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Sample records for bay sediments chile

  1. Sulfur transformations in early diagenetic sediments from the Bay of Concepcion, off Chile

    Energy Technology Data Exchange (ETDEWEB)

    Vairavamurth, M.A.; Wang, Shengke; Khandelwal, B.; Manowitz, B. [Brookhaven National Lab., Upton, NY (United States); Ferdelman, T.; Fossing, H. [Max Plank Institute for Marine Microbiology, Bremen (Germany). Dept. of Biogeochemistry

    1995-04-01

    Despite the recognition that both organic sulfur and pyrite form during the very early stages of diagenesis, and that the amount of H{sub 2}S generated in bacterial sulfate reduction primarily limits their formation, the mechanisms and the active species involved still are not clear. In this study, we quantified the major forms of sulfur distributed in sediments to assess the geochemical mechanisms involved in these transformations. XANES spectroscopy, together with elemental analysis, were used to measure sulfur speciation in the organic-rich sediments from the Bay of Concepcion, Chile. Organic polysulfides constituted the major fraction of the organic sulfur, and occurred maximally just below the sediment surface (1--3 cm), where intermediates from H{sub 2}S oxidation were likely to be generated most abundantly. Sulfonates, which could be formed through the reactions of sulfate and thiosulfate, also showed a sub-surface maximum in the vicinity of the ``oxic-anoxic interface``. These results strongly suggest a geochemical origin for organic polysulfides and sulfonates, and illustrate that intermediates from H{sub 2}S oxidation play a dominant role in incorporating sulfur into organic matter. Pyrite was absent in the surficial layer, and first appeared just below the H{sub 2}S maximum, where organic polysulfides began to decrease in abundance. From these results, we argue, that an iron monosulfide precursor formed first from reactions with H{sub 2}S, and then reacts with organic polysulfides, completing the synthesis of pyrite in the sediment column.

  2. 238U removal and accumulation in Concepción bay sediments, Chile

    Directory of Open Access Journals (Sweden)

    Laura Farías

    2000-12-01

    Full Text Available Activity profiles of 234U, 238U and 210Pb, as well as the 234U/238U ratio, and 210Pb xs radiochemical parameters and macrobenthic abundance in sediments were measured and calculated at different times during a year (1991, along a transect between the head and the mouth of Concepción Bay, Chile. This bay is a semi-enclosed shallow embayment with a strong seasonality in its hydrographic and biological characteristics due to wind driven upwelling. Upwelling of oxygen-poor and nutrient-rich water occurs and organic detritus reaches the seabed, creating a sub-oxic and anoxic environment during, at least, 57% of the year. 238U and 234U activities in the sediments show a gradual increase from 1.57 to 6.07 dpm g-1 from the surface to 15 cm depth in the sediments. Under suboxic-anoxic conditions, this pattern is consistent with a reduction of U(VI to U(IV and its subsequent removal from pore-water. A 234U/238U ratio of 1.10 ±0.08 indicates an authigenic origen. The 238U accumulation rate and inventory show a significant increase from Station 1 (head of the bay to Station 3 (mouth of the bay from 348 to 794 dpm cm-2 kyr-1 and of 14 to 32 dpm cm-2, respectively. The organic-rich and highly reducing sediments also show an increase in sulphate-reduction rates, sulfur speciation and bioturbation activities of macrobenthos. These patterns suggest that the extent of U enrichment in these sediments is regulated by bacterial sulphate reduction rate and bioturbation and bioirrigation activities. The estimated 238U accumulation rates are higher than those reported for other anoxic environments, representing an important U sink in marine sediments. The geochemical behaviour of U seems to be very sensitive to the redox condition and this characteristic could become an important paleoceanographic tool to identify changes in oceanographic conditions during the last millenniumRemoción y acumulación de 328U en los sedimentos de la bahía de Concepción, Chile. Las

  3. Delaware River and Upper Bay Sediment Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The area of coverage consists of 192 square miles of benthic habitat mapped from 2005 to 2007 in the Delaware River and Upper Delaware Bay. The bottom sediment map...

  4. Concentración de metales pesados (Cu, Ni, Zn, Cd, Pb en la biota y sedimentos de una playa artificial, en la bahía San Jorge 23°S, norte de Chile Heavy metals concentration (Cu, Ni, Zn, Cd, Pb, in biota and sediments of an artificial beach, in San Jorge bay 23°S, northern Chile

    Directory of Open Access Journals (Sweden)

    Gabriel Castro

    2012-07-01

    Full Text Available Se evaluó el contenido de metales pesados (Cu, Ni, Zn, Cd, Pb en la biota y el sedimento de una playa artificial (Paraíso y una playa natural (El Lenguado, ubicadas en la bahía San Jorge, norte de Chile. Los resultados fueron utilizados para comparar ambos sistemas, el grado de cumplimiento de la normativa ambiental nacional e internacional, y el efecto de la construcción de la playa artificial sobre el nivel de contaminación por metales existentes históricamente en esa zona. En cada playa se ubicaron estaciones equidistantes que abarcaron desde el intermareal hasta el submareal de las cuales fueron extraídos los organismos. Se tomaron muestras de sedimento en cada playa y se determinaron las pendientes con el método de Emery. El análisis granulométrico evidenció el predominio de arena media en playa El Lenguado, y arena media y fina en playa Paraíso. El contenido de materia orgánica fue mayor en El Lenguado. En playa Paraíso se determinaron cinco phylum/superclase agrupados en 19 taxa, mientras que en El Lenguado se encontraron cuatro phylum/superclase agrupados en cc taxa. El contenido de metales en sedimentos y en la mayoría de organismos presentó valores mayores en playa Paraíso. Estos resultados, junto a las normas de calidad chilenas y norteamericanas, sugieren un evidente deterioro en la calidad ambiental de playa Paraíso lo que se demostró por un incremento en las concentraciones de estos metales desde su construcción, los que sobrepasan los límites establecidos por ambas normas.It was evaluated the heavy metal content (Cu, Ni, Zn, Cd, Pb in biota and sediment of an artificial beach (Paraíso and a natural beach (El Lenguado, both located in San Jorge bay, northern Chile. The results were used to compare both systems, the degree of fulfillment of national and international environmental regulations, and the effect of the construction of the artificial beach on the level of metal contamination historically existing in

  5. REE enrichment in Havana Bay surface sediments using INAA

    International Nuclear Information System (INIS)

    Rare earth elements (REE) levels in Havana bay surface sediments are determined by instrumental neutron activation analysis. REE contents follow the order: Ce > La > Nd > Sm > Eu, Yb, Tb, Lu. The results shows that REE content in the bay is site depended and suggest that an REE anthropogenic input into the bay occurred. The chondrite and upper continental crust-normalizations confirm the REE enrichment of the bay sediments, respect to the REE content in sediments from the Cuban northwestern coast. (author)

  6. Sediments detection at the Havana Bay

    International Nuclear Information System (INIS)

    The study of sedimentation rates and age of marine sediments has been performed through many years using natural and artificial radioactive isotopes. The previously topics have been studied in polluted sediments at the Havana Bay collected in three sampling points. Spectrometric measurements have been carried for determining concentration of the isotope radioactive gamma emitters, 210 Pb and 226 Ra to mainly utilized the Constant Initial Concentration Method and the Constant Rate of Supply Method Dating Models based upon the unsupported 210 Pb. The obtained results show values for sedimentation rate ranging from 0.2 up to 1.3 cm.y-1 increasing with time which manifest the importance of the achievement of a project of dredging. (author)

  7. Microbial biogeography of San Francisco Bay sediments

    Science.gov (United States)

    Lee, J. A.; Francis, C. A.

    2014-12-01

    The largest estuary on the west coast of North America, San Francisco Bay is an ecosystem of enormous biodiversity, and also enormous human impact. The benthos has experienced dredging, occupation by invasive species, and over a century of sediment input as a result of hydraulic mining. Although the Bay's great cultural and ecological importance has inspired numerous surveys of the benthic macrofauna, to date there has been almost no investigation of the microbial communities on the Bay floor. An understanding of those microbial communities would contribute significantly to our understanding of both the biogeochemical processes (which are driven by the microbiota) and the physical processes (which contribute to microbial distributions) in the Bay. Here, we present the first broad survey of bacterial and archaeal taxa in the sediments of the San Francisco Bay. We conducted 16S rRNA community sequencing of bacteria and archaea in sediment samples taken bimonthly for one year, from five sites spanning the salinity gradient between Suisun and Central Bay, in order to capture the effect of both spatial and temporal environmental variation on microbial diversity. From the same samples we also conducted deep sequencing of a nitrogen-cycling functional gene, nirS, allowing an assessment of evolutionary diversity at a much finer taxonomic scale within an important and widespread functional group of bacteria. We paired these sequencing projects with extensive geochemical metadata as well as information about macrofaunal distribution. Our data reveal a diversity of distinct biogeographical patterns among different taxa: clades ubiquitous across sites; clades that respond to measurable environmental drivers; and clades that show geographical site-specificity. These community datasets allow us to test the hypothesis that salinity is a major driver of both overall microbial community structure and community structure of the denitrifying bacteria specifically; and to assess

  8. Distribution and behavior of major and trace elements in Tokyo Bay, Mutsu Bay and Funka Bay marine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Honda, Teruyuki [Musashi Inst. of Technology, Atomic Energy Research Laboratory, Kawasaki, Kanagawa (Japan); Kimura, Ken-ichiro [Musashi Inst. of Technology, Graduate School, Research Division in Engineering, Kawasaki, Kanagawa (Japan)

    2003-06-01

    Fourteen major and trace elements in marine sediment core samples collected from the coasts along eastern Japan, i.e. Tokyo Bay (II) (the recess), Tokyo Bay (IV) (the mouth), Mutsu Bay and Funka Bay and the Northwest Pacific basin as a comparative subject were determined by the instrumental neutron activation analysis (INAA). The sedimentation rates and sedimentary ages were calculated for the coastal sediment cores by the {sup 210}Pb method. The results obtained in this study are summarized as follows: (1) Lanthanoid abundance patterns suggested that the major origin of the sediments was terrigenous material. La*/Lu* and Ce*/La* ratios revealed that the sediments from Tokyo Bay (II) and Mutsu Bay more directly reflected the contribution from river than those of other regions. In addition, the Th/Sc ratio indicated that the coastal sediments mainly originated in the materials from the volcanic island-arcs, Japanese islands, whereas those from the Northwest Pacific mainly from the continent. (2) The correlation between the Ce/U and Th/U ratios with high correlation coefficients of 0.920 to 0.991 indicated that all the sediments from Tokyo Bay (II) and Funka Bay were in reducing conditions while at least the upper sediments from Tokyo Bay (IV) and Mutsu Bay were in oxidizing conditions. (3) It became quite obvious that the sedimentation mechanism and the sedimentation environment at Tokyo Bay (II) was different from those at Tokyo Bay (IV), since the sedimentation rate at Tokyo Bay (II) was approximately twice as large as that at Tokyo Bay (IV). The sedimentary age of the 5th layer (8{approx}10 cm in depth) from Funka Bay was calculated at approximately 1940{approx}50, which agreed with the time, 1943{approx}45 when Showa-shinzan was formed by the eruption of the Usu volcano. (author)

  9. Characterization of Dredged Sediments from Santander Bay

    International Nuclear Information System (INIS)

    The purpose of this study is the physico- chemical characterisation of Santander Bay (North Spain) inter-tidal sediments, with the determination of levels of selected organic compounds pollution. A sampling strategy has been developed based on characteristic parameters of the study. The physico-chemical seasonal characterisation of sediments has been performed by determination of waster content, Ph, density, humidity, lost on ignition (LOI), particle size distribution, and chemical analysis of three categories of organic compounds (VOCs,EOX and PAHs) selected for its ubiquity, persistence and high potential of environmental hazard. The EOX analysis give a picture of the total load of organo halogen compounds in the estuarine area and the VOC and ph values obtained, allow the characterization of sediments in two areas in function of the closeness to the urban and industrial activities

  10. Oxygenation variability in Mejillones Bay, off northern Chile, during the last two centuries

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    J. A. Díaz-Ochoa

    2011-01-01

    Full Text Available The Peru Chile Current ecosystem is characterized by high biological productivity and important fisheries. Although this system is likely to be severely affected by climate change, its response to current global warming is still uncertain. In this paper, we analyze 10–166 year-old sediments in two cores collected from Mejillones Bay, an anoxic sedimentary setting favorable for the preservation of proxies. Based on a 166-year chronology, we used proxies of bottom-water oxygenation (Mo, V, S, and the (lycopane + n−C35/n−C31 ratio and surface water productivity (biogenic opal, counts of diatom valves, biogenic Ba, organic carbon, and chlorins to reconstruct environmental variations in Mejillones Bay. During the last two centuries, a shift took place in the coastal marine ecosystem of Bahia Mejillones at decadal scales. This shift was characterized by intense ENSO-like activity, large-scale fluctuations in biological export productivity and bottom water oxygenation, and increased eolian activity (inferred from Ti/Al and Zr/Al. This short-term variability was accompanied by a gradual increase of sulfidic conditions that has intensified since the early 1960s.

  11. Humic Substances from Manila Bay and Bolinao Bay Sediments

    OpenAIRE

    Elma Llaguno

    1997-01-01

    The C,H,N composition of sedimentary humic acids (HA) extracted from three sites in Manila Bay and six sites in Bolinao Bay yielded H/C atomic ratios of 1.1-1.4 and N/C atomic ratios of 0.09 - 0.16. The Manila Bay HA's had lower H/C and N/C ratios compared to those from Bolinao Bay. The IR spectra showed prominent aliphatic C-H and amide I and II bands. Manila Bay HA's also had less diverse molecular composition based on the GC-MS analysis of the CuO and alkaline permanganate oxidation produc...

  12. Humic substances from Manila Bay and Bolinao Bay sediments

    International Nuclear Information System (INIS)

    The C, H, N composition of sedimentary humic acids (HA) extracted from three sites in Manila Bay and six sites in Bolinao Bay yielded H/C atomic ratios of 1.1-1.4 and N/C atomic ratios of 0.09-0.16. The Manila Bay HA's had lower H/C and C/C ratios compared to those from Bolinao Bay. The IR spectra showed prominent aliphatic C-H amide I and II bands. Manila Bay HA's also had less diverse molecular composition based on the GC-MS analysis of the CuO and alkaline permanganate oxidation products of the humic acids. (Author)

  13. River sediment supply, sedimentation and transport of the highly turbid sediment plume in Malindi Bay, Kenya

    Institute of Scientific and Technical Information of China (English)

    JOHNSON U.Kitheka

    2013-01-01

    The paper presents results of a study on the sediment supply and movement of highly turbid sediment plume within Malindi Bay in the Northern region of the Kenya coast.The current velocities,tidal elevation,salinity and suspended sediment concentrations (TSSC)were measured in stations located within the bay using Aanderaa Recording Current Meter (RCM-9),Turbidity Sensor mounted on RCM-9,Divers Gauges and Aanderaa Temperature-Salinity Meter.The study established that Malindi Bay receives a high terrigenous sediment load amounting to 5.7 × 106 ton·yr-1.The river freshwater supply into the bay is highly variable ranging from 7 to 680 m3·s-1.The high flows that are > 150 m3·s-1 occurred in May during the South East Monsoon (SEM).Relatively low peak flows occurred in November during the North East Monsoon (NEM) but these were usually <70 m3·s-1.The discharge of highly turbidity river water into the bay in April and May occurs in a period of high intensity SEM winds that generate strong north flowing current that transports the river sediment plume northward.However,during the NEM,the river supply of turbid water is relatively low occurring in a period of relatively low intensity NEM winds that result in relatively weaker south flowing current that transports the sediment plume southward.The mechanism of advection of the sediment plume north or south of the estuary is mainly thought to be due to the Ekman transport generated by the onshore monsoon winds.Limited movement of the river sediment plume southward towards Ras Vasco Da Gama during NEM has ensured that the coral reef ecosystem in the northern parts of Malindi Marine National Park has not been completely destroyed by the influx of terrigenous sediments.However,to the north there is no coral reef ecosystem.The high sediment discharge into Malindi Bay can be attributed to land use change in the Athi-Sabaki River Basin in addition to rapid population increase which has led to clearance of forests to open land

  14. Sediments of Cape Cod Bay, Massachusetts (HOUGH42 shapefile)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Cape Cod Bay, lying on the Massachusetts coast partly enclosed by Cape Cod, is in a glaciated region of low relief. Coarse sediments generally occur in areas...

  15. Sediment Thickness--Pigeon Point to South Monterey Bay, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the sediment-thickness map of the Pigeon Point to South Monterey Bay, California, region. The raster data file is included in...

  16. Delaware Bay, Delaware Sediment Distribution 2003 to 2004

    Data.gov (United States)

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

  17. Composición elemental y contenido de metales en sedimentos marinos de la bahía Mejillones del Sur, Chile: evaluación ambiental de la zona costera Elemental composition and metal contents in the marine sediments of Mejillones del Sur Bay, Chile: an environmental assessment of the coastal zone

    Directory of Open Access Journals (Sweden)

    Jorge Valdés

    2009-01-01

    Full Text Available Se midió la concentración de carbono total, nitrógeno total, azufre total, materia orgánica, Ni, Cd, Pb, Cu y Zn en sedimentos costeros (10 m de profundidad de columna de agua de ocho sectores de la bahía Mejillones. La composición elemental de los sedimentos sería el resultado de la abundante materia orgánica autóctona presente en este sistema costero. El orden de abundancia de los metales analizados fue: Zn > Cu > Ni > Pb > Cd. La concentración de metales no se explicaría por el contenido de materia orgánica ni la composición granulométrica de los sedimentos costeros. La evaluación del contenido de metales en los sedimentos, mostró que el Ni, Zn y Pb estarían levemente enriquecidos en la actualidad, aún cuando los valores se mantienen dentro de un rango cercano a los niveles preindustriales. El análisis del dendrograma de similitud de los sectores de estudio separó la línea de costa de Mejillones en dos grandes zonas; una asociada a la actividad industrial desarrollada en la bahía, y otra correspondiente al área de desarrollo urbano de Mejillones con características similares a aquellos ambientes libres de actividad antrópica directa.The total carbon, total nitrogen, total sulphur, organic matter, Ni, Cd, Pb, Cu, and Zn concentrations were measured in coastal sediments (10 m water depth at eight stations in Mejillones Bay. The elemental composition of these sediments is a function of the autochthonous organic matter generated in this coastal system. The order of abundance for the metals was: Zn > Cu > Ni > Pb > Cd. The metal content is not explained by the organic matter content or grain size of these coastal sediments. The evaluation of the concentration metals in the sediments showed that Ni, Zn, and Pb are slightly enriched at the present, although with values that are similar to preindustrial concentrations. A cluster analysis of the similarity in the study area separated the Mejillones coast into two main zones

  18. Humic Substances from Manila Bay and Bolinao Bay Sediments

    Directory of Open Access Journals (Sweden)

    Elma Llaguno

    1997-12-01

    Full Text Available The C,H,N composition of sedimentary humic acids (HA extracted from three sites in Manila Bay and six sites in Bolinao Bay yielded H/C atomic ratios of 1.1-1.4 and N/C atomic ratios of 0.09 - 0.16. The Manila Bay HA's had lower H/C and N/C ratios compared to those from Bolinao Bay. The IR spectra showed prominent aliphatic C-H and amide I and II bands. Manila Bay HA's also had less diverse molecular composition based on the GC-MS analysis of the CuO and alkaline permanganate oxidation products of the humic acids.

  19. Coastal Upwelling off Chile: Ocean Productivity and Surface Sediments

    Science.gov (United States)

    Hebbeln, D.; Lamy, F.

    2002-12-01

    The coastal upwelling system of the Peru-Chile Current belongs to the most productive regions in the world oceans. In spite of this fact only very little is known about the sediment distribution in its southern part off the coast of Chile. To increase the knowledge about this region a multi-parameter study of the surface sediment distribution at over 100 sampling sites along the Chilean continental slope between 23°S and 45°S has been carried out. Detailed analyses of sedimentary data (TOC, carbonate, and biogenic opal contents, delta 15N) reveal a close relation to environmental conditions in the region. Coastal upwelling along the Chilean coast, centered around main upwelling centers such as off Antofagasta (23°S), off Lengua de Vaca (30°S), off Valparaiso (33°S), and off Concepci¢n (35-38°S), sustains the high productivity observed in satellite pigment data and in sediment data. However, the highest pigment concentrations are found south of 40°S where prevailing onshore winds of the Southern Westerlies generally prevent coastal upwelling. There, also highest estimated accumulation rates of organic carbon and biogenic opal at the sea floor are found. Thus, the general pattern of a southward increase of surface water productivity known from satellite data is closely reflected in the organic carbon, biogenic opal and ?15N data, although the observation of highest productivity south of the upwelling area is surprising. Probably, this high productivity in the south can be attributed to the advection of (macro-) nutrients by the Antarctic Circumpolar Current, supplying so-called high nutrient-low chlorophyll (HNLC) waters to the Chilean margin. Impinging on the Chilean margin these waters can take up micronutrients such as iron from the strong riverine input and from benthic exchange processes. The combination of macro- and micro-nutrients in this area most likely results in the high productivity of the area between 40°S and 45°S. From there these fertile

  20. Conowingo Reservoir Sedimentation and Chesapeake Bay: State of the Science.

    Science.gov (United States)

    Cerco, Carl F

    2016-05-01

    The Conowingo Reservoir is situated on the Susquehanna River, immediately upstream of Chesapeake Bay, the largest estuary in the United States. Sedimentation in the reservoir provides an unintended benefit to the bay by preventing sediments, organic matter, and nutrients from entering the bay. The sediment storage capacity of the reservoir is nearly exhausted, however, and the resulting increase in loading of sediments and associated materials is a potential threat to Chesapeake Bay water quality. In response to this threat, the Lower Susquehanna River Watershed Assessment was conducted. The assessment indicates the reservoir is in a state of "dynamic equilibrium" in which sediment loads from the upstream watershed to the reservoir are balanced by sediments leaving the reservoir. Increased sediment loads are not a threat to bay water quality. Increased loads of associated organic matter and nutrients are, however, detrimental. Bottom-water dissolved oxygen declines of 0.1 to 0.2 g m are projected as a result of organic matter oxidation and enhanced eutrophication. The decline is small relative to normal variations but results in violations of standards enforced in a recently enacted total maximum daily load. Enhanced reductions in nutrient loads from the watershed are recommended to offset the decline in water quality caused by diminished retention in the reservoir. The assessment exposed several knowledge gaps that require additional investigation, including the potential for increased loading at flows below the threshold for reservoir scour and the nature and reactivity of organic matter and nutrients scoured from the reservoir bottom. PMID:27136154

  1. Sediment environmental capacity of 137Cs in Daya Bay

    Institute of Scientific and Technical Information of China (English)

    ZHANG Junli; CHEN Jiajun; XU Jialin; LI Yuanxin; HUANG Naiming

    2007-01-01

    Sediment environmental capacity of pollutants is very important for marine environmental management.Based on the methodology of a study on water,soil environmental capacity,and mass conservation theory in a system,the concept and model on sediment environmental capacity for 137Cs in Daya Bay were developed.The static capacity for 137Cs in the upper sediment near the shore at a shallow area was calculated,and the annual dynamic capacity and total dynamic capacity were also calculated through determination of the typical biomass in the sediment.The results showed that the estimated environmental capacity for 137Cs in sediments was approximately equal to the current input of 137Cs into the sediments.Controlling the input of 137Cs in the sediments within the environmental capacity guarantees the sustainability of the current situation of the Daya Bay ecosystem and avoidance of a significant degradation of the system.

  2. Prokaryotic community composition involved production of nitrogen in sediments of Mejillones Bay

    International Nuclear Information System (INIS)

    Conventional denitrification and anaerobic ammonium oxidation (anammox) contributes to nitrogen loss in oxygen-deficient systems, thereby influencing many aspects of ecosystem function and global biogeochemistry. Mejillones Bay, northern Chile, presents ideal conditions to study nitrogen removal processes, because it is inserted in a coastal upwelling system, its sediments have anoxia and hypoxia conditions and under the influence of the Oxygen Minimum Zone (OMZ), unknown processes that occur there and what are the microbial communities responsible for their removal. Microbial communities associated with coastal sediments of Mejillones Bay were studied by denaturing gel electrophoresis (DGGE) and fluorescence in situ hybridization (FISH), by incubation experiments with 15N isotope tracers were studied nitrogen loss processes operating in these sediments. DGGE analysis showed high bacterial diversity, certain redundant phylotypes and differences in community structure given by the depth; this reflects the microbial community adaptations to environmental conditions. A large fraction (up to 70%) of DAPI-stained cells hybridized with the bacterial probes. Nearly 52-90% of the cell could be further identified to know phyla. Members of the Cytophaga-Flavobacterium cluster were most abundant in the sediments (13-26%), followed by Proteobacteria. Isotopic tracer experiments for the sediments studied indicated that nitrogen loss processes that predominated were performed by denitrifying communities (43.31-111.20 μMd-1) was not possible to detect anammox in the area and not anammox bacteria were detected

  3. Heavy Metal Pollution Evolution in Sediments from Urdaibai Bay (Spain)

    International Nuclear Information System (INIS)

    Full Text: The Urdaibai bay is a biosphere reservoir located in the north of Spain. The mayor components of bay sediments come from marls and clays eroded which are deposited together with metallic pollutants present in water, air and rain. For this reason it is possible to study the temporal evolution of the bay pollution by measuring the heavy metal concentrations in the sediments and considering the correspondence with its age. To this aim, sediments cores were taken in two different points of the Urdaibai bay. The cores were cut into 1 cm thick horizontal sections. Sediment dating was performed using a low background gamma spectrometry with GeHP to determine Cs-137, Ra-226 and Pb-210 activities and applying the CIC and CRS models. The heavy metal concentrations in sediments were determined by ICP-MS. The obtained results in one of the studied positions show an increment of the Pb, Zn, Ni, Cu and Cr concentrations in the first 10 cm of the sediment core. This fact can be related to an increase of the bay pollution in the last 100 years. In the second studied core the heavy metal concentrations are constant in depth or lower in the superficial layers. This could be due to an increment the deposition rate of eroded material

  4. Oxygenation variability in Mejillones Bay, off northern Chile, during the last two centuries

    NARCIS (Netherlands)

    Diaz-Ochoa, J.A.; Pantoja, S.; de Lange, G.J.; Lange, C.B.; Sanchez, G.E.; Acuna, V.R.; Munoz, P.; Vargas, G.

    2011-01-01

    The Peru Chile Current ecosystem is characterized by high biological productivity and important fisheries. Although this system is likely to be severely affected by climate change, its response to current global warming is still uncertain. In this paper, we analyze 10–166 year-old sediments in two c

  5. Aromatic hydrocarbon concentrations in sediments of Placentia Bay, Newfoundland

    International Nuclear Information System (INIS)

    A study was conducted to examine the potential for contamination of recent sediments with polycyclic aromatic hydrocarbons due to tanker and refinery activity in Placentia Bay, Newfoundland, an area without large local anthropogenic sources of aromatics. Sediment samples were taken from the vicinity of the Come By Chance refinery, Woody Island, Wild Cove, and Port Royal Arm, all in the north end of the bay. The samples were extracted by two methods, dichloromethane extraction of dried sediment for determination of total aromatic hydrocarbon content and hexane extraction of wet sediment for estimation of the bioavailability of hydrocarbons and determination of more volatile compounds. Class analysis of aromatic hydrocarbons was conducted on a NH2 column with detection at 255 nm. Total concentrations of di-tricyclic aromatics were highest at the Woody Island site (0.6 μg/g). The sediments from the Come By Chance site, Wild Cove, and Port Royal Arm sediments contained 0.3, 0.1, and 0.2 μg/g respectively. The hexane extracts from Come By Chance were lowest in di-tricyclic aromatics (0.007 μg/g), with the other sites being equal in concentration (0.01 μg/g). It is evident from the study that aromatic hydrocarbon concentrations in Placentia Bay are elevated in some parts of the bay in the absence of local combustion sources, and that the most likely source is petroleum. 12 refs., 5 figs., 2 tabs

  6. Organic matter remineralization predominates phosphorus cycling in the mid-Bay sediments in the Chesapeake Bay.

    Science.gov (United States)

    Joshi, Sunendra R; Kukkadapu, Ravi K; Burdige, David J; Bowden, Mark E; Sparks, Donald L; Jaisi, Deb P

    2015-05-19

    Chesapeake Bay, the largest and most productive estuary in the U.S., suffers from varying degrees of water quality issues fueled by both point and nonpoint nutrient sources. Restoration of the Bay is complicated by the multitude of nutrient sources, their variable inputs, and complex interaction between imported and regenerated nutrients. These complexities not only restrict formulation of effective restoration plans but also open up debates on accountability issues with nutrient loading. A detailed understanding of sediment phosphorus (P) dynamics provides information useful in identifying the exchange of dissolved constituents across the sediment-water interface as well as helps to better constrain the mechanisms and processes controlling the coupling between sediments and the overlying waters. Here we used phosphate oxygen isotope ratios (δ(18)O(P)) in concert with sediment chemistry, X-ray diffraction, and Mössbauer spectroscopy on sediments retrieved from an organic rich, sulfidic site in the mesohaline portion of the mid-Bay to identify sources and pathway of sedimentary P cycling and to infer potential feedbacks on bottom water hypoxia and surface water eutrophication. Authigenic phosphate isotope data suggest that the regeneration of inorganic P from organic matter degradation (remineralization) is the predominant, if not sole, pathway for authigenic P precipitation in the mid-Bay sediments. This indicates that the excess inorganic P generated by remineralization should have overwhelmed any pore water and/or bottom water because only a fraction of this precipitates as authigenic P. This is the first research that identifies the predominance of remineralization pathway and recycling of P within the Chesapeake Bay. Therefore, these results have significant implications on the current understanding of sediment P cycling and P exchange across the sediment-water interface in the Bay, particularly in terms of the sources and pathways of P that sustain hypoxia

  7. 137Cs and 210Pb distribution in Manila Bay sediment

    International Nuclear Information System (INIS)

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

  8. Gamma activation analysis of marine sediments at Havana Bay, Cuba

    International Nuclear Information System (INIS)

    Twenty six elements was studied preliminary in the superficial sediments of Havana Bay using gamma activation analysis by the electron accelerator microtron MT-25 at the Flerov Laboratory of Nuclear Reactions, JINR. Samples from five zones of Havana Bay including the three coves were analyzed. The obtained results show a close relation between the concentration levels of the studied elements and the pollution sources. Some elements (As, Ba, Ni, Pb, Cu, Zn, Fe, Cr, Mn) have high concentration levels compared to the values for other environmental marine sediments reported in the literature. (author)

  9. Application of Sediment Trend Analysis in the Examination of Sediment Transport Dynamics of Missisquoi Bay

    Science.gov (United States)

    Kraft, M. P.; Manley, P.; Singer, J.; Manley, T.; McLaren, P.

    2013-12-01

    Missisquoi Bay is located between Vermont and Quebec in the northeast sector of the Restricted Arm of Lake Champlain. The average depth of the Bay is slightly less than 3 meters with a surface area covering 77.5 km2. The Bay receives water from eastern and western catchment basins, most notably via the Missisquoi, Rock, and Pike Rivers. Circulation within Missisquoi Bay has been altered by the construction of railroad causeways in the late 19th century and highway construction in the early 20th century. Over the past several decades there have also been changes in land-use practices, including the intensification of agriculture, increased animal husbandry, and urbanization. As a consequence of construction and changing land use, loadings of nitrogen and phosphorus to the Bay have increased seasonal oxygen depletion causing eutrophication. Since monitoring began in 1992, Missisquoi Bay has displayed the highest mean total phosphorus concentrations and chlorophyll a concentrations in Lake Champlain. Various efforts have taken place to reduce nutrient loading to Missisquoi Bay, but persistent release of phosphorus from bottom sediments will continue to delay for decades the recovery from nutrient diversion. To better understand the causes and timing of eutrophication in Missisquoi Bay, one component of a 5-year integrated VT EPSCoR - RACC program included an examination of N and P loadings and their distribution throughout the Bay. Internal circulation patterns are also being studied. To determine the pattern of net sediment transport and determine sediment behavior (erosion and accretion), a Sediment Trend Analysis (STA) was performed using 369 grab samples collected in the Bay. Grain size distributions for the surface sediment samples were determined using a Malvern Mastersizer 2000 particle size analyzer. Sediment maps showing the proportion of gravel, sand, and mud show that near major river distributaries sand-sized sediment was dominant with muds becoming more

  10. Nitrogen sediment fluxes in an upwelling system off central Chile (Concepción Bay and adjacent shelf during the 1997-1998 El Niño Flujos de compuestos nitrogenados desde los sedimentos, en un sistema de surgencia de Chile central (Bahía Concepción y plataforma adyacente durante El Niño 1997-1998

    Directory of Open Access Journals (Sweden)

    PRAXEDES MUÑOZ

    2004-06-01

    Full Text Available Two stations representing coastal and shelf environments (bay of Concepción and adjacent shelf, respectively were sampled in order to assess benthic nitrogen fluxes. During the study period anomalously high oxygen bottom waters conditions were observed, coinciding with the 1997-1998 El Niño event. From both sites, intact sediment cores were collected for incubation experiments to directly estimate total ammonium fluxes. Pore-water chemistry was also assessed to estimate diffusive fluxes of nitrogen compounds (NH4+, NO3- and NO2-. The NH4+ flux from incubation experiments ranged from 0.55 to 2.18 mmol m-2 day-1 in the inner bay and from 1.84 to 2.14 mmol m-2 day-1 on the shelf. NO3- diffusive fluxes to the sediments were observed in the bay in March (-17 x 10-2 mmol m-2 day-1and on the shelf in November (-2.7 x 10-2 mmol m-2 day-1, associated with the lowest NH4+ diffusive fluxes and coincident with a stronger gradient of Eh in the first centimeters of the sediments. Besides, total NH4+ fluxes lower than in normal periods were observed, suggesting the influence of less reducing conditions, consequence in turn of the lower fluxes of particulated organic material and higher dissolved oxygen in the bottom waters. These conditions were probably imposed by the El Niño event. On the other hand, and relative to previous reports, an increase of irrigation coefficients (DI was estimated. Thus, the flux extension of other nitrogen compounds could have acquired relevance in relation to NH4+ fluxes during the study periodSe analizaron los flujos de compuestos nitrogenados desde los sedimentos en dos áreas representativas de condiciones costeras y de plataforma (Bahía Concepción y plataforma adyacente, respectivamente. Durante el período de muestreo las aguas de fondo presentaron un anómalamente alto contenido de oxígeno disuelto, coincidente con el evento El Niño 1997-1998. De ambos sitios, se incubaron testigos de sedimento intactos para

  11. Predominant Nearshore Sediment Dispersal Patterns in Manila Bay

    Directory of Open Access Journals (Sweden)

    Fernando Siringan

    1997-12-01

    Full Text Available Net nearshore sediment drift patterns in Manila Bay were determined by combining the coastal geomorphology depicted in 1 : 50,000scale topographic maps and Synthetic Aperture Radar (SAR images, with changes in shoreline position and predominant longshore current directions derived from the interaction of locally generated waves and bay morphology.Manila Bay is fringed by a variety of coastal subenvironments that reflect changing balances of fluvial, wave, and tidal processes. Along the northern coast, a broad tidal-river delta plain stretching from Bataan to Bulacan indicates the importance of tides, where the lateral extent of tidal influences is amplified by the very gentle coastal gradients. In contrast, along the Cavite coast sandy strandplains, spits, and wave-dominated deltas attest to the geomorphic importance of waves that enter the bay from the South China Sea.The estimates of net sediment drift derived from geomorphological, shoreline-change, and meteorological information are generally in good agreement. Sediment drift directions are predominantly to the northeast along Cavite, to the northwest along Manila and Bulacan, and to the north along Bataan. Wave refraction and eddy formation at the tip of the Cavite Spit cause southwestward sediment drift along the coast from Zapote to Kawit. Geomorphology indicates that onshore-offshore sediment transport is probably more important than alongshore transport along the coast fronting the tidal delta plain of northern Manila Bay. Disagreements between the geomorphic-derived and predicted net sediment drift directions may be due to interactions of wave-generated longshore currents with wind- and tide-generated currents.

  12. Organic Matter Remineralization Predominates Phosphorus Cycling in the Mid-Bay Sediments in the Chesapeake Bay

    Energy Technology Data Exchange (ETDEWEB)

    Sunendra, Joshi R.; Kukkadapu, Ravi K.; Burdige, David J.; Bowden, Mark E.; Sparks, Donald L.; Jaisi, Deb P.

    2015-05-19

    The Chesapeake Bay, the largest and most productive estuary in the US, suffers from varying degrees of water quality issues fueled by both point and non–point source nutrient sources. Restoration of the bay is complicated by the multitude of nutrient sources, their variable inputs and hydrological conditions, and complex interacting factors including climate forcing. These complexities not only restrict formulation of effective restoration plans but also open up debates on accountability issues with nutrient loading. A detailed understanding of sediment phosphorus (P) dynamics enables one to identify the exchange of dissolved constituents across the sediment- water interface and aid to better constrain mechanisms and processes controlling the coupling between the sediments and the overlying waters. Here we used phosphate oxygen isotope ratios (δ18Op) in concert with sediment chemistry, XRD, and Mössbauer spectroscopy on the sediment retrieved from an organic rich, sulfidic site in the meso-haline portion of the mid-bay to identify sources and pathway of sedimentary P cycling and to infer potential feedback effect on bottom water hypoxia and surface water eutrophication. Isotope data indicate that the regeneration of inorganic P from organic matter degradation (remineralization) is the predominant, if not sole, pathway for authigenic P precipitation in the mid-bay sediments. We interpret that the excess inorganic P generated by remineralization should have overwhelmed any bottom-water and/or pore-water P derived from other sources or biogeochemical processes and exceeded saturation with respect to authigenic P precipitation. It is the first research that identifies the predominance of remineralization pathway against remobilization (coupled Fe-P cycling) pathway in the Chesapeake Bay. Therefore, these results are expected to have significant implications for the current understanding of P cycling and benthic-pelagic coupling in the bay, particularly on the

  13. A Coupled Wave-Current-Sediment model for Skagit Bay

    Science.gov (United States)

    Cowles, G. W.; Holmes, E. M.; Ralston, D. K.

    2010-12-01

    Along with tidal currents, waves provide a dominant forcing mechanism for sediment transport on many tidal flats. In semi-enclosed regions such as Skagit Bay, Washington, the wave action is due mainly to local wind forcing that occurs over seasonal and event scales. Due to the limited fetch, variations in along-flat wave characteristics can drive gradients in the wave-induced bottom stress and resulting sediment transport. In this work, we use an unstructured grid, coupled wave-current-sediment model to study the influence of wave-induced near bottom stresses in the presence of tidal currents on the sediment transport within the Skagit River delta and Skagit Bay. The coupled model consists of three primary components: the Finite Volume Coastal Ocean Model (FVCOM) for hydrodynamics, the unstructured grid model SWAN to compute the phase-averaged wave field, and the Community Sediment Transport Modeling System. Model sensitivities to the choice of coupling and bottom boundary layer formulations are examined. Results from process oriented simulations will be presented. The process studies use a realistic domain with controlled forcing conditions to quantify the influence of wave-induced bed stresses on the sediment dynamics in Skagit Bay.

  14. Sedimentation rates in Manila Bay from 210Pb profiles

    International Nuclear Information System (INIS)

    Manila Bay is one of the water systems affected by red tide occurrences. In an effort to provide an age control to the cyst produced by the red tide causative organism, Pyrodinium bahamense var compressum, several cores were collected from the bay and analyzed for lead-210 (210Pb) by alpha spectrometry. The surface activity ranges from 1.31 dpm/g to 4.56 dpm/g with an average at 3.32 dpm/g. The derived 210Pb vertical profiles indicate a marked increase of 5x to 10x in sedimentation rate in the last ten years in the deeper portions of the bay. This is probably due to the elevated sediment yield of rivers after the eruption of Mt. Pinatubo in 1991 as can be seen in the profiles of the three cores. (Author)

  15. Biogenic silica in surficial sediments of Prydz Bay, Antarctica

    Institute of Scientific and Technical Information of China (English)

    Hu Chuanyu; Xue Bin; Yu Peisong; Pan Jianming

    2008-01-01

    The content and distribution of biogenic silica were investigated in sediment cores from Prydz Bay,Antarctica,during the CHINARE 18/21 cruise.The results show that the content of biogenic silica(BSiO 2 )is ranged from 4.89% to 85.41%,and the average content of biogenic silica is 30.90%,the highest valueoccurred at the IV 10 station.The profile of BSiO 2 in sediment is contrast to that of silicate in the interstitial water.The content of biogenic silica and organic carbon in the surface sediments in the central area of Prydz Bay gyre were much higher than those in other area,and closely related to the Chla content and primary productivity of phytoplankton in the surface water column.

  16. Literature Review of Unconsolidated Sediment in San Francisco Bay and Nearby Pacific Ocean Coast

    OpenAIRE

    Keller, Barry R.

    2009-01-01

    A review of the geologic literature regarding sedimentation in the San Francisco Bay estuarine system shows that the main part of the bay occupies a structural tectonic depression that developed in Pleistocene time. Eastern parts, including San Pablo Bay and Suisun Bay, have had sedimentation throughout late Mesozoic and Tertiary. Carquinez Strait and the Golden Gate may represent antecedent stream erosion. Sedimentation has included estuarine, alluvial, and eolian deposition. The ages of est...

  17. Population study of the filamentous sulfur bacteria Thioploca spp. off the Bay of Concepcion, Chile

    DEFF Research Database (Denmark)

    Schulz, HN; Strotmann, B.; Gallardo, VA;

    2000-01-01

    A population of filamentous sulfur bacteria Thioploca spp. living in the Bay of Concepcion, Chile, and the adjoining shelf area was sampled for 14 mo at 4 to 6 wk intervals to investigate the influence of seasonal variations in upwelling intensity and oxygen concentrations on the population...... 1996, oxygen concentrations in the bottom water were near zero, nitrate was 10 to 20 mu M and the biomass was high, up to 160 g m(-2) wet weight without sheaths. During winter, the biomass declined due to higher oxygen concentrations under reduced upwelling intensity. The depth distribution of...

