl- and limestones. The southeastern and to a lesser extend the northwestern shores show particularly high dolomite contents, reflecting the Triassic dolomites outcroping in the southeastern catchment. The southeastern shore furthermore is also influenced by strong terrestrial input of the Triassic Keuper facies from the most important inlet, Arroyo Fuente Bermeja, as reflected by high contents of Ti, K, Al, Fe, Rb in the lake sediments. The last zone comprises only a small part of the western shore and is characterized by a relatively high gypsum amount. This does not reflect the geology in the catchment

  14. Assessment of metals pollution in sediment cores from the Sabah-Sarawak coastal waters

    International Nuclear Information System (INIS)

    Zal Uyun Wan Mahmood; Zaharudin Ahmad; Che Abdul Rahim Mohamed; Abdul Kadir Ishak; Norfaizal Mohammed

    2011-01-01

    The distribution, enrichment and pollution status of metals in sediment cores from the Sabah-Sarawak coastal waters were studied. Seven sediment cores were taken in July 2004 using a gravity box corer. The metals of Cu, Zn and Pb were analyzed by ICP-MS to assess the pollution status of the sediments. The sediment fine fraction and organic carbon content was also analyzed. Enrichment Factor (EF), Geo accumulation Index (Igeo) and Pollution Load Index (PLI) was calculated as criteria of possible contamination. The results showed that collected sediments were composed with clay, silt and sand as 12 - 74 %, 27 - 72 % and 0 - 20 %, respectively. Meanwhile, organic carbon contents were relatively low and constant over time, based on sediment depth profiles, and it did not exceed 5 % at any sampling station. The average metal concentrations in sediment cores at all sampling station were distributed in the ranges of 1.66 ± 1.36 - 6.61 ± 0.12 μgg -1 for Cu, 26.55 ± 1.04 - 57.94 ± 1.58 μgg -1 for Zn and 3.99 ± 0.10 - 14.48 ± 0.32 μgg -1 for Pb. According to calculations of EF, I geo and PLI, it can be concluded that concentrations of Cu, Zn and Pb were not significantly affected by pollution from anthropogenic sources at the seven sampling locations. Thus, the metal content of Cu, Zn and Pb in sediment should not cause pollution problem to the marine environment of Sabah-Sarawak coastal waters and further response measures are not needed. (author)

  15. Microbial diversity in methane hydrate-bearing deep marine sediments core preserved in the original pressure.

    Science.gov (United States)

    Takahashi, Y.; Hata, T.; Nishida, H.

    2017-12-01

    In normal coring of deep marine sediments, the sampled cores are exposed to the pressure of the atmosphere, which results in dissociation of gas-hydrates and might change microbial diversity. In this study, we analyzed microbial composition in methane hydrate-bearing sediment core sampled and preserved by Hybrid-PCS (Pressure Coring System). We sliced core into three layers; (i) outside layer, which were most affected by drilling fluids, (ii) middle layer, and (iii) inner layer, which were expected to be most preserved as the original state. From each layer, we directly extracted DNA, and amplified V3-V4 region of 16S rRNA gene. We determined at least 5000 of nucleotide sequences of the partial 16S rDNA from each layer by Miseq (Illumina). In the all layers, facultative anaerobes, which can grow with or without oxygen because they can metabolize energy aerobically or anaerobically, were detected as majority. However, the genera which are often detected anaerobic environment is abundant in the inner layer compared to the outside layer, indicating that condition of drilling and preservation affect the microbial composition in the deep marine sediment core. This study was conducted as a part of the activity of the Research Consortium for Methane Hydrate Resources in Japan [MH21 consortium], and supported by JOGMEC (Japan Oil, Gas and Metals National Corporation). The sample was provided by AIST (National Institute of Advanced Industrial Science and Technology).

  16. A preliminary study on the behavior of trace elements in sediment cores from Ilha Grande (Rio de Janeiro State) by neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Wasserman, Julio Cesar [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Geoquimica; Figueiredo, Ana Maria G. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil); Figueira, Andre Luiz [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Dept. de Oceanografia; Kelecom, Alphonse [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Biologia Geral

    2002-07-01

    The present work aims to identify atmospheric and marine inputs of 9 metals (Ba, Co, Cr, Cs, Fe, Hf, Rb, Sc, Zn), 8 rare earths (La, Ce, Nd, Sm, Eu, Tb, Yb e Lu), 2 actinides (U, Th) and 3 non-metals (As, Sb, Se) in sediment cores from a remote area, the Biological Reserve of Praia do Sul, Ilha Grande, Rio de Janeiro, Brazil. The sediment cores were sampled in a peat bog (out of the tidal reach) and in a mangrove, downstream of the peat bog. The analytical technique employed was Instrumental Neutron Activation Analysis. The samples were irradiated for 16 hours at a thermal neutron flux of 10{sup 12} n cm{sup -2} s{sup -1} at the IEA-R1 reactor of IPEN. The measurements of the induced gamma-ray activity were carried out by high resolution gamma spectrometry, with an hyperpure Ge detector. A preliminary sediment dating with Po-210 was also carried out by applying radiochemical procedures and measurements were done in an Alfa spectrometer The results indicate that the peat bog core present a slight surface enrichment that can be attributed to atmospheric inputs. Increasing concentrations of metals with age is probably due to history of soil occupation. In the mangrove core, no significant increase in concentration could be detected in the surface sediments (except for Zn) confirming the suitability of the peat bog core as a tracer for atmospheric inputs. (author)

  17. High resolution optically stimulated luminescence dating of a sediment core from the southwestern Sea of Okhotsk

    DEFF Research Database (Denmark)

    Sugisaki, S.; Buylaert, J. P.; Murray, A. S.

    2012-01-01

    in application to a 19 m marine sediment core (MR0604-PC04A) taken from the southwestern Sea of Okhotsk, immediately to the north of Hokkaido, Japan. Fine-grained quartz (4 to 11 mu m) was chosen as the dosimeter, and a single-aliquot regenerative-dose protocol was used for the determination of equivalent dose...

  18. Geochemistry of deep-sea sediment cores from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Mudholkar, A.V.; Pattan, J; Parthiban, G.

    , thought to be of diagenetic origin. Metals are suppliEd. by upward migration from a suboxic to anoxic zone at an intermediate depth of 12-35 cm below the sediment-water interface in all the cores. Buried maxima in transition metal concentration at depth...

  19. Shallow stratigraphy of the Skagit River Delta, Washington, derived from sediment cores

    Science.gov (United States)

    Grossman, Eric E.; George, Douglas A.; Lam, Angela

    2011-01-01

    Sedimentologic analyses of 21 sediment cores, ranging from 0.4 to 9.6 m in length, reveal that the shallow geologic framework of the Skagit River Delta, western Washington, United States, has changed significantly since 1850. The cores collected from elevations of 3.94 to -2.41 m (relative to mean lower low water) along four cross-shore transects between the emergent marsh and delta front show relatively similar environmental changes across an area spanning ~75 km2. Offshore of the present North Fork Skagit River and South Fork Skagit River mouths where river discharge is focused by diked channels through the delta, the entire 5–7-km-wide tidal flats are covered with 1–2 m of cross-bedded medium-to-coarse sands. The bottoms of cores, collected in these areas are composed of mud. A sharp transition from mud to a cross-bedded sand unit indicates that the tidal flats changed abruptly from a calm environment to an energetic one. This is in stark contrast to the Martha's Bay tidal flats north of the Skagit Bay jetty that was completed in the 1940s to protect the newly constructed Swinomish Channel from flooding and sedimentation. North of the jetty, mud ranging from 1 to 2 m thick drapes a previously silt- and sand-rich tidal flat. The silty sand is a sediment facies that would be expected there where North Fork Skagit River sedimentation occurred prior to jetty emplacement. This report describes the compositional and textural properties of the sediment cores by using geophysical, photographic, x-radiography, and standard sediment grain-size and carbon-analytical methods. The findings help to characterize benthic habitat structure and sediment transport processes and the environmental changes that have occurred across the nearshore of the Skagit River Delta. The findings will be useful for quantifying changes to nearshore marine resources, including impacts resulting from diking, river-delta channelization, shoreline development, and natural variations in fluvial-sediment

  20. Forearc uplift rates deduced from sediment cores of two coastal lakes in south-central Chile

    Science.gov (United States)

    Stefer, Susanne; Moernaut, Jasper; Melnick, Daniel; Echtler, Helmut P.; Arz, Helge W.; Lamy, Frank; De Batist, Marc; Oncken, O.; Haug, Gerald H.

    2010-11-01

    The present paper introduces a new approach for deriving information about local forearc tectonics and related uplift rates based on the study of lake sediments. We investigated two coastal lakes at the south-central Chile margin, lakes Lanalhue and Lleu Lleu, located south of the Arauco Peninsula (38°S). Both lakes developed within the valleys of ancient rivers that once drained to the Pacific Ocean, being subsequently dammed by rising sills in the late Pleistocene/early Holocene. Seismic profiling and sedimentological analyses of cores from both lakes revealed similar successions consisting of marine to brackish sediments covered by lacustrine deposits. Radiocarbon dating indicates that the marine-lacustrine transition occurred at 8 ka and 8.15 ka, respectively. The correlation of this transition with global sea-level curves allowed the calculation of local uplift rates for the Holocene. Uplift rates for the lake basins amount to 0.42 ± 0.71 and 0.49 ± 0.44 mm/a, respectively, which are consistent with rates determined from a late Pleistocene marine terrace in the area. However, conspicuously higher, though likely transient, vertical movements at 8.83 ± 2.7 mm/a and 11.36 ±1.77 mm/a, respectively, were calculated for the sills that block both lakes nowadays. These barriers are interpreted to be the surface expression of a blind reverse fault associated to the Morguilla fault system, a seismically-active structure that controls uplift and folding along the adjacent Arauco Peninsula.

  1. Fine and coarse components in surface sediments from Bikini Lagoon

    Energy Technology Data Exchange (ETDEWEB)

    Noshkin, V. E., LLNL

    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 in the lagoon of Bikini Atoll, one of the two sites in the Marshall Islands used by the United States to test nuclear devices from 1946 through 1958. 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, by comparison, what modifications occurred in the composition since the sediments were first described in samples collected before testing in 1946. Nuclear testing produced more finely divided material that is now found in the surface sediment layer over large areas of the lagoon and especially in regions of the lagoon and reef adjacent to test sites. The 5 cratering events alone at Bikini Atoll redistributed sufficient material to account for the higher inventory of fine material found over the surface 4 cm of the sediment 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 greatly change the general geographical features of the major sedimentary components over most of the lagoon floor.

  2. Measuring the role of seagrasses in regulating sediment surface elevation.

    Science.gov (United States)

    Potouroglou, Maria; Bull, James C; Krauss, Ken W; Kennedy, Hilary A; Fusi, Marco; Daffonchio, Daniele; Mangora, Mwita M; Githaiga, Michael N; Diele, Karen; Huxham, Mark

    2017-09-20

    Seagrass meadows provide numerous ecosystem services and their rapid global loss may reduce human welfare as well as ecological integrity. In common with the other 'blue carbon' habitats (mangroves and tidal marshes) seagrasses are thought to provide coastal defence and encourage sediment stabilisation and surface elevation. A sophisticated understanding of sediment elevation dynamics in mangroves and tidal marshes has been gained by monitoring a wide range of different sites, located in varying hydrogeomorphological conditions over long periods. In contrast, similar evidence for seagrasses is sparse; the present study is a contribution towards filling this gap. Surface elevation change pins were deployed in four locations, Scotland, Kenya, Tanzania and Saudi Arabia, in both seagrass and unvegetated control plots in the low intertidal and shallow subtidal zone. The presence of seagrass had a highly significant, positive impact on surface elevation at all sites. Combined data from the current work and the literature show an average difference of 31 mm per year in elevation rates between vegetated and unvegetated areas, which emphasizes the important contribution of seagrass in facilitating sediment surface elevation and reducing erosion. This paper presents the first multi-site study for sediment surface elevation in seagrasses in different settings and species.

  3. Measuring the role of seagrasses in regulating sediment surface elevation

    KAUST Repository

    Potouroglou, Maria

    2017-09-13

    Seagrass meadows provide numerous ecosystem services and their rapid global loss may reduce human welfare as well as ecological integrity. In common with the other \\'blue carbon\\' habitats (mangroves and tidal marshes) seagrasses are thought to provide coastal defence and encourage sediment stabilisation and surface elevation. A sophisticated understanding of sediment elevation dynamics in mangroves and tidal marshes has been gained by monitoring a wide range of different sites, located in varying hydrogeomorphological conditions over long periods. In contrast, similar evidence for seagrasses is sparse; the present study is a contribution towards filling this gap. Surface elevation change pins were deployed in four locations, Scotland, Kenya, Tanzania and Saudi Arabia, in both seagrass and unvegetated control plots in the low intertidal and shallow subtidal zone. The presence of seagrass had a highly significant, positive impact on surface elevation at all sites. Combined data from the current work and the literature show an average difference of 31 mm per year in elevation rates between vegetated and unvegetated areas, which emphasizes the important contribution of seagrass in facilitating sediment surface elevation and reducing erosion. This paper presents the first multi-site study for sediment surface elevation in seagrasses in different settings and species.

  4. Assessment of acid leachable trace metals in sediment cores from River Uppanar, Cuddalore, Southeast coast of India

    International Nuclear Information System (INIS)

    Ayyamperumal, T.; Jonathan, M.P.; Srinivasalu, S.; Armstrong-Altrin, J.S.; Ram-Mohan, V.

    2006-01-01

    An acid leachable technique is employed in core samples (C1, C2 and C3) to develop a baseline data on the sediment quality for trace metals of River Uppanar, Cuddalore, southeast coast of India. Acid leachable metals (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn and Cd) indicate peak values at the sulphidic phase and enrichment of metals in the surface layers are due to the anthropogenic activities. Association of trace metals with Fe, Mn indicates their adsorption onto Fe-Mn oxyhydroxides and their correlation with S indicate that they are precipitated as metal sulphides. Factor analysis identified three possible types of geochemical associations and the supremacy of trace metals along with Fe, Mn, S and mud supports their geochemical associations. Factor analysis also signifies that anthropogenic activities have affected both the estuarine and fresh water regions of River Uppanar. - Both natural and anthropogenic factors are affecting metals in sediments

  5. Report on Radiocarbon Analysis of Surface Sediments from the Fore-Arc Basin of Nankai Trough

    National Research Council Canada - National Science Library

    Pohlman, John

    2004-01-01

    .... Radiocarbon analysis of the total organic carbon (TOC) and total inorganic carbon (TIC) on 30 sediment samples from two multicores and six piston cores was performed to investigate the fate of methane carbon in sediment of the Nankal Trough...

  6. Acid leachable trace metals in sediment cores from Sunderban Mangrove Wetland, India: an approach towards regular monitoring.

    Science.gov (United States)

    Jonathan, M P; Sarkar, S K; Roy, P D; Alam, Md A; Chatterjee, M; Bhattacharya, B D; Bhattacharya, A; Satpathy, K K

    2010-02-01

    The paper presents the first document to identify the enrichment pattern of acid leachable trace metals (ALTMs) such as Fe, Mn, Cr, Cu, Ni, Pb, Cd, Co, Mo, Ag, As and Ba and their relationship with sediment quality parameters (pH, organic carbon, carbonates and texture) in core sediments (mud. The results indicate that the change in pH values causes coagulation and precipitation of ALTMs. Fe and Mn have fairly close distribution patterns of enrichment in surface layers which might be ascribed to early diagnetic processes. The most prominent feature of ALTMs is the enrichment of Fe, Mn, Cr, Cu, Ni, Pb, and Ba in the surface-subsurface layers in the sediment cores, which is mainly attributed to the intense industrial and agricultural activities as well as drainage of untreated domestic sewage to this coastal region. The ALTMs also indicate their association with organic carbon and Fe-Mn oxyhydroxides. The enrichment is well--supported by the correlation, grouping and clustering of ALTMs in statistical analyses. Anthropogenic Factor values indicated ALTMs enrichment for all trace metals due to intense anthropogenic activities. Overall higher values of ALTMs in sediments in comparison to other Indian coastal regions indicate that they are mainly due to the uncontrolled anthropogenic activities in this mangrove estuarine complex. Statistical analyses suggest that five ALTMs (Cu, Pb, As, Mo, Ba) are attached to the organic particles and the clustering of elements separately also indicates that they are from external source. The result of the present study suggests the need for a regular monitoring program which will help to improve the quality of this potential wetland.

  7. A Direct-Push Sample-Freezing Drive Shoe for Collecting Sediment Cores with Intact Pore Fluid, Microbial, and Sediment Distributions

    Science.gov (United States)

    Bekins, B. A.; Trost, J.; Christy, T. M.; Mason, B.

    2015-12-01

    Abiotic and biological reactions in shallow groundwater and bottom sediments are central to understanding groundwater contaminant attenuation and biogeochemical cycles. The laminar flow regime in unconsolidated surficial aquifers creates narrow reaction zones. Studying these reaction zones requires fine-scale sampling of water together with adjacent sediment in a manner that preserves in situ redox conditions. Collecting representative samples of these narrow zones with traditional subsurface sampling equipment is challenging. For example, use of a basket type core catcher for saturated, non-cohesive sediments results in loss of fluid and sediments during retrieval. A sample-freezing drive shoe designed for a wire line piston core sampler allowed collection of cores with intact sediment, microbial, and pore fluid distributions and has been the basis for studies documenting centimeter-scale variations in aquifer microbial populations (Murphy and Herkelrath, 1996). However, this freezing drive shoe design is not compatible with modern-day direct push sampling rigs. A re-designed sample-freezing drive shoe compatible with a direct-push dual-tube coring system was developed and field-tested. The freezing drive shoe retained sediment and fluid distributions in saturated sediment core samples by freezing a 10 centimeter plug below the core sample with liquid CO­2. Core samples collected across the smear zone at a crude oil spill site near Bemidji, Minnesota, were successfully extracted without loss of fluid or sediment. Multiple core sections from different depths in the aquifer were retrieved from a single hole. This new design makes a highly effective sampling technology available on modern-day direct push sampling equipment to inform myriad questions about subsurface biogeochemistry processes. The re-design of the freezing drive shoe was supported by the USGS Innovation Center for Earth Sciences. References: Murphy, Fred, and W. N. Herkelrath. "A sample

  8. Concentrations and enrichment of metals in sediment cores: geochemistry and correlations with geoaccumulation index

    Directory of Open Access Journals (Sweden)

    Felippe Fernandes

    2017-07-01

    Full Text Available The Mãe d’Água dam was built in 1962 to supply the Federal University of Rio Grande do Sul’s water demanding. Thus, the paper aims to measure Nickel (Ni and Zinc (Zn concentrations in many depths of the dam’s bottom, sampling cores of sediments silted in it. The samplings were carried out in June, 2014, and it was sampled four sediment cores in pre-defined points of the dam. The methodology for extraction of sediment cores was ‘Piston Core’. Sediment particles smaller than 63 μm were separated and used for chemical analysis. EPA 3050 acid digestion methodology is used by the U.S. Environment Protection Agency and it was also used in this study. Analyses were carried out in duplicate and two USGS reference materials were used for quality control: SGR-1b and SCO-1. Zn and Ni concentrations were over than local background values and increasing concentrations of the deepest sendiments to the most recent layers as a result of urbanization activities. Geoaccumulation index was able to characterize decreasing of metal concentrations in depth.

  9. Concentrations of Mn and Fe in the Sediment Cores of Sarawak and Sabah Coastal Waters

    International Nuclear Information System (INIS)

    Zal Uyun Wan Mahmood; Zaharudin Ahmad; Che Abdul Rahim Mohamed

    2010-01-01

    Sediment cores were taken at eight stations along Sarawak and Sabah coastal waters using a gravity box corer on July 2004. The sediment cores were cut into 2 cm interval for measurement of Mn and Fe concentration using the Inductive Couple Plasma-Mass Spectrometer (ICP-MS). Overall, the sediment cores contained much mud which include a mixture of silt (46 - 67 %) and clay (18 - 53 %) compared to sand (0.4 - 16 %). The concentrations of Mn and Fe were in the range of 154 - 366 μg/ g and 0.9 - 3.4 %, respectively. The variation was studied by ANOVA, which showed a significant difference (p = 0.000) for both of Mn and Fe concentrations at all sampling stations. In those ranges, Fe concentration was higher compared to Mn. It is believed that dissolving and diluting process influenced the concentration of Mn in the water column and sediment. Fe showed a significant correlation (r > 0.5, p geo < 1 and classification 0 - 1. (author)

  10. 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 ...

  11. [Study on trace elements of lake sediments by ICP-AES and XRF core scanning].

    Science.gov (United States)

    Cheng, Ai-Ying; Yu, Jun-Qing; Gao, Chun-Liang; Zhang, Li-Sha; He, Xian-Hu

    2013-07-01

    It is the first time to study sediment of Toson lake in Qaidam Basin. Trace elements including Cd, Cr, Cu, Zn and Pb in lake sediment were measured by ICP-AES method, studied and optimized from different resolution methods respectively, and finally determined a optimum pretreatment system for sediment of Toson lake, namely, HCl-HNO3-HF-HClO4-H2O2 system in the proportions of 5 : 5 : 5 : 1 : 1 was determined. At the same time, the data measured by XRF core scanning were compared, the use of moisture content correction method was analyzed, and the influence of the moisture content on the scanning method was discussed. The results showed that, compared to the background value, the contents of Cd and Zn were a little higher, the content of Cr, Cu and Pb was within the background value limits. XRF core scanning was controlled by sediment elements as well as water content in sediment to some extent. The results by the two methods showed a significant positive correlation, with the correlation coefficient up to 0.673-0.925, and they have a great comparability.

  12. Analytical approaches for determination of bromine in sediment core samples by X-ray fluorescence spectrometry.

    Science.gov (United States)

    Pashkova, Galina V; Aisueva, Tatyana S; Finkelshtein, Alexander L; Ivanov, Egor V; Shchetnikov, Alexander A

    2016-11-01

    Bromine has been recognized as a valuable indicator for paleoclimatic studies. Wavelength dispersive X-ray fluorescence (WDXRF) and total reflection X-ray fluorescence (TXRF) methods were applied to study the bromine distributions in lake sediment cores. Conventional WDXRF technique usually requires relatively large mass of a sediment sample and a set of calibration samples. Some analytical approaches were developed to apply WDXRF to small sediment core samples in the absence of adequate calibration samples with a known Br content. The mass of a sample to be analyzed was reduced up to 200-300mg and the internal standard method with correction using fundamental parameters was developed for Br quantification. TXRF technique based on the direct analysis of a solid suspension using 20mg of sediment sample by internal standard method was additionally tested. The accuracy of the WDXRF and TXRF techniques was assessed by the comparative analysis of reference materials of sediments, soil and biological samples. In general, good agreement was achieved between the reference values and the measured values. The detection limits of Br were 1mg/kg and 0.4mg/kg for WDXRF and TXRF respectively. The results of the Br determination obtained with different XRF techniques were comparable to each other and used for paleoclimatic reconstructions. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Time trends of perfluorinated compounds from the sediment core of Tokyo Bay, Japan (1950s-2004)

    Energy Technology Data Exchange (ETDEWEB)

    Zushi, Yasuyuki; Tamada, Masafumi [Graduate School of Environment and Information Sciences, Yokohama National University, 79-7 Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan); Kanai, Yutaka [Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba 305-8567 (Japan); Masunaga, Shigeki, E-mail: masunaga@ynu.ac.j [Graduate School of Environment and Information Sciences, Yokohama National University, 79-7 Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan)

    2010-03-15

    Perfluorinated compounds (PFCs) were detected in sediment core samples collected in Tokyo Bay to reveal their time trends. The core sample deposited during 1950s-2004 was divided into two- to three-year intervals and the concentrations of 24 types of PFCs were determined. Perfluorooctane sulfonate (PFOS) decreased gradually from the early 1990s and its precursor decreased rapidly in the late 1990s, whereas perfluorooctanoic acid (PFOA) increased rapidly. The observed trends were regarded as a reflection of the shift from perfluorooctyl sulfonyl fluoride (PFOSF)-based products to telomer-based products after the phaseout of PFOSF-based products in 2001. The branched isomers of perfluoroundecanoic acid (PFUnDA) and perfluorotridecanoic acid (PFTrDA) were detected in the sample with its ratio of linear-isomer/branched-isomer concentrations decreasing. In this study, we revealed that the sediment core can serve as a tool for reconstructing the past pollution trend of PFCs and can provide interesting evidence concerning their environmental dynamics and time trend. - This study reports the time trends of the concentrations of 24 species of PFCs, including FTCA, FTUCA and FOSAA, in a sediment core of Tokyo Bay, Japan.

  14. Reconstruction of climate change at sub-decadal resolution from marine sediment cores from the Gulf of Taranto, Mediterranean Sea

    Science.gov (United States)

    Grauel, A.; Mueller, I.; Bernasconi, S. M.; Zonneveld, K. A.; de Lange, G. J.

    2009-12-01

    In the framework of MOCCHA project (Multidisciplinary study of continental/ocean climate dynamics using high-resolution records from the eastern Mediterranean) we are reconstructing Holocene climate change from high sedimentation rate marine cores collected in the Gulf of Taranto (Italy). For a calibration study, we carried out oxygen and carbon isotope analysis of planktonic foraminifera of an extensive set of sediment surface samples taken along the southern Italian coast. The comparison with seasonal satellite-based sea surface temperature maps and water column profiles, as well as to a set of water samples from the Gulf of Taranto allows estimating the effect of salinity on the δ18O of foraminifera. The results indicate that the planktonic species G. ruber, while being highly affected by different salinity distributions, predominantly record a signal for summer temperature conditions. Measurements of G. ruber (white and pink sub-species) at 5 year resolution from a short core covering the last 700 years, show large and coherent variations in δ18O which can be correlated to global temperature reconstructions, suggesting that this is a very promising site for reconstructing Holocene climate variability. Differences in the records of the two subspecies indicate an anthropogenic impact on the ecology of these foraminifera for the last 100 years, which is probably related to nutrient inputs.

  15. The Record of Geomagnetic Excursions from a ~150 m Sediment Core: Clear Lake, Northern California

    Science.gov (United States)

    Levin, E.; Byrne, R.; Looy, C. V.; Wahl, D.; Noren, A. J.; Verosub, K. L.

    2015-12-01

    We are studying the paleomagnetic properties of a new ~150 meter drill core from Clear Lake, CA. Step-wise demagnetization of the natural remanent magnetism (NRM) yields stable directions after 20 mT, implying that the sediments are reliable recorders of geomagnetic field behavior. Several intervals of low relative paleointensity (RPI) from the core appear to be correlated with known geomagnetic excursions. At about 46 m depth, and ~33 ka according to an age model based on radiocarbon dates obtained from pollen and the Olema ash bed, a low RPI zone seems to agree with the age and duration of the Mono Lake Excursion, previously identified between 32 and 35 ka. Slightly lower in the core, at about 50 m depth and ~40 ka, noticeably low RPI values seem to be coeval with the Laschamp excursion, which has been dated at ~41 ka. A volcanic ash near the bottom of the core (141 mblf) is near the same depth as an ash identified in 1988 by Andrei Sarna-Wojcicki and others as the Loleta ash bed in a previous Clear Lake core. If the basal ash in the new core is indeed the, Loleta ash bed, then the core may date back to about 270-300 ka. Depending on the age of the lowest ash, a sequence of low RPI intervals could correlate with the Blake (120 ka), Iceland Basin (188 ka), Jamaica/Pringle Falls (211 ka), and CR0 (260 ka) excursions. Correlation of the low RPI intervals to these geomagnetic excursions will help in the development of a higher resolution chronostratigraphy for the core, resolve a long-standing controversy about a possible hiatus in the Clear Lake record, and provide information about climatically-driven changes in sedimentation.

  16. Toxicity of sediment cores collected from the Ashtabula River in northeastern Ohio, USA, to the amphipod Hyalella azteca

    Science.gov (United States)

    Ingersoll, C.G.; Kemble, N.E.; Kunz, J.L.; Brumbaugh, W.G.; MacDonald, D.D.; Smorong, D.

    2009-01-01

    This study was conducted to support a Natural Resource Damage Assessment and Restoration project associated with the Ashtabula River in Ohio. The objective of the study was to evaluate the chemistry and toxicity of 50 sediment samples obtained from five cores collected from the Ashtabula River (10 samples/core, with each 10-cm-diameter core collected to a total depth of about 150 cm). Effects of chemicals of potential concern (COPCs) measured in the sediment samples were evaluated by measuring whole-sediment chemistry and whole-sediment toxicity in the sediment samples (including polycyclic aromatic hydrocarbons [PAHs], polychlorinated biphenyls [PCBs], organochlorine pesticides, and metals). Effects on the amphipod Hyalella azteca at the end of a 28-day sediment toxicity test were determined by comparing survival or length of amphipods in individual sediment samples in the cores to the range of responses of amphipods exposed to selected reference sediments that were also collected from the cores. Mean survival or length of amphipods was below the lower limit of the reference envelope in 56% of the sediment samples. Concentrations of total PCBs alone in some samples or concentrations of total PAHs alone in other samples were likely high enough to have caused the reduced survival or length of amphipods (i.e., concentrations of PAHs or PCBs exceeded mechanistically based and empirically based sediment quality guidelines). While elevated concentrations of ammonia in pore water may have contributed to the reduced length of amphipods, it is unlikely that the reduced length was caused solely by elevated ammonia (i.e., concentrations of ammonia were not significantly correlated with the concentrations of PCBs or PAHs and concentrations of ammonia were elevated both in the reference sediments and in the test sediments). Results of this study show that PAHs, PCBs, and ammonia are the primary COPCs that are likely causing or substantially contributing to the toxicity to

  17. Sediment core fossils in ancient Lake Ohrid: testing for faunal change since the Last Interglacial

    Directory of Open Access Journals (Sweden)

    C. Albrecht

    2010-11-01

    Full Text Available Ancient Lake Ohrid is probably of early Pleistocene or Pliocene origin and amongst the few lakes in the world harbouring an outstanding degree of endemic biodiversity. Although there is a long history of evolutionary research in Lake Ohrid, particularly on molluscs, a mollusc fossil record has been missing up to date. For the first time, gastropod and bivalve fossils are reported from the basal, calcareous part of a 2.6 m long sediment succession (core Co1200 from the north-eastern part of Lake Ohrid. Electron spin resonance (ESR dating of mollusc shells from the same stratigraphic level yielded an age of 130 ± 28 ka. Lithofacies III sediments, i.e. a stratigraphic subdivision comprising the basal succession of core Co1200 between 181.5–263 cm, appeared solid, greyish-white, and consisted almost entirely of silt-sized endogenic calcite (CaCO3>70% and intact and broken mollusc shells. Here we compare the faunal composition of the thanatocoenosis with recent mollusc associations in Lake Ohrid. A total of 13 mollusc species (9 gastropod and 4 bivalve species could be identified within Lithofacies III sediments. The value of sediment core fossils for reconstructing palaeoenvironmental settings was evaluated and the agreement between sediment and palaeontological proxies was tested.

    The study also aims at investigating major faunal changes since the Last Interglacial and searching for signs of extinction events.

    The combined findings of the ecological study and the sediment characteristics suggest deposition in a shallow water environment during the Last Interglacial. The fossil fauna exclusively included species also found in the present fauna, i.e. no extinction events are evident for this site since the Last Interglacial. The thanatocoenosis showed the highest similarity with recent Intermediate Layer (5–25 m water depth mollusc assemblages. The demonstrated existence of a mollusc fossil record in Lake Ohrid

  18. Tracing the origin of Pb using stable Pb isotopes in surface sediments along the Korean Yellow Sea coast

    Science.gov (United States)

    Park, Jong-Kyu; Choi, Man-Sik; Song, Yunho; Lim, Dhong-Il

    2017-06-01

    To investigate the factors controlling lead (Pb) concentration and identify the sources of Pb in Yellow Sea sediments along the Korean coast, the concentration of Pb and Pb isotopes in 87 surface and 6 core sediment samples were analyzed. The 1 M HCl leached Pb concentrations had a similar geographic distribution to those of fine-grained sediments, while the distribution of residual Pb concentrations resembled that of coarse-grained sediments. Leached Pb was presumed to be associated with manganese (Mn) oxide and iron (Fe) oxy/hydroxide, while residual Pb was associated with potassium (K)-feldspar, based on good linear relationships between the leached Pb and the Fe/Mn concentrations, and the residual Pb and K concentrations. Based on a ratio-ratio plot with three isotopes (207Pb/206Pb and 208Pb/206Pb) and the geographic location of each sediment, sediments were categorized into two groups of samples as group1 and group2. Group 1 sediments, which were distributed in Gyeonggi Bay and offshore (north of 36.5°N), were determined to be a mixture of anthropogenic and natural Pb originating from the Han River, based on a 208Pb/206Pb against a Cs/Pbleached mixing plot of core and surface sediments. Group 2 sediments, which were distributed in the south of 36.5°N, also showed a two endmembers mixing relationship between materials from the Geum River and offshore materials, which had very different Pb concentrations and isotope ratios. Based on the isotopes and their concentrations in core and surface sediments, this mixing relationship was interpreted as materials from two geographically different origins being mixed, rather than anthropogenic or natural mixing of materials with the same origin. Therefore, the relative percentage of materials supplied from the Geum River was calculated using a two endmembers mixing model and estimated to be as much as about 50% at 35°N. The spatial distribution of materials derived from the Geum River represented that of fine

  19. Radioactivity distribution of thorium in sediment core of the Sabah-Sarawak coast

    International Nuclear Information System (INIS)

    Zal U'yun Wan Mahmood; Zaharudin Ahmad; Adziz, M.I.A.; Abdul Kadir Ishak; Che Abd Rahim Mohamed

    2010-01-01

    Thorium activity concentrations were measured in seven marine sediment cores taken from Sabah-Sarawak coast on 2004 by using a gravity box corer. Collected sediments were generally homogenous mud which contained much more mixture of silt and clay compared to sand and relatively low content of organic carbon (i.e. less than 5% at all sampling stations). The results found that activity concentrations of 230 Th, 232 Th and ratios of 230 Th/ 232 Th were ranged from 6.5-20.4 Bq/kg dry wt., 6.8-27.8 Bq/kg dry wt. and 0.69-0.92, respectively. It seem that, 232 Th activity concentrations are slightly higher than 230 Th at all sampling stations and both radionuclides were generally high at Sabah compared to Sarawak coastal waters. 230 Th activity concentrations in sediment core appear to be correlated with the activity concentrations of 232 Th at some sampling station. These indicating both radionuclides were supplied from the same of environment and source origin of detrital from terrestrial and shallower water. The low 230 Th/ 232 Th activity ratio which is less than unity suggesting that 232 Th was actively and rapidly regenerated compared to 230 Th from 234 U. It also can be attributed to less efficiently scavenge of 230 Th onto particles prior deposited at the marine sediment bed. (author)

  20. Historical Profiles of Polycyclic Aromatic Hydrocarbons (PAHs) in Marine Sediment Cores from Northwest Spain.

    Science.gov (United States)

    Pérez-Fernández, Begoña; Viñas, Lucía; Bargiela, Jesica

    2016-11-01

    The northwest coast of Spain is characterized by an irregular coastline rich in marine life and with the highest mussel production in Europe. Taking this into account, the characterization of the pollution levels and the sources involved appear necessary. Not only were parent Polycyclic Aromatic Hydrocarbons (PAHs) analysed but also their alkylated homologues. In total, 35 compounds were analyzed in 5 sediment cores. Sediments were collected using a box core dredge and extracted by (Pressurized Liquid Extraction) whilst the quantification of PAHs was performed using gas chromatography coupled to mass spectrometry (GC-MS). The total concentration detected varied from 49.6 to 2489 ng g -1 dry weight (d.w.) of which parent PAHs ranged from 44.5 to 2254 ng g -1 d.w. and alkylated PAHs varied from 5.04 to 317 ng g -1 d.w. Temporal and spatial evolution were outlined and pollution sources were identified along with a possible correlation between this pollution and local history and industry. Most of the PAHs from the superficial samples have a biomass and coal combustion profile, and some specific, localized events are reflected in the total PAH concentration evolution. Moreover, the study of the deepest layers of the sampled cores provides a baseline to develop background concentration values that will help in future sediment quality assessment.

  1. Characteristics of hydrocarbons in sediment core samples from the northern Okinawa Trough.

    Science.gov (United States)

    Huang, Xin; Chen, Shuai; Zeng, Zhigang; Pu, Xiaoqiang; Hou, Qinghua

    2017-02-15

    Sediment core samples from the northern Okinawa Trough (OT) were analyzed to determine abundances and distributions of hydrocarbons by gas chromatography-mass spectrometer (GC-MS). The results show that the n-alkanes in this sediment core conform to a bimodal distribution, and exhibit an odd-to-even predominance of high molecular weights compared to an even-to-odd predominance in low molecular weight n-alkanes with maxima at C 16 and C 18 . The concentrations of bitumen, alkanes and polyaromatic hydrocarbons (PAHs) were higher in samples S10-07 than all others. Three maturity parameters as well as the ratios between parent phenanthrenes (Ps) and methylphenanthrenes (MPs) in samples S10-07 and S10-17 were higher. The distribution and composition of hydrocarbons in sample S10-07 suggest that one, or several, undetected hydrothermal fields may be present in the region of this sediment core. Results also suggest that volcanism may be the main reason for the observed distribution and composition of hydrocarbons in S10-17 sample. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Collection, analysis, and age-dating of sediment cores from 56 U.S. lakes and reservoirs sampled by the U.S. Geological Survey, 1992-2001

    Science.gov (United States)

    Van Metre, Peter; Wilson, Jennifer T.; Fuller, Christopher C.; Callender, Edward; Mahler, Barbara J.

    2004-01-01

    The U.S. Geological Survey Reconstructed Trends National Synthesis study collected sediment cores from 56 lakes and reservoirs between 1992 and 2001 across the United States. Most of the sampling was conducted as part of the National Water-Quality Assessment (NAWQA) Program. The primary objective of the study was to determine trends in particle-associated contaminants in response to urbanization; 47 of the 56 lakes are in or near one of 20 U.S. cities. Sampling was done with gravity, piston, and box corers from boats and push cores from boats or by wading, depending on the depth of water and thickness of sediment being sampled. Chemical analyses included major and trace elements, organochlorine pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, cesium-137, and lead-210. Age-dating of the cores was done on the basis of radionuclide analyses and the position of the pre-reservoir land surface in the reservoir and, in a few cases, other chemical or lithologic depth-date markers. Dates were assigned in many cores on the basis of assumed constant mass accumulation between known depth-date markers. Dates assigned were supported using a variety of other date markers including first occurrence and peak concentrations of DDT and polychlorinated biphenyls and peak concentration of lead. A qualitative rating was assigned to each core on the basis of professional judgment to indicate the reliability of age assignments. A total of 122 cores were collected from the 56 lakes and age dates were assigned to 113 of them, representing 54 of the 56 lakes. Seventy-four of the 122 cores (61 percent) received a good rating for the assigned age dates, 28 cores (23 percent) a fair rating, and 11 cores (9 percent) a poor rating; nine cores (7 percent) had no dates assigned. An analysis of the influence of environmental factors on the apparent quality of age-dating of the cores concluded that the most important factor was the mass accumulation rate (MAR) of sediment: the

  3. The matter of preservation: A comparison of recent organic-walled dinoflagellate cyst assemblages in sediment trap and core top sediments off Cape Blanc (NW Africa)

    Science.gov (United States)

    Rüßbült, Annegret; Zonneveld, Karin A. F.; Pospelova, Vera

    2017-04-01

    During the last decades, organic-walled dinoflagellate cysts (dinocysts) have become a valuable tool for paleoenvironmental reconstructions. It is known that the sedimentary record depends on several factors like initial cyst production and preservation. Therefore it is necessary to know, to what extent the assemblage in the sediment reflects the primary signal produced in the water column. In this study, we compare undisturbed core top sediments with sediment trap data covering the same time intervals. Both, core and trap, were retrieved at a similar location off Cape Blanc (NW Africa) where high productivity of organic material takes place due to costal upwelling. The samples of trap CBi analyzed for dinocysts were collected over 5 years (2003-2008) and compared to assemblages found in 2 mm interval sections of core GeoB 14103-7. 210Pb dating revealed an age of 2.5 years per core sample, leading to a comparison of the upper 6 mm with CBi 1-5. The dinocyst species composition in core and trap sediments is similar. Both assemblages are dominated by heterotrophic species. However, while the most common species in the trap, Brigantidinium spp., makes up over 50% of each sample, it is less abundant in the core where it forms only 13% of the assemblage. Core samples are dominated by Protoperidinium monospinum with an average of 28%. This species is underrepresented in CBi with 3% abundance. Over time the proportions of the individual species show minor variations both in core and trap samples. We therefore assume that the strong differences in association composition are due to post-depositional processes altering the assemblages in the sediments like degradation or bioturbation rather than to changes in initial cyst production or differences in source areas of trap and sediment core.

  4. Sediment cores as archives of historical changes in floodplain lake hydrology.

    Science.gov (United States)

    Lintern, Anna; Leahy, Paul J; Zawadzki, Atun; Gadd, Patricia; Heijnis, Henk; Jacobsen, Geraldine; Connor, Simon; Deletic, Ana; McCarthy, David T

    2016-02-15

    Anthropogenic activities are contributing to the changing hydrology of rivers, often resulting in their degradation. Understanding the drivers and nature of these changes is critical for the design and implementation of effective mitigation strategies for these systems. However, this can be hindered by gaps in historical measured flow data. This study therefore aims to use sediment cores to identify historical hydrological changes within a river catchment. Sediment cores from two floodplain lakes (billabongs) in the urbanised Yarra River catchment (Melbourne, South-East Australia) were collected and high resolution images, trends in magnetic susceptibility and trends in elemental composition through the sedimentary records were obtained. These were used to infer historical changes in river hydrology to determine both average trends in hydrology (i.e., coarse temporal resolution) as well as discrete flood layers in the sediment cores (i.e., fine temporal resolution). Through the 20th century, both billabongs became increasingly disconnected from the river, as demonstrated by the decreasing trends in magnetic susceptibility, particle size and inorganic matter in the cores. Additionally the number of discrete flood layers decreased up the cores. These reconstructed trends correlate with measured flow records of the river through the 20th century, which validates the methodology that has been used in this study. Not only does this study provide evidence on how natural catchments can be affected by land-use intensification and urbanisation, but it also introduces a general analytical framework that could be applied to other river systems to assist in the design of hydrological management strategies. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Assessment of Cr pollution in tributary sediment cores in the Three Gorges Reservoir combining geochemical baseline and in situ DGT.

    Science.gov (United States)

    Gao, Bo; Gao, Li; Xu, Dongyu; Zhou, Yang; Lu, Jin

    2018-07-01

    The mobility and transfer of trace metals in sediments are vital to understanding trace metals environmental behavior in water environment. However, as a predominant aquatic carcinogen, an effective method for assessing the release and deposition for Cr at the sediment-water interface (SWI) is still not clearly understood. Here we established a comprehensive methodology to evaluate the release risk of Cr at the SWI combining regional geochemical baseline (RGB) and diffusive gradients in thin films (DGT). Sediment cores and water samples were collected in the two tributaries and mainstream of the Three Gorges Reservoir, which is the world's largest man-made hydroelectric station. Results showed that the calculated Cr carcinogenic risks in surface water did not exceed US EPA maximum recommended level. The RGB of Cr (85.53 ± 14.44 mg/kg) were calculated and the differentials between Cr concentration and RGB in surface sediments showed the average anthropogenic contribution rate was 6.03% and the upstream of Meixi River (MX-S) and mainstream were influenced by anthropogenic activities. The net diffusive flux using DGT showed that Cr in the midstream of Caotang River and MX had the potential to move upwards into the overlying water. Furthermore, combining the results of differential (Cr concentration vs. RGB) and the net flux, MX-S was the only site with a risk of Cr release. To the best of our knowledge, this study is the first attempt to combine RGB and DGT to scientifically assess metal release at SWI and provided a new perspective to comprehensively assess metal pollution in water environment. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Detection of Tephra Layers in Antarctic Sediment Cores with Hyperspectral Imaging

    Science.gov (United States)

    Aymerich, Ismael F.; Oliva, Marc; Giralt, Santiago; Martín-Herrero, Julio

    2016-01-01

    Tephrochronology uses recognizable volcanic ash layers (from airborne pyroclastic deposits, or tephras) in geological strata to set unique time references for paleoenvironmental events across wide geographic areas. This involves the detection of tephra layers which sometimes are not evident to the naked eye, including the so-called cryptotephras. Tests that are expensive, time-consuming, and/or destructive are often required. Destructive testing for tephra layers of cores from difficult regions, such as Antarctica, which are useful sources of other kinds of information beyond tephras, is always undesirable. Here we propose hyperspectral imaging of cores, Self-Organizing Map (SOM) clustering of the preprocessed spectral signatures, and spatial analysis of the classified images as a convenient, fast, non-destructive method for tephra detection. We test the method in five sediment cores from three Antarctic lakes, and show its potential for detection of tephras and cryptotephras. PMID:26815202

  7. Radiolarian zonation and volcanic ash layers in two Quaternary sediment cores from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, S.M.

    Radiolarian abundance in two Quaternary sediment cores, collected from the Central Indian Basin, was studied and Nigrini's (1971) and Goll's (1980) zones are recognised. New radiolarian zones Collosphaera orthoconus, Lamprocyrtis nigriniae...

  8. Mercury contamination history of an estuarine floodplain reconstructed from a 210Pb-dated sediment core (Berg River, South Africa)

    CSIR Research Space (South Africa)

    Kading, TJ

    2009-01-01

    Full Text Available Mercury deposition histories have been scarcely documented in the southern hemisphere. A sediment core was collected from the ecologically important estuarine floodplain of the Berg River (South Africa). The authors establish the concentration of Hg...

  9. Accumulation and partitioning of seven trace metals in mangroves and sediment cores from three estuarine wetlands of Hainan Island, China

    International Nuclear Information System (INIS)

    Qiu Yaowen; Yu Kefu; Zhang Gan; Wang Wenxiong

    2011-01-01

    Trace metals in mangrove tissues (leaf, branch, root and fruit) of nine species and sediments of ten cores collected in 2008 from Dongzhai Harbor, Sanya Bay and Yalong Bay, Hainan Island, were analyzed. The average concentrations of Cu, Pb, Zn, Cd, Cr, Hg and As in surface sediments were 14.8, 24.1, 57.9, 0.17, 29.6, 0.08 and 9.7 μg g -1 , whereas those in mangrove tissues were 2.8, 1.4, 8.7, 0.03, 1.1, 0.03, and 0.2 μg g -1 , respectively. Compared to those from other typical mangrove wetlands of the world, the metal levels in Hainan were at low- to median-levels, which is consistent with the fact that Hainan Island is still in low exploitation and its mangroves suffer little impact from human activities. Metal concentrations among different tissues of mangroves were different. In general, Zn and Cu were enriched in fruit, Hg was enriched in leaf, Pb, Cd and Cr were enriched in branch, and As was enriched in root. The cycle of trace metals in mangrove species were estimated. The biota-sediment accumulation factors (BSAFs) followed the sequence of Hg (0.43) > Cu (0.27) > Cd (0.22) > Zn (0.17) > Pb (0.07) > Cr (0.06) > As (0.02).

  10. Accumulation and partitioning of seven trace metals in mangroves and sediment cores from three estuarine wetlands of Hainan Island, China

    Energy Technology Data Exchange (ETDEWEB)

    Qiu Yaowen, E-mail: yqiu@scsio.ac.cn [State Key Laboratory of Tropic Marine Environment, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301 (China); Yu Kefu [State Key Laboratory of Tropic Marine Environment, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301 (China); Zhang Gan [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Wang Wenxiong [Section of Marine Ecology and Biotechnology, Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (Hong Kong)

    2011-06-15

    Trace metals in mangrove tissues (leaf, branch, root and fruit) of nine species and sediments of ten cores collected in 2008 from Dongzhai Harbor, Sanya Bay and Yalong Bay, Hainan Island, were analyzed. The average concentrations of Cu, Pb, Zn, Cd, Cr, Hg and As in surface sediments were 14.8, 24.1, 57.9, 0.17, 29.6, 0.08 and 9.7 {mu}g g{sup -1}, whereas those in mangrove tissues were 2.8, 1.4, 8.7, 0.03, 1.1, 0.03, and 0.2 {mu}g g{sup -1}, respectively. Compared to those from other typical mangrove wetlands of the world, the metal levels in Hainan were at low- to median-levels, which is consistent with the fact that Hainan Island is still in low exploitation and its mangroves suffer little impact from human activities. Metal concentrations among different tissues of mangroves were different. In general, Zn and Cu were enriched in fruit, Hg was enriched in leaf, Pb, Cd and Cr were enriched in branch, and As was enriched in root. The cycle of trace metals in mangrove species were estimated. The biota-sediment accumulation factors (BSAFs) followed the sequence of Hg (0.43) > Cu (0.27) > Cd (0.22) > Zn (0.17) > Pb (0.07) > Cr (0.06) > As (0.02).

  11. Temporal trends of heavy metals in sediment core from the gulf of Palermo (Sicily, Italy)

    International Nuclear Information System (INIS)

    Basilea, S.; Braia, M.; Span, M.; Tranchina, L.; Ceraulo, L.; Rizzo, S.

    2009-01-01

    The evaluation of long-term heavy metal concentrations in the Gulf of Palermo was carried out in this study. Measurements of Cr, Cu, Hg, Pb and Zn concentrations were performed by atomic absorption spectrophotometry (AAS) on dated fractions of a sediment core, dated by the 210 Pbex method. They are found to cover a time period from 1951 to 2004. The constant sedimentation rate model was used for dating. Specific activities of 137 Cs have also been measured in the sediment core sections as a check of the time scale derived by the 210 Pbex method. A time-series analysis based on temporal decomposition was used in order to investigate the presence of heavy metal pollution trend. The additive component model, widely used to estimate seasonal and long-term behavior, was chosen for the temporal analysis. Results showed the presence of a specific heavy metal concentration trend. Residual time-autocorrelation has also been taken into account in order to investigate their stochastic properties. Concentrations of some metals (Cu, Hg, and Zn) have been found increasing until the beginning of the 1970s. A peak around the beginning of the 1980s has been found for Cr and Pb. Heavy metal concentration in the sediment core show a significant decreasing after these years. Our results for the concentration time trends are in good agreement with other surveys performed in different areas of the world, and they can be explained in terms of the reduction of anthropogenic contribution to atmospheric emissions. Further investigations on time properties and spatial distributions, are also planned. (Author)

  12. Assessment of gamma-emitting radionuclides in sediment cores from the Gulf of Aqaba, Red Sea.

    Science.gov (United States)

    Ababneh, Zaid Q; Al-Omari, Husam; Rasheed, Mohamad; Al-Najjar, Tariq; Ababneh, Anas M

    2010-10-01

    The Gulf of Aqaba is the only seaport in Jordan which currently has intense activities such as industrial development, phosphate ore exportation, oil importation, shipping, commercial and sport fishing. Most of these activities, especially the phosphate ore exportation, could cause serious radiological effects to the marine environment. Thus, it is essential to investigate the level of the radioactivity concentrations to establish a baseline database, which is not available yet in the Gulf of Aqaba. Radioactivity concentrations of gamma-emitting radionuclides in core and beach sediments of the Gulf of Aqaba were investigated. Core sediments were collected from five representative locations for three different water column depths (5, 15 and 35 m). The results showed that the activity concentrations of 238U, 235U and 226Ra for both seafloor and beach sediments from the phosphate loading berth (PLB) location to be higher than those from other investigated locations and more than twice as high as the worldwide average; the 238U activity concentration was found to vary from 57 to 677 Bq kg(-1). The results also showed that there is little variation of radioactivity concentrations within the core length of 15 cm. The calculated mean values of the radium equivalent activity Ra(eq), the external hazard index, H(ex), the absorbed dose rate and the annual effective dose for the beach sediment in PLB location were 626 Bq kg(-1), 1.69, 263 nGy h(-1) and 614 µSv y(-1), respectively. These values are much higher than the recommended limits that impose potential health risks to the workers in this location. As for other studied locations, the corresponding values were far below the maximum recommended limit and lies within the worldwide range.

  13. Results of submerged sediment core sampling and analysis on Par Pond, Pond C, and L Lake: July 1995

    International Nuclear Information System (INIS)

    Koch, J.W. II; Martin, F.D.; Friday, G.P.

    1996-06-01

    Sediment cores from shallow and deep water locations in Par Pond, Pond C, and L Lake were collected and analyzed in 1995 for radioactive and nonradioactive constituents. This core analysis was conducted to develop a defensible characterization of contaminants found in the sediments of Par Pond, Pond C, and L Lake. Mercury was the only nonradiological constituent with a nonestimated quantity that was detected above the U.S Environmental Protection Agency Region IV potential contaminants of concern screening criteria. It was detected at a depth of 0.3--0.6 meters (1.0--2.0 feet) at one location in L Lake. Cesium-137, promethium-146, plutonium-238, and zirconium-95 had significantly higher concentrations in Par Pond sediments than in sediments from the reference sites. Cobalt-60, cesium-137, plutonium-238, plutonium-239/240, and strontium-90 had significantly higher concentrations in L-Lake sediments than sediments from the reference sites

  14. Origin of metallic surface core-level shifts

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Abrikosov, I. A.

    1995-01-01

    The unique property of the open 4f energy shell in the lanthanide metals is used to show that the initial-state energy shift gives an insufficient description of surface core-level shifts. Instead a treatment, which fully includes the final-state screening, account for the experimentally observed...

  15. Core-satellite supraparticles to ballistically stamp nanostructures on surfaces.

    Science.gov (United States)

    Oppmann, Maximilian; Miller, Franziska; Thürauf, Sandra; Groppe, Philipp; Prieschl, Johannes; Stauch, Claudia; Mandel, Karl

    2018-03-27

    Nanostructured surfaces are of great importance in a very wide range of fields. They can be obtained by imprint or deposition techniques. However, these are usually sophisticated to perform. Generally, it is not easy to equip an object/product with a nanostructure post manufacturing. Yet, it would be very beneficial to achieve a modification of an arbitrary surface with a nanostructure of choice at a later stage by an approach that is simple to perform without the need of sophisticated equipment or excessive treatment by physico-chemical methods. Herein, such a process is reported which combines two "old-fashioned" techniques, namely sandblasting and rubber-stamping, and translates them to the "nano-world". By creating core-satellite supraparticles via spray-drying, a ballistic core-satellite stamp particle system is obtained which can be used to easily transfer a wide range of nanoparticles to a great variety of surfaces to equip these with a nanostructure and subsequently advanced properties. These include water-repellant, anti-fouling or anti-dust surfaces. Moreover, it is also demonstrated that the approach can be used to manufacture well-defined nano-imprinted surfaces. Such surfaces showed an improved spreading behavior for aliphatic alcohols, thus rendering such surfaces for instance very susceptible for disinfectants. All in all, the simple technique described herein has a great potential for creating nanostructured surfaces on nearly any surface.

  16. Source, composition, and environmental implication of neutral carbohydrates in sediment cores of subtropical reservoirs, South China

    Science.gov (United States)

    Duan, Dandan; Zhang, Dainan; Yang, Yu; Wang, Jingfu; Chen, Jing'an; Ran, Yong

    2017-09-01

    Neutral monosaccharides, algal organic matter (AOM), and carbon stable isotope ratios in three sediment cores of various trophic reservoirs in South China were determined by high-performance anion-exchange chromatography, Rock-Eval pyrolysis, and Finnigan Delta Plus XL mass spectrometry, respectively. The carbon isotopic compositions were corrected for the Suess effect. The concentrations of total neutral carbohydrates (TCHO) range from 0.51 to 6.4 mg g-1 at mesotrophic reservoirs, and from 0.83 to 2.56 mg g-1 at an oligotrophic reservoir. Monosaccharide compositions and diagnostic parameters indicate a predominant contribution of phytoplankton in each of the three cores, which is consistent with the results inferred from the corrected carbon isotopic data and C/N ratios. The sedimentary neutral carbohydrates are likely to be structural polysaccharides and/or preserved in sediment minerals, which are resistant to degradation in the sediments. Moreover, the monosaccharide contents are highly related to the carbon isotopic data, algal productivity estimated from the hydrogen index, and increasing mean air temperature during the past 60 years. The nutrient input, however, is not a key factor affecting the primary productivity in the three reservoirs. The above evidence demonstrates that some of the resistant monosaccharides have been significantly elevated by climate change, even in low-latitude regions.

  17. Rare earth elements in core marine sediments of coastal East Malaysia by instrumental neutron activation analysis.

    Science.gov (United States)

    Ashraf, Ahmadreza; Saion, Elias; Gharibshahi, Elham; Mohamed Kamari, Halimah; Chee Kong, Yap; Suhaimi Hamzah, Mohd; Suhaimi Elias, Md

    2016-01-01

    A study was carried out on the concentration of REEs (Dy, Sm, Eu,Yb, Lu, La and Ce) that are present in the core marine sediments of East Malaysia from three locations at South China Sea and one location each at Sulu Sea and Sulawesi Sea. The sediment samples were collected at a depth of between 49 and 109 m, dried, and crushed to powdery form. The entire core sediments prepared for Instrumental Neutron Activation Analysis (INAA) were weighted approximately 0.0500 g to 0.1000 g for short irradiation and 0.1500 g to 0.2000 g for long irradiation. The samples were irradiated with a thermal neutron flux of 4.0×10(12) cm(-2) s(-1) in a TRIGA Mark II research reactor operated at 750 kW. Blank samples and standard reference materials SL-1 were also irradiated for calibration and quality control purposes. It was found that the concentration of REEs varies in the range from 0.11 to 36.84 mg/kg. The chondrite-normalized REEs for different stations suggest that all the REEs are from similar origins. There was no significant REEs contamination as the enrichment factors normalized for Fe fall in the range of 0.42-2.82. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Three-dimensional imaging of sediment cores: a multi-scale approach

    Science.gov (United States)

    Deprez, Maxim; Van Daele, Maarten; Boone, Marijn; Anselmetti, Flavio; Cnudde, Veerle

    2017-04-01

    Downscaling is a method used in building-material research, where several imaging methods are applied to obtain information on the petrological and petrophysical properties of materials from a centimetre to a sub-micrometre scale (De Boever et al., 2015). However, to reach better resolutions, the sample size is necessarily adjusted as well. If, for instance, X-ray micro computed tomography (µCT) is applied on the material, the resolution can increase as the sample size decreases. In sedimentological research, X-ray computed tomography (CT) is a commonly used technique (Cnudde & Boone, 2013). The ability to visualise materials with different X-ray attenuations reveals structures in sediment cores that cannot be seen with the bare eye. This results in discoveries of sedimentary structures that can lead to a reconstruction of parts of the depositional history in a sedimentary basin (Van Daele et al., 2014). Up to now, most of the CT data used for this kind of research are acquired with a medical CT scanner, of which the highest obtainable resolution is about 250 µm (Cnudde et al., 2006). As the size of most sediment grains is smaller than 250 µm, a lot of information, concerning sediment fabric, grain-size and shape, is not obtained when using medical CT. Therefore, downscaling could be a useful method in sedimentological research. After identifying a region of interest within the sediment core with medical CT, a subsample of several millimetres diameter can be taken and imaged with µCT, allowing images with a resolution of a few micrometres. The subsampling process, however, needs to be considered thoroughly. As the goal is to image the structure and fabric of the sediments, deformation of the sediments during subsampling should be avoided as much as possible. After acquiring the CT data, image processing and analysis are performed in order to retrieve shape and orientation parameters of single grains, mud clasts and organic material. This single-grain data can

  19. Resting stage in the biogenic fraction of surface sediments from the deep Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    Luigi della Tommasa

    2004-04-01

    Full Text Available The presence of resting stages in neritic areas is well known, while their occurrence in the deep sea realm has seldom been considered. Recent investigations showed strict interactions between neritic and deep sea domains, due to up- and down-welling phenomena driven by submarine canyons. To estimate the presence of resting stages in deep bottom sediments, seven sediment cores, collected along a trans-Mediterranean transect by means a multi-corer during the TRANSMED survey (1999, were studied. Most biogenic sediment was composed of Foraminifera tests (tens of thousand tests cm-3, Calciodinellum albatrosianum and Leonella granifera (Dinophyta cysts (up to thousands cysts cm-3. Eleven dinocyst morphotypes were recorded mainly as empty shells (seven calcareous-walled: C. albatrosianum, Calciperidinium asymmetricum, Leonella granifera, Scrippsiella trochoidea, S. precaria type 1, S. precaria type 2, S. regalis; four organic-walled: Impagidinium aculeatum, unid. dinocyst 1, unid. dinocyst 2 and unid. dinocyst 3, while no metazoan resting eggs were observed. The presence of viable resting stages in deep bottom surface sediments was much lower than in neritic areas, suggesting that oceanic species do not produce cysts for a "benthic resting" strategy. Further taxonomic and biogeographic studies are needed to better understand the ecological dynamics of oceanic plankton in the Mediterranean Sea.