  18. 210Pb dating of sediments from Havana Bay

    International Nuclear Information System (INIS)

    The study of sedimentation rates and age of marine sediments has been performed through many years using natural and artificial radioactive isotopes. Polluted sediments were collected in three sampling points in the Havana Bay. Sedimentation rates were estimated using two different radiometric approaches: the depth profiles of 137Cs and 210Pb. The maximum activity 137Cs might indicate the proximity of the 1964's. The unsupported 210Pb has been measured to apply both the Constant Initial Concentration Method (CIC) and the Constant Rate of Supply Method (CRS) Dating Models. The results show values for sedimentation rate ranging from 0.2 up to 1.3 cm x y-1 increasing with time which manifests the importance of the achievement of a project of dredging. (author)

  19. Assessment of sediment contamination in Casco Bay, Maine, USA

    International Nuclear Information System (INIS)

    The current status of contaminant concentrations in Casco Bay, decadal trends of these contaminants and changes in their geographical distribution are assessed using sediment samples collected approximately 10 years apart. In general, regulated contaminants appeared to be decreasing in concentration. Total PAH and dioxins/furans concentrations did not significantly change over this period. Total organochlorine pesticides, 4,4-DDE, 4,4-DDD, total DDT, PCB, tributyltin and total butyltin decreased in concentration. Trace element concentrations in sediments decreased at the majority of the sampling sites for chromium, nickel, and selenium while arsenic, cadmium, copper, lead, mercury, silver, and zinc remained relatively constant. None of the contaminants measured has increased by more than a factor of 2. Selected sites located in the Inner Bay, where concentrations are higher and new inputs were more likely, showed increased concentrations of contaminants. Most contaminants were not found at concentrations expected to adversely affect sediment biota based on ERL/ERM guidelines. - Sediment studies indicate decadal decreases for many chemical contaminants in Casco Bay

  20. Heavy metals partitioning in the sediments of Izmir Inner Bay

    Institute of Scientific and Technical Information of China (English)

    GUVEN Duyusen E; AKINCI Gorkem

    2008-01-01

    Izmir Bay is known to be polluted by high concentrations of heavy metals and organic pollutants.Sediment samples taken from 7 different stations in Izmir Inner Bay were analyzed for their total organic matter content and,Cu,Cr Pb and Zn.In addition,the chemical distribution of the metals were determined by means of the BCR(Community Bureau of Reference)Extraction Procedure (developed by European Commission for Standards,Measurement and Testing) which allows the determination of metals bound as four fractions;exchangeable and acid soluble,reducible(bound to iron-manganese oxides),oxidizable(bound to organics)and residual.The results show that Izmir Inner Bay contains sediments with high metal concentrations.According to the chemical distribution of metals,Cr and Cu tend to accumulate mostly on the organic fraction of the sediment.Pb is mostly found in the reducible fraction where Zn is mobile in the sediment,and it is distributed evenly on each fraction.

  1. Concentración de metales pesados (Cu, Ni, Zn, Cd, Pb) en la biota y sedimentos de una playa artificial, en la bahía San Jorge 23°S, norte de Chile Heavy metals concentration (Cu, Ni, Zn, Cd, Pb), in biota and sediments of an artificial beach, in San Jorge bay 23°S, northern Chile

    OpenAIRE

    Gabriel Castro; Jorge Valdés

    2012-01-01

    Se evaluó el contenido de metales pesados (Cu, Ni, Zn, Cd, Pb) en la biota y el sedimento de una playa artificial (Paraíso) y una playa natural (El Lenguado), ubicadas en la bahía San Jorge, norte de Chile. Los resultados fueron utilizados para comparar ambos sistemas, el grado de cumplimiento de la normativa ambiental nacional e internacional, y el efecto de la construcción de la playa artificial sobre el nivel de contaminación por metales existentes históricamente en esa zona. En cada playa...

  2. Distribution, source identification, and historical trends of organic micropollutants in coastal sediment in Jakarta Bay, Indonesia.

    Science.gov (United States)

    Rinawati; Koike, Tatsuya; Koike, Hiroaki; Kurumisawa, Rina; Ito, Maki; Sakurai, Shigeaki; Togo, Ayako; Saha, Mahua; Arifin, Zainal; Takada, Hideshige

    2012-05-30

    We determined concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), linear alkylbenzenes (LABs), and hopanes in coastal sediments collected from Jakarta Bay and Tokyo Bay. PAH concentrations in sediments from Jakarta Bay (257-1511 ng/g-dry) were lower than or comparable to those from Tokyo Bay (1372-1615 ng/g-dry). Ratios of alkyl-PAHs to parent PAHs showed a greater contribution of petrogenic inputs in Jakarta Bay than in Tokyo Bay. This difference is consistent with the higher ratio of hopanes to PAHs in Jakarta Bay. LAB concentrations in Jakarta Bay (geometric mean, 1400 ng/g-dry) were higher than those in Tokyo Bay (661 ng/g-dry). The internal to external (I/E) ratios of LABs in Jakarta Bay (0.92-2.88) were lower than those in Tokyo Bay (2.8-4.8), indicating that Jakarta Bay receives untreated or poorly treated sewage. Significant amounts of tetrapropylene-based alkylbenzenes were detected in several locations in Jakarta Bay, suggesting current usage of the non-degradable surfactants alkylbenzene sulfonates that are banned in many countries. The PCB concentration in Jakarta Bay was 1 order of magnitude lower than in Tokyo Bay, suggesting minimal usage of PCBs in industrial or commercial products in Jakarta. Analyses of a sediment core indicate increasing inputs of PAHs, hopanes, and LABs into Jakarta Bay during recent decades. PMID:22480710

  3. Ecological risk evaluation of sediment metals in a tropical Euthrophic Bay, Guanabara Bay, Southeast Atlantic.

    Science.gov (United States)

    Abreu, Ilene Matanó; Cordeiro, Renato Campello; Soares-Gomes, Abílio; Abessa, Denis Moledo S; Maranho, Luciane Alves; Santelli, Ricardo Erthal

    2016-08-15

    Surface sediments were collected from Guanabara Bay, at 14 stations distributed in five sectors, over three sampling campaigns. Analyses of metals, grain size fractions and total organic carbon analyses were performed. The geo-accumulation index and the enrichment factor were estimated to assess contamination status based on background values. Additionally, the sediment quality guidelines were applied to evaluate the adverse biological effects. Results show that there was no seasonal variation in sediment quality based on any methodology, and all methods utilized showed that NW sector and HRJ sector were the worst affected and that the NE sector had the best conditions. The sediments of GB are polluted mainly by Cr, Pb and Zn. According to ΣSEM/AVS, these metals are not available to the biota, although toxicity tests dispute this. Among the various methods employed, those using background values for the area seem to best reflect the local historical contamination. PMID:27210562

  4. Recent 137Cs deposition in sediments of Admiralty Bay, Antarctica

    International Nuclear Information System (INIS)

    Cesium-137, radium-226 and lead-210 profiles of a 25 cm sediment core give an indication of recent changes in land-ocean interactions at a polar coastal environment (Admiralty Bay, King George Island, Antarctica). The linear sedimentation accumulation rate at the study site calculated from the unsupported 210Pb profile was 6.7 mm/year from 1965 to 2005. A 3.5-fold increase in 137Cs concentrations was observed in the top layer of this sediment core. This sharp increase seems to indicate a recent redistribution of fallout radionuclides previously deposited on soil, vegetation and snow. These results imply enhanced land-ocean interactions at this site likely as a result of climate change. Because our results are based on a single core, additional investigations are needed to confirm our observations.

  5. Sediment dispersal pattern in the Bay of Bengal - evidence for commencement of Bengal Fan sedimentation

    Science.gov (United States)

    Krishna, K. S.; Ismaiel, M.; Karlapati, S.; Gopala Rao, D.; Mishra, J.; D, S.

    2015-12-01

    The sediment succession in the Bay of Bengal records signatures corresponding to India-Asia collision, regional climate, and erosional processes of the Himalayan orogeny and the Indian subcontinent. The Bengal Fan - world's largest submarine fan - has been long studied to understand the link between the Himalayan tectonics and Asian monsoon climate, but early phase information of the Himalaya erosion is not retrieved from the Indian Ocean due to lack of deep-core samples. Therefore, the missing corresponding signals hampered the understanding of coupled processes between tectonics, climate and erosion. Seismic reflection profiles and industrial drill wells from the western Bay of Bengal show two different modes of sediment deposition: initially Indian peninsular rivers discharged sediments to the ocean at a rate ~20 m/m.y. until Oligocene-Miocene time (~23 Ma) with the exception of two fairly-enhanced sediment pulses from 65 to 54 and again from 34 to 23 Ma; since 23 Ma the Ganges and Brahmaputra rivers added huge volumes of sediments to the bay with variable rates range from 40 to >1000 m/m.y. Using seismic stratigraphic technique we found a distinct increase in sediment discharge (~140 m/m.y.) at 23 Ma is an important age marker for the onset of Bengal Fan sedimentation as a coupled connection between the Himalayan tectonics and Asian climate. Further rise in sedimentation rate during the period 6.8 - 0.8 Ma is surprisingly not in agreement with the decrease in sediment rate reported at ODP Leg 116 sites in the distal Bengal Fan, but coincident with the change in monsoon intensity. Here we provide well constrained ages for the growth of the Bengal Fan, which can serve as benchmark for interactions between the Himalayan exhumation and Asian climate.

  6. Evaluation of older bay mud sediment from Richmond Harbor, California

    Energy Technology Data Exchange (ETDEWEB)

    Pinza, M.R.; Mayhew, H.L.; Word, J.Q.

    1996-09-01

    The older, bay mud (OBM) unit predates modem man and could act as a barrier to the downward transport of contaminants from the younger bay mud (YBM) because of its hard-packed consistency. However, its chemical and biological nature have not been well characterized. Battelle/Marine Sciences Laboratory (MSL) conducted three independent studies of OBM sediment in January 1993, January 1994, and October 1994. These studies evaluated potential chemical contamination and biological effects of OBM that could occur as a result of dredging and disposal activities. These evaluations were performed by conducting chemical analysis, solid-phase toxicity tests, suspended- particulate-phase (SPP) toxicity tests, and bioaccumulation tests on the OBM sediment. If the sediment chemistry and toxicity results showed no or minimal contamination and toxicological responses, then either the OBM could be left exposed in Richmond Harbor after dredging the YBM without leaving a source of contamination, or if the project depths necessitate, the OBM would be acceptable for disposal at an appropriate disposal site.

  7. Forearc deformation processes inferred from drowned shorelines in the Arauco Bay, Southern Chile (37°S)

    Science.gov (United States)

    Jara-Muñoz, Julius; Melnick, Daniel; Bernhardt, Anne; Argandoña, Boris; Gonzalez-Acuña, Javiera; Strecker, Manfred

    2015-04-01

    Relict drowned landscapes often constitute preserved snapshots of terrestrial environments prior to flooding episodes during the Quaternary. Forearc deformation processes are usually recorded by coastal landforms, such as paleo-shorelines or marine terraces reflecting pronounced vertical movements. Similarly, drowned coastal landscapes represent past sea-level positions that can be used as tracers of tectonic deformation and sea-level change. In this study we present hitherto unrecognized drowned Quaternary shorelines in the Arauco Bay of southern Chile. The Arauco Bay lies inland of the Santa Maria Fault and is surrounded by densely populated areas, many devastated by the tsunami following the 2010 M 8.8 Maule earthquake. The shorelines are folded, apparently as a result of slip along the Santa Maria Fault, a blind splay-fault system rooted in the Nazca-South America plate-boundary zone, documenting protracted tectonic activity. We mapped and used these drowned geomorphic markers using high-resolution bathymetry (2.5 m) to infer rates and style of deformation along the Santa Maria splay fault. For this purpose we used surface classification models, observations from a remotely operated vehicle (ROV), and sedimentology of sea-bottom samples. High roughness areas correspond to well-exposed bedrock outcrops. The enclosed patches were studied in detail and compared with LiDAR data from emerged and actively forming marine platforms from nearby areas. Three levels of drowned shorelines were identified: at ~110 m, ~40 and ~60 m depth, respectively. The shallower two shorelines are distributed as fringes parallel to the coastline of the Arauco Bay and deepen towards the trench. We selected the shallowest level as an exploratory target for a ROV dive obtaining video and still images of micromorphologic features; a sampling target was selected at 45 m where professional divers collected samples of bedrock and sediments. Chronologic correlation was performed based on global

  8. Aliphatics hydrocarbon content in surface sediment from Jakarta Bay, Indonesia

    Science.gov (United States)

    YAzis, M.; Asia, L.; Piram, A.; Doumenq, P.; Syakti, A. D.

    2016-02-01

    Sedimentary aliphatic hydrocarbons content have been studied quantitatively and qualitatively using GC/MS method in eight coastal stations located in the Jakarta Bay, North of Jakarta, Indonesia. The total concentrations n-alkanes have ranged from 480 μg.kg-1to 1,935 μg.kg-1sediment dry weight. Several ratios (e.g. CPI24-32, NAR, TAR, Pr/Phy, n-C17/Pr, n- C18/Phyt,n-C29/n-C17, Ʃn-alkanes/n-C16LMW/HMW, Paq and TMD) were used to evaluate the possible sources of terrestrial-marine inputs of these hydrocarbons in the sediments. The various origins of aliphatic hydrocarbons were generally biogenic, including both terrigenous and marine, with an anthropogenic pyrolytic contribution (petrogenic and biogenic combustion). Two stations (G,H) were thehighest concentration and had potential risk to environment

  9. Sedimentation rates in Kagoshima Bay, Southwestern Japan, using the 210Pb method

    OpenAIRE

    Yokota K; Inoue M.; Kofuji H.; Maeda H.

    2012-01-01

    To understand the pattern of sedimentation rates as fundamental physical parameter of coastal environment, the 210Pb dating method was applied to core samples collected from Kagoshima Bay, Southwestern Japan. The sedimentation rate varied at each location within the bay (0.08–0.30 g·cm−2·y−1), and the rate at the bay-head area was less than that at the centre of the bay. The inventory of ex210Pb has a lower value in the bay-head area. The low ex210Pb inventory at Stn.5' is considered to be du...

  10. Biogeochemical characteristics of sedimenting particles in Dona Paula Bay, India

    Science.gov (United States)

    D'souza, Fraddry; Garg, Anita; Bhosle, Narayan B.

    2003-10-01

    Sedimenting particles were collected at weekly intervals from October to May during 1995-1997 at a station in the coastal waters of Dona Paula Bay on the west coast of India. Sedimenting particles were analysed for concentration and composition of total sedimented particulate matter (TPM), biogenic silica (BSi) and total neutral carbohydrates (TCHO). TPM, BSi and TCHO fluxes showed seasonal and annual variations. Fluxes of BSi showed significant correlations with the fluxes of TCHO and fucose indicating that at the study site diatoms were associated with the production of carbohydrates. However, a high content of arabinose plus xylose (˜56% of TCHO without glucose) in some samples and their negative correlations with fucose may suggest terrestrial inputs. Sedimenting particles depleted in glucose content were enriched in rhamnose, fucose, xylose, mannose and galactose. A principal component analysis based on log-normalized wt% of monosaccharides established three factors that contributed 78% of total variance. The first factor was mostly controlled by the abundance of arabinose and xylose while the second and third factors were dependent on fucose, galactose, mannose and rhamnose. Carbohydrate composition data suggest that the nature and sources of organic matter at the study site varied over the period of study.

  11. Chile.

    Science.gov (United States)

    1992-05-01

    The background notes on Chile provide a statistical summary of the population, geography, government, and the economy, and more descriptive text on the history, population, government, economy, defense, and foreign relations. In brief, Chile has 13.3 million Spanish Indian (Mestizos), European, and Indian inhabitants and an annual growth rate of 1.6%. 96% are literate. Infant mortality is 18/1000. 34% of the population are involved in industry and commerce, 30% in services, 19% in agriculture and forestry and fishing, 7% in construction, and 2% in mining. The major city is Santiago. The government, which gained independence in 1810, is a republic with executive, legislative, and judicial branches. There are 12 regions. There are 6 major political parties. Suffrage is universal at 18 years. Gross domestic product (GDP) is $29.2 billion. The annual growth rate is 5% and inflation is 19%. Copper, timber, fish, iron ore, nitrates, precious metals, and molybdenum are its natural resources. Agricultural products are 9% of GDP and include wheat, potatoes, corn, sugar beets, onions, beans, fruits, and livestock. Industry is 21% of GDP and includes mineral refining, metal manufacturing, food and fish processing, paper and wood products, and finished textiles. $8.3 billion is the value of exports and $7 billion of imports. Export markets are in Japan, the US, Germany, Brazil, and the United Kingdom. Chile received $3.5 billion in economic aid between 1949-85, but little in recent years. 83% live in urban centers, principally around Santiago. Congressional representation is made on the basis of elections by a unique binomial majority system. Principal government officials are identified. Chile has a diversified free market economy and is almost self-sufficient in food production. The US is a primary trading partner. 49% of Chile's exports are minerals. Chile maintains diplomatic relations with 70 countries, however, relations are strained with Argentina and Bolivia. Relations

  12. Ecotoxicological sediment evaluations in marine aquaculture areas of Chile.

    Science.gov (United States)

    Rudolph, Anny; Medina, Paulina; Urrutia, Carolina; Ahumada, Ramón

    2009-08-01

    Given its geographic characteristics, the southern Chilean fjord area is subjected to growing environmental pressure from the development of diverse forms of aquaculture (i.e., fish, algae, shellfish). The sediments accumulate substances as a natural sink, and ecotoxicology assays offer a reliable and robust proxy for sediment quality analyses. This study's objective was to establish a mid-range toxicity base line for the sediments in the region by applying a battery of non-specific ecotoxicological assays. Sediment samples (28) were collected in the channels and fjords studied during the CIMAR-Fiordos 11 cruise (July 2005). The sediments were evaluated using different species endemic to the eastern Pacific as targets: Ampelisca araucana, Tisbe longicornis, Arbacia spatuligera, and Dunaliella tertiolecta. The conditions for each assay were reported previously. Of the four species used as ecotoxicological tools, only D. tertiolecta differed significantly from the control group (negative) in terms of its growth. This difference could be attributed to nutrient enrichment. In general, we concluded that, although local changes occurred in the sediments, the mesoscale magnitude of the ecotoxicological alterations was small. Nonetheless, a surveillance program should be implemented that would allow us to follow-up and analyze the changes that are taking place in the systems on broader scales of time and space. PMID:18633720

  13. Chile.

    Science.gov (United States)

    1988-09-01

    Chile is a long (2650 miles), narrow (250 miles at widest point) country sandwiched between the Andes mountains and the Pacific. The northern desert is rich in copper and nitrates; the temperate middle region is agricultural and supports the major cities, including Santiago, the capital, and the port of Valparaiso; and the southern region is a cold and damp area of forests, grasslands, lakes, and fjords. The country is divided into 12 administrative regions. Chile's population of 12.5 million are mainly of Spanish or Indian descent or mestizos. Literacy is 92.3%, and the national language is Spanish. Infant mortality is 18.1/1000, and life expectancy is 68.2 years. 82% of the people are urban, and most are Roman Catholics. Chile was settled by the Spanish in 1541 and attached to the Viceroyalty of Peru. Independence was won in 1818 under the leadership of Bernardo O'Higgins. In the 1880s Chile extended its sovereignty over the Strait of Magellan in the south and areas of southern Peru and Bolivia in the north. An officially parliamentary government, elected by universal suffrage, drifted into oligarchy and finally into a military dictatorship under Carlos Ibanez in 1924. Constitutional government was restored in 1932. The Christian Democratic government of Eduardo Frei (1964-70) inaugurated major reforms, including land redistribution, education, and far-reaching social and economic policies. A Marxist government under Salvador Allende lasted from 1970 to 1973 when the present military government of General Pinochet Ugarte took power, overthrew Allende, abolished the Congress, and banned political parties. It has moved the country in the direction of a free market economy but at the cost of systematic violations of human rights. A new constitution was promulgated in 1981, and congressional elections have been scheduled for October, 1989. A "National Accord for Transition to Full Democracy" was mediated by the Catholic Church in 1985. The social reforms of the

  14. Improving Sediment Transport Prediction by Assimilating Satellite Images in a Tidal Bay Model of Hong Kong

    Directory of Open Access Journals (Sweden)

    Peng Zhang

    2014-03-01

    Full Text Available Numerical models being one of the major tools for sediment dynamic studies in complex coastal waters are now benefitting from remote sensing images that are easily available for model inputs. The present study explored various methods of integrating remote sensing ocean color data into a numerical model to improve sediment transport prediction in a tide-dominated bay in Hong Kong, Deep Bay. Two sea surface sediment datasets delineated from satellite images from the Moderate Resolution Imaging Spectra-radiometer (MODIS were assimilated into a coastal ocean model of the bay for one tidal cycle. It was found that remote sensing sediment information enhanced the sediment transport model ability by validating the model results with in situ measurements. Model results showed that root mean square errors of forecast sediment both at the surface layer and the vertical layers from the model with satellite sediment assimilation are reduced by at least 36% over the model without assimilation.

  15. Effect of sediment size on bioleaching of heavy metals from contaminated sediments of Izmir Inner Bay

    Institute of Scientific and Technical Information of China (English)

    Duyusen E.Guven; Gorkem Akinci

    2013-01-01

    The effect of sediment size on metals bioleaching from bay sediments was investigated by using fine (< 45 μm),medium (45-300 μm),and coarse (300-2000μm) size fractions of a sediment sample contaminated with Cr,Cu,Pb,and Zn.Chemical speciation of the metals in bulk and size fractions of sediment were studied before and after bioleaching.Microbial activity was provided with mixed cultures of Acidithiobacillus thiooxidans and Acidithiobacillusferrooxidans.The bioleaching process was carried out in flask experiments for 48 days,by using 5% (W/V) of solid concentration in suspension.Bioleaching was found to be efficient for the removal of selected heavy metals from every size fraction of sediments,where the experiments with the smaller particles resulted in the highest solubilization ratios.At the end of the experimental period,Cr,Cu,Pb and Zn were solubilized to the ratios of 68%,88%,72%,and 91% from the fine sediment,respectively.Higher removal efficiencies can be explained by the larger surface area provided by the smaller particles.The changes in the chemical forms of metals were determined and most of the metal releases were observed from the reducible and organic fractions independent from grain size.Higher concentrations were monitored in the residual fraction after bioleaching period,suggesting they are trapped in this fraction,and cannot be solubilized under natural conditions.

  16. A Tidally Averaged Sediment-Transport Model for San Francisco Bay, California

    Science.gov (United States)

    Lionberger, Megan A.; Schoellhamer, David H.

    2009-01-01

    A tidally averaged sediment-transport model of San Francisco Bay was incorporated into a tidally averaged salinity box model previously developed and calibrated using salinity, a conservative tracer (Uncles and Peterson, 1995; Knowles, 1996). The Bay is represented in the model by 50 segments composed of two layers: one representing the channel (>5-meter depth) and the other the shallows (0- to 5-meter depth). Calculations are made using a daily time step and simulations can be made on the decadal time scale. The sediment-transport model includes an erosion-deposition algorithm, a bed-sediment algorithm, and sediment boundary conditions. Erosion and deposition of bed sediments are calculated explicitly, and suspended sediment is transported by implicitly solving the advection-dispersion equation. The bed-sediment model simulates the increase in bed strength with depth, owing to consolidation of fine sediments that make up San Francisco Bay mud. The model is calibrated to either net sedimentation calculated from bathymetric-change data or measured suspended-sediment concentration. Specified boundary conditions are the tributary fluxes of suspended sediment and suspended-sediment concentration in the Pacific Ocean. Results of model calibration and validation show that the model simulates the trends in suspended-sediment concentration associated with tidal fluctuations, residual velocity, and wind stress well, although the spring neap tidal suspended-sediment concentration variability was consistently underestimated. Model validation also showed poor simulation of seasonal sediment pulses from the Sacramento-San Joaquin River Delta at Point San Pablo because the pulses enter the Bay over only a few days and the fate of the pulses is determined by intra-tidal deposition and resuspension that are not included in this tidally averaged model. The model was calibrated to net-basin sedimentation to calculate budgets of sediment and sediment-associated contaminants. While

  17. Chile.

    Science.gov (United States)

    1986-04-01

    In 1985, Chile's population stood at 12 million, with an annual growth rate of 1.7%. 1984's infant mortality rate was 20/1000 live births and life expectancy was 67 years. The literacy rate was 94%. Of the work force of 3,841,000 in 1985, 15.9% were engaged in agriculture, forestry, and fishing; 31.3% were employed in industry and commerce; 38.6% were in the service sector; 8.7% worked in mining; and 4.4% were employed in construction. Chile's military junta is scheduled to be replaced by an elected legislature in 1990. The GDP was US $19.2 billion in 1984, with an annual real growth rate of 6.3%, and per capita GDP stood at US$1590. Inflation averages 23%. Industry comprises 21% of the GDP. Longterm prospects for the Chilean economy are influenced by a high debt service ratio, very low domestic savings and investment, the prospect of little or no increase in copper prices, and continuing problems in the domestic financial sector. In 1985-88, under the International Monetary Fund macroeconomic program, Chile will strive for moderate economic growth while managing its external debt servicing burden. PMID:12178144

  18. Composition of Carbon-13 and Nitrogen-15 in Sediments of the Ha Long Bay

    International Nuclear Information System (INIS)

    The Ha Long Bay with beautiful landscape and rich ecosystems is being used by human to develop the economy. The Ha Long Bay is currently affected by human activities causing the sedimentary environment to be much changed. The change of the environment in the Bay was studied using the composition of carbon-13, nitrogen-15 (δ13C, δ15N) and the C/N ratio in sediment of seven cores collected within the Ha Long Bay. In the Ha Long Bay, sedimentary environment receives many source sediment supplies. The north-east of Ha Long bay receives sources from sea, it is characterized by δ13C in sediment from -8.79 to -18.01‰, value δ15N in sediment from 4.36 to 4.73 ‰ and ratio of C/N from 13 to 41, the source organic matter in sediment shows that affected by C4 plant. The centre of Ha Long Bay receives organic source from sea, it is characterized by δ13C in sediment from -16.72 to -21.58 ‰, value δ15N in sediment ranges 4.15 - 5.20 ‰, ratio of C/N in sediment from 7 to 23. The north-west of Ha Long Bay is affected by rivers, it is characterized by δ13C in sediment range from -13.64 to -25.77 ‰, value δ15N in sediment from 2.50 to 4.38 ‰, and ratio C/N from 9 to 19. (author)

  19. Characterization of water and lake sediments in Laguna de Bay

    International Nuclear Information System (INIS)

    In this work we studied elemental distributions of trace elements, dissolved oxygen and microbiological allotment (total plate count, Coliform, and E. coli) in sediment and surface water from 3 sites in Laguna de Bay. The measured parameters were associated with the quality of the water and to anthropogenic and geogenic processes taking place in the lake. In all cases sediment samples were collected and analyzed for elemental composition using an X-ray fluorescence technique. Water samples were collected and analyzed for nitrate, chloride, and sulfate ions using selective electrodes. Bicarbonate ions in the lake water were determined by titration. The microbial load (total plate count, total coliform and E,. Coli) were determined using Simplate. Field parameters such as pH and conductivity were likewise measured. Preliminary assumptions suggest that proximity to anthropogenic sources has substantially contributed to the combined loads of major ions pollution in the lake. Laguna de Bay is classified as Class C (DENR Administrative Order No. 34). For all the sites, the conductivity of the water were considerably elevated, which ranged from 929 to 933 uS/cm; Site 1 water exceeded the permissible range for pH for Class C water which is 6.5 to 8.5 for the support and rearing of fish. None of the lake waters exceeded the limits for the ions, chloride (set at 350 mg/L) and nitrate (set at 10 mg/L), for Class C water criteria. All the sites meet the dissolved oxygen, DO, criterion for Class C waters which is set at 5 mg/L. In terms of microbiological load, Site 1 had the least most probable number per ml of water, MPN/ml: total plate count (6720), Coliform (less that detection limit) and E. coli (less than LLD); Site 3 was the most contaminated: total plate count (greater than 70,000), Coliform(48768) and E. Coli (23808). X-ray fluorescence analyses of sediments allowed the determination of elements Na, Mg, Al, P, Si, Cl, K. Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, As, Br, Rb

  20. Estimation of sedimentation processes in Tokyo Bay using radionuclides and anthropogenic molecular markers

    Energy Technology Data Exchange (ETDEWEB)

    Sanada, Yukihisa; Sato, Futoshi; Kumata, Hidetoshi; Takada, Hideshige [Tokyo Univ. of Agriculture and Technology, Fuchu (Japan). Faculty of Agriculture; Yamamoto, Ai; Kato, Yoshihisa; Ueno, Takashi

    1999-06-01

    To estimate the sedimentation rate and to understand the sedimentation processes in Tokyo Bay, vertical distributions of {sup 210}Pb and {sup 137}Cs were determined for two sediment cores (F-2 and F-5) from Tokyo Bay and one from the moat of Imperial Palace for the Tokyo. Molecular stratigraphy was applied to one of the Tokyo Bay sediment cores using polychlorinated biphenyls (PCBs) and linear and tetrapropylene-based alkylbenzenes (LABs and TABs). {sup 210}Pb showed exponential downcore decrease with substantial fluctuation. In the sediment core of the bay (F-2), radiocesium maximum, corresponding to the atmospheric deposition maximum at 1963, was observed. Good agreement between the deposition date estimated using radionuclides ({sup 137}Cs and {sup 210}Pb) and the vertical distributions of PCBs, LABs and TABs, suggests the utility of multiple markers approach for sediment stratigraphy. In the Tokyo Bay sediments, only slight or negligible decrease in {sup 137}Cs activity was observed toward the surface layer where significant amounts of {sup 137}Cs was detected, whereas a sharp peak of {sup 137}Cs were observed for the Moat which has no inflowing rivers. PCBs and TABs, whose productions and usage cased by early 1970s, decreased gradually to the sediment-water interface in the Tokyo Bay and were found significantly in the surficial sediments. All these markers suggest that riverine and estuarine sediments play a role of a reservoir of the pollutants, that is, particle-reactive pollutants are temporally deposited and stored in riverine and estuarine sediments which are intermittently supplied to Tokyo Bay during flood events with resuspension. (author)

  1. Redox dynamics in the Chesapeake Bay: The effect on sediment/water uranium exchange

    International Nuclear Information System (INIS)

    The effect of seasonal variations in productivity and redox dynamics on the sediment/water exchange of uranium was investigated on a twelve cruise time series in the Chesapeake Bay. The deep waters of the bay undergo seasonal anoxia in response to high primary productivity and water column stratification from late spring to early fall. Dissolved oxygen was used to monitor sediment redox conditions. Dissolved 238U was measured in the water column and sediment porewaters to monitor water column/sediment exchange. Uranium incorporation in bay sediments results from two distinct processes: productivity-dependent scavenging from the water column and redox-dependent cycling of uranium between sediments and bottomwater. Uranium is removed from surface waters of the bay by scavenging with biodetritus during periods of high primary productivity. Bottomwater and sediment redox conditions determine whether this particle-bound uranium is buried or released to overlying water. Particulate uranium is released to bottomwaters and porewaters during the degradation of biodetritus and oxidation of authigenic uranium. Low oxygen in bottomwaters in the summer results in minimal exchange of uranium between the sediments and bottomwater, due to the stability of reduced U(IV). High bottomwater oxygen concentrations associated with bay turnover in the fall results in release of authigenic uranium by oxidation to the soluble (VI) form. Enrichment of uranium in fall bottomwater suggests that authigenic uranium is very labile when exposed to oxic environmental conditions. This process is enhanced by physical mixing when anoxic sediments are resuspended into the oxic bottomwaters

  2. Anthropogenic mercury signals in lake sediments from southernmost Patagonia, Chile

    International Nuclear Information System (INIS)

    Atmospheric mercury fluxes to terrestrial and aquatic surfaces in the Northern Hemisphere have increased since the Industrial Revolution. However fluxes are not well characterized for the Southern Hemisphere, since environmental archives are comparatively scarce. Mercury records from 210Pb-dated sediment cores of three South Patagonian lakes were investigated in order to reveal the influence of anthropogenic activities on atmospheric mercury deposition in remote lakes of the Southern Hemisphere. Comparison with indicators of organic matter sources (carbon and nitrogen/carbon ratios) and a conservative mineral soil element (zirconium) in the sediments revealed that soil erosion is an important process contributing mercury to these lakes and influenced variation in concentrations through time. However, at ∼ 1900 AD mercury accumulation increased independent from soil erosion and peaked from 1980 to 2000 AD. We attribute this to an increase in atmospheric mercury deposition in this remote region of the Southern Hemisphere. Mean flux ratios, which reflect the increase in modern mercury accumulation compared to pre-1850 AD, lie within a range of 1.4 to 2.4. These values indicate an increase in atmospheric mercury deposition slightly lower than predictions derived from global mercury models that suggest an increase in Hg deposition by a factor of 2 to 3. - Highlights: ► Hg concentrations and accumulation rates were determined in South Patagonian lake sediments. ► Soil erosion was shown to account significantly for short-term variations in Hg accumulation. ► Increased Hg accumulation since 1900 AD (factor of 1.4–2.4) is attributed to a rise in atmospheric Hg. ► Accumulation of anthropogenic Hg peaked between 1980 and 2000 AD (∼ 3 μg m−2 yr−1)

  3. Anthropogenic mercury signals in lake sediments from southernmost Patagonia, Chile

    Energy Technology Data Exchange (ETDEWEB)

    Hermanns, Yvonne-Marie, E-mail: y-m.hermanns@tu-bs.de; Biester, Harald, E-mail: h.biester@tu-bs.de

    2013-02-15

    Atmospheric mercury fluxes to terrestrial and aquatic surfaces in the Northern Hemisphere have increased since the Industrial Revolution. However fluxes are not well characterized for the Southern Hemisphere, since environmental archives are comparatively scarce. Mercury records from {sup 210}Pb-dated sediment cores of three South Patagonian lakes were investigated in order to reveal the influence of anthropogenic activities on atmospheric mercury deposition in remote lakes of the Southern Hemisphere. Comparison with indicators of organic matter sources (carbon and nitrogen/carbon ratios) and a conservative mineral soil element (zirconium) in the sediments revealed that soil erosion is an important process contributing mercury to these lakes and influenced variation in concentrations through time. However, at ∼ 1900 AD mercury accumulation increased independent from soil erosion and peaked from 1980 to 2000 AD. We attribute this to an increase in atmospheric mercury deposition in this remote region of the Southern Hemisphere. Mean flux ratios, which reflect the increase in modern mercury accumulation compared to pre-1850 AD, lie within a range of 1.4 to 2.4. These values indicate an increase in atmospheric mercury deposition slightly lower than predictions derived from global mercury models that suggest an increase in Hg deposition by a factor of 2 to 3. - Highlights: ► Hg concentrations and accumulation rates were determined in South Patagonian lake sediments. ► Soil erosion was shown to account significantly for short-term variations in Hg accumulation. ► Increased Hg accumulation since 1900 AD (factor of 1.4–2.4) is attributed to a rise in atmospheric Hg. ► Accumulation of anthropogenic Hg peaked between 1980 and 2000 AD (∼ 3 μg m{sup −2} yr{sup −1})

  4. Chronic sublethal effects of San Francisco Bay sediments on nereis (neanthes) arenaceodentata; bioaccumulation from bedded sediments. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Moore, D.; Dillon, T.M.

    1993-09-01

    In previous studies with San Francisco Bay sediments, minimal chronic sublethal effects were detected (Miscellaneous Paper D-93-1 and another Miscellaneous Paper in preparation by Moore and Dillon). To ensure that the lack of effects was not due to a lack of contaminant uptake, a bioaccumulation experiment was conducted. Bioaccumulation from bedded sediments was evaluated following a 9-week exposure with the marine polychaete worm Nereis (Neanthes) arenaceodentata. Two sediments were evaluated, a contaminated San Francisco Bay test sediment and a clean control sediment from Sequim, WA. Animals were exposed as early juveniles through adulthood. Tissues were analyzed for metals, polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and pesticides. Worms exposed to the contaminated San Francisco Bay sediment had significantly higher tissue residues of silver (0.30 mg/kg dry weight) and tributyltin (0.298 mg/kg dry weight). Conversely, tissue residues of control animals were significantly higher in cadmium (0.67 mg/kg dry weight) and lead (1.89 mg/kg dry weight). Small Amounts (0.02 mg/kg dry weight) of aldrin and dieldrin were measured in worms exposed to the contaminated sediment, while dieldrin and 8-BHC were found in Bioaccumulation, Neanthes, Chronic sublethal, San Francisco Bay, Dredged, Material, Sediment.

  5. Sediment Data from Great Bay Estuary, New Hampshire (ARMSTRONG74 shapefile)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The sediment data presented in this data layer were from a geochemical study sited in Great Bay Estuary, New Hampshire. The analog data were originally converted...

  6. Sediments of Western Mass Bay acquired in 1976 (MEISBURGER76 shapefile)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A seismic reflection survey with concurrent bottom sampling was conducted in western Massachusetts Bay to obtain information on bottom topography and sediments,...

  7. Magnitude and Extent of Contaminated Sediment and Toxicity in Chesapeake Bay

    OpenAIRE

    Hartwell, S. Ian; Hameedi, Jawed

    2007-01-01

    INTRODUCTION: This report summarizes the results of NOAA's sediment toxicity, chemistry, and benthic community studies in the Chesapeake Bay estuary. As part of the National Status and Trends (NS&T) Program, NOAA has conducted studies to determine the spatial extent and severity of chemical contamination and associated adverse biological effects in coastal bays and estuaries of the United States since 1991. Sediment contamination in U.S. coastal areas is a major environmental issue becaus...

  8. Variación espacial y temporal de las masas de agua, nutrientes y sedimentación de la materia orgánica e inorgánica en la bahía Mejillones del sur (23° S, Chile Spatial and temporal variability of water masses, nutrients and sedimentation of organic and inorganic matter, in Mejillones del sur bay (23° S, Chile

    Directory of Open Access Journals (Sweden)

    MAURICIO CERDA

    2010-01-01

    temporal variability of physical-chemical properties and sedimentation rates of particulate matter of the water column at a fixed station set within Bahía de Mejillones del Sur, during the austral summer of 2003-2004. The water column was generally characterized by warmer oxygen-rich surface waters, marked stratification gradients between about 10 to 20 m depths and by colder, denser and sub-oxic upwelling waters from 30 m depths to the bottom throughout studied period. The bay was governed by three different water masses: the Surface Sub-Tropical Waters (SSTW, Sub-Antarctic Waters (SAAW and the Equatorial Sub-Surface Waters (ESSW. The surface waters exhibited a clear alternation between weak and short (three to eight days upwelling events and longer (29 days periods of stratification. During the weak upwelling events and at the onset of the stratification periods, sub-oxic to micro-oxic conditions prevailed with elevated nutrient concentrations at the 10 to 15 m depth layer. The variability of oxygen saturation levéis and of the dissolved inorganic nutrients nitrogen (N, phosphorus (P and silicic acid (Si, as well as the behavior of the N:P and Si:NID ratios, indicated the important combined effects of internal recycling of the organic matter in the surface water column and of the contribution of allochthonous nutrients from upwelled bottom waters. The fortnightly variability of the total flux of particulate material collected in sediment traps in the bay suggest that material deposition from the water column is governed by the alternation of upwelling and stratification events. In addition, the sediment traps registered nitrogen impoverishment with increasing depths, suggesting that remineralisation processes affected the settling of particles and the denitrification of the oxydo-reducting deeper waters of the bay.

  9. Sediment grab data from October 1999 in Apalachicola Bay, Florida

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Apalachicola Bay National Estuarine Research Reserve and the NOAA Office for Coastal Management worked together to map benthic habitats within Apalachicola Bay,...

  10. Short- and long-term sediment transport in western Bohai Bay and coastal areas

    Science.gov (United States)

    Feng, Huan; Zhang, Weiguo; Jia, Li; Weinstein, Michael P.; Zhang, Qiufeng; Yuan, Dekui; Tao, Jianhua; Yu, Lizhong

    2010-05-01

    Sediment cores (˜40-100 cm) were collected at 12 locations in the western Bohai Bay, the Haihe River estuary, the Yongding River estuary and the Tianjin Harbor, China, during 24-26 July 2007, and analyzed for 7Be and 210Pb activities. Due to localized hydrodynamic patterns and frequent disturbance from dredging activities, steady-state sedimentation features were not observed in this study. As demonstrated in the 7Be and 210Pb profiles, the temporal and spatial variations of these radionuclides support a non-steady state depositional environment in the study area. By comparing 7Be and 210Pb inventories in the sediments with those of the atmospheric source, we found that: 1) sediments dredged from the Tianjin Harbor or eroded from nearby estuarine and coastal areas are retained in the western Bohai Bay for relatively short intervals (several months), as reflected in the relatively high 7Be inventories in the western Bohai Bay; 2) over the long-term (years to decades), 210Pb inventories in the sediments imply that there is a net on-shore transport of sediments, and the sediments are mass-balanced in the entire study area. Overall, our results suggest that the sediments are retained in the estuaries and the western Bohai Bay despite local variability in sediment dynamics and disturbance due to human activities.

  11. Sediment accumulation in San Leandro Bay, Alameda County, California, during the 20th century - A preliminary report

    International Nuclear Information System (INIS)

    Major changes made in the configuration of San Leandro Bay, Alameda County, California, during the 20th century have caused rapid sedimentation within parts of the Bay. Comparison of bathymetric surveys indicates that sedimentation in the vicinity of the San Leandro Bay channel averaged 0.7 cm/annum between 1856 and 1984. Lead-210 data collected at four shallow water sites east of the San Leandro Bay channel indicated that sedimentation rates have averaged between 0.06 and 0.28 cm/annum. Because bioturbation of bottom sediments cannot be discounted, better definition of this range in sedimentation rates would require measuring the activity of lead-210 on incoming sediments. In addition to sediment deposited in the vicinity of the San Leandro Bay channel and open, shallow areas to the east, 850,740 cu m of sediment was deposited between 1948 and 1983 in an area dredged at the mouth of San Leandro Creek. All available data indicate that between 1,213,000 and 1,364,000 cu m of sediment was deposited in San Leandro Bay between 1948 and 1983. Sediment yield data from an adjacent drainage basin, when combined with inventories of lead-210 and cesium-137, indicate that most of the sediment deposited in San Leandro Bay is coming from resuspension of bottom sediments or from erosion of marshes or shorelines of San Leandro or San Francisco Bay. 31 refs., 7 figs., 4 tabs

  12. Sedimentation rate estimates in Sorsogon Bay, Philippines using 210Pb method

    International Nuclear Information System (INIS)

    Sorsogon Bay has experienced a long history of recurring harmful algal blooms over the past few years. In an attempt to establish a chronology of events in the sediment layer, lead-210 (210Pb) dating method has been utilized in estimating sedimentation rates from three selected areas along the bay. Based on the unsupported 210Pb data and by applying the Constant Initial Concentration (CIC) model, the calculated sedimentation rates were 0.8, 1.3 and 1.8 cm yr1 for sediment cores collected near the coastal areas of Castilla (SO-01), Sorsogon City (SO-07) and Cadacan River (SO-03), respectively. High sedimentation rates were measured in sediment cores believed to be affected from frequent volcanic ash releases and from areas near human settlement combined with intensive farming and agricultural activities. The collected sediments exhibited non-uniform down core values of dry bulk density and moisture content. This variation in measurements may indicate the general quality and composition of the sediment samples, i.e., amount of organic matter and grain size. The calculated sedimentation rates obtained provided an overview of the sedimentation processes and reflect the land use pattern around the bay which may help in understanding the history and distribution of materials and nutrient input relative to the occurrence of harmful algal bloom in the sediment columns. (author)

  13. A reevaluation of the late quaternary sedimentation in todos os Santos Bay (BA, Brazil

    Directory of Open Access Journals (Sweden)

    GUILHERME C. LESSA

    2000-12-01

    Full Text Available Todos os Santos Bay is a large ( 1000 km², structurally controlled tidal bay in northeast Brazil. Three main drainage basins debouch into the bay, providing a mean freshwater discharge of 200 m³/s (prior to 1985, or less than 1% of the spring tidal discharge through the bay mouth. Based on the result of several sedimentological studies performed in the 1970's, five surface sedimentary facies were identified inside the bay, namely i transgressive siliciclastic marine sand facies; ii transgressive bay sand-mud facies; iii a transgressive carbonate marine sand facies; iv regressive bay-mud facies, and v regressive fluvial sand facies. The spatial distribution of these facies would follow, somewhat closely, the hydrodynamic-energy distribution inside the bay. Seismic profiles along the bay bottom indicate the existence of several paleochannels, 5-10 m deep, blanketed at least by three different sedimentary units. The topmost sedimentary unit, 5-20 m thick, appears to be associated with the regressive bay-mud facies, and assuming that it was laid down within the last 5000 years, sedimentation rates for the central and northeastern part of the bay would average at 2,4 mm/y.

  14. Seasonal variation of iron speciation in a pearl-raising bay sediment by Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Ago Bay in Mie Prefecture, central Japan, is world-famous for the site of Mikimoto pearl culture, but recently the production of pearls has considerably declined. Environmental deterioration of the bay is suspected of having caused the decline. The periodic investigation into iron speciation of the bay sediment by 57Fe Moessbauer spectroscopy revealed its high pyrite (FeS2) content from the surface to the 20-cm depth. The pyrite in the surface sediment decreased only in spring, three months after the dissolved oxygen in the bottom water was at maximum. Such oxygen-consuming material as pyrite accumulated through long-term biotic activity is a most-likely explanation for the prolonged environmental deterioration of the bay, which appears in the high chemical oxygen demand (COD) of the sediment. (author)

  15. Sediment biogeochemistry in an East African mangrove forest (Gazi Bay, Kenya)

    NARCIS (Netherlands)

    Middelburg, J.J.; Nieuwenhuize, J.; Slim, F.J.; Ohowa, B.

    1996-01-01

    The biogeochemistry of mangrove sediments was investigated in several mangrove forest communities in Gazi Bay, a coastal lagoon in Kenya, Africa. Carbon dioxide fluxes, sediment median grain sizes, sedimentary organic carbon, nitrogen and phosphorus contents and pore-water characteristics (ammonium,

  16. Multielemental Analysis of Sediments from Havana Bay by Nuclear Analytical Techniques

    International Nuclear Information System (INIS)

    Instrumental Neutron Activation Analysis (INAA) and Gamma Activation Analysis (GAA) were employed to analyze the surface sediments and in 210Pb-dated profiles sediments from several sites on the Havana Bay, Cuba. INAA was performed in the IEA-R1 research reactor at IPEN, Sao, Brazil. GAA was performed in the MT-25 Microtron at Nuclear Reaction Laboratory at JINR, Dubna, Russia. Measurements of 34 heavy and Rare Earth 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. (Author)

  17. Intertidal sediments and benthic animals of Roebuck Bay, Western Australia

    OpenAIRE

    Pepping, M.; Piersma, T.; Pearson, G.; Lavaleye, M.

    1999-01-01

    Roebuck Bay near Broome (NW Australia) is with itsextensive tidal flats one of the foremost internationallyimportant sites for shorebirds in the Asia-Pacificflyway system. It is home to 150,000 shorebirds (or‘waders’) in the nonbreeding season, which suggeststhat the intertidal flats of the bay have abundantinvertebrate food to offer. To answer the question whyand how so many birds are able to make a living in themud of Roebuck Bay, about a quarter of the intertidalarea was quantitatively sam...

  18. Study on origin and sedimentary environment of marine sediments from Kii Channel, Hiroshima Bay and Tosa Bay

    International Nuclear Information System (INIS)

    The trace amounts of elements in the sediments of sea bottom in Kii Channel, Hiroshima Bay and Tosa Bay were determined quantitatively by the neutron activation analysis. The following facts were illustrated particularly from the quantitative analysis of scandium, rare earths, thorium and uranium: 1) It was known from Ce/La ratio that the geological feature in the west part of Japan is reflected in Kii Channel, Hiroshima Bay and Tosa Bay; 2) The rare-earth element pattern and La/Lu ratio suggest the fact that Kii Channel, Hiroshima Bay and Tosa Bay are essentially composed of the materials of which origin is land; 3) From the fact that Ce/La ratio in these sites are slightly under 1.0, these sites are considered to be affected mainly by the materials of which origin is land; 4) The sedimentary environment in the marine bottom of the Japanese coasts has been found to be mostly under a reductive state. (M.H.)

  19. Delineating incised stream sediment sources within a San Francisco Bay tributary basin

    OpenAIRE

    Bigelow, Paul; Benda, Lee; Pearce, Sarah

    2016-01-01

    Erosion and sedimentation pose ubiquitous problems for land and watershed managers, requiring delineation of sediment sources and sinks across landscapes. However, the technical complexity of many spatially explicit erosion models precludes their use by practitioners. To address this critical gap, we demonstrate a contemporary use of applied geomorphometry through a straightforward GIS analysis of sediment sources in the San Francisco Bay Area in California, USA, designed to support erosion r...

  20. The Levels and Distribution of Polycyclic Aromatic Hydrocarbons (PAH) Contamination in Bottom Sediments in Manila Bay

    OpenAIRE

    Evangeline Santiago

    1997-01-01

    The concentration levels of 18 PAH compounds extracted from 19 bottom sediments from the Limay Coast and 16 bottom sediments from the coast along Metro Manila and Cavitc Province of Manila Bay were determined by Gas Chromatography/Mass Spectrometry.The PAH contamination, the levels of other non-PAH petroleum hydrocarbon compounds. and total organic content in the sediments were assessed in relation to the location and depth of the sampling sites. The PAH concentrations and the levels of other...

  1. Sources of mercury to San Francisco Bay surface sediment as revealed by mercury stable isotopes

    Science.gov (United States)

    Gehrke, Gretchen E.; Blum, Joel D.; Marvin-DiPasquale, Mark

    2011-02-01

    Mercury (Hg) concentrations and isotopic compositions were examined in shallow-water surface sediment (0-2 cm) from San Francisco (SF) Bay to determine the extent to which historic Hg mining contributes to current Hg contamination in SF Bay, and to assess the use of Hg isotopes to trace sources of contamination in estuaries. Inter-tidal and wetland sediment had total Hg (Hg T) concentrations ranging from 161 to 1529 ng/g with no simple gradients of spatial variation. In contrast, inter-tidal and wetland sediment displayed a geographic gradient of δ 202Hg values, ranging from -0.30‰ in the southern-most part of SF Bay (draining the New Almaden Hg District) to -0.99‰ in the northern-most part of SF Bay near the Sacramento-San Joaquin River Delta. Similar to SF Bay inter-tidal sediment, surface sediment from the Alviso Slough channel draining into South SF Bay had a δ 202Hg value of -0.29‰, while surface sediment from the Cosumnes River and Sacramento-San Joaquin River Delta draining into north SF Bay had lower average δ 202Hg values of -0.90‰ and -0.75‰, respectively. This isotopic trend suggests that Hg-contaminated sediment from the New Almaden Hg District mixes with Hg-contaminated sediment from a low δ 202Hg source north of SF Bay. Tailings and thermally decomposed ore (calcine) from the New Idria Hg mine in the California Coast Range had average δ 202Hg values of -0.37 and +0.03‰, respectively, showing that Hg calcination fractionates Hg isotopes resulting in Hg contamination from Hg(II) mine waste products with higher δ 202Hg values than metallic Hg(0) produced from Hg mines. Thus, there is evidence for at least two distinct isotopic signals for Hg contamination in SF Bay: Hg associated with calcine waste materials at Hg mines in the Coast Range, such as New Almaden and New Idria; and Hg(0) produced from these mines and used in placer gold mines and/or in other industrial processes in the Sierra Nevada region and SF Bay area.

  2. Distribution and Ecological Risk Evaluation of Organochlorine Pesticides in Sediments from Xinghua Bay,China

    Institute of Scientific and Technical Information of China (English)

    Wang Yinghui; Qi Shihua; Xing Xinli; Gong Xiangyi; Yang Junhua; Xu Meihui

    2009-01-01

    The concentrations of organochlorine pesticides (OCPs) in sediments from Xinghua (兴化) Bay,Fujian(福建)Province,China,were determined.The OCP concentrations ranged from 2.48 to 313.88 ng/g,with a more serious contamination in the upper sediment But the OCP concentration in the upper layer was less than that in the lower sediment at the exit of the bay due to the influence of the Coriolis force.At the joint of the internal and external bays,OCPs accumulated abundantly because of freshwater and seawater mingling.The isomer percentage combined with isomer ratios Indicated that DDTs (dichlorodiphengltrichloroethanes) were mainly derived from long-term weather soils,while lin dane was introduced recently to the bay.The rivers flowing into the bay contributed more to DDT and HCH (hexachlorocyclohexane) contamination,especially at low tide.Compared with the corresponding quality guidelines from Ingersoll,the sediments from Xinghua Bay were likely to pose biological impairment and should be taken into account

  3. Sediment accumulation and mercury (Hg) flux in Avicennia marina forest of Deep Bay, China

    Science.gov (United States)

    Li, Ruili; Chai, Minwei; Guo, Meixian; Qiu, Guo Yu

    2016-08-01

    To investigate the rate of sediment accumulation and mercury (Hg) flux in Avicennia marina forest of Deep Bay, China, sediment cores were analyzed. The results showed that Hg concentrations were much higher at all depths compared to the background level. A high correlation between Hg and total organic carbon (TOC) indicated their similar anthropogenic origin. Sedimentation rate was estimated to be 1.38 cm a-1 by 210Pb geochronology. The increase in the mass sediment accumulation rates was rapid (range: 0.5-0.94 g cm-2 a-1), and the Hg fluxes ranged between 76 and 116 ng cm-2 a-1 during the last three decades. The reduction in both Hg concentrations and flux during the last decade may be due to the adoption of contamination control policies. Our results support the notion that the Hg fluxes determined from the sediment cores reveal the effects of anthropogenic influences from the areas around Deep Bay.

  4. DISTRIBUTION AND COMPOSITION OF PAHs IN SURFACE WATERS,POREWATER AND SEDIMENTS FROM XIAMEN WESTERN BAY

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Xiamen Western Bay's water and sediment quality were studied by determining the levels of sixteen polycyclic aromatic hydrocarbons (PAHs) in water, porewater and sediment samples from nine locations in the bay. Total PAH concentrations varied from 106 to 945 ng/l in water, below detection to 3548 ng/l in porewater, and 247 to 480 ng/g dry weight in surface sediments. PAHs levels in porewater were higher than those in surface water, due to the preference of these hydrophobic compounds for sedimentary phase instead of water. Such a concentration gradient implies a potential flux of pollutants from sediments to overlying water. The PAHs levels in sediments were one to several orders of magnitude lower than those in 1993, suggesting their decreased input in recent years and possible degradation with time.

  5. Assessment of Current Heavy Metal Contamination in the Sediments of Nuevitas Bay (Cuba)

    International Nuclear Information System (INIS)

    Surface sediments from six stations located in Nuevitas Bay (Cuba) were collected in order to determine concentrations of chromium; nickel, copper, zinc and lead by external standard method of X-ray fluorescence analysis (XRF). The level of contamination were calculated by several parameters like Enrichment factor (EF), Degree of contamination (DC), Modified degree of contamination (mCd) and the Sediment Quality Guidelines (SQGs). A 2003 study performed by Engineering Center of Environmental Management of Coast and Bays was used as a baseline in all obtained index in order to corroborate changes after one decade. The Cr content in sediments shows a strong variation across the studied stations (89-513 mg.kg-1, in contrast with the other elements studied. The comparison with Sediment Quality Guidelines and toxicity mean quotients shows that 100% of the Sediments are associated with the occasional presence of possible adverse effects to human health. (Author)

  6. Geochronology of anthropogenic radionuclides in Ribeira Bay sediments, Rio de Janeiro, Brazil

    International Nuclear Information System (INIS)

    Ribeira Bay is located approximately 130 km south of the city of Rio de Janeiro and receives discharges of liquid effluent from the Angra dos Reis nuclear power plant (NPP) site, where two pressurized water reactors are located. To test whether the presence of anthropogenic radionuclides in sediments in Ribeira Bay could be correlated to the NPP operations, we sampled seven sediment cores and determined accumulation rates and chronologies. Only one sediment core did not exhibit a superficial mixing layer; this sample was used for dating purposes. Cesium-137 and 207Bi were observed in this sediment profile, but their presence was associated with atmospheric fall-out rather than the nearby NPP. The exponential decay of 210Pb concentration with sediment layer depth was verified below a superficial mixing layer for all other sediment cores. Calculated accumulation rates ranged from 1.2 mm y-1 in the inner bay to 6.2 mm y-1 close to its entrance. - Graphical abstract: Display Omitted Highlights: → We have dated seven sediment cores on the region close to the Angra dos Reis nuclear power plant site. → Cs-137 and Bi-207 were detected and were used as a tool to validate the Pb-210 dating results. → The spatial variation of the Pb-210 flux indicates two main sources of sediments: the channel between Ilha Grande (Grande Island), and the continental and soil runoff from the adjacent hills.

  7. Geochronology of anthropogenic radionuclides in Ribeira Bay sediments, Rio de Janeiro, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho Gomes, Franciane de [Programa de Engenharia Nuclear, COPPE/UFRJ, Cidade Universitaria, Caixa Postal 68.509, 21945-970 Rio de Janeiro (Brazil); Godoy, Jose Marcus, E-mail: jmgodoy@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD), Caixa Postal 37750, Barra da Tijuca, 22642-970 Rio de Janeiro (Brazil); Departamento de Quimica, Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), Rua Marques de Sao Vicente 225, 22453-900 Rio de Janeiro (Brazil); Godoy, Maria Luiza D.P.; Carvalho, Zenildo Lara de [Instituto de Radioprotecao e Dosimetria (IRD), Caixa Postal 37750, Barra da Tijuca, 22642-970 Rio de Janeiro (Brazil); Tadeu Lopes, Ricardo [Programa de Engenharia Nuclear, COPPE/UFRJ, Cidade Universitaria, Caixa Postal 68.509, 21945-970 Rio de Janeiro (Brazil); Sanchez-Cabeza, Joan-Albert; Osvath, Iolanda [IAEA Marine Environment Laboratories, 4 Quai Antoine Premier, MC98000 Principality of Monaco (Monaco); Drude de Lacerda, Luiz [Laboratorio de Ciencias do Mar, Universidade Federal do Ceara, Fortaleza, Ceara (Brazil)

    2011-09-15

    Ribeira Bay is located approximately 130 km south of the city of Rio de Janeiro and receives discharges of liquid effluent from the Angra dos Reis nuclear power plant (NPP) site, where two pressurized water reactors are located. To test whether the presence of anthropogenic radionuclides in sediments in Ribeira Bay could be correlated to the NPP operations, we sampled seven sediment cores and determined accumulation rates and chronologies. Only one sediment core did not exhibit a superficial mixing layer; this sample was used for dating purposes. Cesium-137 and {sup 207}Bi were observed in this sediment profile, but their presence was associated with atmospheric fall-out rather than the nearby NPP. The exponential decay of {sup 210}Pb concentration with sediment layer depth was verified below a superficial mixing layer for all other sediment cores. Calculated accumulation rates ranged from 1.2 mm y{sup -1} in the inner bay to 6.2 mm y{sup -1} close to its entrance. - Graphical abstract: Display Omitted Highlights: > We have dated seven sediment cores on the region close to the Angra dos Reis nuclear power plant site. > Cs-137 and Bi-207 were detected and were used as a tool to validate the Pb-210 dating results. > The spatial variation of the Pb-210 flux indicates two main sources of sediments: the channel between Ilha Grande (Grande Island), and the continental and soil runoff from the adjacent hills.

  8. Improving lakebed sediment quality in an urban estuary, Presque Isle Bay, Lake Erie, USA

    Science.gov (United States)

    Foyle, A. M.; Norton, K. P.

    2007-12-01

    Presque Isle Bay, Lake Erie, is a microtidal freshwater estuary on the North American Great Lakes. It is one of 40 remaining environmental Areas of Concern (AoCs) on the Great Lakes that have one or more water, habitat, or sediment quality impairments as defined by the International Joint Commission. In-situ natural capping using sediment from to-be-remediated watersheds and other sources is being considered as the most feasible means of remediating contaminated sediments in the estuary. A multi-decade sediment budget shows that, when localized anthropogenic effects are accounted for, the estuary net-accumulated sediment over time from three major sources: the Lake Erie littoral system (20%), streams (25%), and bank erosion and bluff recession (41%). The non-stream sources supply environmentally clean sediment from ancient coastal deposits along the shoreline, and from the modern littoral system. However, organic and metallic contaminants are supplied by streams and run-off and remain a remediation challenge. From a geological perspective, natural capping of contaminated sediment over the next several decades is a viable solution for the majority of the bay. The mechanism may not work effectively in all areas because approximately 25% of the bay floor is moderately net- erosional or accumulates sediments very slowly.

  9. Multielemental analysis of surface sediments in Havana bay (Cuba) using X-ray fluorescence

    International Nuclear Information System (INIS)

    Multielemental Analysis was performed in Superficial Sediments in Havana Bay. Twenty one samples were analysed by Dispersive Energy X- Ray Fluorescence using an spectrometer based on Si (Li) semiconductor detector an a 109 Cd source. The results showed a similar behaviour in the levels of contamination related with neutron activation analysis. The data suggest that an anthropogenic input into the bay from domestic sewage and industries occurred. (Full text)

  10. Constraints on sediment transfer from the Andes to the coast of northern Chile

    Science.gov (United States)

    Binnie, Steven; Liermann, Ariane; Dunai, Tibor; Dewald, Alfred; Heinze, Stefan

    2013-04-01

    While rates of denudation have been suggested as having the potential to link tectonic processes with climate in many settings, the roles that sediment transport must also play have been largely neglected. It is the transport, or not, of eroded material, not necessarily the rate at which that material is produced which is the critical factor in many models of tectonic-climatic interactions. The notable lack of sediment in sections of the Peru-Chile trench has been implicated as a key control of subduction zone processes and consequently Andean mountain building, but little empirical data on sediment transport in the region exists. Here, we present the initial results of a study aiming to constrain the westward transfer of sediment from the Andes Mountains to the Pacific Coast of northern Chile by using in situ-produced cosmogenic nuclides. Fluvial sediments were collected at the mouths of several large catchments between 19° S and 26° S, where they drain into the Pacific, and also from upstream locations within each catchment. Sample sites were selected in order to investigate the cosmogenic nuclide derived basin-averaged denudation rates of the western flank of the Andes, and to compare this with the cosmogenic nuclide concentrations of fluvial sediments further downstream where the catchments exit to the coast. A simplistic interpretation of the cosmogenic 10Be concentrations as denudation rates gives results varying between ~10 and 300 m/Myr. We would expect the most rapid erosion to occur on the steeper, wetter western Andean flank and for slower erosion to be recorded from the more gentle sloping, hyperarid/arid regions between the foothills of the Andes and the Pacific coast. This pattern is observed in some basins but in others the nuclide concentrations imply the opposite, with several-fold higher erosion rates measured for the large catchments sampled at the coast in comparison to their mountainous Andean headwaters. One explanation for this unusual

  11. The distribution characteristics of rare metal elements in surface sediments from four coastal bays on the northwestern South China Sea

    Science.gov (United States)

    Wang, Shuhong; Li, Jin; Wu, Shuzhuang; Yan, Wen; Huang, Weixia; Miao, Li; Chen, Zhong

    2016-02-01

    The distribution of rare metal elements (Zr, Sn, Ti, Y, Nb, Ta, Ce, La, Nd and Th) in surface sediments from four bays along the northwestern coast of the South China Sea allowed infer their main controlling factors and their mineralization potential as metals placer. The results revealed that their contents in surface sediments are very variable but show a clear geographic regularity. The average content of all elements in those areas decreases from the East to the West, with the minimum value of all elements in Leizhou Bay, the maximum value of Zr, Y, La, Ce, Nd and Th in Zhanjiang Bay, and the maximum values of Sn, Ti, Nb and Ta in Hailing Bay. The relative enrichment of these elements in two easternmost bays (Hailing Bay and Shuidong Bay) are attributed to the southwest alongshore current, which drain and transport terrigenous sediments from the granite region of the South China into these two bays. The correlation results between all element contents and fine sediment fraction (analysis shows that sediments from Hailing Bay may contain abundant zircon, cassiterite, ilmenite (or rutile), xenotime, monazite, niobium tantalite and other rare metal minerals, with a good prospect as a rare metal placer resource, and the zircon, xenotime and monazite may also have good metallogenic prospects in Shuidong Bay and in the local area of Zhangjian Bay.

  12. Trace metal variability in coastal waters of San Jorge Bay, Antofagasta, Chile: An environmental evaluation and statistical approach to propose local background levels.

    Science.gov (United States)

    Valdés, J; Román, D; Guiñez, M; Rivera, L; Ávila, J; Cortés, P; Castillo, A

    2015-11-15

    Between 2008 and 2011, twelve metals from 384 coastal waters samples from San Jorge Bay (Antofagasta, northern Chile) were collected and analyzed. The goal was to evaluate the quality of the bay's water bodies according to the current Chilean Quality Guideline and to establish background levels for these metals. The result suggests that the coastal waters of San Jorge Bay are of very good quality suitable for recreational activities involving human body contact. The natural background thresholds established for this bay were significantly lower than primary and secondary water quality guidelines. The distribution of Cu, Zn and Pb, along the bay's coastline provides evidence of the effects of industrial activity. Both situations suggest that the threshold indicated in the environmental guidelines of the Chilean legislation may be overestimated and do not represent pollution-free environments. PMID:26365501

  13. Polycyclic aromatic hydrocarbons in surface sediments of the Zhelin Bay in the South China Sea

    Institute of Scientific and Technical Information of China (English)

    DONG Qiaoxiang; HUANG Hong; HUANG Changjiang

    2007-01-01

    This study examined the concentrations of polycyclic aromatic hydrocarbons (PAHs) in surface sediments collected in July 2004 from eight stations in the Zhelin Bay, one of the most important bays for large-scale mariculture in Guangdong Province. Thirteen individual parent PAH compounds were identified using high performance liquid chromatography with UV detection. The overall average concentration of total PAHs was 477.0 ng/g, ranging from 146.1 to 928.8 ng/g. Low molecular mass PAHs with two to three rings (e.g., acenaphthene) were dominant in each sample. The PAH concentration varied among sampling stations, with the highest concentration observed at bay outlets and the lowest found at stations outside the bay. Ratios of low to high molecular mass PAHs and fluoranthene to pyrene were used to determine the origin of PAHs, and results indicated mainly petroleum-derived contamination. Compared with other bays and harbors around the world, the total concentrations of PAHs in surface sediments at the Zhelin Bay are moderate, but this does not exclude the possibility of potential impact on human consumers because some strong carcinogenic PAHs with high molecular mass were found at the station with a nearby caged-fish and oyster farm. Long-term monitoring of PAH contamination in the Zhelin Bay is recommended to reduce the potential toxicological effects on aquatic: organisms and humans.

  14. Indicators and impact analysis of sediment from the Changjiang Estuary and East China Sea to the Hangzhou Bay

    Institute of Scientific and Technical Information of China (English)

    WANG Hong; FAN Wei; YUN Caixing

    2004-01-01

    Based on the historical evolution of the Hangzhou Bay, by making use of the conclusions made by the previous research workers and the integration of concrete data, five distinct impact indicators of the sediment from the Changjiang Estuary and the East China Sea to the Hangzhou Bay are summarized. Numerical calculation and analysis indicate that the scouring and deposition of seabed in the Hangzhou Bay are subject to the direct impact of the evolution of the Changjiang Estuary, and the growth and decline and the direction of the sandy bar at Nanhuizui give traces to the sediment transport between the Changjiang Estuary and the Hangzhou Bay. The transport of sediment from the Changjiang Estuary to the Hangzhou Bay occurs mainly in winter and spring seasons and the increase of the Changjiang River runoff and the decrease of sediment charge have caused scouring in the northern coast of the Hangzhou Bay and the seabed erosion along the frontal margin of the Changjiang River Delta.

  15. Assessment of heavy and trace element pollution in surface sediments from Havana Bay

    International Nuclear Information System (INIS)

    Instrumental Neutron Activation analysis (INAA) and Energy Dispersive X-Ray Fluorescence (ED-XRF) analysis were employed to analyze the surface sediments from several sites at the Havana Bay, Cuba. Concentrations of 29 heavy and trace elements in the sediments are at first time reported including an important group of REE (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu). The normalization of the results shows 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. (Author)

  16. The levels and distribution of polycyclic aromatic hydrocarbons (PAH) contamination in bottom sediments in Manila Bay

    International Nuclear Information System (INIS)

    The concentration levels of 18 PAH compounds extracted from 19 bottom sediments from the Limay coast and 16 bottom sediments from the coast along Metro Manila and Cavite province of Manila Bay were determined by gas chromatography/mass spectrometry. The PAH contamination, the levels of other non-PAH petroleum hydrocarbon compounds, and total organic content in the sediments were assessed in relation to the location and depth of the sampling sites. The PAH concentrations and the levels of other petroleum hydrocarbons in the sediments showed that the spatial distribution of PAH and other hydrocarbon contamination in Manila Bay is largely dependent on the proximity of the sediment deposition site to known point sources of pollution. On the western side, the highest levels of PAH contamination normalized to % TOC (1.29 x 104 at L12, 1.28 x 104 at L16, 0.55 at L13, and 0.54 at L15) were obtained from sediments collected at deposition sites near the outfall of the Petron Oil Refinery. On the eastern side, sediments located at the effluent zones of the Paranaque and Malabon rivers showed excessively higher levels of PAH normalized to %TOC (3.32 x 104 and 2.87 x 104; respectively) compared to those obtained from other sites in the area. The PAH contamination in the sediments from Manila Bay is dominated by alkylated naphthalenes and phenanthrenes which are associated with petrogenic sources. This indicates that the surface sediments in Manila Bay are exposed to chronic contamination of petroleum hydrocarbons introduced mainly by direct spillage on the western side and by urban run-off on the eastern side. (Author)

  17. The Levels and Distribution of Polycyclic Aromatic Hydrocarbons (PAH Contamination in Bottom Sediments in Manila Bay

    Directory of Open Access Journals (Sweden)

    Evangeline Santiago

    1997-12-01

    Full Text Available The concentration levels of 18 PAH compounds extracted from 19 bottom sediments from the Limay Coast and 16 bottom sediments from the coast along Metro Manila and Cavitc Province of Manila Bay were determined by Gas Chromatography/Mass Spectrometry.The PAH contamination, the levels of other non-PAH petroleum hydrocarbon compounds. and total organic content in the sediments were assessed in relation to the location and depth of the sampling sites. The PAH concentrations and the levels of other petroleum hydrocarbons in the sediments showed that the spatial distribution of PAH and other hydrocarbon contamination in Manila Bay is largely dependent on the proximity of the sediment deposition site to known point sources of pollution. On the western side, the highest levels of PAH contamination normalized to % TOC (1.29 X 104 at Ll2, 1.28 x 104 at Ll6, 0.55 at Ll3, and 0.54 at Ll5 were obtained from sediments collected at deposition sites near the outfall of the Petron Oil Refinery. On the eastern side. sediments located at the effiuent zones of the Paranaque and Malabon Rivers showed excessively higher levels of PAH normalized to % TOC (3.32 x 104 and 2.87 x 104: respectively compared to those obtained from other sites in the area.The PAH contamination in the sediments from Manila Bay is dominated by alkylated naphthalenes and phenanthrenes which are associated with petrogenic sources. This indicates that the surface sediments in Manila Bay are ex-posed to chronic contamination of petroleum hydrocarbons introduced mainly by direct spillage on the western side and by urban run-off on the eastern side.

  18. Anthropogenic Pb input into Bohai Bay, China: Evidence from stable Pb isotopic compositions in sediments

    Science.gov (United States)

    Ning-jing, Hu; Peng, Huang; Hui, Zhang; Ai-mei, Zhu; Ji-hua, Liu; Jun, Zhang; Lian-hua, He

    2015-10-01

    To investigate the source of Pb within Bohai Bay, Pb concentrations and Pb isotopic compositions (204Pb, 206Pb, 207Pb, and 208Pb) of surface sediments in this area were determined. The Pb concentration in this bay varied widely from 6.9 to 39.2 μg/g (average: 21.8±7.8 μg/g), and the Pb isotopic compositions ranged from 0.8338 to 0.8864 (average: 2.0997±0.0180) for 208Pb/206Pb and from 2.0797 to 2.1531 (average: 0.8477±0.0135) for 207Pb/206Pb, presenting in three distinct clusters. The Pb isotopic ratios of sediments from the northeastern (NE zone) and northwestern (NW zone) coastal areas were significantly influenced by anthropogenic sources such as coal combustion and automobile emission. In sediments from the central and southern Bohai Bay (C-S zone); however, Pb mainly originated from the Yellow River catchment, as a result of lithogenic sediment (from rock weathering) accumulation. The Pb isotopic ratios further indicate that, apart from riverine inputs, the neighboring large-scale ports and aerosols significantly contributed to the anthropogenic Pb contained in these sediments. Pb contamination in the Haihe and Luanhe river mouths as well as in the regions near ports is also suggested from anthropogenic enrichment factors. As cities and ports continue to develop around Bohai Bay, a long-term extensive sewage monitoring program is highly recommended.

  19. Suspended sediment dynamics in Queen Inlet, Glacier Bay, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Hoskin, C.M.; Burrell, D.C.; Freitag, G.R.

    1976-01-01

    Suspended sediment input from the major melt-water stream of Carroll Glacier was measured to be 111 x 10/sup 6/ g/hr (dry wt). In the water column of Queen Inlet this sediment formed a surface plume and discrete turbid layers with suspended sediment loads exceeding 500 mg/l. Rate of sediment accumulation near the inlet floor head was measured by sediment trap to be 5 mg/cm/sup 2//hr (dry wt) in late June, and 70 mg/cm/sup 2//hr in late September. Average rate of accumulation for trapped sediment was 1.8 mm wet sediment/hr, equivalent to about 2.6 m/melt-water year. Diversity and abundance of the macrobenthos increased from one species, one individual (total blotted wet wt .003 g) at the head to ten species, seventy-six individuals (total blotted wet wt 1.216 g) 8 km away at the fjord mouth.

  20. Suspended-sediment dynamics in the tidal reach of a San Francisco Bay tributary

    Science.gov (United States)

    Shellenbarger, Gregory G.; Downing-Kunz, Maureen A.; Schoellhamer, David H.

    2015-11-01

    To better understand suspended-sediment transport in a tidal slough adjacent to a large wetland restoration project, we deployed continuously measuring temperature, salinity, depth, turbidity, and velocity sensors in 2010 at a near-bottom location in Alviso Slough (Alviso, California, USA). Alviso Slough is the downstream reach of the Guadalupe River and flows into the far southern end of San Francisco Bay. River flow is influenced by the Mediterranean climate, with high flows (˜90 m3 s-1) correlated to episodic winter storms and low base flow (˜0.85 m3 s-1) during the summer. Storms and associated runoff have a large influence on sediment flux for brief periods, but the annual peak sediment concentrations in the slough, which occur in April and May, are similar to the rest of this part of the bay and are not directly related to peak discharge events. Strong spring tides promote a large upstream sediment flux as a front associated with the passage of a salt wedge during flood tide. Neap tides do not have flood-directed fronts, but a front seen sometimes during ebb tide appears to be associated with the breakdown of stratification in the slough. During neap tides, stratification likely suppresses sediment transport during weaker flood and ebb tides. The slough is flood dominant during spring tides, and ebb dominant during neap tides. Extreme events in landward (salt wedge) and bayward (rainfall events) suspended-sediment flux account for 5.0 % of the total sediment flux in the slough and only 0.55 % of the samples. The remaining 95 % of the total sediment flux is due to tidal transport, with an imbalance in the daily tidal transport producing net landward flux. Overall, net sediment transport during this study was landward indicating that sediment in the sloughs may not be flushed to the bay and are available for sedimentation in the adjacent marshes and ponds.

  1. A study of environmental analysis of Havana Bay sediments using neutron activation analysis

    International Nuclear Information System (INIS)

    Surface sediments from the Havana Bay (Cuba) were analyzed by instrumental neutron activation analysis (INAA). Concentrations of 23 heavy and trace elements in the sediments were reported, including for the first time, an important group of REE (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu). The normalization of the results for a reference metal shows that an anthropogenic Sb, Ba, As, Cr and Zn inputs are due to discharges of sewage and industrial effluent. (author)

  2. Potentially Toxic Metal and Metalloid Fractionation Contamination in Sediments of Daya Bay, South China Sea

    OpenAIRE

    Cao, L. L.; Yang, J; P. Wang; Wang, L.; Tian, H. T.; Zou, M. K.; Xie, J.

    2015-01-01

    The metal profiles in sediments of the Daya Bay (DYB) in China were established using sequential extraction protocols proposed by the European Community Bureau of Reference (BCR). The surface sediment samples from 23 representative stations were collected in 2011 and were analysed to evaluate the mobility and bioavailability of a suite of potentially toxic metals (Cr, Cu, Ni, Zn, Pb and Cd) and metalloid (As). The obtained ranking order of migration and transformation, and the degree of pollu...

  3. Heavy Metals Pollution and Pb Isotopic Signatures in Surface Sediments Collected from Bohai Bay, North China

    OpenAIRE

    Bo Gao; Jin Lu; Hong Hao; Shuhua Yin; Xiao Yu; Qiwen Wang; Ke Sun

    2014-01-01

    To investigate the characteristics and potential sources of heavy metals pollution, surface sediments collected from Bohai Bay, North China, were analyzed for the selected metals (Cd, Cr, Cu, Ni, Pb, and Zn). The Geoaccumulation Index was used to assess the level of heavy metal pollution. Pb isotopic compositions in sediments were also measured to effectively identify the potential Pb sources. The results showed that the average concentrations of Cd, Cr, Cu, Ni, Pb, and Zn were 0.15, 79.73, 2...

  4. Historical contamination of Mississippi River Delta, Tampa Bay, and Galveston Bay sediments. National status and trends program for marine environmental quality: Technical memo (Final)

    Energy Technology Data Exchange (ETDEWEB)

    Presley, B.J.; Wade, T.L.; Santschi, P.; Baskaran, M.

    1998-03-01

    In order to obtain sediment which has accumulated over the past 100 years or so, 50--80 cm long sediment cores were collected from the submarine Mississippi River Delta, Galveston Bay, Texas and Tampa Bay, Florida. The cores were extruded and sliced into 1 cm thick sections which were then radiometrically age dated and analyzed for those organic compounds and trace metals suspected of being contaminants in the sampling areas.

  5. Preservación y abundancia de escamas de peces en sedimentos del margen continental de Chile (21-36° S Fish scale preservation and abundance in sediments from the continental margin off Chile (21-36° S

    Directory of Open Access Journals (Sweden)

    JAVIER A DÍAZ-OCHOA

    2008-12-01

    (Mo/Al, S/Al, Fe/Al using eight sediment cores taken from sites under the influence of the oxygen minimum zone off Chile (Iquique: 20°15' S, Mejillones Bay: 23° S, Concepción: 36° S. Off northern Chile (Iquique and Mejillones, fish scales from anchovy (Engraulis ringens and the Myctophidae family are dominant (mean = 90 and 120 scales 1,000 cm-3, respectively, whereas off central-southern Chile (Concepción, jack mackerel (Trachurus murphy scales are the most abundant (mean = 140 scales 1,000 cm-3. The abundance of hake (Merluccius gayi gayi and sardine (Sardinops sagax scales is approximately one order of magnitude lower than that of anchovy or jack mackerel. In general, the highest valúes and widest ranges of variation in the Mo/Al, S/Al, and Fe/Al ratios are found in Mejillones (Mo/Al ~ 0.8-12 mg g-1, S/Al 0.2-4.6 g g-1, Fe/Al 0.3-0.7 g g-1, followed by Iquique (Mo/Al ~ 0.2-1.8, S/Al 0.2-0.7, Fe/Al 0.5-0.8; Concepción has lower, less variable valúes (Mo/Al ~ 0.07, S/Al ~ 0.15, Fe/Al ~ 0.5. According to the Mo/Al ratio, used as an indicator of paleo-oxygenation, reducing conditions in the Mejillones Bay and Iquique sediments are relatively more intense than in those off Concepción. At all three sampling sites, the relationship between the abundance of anchovy scales and the logarithm of the Mo/Al ratio is statistically significant (r² = 0.46, P 1 mg g-1.

  6. Historical contamination of PAHs, PCBs, DDTs, and heavy metals in Mississippi River Delta, Galveston Bay and Tampa Bay sediment cores.

    Science.gov (United States)

    Santschi, P H; Presley, B J; Wade, T L; Garcia-Romero, B; Baskaran, M

    2001-07-01

    Profiles of trace contaminant concentrations in sediment columns can be a natural archive from which pollutant inputs into coastal areas can be reconstructed. Reconstruction of historical inputs of anthropogenic chemicals is important for improving management strategies and evaluating the success of recent pollution controls measures. Here we report a reconstruction of historical contamination into three coastal sites along the US Gulf Coast: Mississippi River Delta, Galveston Bay and Tampa Bay. Within the watersheds of these areas are extensive agricultural lands as well as more than 50% of the chemical and refinery capacity of the USA. Despite this pollution potential, relatively low concentrations of trace metals and trace organic contaminants were found in one core from each of the three sites. Concentrations and fluxes of most trace metals found in surface sediments at these three sites, when normalized to Al, are typical for uncontaminated Gulf Coast sediments. Hydrophobic trace organic contaminants that are anthropogenic (polycyclic aromatic hydrocarbons, DDTs, and polychlorinated biphenyls) are found in sediments from all locations. The presence in surface sediments from the Mississippi River Delta of low level trace contaminants such as DDTs, which were banned in the early 1970's, indicate that they are still washed out from cultivated soils. It appears that the DDTs profile in that sediment core was produced by a combination of erosion processes of riverine and other sedimentary deposits during floods. Most of the pollutant profiles indicate that present-day conditions have improved from the more contaminated conditions in the 1950-1970's, before the advent of the Clean Water Act. PMID:11488356

  7. Trapping of fine sediment in a semi-enclosed bay, Palau, Micronesia

    Science.gov (United States)

    Golbuu, Yimnang; Victor, Steven; Wolanski, Eric; Richmond, Robert H.

    2003-08-01

    Airai Bay, Palau, is a small (3 km 2), semi-enclosed, mangrove-fringed, meso-tidal, coral lagoon on the southeast coast of Palau. It drains a small catchment area (26 km 2) of highly erodible soils in an area with high annual rainfall (3.7 m). River floods are short-lived and the sediment load is very large, with suspended fine sediment concentration exceeding 1500 mg l -1. The resulting river plume is about 2 m thick. The brackish water residence time is about 7 days; during this period the plume remains a distinct surface feature even after river runoff has ceased. About 98% of the riverine fine sediment settles in Airai Bay, of which about 15-30% is deposited in the mangroves during river floods. This mud remains trapped in Airai Bay because the bay is protected from ocean swells and the tidal currents and locally generated wind waves are too small to resuspend the mud in quantity. The mud is smothering coral reefs, creating a phase shift from coral to fleshy algae dominance, and is even changing habitats by creating mud banks. The persistence of Airai Bay marine resources may not be possible without improved soil erosion control in the river catchment.

  8. Hydrodynamic and Sediment Transport Processes in Long Bay of the Carolinas

    Science.gov (United States)

    Ma, Y.; Xu, K.; He, R.; Wren, P. A.; Gong, Y.; Quigley, B.; Tarpley, D.