  20. Micro and macro constituents of sediment cores from Itupararanga reservoir Sorocaba, SP, by INAA

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Sharlleny A.; Ferreira, Francisco J., E-mail: shasilva@sp.gov.br [Companhia Ambiental do Estado de Sao Paulo (ELAI/CETESB), SP (Brazil). Setor de Quimica Inorganica; Bevilacqua, Jose Eduardo [Companhia Ambiental do Estado de Sao Paulo (CETESB), Osasco, SP (Brazil). Diretoria de Avaliacao de Impacto Ambiental; Favaro, Deborah I.T., E-mail: defavaro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (LAN-CRPq/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Lab. de Analise por Ativacao Neutronica

    2013-07-01

    The Itupararanga reservoir was constructed by LIGHT for generating electrical energy, starting its operations in 1912. It is formed by the Sorocaba river dam. The reservoir finds itself in an area of strong environmental pressures. The waters of the Itupararanga reservoir are currently also used to supply approximately 63% of the basin of Sorocaba, in addition to power generation and recreation areas of nearby cities. Since 2003 it keeps receiving alerts from CETESB (Environmental Company of Sao Paulo State) that continues today. In this study four geo-referenced sampling points were used and bottom sediment samples were collected, were collected using a 60 cm core sampler, sliced at every 10 cm. The sediment samples were dried at 40 deg C, ground in an agate mortar, sieved (200 mesh) and again homogenized. Instrumental neutron activation analysis was applied to the sediment samples in order to determine some major elements (Fe, K and Na) and trace (As, Ba, Br, Co, Cr, Cs, Hf, Rb, Sb, Sc, Ta, Tb, Th, U and Zn) and rare earth (Ce, Eu, La, Lu, Nd, Sm, Tb and Yb) metals. The validation of the analytical methodology was performed by the analysis of certified reference materials. The results obtained were compared to NASC (North American Shale Composite) and UCC (Upper Continental Crust) reference values. The enrichment factors (EF) was assessed for sediment contamination index. Statistical tools of Factorial and Cluster analyses were applied to the data. (author)

  1. Sediment cores and chemistry for the Kootenai River White Sturgeon Habitat Restoration Project, Boundary County, Idaho

    Science.gov (United States)

    Barton, Gary J.; Weakland, Rhonda J.; Fosness, Ryan L.; Cox, Stephen E.; Williams, Marshall L.

    2012-01-01

    The Kootenai Tribe of Idaho, in cooperation with local, State, Federal, and Canadian agency co-managers and scientists, is assessing the feasibility of a Kootenai River habitat restoration project in Boundary County, Idaho. This project is oriented toward recovery of the endangered Kootenai River white sturgeon (Acipenser transmontanus) population, and simultaneously targets habitat-based recovery of other native river biota. Projects currently (2010) under consideration include modifying the channel and flood plain, installing in-stream structures, and creating wetlands to improve the physical and biological functions of the ecosystem. River restoration is a complex undertaking that requires a thorough understanding of the river. To assist in evaluating the feasibility of this endeavor, the U.S. Geological Survey collected and analyzed the physical and chemical nature of sediment cores collected at 24 locations in the river. Core depths ranged from 4.6 to 15.2 meters; 21 cores reached a depth of 15.2 meters. The sediment was screened for the presence of chemical constituents that could have harmful effects if released during restoration activities. The analysis shows that concentrations of harmful chemical constituents do not exceed guideline limits that were published by the U.S. Army Corps of Engineers in 2006.

  2. Hydrocarbon Degradation in Caspian Sea Sediment Cores Subjected to Simulated Petroleum Seepage in a Newly Designed Sediment-Oil-Flow-Through System

    Directory of Open Access Journals (Sweden)

    Tina Treude

    2017-04-01

    Full Text Available The microbial community response to petroleum seepage was investigated in a whole round sediment core (16 cm length collected nearby natural hydrocarbon seepage structures in the Caspian Sea, using a newly developed Sediment-Oil-Flow-Through (SOFT system. Distinct redox zones established and migrated vertically in the core during the 190 days-long simulated petroleum seepage. Methanogenic petroleum degradation was indicated by an increase in methane concentration from 8 μM in an untreated core compared to 2300 μM in the lower sulfate-free zone of the SOFT core at the end of the experiment, accompanied by a respective decrease in the δ13C signal of methane from -33.7 to -49.5‰. The involvement of methanogens in petroleum degradation was further confirmed by methane production in enrichment cultures from SOFT sediment after the addition of hexadecane, methylnapthalene, toluene, and ethylbenzene. Petroleum degradation coupled to sulfate reduction was indicated by the increase of integrated sulfate reduction rates from 2.8 SO42-m-2 day-1 in untreated cores to 5.7 mmol SO42-m-2 day-1 in the SOFT core at the end of the experiment, accompanied by a respective accumulation of sulfide from 30 to 447 μM. Volatile hydrocarbons (C2–C6 n-alkanes passed through the methanogenic zone mostly unchanged and were depleted within the sulfate-reducing zone. The amount of heavier n-alkanes (C10–C38 decreased step-wise toward the top of the sediment core and a preferential degradation of shorter (C30 was seen during the seepage. This study illustrates, to the best of our knowledge, for the first time the development of methanogenic petroleum degradation and the succession of benthic microbial processes during petroleum passage in a whole round sediment core.

  3. Hydrocarbon Degradation in Caspian Sea Sediment Cores Subjected to Simulated Petroleum Seepage in a Newly Designed Sediment-Oil-Flow-Through System

    Science.gov (United States)

    Mishra, Sonakshi; Wefers, Peggy; Schmidt, Mark; Knittel, Katrin; Krüger, Martin; Stagars, Marion H.; Treude, Tina

    2017-01-01

    The microbial community response to petroleum seepage was investigated in a whole round sediment core (16 cm length) collected nearby natural hydrocarbon seepage structures in the Caspian Sea, using a newly developed Sediment-Oil-Flow-Through (SOFT) system. Distinct redox zones established and migrated vertically in the core during the 190 days-long simulated petroleum seepage. Methanogenic petroleum degradation was indicated by an increase in methane concentration from 8 μM in an untreated core compared to 2300 μM in the lower sulfate-free zone of the SOFT core at the end of the experiment, accompanied by a respective decrease in the δ13C signal of methane from -33.7 to -49.5‰. The involvement of methanogens in petroleum degradation was further confirmed by methane production in enrichment cultures from SOFT sediment after the addition of hexadecane, methylnapthalene, toluene, and ethylbenzene. Petroleum degradation coupled to sulfate reduction was indicated by the increase of integrated sulfate reduction rates from 2.8 SO42-m-2 day-1 in untreated cores to 5.7 mmol SO42-m-2 day-1 in the SOFT core at the end of the experiment, accompanied by a respective accumulation of sulfide from 30 to 447 μM. Volatile hydrocarbons (C2–C6 n-alkanes) passed through the methanogenic zone mostly unchanged and were depleted within the sulfate-reducing zone. The amount of heavier n-alkanes (C10–C38) decreased step-wise toward the top of the sediment core and a preferential degradation of shorter (C30) was seen during the seepage. This study illustrates, to the best of our knowledge, for the first time the development of methanogenic petroleum degradation and the succession of benthic microbial processes during petroleum passage in a whole round sediment core. PMID:28503172

  4. The evolution of stenols and stanols in marine sediment core from Beibu Bay, the South China Sea

    Science.gov (United States)

    Jiang, Shanchun; Jia, Rongfen; Luan, Zuofeng

    1992-03-01

    Ten stenols and stanols were identified by TLC, GC and GC-MS-DS in a marine sediment core from Beibu Bay, the South China Sea. C27, C28 and C29 Δ5 stenols and 5α-stanols mainly come from zooplankton, algae and phytoplankton in marine environment. C29 24-ethylcholest-5-en-3β-ol is thought to indicate input of terrigenous organic matter. The increase of C27, C28 and C29 5α-stanol/Δ5 stenol ratios with sediment depth shows the evolution of stenols and stanols in the marine sediment core.

  5. Ab initio surface core-level shifts and surface segregation energies

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Johansson, Börje

    1993-01-01

    We have calculated the surface core-level energy shifts of the 4d and 5d transition metals by means of local-density theory and a Green’s-function technique based on the linear muffin-tin orbitals method. Final-state effects are included by treating the core-ionized atom as an impurity located...

  6. Core surface magnetic field evolution 2000–2010

    DEFF Research Database (Denmark)

    Finlay, Chris; Jackson, A.; Gillet, N.

    2012-01-01

    We present new dedicated core surface field models spanning the decade from 2000.0 to 2010.0. These models, called gufm‐sat, are based on CHAMP, Ørsted and SAC‐C satellite observations along with annual differences of processed observatory monthly means. A spatial parametrization of spherical...... field and the unrealistic rapid decay typical of quadratic regularization at degrees above 12. We describe in detail aspects of the models that are relevant to core dynamics. Secular variation and secular acceleration are found to be of lower amplitude under the Pacific hemisphere where the core field...... is weaker. Rapid field evolution is observed under the eastern Indian Ocean associated with the growth and drift of an intense low latitude flux patch. We also find that the present axial dipole decay arises from a combination of subtle changes in the southern hemisphere field morphology....

  7. Chemical gradients in sediment cores from an EPA reference site off the Farallon Islands - Assessing chemical indicators of dredged material disposal in the deep sea

    Science.gov (United States)

    Bothner, Michael H.; Gill, P.W.; Boothman, W.S.; Taylor, B.B.; Karl, Herman A.

    1998-01-01

    Heavy metal and organic contaminants have been determined in undisturbed sediment cores from the US Environmental Protection Agency reference site for dredged material on the continental slope off San Francisco. As expected, the concentrations are significantly lower than toxic effects guidelines, but concentrations of PCBs, PAHs, Hg, Pb, and Clostridium perfringens (a bacterium spore found in sewage) were nearly two or more times greater in the surface sediments than in intervals deeper in the cores. These observations indicate the usefulness of measuring concentration gradients in sediments at the San Francisco deep ocean disposal site (SF-DODS) where a thin (0.5 cm thick) layer of dredged material has been observed beyond the boundary. This thin layer has not been chemically characterized by the common practice of homogenizing over the top 10 cm. An estimated 300 million cubic yards of dredged material from San Francisco Bay are expected to be discharged at the SF-DODS site during the next 50 years. Detailed depth analysis of sediment cores would add significant new information about the fate and effects of dredged material in the deep sea.

  8. Environmental magnetic and petroleum hydrocarbons records in sediment cores from the north east coast of Tamilnadu, Bay of Bengal, India.

    Science.gov (United States)

    Venkatachalapathy, R; Veerasingam, S; Basavaiah, N; Ramkumar, T; Deenadayalan, K

    2011-04-01

    In this study, mineral magnetic properties and petroleum hydrocarbons were statistically analysed in four sediment cores (C1, A1, T1 and K1) from the north east coast of Tamilnadu, India to examine the feasibility of PHC concentrations assessment using magnetic susceptibility. The C1 and A1 cores reveal a clear horizon of increase in PHC above 35 and 50 cm respectively suggesting the excess anthropogenic loading occurred in the recent past. Magnetic properties which were enhanced in the upper part of the sediment cores were the result of ferrimagnetic minerals from anthropogenic sources. Factor analysis confirmed that the input of magnetic minerals and petroleum hydrocarbons in Chennai coastal sediments are derived from the same sources. The present study shows that instead of expensive and destructive PHC chemical methods, magnetic susceptibility is found to be a suitable, cheap and rapid method for detailed study of petroleum hydrocarbon contamination in marine sediments. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Sediment cores from kettle holes in NE Germany reveal recent impacts of agriculture.

    Science.gov (United States)

    Kleeberg, Andreas; Neyen, Marielle; Schkade, Uwe-Karsten; Kalettka, Thomas; Lischeid, Gunnar

    2016-04-01

    Glacial kettle holes in young moraine regions receive abundant terrigenous material from their closed catchments. Core chronology and sediment accumulation were determined for two semi-permanent kettle holes, designated RG and KR, on arable land close to the villages of Rittgarten and Kraatz, respectively, in Uckermark, NE Germany. Core dating ((210)Pb, (137)Cs) revealed variable sediment accretion rates through time (RG 0.4-23.1 mm a(-1); KR 0.2-35.5 mm a(-1)), with periods of high accumulation corresponding to periods of intensive agricultural activity and consequent erosional inputs from catchments. Sediment composition (C, N, P, S, K, Ca, Fe, Mn, Zn, Cu, Mo, Pb, Cd, Zr) was used to determine sediment source and input processes. At RG, annual P input increased from 0.65 kg ha(-1) in the early nineteenth century to 1.67 kg ha(-1) by 2013. At KR, P input increased from 0.6 to 4.1 kg ha(-1) over the last century. There was a concurrent increase in Fe input in both water bodies. Thus, Fe/P ratios showed no temporal trend and did not differ between RG (18.5) and KR (18.4), indicating similar P mobility. At RG, the S/Fe ratio increased from 0.4 to 2.3, indicating more iron sulphides and thus higher P availability, coinciding with high coverage of duckweed (Spirodela polyrhiza (L.)) and soft hornwort (Ceratophyllum submersum L.). At KR, however, this ratio remained low and relatively unchanged (0.3 ± 0.4), indicating more efficient Fe-P binding and lower hydrophyte productivity. Trends in sediment composition indicate a shift towards eutrophication in both kettle holes, but with differences in timing and magnitude. Other morphologically similar kettle holes in NE Germany that are prone to erosion could have been similarly impacted but may differ in the extent of sediment infilling and degradation of their ecological functions.

  10. Tracking the Transformation and Preservation of Organic Biomarkers in a Varved Sediment-Core Series

    Science.gov (United States)

    Tolu, J.; Bigler, C.; Bindler, R.

    2014-12-01

    An important premise for reconstructing environmental changes using sediment records is to understand which environmental information reaches the lake bottom and how diagenetic processes may affect the proxies, such as terrestrial and aquatic organic biomarkers. We can tackle this question using a unique series of varved sediment cores collected from the lake Nylandssjön (northern Sweden). In addition to limnological and sediment trap sampling since 2001, we have a collection of freeze cores taken in late winter and stored since 1979, which allows us to track individual varve years (e.g., 1978) over time (~30 years). A previous study using this collection showed that 23 % of C and 35 % of N were lost during the first 25 years with a C:N ratio increase of ≈21, suggesting important implications for diagenetic effects on organic biomarkers. To assess the preservation/transformation of organic biomarkers, we developed a new Pyrolysis-Gas Chromatography/Mass Spectrometry method that allows the rapid determination of biomarkers from the common OM classes (e.g., plant waxes, microbial lipids, lignins) using sub-mg sample sizes and thus applicable to high-resolution sampling of the varved sediment (Tolu et al., under review). Our results show that the different biomarkers exhibit a broad spectrum of reactivities over ~30 years -% change determined by ([Peak area at t] - [Peak area at t=0])/ [peak area at t=0] x 100-. For example: 67-80 % of the algal chlorophyll-derived product 'phytene' is lost depending which single varve year is followed over time (e.g., 1979). Only 12-32 % of "pristene", the degraded form of algal chlorophyll, is lost. The guaiacyl and syringyl lignin units are affected by a smaller loss, i.e. 5-15 %, and the S/G ratio, indicative of angiosperm/gymnosperm plant input remains stable, which is contrary to previous work on non-varved lake sediments. Considering all biomarkers, the degradation/production plateaued after ~15 years, which indicates that

  11. Characterization of Vadose Zone Sediment: Uncontaminated RCRA Borehole Core Samples and Composite Samples

    International Nuclear Information System (INIS)

    Serne, R. Jeffrey; Bjornstad, Bruce N.; Schaef, Herbert T.; Williams, Bruce A.; Lanigan, David C.; Horton, Duane G.; Clayton, Ray E.; Mitroshkov, Alexandre V.; Legore, Virginia L.; O'Hara, Matthew J.; Brown, Christopher F.; Parker, Kent E.; Kutnyakov, Igor V.; Serne, Jennifer N.; Last, George V.; Smith, Steven C.; Lindenmeier, Clark W.; Zachara, John M.; Burke, Deborah Sd.

    2001-01-01

    The overall goal of the of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities. To meet this goal, CH2M HILL Hanford Group, Inc. asked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediment from within the S-SX Waste Management Area. This report is the first in a series of four reports to present the results of these analyses. Specifically, this report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from RCRA borehole bore samples and composite samples. Intact cores from two RCRA boreholes (299-W22-48 and 299-W22-50) near the SX Tank Farm and four, large-quantity grab samples from outcrop sediment on and off the Hanford Site were sampled to better understand the fate of contaminants in the vadose zone beneath underground storage tanks at the Hanford Site. Borehole and outcrop samples analyzed for this report are located outside the tank farms, and therefore may be considered standard or background samples from which to compare contaminated sediments within the tank farms themselves. This report presents our interpretation of the physical, chemical, and mineralogical properties of the uncontaminated vadose zone sediments, and variations in the vertical distribution of these properties. The information presented in this report is intended to support preparation of the S-SX Field Investigation Report to be prepared by CH2M Hill Hanford Group, Inc. as well as future remediation actions at the S-SX Tank Farm

  12. Microbial methanogenesis in the sulfate-reducing zone of surface sediments traversing the Peruvian margin

    Science.gov (United States)

    Maltby, J.; Sommer, S.; Dale, A. W.; Treude, T.

    2016-01-01

    We studied the concurrence of methanogenesis and sulfate reduction in surface sediments (0-25 cm below sea floor) at six stations (70, 145, 253, 407, 990 and 1024 m) along the Peruvian margin (12° S). This oceanographic region is characterized by high carbon export to the seafloor creating an extensive oxygen minimum zone (OMZ) on the shelf, both factors that could favor surface methanogenesis. Sediments sampled along the depth transect traversed areas of anoxic and oxic conditions in the bottom-near water. Net methane production (batch incubations) and sulfate reduction (35S-sulfate radiotracer incubation) were determined in the upper 0-25 cm b.s.f. of multiple cores from all stations, while deep hydrogenotrophic methanogenesis (> 30 cm b.s.f., 14C-bicarbonate radiotracer incubation) was determined in two gravity cores at selected sites (78 and 407 m). Furthermore, stimulation (methanol addition) and inhibition (molybdate addition) experiments were carried out to investigate the relationship between sulfate reduction and methanogenesis.Highest rates of methanogenesis and sulfate reduction in the surface sediments, integrated over 0-25 cm b.s.f., were observed on the shelf (70-253 m, 0.06-0.1 and 0.5-4.7 mmol m-2 d-1, respectively), while lowest rates were discovered at the deepest site (1024 m, 0.03 and 0.2 mmol m-2 d-1, respectively). The addition of methanol resulted in significantly higher surface methanogenesis activity, suggesting that the process was mostly based on non-competitive substrates - i.e., substrates not used by sulfate reducers. In the deeper sediment horizons, where competition was probably relieved due to the decrease of sulfate, the usage of competitive substrates was confirmed by the detection of hydrogenotrophic activity in the sulfate-depleted zone at the shallow shelf station (70 m).Surface methanogenesis appeared to be correlated to the availability of labile organic matter (C / N ratio) and organic carbon degradation (DIC production

  13. Extractable organics in surface sediments from Thana creek and Bombay harbour

    Digital Repository Service at National Institute of Oceanography (India)

    Rokade, M.A.; Bhosle, N.B.; Kadam, A.N.

    Considerable variations in hydrocarbon and fatty acid levels in surface sediments from Thana creek and Bombay harbour were observed Sediments from the westernside nearshore locations yielded higher values The residues were characterised by infrared...

  14. The use of XRF core scanner technique to identify anthropogenic chronological markers for dating recent sediments and for mapping and estimating the quantity of contaminated sediments in different fjord settings in western Norway

    Science.gov (United States)

    Haflidason, H.; Thorsen, L.; Soldal, O. L.

    2016-12-01

    Following the initiation of the industrial revolution in Norway at the early 1900´s many of the heavy industrial factories established at that time were located in inner fjord systems of western Norway. The advantage was an easy access to cheap electricity, but the main disadvantage has been that the pollution from this industrial activity has been transported into fjord systems where the circulation of the water masses has been fairly limited leading to a high concentration of heavy metals in the fjord basin sediments. The recently developed non-destructive X-ray Fluorescence (XRF) core scanning technique offers new possibilities to obtain near-continuous records of bulk element composition in marine records. This new analytical geochemical method can measure the bulk element content directly from the surface sediment archives within a period of seconds and with a resolution up to 200 microns. By applying this method on rapidly deposited sediments one can reconstruct a continuous record of carbonate content on a sub-decadal to annual scale. This kind of high-resolution records can also be compared directly with historical and instrumental records from the same area. This offers new possibilities to identify in an effective way the geochemical anomalies in the sediment column and estimate the variability of the industrially produced elements as e.g. Cu, Zn and Pb and their distribution and thickness/quantity in fjord basin sediments. Examples will be presented demonstrating the close linkage between the industrial production history and the entrance of these elements in the fjord sediments. Identification of these elements offers an excellent opportunity to date the recent marine sediments using these elements as an event spike and also to reconstruct the history of pollution in these fjord basin sediments. As the precision of the XRF element detection is high the time of full recovery to natural conditions of the basin sediments, after close down of these

  15. Molecular Characterization of Methanogenic Communities in Core Sediments of the Dajiuhu Peatland, Central China

    Science.gov (United States)

    Wang, R.; Wang, H.

    2017-12-01

    Methane (CH4) is an important greenhouse gas with a global warming potential 22 times greater than carbon dioxide. Large amounts of CH4 can be produced and released by methanogenesis in peatland ecosystems, which make peatland ecosystems play an important role in mediating global climate change. Here we report the abundance and distribution of methanogenic communities and their correlation with physicochemical parameters along two sediment cores in the Dajiuhu Peatland via quantitative PCR, clone library construction of functional genes and statistical analysis. Uncultured Group and Fen Cluster were found to be the dominant methanogens at the upper part of the cores, and Rice and Related Rice Cluster became dominant in the bottom of the cores. Quantitative PCR showed that abundances of methanogenic communities ranged from 104 to 106 copies/ng DNA throughout the cores. Canonical Correlation Analysis (CCA) indicated that dissolved oxygen (DO) (P=0.046, F=1.4) was the main factor significantly controlling methanogenic communities. Our results enhance the understanding of the compositions and variations of methanogenic communities vertically and greatly help us to further investigate process of microbial methanogenesis in Dajiuhu Peatland.

  16. An Ocean Sediment Core-Top Calibration of Foraminiferal (Cibicides) Stable Carbon Isotope Ratios

    Science.gov (United States)

    Schmittner, A.; Mix, A. C.; Lisiecki, L. E.; Peterson, C.; Mackensen, A.; Cartapanis, O. A.

    2015-12-01

    Stable carbon isotope ratios (δ13C) measured on calcium carbonate shells of benthic foraminifera (cibicides) from late Holocene sediments (δ13CCib) are compiled and compared with newly updated datasets of contemporary water-column δ13C observations of dissolved inorganic carbon (δ13CDIC) as the initial core-top calibration of the international Ocean Circulation and CarbonCycling (OC3) project. Using selection criteria based on the spatial distance between samples we find high correlation between δ13CCib and natural (pre-industrial) δ13CDIC, confirming earlier work. However, our analysis reveals systematic differences such as higher (lower) δ13CCib values in the Atlantic (Indian and Pacific) oceans. Regression analyses are impacted by anthropogenic carbon and suggest significant carbonate ion, temperature, and pressure effects, consistent with lab experiments with planktonic foraminifera and theory. The estimated standard error of core-top sediment data is generally σ ~= 0.25 ‰, whereas modern foram data from the South Atlantic indicate larger errors (σ ~= 0.4 ‰).

  17. Submerged terrestrial landscapes in the Baltic Sea: Evidence from multiproxy analyses of sediment cores from Fehmarnbelt

    Science.gov (United States)

    Enters, Dirk; Wolters, Steffen; Blume, Katharina; Segschneider, Martin; Lücke, Andreas; Theuerkauf, Martin; Hübener, Thomas

    2016-04-01

    Five sediment cores were taken from the southern part of the Fehmarn Belt (Baltic Sea) in the context of an environmental impact study for the intended fixed traverse between Germany and Denmark. The lithologies of the 8m long cores reveal dramatic changes in sedimentary environments which reflect the early Holocene history of the southern Baltic Sea. A succession of terrestrial, semiterrestrial and limnic facies from glacial sediments to peat, lacustrine/estuarine deposits and finally marine sediments document the interplay of eustatic sea level rise and isostatic rebound, which finally lead to the establishment of marine conditions during the Littorina transgression. An age control of the observed changes was established by dating over 50 C-14 samples of different fractions. During the Lateglacial minerogenic varves with thicknesses of several centimeters verify the existence of a proglacial lake in the Fehmarnbelt. Peat development started around 11.250 cal. BP and terminated ca. 10.600 cal. BP which is roughly contemporaneous with the end of the Yoldia Phase in the central Baltic Sea. The oldest peat layers consist of undecomposed sedges and reed. Woody remains of willows appear not before 10.700 cal BP and indicate a stagnant or slowly decreasing water table. This semi-terrestrial phase is followed by a shallow inland lake which existed until the Littorina transgression around 8.300 cal. BP. Initially the lacustrine sediments exhibit high C/N ratios, low low δ13Corg values and contain numerous wood fragments as well as other botanical macro remains. This indicates shallow conditions close to the lake shore. Later, the occurrence of planktonic diatom species such as Aulacoseira ambigua suggest greater water depths. We did not find any indications of the often postulated catastrophic outburst of the Ancylus Lake via Fehmarnbelt and the Great Belt into the North Sea. Likewise, XRF scanning does not show conspicuous peaks in Ti or K which would have been

  18. Variation of 210Po and 210Pb Profile in the Sediment Core of Sarawak Coastal Waters

    International Nuclear Information System (INIS)

    Zal U'yun Wan Mahmood; Che Abd Rahim Mohamed; Zaharudin Ahmad; Abdul Kadir Ishak

    2008-01-01

    This study was performed to observe the variation in the distribution of 210 Po and 210 Pb through their activity vertical profile and 210 Po/ 210 Pb activity ratio in the sediment cores that were taken at some sampling stations in the Sarawak coastal waters. It was found that the distribution profile of those radionuclide in the sediment cores varied depending on the sampling location and ANOVA analysis shows significant difference at 95% confidence level for activities of 210 Po (p = 0.000), 210 Pb (p = 0.035) and 210 Po/ 210 Pb (p = 0.000) at all study locations. Generally, the measured activity of 210 Po and 210 Pb ranged from 337 to 2460 Bq/ kg, 11 to 84 Bq/ kg at SR 01; 224 to 2008 Bq/ kg, 6 to 80 Bq/ kg at SR 02; 119 to 1595 Bq/ kg, 6 to 84 Bq/ kg at SR 03; 241 to 2294 Bq/ kg, 5 to 82 Bq/ kg at SR 04 and 175 to 1340 Bq/ kg, 4 to 44 Bq/ kg at SR 05, respectively. In those range it was found that 210 Po activities were higher than 210 Pb with average of 210 Po/ 210 Pb ratios at all stations were from 20 to 35. The variation in the distribution profile for the radionuclides are believed to be influenced by some environmental factors and have strong correlation between the radionuclide distribution and the sediment composition of silt ( 210 Po: r = 0.701 and 210 Pb: r = 0.648), water depth ( 210 Po: r = -0.647) and the distance from the sampling station to the main land ( 210 Po: r = 0.746 and 210 Pb: r = 0.975). Those factors are a major contributions on the variation of 210 Po and 210 Pb in the samples. (author)

  19. Response of core microbial consortia to hydrocarbon contaminations in coastal sediment habitats

    Directory of Open Access Journals (Sweden)

    Mathilde Jeanbille

    2016-10-01

    Full Text Available Traditionally, microbial surveys investigating the effect of chronic anthropogenic pressure such as polyaromatic hydrocarbons (PAHs contaminations consider just the alpha and beta diversity and ignore the interactions among the different taxa forming the microbial community. Here, we investigated the ecological relationships between the three domains of life (i.e. Bacteria, Archaea and Eukarya using 454 pyrosequencing data of the 16S rRNA and 18S rRNA genes from chronically impacted and pristine sediments, along the coasts of the Mediterranean Sea (Gulf of Lion, Vermillion coast, Corsica, Bizerte lagoon and Lebanon and the French Atlantic Ocean (Bay of Biscay and English Channel. Our approach provided a robust ecological framework for the partition of the taxa abundance distribution into 859 core OTUs and 6629 satellite OTUs. OTUs forming the core microbial community showed the highest sensitivity to changes in environmental and contaminant variations, with salinity, latitude, temperature, particle size distribution, total organic carbon (TOC and PAH concentrations as main drivers of community assembly. The core communities were dominated by Gammaproteobacteria and Deltaproteobacteria for Bacteria, by Thaumarchaeota, Bathyarchaeota and Thermoplasmata for Archaea and Metazoa and Dinoflagellata for Eukarya. In order to find associations among microorganisms, we generated a co-occurrence network in which PAHs were found to impact significantly the potential predator – prey relationship in one microbial consortium composed of ciliates and Actinobacteria. Comparison of network topological properties between contaminated and non-contaminated samples showed substantial differences in the structure of the network and indicated a higher vulnerability to environmental perturbations in the contaminated sediments.

  20. δ13C and δ15N values of sediment-trap particles in the Japan and Yamato Basins and comparison with the core-top values in the East/Japan Sea

    Science.gov (United States)

    Khim, Boo-Keun; Otosaka, Shigeyoshi; Park, Kyung-Ae; Noriki, Shinichiro

    2018-01-01

    Investigation of sediment-trap deployments in the East/Japan Sea (EJS) showed that distinct seasonal variations in particulate organic carbon (POC) fluxes of intermediate-water sediment-traps clearly corresponded to changes in chlorophyll a concentrations estimated from SeaWiFS data. The prominent high POC flux periods (e.g., March) were strongly correlated with the enhanced surface-water phytoplankton blooms. Deep-water sedimenttraps exhibited similar variation patterns to intermediate-water sediment-traps. However, their total flux and POC flux were higher than those of intermediate-water sediment-traps during some months (e.g., April and May), indicating the lateral delivery of some particles to the deep-water sediment-traps. Distinct seasonal δ13C and δ15N variations in settling particles of the intermediate-water sediment-traps were observed, strongly supporting the notion of seasonal primary production. Seasonal variations in δ13C and δ15N values from the deep-water sediment-traps were similar to those of the intermediate-water sediment-traps. However, the difference in δ13C and δ15N values between the intermediate-water and the deepwater sediment-traps may be attributed to degradation of organic matter as it sank through the water column. Comparison of fluxweighted δ13C and δ15N mean values between the deep-water sediment-traps and the core-top sediments showed that strong selective loss of organic matter components (lipids) depleted in 13C and 15N occurred during sediment burial. Nonetheless, the results of our study indicate that particles in the deep-water sediment-trap deposited as surface sediments on the seafloor preserve the record of surface-water conditions, highlighting the usefulness of sedimentary δ13C and δ15N values as a paleoceanographic application in the EJS.

  1. Distribution of tetraether lipids in surface sediments of the northern South China Sea: Implications for TEX86 proxies

    Directory of Open Access Journals (Sweden)

    Huangmin Ge

    2013-03-01

    Full Text Available Archaea have unique glycerol dialkyl glycerol tetraether (GDGT lipids that can be used to develop paleotemperature proxies such as TEX86. This research is to validate proposed GDGT-proxies for paleotemperature determination in the South China Sea (SCS. Samples were collected from core-top sediments (0–5 cm in the northern SCS. Total lipids were extracted to obtain core GDGTs, which were identified and quantified using liquid chromatography-mass spectrometry (LC-MS. The abundance of isoprenoidal GDGTs (iGDGTs ranged from 271.5 ng/g dry sediment to 1266.3 ng/g dry sediment, whereas the branched GDGTs (bGDGTs, supposedly derived from terrestrial sources, ranged from 22.2 ng/g dry sediment to 56.7 ng/g dry sediment. The TEX86-derived sea surface temperatures ranged from 20.9 °C in the coast (water depth  1000 m. TEX86-derived temperatures near shore (<160 m water depth averaged 23.1 ± 2.5 °C (n = 4, which were close to the satellite-derived winter mean sea surface temperature (average 22.6 ± 1.0 °C, n = 4; whereas the TEX86-derived temperatures offshore averaged 27.4 ± 0.3 °C (n = 7 and were consistent with the satellite mean annual sea surface temperature (average 26.8 ± 0.4 °C, n = 7. These results suggest that TEX86 may record the sea surface mean annual temperature in the open ocean, while it likely records winter sea surface temperature in the shallower water.

  2. 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.

  3. 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

  4. Soft-sediment deformation structures in cores from lacustrine slurry deposits of the Late Triassic Yanchang Fm. (central China

    Directory of Open Access Journals (Sweden)

    Yang Renchao

    2016-09-01

    Full Text Available The fine-grained autochthonous sedimentation in the deep part of a Late Triassic lake was frequently interrupted by gravity-induced mass flows. Some of these mass flows were so rich in water that they must have represented slurries. This can be deduced from the soft-sediment deformation structures that abound in cores from these lacustrine deposits which constitute the Yanchang Fm., which is present in the Ordos Basin (central China.

  5. 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.

    component and used in PCA and factor analyses. Factor analyses help to understand the relationships among metals and differentiate metals contributed from different sources and groups of metals (different factors) that behaved similarly in a particular... from the core in the lower estuary deposited prior to the beginning of mining activity of Fe-Mn ores in Goa. The concentration of metals in the reference sediment is the average concentration of metals in sediments at 5 intervals at depths between 20...

  6. Reconstruction of paleostorm history using geochemical proxies in sediment cores from Eastern Lake, Florida

    Science.gov (United States)

    Das, O.; Wang, Y.; Donoghue, J. F.; Coor, J. L.; Kish, S.; Elsner, J.; Hu, X. B.; Niedoroda, A. W.; Ye, M.; Xu, Y.

    2009-12-01

    Analysis of geochemical proxies of coastal lake sediments provides a useful tool for reconstructing paleostorm history. Such paleostorm records can help constrain models that are used to predict future storm events. In this study, we collected two sediment cores (60 and 103 cm long, respectively) from the center of Eastern Lake located on the Gulf coast of NW Florida. These cores, which are mainly composed of organic-rich mud and organic-poor sand, were sub-sampled at 2-3mm intervals for analyses of their organic carbon and nitrogen concentrations as well as δ13C and δ15N isotopic signatures. Selected samples were submitted for radiocarbon dating in order to establish a chronological framework for the interpretation of the geochemical data. There are significant variations in δ13C, δ15N, C%, N% and C/N with depth. The δ13C and δ15N values vary from -21.8‰ to -26.7‰ and 2.6‰ to 5‰, respectively. The stable isotopic signatures of carbon and nitrogen indicate that the sources of organic matter in sediments include terrestrial C3 type vegetation, marine input from Gulf of Mexico and biological productivity within the lake, such as phytoplankton and zooplankton growing in the lacustrine environment. The δ13C and δ15N values exhibit significant negative excursions by 2‰ in a 30 cm thick sand layer, bounded by a rapid return to the base value. A positive shift in the δ15N record observed in the upper part of the cores likely reflects increased anthropogenic input of N such as sewage or septic tank effluents associated with recent development of areas around the lake for human habitation. Similarly, organic C% and N% range from 5.8 to 0.4 and 0.4 to 0.1, respectively. A prominent negative shift by 2σ relative to the baseline in C% and N% has been observed at approx. 55 to 58 cm depth, consisting of an organic-poor sand layer. This shift in C% and N% can be correlated with the negative shift in the δ13C and δ15N values, indicating a major storm event

  7. Surface core-level shifts for simple metals

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Johansson, Börje

    1994-01-01

    We have performed an ab initio study of the surface core-level binding energy shift (SCLS) for 11 of the simple metals by means of a Green’s-function technique within the tight-binding linear-muffin-tin-orbitals method. Initial- and final-state effects are included within the concept of complete....... We furthermore conclude that the unexpected negative sign of the SCLS in beryllium is predominantly an initial-state effect and is caused by the high electron density in this metal....

  8. 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

  9. Determination of 210Pb in marine sediment core- A comparison between alpha and gamma techniques

    International Nuclear Information System (INIS)

    Zal Uyun Wan Mahmood; Yii Mei Wo; Zaharudin Ahmad

    2010-01-01

    The most commonly used techniques of alpha and gamma spectrometry were performed to measure 210 Pb activity in marine sediment core as a comparison. Alpha analytical technique measured the activity of 210 Pb from its in-grow grand-daughter 210 Po after a chemical separation, assuming radioactive equilibrium between the two radionuclides. Meanwhile, gamma analysis technique allows direct measurement, non-destructive and no preliminary chemical separation. Through the comparison, it is found that both alpha and gamma analysis techniques were slightly difference. Overall, the results from alpha analytical technique were basically higher than those from the gamma analytical techniques. Some logical argument had been discussed to explain this situation. In routine analysis, the analytical technique used should be chosen carefully based on advantages and disadvantages of the each technique and analysis requirements. Therefore, it is recommended to determine exactly the needs and purpose of analysis and to know the sample history before decide the appropriate analytical technique. (author)

  10. Synthesis of Au@Ag core-shell nanocubes containing varying shaped cores and their localized surface plasmon resonances.

    Science.gov (United States)

    Gong, Jianxiao; Zhou, Fei; Li, Zhiyuan; Tang, Zhiyong

    2012-06-19

    We have synthesized Au@Ag core-shell nanocubes containing Au cores with varying shapes and sizes through modified seed-mediated methods. Bromide ions are found to be crucial in the epitaxial growth of Ag atoms onto Au cores and in the formation of the shell's cubic shape. The Au@Ag core-shell nanocubes exhibit very abundant and distinct localized surface plasmon resonance (LSPR) properties, which are core-shape and size-dependent. With the help of theoretical calculation, the physical origin and the resonance mode profile of each LSPR peak are identified and studied. The core-shell nanocrystals with varying shaped cores offer a new rich category for LSPR control through the plasmonic coupling effect between core and shell materials.

  11. The distribution of gamma-emitting radionuclides in surface subtidal sediments near the Sellafield plant

    Science.gov (United States)

    Jones, D. G.; Roberts, P. D.; Miller, J. M.

    1988-08-01

    Detailed distributions of total gamma activity, 137Cs, 106Ru and 95Zr + 95Nb in surface seabed sediments near the Sellafield plant are presented. The results are derived from a towed seabed gamma-ray spectrometer survey in September, 1982. All the distributions are similar, with contours of equal activity parallel to the coast defining a 'ridge' of higher activity which is displaced northwards relative to the outfall. This pattern appears to be largely a response to the transport of particle-associated radioeffluent modified in places by the type of seabed sediment present. At greater distance from Sellafield, the uptake of nuclides from solution seems to be more important. Nuclide concentrations decrease with increasing distance from Sellafield; rates of decrease being in the order Zr + Nb > Ru > Cs. This can be related to the levels of the nuclides discharged, their sorption characteristics and their half lives. The pattern of seabed activity seems to have been fairly stable over the period 1978 - 1985, but there is evidence of a small northward shift. Concentrations of 137Cs and 106Ru in 1985 were considerably lower than in 1978 or 1982. This is explicable in terms of the fall in discharge levels allied, in the case of Ru, to its short half life and, for Cs, the desorption observed in laboratory experiments. Nuclide ratios in sediment samples yield apparent transit times for the transport of nuclides in the survey area of 1·7 - 3·7 years. These times are generally greater than those obtained from sediments in the more distant Solway Firth and Ravenglass Estuary. It is suggested that they reflect fairly intense bioturbation causing mixing of relatively recent effluent with that from earlier discharges. This is supported by structures observed in X-radiographs of box cores, an abundant burrowing benthos and by interpretations of nuclide profiles and radiocarbon dating of sediment cores by other workers. A lag effect, of up to two years across the survey area

  12. Tracing iron-carbon redox from surface to core

    Science.gov (United States)

    McCammon, C. A.; Cerantola, V.; Bykova, E.; Kupenko, I.; Bykov, M.; Chumakov, A. I.; Rüffer, R.; Dubrovinsky, L. S.

    2017-12-01

    Numerous redox reactions separate the Earth's oxidised surface from its reduced core. Many involve iron, the Earth's most abundant element and the mantle's most abundant transition element. Most iron redox reactions (although not all) also involve other elements, including carbon, where iron-carbon interactions drive a number of important processes within the Earth, for example diamond formation. Many of the Earth's redox boundaries are sharp, much like the seismic properties that define them, for example between the lower mantle and the core. Other regions that appear seismically homogeneous, for example the lower mantle, harbour a wealth of reactions between oxidised and reduced phases of iron and carbon. We have undertaken many experiments at high pressure and high temperature on phases containing iron and carbon using synchrotron-based X-rays to probe structures and iron oxidation states. Results demonstrate the dominant role that crystal structures play in determining the stable oxidation states of iron and carbon, even when oxygen fugacity (and common sense) would suggest otherwise. Iron in bridgmanite, for example, occurs predominantly in its oxidised form (ferric iron) throughout the lower mantle, despite the inferred reducing conditions. Newly discovered structures of iron carbonate also stabilise ferric iron, while simultaneously reducing some carbon to diamond to balance charge. Other high-pressure iron carbonates appear to be associated with the emerging zoo of iron oxide phases, involving transitions between ferrous and ferric iron through the exchange of oxygen. The presentation will trace redox relations between iron and carbon from the Earth's surface to its core, with an emphasis on recent experimental results.

  13. Sedimentary records of PAHs in a sediment core from tidal flat of Haizhou Bay, China.

    Science.gov (United States)

    Zhang, Rui; Zhang, Fan; Zhang, Tian-Cheng

    2013-04-15

    The concentrations and depositional fluxes of polycyclic aromatic hydrocarbons (PAHs) were investigated in a dated sediment core collected from a tidal flat in Haizhou Bay, China. The USEPA's 16 priority PAH concentrations ranged from 72.51 ng g(-1) dw in 1969 to 805.21 ng g(-1) dw in 2010, while the deposition fluxes were in the range of 102.36-861.02 ng cm(-2) yr(-1). The PAH concentrations and fluxes changed dramatically with depth, suggesting changes in energy usage and corresponding closely with the historical economic development of eastern China. The levels of PAHs slightly increased from the late 1970s, following China's "Reform and Open" policy of 1978; however, a drastic increase in the concentration of PAHs observed in 1990 was indicative of the rapid growth in coal and petroleum incomplete combustion byproducts, which was associated with the increase in economic development in this area. Furthermore, isomer ratio analysis and principle component analysis revealed the main anthropogenic pyrolytic source that causes PAH contamination in the coastal sediment. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Distribution of benthic foraminifers (>125 um) in the surface sediments of the Arctic Ocean

    Science.gov (United States)

    Osterman, Lisa E.; Poore, Richard Z.; Foley, Kevin M.

    1999-01-01

    Census data on benthic foraminifers (>125 ?m) in surface sediment samples from 49 box cores are used to define four depth-controlled biofacies, which will aid in the paleoceanographic reconstruction of the Arctic Ocean. The shelf biofacies contains a mix of shallow-water calcareous and agglutinated species from the continental shelves of the Beaufort and Chukchi Seas and reflects the variable sedimentologic and oceanic conditions of the Arctic shelves. The intermediate-depth calcareous biofacies, found between 500 and 1,100 meters water depth (mwd), contains abundant Cassidulina teretis , presumably indicating the influence of Atlantic-derived water at this depth. In water depths between 1,100 and 3,500 m, a deepwater calcareous biofacies contains abundant Oridorsalis umbonatus . Below 3,500 mwd, the deepwater mixed calcareous/agglutinated biofacies of the Canada, Makarov, and Eurasian Basins reflects a combination of low productivity, dissolution, and sediment transport. Two other benthic foraminiferal species show specific environmental preferences. Fontbotia wuellerstorfi has a depth distribution between 900 and 3,500 mwd, but maximum abundance occurs in the region of the Mendeleyev Ridge. The elevated abundance of F. wuellerstorfi may be related to increased food supply carried by a branch of Atlantic water that crosses the Lomonosov Ridge near the Russian Continental Shelf. Triloculina frigida is recognized to be a species preferring lower slope sediments commonly disturbed by turbidites and bottom currents. INTRODUCTION At present, our understanding of the Arctic Ocean lags behind our understanding of other oceans, and fundamental questions still exist about its role in and response to global climate change. The Arctic Ocean is particularly sensitive to climatic fluctuations because small changes in the amounts of sea-ice cover can alter global albedo and thermohaline circulation (Aagaard and Carmack, 1994). Numerous questions still exist regarding the nature

  15. Mercury flux from salt marsh sediments: Insights from a comparison between 224Ra/228Th disequilibrium and core incubation methods

    Science.gov (United States)

    Shi, Xiangming; Mason, Robert P.; Charette, Matthew A.; Mazrui, Nashaat M.; Cai, Pinghe

    2018-02-01

    In aquatic environments, sediments are the main location of mercury methylation. Thus, accurate quantification of methylmercury (MeHg) fluxes at the sediment-water interface is vital to understanding the biogeochemical cycling of mercury, especially the toxic MeHg species, and their bioaccumulation. Traditional approaches, such as core incubations, are difficult to maintain at in-situ conditions during assays, leading to over/underestimation of benthic fluxes. Alternatively, the 224Ra/228Th disequilibrium method for tracing the transfer of dissolved substances across the sediment-water interface, has proven to be a reliable approach for quantifying benthic fluxes. In this study, the 224Ra/228Th disequilibrium and core incubation methods were compared to examine the benthic fluxes of both 224Ra and MeHg in salt marsh sediments of Barn Island, Connecticut, USA from May to August, 2016. The two methods were comparable for 224Ra but contradictory for MeHg. The radiotracer approach indicated that sediments were always the dominant source of both total mercury (THg) and MeHg. The core incubation method for MeHg produced similar results in May and August, but an opposite pattern in June and July, which suggested sediments were a sink of MeHg, contrary to the evidence of significant MeHg gradients between overlying water and porewater at the sediment-water interface. The potential reasons for such differences are discussed. Overall, we conclude that the 224Ra/228Th disequilibrium approach is preferred for estimating the benthic flux of MeHg and that sediment is indeed an important MeHg source in this marshland, and likely in other shallow coastal waters.

  16. Comparison of different enrichment factors to assess the natural accumulation of trace elements in sediment cores from Nhecolandia Pantanal, Brazil

    International Nuclear Information System (INIS)

    Santos, Levi F.; Damatto, Sandra R.; Barbiero, Laurent; Furian, Sonia M.; Rezende Filho, Ary T.

    2015-01-01

    Four sediment cores were collected at different lakes of salty water, commonly known as 'Salinas', in the Nhecolandia Wetland. In the collected cores, Salina A, Salina 6, Salina M and Salina V, the elements As, Ba, Co, Cr, Cs, Fe, Hf, K, Na, Rb, Sb, Se, U, Zn and rare earth elements Ce, Eu, La, Lu, Nd, Sc, Sm, Tb and Yb concentrations were determined by instrumental neutron activation analysis (INAA) technique. Aiming to verify the best criterion to evaluate the enrichment factor of minor and major elements in the sediment cores, three different calculations of the enrichment factor was employed. The first one, EF (Enrichment Factor), compares the normalized element concentrations with Upper Continental Crust normalized values, the second one, GNF (Geochemical Normalization Factor) compares the ratio between the element concentration and the normalizer with the depth in the sediment core; for these both factors the element Sc was used as a normalizer element. The third one factor, BEF (Base Enrichment Factor), compares the concentrations determined throughout the core with the results obtained in the base of it. With the results, it was possible to conclude that the best enrichment factor to evaluate the enhancement of elements in natural environments is the one that takes into account the core element concentration obtained in the base of it, BEF. (author)

  17. Comparison of different enrichment factors to assess the natural accumulation of trace elements in sediment cores from Nhecolandia Pantanal, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Levi F.; Damatto, Sandra R., E-mail: leyi@usp.br, E-mail: damatto@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Barbiero, Laurent, E-mail: barbiero@ltmg.obs.mip.fr [Centro de Energia Nuclear na Agricultura (CENA/USP), Sao Paulo, SP (Brazil); Furian, Sonia M., E-mail: furian@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Departamento de Geografia; Rezende Filho, Ary T., E-mail: ary.rezende@ufms.br [Universidade Federal do Mato Grosso do Sul (UFMS), MS (Brazil). Faculdade de Engenharias, Arquitetura e Urbanismo e Geografia

    2015-07-01

    Four sediment cores were collected at different lakes of salty water, commonly known as 'Salinas', in the Nhecolandia Wetland. In the collected cores, Salina A, Salina 6, Salina M and Salina V, the elements As, Ba, Co, Cr, Cs, Fe, Hf, K, Na, Rb, Sb, Se, U, Zn and rare earth elements Ce, Eu, La, Lu, Nd, Sc, Sm, Tb and Yb concentrations were determined by instrumental neutron activation analysis (INAA) technique. Aiming to verify the best criterion to evaluate the enrichment factor of minor and major elements in the sediment cores, three different calculations of the enrichment factor was employed. The first one, EF (Enrichment Factor), compares the normalized element concentrations with Upper Continental Crust normalized values, the second one, GNF (Geochemical Normalization Factor) compares the ratio between the element concentration and the normalizer with the depth in the sediment core; for these both factors the element Sc was used as a normalizer element. The third one factor, BEF (Base Enrichment Factor), compares the concentrations determined throughout the core with the results obtained in the base of it. With the results, it was possible to conclude that the best enrichment factor to evaluate the enhancement of elements in natural environments is the one that takes into account the core element concentration obtained in the base of it, BEF. (author)

  18. Settlement patterns of the coral Acropora millepora on sediment-laden surfaces.

    Science.gov (United States)

    Ricardo, Gerard F; Jones, Ross J; Nordborg, Mikaela; Negri, Andrew P

    2017-12-31

    Successful recruitment in corals is important for the sustenance of coral reefs, and is considered a demographic bottleneck in the recovery of reef populations following disturbance events. Yet several factors influence larval settlement behaviour, and here we quantified thresholds associated with light attenuation and accumulated sediments on settlement substrates. Sediments deposited on calcareous red algae (CRA) directly and indirectly impacted coral settlement patterns. Although not avoiding direct contact, Acropora millepora larvae were very reluctant to settle on surfaces layered with sediments, progressively shifting their settlement preference from upward to downward facing (sediment-free) surfaces under increasing levels of deposited sediment. When only upward-facing surfaces were presented, 10% of settlement was inhibited at thresholds from 0.9 to 16mgcm -2 (EC 10 ), regardless of sediment type (carbonate and siliciclastic) or particle size (fine and coarse silt). These levels equate to a very thin (<150μm) veneer of sediment that occurs within background levels on reefs. Grooves within settlement surfaces slightly improved options for settlement on sediment-coated surfaces (EC 10 : 29mgcm -2 ), but were quickly infilled at higher deposited sediment levels. CRA that was temporarily smothered by sediment for 6d became bleached (53% surface area), and inhibited settlement at ~7mgcm -2 (EC 10 ). A minor decrease in settlement was observed at high and very low light intensities when using suboptimal concentrations of a settlement inducer (CRA extract); however, no inhibition was observed when natural CRA surfaces along with more realistic diel-light patterns were applied. The low deposited sediment thresholds indicate that even a thin veneer of sediment can have consequences for larval settlement due to a reduction of optimal substrate. And while grooves and overhangs provide more settlement options in high deposition areas, recruits settling at these

  19. [Characteristics and Risk Assessment of Heavy Metals in Core Sediments from Lakes of Tibet].

    Science.gov (United States)

    Guo, Bi-xi; Liu, Yong-qin; Zhang, Fan; Hou, Ju-zhi; Zhang, Hong-bo

    2016-02-15

    To explore the source of heavy metals in lake sediments and their hazard to environment on Tibetan Plateau, China, heavy metal (Cu, Zn, Cd, Pb, Cr, Co, Ni and As) levels in surface sediments of 18 lakes were investigated. Inductively Coupled Plasma Mass Spectrometry (ICP-MS, X-7 series) was used to determine the contents of heavy metals and the concentrations of carbon and nitrogen in sediment samples were analyzed by element analyzer (Vario Max CN, Elementar, Germany). The average concentrations for Cu, Zn, Cd, Pb, Cr, Co, Ni and As were 24.61 mg x kg(-1), 70.14 mg x kg(-1), 0.26 mg x kg(-1), 25.43 mg x kg(-1), 74.12 mg x kg(-1), 7.93 mg x kg(-1), 33.85 mg x kg(-1), 77.69 mg x kg(-1). It was found that heavy-metal concentrations in Tibet sediments were higher than those in Antarctic, but lower than those in the regions affected by anthropogenic activities. The contents of Cu, Zn, Pb, Cr and Co in the samples were lower than the background values of Tibet. Correlation analysis and principal components analysis (PCA) were used to analyze the origins of heavy metals. The result showed that Cu, Zn, Cd, Pb, Co, Ni and As came from soil in drainage basin and atmospheric deposition. Cr was mainly affected by human activities. Assessment on ecological risk of heavy metals was carried out using Hakanson's method and cluster analysis (CA). Assessment on ecological risk indicated that Pumoyum Co, Longmo Co and Bangong Co were at low risks, Bieruoze Co was at high ecological risk level and the other lakes were at different risk levels.

  20. A carbon, nitrogen, and sulfur elemental and isotopic study in dated sediment cores from the Louisiana Shelf

    Science.gov (United States)

    Rosenbauer, R.J.; Swarzenski, P.W.; Kendall, C.; Orem, W.H.; Hostettler, F.D.; Rollog, M.E.

    2009-01-01

    Three sediment cores were collected off the Mississippi River delta on the Louisiana Shelf at sites that are variably influenced by recurring, summer-time water-column hypoxia and fluvial loadings. The cores, with established chronology, were analyzed for their respective carbon, nitrogen, and sulfur elemental and isotopic composition to examine variable organic matter inputs, and to assess the sediment record for possible evidence of hypoxic events. Sediment from site MRJ03-3, which is located close to the Mississippi Canyon and generally not influenced by summer-time hypoxia, is typical of marine sediment in that it contains mostly marine algae and fine-grained material from the erosion of terrestrial C4 plants. Sediment from site MRJ03-2, located closer to the mouth of the Mississippi River and at the periphery of the hypoxic zone (annual recurrence of summer-time hypoxia >50%), is similar in composition to core MRJ03-3, but exhibits more isotopic and elemental variability down-core, suggesting that this site is more directly influenced by river discharge. Site MRJ03-5 is located in an area of recurring hypoxia (annual recurrence >75%), and is isotopically and elementally distinct from the other two cores. The carbon and nitrogen isotopic composition of this core prior to 1960 is similar to average particulate organic matter from the lower Mississippi River, and approaches the composition of C3 plants. This site likely receives a greater input of local terrestrial organic matter to the sediment. After 1960 and to the present, a gradual shift to higher values of ??13C and ??15N and lower C:N ratios suggests that algal input to these shelf sediments increased as a result of increased productivity and hypoxia. The values of C:S and ??34S reflect site-specific processes that may be influenced by the higher likelihood of recurring seasonal hypoxia. In particular, the temporal variations in the C:S and ??34S down-core are likely caused by changes in the rate of

  1. A carbon, nitrogen, and sulfur elemental and isotopic study in dated sediment cores from the Louisiana Shelf

    Science.gov (United States)

    Rosenbauer, Robert J.; Swarzenski, Peter W.; Kendall, Carol; Orem, William H.; Hostettler, Frances D.; Rollog, Mark E.

    2009-12-01

    Three sediment cores were collected off the Mississippi River delta on the Louisiana Shelf at sites that are variably influenced by recurring, summer-time water-column hypoxia and fluvial loadings. The cores, with established chronology, were analyzed for their respective carbon, nitrogen, and sulfur elemental and isotopic composition to examine variable organic matter inputs, and to assess the sediment record for possible evidence of hypoxic events. Sediment from site MRJ03-3, which is located close to the Mississippi Canyon and generally not influenced by summer-time hypoxia, is typical of marine sediment in that it contains mostly marine algae and fine-grained material from the erosion of terrestrial C4 plants. Sediment from site MRJ03-2, located closer to the mouth of the Mississippi River and at the periphery of the hypoxic zone (annual recurrence of summer-time hypoxia >50%), is similar in composition to core MRJ03-3, but exhibits more isotopic and elemental variability down-core, suggesting that this site is more directly influenced by river discharge. Site MRJ03-5 is located in an area of recurring hypoxia (annual recurrence >75%), and is isotopically and elementally distinct from the other two cores. The carbon and nitrogen isotopic composition of this core prior to 1960 is similar to average particulate organic matter from the lower Mississippi River, and approaches the composition of C3 plants. This site likely receives a greater input of local terrestrial organic matter to the sediment. After 1960 and to the present, a gradual shift to higher values of δ13C and δ15N and lower C:N ratios suggests that algal input to these shelf sediments increased as a result of increased productivity and hypoxia. The values of C:S and δ34S reflect site-specific processes that may be influenced by the higher likelihood of recurring seasonal hypoxia. In particular, the temporal variations in the C:S and δ34S down-core are likely caused by changes in the rate of

  2. Wright Valley Sediments as Potential Analogs for Martian Surface Processes

    Science.gov (United States)

    Englert, P. A. J.; Bishop, J. L.; Patel, S.; Gibson, E. K.; Koeberl, C.

    2015-12-01

    The Antarctic Dry Valleys (ADV) may provide a unique terrestrial analog for current Martian surface processes. The Wright Valley located in the ADV contains streams, lakes and ponds that host highly saline, sedimentary environments. This project highlights comparisons of formation and salt accumulation processes at the Don Juan Pond (DJP) and Don Quixote Pond (DQP). These are located in the north and south forks of the Wright Valley, which are unique areas where unusual terrestrial processes can be studied. DQP is located in the western part of the north fork about 100 m above mean seawater level. The DQP Valley walls are up to 2500 m high and the brine is seasonally frozen. DJP from the south fork is located ~9 km west of Lake Vanda. The basin floor is 117 m above mean seawater level with activity to the north and south rising above 1000 m. The DJP brine does not freeze and may be a model environment for Ca and Cl weathering and distribution on Mars. Our findings indicate that DJP and DQP have formed in similar climatic and geological environments, but likely experienced different formation conditions. Samples were collected from surface, soil pits and depth profiles during the 1979/1980, the 1990/1991 and the 2005/2006 field seasons. Elemental abundances and mineralogy were evaluated for several sets of sediments. The DJP basin shows low surface abundances of halite and relatively high abundances of sulfates throughout with gypsum or anhydrite dominating at different locations. The DQP area has high surface abundances of halite with gypsum present as the major sulfate. Two models have been proposed to explain these differences: DQP may have formed through a combination of shallow and some deep groundwater influx, while deep groundwater upwelling likely played the dominant role of salt formation at DJP. Our study seeks to understand the formation of DQP and DJP as unique terrestrial processes and as models for Ca, Cl, and S weathering and distribution on Mars.

  3. Heavy sediment influx during early Holocene: Inference from clay mineral studies in a core from the western Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Reddy, N.P.C.; Rao, K.M.

    Clay mineral studies were carried out in a 650 cm long sediment core collected at a depth of 2200 m from the north-western Bay of Bengal. Illite is the predominant mineral, followed by montmorillonite and chlorite. Illite concentration varies from...

  4. Fluctuation in glacial and interglacial sediment discharge of the River Indus as seen in the core from the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Guptha, M.V.S.; Hashimi, N.H.

    Sediment core from the upper continental slope off Saurashtra Coast has been analysed for CaCO sub(3) and coarse fraction contents in addition to planktonic foraminifera and clay mineralogy. Based on CaCO sub(3) and planktonic foraminiferal data a...

  5. Phosphorite concretions in a sediment core from a bathymetric high off Goa, western continental margin of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, Ch.M; Rao, B.R.

    A sediment core collected from a bathymetric high off Goa on the western continental margin of India, has yielded phosphorite concretions with an average Pd2O5 content of 32.75%, the P2O5 concentrations being highest ever reported from the margins...

  6. [Surface Property and Sorption Characteristics of Phosphorus onto Surface Sediments in Sanggou Bay].

    Science.gov (United States)

    Zhu, Jia-mei; Cao, Xiao-yan; Liu, Su-mei; Wang, Li-sha; Yang, Gui-peng; Ge, Cheng-feng; Lu, Min

    2016-02-15

    Kinetic curves and isotherms were investigated to study the sorption mechanism of phosphorus onto the sediments of Sanggou Bay, together with the surface charge properties of sediments and the forms of phosphorus studied. The results showed that the sorption including a fast process and a slow one, and could be described by a two-compartment first order equation. The thermodynamic isotherms were well fitted with a modified Langmuir equation. The maximum adsorption capacity was larger in summer than in spring, and the smaller particle size was favorable to the sorption. The maximum adsorption capacities (Qm) were 0.0471-0.1230 mg x g(-1), and the zero equilibrium phosphorus concentration (EPC0) of the sediments ranged from 0.0596 mg x L(-1) to 0.1927 mg x L(-1), which indicated that the sediments from Sanggou Bay were sources of phosphorus. Inorganic phosphorus (IP) was the main form of total phosphorus (TP). The contents of exchangeable or loosely absorbed P and Fe-bound P increased significantly in the samples after sorption. The sorption process involved physical sorption and chemical sorption, with the former being the predominant.

  7. Age of a prehistoric "Rodedian" cult site constrained by sediment and rock surface luminescence dating techniques

    DEFF Research Database (Denmark)

    Sohbati, Reza; Murray, Andrew; Porat, N.

    2015-01-01

    . Important information on the bleaching history of the rock surfaces directly obtained from these luminescencedepth profiles is not available in the underlying unconsolidated sediments. This is a significant advantage of rock surface dating over more conventional sediment dating. © 2015 Elsevier B.V. All...

  8. Quantitative radiolarian assemblages in surface sediments from the central Indian Basin and their paleomonsoonal significance

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, S.M.

    The percentage data of 47 radiolarian coarser taxonomic groups in the surface sediments from the central Indian Basin was subjected to cluster and factor analyses. The R-mode cluster analysis resulted in 3 dominant clusters which represent surface...

  9. Intense equatorial flux spots on the surface of Earth's core

    Science.gov (United States)

    Jackson, A.