    2010-12-01

    The coastline along Long Bay of the Carolinas is a fast-growing and heavily-developed area supporting local populations, infrastructure, and a large tourism industry. Myrtle Beach and its adjacent sandy beaches are popular tourist destinations that attract millions of visitors each year, representing one of the state’s most essential natural resources. The economy of this region is closely related to the stability of the sandy beaches, which are vulnerable to coastal erosion during severe storm events. Quantifying the sediment transport processes in the nearshore and inner continental shelf regions is thus critical for both understanding the regional sediment budget and implementing effective coastal management. As a first step toward investigating the sediment transport processes, a three-dimensional coupled hydrodynamic-sediment transport model for Long Bay in the Carolinas has been developed. The model, based on the Regional Ocean Modeling System (ROMS), spans from Cape Fear estuary in NC to Winyah Bay estuary in SC. It considers the delivery of fluvial sediment from the Cape Fear and Pee Dee Rivers, resuspension from seabed, and transport of suspended sediment by ambient currents and waves calculated using Simulating WAve Nearshore model (SWAN). Our model simulations are driven by observed wind fields, which were collected at nearby meteorological stations maintained by National Data Buoy Center as well as at six buoys by the Palmetto Wind Research Project at Coastal Carolina University. Spatially varying sea bed conditions consisting of both hard bottoms and sandy bodies are applied in the calculation. The model is one-way nested inside a large-scale coastal circulation model that covers both the Middle Atlantic Bight and the South Atlantic Bight and provides dynamically consistent and numerically accurate circulation open boundary conditions. Modeling results indicate both wind-driven currents and storm-induced waves are capable of resuspending sandy

  9. ESTRUCTURA DE LA MACROFAUNA EN AMBIENTES OXICOS DE BAHIA COLIUMO, REGION DEL BIO-BIO, CHILE CENTRAL STRUCTURE OF MACROFAUNA IN OXIC ENVIRONMENTAL OFF BAY COLIUMO, BIO-BIO REGION, CENTRAL CHILE

    Directory of Open Access Journals (Sweden)

    Karina Neira

    2007-01-01

    Full Text Available Se analizó la densidad, biomasa, diversidad y riqueza de especies de la macrofauna bentónica (³500 mm en ambientes óxicos (> 0.5 ml L-1 en Bahía Coliumo (36º32`S, 72º57`W, Chile central. En un transecto de cinco estaciones, entre 3,6 y 22,5 m de profundidad, fueron recolectadas muestras de sedimento con una draga tipo Van veen de 0,051 m², a bordo de la embarcación científica L/C Kay-Kay. A partir de las muestras de sedimento se determinó, el porcentaje de materia orgánica total, el tamaño de grano, densidad y biomasa de la macrofauna. Adicionalmente, se tomaron muestras de agua para el análisis de oxígeno disuelto de fondo, temperatura y salinidad. Las densidades de la macrofauna total fluctuaron entre 1111 y 11183 ind m-2. En tanto, los valores de biomasa alcanzaron 9,9 y 252,86 g m-2. Del total de la macrofauna 29 especies fueron identificadas. Los valores más altos de diversidad (3,23 coinciden con los valores más bajos de dominancia y uniformidad. Los parámetros de diversidad no mostraron una relación lineal con la profundidad. Los poliquetos fueron el grupo dominante (51,8%, seguido de los crustáceos (41% y moluscos (6,8%. Adicionalmente, a través del análisis BIOENV, se observó que el porcentaje de arena y el contenido de materia orgánica fueron los principales factores ambientales que regulan la estructura de la macrofauna de Bahía Coliumo.The density, biomass, diversity and species richness of macrofaunal benthic (³500 mm in oxic environment (> 0.5 ml L-1 off Bay Coliumo (36º32`S, 72º57`W, Chile were analyzed. One transect of five stations between 3.6 and 22.5 m of depth were collected samples of sediments with a dredged Van veen of 0.051 m²a board R/V Kay-Kay in August (winter of 2004. From sediment sample the organic matter percent, size of grain, density and biomass of the macrofauna were determined. Additionally, were taken water column samples for analyses of dissolved oxygen of bottom, temperature and

  10. Chronology of sedimentation in Cienfuegos bay, elucidated from 210Pb and 137Cs

    International Nuclear Information System (INIS)

    This article present the results of the use of radiotracers in geochronology technique for evaluate the anthropogenic impact on Cienfuegos Bay, Cuba. The excess 210Pb and 137Cs radionuclides were measurements on one sediment corer collected in Cienfuegos Bay using a gravity core. Each core was sliced and pre treatment for gamma spectrometric measurements and other complementary analyses. It was applied the Constant Rate Supply model for dating the 210Pb profile and it was used the 137Cs as an alternative method for dating calibration. The results show a good agreement between CRS method's results and 1963's 137Cs peak. Spatial and temporal evaluation of the radiotracers profiles have shown that sedimentation rate have changed in the last fourth years and it is associated to the economical and industrial development. It was demonstrated the significance of radiotracers in environmental impact on estuaries and semi enclosed bays

  11. Assessment of the state of pollution by heavy metals in the surficial sediments of Algiers Bay

    International Nuclear Information System (INIS)

    Sediment samples were collected at 33 stations from Algiers Bay to determine potential sources of pollution. The analyses were made with X-ray fluorescence (XRF). The results give information about the level of concentrations for Cr, Mn, Fe, Cu, Zn and Pb. Except for Mn and Fe which present a particular distribution (unrelated to the sedimentary facies), the distribution of the different heavy metals is irregular and depends on the bay morphology. The level of pollution by heavy metals of the bottom sediments in Algiers Bay has been shown to be significant compared with that of Surkouf, considered to be a region with low anthropogenic activity. Comparison with previous studies shows: no dependence of the assignation of Mn and Fe on sedimentary facies; high concentration of Cu, Pb and Zn in the vases and high concentration of Cr in the sands with a fine fraction between 50% and 75%

  12. QUANTIFYING SEDIMENT CONTRIBUTIONS TO THE GUÁNICA BAY PUERTO RICO

    Science.gov (United States)

    The island of Puerto Rico faces considerable challenges regarding sustainable land use and effects of land use on adjacent freshwater and marine ecosystem services. In watersheds feeding Guánica Bay (southwestern Puerto Rico), increased soil erosion and sediment loading to strea...

  13. Particle fluxes in the Bay of Bengal measurEd. by sediment traps

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaswamy, V.; Parthiban, G.

    Particle fluxes were measured between October, 1987 and March, 1988 using six automated time series sediment traps at three locations in the northern, central and southern Bay of Bengal. Particle fluxes varied between 16.8 and 345 mg m/2 day/1...

  14. Photobacterium marinum sp. nov., a marine bacterium isolated from a sediment sample from Palk Bay, India

    Digital Repository Service at National Institute of Oceanography (India)

    Srinivas, T.N.R.; VijayaBhaskar, Y.; Bhumika, V.; AnilKumar, P.

    The novel, cream colored, Gram-staining-negative, rod-shaped, motile bacteria, designated strains AK15 sup(T) and AK18, were isolated from sediment samples collected from Palk Bay, India. Both strains were positive for arginine dihydrolase, lysine...

  15. Consolidation and strength properties of calcareous sediments from Kaneohe and Kailua Bays, Hawaii

    Digital Repository Service at National Institute of Oceanography (India)

    Brandes, H.G.; Khadge, N.H.; Nakayama, D.D.

    Shallow-water sediments found near the shorelines of Kaneohe and Kailua bays on the island of Oahu, an area that has seen continuous development over the last 40 years, were tested to determine the influence of terrigenous input on the geotechnical...

  16. Lithogenic fluxes in the Bay of Bengal measured by sediment traps

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaswamy, V.; VijayKumar, B.; Parthiban, G.; Ittekkot, V.; Nair, R.R.

    after removal of carbonates with phosphoric acid. Duplicate anlayses were carried out on all samples, and the variation was less than 1% of the mean. On another aliquot, carbonate Lithogenic fluxes in the Bay of Bengal measured by sediment traps 797...

  17. EFFECTS OF DDT SEDIMENT-CONTAMINATION ON MACROFAUNAL COMMUNITY STRUCTURE AND COMPOSITION IN SAN FRANCISCO BAY

    Science.gov (United States)

    The objectives of this study were to determine the effects of sediment contamination on the benthic macrofauna and to predict macrofaunal changes following remediation at a Superfund (uncontrolled hazardous waste) site in San Francisco Bay, CA, USA. DDT and its metabolites (sumDD...

  18. Oil characterization and distribution in shoreline sediments of Pensacola Bay, Florida following the Deepwater Horizon spill

    Science.gov (United States)

    Barrier islands of Northwest Florida were heavily oiled during the Deepwater Horizon spill, but less is known about the impacts to the shorelines of the associated estuaries. Shoreline sediment oiling was investigated at 18 sites within the Pensacola Bay, Florida system prior to...

  19. Modeling Water and Sediment Quality in Two California Bays

    OpenAIRE

    Stolzenbach, Keith; McWilliams, James

    2002-01-01

    While polluted coastal bays have often been studied observationally, less effort has focused on developing computer models that simulate the processes that disperse, depositand resuspend pollution and contaminants on the seabed. Such models would not only help interpret observational data but would also benefit resource managers charged with upholding state and federal clean water laws.

  20. Respiratory disease and particulate air pollution in Santiago Chile: Contribution of erosion particles from fine sediments

    International Nuclear Information System (INIS)

    Air pollution in Santiago is a serious problem every winter, causing thousands of cases of breathing problems within the population. With more than 6 million people and almost two million vehicles, this large city receives rainfall only during winters. Depending on the frequency of storms, statistics show that every time it rains, air quality improves for a couple of days, followed by extreme levels of air pollution. Current regulations focus mostly on PM10 and PM2.5, due to its strong influence on respiratory diseases. Though more than 50% of the ambient PM10s in Santiago is represented by soil particles, most of the efforts have been focused on the remaining 50%, i.e. particulate material originating from fossil and wood fuel combustion, among others. This document emphasizes the need for the creation of erosion/sediment control regulations in Chile, to decrease respiratory diseases on Chilean polluted cities. - We emphasize the urgent need to implement erosion and sediment control politics in Santiago, to decrease PM10 concentrations in the city's air, based on the US experience

  1. Shift in detrital sedimentation in the eastern Bay of Bengal during the late Quaternary

    Indian Academy of Sciences (India)

    C Prakash Babu; J N Pattan; K Dutta; N Basavaiah; G V Ravi Prasad; D K Ray; P Govil

    2010-06-01

    Down-core variations of granulometric, geochemical and mineral magnetism of a 70-cm long sediment core retrieved from the eastern Bay of Bengal abyssal region were studied to understand sedimentation pattern and sediment provenance during the last ∼12 kyr BP. Based on down-core physical and elemental variations, three units were identified: unit 3 (70–43 cm) is a ∼30 cm thick clayey silt organic carbon-rich (0.5–0.92%) turbidite probably delivered by the Brahmaputra River during the late Quaternary period. Units 2 (43–24 cm) and 1 (24–0 cm) represent enhanced and reduced supply of coarse-grained detrital sediments from the Ganges River during early and late Holocene period, respectively. Increased terrigenous supply dilutes calcium carbonate (CaCO3) and biogenic elements (P, Ba and Cu) in units 3 and 2. On the contrary, a reduction in detrital input enhances CaCO3 and biogenic elements in unit 1. Lithogenic elements (Ti, Al, K and Rb) and shale-normalized REE patterns in all three units suggest terrigenous source. The shift in provenance from the Brahmaputra to the Ganges derived sediments is evident by a sharp increase in sediment grain size, increased concentration and grain size assemblages of magnetic minerals, lithogenic elements concentration and Lan/Ybn ratio. This study highlights terrigenous dilution on biogenic sedimentation in the eastern Bay of Bengal sediments.

  2. Modern Diatom Distributions in Guanabara Bay Sediment and Oceanic Areas, Rio de Janeiro (Brazil

    Directory of Open Access Journals (Sweden)

    Frederico S. Silva

    2011-01-01

    Full Text Available One hundred and fifty three superficial sediments were collected in Guanabara Bay to physical-chemistry and diatom analyses in the ambit to Monitoring Project (CENPES/PETROBRAS. A total of 146 taxa of diatoms were identified where the most frequent taxa in Guanabara Bay were Amphora spp., Coscinodiscus spp. and Navicula yarrensis var. yarrensis. These species are potentially harmful that might harm fisheries and mariculture during blooms. The values of ecological indexes like richness and diversity followed the estuarine gradient were the higher values were found in the mouth and de low in the inner part. The multivariate analyzes permitted recognize seven diatom assemblages in the bay. The DCA analyze shows the most influence in the distribution of assemblages were the depth and pH. The diatom assemblages analyze proved to be an efficient tool in the environmental diagnosis of Guanabara Bay.

  3. Characteristics of radionuclide distribution in surface layer sediments of Osaka Bay and Lake Biwa

    International Nuclear Information System (INIS)

    The PCDDs/DFs contamination in the environment has concerned our society even after prohibition of its use. Dr. Sakai et al. showed the change in concentration of PCDDs/DFs historically in sediment core samples taken from Osaka Bay and Lake Biwa. Sediment core samples were taken from five points on urban coastal area in Osaka Bay and three points on the coastal area in Lake Biwa. We measured the concentration of 226Ra, 210Pb, 228Th, 40K and 137Cs in the sediment core samples by using gamma-ray spectrometry and estimated the sedimentation rate with the 210Pb method. The sedimentation rate was about (200-600) mg/cm2·y in Osaka Bay and (150-300) mg/cm2·y n Lake Biwa. The characteristics on distribution of the 226Ra, 210Pb, 228Th, 40K and 137Cs concentration in the surface sediments on the cost of Osaka Bay and Lake Biwa were also investigated. The peaks of 137Cs concentration (35-70 Bq/kg) in three core samples from Lake Biwa were clearly observed. The sedimentation rates with 137Cs distribution indicated similarity to those calculated from the 210Pb method in the samples of Lake Biwa. However, a remarkable peak of 137Cs concentration was not observed in the core samples taken in Osaka Bay. These concentration were under 6 Bq/kg. We have kept on measuring the annual deposition rate (about 100 Bq/m2) of 210Pb in the Institute in Osaka with observation of the monthly deposition using a basin. We estimated the area contributed to the points taken core samples in comparison the annual deposition rate of 210Pb at the sampling points in Osaka Bay and Lake Biwa with that mentioned above. The mineral composition of the core samples were also measured by X-ray diffraction analysis. It is possible that the distribution of the concentration of these nuclides and the mineral composition in the sediments shows the environmental change. (author)

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

    International Nuclear Information System (INIS)

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

  5. Sublittoral soft bottom communities and diversity of Mejillones Bay in northern Chile (Humboldt Current upwelling system)

    OpenAIRE

    Laudien, J; Rojo, M.E.; Oliva, M.E.; Arntz, W. E.; Thatje, S.

    2007-01-01

    Keywords: macrozoobenthos ◊ community analyses ◊ feeding modes ◊ Mejillones Bay ◊ El NiñoThe macrozoobenthos of Mejillones Bay (23ºS; Humboldt Current) was quantitatively investigated over a seven years period from austral summer 1995/96 to winter 2002. 78 single van Veen grab samples taken at six stations (5, 10, 20 m depth) provided the basis for the analysis of the distribution of 60 species and 28 families as well as their abundance and biomass. Mean abundance (211...

  6. Evolution of sediment plumes in the Chesapeake bay and implications of climate variability.

    Science.gov (United States)

    Zheng, Guangming; DiGiacomo, Paul M; Kaushal, Sujay S; Yuen-Murphy, Marilyn A; Duan, Shuiwang

    2015-06-01

    Fluvial sediment transport impacts fisheries, marine ecosystems, and human health. In the upper Chesapeake Bay, river-induced sediment plumes are generally known as either a monotonic spatial shape or a turbidity maximum. Little is known about plume evolution in response to variation in streamflow and extreme discharge of sediment. Here we propose a typology of sediment plumes in the upper Chesapeake Bay using a 17 year time series of satellite-derived suspended sediment concentration. On the basis of estimated fluvial and wind contributions, we define an intermittent/wind-dominated type and a continuous type, the latter of which is further divided into four subtypes based on spatial features of plumes, which we refer to as Injection, Transport, Temporary Turbidity-Maximum, and Persistent Turbidity-Maximum. The four continuous types exhibit a consistent sequence of evolution within 1 week to 1 month following flood events. We also identify a "shift" in typology with increased frequency of Turbidity-Maximum types before and after Hurricane Ivan (2004), which implies that extreme events have longer-lasting effects upon estuarine suspended sediment than previously considered. These results can serve as a diagnostic tool to better predict distribution and impacts of estuarine suspended sediment in response to changes in climate and land use. PMID:25938877

  7. Late Quaternary sedimentation in eastern Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Mascarenhas, A.; Paropkari, A.L.; Rao, Ch.M.

    occupy the area designated for suspended sediments indicating that the entire sedimentary section was deposited under calm conditions. The sharp change in distribution of organic carbon and calcium carbonate at 40 cm suggests a change in the nature...

  8. Bottom Sediments -- Cape Ann to Casco Bay (FOLGER75 shapefile)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The reconnaissance maps upon which this data set is based show the areal distribution of the major bottom sediment types covering the sea floor off eastern New...

  9. Quantitative research for pollution levels in marine sediments of Ha Long Bay by nuclear technique

    International Nuclear Information System (INIS)

    Under the theme of Quantitative study of pollution levels in marine sediments of Halong bay by nuclear techniques conducted from June 2011 to June 2013, the authors conducted monitoring, sediment samples collected in the bay below the sediment column at 8 locations, in which 7 columns located at the estuary near Tuan Chau Island and 1 column at the area near the harbor of Cam Pha. The column samples were taken to the laboratory, cut slices with a distance of 2 cm in the form of frozen and conduct tests of radioactive Pb-210 to determine the rate of sediment in the survey area. Evaluation results based on the method by determining 210Pb, the sediment rate showed speed in the survey area ranged from 0.3 cm.a-1 to 1.2 cm.a-1 and an average of 1.0 cm.a-1. The slices of sediment samples (110 samples) were analyzed heavy metals (KLN) and As elemental by ICP-MS method. These sediment sample also were analyzed for simultaneous determination of N and P and total organic carbon (TOC). Results showed that heavy metal concentrations and As is smaller than the value specified in the National Technical Regulation on Sediment Quality of Vietnam (QCVN), phosphorus concentration less than that can cause harmful effects, but the concentration of total nitrogen and organic carbon that may exceed be harmful as directed by Canadian standards (Persuad et al. 1992). The concentration data in the Halong bay sediment were processed by statistical software SPSS-18, results showed high correlation between the quality TOC, N, P, K and correlation the majority of KLN, this proves the origin of sediments is part of the natural soil components and parts (TOC, N, P, K) is due to the activity of human activity as well as by agricultural fertilizers. The average content of elements in sediments Halong be compared with other data published works of sediment Quang Ninh area, the results show the correlation figures are also high. However, the results of the analysis of KLN and As in Halong sediment

  10. Sediment geochemical properties and dinoflagellate cyst distribution in Manila Bay, Philippines

    International Nuclear Information System (INIS)

    Full text: One of the theories used to explain the initiation of harmful algal blooms (HAB's) is the release and germination of microalgal cysts from the sediments. Assessment of the sediment's geochemical properties and its correlation with past HAB occurrences could serve as a clue on the conditions favorable for the occurrence of HAB's. HAB's of Pyrodinium bahamense var. compressum seasonally occurred in Manila Bay, Philippines from 1988 to 1998. To help understand and manage this phenomenon, sediment cores were dated using Lead-210 and analyzed for cysts, grain size, total carbonate and organic matter, elemental concentrations and metals. Lead-210 profiles indicated sedimentation rates of 1.2 to 2.5 cm/year while earlier periods ranged from 0.4 to 0.6 cm/yr. Such high sedimentation rates can dilute cyst counts which was apparent in this study. Shift in sedimentation rate could be attributed to the eruption of Mt. Pinatubo in 1991 which may have caused the burial of Pyrodinium cysts and subsequent nonoccurrence of its blooms since 1998. Dating also showed the presence of Pyrodinium in the early 1950s and ensuing increase until 1988. Autotrophic dinoflagellate cysts identified were: Lingulodinium polyedra, Gonyaulax spp., Pyrophacus steinii, Protoceratium reticulatum and Pyrodinium bahamense var. compressum while heterotrophs consisted of Protoperidinium and Diplopsalis species. Cyst density fluctuated but showed overall increase through time. The increase was most significantly observed before 1991 which coincided with the Bay's first bloom in 1988. The fluctuations which implied cyclicity was found to be controlled by the overall abundance of heterotrophs. Autotrophs, however showed significant increase in abundance in younger sediments which could account for HAB's from 1988 to 1998. Mud predominates in all of the cores which comprise of: clay (20% to 70%), silt (20% to 90%) and sand (0.6 to 3%). Major element profiles show an increase in Si/Al ratio and

  11. Influence of urbanization and industrialization on metal enrichment of sediment cores from Shantou Bay, South China

    International Nuclear Information System (INIS)

    Four sediment cores were collected to investigate geochemical sources and to assess enrichment and pollution of metals in sediments from Shantou Bay, an area experiencing rapid economic development on the Southeastern Coast of China. The results indicated that the concentrations of the majority of metals showed a decrease with depth, with overall maximum values in the top layers, and that different sampling locations in the Bay received slightly different types of inputs. Three major sources were identified by correlation analysis and principal component analysis: river inputs, metropolitan, and port facilities discharge. Calculation of a pollution load index revealed overall low values, but the enrichment factor values for Pb and Cd were typically high for all cores. The mean concentrations of Cu, Pb, Zn and to some extent Cd exceeded the Effects-Range-Low values in the majority of the cases, indicating that there were possible ecotoxicological risks to organisms in Shantou Bay. -- Highlights: •Metals had downward decrease with overall maximum value at top layers. •River input, metropolitan and port facilities discharge are identified as major sources. •Pb and Cd are mainly enriched metals. •Cu, Pb, Zn and Cd had potential ecotoxicological risks to organisms in Shantou Bay. -- Shantou Bay was polluted by Cd, Cu, Pb and Zn, and showed an increase trend along time. River input, metropolitan and port facilities were identified as their sources based on multi-analysis

  12. Isoprenoid and branched GDGT-based proxies for surface sediments from marine, fjord and lake environments in Chile

    OpenAIRE

    J. Kaiser; Schouten, S.; Kilian, R.; H. W. Arz; F. Lamy; Sinninghe Damsté, J.S.

    2015-01-01

    Proxies based on glycerol dialkyl glycerol tetraether (GDGT) lipids from archaea [isoprenoid GDGTs] and bacteria [branched (br) GDGTs] in 33 surface sediments from marine, fjord and lake systems between 25°S and 50°S in Chile were analyzed. The regional TEXH86 calibration obtained from the marine and fjord sediments and mean annual surface temperature (T = 59.6 × TEXH86 + 33.0; r2 0.9; n = 23) is statistically identical to the global ocean calibration based on suspended particulate material i...

  13. Characterization of trace organic contaminants in marine sediment from Yeongil Bay, Korea: 1. Instrumental analyses

    International Nuclear Information System (INIS)

    Concentrations of polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides (HCB, HCHs, CHLs, and DDTs), polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), and bisphenol A (BPA) were measured in 26 marine sediments collected from Yeongil Bay, Korea, in order to characterize their spatial distribution and sources. PCBs (2.85-26.5 ng/g, dry wt.) were detected mainly in the inner bay locations Mean OC pesticide ranged from 1.16 ng/g dry wt. for HCH to 0.05 ng/g dry wt. for HCB). PAH concentrations ranged from <10.0 to 1870 (mean: 309) ng/g dry wt., and were predominated 3- and 4-ring congeners. Concentrations of APs, such as nonylphenol, octylphenol, butylphenol (means 89.1, 4.61, 11.0 ng/g dry wt., respectively), were greater at locations proximal to municipal wastewater discharges. Concentrations of PCBs and PAHs were great near shipyards and industrial complexes. Vertical profiles of PAHs and APs indicated that they have been associated with sediments since the 1950s. - Among various sediment contaminant classes measured, nonylphenol and PAHs are responsible for the variability among sampling sites, suggesting the existence of multiple sources in Yeongil Bay sediment

  14. Mapping the extent and relative toxicity of sediments, Winter Quarters Bay, Antarctica

    International Nuclear Information System (INIS)

    McMurdo Station was established in the mid 1950s and is the largest research station in Antarctica. In earlier days, wastes were dumped on the steep shores of Winter Quarters Bay, dosed with up to 19,000 L of diesel or jet fuel and ignited. Along with periodic fuel spills, and the discharge of raw sewage the Bay became littered with trash and contaminated with elevated levels of metals, PCBs and petroleum hydrocarbons. The original benthic community was essentially totally replaced with more opportunistic species. In 1993, a study was initiated to map the distribution of PCB and hydrocarbon contamination as well as determine sediment pore water toxicity. Sediments were collected from over forty locations with an Ekman dredge after drilling through about 210 cm of ice. Maps of sediment particle size distribution, percent organic carbon, total PCBs, total petroleum hydrocarbons, etc. were developed. Potential toxicity was mapped by normalizing the data to 1 percent organic carbon and comparing the data with various sediment quality criteria. While onsite sediment pore water toxicity tests showed essentially no impacts, the new Microtox trademark chronic bioassay on both pore water and solvent extra showed considerable toxic effects. This paper compares the relative levels of contamination, with sediment quality criteria and toxicity as determined by a chronic microbial bioassays

  15. Distribution and pollution assessment of trace metals in seawater and sediment in Laizhou Bay

    Science.gov (United States)

    Lü, Dongwei; Zheng, Bing; Fang, Yan; Shen, Ge; Liu, Huijun

    2015-07-01

    Selected trace metals (Pb, Cd, Cu, Hg) and arsenic in seawater and surface sediments of Laizhou Bay were determined, to evaluate their spatial distribution, pollution risk and potential ecological risk. Concentrations of the elements were 0.56-2.07, 0.14-0.38, 12.70-18.40, 0.014-0.094, and 1.13-2.37 μg/L in the seawater and 8.94-32.2, 0.18-0.67, 4.51-30.5, 0.006-0.058, and 5.75-15.3 mg/kg in sediments for Pb, Cd, Cu, Hg and As, respectively. High concentrations of the trace metals and arsenic in seawater and surface sediments were generally observed near the river estuary. The pollution risk result of the elements showed that Cu was the prominent trace metal pollutant in seawater, followed by Hg, Pb, Cd and As. The metal complex pollution index in seawater was at a medium level. The most important trace metal pollutant in sediments was Cd, followed by As, Cu, Pb, and Hg. Our pollution assessment suggests that trace metal pollution in Laizhou Bay sediments was at a low level. The potential ecological risk was also low in surface sediment.

  16. Sediment distribution and transport along a rocky, embayed coast: Monterey Peninsula and Carmel Bay, California

    Science.gov (United States)

    Storlazzi, C.D.; Field, M.E.

    2000-01-01

    Field measurements of beach morphology and sedimentology were made along the Monterey Peninsula and Carmel Bay, California, in the spring and summer of 1997. These data were combined with low-altitude aerial imagery, high-resolution bathymetry, and local geology to understand how coastal geomorphology, lithology, and tectonics influence the distribution and transport of littoral sediment in the nearshore and inner shelf along a rocky shoreline over the course of decades. Three primary modes of sediment distribution in the nearshore and on the inner shelf off the Monterey Peninsula and in Carmel Bay were observed. Along stretches of the study area that were exposed to the dominant wave direction, sediment has accumulated in shore-normal bathymetric lows interpreted to be paleo-stream channels. Where the coastline is oriented parallel to the dominant wave direction and streams channels trend perpendicular to the coast, sediment-filled paleo-stream channels occur in the nearshore as well, but here they are connected to one another by shore-parallel ribbons of sediment at depths between 2 and 6 m. Where the coastline is oriented parallel to the dominant wave direction and onshore stream channels are not present, only shore-parallel patches of sediment at depths greater than 15 m are present. We interpret the distribution and interaction or transport of littoral sediment between pocket beaches along this coastline to be primarily controlled by the northwest-trending structure of the region and the dominant oceanographic regime. Because of the structural barriers to littoral transport, peaks in wave energy appear to be the dominant factor controlling the timing and magnitude of sediment transport between pocket beaches, more so than along long linear coasts. Accordingly, the magnitude and timing of sediment transport is dictated by the episodic nature of storm activity. (C) 2000 Elsevier Science B.V.

  17. Sediment Dwelling Benthos as Indicator Species for Pollution Monitoring of Mamala Bay, Oahu, Hawaii, 1993-1994 (NODC Accession 9900121)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A multifaceted study of the sediment dwelling benthos was conducted in Mamala Bay to identify suitable species as indicators of sewage enrichment. There are five...

  18. Sediment Sampling for Poly-Aromatic Hydrocarbons (PAHs) in Mobile Bay and Mississippi Sound in 2013 (NODC Accession 0116480)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sediment samples were collected at ten sites within Mobile Bay and Mississippi Sound on January 28, 2013, for PAH analysis. All samples tested were below detection...

  19. Copper and Other Contaminants in King's Bay and Crystal River (Florida) Sediments: Implications for Impact on the West Indian Manatee

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Contaminant concentrations were measured in 25 sediment samples collected from King's Bay, the headwaters of the Crystal River, Florida. Total organic carbon...

  20. First record of Cymatium keenae Beu, 1970 (Mollusca: Ranellidae) from Antofagasta Bay, northern Chile, in connection with El Niño events

    Science.gov (United States)

    Ashton, Tom; Riascos, Jose M.; Pacheco, Aldo

    2008-03-01

    Cymatium ( Monoplex) keenae Beu, 1970, the neopolitan triton, is a Ranellidae predator distributed in tropical and subtropical waters. In this study we report this species for the first time in Antofagasta Bay, northern Chile. Adult specimens have been found since June 2003 at depths ranging from 5 to 15 m in La Rinconada Marine Reserve (23°28'18″S, 70°30'46″W) in Antofagasta Bay, near a scallop farming facility. The present findings clearly extend the geographic range of C. keenae, which previously had been reported from La Paz, Gulf of California (Mexico) to Galápagos Islands (Ecuador) in the SE Pacific. Previous evidence strongly suggests that the intrusion of this tropical immigrant can be related to warm El Niño episodes. We analyze the key role of the oceanographic characteristics of Antofagasta Bay as potential temporal refuge for this species.

  1. Trace element residues in water, sediments, and organs of Savacu (Nycticorax nycticorax from Sepetiba Bay, Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    Marco Aurélio P. Horta

    2010-04-01

    Full Text Available Heavy metal (Cr, Cd, Zn, Cu, Ni, Pb concentrations in water, sediment and organs of Savacu, Nycticorax nycticorax were analyzed. Samples of water and sediment were collected from seven stations along Sepetiba Bay, and experimental animals, also were collected in the study area. This bay receives effluents discharges from heavily industrialized and highly populated settlements. Samples of water, sediment and Savacu were processed and analyzed for heavy metals and the results showed that these concentrations in sediment were higher than in water. The exposure to metals either in the water or by the effect of bioaccumulation in the food chain is reflected in the results obtained with animals’ test.

  2. Study of recent changes in sedimentation regime inside Cienfuegos Bay, Cuba using 210Pb and 137Cs as tracers

    International Nuclear Information System (INIS)

    Sedimentation dynamics in the Cienfuegos Bay was investigated based on profiles and inventories of 210Pbex and 137Cs in cores collected at two sites. The age of sediment layers was determined using the CRS model. Both cores show changes in sedimentation regime in the last 40 years. Since 1960-1965 sediment accumulation rates have doubled in both cells of the bay, from 0.2 to 0.4 g.cm-2.y-1. This change was probably one of the factors that influenced the important environmental modifications observed in the area. (author)

  3. Bioaccumulation of heavy metals in marine organisms and sediments from Admiralty Bay, King George Island, Antarctica.

    Science.gov (United States)

    Trevizani, Tailisi Hoppe; Figueira, Rubens Cesar Lopes; Ribeiro, Andreza Portella; Theophilo, Carolina Yume Sawamura; Majer, Alessandra Pereira; Petti, Monica Angélica Varella; Corbisier, Thais Navajas; Montone, Rosalinda Carmela

    2016-05-15

    The Antarctic continent is considered a low-impact environment; however, there is a tendency to increase the contaminants' levels due to human activities in the research stations. In this study, As, Cd, Cr, Cu, Hg, Ni, Pb and Zn levels in sediment and biota were determined in the environmental samples from Admiralty Bay (King George Island, Antarctica) collected in 2003. The results demonstrated high concentrations of Cu and Zn in the sediments. There was bioaccumulation of As in the biota from Admiralty Bay and bioaccumulation of Zn specifically in the biota from Martel Inlet. In addition, the results were useful in order to understand the heavy metal levels for the pre-accident condition of Comandante Ferraz Antarctic Station, where an accident occurred in 2012, and also for the comparison with current conditions within the monitoring work developed by INCT-APA (National Institute of Science and Technology for Environmental Research Antarctic). PMID:26936119

  4. Hydrogeochemical and stream sediment reconnaissance basic data for Bay City NTMS Quadrangle, Texas

    International Nuclear Information System (INIS)

    Results of a reconnaissance geochemical survey of the Bay City Quadrangle, Texas are reported. Statistical data and areal distributions for uranium and uranium-related variables are presented for 55 groundwaters and 46 stream sediment samples. Also included is a brief discussion on location and geologic setting. The Bay City Quadrangle is represented by a small area with relatively simple surface and subsurface geology. Two stratigraphic units are exposed at the surface and only one aquifer system supplies the groundwater samples. The results of the groundwater geochemical analysis show uranium associated with saline waters thus indicating possible salt water infiltration from the Gulf. The geochemical results from the analysis of stream sediments indicate uranium in association with resistate mineral indicators

  5. Trace element distribution in different chemical fractions of False Bay sediments

    International Nuclear Information System (INIS)

    Trace metals in the aquatic environment are generally concentrated on solid geochemical phases which eventually become incorporated into estuarine and marine sediments. The mechanism of trace metal concentration is believed to be adsorption on various geochemical phases, such as hydrous metal oxides, clays and organic matter. Metals in estuarine sediments can thus be expected to be partitioned between different phases, depending on the concentration of the phase and the strength of the adsorption bond. The bioavailability of sediment-bound metals to deposit-feeding organisms will depend on trace metal partitioning and the kinetics of biological metal uptake from each geochemical phase. The major objective of this study was to establish an analytical procedure involving sequential chemical extractions for the partitioning of particulate trace metals in sediment samples, collected from False Bay. Eight metals were examined, i.e. Cd, Cu, Cr, Fe, Mn, Ni, Pb and Zn. X-ray diffraction was also used in the study

  6. Horizontal distribution of steroid estrogens in surface sediments in Tokyo Bay

    International Nuclear Information System (INIS)

    A monitoring survey was conducted to investigate the distribution of steroid estrogens and their conjugates in surface sediments of Tokyo Bay for the first time, which is known as one of the most heavily polluted marine embayments in the world. The surface sediment samples were collected at 20 locations covering the whole area of Tokyo Bay and analyzed for steroid estrogens and their conjugates using liquid chromatography-tandem mass spectrometry. The concentrations of 17β-estradiol (β-E2) and estrone (E1) ranged from ND (below the detection limit; -1 dry, respectively. Those concentrations were higher in the northern part of the bay, which is directly receiving huge quantities of pollutants from adjacent rivers containing a large amount of municipal and industrial wastewater. 17α-Estradiol (α-E2) and estrone-3-sulfate (E1-3S) were detected in some of the samples, whereas neither of the other conjugates, estriol (E3) or 17α-ethynylestradiol (EE2), was found. - High concentrations of estrogen pollutants occur in areas of Tokyo Bay receiving runoff from highly urbanized areas of the watershed

  7. Horizontal distribution of steroid estrogens in surface sediments in Tokyo Bay

    Energy Technology Data Exchange (ETDEWEB)

    Isobe, Tomohiko [Endocrine Disrupters Research Laboratory, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan)]. E-mail: t.isobe@agr.ehime-u.ac.jp; Serizawa, Shigeko [Endocrine Disrupters Research Laboratory, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Horiguchi, Toshihiro [Endocrine Disrupters Research Laboratory, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Shibata, Yasuyuki [Endocrine Disrupters Research Laboratory, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Managaki, Satoshi [Laboratory of Organic Geochemistry, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509 (Japan); Takada, Hideshige [Laboratory of Organic Geochemistry, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509 (Japan); Morita, Masatoshi [Endocrine Disrupters Research Laboratory, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Shiraishi, Hiroaki [Endocrine Disrupters Research Laboratory, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan)

    2006-11-15

    A monitoring survey was conducted to investigate the distribution of steroid estrogens and their conjugates in surface sediments of Tokyo Bay for the first time, which is known as one of the most heavily polluted marine embayments in the world. The surface sediment samples were collected at 20 locations covering the whole area of Tokyo Bay and analyzed for steroid estrogens and their conjugates using liquid chromatography-tandem mass spectrometry. The concentrations of 17{beta}-estradiol ({beta}-E2) and estrone (E1) ranged from ND (below the detection limit; <0.07) to 0.59 and from 0.05 to 3.60 ng g{sup -1} dry, respectively. Those concentrations were higher in the northern part of the bay, which is directly receiving huge quantities of pollutants from adjacent rivers containing a large amount of municipal and industrial wastewater. 17{alpha}-Estradiol ({alpha}-E2) and estrone-3-sulfate (E1-3S) were detected in some of the samples, whereas neither of the other conjugates, estriol (E3) or 17{alpha}-ethynylestradiol (EE2), was found. - High concentrations of estrogen pollutants occur in areas of Tokyo Bay receiving runoff from highly urbanized areas of the watershed.

  8. Temporal variability of remotely sensed suspended sediment and sea surface temperature patterns in Mobile Bay, Alabama

    Science.gov (United States)

    Rucker, J.B.; Stumpf, R.P.; Schroeder, W.W.

    1990-01-01

    Distribution patterns of suspended sediments and sea surface temperatures in, Mobile Bay were derived from algorithms using digital data from the visible, near infrared, and infrared channels of the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-TIROS-N satellite. Closely spaced AVHRR scenes for January 20, 24, and 29, 1982, were compared with available environmental information taken during the same period. A complex interaction between river discharge, winds, and astronomical tides controlled the distribution patterns of suspended sediments. These same variables, coupled with air temperatures, also governed the distribution patterns of sea surface temperatures. ?? 1990 Estuarine Research Federation.

  9. Distribution and sources of polycyclic aromatic hydrocarbons in sediments from Kyeonggi Bay, Korea

    International Nuclear Information System (INIS)

    Sixty-six sediment samples were collected from Kyeonggi Bay, Korea, in December 1995 and analysed for a suite of 2-6 ring polycyclic aromatic hydrocarbons (PAHs). Sediments were collected in the Han River estuary, Incheon Harbour, from nearshore locations adjacent to large industrial complexes south of Incheon, and along transects toward the open sea. Concentrations of PAHs (9.1-1400 ng g-1 dry wt. with an average of 120 ng g-1) were positively correlated with organic carbon (OC) content and negatively correlated with mean sediment grain size. The highest PAH concentrations were in samples from inner Incheon Harbour basins; these levels decreased within a short distance from these heavily industrialised waterways. The sources of PAHs were determined to be primarily combustion nature based on the distribution of alkylated homologs to parent compounds. Overall, sediment PAHs in Kyeonggi Bay were lower than those in the United States and Europe. The potential for biological effects due to PAHs alone is expected to be low based on comparisons of individual and ΣPAH concentrations with effects-based and equilibrium partitioning-based sediment quality guidelines/criteria. (author)

  10. Geochemical characterization and environmental status of Makirina Bay sediments (northern Dalmatia, Republic of Croatia)

    OpenAIRE

    Komar, Darja; Dolenec, Matej; Lambaša Belak, Živana; Slavica Matešić, Sanja; Lojen, Sonja; Kniewald, Goran; Vrhovnik, Petra; Dolenec, Tadej; Rogan Šmuc, Nastja

    2015-01-01

    This research focuses on determination of the mineralogical composition, geochemical characteristics and evaluationof pollution status of the Makirina Bay sediments. Calculated enrichment factor (EF) values show no enrichment (< 1) for Cd, Ni, and Zn, minor enrichment (< 3) for As, Cu, and Pb, and minor to moderate enrichment for Mo. The resultsof the sequential leaching procedure for the aforementioned potentially toxic elements (PTE) indicates that the mobilityand bioavailability characteri...

  11. Depositional variability of estuarine intertidal sediments and implications for metal distribution: An example from Moreton Bay (Australia)

    Science.gov (United States)

    Morelli, Guia; Gasparon, Massimo

    2015-10-01

    This study examines the patterns of depositional variability, sediment geochemistry and metal distribution in intertidal areas of Moreton Bay, southeast Queensland, Australia. Recent concern over increasing human impact on the bay has generated the need to obtain evidence on how the disturbance of the depositional setting might affect the natural estuarine environment. Sediment stratigraphy, major, and trace element analyses of sediment cores show that the sedimentation pattern is unique to each intertidal site. Disturbed 210Pb and 137Cs activity profiles of some of the cores indicate that sediment reworking occurs across the intertidal flats up to a depth of at least 80 cm. With some notable exceptions, an accurate geochronology of the surface sediments could not be established due to low 210Pb activities and sediment mixing. Thus, an increase in Pb, Zn and Cu towards the surface sediments observed at various sites is attributed to both anthropogenic contribution following the rapid urban development in the last century and to post-depositional diagenetic processes, bioturbation and sediment re-suspension induced by tides, storms or floods. Sediment cores are representative only of the local sedimentation and may not always allow extensive correlation to larger areas. Vertical profiles of heavy metals reflect the different depositional environment controlled by the complex hydrodynamics of the bay. Local hydrologic, physical, and tidal conditions might induce metals redistribution at different scales. This information is of critical importance in view of sediment remobilization caused by future development such as dredging, intertidal areas reclamation or excavation of new navigational channels.

  12. Bioavailability of Organic Matter in the Superficial Sediment of Guanabara Bay, Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    José Augusto Pires Bitencourt

    2011-01-01

    Full Text Available Thirty superficial sediment samples were collected in Guanabara Bay in order to identify new trophic state and environmental quality descriptors for coastal systems. A biochemical approach was used for analyzing the quality and quantity of sedimentary organic matter and metabolic bacterial activity. The samples were analyzed for particle size; organic matter, protein, carbohydrate, lipid, biopolymeric carbon, and bioavailable carbon levels; and bacterial metabolic activity. The results show a homogeneous spatial distribution for the anaerobic bacteria web and for biopolymers (carbohydrates>lipids>protein. The NE area of the bay displayed sediment lipid levels above 1 mg/g, indicative of organic sewage input. Spatial distribution of the superficial sediments in relation to other variables was not significant (p>0.05. Biopolymers and labile organic matter showed a significant correlation with the average particle size of 80% of the fine particles. Despite the availability of labile organic matter, under the form of biopolymeric carbon, only 50% of the carbon was available to the trophic web. The bacterial consortia formed by sulfate reducing and denitrifying bacteria sustain the benthic trophic food web in Guanabara Bay.

  13. Aminostratigraphy of sediments of the SW Bay or Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, N.S.; Krishna, M.S.R.; Pasha, S.K.G.; Yadava, M.G.; Rao, K.M.

    . At a water depth of 1200 m off Penna delta, Purnachandra Rao et al . 15 su g- gested a Holocene sedimentation rate of 9.4 cm kyr ? 1 . In a core (2909 m water depth) of the deep Andaman Sea, Ahmad et al . 16.... Rev. , 1980, 16 , 21 ? 55. 15. Purnachandra Rao, V., Rao, Ch. M., Mascarenhas, A., Mohana Rao, K., Reddy, N. P. C. and Das, H. C., J. Geol. Soc. I n dia , 1992, 40 , 59 ? 69. 16. Ahmad, S. M., Patil, D. J., Rao, P. S., Nath, B. N., Rao...

  14. Sediment chemistry and toxicity in Barnegat Bay, New Jersey: Pre- and post-Hurricane Sandy, 2012-13.

    Science.gov (United States)

    Romanok, Kristin M; Szabo, Zoltan; Reilly, Timothy J; Defne, Zafer; Ganju, Neil K

    2016-06-30

    Hurricane Sandy made landfall in Barnegat Bay, October, 29, 2012, damaging shorelines and infrastructure. Estuarine sediment chemistry and toxicity were investigated before and after to evaluate potential environmental health impacts and to establish post-event baseline sediment-quality conditions. Trace element concentrations increased throughout Barnegat Bay up to two orders of magnitude, especially north of Barnegat Inlet, consistent with northward redistribution of silt. Loss of organic compounds, clay, and organic carbon is consistent with sediment winnowing and transport through the inlets and sediment transport modeling results. The number of sites exceeding sediment quality guidance levels for trace elements tripled post-Sandy. Sediment toxicity post-Sandy was mostly unaffected relative to pre-Sandy conditions, but at the site with the greatest relative increase for trace elements, survival rate of the test amphipod decreased (indicating degradation). This study would not have been possible without comprehensive baseline data enabling the evaluation of storm-derived changes in sediment quality. PMID:27158047

  15. {sup 137}Cs in marine sediments of Admiralty Bay, King George Island, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Paulo Alves de Lima [Instituto Oceanográfico, Universidade de São Paulo (IO-USP), Pça. do Oceanográfico, 191, Butantã, SP, 05508 900 (Brazil); Ribeiro, Andreza Portella, E-mail: andrezpr@usp.br [Instituto Oceanográfico, Universidade de São Paulo (IO-USP), Pça. do Oceanográfico, 191, Butantã, SP, 05508 900 (Brazil); Mestrado de Gestão Ambiental e Sustentabilidade, Universidade Nove de Julho (UNINOVE), Avenida Francisco Matarazzo, 612, prédio C, andar térreo, Água Branca, São Paulo, SP, 05001 100 (Brazil); Nascimento, Mylene Giseli do; Martins, Cesar de Castro [Centro de Estudos do Mar, Universidade Federal do Paraná (CEM-UFPR), Av. Beira-mar, no number, Balneário Pontal do Sul, Pontal do Paraná, PR, 83255 971 (Brazil); Mahiques, Michel Michaelovitch de; Montone, Rosalinda Carmelo; Figueira, Rubens Cesar Lopes [Instituto Oceanográfico, Universidade de São Paulo (IO-USP), Pça. do Oceanográfico, 191, Butantã, SP, 05508 900 (Brazil)

    2013-01-15

    The radionuclide cesium-137 ({sup 137}Cs) is produced exclusively by anthropogenic processes and primarily by nuclear explosions. This study determined the reference inventory that is {sup 137}Cs associated with the element's original input, and utilized the levels of activity of this radionuclide previously measured in five sediment profiles collected from Admiralty Bay, Antarctica, to investigate the mobility of this element in the environment. {sup 137}Cs has a half-life of 30 years. Because of this, it is environmentally persistent and has been shown to accumulate in marine organisms. The mean reference inventory of this radionuclide in Admiralty Bay sediments, determined using high resolution gamma ray spectrometry, was 20.23 ± 8.94 Bq m{sup −2}, and within the ambient {sup 137}Cs activity range. A model of {sup 137}Cs diffusion–convection was applied to data collected from 1 cm intervals in sediment cores with the aim of providing insights with respect to this element's behavior in sediments. Model results showed a significant correlation between measured and modeled values using the concentrations of {sup 137}Cs, and estimated input into the system from the global fallout of past nuclear tests and expected values based on local sedimentation rates. Results highlight the importance of accounting for the vertical diffusion of {sup 137}Cs in marine sediments when used as a tracer for environmental processes and for assessing potential bioavailability. - Highlights: ► Cesium-137 ({sup 137}Cs) is produced exclusively by anthropogenic processes. ► A model of diffusion–convection simulated {sup 137}Cs environmental behavior. ► This is important for assessing the bioavailability of this toxic element. ► In Antarctica ice cover influenced the input to the sediments.

  16. 137Cs in marine sediments of Admiralty Bay, King George Island, Antarctica

    International Nuclear Information System (INIS)

    The radionuclide cesium-137 (137Cs) is produced exclusively by anthropogenic processes and primarily by nuclear explosions. This study determined the reference inventory that is 137Cs associated with the element's original input, and utilized the levels of activity of this radionuclide previously measured in five sediment profiles collected from Admiralty Bay, Antarctica, to investigate the mobility of this element in the environment. 137Cs has a half-life of 30 years. Because of this, it is environmentally persistent and has been shown to accumulate in marine organisms. The mean reference inventory of this radionuclide in Admiralty Bay sediments, determined using high resolution gamma ray spectrometry, was 20.23 ± 8.94 Bq m−2, and within the ambient 137Cs activity range. A model of 137Cs diffusion–convection was applied to data collected from 1 cm intervals in sediment cores with the aim of providing insights with respect to this element's behavior in sediments. Model results showed a significant correlation between measured and modeled values using the concentrations of 137Cs, and estimated input into the system from the global fallout of past nuclear tests and expected values based on local sedimentation rates. Results highlight the importance of accounting for the vertical diffusion of 137Cs in marine sediments when used as a tracer for environmental processes and for assessing potential bioavailability. - Highlights: ► Cesium-137 (137Cs) is produced exclusively by anthropogenic processes. ► A model of diffusion–convection simulated 137Cs environmental behavior. ► This is important for assessing the bioavailability of this toxic element. ► In Antarctica ice cover influenced the input to the sediments

  17. Dating of sediments in the Biscay bay: implication for pollution chronology

    International Nuclear Information System (INIS)

    Important historical informations on the temporal changes of anthropogenic pollution in marine environment can be assessed using sediment analysis. Dating is a crucial prerequisite to reconstruct pollution events, to calculate fluxes, and thus to allow comparison between different sites. This work presents estimates of accumulation rate of sediments in the Bay of Biscay. Fives cores were collected during RIKEAU 2002 cruise on board o/v Thalia in order to study temporal changes in PAH and organo-halogens compounds (PCB, PBDE and PCDD/Fs) content of sediment. We compare chronostratigraphic estimates on cores derived from the natural radionuclide 210Pb in excess with estimates from the known times of introduction of the artificial radionuclide 137Cs to the environment. 210Pb, 226Ra (210Pb in excess = 210Pb - 226Ra) and 137Cs were measured directly by non-destructive gamma spectrometry using a well type γ-detector. Total 210Pb and 226Ra activities vary from 30 to 150 mBq g-1, and 20 to 36 mBq g-1 respectively; 137Cs presents lower levels (-1). Profiles of 210Pbxs present a mixed layer from 2-3 to 10 cm) in the uppermost sediments, followed by an exponential decrease of activities, suitable for the determination of sedimentation rates. Under constant flux and sedimentation rate assumptions, vertical accretion rates derived from 210Pbxs present a large range from nearly 0.1 cm yr-1 up to almost 0.6 cm yr-1. Differences are mainly due to relative position of studied cores regarding the muddy patch. Although the moderate level of 137Cs limits the accuracy of this dating method, profiles of 137Cs with depth strengthen mean rates derived from 210Pbxs data. The implication of these dating on pollutant inputs in sediments of the Bay of Biscay will be discussed. (author)

  18. Delineating incised stream sediment sources within a San Francisco Bay tributary basin

    Science.gov (United States)

    Bigelow, Paul; Benda, Lee; Pearce, Sarah

    2016-07-01

    Erosion and sedimentation pose ubiquitous problems for land and watershed managers, requiring delineation of sediment sources and sinks across landscapes. However, the technical complexity of many spatially explicit erosion models precludes their use by practitioners. To address this critical gap, we demonstrate a contemporary use of applied geomorphometry through a straightforward GIS analysis of sediment sources in the San Francisco Bay Area in California, USA, designed to support erosion reduction strategies. Using 2 m lidar digital elevation models, we delineated the entire river network in the Arroyo Mocho watershed (573 km2) at the scale of ˜ 30 m segments and identified incised landforms using a combination of hillslope gradient and planform curvature. Chronic erosion to the channel network was estimated based on these topographic attributes and the size of vegetation, and calibrated to sediment gage data, providing a spatially explicit estimate of sediment yield from incised channels across the basin. Rates of erosion were summarized downstream through the channel network, revealing patterns of sediment supply at the reach scale. Erosion and sediment supply were also aggregated to subbasins, allowing comparative analyses at the scale of tributaries. The erosion patterns delineated using this approach provide land use planners with a robust framework to design erosion reduction strategies. More broadly, the study demonstrates a modern analysis of important geomorphic processes affected by land use that is easily applied by agencies to solve common problems in watersheds, improving the integration between science and environmental management.

  19. Plankton Resting Stages in the Marine Sediments of the Bay of Vlorë (Albania

    Directory of Open Access Journals (Sweden)

    Fernando Rubino

    2013-01-01

    Full Text Available In the frame of the INTERREG III CISM project, sediment cores were collected at 2 stations in the Gulf of Vlorë to study the plankton resting stage assemblages. A total of 87 morphotypes were identified and produced by Dinophyta, Ciliophora, Rotifera, and Crustacea. In 22 cases, the cyst belonged to a species absent from the plankton of the same period. The most abundant resting stages were those produced by Scrippsiella species (Dinophyta. Some calcareous cysts were identified as fossil species associated with Pleistocene to Pliocene sediment, although they were also found in surface sediments and some of them successfully germinated, thus proving their modern status. Total abundance generally decreased with sediment depth at station 40, while station 45 showed distinct maxima at 3 and 8 cm below the sediment surface. The depth of peak abundance in the sediment varied with species. This paper presents the first study of the plankton resting stages in the Bay of Vlorë. The study confirmed the utility of this type of investigation for a more correct evaluation of species diversity. In addition, the varying distribution with sediment depth suggests that this field could be of some importance in determining the history of species assemblages.

  20. Sublittoral soft bottom communities and diversity of Mejillones Bay in northern Chile (Humboldt Current upwelling system)

    Science.gov (United States)

    Laudien, Jürgen; Rojo, Manuel E.; Oliva, Marcelo E.; Arntz, Wolf E.; Thatje, Sven

    2007-06-01

    The macrozoobenthos of Mejillones Bay (23°S; Humboldt Current) was quantitatively investigated over a 7-year period from austral summer 1995/1996 to winter 2002. About 78 van Veen grab samples taken at six stations (5, 10, 20 m depth) provided the basis for the analysis of the distribution of 60 species and 28 families of benthic invertebrates, as well as of their abundance and biomass. Mean abundance (2,119 individuals m-2) was in the same order compared to a previous investigation; mean biomass (966 g formalin wet mass m-2), however, exceeded prior estimations mainly due to the dominance of the bivalve Aulacomya ater. About 43% of the taxa inhabited the complete depth range. Mean taxonomic Shannon diversity (H', Log e) was 1.54 ± 0.58 with a maximum at 20 m (1.95 ± 0.33); evenness increased with depth. The fauna was numerically dominated by carnivorous gastropods, polychaetes and crustaceans (48%). About 15% of the species were suspensivorous, 13% sedimentivorous, 11% detritivorous, 7% omnivorous and 6% herbivorous. Cluster analyses showed a significant difference between the shallow and the deeper stations. Gammarid amphipods and the polychaete family Nephtyidae characterized the 5-m-zone, the molluscs Aulacomya ater, Mitrella unifasciata and gammarids the intermediate zone, while the gastropod Nassarius gayi and the polychaete family Nereidae were most prominent at the deeper stations. The communities of the three depth zones did not appear to be limited by hypoxia during non-El Niño conditions. Therefore, no typical change in community structure occurred during El Niño 1997-1998, in contrast to what was observed for deeper faunal assemblages and hypoxic bays elsewhere in the coastal Humboldt Current system.

  1. Impact of storm-water outfalls on sediment quality in Corpus Christi Bay, Texas, USA

    Energy Technology Data Exchange (ETDEWEB)

    Carr, R.S.; Montagna, P.A.; Biedenbach, J.M.; Kalke, R.; Kennicutt, M.C.; Hooten, R.; Cripe, G.

    2000-03-01

    To determine the quality of sediments and extent of contaminant impacts, a Sediment Quality Triad (SQT) study was conducted at 36 sites in the Corpus Christi Bay, Texas, USA, system. Fifteen of the 36 sites were located near storm-water outfalls, but 13 other sites (i.e., industrial and domestic outfalls, oil field-produced water discharges, and dredging activity) and eight reference sites were also evaluated. Sediment samples were collected and analyzed for physical-chemical characteristics, contaminant concentrations (metals, polycyclic aromatic hydrocarbons [PAHs], polychlorinated biphenyls [PCBs], and pesticides), toxicity, and a benthic index of biotic integrity (BIBI) composed of 10 independent metrics calculated for each site. This large data matrix was reduced using multivariate analysis to create new variables for each component representing overall means and containing most of the variance in the larger data set. The new variables were used to conduct the correlation analysis. Toxicity was significantly correlated with both chemistry and ecological responses, whereas no correlations between the benthic metrics and sediment chemistry were observed. Using the combined information from the SQT, four of the five most degraded sites were storm-water outfall sites. Although estuaries are naturally stressful environments because of salinity and temperature fluctuations, this ecosystem appears to have been compromised by anthropogenic influences similar to what has been observed for other heavily urbanized bay systems along the Texas and Gulf coast.

  2. New non-PBDE brominated flame retardants in sediment and plant samples from Jiaozhou Bay wetland.

    Science.gov (United States)

    Wang, Ling; Zhao, Quansheng; Zhao, Yanyan; Zheng, Minggang; Lou, Yinghua; Yang, Baijuan

    2015-08-15

    Seven non-polybrominated diphenyl ethers (non-PBDE) (TBB, TBX, PBT, PBEB, HBB, DBHCTD and BB153) were analyzed in sediment and plant samples which were collected from Xiaojianxi landfill to Dagu river estuary in Jiaozhou Bay wetland. The species of non-PBDE were different in sediment and plant samples with the concentration of 0.41-9.66ngg(-1) and 0.15-1.2ngg(-1), respectively. DBHCTD was the main non-PBDE compared with other target compounds and its concentration was 1.21-9.66ngg(-1)dw. Generally, the concentration of non-PBDE in sediment showed a decreasing tendency while discrete decline in plant has been revealed. Furthermore, DBHCTD, HBB, as well as other BFRs, might have a common BFRs degradation or similar accumulation potential in sediment, as their Pearson relationship p<0.05. Generally, the content of non-PBDE in Jiaozhou Bay wetland was higher than other published research. Therefore, more attention should be paid to non-PBDE on account of their persisting impact on human health and environment. PMID:25986656

  3. Reconstructing the rise of recent coastal anoxia; molybdenum in Chesapeake Bay sediments

    Science.gov (United States)

    Adelson, J.M.; Helz, G.R.; Miller, C.V.

    2001-01-01

    Sporadic, direct observations over a 50 yr period inadequately characterize the history of seasonal hypoxia and anoxia in Chesapeake Bay, alarge estuary threatened by eutrophication. Here, we undertake a reconstruction of 20th century oxygen depletion in this estuary using Mo concentrations in 210Pb-dated sediments; Cu concentrations are used to control for anthropogenic influences. Cores from the central channel display mild Mo enrichments above crustal backgrounds (up to 5 ??g/g) and strong Cu enrichments (up to 35 ??g/g). Temporally, Cu enrichment (mostly anthropogenic) began earlier and stabilized in the last two thirds of the 20th century. In contrast, Mo enrichment has grown during the last two thirds of the century. Molybdenum enrichment is mostly hydrogenic, except in a section of the channel that receives additional Mo from erosion of Early Miocene shore deposits. Two geochemical mechanisms promote Mo enrichment: Manganese refluxing concentrates dissolved MoO24- at the sediment-water interface and sulfide substitution into MoO24- produces thiomolybdates, which can be fixed by particles. The Mo enrichment mechanisms operate primarily during periods when bottom waters are anoxic and thiomolybdate formation can occur near the sediment-water interface. This implies a temporal coupling between water-column anoxia and Mo fixation even though fixation occurs only within sediments. The Mo enrichment profiles suggest that Chesapeake Bay has experienced growing O2 depletion since the first half of the 20th century, but especially after 1960. Copyright ?? 2001 Elsevier Science Ltd.

  4. Natural and anthropogenic sources of chemical elements in sediment profiles from the Admiralty Bay, Antarctica

    International Nuclear Information System (INIS)

    Full text: The Antarctic Continent and its surrounding Southern Ocean are the least known regions of the world, mainly due to the most unfavorable climatic conditions, in which sampling for environmental studies are quite difficult to be carried out. Admiralty Bay on the King George Island (Antarctica) hosts three research stations, Arctowski, Ferraz and Macchu Picchu, which are operate by Poland, Brazil and Peru, respectively. Therefore, human activities in this region require the use of fossil fuel as an energy source, which is also considered the main source of pollutants in the area. This work investigated the natural and anthropogenic inputs of chemical elements in sediment samples collected close to Ferraz Station, during the 25th Brazilian Antarctica Expedition in the 2006/2007 austral summer. Total concentrations of As, Zn and Sc were determined in sediment profiles by using the Instrumental Neutron Activation Analysis (INAA). The analytical technique employed to determine the major elements such as Fe, Al, Ca, Mn and Ti was X-ray fluorescence (XRF) spectroscopy. For estimating the sedimentation rate, High Resolution Gamma Ray Spectrometry was applied to determine 137Cs, after 30 days, to achieve secular equilibrium. According to the enrichment factor and the geochronology analysis, the most relevant enrichment was observed for As in the sediment samples, suggesting the increasing of its content due to the Brazilian activities in the Admiralty Bay. Despite some evidences of anthropogenic contribution, the study indicated low level of environmental risk for this region. (author)

  5. Iron geochemistry in surface sediments of a temperate semi-enclosed bay, North China

    Science.gov (United States)

    Zhu, Mao-Xu; Huang, Xiang-Li; Yang, Gui-Peng; Chen, Liang-Jin

    2015-11-01

    Iron (Fe) speciation and microbial reducible Fe(III) oxides (MR-Fe(III)) in surface sediments of semi-enclosed Jiaozhou Bay were quantified to reveal Fe geochemistry in the settings subjected to anthropogenic perturbations. Results indicate that sedimentary Fe in the bay is mainly of natural weathering source, without appreciable anthropogenic Fe inputs, as indicated by a generally good linear coupling of total Fe to aluminum. Among the three highly reactive Fe(III) (Fe(III)HR) pools, well crystalline Fe(III) oxides (Fe(III)wc) were always the predominant phase, followed by poorly crystalline Fe(III) oxides (Fe(III)pc), and amorphous Fe(III) oxides (Fe(III)am) were only of minor importance. The dominance of non-sulfidized Fe(II) over sulfidized Fe in the sediments points to the importance of microbial iron(III) reduction (MIR) in the free sulfide-starved conditions. High riverine inputs of TOC leads to outliers in the Fe(III)HR versus total organic carbon (TOC) ratio compared the rest of the bay. OM-dependent MIR as the common driving force has rendered all Fe(II)-bearing phases linearly coupled to TOC. MR-Fe(III) in the surface sediments covered all Fe(III)am and a fraction of less reactive Fe(III) phases, while Fe(III)wc was at most a minor contributor. Highly reactive Fe appears to be enriched to some extent in the temperate semi-enclosed bay, as in the wet-tropical counterparts.

  6. Methodical Features of the Field Researches of the Anapa Bay-Bar Sediment Composition

    Science.gov (United States)

    Krylenko, Marina; Krylenko, Viacheslav; Gusakova, Anastasiya; Kosyan, Alisa

    2014-05-01

    Resort Anapa (Black Sea coast, Russia) holds leading positions in the Russian market of sanatorium-resort and children's recreation. The 50-200 m sandy beaches of Anapa bay-bar are the main value of the resort. Anapa bay-bar is an extensive accumulative sandy body having the length about 47 km. Obvious attributes of the beaches degradation demanding immediate measures on their protection and restoration are observed in last years. The main reason of degradation is beach material deficiency. To organize researches of the sediments of this extensive natural object is a difficult challenge. It is necessary to reduce number of tests to minimum. It is important to record differences of separate bay-bar sites and to receive comparable data for different seasons and years. Our researches showed that the grain-size sediment composition significantly depends of position on local relief. Consequently, researching of the alongshore change of the sediment size is effectual to realize at this morphological elements. Shelly detritus makes to 30% of total amount of beach sediments. It is necessary to consider that quantitative shell distribution along the coast significantly depends on a configuration of the coastline and an underwater relief. Quantity of the shells for cross-shore profile is maximal near coastline. For identification of the sediment sources and researching of their fluxes to use minerals markers (heavy minerals) is optimum. The maximum of heavy minerals concentration is characteristic for fraction 0.1-0.05mm at depth more 5 m. The maintenance of this fraction within other morphological zones isn't enough for the analysis or is excessively changeable. Use of the revealed features allowed to conduct the representative field researches of grain-size and mineral sediment composition for all morphological zones of underwater and coast part of the Anapa bay-bar. This methodic recommendations are workable for researches on others coast accumulative body. The work is

  7. Evaluation of hypoxia at dredged trenches in Tokyo Bay by determination of redox sensitive elements in the sediments

    International Nuclear Information System (INIS)

    Sediment samples were collected from Tokyo Bay, and the concentrations of some elements were determined by instrumental neutron activation analysis (INAA). Though hypoxia has been observed in dredged trenches, it is suggested that upper layers of the sediments are more oxidative than lower layers. (author)

  8. Long-Term Changes in Sediment and Nutrient Delivery from Conowingo Dam to Chesapeake Bay: Effects of Reservoir Sedimentation.

    Science.gov (United States)

    Zhang, Qian; Hirsch, Robert M; Ball, William P

    2016-02-16

    Reduction of suspended sediment (SS), total phosphorus (TP), and total nitrogen is an important focus for Chesapeake Bay watershed management. The Susquehanna River, the bay's largest tributary, has drawn attention because SS loads from behind Conowingo Dam (near the river's mouth) have been rising dramatically. To better understand these changes, we evaluated histories of concentration and loading (1986-2013) using data from sites above and below Conowingo Reservoir. First, observed concentration-discharge relationships show that SS and TP concentrations at the reservoir inlet have declined under most discharges in recent decades, but without corresponding declines at the outlet, implying recently diminished reservoir trapping. Second, best estimates of mass balance suggest decreasing net deposition of SS and TP in recent decades over a wide range of discharges, with cumulative mass generally dominated by the 75∼99.5th percentile of daily Conowingo discharges. Finally, stationary models that better accommodate effects of riverflow variability also support the conclusion of diminished trapping of SS and TP under a range of discharges that includes those well below the literature-reported scour threshold. Overall, these findings suggest that decreased net deposition of SS and TP has occurred at subscour levels of discharge, which has significant implications for the Chesapeake Bay ecosystem. PMID:26744776

  9. Accumulation rates and sediment deposition in the Goekova Bay in Aegean Sea Turkish Coast

    International Nuclear Information System (INIS)

    Sediment accumulation rates were estimated from the vertical distribution of excess 210Pb in sediment cores collected at six stations in the Goekova Bay near the heavily industrialized Turkish Coastal zone of the Aegean Sea. Total 210Pb was determined by measuring 210Po activities. The sediment accumulation rates were calculated to vary from 0.32±0.01 cm yr-1 (0.17±0.01 g cm-2 yr-1) to 1.92±0.20 cm yr-1 (1.13±0.10 g cm-2 yr-1). The unsupported 210Pb flux was calculated from the accumulated dry matter of the examined slices and their unsupported 210Pb concentrations. The flux of unsupported 210Pb varies between 62±5 and 105±8 Bq m-2 yr-1. The average depositional flux was found to be considerably higher for cores from the Mediterranean

  10. Marine meiofauna, carbon and nitrogen mineralization in sandy and soft sediments of Disko Bay, West Greenland

    DEFF Research Database (Denmark)

    Rysgaard, S.; Christensen, P.B.; Sørensen, Martin Vinther; Funch, P.; Berg, P.

    2000-01-01

    Organic carbon mineralization was studied in a shallow-water (4 m), sandy sediment and 2 comparatively deep-water (150 and 300 m), soft sediments in Disko Bay, West Greenland. Benthic microalgae inhabiting the shallow-water locality significantly affected diurnal O-2 conditions within the surface...... and was, together with organotrophic O-2 respiration, the most important pathway for carbon mineralization within these sediments. The obtained process rates were comparable to mineralization rates from much warmer localities, suggesting that benthic mineralization in arctic marine environments is...... belonging to Platyhelminthes, Rotifera, Gastrotricha, and Protodriloidae (Polychaeta) occurred only at the sandy locality, whereas Kinorhyncha, Foraminifera, and Cumacea (Crustacea) occurred only at the muddy stations. The larger number of meiofauna individuals at the sandy locality may in part be explained...

  11. Recent {sup 137}Cs deposition in sediments of Admiralty Bay, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, Christian J., E-mail: zinosanders@yahoo.co [Departamento de Geoquimica, Universidade Federal Fluminense, 24020-007, Niteroi-RJ (Brazil); Santos, Isaac R. [Centre for Coastal Biogeochemistry, School of Environmental Science and Management, Southern Cross University, Lismore, NSW 2480 (Australia); Patchineelam, Sambasiva R. [Departamento de Geoquimica, Universidade Federal Fluminense, 24020-007, Niteroi-RJ (Brazil); Schaefer, Carlos [Departamento de Solos, Universidade Federal de Vicosa, 36570-000, Vicosa-MG (Brazil); Silva-Filho, Emmanoel V. [Departamento de Geoquimica, Universidade Federal Fluminense, 24020-007, Niteroi-RJ (Brazil)

    2010-05-15

    Cesium-137, radium-226 and lead-210 profiles of a 25 cm sediment core give an indication of recent changes in land-ocean interactions at a polar coastal environment (Admiralty Bay, King George Island, Antarctica). The linear sedimentation accumulation rate at the study site calculated from the unsupported {sup 210}Pb profile was 6.7 mm/year from 1965 to 2005. A 3.5-fold increase in {sup 137}Cs concentrations was observed in the top layer of this sediment core. This sharp increase seems to indicate a recent redistribution of fallout radionuclides previously deposited on soil, vegetation and snow. These results imply enhanced land-ocean interactions at this site likely as a result of climate change. Because our results are based on a single core, additional investigations are needed to confirm our observations.

  12. Mercury flux to estuarine sediments, derived from Pb-210 and Cs-137 geochronologies (Guaratuba Bay, Brazil)

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, Christian J. [Departamento de Geoquimica, Universidade Federal Fluminense, 24020-007 Niteroi-RJ (Brazil)]. E-mail zinosanders@yahoo.com; Santos, Isaac R. [Department of Oceanography, Florida State University, Tallahassee, FL, 32306 (United States); Silva-Filho, Emmanoel V. [Departamento de Geoquimica, Universidade Federal Fluminense, 24020-007 Niteroi-RJ (Brazil); Patchineelam, Sambasiva R. [Departamento de Geoquimica, Universidade Federal Fluminense, 24020-007 Niteroi-RJ (Brazil)

    2006-09-15

    A sediment core from Guaratuba Bay was used to indicate possible Hg modifications to this coastal environment brought about by growing agricultural activity. Sedimentation rates were estimated to be 6.1 mm/year and 5.2 mm/year through {sup 21}Pb and {sup 137}Cs geochronologies, respectively. Mercury concentrations and organic matter ratios in the surface layers are greater than in the older sediments, supporting the hypothesis of anthropogenic enrichment. Results show that the Hg flux has raised more than twofold during the second half of the 20th century. These results point to the need for further studies to substantiate the hypothesis of anthropogenic enrichment and to quantify point sources of Hg to this estuary.

  13. The sediment load and deposition by river discharge and their relation to organochlorine pesticides pollutants in the sediment bottom of Nha Trang Bay, Vietnam

    Science.gov (United States)

    Du, Hoang Trung; Kunzmann, Andreas

    2015-06-01

    Based on previous results from the "River reef impact studies project that was carried out as a co-operation programme between ZMT (Germany) and NIO (Vietnam) from 2008-2012, the variation of sediment load and associated persistent organic pollutants were investigated in Nha Trang Bay. In northern parts of the bay, both suspended matter load and deposition rates are high during the rainy season (flood events). The total suspended matter (TSM) and particulate nitrogen (PN) concentration show variations both with season (dry and rainy seasons) and increasing distances from the coast: TSM ranged from 2.30 to 19.79 mgL-1; and PN concentration ranged from 0.006 to 0.055 mgL-1. High deposition rates occurred both near the shore and in mid-bay, ranging from 12.8 to 36.1 g m-2 d-1. In the southern section of the bay, sediment deposition was slightly lower, with little seasonal variation. The highest deposition rate was measured at the river estuarine site, amounting to 9.1 g m-2 d-1 (dry season) and 9.0 g m-2 d-1 (rainy season). Further, persistent organic pollutants (POP) concentrations in sediment samples and sediment cores clearly showed the presence of organo-chlorine pesticides (OCP pollutant). High accumulation levels of OCP components were found in almost all sediment samples of Nha Trang Bay. The DDT concentrations showed high levels in sediment located in the estuary at the northern part of the bay (ranged: 20.11µg kg-1 to 5.28µg kg-1), and in the southern part (B1) 3.76µg kg-1. This study provides essential data and information, which are needed to assess the long-term impacts of river input on the degradation of marine ecosystems in the coastal waters of Nha Trang Bay.

  14. Satellite Observation of Changes in Suspended Sediment Induced by a Bay Bridge

    Science.gov (United States)

    Cai, Lina; Tang, Danling; Li, Congying

    2014-11-01

    Nearshore bridges may have impacts on ocean environments. This paper introduced how to investigate suspended sediment changes induced by a bay-bridge using remote sensing method. Hangzhou Bay Bridge (HBB) crossing Hangzhou Bay, in China, was taken as example. The spectral features of water were analyzed, and unsupervised classification of water quality was conducted, suspended sediment concentration (SSC) was inversed from Landsat TM data (30m spatial resolution) using a new established model. Those three aspects together revealed details of SSC changes induced by HBB. When water turbidity was low upstream, SSC increased 3% - 60% (8.4 mg. l-1 -176.29 mg. l-1) downstream. In general, the more turbid the water in upstream, the less SSC increases amplitude downstream. If water turbidity was high (> 350 mg. l-1) upstream, SSC decrease can be observed in the range of 300 meters or further downstream from the bridge. It decreases nearly 2% -17.5% (12.6 mg. l-1-62.98 mg. l-1). This study shows that Landsat TM data and corresponding methods can display the changing patterns of SSC induced by a nearshore bridge in coastal waters.

  15. Major and trace elements in sediments from Terra Nova Bay, Antarctica

    International Nuclear Information System (INIS)

    The concentrations of trace metals (Be, Bi, Cd, Cr, Mn, Ni, Pb, Sn, Zn), aluminium, iron and total organic carbon (TOC) were determined in sediments collected in Antarctica (Terra Nova Bay-Ross Sea). Samples were analysed by atomic absorption spectrometry with either flame or flameless techniques. Chemical data were evaluated taking into account the textural and compositional character of the sediments. The mean concentration levels of the elements in the <2 mm granulometric fraction were (mg/kg): Be: 2.04±0.25; Bi ≤0.8; Cd: 0.26±0.16; Cr: 20.3±8.3; Mn: 359±108; Ni: 6.31±3.5; Pb: 20.7±2.8; Sn: 2.12±0.71; Zn: 42.3±10.4; Al: 56-100±3900; Fe: 16-400±4800. The mean value of TOC was 0.34±0.20 g%. In the <63 μm fraction higher levels were observed for all the elements, with the exception of Al and Be. Both petrographic and chemical analyses showed differences between the samples collected in Terra Nova Bay and the sample from Wood Bay. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  16. Sedimentation rates and fluxes in the continental shelf mud fields in the Bay of Biscay (France)

    Science.gov (United States)

    Lesueur, P.; Jouanneau, J.-M.; Boust, D.; Tastet, J.-P.; Weber, O.

    2001-08-01

    Sedimentation rates in shelf mud fields of the Bay of Biscay (the Gironde shelf mud patches and "La Grande Vasière") were investigated for a 100-yr time scale, using 210Pb geochronology of nine cores. The distribution of apparent sedimentation rates reveals a general trend along the terrigenous dispersal system from the Gironde outlet of: no or negligible (sedimentation in the inner zone of the mud fields; 0.1-0.2 cm yr -1 in the outer zone where the supply is reduced; and a maximum value of about 0.5 cm yr -1 in the depocentre of the main mud field. Except for the latter value, the 210Pb sedimentation rates are of the same magnitude as longer-term rates based on 14C, and although slightly higher, are in good agreement with an earlier estimation determined for the rate of accumulation of surficial sediments, using pollen analyses. These differences are interpreted as being due to an increase in the supply of fine-grained sediment over the last century (from 0.2 to 0.5 cm yr -1), perhaps as a result of an intensification of estuarine suspended matter supply to the shelf. Compilation of a sediment budget shows that about one third of the annual Gironde solid discharge is trapped in the Gironde nearshore shelf mud fields. The mid-shelf muddy belt (i.e. "La Grande Vasière") is the site of accumulation of fine-grained material from various terrigenous sources (mainly from the Gironde and Loire rivers). Two cores from the latter area yielded a maximum rate of sedimentation of 0.2 cm yr -1. Mixing processes dominate in this open middle shelf, due to the periodic sediment removal by long-period swells and bioturbation.

  17. Heavy metal contamination from historic mining in upland soil and estuarine sediments of Egypt Bay, Maine, USA

    Science.gov (United States)

    Osher, L. J.; Leclerc, L.; Wiersma, G. B.; Hess, C. T.; Guiseppe, V. E.

    2006-10-01

    Concentrations of Cd, Cu, Pb and Zn in sediments of Egypt Bay in Hancock County, Maine, are elevated above background levels. The source of the contamination is Cu mining that occurred in the uplands adjacent to Egypt Stream between 1877 and 1885. Egypt Stream is a tributary to Egypt Bay. Egypt Bay is part of the Taunton Bay estuary system. The Hagan Mine was one of the mines extracting metals from the sulfide deposits in Downeast Maine north of Penobscot Bay. Metal concentrations were determined using ICP-AES after sample digestion with nitric acid. Soil collected from the coarse textured mine tailings pile contained elevated concentrations of Cd, Cu, Pb and Zn, but the majority of the surface soils at the Hagan Mine site were not contaminated. Estuary sediments from the surface to 100 cm depth were collected in four locations within Egypt Bay. Below 40 cm, metal concentrations in sediments were similar to those in uncontaminated upland soils. Metal concentrations in the estuary sediments between the surface and 26 cm were above background levels. According to 210Pb dating, the sediment at 26-34 cm depth was likely to have been deposited at the time the historic mines were in operation. Concentrations of Cd, Cu, Pb, and Zn in sediment from the 32-34 cm depth interval are similar to concentrations in the upland soil sample from the mine tailings pile. Elevated Pb concentrations in sediments from the surface to 24 cm are from atmospheric Pb deposition from anthropogenic sources. Sediment in the top 10 cm of the estuary has been mixed both by the polychaete worm Nereis virens and by those harvesting the worms for sale as fish bait.

  18. Metagenomic evidence for reciprocal particle exchange between the mainstem estuary and lateral bay sediments of the lower Columbia River

    Directory of Open Access Journals (Sweden)

    Mariya W Smith

    2015-10-01

    Full Text Available Lateral bays of the lower Columbia River estuary are areas of enhanced water retention that influence net ecosystem metabolism through activities of their diverse microbial communities. Metagenomic characterization of sediment microbiota from three disparate sites in two brackish lateral bays (Baker and Youngs produced approximately 100 Gbp of DNA sequence data analyzed subsequently for predicted SSU rRNA and peptide-coding genes. The metagenomes were dominated by Bacteria. A large component of Eukaryota was present in Youngs Bay samples, i.e. the inner bay sediment was enriched with the invasive New Zealand mudsnail, Potamopyrgus antipodarum, known for high ammonia production. The metagenome was also highly enriched with an archaeal ammonia oxidizer closely related to Nitrosoarchaeum limnia. Combined analysis of sequences and continuous, high-resolution time series of biogeochemical data from fixed and mobile platforms revealed the importance of large-scale reciprocal particle exchanges between the mainstem estuarine water column and lateral bay sediments. Deposition of marine diatom particles in sediments near Youngs Bay mouth was associated with a dramatic enrichment of Bacteroidetes (58% of total Bacteria and corresponding genes involved in phytoplankton polysaccharide degradation. The Baker Bay sediment metagenome contained abundant Archaea, including diverse methanogens, as well as functional genes for methylotrophy and taxonomic markers for syntrophic bacteria, suggesting that active methane cycling occurs at this location. Our previous work showed enrichments of similar anaerobic taxa in particulate matter of the mainstem estuarine water column. In total, our results identify the lateral bays as both sources and sinks of biogenic particles significantly impacting microbial community composition and biogeochemical activities in the estuary.

  19. 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.

  20. Multi-elemental analysis of marine sediments of Manila Bay using x-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    An analysis of the marine sediments of Manila Bay was done by employing X-ray fluorescence spectrometry. The general trends observed in sediments are increasing (Ca and Sr), decreasing (Zr), or constant (Cl, Na, S, K) with respect to depth, sometimes, no trend can be observed. These trends are further explained by correlations present among these elements, plus all the other elements. The two X RF data analysis methods Auto Quantify and AXIL were also compared on the basis of the correlation plot obtained. AutoQuantify gave clearer correlations; thus, results from this method were used for constructing correlation plots. Correlations using Microsoft Excel and Stat graphics Centurion X V show that there are naturally occurring [lithogenic (Si, Ti, Al, Mg, Rb, Zn and Fe), biogenic (Ca, Mg), and conservative (Na, Cl)] and non-naturally occurring [mostly anthropogenic, brought to the bodies of water by aeolian or fluvial input (heavy metals Pb-Cu-Zn and Ni-Cr)] correlation present in the sediments. Moreover, pairs of elements that may coexist in a source and not coexist in another (Cr and Mg, Cr and Ni) have also been observed. The heavy metal enrichment was attributed to the burning of fossil fuels, iron and steel manufacturing (present in Valenzuela-Bulacan area), ferry and fishing services and other industrialization activities present in Manila Bay. Marine organisms are affected by the presence of these heavy metals by means of bioaccumulations, and may later on affect humans because of trophic transfer and bio magnification. (author)

  1. Potentially Toxic Metal and Metalloid Fractionation Contamination in Sediments of Daya Bay, South China Sea

    Directory of Open Access Journals (Sweden)

    L. L. Cao

    2015-05-01

    Full Text Available The metal profiles in sediments of the Daya Bay (DYB in China were established using sequential extraction protocols proposed by the European Community Bureau of Reference (BCR. The surface sediment samples from 23 representative stations were collected in 2011 and were analysed to evaluate the mobility and bioavailability of a suite of potentially toxic metals (Cr, Cu, Ni, Zn, Pb and Cd and metalloid (As. The obtained ranking order of migration and transformation, and the degree of pollution was Pb > Cd > Cu > Zn > Ni > Cr > As. Among these elements, Pb is considered to pose a serious threat to human health and ecological environment due to its significant percentage in non-residual form. The ratios of secondary and primary phases showed that studied sediments are moderately to heavily polluted with Cu and Zn, and Cd and Pb respectively. The levels of association between the variables (metal-metalloid at each step of sequential extractions were evaluated with multivariate statistical analysis, including correlation analysis and principal components analysis. With these analyses, the possible sources of potential pollution were deduced. The correlation analysis revealed that Total Organic Carbon content is the most important influencing factor affecting the distribution of potentially toxic elements in Daya Bay. The principal components analysis (PCA suggested that the studied elements in DYB area originate primarily from natural weathering and secondly from industrial wastewater and aquaculture waste water.

  2. Heavy metal pollution in tidal zones of Bohai Bay using the dated sediment cores

    Institute of Scientific and Technical Information of China (English)

    QIN Yan-wen; MENG Wei; ZHENG Bing-hui; SU Yi-bin

    2006-01-01

    Three sediment cores were collected in November 2003 from Dagu estuary to Qikou estuary. The main polluted heavy metals in the sediment of tidal zones for the Bohai Bay have been found by analyzing the relationship among the contents of heavy metals, the contents of geochemical elements (Fe, Al and Mn) and the size of grain. The dominating contaminative elements in tidal sediments of Bohai Bay are Pb, Zn and Cd. Their contents are higher than the corresponding upper limit of environmental background values and they have very faint correlation with the corresponding contents of geochemical elements and the size of grain, indicating the anthropogenic enrichment. Especially, the preliminary study on the pollution sources and the history of heavy metals in the Dagu estuary has been done using the dated results. The contamination by Zn and Cd also started in the middle 1950s, while the contamination by Pb appeared in the early 1940s. The pollution by Zn and Cd mainly originate from sewage discharge, while the pollution by Pb has many sources, like atmosphere deposition and industrial discharge.

  3. Evaluation of recent sedimentation rates in Guajara Bay (N Brazilian coast) with 210Pb and 137Cs

    International Nuclear Information System (INIS)

    In the last 50 years the Amazon region suffered the negative effects of urban growth and industrial and agricultural development. Belem, capital city of the state of Para located, is one of its greatest urban centers, and, within its influence, Guajara Bay receives wastes discharges from Belem, which introduce many organic and inorganic contaminants to this bay. As the environmental accumulation of these pollutants is deeply related to intensity and volume of sediments deposition, this study aims to evaluate recent sedimentation rates (in a time range of 60 years) in Guajara Bay. By using high resolution gamma spectrometry, a nuclear technique proper for the analysis of radionuclides 137Cs and 210Pb, recent sedimentation rates were assessed in three sediment cores collected in 2011. The mean sedimentation rates found were 0.85 ± 0.12 cm yr-1for Anadim core, 1.02 ± 0.17 cm yr-1for Outeiro core and 0.53 ± 0.04 cm yr-1for Tucunduba core, which are within the range of expected values for systems such as bays, estuaries and lagoons with anthropic presence (the case of Guajara Bay). (author)

  4. Study of sedimentation rates in the coastal areas of manila bay using /sup 210/Pb-dating technique

    International Nuclear Information System (INIS)

    The presence of toxic Harmful Algal Blooms (HAB) has been reported in more than 20 areas in the Philippine after its first record occurrence in 1983. The HAB causing organism (Pyrodinium bahamense var compressum) normally produces a temporary and resting cyst during its life cycle. These cysts, which are deposited in the sediment column of the affected Bay, may play an important role in initiating the next episode of toxic bloom. To provide an age control to the cyst, produced by the causative organism, several cores have been collected from the Bay and analyzed for /sup 210/Pb using alpha spectrometry. The surface activity of these sediments ranged from 22 plus minus 4 to 110 plus minus 8 Bqkg/sup -1/ with an average value of 68.3 plus minus 38 Bqkg/sup -1/. The derived /sup 210/Pb vertical profile indicates a marked increase in sedimentation rate during the last ten years in the deeper portions of the bay. Higher sedimentation rates about 1 cm y/sup -l/ have been observed in the northern and western parts of the Manila Bay. Results indicate that the sedimentation process occurring in the Bay would require subsurface cyst concentration analysis in evaluating the potential of an area to act as seed-bed. (author)

  5. Summertime tidal flushing of Barataria Bay: Transports of water and suspended sediments

    Science.gov (United States)

    Li, Chunyan; White, John R.; Chen, Changsheng; Lin, Huichan; Weeks, Eddie; Galvan, Kari; Bargu, Sibel

    2011-04-01

    Inlets provide a critical ecological link between restricted bays and estuaries to the coastal ocean. The net fluxes of water and suspended sediment are presented in this study. These fluxes are obtained based on data from a multidisciplinary, full tidal cycle survey across Barataria Pass in southern Louisiana on 31 July to 1 August 2008. The velocity profiles were obtained with an acoustic Doppler current profiler mounted on a small boat continuously crossing the inlet, which contains swift and turbulent tidal currents. Water samples were collected six times in a 24 h period at three discrete depths and three locations across the inlet. The observations delineated a clear eddy on the western side of the inlet which causes a low R2 value of the tidal harmonic analysis on the edges of the inlet. The net flux of total suspended sediment out of the bay was determined to be 8800 t of which 20% was organic matter, demonstrating a significant source of organic matter to the base of the coastal ocean detrital food chain. The time evolution and net fluxes of water, and suspended sediments showed that the net flow resembles conventional estuarine circulation patterns with net outward flow on the surface and shallow ends of the inlet and with net inward flow in the center and at the bottom of the center of the inlet. The west side has a much larger outward flow than the east side while the east side is fresher. These differences suggest that the Louisiana Coastal Current from around the Bird's Foot Delta derived from the mixing of shelf water with the Mississippi River freshwater may have entered the bay. This must have been mostly from the east side during the survey, which resulted in a smaller outward flow on the eastern side. A numerical experiment further confirmed this assumption and the model was verified by field observations on 5 May 2010.