    2003-04-01

    A vast number of vector measurements of the Earth's magnetic field have recently become available from the satellite Oersted, currently in orbit monitoring the core magnetic field. In this presentation I will present new maps of the Earth's magnetic field at the surface of the fluid core derived from these satellite data which show intense flux spots in equatorial regions; the images are derived using a maximum entropy technique which is capable of reconstructing images with high dynamic range more precisely than conventional techniques. The intensity of these features is unusually large - they are comparable to high-latitude flux patches near the poles, previously identified as the major component of the dynamo field. A comparison with sunspots is tempting, though they are probably not associated with expulsion of toroidal magnetic field as is the case for the sun. Indeed, the tendency for pairing of these spots to the north and south of the geographical equator suggests they might be associated with the tops of so-called `Taylor columns' (indicative of the dominance of the rotation of the Earth) which have previously been suggested to be associated with the four high-latitude flux patches near the poles. Equatorially-trapped waves are known to exist in theory, and a correct interpretation of these features might lead to constraints on the strength of the hidden toroidal magnetic field within the Earth, as well as constraints on other physical regimes.

  10. Core surface flow modelling from high-resolution secular variation

    DEFF Research Database (Denmark)

    Holme, R.; Olsen, Nils

    2006-01-01

    -flux hypothesis, but the spectrum of the SV implies that a conclusive test of frozen-flux is not possible. We parametrize the effects of diffusion as an expected misfit in the flow prediction due to departure from the frozen-flux hypothesis; at low spherical harmonic degrees, this contribution dominates...... the expected departure of the SV predictions from flow to the observed SV, while at high degrees the SV model uncertainty is dominant. We construct fine-scale core surface flows to model the SV. Flow non-uniqueness is a serious problem because the flows are sufficiently small scale to allow flow around non......-series of magnetic data and better parametrization of the external magnetic field....

  11. A survey of metal concentrations in marine sediment cores in the vicinity of an old mercury-mining area in Karaburun, Aegean Sea.

    Science.gov (United States)

    Ozkan, Ebru Yesim; Buyukisik, Hasan Baha; Kontas, Aynur; Turkdogan, Mert

    2017-05-01

    The aim of this study was to assess the historical trends of metal concentrations in coastal sediments in the vicinity of an inactive mining area, find background values and contamination levels of metals around the Karaburun peninsula, and then search for other sources of mercury in marine sediment cores using multivariate statistical analysis and report the potential ecological risks from that metal contamination. Surface sediment samples were taken from seven stations. Water depths were less than 20 m (coastal area) at stations KB07 and KB08. The depths at stations KB01, KB02, and KB03 were between 20 and 40 m, and stations KB05 and KB06 were more than 40 m (open area). In surface sediments at depths between 20 and 40 m, Mo, Cu, Pb, Zn, Ni, Co, Fe, Cd, Ti, Zr, Sn, As, Y, and Hg levels revealed higher contamination factors (C f ) compared to those of the coastal and open areas. Also, sediment samples were taken for historical records at stations KB01 and KB02 for 2012. Metal concentrations of Cu, Zn, Ni, Co, As, Sb, Cr, Ba, Ti, Al, and Hg in the sediment core samples were significantly higher during the Holocene (~5700 BC to 2000 B.C.) and Medieval Warm periods (~1000 A.D. to 1400 A.D.) and tended to decrease towards the Little Ice Age (2200 B.C. to the birth of Jesus Christ). Background concentration of Hg in sediment was found as 1.67 μg/g around the Karaburun peninsula. Average EF values higher than 20 were identified for As, Hg, Sb, and Ca. Ni and Hg levels were found above the PEL values. It was determined that the accumulation effect of Hg coming from the mafic rocks due to erosion in the marine environment was higher than that of Hg coming from the mine. The factor analyses showed an association between Hg, Ni, and Co. This reveals the importance of the contribution of mafic rocks reaching the marine environment by wave erosion. According to the factor analyses, high concentrations of Pb, Zn, Cd, As, Sb, Ba, Ti, and Zr were detected in the

  12. Late Quaternary sediment deposition of core MA01 in the Mendeleev Ridge, the western Arctic Ocean: Preliminary results

    Science.gov (United States)

    Park, Kwang-Kyu; Kim, Sunghan; Khim, Boo-Keun; Xiao, Wenshen; Wang, Rujian

    2014-05-01

    Late Quaternary deep marine sediments in the Arctic Ocean are characterized by brown layers intercalated with yellowish to olive gray layers (Poore et al., 1999; Polyak et al., 2004). Previous studies reported that the brown and gray layers were deposited during interglacial (or interstadial) and glacial (or stadial) periods, respectively. A 5.5-m long gravity core MA01 was obtained from the Mendeleev Ridge in the western Arctic Ocean by R/V Xue Long during scientific cruise CHINARE-V. Age (~450 ka) of core MA01 was tentatively estimated by correlation of brown layers with an adjacent core HLY0503-8JPC (Adler et al., 2009). A total of 22 brown layers characterized by low L* and b*, high Mn concentration, and abundant foraminifera were identified. Corresponding gray layers are characterized by high L* and b*, low Mn concentration, and few foraminiferal tests. Foraminifera abundance peaks are not well correlated to CaCO3 peaks which occurred with the coarse-grained (>0.063 mm) fractions (i.e., IRD) both in brown and gray layers. IRDs are transported presumably by sea ice for the deposition of brown layers and by iceberg for the deposition of gray layers (Polyak et al., 2004). A strong correlation coefficient (r2=0.89) between TOC content and C/N ratio indicates that the major source of organic matter is terrestrial. The good correlations of CaCO3 content to TOC (r2=0.56) and C/N ratio (r2=0.69) imply that IRDs contain detrital CaCO3 which mainly originated from the Canadian Arctic Archipelago. In addition, high kaolinite/chlorite (K/C) ratios mostly correspond to CaCO3 peaks, which suggests that the fine-grained particles in the Mendeleev Ridge are transported from the north coast Alaska and Canada where Mesozoic and Cenozoic strata are widely distributed. Thus, the Beaufort Gyre, the predominant surface current in the western Arctic Ocean, played an important role in the sediment delivery to the Mendeleev Ridge. It is worthy of note that the TOC and CaCO3 peaks are

  13. Paleomagnetism and environmental magnetism of GLAD800 sediment cores from Bear Lake, Utah and Idaho

    Science.gov (United States)

    Heil, C.W.; King, J.W.; Rosenbaum, J.G.; Reynolds, R.L.; Colman, Steven M.

    2009-01-01

    A ???220,000-year record recovered in a 120-m-long sediment core from Bear Lake, Utah and Idaho, provides an opportunity to reconstruct climate change in the Great Basin and compare it with global climate records. Paleomagnetic data exhibit a geomagnetic feature that possibly occurred during the Laschamp excursion (ca. 40 ka). Although the feature does not exhibit excursional behavior (???40?? departure from the expected value), it might provide an additional age constraint for the sequence. Temporal changes in salinity, which are likely related to changes in freshwater input (mainly through the Bear River) or evaporation, are indicated by variations in mineral magnetic properties. These changes are represented by intervals with preserved detrital Fe-oxide minerals and with varying degrees of diagenetic alteration, including sulfidization. On the basis of these changes, the Bear Lake sequence is divided into seven mineral magnetic zones. The differing magnetic mineralogies among these zones reflect changes in deposition, preservation, and formation of magnetic phases related to factors such as lake level, river input, and water chemistry. The occurrence of greigite and pyrite in the lake sediments corresponds to periods of higher salinity. Pyrite is most abundant in intervals of highest salinity, suggesting that the extent of sulfidization is limited by the availability of SO42-. During MIS 2 (zone II), Bear Lake transgressed to capture the Bear River, resulting in deposition of glacially derived hematite-rich detritus from the Uinta Mountains. Millennial-scale variations in the hematite content of Bear Lake sediments during the last glacial maximum (zone II) resemble Dansgaard-Oeschger (D-O) oscillations and Heinrich events (within dating uncertainties), suggesting that the influence of millennial-scale climate oscillations can extend beyond the North Atlantic and influence climate of the Great Basin. The magnetic mineralogy of zones IV-VII (MIS 5, 6, and 7

  14. Effects of soil surface roughness on interrill erosion processes and sediment particle size distribution

    Science.gov (United States)

    Ding, Wenfeng; Huang, Chihua

    2017-10-01

    Soil surface roughness significantly impacts runoff and erosion under rainfall. Few previous studies on runoff generation focused on the effects of soil surface roughness on the sediment particle size distribution (PSD), which greatly affects interrill erosion and sedimentation processes. To address this issue, a rainfall-simulation experiment was conducted with treatments that included two different initial soil surface roughnesses and two rainfall intensities. Soil surface roughness was determined by using photogrammetric method. For each simulated event, runoff and sediment samples were collected at different experimental times. The effective (undispersed) PSD of each sediment sample and the ultimate (after dispersion) PSD were used to investigate the detachment and transport mechanisms involved in sediment movement. The results show that soil surface roughness significantly delayed runoff initiation, but had no significant effect on the steady runoff rate. However, a significant difference in the soil loss rate was observed between the smooth and rough soil surfaces. Sediments from smooth soil surfaces were more depleted in clay-size particles, but more enriched in sand-size particles than those from rough soil surfaces, suggesting that erosion was less selective on smooth than on rough soil surfaces. The ratio of different sizes of transported sediment to the soil matrix indicates that most of the clay was eroded in the form of aggregates, silt-size particles were transported mainly as primary particles, and sand-size particles were predominantly aggregates of finer particles. Soil surface roughness has a crucial effect on the sediment size distribution and erosion processes. Significant differences of the enrichment ratios for the effective PSD and the ultimate PSD were observed under the two soil surface roughness treatments. These findings demonstrate that we should consider each particle size separately rather than use only the total sediment discharge in

  15. Metal pollution determined by pollution indices for sea grass P. oceanica and surface sediments

    Directory of Open Access Journals (Sweden)

    Stanković Slavka

    2015-01-01

    Full Text Available Concentrations of Fe, Mn, Cu, Zn, Pb, Ni, Co, As, Co, and Hg in the sea grass Posidonia oceanica and surface sediment samples were determined. Together with P. oceanica, surface sediment samples were collected at eight locations in the major demographic, tourist and port areas along the Montenegrin coast to assess metal pollution. The metal pollution index (MPI and metal enrichment factor (EF were calculated and used to evaluate the impact of heavy metals in the surface sediment on P. oceanica. The sediment MPI and EF values were lower than these values in P. oceanica at the same locations. Since the surface sediment contained lower mean concentrations of Zn, Ni, Pb, Cd and Hg, than the sea grass P. oceanic, we concluded that the sea grass absorbed some metals from the seawater column. [Projekat Ministarstva nauke Republike Srbije, br. III 43009

  16. 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)

  17. Heavy metals in surface sediments of the Jialu River, China: Their relations to environmental factors

    International Nuclear Information System (INIS)

    Fu, Jie; Zhao, Changpo; Luo, Yupeng; Liu, Chunsheng; Kyzas, George Z.; Luo, Yin; Zhao, Dongye; An, Shuqing; Zhu, Hailiang

    2014-01-01

    Highlights: • Zhengzhou City had major effect on the pollution of the Jialu River. • TN, OP, TP and COD Mn in water drove heavy metals to deposit in sediments. • B-IBI was sensitive to the adverse effect of heavy metals in sediments. - Abstract: This work investigated heavy metal pollution in surface sediments of the Jialu River, China. Sediment samples were collected at 19 sites along the river in connection with field surveys and the total concentrations were determined using atomic fluorescence spectrometer and inductively coupled plasma optical emission spectrometer. Sediment samples with higher metal concentrations were collected from the upper reach of the river, while sediments in the middle and lower reaches had relatively lower metal concentrations. Multivariate techniques including Pearson correlation, hierarchical cluster and principal components analysis were used to evaluate the metal sources. The ecological risk associated with the heavy metals in sediments was rated as moderate based on the assessments using methods of consensus-based Sediment Quality Guidelines, Potential Ecological Risk Index and Geo-accumulation Index. The relations between heavy metals and various environmental factors (i.e., chemical properties of sediments, water quality indices and aquatic organism indices) were also studied. Nitrate nitrogen, total nitrogen, and total polycyclic aromatic hydrocarbons concentrations in sediments showed a co-release behavior with heavy metals. Ammonia nitrogen, total nitrogen, orthophosphate, total phosphate and permanganate index in water were found to be related to metal sedimentation. Heavy metals in sediments posed a potential impact on the benthos community

  18. Vertical distributions of plutonium isotopes in marine sediment cores off the Fukushima coast after the Fukushima Dai-ichi Nuclear Power Plant accident

    Directory of Open Access Journals (Sweden)

    W. T. Bu

    2013-04-01

    Full Text Available The Fukushima Dai-ichi Nuclear Power Plant (FDNPP accident led to the release of large amounts of radionuclides into the atmosphere as well as direct discharges into the sea. In contrast to the intensive studies on the distribution of the released high volatility fission products, such as 131I, 134Cs and 137Cs, similar studies of the actinides, especially the Pu isotopes, are limited. To obtain the vertical distribution of Pu isotopes in marine sediments and to better assess the possible contamination of Pu from the FDNPP accident in the marine environment, we determined the activities of 239+240Pu and 241Pu as well as the atom ratios of 240Pu/239Pu and 241Pu/239Pu in sediment core samples collected in the western North Pacific off Fukushima from July 2011 to July 2012. We also measured surface sediment samples collected from seven Japanese estuaries before the FNDPP accident to establish the comprehensive background baseline data. The observed results of both the Pu activities and the Pu atom ratios for the sediments in the western North Pacific were comparable to the baseline data, suggesting that the FDNPP accident did not cause detectable Pu contamination to the studied regions prior to the sampling time. The Pu isotopes in the western North Pacific 30 km off the Fukushima coast originated from global fallout and Pacific Proving Ground close-in fallout.

  19. Anthropogenic Pollution in Izmit Bay: Heavy Metal Concentrations in Surface Sediments

    OpenAIRE

    YAŞAR, D.

    2014-01-01

    The extent of marine pollution in İzmit Bay is studied using geochemical data in surface sediments. The concentrations of 41 elements in 24 samples establish that surface sediments in inner and central İzmit Bay display significant enrichments in Ag, As, Cd, Cr, Co, Cu, Hg, Mo, P, Pb, Sb, Ti, V, and Zn associated with high concentrations of total organic carbon and sulphur. Geo-accumulation indices indicate that the inner and central İzmit Bay surface sediments are moderately to very...

  20. Neutron activation analysis to the profile surface sediments from several sites on the Havana Bay

    International Nuclear Information System (INIS)

    Diaz Riso, O.; Gelen, A.; Lopez, N.; Gonzalez, H.; Manso, M.V.; Graciano, A.M.; Nogueira, C.A.; Beltran, J.; Soto, J.

    2003-01-01

    Instrumental neutron activation analysis (INAA) technique was employed to analyze the surface sediments from several sites on the Havana Bay, Cuba. Measurements of heavy and trace elements in the sediments are reported. The results show that the concentration of the elements is site dependent. The data suggest that an anthropogenic input into the bay from domestic sewage and industries occurred

  1. Microplastics Baseline Surveys at the Water Surface and in Sediments of the North-East Atlantic

    NARCIS (Netherlands)

    Maes, Thomas; van der Meulen, Myra; Devriese, Lisa; Leslie, H.A.; Huvet, Arnaud; Frère, Laura; Robbens, Johan; Vethaak, A.D.

    2017-01-01

    Microplastic contamination was determined in sediments of the Southern North Sea and floating at the sea surface of NorthWest Europe. Floating concentrations ranged between 0 and 1.5 microplastic/m3, whereas microplastic concentrations in sediments ranged between 0 and 3,146 particles/kg dry weight

  2. Impacts on surface productivity during sediment dispersal experiment in Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; Nath, B.N.; Ingole, B.S.; Parthiban, G.; Matondkar, S.G.P.; Raghukumar, C.; Khadge, N.H.; Valsangkar, A.B.; Suryanarayana, A.; Jaisankar, S.; Sharma, R.

    conditions at the point of discharge thus altering the regimes of productivity in the water column. In order to assess the effects of deep sea sediment discharge on the oceanic surface water-layers (0-50M) after nodule mining, a Sediment Dispersal Experiment...

  3. Tephrostratigraphic studies on a sediment core from Lake Prespa in the Balkans

    Directory of Open Access Journals (Sweden)

    M. Damaschke

    2013-01-01

    Full Text Available A detailed tephrostratigraphic record, which dates back to Marine Isotope Stage (MIS 5b (ca. 91 kyr, has been established from a 17.76 m long core (Co1215 from Lake Prespa (Macedonia, Albania and Greece. A total of eleven tephra and cryptotephra layers (PT0915-1 to PT0915-11 were identified, using XRF scanning, magnetic susceptibility measurements, and macro- and microscopic inspection of the sediments. The major element composition of glass shards and/or micro-pumice fragments indicates that the tephras and cryptotephras originate from the explosive volcanism of Italy. Eight tephra and cryptotephra layers were correlated with specific volcanic eruptions: the AD 512 eruption of Somma-Vesuvius (1438 cal yr BP, the Mercato eruption of Somma-Vesuvius (8890 ± 90 cal yr BP, the Tufi Biancastri/LN1-LN2 eruption of the Campi Flegrei (14 749 ± 523 cal yr BP and 15 551 ± 621 cal yr BP, the SMP1-e/Y-3 eruption of the Campi Flegrei (30 000–31 000 cal yr BP, the Campanian Ignimbrite/Y-5 eruption of the Campi Flegrei (39 280 ± 110 cal yr BP, the SMP1-a event of Ischia Island (around 44 000 cal yr BP and the Green Tuff/Y-6 eruption of Pantelleria Island (around 45 000 cal yr BP. One tephra could be attributed to the volcanic activity of Mount Etna, but probably represents an unknown eruption at ca. 60 000 cal yr BP. Cryptotephras PT0915-6 and PT0915-10 remain unclassified so far, but according to the presented age-depth model these would have been deposited around 35 000 and 48 500 cal yr BP, respectively. Some of the tephras and cryptotephras are recognised for the first time in the Balkan region. The tephrostratigraphic work provides important information about ash dispersal and explosion patterns of source volcanoes and can be used to correlate and date geographically distant paleoenvironmental and archaeological archives in the central Mediterranean region. Moreover, the tephrostratigraphic work in combination with radiocarbon and electron spin

  4. Reconstruction of pollution history of organic contaminants in the upper Gulf of Thailand by using sediment cores: first report from Tropical Asia Core (TACO) project.

    Science.gov (United States)

    Boonyatumanond, Ruchaya; Wattayakorn, Gullaya; Amano, Atsuko; Inouchi, Yoshio; Takada, Hideshige

    2007-05-01

    This paper reports the first reconstruction of a pollution history in tropical Asia from sediment cores. Four sediment core samples were collected from an offshore transect in the upper Gulf of Thailand and were analyzed for organic micropollutants. The cores were dated by measurement of (137)Cs and geochronometric molecular markers (linear alkylbenzenes, LABs; and tetrapropylene-type alkylbenzenes, TABs). Polychlorinated biphenyl (PCB) concentrations showed a subsurface maximum in layers corresponding to the 1970s, indicating the effectiveness of regulation of PCBs in Thailand. LAB concentrations increased over time, indicating the increase in input of sewage into the Gulf during the last 30 years. Hopanes, biomarkers of petroleum pollution, also increased over time, indicating that the inputs of automobile-derived hydrocarbons to the coastal zone has been increasing owing to the increased number of cars in Thailand since the 1950s. Polycyclic aromatic hydrocarbons (PAHs) increased in the layers corresponding to the 1950s and 1960s, probably because of the increased inputs of automobile-derived PAHs. PAH concentrations in the upper layers corresponding to the 1970s and later remained constant or increased. The absence of a subsurface maximum of PAHs contrasts with results observed in industrialized countries. This can be explained by the facts that the Thai economy did not depend on coal as an energy source in the 1960s and that economic growth has continued since the 1970s to the present. The deposition flux of PAHs and hopanes showed a dramatic offshore decrease, whereas that of LABs was uniform.

  5. Reconstruction of pollution history of organic contaminants in the upper Gulf of Thailand by using sediment cores: First report from Tropical Asia Core (TACO) project

    International Nuclear Information System (INIS)

    Boonyatumanond, Ruchaya; Wattayakorn, Gullaya; Amano, Atsuko; Inouchi, Yoshio; Takada, Hideshige

    2007-01-01

    This paper reports the first reconstruction of a pollution history in tropical Asia from sediment cores. Four sediment core samples were collected from an offshore transect in the upper Gulf of Thailand and were analyzed for organic micropollutants. The cores were dated by measurement of 137 Cs and geochronometric molecular markers (linear alkylbenzenes, LABs; and tetrapropylene-type alkylbenzenes, TABs). Polychlorinated biphenyl (PCB) concentrations showed a subsurface maximum in layers corresponding to the 1970s, indicating the effectiveness of regulation of PCBs in Thailand. LAB concentrations increased over time, indicating the increase in input of sewage into the Gulf during the last 30 years. Hopanes, biomarkers of petroleum pollution, also increased over time, indicating that the inputs of automobile-derived hydrocarbons to the coastal zone has been increasing owing to the increased number of cars in Thailand since the 1950s. Polycyclic aromatic hydrocarbons (PAHs) increased in the layers corresponding to the 1950s and 1960s, probably because of the increased inputs of automobile-derived PAHs. PAH concentrations in the upper layers corresponding to the 1970s and later remained constant or increased. The absence of a subsurface maximum of PAHs contrasts with results observed in industrialized countries. This can be explained by the facts that the Thai economy did not depend on coal as an energy source in the 1960s and that economic growth has continued since the 1970s to the present. The deposition flux of PAHs and hopanes showed a dramatic offshore decrease, whereas that of LABs was uniform

  6. Water-quality trends in the Rio Grande/Rio Bravo Basin using sediment cores from reservoirs

    Science.gov (United States)

    Van Metre, Peter C.; Mahler, B.J.; Callender, Edward C.

    1997-01-01

    Water-quality trends reflect the relation between water quality and human activities, chronicling changes in concentrations of environmental contaminants, introduction of new contaminants, and successful efforts in environmental pollution remediation. Historical data available for analyzing trends often have severe limitations, from questionable accuracy to unknown sampling and analytic methodologies. Where data are unavailable or have such limitations, water-quality trends sometimes can be reconstructed using sediment cores from lakes and reservoirs.

  7. Application of sediment core modelling to interpreting the glacial-interglacial record of Southern Ocean silica cycling

    Directory of Open Access Journals (Sweden)

    A. Ridgwell

    2007-07-01

    Full Text Available Sediments from the Southern Ocean reveal a meridional divide in biogeochemical cycling response to the glacial-interglacial cycles of the late Neogene. South of the present-day position of the Antarctic Polar Front in the Atlantic sector of the Southern Ocean, biogenic opal is generally much more abundant in sediments during interglacials compared to glacials. To the north, an anti-phased relationship is observed, with maximum opal abundance instead occurring during glacials. This antagonistic response of sedimentary properties provides an important model validation target for testing hypotheses of glacial-interglacial change against, particularly for understanding the causes of the concurrent variability in atmospheric CO2. Here, I illustrate a time-dependent modelling approach to helping understand climates of the past by means of the mechanistic simulation of marine sediment core records. I find that a close match between model-predicted and observed down-core changes in sedimentary opal content can be achieved when changes in seasonal sea-ice extent are imposed, whereas the predicted sedimentary response to iron fertilization on its own is not consistent with sedimentary observations. The results of this sediment record model-data comparison supports previous inferences that the changing cryosphere is the primary driver of the striking features exhibited by the paleoceanographic record of this region.

  8. Final report on the sampling and analysis of sediment cores from the L-Area oil and chemical basin

    Energy Technology Data Exchange (ETDEWEB)

    1985-08-01

    Nine vibracores were collected in the L-Area oil and chemical basin (904-83G) during late March and early April 1985. These cores were collected for analysis of the sludge on the basin floor and the underlying sediment. Several different field and laboratory analyses were performed on each three inch segment of all the cores. These included: (1) Sediment characterization; (2) Percent moisture; (3) Dry weight; (4) Spectral gamma analysis; (5) Gross alpha and beta analysis. Detailed chemical analysis were measured on selected intervals of 2 cores (LBC-5 and 6) for complete chemical characterization of the sediments. This sampling program was conducted to provide information so that a closure plan for the basin could be developed. This report describes the methods employed during the project and provide a hard copy of the analytical results from the sample analyses. Included in the appendices are copies of all field and laboratory notes taken during the project and copies of the gas chromatograms for the petroleum hydrocarbon analysis. All chemical results were also submitted on a 5-inch floppy disk.

  9. PAHs in sediment cores at main river estuaries of Chaohu Lake: implication for the change of local anthropogenic activities.

    Science.gov (United States)

    Ren, Chen; Wu, Yaketon; Zhang, Shuo; Wu, Liang-Liang; Liang, Xiao-Guo; Chen, Tian-Hu; Zhu, Cheng-Zhu; Sojinu, Samuel O; Wang, Ji-Zhong

    2015-02-01

    In the present study, 28 polycyclic aromatic hydrocarbons (PAHs) were investigated in four sediment cores collected from the main river estuaries of Chaohu Lake, one of the severely polluted lakes in China. The results indicate that elevated concentrations of total PAHs (Σ28PAH) were found in the samples from the estuary of Nanfei River (ENF), considering BaP-based total toxicity equivalent (TEQ-BaP) and toxic unit (TU) results; there are potential adverse environmental implications. The total organic carbon (TOC) played an important role on the accumulation of PAHs at ENF and the estuary of Tongyang River (ETY). The predominant PAHs are high molecular weight (HMW) homologous for all samples; as a result, industrial wastewater from a steel company is expectedly the key source of PAHs in ENF, while coke consumption would be the important source of PAHs at other three sampling sites. Vertical distribution of PAHs in the sediment cores could be explained by the local social and economic activities. Furthermore, a minor variation of PAH composition in the sediment core could be justified by the stable structure of energy consumption in the Anhui Province. These results justify the need for further enhancement of industrial wastewater treatment and development of renewable energies which are the key factors on the control of PAH pollution in China.

  10. Distribution of Trace Elements in Core Marine Sediments of Coastal East Malaysia by Instrumental Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Ashraf, Ahmadreza; Saion, Elias; Gharibshahi, Elham; Kamari, Halimah Mohamed; Yap, Chee Kong; Hamzah, Mohd Suhaimi; Elias, Md Suhaimi

    2017-01-01

    A study was carried out on the distribution and enrichment of trace elements in the core marine sediments of East Malaysia from three stations at South China Sea and one station each at Sulu Sea and Sulawesi Sea. Five stations of sediment cores were recovered and the vertical concentration profiles of six elements namely Br, Cs, Hf, Rb, Ta, and V were determined using the instrumental neutron activation analysis. The enrichment factor, geoaccumulation index and the modified degree of contamination were used to calculate the anthropogenic and pollution status of the elements in the samples. Except for Cs and Hf, which by the enrichment factor are categorized from minimum enrichment to moderate enrichment in all stations and for V and Rb in Sulu Sea and Sulawesi Sea, which are categorized minimum enrichment, other elements are found to be no enrichment at all stations. The geoaccumulation index of Hf in one station shows moderately polluted and for other elements are unpolluted. However, the modified degree values of all samples are less than 1, suggesting very low contamination of elements found in all the stations. - Highlights: • Measurement of trace elements distribution in the Malaysian East core marine sediment by INAA. • Standard reference materials were used as quality control of analytical procedure. • Assessment of pollution based on EF of related elements to the average shale. • Determine the contamination status of trace elements with the modified degree of contamination. • Evaluation of pollution status by I geo calculation.

  11. Modern sedimentation patterns in Lake El'gygytgyn, NE Russia, derived from surface sediment and inlet streams samples

    Directory of Open Access Journals (Sweden)

    V. Wennrich

    2013-01-01

    Full Text Available Lake El'gygytgyn/NE Russia holds a continuous 3.58 Ma sediment record, which is regarded as the most long-lasting climate archive of the terrestrial Arctic. Based on multi-proxy geochemical, mineralogical, and granulometric analyses of surface sediment, inlet stream and bedrock samples, supplemented by statistical methods, major processes influencing the modern sedimentation in the lake were investigated. Grain-size parameters and chemical elements linked to the input of feldspars from acidic bedrock indicate a wind-induced two-cell current system as major driver of sediment transport and accumulation processes in Lake El'gygytgyn. The distribution of mafic rock related elements in the sediment on the lake floor can be traced back to the input of weathering products of basaltic rocks in the catchment. Obvious similarities in the spatial variability of manganese and heavy metals indicate sorption or co-precipitation of these elements with Fe and Mn hydroxides and oxides. But the similar distribution of organic matter and clay contents might also point to a fixation to organic components and clay minerals. An enrichment of mercury in the inlet streams might be indicative of neotectonic activity around the lake. The results of this study add to the fundamental knowledge of the modern lake processes of Lake El'gygytgyn and its lake-catchment interactions, and thus, yield crucial insights for the interpretation of paleo-data from this unique archive.

  12. Acquiring Sediment and Element Compositional Changes Based on a Diffuse Reflectance Spectrophotometry Technology from Cores Offshore Southwestern Taiwan

    Science.gov (United States)

    Pan, H. J.; Chen, M. T.

    2014-12-01

    Heavy summer monsoon rainfall along with typhoon-induced extreme precipitation cause frequent geological hazards that often threaten the human's safety and property in Taiwan. These geological hazards can be triggered by both natural factors, and/or have become deteriorated by perturbations from more and more human activities ever since few thousand years ago. However, due to the limit of instrumental records for observing long-term environmental changes in Taiwan, few evidence exist for distinguishing the human-induced impacts from natural climate change. Here we report a study on a high quality marine sediment core (MD103264) which were retrieved from the high sedimentation rate area from offshore southwestern Taiwan and present evidence for the long-term climate and possibly human-induced environmental changes since the last glacial. We are using the VIS-NIR Diffuse Reflectance Spectrophotometry (DRS) methods to study the cores. Interpreting the VIS-NIR reflectance spectra through the VARIMAX-rotation, principle component analysis (VPCA) helps conducting rapid and inexpensive measurements for acquiring high-resolution biogenic component, clay, and iron oxide mineral compositional data from the cores. We are also using X-Ray Fluorescence (XRF) analysis, which is also useful in determining the element compositional changes in the core. Our studies aim toward understanding the sediment and element compositional changes that reflect the patterns of changes in precipitation and soil erosion on land since the last glacial to the Holocene, during which the human activities (deforestation, agriculture, and land uses change) may have increased drastically. We will report and interpret the preliminary results of the optical analyses of the core.

  13. Environmental and geochemical assessment of surface sediments on irshansk ilmenite deposit area

    Directory of Open Access Journals (Sweden)

    Наталия Олеговна Крюченко

    2015-03-01

    Full Text Available It is revealed the problem of pollution of surface sediments of Irshansk ilmenite deposit area of various chemical elements hazard class (Mn, V, Ba, Ni, Co, Cr, Mo, Cu, Pb, Zn. It is determined its average content in surface sediments of various functional areas (forest and agricultural land, flood deposits, reclaimed land, calculated geochemical criteria, so given ecological and geochemical assessment of area

  14. Investigation of mechanical properties of hydrate-bearing pressure core sediments recovered from the Eastern Nankai Trough using transparent acrylic cell triaxial testing system (TACTT-system)

    Science.gov (United States)

    Yoneda, J.; Masui, A.; Konno, Y.; Jin, Y.; Kida, M.; Suzuki, K.; Nakatsuka, Y.; Tenma, N.; Nagao, J.

    2014-12-01

    Natural gas hydrate-bearing pressure core sediments have been sheared in compression using a newly developed Transparent Acrylic Cell Triaxial Testing (TACTT) system to investigate the geophysical and geomechanical behavior of sediments recovered from the deep seabed in the Eastern Nankai Trough, the first Japanese offshore production test region. The sediments were recovered by hybrid pressure core system (hybrid PCS) and pressure cores were cut by pressure core analysis tools (PCATs) on board. These pressure cores were transferred to the AIST Hokkaido centre and trimmed by pressure core non-destructive analysis tools (PNATs) for TACTT system which maintained the pressure and temperature conditions within the hydrate stability boundary, through the entire process of core handling from drilling to the end of laboratory testing. An image processing technique was used to capture the motion of sediment in a transparent acrylic cell, and digital photographs were obtained at every 0.1% of vertical strain during the test. Analysis of the optical images showed that sediments with 63% hydrate saturation exhibited brittle failure, although nonhydrate-bearing sediments exhibited ductile failure. In addition, the increase in shear strength with hydrate saturation increase of natural gas hydrate is in agreement with previous data from synthetic gas hydrate. This research was financially supported by the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) that carries out Japan's Methane Hydrate R&D Program by the Ministry of Economy, Trade and Industry (METI).

  15. Lead isotope ratios in six lake sediment cores from Japan Archipelago: Historical record of trans-boundary pollution sources

    Energy Technology Data Exchange (ETDEWEB)

    Hosono, Takahiro, E-mail: hosono@kumamoto-u.ac.jp [Priority Organization for Innovation and Excellence, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Alvarez, Kelly [Priority Organization for Innovation and Excellence, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Kuwae, Michinobu [Senior Research Fellow Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577 (Japan)

    2016-07-15

    Sediment cores from six lakes situated from north to south on the Japanese Archipelago were collected during 2009–2010 to investigate the hypothesis that deposition of lead (Pb) was coming from East Asia (including China, South Korea and eastern part of Russia). Accumulation rates and ages of the lake sediment were estimated by the {sup 210}Pb constant rate of supply model and {sup 137}Cs inputs to reconstruct the historical trends of Pb accumulation. Cores from four lakes located in the north and central Japan, showed clear evidence of Pb pollution with a change in the {sup 206}Pb/{sup 207}Pb and {sup 208}Pb/{sup 207}Pb ratios in the recent sediment as compared to the deeper sediment. Among the six studied lakes, significant inputs of anthropogenic lead emissions were observed at Lake Mikazuki (north Hokkaido in north Japan), Lake Chokai (north of Honshu), and Lake Mikuriga (central part of Honshu). Pb isotopic comparison of collected core sediment and previously reported data for wet precipitation and aerosols from different Asian regions indicate that, before 1900, Pb accumulated in these three lakes was not affected by trans-boundary sources. Lake Mikazuki started to receive Pb emissions from Russia in early 1900s, and during the last two decades, this lake has been affected by trans-boundary Pb pollution from northern China. Lake Chokai has received Pb pollutant from northern China since early 1900s until 2009, whereas for the Lake Mikuriga the major Pb contaminant was transported from southern China during the past 100 years. The results of our study demonstrate that Japan Archipelago has received trans-boundary Pb emissions from different parts of East Asian region depending on location, and the major source region has changed historically. - Highlights: • Historical trend of Pb pollution was recorded in six Japanese Lakes. • Pb concentration and Pb isotope ratios were determined for sediment cores. • High [Pb] and less radiogenic Pb isotope ratios

  16. Effects of engineered nano-titanium dioxide on pore surface properties and phosphorus adsorption of sediment: Its environmental implications

    International Nuclear Information System (INIS)

    Luo, Zhuanxi; Wang, Zhenhong; Wei, QunShan; Yan, Changzhou; Liu, Feng

    2011-01-01

    Highlights: → The attachment of Enano-TiO 2 to surface enhanced markedly sediment BET surface area and t-Plot external surface area. → The fill of Enano-TiO 2 into the micropores reduced significantly the sediment t-Plot micropore surface area. → Enano-TiO 2 could increase sediment phosphorus (P) adsorption maximum and decrease in sediment P binding energy. → P would be easily released because of the decreasing P binding energy of the sediment with elevated Enano-TiO 2 . - Abstract: Understanding the environmental safety and human health implications of engineered nanoparticles (ENPs) is of worldwide importance. As an important ENPs, engineered nano-TiO 2 (Enano-TiO 2 ) may have been substantially deposited in aquatic sediments because of its widely uses. Sediment pore surface properties would be thus significantly influenced due to the large surface area of Enano-TiO 2 . In this study, Enano-TiO 2 was found to greatly impact on sediment pore surface properties. The attachment of Enano-TiO 2 particles to sediment surfaces enhanced markedly BET specific surface area and t-Plot external specific surface area, and thereby increased sediment phosphorus (P) adsorption maximum (S max ). Contrarily, the fill of Enano-TiO 2 particles into the micropores of sediments could significantly reduce t-Plot micropore specific surface area, and cause slight decrease in sediment P binding energy (K). Clearly, P sorbed in sediment would be easily released because of the decreasing P binding energy of the sediment with elevated Enano-TiO 2 . Enano-TiO 2 would thus cause aggravated endogenous pollution in water if such sediment was re-suspended on disturbance. The results obtained in this study contribute to our increasing knowledge of how to regulate physicochemical behavior of pollutants in sediments under the influences of Enano-TiO 2 and/or similar ENPs.

  17. Palynological analysis of a sediment core obtained in Guanabara Bay, Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    Cintia F. Barreto

    2007-06-01

    Full Text Available The sediment of a core collected about 2 km north of Paquetá Island, Guanabara Bay, was submitted to pollen analysis, in order to recognize the dynamics of the regional vegetation, and the anthropic influence. Radiocarbon dating of a sample next to the bottom of the core indicates an age of 4.210 ± 40 14C yrs B.P (calibrated age. It was possible to establish four palynological zones. Starting at the bottom of the core, a decrease in palynomorph concentration, the presence of degraded pollen grains and spores, and the predominance of ombrophilous forest pollen grains were observed in the basal portion of Zone I. These data may indicate the presence of an exuberant Atlantic Forest, dominated by a marine regressive event. The concentration of well-preserved palynomorphs increased in Zone II, with the predominance of the ombrophilous forest vegetation also, and an expressive increase of hygrophytes, indicating more humid environmental conditions. Palynomorph concentration decreased again toward the top of Zone III, and the field vegetation was predominant. In the upper Zone IV occurred a strong decrease in pollen and spore concentration, with predominance of field vegetation also, and the appearance of exotic pollen grains, showing the anthropic influence at this time.Sedimentos de um testemunho de sondagem coletado a 2 km ao norte da Ilha de Paquetá, Baía de Guanabara foram submetidos à análise palinológica, com o objetivo de reconhecer e interpretar a dinâmica temporal da vegetação na região e a influência antrópica. A datação radiocarbônica realizada próxima à base do testemunho indicou uma idade de 4.210 ± 40 anos AP (idade calibrada. Os resultados possibilitaram determinar quatro zonas palinológicas. Na Zona I, a mais basal, observou-se o decréscimo da concentração total de palinomorfos em direção ao topo e elevada deposição de grãos de pólen e esporos degradados, com o predomínio de grãos de pólen concernentes

  18. Application of the alpha spectrometry for the study of core sediment extracted in the San Marcos dam in Chihuahua

    International Nuclear Information System (INIS)

    Mendez G, C.; Renteria V, M.; Montero C, M. E.; Garcia T, R.

    2012-01-01

    The determination of the specific activities of 210 Po and isotopic uranium by alpha spectrometry was performed in a sediment core from San Marcos Dam. The objective of this work was to analyze the vertical distribution of isotopic uranium and 210 Po and the behavior of these radionuclides along sediment core collected from the San Marcos Dam. Sample was divided into 11 sections, in which 210 Po and isotopic uranium were determined using liquid-liquid extraction with tributyl phosphate. Furthermore, it was made a comparison between the tributyl phosphate technique and the technique of extraction chromatography using UTEVA resins for uranium. The results of specific activities for 210 Po show a trend to decrease along the core, whereas the uranium isotopic does not show a pointed trend. The results of isotopic ratios between the 234 U and 238 U show that they are close to secular equilibrium in each of the core sections. The comparison between the two uranium extraction techniques indicates that the chemical yield is better using the UTEVA technique than tributyl phosphate extraction. (Author)

  19. Application of the alpha spectrometry for the study of core sediment extracted in the San Marcos dam in Chihuahua

    Energy Technology Data Exchange (ETDEWEB)

    Mendez G, C.; Renteria V, M.; Montero C, M. E. [Centro de Investigacion en Materiales Avanzados, S. C., Miguel de Cervantes No. 120, Complejo Industrial Chihuahua, 31109 Chihuahua (Mexico); Garcia T, R., E-mail: elena.montero@cimav.edu.mx [Universidad de Sevilla, Escuela Tecnica Superior de Arquitectura, Grupo de Fisica Nuclear Aplicada, Av. Reina Mercedes s/n, 41012 Sevilla (Spain)

    2012-06-15

    The determination of the specific activities of {sup 210}Po and isotopic uranium by alpha spectrometry was performed in a sediment core from San Marcos Dam. The objective of this work was to analyze the vertical distribution of isotopic uranium and {sup 210}Po and the behavior of these radionuclides along sediment core collected from the San Marcos Dam. Sample was divided into 11 sections, in which {sup 210}Po and isotopic uranium were determined using liquid-liquid extraction with tributyl phosphate. Furthermore, it was made a comparison between the tributyl phosphate technique and the technique of extraction chromatography using UTEVA resins for uranium. The results of specific activities for {sup 210}Po show a trend to decrease along the core, whereas the uranium isotopic does not show a pointed trend. The results of isotopic ratios between the {sup 234}U and {sup 238}U show that they are close to secular equilibrium in each of the core sections. The comparison between the two uranium extraction techniques indicates that the chemical yield is better using the UTEVA technique than tributyl phosphate extraction. (Author)

  20. Centennial-scale records of total organic carbon in sediment cores from the South Yellow Sea, China

    Science.gov (United States)

    Zhu, Qing; Lin, Jia; Hong, Yuehui; Yuan, Lirong; Liu, Jinzhong; Xu, Xiaoming; Wang, Jianghai

    2018-01-01

    Global carbon cycling is a significant factor that controls climate change. The centennial-scale variations in total organic carbon (TOC) contents and its sources in marginal sea sediments may reflect the influence of human activities on global climate change. In this study, two fine-grained sediment cores from the Yellow Sea Cold Water Mass of the South Yellow Sea were used to systematically determine TOC contents and stable carbon isotope ratios. These results were combined with previous data of black carbon and 210Pb dating from which we reconstructed the centennial-scale initial sequences of TOC, terrigenous TOC (TOCter) and marine autogenous TOC (TOCmar) after selecting suitable models to correct the measured TOC (TOCcor). These sequences showed that the TOCter decreased with time in the both cores while the TOCmar increased, particularly the rapid growth in core H43 since the late 1960s. According to the correlation between the Huanghe (Yellow) River discharge and the TOCcor, TOCter, or TOCmar, we found that the TOCter in the two cores mainly derived from the Huanghe River and was transported by it, and that higher Huanghe River discharge could strengthen the decomposition of TOCmar. The newly obtained initial TOC sequences provide important insights into the interaction between human activities and natural processes.

  1. Sedimentology and geochemistry of surface sediments, outer continental shelf, southern Bering Sea

    Science.gov (United States)

    Gardner, J.V.; Dean, W.E.; Vallier, T.L.

    1980-01-01

    Islands and the outer continental shelf and slope, indicates that Holocene sediment dynamics cannot be used to explain the observed distribution of surface sediment derived from the Aleutian Islands. We suggest that this pattern is relict and resulted from sediment dynamics during lower sea levels of the Pleistocene. ?? 1980.

  2. Archive of Geosample Data and Information from the Ohio State University Byrd Polar and Climate Research Center (BPCRC) Sediment Core Repository

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Byrd Polar and Climate Research Center (BPCRC) Sediment Core Repository operated by the Ohio State University is a partner in the Index to Marine and Lacustrine...

  3. Pore-water chemistry of sediment cores off Mahanadi Basin, Bay of Bengal: Possible link to deep seated methane hydrate deposit

    Digital Repository Service at National Institute of Oceanography (India)

    Mazumdar, A.; Peketi, A.; Joao, H.M.; Dewangan, P.; Ramprasad, T.

    Organoclastic degradation and anaerobic oxidation of methane (AOM) are known to influence sulfate, methane and bicarbonate concentrations of sediment pore-waters. In this work we have analyzed the pore-fluid composition of three piston cores (36e39...

  4. Patterns and controls of surface sediment distribution: West-central Florida inner shelf

    Science.gov (United States)

    Brooks, G.R.; Doyle, L.J.; Davis, R.A.; DeWitt, N.T.; Suthard, B.C.

    2003-01-01

    The west-central Florida inner shelf represents a transition between the quartz-dominated barrier-island system and the carbonate-dominated mid-outer shelf. Surface sediments exhibit a complex distribution pattern that can be attributed to multiple sediment sources and the ineffectiveness of physical processes for large-scale sediment redistribution. The west Florida shelf is the submerged extension of the Florida carbonate platform, consisting of a limestone karst surface veneered with a thin unconsolidated sediment cover. A total of 498 surface sediment samples were collected on the inner shelf and analyzed for texture and composition. Results show that sediment consists of a combination of fine quartz sand and coarse, biogenic carbonate sand and gravel, with variable but subordinate amounts of black, phosphorite-rich sand. The carbonate component consists primarily of molluskan fragments. The distribution is patchy and discontinuous with no discernible pattern, and the transition between sediment types is generally abrupt. Quartz-rich sediment dominates the inner 15 km north of the entrance into Tampa Bay, but south of the Bay is common only along the inner 3 km. Elsewhere, carbonate-rich sediment is the predominate sediment type, except where there is little sediment cover, in which cases black, phosphorite-rich sand dominates. Sediment sources are likely within, or around the periphery of the basin. Fine quartz sand is likely reworked from coastal units deposited during Pleistocene sea-level high stands. Carbonate sand and gravel is produced by marine organisms within the depositional basin. The black, phosphorite-rich sand likely originates from the bioerosion and reworking of the underlying strata that irregularly crop out within the study area. The distribution pattern contains elements of both storm- and tide-dominated siliciclastic shelves, but it is dictated primarily by the sediment source, similar to some carbonate systems. Other systems with similar

  5. A Multiproxy Approach to Unraveling Climate and Human Demography in the Peruvian Altiplano from a 5000 year Lake Sediment Core

    Science.gov (United States)

    Vaught-Mijares, R. M.; Hillman, A. L.; Abbott, M. B.; Werne, J. P.; Arkush, E.

    2017-12-01

    Drought and flood events are thought to have shaped the ways in which Andean societies have adapted to life in the Titicaca Basin region, particularly with regard to land use practices and settlement patterns. This study examines a small lake in the region, Laguna Orurillo. Water isotopes suggest that the lake primarily loses water through evaporation, making it hydrologically sensitive. In 2015, a 3.4 m overlapping sediment record was collected and inspected for evidence of shallow water facies and erosional unconformities to reconstruct paleohydrology. Sediment core chronology was established using 7 AMS radiocarbon dates and 210Pb dating and indicates that the core spans 5000 years. Additional sediment core measurements include magnetic susceptibility, bulk density, organic/carbonate content, and XRD. Results show a pronounced change in sediment composition from brittle, angular salt deposits to massive calcareous silt and clay around 5000 years BP. Multiple transitions from clay to sand show potential lake level depressions at 1540, 2090, and 2230, yr BP that are supported by a drastic increase in carbonate composition from 2760-1600 yr BP. Additional shallow-water periods may be reflected in the presence of rip-up clasts from 4000 to 3000 yr BP. These early interpretations align well with existing hydrologic records from Lake Titicaca. In order to develop a more detailed climate and land use record, isotope analyses of authigenic carbonate minerals using δ13C and δ18O and leaf waxes using δD are being developed. Ultimately, this record will be linked with records from nearby Lagunas Arapa and Umayo. Additional proxies for human population such as fecal 5β-stanols and proximal anthropologic surveys will be synthesized to contribute to a regional understanding of Holocene climate variability and human demography in the Peruvian Altiplano.

  6. (210)Pb and composition data of near-surface sediments and interstitial waters evidencing anthropogenic inputs in Amazon River mouth, Macapá, Brazil.

    Science.gov (United States)

    Nery, José Reinaldo Cardoso; Bonotto, Daniel Marcos

    2011-04-01

    Activity profiles of excess (210)Pb determined in three sediment cores from Amazon River mouth, Macapá city, Brazil, provided the evaluation of sedimentation rates, contributing to a better knowledge of the hydrological conditions in the site that is the capital of Amapá State and is drained by the waters of the huge Amazon River. Chemical data were also determined in the sediments, allowing identify signatures coupled to anthropogenic inputs held in the past in Amapá State. Significant direct relationships between LOI (loss on ignition) and organic matter were found for all sediments profiles. Silica was found to be inversely related to organic matter in the three profiles; its decrease accompanied an increase on the specific surface of the sediments. This relationship was confirmed by a great number of inverse significant correlations among silica and oxides Na(2)O, K(2)O, CaO, MgO, Al(2)O(3), P(2)O(5), Fe(2)O(3) and MnO. It was possible to identify the role of organic matter on adsorption of several oxides in the core sediments profiles. Apparent sediment mass accumulation rates corresponding to values between 450 and 2510 mg cm(-2)yr(-1) were obtained, and are compatible with the results of others studies. The (210)Pb activities in one sampling point suggested the occurrence of anthropogenic inputs related to the initial period of the mining activities conducted in Serra do Navio, Amapá State, for the commercialization of Mn ores. This was reinforced by the abrupt fluctuations in chemical data obtained for the sediments and composition of the interstitial waters occurring there. The Atlantic hurricane activity also appeared to affect the sedimentation rates in the area, as two different values were recorded in each profile. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. 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...

  8. Soil, Groundwater, Surface Water, and Sediments of Kennedy Space Center, Florida: Background Chemical and Physical Characteristics

    Science.gov (United States)

    Shmalzer, Paul A.; Hensley, Melissa A.; Mota, Mario; Hall, Carlton R.; Dunlevy, Colleen A.

    2000-01-01

    This study documented background chemical composition of soils, groundwater, surface; water, and sediments of Kennedy Space Center. Two hundred soil samples were collected, 20 each in 10 soil classes. Fifty-one groundwater wells were installed in 4 subaquifers of the Surficial Aquifer and sampled; there were 24 shallow, 16 intermediate, and 11 deep wells. Forty surface water and sediment samples were collected in major watershed basins. All samples were away from sites of known contamination. Samples were analyzed for organochlorine pesticides, aroclors, chlorinated herbicides, polycyclic aromatic hydrocarbons (PAH), total metals, and other parameters. All aroclors (6) were below detection in all media. Some organochlorine pesticides were detected at very low frequencies in soil, sediment, and surface water. Chlorinated herbicides were detected at very low frequencies in soil and sediments. PAH occurred in low frequencies in soiL, shallow groundwater, surface water, and sediments. Concentrations of some metals differed among soil classes, with subaquifers and depths, and among watershed basins for surface water but not sediments. Most of the variation in metal concentrations was natural, but agriculture had increased Cr, Cu, Mn, and Zn.

  9. Analysis of Heavy Metals in Surface Sediments from Agh Gel Wetland, Iran

    Directory of Open Access Journals (Sweden)

    Soheil Sobhanardakani

    2016-06-01

    Full Text Available Background: Soil and sediment serve as major reservoir for contaminants as they possess ability to bind various chemicals together. In this study the concentrations of heavy metals Cd, Cr and Cu were analyzed in surface sediments of Agh Gel Wetland in west of Iran. Methods: The sediment samples were taken from 10 stations. The samples were subjected to bulk digestion and chemical partitioning and Cd, Cr and Cu concentrations of the sediments were determined by ICP-OES. Geo-accumulation index (I-geo, Contamination factor (CF and Pollution load index (PLI were used to evaluate the magnitude of contaminants in the sediment profile. Results: The mean sediment concentrations (mg kg-1 dry weight ranged within 0.20-0.29 (Cd, 58-71 (Cr and 23-36 (Cu. According to the I-geo values, the sediments' qualities are classified as unpolluted to moderately polluted category. According to the CF values, the sediments' qualities are classified as low to moderate contamination. Furthermore, the PLI values indicated that there were no metal pollution exists for all sampling stations. Conclusion: The Agh Gel Wetland is potential to be threatened by chemical pollutants such as agricultural effluent. So to preserve the environment of the Agh Gel Wetland from deterioration, periodically monitoring of the water and sediment qualities is recommended.

  10. Geochemistry and particle size of surface sediments of Gulf of Manfredonia (Southern Adriatic sea)

    Science.gov (United States)

    Spagnoli, F.; Bartholini, G.; Dinelli, E.; Giordano, P.

    2008-10-01

    In this study we describe mechanisms influencing the spatial distribution of the surface sediments in the Gulf of Manfredonia. Seventy-three samples were collected on a regional grid and analyzed for grain-size, major and trace elements and organic matter content. Sediments contain marine-derived carbonate as well as terrigenous fractions indicating highly heterogeneous sediment composition dictated by different provenance and complex transport processes. Principal Component Analysis provides information about processes involved in the formation and dispersal of the sediments. The regional sediment distribution is function of the Gulf's morphology and sedimentary inputs from fluvial sources, mainly from the Ofanto River, and from the North and Central Adriatic basin. Biogenic carbonate reefs, identified in two restricted coastal areas add complexity to sediment shelf dispersal. The North-Adriatic current flowing southward transports and deposits sediments from the Northern basin in the offshore area of the Gulf while an inner anticyclonic current distributes and mixes northern and fluvial sediment with a clockwise pattern. In order to better assess the fluvial contribution also bedload samples from the main river debouching into the Gulf were sampled, enabling the identification of geochemical indexes to distinguish the role of both fluvial inputs and hydrodynamic processes affecting solid particles dispersion within the Gulf. This study provides a contribution to a qualitative estimate of the sediment supply entailed in the Southwestern Adriatic basin.

  11. Depositional record of trace metals and degree of contamination in core sediments from the Mandovi estuarine mangrove ecosystem, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Veerasingam, S.; Vethamony, P.; ManiMurali, R.; Fernandes, B.

    of sources. Enrichment of metals in bottom sediments represents a critical measure of health for any mangrove ecosystem (Janaki-Raman et al., 2007). Trace metals in coastal and estuarine sediments are incorporated into the aquatic food webs through primary... Version: Mar. Pollut. Bull., vol.91(1); 2015; 362-367 Depositional record of trace metals and degree of contamination in core sediments from the Mandovi estuarine mangrove ecosystem, west coast of India S. Veerasingam, P. Vethamony*, R. Mani Murali...

  12. Radiolarian abundance and geochemistry of the surface-sediments from the Central Indian Basin: Inferences to Antarctic bottom water current

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, S.M.; Jauhari, P.

    The distribution trend of numbers of radiolarian shells/gram dry sediment, biogenic silica, organic carbon, and the carbon/nitrogen ratios in the surface sediments of the Central Indian Basin is similar. Ratios of two suborders of radiolaria, i...

  13. Long-term Records of Trace Metal Elements in Core Sediments: Anthropogenic Impacts in The Eure River Watershed

    Science.gov (United States)

    Gardes, T.; Debret, M.; Copard, Y.; Patault, E.; Deloffre, J.; Marcotte, S.; Develle, A. L.; Sabatier, P.; Chaumillon, E.; Coulombier, T.; Revillon, S.; Nizou, J.; Laberdesque, Y.; Koltalo, F.

    2017-12-01

    The Martot Dam is located in the Eure River Watershed (Normandy, France), few hundred meters upstream the Eure-Seine Rivers confluence. In the context of the European Water Framework Directive (2000/60/EC), the French Authorities planned to remove this dam in 2017. Nevertheless, impacts of the removal remain poorly studied. Classically, dam blocked sedimentary transfers downstream, but here, sediments are not blocked behind the dam but stored three hundred meters upstream in a hydraulic annex, called the Martot Pond. Furthermore, this pond is submitted to the tidal flow from the Seine Estuary despite the Martot Dam. The aim of the study is to evaluate the dam removal impacts on sedimentary transfers and re-suspension of contaminated sediments stored in the Martot Pond and the Eure River's channel. Concerning past transfers and sediments accumulation in the Eure River Watershed, sedimentary archives have been cored, before dam removal, at the Martot Pond and the Les Damps Pond (located 10km upstream the latter). Dating of sedimentary cores for both ponds indicates a sedimentation rate around 1 cm y-1. Trace metal elements quantification showed a wide metallic contamination with highest concentrations evidenced during the 1950-1960's (As: 13-22 mg kg-1; Cd: 40-55 mg kg-1; Cr: 170-210 mg kg-1; Cu: 400-490 mg kg-1; Hg: 2.3 mg kg-1; Mn: 1,280-2,200 mg kg-1; Ni: 64-75 mg kg-1; Zn: 905-990 mg kg-1) and the 1990-2000's (Cr: 95-215 mg kg-1; Ni: 100 mg kg-1; Pb: 670-855 mg kg-1). These variations of concentrations along cores can be associated with industrial past of the Eure River Watershed and sources of contamination can be identified. Thereby, Zn, Ni or Hg contamination could be associated with wastes of battery factory released in the Eure River during the economic recovery, while Pb contamination is linked to the activities of a cathode-ray tubes factory. Metals quantification in core materials highlighted anthropogenic impacts in the Eure River Watershed. These

  14. A synthesis of marine sediment core δ13C data over the last 150 000 years

    Directory of Open Access Journals (Sweden)

    R. E. M. Rickaby

    2010-10-01

    Full Text Available The isotopic composition of carbon, δ13C, in seawater is used in reconstructions of ocean circulation, marine productivity, air-sea gas exchange, and biosphere carbon storage. Here, a synthesis of δ13C measurements taken from foraminifera in marine sediment cores over the last 150 000 years is presented. The dataset comprises previously published and unpublished data from benthic and planktonic records throughout the global ocean. Data are placed on a common δ18O age scale suitable for examining orbital timescale variability but not millennial events, which are removed by a 10 ka filter. Error estimates account for the resolution and scatter of the original data, and uncertainty in the relationship between δ13C of calcite and of dissolved inorganic carbon (DIC in seawater. This will assist comparison with δ13C of DIC output from models, which can be further improved using model outputs such as temperature, DIC concentration, and alkalinity to improve estimates of fractionation during calcite formation. High global deep ocean δ13C, indicating isotopically heavy carbon, is obtained during Marine Isotope Stages (MIS 1, 3, 5a, c and e, and low δ13C during MIS 2, 4 and 6, which are temperature minima, with larger amplitude variability in the Atlantic Ocean than the Pacific Ocean. This is likely to result from changes in biosphere carbon storage, modulated by changes in ocean circulation, productivity, and air-sea gas exchange. The North Atlantic vertical δ13C gradient is greater during temperature minima than temperature maxima, attributed to changes in the spatial extent of Atlantic source waters. There are insufficient data from shallower than 2500 m to obtain a coherent pattern in other ocean basins. The data synthesis indicates that basin-scale δ13C during the last interglacial (MIS 5e is not clearly distinguishable from the Holocene (MIS 1 or from MIS 5a and 5c, despite significant differences in ice volume and atmospheric CO2

  15. [Surface physicochemical and fractal characteristics of sediments in desilting basin from Yellow River diversion reservoir].

    Science.gov (United States)

    Hu, Kang-Bo; Wang, Yi-Li; Li, Jun-Qing; Gui, Ping; Jiang, Yan-Ling

    2011-07-01

    Surface morphology and pore surface fractal characteristics of the sediment in the desilting basin of Queshan Reservoir were studied. Six sediment samples were collected and particle size, morphology, pore structure and fractal characteristics, surface elements distribution were analyzed as well. The objectives of this study were to investigate the reason for the differences among the pore surface fractal dimensions and fractal scales on the basis of different models, and discuss the effect of surface morphology of these sediment particles on their surface elements distribution. The results showed that these sediment particles with average diameter of 18-83 microm were mainly composed of clay, silt and fine sand. Their complex surface morphology and pore size distribution were reflected by wide range of the BET surface area (8.248-31.60 m2/g), average pore diameter (3.977-7.850 nm) and pore-size distribution (1.870-60.78 nm). Although the pore surface fractal dimensions (D(s)), based on fractal FHH or thermodynamic models, were 2.67-2.89, and their fractal scales generally ranged from several nanometers to tens of nanometers, the differences were still observed in D(s) values calculated from above two models because of inhomogeneity in surface pore size distribution. Therefore, the D(s) based on pore-size distribution were 2.12-2.60, these values close to D(s) calculated from fractal FHH models revealed that pore-size distribution could contribute significantly to D(s) calculation. In addition, the heterogeneous surface adsorption sites of these sediment particles caused by much complex surface morphology had strong influence on the each element distribution on the particle surface.

  16. Watershed trend analysis and water-quality assessment using bottom-sediment cores from Cheney Reservoir, south-central Kansas

    Science.gov (United States)

    Pope, Larry M.

    1998-01-01

    An examination of Cheney Reservoir bottom sediment was conducted in August 1997 to describe long-term trends and document the occurrence of selected constituents at concentrations that may be detrimental to aquatic organisms. Average concentrations of total phosphorus in bottom-sediment cores ranged from 94 to 674 milligrams per kilogram and were statistically related to silt- and (or) clay-size particles. Results from selected sampling sites in Cheney Reservoir indicate an increasing trend in total phosphorus concentrations. This trend is probably of nonpoint-source origin and may be related to an increase in fertilizer sales in the area, which more than doubled between 1965 and 1996, and to livestock production. Few organochlorine compounds were detected in bottom-sediment samples from Cheney Reservoir. DDT, its degradation products DDD and DDE, and dieldrin had detectable concentrations in the seven samples that were analyzed. DDT and DDD were each detected in one sample at concentrations of 1.0 and 0.65 microgram per kilogram, respectively. By far, the most frequently detected organochlorine insecticide was DDE, which was detected in all seven samples, ranging in concentration from 0.31 to 1.3 micrograms per kilogram. A decreasing trend in DDE concentrations was evident in sediment-core data from one sampling site. Dieldrin was detected in one sample from each of two sampling sites at concentrations of 0.21 and 0.22 micrograms per kilogram. Polychlorinated biphenyls were not detected in any bottom-sediment sample analyzed. Selected organophosphate, chlorophenoxy-acid, triazine, and acetanilide pesticides were analyzed in 18 bottom-sediment samples. Of the 23 pesticides analyzed, only the acetanilide herbicide metolachlor was detected (in 22 percent of the samples). Seven bottom-sediment samples were analyzed for major metals and trace elements. The median and maximum concentrations of arsenic and chromium, the maximum concentration of copper, and all

  17. Heavy metal concentrations in the surface marine sediments of Sfax Coast, Tunisia.

    Science.gov (United States)

    Gargouri, Dorra; Azri, Chafai; Serbaji, Mohamed Moncef; Jedoui, Younes; Montacer, Mabrouk

    2011-04-01

    Sixty-seven surface marine sediment samples in the Sfax (Tunisia) were analyzed by inductively coupled plasma-atomic emission spectrometry for seven heavy metals (Pb, Ni, Cu, Cr, Zn, Cd, and Fe). Metal concentrations were compared with natural values, marine sediment quality standards, and also with other results concerning sediments from several Mediterranean coasts. The study of their spatial distributions refined by complementary approaches including principal component analysis, enrichment factors, and geoaccumulation index showed a significant impact of multiple anthropogenic sources. These included industrial sources and municipal discharges of the urban Sfax and also non-controlled discharges in rural zones close to the coastline. Moderate pollution of sediments, especially by Pb, Zn, and Ni, was shown to exist in localized sites. Besides, it was shown that other sites, slightly to highly enriched in terms of Cu, Cr, and Cd, are characterized by a quality of sediments varying from unpolluted to moderately polluted.