  6. Storm-induced inner-continental shelf circulation and sediment transport: Long Bay, South Carolina

    Science.gov (United States)

    Warner, John C.; Armstrong, Brandy; Sylvester, Charlene S.; Voulgaris, George; Nelson, Tim; Schwab, William C.; Denny, Jane F.

    2012-07-01

    Long Bay is a sediment-starved, arcuate embayment located along the US East Coast connecting both South and North Carolina. In this region the rates and pathways of sediment transport are important because they determine the availability of sediments for beach nourishment, seafloor habitat, and navigation. The impact of storms on sediment transport magnitude and direction were investigated during the period October 2003-April 2004 using bottom mounted flow meters, acoustic backscatter sensors and rotary sonars deployed at eight sites offshore of Myrtle Beach, SC, to measure currents, water levels, surface waves, salinity, temperature, suspended sediment concentrations, and bedform morphology. Measurements identify that sediment mobility is caused by waves and wind driven currents from three predominant types of storm patterns that pass through this region: (1) cold fronts, (2) warm fronts and (3) low-pressure storms. The passage of a cold front is accompanied by a rapid change in wind direction from primarily northeastward to southwestward. The passage of a warm front is accompanied by an opposite change in wind direction from mainly southwestward to northeastward. Low-pressure systems passing offshore are accompanied by a change in wind direction from southwestward to southeastward as the offshore storm moves from south to north. During the passage of cold fronts more sediment is transported when winds are northeastward and directed onshore than when the winds are directed offshore, creating a net sediment flux to the north-east. Likewise, even though the warm front has an opposite wind pattern, net sediment flux is typically to the north-east due to the larger fetch when the winds are northeastward and directed onshore. During the passage of low-pressure systems strong winds, waves, and currents to the south are sustained creating a net sediment flux southwestward. During the 3-month deployment a total of 8 cold fronts, 10 warm fronts, and 10 low-pressure systems

  7. Biochemical response of amphipods (Gammarid: Paramorea) in a sediment laboratory exposure from Ushuaia Bay, Beagle Channel.

    Science.gov (United States)

    Schvezov, Natasha; Amin, Oscar

    2011-03-01

    A coastal system (Ushuaia Bay, Argentina) impacted by anthropogenic activities was studied by the response of local amphipods (Parmorea sp., Gammaridae) to the exposure of coastal sediments in a laboratory assay. Four coastal areas with different loadings of contaminants and one considered as reference were studied. Organic matter, carbohydrates, proteins and heavy metals were measured in sediment samples. Organisms were exposed to sediments for seven days and catalase (CAT), glutathione S-transferase (GST), acetylcholinesterase (AChE) and lipid peroxidation (LPO) were measured afterward. Amphipods exhibited an activation of GST and inhibition of AChE in most impacted areas. Principal Component Analysis (PCA) was conducted in order to associate the biological responses with sediment metal concentration and its eutrophicated status. Levels of Cd and Cr were associated with the inhibition of AChE and with the enhancement of GST. CAT and LPO were enhanced in most areas, but no link was found with the contaminants studied by PCA, suggesting that other parameters present in sediments not included in the PCA affect the amphipods. The most impacted area corresponds to Nautical Club station, with a highly eutrophicated status and high content of metals, where amphipods after the exposure were affected in a biochemical level. PMID:21239059

  8. Shift in detrital sedimentation in the eastern Bay of Bengal during the late Quaternary

    Digital Repository Service at National Institute of Oceanography (India)

    PrakashBabu, C.; Pattan, J.N.; Dutta, K.; Basavaiah, N.; Prasad, G.V.K.; Ray, D.K.; Govil, P.

    carried out using the Malvern laser particle size analyzer (Master-Sizer 2000) after removing carbonate and organic carbon. The 14 C measurements were done by accelerator mass spectrometry (AMS), using the NEC 3MV 9SDH-2 pelletron accelerator... sedimentation in the eastern Bay of Bengal 293 sand content, χ LF , χ ARM and SIRM due to less intense monsoon. Decrease in terrigenous sedimen- tation is responsible for high CaCO 3 and biogenic elements content. As a matter of fact the produc- tivity was low...

  9. Chronic sublethal effects of San Francisco Bay sediments on nereis (neanthes) arenaceodentata; effect of food ration on sediment toxicity. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Moore, D.W.; Dillon, T.M.

    1993-09-01

    This report is designed to address concerns regarding the effect of food ration on toxicity during chronic sublethal sediment bioassays. To this end, a contaminated San Francisco Bay sediment and a clean control sediment were evaluated in a chronic sublethal test under a series of different food rations, with the marine polychaete worm Nereis (Neanthes) arenaceodentata. Animals were exposed from early juvenile stage through the onset of gametogenesis. Treatments were 2.OX, 1.OX, 0.5X, and 0.25X where X is the recommended food ration for laboratory cultures. Test end points were survival, growth, and reproduction. The contaminated sediment was a composite of several cores taken to project depth (38 ft (11.6 m) below mean low water mark) from an area in Oakland Inner Harbor known to be contaminated with polycyclic aromatic hydrocarbons and metals. Comparisons were made with a clean control sediment. The control sediment is used in the laboratory cultures of N. arenaceodentata and was collected from Sequim, WA. Mean percent survival of Neanthes was high (>90 percent) in both the contaminated and control sediment across all food ration treatments. Individual wet weights were significantly reduced with decreasing food ration in both contaminated and control sediments. Significant differences in wet weight between sediment types were observed at the 1.OX, 0.5X, and 0.25X rations. Reproduction (fecundity and emergent juvenile (EJ) production) was also Chronic sublethal, Neanthes, Dredged material, San Francisco Bay, Food ration, Sediment.

  10. Soil Erosion and Sediment Losses from the Ridge Watersheds in the Guánica Bay, Puerto Rico

    Science.gov (United States)

    Yuan, Yongping; Taguas, Encarnación; Hu, Wenhui

    2014-05-01

    Puerto Rico faces considerable challenges regarding sustainable land use and effects of land use on adjacent coastal ecosystems and the services they provide. One primary concern is increased sediment loading to reservoirs and ultimately to Guánica Bay and reef areas outside the Bay. Studies by scientists in Puerto Rico have suggested that nutrient and sediment contaminants have increased 5 to 10 fold since pre-colonial levels and an additional 2 to 3 fold in the last 40-50 years (Sturm et al., 2012). Sediment deposition has significantly reduced the storage capacity of several reservoirs, and the associated contaminants and nutrients within the terrestrial soil particles of sediment can stress corals and negatively impact reef health. Sedimentation can also reduce photosynthetic activity of aquatic plants and algae, and increase water-treatment costs for domestic and industrial uses (Estades Hernández, 1997). Therefore, it is important to understand soil erosion and sediment transport processes. In this study, we analyze sediment losses from ridge watersheds of the Guánica Bay and try to understand the main factors causing soil erosion and sediment in those ridge watersheds. Our specific objectives were: 1) to quantify sediment contributions to Guánica Bay and identify sediment sources; 2) seek factors that impact the sediment loss and explore alternative strategies to reduce soil erosion and sediment loading to the reservoirs, Guánica Bay and the coastal zone. It was found that sediment loss in those ridge watersheds was mainly caused by interaction of heavy rainfall (especially the hurricanes) and steep mountainous slopes. Coffee planting increased the risk of soil erosion, which the loss of protective canopy for sun-grown coffee exacerbated. In addition, rainy seasons (February to May and August to November) contributed more than 80% of annual sediment loss. Exploration of different land use scenarios found that coffee land use yielded more sediment per

  11. Total mercury in water and sediment from Honda Bay area in Palawan

    International Nuclear Information System (INIS)

    This project is intended to pinpoint the sources of mercury contamination from the Honda Bay area in Palawan. Sampling sites were pinpointed which water and sediment samples were to be taken and kept in virgin polyethylene liter bottles. Analytical procedures were applied. The results of the analysis for total mercury content vary cosiderably from ml, less than 0.003 ng/9 to high of 0.419 ng/g with a considerable number of the sample going above the 0.100 ng/g level. Sediment samples also gave similar results, from a low of 0.004 ng/g to value higher than 2 ng/g round the jetty. It can be concluded, therefore, that the area surveyed is contaminated with mercury but not severely so. (author)

  12. Persistence and growth of faecal culturable bacterial indicators in water column and sediments of Vidy Bay, Lake Geneva, Switzerland

    Institute of Scientific and Technical Information of China (English)

    POTE John; HALLER Laurence; KOTTELAT Régis; SASTRE Vincent; ARPAGAUS Philippe; WILDI Walter

    2009-01-01

    The aims of this study was to investigate the persistence and the growth of culturable bacterial indicators (CBI) including total coliforms (TC) and faecal coliforms represented by E. coli, enterococcus (ENT), and aerobic mesophilic bacteria (AMB) in the surface sediments and the water column of the Bay of Vidy (Lake Geneva, City of Lausanne, Switzerland). The study was carried out for 60 d using microcosms containing Sewage Treatment Plant (STP) effluent water and non-sterile water without CBI, as well as contaminated and non-contaminated sediments. The effects of water temperature and of organic matter associated with sediments on the survival of CBI in the sediments and the water column were observed. The number of CBI colonies in the contaminated sediments of Vidy Bay and in the STP effluent water was almost identical in the order of 105--107, 104--106, 103--105, and 104--107 CFU/100 g sediment or /100 mL water for TC, E. coli, ENT, and AMB respectively. A degradation of CBI was observed in the sediments where organic mater content was low and in the water column at a temperature of 10℃ after 5 d of experimentation. In addition, a growth of CBI was observed in the sediment which is rich in organic matter at a temperature of 20℃. The results of this study indicate: (1) the higher concentrations of the CBI observed in different points in the water column of Vidy Bay may not be explained only by the recent contribution of the three potential sources of the Bay contamination including STP and the Chamberonne and Flon Rivers, but also by the persistence, removal from sediment and multiplication of CBI in the sediment and water column; (2) the sediment of Vidy Bay constitute a reservoir of CBI and can even support their growth. (3) the CBI not only survive in sediments, but also can be remobilized and increased in the water column, therefore it become a permanent microbiological pollution in Vidy Bay.

  13. Sediment characterization in intertidal zone of the Bourgneuf bay using the Automatic Modified Gaussian Model (AMGM)

    Science.gov (United States)

    Verpoorter, C.; Carrère, V.; Combe, J.-P.; Le Corre, L.

    2009-04-01

    Understanding of the uppermost layer of cohesive sediment beds provides important clues for predicting future sediment behaviours. Sediment consolidation, grain size, water content and biological slimes (EPS: extracellular polymeric substances) were found to be significant factors influencing erosion resistance. The surface spectral signatures of mudflat sediments reflect such bio-geophysical parameters. The overall shape of the spectrum, also called a continuum, is a function of grain size and moisture content. Composition translates into specific absorption features. Finally, the chlorophyll-a concentration derived from the strength of the absorption at 675 nm, is a good proxy for biofilm biomass. Bourgneuf Bay site, south of the Loire river estuary, France, was chosen to represent a range of physical and biological influences on sediment erodability. Field spectral measurements and samples of sediments were collected during various field campaigns. An ASD Fieldspec 3 spectroradiometer was used to produce sediment reflectance hyperspectra in the wavelength range 350-2500 nm. We have developed an automatic procedure based on the Modified Gaussian Model that uses, as the first step, the Spectroscopic Derivative Analysis (SDA) to extract from spectra the bio-geophysical properties on mudflat sediments (Verpoorter et al., 2007). This AMGM algorithm is a powerfull tool to deconvolve spectra into two components, first gaussian curves for the absorptions bands, and second a straight line in the wavenumber range for the continuum. We are investigating the possibility of including other approaches, as the inverse gaussian band centred on 2800 nm initially developed by Whiting et al., (2006) to estimate water content. Additionally, soils samples were analysed to determine moisture content, grain size (laser grain size analyses), organic matter content, carbonate content (calcimetry) and clay content. X-ray diffraction analysis was performed on selected non

  14. Spreading of the ocean floor: Undeformed sediments in the peru-chile trench

    Science.gov (United States)

    Scholl, D. W.; Von Huene, R.; Ridlon, J.B.

    1968-01-01

    None of the expected stratigraphic and structural effects of a spreading sea floor have been imposed on the sedimentary fill of the Peru-Chile Trench. During at least the last several million years, and perhaps during much of the Cenozoic, the trench has not been affected by an oceanic crust thrusting under the continent.

  15. Lead and Stable Isotopes in Sediments of Babitonga Bay: An Oil Spill Case

    International Nuclear Information System (INIS)

    The hydrologic complex of Babitonga Bay (Brazil) forms a vast environmental complex, hosting the last great mangrove bulk of the southern hemisphere. Mangroves are among the most productive ecosystems on earth. The effects of an oil spill were studied in Babitonga Bay using lead and carbon isotopes. Samples of the spilled oil were obtained nine months after the accident, as well as sediment and water samples. Thus, the isotopic composition of the oil allowed the tracing of the environmental pollution. Notwithstanding the delay in time, isotopes of lead and carbon allowed the identification of areas where the presence of the oil can be still detected, permitting assessment of the extent of pollution. Contaminated sediments exhibited an isotopic composition (206Pb/207Pb and 208Pb/206Pb) close to that of the oil spilled. Moreover δ13C also permitted the ratification of these results. Others isotopes were used but with no contributions. Conclusions are derived in terms of the source of the pollution in the specific area. (author)

  16. Mixing and sediment resuspension associated with internal bores in a shallow bay

    Science.gov (United States)

    Masunaga, Eiji; Homma, Hikaru; Yamazaki, Hidekatsu; Fringer, Oliver B.; Nagai, Takeyoshi; Kitade, Yujiro; Okayasu, Akio

    2015-11-01

    Observations of the run-up of internal bores in a shallow bay were made with a tow-yo instrument and mooring arrays with high spatial and temporal resolution. Shoreward propagating internal bores have been studied with laboratory experiments and numerical models, but few observational studies have shown the detailed structure of the run-up of internal bores induced by internal tides. Our observations showed that internal bores propagate along the slope, accompanied by strong turbulent mixing and strong sediment resuspension in a shallow bay. The isothermal displacement due to the bores reached 20 m vertically in a water depth of 40 m. Turbidity measurements showed suspended particles transported from the sloping bottom and offshore above the thermocline, forming an intermediate nepheloid layer (INL). At the head of the bore (dense water), a vortex accompanied by strong vertical motion induced strong vertical sediment resuspension and a steep isothermal displacement. The rate of turbulent kinetic energy dissipation reached 10-6 W kg-1 at the head of the wave. A nonhydrostatic numerical simulation in a two-dimensional domain reproduced fine features associated with the run-up of an internal bore and the vortex motion at its head.

  17. Effect of Development of Caofeidian Harbor Area in Bohai Bay on Hydrodynamic Sediment Environment

    Institute of Scientific and Technical Information of China (English)

    LU Yong-jun; ZUO Li-qin; JI Rong-yao; XU Xiao; HUANG Jian-wei

    2008-01-01

    Based on the characteristics of waves, tidal currents, sediment and seabed evolution in the Caofeidian sea area in the Bohai Bay, a 2D sediment mathematical model of waves and tidal currents is employed to study the development schemes of the harbor. Verification of spring and neap tidal currents and sediment in the winter and summer of 2006 shows that the calculated values of tidal stages as well as flow velocities, flow directions and sediment concentration of 15 synchronous vertical lines are in good agreement with the measured data. Also, deposition and erosion of the sea area in front of Caofeidian ore terminal induced by suspended load under tidal currents and waves are verified; it shows that the calculated values of depth of deposition and erosion as well as their distribution are close to the measured data. Furthermore, effects of reclamation scheme of island in front of the land behind Caofeidian harbor on the hydrodynamic environment are studied, including changes of flow velocities in the deep channels at the south side of Caofeidian foreland and Laolonggou and in various harbor basins, as well as changes of deposition and erosion of seabed induced by the project.

  18. Seasonality of community structure and carbon flow in Narragansett Bay sediments

    International Nuclear Information System (INIS)

    Seasonal patterns of benthic community dynamics and the pathways of detrital decomposition in Narragansett Bay were examined. Benthic meiofauna and macrofauna exhibited a pronounced seasonality, with peak abundances in the late spring and minima in the late summer. This pattern was most pronounced for surface dwelling fauna, particularly harpacticoid copepods. These results were attributed to the seasonality of detrital inputs to the sediment and the fate of these inputs. A six month study in which 14C-sodium bicarbonate was added to a large (13 m3) microcosm enabled the author to observe pathways of carbon flow. Half of the labeled organic carbon that was deposited on the sediment during the winter and spring was found in the sediment in July. At least 20 gC/m2 had accumulated since December. Within the sediment, the existence of two discrete food webs was distinguished by measurement of faunal specific activity. Surface fauna, dominated by the meiofauna, exclusively assimilate fresh (labeled) organics, while subsurface fauna (meiofauna and macrofauna) predominantly assimilated older, non-labeled organics for the duration of the study. Only the subsurface food web had access to the storage of buried detritus. While there was a surplus of detritus for both food webs during the winter and spring, the authors expect that benthic respiration rates exceed organic deposition rates during the summer. Detrital storage may be critical for the survival of the fauna through the summer

  19. Source identification of heavy metal contamination using metal association and Pb isotopes in Ulsan Bay sediments, East Sea, Korea

    International Nuclear Information System (INIS)

    Highlights: • The levels of Cu, Zn, and Pb in sediments were higher than the Korean TEL at one-third of all sites. • The primary source of metal contamination came from activities related to nonferrous metal refineries near Onsan Harbor. • Three different anthropogenic sources and background sediments could be identified as endmembers using Pb isotopes. • The major anthropogenic Pb sources were identified as imported ores from Australia and Peru. • Isotope ratios in anthropogenic Pb discharged from Ulsan Bay to offshore could be identified. - Abstract: To determine the characteristics of metal pollution sources in Ulsan Bay, East Sea, 39 surface and nine core sediments were collected within the bay and offshore area, and analyzed for metals and stable lead (Pb) isotopes. Most surface sediments (>95% from 48 sites) had high copper (Cu), zinc (Zn), cadmium (Cd), and Pb concentrations that were as much as 1.3 times higher than background values. The primary source of metal contamination came from activities related to nonferrous metal refineries near Onsan Harbor, and the next largest source was from shipbuilding companies located at the mouth of the Taehwa River. Three different anthropogenic sources and background sediments could be identified as end-members using Pb isotopes. Isotopic ratios for the anthropogenic Pb revealed that the sources were imported ores from Australia, Peru, and the United States. In addition, Pb isotopes of anthropogenic Pb discharged from Ulsan Bay toward offshore could be determined

  20. Concentrations of heavy metals in sediment and organisms during a harmful algal bloom (HAB) at Kun Kaak Bay, Sonora, Mexico

    International Nuclear Information System (INIS)

    In early April 2003, fishermen from Kino Bay Sonora alerted us about a massive die-off of fish and mollusks occurring at Kun Kaak Bay. Phytoplankton samples taken on 17 May 2003 reported the presence of a harmful algal bloom composed of Chatonella marina, Chatonella cf. ovata, Gymnodinium catenatum and Gymnodinium sanguineum. On 22 of May, we collected samples of water, sediment and organisms at the affected area. Physicochemical parameters and nutrients were measured in water samples from different depths. Sediment and benthic organisms were analyzed for Cd, Cu, Zn, Pb and Hg. We found concentrations of heavy metals higher than background levels for this area. Cadmium and Lead concentrations in sediment from the HAB area were up to 6x greater than background levels and Cd in mollusks was 8x greater than regulations allow. A relationship between elevated Cd and Pb concentrations in sediment and the survival of toxic dinoflagellates is suspected

  1. Concentrations of heavy metals in sediment and organisms during a harmful algal bloom (HAB) at Kun Kaak Bay, Sonora, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Hernandez, Jaqueline [Centro de investigacion en Alimentacion y Desarrollo AC (CIAD) Guaymas Unit, Carretera al Varadero Nal. Km 6.6, Apdo. Postal 284, CP 85480 Guaymas, Sonora (Mexico)]. E-mail: jaqueline@cascabel.ciad.mx; Garcia-Rico, Leticia [Centro de investigacion en Alimentacion y Desarrollo AC (CIAD), Carretera a la Victoria Km 0.6, Apdo. Postal 1735, CP 83000 Hermosillo, Sonora (Mexico)]. E-mail: lgarciar@cascabel.ciad.mx; Jara-Marini, Martin E. [Centro de investigacion en Alimentacion y Desarrollo AC (CIAD), Carretera a la Victoria Km 0.6, Apdo. Postal 1735, CP 83000 Hermosillo, Sonora (Mexico)]. E-mail: mjara@cascabel.ciad.mx; Barraza-Guardado, Ramon [Departamento de Investigaciones Cientificas y Tecnologicas de la Universidad de Sonora (DICTUS), Rosales y Ninos Heroes s/n Col. Centro, CP 83000 Hermosillo, Sonora (Mexico)]. E-mail: rbarraza@rtn.uson.mx; Hudson Weaver, Amy [Comunidad y Biodiversidad AC - COBI, Terminacion Bahia de Bacochibampo s/m, Fraccionamiento Lomas de Cortes, CP 85450 Guaymas, Sonora (Mexico)]. E-mail: ahw@cobi.org.mx

    2005-07-01

    In early April 2003, fishermen from Kino Bay Sonora alerted us about a massive die-off of fish and mollusks occurring at Kun Kaak Bay. Phytoplankton samples taken on 17 May 2003 reported the presence of a harmful algal bloom composed of Chatonella marina, Chatonella cf. ovata, Gymnodinium catenatum and Gymnodinium sanguineum. On 22 of May, we collected samples of water, sediment and organisms at the affected area. Physicochemical parameters and nutrients were measured in water samples from different depths. Sediment and benthic organisms were analyzed for Cd, Cu, Zn, Pb and Hg. We found concentrations of heavy metals higher than background levels for this area. Cadmium and Lead concentrations in sediment from the HAB area were up to 6x greater than background levels and Cd in mollusks was 8x greater than regulations allow. A relationship between elevated Cd and Pb concentrations in sediment and the survival of toxic dinoflagellates is suspected.

  2. Inorganic As speciation and bioavailability in estuarine sediments of Todos os Santos Bay, BA, Brazil

    International Nuclear Information System (INIS)

    Research highlights: → Total concentration of As at several stations along Todos os Santos Bay, was above TEL value. → At Subae and Paraguacu systems, As (V) was the dominant species, which is less toxic and less mobile than As (III). → Arsenic concentrations at Jaguaripe estuary were higher than in other estuaries and As (III) was the dominant species. → Relationship between As, Fe, Mn and sand indicated that As enrichment at Jaguaripe River is natural. → As concentrations in sediments and biota suggest that As is bioavailable and it is accumulating in marine organisms, which may impose human risks. → Slurry sampling showed to be a easy, accurate procedure to be used for As determination in estuarine samples. - Abstract: The spatial distribution of As (total As, As (III) and As (V)) in estuarine sediments from the main tributaries of Todos os Santos Bay, BA, Brazil, was evaluated under high and low flow conditions. The concentrations of As were determined using a slurry sampling procedure with hydride generation atomic absorption spectrometry (HG-AAS). The highest concentrations were observed at estuary mouths, and exceeded conservative lower threshold value (Threshold Effects Level; TEL). Due to the oxic conditions and abundance of Mn and Fe (oxyhydr)oxides in the sediments, most inorganic arsenic in the Subae and Paraguacu estuaries was present as As (V). Nevertheless, the concentration of As (III) at several locations along the Jaguaripe River were also above the TEL value, suggesting that As may be toxic to biota. In the Subae estuary, antropogenic activities are the main source of As. At the Jaguaripe and at Paraguacu estuaries, nevertheless, natural sources of As need to be considered to explain the distribution patterns.

  3. Carbon sources supporting benthic mineralization in mangrove and adjacent seagrass sediments (Gazi Bay, Kenya

    Directory of Open Access Journals (Sweden)

    S. Bouillon

    2004-01-01

    Full Text Available The origin of carbon substrates used by in situ sedimentary bacterial communities was investigated in an intertidal mangrove ecosystem and in adjacent seagrass beds in Gazi bay (Kenya by δ13C analysis of bacteria-specific PLFA (phospholipid fatty acids and bulk organic carbon. Export of mangrove-derived organic matter to the adjacent seagrass-covered bay was evident from sedimentary total organic carbon (TOC and δ13CTOC data. PLFA δ13C data indicate that the substrate used by bacterial communities varied strongly and that exported mangrove carbon was a significant source for bacteria in the adjacent seagrass beds. Within the intertidal mangrove forest, bacterial PLFA at the surface layer (0-1cm typically showed more enriched δ13C values than deeper (up to 10cm sediment layers, suggesting a contribution from microphytobenthos and/or inwelled seagrass material. Under the simplifying assumption that seagrasses and mangroves are the dominant potential end-members, the estimated contribution of mangrove-derived carbon to benthic mineralization in the seagrass beds (16-74% corresponds fairly well to the estimated contribution of mangrove C to the sedimentary organic matter pool (21-71% across different seagrass sites. Based on the results of this study and a compilation of literature data, we suggest that trapping of allochtonous C is a common feature in seagrass beds and often represents a significant source of C for sediment bacteria - both in cases where seagrass C dominates the sediment TOC pool and in cases where external inputs are significant. Hence, it is likely that data on community respiration rates systematically overestimate the role of in situ mineralization as a fate of seagrass production.

  4. Response of marine sedimentation to upper Holocene climate variability in Maxwell Bay, King George Island, West Antarctic Peninsula

    Science.gov (United States)

    Wittenberg, Nina; Hass, Christian; Kuhn, Gerhard

    2013-04-01

    The Western Antarctic Peninsula experiences a temperature increase that is higher than in other parts of Antarctica. Within the last 50 years the tidewater glaciers in the tributary fjords of Maxwell Bay (King George Island) have retreated landwards with increasing speed. Meltwaters mobilize fine-grained sediments and transport those in plumes out of the coves into Maxwell Bay. Our hypothesis is that meltwater sediments characterize warmer climate periods of the Holocene. Marine sediment cores recovered along a profile of the eastern slope of Maxwell Bay were studied. The cores were taken in high-accumulation areas at the entrances of Collins Harbor, Marian and Potter coves. We measured the grain-size distribution in 1-cm steps in each core with a Laser diffraction particle analyzer (range 0.04-2500 µm) in order to resolve shifts in grain size compositions in very high resolution. We undertook different approaches for reliable age determination of the sediments. Since marine biogenic carbonate suitable for radiocarbon age determination is sparse, radiocarbon dating of the extracted humic acid fraction of the bulk sediment was included. Unfortunately, these age determinations turned out to be not reliable, likely because they are overprinted by an unknown older radiocarbon source. Preliminary results suggest that the cores cover approximately the last 2000 years. The magnetic susceptibility (MS) parameter fluctuates throughout the cores. It is negatively correlated to the amount of total organic carbon (TOC) and biogenic opal, suggesting dilution of the MS signal through higher input of organic material. Together with the bathymetry data, sub-bottom profiles reveal information on the interior of the topography and the geometry of the deposited sediments. The profiles obtained in Potter Cove show almost no sediment penetration suggesting either a very thin sediment cover and/or highly reworked unsorted sediments. The sub-bottom profiles from Maxwell Bay penetrate

  5. Distribution of Ammonia-Oxidizing Archaea and Bacteria in the Surface Sediments of Matsushima Bay in Relation to Environmental Variables

    OpenAIRE

    Sakami, Tomoko

    2011-01-01

    Ammonia oxidization is the first and a rate-limiting step of nitrification, which is often a critical process in nitrogen removal from estuarine and coastal environments. To clarify the correlation of environmental conditions with the distribution of ammonia oxidizers in organic matter-rich coastal sediments, ammonia-oxidizing archaea (AOA) and bacteria (AOB) ammonia monooxygenase alpha subunit gene (amoA) abundance was determined in sediments of Matsushima Bay located in northeast Japan. The...

  6. Osseous skeletal material and fish scales in marine sediments under the oxygen minimum zone off northern and central Chile

    Science.gov (United States)

    Milessi, Andrés C.; Sellanes, Javier; Gallardo, Víctor A.; Lange, Carina B.

    2005-08-01

    The significance of whale falls for the study of the biogeography, evolution and biodiversity of deep-sea biota has been recently recognized by international programs since large carcasses are known to give rise to biogenic chemosynthetic ecosystems. However, the plain accumulation of smaller bone material in the shallower settings of the continental shelf and upper slope under the hypoxic conditions of the Oxygen Minimum Zone (OMZ), has received much less attention. Here we describe new findings of skeletal material and fish scales in marine sediments under the OMZ off northern and central Chile which, combined with previous reports for the study area, lead us to suggest the existence of a band in the benthos of accumulation of bones and scales extending at least twenty degrees in latitude (18-38° S). Future studies should focus on the characterization of biotic communities living upon these resources in order to elucidate their peculiarities and importance in the Eastern South Pacific.

  7. Using 137Cs and 210Pbex and other sediment source fingerprints to document suspended sediment sources in small forested catchments in south-central Chile

    International Nuclear Information System (INIS)

    A study of the impact of forest harvesting operations on sediment mobilization from forested catchments has been undertaken in south-central Chile. The study focused on two sets of small paired catchments (treatment and control), with similar soil type, but contrasting mean annual rainfall, located about 400 km apart at Nacimiento (1200 mm yr−1) and Los Ulmos (2500 mm yr−1). The objective was to study the changes in the relative contribution of the primary sources of fine sediment caused by forestry operations. Attention focused on the pre-harvest and post-harvest periods and the post-replanting period was included for the Nacimiento treatment catchment. The sediment source fingerprinting technique was used to document the contributions of the potential sources. Emphasis was placed on discriminating between the forest slopes, forest roads and channel erosion as potential sources of fine sediment and on assessing the relative contributions of these three sources to the sediment yield from the catchments. The fallout radionuclides (FRNs) 137Cs and excess lead-210, the environmental radionuclides 226Ra and 40K and soil organic matter (SOM) were tested as possible fingerprints for discriminating between potential sediment sources. The Kruskal–Wallis test and discriminant function analysis were used to guide the selection of the optimum fingerprint set for each catchment and observation period. Either one or both of the FRNs were selected for inclusion in the optimum fingerprint for all datasets. The relative contribution of each sediment source to the target sediment load was estimated using the selected fingerprint properties, and a mixing model coupled with a Monte Carlo simulation technique that takes account of uncertainty in characterizing sediment source properties. The goodness of fit of the mixing model was tested by comparing the measured and simulated fingerprint properties for the target sediment samples. In the Nacimiento treatment catchment the

  8. Characterization of trace organic contaminants in marine sediment from Yeongil Bay, Korea: 2. Dioxin-like and estrogenic activities

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Chul-Hwan [School of Earth and Environmental Sciences (Oceanography), College of Natural Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of); Khim, Jong Seong [School of Earth and Environmental Sciences (Oceanography), College of Natural Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of)]. E-mail: jskocean@snu.ac.kr; Villeneuve, Daniel L. [U.S. Environmental Protection Agency, Mid-Continent Ecology Division, 6201 Congdon Blvd., Duluth, MN 55804-2595 (United States); Kannan, Kurunthachalam [Wadsworth Center, New York State Department of Health and Department of Environmental Health and Toxicology, State University of New York at Albany, Empire State Plaza, PO Box 509, Albany, NY 12201-0509 (United States); Giesy, John P. [National Food Safety and Toxicology Center, Department of Zoology, and Institute for Environmental Toxicology, Michigan State University, East Lansing, MI 48824 (United States); Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2006-07-15

    This study employed mechanism-specific in vitro bioassays to help characterize the occurrence and distribution of dioxin-like and estrogenic contaminants in sediment from Yeongil Bay, Korea. Approximately 85% of the sediments tested induced significant dioxin-like activity in the H4IIE-luc bioassay, while approximately 50% induced significant estrogenic activity in the MVLN bioassay. Instrumentally-derived estimates of 2,3,7,8-tetrachlorodibenzo-p-dioxin and 17{beta}-estradiol equivalents tended to underestimate the magnitude of response observed in the bioassays, suggesting that compounds detected by chemical analysis did not account for all the activity associated with Yeongil Bay sediments, or that non-additive interactions were occurring. The greatest dioxin-like and estrogenic activity was associated with the mid-polarity Florisil fractions (F2) expected to contain polycyclic aromatic hydrocarbons (PAHs) as well as chlorinated dioxins and furans. As in previous studies of Korean coastal sediment, more polar fractions (F3) generated more modest responses both in terms of magnitude and the number of samples responding. -- In vitro bioassay responses observed for Yeongil Bay surficial sediment and sediment core extracts showed the greatest dioxin-like and estrogenic activities in the mid-polarity fraction containing PAHs as well as chlorinated dioxins and furans.

  9. Partition of organochlorine concentrations among suspended solids, sediments and brown mussel Perna perna, in tropical bays.

    Science.gov (United States)

    Galvao, Petrus; Henkelmann, Bernhard; Longo, Renan; Dorneles, Paulo Renato; Torres, João Paulo Machado; Malm, Olaf; Schramm, Karl-Werner

    2014-11-01

    For evaluating the brown mussel Perna perna as a sentinel organism regarding environmental concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), the present study reports original data on the relationship between the concentrations of these chemicals in bottom surface sediments, suspended solids (SS) and concentrations bioaccumulated by this bivalve. Three P. perna cultivation areas, located at three bays in southeastern Brazil were used in this study. The three estuaries are under different degrees of environmental impact. Variations in the OCP and PCB concentrations bioaccumulated by the bivalves tended to be similar to those observed in the sediment, but differed from those found in SS. This latter difference might suggest that the SS trapping apparatuses should have been left in place for approximately 60 days (not only 15 days). This longer period would allow the integration of the environmental variability of the OCP and PCB burden adsorbed to this compartment. Authors encourage future studies to evaluate P. perna exposure to OCPs and PCBs through the evaluation of sediment concentrations. PMID:25113178

  10. Vertical distribution of tritium in core sediment of Mumbai Harbour Bay

    International Nuclear Information System (INIS)

    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 (3H) is ubiquitous in the aquatic environment and has a various sources of origin. It is transported to the earth's surface via hydrological cycle. 3H 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 3H 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

  11. Escherichia coli and Suspended Sediment in Berger Ditch at Maumee Bay State Park, Oregon, Ohio, 2006

    Science.gov (United States)

    Brady, Amie M.G.

    2007-01-01

    Berger Ditch discharges to the marina at Maumee Bay State Park (MBSP), just east of the MBSP bathing beach. Recent studies by U.S. Geological Survey (USGS) and University of Toledo researchers have identified the ditch as a source of Escherichia coli (E. coli), an indicator bacterium that is used to assess recreational water quality. An automatic sampler was installed at a USGS streamgage on Berger Ditch. Samples were collected as a function of streamflow, including negative flow conditions. Instantaneous discharges of E. coli and suspended sediment from Berger Ditch were calculated. When samples were collected, streamflow ranged from -21 to 227 cubic feet per second (ft3/s) and over the entire time period, streamflow ranged from -23 to 243 ft3/s. Discharges of E. coli ranged from 2.5 ? 108 to greater than 2.6 ? 1010 colony-forming units per second (cfu/s), and suspended-sediment discharges ranged from 0.01 to 2.2 kilograms per second (kg/s). One sample was collected during negative flow conditions, and discharges of E. coli and suspended sediment in this sample were -4.3 ? 108 cfu/s and -0.015 kg/s, respectively.

  12. Organic compounds and trace metals of anthropogenic origin in sediments from Montego Bay, Jamaica: assessment of sources and distribution pathways

    International Nuclear Information System (INIS)

    Sources and distribution pathways were identified. - Surface sediments throughout Montego Bay, Jamaica were collected in 1995 and analyzed for their trace metal and trace organic contaminant content. A variety of trace metals, petroleum hydrocarbons, polycyclic aromatic hydrocarbons, coprostanol as well as chlorinated hydrocarbons such as pesticides and polychlorinated biphenyls were detected and provide evidence for several anthropogenic inputs to the bay. Two main sources of these chemicals are the Montego River and the North Gully, the latter being more significant. Particle-associated pollutants were found to be distributed along the Montego River plume, as well as being transported by the prevailing water currents to the South-Western sections of the bay, probably through re-suspension of enriched fine sediments from the North Gully outfall area

  13. Utilizing short-lived radionuclides to study sediment dynamics in Pelekane Bay, Hawaii following the 2011 Tohoku Tsunami

    International Nuclear Information System (INIS)

    On 11 March 2011, a catastrophic M 9.0 earthquake occurred off the coast of Japan and triggered series of tsunami waves that quickly traversed the Pacific Ocean. The Hawaiian Islands were in the direct path of these tsunami waves and many of the exposed shorelines on these islands experienced significant impact from a series of persistent, oscillating waves. Approximately 7 hours after the initial earthquake, Pelekane Bay located on the northwest coast of Hawaii was struck by 2-m high tsunami waves. More than 24 hours later, tsunami waves on the order of 0.3 m continued to propagate into and withdraw from the shallow, coral reef-lined bay. As these waves ran up and drew down from the coastline, fine-grained seabed sediment was energetically remobilize into the bays water column. Down-core variations of excess 210Pb, 137Cs, and 7Be and their respective inventories were examined in a series of short sediment cores collected in Pelekane Bay serendipitously before and after the tsunami event, to assess tsunamigenic sediment dynamics in this system. Such a study provide insight on sediment redistribution following a tsunami in small water bodies. (author)

  14. Seasonality and variability of coccolithophore fluxes in response to diverse oceanographic regimes in the Bay of Bengal: Sediment trap results

    Digital Repository Service at National Institute of Oceanography (India)

    Mergulhao, L.P.; Guptha, M.V.S.; Unger, D.; Murty, V.S.N.

    A study on coccolithophores from the sediment trap samples, collected over a period of one year (January 1992–December 1992) from three trap locations in the Bay of Bengal (BOB) were used to understand their production and export processes...

  15. SEDIMENT AND PERIPHYTON ASSESSMENT AS INDICATORS OF ENVIRONMENTAL CONDITION IN THE FLORIDA BAY-EVERGLADES TRANSITIONAL ZONE

    Science.gov (United States)

    Florida Bay and its watershed are currently the focus of numerous investigations designed to assess the extent and cause of deterioration in environmental quality observed during recent years. Periphyton and sediment bioassessment were used in a multiyear study to compare the rel...

  16. SEDIMENT TOXICITY AND COMMUNITY COMPOSITION OF BENTHOS AND COLONIZED PERIPHYTON IN THE EVERGLADES - FLORIDA BAY TRANSITIONAL ZONE.

    Science.gov (United States)

    Lewis, Michael A., Larry R. Goodman, John M. Macauley and James C. Moore. 2004. Sediment Toxicity and Community Composition of Benthos and Colonized Periphyton in the Everglades-Florida Bay Transitional Zone. Ecotoxicology. 13(3):231-244. (ERL,GB 1164). This survey provid...

  17. Metal pollution in a contaminated bay: Relationship between metal geochemical fractionation in sediments and accumulation in a polychaete

    International Nuclear Information System (INIS)

    Jinzhou Bay in Northern China has been seriously contaminated with metals due to the impacts of smelting activities. In this study, we investigated the relationship between metal accumulation in a deposit-feeding polychaete Neanthes japonica and metal concentration and geochemical fractionation (Cd, Cu, Pb, Zn and Ni) in sediments of Jinzhou Bay. Compared with the historical data, metals in the more mobile geochemical fraction (exchangeable and carbonate fractions) were gradually partitioned into the more stable fraction (Fe–Mn oxides) over time. Metal concentration and geochemical fractionation in sediment significantly affected metal bioavailability and accumulation in polychaetes, except for Ni. Metal accumulation in polychaetes was significantly influenced by Fe or Mn content, and to a lesser degree by organic matter. Prediction of metal bioaccumulation in polychaetes was greatly improved by normalizing metal concentrations to Mn content in sediment. The geochemical fractionation of metals in sediments including the exchangeable, organic matter and Fe–Mn oxides were important in controlling the sediment metal bioavailability to polychaetes. - Highlights: • Metals in contaminated sediments gradually partitioned into the more stable phase over time. • Metal accumulation in polychaetes was more significantly influenced by Fe/Mn content than by organic matter. • Prediction of metal bioaccumulation greatly improved by normalizing metals to Mn content in sediment. • Metals in exchangeable, organic matter and Fe–Mn oxides were important in controlling their bioavailability. - Prediction of metal bioaccumulation in polychaetes was significantly improved by normalizing metal concentrations to Mn content in sediment

  18. Process-diagnostic patterns of chlorobiphenyl congeners in two radiochronologically characterized sediment cores from the northern Baffin Bay

    DEFF Research Database (Denmark)

    Gustafsson, O.; Axelman, J.; Broman, D.;

    2001-01-01

    sediments, corresponding to the past 170 years, in a single dated core from the Baffin Bay shelf. Fluxes of the dominant individual congeners in the surface sediments were 20-100 mug m(-2) d(-1). Combining these data with the sediment data from the Arctic Monitoring and Assessment Program, it appears that...... the PCB distribution in Arctic surface sediments is governed by the organic carbon (OC) content of the sediments. The historical development of the PCB congener fingerprint suggests that the modern sediments are enriched in medium-chlorinated congeners, implying that there are at least two significant......, consistent with a temperature-driven global fractionation process. The significant presence of PCB in historical archives pre-dating the organochlorine society, as observed in this and several previous studies, awaits a fuller explanation. (C) 2001 Elsevier Science Ltd. All rights reserved....

  19. Shoreline changes in Concón and Algarrobo bays, central Chile, using an adjustment model Cambios en la línea litoral de las bahías de Algarrobo y Concón, Chile central, a través de un modelo de ajuste

    OpenAIRE

    Carolina Martinez

    2007-01-01

    Adjustment models for both Algarrobo and Concón bays, central Chile, are presented herein; the results show a nearly logarithmic spiral shape for the shore. Spatial-temporal variations in the shorelines of both bays were found based on aerial photographs from different years. The results indicate important variations in the relative position of the Concón Bay shoreline between 1945 and 2006, with extreme oscillations (-368 to 123.8 m) only occurring in the proximal zone, where the Aconcagua E...

  20. Assessing past and present P Retention in Sediments in Lake Ontario (Bay of Quinte) by Reaction-Transport Diagenetic Modeling

    Science.gov (United States)

    Doan, Phuong; Berry, Sandra; Markovic, Stefan; Watson, Sue; Mugalingam, Shan; Dittrich, Maria

    2016-04-01

    Phosphorus (P) is an important macronutrient that can limit aquatic primary production and the risk of harmful algal blooms. Although there is considerable evidence that P release from sediments can represent a significant source of P and burial in sediments returns P to the geological sink; these processes have been poorly characterised. In this study, we applied a non-steady state reactive transport diagenetic model to gain insights into the dynamics of phosphorus binding forms in sediments and the phosphorus cycling of the Bay of Quinte, an embayment of Lake Ontario, Canada. The three basins of the bay (Belleville, Hay Bay and Napanee) that we investigated had differences in their phosphorus binding forms and phosphorus release, reflecting the distinct spatial temporal patterns of land use and urbanization levels in the watershed. Sediment cores from the three stations were collected during summer and under ice cover in 2013-14. Oxygen, pH and redox potential were monitored by microsensors; porewater and sediment solid matter were analyzed for P content, and a sequential extraction was used to analyze P binding forms. In the reaction-transport model, total phosphorus was divided into adsorbed phosphorus, phosphorus bound with aluminium, organic phosphorus, redox sensitive and apatite phosphorus. Using the fluxes of organic and inorganic matter as dynamic boundary conditions, we simulated the depth profiles of solute and solid components. The model closely reproduced the fractionation data of phosphorus binding forms and soluble reactive phosphorus. The past and present P fluxes were calculated and estimated; they related to geochemical conditions, and P binding forms in sediments. Our results show that P release from sediments is dominated by the redox-sentive P fraction accounting for higher percentage at Napanee station. The main P binding form that can be immobilized through diagenesis is apatite P contributing highest P retention at HayBay station. The mass

  1. Understanding processes controlling sediment transports at the mouth of a highly energetic inlet system (San Francisco Bay, CA)

    Science.gov (United States)

    Elias, Edwin P.L.; Hansen, Jeff E.

    2013-01-01

    San Francisco Bay is one of the largest estuaries along the U.S. West Coast and is linked to the Pacific Ocean through the Golden Gate, a 100 m deep bedrock inlet. A coupled wave, flow and sediment transport model is used to quantify the sediment linkages between San Francisco Bay, the Golden Gate, and the adjacent open coast. Flow and sediment transport processes are investigated using an ensemble average of 24 climatologically derived wave cases and a 24.8 h representative tidal cycle. The model simulations show that within the inlet, flow and sediment transport is tidally dominated and driven by asymmetry of the ebb and flood tides. Peak ebb velocities exceed the peak flood velocities in the narrow Golden Gate channel as a result of flow convergence and acceleration. Persistent flow and sediment gyres at the headland tips are formed that limit sediment transfer from the ebb-tidal delta to the inlet and into the bay. The residual transport pattern in the inlet is dominated by a lateral segregation with a large ebb-dominant sediment transport (and flow) prevailing along the deeper north side of the Golden Gate channel, and smaller flood dominant transports along the shallow southern margin. The seaward edge of the ebb-tidal delta largely corresponds to the seaward extent of strong tidal flows. On the ebb-tidal delta, both waves and tidal forcing govern flow and sediment transport. Wave focusing by the ebb-tidal delta leads to strong patterns of sediment convergence and divergence along the adjacent Ocean Beach.

  2. Sediment dynamic responses of coastal salt marsh to typhoon "KAEMI" in Quanzhou Bay, Fujian Province, China

    Institute of Scientific and Technical Information of China (English)

    WANG AiJun; GAO Shu; GHEN Jian; LI DongYi

    2009-01-01

    In order to understand the mechanisms of coastal protection by salt marshes during typhoon events, in situ measurements of water level, tidal current speed and direction, and suspended sediment concen-tration (SSC) were carried out using Electromagnetic Current Meter (EMCM, AEM HR), miniature pres-sure sensor (MkV/D) and Seapoint Turbidity Meter (STM) sensor on a tidal flat in Quanzhou Bay, during the period when the typhoon "KAEMI" was passing through the region. The analysis of the data ob-tained shows that the near-bed current speed within the Spartina alterniflora marsh was generally be-low 5 cm s-1, which was apparently smaller than on the adjacent bare flat (I.e. 5-30 cm s-1). The change in the near-bed current speed in response to the typhoon event was not significant within the S. Al-terniflora marsh, but the current direction was influenced by the typhoon. The effect of the typhoon on the SSC was highly significant, with the SSC reaching 13 to 19 times the values on the bare flat or within the marsh under fair weather conditions; the near-bed SSC within the marsh was higher than on the bare flat, after the typhoon landed. The near-bed suspended sediment fluxes within the marsh and on the bare flat during the typhoon event were both enhanced, I.e., 4 times larger than under fair weather conditions. During the ebb, the bottom shear stress on the bare flat exceeded the critical shear stress for sediment motion for most of the ebb duration of the tide and, therefore, the bed sediment was eroding, with the erosion flux after the typhoon landed being around 2 to 3 times the value associated with fair weather conditions. In contrast, within the S. Alterniflora marsh, the bottom shear stress was mostly lower than the critical shear stress for sediment motion, or lower than the critical shear stress for the maintenance of suspension; hence, the marsh surface was dominated by settling processes, with a settling flux during the typhoon being 3 to 6 times compared

  3. Radium isotopes in Port Phillip Bay: estimation of the rate of bio irrigation of sediments, and water residence time

    International Nuclear Information System (INIS)

    Recent work has shown that estuarine sediments are a source of radium (Ra) to coastal waters (Bollinger and Moore, 1982, Webster et al., 1994; Hancock et al., 1997). Ra is soluble in saline water (Moore, 1992, Webster et al., 1995) and is rapidly desorbed into porewater from deposited fluvial sediments where it is continuously generated by insoluble Th parents. The rate at which Ra effuses into surface water has been used to determine the rate of surface-water pore water exchange (Hancock and Murray, 1996). Once in the water column, the behaviour of Ra is essentially conservative, enabling the determination of water residence time in a semi-enclosed estuary (Turekian et al., 1996). Here we use measurements of Ra in an estuary to estimate two water mixing processes. Port Phillip Bay (PPB) is a semi-enclosed estuary adjacent to the city of Melbourne, one of the highest density population centres in Australia. The Bay is approximately 50 km in diameter, and has an average depth of 14 m. A recent study found that the potential for eutrophication and algal blooms in the Bay was intricately linked to the fate of nutrients, particularly nitrogen, discharged into the Bay from rivers, drains, and sewage treatment plants (Harris et al. 1996). Two of the most important processes controlling the levels of inorganic N in the water column were identified as bio irrigation of bottom sediments, and the rate of exchange of Bay water with ocean water via Bass Strait. In this paper we describe how Ra isotopes can be used to estimate the rates of these processes, and we compare these rates with estimates made using conventional techniques. Water and sediment samples were collected from five sites in February 1996. Sediment cores were collected by divers, frozen, and sectioned in the laboratory. Surface, mid depth and bottom water samples were collected using a Niskin bottle. Radionuclide activities were determined by alpha spectrometry (Martin and Hancock, 1992) and gamma spectrometry

  4. Speciation of Metals and Assessment of Contamination in Surface Sediments from Daya Bay, South China Sea

    Directory of Open Access Journals (Sweden)

    Jie Yang

    2014-12-01

    Full Text Available The contents, speciation, source factors and potential ecological risks of the selected metals (Cr, Ni, Cu, Pb, Zn, Cd and As were analyzed in surface sediments from Daya Bay (DYB. The results show that, with the exception of Pb, metal concentrations have decreased at all sites over the past decade. The distribution features of these concentrations represent a ring shape that descends from shore to bay by varying degrees. Speciation analysis showed that Cr, Ni, Cu, Zn and As exist mainly in the residual fraction and, thus, are of low bioavailability, while Cd and Pb were found to be abundant in the non-residual fraction and, thus, have high potential mobility. The ratio of heavy metals in non-residual form in descending order is Pb (78.83%, Cd (78.65%, Cu (48.54%, Zn (48.10%, Ni (38.31%, Cr (28.43% and As (27.76%. The ratio of Pb content is the highest, meaning the highest mobility of Pb. The metals’ potential ecological risks to the environment were also assessed using the methods of the mean effect range-median quotient and the criteria of risk assessment code. The results showed that Cd presents the highest risk, and Pb and Cu are generally considered to be medium risks in the sub-basins of Daya Bay. The principal component analysis (PCA revealed that natural coastal weathering and erosion of rock caused the highest input, followed by mariculture and industrial wastewater and, finally, domestic sewage discharge.

  5. Bottom sediments and pore waters near a hydrothermal vent in Lake Baikal (Frolikha Bay)

    Science.gov (United States)

    Granina, L.Z.; Klerkx, J.; Callender, E.; Leermakers, M.; Golobokova, L.P.

    2007-01-01

    We discuss the redox environments and the compositions of bottom sediments and sedimentary pore waters in the region of a hydrothermal vent in Frolikha Bay, Lake Baikal. According to our results, the submarine vent and its companion nearby spring on land originate from a common source. The most convincing evidence for their relation comes from the proximity of stable oxygen and hydrogen isotope compositions in pore waters and in the spring water. The isotope composition indicates a meteoric origin of pore waters, but their major- and minor-element chemistry bears imprint of deep water which may seep through permeable faulted crust. Although pore waters near the submarine vent have a specific enrichment in major and minor constituents, hydrothermal discharge at the Baikal bottom causes a minor impact on the lake water chemistry, unlike the case of freshwater geothermal lakes in the East-African Rift and North America. ?? 2007.

  6. Fatty acids and Pb-210 geochronology of a sediment core from Buzzards Bay, Massachusetts

    International Nuclear Information System (INIS)

    Four sections of a Pb-210 dated core of 62 cm length from Buzzards Bay, Massachusetts, were analyzed for fatty acids. A comparison of fatty acids extracted by Soxhlet extraction (unbound fatty acids) with fatty acids extracted by subsequent saponification extraction of the same sample (bound fatty acids) showed that the former did not undergo diagenetic loss any faster than the latter. However, compositional differences between bound and unbound fatty acids were apparent in the top section of 1 to 2 cm and were less apparent in the 54 to 58 cm section. At least 14% of the bound fatty acids are esterified to non-solvent extractable material. The net conversion of fatty acids to other compounds is 32 μg/g dry weight sediment over the first 30 yr after deposition. (author)

  7. 10Be dating of marine core sediment from Central Western Bay of Bengal by using accelerator mass spectrometry

    International Nuclear Information System (INIS)

    A 4.12 m long marine sediment gravity core was collected during 157 cruise of ORV Sagar Kanya (October 2000) from the marginal coastal waters of central western Bay of Bengal. Sediment samples were taken for every 50cm interval; i.e 7 samples are studied for dating purpose. Rate of sedimentation and age of the core was determined with the cosmogenic radionuclide 10Be by using Accelerator Mass Spectrometry (AMS). 9Be was determined using ICPMS. The data is in good agreement with literature values. (author)

  8. Analysis and dating of Sediments in Montevideo Bay and Silver river

    International Nuclear Information System (INIS)

    The present work includes generalities on the River of the Silver, antecedents of studies carried out during the years 1992-1997, in the issuing sub aquatic of Tip Carts, studies about the contamination of silts carried out during the years 1993-1996, studies preliminary of the contamination of silts in the Bay,results obtain,treatment of the data and enrichment factors. In the description of the project it is looked for to obtain reliable data on the state of contamination for heavy metals sedimentation ,velocity and age of the silts of the Bay of Montevideo and the River of the Silver, describe geologic aspects in the area involved in the study, the sampling of silts is planned having present the purpose of the same one that is to say to take samples that represent the characteristics real of silts in the sampling area, X Ray Fluorescence dispersive Energy are used in the analysis of samples, for finish, results and discussion are presented

  9. Monitoring of sedimentation using bathymetric changes and 210Pb profiling in Laguna de Bay, Philippines

    International Nuclear Information System (INIS)

    Laguna de Bay is the largest inland body of water in the Philippines. It is a multi-use resource but at present, the dominant use is for fishery. At present there is a very high demand for domestic water in the Metropolitan Manila Area and the lake is considered as the most viable source. Among the concerns raised are the eutrophic condition of the lake, the alarming siltation due to the denudation of the forest areas within the watershed, deterioration of the water quality due to rapid development in built-up areas and the booming industrialization in the lake's West Bay area. The dredging of the lake has long been requested by the different stake holders to improve its water quality and to achieve the volume necessary to meet the lake's various uses. In line with the thrust of the Laguna Lake Development Authority to formulate policies on the development of the lake region and the sustainable use of the lake's resources based on concrete and reliable data, a collaborative work with the National Institute of Geological Sciences at the University of the Philippines, Diliman Campus, commenced in 1997. Among the objectives is to generate an updated bathymetric map of the lake and establish the changes in the configuration of the lake during the past few tens of years and to estimate the rates of sedimentation using time series analysis of bathymetric maps and radiometric dating using 210Pb

  10. Carbon sources supporting benthic mineralization in mangrove and adjacent seagrass sediments (Gazi Bay, Kenya

    Directory of Open Access Journals (Sweden)

    F. Dehairs

    2004-08-01

    Full Text Available The origin of carbon substrates used by in situ sedimentary bacterial communities was investigated in an intertidal mangrove ecosystem and in adjacent seagrass beds in Gazi bay (Kenya by δ13C analysis of bacteria-specific PLFA (phospholipid fatty acids and bulk organic carbon. Export of mangrove-derived organic matter to the adjacent seagrass-covered bay was evident from sedimentary total organic carbon (TOC and δ13CTOC data. PLFA δ13C data indicate that the substrate used by bacterial communities varied strongly and that exported mangrove carbon was a significant source for bacteria in the adjacent seagrass beds. Within the intertidal mangrove forest, bacterial PLFA at the surface layer (0-1 cm typically showed more enriched δ13C values than deeper (up to 10 cm sediment layers, suggesting a contribution from microphytobenthos and/or inwelled seagrass material. Under the assumption that seagrasses and mangroves are the dominant potential end-members, the estimated contribution of mangrove-derived carbon to benthic mineralization in the seagrass beds (16-74% corresponds fairly well to the estimated contribution of mangrove C to the sedimentary organic matter pool (21-71% across different seagrass sites. Based on these results and a compilation of literature data, we suggest that allochtonous carbon trapped in seagrass beds may often represent a significant fraction of the substrate for benthic mineralization - both in cases where seagrass C dominates the sediment TOC pool and in cases where external inputs are significant. Hence, it is likely that community respiration data systematically overestimate the role of mineralization in the overall seagrass C budget.

  11. Reconstruction of metal pollution and recent sedimentation processes in Havana Bay (Cuba): A tool for coastal ecosystem management

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Asencio, M., E-mail: misael@ceac.cu [Centro de Estudios Ambientales de Cienfuegos, Carretera Castillo de Jagua, Cienfuegos, CITMA-Cienfuegos (Cuba); Alvarado, J.A. Corcho [Institute of Radiation Physics (IRA), University Hospital and University of Lausanne, Rue du Grand-Pre 1, 1007 Lausanne (Switzerland); Alonso-Hernandez, C. [Centro de Estudios Ambientales de Cienfuegos, Carretera Castillo de Jagua, Cienfuegos, CITMA-Cienfuegos (Cuba); Quejido-Cabezas, A. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain); Ruiz-Fernandez, A.C. [Universidad Nacional Autonoma de Mexico. ICMyL, Mazatlan (Mexico); Sanchez-Sanchez, M.; Gomez-Mancebo, M.B. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain); Froidevaux, P. [Institute of Radiation Physics (IRA), University Hospital and University of Lausanne, Rue du Grand-Pre 1, 1007 Lausanne (Switzerland); Sanchez-Cabeza, J.A. [Institute of Environmental Science and Technology, and Physics Department, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain)

    2011-11-30

    Highlights: Black-Right-Pointing-Pointer Past metal pollution in the heavy polluted coastal ecosystem of Havana Bay. Black-Right-Pointing-Pointer Effectiveness of pollution-reduction strategies. Black-Right-Pointing-Pointer Dated environmental archives to reconstruct sedimentation and pollution trends. Black-Right-Pointing-Pointer Impact of severe climatic events on sedimentation. - Abstract: Since 1998 the highly polluted Havana Bay ecosystem has been the subject of a mitigation program. In order to determine whether pollution-reduction strategies were effective, we have evaluated the historical trends of pollution recorded in sediments of the Bay. A sediment core was dated radiometrically using natural and artificial fallout radionuclides. An irregularity in the {sup 210}Pb record was caused by an episode of accelerated sedimentation. This episode was dated to occur in 1982, a year coincident with the heaviest rains reported in Havana over the XX century. Peaks of mass accumulation rates (MAR) were associated with hurricanes and intensive rains. In the past 60 years, these maxima are related to strong El Nino periods, which are known to increase rainfall in the north Caribbean region. We observed a steady increase of pollution (mainly Pb, Zn, Sn, and Hg) since the beginning of the century to the mid 90s, with enrichment factors as high as 6. MAR and pollution decreased rapidly after the mid 90s, although some trace metal levels remain high. This reduction was due to the integrated coastal zone management program introduced in the late 90s, which dismissed catchment erosion and pollution.

  12. Reconstruction of metal pollution and recent sedimentation processes in Havana Bay (Cuba): A tool for coastal ecosystem management

    International Nuclear Information System (INIS)

    Highlights: ► Past metal pollution in the heavy polluted coastal ecosystem of Havana Bay. ► Effectiveness of pollution-reduction strategies. ► Dated environmental archives to reconstruct sedimentation and pollution trends. ► Impact of severe climatic events on sedimentation. - Abstract: Since 1998 the highly polluted Havana Bay ecosystem has been the subject of a mitigation program. In order to determine whether pollution-reduction strategies were effective, we have evaluated the historical trends of pollution recorded in sediments of the Bay. A sediment core was dated radiometrically using natural and artificial fallout radionuclides. An irregularity in the 210Pb record was caused by an episode of accelerated sedimentation. This episode was dated to occur in 1982, a year coincident with the heaviest rains reported in Havana over the XX century. Peaks of mass accumulation rates (MAR) were associated with hurricanes and intensive rains. In the past 60 years, these maxima are related to strong El Niño periods, which are known to increase rainfall in the north Caribbean region. We observed a steady increase of pollution (mainly Pb, Zn, Sn, and Hg) since the beginning of the century to the mid 90s, with enrichment factors as high as 6. MAR and pollution decreased rapidly after the mid 90s, although some trace metal levels remain high. This reduction was due to the integrated coastal zone management program introduced in the late 90s, which dismissed catchment erosion and pollution.

  13. Ecological risk, source and preliminary assessment of metals in the surface sediments of Chabahar Bay, Oman Sea.

    Science.gov (United States)

    Agah, Homira; Saleh, Abolfazl; Bastami, Kazem Darvish; Fumani, Neda Sheijooni

    2016-06-15

    In this study, concentrations of Aluminum (Al), Iron (Fe), Chromium (Cr), Copper (Cu), Nickel (Ni), Vanadium (V), Zinc (Zn), Arsenic (As), Cobalt (Co) and lead (Pb) in the surface sediments from Chabahar Bay were studied to assess the degree of heavy metal pollution as a consequence of natural and anthropogenic sources. Metal contents in the sediments were observed in the order of: Al>Fe>Cr>V>Ni>Zn>Cu>As>Pb>Co. According to enrichment factor (EF), Arsenic was higher than 1.5 at some sites, indicating anthropogenic inputs. Contents of Ni, As and Cr in the some sampling sites were higher than sediment quality guideline implying adverse impacts of these metals. Based on potential ecological risk (PER), the Chabahar Bay had low ecological risk. PMID:27038881

  14. Comparison of wastewater-associated contaminants in the bed sediment of Hempstead Bay, New York, before and after Hurricane Sandy

    Science.gov (United States)

    Fisher, Shawn C.; Phillips, Patrick; Brownawell, Bruce J.; Browne, James

    2016-01-01

    Changes in bed sediment chemistry of Hempstead Bay (HB) have been evaluated in the wake of Hurricane Sandy, which resulted in the release of billions of liters of poorly-treated sewage into tributaries and channels throughout the bay. Surficial grab samples (top 5 cm) collected before and (or) after Hurricane Sandy from sixteen sites in HB were analyzed for 74 wastewater tracers and steroid hormones, and total organic carbon. Data from pre- and post-storm comparisons of the most frequently detected wastewater tracers and ratios of steroid hormone and of polycyclic aromatic hydrocarbon concentrations indicate an increased sewage signal near outfalls and downstream of where raw sewage was discharged. Median concentration of wastewater tracers decreased after the storm at sites further from outfalls. Overall, changes in sediment quality probably resulted from a combination of additional sewage inputs, sediment redistribution, and stormwater runoff in the days to weeks following Hurricane Sandy.

  15. Comparison of wastewater-associated contaminants in the bed sediment of Hempstead Bay, New York, before and after Hurricane Sandy.

    Science.gov (United States)

    Fisher, Shawn C; Phillips, Patrick J; Brownawell, Bruce J; Browne, James P

    2016-06-30

    Changes in bed sediment chemistry of Hempstead Bay (HB) have been evaluated in the wake of Hurricane Sandy, which resulted in the release of billions of liters of poorly-treated sewage into tributaries and channels throughout the bay. Surficial grab samples (top 5cm) collected before and (or) after Hurricane Sandy from sixteen sites in HB were analyzed for 74 wastewater tracers and steroid hormones, and total organic carbon. Data from pre- and post-storm comparisons of the most frequently detected wastewater tracers and ratios of steroid hormone and of polycyclic aromatic hydrocarbon concentrations indicate an increased sewage signal near outfalls and downstream of where raw sewage was discharged. Median concentration of wastewater tracers decreased after the storm at sites further from outfalls. Overall, changes in sediment quality probably resulted from a combination of additional sewage inputs, sediment redistribution, and stormwater runoff in the days to weeks following Hurricane Sandy. PMID:27045048

  16. Extraction procedure compared to attenuation model to assess heavy metals mobility in sediments from Sepetiba Bay, Rio de Janeiro

    International Nuclear Information System (INIS)

    Sepetiba bay, located about 60 km west of the metropolitan region of Rio de Janeiro city, has undergone notable development in the last decades, with the establishment of about 400 industrial plants in its basin, basically metallurgical, which release its industrial waste either straight into the bay or through local rivers. The Sepetiba harbor also brought up a lot of industrial investment in that area. This urban and industrial expansion caused several environmental impacts, mainly due to the presence of heavy metals and other potentially toxic substances present in the effluents discharged into the bay. This work aimed to assess heavy metal (Cd, Cu, Ni, Pb e Zn) contamination and mobility in sediments from Sepetiba bay. The acid-volatile sulfides (AVS) and the concentration of simultaneously extracted metals (SIGMA[SEM) were determined in 65 sediment samples from Sepetiba bay, representing the whole area. The results obtained showed that Cd, Cu, Pb and Zn presented higher concentrations in the northeastern area (mainly in the mouth of Guandu and Canal de Sao Francisco rivers), while the highest concentration of Ni were observed in the western region of the bay. The comparison between SEM concentrations with the Canadian Sediment Quality Guidelines (TEL and PEL) indicated that Cd and Zn presented values which may hazard to aquatic organisms (concentration levels above PEL); the elements Cu, Pb and Ni presented concentration levels below PEL, suggesting low probability of toxicological effects to the aquatic organisms. On the other hand, the ratio Σ[SEM]/[AVS] was below 1 in the northeastern region, indicating that, in spite of the high concentration of the analyzed metals in this area, they are trapped in the sediment, as sulfides. The total metal concentrations in the sediments were also determined and the same distribution pattern obtained for the SEM were observed, with high concentrations in the northeastern region of the bay, classifying the area as level 2

  17. Seasonal and geographical variability in some trace elements of Pacific oysters (Crassostrea Gigas) cultured in two different bays of Northern Chile

    International Nuclear Information System (INIS)

    Chile has approximately 4,500 kilometers of continental coastline on the Pacific Ocean. It is therefore in a favorable position to develop fishing activities, since its waters contain a great variety of marine resources, namely, fish, shellfish and seaweeds. Fishing in Chile plays an important role in production. Metal contamination of the marine ecosystem is a pervasive and worldwide problem. Consequently, seafood consuming and exporting countries have gradually increased the need to improve the quality of their products in order to meet the required standards. In turn, this implies the need to adopt more efficient methods to analyze these resources by carrying out studies that will provide greater integral knowledge on the levels of essential and toxic trace elements found in seafood. In the present study, seasonal and geographical variability of some trace elements content of Pacific Oysters (Crassostrea Gigas) cultured, greatly demanded on the international market, are investigated. Samples for the analysis were collected from two different bays of Northern Chile, where heavy-metal pollution is already recognized as a problem. The trace elements content of this mollusk was studied at monthly intervals for 12 months (September 1987-August 1988). The determination of Cu was carried out using radiochemical neutron activation analysis and the other trace elements like Cd, As, Br, Na, Se, Cr, Fe, Zn and Co, were determined through neutron activation analysis in its purely instrumental form. NBS Standard Reference Materials were used to determine the accuracy of both methods. Significant differences were found comparing the content of copper and cadmium at the different seasons and locations of capture

  18. Impact of a river system on carbon sedimentation and sequestration in Cook's Bay of Lake Simcoe, Ontario

    Science.gov (United States)

    Blodau, Christian; Agethen, Svenja; Spangenberg, Ines; Broder, Tanja; Gimbel, Nicole; Strauss, Harald; Knorr, Klaus-Holger

    2016-04-01

    The influence of sedimentation rates and organic matter quality on carbon sequestration and mineralization at the land-water interface of lakes is not well understood. To study this issue we investigated shallow Cook's Bay of temperate Lake Simcoe in southern Ontario. The elongated bay provides gradients in morphometry, trophic level, and distance to a major tributary as a potential point source of nutrients and terrestrial organic carbon. At five sampling sites of increasing distance to the river outlet the water column was examined during stratification regarding physio-chemical parameters, dissolved organic matter (DOM) characteristics, sedimentation rates and mineralization of settling material and sediments. To quantify actual organic carbon burial, sedimentation rates and mineralization were determined in situ and by diffusive flux modeling. Long-term carbon burial and sedimentation rates were determined using 210Pb dated sediment cores. Organic carbon quality and origin were analyzed in water samples via fluorescence spectroscopy, solid DOM and settling particles via elemental analysis and 13C isotopic data. Results showed that actual and long-term carbon burial were highest at the central sites of the transect (52-63%) and lowest at the profundal sites (0-25%). Current organic carbon deposition was highest near the river outlet (max. 0.3 g C m-2 d-1) and there the settling material reaching the sediments and in the sediments was also most highly decomposable. Total sedimentation rates and organic carbon burial were closely related. Compared to the outer sites, the DOM quality was significantly different at the site closest to the river outlet but already strongly influenced by lacustrine carbon cycling. Permanent organic carbon burial was mainly influenced by sedimentation related to lake morphometry and dependent parameters. The relation between sedimentation and carbon burial rates underlined the importance of oxygen exposure time and burial for

  19. Sedimentary environment inferred from sedimentation rates by 210Pb and 137Cs and their inventories in Mutsu Bay, Japan

    International Nuclear Information System (INIS)

    Fourteen sediment cores were collected from Mutsu Bay, Aomori in Japan, and excess 210Pb and 137Cs were measured γ-spectrometrically. The spatial distributions of sedimentation rates by 210Pbex and 137Cs and their inventories were studied in order to clarify whole pictures about the sedimentary environment of Mutsu Bay. Excessively post-depositional mixing (up to a depth of 10-15 cm) of surface sediments by bioturbation was observed on the 210Pbex depth profiles in cores from the offshore areas. The sedimentation rates calculated varied in the wide range from 0.04 to 0.2 g/cm2/y. The sedimentation rates using 137Cs method could not be applied. Apart from the 210Pbex inventories from the nearshore area, the responding inventories (17-30 kBq/m2) from the offshore area were higher than the reported value of ca.15 kBq/m2 in the surrounding soils, indicating that the sediment focusing due to the inner current etc., to the deeper area from the surrounding nearshore area, affects the sediment accumulation in the offshore area. (author)

  20. Enrichment of arsenic transforming and resistant heterotrophic bacteria from sediments of two salt lakes in Northern Chile.

    Science.gov (United States)

    Lara, José; Escudero González, Lorena; Ferrero, Marcela; Chong Díaz, Guillermo; Pedrós-Alió, Carlos; Demergasso, Cecilia

    2012-05-01

    Microbial populations are involved in the arsenic biogeochemical cycle in catalyzing arsenic transformations and playing indirect roles. To investigate which ecotypes among the diverse microbial communities could have a role in cycling arsenic in salt lakes in Northern Chile and to obtain clues to facilitate their isolation in pure culture, sediment samples from Salar de Ascotán and Salar de Atacama were cultured in diluted LB medium amended with NaCl and arsenic, at different incubation conditions. The samples and the cultures were analyzed by nucleic acid extraction, fingerprinting analysis, and sequencing. Microbial reduction of As was evidenced in all the enrichments carried out in anaerobiosis. The results revealed that the incubation factors were more important for determining the microbial community structure than arsenic species and concentrations. The predominant microorganisms in enrichments from both sediments belonged to the Firmicutes and Proteobacteria phyla, but most of the bacterial ecotypes were confined to only one system. The occurrence of an active arsenic biogeochemical cycle was suggested in the system with the highest arsenic content that included populations compatible with microorganisms able to transform arsenic for energy conservation, accumulate arsenic, produce H(2), H(2)S and acetic acid (potential sources of electrons for arsenic reduction) and tolerate high arsenic levels. PMID:22555750

  1. Composition and depth distribution of hydrocarbons in Barataria Bay marsh sediments after the Deepwater Horizon oil spill.

    Science.gov (United States)

    Dincer Kırman, Zeynep; Sericano, José L; Wade, Terry L; Bianchi, Thomas S; Marcantonio, Franco; Kolker, Alexander S

    2016-07-01

    In 2010, an estimate 4.1 million barrels of oil were accidentally released into the Gulf of Mexico (GoM) during the Deepwater Horizon (DWH) Oil Spill. One and a half years after this incident, a set of subtidal and intertidal marsh sediment cores were collected from five stations in Barataria Bay, Louisiana, USA, and analyzed to determine the spatial and vertical distributions and source of hydrocarbon residues based on their chemical composition. An archived core, collected before the DWH oil spill from the same area, was also analyzed to assess the pre-spill hydrocarbon distribution in the area. Analyses of aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and stable carbon isotope showed that the distribution of petroleum hydrocarbons in Barataria Bay was patchy and limited in areal extent. Significant TPH and ΣPAH concentrations (77,399 μg/g and 219,065 ng/g, respectively) were detected in the surface sediments of one core (i.e., core A) to a depth of 9 cm. Based on a sedimentation rate of 0.39 cm yr(-1), determined using (137)Cs, the presence of anthropogenic hydrocarbons in these sediment core deposited ca. 50 to 60 years ago. The historical background hydrocarbon concentrations increased significantly at the sediment surface and can be attributed to recent inputs. Although the oil present in the bay's sediments has undergone moderate weathering, biomarker analyses performed on core A samples likely indicated the presence of hydrocarbons from the DWH oil spill. The effects of oiling events on Barataria Bay and other marsh ecosystems in this region remain uncertain, as oil undergoes weathering changes over time. PMID:27064616

  2. [Metagenomic Analysis of Microbial Communities of the Sediments of the Kara Sea Shelf and the Yenisei Bay].

    Science.gov (United States)

    Mamaeva, E V; Galach'yants, Yu P; Khabudaev, K V; Petrova, D P; Pogodaeva, T V; Khodzher, T B; Zemskaya, T I

    2016-01-01

    Microbial diversity in the sediments of the Kara Sea shelf and the southern Yenisei Bay, differing in pore water mineralization, was studied using massive parallel pyrosequencing according to the 454 (Roche) technology. Members of the same phyla (Cyanobacteria, Verrucomicrobia, Actinobacteria, Proteobacteria, and Bacteroidetes) predominated in bacterial communities of the sediments, while their ratio and taxonomic composition varied within the phyla and depended on pore water mineralization. Increasing salinity gradient was found to coincide with increased share of the γ-Proteobacteria and decreased abundance of α- and β-Proteo- bacteria, as well as of the phyla Verrucomicrobia, Chloroflexi, Chlorobi, and Acidobacteria. Archaeal diversity was lower, with Thaumarchaeota predominant in the sediments with high and low mineralization, while Crenarchaeota predominated in moderately mineralized sediments. Microbial communities of the Kara Sea shelf and Yenisei Gulf sediments were found to contain the organisms capable of utilization of a broad spectrum of carbon sources, including gaseous and petroleum hydrocarbons. PMID:27476207

  3. Brominated diphenyl ethers in the sediments, porewater, and biota of the Chesapeake Bay, USA

    Energy Technology Data Exchange (ETDEWEB)

    Baker, K.; Klosterhaus, S.; Liebert, D.; Stapleton, H. [Maryland Univ., Solomons, MD (United States)

    2004-09-15

    Levels of brominated diphenyl ethers (BDEs) are rapidly increasing in the environment, and in a short time these chemicals have evolved from 'emerging contaminants' to globally-distributed organic pollutants. Recent research demonstrates BDEs are sufficiently stable to be transported long distances in the environment and to accumulate in higher trophic levels. Photolysis and metabolism appear to be dominant loss processes for the parent compounds, generating a variety of lower brominated diphenyl ethers, hydroxylated metabolites, and other products. BDEs are hydrophobic, and therefore their transport in aquatic systems is likely controlled by sorption to sediments and perhaps exchange across the air-water interface. To date, few studies have examined the geochemistry of BDEs in natural waters. In this paper, we review our recent measurements of BDEs in the Chesapeake Bay, a shallow, productive estuary in eastern North America. We focus on the distribution of BDE congeners sediment, porewater, and in faunal benthos along a contamination gradient downstream from a wastewater treatment plant and on the spatial distribution of BDEs in bottom-feeding and pelagic fish species.

  4. Two-Dimensional Mathematical Model of Tidal Current and Sediment for Oujiang Estnary and Wenzhou Bay

    Institute of Scientific and Technical Information of China (English)

    陆永军; 李浩麟; 董壮; 陆建宇; 郝嘉凌

    2002-01-01

    A 2-D mathematical model of tidal current and sediment has been developed for the Oujiang Estuary and the WenzhouBay. This model accomodates complicated features including multiple islands, existence of turbidity, and significant differ-ence in size distribution of bed material. The governing equations for non-uniform suspended load and bed load transport arepresented in a boundary-fitted orthogonal curvilinear coordinate system. The numerical solution procedures along with theirinitial conditions, boundary conditions, and movable boundary technique are presented. Strategies for computation of thecritical condition of deposition or erosion, sediment transport capacity, non-uniform bed load discharge, etc. are suggested.The model verification computation shows that, the tidal levels computed from the model are in good agreement with the fielddata at the 18 tidal gauge stations. The computed velocities and flow directions also agree well with the values measuredalong the totally 52 synchronously observed verticals distributed over 8 cross sections. The computed tidal water throughputsthrough the Huangda'ao cross section are close to the measured data. And the computed values of bed deformation fromYangfushan to the estuary outfall and in the outer-sea area are in good agreement with the data observed from 1986 to 1992.The changes of tidal volumes through the estuary, velocities in different channels and the bed form due to the influence of thereclamation project on the Wenzhou shoal are predicted by means of this model.

  5. Seagrass vegetation and meiofauna enhance the bacterial abundance in the Baltic Sea sediments (Puck Bay).

    Science.gov (United States)

    Jankowska, Emilia; Jankowska, Katarzyna; Włodarska-Kowalczuk, Maria

    2015-09-01

    This study presents the first report on bacterial communities in the sediments of eelgrass (Zostera marina) meadows in the shallow southern Baltic Sea (Puck Bay). Total bacterial cell numbers (TBNs) and bacteria biomass (BBM) assessed with the use of epifluorescence microscope and Norland's formula were compared between bare and vegetated sediments at two localities and in two sampling summer months. Significantly higher TBNs and BBM (PERMANOVA tests, P macrofauna densities, as well as macrophyte vegetation characteristics (shoot density, phytobenthos biomass) were tested using PERMANOVA distance-based linear model (DISTLM) procedures and showed that the main factors explaining bacteria characteristics are bottom type (vegetated vs. unvegetated) and meiofauna density. These two factors explained together 48.3% of variability in TBN and 40.5% in BBM, and their impacts did not overlap (as indicated by DISTLM sequential tests) demonstrating the different natures of these relationships. The effects of seagrass were most probably related to the increase of organic matter and providing habitat while higher numbers of meiofauna organisms may have stimulated the bacterial growth by increased grazing. PMID:26178839

  6. Fluvio-lacustrine sedimentation and volcanism in a Late Carboniferous tensional intra-arc basin, northern Chile

    Science.gov (United States)

    Breitkreuz, Christoph

    1991-11-01

    Extensive outcrops of Late Carboniferous to Triassic volcanoplutonic magnetic-arc complexes occur in the Andes of northern Chile. In the Salar de Atacama area, terrestrial volcanosedimentary successions include a 200-600 m thick fluvio-lacustrine sequence ("Miembro Medio"). The terrestrial basin which accommodated this sequence formed during the latest Carboniferous on top of the deposits of the pre-existing Carboniferous composite volcanoes. The lower part of the Miembro Medio consists of green limnic and multicoloured alluvial fan deposits; the upper part is made up of red fluvial sedimentary rocks. Basic volcanic rocks occur locally throughout the sequence. The climate is inferred to have been warm and humid. The limnic (freshwater) environment had a minimum extension of 300 × 100 km. Limnic facies is inferred from the existence of fine-parallel-bedded sediments, ooliths and a limnic benthic fauna. Lake-shore deposits prevail in the outcrops. In some sections, the green limnic sequence is followed by red fine-grained floodplain or alluvial plain, and fluvial channel deposits. The framework composition of the Miembro Medio is dominated by volcanogenic detritus presumably eroded from the successions of the previous Late Carboniferous volcanic arc. Another volcanogenic clast type was provided by syndepositional basalto-andesitic phreatomagmatic activity, which also produced peperitic sills, dykes and lavas. The limnic-alluvial fan facies association, the predominance of volcanogenic detritus, and the accompanying intrabasinal basic calc-alkaline volcanism together with the considerable size of the basin point to a ?NW-SE trending half-graben setting controlled by (trans-)tensional arc tectonics. With regard to the Late Carboniferous-Triassic volcanosedimentary successions of northern Chile, this Latest Carboniferous tensional setting is the only feature in this area supporting those models, which inferred an extensional magmatic arc for the entire Central and

  7. Modern sedimentation processes in a wave-dominated coastal embayment: Espírito Santo Bay, southeast Brazil

    Science.gov (United States)

    Bastos, Alex Cardoso; Costa Moscon, Daphnne Moraes; Carmo, Dannilo; Neto, José Antonio Baptista; da Silva Quaresma, Valéria

    2015-02-01

    Sediment dynamics in wave-dominated coastal embayments are generally controlled by seasonal meteorological conditions, storms having a particularly strong influence. In the present study, such hydrodynamic processes and associated deposits have been investigated in a coastal embayment located along the southeast coast of Brazil, i.e. Espírito Santo Bay, in the winter (June/July) of 2008. The bay has undergone a series of human interventions that have altered the local hydrodynamic processes and, consequently, the sediment transport patterns. Facies distribution and sediment dynamics were examined by acoustic seabed mapping, sediment and core sampling, hydrodynamic measurements and sand transport modelling. The results show that sediment distribution can be described in terms of nearshore and offshore zones. The offshore bay sector is predominantly composed of "palimpsest" lithoclastic medium-coarse sands deposited in the course of the early Holocene transgression that peaked about 5,000 years ago. In the inner bay or nearshore zone (up to depths of 4-8 m), these older transgressive deposits are today overlain by a thin (up to 30-cm-thick) and partly patchy blanket of younger regressive fine sand/muddy fine sands. Both coarse- and fine-grained facies are being reworked during high-energy events (Hs>1.5 m) when fine sediment is resuspended, weak tide-induced drift currents causing the sand patches to be displaced. The coarser sediment, by contrast, is mobilized as bedload to produce wave ripples with spacings of up to 1.2 m. These processes lead to a sharp spatial delimitation between a fine sand/mud facies and a rippled coarse sand facies. The fine sand patches have a relief of about 20-30 cm and reveal a typical internal tempestite depositional sequence. Fair-weather wave-induced sediment transport (Hssand patches concentrated in the north-eastern part of the bay. Because storm-induced deposits of the type observed in this study have an inherently patchy

  8. Morphology of submarine canyon system and geotechnical properties of surficial sediments across the Peru-Chile forearc

    Energy Technology Data Exchange (ETDEWEB)

    Bergersen, D.D.; Coulbourn, W.T.; Moberly, R.

    1989-03-01

    During August 1987, a SeaMARC II side-scan and sampling survey was conducted across the Peru-Chile forearc from 17/degrees/30'S to 19/degrees/30'S. Side-scan images reveal a complex submarine canyon system. Incised canyons meander across the Arequipa basin; their sinuosity results from erosion and cutbank slumping of the basin sediments. Lenticular packets of strata visible in reprocessed digital single-channel seismic profiles are interpreted to be buried channels. Tributary canyons coalesce into a single canyon at the structural high that deviates from its north-south course to a northeast-southwest course as a result of stream piracy. A dendritic drainage basin forming on the midslope may be the rejuvenation of an abandoned channel. Sediment properties were measured on 42 free-fall cores and 7 piston cores recovered both in and around the submarine canyon. Olive-gray (5Y 3/2) hemipelagic mud is the predominant sediment across the forearc. Most cores exhibit a small degree of bioturbation and thin laminae of sand; the number of sand laminae increases as the distance away from the canyon decreases. Shear strengths, averaged over a 1-m core length, decrease slightly with water depth. Carbonate content in all samples from this area is negligible with the exception of one piston core recovered from the upper reaches of the canyon, the bottom of which is composed of gravel- and sand-size shell fragments. Bulk mineralogy, determined from semiquantitative analysis of x-ray diffraction patterns, shows a decrease in relative feldspar percent and an increase in total clay content with increasing water depth. Preliminary analysis of core tops shows a mean grain size in the medium to very fine silt class, with increasing grain size toward the canyon. Smear slide counts generally show a surprisingly low abundance of volcanic glass and biogenic material, particularly diatoms.