  18. Microplastics Baseline Surveys at the Water Surface and in Sediments of the North-East Atlantic

    Directory of Open Access Journals (Sweden)

    Thomas Maes

    2017-05-01

    Full Text Available Microplastic contamination was determined in sediments of the Southern North Sea and floating at the sea surface of North West Europe. Floating concentrations ranged between 0 and 1.5 microplastic/m3, whereas microplastic concentrations in sediments ranged between 0 and 3,146 particles/kg dry weight sediment. In sediments, mainly fibers and spheres were found, whereas at the sea surface fragments were dominant. At the sea surface, concentrations of microplastics are lower and more variable than in sediments, meaning that larger sample sizes and water volumes are required to find detectable concentrations. We have calculated the widths of the confidence intervals (CI for different sample sizes, to give a first indication of the necessary sample size for a microplastic survey at the water surface. Higher concentrations of floating microplastics were found near estuaries. In sediments, estuaries and areas with a high organic carbon content were likely hotspots. Standardization of monitoring methods within marine regions is recommended to compare and assess microplastics pollution over time.

  19. SedCT: MATLAB™ tools for standardized and quantitative processing of sediment core computed tomography (CT) data collected using a medical CT scanner

    Science.gov (United States)

    Reilly, B. T.; Stoner, J. S.; Wiest, J.

    2017-08-01

    Computed tomography (CT) of sediment cores allows for high-resolution images, three-dimensional volumes, and down core profiles. These quantitative data are generated through the attenuation of X-rays, which are sensitive to sediment density and atomic number, and are stored in pixels as relative gray scale values or Hounsfield units (HU). We present a suite of MATLAB™ tools specifically designed for routine sediment core analysis as a means to standardize and better quantify the products of CT data collected on medical CT scanners. SedCT uses a graphical interface to process Digital Imaging and Communications in Medicine (DICOM) files, stitch overlapping scanned intervals, and create down core HU profiles in a manner robust to normal coring imperfections. Utilizing a random sampling technique, SedCT reduces data size and allows for quick processing on typical laptop computers. SedCTimage uses a graphical interface to create quality tiff files of CT slices that are scaled to a user-defined HU range, preserving the quantitative nature of CT images and easily allowing for comparison between sediment cores with different HU means and variance. These tools are presented along with examples from lacustrine and marine sediment cores to highlight the robustness and quantitative nature of this method.

  20. Ecosystem history of southern and central Biscayne Bay; summary report on sediment core analyses

    Science.gov (United States)

    Wingard, G.L.; Cronin, T. M.; Dwyer, G.S.; Ishman, S.E.; Willard, D.A.; Holmes, C.W.; Bernhardt, C.E.; Williams, C.P.; Marot, M.E.; Murray, J.B.; Stamm, R.G.; Murray, J.H.; Budet, C.

    2003-01-01

    of inter-decadal salinity extremes or periods of hypersalinity. o\tFreshwater and mesohaline salinities have had a minor influence on No Name bank throughout the time of deposition. At Featherbed Bank, the influence is reduced to mesohaline salinities. ?\tCard Bank has experienced relatively large swings in salinity over multi-decadal and centennial timescales, compared to central Biscayne Bay, but marine influence at the site has increased over the last century. ?\tIndications of regional scale patterns have been found, especially in the shell chemistry data and the pollen assemblages. These regional patterns indicate that the changes are not site specific and may not be limited to Biscayne Bay. ?\tSub-aquatic vegetation has undergone bay-wide patterns of change over the last 200-500 years, which includes expansion prior to 1900 and declines during the last century in central Biscayne Bay. o\tThalassia appears to have increased at all three core sites sometime between 1550 and 1750 AD. o\tA decline in Thalassia appears to have occurred after 1950 at No Name Bank and slightly earlier in the 20th century at Featherbed Bank. o\tCard Bank does not appear to have experienced any declines in vegetation on an inter-decadal scale during the 20th century. ?\tMolluscan faunal abundance and diversity have undergone significant changes in central Biscayne Bay. ?\tIndicators of increased organic-rich sediments at No Name occur between 1869 to 1888 and between the 1930's to 1975. These changes may correlate to human activities (settlement, population growth). These findings represent a first step towards the project's goal to reconstruct the history of Biscayne Bay and they provide us with a working model to be tested at other sites. It is clear from our findings that Biscayne Bay has been a dynamic environment over the last 500 years, with natural changes occurring in salinity and benthic habitats. However, several significant changes have occurred in the 20th ce

  1. Characteristics and Distribution of Phosphorus in Surface Sediments of Limnetic Ecosystem in Eastern China.

    Directory of Open Access Journals (Sweden)

    Wenqiang Zhang

    Full Text Available Phosphorus (P is an essential nutrient for aquatic organisms; however, excessive P inflow to limnetic ecosystems can induce eutrophication. P concentrations in the rivers, wetlands and lakes of Eastern China have been amplified by fertilizer and sewage inputs associated with the development of industry and agriculture. Yet, knowledge of the distribution and speciation of P is lacking at the regional scale. We determined the distribution and speciation of P in limnetic ecosystems in Eastern China using Standards, Measurements and Testing (SMT and phosphorus nuclear magnetic resonance (31P-NMR. The results indicate that P pollution in surface sediments was serious. Inorganic P (Pi was the primary drive of variation in total P (TP among different river systems, and Pi accounted for 71% to 90% of TP in surface sediment in Eastern China. Also, the concentrations of TP and Pi varied among watersheds and Pi primarily drove the variation in TP in different watersheds. Sediments less than 10-cm deep served as the main P reservoir. Environmental factors affect the speciation and origin of P. NaOH-Pi, HCl-Pi and organic P (Po were related to pH accordingly at the regional scale. The physicochemical properties of sediments from different limnetic ecosystems affect the P speciation. HCl-Pi was higher in wetland sediments than in riverine and lake sediments in Eastern China. Conversely, NaOH-Pi was lowest in wetland sediments. Total Po concentration was lower in riverine sediments than in other sediments, but Mono-P was higher, with an average concentration of 48 mg kg-1. Diesters-P was highest in lake sediments. By revealing the regional distribution of TP, Pi and Po, this study will support eutrophication management in Eastern China.

  2. Spatial and temporal variation of heavy metals in sediment cores from the Calcasieu River/Lake Complex

    International Nuclear Information System (INIS)

    Mueller, C.S.; Ramelow, G.J.; Beck, J.N.

    1987-01-01

    Sediment cores were obtained from several locations in the Calcasieu River/Lake Complex, including Calcasieu Lake, Calcasieu River, two bayou tributaries, and Lake Charles during the period from November 1983 to November 1985. The cores were analyzed for Cu, Zn, Cr, and Pb. The approximate sedimentation rate and a core chronology were determined by the use of 137 Cs and 210 Pb isotopes. The increase in metal concentrations after 1933, particularly along Bayou d'Inde where most industries are located, points to anthropogenic input if these metals to the system. The fact that metal concentrations tend to merge to a common value prior to 1940 throughout the system suggests that geological factors do not contribute to the observed variations in metal concentrations in this area. The background concentrations of heavy metals found in this study for the Calcasieu River/Lake Complex were: Cu (10 mg kg -1 ), Cr (25 mg kg -1 ), Pb (8 mg kg -1 ), and Zn (40 mg kg -1 ). The main emphasis of the study focused along Bayou d'Inde due to the enhanced levels of heavy metals found

  3. Stratigraphy and AMS radiocarbon dates of cored sediments (IrBH-2) from the Irosin caldera, the Philippines

    International Nuclear Information System (INIS)

    Mirabueno, Ma. Hannah T.; Laguerta, Eduardo P.; Delos Reyes, Perla J.; Bariso, Ericson B.; Torii, Masayuki; Fujiki, Toshiyuki; Okuno, Mitsuru; Nakamura, Toshio; Danhara, Tohru; Saito-Kokubu, Yoko; Kobayashi, Tetsuo

    2014-01-01

    Core drilling at Site IrBH-2 within the Irosin caldera in Sorsogon Province, southern Luzon reached a depth of 50 m. Systematic logging and documentation were carried out to describe and interpret the sediments. The accelerator mass spectrometer (AMS) radiocarbon dates obtained from plant fragments at 7.02-10.40-m depth were 1000 to 1800 BP. Lahars and fluvial deposits were the predominant deposits in the core sequence. The upper 12 m consisted mostly of andesitic fluvial and minor lahar deposits. These deposits may be correlated with the reworking of eruptive products from resurgent andesitic volcanism. One pyroclastic flow and 12 fallout deposits, including five possible fallout deposits, were intercalated with reworked sediments at depths of 12-50 m. The refractive index of representative samples indicated that post-caldera eruptions involved mainly andesite to dacite, with minor rhyolite magmas. The rhyolite fallout in the core had similar petrographic characteristics to the 41 cal kBP Irosin ignimbrite, suggesting that the fallout and the ignimbrite were sourced from the same magma. (author)

  4. Sulphur enrichment in a sediment core from the central western continental margin of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, P.S.; Rao, Ch.M.

    deposited in anoxic environment. Our study indicate that the excess sulphur is mainly due to the addition of sulphides from the shallow regions by mass sedimentation processes rather than water column sulphide formation as observed in anoxic environment...

  5. Sediment plume response to surface melting and supraglacial lake drainages on the Greenland ice sheet

    DEFF Research Database (Denmark)

    Chu, Vena W.; Smith, Laurence C; Rennermalm, Asa K.

    2009-01-01

    of a downstream sediment plume in Kangerlussuaq Fjord by comparing: (1) plume area and suspended sediment concentration from Moderate Resolution Imaging Spectroradiometer (MODIS) imagery and field data; (2) ice-sheet melt extent from Special Sensor Microwave/Imager (SSM/I) passive microwave data; and (3......) supraglacial lake drainage events from MODIS. Results confirm that the origin of the sediment plume is meltwater release from the ice sheet. Interannual variations in plume area reflect interannual variations in surface melting. Plumes appear almost immediately with seasonal surface-melt onset, provided...... the estuary is free of landfast sea ice. A seasonal hysteresis between melt extent and plume area suggests late-season exhaustion in sediment supply. Analysis of plume sensitivity to supraglacial events is less conclusive, with 69% of melt pulses and 38% of lake drainage events triggering an increase in plume...

  6. Quantifying exchange between groundwater and surface water in rarely measured organic sediments

    Science.gov (United States)

    Rosenberry, D. O.; Cavas, M.; Keith, D.; Gefell, M. J.; Jones, P. M.

    2016-12-01

    Transfer of water and chemicals between poorly competent organic sediments and surface water in low-energy riverine and lentic settings depends on several factors, including rate and direction of flow, redox state, number and type of benthic invertebrates, and chemical gradients at and near the sediment-water interface. In spite of their commonly large areal extent, direct measurements of flow in soft, organic sediments are rarely made and little is known about flux direction, rate, or heterogeneity. Commonly used monitoring wells are difficult to install and suffer from slow response to changing hydraulic head due to the low permeability of these sediments. Seepage meters can directly quantify seepage flux if several challenges can be overcome. Meters are difficult to install and operate where water is deep, visibility is poor, and the position of the sediment-water interface is not readily apparent. Soft, easily eroded sediment can be displaced during meter installation, creating bypass flow beneath the bottom of the seepage cylinder. Poorly competent sediments often cannot support the weight of the meters; they slowly sink into the bed and displace water inside the seepage cylinder, which leads to the interpretation of large upward flow. Decaying organic material within the sediment generates gas that can displace water and corrupt seepage-meter measurements. Several inexpensive modifications to a standard seepage meter, as well as precautions during installation and operation, can minimize these sources of error. Underwater video cameras can be mounted to the meter to remotely observe sediment disturbance during sensor installation and monitor the stability of the meter insertion depth during the period of deployment. Anchor rods can be driven a meter or more into the sediment until refusal, firmly anchoring the seepage meter at a constant sediment insertion depth. Data collected from modified seepage meters installed in Minnesota and New York demonstrate the

  7. Uranium series disequilibrium in the coastal surface sediments and sea water of the Arabian sea

    Digital Repository Service at National Institute of Oceanography (India)

    Joshi, L.U.; Zingde, M.D.

    activity ratios in leachates, and residues after removal of surface organic matter from the sediment particles by treatment with hydrogen peroxide and 0.05M HCl, revealed disequilibrium between sup(238) U and sup(234) U only in the surface organic matter...

  8. Heavy metals levels in surface waters and sediments in an oilfield in ...

    African Journals Online (AJOL)

    Heavy metal levels in the surface waters and sediments from five sampling stations of the Bukuma oilfield, in the Niger Delta, Nigeria were investigated using the AAS technique after standard procedures of storage and extraction. Mean range (mg/l) in the surface waters varied from Zn (0.19 0.64); Pb (ND 0.60); Cd (ND ...

  9. Distribution of heavy metals and environmental assessment of surface sediment of typical estuaries in eastern China.

    Science.gov (United States)

    Bi, Shipu; Yang, Yuan; Xu, Chengfen; Zhang, Yong; Zhang, Xiaobo; Zhang, Xianrong

    2017-08-15

    Estuary sediment is a major pollutant enrichment medium and is an important biological habitat. This sediment has attracted the attention of the marine environmental scientists because it is a more stable and effective medium than water for monitoring regional environmental quality conditions and trends. Based on a large amount of measurement data, we analyzed the concentrations, distribution, and sources of seven heavy metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) in the surface sediment of typical estuaries that empty into the sea in eastern China: the Liaohe River Estuary, Yellow River Estuary, Yangtze River Estuary, Minjiang River Estuary, and Pearl River Estuary. The heavy metal concentrations in the sediments vary considerably from one estuary to the next. The Liaohe River Estuary sediment contains elevated levels of Cd, Hg, and Zn. The Yellow River Estuary sediment contains elevated levels of As. The sediments in the Yangtze River and Minjiang River estuaries contain elevated levels of Cd and Cu and of Pb and Zn, respectively. The sediment in the Pearl River Estuary contains elevated levels of all seven heavy metals. We used the Nemerow index method to assess the environment quality. The heavy metal pollution in the Liaohe River and Pearl River estuaries is more severe than that in the other estuaries. Additional work indicates that the heavy metal pollution in the Liaohe River and Pearl River estuaries is caused mainly by human activity. Copyright © 2017. Published by Elsevier Ltd.

  10. Nutrient, trace-element, and ecological history of Musky Bay, Lac Courte Oreilles, Wisconsin, as inferred from sediment cores

    Science.gov (United States)

    Fitzpatrick, Faith A.; Garrison, Paul J.; Fitzgerald, Sharon A.; Elder, John F.

    2003-01-01

    Sediment cores were collected from Musky Bay, Lac Courte Oreilles, and from surrounding areas in 1999 and 2001 to determine whether the water quality of Musky Bay has declined during the last 100 years or more as a result of human activity, specifically cottage development and cranberry farming. Selected cores were analyzed for sedimentation rates, nutrients, minor and trace elements, biogenic silica, diatom assemblages, and pollen over the past several decades. Two cranberry bogs constructed along Musky Bay in 1939 and the early 1950s were substantially expanded between 1950?62 and between 1980?98. Cottage development on Musky Bay has occurred at a steady rate since about 1930, although currently housing density on Musky Bay is one-third to one-half the housing density surrounding three other Lac Courte Oreilles bays. Sedimentation rates were reconstructed for a core from Musky Bay by use of three lead radioisotope models and the cesium-137 profile. The historical average mass and linear sedimentation rates for Musky Bay are 0.023 grams per square centimeter per year and 0.84 centimeters per year, respectively, for the period of about 1936?90. There is also limited evidence that sedimentation rates may have increased after the mid-1990s. Historical changes in input of organic carbon, nitrogen, phosphorus, and sulfur to Musky Bay could not be directly identified from concentration profiles of these elements because of the potential for postdepositional migration and recycling. Minor- and trace-element profiles from the Musky Bay core possibly reflect historical changes in the input of clastic material over time, as well as potential changes in atmospheric deposition inputs. The input of clastic material to the bay increased slightly after European settlement and possibly in the 1930s through 1950s. Concentrations of copper in the Musky Bay core increased steadily through the early to mid-1900s until about 1980 and appear to reflect inputs from atmospheric

  11. Phosphorus forms of the surface sediment in the Iranian coast of the southern Caspian Sea

    OpenAIRE

    Nasrollahzadeh Saravi, H.; Pouraria, A.; Nowruzi, B.

    2015-01-01

    Sediments from the southern Caspian Sea, located in Iranian coast were examined on the basis of P-fractionation (five forms of phosphorus) by a sequential extraction scheme. Ninety-six surface sediment samples (for each season with triplicate) were collected from eight sampling transects in 10 and 100 m depths during summer and winter in 2010-2011. The result indicated that the most abundant forms of phosphorus were calcium bound phosphorus. Relative abundance of other forms of phosphorus fol...

  12. {sup 210}Pb geochronology and chemical characterization of sediment cores from lakes of the Parana river alluvial plain

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, L.F.L.; Damatto, S.R.; Scapin, M.A. [IPEN - Instituto de Pesquisas Energeticas e Nucleares (Brazil); Remor, M.B.; Sampaio, S.C. [UNIOESTE - Universidade Estadual do Oeste do Parana (Brazil)

    2014-07-01

    The flood plain of the upper Parana River is located among the lakes formed by the Brazilian hydroelectric plants being the last part of the Parana river, in Brazil, where there is an ecosystem with interaction river-flood plain. This flood plain has considerable habitat variability, with great diversity of terrestrial and aquatic species, and the floods are the main factor that regulates the operation of this ecosystem. The seasonality of the flood pulses is mainly influenced by the El Nino phenomenon, which increases precipitation in the drainage basin of the flood plain of the upper Parana River. Because of its unique characteristics this ecosystem is the subject of intense study since 1980, mainly from the ecological point of view. Therefore, two sediment cores were collected in the ponds formed by the floods, Patos pond and Garcas pond, in order to characterize the sediment chemically and evaluate a possible historic contamination. The trace element concentrations As, Ba, Br, Ce, Co, Cr, Cs, Eu, Hf, La, Lu, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb and Zn (mg.kg{sup -1}) and the major elements Si, Al, Fe, Ti, K, Ca, Mg, P, V, Mn, and Na (%) were determined in the sediment cores dated by {sup 210}Pb method, using instrumental neutron activation analysis, X-ray fluorescence and gross beta counting, respectively. The results obtained for the elements Ce, Cr, Cs, La, Nd, Sc, Sm and Th are higher than the values of Upper Continental Crust for both ponds. The sedimentation rates obtained for Garca pond, 0.77 cm.y{sup -1}, and Patos pond, 0.62 cm.y{sup -1} are in agreement with studies performed in sedimentary environments similar to the present work, such as Brazilian wetland Pantanal. The enrichment factor and the geo-accumulation index were used to assess the presence of anthropogenic sources of pollution. Document available in abstract form only. (authors)

  13. Signals of the change in monsoonal precipitation at around 2,000 years BP in a sediment core off central west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Khare, N.

    A 4.80 m long shallow water sediment core, collected from the inner shelf (at 22 m water depth) off Karwar near Kali River mouth is studied for foraminiferal tracers of palaeomonsoons. The climatic history of this core which represents the last 4,500...

  14. Effects of engineered nano-titanium dioxide on pore surface properties and phosphorus adsorption of sediment: its environmental implications.

    Science.gov (United States)

    Luo, Zhuanxi; Wang, Zhenhong; Wei, Qunshan; Yan, Changzhou; Liu, Feng

    2011-09-15

    Understanding the environmental safety and human health implications of engineered nanoparticles (ENPs) is of worldwide importance. As an important ENPs, engineered nano-TiO(2) (Enano-TiO(2)) may have been substantially deposited in aquatic sediments because of its widely uses. Sediment pore surface properties would be thus significantly influenced due to the large surface area of Enano-TiO(2). In this study, Enano-TiO(2) was found to greatly impact on sediment pore surface properties. The attachment of Enano-TiO(2) particles to sediment surfaces enhanced markedly BET specific surface area and t-Plot external specific surface area, and thereby increased sediment phosphorus (P) adsorption maximum (S(max)). Contrarily, the fill of Enano-TiO(2) particles into the micropores of sediments could significantly reduce t-Plot micropore specific surface area, and cause slight decrease in sediment P binding energy (K). Clearly, P sorbed in sediment would be easily released because of the decreasing P binding energy of the sediment with elevated Enano-TiO(2). Enano-TiO(2) would thus cause aggravated endogenous pollution in water if such sediment was re-suspended on disturbance. The results obtained in this study contribute to our increasing knowledge of how to regulate physicochemical behavior of pollutants in sediments under the influences of Enano-TiO(2) and/or similar ENPs. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Structural identification of long-chain polyamines associated with diatom biosilica in a Southern Ocean sediment core

    Science.gov (United States)

    Bridoux, Maxime C.; Ingalls, Anitra E.

    2010-07-01

    Long-chain polyamines (LCPAs) constitute a new family of natural organic compounds that have recently been isolated and characterized from the biosilicified cell walls of diatom cultures. To date, diatom-specific polyamines have not been investigated from the marine environment and their fate in the environment is entirely unknown. Here, we report a series of LCPAs in a diatom frustule-rich sediment core (TNO57-13 PC4), originating from the Atlantic sector of the Southern Ocean and spanning from the Holocene to the Last Glacial Maximum (LGM). Liquid chromatography with electrospray ionization mass spectrometry (LC-ESI-MS) revealed a complex mixture of linear polyamines with at least 28 individual molecular species. Ion trap mass fragmentation studies, combined with high resolution Time of Flight (TOF) mass spectrometry showed that the polyamine pool consisted of a series of N-methylated propylamine compounds attached to a putrescine moiety, with individual LCPAs varying in chain length and degree of methylation. The structural similarity between LCPAs extracted from the diatom-rich sediment core and those extracted from the frustules of cultured diatoms suggests that sedimentary LCPAs are derived from diatom frustules. We hypothesize that these intrinsically labile organic molecular fossils are protected from diagenesis by encapsulation within the frustule. These compounds constitute a new class of biomarkers that could potentially be indicators of diatom species distribution. Isotopic analysis of LCPAs could be used to improve age models for sediment cores that lack calcium carbonate and to improve current interpretations of diatom-based paleoproxies, including diatom-bound nitrogen isotopes.

  16. Heavy metal contamination in surface runoff sediments of the urban area of Vilnius, Lithuania

    Directory of Open Access Journals (Sweden)

    Gytautas Ignatavičius

    2017-02-01

    Full Text Available Surface runoff from urbanized territories carries a wide range of pollutants. Sediments in untreated runoff from direct discharge stormwater systems significantly contribute to urban waterway pollution. In this study, heavy metal (Pb, Zn, Cu, Cr, Ba, As and Fe contamination in surface runoff sediments of the urban area of the city of Vilnius was investigated. The surface runoff sediment samples were collected from seven dischargers with the highest volume rate of water flow and concentrations of suspended solids. The geospatial analysis of the distribution of heavy metals shows that there are several active pollution sources supplying the dischargers with contaminated sediments. Most of these areas are located in the central part of the city and in old town with intense traffic. Principal components analysis and t-test results clearly depicted the significantly different chemical compositions of winter and autumn surface sediment samples. The sampling approach and assessment of results provide a useful tool to examine the contamination that is generated in urban areas, distinguish pollution sources and give a better understanding of the importance of permeable surfaces and green areas.

  17. Mathematical simulation of sediment and contaminant transport in surface waters. Annual report, October 1977--September 1978

    International Nuclear Information System (INIS)

    Onishi, Y.; Arnold, E.M.; Serne, R.J.; Cowan, C.E.; Thompson, F.L.; Mayer, D.W.

    1979-01-01

    Various pathways exist for exposure of humans and biota to radioactive materials released from nuclear facilities. Hydrologic transport (liquid pathway) is one element in the evaluation of the total radiation dose to man. Mathematical models supported by well-planned field data collection programs can be useful tools in assessing the hydrologic transport and ultimate fate of radionuclides. Radionuclides with high distribution coefficients or radionuclides in surface waters with high suspended sediment concentrations are, to a great extent, adsorbed by river and marine sediments. Thus, otherwise dilute contaminants are concentrated. Contaminated sediments may be deposited on the river and ocean beds creating a significant pathway to man. Contaminated bed sediment in turn may become a long-term source of pollution through desorption and resuspension. In order to assess migration and accumulation of radionuclides in surface waters, mathematical models must correctly simulate essential mechanisms of radionuclide transport. The objectives of this study were: (1) to conduct a critical review of (a) radionuclide transport models as well as sediment transport and representative water quality models in rivers, estuaries, oceans, lakes, and reservoirs, and (b) adsorption and desorption mechanisms of radionuclides with sediments in surface waters; (2) to synthesize a mathematical model capable of predicting short- and long-term transport and accumulation of radionuclides in marine environments

  18. Holocene paleoclimate history of Fallen Leaf Lake, CA., from geochemistry and sedimentology of well-dated sediment cores

    Science.gov (United States)

    Noble, Paula J.; Ball, G. Ian; Zimmerman, Susan H.; Maloney, Jillian; Smith, Shane B.; Kent, Graham; Adams, Kenneth D.; Karlin, Robert E.; Driscoll, Neal

    2016-01-01

    Millennial-scale shifts in aridity patterns have been documented during the Holocene in the western United States, yet the precise timing, severity, and regional extent of these shifts prompts further study. We present lake sediment core data from Fallen Leaf Lake, a subalpine system at the southern end of the Lake Tahoe basin for which 80% of the contemporary inflow is derived from snowpack delivered by Pacific frontal storm systems. A high quality age model has been constructed using 14C ages on plant macrofossils, 210Pb, and the Tsoyowata tephra datum (7.74-7.95 cal kyr BP). One core captures the transition from the Late Tioga-younger Dryas glaciolacustrine package to laminated opaline clay at 11.48 cal kyr BP. Early Holocene sedimentation rates are relatively high (∼1.9 mm/year) and cooler winter temperatures are inferred by the presence of pebbles interpreted to be transported out into the lake via shore ice. There is a geochemically distinct interval from ∼4.71 to 3.65 cal kyr BP that is interpreted as a late Holocene neopluvial, characterized by depleted δ13C and lower C:N that point to reduced runoff of terrigenous organic matter, increased winter precipitation, and increased algal productivity. The largest Holocene signal in the cores occurs at the end of the neopluvial, at 3.65 cal kyr BP, and marks a shift into a climate state with variable precipitation, yet is overall more arid than the neopluvial. This new climate state persists for ∼3 ka, until the Little Ice Age. Low sedimentation rates (0.5 mm/year), the homogeneous opaline sediment, and steadily increasing contributions of terrestrial vs. algal organic matter in these cores suggest that the lowstand state of Fallen Leaf Lake may have been the norm from 3.65 to 0.55 cal kyr BP, punctuated by short term high precipitation years or multi-year intervals capable of rapid short duration lake level rise. Fallen Leaf Lake is strongly influenced by changes in winter precipitation and temperature

  19. Microbial ecological associations in the surface sediments of Bohai strait

    Science.gov (United States)

    Wang, Bin; Liu, Hongmei; Tang, Haitian; Hu, Xiaoke

    2017-09-01

    Microbial communities play key roles in the marine ecosystem. Despite a few studies on marine microbial communities in deep straits, ecological associations among microbial communities in the sediments of shallow straits have not been fully investigated. The Bohai Strait in northern China (average depth less than 20 m) separates the Bohai Sea from the Yellow Sea and has organic-rich sediments. In this study, in the summer of 2014, six stations across the strait were selected to explore the taxonomic composition of microbial communities and their ecological associations. The four most abundant classes were Gammaproteobacteria, Deltaproteobacteria, Bacilli and Flavobacteriia. Temperature, total carbon, depth, nitrate, fishery breeding and cold water masses influenced the microbial communities, as suggested by representational difference and composition analyses. Network analysis of microbial associations revealed that key families included Flavobacteriaceae, Pirellulaceae and Piscirickettsiaceae. Our findings suggest that the families with high phylogenetic diversity are key populations in the microbial association network that ensure the stability of microbial ecosystems. Our study contributes to a better understanding of microbial ecology in complex hydrological environments.

  20. Physical mechanism of surface roughening on the radial core-shell nanowire heterostructure with alloy shell

    Science.gov (United States)

    Cao, Yuanyuan; Diao, Dongfeng

    2017-05-01

    We proposed a quantitative thermodynamic theory to address the physical process of surface roughening during the epitaxial growth of core-shell NW with alloy layer. The surface roughening origins from the transformation of the Frank-van der Merwe (FM) mode to the Stranski-Krastanow (SK) mode. In addition to the radius of NW core, the composition and thickness of alloy shell could determine the growth behaviors due to their modulation to the strain. The established theoretical model not only explains the surface roughening caused by the alloy shell layer, but also provides a new way to control the growth of core-shell NW.

  1. Physical mechanism of surface roughening on the radial core-shell nanowire heterostructure with alloy shell

    Directory of Open Access Journals (Sweden)

    Yuanyuan Cao

    2017-05-01

    Full Text Available We proposed a quantitative thermodynamic theory to address the physical process of surface roughening during the epitaxial growth of core-shell NW with alloy layer. The surface roughening origins from the transformation of the Frank-van der Merwe (FM mode to the Stranski-Krastanow (SK mode. In addition to the radius of NW core, the composition and thickness of alloy shell could determine the growth behaviors due to their modulation to the strain. The established theoretical model not only explains the surface roughening caused by the alloy shell layer, but also provides a new way to control the growth of core-shell NW.

  2. Distribution and possible sources of some heavy metals in the sediment cores at the front bay (Carter) and Labor Island (Khor Maksar), Aden (Yemen)

    International Nuclear Information System (INIS)

    Ali, Anis Ahmed

    2004-01-01

    Metal contents (Cd, Co,Cu,Fe,Mn,Pb an Zn) in the sediments are measured in the same cores that collected and determined by using atomic absorption spectrometric (AAS) method. two areas were chosen in Aden, Labor Island, and front Bay. The vertical sequence of sedimentary structures reflected variations in processes and rates of sedimentation with ti,e. The difference in metal concentration between the recent (upper) and the historical (lower) sediments is defined as the anthropogenic metal concentration. the series of studied cores, gave a regional picture of the sediments, metal fluxes, the calculated budgets for sediments, and metal deposition. Statistically, significant correlations (p<0.01) between concentrations of selected metals were observed, fractions < 100μm and < 250μm are the best to accumulate the heavy metals. Improvement of the situation in the two studied areas during the last decades is reflected by the decrease in anthropogenic fluxes into these areas. (author)

  3. Identifying the source of petroleum pollution in sediment cores of southwest of the Caspian Sea using chemical fingerprinting of aliphatic and alicyclic hydrocarbons.

    Science.gov (United States)

    Shirneshan, Golshan; Bakhtiari, Alireza Riyahi; Memariani, Mahmoud

    2017-02-15

    In this study, the concentration and sources of aliphatic and petroleum markers were investigated in 105 samples of Anzali, Rezvanshahr and Astara cores from the southwest of Caspian Sea. Petroleum importation was diagnosed as a main source in most depths of cores by the results of unresolved complex mixture, carbon preference index and hopanes and steranes. From the chemical diagnostic parameters, petroleum inputs in sediment of cores were determined to be different during years and the sources of hydrocarbons in some sections differed than Anzali and Turkmenistan and Azerbaijan oils. Diagenic ratios in most sediments of upper and middle sections in Astara core were determined to be highly similar to those of Azerbaijan oil, while the presence of Turkmenistan and Anzali oils were detected in a few sections of Anzali and Rezvanshahr cores and only five layers of downer section in Anzali core, respectively. Copyright © 2016. Published by Elsevier Ltd.

  4. The influence of oxygen exposure time on the composition of macromolecular organic matter as revealed by surface sediments on the Murray Ridge (Arabian Sea)

    Science.gov (United States)

    Nierop, Klaas G. J.; Reichart, Gert-Jan; Veld, Harry; Sinninghe Damsté, Jaap S.

    2017-06-01

    The Arabian Sea represents a prime example of an open ocean extended oxygen minimum zone (OMZ) with low oxygen concentrations (down to less than 2 μM) between 200 and 1000 m water depth. The OMZ impinges on the ocean floor, affecting organic matter (OM) mineralization. We investigated impact of oxygen depletion on the composition of macromolecular OM (MOM) along a transect through the OMZ on the slopes of the Murray Ridge. This sub-marine high in the northern Arabian Sea, with the top at approximately 500 m below sea surface (mbss), intersects the OMZ. We analyzed sediments deposited in the core of OMZ (suboxic conditions), directly below the OMZ (dysoxic conditions) and well below the OMZ (fully oxic conditions). The upper 18 cm of sediments from three stations recovered at different depths were studied. MOM was investigated by Rock Eval and flash pyrolysis techniques. The MOM was of a predominant marine origin and inferred from their pyrolysis products, most biomolecules (tetra-alkylpyrrole pigments, polysaccharides, proteins and their transformation products, and polyphenols including phlorotannins), showed a progressive relative degradation with increasing exposure to oxygen. Alkylbenzenes and, in particular, aliphatic macromolecules increased relatively. The observed differences in MOM composition between sediment deposited under various bottom water oxygen conditions (i.e. in terms of concentration and exposure time) was much larger than within sediment cores, implying that early diagenetic alteration of organic matter depends largely on bottom water oxygenation rather than subsequent anaerobic degradation within the sediments, even at longer time scales.

  5. Historical trends of organochlorine pesticides in a sediment core from the Gulf of Batabanó, Cuba.

    Science.gov (United States)

    Alonso-Hernández, C M; Tolosa, I; Mesa-Albernas, M; Díaz-Asencio, M; Corcho-Alvarado, J A; Sánchez-Cabeza, J A

    2015-10-01

    Sediments can be natural archives to reconstruct the history of pollutant inputs into coastal areas. This is important to improve management strategies and evaluate the success of pollution control measurements. In this work, the vertical distribution of organochlorine pesticides (DDTs, Lindane, HCB, Heptachlor, Aldrin and Mirex) was determined in a sediment core collected from the Gulf of Batabanó, Cuba, which was dated by using the (210)Pb dating method and validated with the (239,240)Pu fallout peak. Results showed significant changes in sediment accumulation during the last 40 years: recent mass accumulation rates (0.321 g cm(-2) yr(-1)) double those estimated before 1970 (0.15 g cm(-2) yr(-1)). This change matches closely land use change in the region (intense deforestation and regulation of the Colon River in the late 1970s). Among pesticides, only DDTs isomers, Lindane and HCB were detected, and ranged from 0.029 to 0.374 ng g(-1) dw for DDTs, from<0.006 to 0.05 ng g(-1) dw for Lindane and from<0.04 to 0.134 ng g(-1) dw for HCB. Heptachlor, Aldrin and Mirex were below the detection limits (∼0.003 ng g(-1)), indicating that these compounds had a limited application in the Coloma watershed. Pesticide contamination was evident since the 1970s. DDTs and HCB records showed that management strategies, namely the banning the use of organochlorine contaminants, led to a concentration decline. However, Lindane, which was restricted in 1990, can still be found in the watershed. According to NOAA guidelines, pesticides concentrations encountered in these sediments are low and probably not having an adverse effect on sediment dwelling organisms. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    Simon, Nancy S.; Ingle, Sarah N.

    2011-01-01

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

  7. Arctic-ice history and its related sedimentary regimes in the central Arctic Ocean: IODP Expedition 302 "Arctic Coring Expedition: ACEX by new non-destructive 2-D XRF and transmission X-Ray sediment-scanning techniques, TATSCAN

    Science.gov (United States)

    Sakamoto, T.; Sugisaki, S.; Iijima, K.; Yamamoto, M.; O'Regan, M.; King, J. W.; Moran, K.

    2006-12-01

    Until the recent when the Integrated Ocean Drilling Program (IODP) Expedition 302 has conducted a deep sea drilling at the central Arctic Ocean, the past Arctic-ice history has been a mystery of the Cenozoic icehouse Earth system. The IODP- Arctic Coring Expedition (ACEX) has successfully recovered over 400m sediment records (about 0 to 55 Ma) on the Lomonosov Ridge in 2004 (Moran et al., 2006). In order to reconstruct and reveal the ice history in the central Arctic Ocean, we conducted new non- destructive sediment core scanning techniques, TATSCAN, that is a code name of developing original instruments for non-destructive sediment scanning and imaging in range of millimeter and micrometer scale. In the recent, we have newly developed non-destructive energy dispersive type X-ray Fluorescence (XRF) scanner, TATSCAN-F2, for 2-dimensional elemental imaging of the surface of sediment with 1mm- or 1cm- measuring diamter in the length of up to 150 cm. The TATSCAN-X is another non-destructive scanning technique by using transmission X-ray, which can detect and identify discrete shapes such like isolated granule and pebble in the sediment core. The number of ice-rafted debris (IRD) that was defined as discrete grains more than 1mm in diameter in the X- ray imaging, was direct information of the past Arctic ice recorded in the sediment. IRD increased 1.6 1.75 Ma and 0.0 - 0.8 Ma. During 0.8 Ma, especially, IRD significantly became 2 to 4 time richer than previous duration. IRD increased in the glacial and decreased in the interglacial. The IRD variation was consistent with biomarkers in the sediment core. The increase of IRD corresponds to high amount of diagenetic hopanes and to low concentration of other biomarkers such as long-chain organic compounds derived from fresh higher plant, which was mainly supplying by river discharge. The variation of the IRD should be related to expansion of northern Siberian ice-sheet to the Arctic during the cold durations. High

  8. UPWARD MOVEMENT OF PLUTONIUM TO SURFACE SEDIMENTS DURING AN 11-YEAR FIELD STUDY

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, D.; Beals, D.; Cadieux, J.; Halverson, J.

    2010-01-25

    An 11-y lysimeter study was established to monitor the movement of Pu through vadose zone sediments. Sediment Pu concentrations as a function of depth indicated that some Pu moved upward from the buried source material. Subsequent numerical modeling suggested that the upward movement was largely the result of invading grasses taking up the Pu and translocating it upward. The objective of this study was to determine if the Pu of surface sediments originated from atmosphere fallout or from the buried lysimeter source material (weapons-grade Pu), providing additional evidence that plants were involved in the upward migration of Pu. The {sup 240}Pu/{sup 239}Pu and {sup 242}Pu/{sup 239}Pu atomic fraction ratios of the lysimeter surface sediments, as determined by Thermal Ionization Mass Spectroscopy (TIMS), were 0.063 and 0.00045, respectively; consistent with the signatures of the weapons-grade Pu. Our numerical simulations indicate that because plants create a large water flux, small concentrations over multiple years may result in a measurable accumulation of Pu on the ground surface. These results may have implications on the conceptual model for calculating risk associated with long-term stewardship and monitored natural attenuation management of Pu contaminated subsurface and surface sediments.

  9. Atrazine, triketone herbicides, and their degradation products in sediment, soil and surface water samples in Poland.

    Science.gov (United States)

    Barchanska, Hanna; Sajdak, Marcin; Szczypka, Kornelia; Swientek, Angelika; Tworek, Martyna; Kurek, Magdalena

    2017-01-01

    The aim of this study was to monitor the sediment, soil and surface water contamination with selected popular triketone herbicides (mesotrione (MES) and sulcotrione(SUL)), atrazine (ATR) classified as a possible carcinogen and endocrine disrupting chemical, as well as their degradation products, in Silesia (Poland). Seventeen sediment samples, 24 soil samples, and 64 surface water samples collected in 2014 were studied. After solid-liquid extraction (SLE) and solid phase extraction (SPE), analytes were determined by high-performance liquid chromatography (HPLC) with diode array detection (DAD). Ten years after the withdrawal from the use, ATR was not detected in any of the collected samples; however, its degradation products are still present in 41 % of sediment, 71 % of soil, and 8 % of surface water samples. SUL was determined in 85 % of soil samples; its degradation product (2-chloro-4-(methylosulfonyl) benzoic acid (CMBA)) was present in 43 % of soil samples. In 17 % of sediment samples, CMBA was detected. Triketones were detected occasionally in surface water samples. The chemometric analysis (clustering analysis (CA), single-factor analysis of variance (ANOVA), N-Way ANOVA) was applied to find relations between selected soil and sediment parameters and herbicides concentration. In neither of the studied cases a statistically significant relationship between the concentrations of examined herbicides, their degradation products and soil parameters (organic carbon (OC), pH) was observed.

  10. Determining surface water and bed sediment quality of Lake Kopa

    Directory of Open Access Journals (Sweden)

    Nurgul Kazangapovaa

    2016-10-01

    Full Text Available In this research, the results of a hydro-chemical study of Lake Kopa in Kazakhstan are described, in the context of the regional geography and aggravating ecological problems of the lake. Besides analyzing the concentrations of all major ions, heavy-metal ions and other pollutants, their vertical and horizontal distribution were also assessed. Moreover, water pollution indices (WPI were calculated for individual ions, classes of pollutants, and total pollution, revealing serious overload of human- induced pollution within the lake’s ecosystem. Concentrations of major ions and WPI were monitored over 2009-2013 period, revealing a distinct seasonal pattern and a multi-year periodicity in respect to the measured parameters. In addition, studying ion exchange between lake water and bottom sediment showed complex non-equilibrium processes besides leaching out Ca2+ and its exchange for Na+.

  11. Deep layer-resolved core-level shifts in the beryllium surface

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Johansson, Börje

    1993-01-01

    Core-level energy shifts for the beryllium surface region are calculated by means of a Green’s function technique within the tight-binding linear muffin-tin orbitals method. Both initial- and final-state effects in the core-ionization process are fully accounted for. Anomalously large energy shifts...

  12. Cladding defects in hollow core fibers for surface mode suppression and improved birefringence

    DEFF Research Database (Denmark)

    Michieletto, Mattia; Lyngso, J. K.; Lægsgaard, Jesper

    2014-01-01

    of the surface mode stripping is presented and compared to the measured performance of four 7-cells core fibers that were drawn with different collapse ratio of the defects. The varying pressure along the defect row in the cladding during drawing introduces an ellipticity of the core. This, combined...

  13. Nickel, Lead and Zinc Contamination in the Surface Sediments of Agh Gel Wetland, Iran

    Directory of Open Access Journals (Sweden)

    Soheil Sobhan Ardakani

    2016-07-01

    Full Text Available Background & Aims of the Study: Due to the increased human activities around the Agh Gel wetland, this study aimed to measured accumulations of heavy metals (Ni, Pb and Zn in the surface sediment samples taken from this wetland. Materials & Methods: Samples were taken from 10 stations and exposed to bulk digestion and chemical partitioning. Finally, Ni, Pb and Zn concentrations were monitored with ICP-OES in the sediments. Also, geo-accumulation index, contamination factor and pollution load index were used to evaluate the magnitude of contaminants in the sediment profile. Results: The results showed, the average of metal concentration in samples (mg kg-1 wet weight were 34.20±3.58 for Ni, 25.37±2.52 for Pb and 127.20±15.21 for Zn, respectively. Therefore, the pattern of metal concentrations in sediment was determined as Zinc>Nickel >Lead. According to the mean I-geo values, sediments' qualities are classified as unpolluted category for Ni and Pb. Also, sediment's quality is classified as unpolluted to moderately polluted for Zn. The CF values for all elements are classified as moderate contamination. The PLI values indicated that metal pollution exists for all sampling stations. Conclusions: The obtained results indicated that the Agh Gel wetland has a potential to threaten by chemical pollutants such as agricultural effluent. So, in order to preserve the environment of the Agh Gel wetland from deterioration, monitoring of water and sediment qualities is recommended periodically.

  14. Quantifying dust input to the Subarctic North Pacific - Results from surface sediments and sea water thorium isotope measurements

    Science.gov (United States)

    Winckler, G.; Serno, S.; Hayes, C.; Anderson, R. F.; Gersonde, R.; Haug, G. H.

    2012-12-01

    The Subarctic North Pacific is one of the three primary high-nutrient-low chlorophyll regions of the modern ocean, where the biological pump is relatively inefficient at transferring carbon from the atmosphere to the deep sea. The system is thought to be iron-limited. Aeolian dust is a significant source of iron and other nutrients that are essential for the health of marine ecosystems and potentially a controlling factor of the high-nutrient-low chlorophyll status of the Subarctic North Pacific. However, constraining the size of the dust flux to the surface ocean remains difficult. Here we apply two different approaches, based on surface sediment and water column samples, respectively, obtained during the SO202/INOPEX research cruise to the Subarctic North Pacific in 2009. We map the spatial patterns of Th/U isotopes, helium isotopes and rare earth elements across surface sediments from 37 multi-core core-top sediments across the Subarctic North Pacific. In order to deconvolve the detrital endmembers in regions of the North Pacific affected by volcanic material, IRD and hemipelagic input, we use a combination of trace elements with distinct characteristics in the different endmembers. This approach allows us to calculate the relative aeolian fraction, and in combination with Thorium230-normalized mass flux data, to quantify the dust supply. Secondly, we present an innovative approach to use paired Thorium-232 and Thorium-230 concentrations of upper-ocean seawater at 7 stations along the INOPEX track. Thorium-232 in the upper water column is dominantly derived from dissolution of aeolian dust, whereas Thorium-230 data provide a measure of the thorium removal from the surface waters and, thus, allow us to derive Thorium-232 fluxes. Combined with a mean Thorium-232 concentration in dust and estimate of the thorium solubility, the Thorium-232 flux can be translated in a dust flux to the surface ocean. Dust flux estimates for the Subarctic North Pacific will be

  15. APPLICATION OF SEDIMENT QUALITY GUIDELINES IN THE ASSESSMENT OF MANGROVE SURFACE SEDIMENT IN MENGKABONG LAGOON, SABAH, MALAYSIA

    OpenAIRE

    S. M. Praveena, M. Radojevic, M. H. Abdullah, A. Z. Aris

    2008-01-01

    There have been numerous sediment quality guidelines developed to monitor the sediments. Sediment quality guidelines are very useful to screen sediment contamination by comparing sediment contaminant concentration with the corresponding quality guideline, provide useful tools for screening sediment chemical data to identify pollutants of concern and prioritise problem sites and relatively good predictors of contaminations. However, these guidelines are chemical specific and do not include bio...

  16. Environmental assessment of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the Santander Bay, Northern Spain.

    Science.gov (United States)

    Viguri, J; Verde, J; Irabien, A

    2002-07-01

    Samples of intertidal surface sediments (0-2 cm) were collected in 17 stations of the Santander Bay, Cantabric Sea, Northern Spain. The concentrations of polycyclic aromatic hydrocarbons (PAHs), 16, were analysed by HPLC and MS detection. Surface sediments show a good linear correlation among the parameters of the experimental organic matter evaluation, where total carbon (TC) and loss on ignition (LOI) are approximately 2.5 and 5 times total organic carbon (TOC). A wide range of TOC from 0.08% to 4.1%, and a broad distribution of the sum of sigma16PAHs, from 0.02 to 344.6 microg/g d.w., which can be correlated by an exponential equation to the TOC, has been identified. A qualitative relationship may be established between the industrial input along the rivers and the concentration of sigma6PAHs in the sediments of the estuaries: Boo estuary (8404-4631 microg/g OC), Solia-San Salvador estuaries (305-113 microg/g OC) and Cubas estuary (31-32 microg/g OC). This work shows a dramatic change in the spatial distribution in the concentration of PAHs of intertidal surface sediments. The left edge of the Bay has the main traffic around the city and the major source of PAHs is from combustion processes and estuarine inputs, leading to medium values of PAHs in the sediments; the right edge of the Bay has much lesser anthropogenic activities leading to lower values of PAHs in sediments. The distribution of individual PAHs in sediments varies widely depending on their structure and molecular weight; the 4-6 ring aromatics predominate in polluted sediments due to their higher persistence. The isomer ratio does not allow any clear identification of the PAHs origin. Environmental evaluation according to Dutch guidelines and consensus sediment quality guidelines based on ecotoxicological data leads to the same conclusion, sediments in the Santander Bay show a very different environmental quality depending on the spatial position from heavily polluted/medium effects to non

  17. Distribution, sources, and ecological risk assessment of SVOCs in surface sediments from Guan River Estuary, China.

    Science.gov (United States)

    He, Xinran; Song, Xiaojuan; Pang, Yong; Li, Yiping; Chen, Binlin; Feng, Zhihua

    2014-07-01

    The contamination of semi-volatile organic compounds (SVOCs) in the surface sediments of the Guan River Estuary, China was fully investigated. Total concentrations of 56 species of SVOCs ranged from 132 to 274 ng/g with an average of 186 ng/g (dry weight). Polycyclic aromatic hydrocarbon (PAH) concentrations were positively correlated with clay content and negatively correlated with sediment grain size. Source identification indicated that PAHs originated mainly from pyrolytic sources. However, intense ship traffic in the estuary may provide sources of petrogenic PAHs. Organochlorine pesticides (OCPs) mainly originated from direct input of dichlorodiphenyltrichloroethanes (DDTs) during some industrial processes. The SVOC concentrations were also compared with International Sediments Quality Guidelines and Sediments Quality Criteria, and the results indicated that negative biological impacts may originate from high concentrations of FLO, p,p'-DDE, and total DDTs.

  18. Sedimentological and biostratigraphical analyses of short sediment cores from Hagelseewli (2339 m a.s.l. in the Swiss Alps

    Directory of Open Access Journals (Sweden)

    Jacqueline F.N. VAN LEEUWEN

    2000-09-01

    Full Text Available Several short sediment cores of between 35 and 40 cm from Hagelseewli, a small, remote lake in the Swiss Alps at an elevation of 2339 m a.s.l. were correlated according to their organic matter content. The sediments are characterized by organic silts and show in their uppermost part a surprisingly high amount of organic matter (30-35%. Synchronous changes, occurring in pollen from snow-bed vegetation, the alga Pediastrum, chironomids, and grain-size composition, point to a climatic change interpreted as cooler or shorter summers that led to prolonged ice-cover on the lake. According to palynological results the sediments date back to at least the early 15th century A.D., with the cooling phase encompassing the period between late 16th and the mid-19th century thus coinciding with the Little Ice Age. Low concentrations of both chironomid head capsules and cladoceran remains in combination with results from fossil pigment analyses point to longer periods of bottom-water anoxia as a result of long-lasting ice-cover that prevented mixing of the water column. According to our results aquatic biota in Hagelseewli are mainly indirectly influenced by climate change. The duration of ice-cover on the lake controls the mixing of the water column as well as light-availability for phytoplankton blooms.

  19. Early diagenetic overprint in Caribbean sediment cores and its effect on the geochemical composition of planktonic foraminifera

    Directory of Open Access Journals (Sweden)

    M. Regenberg

    2007-11-01

    Full Text Available Early diagenetic features are noticed in the vicinity of carbonate platforms. Planktonic foraminifera of two tropical Atlantic deep-sea sediment cores show the strict relation between micro-scale euhydral crystallites of inorganic precipitates, higher oxygen isotope values and Mg/Ca ratios, and lower Sr/Ca ratios than expected for their pelagic environment in the time interval of ~100 000–550 000 calendar years before present. Laser ablation Mg/Ca (Sr/Ca of crystallite-bearing foraminiferal chamber walls revealed 4–6 times elevated (2–3 times depleted ratios, when ablating the diagenetic overgrowth. Crystalline overgrowth in proportion of 10–20% are estimated to cause the observed geochemical alteration. The extent of foraminiferal Mg/Ca alteration, moreover, seems to be controlled by the composition of the bulk sediment, especially the content of high-magnesium calcite. Anomalous ratios of >6 mmol/mol only occur, when high-magnesium calcite has dissolved within the sediment. The older parts (back to ~800 kyrs of the records are characterized by similar trends of Mg/Ca and Sr/Ca. We discuss possible scenarios to accommodate the obtained geochemical information.

  20. Relationship between chemical composition and magnetic susceptibility in sediment cores from Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Parthiban, G.; Banakar, V.K.; Tomer, A.; Kulkarni, M.

    and shows increasing trend with the core depth (figure 2). The TC is closer to conti- nent compared to SC but the χ values are lower ranging from 9.78 to 83.47 ×10 −7 m 3 kg −1 with an average of 29.93×10 −7 m 3 kg −1 (figure 3). The low values of χ... AAS- 01/SPC-01 (calcareous core) is referred to as CC, AAS-40/GC-02 (terrigenous core) as TC and AAS-27/GC-01 (siliceous core) as SC for convenience. All sub-samples were oven dried at 40 ◦ Cand powdered in agate mortar. The dried powders were Figure 1...

  1. Physical properties of a sediment core from the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Khadge, N.H.

    A box core of 7.5 m was collected from the Central Indian Basin for the purpose of geotechnical studies and depthwise variation of physical properties and clay mineralogy. Water content, Atterberg limits, specific gravity are measured at regular...

  2. Palynological investigation of the sediment cores from the Arabian Sea 1 Fungal spores

    Digital Repository Service at National Institute of Oceanography (India)

    Chandra, A.; Saxena, R.K.; Setty, M.G.A.P.

    are new to the record @iInapertisporites@@ is represented in all the samples and is the most common element of the assemblage The distribution of various fungal spore genera and species in each core has been discussed...

  3. Size-Dependent Specific Surface Area of Nanoporous Film Assembled by Core-Shell Iron Nanoclusters

    Directory of Open Access Journals (Sweden)

    Jiji Antony

    2006-01-01

    Full Text Available Nanoporous films of core-shell iron nanoclusters have improved possibilities for remediation, chemical reactivity rate, and environmentally favorable reaction pathways. Conventional methods often have difficulties to yield stable monodispersed core-shell nanoparticles. We produced core-shell nanoclusters by a cluster source that utilizes combination of Fe target sputtering along with gas aggregations in an inert atmosphere at 7∘C. Sizes of core-shell iron-iron oxide nanoclusters are observed with transmission electron microscopy (TEM. The specific surface areas of the porous films obtained from Brunauer-Emmett-Teller (BET process are size-dependent and compared with the calculated data.

  4. Mid-term variation of vertical distribution of acid volatile sulphide and simultaneously extracted metals in sediment cores from Lake Albufera (Valencia, Spain).

    Science.gov (United States)

    Hernández-Crespo, Carmen; Martín, Miguel

    2013-11-01

    Lake Albufera is one of the most eutrophic bodies of water in Spain due to point and diffuse pollution over past decades, and its sediments are likely to be anoxic because of high organic matter flux. Hence, sulphides can play an important role in limiting the mobility of heavy metals. This study aimed to study the vertical variation of acid volatile sulphide (AVS) and simultaneously extracted metals (SEM) in sediment cores collected from Lake Albufera; other sediment characteristics, such as organic matter, biochemical oxygen, demand or total metals, were also studied. Three sites were selected, and four sampling campaigns were performed to study spatial and temporal variation as well as to obtain information regarding historical variation in the composition of sediments. AVS and SEM were analysed by the purge-and-trap method. The vertical distribution of AVS and SEM varied depending on the sampling site-concentrations of AVS and SEM were higher at sites close to mouths of inflowing channels. A decreasing trend of AVS has been found at these sites over time: In the two first samplings, AVS increased with depth reaching maximum concentrations of 40 and 21 μmol g(-1), but from then on AVS were lower and decreased with depth. SEM decreased with depth from 3 μmol g(-1) in surface layers to approximately 1 μmol g(-1) at deeper segments at these sites. However, the central site was more uniform with respect to depth as well as with time; it presented lower values of SEM and AVS (mean 0.9 and 2.0 μmol g(-1) respectively), and the maximum value of AVS (7 μmol g(-1)) was found at the top layer (0-3 cm). According to the (SEM-AVS)/fOC approach, every site, and throughout the cores, can be classified as containing nontoxic metals because the values were <130 μmol g(-1).

  5. Trace metals and other constitutive components in two sediment cores from a remote glacier-fed estuarine lagoon in southern Chile

    Science.gov (United States)

    Ahumada, R.; Rudolph, A.

    2004-02-01

    Laguna San Rafael is an estuarine basin at the base of an active glacier in the process of regression, which forms part of Chile's remote Northern Ice Fields. The basin is about 140 m in maximum depth and is connected indirectly to the coastal zone by narrow channels. The present report presents preliminary data obtained from the first two sediment cores obtained from the center of Laguna San Rafael as "samples of opportunity" on an oceanographic cruise. Results from the samples are of unusual interest due to the remote location, absence of anthropogenic insult, and need to obtain background data prior to expansion of development of tourism in the area. The sediment cores were obtained from the deepest portion of the lagoon and later examined at six levels through the core. One sediment core was analyzed for organic carbon, organic nitrogen and total phosphorus and the second was analyzed for nine metals, two metal oxides, and silicon dioxide. The sediments were formed of gray-green, well-selected clay minerals, and contained low levels of C and N. There was little variation in the distribution of trace metals throughout the core. Sediment metal abundances were Ba > V > Zn > Cr > Cu ≥ Ni > Co > Pb > Cd. Concentrations were relatively low compared with the results observed from comparable fjords, with the exception of unexplained high values obtained for sedimentary Ba, V, and Zn.

  6. Granulometric characterization of sediments transported by surface runoff generated by moving storms

    Directory of Open Access Journals (Sweden)

    J. L. M. P. de Lima

    2008-12-01

    Full Text Available Due to the combined effect of wind and rain, the importance of storm movement to surface flow has long been recognized, at scales ranging from headwater scales to large basins. This study presents the results of laboratory experiments designed to investigate the influence of moving rainfall storms on the dynamics of sediment transport by surface runoff. Experiments were carried out, using a rain simulator and a soil flume. The movement of rainfall was generated by moving the rain simulator at a constant speed in the upstream and downstream directions along the flume. The main objective of the study was to characterize, in laboratory conditions, the distribution of sediment grain-size transported by rainfall-induced overland flow and its temporal evolution. Grain-size distribution of the eroded material is governed by the capacity of flow that transports sediments. Granulometric curves were constructed using conventional hand sieving and a laser diffraction particle size analyser (material below 0.250 mm for overland flow and sediment deliveries collected at the flume outlet. Surface slope was set at 2%, 7% and 14%. Rainstorms were moved with a constant speed, upslope and downslope, along the flume or were kept static. The results of laboratory experiments show that storm movement, affecting the spatial and temporal distribution of rainfall, has a marked influence on the grain-size characteristics of sediments transported by overland flow. The downstream-moving rainfall storms have higher stream power than do other storm types.

  7. Sediment yield on a devastated hill in southern China: effects of microbiotic crust on surface erosion process

    Science.gov (United States)

    Uchida, Taro; Ohte, Nobuhito; Kimoto, Akitsu; Mizuyama, Takahisa; Changhua, Li

    2000-02-01

    In southern China, most of the forests consist of Pinus massoniana, but they are usually poor, thin, and deteriorated due to human intervention such as cutting, removal of litter for fuel and over-grazing. Therefore, exposed bare soil is found in many devastated hills. As a consequence, both the direct runoff percentage and the sediment yield are very high. In order to understand the surface erosion processes in this environment, we measured sediment yield and surface erosion depth in terms of catchment scale, and carried out in situ sprinkling experiments, focusing on the spatial variability of surface conditions and sediment sources. The results of sediment yield measurements at the end of headwater catchment suggest the following characteristic. (1) The surface water is capable of transporting more material than is supplied by detachment. That is, the sediment discharge process is detachment-limited. In situ sprinkling experiments indicate that: (2) In the lower part of the hillslope where the surface is covered by microbiotic crust, the ratio of surface runoff to rainfall is high, but sediment yield is small. (3) In the upper part of the hillslope where there is no microbiotic crust, the ratio of surface runoff to rainfall is low, but sediment yield is large. Measurements of surface erosion depths indicate that: (4) Microbiotic crusts provide a high degree of protection against soil erosion, even though the surface runoff ratio is large at the lower hillslope. Consequently, the surface erosion depth is almost zero at the lower part of hillslope. (5) The main source of sediment was the upper part of hillslope. Based on these indications, it can be concluded that when the sediment discharge process is detachment-limited, the effect of the surface crust and/or the vegetation cover on the sediment discharge process is great. That is, the spatial variation of the surface crust and/or the vegetation cover controls the source of sediment.

  8. Nitrogen cycling across the Peruvian oxygen minimum zone surface sediments

    Science.gov (United States)

    Sommer, S.; Bohlen, L.; Dale, A. W.; Wallmann, K.; Noffke, A.; Hensen, C.; Mosch, T.; Pfannkuche, O.

    2012-04-01

    Oxygen minimum zones (OMZ) are key regions for pelagic and benthic nitrogen turnover. During Meteor cruise M77 (Oct. - Dec. 2008) benthic nitrogen cycling along a latitudinal depth transect (85 to 1000 m) across the Peruvian OMZ at 11°S was studied involving in situ flux measurements, pore water geochemistry as well as diagenetic modeling. Along this transect bottom water oxygen levels were minor importance on the shelf and upper slope but was the dominant N sink at 1000 m. Mass balance calculations as well as modeling indicate that dissimilatory nitrate reduction to ammonium (DNRA) by sulfur bacteria and ammmonification were the main source pathways for ammonium to the bottom water, yielding release rates of up to 4.6 mmol m-2 d-1. DNRA retains DIN within the ecosystem and counteracts the removal of DIN via denitrification and/or anammox. This finding is in contrast to the current opinion that slope sediments in general represent major sinks for DIN.

  9. Sulfate reduction controlled by organic matter availability in deep sediment cores from the saline, alkaline Lake Van (Eastern Anatolia, Turkey

    Directory of Open Access Journals (Sweden)

    Clemens eGlombitza

    2013-07-01

    Full Text Available As part of the International Continental Drilling Program (ICDP deep lake drilling project PaleoVan, we investigated sulfate reduction (SR in deep sediment cores of the saline, alkaline (salinity 21.4 ‰, alkalinity 155 m mEq-1, pH 9.81 Lake Van, Turkey. The cores were retrieved in the Northern Basin (NB and at Ahlat Ridge (AR and reached a maximum depth of 220 m. Additionally, 65-75 cm long gravity cores were taken at both sites. Sulfate reduction rates (SRR were low (≤ 22 nmol cm-3 d-1 compared to lakes with higher salinity and alkalinity, indicating that salinity and alkalinity are not limiting SR in Lake Van. Both sites differ significantly in rates and depth distribution of SR. In NB, SRR are up to 10 times higher than at AR. Sulfate reduction (SR could be detected down to 19 meters below lake floor (mblf at NB and down to 13 mblf at AR. Although SRR were lower at AR than at NB, organic matter (OM concentrations were higher. In contrast, dissolved OM in the pore water at AR contained more macromolecular OM and less low molecular weight OM. We thus suggest, that OM content alone cannot be used to infer microbial activity at Lake Van but that quality of OM has an important impact as well. These differences suggest that biogeochemical processes in lacustrine sediments are reacting very sensitively to small variations in geological, physical or chemical parameters over relatively short distances. 

  10. Accumulation and Risk of Triclosan in Surface Sediments Near the Outfalls of Municipal Wastewater Treatment Plants.

    Science.gov (United States)

    Chen, Lei; Wang, Zheng; Jing, Zhaoqian; Wang, Zhulai; Cao, Shiwei; Yu, Ting

    2015-10-01

    Triclosan is an antimicrobial agent which is widely used in many personal care products. This toxic chemical is frequently found in the aquatic environment. The municipal wastewater treatment plant (WWTP) effluent has been reported to be one of the major sources for triclosan in the aquatic system. The aim of the present study was to investigate the accumulation of triclosan in the surface sediments near the outfalls of the five major municipal WWTPs of Nanjing, China, as well as to evaluate its potential ecological risk. The concentration of triclosan in the sediment samples ranged from 48.3 to 226 ng/g dry weight, which was well correlated with the acute and genetic toxicity by bioassay. The results suggested that triclosan released from municipal WWTPs could accumulate in the surface sediments nearby and may pose undetermined risk to aquatic organisms.

  11. Gases (CH4, CO2 and N2 and pore water chemistry in the surface sediments of Lake Orta, Italy: acidification effects on C and N gas cycling

    Directory of Open Access Journals (Sweden)

    Donald D. ADAMS

    2001-02-01

    Full Text Available Lake Orta, a subalpine, warm monomictic lake in northwestern Italy was heavily polluted from rayon factory discharges of ammonium and copper since 1926. In the 1950s accumulations of contaminants resulted in whole lake pHs of 3.8-4.0 from ammonium oxidation. Partial remediation started in the 1950s, but by 1985-89 the water remained acidified at pHs of 4.0. Artificial liming (14,500 t in 1989-90 resulted in improved water quality and substantial recovery of the biological community. Sediment gases, sampled in 1989 before liming, from the lake's four basins showed severe inhibition of methanogenesis (CH4 = 0.0-0.15 mM in the surface sediments (0.5-5 cm of the southern basin, location of the plant effluent, as compared to the deep central and northern basins (0.9-1.4 mM. Four years after liming, cores collected in 1994 near the 1989 southern basin sites showed a slight change in surface sediment methane (0.07-0.82 mM, yet suggested continual sediment toxicity, at least to carbon cycling through methanogenesis. Calculations of diffuse flux of CH4 at the sediment-water interface (SWI in 1989 were 6.6-7.4 mM m-2 day-1 for the central and northern basins and 0.13 for the southern basin. CH4 fluxes increased 16x to 2 mM m-2 day-1 in 1994 in the southern basin, possibly from remediation of near surface sediments. The impact of pollution on denitrification (formation of sediment N2 gas was not so obvious since two processes could counteract each other (high NO3 - stimulating denitrification versus possible negative effects from acidity and metals. The calculated flux of N2 from the southern basin sediments increased 5x four years after liming compared to the period of acidification, suggesting possible toxicity towards denitrifiers during the earlier period. Core overlying water (0.68 mM exhibited N2 concentrations close to saturation, while most surface sediments were twice as much (1.5 mM. Surface (0-6 cm sediment N2 was similar at most sites, with the

  12. APPLICATION OF SEDIMENT QUALITY GUIDELINES IN THE ASSESSMENT OF MANGROVE SURFACE SEDIMENT IN MENGKABONG LAGOON, SABAH, MALAYSIA

    Directory of Open Access Journals (Sweden)

    S. M. Praveena, M. Radojevic, M. H. Abdullah, A. Z. Aris

    2008-01-01

    Full Text Available There have been numerous sediment quality guidelines developed to monitor the sediments. Sediment quality guidelines are very useful to screen sediment contamination by comparing sediment contaminant concentration with the corresponding quality guideline, provide useful tools for screening sediment chemical data to identify pollutants of concern and prioritise problem sites and relatively good predictors of contaminations. However, these guidelines are chemical specific and do not include biological parameters. Aquatic ecosystems, including sediments, must be assessed in multiple components (biological data, toxicity, physicochemistry by using intregrated approaches in order to establish a complete and comprehensive set of sediment quality guidelines. Numerous sediment quality guidelines Washington Department of Ecology Sediment Quality Guideline, Australian and New Zealand Environment and Conservation Council, Swedish Environmental Sediment Quality, Screening Quick Reference Table, Portuguese Legislation on the Classification of Dredged Materials in Coastal Zones and Interim Sediment Quality Guideline for Hong Kong have been applied to the Mengkabong lagoon mangrove sediment and discussed. The most appropriate guideline that meets the prioritization criteria consistent with international initiatives and regulations is interim sediment quality values for Hong Kong. The guideline verifies that all the metals are below the Interim Sediment Quality Value-low. However, site-specific, biological testing and ecological analysis of exisiting benthics community structure related to sediment contamination are needed for final decision making in the case of Mengkabong lagoon.

  13. Sedimentation

    Digital Repository Service at National Institute of Oceanography (India)

    Rixen, T.; Guptha, M.V.S.; Ittekkot, V.

    through the water column but their trapping efficiency, and thus, their accuracy can be biased by hydrodynamic and biological effects (Lee et al., 1988; Gust et al., 1992; 1994). Scholten et al. (2001) showed that the 230 Thorium trapping efficiency... of sediment traps moored at different sites and water depths in eastern North Atlantic Ocean varies between 9 and 143%. In general, these trapping efficiencies increase with increasing water-depth (Scholten et al., 2001). By comparing data from various ocean...

  14. Mineralization of 2,4,6-Trinitrotoleune (TNT) in Coastal Waters and Sediments

    National Research Council Canada - National Science Library

    Walker, S. W; Osburn, C. L; Boyd, T. J; Hamdan, L. J; Coffin, R. B; Montgomery, M. T; Smith, J. P; Li, Q. X; Monteil, F; Hawari, J

    2006-01-01

    Mineralization rates of 14C-TNT, -DNT, and -DAT were measured in surface sediments, with depth in sediment cores, and in the water column during 12 research cruises over the past 4 years in the San...

  15. Forearc uplift rates deduced from sediment cores of two coastal lakes in south-central Chile

    OpenAIRE

    Stefer, S.; Moernaut, J.; Melnick, D.; Echtler, H. P.; Arz, H. W.; Lamy, Frank; De Batist, M.; Oncken, O.; Haug, G. H.

    2010-01-01

    The present paper introduces a new approach for deriving information about local forearc tectonics and related uplift rates based on the study of lake sediments. We investigated two coastal lakes at the south-central Chile margin, lakes Lanalhue and Lleu Lleu, located south of the Arauco Peninsula (38°S). Both lakes developed within the valleys of ancient rivers that once drained to the Pacific Ocean, being subsequently dammed by rising sills in the late Pleistocene/early Holocene. Seismic pr...

  16. Micro contaminants in surface sediments and macrobenthic invertebrates of the North Sea

    NARCIS (Netherlands)

    Everaarts, J.M.; Fischer, C.V.

    1989-01-01

    Trace metal concentrations (copper, zinc, cadmium and lead) were measured in the silt fraction (grainsize < 63 µm) of surface sediment of the North Sea. The concentrations varied in different areas of the Dutch continental shelf of the North Sea. The trace metal concentrations were highly related

  17. 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.

  18. The impact of oxic degradation on long chain alkyl diol distributions in Arabian Sea surface sediments

    NARCIS (Netherlands)

    Rodrigo-Gámiz, M.; Rampen, S.W.; Schouten, S.; Sinninghe Damsté, J.S.

    2016-01-01

    Oxygen exposure has a large impact on lipid biomarker preservation in surface sediments and may affectthe application of organic proxies used for reconstructing past environmental conditions. To determineits effect on long chain alkyl diol and keto-ol based proxies, the distributions of these lipids

  19. The impact of oxic degradation on long chain alkyl diol distributions in Arabian Sea surface sediments

    NARCIS (Netherlands)

    Rodrigo-Gámiz, M.; Rampen, Sebastiaan W.; Schouten, S.; Sinninghe Damsté, J.S.

    2016-01-01

    Oxygen exposure has a large impact on lipid biomarker preservation in surface sediments and may affect the application of organic proxies used for reconstructing past environmental conditions. To determine its effect on long chain alkyl diol and keto-ol based proxies, the distributions of these

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Takahiro, E-mail: twatanabe@geo.kankyo.tohoku.ac.jp [Graduate School of Environmental Studies, Tohoku University, 6-6-20 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Graduate School of Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8578 (Japan); Nakamura, Toshio [Center for Chronological Research, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601 (Japan); Matsunaka, Tetsuya [School of Marine Science and Technology, Tokai University, 3-20-1 Orido, Shimizu, Shizuoka 424-0902 (Japan); Nara, Fumiko Watanabe [Graduate School of Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8578 (Japan); Zhu Liping; Wang Junbo [Institute of Tibetan Plateau Research, Chinese Academy of Science, No. 18 Shuangqing Road, Haidian District, Beijing 100085 (China); Kakegawa, Takeshi [Graduate School of Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8578 (Japan); Nishimura, Mitsugu [School of Marine Science and Technology, Tokai University, 3-20-1 Orido, Shimizu, Shizuoka 424-0902 (Japan)

    2013-01-15

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

  2. On the bioavailability of trace metals in surface sediments: a combined geochemical and biological approach.

    Science.gov (United States)

    Roosa, Stéphanie; Prygiel, Emilie; Lesven, Ludovic; Wattiez, Ruddy; Gillan, David; Ferrari, Benoît J D; Criquet, Justine; Billon, Gabriel

    2016-06-01

    The bioavailability of metals was estimated in three river sediments (Sensée, Scarpe, and Deûle Rivers) impacted by different levels of Cu, Cd, Pb, and Zn (Northern France). For that, a combination of geochemistry and biological responses (bacteria and chironomids) was used. The results obtained illustrate the complexity of the notion of "bioavailability." Indeed, geochemical indexes suggested a low toxicity, even in surface sediments with high concentrations of total metals and a predicted severe effect levels for the organisms. This was also suggested by the abundance of total bacteria as determined by DAPI counts, with high bacterial cell numbers even in contaminated areas. However, a fraction of metals may be bioavailable as it was shown for chironomid larvae which were able to accumulate an important quantity of metals in surface sediments within just a few days.We concluded that (1) the best approach to estimate bioavailability in the selected sediments is a combination of geochemical and biological approaches and that (2) the sediments in the Deûle and Scarpe Rivers are highly contaminated and may impact bacterial populations but also benthic invertebrates.

  3. Methane Bubbles Transport Particles From Contaminated Sediment to a Lake Surface

    Science.gov (United States)

    Delwiche, K.; Hemond, H.

    2017-12-01

    Methane bubbling from aquatic sediments has long been known to transport carbon to the atmosphere, but new evidence presented here suggests that methane bubbles also transport particulate matter to a lake surface. This transport pathway is of particular importance in lakes with contaminated sediments, as bubble transport could increase human exposure to toxic metals. The Upper Mystic Lake in Arlington, MA has a documented history of methane bubbling and sediment contamination by arsenic and other heavy metals, and we have conducted laboratory and field studies demonstrating that methane bubbles are capable of transporting sediment particles over depths as great as 15 m in Upper Mystic Lake. Methane bubble traps were used in-situ to capture particles adhered to bubble interfaces, and to relate particle mass transport to bubble flux. Laboratory studies were conducted in a custom-made 15 m tall water column to quantify the relationship between water column height and the mass of particulate transport. We then couple this particle transport data with historical estimates of ebullition from Upper Mystic Lake to quantify the significance of bubble-mediated particle transport to heavy metal cycling within the lake. Results suggest that methane bubbles can represent a significant pathway for contaminated sediment to reach surface waters even in relatively deep water bodies. Given the frequent co-occurrence of contaminated sediments and high bubble flux rates, and the potential for human exposure to heavy metals, it will be critical to study the significance of this transport pathway for a range of sediment and contaminant types.

  4. Coccolith distribution patterns in South Atlantic and Southern Ocean surface sediments in relation to environmental gradients

    DEFF Research Database (Denmark)

    Boeckel, B.; Baumann, K.-H.; Henrich, R.

    2006-01-01

    In this study, the coccolith compositions of 213 surface sediment samples from the South Atlantic and Southern Ocean were analysed with respect to the environmental parameters of the overlying surface waters. From this data set, the abundance patterns of the main species and their ecological...... seems to be associated with high temperatures and salinities under low-nutrient conditions. Based on the relative abundances of Calcidiscus leptoporus, F. profunda, Gladiolithus flabellatus, Helicosphaera spp., Umbilicosphaera foliosa, Umbilicosphaera sibogae and a group of subordinate subtropical...

  5. Thallium dispersal and contamination in surface sediments from South China and its source identification.

    Science.gov (United States)

    Liu, Juan; Wang, Jin; Chen, Yongheng; Shen, Chuan-Chou; Jiang, Xiuyang; Xie, Xiaofan; Chen, Diyun; Lippold, Holger; Wang, Chunlin

    2016-06-01

    Thallium (Tl) is a non-essential element in humans and it is considered to be highly toxic. In this study, the contents, sources, and dispersal of Tl were investigated in surface sediments from a riverine system (the western Pearl River Basin, China), whose catchment has been contaminated by mining and roasting of Tl-bearing pyrite ores. The isotopic composition of Pb and total contents of Tl and other relevant metals (Pb, Zn, Cd, Co, and Ni) were measured in the pyrite ores, mining and roasting wastes, and the river sediments. Widespread contamination of Tl was observed in the sediments across the river, with the highest concentration of Tl (17.3 mg/kg) measured 4 km downstream from the pyrite industrial site. Application of a modified Institute for Reference Materials and Measurement (IRMM) sequential extraction scheme in representative sediments unveiled that 60-90% of Tl and Pb were present in the residual fraction of the sediments. The sediments contained generally lower (206)Pb/(207)Pb and higher (208)Pb/(206)Pb ratios compared with the natural Pb isotope signature (1.2008 and 2.0766 for (206)Pb/(207)Pb and (208)Pb/(206)Pb, respectively). These results suggested that a significant fraction of non-indigenous Pb could be attributed to the mining and roasting activities of pyrite ores, with low (206)Pb/(207)Pb (1.1539) and high (208)Pb/(206)Pb (2.1263). Results also showed that approximately 6-88% of Tl contamination in the sediments originated from the pyrite mining and roasting activities. This study highlights that Pb isotopic compositions could be used for quantitatively fingerprinting the sources of Tl contamination in sediments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Vortex cores and vortex motion in superconductors with anisotropic Fermi surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Galvis, J.A. [Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Departamento de Ciencias Naturales, Facultad de ingeniería y Ciencias Básicas, Universidad Central, Bogotá (Colombia); National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States); Herrera, E.; Guillamón, I.; Vieira, S. [Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Unidad Asociada de Altos Campos Magnéticos y Bajas Temperaturas, UAM, CSIC, Madrid (Spain); Suderow, H., E-mail: hermann.suderow@uam.es [Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Unidad Asociada de Altos Campos Magnéticos y Bajas Temperaturas, UAM, CSIC, Madrid (Spain)

    2017-02-15

    Highlights: • The observation of vortex cores is reviewed, with emphasis in new experiments. • Vortex cores are follow superconducting gap and Fermi surface shapes. • The vortex core shape influences vortex dynamics. - Abstract: Explaning static and dynamic properties of the vortex lattice in anisotropic superconductors requires a careful characterization of vortex cores. The vortex core contains Andreev bound states whose spatial extension depends on the anisotropy of the electronic band-structure and superconducting gap. This might have an impact on the anisotropy of the superconducting properties and on vortex dynamics. Here we briefly summarize basic concepts to understand anisotropic vortex cores and review vortex core imaging experiments. We further discuss moving vortex lattices and the influence of vortex core shape in vortex motion. We find vortex motion in highly tilted magnetic fields. We associate vortex motion to the vortex entry barrier and the screening currents at the surface. We find preferential vortex motion along the main axis of the vortex lattice. After travelling integers of the intervortex distance, we find that vortices move more slowly due to the washboard potential of the vortex lattice.

  7. Vortex cores and vortex motion in superconductors with anisotropic Fermi surfaces

    International Nuclear Information System (INIS)

    Galvis, J.A.; Herrera, E.; Guillamón, I.; Vieira, S.; Suderow, H.

    2017-01-01

    Highlights: • The observation of vortex cores is reviewed, with emphasis in new experiments. • Vortex cores are follow superconducting gap and Fermi surface shapes. • The vortex core shape influences vortex dynamics. - Abstract: Explaning static and dynamic properties of the vortex lattice in anisotropic superconductors requires a careful characterization of vortex cores. The vortex core contains Andreev bound states whose spatial extension depends on the anisotropy of the electronic band-structure and superconducting gap. This might have an impact on the anisotropy of the superconducting properties and on vortex dynamics. Here we briefly summarize basic concepts to understand anisotropic vortex cores and review vortex core imaging experiments. We further discuss moving vortex lattices and the influence of vortex core shape in vortex motion. We find vortex motion in highly tilted magnetic fields. We associate vortex motion to the vortex entry barrier and the screening currents at the surface. We find preferential vortex motion along the main axis of the vortex lattice. After travelling integers of the intervortex distance, we find that vortices move more slowly due to the washboard potential of the vortex lattice.

  8. The use of downstream sediment mini-cores to indicate changes through time in the spatial pattern and process contribution of erosion within a small, selectively logged rainforest catchment in Sabah, Malaysian Borneo

    Science.gov (United States)

    Williams, R. E.; Walsh, R. P. D.; Coombs, T. J.; Bidin, K.; Blake, W. H.

    2012-04-01

    Multi-proxy sediment fingerprinting (using changes in geochemical variables within downstream floodplain or lateral bench cores and relating them to differences in geochemical character of upstream tributary sediment inputs and/or down soil profiles, preferably in combination with dating using Pb-210 and Cs-137) provides the potential for assessing changes in sediment sources through time. This has rarely been done in tropical rainforest catchments, but needs to be tested at a variety of spatial scales. This poster paper presents the results of an attempt to use mini-cores of bankside sediment to explore changes through post-logging time in the relative contributions made by different sub-catchments to the sediment budget of a small (0.44 sq.km.) Baru catchment (selectively logged in the first half of 1989) in the Danum Valley area of Sabah, Malaysian Borneo. The catchment provides a good testing ground for the technique, as it has been monitored for slope erosion and stream suspended sediment transport continuously from before logging to the present day. The research design comprised (1) sampling (at 2 cm vertical intervals) fluvially deposited sediment down replicated pit profiles at three bankside locations at the downstream end of the catchment between the long-term gauging station and the confluence with a higher-order stream: (2) sampling of the finer bed-sediment the three principal tributaries (2West, 2Middle and 2East) and of surface, sub-surface and deep surface soil material from soil pits and road-cuttings across the catchment; (3) geochemical analysis of the <63μ, 63-125μ and 125μ-2mm fractions of all samples (following drying and sieving), using a portable Niton elemental analyser; (4) graphical and statistical analysis of the data. Pit 1 (34 cm deep) was considered to provide the longest and most dependable sediment record and marked changes in the levels of some elements were detected, with Mn, Fe, Ti and Zr proving to be the most useful. Local

  9. Surface Modification of Cored, Thin Walled Castings of Nickel Superalloy IN-713C

    Directory of Open Access Journals (Sweden)

    Binczyk F.

    2015-09-01

    Full Text Available In current casting technology of cored, thin walled castings, the modifying coating is applied on the surface of wax pattern and, after the removal of the wax, is transferred to inner mould surface. This way the modification leading to grain refinement occur on the surface of the casting. In thin walled castings the modification effect can also be seen on the other (external side of the casting. Proper reproduction of details in thin walled castings require high pouring temperature which intensify the chemical reactions on the mould – molten metal interface. This may lead to degradation of the surface of the castings. The core modification process is thought to circumvent this problem. The modifying coating is applied to the surface of the core. The degradation of internal surface of the casting is less relevant. The most important factor in this technology is “trough” modification – obtaining fine grained structure on the surface opposite to the surface reproduced by the core.

  10. Physical properties of a long sediment core from the central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Khadge, N.H.

    In a 7.5 m-long box core, collected at 9 degrees S and 77 degrees E from 5400 m water depth from the Central Indian Basin, geotechnical properties clearly reflect the Plio-Pleistocene boundary. It is marked by a drastic change in the physical...

  11. Predicting uncertainty in sediment transport and landscape evolution - the influence of initial surface conditions

    Science.gov (United States)

    Hancock, G. R.; Coulthard, T. J.; Lowry, J. B. C.

    2016-05-01

    Numerical landscape evolution models were initially developed to examine natural catchment hydrology and geomorphology and have become a common tool to examine geomorphic behaviour over a range of time and space scales. These models all use a digital elevation model (DEM) as a representation of the landscape surface and a significant issue is the quality and resolution of this surface. Here we focus on how subtle perturbations or roughness on the DEM surface can produce alternative model results. This study is carried out by randomly varying the elevations of the DEM surface and examining the effect on sediment transport rates and geomorphology for a proposed rehabilitation design for a post-mining landscape using multiple landscape realisations with increasing magnitudes of random changes. We show that an increasing magnitude of random surface variability does not appear to have any significant effect on sediment transport over millennial time scales. However, the random surface variability greatly changes the temporal pattern or delivery of sediment output. A significant finding is that all simulations at the end of the 10,000 year modelled period are geomorphologically similar and present a geomorphological equifinality. However, the individual patterns of erosion and deposition were different for repeat simulations with a different sequence of random perturbations. The alternative positions of random perturbations strongly influence local patterns of hillslope erosion and evolution together with the pattern and behaviour of deposition. The findings demonstrate the complex feedbacks that occur even within a simple modelled system.

  12. High-resolution OSL chronology of a sediment core from Lake Nam Co on the southern Tibetan Plateau: Comparison with radiocarbon dating

    Science.gov (United States)

    Long, Hao; Shen, Ji; Haberzettl, Torsten; Fuchs, Markus; Frechen, Manfred; Wang, Junbo

    2013-04-01

    Numerous studies on lake sediment cores from the Tibetan Plateau aimed to reconstruct spatial and temporal changes of the late Glacial and Holocene monsoon variations, which are characterized by fluctuations in precipitation and expansion of monsoonal air masses across the Plateau. Accurate and reliable dating of lacustrine deposits is of crucial importance in both the reconstruction of palaeolake and palaeoclimate evolution and the understanding of the mechanisms for climate changes, especially abrupt changes of regional-hemispheric hydrological circulation. Radiocarbon dating is the most commonly used method for establishing chronologies of lake sediments. However, 14C dating of such sediments could be problematic due to the lack of organic matter or a reservoir effect, which appears common in radiocarbon dating of lacustrine sediments from the Tibetan Plateau. In this study, ca. 10.5 m long core (NC core) was retrieved from the water depth of 93 m at Nam Co Lake, which is the second largest saline lake in China, located on the southern Tibetan Plateau. For this core, high-resolution samples (23 samples) were obtained for optically stimulated luminescence (OSL) dating. Quartz of fine-grain (4-11 μm) fraction were extracted from this samples for OSL dating, which is compared with the 14C chronology of NC core based on accelerator mass spectrometry (AMS) dating of bulk organic matter of 22 samples. The sample from the top of NC core was dated to approximate zero age, indicating the sediments bleached well before deposition. Luminescence behaviors of the study samples further confirmed the robustness of OSL ages. Comparison between OSL and 14C ages suggested that: (1) two kinds of ages are in agreement within error from top to 1.8 m, (2) from 1.8 m to the base of NC core, the 14C ages show a general trend to ca. 4 ka higher ages than the OSL ages. Although 14C dating overestimate the ages from 1.8 m to base, they still show the general trend in sedimentation rate

  13. Trends in chemical concentration in sediment cores from three lakes in New Jersey and one lake on Long Island, New York

    Science.gov (United States)

    Long, Gary R.; Ayers, Mark A.; Callender, Edward; Van Metre, Peter C.

    2003-01-01

    Sediment cores were extracted from three lakes in northeastern New Jersey and one lake on western Long Island, New York, as part of the U.S. Geological Survey National Water-Quality Assessment Program. Sediment layers were dated by use of cesium-137 (137Cs), copper, lead, or dichlorodiphenyl-trichloroethane (DDT) profiles. Sediment layers were analyzed for seven selected trace elements, including arsenic, cadmium, chromium, lead, mercury, nickel, and zinc, and five hydrophobic organochlorine compounds, including chlordane, dieldrin, total DDT, total polychlorinated biphenyls (PCBs), and total polycyclic aromatic hydrocarbons (PAHs).

  14. The secondary calcification of Neogloboquadrina pachyderma assemblages in Arabian Sea waters and surface sediments

    Science.gov (United States)

    Abdolalipour, Samereh; Schulz, Hartmut; Darling, Kate F.

    2014-05-01

    The planktic foraminifer Neogloboquadrina pachyderma (N. pachyderma (sin); Darling et al., 2006) has been recently considered as a (paleo) climatic index in Arabian Sea waters, where increased abundance correlates to the South West monsoon upwelling. Genetic characterization of living specimens collected in multinets off the Oman margin and in the central Arabian Sea indicate the presence of an new genotype of N. pachyderma (Type VIII) (Darling et al., submitted) in the northwestern Indian Ocean. Ecological investigation on these samples reveals that this new genotype, which is the only one to date found in this region, can tolerate warm water temperatures of up to 28° C. It was also found alive below the photic zone within the prominent oxygen minimum zone (OMZ) of the Arabian Sea. To extend our knowledge and understanding of this N. pachyderma Type VIII genotype, we have focused on a morphological analysis of randomly picked specimens (live and dead) from the multinets collected from 200 m down to 700 m water column and from core top sediments distributed over a wide range of water depths (607-3951 m) off the Oman margin in the Arabian Sea. We here use Scanning Electron Microscopy (SEM) to determine the size, shape variation and test wall structure of the penultimate chamber. High resolution measurements confirm the model of chamber growth in non-spinose bilamellar foraminifera of a three or four-layered test wall. As ontogenetic calcite, we were able to visualize the inner lining, the outer layer and the outermost layer formed during the growth of the ultimate chamber. Some of the specimens also showed a fourth layer, which can be attributed to encrustation, observed in higher-latitude specimens of both hemispheres to result from secondary calcification as a terminal step in ontogenetic maturation. To verify the test wall growth and secondary calcification the measurements of the layers were related to the maximum test diameter of the shell. The measurement

  15. Additive surface complexation modeling of uranium(VI) adsorption onto quartz-sand dominated sediments.

    Science.gov (United States)

    Dong, Wenming; Wan, Jiamin

    2014-06-17

    Many aquifers contaminated by U(VI)-containing acidic plumes are composed predominantly of quartz-sand sediments. The F-Area of the Savannah River Site (SRS) in South Carolina (USA) is an example. To predict U(VI) mobility and natural attenuation, we conducted U(VI) adsorption experiments using the F-Area plume sediments and reference quartz, goethite, and kaolinite. The sediments are composed of ∼96% quartz-sand and 3-4% fine fractions of kaolinite and goethite. We developed a new humic acid adsorption method for determining the relative surface area abundances of goethite and kaolinite in the fine fractions. This method is expected to be applicable to many other binary mineral pairs, and allows successful application of the component additivity (CA) approach based surface complexation modeling (SCM) at the SRS F-Area and other similar aquifers. Our experimental results indicate that quartz has stronger U(VI) adsorption ability per unit surface area than goethite and kaolinite at pH ≤ 4.0. Our modeling results indicate that the binary (goethite/kaolinite) CA-SCM under-predicts U(VI) adsorption to the quartz-sand dominated sediments at pH ≤ 4.0. The new ternary (quartz/goethite/kaolinite) CA-SCM provides excellent predictions. The contributions of quartz-sand, kaolinite, and goethite to U(VI) adsorption and the potential influences of dissolved Al, Si, and Fe are also discussed.

  16. Comparison of 210Pb level in Kuala Muda tsunami affected marine sediment core measured using two different techniques

    International Nuclear Information System (INIS)

    Yii Mei Wo; Zal Uyun Wan Mahmood; Jalal Sharib; Zaharudin Ahmad

    2010-01-01

    The most commonly used techniques of alpha and gamma spectrometry were compared to measure 210 Pb activity in marine sediment core. Alpha analytical technique measured the activity of 210 Pb from its in-grow grand-daughter 210 Po after a chemical separation by assuming that there is radioactive equilibrium between the two radionuclides. Meanwhile, gamma analysis technique allows direct measurement, non-destructive and no preliminary chemical separation. Through the comparison, it was found that both alpha and gamma analysis techniques were slightly different. Overall, the results from gamma analytical technique were higher than those from the alpha analytical techniques. Some logical argument had been discussed to explain this situation. In routine analysis, the analytical technique used should be chosen carefully based on advantages and disadvantages of the each technique and analysis requirements. Therefore, it is recommended to determine the exact needs and purpose of analysis and to know the sample history before deciding the appropriate analytical technique. (author)

  17. Characterization of Vadose Zone Sediment: Uncontaminated RCRA Borehole Core Samples and Composite Samples

    International Nuclear Information System (INIS)

    Serne, R. Jeffrey; Bjornstad, Bruce N.; Schaef, Herbert T.; Williams, Bruce A.; Lanigan, David C.; Horton, Duane G.; Clayton, Ray E.; Mitroshkov, Alexandre V.; Legore, Virginia L.; O'Hara, Matthew J.; Brown, Christopher F.; Parker, Kent E.; Kutnyakov, Igor V.; Serne, Jennifer N.; Last, George V.; Smith, Steven C.; Lindenmeier, Clark W.; Zachara, John M.; Burke, Deborah S.

    2008-01-01

    This report was revised in September 2008 to remove acid-extractable sodium data from Tables 4.14, 4.16, 5.20, 5.22, 5.43, and 5.45. The sodium data was removed due to potential contamination introduced during the acid extraction process. The rest of the text remains unchanged from the original report issued in February 2002. The overall goal of the of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities. To meet this goal, CH2M HILL Hanford Group, Inc. asked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediment from within the S-SX Waste Management Area. This report is one in a series of four reports to present the results of these analyses. Specifically, this report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from Resource Conservation and Recovery Act (RCRA) borehole bore samples and composite samples

  18. Characterization of Vadose Zone Sediment: Uncontaminated RCRA Borehole Core Samples and Composite Samples

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R. Jeffrey; Bjornstad, Bruce N.; Schaef, Herbert T.; Williams, Bruce A.; Lanigan, David C.; Horton, Duane G.; Clayton, Ray E.; Mitroshkov, Alexandre V.; Legore, Virginia L.; O' Hara, Matthew J.; Brown, Christopher F.; Parker, Kent E.; Kutnyakov, Igor V.; Serne, Jennifer N.; Last, George V.; Smith, Steven C.; Lindenmeier, Clark W.; Zachara, John M.; Burke, Deborah S.

    2008-09-11

    This report was revised in September 2008 to remove acid-extractable sodium data from Tables 4.14, 4.16, 5.20, 5.22, 5.43, and 5.45. The sodium data was removed due to potential contamination introduced during the acid extraction process. The rest of the text remains unchanged from the original report issued in February 2002. The overall goal of the of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities. To meet this goal, CH2M HILL Hanford Group, Inc. asked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediment from within the S-SX Waste Management Area. This report is one in a series of four reports to present the results of these analyses. Specifically, this report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from Resource Conservation and Recovery Act (RCRA) borehole bore samples and composite samples.

  19. Hexabromocyclododecanes, polybrominated diphenyl ethers, and polychlorinated biphenyls in radiometrically dated sediment cores from English lakes, ~ 1950–present

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Congqiao, E-mail: congqiao.yang@utoronto.ca [School of Geography, Earth, and Environmental Sciences, University of Birmingham, Birmingham B15 2TT (United Kingdom); Rose, Neil L.; Turner, Simon D.; Yang, Handong; Goldsmith, Ben [Environmental Change Research Centre, Department of Geography, University College London, London WC1E 6BT (United Kingdom); Losada, Sara; Barber, Jonathan L. [Centre for Environment, Fisheries and Aquaculture Science, Cefas Lowestoft Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT (United Kingdom); Harrad, Stuart [School of Geography, Earth, and Environmental Sciences, University of Birmingham, Birmingham B15 2TT (United Kingdom)

    2016-01-15

    This paper reports input fluxes between ~ 1950 and present, of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and hexabromocyclododecanes (HBCDs) in radiometrically-dated sediment cores from 7 English lakes. Fluxes of PCBs at all but one location prone to significant sediment resuspension peaked in the late-1960s/early-1990s, before declining thereafter. Input fluxes of HBCDs at all sites increased from first emergence in the mid-1960s. Thereafter, fluxes peaked in the late-1980s/early-2000s, before declining through to the present, except at the most urban site where HBCD fluxes are still increasing. Trends of PBDEs predominant in the Penta-BDE and Octa-BDE formulations vary between sites. While at some locations, fluxes peaked in the late-1990s/early-2000s; at others, fluxes are still increasing. This suggests the full impact of EU restrictions on these formulations has yet to be felt. Fluxes of BDE-209 have yet to peak at all except one location, suggesting little discernible environmental response to recent EU restrictions on the Deca-BDE product. Strikingly, fluxes of BDE-209 in the most recent core slices either exceed or approach peak fluxes of ΣPCBs, implying substantial UK use of Deca-BDE. Excepting HBCDs, inventories of our target contaminants correlated significantly with local population density, implying substantial urban sources. - Highlights: • Temporal trends in PCB inputs consistent with those in UK manufacture & use. • HBCD inputs declining from peak levels at all but the most urban site. • Deca-BDE inputs yet to peak at all but one site. • Varying Penta & Octa-BDE trends imply full impact of restrictions not yet evident. • Excepting HBCDs, contaminant inventories correlate with local population density.

  20. Hydrothermal alteration of sediments associated with surface emissions from the Cerro Prieto geothermal field

    Energy Technology Data Exchange (ETDEWEB)

    Valette-Silver, J.N.; Esquer P., I.; Elders, W.A.; Collier, P.C.; Hoagland, J.R.

    1981-01-01

    A study of the mineralogical changes associated with these hydrothermal vents was initiated with the aim of developing possible exploration tools for geothermal resources. The Cerro Prieto reservoir has already been explored by extensive deep drilling so that relationships between surface manifestations and deeper hydrothermal processes could be established directly. Approximately 120 samples of surface sediments were collected both inside and outside of the vents. The mineralogy of the altered sediments studied appears to be controlled by the type of emission. A comparison between the changes in mineralogy due to low temperature hydrothermal activity in the reservoir, seen in samples from boreholes, and mineralogical changes in the surface emission samples shows similar general trends below 180 C: increase of quartz, feldspar and illite, with subsequent disappearance of kaolinite, montmorillonite, calcite and dolomite. These mineral assemblages seem to be characteristic products of the discharge from high intensity geothermal fields.

  1. Establishment of a Subsidence Superstation in the Mississippi Delta: Integrating sediment core, SET, GPS and vertical strainmeter data to understand subsidence

    Science.gov (United States)

    Steckler, M. S.; Allison, M. A.; Bridgeman, J.; Dixon, T. H.; Hatfield, W.; A Karegar, M.; Tornqvist, T. E.; Zumberge, M. A.; Wyatt, F. K.

    2017-12-01

    There is a great need for coordinated efforts to monitor and better understand subsidence rates in low-elevation coastal zones by integrating different, complementary techniques at carefully selected sites. We present recent efforts to establish a subsidence superstation in the Mississippi Delta. The site is 2 km from the river near Myrtle Grove, Louisiana, at a CRMS (Coastwide Reference Monitoring System) site. The CRMS site consists of a surface elevation table (SET) and marker horizon established in 2008. The surface elevation relative to a rod driven to refusal (26 m) and the sedimentation above the marker horizon is measured semiannually. Adjacent to this site we have added three borehole optical fiber strainmeters that have been providing continuous records of displacement between the near-surface and depths of 10, 26, and 42 m. The instruments provide unprecedented resolution for compaction studies (see Hatfield et al. abstract). We regularly record teleseismic events with amplitudes <1 μm. The records also show a number of days-long compaction and rebound events of less than 1 mm, resulting from changes in the weather and water level. We have attached GPS to each of the wells. For the deepest well, the GPS is anchored to the bottom of the well with the base of the optical strainmeter. For the other two wells, the GPS is anchored to the upper casing of the well. While drilling the wells, a 5" diameter continuous core was collected reaching the Pleistocene boundary at 37 m depth (see Bridgeman et al. abstract). The silty uppermost 10 m, comprised of proximal overbank deposits, reveal up to 5-6 m of subsidence over the past 3000 years. In contrast, the surficial sediments ( 70 cm) are almost entirely organic matter and show little subsidence. The SET shows only 0.4 mm/yr for a 7.4 yr time window. Over the first year, the strainmeters show no long-term compaction or extension greater than ± 0.5 mm. Precise processing of the available GPS data indicates the

  2. Composition and sources of extractable organic matter from a sediment core in Lake Kivu, East African rift valley

    International Nuclear Information System (INIS)

    Al-Mutlaq, Khalid F.; Standley, Laurel J.; Simoneit, Bernd R.T.

    2008-01-01

    Lake Kivu is a gas-charged East African rift lake with currently anoxic bottom water. The extractable compounds and residual organic matter of a short sediment core have δ 13 C values typical of lacustrine microbial detritus. The total extracts consist primarily of polar compounds such as n-alkanoic acids, hydroxyalkanoic acids, triterpenoids, steroids and monosaccharides, with minor amounts of n-alkanes and n-alkanols. These tracer compounds and δ 13 C values indicate that the organic matter in the surficial and deeper sedimentary record was dominated by bacterial sources. The sapropelic sediment between these horizons contains organic matter from primarily algal with lesser bacterial input. Terrestrial organic markers are minor in all samples. The major fractions of the compounds in the total extracts were oxidized in the upper water column prior to transit through the anoxic bottom water to sedimentary deposition. The sapropelic horizon may reflect lake water turnover with ventilation or hydrothermal activity and consequently increased algal blooms

  3. Synoptic conditions of fine-particle transport to the last interglacial Red Sea-Dead Sea from Nd-Sr compositions of sediment cores

    Science.gov (United States)

    Palchan, Daniel; Stein, Mordechai; Goldstein, Steven L.; Almogi-Labin, Ahuva; Tirosh, Ofir; Erel, Yigal

    2018-01-01

    The sediments deposited at the depocenter of the Dead Sea comprise high-resolution archive of hydrological changes in the lake's watershed and record the desert dust transport to the region. This paper reconstructs the dust transport to the region during the termination of glacial Marine Isotope Stage 6 (MIS 6; ∼135-129 ka) and the last interglacial peak period (MIS5e, ∼129-116 ka). We use chemical and Nd and Sr isotope compositions of fine detritus material recovered from sediment core drilled at the deepest floor of the Dead Sea. The data is integrated with data achieved from cores drilled at the floor of the Red Sea, thus, forming a Red Sea-Dead Sea transect extending from the desert belt to the Mediterranean climate zone. The Dead Sea accumulated flood sediments derived from three regional surface cover types: settled desert dust, mountain loess-soils and loess-soils filling valleys in the Dead Sea watershed termed here "Valley Loess". The Valley Loess shows a distinct 87Sr/86Sr ratio of 0.7081 ± 1, inherited from dissolved detrital calcites that originate from dried waterbodies in the Sahara and are transported with the dust to the entire transect. Our hydro-climate and synoptic conditions reconstruction illustrates the following history: During glacial period MIS6, Mediterranean cyclones governed the transport of Saharan dust and rains to the Dead Sea watershed, driving the development of both mountain soils and Valley Loess. Then, at Heinrich event 11, dry western winds blew Saharan dust over the entire Red Sea - Dead Sea transect marking latitudinal expansion of the desert belt. Later, when global sea-level rose, the Dead Sea watershed went through extreme aridity, the lake retreated, depositing salt and accumulating fine detritus of the Valley Loess. During peak interglacial MIS 5e, enhanced flooding activity flushed the mountain soils and fine detritus from all around the Dead Sea and Red Sea, marking a significant "contraction" of the desert belt

  4. Improving understanding of the underlying physical process of sediment wash-off from urban road surfaces

    Science.gov (United States)

    Muthusamy, Manoranjan; Tait, Simon; Schellart, Alma; Beg, Md Nazmul Azim; Carvalho, Rita F.; de Lima, João L. M. P.

    2018-02-01

    Among the urban aquatic pollutants, the most common is sediment which also acts as a transport medium for many contaminants. Hence there is an increasing interest in being able to better predict the sediment wash-off from urban surfaces. The exponential wash-off model is the most widely used method to predict the sediment wash-off. Although a number of studies proposed various modifications to the original exponential wash-off equation, these studies mostly looked into one parameter in isolation thereby ignoring the interactions between the parameters corresponding to rainfall, catchment and sediment characteristics. Hence in this study we aim (a) to investigate the effect of rainfall intensity, surface slope and initial load on wash-off load in an integrated and systematic way and (b) to subsequently improve the exponential wash-off equation focusing on the effect of the aforementioned three parameters. A series of laboratory experiments were carried out in a full-scale setup, comprising of a rainfall simulator, a 1 m2 bituminous road surface, and a continuous wash-off measuring system. Five rainfall intensities ranging from 33 to 155 mm/h, four slopes ranging from 2 to 16% and three initial loads ranging from 50 to 200 g/m2 were selected based on values obtained from the literature. Fine sediment with a size range of 300-600 μm was used for all of the tests. Each test was carried out for one hour with at least 9 wash-off samples per test collected. Mass balance checks were carried out for all the tests as a quality control measure to make sure that there is no significant loss of sand during the tests. Results show that the washed off sediment load at any given time is proportional to initial load for a given combination of rainfall intensity and surface slope. This indicates the importance of dedicated modelling of build-up so as to subsequently predict wash-off load. It was also observed that the maximum fraction that is washed off from the surface increases

  5. Eco-friendly aqueous core surface-modified nanocapsules.

    Science.gov (United States)

    Carbone, C; Musumeci, T; Lauro, M R; Puglisi, G

    2015-01-01

    In this work, positively charged nanocapsules have been developed for potential ocular delivery exploiting the deposition of PLA onto the droplet surface of a W/O nanoemulsion prepared by the reversed procedure of the PIT method. PLA in combination with different amounts of various oils and surfactants have been studied in order to select the best formulation for polymeric nanocapsule preparation. The traditional visual observation together with the Turbiscan(®) technology were exploited in order to identify the best combination of polymer/oil for nanocapsule preparation. Two different primary surfactants (Span(®) 60 and Span(®) 80) have been tested to select their influence on the field of existence of the nanoemulsion by the construction of the pseudoternary phase diagrams. Cationic hybrid NC have been prepared by the addition of a coating layer of DDAB. The physico-chemical and morphological properties of all the prepared nanocapsules have been evaluated and compared by PCS, DSC and AFM. Therefore, positively charged nanocapsules can be easily prepared by a simple eco-friendly technique that exploits biocompatible materials avoiding a large input of mechanical energy as a potential ocular delivery systems for hydrophilic compounds or gene materials. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Heavy metal concentration in mangrove surface sediments from the north-west coast of South America.

    Science.gov (United States)

    Fernández-Cadena, J C; Andrade, S; Silva-Coello, C L; De la Iglesia, R

    2014-05-15

    Mangrove ecosystems are coastal estuarine systems confined to the tropical and subtropical regions. The Estero Salado mangrove located in Guayaquil, Ecuador, has suffered constant disturbances during the past 20 years, due to industrial wastewater release. However, there are no published data for heavy metals present in its sediments and the relationship with anthropogenic disturbance. In the present study, metal concentrations were evaluated in surface sediment samples of the mangrove, showing that B, Cd, Cu, Pb, Se, V, and Zn levels exceeded those declared in international environmental quality standards. Moreover, several metals (Pb, Sn, Cd, Ag, Mo, Zn and Ni) could be linked to the industrial wastewater present in the studied area. In addition, heavy metal levels detected in this mangrove are higher than previous reports on mangrove sediments worldwide, indicating that this mangrove ecosystem is one of the most disrupted on earth. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Distribution of /sup 137/Cs in surface intertidal sediments from the Solway Firth

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D.G.; Miller, J.M.; Roberts, P.D. (Institute of Geological Sciences, Keyworth (UK))

    1984-05-01

    The distribution of /sup 137/Cs from the Sellafield (Windscale) nuclear fuel reprocessing plant has been examined in detail in the surface intertidal sediments of the inner Solway Firth by means of a hovercraft-borne radiometric survey. With the exception of a belt of relatively active sands to the south of Silloth, caesium distribution is generally consistent with that of fine-grained sediment such that the highest concentrations occur in mud flat and salt marsh sediments which are most extensive in sheltered coastal embayments. /sup 137/Cs activities in July 1980 were typically 2 to 30 pCi g/sup -1/ but locally exceeded 50 pCi g/sup -1/. These levels are considerably lower than those recorded in locations, such as the outer Solway and Ravenglass estuary, which are closer to the Sellafield outfall.

  8. Automated Measurement for Sensitivity Analysis of Runoff-Sediment Load at Varying Surface Gradients

    Directory of Open Access Journals (Sweden)

    Imanogor P.A.

    2015-07-01

    Full Text Available Direct measurement of surface runoff is often associated with errors and inaccuracies which results to unreliable hydrological data. An automatic Runoff-meter using tipping buckets arrangement calibrated to tip 0.14 liter of runoff water per tip with an accuracy of ± 0.001 litre was used to measure surface runoff from a steel bounded soil tray of dimension (1200 mm X 900 mm X 260 mm filled with sand loamy to the depth of 130 mm and inclined at angle (0 0 , 5 0 ,12 0 and 15 0 horizontal to the instrument. The effect of varying angles of inclination on runoff intensity, sediment loss rate and sediment loss is significant at 5 % confidence level, while surface runoff is not significant at 5 % confidence level. Total highest sediment loss of 458.2 g and 313.4 g were observed at angle 15 0 and 12 0 respectively. Total surface runoff of 361.5 mm and 445.8 mm were generated at inclined angle of 0 0 and 5 0 , while at angle 12 0 and 15 0 , 564.3 mm and 590.0 mm of surface runoff were generated. In addition, runoff intensity and sediment loss rate were highest at angle 15 0 , while the lowest values of 1.5mm/min and 5.43 g/min were obtained at angle of inclination 5 0 . The results showed that strong relationship existed among the hydrological variables as a result of subjecting the steel bounded soil tray to different angles of inclination. Such results would provide useful data for the running of physics-based deterministic model of surface runoff and erosion which will be useful for the design of hydrological structures, land use planning and management.

  9. 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.

  10. Effect of cosolutes on the sorption of phenanthrene onto mineral surface of river sediments and kaolinite.

    Science.gov (United States)

    Wu, Yinghong; Liu, Fang; Zhang, Wen; Wang, Lei

    2014-01-01

    Sorption of phenanthrene onto the natural sediment with low organic carbon content (OC%), organic-free sediment, and kaolinite was investigated through isotherm experiments. Effects of cosolutes (pyrene, 4-n-nonyphenol (NP), and humic acid (HA)) on phenanthrene sorption were also studied by comparing apparent solid-water distribution coefficients (K d (app)) of phenanthrene. Two addition sequences, including "cosolute added prior to phenanthrene" and "cosolute and phenanthrene added simultaneously," were adopted. The Freundlich model fits phenanthrene sorption on all 3 sorbents well. The sorption coefficients on these sorbents were similar, suggesting that mineral surface plays an important role in the sorption of hydrophobic organic contaminants on low OC% sediments. Cosolutes could affect phenanthrene sorption on the sorbents, which depended on their properties, concentrations, and addition sequences. Pyrene inhibited phenanthrene sorption. Sorbed NP inhibited phenanthrene sorption at low levels and promoted sorption at high levels. Similar to NP, effect of HA on phenanthrene sorption onto the natural sediment depended on its concentrations, whereas, for the organic-free sediment and kaolinite, preloading of HA at high levels led to an enhancement in phenanthrene K d (app) while no obvious effect was observed at low HA levels; dissolved HA could inhibit phenanthrene sorption on the two sorbents.

  11. 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.

  12. Surface Sediment Analysis on Petroleum Hydrocarbon and Total Organic Carbon from Coastal Area of Papar to Tuaran, Sabah

    International Nuclear Information System (INIS)

    Siti Aishah Mohd Ali; Payus, C.; Masni Mohd Ali

    2015-01-01

    Total petroleum hydrocarbons (TPH) and total organic carbon (TOC) were investigated in surface sediments along coastal area of Papar to Tuaran, Sabah. Surface sediment samples were collected in 24 different stations in each area by using Ponar grab sampler. Samples were extracted for TPH using standard method sediment/ sludge APHA 5520E and analyzed using UV/VIS spectrophotometer while for TOC method analysis using United Nations Environment Programme (UNEP)/ MAP Athens (2006). The range of TPH concentrations in surface sediments were recorded at 0.24 - 20.65 mg/ kg dw Miri crude oil equivalents, meanwhile the TOC percentage ranged from 0.03 - 4.02 %. In the mean time, the statistical analysis by Pearson correlation showed a positive correlation with coefficient, r = 0.790 which showing the TPH concentrations significantly have influence on the TOC accumulations in the surface sediment. (author)

  13. Fallout isotope chronology of the near-surface sediment record of Lake Bolătău.

    Science.gov (United States)

    Bihari, Árpád; Karlik, Máté; Mîndrescu, Marcel; Szalai, Zoltán; Grădinaru, Ionela; Kern, Zoltán

    2018-01-01

    Fallout isotope ( 210 Pb ex, 137 Cs and 241 Am) based dating has been carried out on the near-surface sediment core collected from Lake Bolătău-Feredeu (Bukovina, Romania). The motivation was to improve the chronology of this recent section in connection with significant fluctuations observed in sediment accumulation rates, particle size distribution and primordial radioisotope (i.e. 40 K and 232 Th) composition. Previously only an extrapolation of a broad-range OxCal age-depth model, which was based on 8 AMS radiocarbon dates from the deeper part of a parallel sediment sequence and tentatively validated for the upper part using the double peaks of the 137 Cs activity concentration distribution, was available for the studied section (1-24 cm). Parallel to the previous 137 Cs measurement, 210 Pb and 226 Ra (for a more detailed, 210 Pb ex -based chronology), 241 Am (for an additional time-marker), as well as 40 K and 232 Th concentrations have also been determined by gamma-spectrometry. In case of the 210 Pb ex -based chronology, due to a large deviation from a pure exponential distribution, the Constant Flux (CF) model has been used for the calculation of sediment ages and accumulation rates. Although the broad-range OxCal and the CF model were broadly similar down to 22 cm, the 210 Pb ex -based ages are clearly superior in terms of uncertainty in the uppermost 12 cm, while the broad-range model has smaller uncertainty below 20 cm (>150 years). The CF model gave an average mass accumulation rate of (0.08 ± 0.03) g cm -2 yr -1 for sections 0-11 cm, and (0.03 ± 0.01) g cm -2 yr -1 for sections 12-22 cm, respectively. Significant changes have been observed in the depth distribution of both the particle size distribution and the elemental/isotopic composition of the sediment record, most likely related to the variation observable in the intensity and volume of precipitation in the catchment. The obtained high-resolution records of Lake Bolătău, including

  14. Semi-automatic surface sediment sampling system - A prototype to be implemented in bivalve fishing surveys

    Science.gov (United States)

    Rufino, Marta M.; Baptista, Paulo; Pereira, Fábio; Gaspar, Miguel B.

    2018-01-01

    In the current work we propose a new method to sample surface sediment during bivalve fishing surveys. Fishing institutes all around the word carry out regular surveys with the aim of monitoring the stocks of commercial species. These surveys comprise often more than one hundred of sampling stations and cover large geographical areas. Although superficial sediment grain sizes are among the main drivers of benthic communities and provide crucial information for studies on coastal dynamics, overall there is a strong lack of this type of data, possibly, because traditional surface sediment sampling methods use grabs, that require considerable time and effort to be carried out on regular basis or on large areas. In face of these aspects, we developed an easy and un-expensive method to sample superficial sediments, during bivalve fisheries monitoring surveys, without increasing survey time or human resources. The method was successfully evaluated and validated during a typical bivalve survey carried out on the Northwest coast of Portugal, confirming that it had any interference with the survey objectives. Furthermore, the method was validated by collecting samples using a traditional Van Veen grabs (traditional method), which showed a similar grain size composition to the ones collected by the new method, on the same localities. We recommend that the procedure is implemented on regular bivalve fishing surveys, together with an image analysis system to analyse the collected samples. The new method will provide substantial quantity of data on surface sediment in coastal areas, using a non-expensive and efficient manner, with a high potential application in different fields of research.

  15. Heavy metals in the surface sediments of lakes on the Tibetan Plateau, China.

    Science.gov (United States)

    Guo, Bixi; Liu, Yongqin; Zhang, Fan; Hou, Juzhi; Zhang, Hongbo; Li, Chaoliu

    2018-02-01

    Heavy metal contamination has affected many regions in the world, particularly the developing countries of Asia. We investigated 8 heavy metals (Cu, Zn, Cd, Pb, Cr, Co, Ni, and As) in the surface sediments of 18 lakes on the Tibetan Plateau. It was found that the distributions of the heavy metals showed no clear spatial pattern on the plateau. The results indicated that the mean concentrations of these metals in the sediment samples diminished as follows: Cr > As > Zn > Ni > Pb > Cu > Co > Cd. The results of geoaccumulation index (I geo ) and potential ecological risk factor (E i r ) assessments showed that the sediments were moderately polluted by Cd and As, which posed much higher risks than the other metals. The values of the potential ecological risk index (RI) showed that lake Bieruoze Co has been severely polluted by heavy metals. Principal component analysis, hierarchical cluster analysis, and Pearson correlation analysis results indicated that the 8 heavy metals in the lake surface sediments of the Tibetan Plateau could be classified into four groups. Group 1 included Cu, Zn, Pb, Co, and Ni which were mainly derived from both natural and traffic sources. Group 2 included Cd which mainly originated from anthropogenic sources like alloying, electroplating, and dyeing industries and was transported to the Tibetan Plateau by atmospheric circulation. Group 3 included Cr and it might mainly generate from parent rocks of watersheds. The last Group (As) was mainly from manufacturing, living, and the striking deterioration of atmospheric environment of the West, Central Asia, and South Asia.

  16. Heavy metal pollution status in surface sediments of the coastal Bohai Bay.

    Science.gov (United States)

    Gao, Xuelu; Chen, Chen-Tung Arthur

    2012-04-15

    Bohai Bay, the second largest bay of Bohai Sea, largely due to the huge amount of pollutants discharged into it annually and its geohydrologic condition, is considered to be one of the most polluted marine areas in China. To slow down, halt and finally reverse the environmental deterioration of Bohai Sea, some researchers have proposed to connect it with Jiaozhou Bay in the western coast of Southern Yellow Sea by digging an interbasin canal through Shandong Peninsula. In order to assess the heavy metal pollution and provide background information for such a large geoengineering scheme, surface sediments from 42 stations covering both riverine and marine regions of the northwestern coast of Bohai Bay were analyzed for heavy metal content and fractionation (Cd, Cr, Cu, Ni, Pb and Zn). Three empirically derived sediment quality guidelines were used to assess the pollution extent of these metals. The studied metals had low mobility except for Cd at all stations and Zn at some riverine stations. Although a high mobility of Cd was observed, it could hardly cause a bad effect on the environment owing to its low total concentrations. Anthropogenic influence on the accumulation of studied heavy metals in sediments of Bohai Bay was obvious, but their contents were relatively lower to date comparing with some other marine coastal areas that receive important anthropogenic inputs. Taking as a whole, surface sediments of northwestern Bohai Bay had a 21% probability of toxicity based on the mean effects range-median quotient. Copyright © 2012. Published by Elsevier Ltd.

  17. CORE

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin

    2013-01-01

    State-of-the-art in network coding for wireless, meshed networks typically considers two problems separately. First, the problem of providing reliability for a single session. Second, the problem of opportunistic combination of flows by using minimalistic coding, i.e., by XORing packets from...... different flows. Instead of maintaining these approaches separate, we propose a protocol (CORE) that brings together these coding mechanisms. Our protocol uses random linear network coding (RLNC) for intra- session coding but allows nodes in the network to setup inter- session coding regions where flows...

  18. Using lead isotopes and trace element records from two contrasting Lake Tanganyika sediment cores to assess watershed – Lake exchange

    Science.gov (United States)

    Odigie, Kingsley; Cohen, A.D.; Swarzenski, Peter W.; Flegal, R

    2014-01-01

    Lead isotopic and trace element records of two contrasting sediment cores were examined to reconstruct historic, industrial contaminant inputs to Lake Tanganyika, Africa. Observed fluxes of Co, Cu, Mn, Ni, Pb, and Zn in age-dated sediments collected from the lake varied both spatially and temporally over the past two to four centuries. The fluxes of trace elements were lower (up to 10-fold) at a mid-lake site (MC1) than at a nearshore site (LT-98-58), which is directly downstream from the Kahama and Nyasanga River watersheds and adjacent to the relatively pristine Gombe Stream National Park. Trace element fluxes at that nearshore site did not measurably change over the last two centuries (1815–1998), while the distal, mid-lake site exhibited substantial changes in the fluxes of trace elements – likely caused by changes in land use – over that period. For example, the flux of Pb increased by ∼300% from 1871 to 1991. That apparent accelerated weathering and detrital mobilization of lithogenic trace elements was further evidenced by (i) positive correlations (r = 0.77–0.99, p < 0.05) between the fluxes of Co, Cu, Mn, Ni, Pb, and Zn and those of iron (Fe) at both sites, (ii) positive correlations (r = 0.82–0.98, p < 0.01, n = 9) between the fluxes of elements (Al, Co, Cu, Fe, Mn, Ni, Pb, and Zn) and the mass accumulation rates at the offshore site, (iii) the low enrichment factors (EF < 5) of those trace elements, and (iv) the temporal consistencies of the isotopic composition of Pb in the sediment. These measurements indicate that accelerated weathering, rather than industrialization, accounts for most of the increases in trace element fluxes to Lake Tanganyika in spite of the development of mining and smelting operations within the lake’s watershed over the past century. The data also indicate that the mid-lake site is a much more sensitive and useful recorder of environmental changes than the nearshore site. Furthermore, the lead isotopic compositions

  19. Inventory of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb in marine sediments cores of Southwest Atlantic Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Alice M.R.; Oliveira, Joselene de, E-mail: alice.costa@usp.br, E-mail: jolivei@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Gerencia de Metrologia das Radiacoes. Lab. de Radiometria Ambiental; Figueira, Rubens C.L.; Mahiques, Michel M.; Sousa, Silvia H.M., E-mail: rfigueira@usp.br, E-mail: mahiques@usp.br, E-mail: smsousa@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto Oceanografico

    2015-07-01

    {sup 210}Pb (22.3 y) is a radioactive isotope successfully applied as tracer of sediment dating of the last 100-150 years. The application of {sup 226}Ra and {sup 228}Ra as paleoceanographic tracers (half-lives of 1,600 y and 5.7 y, respectively) also gives some information of ocean's role in past climate change. In this work, it was analyzed 2 sediment cores collect at Southwest Atlantic Ocean. The sediments samples were freeze-dried and acid digested in microwave. It was carried out a radiochemical separation of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb and performed a gross alpha and gross beta measurement of both precipitates Ba(Ra)SO{sub 4} and PbCrO{sub 4} in a low background gas-flow proportional counter. Activity concentrations of {sup 226}Ra ranged from 45 Bq kg{sup -1} to 70 Bq kg{sup -1} in NAP-62 and from 57 Bq kg{sup -1} to 82 Bq kg{sup -1} in NAP-63 samples. The concentration of {sup 228}Ra varied between 37 Bq kg{sup -1} and 150 Bq kg{sup -1} in NAP-62 and between 23 Bq kg{sup -1} and 111 Bq kg{sup -1} in NAP-63 samples. The concentration of total {sup 210}Pb ranged from 126 Bq kg{sup -1} to 256 Bq kg{sup -1} in NAP-62 and from 63 Bq kg{sup -1} to 945 Bq kg{sup -1} in NAP-63 samples. Results of {sup 210}Pb{sub uns} varied from 68 Bq kg{sup -1} to 192 Bq kg{sup -1} for NAP-62, while varied from <4.9 Bq kg{sup -1} to 870 Bq kg{sup -1} in NAP-63 profile. Increased values of {sup 210}Pb{sub uns} were found on the top of both NAP-62 and NAP- 63 sediment profile. (author)

  20. Ecological risk evaluation of sediment core samples, Lake Tortum (Erzurum, NE Turkey using environmental indices

    Directory of Open Access Journals (Sweden)

    Hakan Kaya

    2017-11-01

    Full Text Available This study aimed to determine the vertical distribution of heavy metals in a 72 cm-long core sample from Lake Tortum in order to shed light on the implications of potential ecological risks. Analysis was based on the use of environmental indices such as the Integrated Pollution Load Index (PLI and Potential Ecological Risk Index (PER. Results reveal that, except for Pb, Mn and Hg, the lowest concentrations of heavy metals occur at a core depth of between 2 cm and 20 cm for Cu, Zn, Ni, Fe, As, Cd, Cr and Al. The highest concentration was found at sampling intervals of 36 cm and 50 cm, with the exception of Pb, Mn, Hg and Ni. The PLI values from bottom to top are less than 1 while the level with the nearest value to the background value lies at a depth between 24 cm and 26 cm. The PER index results suggest a low ecological risk level for Cu, Pb, Zn, Ni, Mn, Fe, As, Cr, and Al; however, Cd and Hg constitute an ecological threat to the lake ecosystem.

  1. Impact of industrial effluents on geochemical association of metals within intertidal sediments of a creek

    Digital Repository Service at National Institute of Oceanography (India)

    Volvoikar, S.P.; Nayak, G.N.

    Metal speciation studies were carried out on three intertidal core sediments of the industrially impacted Dudh creek located along west coast of India Metals indicated a drastic increase in the bioavailable fraction towards the surface of the cores...

  2. X-ray fluorescence core scanning of wet marine sediments: methods to improve quality and reproducibility of high-resolution paleoenvironmental records

    NARCIS (Netherlands)

    Hennekam, R.; de Lange, G.

    2012-01-01

    X-ray fluorescence (XRF) core-scanning is a convenient non-destructive tool to rapidly assess elemental variations in unprocessed sediments. However, substantial analytical deviations may occur in such data due to physical sedimentary properties. The consequences of these artifacts on element

  3. Simultaneous determination of mercury and organic carbon using a direct mercury analyzer: Mercury profiles in sediment cores from oxbow lakes in the Mississippi Delta

    Science.gov (United States)

    Sediment cores from seasonal wetland and open water areas from six oxbow lakes in the Mississippi River alluvial flood plain were analyzed for total-mercury (Hg) using a direct mercury analyzer (DMA). In the process we evaluated the feasibility of simultaneously determining organic matter content by...

  4. Distribution of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of Pulau Tinggi, Johor

    Science.gov (United States)

    Razak, Ezzati Sulhi Abdul; Halim, Izzyan Syazwani Abdul; Ali, Masni Mohd

    2016-11-01

    Surface sediments samples were collected at 11 stations around the Pulau Tinggi, Johor in September 2015. A total of 15 PAHs were determined and quantified by gas chromatography coupled with mass spectrometry (GC-MS). The total PAH concentrations of surface sediments from Pulau Tinggi ranged from 39.61 ng/g to 149.2 ng/g and they were classified as being in low to moderate pollution range. Individual PAH analysis showed that two and three rings PAHs were the most frequently detected isomers and accounted for 22 - 46% of the total PAH concentrations. The sources of PAHs were evaluated by employing diagnostic ratiosof specific PAH compounds.PAH ratios analysis showed a prevalence of pyrogenic PAH origin at most of the stations with exception of only a few stations.

  5. Effect of surface modification of fiber post using dopamine polymerization on interfacial adhesion with core resin

    Science.gov (United States)

    Li, Yan; Chen, Qian; Yi, Mi; Zhou, Xuegang; Wang, Xinzhi; Cai, Qing; Yang, Xiaoping

    2013-06-01

    The purpose of this study is to evaluate the effects of surface modification of fiber posts using dopamine polymerization on their interfacial adhesion with core resins. The fiber posts were surface-coated with polydopamine via the oxidization polymerization of dopamine in aqueous solution. Two commercial composite resins (3M ESPE and paracore) were used to build up the cores around the post heads (modified and unmodified). Pull-out tests were conducted, and the maximum failure load (N) and the failure modes were recorded to compare the interfacial adhesion between fiber post and resin core. The results demonstrated that the tensile forces needed to damage the retention of fiber post increased from 228.6 ± 10.9 N to 276.3 ± 14.7 N in the 3M ESPE group, from 216.5 ± 17.4 N to 277.2 ± 14.3 N in the paracore group, when polydopamine-coated fiber posts were applied. No significant difference had been found between the different resin groups. The observation of the surface morphology of both fiber posts and cores after adhesive failure clearly confirmed that the presence of polydopamine interlayer had acted as a binder to bond fiber post and resin together. This study would be valuable for endodontically treatments to reduce the chances of detachment of resin core from the fiber post or dislodgement of fiber posts from the canal.

  6. Clyde tributaries : report of urban stream sediment and surface water geochemistry for Glasgow

    OpenAIRE

    Fordyce, F.M.; O Dochartaigh, B.E.O.; Lister, T.R.; Cooper, R.; Kim, A.; Harrison, I.; Vane, C.; Brown, S.E.

    2004-01-01

    This report presents the results of an urban drainage geochemical survey carried out jointly by the British Geological Survey (BGS) and Glasgow City Council (GCC) during June 2003. 118 stream sediment and 122 surface water samples were collected at a sample density of 1 per 1 km2 from all tributaries draining into the River Clyde within the GCC administrative area. The study was carried out as part of the BGS systematic Geochemical Surveys of Urban Environments (GSUE) programme. Stream sed...

  7. Aerobic and Anaerobic Bacterial Isolates on the Surface and Core of Tonsils from Patients with Chronic Tonsillitis

    Directory of Open Access Journals (Sweden)

    Meera Niranjan Khadilkar

    2017-08-01

    Full Text Available Introduction Controversy regarding treatment of tonsillitis based on throat culture report still persists. If surface culture is a determinant of bacteriology of the core, then rational therapy could be aimed at organisms cultured by surface swab. Materials and Methods A Cross-sectional study was conducted on 100 patients of chronic tonsillitis who underwent tonsillectomy. Tonsil surface and core swabs were studied for aerobic and anaerobic growth. Result Eighty seven percent patients had aerobic growth on tonsil surface and ninety percent in tonsil core. Staphylococcus aureus was the commonest aerobic bacteria isolated. Anaerobic growth was present in 47% patients on tonsil surface, and 48% in core. Porphyromonas sp. was the commonest anaerobic bacterium isolated. Discussion There was no statistically significant difference between aerobic and anaerobic bacteria found in tonsil surface and core.  Conclusion Throat swabs adequately represent core pathogen, and are dependable in detecting bacteriology of chronic tonsillitis.

  8. Foam Core Particleboards with Intumescent FRT Veneer: Cone Calorimeter Testing With Varying Adhesives, Surface Layer Thicknesses, and Processing Conditions

    Science.gov (United States)

    Mark A. Dietenberger; Johannes Welling; Ali Shalbafan

    2014-01-01

    Intumescent FRT Veneers adhered to the surface of foam core particleboard to provide adequate fire protection were evaluated by means of cone calorimeter tests (ASTM E1354). The foam core particleboards were prepared with variations in surface layer treatment, adhesives, surface layer thicknesses, and processing conditions. Ignitability, heat release rate profile, peak...

  9. Planetary gyre, time-dependent eddies, torsional waves, and equatorial jets at the Earth's core surface

    DEFF Research Database (Denmark)

    Gillet, N.; Jault, D.; Finlay, Chris

    2015-01-01

    We report a calculation of time-dependent quasi-geostrophic core flows for 1940–2010. Inverting recursively for an ensemble of solutions, we evaluate the main source of uncertainties, namely, the model errors arising from interactions between unresolved core surface motions and magnetic fields...... between the magnetic field and subdecadal nonzonal motions within the fluid outer core. Both the zonal and the more energetic nonzonal interannual motions were particularly intense close to the equator (below 10∘ latitude) between 1995 and 2010. We revise down the amplitude of the decade fluctuations...... of the planetary-scale circulation and find that electromagnetic core-mantle coupling is not the main mechanism for angular momentum exchanges on decadal time scales if mantle conductance is 3 × 108 S or lower....

  10. Application of a surface complexation model to the interactions of Pu and Am with Esk Estuary sediments

    International Nuclear Information System (INIS)

    Turner, D.R.; Knox, S.; Titley, J.G.; Hamilton-Taylor, J.; Kelly, M.; Williams, G.

    1990-10-01

    Previous work has shown that Pu is remobilised from Esk sediments at low salinities of overlying water. A constant capacitance surface complexation model has been developed in order to understand and model the chemical processes occurring. The model is based on detailed chemical characterisation of sediment samples from the estuary. The following measurements were carried out to provide input parameters for the model: specific surface area; total surface sites (tritium exchange); proton and major ion exchange (potentiometric titration); and actinide (Pu and Am) partition coefficient as a function of pH and salinity at sediment and actinide concentrations typical of the Esk. (author)

  11. Dynamics of metallic contaminants at a basin scale--Spatial and temporal reconstruction from four sediment cores (Loire fluvial system, France).

    Science.gov (United States)

    Dhivert, E; Grosbois, C; Courtin-Nomade, A; Bourrain, X; Desmet, M

    2016-01-15

    From the 19th century, the Loire basin (France) presents potentially pollutant activities such as mining and heavy industries. This paper shows spatio-temporal distribution of trace elements in sediments at a basin-scale, based on a comparison of archived temporal signals recorded in four sedimentary cores. Anthropogenic sources contributing to sediment contamination are also characterized, using geochemical signatures recorded in river bank sediments of the most industrialized tributaries. This study highlights upstream-downstream differences concerning recorded contamination phases in terms of spatial influence and temporality of archiving processes. Such differences were related to (i) various spatial influences of contamination sources and (ii) polluted sediments dispersion controlled by transport capacity of metal-carrier phases and hydrosedimentary dynamics. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Hominin Sites and Paleolakes Drilling Project. Chew Bahir, southern Ethiopia: How to get from three tonnes of sediment core to > 500 ka of continuous climate history?

    Science.gov (United States)

    Foerster, Verena; Asrat, Asfawossen; Cohen, Andrew S.; Gromig, Raphael; Günter, Christina; Junginger, Annett; Lamb, Henry F.; Schaebitz, Frank; Trauth, Martin H.

    2016-04-01

    In search of the environmental context of the evolution and dispersal of Homo sapiens and our close relatives within and beyond the African continent, the ICDP-funded Hominin Sites and Paleolakes Drilling Project (HSPDP) has recently cored five fluvio-lacustrine archives of climate change in East Africa. The sediment cores collected in Ethiopia and Kenya are expected to provide valuable insights into East African environmental variability during the last ~3.5 Ma. The tectonically-bound Chew Bahir basin in the southern Ethiopian rift is one of the five sites within HSPDP, located in close proximity to the Lower Omo River valley, the site of the oldest known fossils of anatomically modern humans. In late 2014, the two cores (279 and 266 m long respectively, HSPDP-CHB14-2A and 2B) were recovered, summing up to nearly three tonnes of mostly calcareous clays and silts. Deciphering an environmental record from multiple records, from the source region of modern humans could eventually allow us to reconstruct the pronounced variations of moisture availability during the transition into Middle Stone Age, and its implications for the origin and dispersal of Homo sapiens. Here we present the first results of our analysis of the Chew Bahir cores. Following the HSPDP protocols, the two parallel Chew Bahir sediment cores have been merged into one single, 280 m long and nearly continuous (>90%) composite core on the basis of a high resolution MSCL data set (e.g., magnetic susceptibility, gamma ray density, color intensity transects, core photographs). Based on the obvious cyclicities in the MSCL, correlated with orbital cycles, the time interval covered by our sediment archive of climate change is inferred to span the last 500-600 kyrs. Combining our first results from the long cores with the results from the accomplished pre-study of short cores taken in 2009/10 along a NW-SE transect across the basin (Foerster et al., 2012, Trauth et al., 2015), we have developed a hypothesis

  13. Asteroseismic measurement of surface-to-core rotation in a main-sequence star*

    Directory of Open Access Journals (Sweden)

    Kurtz Donald W.

    2015-01-01

    Full Text Available We have discovered rotationally split core g-mode triplets and surface p-mode triplets and quintuplets in a terminal age main-sequence A star, KIC 11145123, that shows both δ Sct p-mode pulsations and γ Dor g-mode pulsations. This gives the first robust determination of the rotation of the deep core and surface of a main-sequence star, essentially model-independently. We find its rotation to be nearly uniform with a period near 100 d, but we show with high confidence that the surface rotates slightly faster than the core. A strong angular momentum transfer mechanism must be operating to produce the nearly rigid rotation, and a mechanism other than viscosity must be operating to produce a more rapidly rotating surface than core. Our asteroseismic result, along with previous asteroseismic constraints on internal rotation in some B stars, and measurements of internal rotation in some subgiant, giant and white dwarf stars, has made angular momentum transport in stars throughout their lifetimes an observational science.

  14. Surface-Active Agents for Isolation of the Core Component of Avian Myeloblastosis Virus 1

    Science.gov (United States)

    Stromberg, Kurt

    1972-01-01

    Sixty-one surface-active agents were evaluated in a procedure designed to assess their ability to remove the envelope from the core component of avian myeloblastosis virus (AMV). The procedure consisted of centrifugation of intact AMV through a series of sucrose gradients each containing an upper layer of agent at one of eight concentrations between 0.01 and 10%. The effectiveness of an agent in producing AMV cores was indicated by (i) the appearance of light-scattering bands in the region of core buoyant density in gradient tubes; (ii) the range of surfactant concentration over which these bands appeared; and (iii) an electron microscopy assessment by the negative-staining technique of the relative proportion of core to non-core material in each of these bands. Six nonionic surfactants were selected by this screening method for comparison in regard to recovery of core protein and endogenous ribonucleic acid (RNA)-dependent deoxyribonucleic acid (DNA) polymerase activity, as well as further morphologic evaluation by electron microscopy. The nonionic surfactants of the polyoxyethylene alcohol class (particularly, Sterox SL) were most effective. Nonionic surfactants of the polyoxyethylene alkylphenol class (particularly, Nonidet P-40) were also effective. Sterox SL and Nonidet P-40 each gave a more than fivefold increase in specific activity of endogenous RNA-dependent DNA polymerase, and each gave a low recovery of core protein. Sterox SL did not interfere to the extent that Nonidet P-40 did in procedures which involved spectrophotometric assay at 260 nm. The use of Sterox SL resulted in the least envelope contamination of core preparations by electron microscopy examination, the most recovery of protein and endogenous RNA-dependent DNA polymerase activity, and a core buoyant density in sucrose of 1.27 g/ml. Images PMID:4112071

  15. Approaches to surface complexation modeling of Uranium(VI) adsorption on aquifer sediments

    Science.gov (United States)

    Davis, J.A.; Meece, D.E.; Kohler, M.; Curtis, G.P.

    2004-01-01

    Uranium(VI) adsorption onto aquifer sediments was studied in batch experiments as a function of pH and U(VI) and dissolved carbonate concentrations in artificial groundwater solutions. The sediments were collected from an alluvial aquifer at a location upgradient of contamination from a former uranium mill operation at Naturita, Colorado (USA). The ranges of aqueous chemical conditions used in the U(VI) adsorption experiments (pH 6.9 to 7.9; U(VI) concentration 2.5 ?? 10-8 to 1 ?? 10-5 M; partial pressure of carbon dioxide gas 0.05 to 6.8%) were based on the spatial variation in chemical conditions observed in 1999-2000 in the Naturita alluvial aquifer. The major minerals in the sediments were quartz, feldspars, and calcite, with minor amounts of magnetite and clay minerals. Quartz grains commonly exhibited coatings that were greater than 10 nm in thickness and composed of an illite-smectite clay with occluded ferrihydrite and goethite nanoparticles. Chemical extractions of quartz grains removed from the sediments were used to estimate the masses of iron and aluminum present in the coatings. Various surface complexation modeling approaches were compared in terms of the ability to describe the U(VI) experimental data and the data requirements for model application to the sediments. Published models for U(VI) adsorption on reference minerals were applied to predict U(VI) adsorption based on assumptions about the sediment surface composition and physical properties (e.g., surface area and electrical double layer). Predictions from these models were highly variable, with results overpredicting or underpredicting the experimental data, depending on the assumptions used to apply the model. Although the models for reference minerals are supported by detailed experimental studies (and in ideal cases, surface spectroscopy), the results suggest that errors are caused in applying the models directly to the sediments by uncertain knowledge of: 1) the proportion and types of

  16. Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea.

    Science.gov (United States)

    Cho, Jinhyung; Hyun, Sangmin; Han, J-H; Kim, Suhyun; Shin, Dong-Hyeok

    2015-06-15

    The spatiotemporal distribution and their mass accumulation rate (MAR) of heavy metals were investigated to evaluate the time-dependent historical trends of heavy metal concentration. The three short cores used for this study were collected from the catchment area (MS-PC5, 60cm length), the central part (MS-PC4, 40cm length) and the offshore (MS-PC2, 60cm length) of the Masan Bay, Korea. The concentration of heavy metals (Co, Ni, Cu, Zn, Cr and Pb) in catchment area is as much as 1.5-2 times higher than central part of the Bay, and about 2 times higher than offshore area approximately. In particular, MAR of metals (Cu, Zn and Pb) show clear spatiotemporal variation, so that MAR's of heavy metal may provide more accurate information in evaluating the degree of pollution. Temporally, the heavy metal concentration had been increased since the late 1970s, but it seems to decrease again since the 2004yr in catchment area. This may came from concentrated efforts for the government to reduce industrial waste release. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Identification of contamination in a lake sediment core using Hg and Pb isotopic compositions, Lake Ballinger, Washington, USA

    International Nuclear Information System (INIS)

    Gray, John E.; Pribil, Michael J.; Van Metre, Peter C.; Borrok, David M.; Thapalia, Anita

    2013-01-01

    Highlights: ► Hg and Pb concentration and isotopic compositions traced anthropogenic sources. ► Concentrations and metal loadings of Hg and Pb increased during the smelting period. ► Hg isotopic compositions changed during smelting compared to the pre-smelting period. ► Data indicate mass independent fractionation of Hg isotopes. - Abstract: Concentrations and isotopic compositions of Hg and Pb were measured in a sediment core collected from Lake Ballinger, near Seattle, Washington, USA. Lake Ballinger has been affected by input of metal contaminants emitted from the Tacoma smelter, which operated from 1887 to 1986 and was located about 53 km south of the lake. Concentrations and loadings of Hg and Pb in Lake Ballinger increased by as much as three orders of magnitude during the period of smelting as compared to the pre-smelting period. Concentrations and loadings of Hg and Pb then decreased by about 55% and 75%, respectively, after smelting ended. Isotopic compositions of Hg changed considerably during the period of smelting (δ 202 Hg = −2.29‰ to −0.38‰, mean −1.23‰, n = 9) compared to the pre-smelting period (δ 202 Hg = −2.91‰ to −2.50‰, mean −2.75‰, n = 4). Variations were also observed in 206 Pb/ 207 Pb and 208 Pb/ 207 Pb isotopic compositions during these periods. Data for Δ 199 Hg and Δ 201 Hg indicate mass independent fractionation (MIF) of Hg isotopes in Lake Ballinger sediment during the smelting and post-smelting period and suggest MIF in the ore smelted, during the smelting process, or chemical modification at some point in the past. Negative values for Δ 199 Hg and Δ 201 Hg for the pre-smelting period are similar to those previously reported for soil, peat, and lichen, likely suggesting some component of atmospheric Hg. Variations in the concentrations and isotopic compositions of Hg and Pb were useful in tracing contaminant sources and the understanding of the depositional history of sedimentation in Lake Ballinger

  18. Effect of soil surface conditions on runoff velocity and sediment mean aggregate diameter

    Science.gov (United States)

    César Ramos, Júlio; Bertol, Ildegardis; Paz González, Antonio; de Souza Werner, Romeu; Marioti, Juliana; Henrique Bandeira, Douglas; Andrighetti Leolatto, Lidiane

    2013-04-01

    Soil cover and soil management are the factors that most influence soil erosion by water, because they directly affect soil surface roughness and surface cover. The main effect of soil cover by crop residues consists in dissipation of kinetic energy of raindrops and also partly kinetic energy of runoff, so that the soil disaggregation is considerably reduced but, in addition, soil cover captures detached soil particles, retains water on its surface and decreases runoff volume and velocity. In turn, soil surface roughness, influences soil surface water storage and infiltration and also runoff volume and velocity, sediment retention and subsequently water and sediment losses. Based on the above rationale, we performed a field experiment to assess the influence of soil cover and soil surface roughness on decay of runoff velocity as well as on mean diameter of transported sediments (D50 index). The following treatments were evaluated: SRR) residues of Italian ryegrass (Lolium multiflorum) on a smooth soil surfcace, SRV) residues of common vetch (Vicia sativa) on a smooth soil surface, SSR) scarification after cultivation of Italian ryegrass resulting in a rough surface, SSV) scarification after cultivation of common vetch resulting in a rough surface, and SBS) scarified bare soil with high roughness as a control. The field experiments was performed on an Inceptisol in South Brazil under simulated rainfall conditions during 2012. Experimental plots were 11 m long and 3.5 m wide with an area of 38.5 m2. Six successive simulated rainfall tests were applied using a rotating-boom rain simulator. During each test, rain intensity was 60 mmhr-1, whereas rain duration was 90 minutes. Runoff velocity showed no significant differences between cultivated treatments. However, when compared to bare soil treatment, SBS (0.178 m s-1) and irrespective of the presence of surface crop residues or scarification operations, cultivated soil treatments significantly reduced runoff velocity

  19. Core-and-surface-functionalized polyphenylene dendrimers for solution-processed, pure-blue light-emitting diodes through surface-to-core energy transfer.

    Science.gov (United States)

    Zhang, Guang; Baumgarten, Martin; Auer, Manuel; Trattnig, Roman; List-Kratochvil, Emil J W; Müllen, Klaus

    2014-11-01

    Several pyrene-based polyphenylene dendrimers (PYPPDs) with different peripheral chromophores (PCs) are synthesized and characterized. Deep blue emissions solely from the core are observed for all of them in photoluminescence spectra due to good steric shielding of the core and highly efficient surface-to-core Förster resonant energy transfers (FRETs). Device performances are found in good correlation with the energy gaps between the work function of the electrodes and the frontier molecular orbital (FMO) levels of the PCs. Pure blue emission, luminance as high as 3700 cd m(-2) with Commission Internationale de l'Éclairage 1931 (CIE(xy)) = (0.16, 0.21), and a peak current efficiency of 0.52 cd A(-1) at CIE(xy) = (0.17, 0.20) are achieved. These dendrimers are among the best dendritic systems so far for fluorescent blue light-emitting materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Concentrations and sources of polycyclic aromatic hydrocarbons in surface coastal sediments of the northern Gulf of Mexico

    Science.gov (United States)

    2014-01-01

    Background Coastal sediments in the northern Gulf of Mexico have a high potential of being contaminated by petroleum hydrocarbons, such as polycyclic aromatic hydrocarbons (PAHs), due to extensive petroleum exploration and transportation activities. In this study we evaluated the spatial distribution and contamination sources of PAHs, as well as the bioavailable fraction in the bulk PAH pool, in surface marsh and shelf sediments (top 5 cm) of the northern Gulf of Mexico. Results PAH concentrations in this region ranged from 100 to 856 ng g−1, with the highest concentrations in Mississippi River mouth sediments followed by marsh sediments and then the lowest concentrations in shelf sediments. The PAH concentrations correlated positively with atomic C/N ratios of sedimentary organic matter (OM), suggesting that terrestrial OM preferentially sorbs PAHs relative to marine OM. PAHs with 2 rings were more abundant than those with 5–6 rings in continental shelf sediments, while the opposite was found in marsh sediments. This distribution pattern suggests different contamination sources between shelf and marsh sediments. Based on diagnostic ratios of PAH isomers and principal component analysis, shelf sediment PAHs were petrogenic and those from marsh sediments were pyrogenic. The proportions of bioavailable PAHs in total PAHs were low, ranging from 0.02% to 0.06%, with higher fractions found in marsh than shelf sediments. Conclusion PAH distribution and composition differences between marsh and shelf sediments were influenced by grain size, contamination sources, and the types of organic matter associated with PAHs. Concentrations of PAHs in the study area were below effects low-range, suggesting a low risk to organisms and limited transfer of PAHs into food web. From the source analysis, PAHs in shelf sediments mainly originated from direct petroleum contamination, while those in marsh sediments were from combustion of fossil fuels. PMID:24641695

  1. Innovative eco-friendly bio- solvent for combating sea surface and sedimented oil pollution

    Science.gov (United States)

    Theodorou, Paraskevas

    2017-04-01

    The combating of oil spill at sea surface by chemical dispersants accelerates the evaporation and disperse the oil into the water column, where it is broken down by natural processes and/or is sedimented at the sea bottom, especially at near coastal shallow areas, ports and marinas. The usual methodology for cleaning the sedimented oil from the sea bottom is mainly carried out via excavation and dumping of the polluted sediment into deeper sea areas, where the contamination is transferred from one area to another. The eco-friendly bio-solvent MSL Aqua 250 is an innovative new solution based mainly on natural constituents. The action mechanism and the effectiveness of this eco-friendly solvent is based on the high surface tension process. Organic compounds, including hydrocarbons upon coming in contact with MSL Aqua 250 solvent generate a significant surface tension reaction, which is able to alter the organic compounds to liquid form and then to drastically evaporate it. The use of MSL Aqua 250 solvent, both at sea surface and at the bottom, has the following advantages compared to the dispersants: • Efficient solution without transferring the pollution from sea surface to the water column and to the bottom or disturbing the Aquatic Eco System. • Non-Toxic. • Environmentally friendly with a restoration of marine life in the Eco System. • Cost effective. The MSL Aqua 250 solvent has been tested in cooperation with the Cyprus Department of Fisheries and Marine Research and the Technological University of Cyprus and used during the years 2015 and 2016 in marinas and fishing shelters in Cyprus faced oil pollution, with high concentration in the sea water and at the sea bottom of chemical parameters (BOD5, COD, FOG, TKN, TP, TPH), with excellent results.

  2. CSciBox: An Intelligent Assistant for Dating Ice and Sediment Cores

    Science.gov (United States)

    Finlinson, K.; Bradley, E.; White, J. W. C.; Anderson, K. A.; Marchitto, T. M., Jr.; de Vesine, L. R.; Jones, T. R.; Lindsay, C. M.; Israelsen, B.

    2015-12-01

    CSciBox is an integrated software system for the construction and evaluation of age models of paleo-environmental archives. It incorporates a number of data-processing and visualization facilities, ranging from simple interpolation to reservoir-age correction and 14C calibration via the Calib algorithm, as well as a number of firn and ice-flow models. It employs modern database technology to store paleoclimate proxy data and analysis results in an easily accessible and searchable form, and offers the user access to those data and computational elements via a modern graphical user interface (GUI). In the case of truly large data or computations, CSciBox is parallelizable across modern multi-core processors, or clusters, or even the cloud. The code is open source and freely available on github, as are one-click installers for various versions of Windows and Mac OSX. The system's architecture allows users to incorporate their own software in the form of computational components that can be built smoothly into CSciBox workflows, taking advantage of CSciBox's GUI, data importing facilities, and plotting capabilities. To date, BACON and StratiCounter have been integrated into CSciBox as embedded components. The user can manipulate and compose all of these tools and facilities as she sees fit. Alternatively, she can employ CSciBox's automated reasoning engine, which uses artificial intelligence techniques to explore the gamut of age models and cross-dating scenarios automatically. The automated reasoning engine captures the knowledge of expert geoscientists, and can output a description of its reasoning.

  3. Surface Plasmon Scattering in Exposed Core Optical Fiber for Enhanced Resolution Refractive Index Sensing.

    Science.gov (United States)

    Klantsataya, Elizaveta; François, Alexandre; Ebendorff-Heidepriem, Heike; Hoffmann, Peter; Monro, Tanya M

    2015-09-29

    Refractometric sensors based on optical excitation of surface plasmons on the side of an optical fiber is an established sensing architecture that has enabled laboratory demonstrations of cost effective portable devices for biological and chemical applications. Here we report a Surface Plasmon Resonance (SPR) configuration realized in an Exposed Core Microstructured Optical Fiber (ECF) capable of optimizing both sensitivity and resolution. To the best of our knowledge, this is the first demonstration of fabrication of a rough metal coating suitable for spectral interrogation of scattered plasmonic wave using chemical electroless plating technique on a 10 μm diameter exposed core of the ECF. Performance of the sensor in terms of its refractive index sensitivity and full width at half maximum (FWHM) of SPR response is compared to that achieved with an unstructured bare core fiber with 140 μm core diameter. The experimental improvement in FWHM, and therefore the detection limit, is found to be a factor of two (75 nm for ECF in comparison to 150 nm for the large core fiber). Refractive index sensitivity of 1800 nm/RIU was achieved for both fibers in the sensing range of aqueous environment (1.33-1.37) suitable for biosensing applications.

  4. Occurrence and profiles of organic sun-blocking agents in surface waters and sediments in Japanese rivers and lakes

    Energy Technology Data Exchange (ETDEWEB)

    Kameda, Yutaka, E-mail: kameda.yutaka@pref.saitama.lg.jp [Center for Environmental Science in Saitama, Kamitanadare 914, Kazo 347-0115 (Japan); Kimura, Kumiko; Miyazaki, Motonobu [Saitama City Institute of Health Science and Research, Suzuya 7-5-12, Chuo-ku, Saitama 338-0013 (Japan)

    2011-06-15

    Sun-blocking agents including eight UV filters (UVF) and 10 UV light stabilizers (UVLS) were measured in water and sediment collected from 22 rivers, four sewage treatment plant effluents (STPE) and three lakes in Japan. Total sun blocking agents levels ranged from N.D. to 4928 ng/L and from 2.0 to 3422 {mu}g/kg dry wt in surface water and in sediment, respectively. Benzyl salicylate, benzophenone-3, 2-ethyl hexyl-4-methoxycinnamte (EHMC) and octyl salicylate were dominant in surface water receiving wastewater effluents and STPE, although UV-328, benzophenone and EHMC were dominant in other surface water except background sites. Three UVF and nine UVLS were observed from all sediment and their compositions showed similar patterns with UV-328 and UV-234 as the most prevalent compounds. Homosalate, octocrylene, UV-326, UV-327, UV-328 and UV-234 were significantly correlated with Galaxolide in sediments. Concentrations of UV-327 and UV-328 also had strong correlation between those of UV-326 in sediment. - Highlights: > Total sun-blocking agents levels ranged from N.D. to 4928 ng/L in surface water from 29 sampling sites. > The maximum concentration of total sun-blocking agents was 3422 {mu}g/kg dry wt. in sediment. > Residential wastewaters and STPE were considered to be potential sources of UVLS in river and lakes. > Most of sun-blocking agents in sediment were significantly correlated with HHCB. > UV-326 had a strong linear correlation between UV-327 as well as UV-328 in all sediment. - Occurrence of eight UV filters and 10 UV light stabilizers in surface water and sediment were investigated and characterized their compositions in water and sediment.

  5. Mercury in dated Greenland marine sediments

    DEFF Research Database (Denmark)

    Asmund, G.; Nielsen, S.P.

    2000-01-01

    Twenty marine sediment cores from Greenland were analysed for mercury, and dated by the lead-210 method. In general the cores exhibit a mercury profile with higher mercury concentrations in the upper centimetres of the core. The cores were studied by linear regression of In Hg vs, age...... of the sediment for the youngest 100 years. As a rule the mercury decreased with depth in the sediment with various degrees of significance. The increase of the mercury flux during the last 100 years is roughly a doubling. The increase may be of anthropogenic origin as it is restricted to the last 100 years....... In four cores the concentration of manganese was found also to increase in the top layers indicating diagenesis. In the other cases the higher concentrations were not accompanied by higher manganese concentrations. The mercury flux to the sediment surface was generally proportional to the Pb-210 flux...

  6. PAH fluxes in the Laja Lake of south central Chile Andes over the last 50 years: Evidence from a dated sediment core

    International Nuclear Information System (INIS)

    Quiroz, Roberto; Popp, Peter; Urrutia, Roberto; Bauer, Coretta; Araneda, Alberto; Treutler, Hanns-Christian; Barra, Ricardo

    2005-01-01

    This paper reports the occurrence of polyaromatic hydrocarbons (PAHs) deposition inferred from a sediment core of an Andean lake in south central Chile. Sediments were carefully collected from one of the deepest section of the lake and sliced every 1 cm. The samples were analyzed for PAHs, 137 Cs, 210 Pb, organic carbon and grain-size. The stratigraphic chronology and the sedimentation rates were estimated using the sedimentary signature left by the 137 Cs and 210 Pb fallout as temporal markers. PAHs were quantified by HPLC-fluorescence detection (HPLC-Fluorescence). 15 priority EPA PAHs were analyzed in this study. Based on these results, PAH deposition over the last 50 years was estimated (a period characterized by an important intervention in the area). PAH concentration ranged from 226 to 620 ng g -1 d.w. The highest concentrations of PAHs were found in the core's bottom. The PAH profile is dominated by the presence of perylene indicating a natural source of PAH. In addition, two clear PAH deposition periods could be determined: the most recent with two-four rings PAHs, the older one with five-seven rings predomination. Determined fluxes where 71 to 972 μg m -2 year -1 , dominated by perylene deposition. PAH levels and fluxes are lower compared to the levels found in sediments from remote lakes in Europe and North America. It is concluded that the main source of PAHs into the Laja Lake sediments are of natural origin

  7. Concentration, enrichment and distribution of heavy metals in surface sediments of the Tangier Bay, Morocco

    Directory of Open Access Journals (Sweden)

    María Rocío Rodríguez-Barroso

    2010-11-01

    Full Text Available The distribution, enrichment, and accumulation of heavy metals in the surface sediments of the Tangier Bay, Morocco, were investigated. Surface sediment samples from eleven locations in the Bay of Tangier were collected in 2007 and characterized for grain size, organic matter and metal content (e.g. Fe, Mn, Cr, Cu, Ni, Pb, Zn and Cd. The evaluation of the heavy metal contamination status of the bay showed minor enrichment by the enrichment factors (EF calculation, corroborated by the metal pollution index (MPI. The results of a Pearson correlation showed high positive correlations among organic carbon and most metals (0.788 < r < 0.939 and cluster analysis grouped the stations inside the harbour (stations 1, 10 and 9 and in the vicinity of the principal rivers in the bay (stations 3 and 11, which showed the highest concentrations of metal content. The main sources of contamination are domestic and industrial effluents, which arise due to the lack of sewage treatment. However, these areas could not be classified as polluted when the data were compared with sediment quality guidelines (USEPA, 1997.

  8. Radiological impact of surface water and sediment near uranium mining sites.

    Science.gov (United States)

    Ivanova, K; Stojanovska, Z; Badulin, V; Kunovska, B; Yovcheva, M

    2015-12-01

    The aim of this study is to assess the radiological impact of surface water and sediment around uranium mining sites 20 years after their closing. The areas under observations are 31 former classical underground uranium mining and exploratory sites in Bulgaria, named as objects. The extraction and processing of uranium ores in the Republic of Bulgaria were ended in 1992. To assess the radiological impact of radionuclides field expeditions were performed to sample water and bottom sediment. The migration of uranium through surface water was examined as one of the major pathways for contamination spread. The range of uranium concentration in water flowing from the mining sites was from 0.012 to 6.8 mgU l(-1) with a geometric mean of 0.192 mgU l(-1). The uranium concentrations in water downstream the mining sites were approximately 3 times higher than the background value (upstream). The concentrations of Unat, (226)Ra, (210)Pb, and (232)Th in the sediment of downstream river were higher than those upstream by 3.4, 2.6, 2, and 1.7 times, respectively. The distribution coefficient of uranium reflects its high mobility in most of the sites. In order to evaluate the impact on people as well as site prioritization for more detailed assessment and water management, screening dose assessments were done.

  9. Fatty Alcohol Variations in Surface Sediments of Sungai Sepang Besar, Sepang, Selangor

    International Nuclear Information System (INIS)

    Masni Mohd Ali; Norfariza Humrawali; Ying, P.Q.; Mohd Talib Latif; Mohamad Pauzi Zakaria

    2011-01-01

    Composition of fatty alcohols from 19 surface sediment samples collected along Sungai Sepang Besar, Sepang, Selangor were determined. The sediments were extracted and analysed using the Gas Chromatography-Mass Spectrometry (GC-MS) technique. A total of 19 fatty alcohols from C 12 to C 30 including 4 branched compounds were identified with concentrations in the range 0.02 μg/ g - 9.01 μg/ g dry weight. C 26 fatty alcohols dominated most sampling stations with concentrations ranging from 0.29 to 5.43 μg/ g dry weight and constituted 15.5 % of total fatty alcohols. According to individual compounds of fatty alcohols and the [Σ(C 12 - C 20 )/ Σ(C 22 - C 30 )] ratio, Sungai Sepang Besar has a high composition of short-chain fatty alcohols (C 12 - C 20 ) which mainly originate from marine organisms. However, the Alcohol Sources Index (ASI) showed that terrestrial derived fatty alcohols dominated the area due to high concentration of C 26 compounds in most sampling stations. The value of (odd chain length)/ (even chain length) ratios were high for almost all the sampling stations due to high bacterial activities. It can be concluded that the surface sediments of Sungai Sepang Besar contained organic materials from marine, terrestrial and bacterial sources. (author)

  10. Heavy metal contamination in surface sediments of Yangtze River intertidal zone: An assessment from different indexes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Weiguo [State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062 (China); Feng Huan, E-mail: fengh@mail.montclair.ed [Department of Earth and Environmental Studies, Montclair State University, 1 Normal Avenue, Montclair, NJ 07043 (United States); Chang Jinna; Qu Jianguo; Xie Hongxia; Yu Lizhong [State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062 (China)

    2009-05-15

    Surface sediments (0-5 cm) from 59 stations within the Yangtze River intertidal zone (YRIZ) were sampled for metal contamination analysis in April and August 2005. The concentrations ranged (in mg kg{sup -1} dry weight): Al, 40,803-97,213; Fe, 20,538-49,627; Cd, 0.12-0.75; Cr, 36.9-173; Cu, 6.87-49.7; Mn, 413-1,112; Ni, 17.6-48.0; Pb, 18.3-44.1; and Zn, 47.6-154; respectively. Among the 59 sampling stations, enrichment factors (EF) indicate enrichment of Cd (52 stations), Cr (54 stations), Cu (5 stations), Ni (26 stations), Pb (5 stations) and Zn (5 stations). Geoaccumulation indexes (I{sub geo}) also suggest individual metal contamination in localized areas. This study indicates that Cd, Cr and Ni enrichment in the YRIZ sediment is widespread whereas Cu, Mn, Pb and Zn enrichment is localized or nonexistent. Factor and cluster analyses indicate that Cd is associated with total organic carbon whereas Cu, Cr, Ni, Pb and Zn have a close association with Mn. - Surface sediment metal enrichment is evidenced for Cd, Cr and Ni in the Yangtze River intertidal zone.

  11. Evidence of stochastic region near a rational surface in core plasmas of LHD

    International Nuclear Information System (INIS)

    Ida, K.; Tamura, N.; Tuchiya, H.

    2010-11-01

    Clear evidence of stochastization of the magnetic surfaces near a rational surface is observed in the core plasma with weak magnetic shear in the Large Helical Device (LHD) by applying heat pulses driven by modulated electron cyclotron heating (MECH). The stochastization of the magnetic surfaces is confirmed by the observation of flattening of electron temperature (T e ) profiles and very fast propagation of the heat pulse, which is in contrast to the slow heat pulse propagation observed in the T e flat region of the nested magnetic island. (author)

  12. Uptake of radioactivity by marine surface sediments collected in Ghazaouet, west coast of Algeria

    International Nuclear Information System (INIS)

    Noureddine, A.; Baggoura, B.; Hocini, N.; Boulahdid, M.

    1998-01-01

    Samples of surface marine sediments of different grain sizes collected in Ghazaouet, a small bay on the western coast of Algeria, have been examined to measure concentrations of natural and artificial gamma-emitting radionuclides. The aim of this study is to determine the level of radioactivity and its repartition in the sedimentary area. The samples analyzed by direct counting gamma spectrometry, showed relatively high activities for natural radioactivity and revealed measurable quantities of 137 Cs, ranging from 0.66-8.47 Bq kg -1 dry weight. In addition, some of the samples of different nature were sieved in different grain-sizes, to study the uptake of radioactivity. It is found that the sediments of less than 100 μm grain-size have the highest level of uptake of radioactivity

  13. Uptake of radioactivity by marine surface sediments collected in Ghazaouet, west coast of Algeria

    Energy Technology Data Exchange (ETDEWEB)

    Noureddine, A.; Baggoura, B. [Laboratoire d' Environnement, Centre de Radioprotection et de Surete (C.R.S.), Algiers (Algeria); Hocini, N. [Laboratoire de Sedimentologie, Centre de Developpement des Techniques Nucleaires (C.D.T.N.), Algiers (Algeria); Boulahdid, M. [Departement de la Pollution Chimique, Institut des Sciences de la Mer et de l' Amenagement du Littoral, Tipaza (Algeria)

    1998-12-01

    Samples of surface marine sediments of different grain sizes collected in Ghazaouet, a small bay on the western coast of Algeria, have been examined to measure concentrations of natural and artificial gamma-emitting radionuclides. The aim of this study is to determine the level of radioactivity and its repartition in the sedimentary area. The samples analyzed by direct counting gamma spectrometry, showed relatively high activities for natural radioactivity and revealed measurable quantities of {sup 137}Cs, ranging from 0.66-8.47 Bq kg{sup -1} dry weight. In addition, some of the samples of different nature were sieved in different grain-sizes, to study the uptake of radioactivity. It is found that the sediments of less than 100 {mu}m grain-size have the highest level of uptake of radioactivity.

  14. Heavy metals and polycyclic aromatic hydrocarbons in surface sediments of Karoon River, Khuzestan Province, Iran.

    Science.gov (United States)

    Keshavarzi, Behnam; Mokhtarzadeh, Zeinab; Moore, Farid; Rastegari Mehr, Meisam; Lahijanzadeh, Ahmadreza; Rostami, Soqra; Kaabi, Helena

    2015-12-01

    Karoon is the longest river in Iran and provides water for industries located along its banks, such as metal, petrochemical, and oil industries. It is also the source of drinking water for cities such as Ahwas, Abadan, and Khorramshahr. In this study, 34 and 18 surface sediment samples were collected and analyzed for heavy metals (Al, As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and polycyclic aromatic hydrocarbons (PAHs). The measured concentrations of heavy metals were compared with US EPA sediment quality guidelines, and the results showed that Cu concentration was above the threshold effect level (TEL) in 65.67% of the samples and Hg concentration was above the effect range median (ERM) in some samples. The results revealed that Hg was severely enriched (5 soap factory and Abadan petrochemical complex. Principal component analysis and cluster analysis also revealed the relationships between the studied parameters and identified their probable sources.

  15. Pollen grains in quaternary sediments from the Campos Basin, state of Rio de Janeiro, Brazil: Core BU-91-GL-05

    Directory of Open Access Journals (Sweden)

    Aline Gonçalves de Freitas

    2013-12-01

    Full Text Available Here, we describe pollen grains extracted from a Pleistocene-Holocene sediment core (BU-91-GL-05; 22°48'45"S; 41°54'13"W taken from the Albacora Slope (22°48'45"S; 41°54'13"W, located in the Campos Basin of the northern region of the state of Rio de Janeiro, Brazil. The analysis resulted in the identification and morphological description of 46 types of pollen: one of a gymnosperm genus (Podocarpus; and 45 of angiosperm taxa across 27 families-one family of monocotyledons (Poaceae and 26 families (30 types of dicotyledons. The most common angiosperm families were Amaranthaceae (Chenopodium, Amaranthus and Gomphrena; Fabaceae (Fabaceae type, Bauhinia, Inga and Canavalia; Malpighiaceae (Tetrapteris, Heteropteris and Peixotoa; Malvaceae (Sida, Abutilon, Hibiscus and Pseudobombax; Rubiaceae (Faramea, Borreria and Psychotria; Asteraceae (Eupatorium and tribe Vernonieae; Bignoniaceae (Bignoniaceae type, Adenocalymma and Tabebuia; and Onagraceae (Fuchsia and Ludwigia. The palynoflora in this study are associated with dense montane and submontane Atlantic Forest, semideciduous forest and restinga (coastal woodland, all of which are present in the state of Rio de Janeiro. Palynological analysis can provide important data about paleovegetation and paleoclimatic changes in the studied area during the Quaternary, specifically in the last 145,000 years.

  16. Concentration of polybrominated diphenyl ethers (PBDEs) in sediment cores of Sundarban mangrove wetland, northeastern part of Bay of Bengal (India)

    International Nuclear Information System (INIS)

    Binelli, Andrea; Sarkar, Santosh Kumar; Chatterjee, Mousumi; Riva, Consuelo; Parolini, Marco; Bhattacharya, Bhaskar deb; Bhattacharya, Asok Kumar; Satpathy, Kamala Kanta

    2007-01-01

    The paper presents the first comprehensive survey of congener profiles (12 congeners) of polybrominated diphenyl ethers (PBDEs) in core sediment samples ( 12 PBDE values ranging from 0.08 to 29.03 ng g -1 , reflecting moderate to low contamination closely in conformity to other Asian aquatic environments. The general order of decreasing congener contribution to the total load was: BDE 47 > 99 > 100 > 154, similar to the distribution pattern worldwide. Although tetrabromodiphenyl ether BDE 47 was found in all samples followed by hexabromodiphenyl ether BDE-154, they were not necessarily the dominant congeners. No uniform temporal trend on PBDE levels was recorded probably due to particular hydrological characteristics of the wetland and/on non-homologous inputs from point sources (untreated municipal wastewater and local industries, electronic wastes from the dump sites, etc.) of these compounds. Because of the propensity of PBDEs to accumulate in various compartments of wildlife and human food webs, evaluation of biological tissues should be undertaken as a high priority

  17. Spatial glyphosate and AMPA redistribution on the soil surface driven by sediment transport processes – A flume experiment

    NARCIS (Netherlands)

    Bento, Célia P.M.; Commelin, Meindert C.; Baartman, Jantiene E.M.; Yang, Xiaomei; Peters, Piet; Mol, Hans G.J.; Ritsema, Coen J.; Geissen, Violette

    2018-01-01

    This study investigates the influence of small-scale sediment transport on glyphosate and AMPA redistribution on the soil surface and on their off-site transport during water erosion events. Both a smooth surface (T1) and a surface with “seeding lines on the contour” (T2) were tested in a rainfall

  18. E. coli Surface Properties Differ between Stream Water and Sediment Environments

    Directory of Open Access Journals (Sweden)

    Xiao Liang

    2016-11-01

    Full Text Available The importance of E. coli as an indicator organism in fresh water has led to numerous studies focusing on cell properties and transport behavior. However, previous studies have been unable to assess if differences in E. coli cell surface properties and genomic variation are associated with different environmental habitats. In this study, we investigated the variation in characteristics of E. coli obtained from stream water and stream bottom sediments. Cell properties were measured for 77 genomically different E. coli strains (44 strains isolated from sediments and 33 strains isolated from water under common stream conditions in the Upper Midwestern United States: pH 8.0, ionic strength 10mM and 22˚C. Measured cell properties include hydrophobicity, zeta potential, net charge, total acidity and extracellular polymeric substance (EPS composition. Our results indicate that stream sediment E. coli had significantly greater hydrophobicity, greater EPS protein content and EPS sugar content, less negative net charge, and higher point of zero charge than stream water E. coli. A significant positive correlation was observed between hydrophobicity and EPS protein for stream sediment E. coli but not for stream water E. coli. Additionally, E. coli surviving in the same habitat tended to have significantly larger (GTG5 genome similarity. After accounting for the intrinsic impact from the genome, environmental habitat was determined to be a factor influencing some cell surface properties, such as hydrophobicity. The diversity of cell properties and its resulting impact on particle interactions should be considered for environmental fate and transport modeling of aquatic indicator organisms such as E. coli.

  19. 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.

  20. E. coli Surface Properties Differ between Stream Water and Sediment Environments.

    Science.gov (United States)

    Liang, Xiao; Liao, Chunyu; Thompson, Michael L; Soupir, Michelle L; Jarboe, Laura R; Dixon, Philip M

    2016-01-01

    The importance of E. coli as an indicator organism in fresh water has led to numerous studies focusing on cell properties and transport behavior. However, previous studies have been unable to assess if differences in E. coli cell surface properties and genomic variation are associated with different environmental habitats. In this study, we investigated the variation in characteristics of E. coli obtained from stream water and stream bottom sediments. Cell properties were measured for 77 genomically different E. coli strains (44 strains isolated from sediments and 33 strains isolated from water) under common stream conditions in the Upper Midwestern United States: pH 8.0, ionic strength 10 mM and 22°C. Measured cell properties include hydrophobicity, zeta potential, net charge, total acidity, and extracellular polymeric substance (EPS) composition. Our results indicate that stream sediment E. coli had significantly greater hydrophobicity, greater EPS protein content and EPS sugar content, less negative net charge, and higher point of zero charge than stream water E. coli . A significant positive correlation was observed between hydrophobicity and EPS protein for stream sediment E. coli but not for stream water E. coli . Additionally, E. coli surviving in the same habitat tended to have significantly larger (GTG) 5 genome similarity. After accounting for the intrinsic impact from the genome, environmental habitat was determined to be a factor influencing some cell surface properties, such as hydrophobicity. The diversity of cell properties and its resulting impact on particle interactions should be considered for environmental fate and transport modeling of aquatic indicator organisms such as E. coli .

  1. Physical and Mechanical Properties of Surface Sediments and methane hydrate-bearing sediments in the Shenhu area of South China Sea

    Science.gov (United States)

    Jiang, J.; Shen, Z.; Jia, Y.

    2017-12-01

    Methane hydrates are superior energy resources and potential predisposing factors of geohazard. With the success in China's persistent exploitation of methane hydrates in the Shenhu area of South China Sea for 60 days, there is an increasing demand for detailed knowledge of sediment properties and hazard assessment in this area. In this paper, the physical and mechanical properties of both the surface sediments and methane hydrate-bearing sediments (MHBS) in the exploitation area, the Shenhu area of South China Sea, were investigated using laboratory geotechnical experiments, and triaxial tests were carried out on remolded sediment samples using a modified triaxial apparatus. The results show that sediments in this area are mainly silt with high moisture content, high plasticity, low permeability and low shear strength. The moisture content and permeability decrease while the shear strength increases with the increasing depth. The elastic modulus and peak strength of MHBS increase with the increasing effective confining pressure and higher hydrate saturation. The cohesion increases with higher hydrate saturation while the internal friction angle is barely affected by hydrate saturation. The obtained results demonstrate clearly that methane hydrates have significant impacts on the physical and mechanical properties of sediments and there is still a wide gap in knowledge about MHBS.

  2. Contributions to the geomagnetic secular variation from a reanalysis of core surface dynamics

    Science.gov (United States)

    Barrois, O.; Gillet, N.; Aubert, J.

    2017-10-01

    We invert for motions at the surface of Earth's core under spatial and temporal constraints that depart from the mathematical smoothings usually employed to ensure spectral convergence of the flow solutions. Our spatial constraints are derived from geodynamo simulations. The model is advected in time using stochastic differential equations coherent with the occurrence of geomagnetic jerks. Together with a Kalman filter, these spatial and temporal constraints enable the estimation of core flows as a function of length and time-scales. From synthetic experiments, we find it crucial to account for subgrid errors to obtain an unbiased reconstruction. This is achieved through an augmented state approach. We show that a significant contribution from diffusion to the geomagnetic secular variation should be considered even on short periods, because diffusion is dynamically related to the rapidly changing flow below the core surface. Our method, applied to geophysical observations over the period 1950-2015, gives access to reasonable solutions in terms of misfit to the data. We highlight an important signature of diffusion in the Eastern equatorial area, where the eccentric westward gyre reaches low latitudes, in relation with important up/downwellings. Our results also confirm that the dipole decay, observed over the past decades, is primarily driven by advection processes. Our method allows us to provide probability densities for forecasts of the core flow and the secular variation.

  3. Strippable core-shell polymer emulsion for decontamination of radioactive surface contamination

    International Nuclear Information System (INIS)

    Hwang, Ho-Sang; Seo, Bum-Kyoung; Lee, Kune-Woo

    2011-01-01

    In this study, the core-shell composite polymer for decontamination from the surface contamination was synthesized by the method of emulsion polymerization and blends of polymers. The strippable polymer emulsion is composed of the poly(styrene-ethyl acrylate) [poly(St-EA)] composite polymer, poly(vinyl alcohol) (PVA) and polyvinylpyrrolidone (PVP). The morphology of the poly(St-EA) composite emulsion particle was core-shell structure, with polystyrene (PS) as the core and poly(ethyl acrylate) (PEA) as the shell. Core-shell polymers of styrene (St)/ethyl acrylate (EA) pair were prepared by sequential emulsion polymerization in the presence of sodium dodecyl sulfate (SDS) as an emulsifier using ammonium persulfate (APS) as an initiator. Related tests and analysis confirmed the success in synthesis of composite polymer. The products are characterized by FT-IR spectroscopy, TGA that were used, respectively, to show the structure, the thermal stability of the prepared polymer. Two-phase particles with a core-shell structure were obtained in experiments where the estimated glass transition temperature and the morphologies of emulsion particles. Decontamination factors of the strippable polymeric emulsion were evaluated with the polymer blend contents. (author)

  4. Anisotropy of magnetic susceptibility as a tool for recognizing core deformation: reevaluation of the paleomagnetic record of Pleistocene sediments from drill hole OL-92, Owens Lake, California

    Science.gov (United States)

    Rosenbaum, Joseph; Reynolds, Richard T.; Smoot, Joseph; Meyer, Robert

    2000-01-01

    At Owens Lake, California, paleomagnetic data document the Matuyama/Brunhes polarity boundary near the bottom of a 323-m core (OL-92) and display numerous directional fluctuations throughout the Brunhes chron. Many of the intervals of high directional dispersion were previously interpreted to record magnetic excursions. For the upper ~120 m, these interpretations were tested using the anisotropy of magnetic susceptibility (AMS), which typically defines a subhorizontal planar fabric for sediments deposited in quiet water. AMS data from intervals of deformed core, determined from detailed analysis of sedimentary structures, were compared to a reference AMS fabric derived from undisturbed sediment. This comparison shows that changes in the AMS fabric provide a means of screening core samples for deformation and the associated paleomagnetic record for the adverse effects of distortion. For that portion of core OL-92 studied here (about the upper 120 m), the combined analyses of sedimentary structures and AMS data demonstrate that most of the paleomagnetic features, previously interpreted as geomagnetic excursions, are likely the result of core deformation.

  5. Selected anionic and cationic surface active agents: case study on the Kłodnica sediments

    Directory of Open Access Journals (Sweden)

    Olkowska Ewa

    2017-03-01

    Full Text Available Surface active agents (surfactants are a group of chemical compounds, which are used as ingredients of detergents, cleaning products, cosmetics and functional products. After use, wastes containing surfactants or their degradation products are discharged to wastewater treatment plants or directly into surface waters. Due to their specific properties of SAAs, compounds are able to migrate between different environmental compartments such as soil, sediment, water or even living organisms and accumulate there. Surfactants can have a harmful effect on living organisms. They can connect with bioactive molecules and modify their function. Additionally, they have the ability to migrate into cells and cause their damage or death. For these reasons investigation of individual surfactants should be conducted. The presented research has been undertaken to obtain information about SAA contamination of sediment from the River Kłodnica catchment caused by selected anionic (linear alkylbenzene sulfonates (LAS C10-C13 and cationic (alkylbenzyldimethylammonium (BDMA-C12-16, alkyl trimethyl ammonium (DTMA, hexadecyl piridinium chloride (HP chlorides surfactants. This river flows through an area of the Upper Silesia Industrial Region where various companies and other institutions (e.g. coal mining, power plants, metallurgy, hospitals are located. To determine their concentration the following analytical tools have been applied: accelerated solvent extraction– solid phase extraction – high performance liquid chromatography – UV-Vis (anionic SAAs and conductivity (cationic SAAs detectors. In all sediments anionic SAAs have been detected. The concentrations of HTMA and BDMA-C16 in tested samples were higher than other cationic analytes. Generally, levels of surfactants with longer alkyl chains were higher and this observation can confirm their higher susceptibility to sorption on solid surfaces.

  6. Shift in the microbial community composition of surface water and sediment along an urban river.

    Science.gov (United States)

    Wang, Lan; Zhang, Jing; Li, Huilin; Yang, Hong; Peng, Chao; Peng, Zhengsong; Lu, Lu

    2018-01-30

    Urban rivers represent a unique ecosystem in which pollution occurs regularly, leading to significantly altered of chemical and biological characteristics of the surface water and sediments. However, the impact of urbanization on the diversity and structure of the river microbial community has not been well documented. As a major tributary of the Yangtze River, the Jialing River flows through many cities. Here, a comprehensive analysis of the spatial microbial distribution in the surface water and sediments in the Nanchong section of Jialing River and its two urban branches was conducted using 16S rRNA gene-based Illumina MiSeq sequencing. The results revealed distinct differences in surface water bacterial composition along the river with a differential distribution of Proteobacteria, Cyanobacteria, Actinobacteria, Bacteroidetes and Acidobacteria (P urban water. PICRUSt metabolic inference analysis revealed a growing number of genes associated with xenobiotic metabolism and nitrogen metabolism in the urban water, indicating that urban discharges might act as the dominant selective force to alter the microbial communities. Redundancy analysis suggested that the microbial community structure was influenced by several environmental factors. TP (P urban river. These results highlight that river microbial communities exhibit spatial variation in urban areas due to the joint influence of chemical variables associated with sewage discharging and construction of hydropower stations. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Self-consistent Green’s-function technique for bulk and surface impurity calculations: Surface core-level shifts by complete screening

    DEFF Research Database (Denmark)

    Aldén, M.; Abrikosov, I. A.; Johansson, B.

    1994-01-01

    of the frozen-core and atomic-sphere approximation but, in addition, includes the dipole contribution to the intersphere potential. Within the concept of complete screening, we identify the surface core-level binding-energy shift with the surface segregation energy of a core-ionized atom and use the Green......'s-function impurity technique in a comprehensive study of the surface core-level shifts (SCLS) of the 4d and 5d transition metals. In those cases, where observed data refer to single crystals, we obtain good agreement with experiment, whereas the calculations typically underestimate the measured shift obtained from...... a polycrystalline surface. Comparison is made with independent theoretical data for the surface core-level eigenvalue shift, and the much debated role of the so-called initial-and final-state contributions to the SCLS is discussed....

  8. On the flow magnitude and field-flow alignment at Earth's core surface

    DEFF Research Database (Denmark)

    Finlay, Chris; Amit, H.

    We present a method to estimate the typical magnitude of flow close toEarth's core surface based on observational knowledge of the maingeomagnetic field (MF) and its secular variation (SV), together withprior information concerning field-flow alignment gleaned from numericaldynamo models. An expr......We present a method to estimate the typical magnitude of flow close toEarth's core surface based on observational knowledge of the maingeomagnetic field (MF) and its secular variation (SV), together withprior information concerning field-flow alignment gleaned from numericaldynamo models...... geomagnetic field model gufm1for the interval 1840.0 - 1990.0, the method predicts temporalvariations in flow magnitude similar to those found in earlier studies.The calculations rely primarily on knowledge of the MF and SV spectra;by extrapolating these beyond observed scales the influence of smallscales...

  9. PBDD/Fs in surface sediments from the East River, China.

    Science.gov (United States)

    Ren, M; Peng, P A; Chen, D Y; Chen, P; Zhou, L

    2009-09-01

    The contamination status of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) was preliminarily investigated in surface sediments from the East River. The concentrations of eight 2,3,7,8-substituted tetra- to hexa- PBDD/Fs were found to be in the range of 0.32-110 (mean 13) pg g(-1) and the corresponding TEQ concentrations were 0.087-18 (mean 2) pg I-TEQ g(-1). All sediments were characterized by the dominant PBDFs. 2,3,4,7,8-PeBDF was the most important TEQ contributor, accounting for 47%-77% of the total I-TEQ of PBDD/Fs. PCDD/Fs contributed dominantly to the total TEQs of PCDD/Fs, PBDD/Fs and dioxin-like PCBs in most samples except of the sediment from the Shima River. The higher PBDD/F concentrations in the Shima River may be attributed to the use of BFRs in the electrical and electronics industries, which posed a potential risk of dioxins on ecological system.

  10. Sensitivity-Based Modeling of Evaluating Surface Runoff and Sediment Load using Digital and Analog Mechanisms

    Directory of Open Access Journals (Sweden)

    Olotu Yahaya

    2014-07-01

    Full Text Available Analyses of runoff- sediment measurement and evaluation using automated and convectional runoff-meters was carried out at Meteorological and Hydrological Station of Auchi Polytechnic, Auchi using two runoff plots (ABCDa and EFGHm of area 2m 2 each, depth 0.26 m and driven into the soil to the depth of 0.13m. Runoff depths and intensities were measured from each of the positioned runoff plot. Automated runoff-meter has a measuring accuracy of ±0.001l/±0.025 mm and rainfall depth-intensity was measured using tipping-bucket rainguage during the period of 14-month of experimentation. Minimum and maximum rainfall depths of 1.2 and 190.3 mm correspond to measured runoff depths (MRo of 0.0 mm for both measurement approaches and 60.4 mm and 48.9 mm respectively. Automated runoffmeter provides precise, accurate and instantaneous result over the convectional measurement of surface runoff. Runoff measuring accuracy for automated runoff-meter from the plot (ABCDa produces R 2 = 0.99; while R 2 = 0.96 for manual evaluation in plot (EFGHm. WEPP and SWAT models were used to simulate the obtained hydrological variables from the applied measurement mechanisms. The outputs of sensitivity simulation analysis indicate that data from automated measuring systems gives a better modelling index and such could be used for running robust runoff-sediment predictive modelling technique under different reservoir sedimentation and water management scenarios.

  11. Horizontal and vertical distribution of lignin in surface sediments of the Gdansk Basin

    Directory of Open Access Journals (Sweden)

    Andrzej Staniszewski

    2001-12-01

    Full Text Available The aim of this study was to identify and quantify lignin transported from the River Vistula to the accumulation area in the Gdansk Basin. Sediment samples collected along the Vistula mouth - Gdansk Deep transect were analysed for lignin. Lignin was characterised by oxidative degradation, cupric oxide being chosen as the most suitable oxidising agent. The polar functional groups of the oxidation products were silylated and the derivatives analysed by capillary gas chromatography on fused capillary silica columns with flame ionisation detection. Lignin-derived oxidation products were quantified in the range from 3 to 20 µg g-1 dry wt. for phenolic acids and from 6 to 12 µg g-1 dry wt. for phenolic aldehydes. Differences in oxidation products contents are assigned to different lignin sources in the marine environment. The horizontal and vertical gradients of these compounds in the sediments of the Gdansk Basin are documented. The results are discussed in terms of the origin and fate of organic matter in the Gdansk Basin. The measured differences in quality and quantity of the identified oxidation products provide insight into diagenetic processes in the surface marine sediments.

  12. Assessment of metals contamination in Klang River surface sediments by using different indexes

    Directory of Open Access Journals (Sweden)

    Abolfazl Naji

    2011-01-01

    Full Text Available Surface sediments (0-5 cm from 21 stations throughout Klang River were sampled for metal concentration as well sediment's pH, total organic carbon (TOC and particles sizes to obtain an overall classification of metal contaminations in the area. The concentration of metals (µg∕g, Fe%, dw were as follows: 0.57- 2.19 Cd; 31.89-272.33 Zn; 5.96-24.47 Ni; 10.57- 52.87 Cu; 24.23-64.11 Pb and 1.56-3.03 Fe. The degree of sediment contaminations were computed using an enrichment factor (EF and geoaccumulation index (Igeo. The results suggested that enrichment factor and geoaccumulation values of Cd were greatest among the studied metals. Pearson's correlation indicated that effectiveness of TOC in controlling the distribution and enrichment of metals was a more important factor than that of the grain size (< 63µm. The study revealed that on the basis of computed indexes, Klang River is classified as moderately polluted river.

  13. Sedimentary record of polycyclic aromatic hydrocarbons in a sediment core from a maar lake, Northeast China: evidence in historical atmospheric deposition.

    Science.gov (United States)

    Guan, Yu-Feng; Sun, Jian-Lin; Ni, Hong-Gang; Guo, Jian-Yang

    2012-09-01

    A maar lake is an excellent ecosystem to study the atmospheric deposition of pollutants, as its contaminants are primarily by atmospheric deposition. In this study, a sediment core from Sihailongwan Maar Lake, Northeast China, was collected and the historical atmospherically deposited polycyclic aromatic hydrocarbons (PAHs) were analyzed. The concentrations of TPAHs (the sum of the US EPA proposed 16 priority PAHs, excluding naphthalene and pyrene) ranged from 473.9 to 2289 ng g(-1) with a slow increasing stage in the deeper sediments and a sharp increasing stage in the upper sediments. The input rate of TPAHs, especially that of PAH(9) (the sum of fluoranthene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene, dibenzo(ah)anthrathene, and benzo(ghi)perylene), correlated well to the Chinese historical socioeconomic data. This indicates that sediment PAHs were mainly derived from human activities and PAH(9) can be regarded as a better indicator of the local socioeconomic development. Source identification suggested that PAHs were originated primarily from mixed sources (e.g., coal and biomass burning and petroleum combustion), except for perylene which was mostly of diagenetic origin. In addition, the down-core PAHs profile clearly illustrated that PAHs sources in Northeast China experienced a transformation from low- and moderate temperature to high-temperature combustion processes, especially after the late 1980s. Additionally, an ecological risk assessment using two redefined biological thresholds (TEQ(ERL) and TEQ(ERM)) indicated that most of the PAHs measured in the present sediment core would not cause an immediate toxic effect; only FLU and PHEN are a potential source of concern for biological impairment.

  14. Influence of surface treatments on the surface properties of different zirconia cores and adhesion of zirconia-veneering ceramic systems.

    Science.gov (United States)

    Elsaka, Shaymaa E

    2013-10-01

    The aim of this study was to assess the influence of surface treatments on the surface characteristics of different zirconia cores and the adhesion of the zirconia-veneering ceramic systems by means of strain energy release rate (G-value, J/m(2)). Three types of zirconia cores (NANOZR (NZ), Vita In-Ceram YZ (VZ), and IPS e.max ZirCAD (IZ)) were used. The specimens were divided into four groups in each test according to the surface treatment used; Gr 1 (control; no treatment), Gr 2 (sandblasted), Gr 3 (CH2Cl2 for 60min), and Gr 4 (experimental hot etching solution for 60min). AFM, SEM, EDS, and XRD were carried out. Two types of veneering ceramics (Vita VM9 (V9) and IPS e.max Ceram (IC)) were used for testing the adhesion. The G-value (J/m(2)) was measured with a four-point bending configuration. Following fracture testing specimens were examined with SEM. Data were analyzed using ANOVA and Tukey's test. NZ treated with the experimental hot etching solution showed the highest Ra values (206.06±9.98nm) compared with the other groups (Pveneering ceramic systems. The experimental hot etching solution could be considered as alternative treatment modality to sandblasting for zirconia cores to avoid phase transition at the surface from tetragonal to monoclinic that may be detrimental for the longevity of the zirconia-veneering ceramic restoration. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  15. Gases Emission From Surface Layers of Sand Moulds and Cores Stored Under the Humid Air Conditions

    Directory of Open Access Journals (Sweden)

    Kaźnica N.

    2017-12-01

    Full Text Available A large number of defects of castings made in sand moulds is caused by gases. There are several sources of gases: gases emitted from moulds, cores or protective coatings during pouring and casting solidification; water in moulding sands; moisture adsorbed from surroundings due to atmospheric conditions changes. In investigations of gas volumetric emissions of moulding sands amounts of gases emitted from moulding sand were determined - up to now - in dependence of the applied binders, sand grains, protective coatings or alloys used for moulds pouring. The results of investigating gas volumetric emissions of thin-walled sand cores poured with liquid metal are presented in the hereby paper. They correspond to the surface layer in the mould work part, which is decisive for the surface quality of the obtained castings. In addition, cores were stored under conditions of a high air humidity, where due to large differences in humidity, the moisture - from surroundings - was adsorbed into the surface layer of the sand mould. Due to that, it was possible to asses the influence of the adsorbed moisture on the gas volumetric emission from moulds and cores surface layers by means of the new method of investigating the gas emission kinetics from thin moulding sand layers heated by liquid metal. The results of investigations of kinetics of the gas emission from moulding sands with furan and alkyd resins as well as with hydrated sodium silicate (water glass are presented. Kinetics of gases emissions from these kinds of moulding sands poured with Al-Si alloy were compared.

  16. Denali Ice Core Record of North Pacific Sea Surface Temperatures and Marine Primary Productivity

    Science.gov (United States)

    Polashenski, D.; Osterberg, E. C.; Kreutz, K. J.; Winski, D.; Wake, C. P.; Ferris, D. G.; Introne, D.; Campbell, S. W.

    2016-12-01

    Chemical analyses of precipitation preserved in glacial ice cores provide a unique opportunity to study changes in atmospheric circulation patterns and ocean surface conditions through time. In this study, we aim to investigate changes in both the physical and biological parameters of the north-central Pacific Ocean and Bering Sea over the twentieth century using the deuterium excess (d-excess) and methanesulfonic acid (MSA) records from the Mt. Hunter ice cores drilled in Denali National Park, Alaska. These parallel, 208 m-long ice cores were drilled to bedrock during the 2013 field season on the Mt. Hunter plateau (63° N, 151° W, 3,900 m above sea level) by a collaborative research team consisting of members from Dartmouth College and the Universities of Maine and New Hampshire. The cores were sampled on a continuous melter system at Dartmouth College and analyzed for the concentrations major ions (Dionex IC) and trace metals (Element2 ICPMS), and for stable water isotope ratios (Picarro). The depth-age scale has been accurately dated to 400 AD using annual layer counting of several chemical species and further validated using known historical volcanic eruptions and the Cesium-137 spike associated with nuclear weapons testing in 1963. We use HYSPLIT back trajectory modeling to identify likely source areas of moisture and aerosol MSA being transported to the core site. Satellite imagery allows for a direct comparison between chlorophyll a concentrations in these source areas and MSA concentrations in the core record. Preliminary analysis of chlorophyll a and MSA concentrations, both derived almost exclusively from marine biota, suggest that the Mt. Hunter ice cores reflect changes in North Pacific and Bering Sea marine primary productivity. Analysis of the water isotope and MSA data in conjunction with climate reanalysis products shows significant correlations (psea surface temperatures in the Bering Sea and North Central Pacific. These findings, coupled with

  17. Contamination by persistent toxic substances in surface sediment of urban rivers in Chaohu City, China.

    Science.gov (United States)

    Li, Feipeng; Zhang, Haiping; Meng, Xiangzhou; Chen, Ling; Yin, Daqiang

    2012-01-01

    The concentration and spatial distribution of persistent toxic substances (PTS) in the river sediment in Chaohu City, China were investigated. A total of nine surface sediments were collected and the selected PTS pollutants including six heavy metals and nineteen polybrominated diphenyl ethers (PBDEs) were analyzed. The mean heavy metal concentrations (in mg/kg, dry weight) ranged within 0.18-1.53 (Hg), 50.08-200.18 (Cu), 118.70-313.65 (Zn), 50.77-310.85 (Cr), 37.12-92.72 (Pb) and 13.29-197.24 (As), and Cu, Zn and As have been regarded as the main metal pollutants. The levels of PBDEs (1.2-12.1 ng/g) and BDE-209 (2.4-30.5 ng/g) were at the middle level of the global range. BDE-209 was the predominant congener (67.0%-85.7%), which agrees with the fact that technical deca-BDE mixtures are the dominant PBDE formulation in China. The relative high level of PTS pollutants in the western part of the city is probably owing to the intensive agricultural activities and lack of sewerage system there. The ecological risk assessment with the sediment quality guidelines (SOGs) indicates that the urban river sediments in the city have been heavily contaminated by heavy metals with probable ecotoxicological impacts on freshwater organisms and the main toxic pollutants are Hg and As. The results of current study imply that the city, and perhaps many other small cities in China as well, requires immediate pollution control measures with emphasis on not only conventional organic pollutants but also on PTS such as heavy metals and PBDEs.

  18. Immobilization of α-Chymotrypsin on the Surface of Magnetic/Gold Core/Shell Nanoparticles

    International Nuclear Information System (INIS)

    Ahmadi, M.K.; Vossoughi, M.

    2013-01-01

    Over the last decade, nanoparticles used as protein carriers have opened new avenues for a variety of biomedical applications. The main concern for these applications is changes in biological activity of immobilized proteins due to conformational changes on the surface of the carrier. To evaluate this concern, the preparation and bio catalyst activity of α-chymotrypsin-Fe 3 O 4 Au core/shell nanoparticles were investigated. First, Fe 3 O 4 Au core/shell nanoparticles were synthesized by coprecipitation method and citrate reduction of HAuCl 4 . TEM imaging revealed a core size of 13 ± 3 nm and a shell thickness of 4 ± 1 nm for synthesized nanoparticles. X-ray diffraction (XRD) was used to study the crystalline structure of the nanoparticles. Next, the enzyme was immobilized on the surface of synthesized nanoparticles by covalent bonding of Au shell with thiol and amine groups present in the protein structure (e.g., cysteine and histidine residues). FTIR and fluorescence spectroscopy were utilized to study secondary and tertiary structures of the immobilized enzyme. Results show that the secondary and tertiary structures of the enzyme remain virtually unchanged after immobilization on the nanoparticles surface. However, the bio catalyst activity of the enzyme was reduced by thirty percent, indicating possible conformational changes or active site occlusion

  19. Diversity of active microbial communities subjected to long-term exposure to chemical contaminants along a 40-year-old sediment core.

    Science.gov (United States)

    Kaci, Assia; Petit, Fabienne; Fournier, Matthieu; Cécillon, Sébastien; Boust, Dominique; Lesueur, Patrick; Berthe, Thierry

    2016-03-01

    In estuarine ecosystems, metallic and organic contaminants are mainly associated with fine grain sediments which settle on mudflats. Over time, the layers of sediment accumulate and are then transformed by diagenetic processes mainly controlled by microbial activity, recording the history of the estuary's chemical contamination. In an environment of this specific type, we investigated the evolution of the chemical contamination and the structure of both total and active microbial communities, based on PhyloChip analysis of a 4.6-m core corresponding to a 40-year sedimentary record. While the archaeal abundance remained constant along the core, a decrease by one order of magnitude in the bacterial abundance was observed with depth. Both total and active microbial communities were dominated by Proteobacteria, Actinobacteria, and Firmicutes in all sediment samples. Among Proteobacteria, alpha-Proteobacteria dominated both total (from 37 to 60 %) and metabolically active (from 19.7 to 34.6 %) communities, including the Rhizobiales, Rhodobacter, Caulobacterales, and Sphingomonadales orders. Co-inertia analysis revealed a relationship between polycyclic aromatic hydrocarbons, zinc and some polychlorobiphenyls concentrations, and the structure of total and active microbial communities in the oldest and most contaminated sediments (from 1970 to 1975), suggesting that long-term exposure to chemicals shaped the structure of the microbial community.

  20. Atom diffraction reveals the impact of atomic core electrons on atom-surface potentials.

    Science.gov (United States)

    Lonij, Vincent P A; Klauss, Catherine E; Holmgren, William F; Cronin, Alexander D

    2010-12-03

    We measured ratios of van der Waals potential coefficients (C3) for different atoms (Li, Na, K, and Rb) interacting with the same surface by studying atom diffraction from a nanograting. These measurements are a sensitive test of atomic structure calculations because C3 ratios are strongly influenced by core electrons and only weakly influenced by the permittivity and geometry of the surface. Our measurement uncertainty of 2% in the ratio C(3)(K)/C(3)(Na) is close to the uncertainty of the best theoretical predictions, and some of these predictions are inconsistent with our measurement.

  1. Stable isotope biogeochemistry of the sulfur cycle in modern marine sediments: I. Seasonal dynamics in a temperate intertidal sandy surface sediment.

    Science.gov (United States)

    Böttcher, Michael; Hespenheide, Britta; Brumsack, Hans-Jürgen; Bosselmann, Katja

    2004-12-01

    A biogeochemical and stable isotope geochemical study was carried out in surface sediments of an organic-matter poor temperate intertidal sandy surface sediment (German Wadden Sea of the North Sea) to investigate the activity of sulfate-reducing bacteria and the dynamics of the vertical partitioning of sedimentary sulfur, iron, and manganese species in relation to the availability of total organic carbon (TOC) and mud contents. The contents and stable isotopic compositions ((34)S/(32)S) of total reduced inorganic sulfur species (TRIS) and dissolved sulfate were measured. Maximum oxygen penetration depths were estimated from the onset of a blackening of the sediments due to FeS accumulation and ranged from 5 to 10 mm below surface (mmbsf). A zone of relatively moderate relative organic-matter enrichment was found between 5 and 20 mmbsf leading to enhanced activities of sulfate-reducing bacteria with sulfate-reduction rates (SRR) up to 350 nmol cm(-3) d(-1). Below this zone, microbial SRR dropped significantly. Depth integrated SRR seem to depend not only on temperature but also on the availability of reactive organic matter. The sulfur-isotopic composition of TRIS was depleted in (34)S by 33-40 per thousand with respect to coexisting dissolved sulfate (constant at about +21 per thousand vs. Vienna-Canyon Diablo Troilite (V-CDT)). Since sulfate reduction is not limited by dissolved sulfate (open system), depth variations of the isotopic composition of TRIS reflect changes in overall isotope effect due to superimposed microbial and abiotic reactions. Most of the solid-phase iron and manganese was bonded to (non-reactive) heavy minerals. However, a layer of reactive Fe(III) and Mn(IV) oxi(hydroxi)des was found in the uppermost sediment section due to re-oxidation of dissolved Fe(II) and Mn(II) species at the sediment-water interface. Metal cycling below the surface is at least partially coupled to intense sulfur cycling.

  2. Geochemical investigation of a sediment core from the Trajan basin at Portus, the harbor of ancient Rome

    Science.gov (United States)

    Delile, H.; Mazzini, I.; Blichert-Toft, J.; Goiran, J. P.; Arnaud-Godet, F.; Salomon, F.; Albarède, F.

    2014-03-01

    From the 1st century AD and for the duration of the Roman Empire, the Portus complex was the main harbor of Rome. Its location on the Tiber delta next to the Tyrrhenian Sea produced rapid environmental changes that, together with historical vicissitudes, largely determined the fate of the harbor. We have assembled data on the mineralogy, sedimentology, geochemistry, and ostracod populations of a sediment core drilled in the access channel of the hexagonal basin of Trajan, with the expectation that such a combined data set will shed new light on how the connections of the inland Trajan basin with the Tiber river, the earlier Claudius harbor on the nearby shoreline, and the sea evolved through the centuries. The data define four distinct periods which geochemistry characterizes by different conditions of salinity and oxygenation. These in turn can be related to historical periods and events by means of 14C data. The early Imperial Period was dominated by input of well-oxygenated freshwater from the Tiber. During the Late Empire, harbor water became relatively more influenced by seawater and increasingly oxygen deficient, which attests to a decommissioning of the Canale Trasverso connecting the harbor to the Tiber. The strong anthropogenic signal, which is visible very clearly in geochemical parameters, attests to the human occupation of the harbor area up to the Early Middle Ages, when human activity was brought to an abrupt end. The simultaneous use in this study of multiple complementary tracers has allowed for the sedimentary sources of the different classes of particles in the harbor basin to be identified and assigned to either the freshwater supply from the Canale Trasverso or the seawater of the Claudius harbor.

  3. 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.

  4. Determination of natural radionuclides from 238U and 232Th series, trace and major elements in sediment cores from baixada Santista and evaluation of impacted areas

    International Nuclear Information System (INIS)

    Damatto, Sandra Regina

    2010-01-01

    Baixada Santista is the region of higher population of the coast of Sao Paulo State, where it is located the largest port in Latin America, in the city of Santos, and the most important industrial complex of Latin America, in the city of Cubatao. This region has received in recent years a considerable load of industrial and domestic effluents in its water bodies, as a direct result of the industrial and port activities and the large population growth in recent decades, and is considered nowadays highly impacted. In the present study sediment cores were collected in the estuary of Santos-Cubatao, in the estuary of Sao Vicente, in the channel of Bertioga and Santos Bay, in order to determine the concentration of trace and major elements and natural radionuclides from the 238 U and 232 Th series. The techniques used were neutron activation analysis, X-ray fluorescence and gamma spectrometry, respectively. The obtained values for the elements Cr, Sb, Ta and Zn in some cores, are higher than data from literature, and can indicate a possible anthropic contribution. Comparing the obtained values of Cr and Zn elements determined in the sediment cores with the values of TEL and PEL index for sediment quality, it was verified that the studied region presents Cr levels higher than TEL in Santos-Cubatao estuary and Bertioga channel and Zn element presented values higher than TEL for some core slices of Santos-Cubatao estuary, for one core of Sao Vicente estuary, one core in Bertioga channel and Santos Bay. For the other elements, the values obtained in this study can be considered as reference values for the region. Although the element As presented higher values than the TEL in all the studied environments, the concentrations obtained are of the same order of magnitude as literature data and, therefore, can be considered also as reference values for the region. No enrichment was found for the major elements in all the ecosystems studied, with the exception for the element P

  5. Evolution Of Late Holocene Sea-Surface Parameters In The Beaufort Sea Area (Mackenzie Slope, Canadian Arctic): Insights From CASES 2004-804-803 Cores

    Science.gov (United States)

    Rochon, A.; Bringué, M.

    2009-05-01

    This study aims at reconstructing late Holocene sea-surface parameters in the Beaufort Sea area (Western Canadian Arctic) on the basis of sedimentary cores collected over the Mackenzie Slope. Piston, trigger and box cores were sampled at station 803 in 2004 aboard the CCGS Amundsen (CASES) at 218 m water depth. Sedimentation at this particular location is influenced by both the Beaufort gyre and the Mackenzie River, whose sedimentary discharge is by far the largest among all other Arctic rivers. The chronology of the piston core is constrained by 4 AMS-14C dates, as the sedimentation rate in the box core is assessed from 210Pb data. We obtain a continuous composite sequence covering the last 4600 years, with a sedimentation rate of ˜140 cm/kyr. Palynological data reveal that dinocyst assemblages are dominated by Operculodinium centrocarpum (mean of 43.3%), with the accompanying taxa Brigantedinium spp. (19.6%), Islandinium minutum (15.6%) and cysts of Pentapharsodinium dalei (13.7%). Four zones have been established on the basis of dinocyst relative abundances, with the following key taxa. Zone I (4600-4000 cal BP): high relative abundances of cysts of P. dalei (mean of 14.9%) and I. minutum var. cezare (up to 8.9%); zone II (4000-2600 cal BP): high abundances of Spiniferites frigidus/elongatus (up to 7.3%); zone III (2600-1600 cal BP): well- represented heterotrophic taxa Brigantedinium spp. (30.8%) and cysts of Polykrikos sp. arctic/quadratus (up to 4.2%); zone IV (1600 cal BP - present): high relative abundances of I. minutum (mean of 19.8%) and cysts of P. dalei (17.3%). Quantitative reconstructions of sea-surface parameters indicate relatively stable conditions from 4600 to 1600 cal BP. Conversely, a trend of increasing summer (August) sea-surface temperature (from ˜5° C to ˜6° C; actual value = 6° C), increasing salinity (from ˜20 to ˜26 psu; modern value = 19 psu) and decreasing sea-ice cover (from ˜9 to 8 month/yr; actual value = 10) is observed

  6. Mercury profiles in sediment from the marginal high of Arabian Sea: an indicator of increasing anthropogenic Hg input.

    Science.gov (United States)

    Chakraborty, Parthasarathi; Vudamala, Krushna; Chennuri, Kartheek; Armoury, Kazip; Linsy, P; Ramteke, Darwin; Sebastian, Tyson; Jayachandran, Saranya; Naik, Chandan; Naik, Richita; Nath, B Nagender

    2016-05-01

    Total Hg distributions and its speciation were determined in two sediment cores collected from the western continental marginal high of India. Total Hg content in the sediment was found to gradually increase (by approximately two times) towards the surface in both the cores. It was found that Hg was preferentially bound to sulfide under anoxic condition. However, redox-mediated reactions in the upper part of the core influenced the total Hg content in the sediment cores. This study suggests that probable increase in authigenic and allogenic Hg deposition attributed to the increasing Hg concentration in the surface sediment in the study area.

  7. Origin and migration of trace elements in the surface sediments of Majuro Atoll, Marshall Islands.

    Science.gov (United States)

    Ito, Lisa; Omori, Takayuki; Yoneda, Minoru; Yamaguchi, Toru; Kobayashi, Ryuta; Takahashi, Yoshio

    2018-03-13

    The sediments of Majuro Atoll, Marshall Islands, consist of bioclastic materials, including foraminifera and coral debris. The sedimentary depth profiles of elements showed that various elements including zinc (Zn) and copper (Cu) were enriched in the upper layers of the islands of Majuro Atoll. Carbon-14 dating revealed that the sedimentation of the upper layer was completed before 1670 and 542 cal BP in Laura and Calalen, respectively. The enriched elements could be categorized by their origins: (a) terrestrial elements transported as dust (aluminum (Al) and rare earth elements (REEs)); (b) anthropogenic elements (Zn and Cu); and (c) elements supplied by seabirds (phosphorus (P)). From the results of the total amount of Al supplied to sediments for ca. 2000 years, Al in Majuro Atoll was suggested to be airborne origin. The enrichment factors of the elements normalized to Al concentration of continental crust showed that REEs were also transported as dust, while Zn and Cu were mainly of anthropogenic origin. The speciation analysis by X-ray absorption near-edge structure (XANES) showed the presence of Zn-Cu alloys originated from industrial products. It was also revealed that Zn was enriched in the surface due to anthropogenic emission after urbanization on Majuro Atoll and fixed by carbonate and phosphate at the upper layer, which inhibits migration of Zn into the deeper layer and its release to the groundwater and costal water. Hence, the fixation of heavy metals at the surface prevents their exposure to aquatic organisms and residents via fresh groundwater in the island. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Dynamics of organic and inorganic carbon in surface sediments of the Yellow River Estuary

    Science.gov (United States)

    Yu, Z.; Wang, X.; Liu, X.; Zhang, E.; Hang, F.

    2017-12-01

    Estuarine sediment is an important carbon reservoir thus may play an important role in the global carbon cycle. However, little is known on the dynamics of organic carbon (OC) and inorganic carbon (IC) in the surface sediment of the Yellow River Estuary, a large estuary in northern China. In this study, we applied element analyses and isotopic approach to study spatial distribution and sources of OC and IC in the Yellow River Estuary. We found that TIC concentration (6.3-20.1 g kg-1) was much higher than TOC (0.2-4.4 g kg-1) in the surface sediment. There showed a large spatial variability in TOC and TIC and their stable isotopes. Both TOC and TIC were higher to the north (2.6 and 14.5 g kg-1) than to the south (1.6 and 12.2 g kg-1), except in the southern bay where TOC and TIC reached 2.7 and 15.4 g kg-1, respectively. Generally, TOC and TIC in our study area was mainly autochthonous. The lower TOC values in the south section were due to relatively higher kinetic energy level whereas the higher values in the bay was attributable to terrigenous matters accumulation and lower kinetic energy level. However, the southern bay revealed the most negative δ13Corg and δ13Ccarb, suggesting that there might exist some transfer of OC to IC in the section. Our study points out that the dynamics of sedimentary carbon in the Yellow River Estuary is influenced by multiple and complex processes, and highlights the importance of carbonate in carbon sequstration.

  9. Lead isotopes in marine surface sediments reveal historical use of leaded fuel.

    Science.gov (United States)

    Larsen, Martin M; Blusztajn, Jerzy S; Andersen, Ole; Dahllöf, Ingela

    2012-11-01

    Analyses of lead (Pb) isotopes have been performed in terrestrial and fresh water environments to estimate historical uses of leaded fuel, but so far this method has not been employed in studies of world-wide marine surface sediments. We analyzed Pb and its isotopes in 23 surface sediments from four continents collected during the Galathea 3 expedition in 2006-2007. To enhance the anthropogenic signal, a partial digestion using nitric acid was performed. The concentrations of Pb, Th, U and Al were determined with an ICP-Quadrupole MS, and Pb-isotope ratios with an ICP-multi-collector MS. The samples could be divided into three groups: Harbor areas in larger cities with concentrations of 150 to 265 mg kg(-1) dry weight, smaller towns with concentrations between 20 and 40 mg kg(-1) dry weight, and remotely located sites with concentrations below 15 mg kg(-1) dry weight. Pb-isotope ratios were compared to literature values for gasoline and local or geological background values, and the contribution of leaded-gasoline to total concentrations was calculated for contaminated sites using both a one-dimensional and a novel two-dimensional (vector) method. The North American sites had Pb-isotope ratios corresponding to the US leaded gasoline, with 24-88% of the Pb from leaded gasoline. Samples from Oceania showed Pb-isotope ratios corresponding to Australian gasoline, with 60% attributed to leaded gasoline in Sydney and 21% in Christchurch. Outside Cape Town, 15 to 46% of Pb in sediments was from leaded gasoline.

  10. Late Quaternary lake-level changes constrained by radiocarbon and stable isotope studies on sediment cores from Lake Titicaca, South America

    Science.gov (United States)

    Rowe, Harold D.; Guilderson, Thomas P.; Dunbar, Robert B.; Southon, John R.; Seltzer, Geoffrey O.; Mucciarone, David A.; Fritz, Sherilyn C.; Baker, Paul A.

    2003-09-01

    We present and compare AMS- 14C geochronologies for sediment cores recovered from Lake Titicaca, South America. Radiocarbon dates from three core sites constrain the timing of late Quaternary paleoenvironmental changes in the Central Andes and highlight the site-specific factors that limit the radiocarbon geochronometer. With the exception of mid-Holocene sediments, all cores are generally devoid of macrophyte fragments, thus bulk organic fractions are used to build core chronologies. Comparisons of radiocarbon results for chemically defined fractions (bulk decalcified, humate, humin) suggest that ages derived from all fractions are generally coherent in the post-13,500 yr BP time interval. In the pre-13,500 yr BP time interval, ages derived from humate extracts are significantly younger (300-7000 years) than ages from paired humin residues. Gross age incoherencies between paired humate and humin sub-fractions in pre-13,500 yr BP sediments from all core sites probably reflect the net downward migration of humates. Ages derived from bulk decalcified fractions at our shallow water (90 m) and deep water (230 m) core sites consistently fall between ages derived from humate and humin sub-fractions in the pre-13,500 yr BP interval, reflecting that the bulk decalcified fraction is predominantly a mixture of humate and humin sub-fractions. Bulk decalcified ages from the pre-13,500 yr BP interval at our intermediate depth core site (150 m) are consistently older than humate (youngest) and humin sub-fractions. This uniform, reproducible pattern can be explained by the mobilization of a relatively older organic sub-fraction during and after the re-acidification step following the alkaline treatment of the bulk sediment. The inferred existence of this 'alkali-mobile, acid-soluble' sub-fraction implies a different depositional/post-depositional history that is potentially associated with a difference in source material. While internally consistent geochronologies can be

  11. Heavy Metal Contamination in the Surface Sediments of Representative Limnetic Ecosystems in Eastern China

    Science.gov (United States)

    Tang, Wenzhong; Shan, Baoqing; Zhang, Hong; Zhang, Wenqiang; Zhao, Yu; Ding, Yuekui; Rong, Nan; Zhu, Xiaolei

    2014-11-01

    A comprehensive analysis of heavy metal pollution was conducted in the representative limnetic ecosystems of eastern China, which are subject to rapid economic development and population growth. The results demonstrated that the average contents with standard deviations of Cd, Cr, Cu, Ni, Pb and Zn in the surface sediments were 0.925 +/- 0.936, 142 +/- 46.8, 54.7 +/- 29.1, 60.5 +/- 21.6, 61.9 +/- 36.0 and 192 +/- 120 mg/kg dry wt., respectively, and that higher values were mainly observed in the southern portion of the study area, especially in the basins of Southeast Coastal Rivers (SCRB) and the Zhu River (ZRB). The six heavy metals in the surface sediments all had anthropogenic origins. In addition, the limnetic ecosystems, especially in the southern portion of the study area were found to be polluted by heavy metals, especially Cd. Overall, two hotspots of heavy metal pollution in the limnetic ecosystems of eastern China were found, one that consisted of the heavy pollution regions, SCRB and ZRB, and another composed of Cd pollution. These results indicate that heavy metal contamination, especially Cd, should be taken into account during development of management strategies to protect the aquatic environment in the limnetic ecosystems of eastern China, especially in the two aforementioned basins.

  12. Hydrocarbons in surface sediments from the Sfax coastal zone, (Tunisia) Mediterranean Sea.

    Science.gov (United States)

    Zaghden, Hatem; Kallel, Monem; Louati, Afifa; Elleuch, Boubaker; Oudot, Jean; Saliot, Alain

    2005-11-01

    The Semi-enclosed Mediterranean Sea records various signals of high anthropic pressures from surrounding countries and the industrialized European countries. This is particularly true for oil pollution. Although accounting for 1% of the world's ocean surface, it receives about 25% of the petroleum inputs to the ocean. To achieve a global budget we need to collect information from different parts of the Mediterranean. Particularly, we focus in this paper on the Southern Mediterranean, where data are presently very scarce. In this context, the University of Sfax has undertaken an estimation of hydrocarbon pollution along the coasts of Sfax and Gabès Gulf. Non-aromatic hydrocarbons were analysed in 8 surface sediments by FT/IR and GC/MS. Non-aromatic hydrocarbon concentrations vary in the range 310-1406 microg g(-1) sediments dry weight, which is high, compared to other Mediterranean sites. GC/MS data indicate a large group of unresolved compounds suggesting a petroleum contamination, confirmed by the identification of hopanes with predominant C29 and C30alpha,beta compounds and steranes with predominance of C27 over C28) and C29 compounds.

  13. Lipid composition of water and surface sediments in Takapoto atoll lagoon (French Polynesia)

    Science.gov (United States)

    Saliot, A.; Bouloubassi, I.; Lorre-Boireau, A.; Trichet, J.; Poupet, P.; Charpy, L.

    1994-11-01

    Dissolved, particulate and sedimentary lipid compounds were analyzed in samples collected in May 1988 at three sites in the lagoon of the closed atoll of Takapoto (Tuamotu archipelago, French Polynesia). The study provides background information dealing with water quality and the nature and concentration of lipids. Non-aromatic hydrocarbons and fatty acids were isolated from lipids and analyzed by gas chromatography/mass spectrometry. Non-aromatic hydrocarbon concentrations did not exceed 1000 ng l-1 in water, and 2300 ng g-1 in surface sediments and are among the lowest encountered in pristine marine environments. No noticeable petroleum pollution was evidenced in the lagoon. Nevertheless, traces of petroleum-derived compounds were detected at the central site for both surface and deep water. Total fatty acid concentrations varied in the range 6.3 14.4 μg l-1 for the particulate phase and in the range 0.5 3.2 μg l-1 for the dissolved phase. The molecular fingerprints of fatty acids and hydrocarbons evidenced a predominant algal, and to a lesser extent microbial, origin of the organic matter present in water and sediments. Mono- and polyunsaturated fatty acids, which are essential components for animal metabolism, were identified in noticeable amounts in suspended matter (1.8 4.6 μg l-1), and at highly variable levels in the dissolved phase (0.08 1.21 μg l-1).

  14. 226Ra, 228Ra and 228Ra/226Ra in surface marine sediment of Malaysia

    International Nuclear Information System (INIS)

    Mei-Wo Yii; Zal Uyun Wan-Mahmood

    2013-01-01

    Surface sediment samples were collected at the West (east coast and west coast of Peninsular Malaysia) and East (Sabah and Sarawak) Malaysia in several expeditions within August 2003 until June 2008 for determining the level of natural radium isotopes. Activity concentrations of 226 Ra and 228 Ra in surface marine sediment at 176 sampling stations were measured. The activity concentrations of both radionuclides in Malaysia (East and West Malaysia) display varied with the range from 9 to 158 Bq/kg dry wt. and 13 to 104 Bq/kg dry wt., respectively. Meanwhile, the ratio distributions of 228 Ra/ 226 Ra were ranged from 0.62 to 3.75. This indicated that the ratios were slightly high at west coast of Peninsular Malaysia compared to other regions (east coast of Peninsular Malaysia, Sabah and Sarawak). The variation of activity concentrations of 226 Ra and 228 Ra and its ratios were also supported by the statistical analyses of one-way ANOVA and t test at 95 % confidence level, whereby there were proved that the measured values were different between the regions. These different were strictly related to their half-life, potential input sources (included their parents, 238 U and 232 Th), parent's characteristic, the geological setting/formation of the study area, environment origin and behavior. (author)

  15. Study of natural radionuclides - 226Ra, 228Ra and 210PB - in marine sediment cores from Southwest Atlantic during the Holocene

    International Nuclear Information System (INIS)

    Costa, Alice Miranda Ribeiro

    2016-01-01

    Natural radionuclides from 238 U and 232 Th series have been successfully applied as tracers of environmental process and climate changes. The 210 Pb (half-life of 22.2 years) is used in the geochronological dating technique of sediment cores of the last 100-150 years, and its respective sedimentation rate determination. The study of 226 Ra and 228 Ra concentrations (half-lives of 1,600 years and 5.75 years, respectively) helps calculate the activity of 210 Pb in excess in the environment, besides being important tracers of marine processes, as ground water discharge. In this work it was determined the activity concentrations of 226 Ra, 228 Ra and 210 Pb in four short marine cores collected since the continental platform to upper slope of Southwest Atlantic Ocean. Taking into account the results obtained, sedimentation rates and the ages of each sediment layer were determined using the geochronological dating method with 210 Pb. All sediment samples were total acid digested in microwave. The sequential radiochemical separation of 226 Ra, 228 Ra, 210 Pb were performed, obtaining in the end the precipitation of Ba(Ra)SO 4 and PbCrO 4 . The gross α measurements of 226 Ra and gross β measurements of 228 Ra and 210 Pb from the precipitates were carried out in a gas-flow low background proportional counter. Concerning all cores analyzed, the activities concentrations of 226 Ra ranged from 14 Bq.kg -1 to 154 Bq.kg -1 ; the concentrations of 228 Ra ranged from 17 Bq.kg -1 to 45 Bq.kg -1 ; and the concentrations of 210 Pb ranged from 20 Bq.kg -1 to 2,073 Bq.kg -1 . High values of 210 Pb were observed on the top of all the cores studied, mainly related to atmospheric deposition. The results obtained in this work were of the same order of magnitude of those reported in the literature available on non contaminated areas of Southeast Brazilian Coast. Sedimentation rates fall with the increase of water column depth and ranged from 0,049 cm.ano -1 to 0.40 cm.y -1 . (author)

  16. Radiocarbon dating of Irish Sea sediments

    Science.gov (United States)

    Kershaw, P. J.

    1986-09-01

    Radiocarbon dating has been carried out on three cores from areas of muddy sediments in the N. Irish Sea to estimate rates of sediment accumulation. 14C age profiles of the two eastern basin cores revealed a near-constant age from the sediment surface to the base of the core (12 500±1000 years bp). The 14C age profile of the western basin core revealed a zone of apparent mixing to a depth of 55 cm, underlain by a zone of constant sedimentation rate (0·018 cm y -1) to 160 cm. These data are discussed in relation both to previously reported sedimentological studies of the area and to the authorised discharges of low-level radioactive waste from the Sellafield nuclear fuel reprocessing plant.

  17. 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.

  18. Assessment of heavy metal contamination in core sediment samples in Gulf of Izmir, Aegean Sea, Turkey (by inductively coupled plasma-optical emission spectrometry (ICP-OES))

    Science.gov (United States)

    Ünal Yumun, Zeki; Kam, Erol; Kurt, Dilek

    2017-04-01

    Heavy metal and radionuclide analysis studies are crucial in explaining biotic and abiotic interactions in ecosystems. This type of analysis is highly needed in environments such as coastal areas, gulfs or lakes where human activities are generally concentrated. Sediments are one of the best biological indicators for the environment since the pollution accumulates in the sediments by descent to the sea floor. In this study, sediments were collected from the Gulf of Izmir (Eastern Aegean Sea, Turkey) considering the accumulated points of domestic and industrial wastes to make an anthropogenic pollution analysis. The core sediments had different depths of 0.00-30.00 m at four different locations where Karsiyaka, Bayrakli, Incialti and Cesmealti in the Gulf of Izmir. The purpose of the study was determining Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn concentrations in the drilling samples to assess their levels and spatial distribution in crucial areas of the Aegean Sea by inductively coupled plasma-optical emission spectrometry (ICP-OES) with microwave digestion techniques. The heavy metal concentrations found in sediments varied for Cd: sediments were relatively unpolluted. The potential ecological risk assessment was not found in Cesmealti while Karsiyaka and Inciralti had higher levels in parts of investigating heavy metals. Keywords: Gulf of Izmir, heavy metals, ICP-OES, pollution, sediment.

  19. High-resolution sub-bottom seismic and sediment core records from the Chukchi Abyssal Plain reveal Quaternary glaciation impacts on the western Arctic Ocean

    Science.gov (United States)

    Joe, Y. J.; Seokhoon, Y.; Nam, S. I.; Polyak, L.; Niessen, F.

    2017-12-01

    For regional context of the Quaternary history of Arctic marine glaciations, such as glacial events in northern North America and on the Siberian and Chukchi margins, we used CHIRP sub-bottom profiles (SBP) along with sediment cores, including a 14-m long piston core ARA06-04JPC taken from the Chukchi abyssal plain during the RV Araon expedition in 2015. Based on core correlation with earlier developed Arctic Ocean stratigraphies using distribution of various sedimentary proxies, core 04JPC is estimated to extend to at least Marine Isotope Stage 13 (>0.5 Ma). The stratigraphy developed for SBP lines from the Chukchi abyssal plain to surrounding slopes can be divided into four major seismostratigraphic units (SSU 1-4). SBP records from the abyssal plain show well preserved stratification, whereas on the surrounding slopes this pattern is disrupted by lens-shaped, acoustically transparent sedimentary bodies interpreted as glaciogenic debris flow deposits. Based on the integration of sediment physical property and SBP data, we conclude that these debris flows were generated during several ice-sheet grounding events on the Chukchi and East Siberian margins, including adjacent ridges and plateaus, during the middle to late Quaternary.

  20. Accumulation and distribution of heavy metals in surface sediments of a semienclosed basin in the southeastern Mediterranean Sea, Egypt

    Directory of Open Access Journals (Sweden)

    M.A.M. ABDALLAH

    2007-06-01

    Full Text Available The distribution, enrichment and accumulation of heavy metals in the surficial sediments of the Alexandria City Eastern Harbour (Mediterranean coast of Egypt were investigated. Surface sediments (in the <63mm fraction collected from 12 sites representing the entire area of the harbour, were analyzed by AAS for Cd, Cu, Zn, Cr, Pb and Al. Metal contents were compared with literature data to assess the pollution status of sediments. Enrichment factors (EFs and the geoaccumulation Index (Igeo were calculated as a criterion of possible contamination.

  1. Diversity of Microbial Communities and Quantitative Chemodiversity in Layers of Marine Sediment Cores from a Causeway (Kaichu-Doro in Okinawa Island, Japan

    Directory of Open Access Journals (Sweden)

    Taha Soliman

    2017-12-01

    Full Text Available Microbial community diversity and chemodiversity were investigated in marine sediments adjacent to the Okinawan “Kaichu-Doro” Causeway, which was constructed 46 years ago to connect a group of four islands (Henza-jima, Miyagi-jima, Ikei-jima, Hamahiga-jima to the Okinawan main island. This causeway was not built on pilings, but by land reclamation; hence, it now acts as a long, thin peninsula. The construction of this causeway was previously shown to have influenced the surrounding marine ecosystem, causing ecosystem fragmentation and loss of water circulation. In this study, we collected sediment cores (n = 10 from five paired sites in 1 m water depths. Each pair of sites consisted of one site each on the immediate north and south sides of the causeway. Originally the members of each pair were much closer to each other (<150 m than to other pairs, but now the members of each pair are isolated by the causeway. Each core was 60–80 cm long and was divided into 15-cm layers. We examined the vertical diversity of microbial communities and chemical compounds to determine the correlation between chemodiversity and microbial communities among marine sediment cores and layers. Principal coordinate analyses (PCoA of detected compounds and of bacterial and archaeal operational taxonomic units (OTUs revealed that the north and south sides of the causeway are relatively isolated, with each side having unique microbial OTUs. Additionally, some bacterial families (e.g., Acidaminobacteraceae, Rhizobiaceae, and Xanthomonadaceae were found only on the south side of Kaichu-Doro. Interestingly, we found that the relative abundance of OTUs for some microbial families increased from top to bottom, but this was reversed in some other families. We conclude that the causeway has altered microbial community composition and metabolite profiles in marine sediments.

  2. Diversity of Microbial Communities and Quantitative Chemodiversity in Layers of Marine Sediment Cores from a Causeway (Kaichu-Doro) in Okinawa Island, Japan.

    Science.gov (United States)

    Soliman, Taha; Reimer, James D; Yang, Sung-Yin; Villar-Briones, Alejandro; Roy, Michael C; Jenke-Kodama, Holger

    2017-01-01

    Microbial community diversity and chemodiversity were investigated in marine sediments adjacent to the Okinawan "Kaichu-Doro" Causeway, which was constructed 46 years ago to connect a group of four islands (Henza-jima, Miyagi-jima, Ikei-jima, Hamahiga-jima) to the Okinawan main island. This causeway was not built on pilings, but by land reclamation; hence, it now acts as a long, thin peninsula. The construction of this causeway was previously shown to have influenced the surrounding marine ecosystem, causing ecosystem fragmentation and loss of water circulation. In this study, we collected sediment cores ( n = 10) from five paired sites in 1 m water depths. Each pair of sites consisted of one site each on the immediate north and south sides of the causeway. Originally the members of each pair were much closer to each other (<150 m) than to other pairs, but now the members of each pair are isolated by the causeway. Each core was 60-80 cm long and was divided into 15-cm layers. We examined the vertical diversity of microbial communities and chemical compounds to determine the correlation between chemodiversity and microbial communities among marine sediment cores and layers. Principal coordinate analyses (PCoA) of detected compounds and of bacterial and archaeal operational taxonomic units (OTUs) revealed that the north and south sides of the causeway are relatively isolated, with each side having unique microbial OTUs. Additionally, some bacterial families (e.g., Acidaminobacteraceae, Rhizobiaceae, and Xanthomonadaceae) were found only on the south side of Kaichu-Doro. Interestingly, we found that the relative abundance of OTUs for some microbial families increased from top to bottom, but this was reversed in some other families. We conclude that the causeway has altered microbial community composition and metabolite profiles in marine sediments.

  3. Sedimentation and chemical quality of surface waters in the Wind River basin, Wyoming

    Science.gov (United States)

    Colby, B.R.; Hembree, C.H.; Rainwater, F.H.

    1956-01-01

    This report gives results of an investigation by the U. S. Geological Survey of chemical quality of surface waters and sedimentation in the Wind River Basin, Wyo. The sedimentation study was begun in 1946 to determine the quantity of sediment that is transported by the streams in the basin; the probable sources of the sediment; the effect of large irrigation projects on sediment yield, particularly along Fivemile Creek; and the probable specific weight of the sediment when initially deposited in a reservoir. The study of the chemical quality of the water was begun in 1945 to obtain information on the sources, nature, and amounts of dissolved material that is transported by streams and on the suitability of the waters for different uses. Phases of geology and hydrology pertinent to the sedimentation and chemical quality were studied. Results of the investigation through September 30, 1952, and some special studies that were made during the 1953 and 1954 water years are reported. The rocks in the Wind River Basin are granite, schist, and gneiss of Precambrian age and a thick series of sedimentary strata that range in age from Cambrian to Recent. Rocks of Precambrian and Paleozoic age are confined to the mountains, rocks of Mesozoic age crop out along the flank of the Wind River and Owl Creek Mountains and in denuded anticlines in the floor of the basin, and rocks of Tertiary age cover the greater part of the floor of the basin. Deposits of debris from glaciers are in the mountains, and remnants of gravel-capped terraces of Pleistocene age are on the floor of the basin. The lateral extent and depth of alluvial deposits of Recent age along all the streams are highly variable. The climate of the floor of the basin is arid. The foothills probably receive a greater amount of intense rainfall than the areas at lower altitudes. Most precipitation in the Wind River Mountains falls as snow. The foothill sections, in general, are transitional zones between the cold, humid

  4. Seasonal variability of benthic ammonium release in the surface sediments of the Gulf of Gdansk (southern Baltic Sea

    Directory of Open Access Journals (Sweden)

    Dorota Maksymowska-Brossard

    2001-03-01

    Full Text Available This paper describes the seasonal and spatial variations of diffusive sediment- water ammonium fluxes in the western part of the Gulf of Gdansk (southern Baltic. It assesses the potential environmental controls of these fluxes, such as the inflow of organic matter to bottom sediments and its quality, temperature-induced degradation of organic matter, and the redox potential of sediments. Ammonium fluxes, calculated using Fick's first law, were always in the direction from the sediment into the water column and differed significantly with respect to sediment type. Fluxes were most intensive in sediments with the highest silt-clay fraction located in the deepest parts of the study area. The mean annual diffusive fluxes of ammonium from sediments to near-bottom water were estimated at 5.24 tonnes km-2 year-1 for silty-clays, 1.85 tonnes km-2 year-1 for silty-sands and 1.03 tonnes km-2 year-1 for sandy sediments. There was a high seasonal variation, with the greatest ammonium release in summer and early autumn, when the temperature of near-bottom water was the highest. On the basis of the calculated diffusive ammonium fluxes, we estimated that approximately 2700 tonnes of N-NH4+ are released annually from the surface sediments of the western part of the Gulf of Gdansk, providing a minimum of 10% of the mineral nitrogen essential for primary production in surface waters. Our results are undoubtedly underestimated, as we disregarded advective ammonium fluxes, which in some areas of the Gulf of Gdansk could well be comparable to diffusive fluxes.

  5. Tracing historical trends of Hg in the Mississippi River using Hg concentrations and Hg isotopic compositions in a lake sediment core, Lake Whittington, Mississippi, USA

    Science.gov (United States)

    Gray, John E.; Van Metre, Peter C.; Pribil, Michael J.; Horowitz, Arthur J.

    2015-01-01

    Concentrations and isotopic compositions of mercury (Hg) in a sediment core collected from Lake Whittington, an oxbow lake on the Lower Mississippi River, were used to evaluate historical sources of Hg in the Mississippi River basin. Sediment Hg concentrations in the Lake Whittington core have a large 10-15 y peak centered on the 1960s, with a maximum enrichment factor relative to Hg in the core of 4.8 in 1966. The Hg concentration profile indicates a different Hg source history than seen in most historical reconstructions of Hg loading. The timing of the peak is consistent with large releases of Hg from Oak Ridge National Laboratory (ORNL), primarily in the late 1950s and 1960s. Mercury was used in a lithiumisotope separation process by ORNL and an estimated 128Mg (megagrams) of Hgwas discharged to a local stream that flows into the Tennessee River and, eventually, the Mississippi River. Mass balance analyses of Hg concentrations and isotopic compositions in the Lake Whittington core fit a binary mixing model with a Hg-rich upstream source contributing about 70% of the Hg to Lake Whittington at the height of the Hg peak in 1966. This upstream Hg source is isotopically similar to Hg isotope compositions of stream sediment collected downstream near ORNL. It is estimated that about one-half of the Hg released from the ORNL potentially reached the LowerMississippi River basin in the 1960s, suggesting considerable downstream transport of Hg. It is also possible that upstream urban and industrial sources contributed some proportion of Hg to Lake Whittington in the 1960s and 1970s.

  6. Physical mechanism of surface roughening of the radial Ge-core/Si-shell nanowire heterostructure and thermodynamic prediction of surface stability of the InAs-core/GaAs-shell nanowire structure.

    Science.gov (United States)

    Cao, Y Y; Ouyang, G; Wang, C X; Yang, G W

    2013-02-13

    As a promising and typical semiconductor heterostructure at the nanoscale, the radial Ge/Si NW heterostructure, that is, the Ge-core/Si-shell NW structure, has been widely investigated and used in various nanodevices such as solar cells, lasers, and sensors because of the strong changes in the band structure and increased charge carrier mobility. Therefore, to attain high quality radial semiconductor NW heterostructures, controllable and stable epitaxial growth of core-shell NW structures has become a major challenge for both experimental and theoretical evaluation. Surface roughening is usually undesirable for the epitaxial growth of high quality radial semiconductor NW heterostructures, because it would destroy the core-shell NW structures. For example, the surface of the Ge-core/Si-shell NWs always exhibits a periodic modulation with island-like morphologies, that is, surface roughening, during epitaxial growth. Therefore, the physical understanding of the surface roughening behavior during the epitaxial growth of core-shell NW structures is essential and urgent for theoretical design and experimentally controlling the growth of high quality radial semiconductor NW heterostructures. Here, we proposed a quantitative thermodynamic theory to address the physical process of epitaxial growth of core-shell NW structures and surface roughening. We showed that the transformation from the Frank-van der Merwe mode to the Stranski-Krastanow mode during the epitaxial growth of radial semiconductor NW heterostructures is the physical origin of surface roughening. We deduced the thermodynamic criterion for the formation of the surface roughening and the phase diagram of growth and showed that the radius of the NWs and the thickness of the shell layer can not only determine the formation of the surface roughening in a core-shell NW structure, but also control the periodicity and amplitude of the surface roughness. The agreement between the theoretical results and the

  7. Degradation state of organic matter in surface sediments from the Southern Beaufort Sea: a lipid approach

    Directory of Open Access Journals (Sweden)

    J.-F. Rontani

    2012-09-01

    Full Text Available For the next decades significant climatic changes should occur in the Arctic zone. The expected destabilisation of permafrost and its consequences for hydrology and plant cover should increase the input of terrigenous carbon to coastal seas. Consequently, the relative importance of the fluxes of terrestrial and marine organic carbon to the seafloor will likely change, strongly impacting the preservation of organic carbon in Arctic marine sediments. Here, we investigated the lipid content of surface sediments collected on the Mackenzie basin in the Beaufort Sea. Particular attention was given to biotic and abiotic degradation products of sterols and monounsaturated fatty acids. By using sitosterol and campesterol degradation products as tracers of the degradation of terrestrial higher plant inputs and brassicasterol degradation products as tracers of degradation of phytoplanktonic organisms, it could be observed that autoxidation, photooxidation and biodegradation processes act much more intensively on higher plant debris than on phytoplanktonic organisms. Examination of oxidation products of monounsaturated fatty acids showed that photo- and autoxidation processes act more intensively on bacteria than on phytodetritus. Enhanced damages induced by singlet oxygen (transferred from senescent phytoplanktonic cells in bacteria were attributed to the lack of an adapted antioxidant system in these microorganisms. The strong oxidative stress observed in the sampled sediments resulted in the production of significant amounts of epoxy acids and unusually high proportions of monounsaturated fatty acids with a trans double bond. The formation of epoxy acids was attributed to peroxygenases (enzymes playing a protective role against the deleterious effects of fatty acid hydroperoxides in vivo, while cis/trans isomerisation was probably induced by thiyl radicals produced during the reaction of thiols with hydroperoxides. Our results confirm the

  8. Degradation state of organic matter in surface sediments from the Southern Beaufort Sea: a lipid approach

    Science.gov (United States)

    Rontani, J.-F.; Charriere, B.; Petit, M.; Vaultier, F.; Heipieper, H. J.; Link, H.; Chaillou, G.; Sempéré, R.

    2012-09-01

    For the next decades significant climatic changes should occur in the Arctic zone. The expected destabilisation of permafrost and its consequences for hydrology and plant cover should increase the input of terrigenous carbon to coastal seas. Consequently, the relative importance of the fluxes of terrestrial and marine organic carbon to the seafloor will likely change, strongly impacting the preservation of organic carbon in Arctic marine sediments. Here, we investigated the lipid content of surface sediments collected on the Mackenzie basin in the Beaufort Sea. Particular attention was given to biotic and abiotic degradation products of sterols and monounsaturated fatty acids. By using sitosterol and campesterol degradation products as tracers of the degradation of terrestrial higher plant inputs and brassicasterol degradation products as tracers of degradation of phytoplanktonic organisms, it could be observed that autoxidation, photooxidation and biodegradation processes act much more intensively on higher plant debris than on phytoplanktonic organisms. Examination of oxidation products of monounsaturated fatty acids showed that photo- and autoxidation processes act more intensively on bacteria than on phytodetritus. Enhanced damages induced by singlet oxygen (transferred from senescent phytoplanktonic cells) in bacteria were attributed to the lack of an adapted antioxidant system in these microorganisms. The strong oxidative stress observed in the sampled sediments resulted in the production of significant amounts of epoxy acids and unusually high proportions of monounsaturated fatty acids with a trans double bond. The formation of epoxy acids was attributed to peroxygenases (enzymes playing a protective role against the deleterious effects of fatty acid hydroperoxides in vivo), while cis/trans isomerisation was probably induced by thiyl radicals produced during the reaction of thiols with hydroperoxides. Our results confirm the important role played by abiotic

  9. Metal speciation in surface sediments of the Vigo Ria (NW Iberian Peninsula

    Directory of Open Access Journals (Sweden)

    María Jesús Belzunce Segarra

    2008-03-01

    Full Text Available Total concentrations and chemical forms of metals in surface sediments of the Vigo Ria (NW Iberian Peninsula were determined following the sequential extraction method proposed by Tessier et al. (1979. Total values ranged from 7 to 14 µgCo g-1, 52 to 76 µgCr g-1, 18 to 82 µgCu g g-1, 136 to 209 µgMn g g-1, 18 to 30 µgNi g g-1, 24 to 112 µgPb g g-1, 62 to 185 µgZn g g-1 and 18 to 34 mg g g-1 for Fe. The distribution of metals is strongly influenced by the presence of urban and industrial centres. A decreasing concentration trend was observed towards (i the outer-oceanic part of the ria and (ii the northern shore in the middle part. Cobalt, Cr, Fe, Mn, and Ni were found to be strongly associated with the residual fraction of the sediment (65-78%, whereas Cu is significantly present in the oxidisable phase (34-72% and Pb and Zn are found in both the reducible (14-49% and the oxidisable (14-39% phases. The speciation patterns reflect natural uncontaminated conditions in the outer part of the ria. However, a significant fraction of the Cu, Pb, and Zn in the sediments of the southern margin of the middle part of the ria, which supports most of the population and industrial activities, is present in labile forms, so a potential pollution risk may exist.

  10. Experimental removal of wetland emergent vegetation leads to decreased methylmercury production in surface sediment

    Science.gov (United States)

    Windham-Myers, Lisamarie; Marvin-DiPasquale, Mark; Krabbenhoft, David P.; Agee, Jennifer L.; Cox, Marisa H.; Heredia-Middleton, Pilar; Coates, Carolyn; Kakouros, Evangelos

    2009-01-01

    We performed plant removal (devegetation) experiments across a suite of ecologically diverse wetland settings (tidal salt marshes, river floodplain, rotational rice fields, and freshwater wetlands with permanent or seasonal flooding) to determine the extent to which the presence (or absence) of actively growing plants influences the activity of the Hg(II)-methylating microbial community and the availability of Hg(II) to those microbes. Vegetated control plots were paired with neighboring devegetated plots in which photosynthetic input was terminated 4–8 months prior to measurements, through clipping aboveground biomass, severing belowground connections, and shading the sediment surface to prevent regrowth. Across all wetlands, devegetation decreased the activity of the Hg(II)-methylating microbial community (kmeth) by 38%, calculated MeHg production potential (MP) rates by 36%, and pore water acetate concentration by 78%. Decreases in MP were associated with decreases in microbial sulfate reduction in salt marsh settings. In freshwater agricultural wetlands, decreases in MP were related to indices of microbial iron reduction. Sediment MeHg concentrations were also significantly lower in devegetated than in vegetated plots in most wetland settings studied. Devegetation effects were correlated with live root density (percent volume) and were most profound in vegetated sites with higher initial pore water acetate concentrations. Densely rooted wetlands had the highest rates of microbial Hg(II)-methylation activity but often the lowest concentrations of bioavailable reactive Hg(II). We conclude that the exudation of labile organic carbon (e.g., acetate) by plants leads to enhanced microbial sulfate and iron reduction activity in the rhizosphere, which results in high rates of microbial Hg(II)-methyation and high MeHg concentrations in wetland sediment.

  11. Aryl hydrocarbon receptor (AhR) inducers and estrogen receptor (ER) activities in surface sediments of Three Gorges Reservoir, China evaluated with in vitro cell bioassays

    NARCIS (Netherlands)

    Wang, J.; Bovee, T.F.H.; Bi, Y.; Bernhöft, S.; Schramm, K.W.

    2014-01-01

    Two types of biological tests were employed for monitoring the toxicological profile of sediment cores in the Three Gorges Reservoir (TGR), China. In the present study, sediments collected in June 2010 from TGR were analyzed for estrogen receptor (ER)- and aryl hydrocarbon receptor (AhR)-mediated

  12. BET surface area distributions in polar stream sediments: Implications for silicate weathering in a cold-arid environment

    Science.gov (United States)

    Marra, Kristen R.; Elwood Madden, Megan E; Soreghan, Gerilyn S.; Hall, Brenda L

    2014-01-01

    BET surface area values are critical for quantifying the amount of potentially reactive sediments available for chemical weathering and ultimately, prediction of silicate weathering fluxes. BET surface area values of fine-grained (<62.5 μm) sediment from the hyporheic zone of polar glacial streams in the McMurdo Dry Valleys, Antarctica (Wright and Taylor Valleys) exhibit a wide range (2.5–70.6 m2/g) of surface area values. Samples from one (Delta Stream, Taylor Valley) of the four sampled stream transects exhibit high values (up to 70.6 m2/g), which greatly exceed surface area values from three temperate proglacial streams (0.3–12.1 m2/g). Only Clark stream in Wright Valley exhibits a robust trend with distance, wherein surface area systematically decreases (and particle size increases) in the mud fraction downstream, interpreted to reflect rapid dissolution processes in the weathering environment. The remaining transects exhibit a range in variability in surface area distributions along the length of the channel, likely related to variations in eolian input to exposed channel beds, adjacent snow drifts, and to glacier surfaces, where dust is trapped and subsequently liberated during summer melting. Additionally, variations in stream discharge rate, which mobilizes sediment in pulses and influences water:rock ratios, the origin and nature of the underlying drift material, and the contribution of organic acids may play significant roles in the production and mobilization of high-surface area sediment. This study highlights the presence of sediments with high surface area in cold-based glacier systems, which influences models of chemical denudation rates and the impact of glacial systems on the global carbon cycle.

  13. Synchronizing Greenland ice-core records and the Meerfelder maar sediment record via the global cosmogenic radionuclide signature and insights on climate around 11,230 years BP

    Science.gov (United States)

    Mekhaldi, F.; Czymzik, M.; Brauer, A.; Martin-Puertas, C.; Aldahan, A.; Possnert, G.; Muscheler, R.

    2017-12-01

    The causal investigation of multiple paleoclimate records relies on the accuracy of their respective chronostratigraphy. To achieve relative synchronization, cosmogenic radionuclides are an excellent tool because their common signature is global and can be retrieved and measured in different paleoclimate archives. For instance, 10Be can be measured in both ice cores and lake sediments (Berggren et al., 2013; Czymzik et al., 2016) which allows for both archives to be anchored onto radiocarbon timescales by synchronizing 10Be with 14C. We investigate the period 11,500-11,000 years BP when a short cold climate spell is known, from ice-core proxy records, to have occurred in Greenland shortly after the onset of the Holocene - the Preboreal Oscillation (PBO). This period also coincides with one of the largest and longest-lived increase in 14C production rate during the Holocene, which most likely corresponds to a grand solar minimum (around 11,230-11,000 years BP). In consequence, this period ideally illustrates the potential of using a known and clear signal in the production rate of cosmogenic radionuclides as a synchronizing tool, such as caused by large variations in solar activity. Here we measure 10Be in Meerfelder Maar (a well-dated and widely used sediment record from Germany) around 11,230 years BP which allows us to align the 10Be signal in both the Meerfelder Maar (MFM) sediment record and the GRIP ice core to IntCal13. Doing so, we report that i) the structure of the grand solar minimum is well-preserved in the 10Be signal of MFM sediments, ii) the PBO in Greenland occurs during high levels of solar activity and is not clearly observed in MFM, and iii) the PBO in Greenland ends precisely at the onset of the grand solar minimum at 11,230 years BP which also corresponds to a depositional change in MFM sediments (Martin-Puertas et al., 2017). These results thus suggest that changes in solar activity could have been a forcing at play eventually resulting in the

  14. 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

  15. Degradation state of organic matter in surface sediments from the Beaufort Shelf: a lipid approach

    Science.gov (United States)

    Rontani, J.-F.; Charriere, B.; Petit, M.; Vaultier, F.; Heipieper, H. J.; Link, H.; Chaillou, G.; Sempéré, R.

    2012-03-01

    The lipid content of surface sediments collected on the Beaufort Shelf was examined. Particular attention was given to biotic and abiotic degradation products of sterols and monounsaturated fatty acids. By using sitosterol and campesterol degradation products as tracers of the degradation of terrestrial higher plant inputs and brassicasterol degradation products as tracers of degradation of phytoplanktonic organisms, it could be observed that autoxidation, photooxidation and biodegradation processes act much more intensively on higher plant debris than on phytoplanktonic organisms. Examination of oxidation products of monounsaturated fatty acids showed that photo- and autoxidation processes act more intensively on bacteria than on phytodetritus. Enhanced damages induced by singlet oxygen (transferred from senescent phytoplanktonic cells) in bacteria were attributed to the lack of an adapted antioxidant system in these microorganisms. The strong oxidative stress observed in the sampled sediments resulted in the production of significant amounts of epoxyacids and unusually very high proportions of monounsaturated fatty acids with a trans double bond. The formation of epoxyacids was attributed to peroxygenases (enzymes playing a protective role against the deleterious effects of fatty acid hydroperoxides in vivo), while cis/trans isomerization was probably induced by thiyl radicals produced during the reaction of thiols with hydroperoxides. Our results confirm the important role played by abiotic oxidative processes in the degradation of marine bacteria and do not support the generally expected refractory character of terrigenous material deposited in deltaic systems.

  16. Microbial activity in surface sediments of Chacopata-Bocaripo lagoon axis, Sucre State, Venezuela.

    Science.gov (United States)

    Segnini de B, Mary Isabel; Gómez, Irma; Brito, Leonor; Acosta, Vanessa; Troccoli, Luis

    2015-02-28

    The aim of this work was to evaluate the microbial activity of the surface sediments (0-10 cm) of the Chacopata-Bocaripo lagoon axis (Ch-BLA) through microbiological parameters: microbial biomass (Cmic) dehydrogenase activity (DHS), fluorescein diacetate hydrolysis (HFDA), arginine ammonification (AA) and biochemical parameters: phosphatase (PHa) and urease (URa) activity. They were determined during transition (July 2010) and upwelling (March 2011) periods. Total organic carbon (TOC) did not vary significantly (p⩾0.05) between climatic periods. All the parameters studied were higher in upwelling season: Cmic (191.79 mg Cmic kg(-1)), DHS (228.70 μg TFF g(-1) 24 h(-1)), HFDA (204.09 μg fluorescein g(-1) 24 h(-1)), AA (13.09 μg NH4-N g(-1) h(-1)), PHa (132.31 μg pNF g(-1) h(-1)), URa (12.90 μg NH4-N g(-1) h(-1)). They appear to be controlled by the availability and quality of nutrients in each climatic period, and were useful tools for evaluating changes in microbial activity in marine sediments. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Temporal variation of coastal surface sediment bacterial communities along an environmental pollution gradient.

    Science.gov (United States)

    Thiyagarajan, V; Tsoi, M M Y; Zhang, W; Qian, P Y

    2010-07-01

    Terminal restriction fragment length polymorphism analysis (T-RFLP) was used to track the changes of bacterial community compositions (BCC) in coastal surface sediments along an environmental pollution gradient between 2004 and 2006. BCC in the chronically contaminated sites showed the largest deviation from those in the adjacent sites. Surprisingly, BCC at two contrasting environments (oceanic vs. river-influenced) were more similar. Unexpectedly, the BCC did not recover (when compared to oceanic control site) even after 5 years of pollution abatement initiatives in Victoria Harbour, Hong Kong. On the other hand, disposal of treated sewage for 5 years in one of the sites did not significantly affect the BCC. A striking seasonal variation in the BCC was observed at only the polluted sites. Although factors other than pollution gradients may explain the observed BCC patterns, the information presented here can be useful in predicting long-term effects of pollution on BCC. Furthermore, this study suggests that BCC analysis using T-RFLP is a faster, reliable and easier approach to monitor microbenthic community response to environmental pollution gradient in coastal sediments. 2010 Elsevier Ltd. All rights reserved.

  18. Influence of surface modification techniques on shear bond strength between different zirconia cores and veneering ceramics

    Science.gov (United States)

    Rismanchian, Mansour; Savabi, Omid; Ashtiani, Alireza Hashemi

    2011-01-01

    PURPOSE Veneering porcelain might be delaminated from underlying zirconia-based ceramics. The aim of this study was the evaluation of the effect of different surface treatments and type of zirconia (white or colored) on shear bond strength (SBS) of zirconia core and its veneering porcelain. MATERIALS AND METHODS Eighty zirconia disks (40 white and 40 colored; 10 mm in diameter and 4 mm thick) were treated with three different mechanical surface conditioning methods (Sandblasting with 110 µm Al2O3 particle, grinding, sandblasting and liner application). One group had received no treatment. These disks were veneered with 3 mm thick and 5 mm diameter Cercon Ceram Kiss porcelain and SBS test was conducted (cross-head speed = 1 mm/min). Two and one way ANOVA, Tukey's HSD Past hoc, and T-test were selected to analyzed the data (α=0.05). RESULTS In this study, the factor of different types of zirconia ceramics (P=.462) had no significant effect on SBS, but the factors of different surface modification techniques (P=.005) and interaction effect (P=.018) had a significant effect on SBS. Within colored zirconia group, there were no significant differences in mean SBS among the four surface treatment subgroups (P=0.183). Within white zirconia group, "Ground group" exhibited a significantly lower SBS value than "as milled" or control (P=0.001) and liner (P=.05) groups. CONCLUSION Type of zirconia did not have any effect on bond strength between zirconia core and veneer ceramic. Surface treatment had different effects on the SBS of the different zirconia types and grinding dramatically decreased the SBS of white zirconia-porcelain. PMID:22259706

  19. [Risk assessment and analysis of polycyclic aromatic hydrocarbons in the surface sediments of Xinglin Bay Suburb Rivers of Xiamen].

    Science.gov (United States)

    Cheng, Qi-ming; Huang, Qing; Liao, Zhen-ni; Su, Li; Liu, Xing-qiang; Tang, Jian-feng

    2015-01-01

    The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), declared as carcinogens by USEPA, were measured in the sediment samples (n = 19) collected along Xinglin Bay rivers/canals present in Xiamen. PAHs were extracted using accelerated solvent extraction system and analyzed using gas chromatography-mass spectrometry (GC-MS). The possible sources of PAHs and their health risk were investigated. Among selected PAHs, 13 PAHs were detected in the surface sediments. Total concentrations of PAHs in the surface sediments ranged from 413.00 to 2748.81 ng x g(-1), with a mean value of 949.56 ng x g(-1). The mean concentration of highly carcinogenic compounds such as benzo [k] fluoranthene (BkF) and benzo [g, h, i] perylene (BghiP) were 69.15 ng x g(-1) and 49.86 ng x g(-1), respectively and counted for 73.68% out of the total samples. The dominant PAH compounds were 2, 3 and 4 rings and counted for 61.03% and 23.53% , respectively; while 5-6 rings containing PAHs were accounted for 15.82%. According to the results, 68.42% of samples were moderately contaminated, while 31.58% were highly contaminated with PAHs. Based on the ratios of Ant/(Ant + Phe) and Fla/(Fla + Pyr), it cleared that PAHs in surface sediments were mainly derived from fossil fuel and combustion products. Principal component analysis results and sediment quality benchmarks (mSQG-Q) were used for risk assessment of these PAH contaminated sediments. The risk SQG-Q of 16 PAHs were less than 0.50. Comprehensive content, composition and SQG-Q showed that a certain degree of ecological risks of PAH pollution existed in the surface sediments, particularly in the sites close to Xinglin Industrial Zone (2, 3, 5 and 9) and Gangtou(13), which need further research work and proper attentions.

  20. Quantification of MTE in surface sediments of Morbihan Coast (South Brittany, France): A preliminary approach for determination of sources and dynamics

    Science.gov (United States)

    Jimenez, Joselyn; Goubert, Evelyne; Labeyrie, Laurent; Coynel, Alexandra; Menier, David

    2014-05-01

    The Morbihan Coast (South Brittany, France) has an intense coastal activity: farming, industry, urban habitation run-off, yachting and transportation. In the past centuries, tin mining industry was also developed. These different factors may introduce metal trace elements (MTE) into the marine environment at toxic concentration levels. This pollution can particularly affect the oyster production, widely developed in the area. Monitoring MTE in surface sediments at high spatial resolution has been programmed to assess pollutants and their sources in two of the major Morbihan coastal systems concerned with oyster farming, and where available information on MTE impact and sediment quality is limited: the Bay of Quiberon, partly protected from the open ocean by the Quiberon Peninsula and several islands, mostly sandy (coarse to fine, with a significant shelly fraction), with water depths shallower that 25 m, and the Gulf of Morbihan, a shallow depth (less than 5 m, apart from the two paleoriver beds), semi-enclosed, estuarine system with very coarse sand to fine mud, mostly distributed by a strong tidal current system. Fifty two surface sediment samples were collected in April 2013 to characterize the MTE spatial distribution through the salinity and pollution gradients, from the small local rivers and harbor areas to the open marine environments. Analyses cover sedimentological and biogeochemical properties (particulate organic carbon using a LECO-CS-230; MTE using ICP-MS or DMA for Hg). Statistical analyses help to discriminate within the spatial variability the natural (e.g. grain-size effect) and anthropogenic factors. MTE concentrations were also compared to local geochemical background as measured at the bottom of three sediment cores collected in representative sites, for calculating the enrichment index of each MTE and evaluating the degree of sediment contamination. The initial interpretation of the results would indicate a clear distinction between the

  1. Key parameters of the sediment surface morphodynamics in an estuary - An assessment of model solutions

    Science.gov (United States)

    Sampath, D. M. R.; Boski, T.

    2018-05-01

    Large-scale geomorphological evolution of an estuarine system was simulated by means of a hybrid estuarine sedimentation model (HESM) applied to the Guadiana Estuary, in Southwest Iberia. The model simulates the decadal-scale morphodynamics of the system under environmental forcing, using a set of analytical solutions to simplified equations of tidal wave propagation in shallow waters, constrained by empirical knowledge of estuarine sedimentary dynamics and topography. The key controlling parameters of the model are bed friction (f), current velocity power of the erosion rate function (N), and sea-level rise rate. An assessment of sensitivity of the simulated sediment surface elevation (SSE) change to these controlling parameters was performed. The model predicted the spatial differentiation of accretion and erosion, the latter especially marked in the mudflats within mean sea level and low tide level and accretion was mainly in a subtidal channel. The average SSE change mutually depended on both the friction coefficient and power of the current velocity. Analysis of the average annual SSE change suggests that the state of intertidal and subtidal compartments of the estuarine system vary differently according to the dominant processes (erosion and accretion). As the Guadiana estuarine system shows dominant erosional behaviour in the context of sea-level rise and sediment supply reduction after the closure of the Alqueva Dam, the most plausible sets of parameter values for the Guadiana Estuary are N = 1.8 and f = 0.8f0, or N = 2 and f = f0, where f0 is the empirically estimated value. For these sets of parameter values, the relative errors in SSE change did not exceed ±20% in 73% of simulation cells in the studied area. Such a limit of accuracy can be acceptable for an idealized modelling of coastal evolution in response to uncertain sea-level rise scenarios in the context of reduced sediment supply due to flow regulation. Therefore, the idealized but cost

  2. Impacts of mangrove density on surface sediment accretion, belowground biomass and biogeochemistry in Puttalam Lagoon, Sri Lanka

    Science.gov (United States)

    Phillips, D.H.; Kumara, M.P.; Jayatissa, L.P.; Krauss, Ken W.; Huxham, M.

    2017-01-01

    Understanding the effects of seedling density on sediment accretion, biogeochemistry and belowground biomass in mangrove systems can help explain ecological functioning and inform appropriate planting densities during restoration or climate change mitigation programs. The objectives of this study were to examine: 1) impacts of mangrove seedling density on surface sediment accretion, texture, belowground biomass and biogeochemistry, and 2) origins of the carbon (C) supplied to the mangroves in Palakuda, Puttalam Lagoon, Sri Lanka. Rhizophora mucronata propagules were planted at densities of 6.96, 3.26, 1.93 and 0.95 seedlings m−2along with an unplanted control (0 seedlings m−2). The highest seedling density generally had higher sediment accretion rates, finer sediments, higher belowground biomass, greatest number of fine roots and highest concentrations of C and nitrogen (N) (and the lowest C/N ratio). Sediment accretion rates, belowground biomass (over 1370 days), and C and N concentrations differed significantly between seedling densities. Fine roots were significantly greater compared to medium and coarse roots across all plantation densities. Sulphur and carbon stable isotopes did not vary significantly between different density treatments. Isotope signatures suggest surface sediment C (to a depth of 1 cm) is not derived predominantly from the trees, but from seagrass adjacent to the site.

  3. On the accumulation of organic matter on the southeastern Brazilian continental shelf: a case study based on a sediment core from the shelf off Rio de Janeiro

    Directory of Open Access Journals (Sweden)

    Renato da Silva Carreira

    2012-03-01

    Full Text Available Sterol and fatty acid biomarkers and isotopic composition (δ13C and δ15N of bulk organic matter (OM were quantified in a sediment core to characterize the accumulation of autochthonous OM in an area on the continental shelf adjacent to Rio de Janeiro State. In the sediment surface (0-1 cm the concentration of total sterols and fatty acids was at least one order of magnitude higher than that measured deeper down in the core and was dominated by labile and planktonic-derived biomarker compounds. These results suggest, as is confirmed by multivariate statistical analysis, the occurrence of an event of enhanced primary production in the water column and efficient export of particles to the bottom. Similar conditions have been observed at Cabo Frio, located 150 km to the north of our study site, during an upwelling event, suggesting that such events may exert a regional influence on primary production on the south-eastern Brazilian continental shelf. Beyond the signatures from this event, the presence of biomarker compounds from vascular plants suggests the additional influence of an outflow from Guanabara Bay at the study site. These results point to the need for further investigation of the relative influence of physical forcings and continental inputs on the biogeochemical processes on the section of the continental shelf considered in the present study.Marcadores moleculares na classe de lipídios (esterois, ácidos graxos e hidrocarbonetos e a composição isotópica (δ13C e δ15N da matéria orgânica bruta foram quantificados em amostras de um testemunho de sedimento para caracterizar o histórico recente de sedimentação da matéria orgânica na plataforma continental adjacente à Baía de Guanabara, no Estado do Rio de Janeiro. Na superfície do sedimento (0-1 cm, a concentração total de esterois e ácidos graxos foi cerca de uma ordem de grandeza maior do que observado nas camadas mais profundas do sedimento, com predominância de lip

  4. Sea ice and primary production proxies in surface sediments from a High Arctic Greenland fjord

    DEFF Research Database (Denmark)

    Ribeiro, Sofia; Sejr, Mikael K.; Limoges, Audrey

    2017-01-01

    that IP25 records from fjords need to be carefully considered and not directly compared to marine settings. The sea ice-associated biomarker HBI III revealed an open-water signature, with highest concentrations near the mid-July ice edge. This proxy evaluation is an important step towards reliable......In order to establish a baseline for proxy-based reconstructions for the Young Sound–Tyrolerfjord system (Northeast Greenland), we analysed the spatial distribution of primary production and sea ice proxies in surface sediments from the fjord, against monitoring data from the Greenland Ecosystem...... Monitoring Programme. Clear spatial gradients in organic carbon and biogenic silica contents reflected marine influence, nutrient availability and river-induced turbidity, in good agreement with in situ measurements. The sea ice proxy IP25 was detected at all sites but at low concentrations, indicating...

  5. Distribution and pollution assessment of heavy metals in surface sediments in the Yellow Sea.

    Science.gov (United States)

    Jiang, Xin; Teng, Ankang; Xu, Wenzhe; Liu, Xiaoshou

    2014-06-15

    Heavy metal concentrations in surface sediments at 56 stations during two cruises in the Yellow Sea in summer and winter, 2011 were analyzed by inductively coupled plasma-mass spectrometry. The pollution status was assessed via the Geoaccumulation index and Hankanson potential ecological risk index. Higher concentrations of heavy metals (except for Mn) were found in the central Southern Yellow Sea and the western Northern Yellow Sea. The higher contents of Mn were much closer to Shandong Peninsula. Correlation analyses indicated that Pb, Cu, Fe, Ni, Zn and Co probably had the same origin and were controlled by grain size and total organic carbon. Pollution assessment showed that most areas of the Yellow Sea were not or lowly contaminated with the exception of the northwest and south parts of the Southern Yellow Sea showing Cd-contamination. The pollution status of the Yellow Sea in summer was worse than that in winter. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Dinoflagellate cysts from surface sediments of Syracuse Bay (Western Ionian Sea, Mediterranean)

    Science.gov (United States)

    Rubino, Fernando; Belmonte, Manuela; Caroppo, Carmela; Giacobbe, Mariagrazia

    2010-02-01

    The occurrence and abundance of dinoflagellate cysts were investigated for the first time at an Ionian locality along the south-eastern coast of Sicily, subject to spring-summer harmful algal events. Thirty-four cyst morphotypes were recognized belonging to 24 taxa identified at least at the genus level. Cyst abundance in surface sediments ranged from 43 to 828 cysts g -1 dry weight, with the highest numbers recorded at the most restricted station. Germination experiments allowed confirmation of species identification determined by cyst analysis and provided clonal cultures of Alexandrium minutum and Gymnodinium nolleri, two of the bloom-forming species in the area. This represents the first record of G. nolleri for the Mediterranean Sea.

  7. Content of trace metals in surface sediments of Lac Sud de Tunis before development

    International Nuclear Information System (INIS)

    Ben Souissi, J.; Zaouali, J.; Aouij, S.; Orlando, E.; Mazghouni, M.; Rezig, M.

    1999-01-01

    The analysis of metal (Hg, Cd, Pb, Cu, Cr, Ni, Mn, Zn, Fe) concentrations in the surface sediments of the South Lake of Tunis before its restoration showed a high level of contamination. The values for mercury, cadmium and lead oscillate respectively between (0,17 and 2,6 μg/g d.w), (0,13 and 13,3 μg/g d. w); (3,97 and 698 μg/g d. w). This pollution is generated by the intensive industrial activity situated on south banks of the Lake. This environment constitutes since more of the millennium a outfall of urban used waters and since one century an outfall of industrial waste waters strongly charged with nutrients and heavy metals. (author)

  8. Phosphorus fractionation in sediment cores collected in 2005 before and after onset of an Aphanizomenon flos-aquae bloom in upper Klamath Lake, OR, USA

    Science.gov (United States)

    Simon, N.S.; Lynch, D.; Gallaher, T.N.

    2009-01-01

    We tested the hypothesis that there would be measurable losses of phosphorus (P) from surficial sediments of Upper Klamath Lake (UKL), Oregon, if sediments were a source of P during an algal bloom. We compared concentrations of total and forms of P at various depths in cores collected before and after the onset of a large Aphanizomenon flos-aquae bloom. Concentrations of inorganic P were determined in extraction solutions of MgCl2 (1 M, pH 8), citrate-dithionite-bicarbonate, and 1 M HCl. Sediments below 2 cm were dominated by residual P which is defined as total P minus inorganic P. During the study period, data from the top 2-cm of sediment indicated (a) significant decrease in total P concentration, primarily associated with iron oxyhydroxides at one site, and (b) significant increase in total P concentration associated with residual P at a second site. Data from two other sites indicated no net changes in concentrations of total P. ?? 2009 US Government.

  9. Localized surface plasmon mediated energy transfer in the vicinity of core-shell nanoparticle

    Energy Technology Data Exchange (ETDEWEB)

    Shishodia, Manmohan Singh, E-mail: manmohan@gbu.ac.in; Juneja, Soniya [Department of Applied Physics, School of Vocational Studies and Applied Sciences, Gautam Buddha University, Greater Noida 201308 (India)

    2016-05-28

    Multipole spectral expansion based theory of energy transfer interactions between a donor and an acceptor molecule in the vicinity of a core-shell (nanoshell or core@shell) based plasmonic nanostructure is developed. In view of the diverse applications and rich plasmonic features such as tuning capability of surface plasmon (SP) frequencies, greater sensitivity to the change of dielectric environment, controllable redirection of electromagnetic radiation, closed form expressions for Energy Transfer Rate Enhancement Factor (ETREF) near core-shell particle are reported. The dependence of ETREF on different parameters is established through fitting equations, perceived to be of key importance for developing appropriate designs. The theoretical approach developed in the present work is capable of treating higher order multipoles, which, in turn, are also shown to play a crucial role in the present context. Moreover, closed form expressions derived in the present work can directly be used as formula, e.g., for designing SP based biosensors and estimating energy exchange between proteins and excitonic interactions in quantum dots.

  10. Physical characterization of core samples recovered from Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Tae Sup; Carlos Santamarina, J. [School of Civil and Environmental Engineering, Georgia Institute of Technology, 790 Atlantic Drive, Atlanta, GA 30332-0355 (United States); Narsilio, Guillermo A. [Department of Civil and Environmental Engineering, The University of Melbourne, Engineering Block D 321, Parkville, VIC 3010 (Australia)

    2006-12-15

    Seventy whole rounds from conventional cores obtained during drilling to 300mbsf at Atwater Valley and Keathley Canyon in the Gulf of Mexico in April and May 2005 were tested to determine geophysical and geomechanical parameters (liquid and plastic limit, porosity, specific surface, pH, sediment electrical conductivity, P- and S-wave velocities and undrained shear strength). Available data from a pressure core are included as well. Results show that the sediments are high specific surface plastic clays, and exhibit pronounced time-dependent stiffness recovery. Strains during coring disturb specimens, yet, the water content retains the effective stress history and permits gaining stiffness and strength information from conventional cores. Remolding is exacerbated when gas expands upon decompression; the limited pressure core data available show the advantages of preserving the pore fluid pressure during core recovery and testing. Valuable parameters for sediment characterization and engineering analysis are extracted from the data using pre-existing soil models. (author)

  11. Geochemistry of the near surface sediments of the Nares Abyssal Plain

    International Nuclear Information System (INIS)

    Carpenter, M.S.N.; Colley, S.; Elderfield, H.; Kennedy, H.A.; Thomson, J.; Wilson, T.R.S.

    1983-01-01

    The geochemistry of a suite of box and 2m gravity cores from the Nares Abyssal Plain has been characterised by means of pore water analyses, XRF determination of major and trace element concentrations, mineralogy and 230 Thsub(excess) dating. The interstitial fluid environment of those deep-sea clays is mildly reducing, although one site exhibits manganese remobilisation and precipitation. Despite their marked colour differences, there is a similarity in clay mineralogy between the grey silt/clay turbidites and the brown clays found in the area. Sediment accumulation rates of pelagic brown clays range between 0.5 and 1.0 cm/10 3 yr. These pelagic brown clays are metal-rich relative to the grey clays, and a model is used to estimate the hydrogenous metal fluxes on the assumption that they are constant over the Plain. This model gives values of approx. 1300 μg/cm 2 /10 3 yr for Mn, approx. 2600 μg/cm 2 /10 3 yr for Fe and Co, Ni, Cu, V and Zn in the range 6 to 26 μg/cm 2 /10 3 yr. An associated model-derived estimate of the detrital contents of the same elements agrees well with the mean values of the grey clays and of average shale. Metal-poor brown clays and assorted minor lithologies are intermediate in composition between these two end-members. (author)

  12. I-cored Coil Probe Located Above a Conductive Plate with a Surface Hole

    Directory of Open Access Journals (Sweden)

    Tytko Grzegorz

    2018-02-01

    Full Text Available This work presents an axially symmetric mathematical model of an I-cored coil placed over a two-layered conductive material with a cylindrical surface hole. The problem was divided into regions for which the magnetic vector potential of a filamentary coil was established applying the truncated region eigenfunction expansion method. Then the final formula was developed to calculate impedance changes for a cylindrical coil with reference to both the air and to a material with no hole. The influence of a surface flaw in the conductive material on the components of coil impedance was examined. Calculations were made in Matlab for a hole with various radii and the results thereof were verified with the finite element method in COMSOL Multiphysics package. Very good consistency was achieved in all cases.

  13. Distribution of radionuclides in a marine sediment core off the waterspout of the nuclear power plants in Daya Bay, northeastern South China Sea.

    Science.gov (United States)

    Zhou, Peng; Li, Dongmei; Li, Haitao; Fang, Hongda; Huang, Chuguang; Zhang, Yusheng; Zhang, Hongbiao; Zhao, Li; Zhou, Junjie; Wang, Hua; Yang, Jie

    2015-07-01

    A sediment core was collected and dated using (210)Pbex dating method off the waterspout of nuclear power base of Daya Bay, northeastern South China Sea. The γ-emitting radionuclides were analyzed using HPGe γ spectrometry, gross alpha and beta radioactivity as well as other geochemical indicators were deliberated to assess the impact of nuclear power plants (NPP) operation and to study the past environment changes. It suggested that NPP provided no new radioactivity source to sediment based on the low specific activity of (137)Cs. Two broad peaks of TOC, TC and LOI accorded well with the commercial operations of Daya Bay NPP (1994.2 and 1994.5) and LNPP Phase I (2002.5 and 2003.3), implying that the mass input of cooling water from NPP may result into a substantial change in the ecological environment and Daya Bay has been severely impacted by human activities. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Aerobic biodegradation potential of endocrine disrupting chemicals in surface-water sediment at Rocky Mountains National Park, USA

    Science.gov (United States)

    Bradley, Paul M.; Battaglin, William A.; Iwanowicz, Luke R.; Clark, Jimmy M.; Journey, Celeste

    2016-01-01

    Endocrine disrupting chemicals (EDC) in surface water and bed sediment threaten the structure and function of aquatic ecosystems. In natural, remote, and protected surface-water environments where contaminant releases are sporadic, contaminant biodegradation is a fundamental driver of exposure concentration, timing, duration, and, thus, EDC ecological risk. Anthropogenic contaminants, including known and suspected EDC, were detected in surface water and sediment collected from 2 streams and 2 lakes in Rocky Mountains National Park (ROMO). The potential for aerobic EDC biodegradation was assessed in collected sediments using 6 14C-radiolabeled model compounds. Aerobic microbial mineralization of natural (estrone and 17β-estradiol) and synthetic (17α-ethinylestradiol) estrogen was significant at all sites. ROMO bed sediment microbial communities also effectively degraded the xenoestrogens, bisphenol-A and 4-nonylphenol. The same sediment samples exhibited little potential for aerobic biodegradation of triclocarban, however, illustrating the need to assess a wider range of contaminant compounds. The current results support recent concerns over the widespread environmental occurrence of carbanalide antibacterials, like triclocarban and triclosan, and suggest that backcountry use of products containing these compounds should be discouraged.

  15. Evaluation of Near-Surface Gases in Marine Sediments to Assess Subsurface Petroleum Gas Generation and Entrapment

    Directory of Open Access Journals (Sweden)

    Michael A. Abrams

    2017-05-01

    Full Text Available Gases contained within near-surface marine sediments can be derived from multiple sources: shallow microbial activity, thermal cracking of organic matter and inorganic materials, or magmatic-mantle degassing. Each origin will display a distinctive hydrocarbon and non-hydrocarbon composition as well as compound-specific isotope signature and thus the interpretation of origin should be relatively straightforward. Unfortunately, this is not always the case due to in situ microbial alteration, non-equilibrium phase partitioning, mixing, and fractionation related to the gas extraction method. Sediment gases can reside in the interstitial spaces, bound to mineral or organic surfaces and/or entrapped in carbonate inclusions. The interstitial sediment gases are contained within the sediment pore space, either dissolved in the pore waters (solute or as free (vapour gas. The bound gases are believed to be attached to organic and/or mineral surfaces, entrapped in structured water or entrapped in authigenic carbonate inclusions. The purpose of this paper is to provide a review of the gas types found within shallow marine sediments and examine issues related to gas sampling and extraction. In addition, the paper will discuss how to recognise mixing, alteration and fractionation issues to best interpret the seabed geochemical results and determine gas origin to assess subsurface petroleum gas generation and entrapment.

  16. Facile and green synthesis of core-shell structured magnetic chitosan submicrospheres and their surface functionalization.

    Science.gov (United States)

    Li, Yiya; Yuan, Dongying; Dong, Mingjie; Chai, Zhihua; Fu, Guoqi

    2013-09-17

    Submicrometer-sized magnetite colloid nanocrystal clusters (MCNCs) provide a new avenue for constructing uniformly sized and highly magnetic composite submicrospheres. Herein, a facile and eco-friendly method is described for the synthesis of Fe3O4@poly(acrylic acid) (PAA)/chitosan (CS) core-shell submicrospheres using MCNCs bearing carboxyl groups as the magnetic cores. It is based on the self-assembly of positively charged CS chains on the surface of the oppositely charged MCNCs dispersed in the aqueous solution containing acrylic acid (AA) and a cross-linker N,N'-methylenebis(acrylamide) (MBA), followed by radical induced cross-linking copolymerization of AA and MBA along the CS chains. The resulting polymer shell comprises a medium shell of cross-linked PAA/CS polyelectrolyte complexes and an outer shell of protonated CS chains. It was found that the shell thickness could be tuned by varying either the concentration of radical initiator or the molar ratio of AA to aminoglucoside units of CS. To the surface of thus obtained Fe3O4@PAA/CS particles, Au nanoparticles, a variety of functional groups such as fluorescein, carboxyl, quaternary ammonium, and aliphatic bromide, and even functional polymer chains were successfully introduced. Therefore, such Fe3O4@PAA/CS submicrospheres may be used as versatile magnetic functional scaffolds in biorelated areas like bioseparation and medical assay, considering the unique features of CS like nontoxicity and biocompatibility.

  17. Distribution and sources of organic matter in surface sediments of the eastern continental margin of India

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, M.S.; Naidu, S.A.; Subbaiah, Ch.V.; Sarma, V.V.S.S.; Reddy, N.P.C.

    productivity [IGBP, 1993; Carr, 2001] and high sedimentation rate. High biological production in coastal regions is due to availability of nutrients discharged by rivers. Transport of high suspended load through river discharge results in fast... sedimentation that support better accumulation of OM in coastal sediments [Ittekkot et al., 1991]. Recent estimates revealed that world rivers transport annually about 19 x 109 tons of suspended sediment to the ocean [Milliman and Farnsworth, 2010]. Coastal...

  18. Hydro-mechanical properties of pressure core sediments recovered from the Krishna-Godavari Basin during India's National Gas Hydrate Program Expedition NGHP-02

    Science.gov (United States)

    Yoneda, J.; Oshima, M.; Kida, M.; Kato, A.; Konno, Y.; Jin, Y.; Waite, W. F.; Jang, J.; Kumar, P.; Tenma, N.

    2017-12-01

    Pressure coring and analysis technology allows for gas hydrate to be recovered from the deep seabed, transferred to the laboratory and characterized while continuously maintaining gas hydrate stability. For this study, dozens of hydrate-bearing pressure core sediment subsections recovered from the Krishna-Godavari Basin during India's National Gas Hydrate Program Expedition NGHP-02 were tested with Pressure Core Non-destructive Analysis Tools (PNATs) through a collaboration between Japan and India. PNATs, originally developed by AIST as a part of the Japanese National hydrate research program (MH21, funded by METI) conducted permeability, compression and consolidation tests under various effective stress conditions, including the in situ stress state estimated from downhole bulk density measurements. At the in situ effective stress, gas hydrate-bearing sediments had an effective permeability range of 0.01-10mD even at pore-space hydrate saturations above 60%. Permeability increased by 10 to 100 times after hydrate dissociation at the same effective stress, but these post-dissociation gains were erased when effective stress was increased from in situ values ( 1 MPa) to 10MPa in a simulation of the depressurization method for methane extraction from hydrate. Vertical-to-horizontal permeability anisotropy was also investigated. First-ever multi-stage loading tests and strain-rate alternation compression tests were successfully conducted for evaluating sediment strengthening dependence on the rate and magnitude of effective confining stress changes. In addition, oedometer tests were performed up to 40MPa of consolidation stress to simulate the depressurization method in ultra-deep sea environments. Consolidation curves measured with and without gas hydrate were investigated over a wide range of effective confining stresses. Compression curves for gas hydrate-bearing sediments were convex downward due to high hydrate saturations. Consolidation tests show that

  19. SEA LEVEL AND PALAEOCLIMATIC CHANGES IN THE SOUTH AND MIDDLE CASPIAN SEA REGION SINCE THE LATEGLACIAL FROM PALYNOLOGICAL ANALYSES OF MARINE SEDIMENT CORES

    Directory of Open Access Journals (Sweden)

    Suzanne Leroy

    2010-01-01

    Full Text Available A review of pollen, spores, non-pollen palynomorphs and dinocyst analyses made in the last two decades is proposed here. Building on spare palynological analyses before 1990, a series of new projects have allowed taking cores in the deeper parts of the Caspian Sea, hence providing access to low-stand sediment. However, still nowadays no complete record exists for the Holocene. The first steps towards quantification of the palynological spectra have been taken. Some of the most urgent problems to solve are the uncertainties related to radiocarbon dating, which are especially acute in the Caspian Sea.

  20. 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.

  1. Dynamics of an Alfvén Surface in Core Collapse Supernovae

    Science.gov (United States)

    Guilet, Jérôme; Foglizzo, Thierry; Fromang, Sébastien

    2011-03-01

    We investigate the dynamics of an Alfvén surface (where the Alfvén speed equals the advection velocity) in the context of core collapse supernovae during the phase of accretion on the proto-neutron star. Such a surface should exist even for weak magnetic fields because the advection velocity decreases to zero at the center of the collapsing core. In this decelerated flow, Alfvén waves created by the standing accretion shock instability or convection accumulate and amplify while approaching the Alfvén surface. We study this amplification using one-dimensional MHD simulations with explicit physical dissipation (resistivity and viscosity). In the linear regime, the amplification continues until the Alfvén wavelength becomes as small as the dissipative scale. A pressure feedback that increases the pressure in the upstream flow is created via a nonlinear coupling. We derive analytic formulae for the maximum amplification and the nonlinear coupling and check them with numerical simulations to very good accuracy. Interestingly, these quantities diverge if the dissipation is decreased to zero, scaling as the square root of the Reynolds number, suggesting large effects in weakly dissipative flows. We also characterize the nonlinear saturation of this amplification when compression effects become important, leading to either a change of the velocity gradient, or a steepening of the Alfvén wave. Applying these results to core collapse supernovae shows that the amplification can be fast enough to affect the dynamics if the magnetic field is strong enough for the Alfvén surface to lie in the region of strong velocity gradient just above the neutrinosphere. This requires the presence of a strong magnetic field in the progenitor star, which would correspond to the formation of a magnetar under the assumption of magnetic flux conservation. An extrapolation of our analytic formula (taking into account the nonlinear saturation) suggests that the Alfvén wave could reach an

  2. Soil aggregate stability and size-selective sediment transport with surface runoff as affected by organic residue amendment.

    Science.gov (United States)

    Shi, Pu; Arter, Christian; Liu, Xingyu; Keller, Martin; Schulin, Rainer

    2017-12-31

    Aggregate breakdown influences the availability of soil particles for size-selective sediment transport with surface runoff during erosive rainfall events. Organic matter management is known to affect aggregate stability against breakdown, but little is known about how this translates into rainfall-induced aggregate fragmentation and sediment transport under field conditions. In this study, we performed field experiments in which artificial rainfall was applied after pre-wetting on three pairs of arable soil plots (1.5×0.75m) six weeks after incorporating a mixture of grass and wheat straw into the topsoil of one plot in each pair (OI treatment) but not on the other plot (NI treatment). Artificial rainfall was applied for approximately 2h on each pair at an intensity of 49.1mmh -1 . In both treatments, discharge and sediment concentration in the discharge were correlated and followed a similar temporal pattern after the onset of surface runoff: After a sharp increase at the beginning both approached a steady state. But the onset of runoff was more delayed on the OI plots, and the discharge and sediment concentration were in average only roughly half as high on the OI as on the NI plots. With increasing discharge the fraction of coarse sediment increased. This relationship did not differ between the two treatments. Thus, due to the lower discharge, the fraction of fine particles in the exported sediment was larger in the runoff from the OI plots than from the NI plots. The later runoff onset and lower discharge rate was related to a higher initial aggregate stability on the OI plots. Terrestrial laser scanning proved to be a very valuable method to map changes in the micro-topography of the soil surfaces. It revealed a much less profound decrease in surface roughness on the OI than on the NI plots. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Near surface velocity and Q S structure of the Quaternary sediment in Bohai basin, China

    Science.gov (United States)

    Chong, Jiajun; Ni, Sidao

    2009-10-01

    Heavily populated by Beijing and Tianjin cities, Bohai basin is a seismically active Cenozoic basin suffering from huge lost by devastating earthquakes, such as Tangshan earthquake. The attenuation ( Q P and Q S) of the surficial Quaternary sediment has not been studied at natural seismic frequency (1-10 Hz), which is crucial to earthquake hazards study. Borehole seismic records of micro earthquake provide us a good way to study the velocity and attenuation of the surficial structure (0-500 m). We found that there are two pulses well separated with simple waveforms on borehole seismic records from the 2006 M W4.9 Wen’an earthquake sequence. Then we performed waveform modeling with generalized ray theory (GRT) to confirm that the two pulses are direct wave and surface reflected wave, and found that the average ν P and ν S of the top 300 m in this region are about 1.8 km/s and 0.42 km/s, leading to high ν P/ ν S ratio of 4.3. We also modeled surface reflected wave with propagating matrix method to constrain Q S and the near surface velocity structure. Our modeling indicates that Q S is at least 30, or probably up to 100, much larger than the typically assumed extremely low Q (˜10), but consistent with Q S modeling in Mississippi embayment. Also, the velocity gradient just beneath the free surface (0-50 m) is very large and velocity increases gradually at larger depth. Our modeling demonstrates the importance of borehole seismic records in resolving shallow velocity and attenuation structure, and hence may help in earthquake hazard simulation.

  4. Carbon isotope heterogeneities in deep Earth: Recycling of surface carbon or from core?

    Science.gov (United States)

    Satish-Kumar, Madhusoodhan

    2017-04-01

    Subduction of crustal materials, mantle melting and upwelling of deep mantle, in addition to a potential source from the core, largely controls the Earth's deep carbon cycle. Large variations in carbon isotopic composition between different reservoirs have been used widely to differentiate the source of carbon and to understand the carbon inventories and its recycling processes. However, how far high-temperature and hign-pressure conditions can affect the carbon isotope distribution, is a question still unanswered to clearly address the deep carbon cycle. I present here a review on carbon isotope fractionation processes in deep Earth and critically evaluate whether we can easily differentiate between surface carbon and deep carbon based on isotope characteristics. Recent experimental carbon isotope fractionation studies in the Fe-C system suggests that light carbon is selectively partition into metallic core during early magma ocean environment (Satish-Kumar et al., 2011). Furthermore, carbonate melts can be a medium for efficient crystallisation of diamonds in Earth's mantle (Palyanov et al., 2013). Rayleigh fractionation modelling based on fractionation suggests that core can be a reservoir of 12C enriched carbon and can itself form a reservoir which can cause heterogeneity in mantle carbon (Wood et al., 2013). In addition, high pressure experiments in the carbon-saturated model harzburgite system (Enstatite-Magnesite-Olivine-Graphite), carbonated silicate melting resulted in 13C enrichment in the carbon dissolved in the silicate melt relative to elemental graphite (Mizutani et al., 2014). 13C enrichment in carbonate melt were further confirmed in experiments where redox melting between olivine and graphite produced a carbonate melt as well as carbonate reduction experiments to form graphite. A third factor, still unconquered is the effect of pressure on isotope fractionation process. Theoretical studies as well as preliminary experimental studies have suggested

  5. GPS based surface displacements – a proxy for discharge and sediment transport from the Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Hasholt, Bent; Khan, Shfaqat Abbas; Mikkelsen, Andreas Bech

    2014-01-01

    The elastic respond of the Earth’s surface to mass changes has been measured with Global Positioning System (GPS). Mass loss as accumulated runoff and sediment transport from a 10000 km2 segment of the Greenland Ice Sheet (GrIS) correlated very well (R2=0.83) with GPS measured uplift. Accumulated...

  6. The influence of salinity on Mg/Ca in planktic foraminifers - Evidence from cultures, core-top sediments and complementary δ18O

    Science.gov (United States)

    Hönisch, Bärbel; Allen, Katherine A.; Lea, David W.; Spero, Howard J.; Eggins, Stephen M.; Arbuszewski, Jennifer; deMenocal, Peter; Rosenthal, Yair; Russell, Ann D.; Elderfield, Henry

    2013-11-01

    The Mg/Ca ratio in foraminiferal calcite is one of the principal proxies used for paleoceanographic temperature reconstructions, but recent core-top sediment observations suggest that salinity may exert a significant secondary control on planktic foraminifers. This study compiles new and published laboratory culture experiment data from the planktic foraminifers Orbulina universa, Globigerinoides sacculifer and Globigerinoides ruber, in which salinity was varied but temperature, pH and light were held constant. Combining new data with results from previous culture studies yields a Mg/Ca-sensitivity to salinity of 4.4 ± 2.3%, 4.7 ± 1.2%, and 3.3 ± 1.7% per salinity unit (95% confidence), respectively, for the three foraminifer species studied here. Comparison of these sensitivities with core-top data suggests that the much larger sensitivity (27 ± 4% per salinity unit) derived from Atlantic core-top sediments in previous studies is not a direct effect of salinity. Rather, we suggest that the dissolution correction often applied to Mg/Ca data can lead to significant overestimation of temperatures. We are able to reconcile culture calibrations with core-top observations by combining evidence for seasonal occurrence and latitude-specific habitat depth preferences with corresponding variations in physico-chemical environmental parameters. Although both Mg/Ca and δ18O yield temperature estimates that fall within the bounds of hydrographic observations, discrepancies between the two proxies highlight unresolved challenges with the use of paired Mg/Ca and δ18O analyses to reconstruct paleo-salinity patterns across ocean basins. The first step towards resolving these challenges requires a better spatially and seasonally resolved δ18Osw archive than is currently available. Nonetheless, site-specific reconstructions of salinity change through time may be valid.

  7. Spatial Evaluation of Heavy Metals Concentrations in the Surface Sediment of Taihu Lake

    Science.gov (United States)

    Niu, Yong; Jiao, Wei; Yu, Hui; Niu, Yuan; Pang, Yong; Xu, Xiangyang; Guo, Xiaochun

    2015-01-01

    With regard to the size of China’s freshwater lakes, Taihu Lake ranks third and it plays an important role in the supply of drinking water, flood prevention, farming and navigation, as well as in the travelling industry. The problem of environmental pollution has attracted widespread attention in recent years. In order to understand the levels, distribution and sources of heavy metals in sediments of Taihu Lake, random selection was carried out to obtain 59 samples of surface sediment from the entire lake and study the concentrations of Pb, Cd, Cu, Zn, Cr and Ni. Toxic units were also calculated to normalize the toxicities caused by various heavy metals. As a result, Cd and Cu in sediment were considered lower than the effect range low (ERL) at all regions where samples were gathered, while Pb and Ni were categorized into ERL-effect range median (ERM) at over 22% of the regions where samples were obtained. Nevertheless, all average concentrations of the samples were below the level of potential effect. According to the findings of this research, significant spatial heterogeneity existed in the above heavy metals. In conclusion, the distribution areas of heavy metals with higher concentrations were mainly the north bays, namely Zhushan Bay, Meiliang Bay as well as Gonghu Bay. The distribution areas of Cu, Zn, Cr and Ni with higher concentration also included the lake’s central region, whereas the uniform distribution areas of those with lower concentrations were the lake’s southeast region. In addition, it was most probable that the spatial distribution of heavy metals was determined by river inputs, whereas atmospheric precipitation caused by urban and traffic contamination also exerted considerable effects on the higher concentrations of Pb and Cd. Through evaluating the total amount of toxic units (ΣTU), it was found that higher toxicity existed primarily in the north bays and central region of the lake. If the heavy metals were sorted by the reduction of

  8. Origins of terrestrial organic matter in surface sediments of the East China Sea shelf

    Science.gov (United States)

    Zhang, Hailong; Xing, Lei; Zhao, Meixun

    2017-10-01

    Terrestrial organic matter (TOM) is an important component of marine sedimentary OM, and revealing the origins and transport mechanisms of TOM to the East China Sea (ECS) is important for understanding regional carbon cycle. A novel approach combining molecular proxies and compound-specific carbon isotopes is used to quantitatively constrain the origins and transport mechanisms of TOM in surface sediments from the ECS shelf. The content of terrestrial biomarkers of (C27+C29+C31) n-alkanes (52 to 580 ng g-1) revealed a seaward decreasing trend, the δ13CTOC values (-20.6‰ to -22.7‰) were more negative near the coast, and the TMBR (terrestrial and marine biomarker ratio) values (0.06 to 0.40) also revealed a seaward decreasing trend. These proxies all indicated more TOM (up to 48%) deposition in the coastal areas. The Alkane Index, the ratio of C29/(C29+C31) n-alkanes indicated a higher proportion of grass vegetation in the coastal area; While the δ13C values of C29 n-alkane (-29.3‰ to -33.8‰) indicated that terrestrial plant in the sediments of the ECS shelf were mainly derived from C3 plants. Cluster analysis afforded detailed estimates of different-sourced TOM contributions and transport mechanisms. TOM in the Zhejiang-Fujian coastal area was mostly delivered by the Changjiang River, and characterized by higher %TOM (up to 48%), higher %C3 plant OM (68%-85%) and higher grass plant OM (56%-61%); TOM in the mid-shelf area was mostly transported by aerosols, and characterized by low %TOM (less than 17%), slightly lower C3 plant OM (56%-72%) and lower grass plant OM (49%-55%).

  9. Metal concentrations in surface water and sediments from Pardo River, Brazil: human health risks.

    Science.gov (United States)

    Alves, Renato I S; Sampaio, Carolina F; Nadal, Martí; Schuhmacher, Marta; Domingo, José L; Segura-Muñoz, Susana I

    2014-08-01

    Pardo River (Brazil) is suffering from an important anthropogenic impact due to the pressure of highly populated areas and the influence of sugarcane cultivation. The objective of the present study was to determine the levels of 13 trace elements (As, Be, Cd, Cr, Cu, Pb, Mn, Hg, Ni, Tl, Sn, V and Zn) in samples of surface water and sediments from the Pardo River. Furthermore, the human health risks associated with exposure to those metals through oral intake and dermal absorption were also evaluated. Spatial and seasonal trends of the data were closely analyzed from a probabilistic approach. Manganese showed the highest mean concentrations in both water and sediments, remarking the incidence of the agricultural activity and the geological characteristics within the basin. Thallium and arsenic were identified as two priority pollutants, being the most important contributors to the Hazard Index (HI). Since non-carcinogenic risks due to thallium exposure slightly exceeded international guidelines (HI>1), a special effort should be made on this trace element. However, the current concentrations of arsenic, a carcinogenic element, were in accordance to acceptable lifetime risks. Nowadays, there is a clear increasing growth in human population and economic activities in the Pardo River, whose waters have become a serious strategic alternative for the potential supply of drinking water. Therefore, environmental monitoring studies are required not only to assure that the current state of pollution of Pardo River does not mean a risk for the riverside population, but also to assess the potential trends in the environmental levels of those elements. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Near-surface Heating of Young Rift Sediment Causes Mass Production and Discharge of Reactive Dissolved Organic Matter

    Science.gov (United States)

    Lin, Yu-Shih; Koch, Boris P.; Feseker, Tomas; Ziervogel, Kai; Goldhammer, Tobias; Schmidt, Frauke; Witt, Matthias; Kellermann, Matthias Y.; Zabel, Matthias; Teske, Andreas; Hinrichs, Kai-Uwe

    2017-03-01

    Ocean margin sediments have been considered as important sources of dissolved organic carbon (DOC) to the deep ocean, yet the contribution from advective settings has just started to be acknowledged. Here we present evidence showing that near-surface heating of sediment in the Guaymas Basin, a young extensional depression, causes mass production and discharge of reactive dissolved organic matter (DOM). In the sediment heated up to ~100 °C, we found unexpectedly low DOC concentrations in the pore waters, reflecting the combined effect of thermal desorption and advective fluid flow. Heating experiments suggested DOC production to be a rapid, abiotic process with the DOC concentration increasing exponentially with temperature. The high proportions of total hydrolyzable amino acids and presence of chemical species affiliated with activated hydrocarbons, carbohydrates and peptides indicate high reactivity of the DOM. Model simulation suggests that at the local scale, near-surface heating of sediment creates short and massive DOC discharge events that elevate the bottom-water DOC concentration. Because of the heterogeneous distribution of high heat flow areas, the expulsion of reactive DOM is spotty at any given time. We conclude that hydrothermal heating of young rift sediments alter deep-ocean budgets of bioavailable DOM, creating organic-rich habitats for benthic life.

  11. Near-surface Heating of Young Rift Sediment Causes Mass Production and Discharge of Reactive Dissolved Organic Matter.

    Science.gov (United States)

    Lin, Yu-Shih; Koch, Boris P; Feseker, Tomas; Ziervogel, Kai; Goldhammer, Tobias; Schmidt, Frauke; Witt, Matthias; Kellermann, Matthias Y; Zabel, Matthias; Teske, Andreas; Hinrichs, Kai-Uwe

    2017-03-22

    Ocean margin sediments have been considered as important sources of dissolved organic carbon (DOC) to the deep ocean, yet the contribution from advective settings has just started to be acknowledged. Here we present evidence showing that near-surface heating of sediment in the Guaymas Basin, a young extensional depression, causes mass production and discharge of reactive dissolved organic matter (DOM). In the sediment heated up to ~100 °C, we found unexpectedly low DOC concentrations in the pore waters, reflecting the combined effect of thermal desorption and advective fluid flow. Heating experiments suggested DOC production to be a rapid, abiotic process with the DOC concentration increasing exponentially with temperature. The high proportions of total hydrolyzable amino acids and presence of chemical species affiliated with activated hydrocarbons, carbohydrates and peptides indicate high reactivity of the DOM. Model simulation suggests that at the local scale, near-surface heating of sediment creates short and massive DOC discharge events that elevate the bottom-water DOC concentration. Because of the heterogeneous distribution of high heat flow areas, the expulsion of reactive DOM is spotty at any given time. We conclude that hydrothermal heating of young rift sediments alter deep-ocean budgets of bioavailable DOM, creating organic-rich habitats for benthic life.

  12. Pollution, toxicity, and ecological risk of heavy metals in surface river sediments of a large basin undergoing rapid economic development.

    Science.gov (United States)

    Tang, Wenzhong; Zhang, Chao; Zhao, Yu; Shan, Baoqing; Song, Zhixin

    2017-05-01

    A comprehensive and detailed investigation of heavy metal pollution, toxicity, and ecological risk assessment was conducted for the surface river sediments of the Haihe Basin in China based on 220 sampling sites selected in 2013. The average concentrations of Cr, Cu, Ni, Pb, and Zn in the sediments were 129 mg/kg, 63.4 mg/kg, 36.6 mg/kg, 50.0 mg/kg, and 202 mg/kg, respectively. As indicated by the geoaccumulation and pollution load indices, most surface river sediments of the Haihe Basin were contaminated with the investigated metals, especially in the junction region of the Zi Ya He and Hei Long Gang watersheds. The 5 heavy metals in the sediments all had anthropogenic sources, and the enrichment degrees followed the order Cu > Pb > Zn > Cr > Ni, with mean enrichment factors of 3.27, 2.77, 2.58, 1.81, and 1.44, respectively. According to the mean index of comprehensive potential ecological risk (38.9), the studied sediments of the Haihe Basin showed low potential ecological risk, but the sediments were potentially biologically toxic based on the mean probable effect concentration quotient (0.547), which may be the result of speciation of the 5 metals in the sediments. The results indicate that heavy metal pollution should be considered during the development of ecological restoration strategies in the Haihe Basin. Environ Toxicol Chem 2017;36:1149-1155. © 2016 SETAC. © 2016 SETAC.

  13. Accumulation of Trace Metal Elements (Cu, Zn, Cd, and Pb in Surface Sediment via Decomposed Seagrass Leaves: A Mesocosm Experiment Using Zostera marina L.

    Directory of Open Access Journals (Sweden)

    Shinya Hosokawa

    Full Text Available Accumulation of Cu, Zn, Cd, and Pb in the sediment of seagrass ecosystems was examined using mesocosm experiments containing Zostera marina (eelgrass and reference pools. Lead was approximately 20-fold higher in the surface sediment in the eelgrass pool than in eelgrass leaves and epiphytes on the eelgrass leaves, whereas zinc and cadmium were significantly lower in the surface sediment than in the leaves, with intermediate concentrations in epiphytes. Copper concentrations were similar in both the surface sediment and leaves but significantly lower in epiphytes. Carbon and nitrogen contents increased significantly with increasing δ13C in surface sediments of both the eelgrass and reference pools. Copper, Zn, Cd, and Pb also increased significantly with increasing δ13C in the surface sediment in the eelgrass pool but not in the reference pool. By decomposition of eelgrass leaves with epiphytes, which was examined in the eelgrass pool, copper and lead concentrations increased more than 2-fold and approximately a 10-fold, whereas zinc and cadmium concentrations decreased. The high copper and lead concentrations in the surface sediment result from accumulation in decomposed, shed leaves, whereas zinc and cadmium remobilized from decomposed shed leaves but may remain at higher concentrations in the leaves than in the original sediments. The results of our mesocosm study demonstrate that whether the accumulation or remobilization of trace metals during the decomposition of seagrass leaves is trace metal dependent, and that the decomposed seagrass leaves can cause copper and lead accumulation in sediments in seagrass ecosystems.

  14. Pollution characteristics and ecological risk assessment of heavy metals in the surface sediments from a source water reservoir

    Directory of Open Access Journals (Sweden)

    Changming Yang

    2016-10-01

    Full Text Available Surface sediment samples were collected from a source water reservoir in Zhejiang Province, East of China to investigate pollution characteristics and potential ecological risk of heavy metals. The BCR sequential extraction method was used to determine the four chemical fractions of heavy metals such as acid soluble, easily reducible, easily oxidizable and residual fractions. The heavy metals pollution and potential ecological risk were evaluated systematically using geoaccumulation index (Igeo and Hakanson potential ecological risk index (H′. The results showed that the sampling sites from the estuaries of tributary flowing through downtowns and heavy industrial parks showed significantly (p < 0.05 higher average concentrations of heavy metals in the surface sediments, as compared to the other sampling sites. Chemical fractionation showed that Mn existed mainly in acid extractable fraction, Cu and Pb were mainly in reducible fraction, and As existed mainly in residual fraction in the surface sediments despite sampling sites. The sampling sites from the estuary of tributary flowing through downtown showed significantly (p < 0.05 higher proportions of acid extractable and reducible fractions than the other sampling sites, which would pose a potential toxic risk to aquatic organisms as well as a potential threat to drinking water safety. As, Pb, Ni and Cu were at relatively high potential ecological risk with high Igeo values for some sampling locations. Hakanson potential ecological risk index (H′ showed the surface sediments from the tributary estuaries with high population density and rapid industrial development showed significantly (p < 0.05 higher heavy metal pollution levels and potential ecological risk in the surface sediments, as compared to the other sampling sites.

  15. Characterization of the intragranular water regime within subsurface sediments: pore volume, surface area, and mass transfer limitations

    Science.gov (United States)

    Hay, Michael B.; Stoliker, Deborah L.; Davis, James A.; Zachara, John M.

    2011-01-01

    Although "intragranular" pore space within grain aggregates, grain fractures, and mineral surface coatings may contain a relatively small fraction of the total porosity within a porous medium, it often contains a significant fraction of the reactive surface area, and can thus strongly affect the transport of sorbing solutes. In this work, we demonstrate a batch experiment procedure using tritiated water as a high-resolution diffusive tracer to characterize the intragranular pore space. The method was tested using uranium-contaminated sediments from the vadose and capillary fringe zones beneath the former 300A process ponds at the Hanford site (Washington). Sediments were contacted with tracers in artificial groundwater, followed by a replacement of bulk solution with tracer-free groundwater and the monitoring of tracer release. From these data, intragranular pore volumes were calculated and mass transfer rates were quantified using a multirate first-order mass transfer model. Tritium-hydrogen exchange on surface hydroxyls was accounted for by conducting additional tracer experiments on sediment that was vacuum dried after reaction. The complementary ("wet" and "dry") techniques allowed for the simultaneous determination of intragranular porosity and surface area using tritium. The Hanford 300A samples exhibited intragranular pore volumes of ~1% of the solid volume and intragranular surface areas of ~20%–35% of the total surface area. Analogous experiments using bromide ion as a tracer yielded very different results, suggesting very little penetration of bromide into the intragranular porosity.

  16. Variation and significance of surface heat after the mechanical sand control of Qinghai–Tibet Railway was covered with sandy sediments

    Directory of Open Access Journals (Sweden)

    Shengbo Xie

    Full Text Available Mechanical control of drifting sand used to protect the Qinghai–Tibet Railway from sand damage inevitably results in sand deposition, and the change in radiation and heat flux after the ground surface is covered with sandy sediments remains unclear. These variations were studied in this work through field observations along with laboratory analyses and tests. After the ground surface was covered with sandy sediments produced by the mechanical control of sand in the Qinghai–Tibet Railway, the reflectivity increased, and the annual average reflectivity on the surface covered with sandy sediments was higher than that without sandy sediments, with the value increasing by 0.043. Moreover, the surface shortwave radiation increased, whereas the surface net radiation decreased. The annual average value of the surface shortwave radiant flux density on the sandy sediments was higher than that without sandy sediments, with the value increasing by 7.291 W·m−2. The annual average value of the surface net radiant flux density on the sandy sediments decreased by 9.639 W·m−2 compared with that without sandy sediments. The soil heat flux also decreased, and the annual average value of the heat flux in the sandy sediments decreased by 0.375 W·m−2 compared with that without sandy sediments. These variations caused the heat source on the surface of sandy sediments underground to decrease, which is beneficial for preventing permafrost from degradation in the section of sand control of the railway. Keywords: Mechanical control of sand, Sand depositions, Surface radiation, Heat flux, Qinghai–Tibet Railway

  17. [Speciation and Risk Assessment of Heavy Metals in Surface Sediments from the Heavily Polluted Area of Xiaoqing River].

    Science.gov (United States)

    Huang, Ying; Li, Yong-xia; Gao, Fu-wei; Xu, Min-min; Sun, Bo; Wang, Ning; Yang, Jian

    2015-06-01

    Th concentrations of Cu, As, Pb, Zn, Cr, Cd, Ni in interstitial water were analyzed by ICP-MS from the heavily polluted area of Xiaoqing River. A modified BCR's sequential extraction procedure was used to investigate the fraction of the heavy metals in the surface sediments. The aquatic toxicity of heavy metals in interstitial water was assessed by US Water Quality Criteria (CCC, CMC). Based on the speciation of the metals in the surface sediments, the ecological risk of heavy metals was assessed with methods of risk assessment code (RAC) and potential ecological risk index. The results showed that: The tested heavy metals would not pose chronic toxicity for aquatic ecosystem. The contents of heavy metals (Cu, Pb, Zn, Cr, Cd, Ni) in the surface sediments were higher than the background values of the local soils, indicating enrichment of heavy metals. Cu, As and Ni were mainly composed with residual fractions, Pb and Cr were mainly constituted of residual and oxidizable fra