  9. Searching for order in chaos: a sediment stratigraphical study of a multiple-impacted bay of the Baltic Sea

    Science.gov (United States)

    Vaalgamaa, S.; Korhola, A.

    2004-02-01

    The lithological and geochemical properties of sediment cores collected from a heavily impacted embayment in the Gulf of Finland, Baltic Sea, were investigated. Hillonlahti Bay has been the focus of much human activity, including timber and oil industries, transportation, housing, dredging and waste discharge, thus constituting an exceptionally challenging environment for sediment studies. A total of nine cores were sampled along perpendicular transects across the elongated bay, and described lithologically in the field. Major and trace element concentrations were determined for a "master core" taken from the central area of the bay. The vertical distribution of 210Pb, 137Cs and spheroidal carbonaceous particles (SCP) was also examined in order to provide a chronological framework for the sediment. Changes in the sediment nature and differences in the distributions of soluble heavy metals (Cd, Cr, Cu, Ni, V, Zn), lithophilous (Al, Ti, K, Mg, Ca, Na), redox-sensitive (Fe, Mn), and nutrient (TP) elementary concentrations were related to temporal and spatial processes. These include the building of the Hamina port starting in the mid-1930s, establishment of the timber and oil industry in 1950-1960s, construction of railway embankments in 1950 and 1996, increasing urbanisation from 1960s, and wastewater discharge between 1950 and 1987. The use of Cr as a preservative in the wood processing industry is reflected in the marked enrichment of Cr in the sediment, while the influence of wastewater discharge can be seen in the sediment record by a rise in concentrations of P and evidently organically bound Na, Cu and Zn. The results are encouraging in demonstrating that via a rather simple repertoire of sediment-analytical methods it is possible to obtain information about the land-use history and contamination in such a strongly rampaged system.

  10. The Vertical Distribution of Sediment Archaeal Community in the “Black Bloom” Disturbing Zhushan Bay of Lake Taihu

    Science.gov (United States)

    Fan, Xianfang; Xing, Peng

    2016-01-01

    Using the Illumina sequencing technology, we investigated the vertical distribution of archaeal community in the sediment of Zhushan Bay of Lake Taihu, where the black bloom frequently occurred in summer. Overall, the Miscellaneous Crenarchaeotal Group (MCG), Deep Sea Hydrothermal Vent Group 6 (DHVEG-6), and Methanobacterium dominated the archaeal community. However, we observed significant difference in composition of archaeal community among different depths of the sediment. DHVEG-6 dominated in the surface layer (0–3 cm) sediment. Methanobacterium was the dominating archaeal taxa in the L2 (3–6 cm) and L3 (6–10) sediment. MCG was most abundant in the L4 (10–15 cm) and L5 (15–20 cm) sediment. Besides, DHVEG-6 was significantly affected by the concentration of total phosphorus (TP). And loss on ignition (LOI) was an important environmental factor for Methanobacterium. As the typical archaeal taxa in the surface layer sediment, DHVEG-6 and Methanobacterium might be more adapted to abundant substrate supply from cyanobacterial blooms and take active part in the biomass transformation. We propose that DHVEG-6 and Methanobacterium could be the key archaeal taxa correlated with the “black bloom” formation in Zhushan Bay. PMID:26884723

  11. Sediment core record of global fallout and Bikini close-in fallout Pu in Sagami Bay, Western Northwest Pacific margin.

    Science.gov (United States)

    Zheng, Jian; Yamada, Masatoshi

    2004-07-01

    The total 239-240Pu activity and 240Pu/239Pu atom ratio in the sediments in Sagami Bay of the western Northwest Pacific margin were investigated using ICP-MS with a shield torch system. 239+240Pu inventories in the examined sediment cores were found to be much higher than those predicted from atmospheric global fallout (42 MBq/km2) at the same latitude. In addition, elevated 240Pu/239Pu atom ratios ranging from 0.22 to 0.28 were observed in the sediment samples. On the basis of the vertical profiles of 239+240Pu and characterized 240Pu/239Pu atom ratios in a sediment core collected in the center of Sagami Bay, we identified two distinct sources of fallout Pu in the bay: the global stratospheric fallout with characteristic 240Pu/239Pu ratio of 0.18 and the transported close-in fallout derived from Bikini and Enewetak surface nuclear weapon test series in the 1950s. We propose that the Pu transportation was mainly due to oceanic processes (for example, through the North Equatorial Current and the Kuroshio Current). Using a two fallout end-member model, we find that the contribution of Bikini close-in fallout Pu ranged from 44 to 59% in Sagami Bay sediments. To the best of our knowledge, this is the first report that Pu contamination, which originated from Bikini and Enewetak nuclear weapon test series in the 1950s, has extended westwards as far as the Japanese coast. PMID:15296298

  12. Sorption characteristics of uranium and thorium in bottom sediments of Mumbai Harbour Bay

    International Nuclear Information System (INIS)

    Since 232Th and 238U have been present over the time of existence of present marine systems, their chemical speciation and sorption behavior can provide data for development of predictive models for the long-term behavior of the synthetic radionuclides. For this study, 5 g dry sediment samples collected from two different locations of Mumbai Harbour Bay (MHB) was placed in a conical flask and equilibrated with 150 mL of sea water containing 10, 20, 30, 40, 50, 75 and 100 mg L-1 of uranium and thorium as UO2(NO3)2 and Th(NO3)4 solution. The sediment suspension was equilibrated for 7 days at 25 deg C. pH of sediment solution ranged from 7.6-7.8. After equilibration time, the distribution coefficients (kd) of uranium and thorium in each set of bottom sediments were determined. The % adsorption yields (> 99%) were found to be almost constant for both U and Th. At sufficiently high concentration, the partitioning behavior deviates from ideality due to removal of species by precipitation and distribution coefficients decreases. After achieving the saturation stage, the concentration of species in solution will not change and distribution coefficient will be constant. The sorption data were fitted to linear model, Freundlich and Langmuir isotherm models to predict the sorption behavior of uranium and thorium by the sediments. In Freundlich model, it was found to be closer to unity. Therefore linear model was observed to be highly suitable. For uranium, all models showed a better fit of the adsorption data and well agreement between them. Based on the linear model, the distribution coefficient of thorium was 1.61 times higher than uranium. However, for Th, linear model of kd gave the better fit (R2 = 0.96) than Freundlich isotherm models (R2 = 0.93) and Langmuir isotherm models (R2= 0.86). The amount of Freundlich sorption coefficient (Kf) of uranium and Thorium was observed to be 95500 Lkg-1 and 31623 Lkg-1 respectively. Based on Langmuir isotherm model, the maximum

  13. Pre- and post-monsoonal changes in grain size and heavy minerals in the sediments from Kalbadevi Bay, Ratnagiri, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Valsangkar, A.B.; Fernandes, D.

    Sediments from the Kalbadevi Bay, Ratnagiri collected during January, May and October have been studied for processes responsible for the observed grain size variations and heavy mineral distribution. The study shows transportation of loose sand...

  14. Water Quality and Sedimentation Data of the Coastal Intensive Site Network (CISNet) Long Term Monitoring Sites in Kaneohe Bay, Oahu, Hawaii from 1998 to 2001 (NODC Accession 0001473)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A long term project to monitor water quality and sediment processes in Kaneohe Bay was initiated in November 1998 and continued through July 2001. Four primary...

  15. National Status and Trends: Bioeffects Program - Magnitude and Extent of Sediment Toxicity in Four Bays of the Florida Panhandle: Pensacola, Choctawhatchee, St. Andrew and Apalachicola

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The toxicity of sediments in Pensacola, Choctawhatchee, St. Andrew and Apalachicola Bays was determined as part of bioeffects assessments performed by NOAA's...

  16. Radiocarbon and thermoluminescence dating of quaternary sediments in Deception Bay, southeast Queensland: some problems encountered

    International Nuclear Information System (INIS)

    Full text: Radiocarbon and Thermoluminescence dating of sediment facies were utilised to develop a chronometric framework for the quaternary coastal evolution of Deception Bay southeast Queensland (Cotter 1996). This chronometric framework was developed in the context of a broader geoarchaeological and palaeogeographical investigation of the indigenous cultural landscape of the area. The TL analysis confirmed the presence of previously undated Pleistocene sands within the study area. However in the course of dating one sedimentary sequence, conventional radiocarbon analysis of Notispisula sheldls produced an age of 5190± 90 years BP (Beta-85415) whilst an overlying sandy unit (shown by particle size analysis and SEM surface textural analysis to be aeolian transported) subject to TL-dating produced an age of 14,900 ± 3300 years BP (W1942). This poster highlights the considerations made in order to reconcile this obvious anomaly. In effect, previously obtained radiometric data within the study area (Flood 1981; Hall 1996), in conjunction with an examination of the adequacy of the sampled materials for radiocarbon and TL age determinations point to the TL determination being in error. Similar anomalies have been shown to occur elsewhere in southeast Queensland (Tejan-Kella et al. 1990) explanations for which have been related to selective rather than total bleaching of Holocene sands (Prescott personal communication). Re-dating of the sand sequence using the selective bleach method is required to examine whether the dating anomaly shown for Deception Bay parallels selective bleaching effects determined for other sequences within southeast Queensland. Unfortunately this is beyond the scope and funds of this geoarchaeological study

  17. Levels of 137Cs in muddy sediments on the seabed in the Bay of Cadiz (Spain). Part II. Model of vertical migration of 137Cs

    International Nuclear Information System (INIS)

    This second part of the study reports the development of a model to describe the vertical migration of the artificial radioisotope 137Cs in the sediment column on the seabed of the Bay of Cadiz. The application of the model provides an overall picture of the process of sedimentation in the Inner Bay of Cadiz. The spatial distribution of the rate of sedimentation enables us to study the sources of sediments and the means by which the sediments have been transported. A method has been derived from the rate of sedimentation to perform the dating of the layers of sediment. The model describes the behaviour of 137Cs in the area under study, taking into account the time of residence in the zones that are the source of accumulation, the origin of the sedimentary material, together with the diffusion of the radionuclide in the sediment of the seabed

  18. Postimpact deposition in the Chesapeake Bay impact structure: Variations in eustasy, compaction, sediment supply, and passive-aggressive tectonism

    Science.gov (United States)

    Kulpecz, A.A.; Miller, K.G.; Browning, J.V.; Edwards, L.E.; Powars, D.S.; McLaughlin, P.P., Jr.; Harris, A.D.; Feigenson, M.D.

    2009-01-01

    The Eyreville and Exmore, Virginia, core holes were drilled in the inner basin and annular trough, respectively, of the Chesapeake Bay impact structure, and they allow us to evaluate sequence deposition in an impact crater. We provide new high-resolution geochronologic (<1 Ma) and sequence-stratigraphic interpretations of the Exmore core, identify 12 definite (and four possible) postimpact depositional sequences, and present comparisons with similar results from Eyreville and other mid- Atlantic core holes. The concurrence of increases in ??18O with Chesapeake Bay impact structure sequence boundaries indicates a primary glacioeustatic control on deposition. However, regional comparisons show the differential preservation of sequences across the mid-Atlantic margin. We explain this distribution by the compaction of impactites, regional sediment-supply changes, and the differential movement of basement structures. Upper Eocene strata are thin or missing updip and around the crater, but they thicken into the inner basin (and offshore to the southeast) due to rapid crater infilling and concurrent impactite compaction. Oligocene sequences are generally thin and highly dissected throughout the mid-Atlantic region due to sediment starvation and tectonism, except in southeastern New Jersey. Regional tectonic uplift of the Norfolk Arch coupled with a southward decrease in sediment supply resulted in: (1) largely absent Lower Miocene sections around the Chesapeake Bay impact structure compared to thick sections in New Jersey and Delaware; (2) thick Middle Miocene sequences across the Delmarva Peninsula that thin south of the Chesapeake Bay impact structure; and (3) upper Middle Miocene sections that pinch out just north of the Chesapeake Bay impact structure. Conversely, the Upper Miocene-Pliocene section is thick across Virginia, but it is poorly represented in New Jersey because of regional variations in relative subsidence. ?? 2009 The Geological Society of America.

  19. Phosphate geochemistry, mineralization processes, and Thioploca distribution in shelf sediments off central Chile

    DEFF Research Database (Denmark)

    Holmkvist, Lars; Arning, Esther T.; Küster-Heins, Kathrin;

    2010-01-01

    Sediments underlying the major costal upwelling systems of the world oceans are hot-spots of modern formation of hydroxyapatites, often associated with benthic communities of large, nitrate-accumulating sulfur bacteria. We studied the association between phosphate release, organic phosphorus...

  20. Diffusion of Nitrogen and Phosphorus Across the Sediment-Water Interface and In Seawater at Aquaculture Areas of Daya Bay, China

    OpenAIRE

    Xiangju Cheng; Yingxue Zeng; Zhenren Guo; Liangsheng Zhu

    2014-01-01

    With the yearly increasing marine culture activities in floating cages in Daya Bay, China, the effects of pollution may overlap and lead to more severe water environmental problems. In order to track the impacts of the marine culture in floating cages on water environment, sediments and overlying water were sampled by cylindrical samplers at three representative aquaculture areas of Daya Bay. The water content, porosity, density of sediments as well as the vertical distributions of ammonia ni...

  1. Determination of the sedimentation rates in the Sepetiba bay northeastern area by using dating with the excesses 210 Pb radioisotope

    International Nuclear Information System (INIS)

    210 Pb dating, using two modes of data analysis, CIC and CRS, was used to determine sedimentation in the North East part of Sepetiba Bay. 210 Pb was leached from samples using dilute HBr and subsequently separated onto anionic exchange columns, followed by re-extraction and precipitation as Pb CrO4. The original method was modified by the introduction of a pre-digestion step whose purpose was to liberate the lead bound as sulphide. The sedimentation rates found o.68 - 0.98 cm.y-1 were moderate, compared to other authors estimates. Dating using the CRS model showed a maximum rate of sedimentation in the period between 1954 and 1977, when the riverine input was probably at its greatest. The CRS model appears to be more applicable to the data, since it works over longer periods and allows for variations in sedimentation rate. (author)

  2. Effect of Coarse Particle Volume Fraction on the Yield Stress of Muddy Sediments from Marennes Oléron Bay

    Directory of Open Access Journals (Sweden)

    A. Pantet

    2010-01-01

    Full Text Available Coastal erosion results from a combination of various factors, both natural and humaninduced, which have different time and space patterns. In addition, uncertainties still remain about the interactions of the forcing agents, as well as on the significance of non-local causes of erosion. We focused about the surface sediments in the Marennes Oléron bay, after a general description of the site that has many various activities. The superficial sediments show a mechanical behavior, mainly depends on the fine fraction for a composition that contains up to 60% of sandy material. Fine sediments fraction has a typical yield stress depending naturally of concentration or water content. This yield could be modified slightly or significantly by adding silt or sand. As a result, the rheological measurement sensitivity allows us to characterize five typical sediments that correlate with solid fraction and fine fraction.

  3. Distribution and contamination of metals and biogenic elements in sediments from Zhifu Bay of the Yellow Sea, China.

    Science.gov (United States)

    Wang, Zhaohui; Lu, Xinxin; Zhang, Ke

    2016-03-01

    Metals and biogenic elements were analyzed from surface sediments of sixteen stations and a 32cm core collected from Zhifu Bay in July 2009. High concentrations of biogenic silica (BSi) reflected the high diatom productivity in the Bay. Meanwhile, total organic carbon (TOC) in Zhifu Bay was mainly from terrestrial sources. All metals were lower than the marine sediment quality guidelines. Based on the vertical profiles of biogenic elements, there was a clear increase of TOC, total nitrogen (TN), and total phosphate (TP) between 1985 and 2000. TN concentrations decreased after the start of the operation of the sewage treatment plant in 1998; however TOC and BSi remained at high levels. Metal concentrations showed a general increase from the bottom to the top of the core. Most anthropogenic metals reached a maximum during 1996 and 2000, and decreased after the startup of the sewage plant; however, they have increased again recently. The results from correlation analysis and principal component analysis show that industrial pollution is the main source of Cd, Cr, Cu, Ni, Pb and Zn contamination in Zhifu Bay, and Yantai Port and ship transportation also contribute a lot to Cd, Cu, Hg, and Pb pollution. PMID:26969045

  4. The zonation of soft-bottom sediments in Gorgan Bay (Caspian Sea) using macrobenthos as indicator of ecological health

    OpenAIRE

    Ghorbanzadeh Zaferani, Seyed Ghasem

    2015-01-01

    In this study, in order to assess the ecological health status and zoning of soft bottom of Gorgan Bay, the spatial and temporal distribution of macrofauna and their relationship with environmental stress were investigated. Sediment samples were collected using a Van Veen grab at 22 sampling points, seasonally during 2012-2013. The averages (±SD) of the percentages of sand, silt, clay and TOM (Total Organic Matter) in the sediment samples were determined (44.4± 15, 53.4 ± 14, and 2.2 ±2.2 and...

  5. Associations among Plankton Abundance, Water Quality And Sediment Quality In The San Francisco Bay: Nitrogen And Phosphorus

    OpenAIRE

    Moritsch, Monica

    2011-01-01

    nutrients from anthropogenic pollution can degrade water quality and alter the balance of marine food webs. lying at the base of the trophic pyramid, plankton quickly respond to nutrient changes in the water, which can have repercussions throughout both pelagic and benthic food webs, and thus they serve as a good bioindicator of water quality. In early november 2009, we evaluated sediment pollution, water pollution, and plankton abundance at four shoreline sites in the San Francisco Bay. We t...

  6. Sediment profile image data from October 1999 in Apalachicola Bay, Florida

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Apalachicola Bay National Estuarine Research Reserve and the NOAA Office for Coastal Management worked together to map benthic habitats within Apalachicola Bay,...

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

    Institute of Scientific and Technical Information of China (English)

    Subramanian VEERASINGAM; Ramdoss VENKATACHALAPATHY; Thirunavukkarasu RAMKUMAR

    2014-01-01

    Clay mineralogy, texture size and statistical analyses were carried out on surface sediments from the continental shelf of Chennai, Bay of Bengal, India. The purpose of this study is to characterize the clay mineral distribution and its relation to the hydrodynamics off Chennai to identify the sources and transport pathways of the marine sediments. Characterization of clay minerals in coastal sediments by Fourier Transform Infrared (FTIR) spectroscopy has provided the association of quartz, feldspar, kaolinite, chlorite, illite and iron oxides (magnetite and hematite) derived from river catchments and coastal erosion. Kaolinite, chlorite, illite, iron oxides, and organic matter are the dominant minerals in Cooum, and Adayar region. High quartz and feldspar zones were identified in Marina, which are being confined the sand zone and paralleling the coast. The strong relationships among the wave energy density, sand, quartz and carbonate revealed that wave induced littoral drift system play a dominant role in transportation and deposition of sediments in the Chennai coast. The sediment texture and minerals data are in agreement well with the previous results of hydrodynamics and littoral drift models in this region. Multivariate statistical analyses (correlation, cluster and factor analyses) were carried out and obtained results suggested that clay minerals and organic matter are trapped in silt and clay particles, whereas quartz, feldspar and carbonate are associated with sand particles. Results of sediment sources and transport processes from this study will be useful to predict the fate of the pollutants released from land or the potential change in sediment delivery to coastal areas.

  8. Environmental quality in sediments of Cadiz and Algeciras Bays based on a weight of evidence approach (southern Spanish coast).

    Science.gov (United States)

    Usero, José Antonio; Rosado, Daniel; Usero, José; Morillo, José

    2016-09-15

    This research applies an integrated sediment quality assessment method using a weight of evidence approach to Cadiz and Algeciras Bays (southern Spain). The method is composed of several analyses (particle size profile, aqua regia extractable metals, acid labile metals, total organic carbon, toxicity bioassay with Photobacterium phosphoreum and macrobenthic community alteration). The proposed method provides a single result, the environmental degradation index (EDI). EDI defined samples as low degraded (outer areas of both bays) and moderately degraded (Inner Bay of Cadiz Bay, the surroundings of Algeciras port and the northern part of Algeciras Bay). These samples showed the highest concentration of aqua regia extractable metals, which exceeded effects range-low (ERL) for Zn (51-176mg/l), Cu (11-54mg/l), As (4.3-9.5mg/l), Hg (0.17-0.28mg/l), Ni (23-82mg/l), and. Cr (37-134mg/l). They also exceeded some quality criteria for total organic carbon (4.0-6.5%) and toxicity (120-240TU/g) and showed poor results for macrobenthic community. PMID:27371957

  9. Combined use of remote sensing and continuous monitoring to analyse the variability of suspended-sediment concentrations in San Francisco Bay, California

    Science.gov (United States)

    Ruhl, C.A.; Schoellhamer, D.H.; Stumpf, R.P.; Lindsay, C.L.

    2001-01-01

    Analysis of suspended-sediment concentration data in San Francisco Bay is complicated by spatial and temporal variability. In situ optical backscatterance sensors provide continuous suspended-sediment concentration data, but inaccessibility, vandalism, and cost limit the number of potential monitoring stations. Satellite imagery reveals the spatial distribution of surficial-suspended sediment concentrations in the Bay; however, temporal resolution is poor. Analysis of the in situ sensor data in conjunction with the satellite reflectance data shows the effects of physical processes on both the spatial and temporal distribution of suspended sediment in San Francisco Bay. Plumes can be created by large freshwater flows. Zones of high suspended-sediment concentrations in shallow subembayments are associated with wind-wave resuspension and the spring-neap cycle. Filaments of clear and turbid water are caused by different transport processes in deep channels, as opposed to adjacent shallow water.

  10. Speciation, distribution, and potential ecological risk assessment of heavy metals in Xiamen Bay surface sediment

    Institute of Scientific and Technical Information of China (English)

    LIN Cai; LIU Yang; LI Wenquan; SUN Xiuwu; JI Weidong

    2014-01-01

    Based on the survey of surface sediment in Xiamen Bay in October 2011, the speciation, distribution, and potential ecological risk assessment of heavy metals (Cu, Pb, Zn, Cd, and Cr) in this area were studied us-ing the sequential extraction method and ecological risk assessment method. The results indicated:(1) the total concentrations of these heavy metals were influenced by runoff, industrial wastewater, and sewage, and were all higher in the coastal area than the offshore area while the highest area of Pb was a little far-ther away from the coastal water due to atmosphere deposition;(2) sequential extractions suggested that Cu was mainly composed with residual and Fe/Mn-oxide bound fractions, Pb was bound to Fe/Mn-oxide, Zn and Cr were dominated by residual, and Cd bound to exchangeable and carbonate fractions; (3) the order of migration and transformation sequence was Cd>Pb>Cu>Zn>Cr and the degree of pollution was Cd>Pb>Cu>Zn>Cr;and (4) the ratios of the secondary and primary phases showed that Zn and Cr were both clean, Cu may be polluted, Pb was moderately polluted, while Cd was heavily polluted.

  11. Characterization of organic matter in sediment cores of the Todos os Santos Bay, Bahia, Brazil, by elemental analysis and 13C NMR

    International Nuclear Information System (INIS)

    Highlights: → The impact of human activity on the sediments of Todos os Santos Bay in Brazil was evaluated by EA and 13C NMR. → This article reports a study of six sediment cores collected at different depths and regions. → The elemental profiles of cores suggest an abrupt change in the sedimentation regime, corresponds to about 50 years ago, coinciding with the implantation of major onshore industrial projects. → The results presented illustrate several important aspects of environmental impact of human activity on this bay. - Abstract: The impact of human activity on the sediments of Todos os Santos Bay in Brazil was evaluated by elemental analysis and 13C Nuclear Magnetic Resonance (13C NMR). This article reports a study of six sediment cores collected at different depths and regions of Todos os Santos Bay. The elemental profiles of cores collected on the eastern side of Frades Island suggest an abrupt change in the sedimentation regime. Autoregressive Integrated Moving Average (ARIMA) analysis corroborates this result. The range of depths of the cores corresponds to about 50 years ago, coinciding with the implantation of major onshore industrial projects in the region. Principal Component Analysis of the 13C NMR spectra clearly differentiates sediment samples closer to the Subae estuary, which have high contents of terrestrial organic matter, from those closer to a local oil refinery. The results presented in this article illustrate several important aspects of environmental impact of human activity on this bay.

  12. Bioaccumulation potential of contaminants from bedded and suspended Oakland Harbor deepening project sediments to San Francisco Bay flatfish and bivalve mollusks. Final report

    Energy Technology Data Exchange (ETDEWEB)

    McFarland, V.A.; Clarke, J.U.; Lutz, C.H.; Jarvis, A.S.; Mulhearn, B.

    1994-08-01

    The Oakland Harbor Deepening Project (OHDP) has been on hold since 1987 due to public and resource agency concerns regarding further disposal of dredged sediments within San Francisco (SF) Bay. Dispersal of the fines fraction throughout the Bay was thought to occur following disposal operations at the Alcatraz site, resulting in transport of contaminants throughout the Bay system. The study described in this report was designed to address the potential for contaminant uptake in estuarine organisms through exposure to suspended and bedded OHDP sediments. Bioaccumulation that occurred from these sediments was put into perspective with bioaccumulation from sediments normally resuspended in the Bay by natural processes, and from a demonstrably contaminated sediment. Indigenous SF Bay organisms were exposed to either bedded or suspended sediment in replicate experimental units of the Flow-through Aquatic Toxicology Exposure System (FATES) at the WES. Sediments and tissues were analyzed for a suite of contaminants, including organotins, polynuclear aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides and DDE, and ten metals.

  13. 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.

  14. Rapid sedimentation of iron oxyhydroxides in an active hydrothermal shallow semi-enclosed bay at Satsuma Iwo-Jima Island, Kagoshima, Japan

    Science.gov (United States)

    Kiyokawa, Shoichi; Ueshiba, Takuya

    2015-04-01

    Hydrothermal activity is common in the fishing port of Nagahama Bay, a small semi-enclosed bay located on the southwest coast of Satsuma Iwo-Jima Island (38 km south of Kyushu Island, Japan). The bay contains red-brown iron oxyhydroxides and thick deposits of sediment. In this work, the high concentration and sedimentation rates of oxyhydroxide in this bay were studied and the sedimentary history was reconstructed. Since dredging work in 1998, a thickness of ~ 1.0-1.5 m of iron oxyhydroxide-rich sediments has accumulated on the floor of the bay. To estimate the volume of iron oxyhydroxide sediments and the amount discharged from hydrothermal vents, sediment traps were operated for several years and 13 sedimentary core samples were collected to reconstruct the 10-year sedimentary history of Nagahama Bay. To confirm the timing of sedimentary events, the core data were compared with meteorological records obtained on the island, and the ages of characteristic key beds were thus identified. The sedimentation rate of iron oxyhydroxide mud was calculated, after correcting for sediment input from other sources. The sediments in the 13 cores from Nagahama Bay consist mainly of iron oxyhydroxide mud, three thick tephra beds, and a topmost thick sandy mud bed. Heavy rainfall events in 2000, 2001, 2002, and 2004-2005 coincide with tephra beds, which were reworked from Iwo-Dake ash deposits to form tephra-rich sediment. Strong typhoon events with gigantic waves transported outer-ocean-floor sediments and supplied quartz, cristobalite, tridymite, and albite sands to Nagahama Bay. These materials were redeposited together with bay sediments as the sandy mud bed. Based on the results from the sediment traps and cores, it is estimated that the iron oxyhydroxide mud accumulated in the bay at the relatively rapid rate of 33.3 cm/year (from traps) and 2.8-4.9 cm/year (from cores). The pore water contents within the sediment trap and core sediments are 73%-82% and 47

  15. Evaluation of surface water and sediment quality in Chicalim Bay, Nerul Creek, and Chapora Bay from Goa coast, India-a statistical approach.

    Science.gov (United States)

    Shenai-Tirodkar, P S; Gauns, M U; Ansari, Z A

    2016-08-01

    To better understand the spatial and temporal variation in surface water and sediment quality, parameters were evaluated from the three sites Chicalim Bay (CB), Nerul Creek (NC), and Chapora Bay (ChB) along the Goa coast, which has major oyster beds. Multivariate analysis such as cluster analysis (CA), Box-Whisker plot (Box plot), and principle component analysis (PCA) revealed that nitrate (NO3-N), nitrite (NO2-N), phosphate (PO4-P), particulate organic carbon (POC), total suspended solids (TSS), dissolved oxygen (DO), and phaeopigments are the responsible parameters for spatio-temporal variability among the studied sites. Results showed an elevated level of ecotoxicological hazard at CB while moderate toxicological risks were observed for organisms at NC. In contrast, ChB was considerably pristine compared with other two sampling sites. Results of present study showed marked dominance of nutrients, phaeopigments, POC, and TSS at CB and NC. The increased levels of these parameters are attributed to the anthropogenic activities which may cause potential risk to humans via consumption of oysters. Therefore, we suggest monitoring heavy metal concentrations in tissue of commercially important oyster species, and their ambient environment (water and sediment) from these estuaries is necessary to create a comprehensive pollution database. PMID:27421260

  16. The South Carolina Coastal Erosion Study: Numerical modeling of circulation and sediment transport in Long Bay, SC

    Science.gov (United States)

    Warner, J. C.; Sullivan, C.; Voulgaris, G.; Work, P.; Haas, K.; Hanes, D. M.

    2004-12-01

    Long Bay, South Carolina, is a heavily populated coastal region that supports a large tourism industry. Sand resources are important for both recreation and coastal habitat. Earlier geological framework studies have identified a large sand deposit oblique to the shoreline, oriented clockwise in the offshore direction. This sand feature is ~ 10 km long, 2 km wide, and in excess of 3m thick, possibly providing a source for beach nourishment material. Objectives of this study are to describe the physical processes that control the transport of sediment in Long Bay, specifically off the coast of Myrtle Beach, South Carolina. Specifically we seek to 1) measure and model the oceanographic circulation in the region, 2) identify the processes that maintain the presence of the offshore sand feature, 3) quantify the control that the shoal exerts on the nearshore through changes in wave energy propagation, and 4) identify consequences of removal of the offshore sand feature. Both observational and numerical experiments are used to study the oceanographic circulation and transport of sediment. The observational study is described in an accompanying poster and consists of eight sites that measured tides, surface waves, currents, salinity, temperature, suspended sediment concentrations, and bed forms from October 2003 to April 2004. Numerical modeling for circulation and sediment transport in the study region uses a new version of ROMS (v2.1) that now includes transport of multiple grain sizes, coupling of sediment transport to wave bottom boundary layer models, and evolution of the bottom morphology. The SWAN model is used to compute wave propagation. Results indicate that currents in the study area are strongly influenced by both tidal motion and wind driven setup / setdown. The presence of the offshore sand feature alters the residual flows in the region. Sediment transport is more significant during periods of sustained strong winds that generate local waves. Wind direction

  17. Morphology and texture of modern sediments on the inner shelf of South Carolina's Long Bay from Little River Inlet to Winyah Bay

    Science.gov (United States)

    Denny, J.F.; Baldwin, W.E.; Schwab, W.C.; Gayes, P.T.; Morton, R.; Driscoll, N.W.

    2007-01-01

    High-resolution sea-floor mapping techniques, including sidecan-sonar, seismic-reflection, swath bathymetric systems, and bottom sampling, were used to map the geologic framework offshore of the northern South Carolina coast in order to provide a better understanding of the physical processes controlling coastal erosion and shoreline change. Four general sea floor environments were identified through analysis of sidescan-sonar, swath bathymetry, and surface sediment texture: inlet shoal complexes, shore-detached shoals, hardground, and mixed zones. Inlet shoal complexes generally lie offshore of modern inlet systems, with the exception of a shore-detached shoal lying offshore of Myrtle Beach. The shoals show 1 - 3 m in relief and comprise the largest accumulations of modern sediment within the inner shelf survey area. Surficial sediments within the shoal complexes are characterized by a low-backscatter, moderately sorted fine sand. Hardground areas are characterized by exposures of Cretaceous and Tertiary strata and Pleistocene channel-fill deposits. These areas display little to no bathymetric relief and are characterized by high-backscatter, coarser grained sand. Mixed zones show small-scale spatial variations in bathymetry, surface texture and backscatter. These areas are characterized by a thin layer of modern sediment ( Textural and geomorphic variations suggest a long-term net southerly flow within the study area. The general acoustic and textural character of the inner shelf within Long Bay suggests long-term erosion, reworking and continued modification of inner-shelf deposits by modern nearshore processes.

  18. Distribution and generic composition of culturable marine actinomycetes from the sediments of Indian continental slope of Bay of Bengal

    Science.gov (United States)

    Das, Surajit; Lyla, P. S.; Ajmal Khan, S.

    2008-05-01

    Actinomycetes population from continental slope sediment of the Bay of Bengal was studied. Samples were collected during two voyages of FORV Sagar Sampada in 2004 (May-June) and 2005 (July) respectively from 11 transects (each transect had ca. 200 m, 500 m, and 1 000 m depth stations). The physicochemical parameters of overlying water, and sediment samples were also recorded. The actinomycete population ranged from 5.17 to 51.94 CFU/g dry sediment weight and 9.38 to 45.22 CFU/g dry sediment weight during the two cruises respectively. No actinomycete colony was isolated from stations in 1 000 m depth. Two-way analysis of variance showed significant variation among stations (ANOVA two-way, P0.05). Three actinomycetes genera were identified. Streptomyces was found to be the dominating one in both the cruises, followed by Micromonospora, and Actinomyces. The spore of Streptomyces isolates showed the abundance in spiral spore chain. Spore surface was smooth. Multiple regression analysis revealed that the influencing physico-chemical factors were sediment pH, sediment temperature, TOC, porosity, salinity, and pressure. The media used in the present study was prepared with seawater. Thus, they may represent an autochthonous marine flora and deny the theory of land runoff carriage into the sea for adaptation to the salinity of the seawater and sediments.

  19. 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.

  20. A preliminary evaluation of Trinity river sediment and nutrient loads into Galveston Bay, Texas, during two periods of high flow

    Science.gov (United States)

    Lee, Michael T.

    2010-01-01

    Suspend-sediment and water-quality data were measured during two periods o high flow, one during April 20-23, 2009 and a second during September 22-November 3, 2009. On the basis of streamflow and continuous and discrete water-quality measurements, the two periods of high flow had different flood and nutrient loading characteristics. Some differences in the nature of these two periods of high flow were evident. Preliminary results indicate that it might be possible to better understand the extent of sediment and nutrient loading in Galveston Bay using selected measurements of discrete and continuous water-quality data. An apparent correlation was observed between the concentrations of selected nutrients and suspended sediment, and an apparent correlation was observed between suspended sediment and total nutrient concentration measured with in-situ turbidity measurements during periods of high flow in Trinity River at the Wallisville, Texas gage, about 3.5 miles upstream from where the Trinity River enters Galveston Bay. Additional data are needed to confirm these preliminary results.  

  1. Fate of corrosion products released from stainless steel in marine sediments and seawater. Part 2. Sequim Bay clayey silt

    International Nuclear Information System (INIS)

    This report describes laboratory experiments in which neutron-activated 347 stainless steel specimens were exposed to clayey silt from Sequim Bay, Washington. The properties and trace metal geochemistry of the sediment and the amounts of corrosion products that were released under oxic and reduced conditions and their distribution among different chemical fractions of the sediment are discussed. The distributions of Cr, Mn, Fe, Ni and Cu among different chemical forms in the Sequim Bay sediment show that DTPA removed <10% of extractable Cr, Fe and Mn, approx. 20% of extractable Ni and approx. 30% of extractable Cu. The inorganic fraction (material soluble in 2.5% acetic acid) accounted for approx. 30% of total extractable Mn and approx. 10% or less of Cr, Fe, Ni and Cu. Major portions of Cr and Cu, and a large amount of Fe were in the organic fraction. Extractable Mn, Fe and Ni were associated with hydrous oxides likely as coatings on the mineral substrate of the sediment. No Co was detectable in any of the extracts

  2. A Sr-Nd isotopic study of sand-sized sediment provenance and transport for the San Francisco Bay coastal system

    Science.gov (United States)

    Rosenbauer, Robert J.; Foxgrover, Amy C.; Hein, James R.; Swarzenski, Peter W.

    2013-01-01

    A diverse suite of geochemical tracers, including 87Sr/86Sr and 143Nd/144Nd isotope ratios, the rare earth elements (REEs), and select trace elements were used to determine sand-sized sediment provenance and transport pathways within the San Francisco Bay coastal system. This study complements a large interdisciplinary effort (Barnard et al., 2012) that seeks to better understand recent geomorphic change in a highly urbanized and dynamic estuarine-coastal setting. Sand-sized sediment provenance in this geologically complex system is important to estuarine resource managers and was assessed by examining the geographic distribution of this suite of geochemical tracers from the primary sources (fluvial and rock) throughout the bay, adjacent coast, and beaches. Due to their intrinsic geochemical nature, 143Nd/144Nd isotopic ratios provide the most resolved picture of where sediment in this system is likely sourced and how it moves through this estuarine system into the Pacific Ocean. For example, Nd isotopes confirm that the predominant source of sand-sized sediment to Suisun Bay, San Pablo Bay, and Central Bay is the Sierra Nevada Batholith via the Sacramento River, with lesser contributions from the Napa and San Joaquin Rivers. Isotopic ratios also reveal hot-spots of local sediment accumulation, such as the basalt and chert deposits around the Golden Gate Bridge and the high magnetite deposits of Ocean Beach. Sand-sized sediment that exits San Francisco Bay accumulates on the ebb-tidal delta and is in part conveyed southward by long-shore currents. Broadly, the geochemical tracers reveal a complex story of multiple sediment sources, dynamic intra-bay sediment mixing and reworking, and eventual dilution and transport by energetic marine processes. Combined geochemical results provide information on sediment movement into and through San Francisco Bay and further our understanding of how sustained anthropogenic activities which limit sediment inputs to the system (e

  3. Environmental implications of the use of sulfidic back-bay sediments for dune reconstruction - Lessons learned post Hurricane Sandy.

    Science.gov (United States)

    Plumlee, Geoffrey S; Benzel, William M; Hoefen, Todd M; Hageman, Philip L; Morman, Suzette A; Reilly, Timothy J; Adams, Monique; Berry, Cyrus J; Fischer, Jeffrey M; Fisher, Irene

    2016-06-30

    Some barrier-island dunes damaged or destroyed by Hurricane Sandy's storm surges in October 2012 have been reconstructed using sediments dredged from back bays. These sand-, clay-, and iron sulfide-rich sediments were used to make berm-like cores for the reconstructed dunes, which were then covered by beach sand. In November 2013, we sampled and analyzed partially weathered materials collected from the cores of reconstructed dunes. There are generally low levels of metal toxicants in the reconstructed dune materials. However oxidation of reactive iron sulfides by percolating rainwater produces acid-sulfate pore waters, which evaporate during dry periods to produce efflorescent gypsum and sodium jarosite salts. The results suggest use of sulfidic sediments in dune reconstruction has both drawbacks (e.g., potential to generate acid runoff from dune cores following rainfall, enhanced corrosion of steel bulwarks) and possible benefits (e.g., efflorescent salts may enhance structural integrity). PMID:27210565

  4. [Residues and risk assessment of polycyclic aromatic hydrocarbons in the surface sediments and marine organisms from Dapeng Bay, Shenzhen].

    Science.gov (United States)

    Sun, Run-Xia; Ke, Chang-Liang; Gu, Yang-Guang; Lu, Teng-Teng; Du, Fei-Yan; Ma, Sheng-Wei; Lin, Qin

    2013-10-01

    In order to assess contamination by polycyclic aromatic hydrocarbons (PAHs), surface sediments and marine organism samples of fish, shrimp and shellfish were collected from the Dapeng Bay, Shenzhen in October 2011. Concentrations fof sixteen priority PAHs were determined by gas chromatography and mass spectrometry (GC-MS). The total concentrations of PAHs (Sigma PAHs ) ranged from 216. 56 ng.g-1 to 1 314. 92 ng.g-1 dry weight in sediment samples and from 70. 88 ng.g-1 to 251.90 ng.g-1 wet weight in biological samples, respectively. The mean concentration was the highest in fish (171.52 ng.g-1 ), followed by mussel (134.75 ng.g-1) and shrimp (123.35 ng.g-1) in the studied marine organisms. Compared with those in other water bodies around the world, PAHs pollution in the studied area was at medium level. The dominant fraction in the surface sediments was the 4-ring PAHs. Identification of PAH sources suggested that PAHs in Dapeng Bay were likely originated from both pyrolytic and petrogenic sources. The most abundant PAHs were 3-ring PAHs in the tissues of organisms, which may be governed by their feeding behaviors, habitats, and bioavailability of PAHs. Ecological risk assessment indicated that PAHs in surface sediments might have adverse impacts on local ecosystem. Health risk analysis revealed that the potency equivalent concentrations of BaP to the total PAHs in marine organisms from Dapeng Bay were relatively high and may cause some concerns on human health by consumption. PMID:24364300

  5. Petroleum pollution in surface sediments of Daya Bay, South China, revealed by chemical fingerprinting of aliphatic and alicyclic hydrocarbons

    Science.gov (United States)

    Gao, Xuelu; Chen, Shaoyong

    2008-10-01

    Nine surface sediments collected from Daya Bay have been Soxhlet-extracted with 2:1 (v/v) dichloromethane-methanol. The non-aromatic hydrocarbon (NAH) fraction of solvent extractable organic matter (EOM) and some bulk geochemical parameters have been analyzed to determine petroleum pollution of the bay. The NAH content varies from 32 to 276 μg g -1 (average 104 μg g -1) dry sediment and accounts for 5.8-64.1% (average 41.6%) of the EOM. n-Alkanes with carbon number ranging from 15 to 35 are identified to be derived from both biogenic and petrogenic sources in varying proportions. The contribution of marine authigenic input to the sedimentary n-alkanes is lower than the allochthonous input based on the average n-C 31/ n-C 19 alkane ratio. 25.6-46.5% of the n-alkanes, with a mean of 35.6%, are contributed by vascular plant wax. Results of unresolved complex mixture, isoprenoid hydrocarbons, hopanes and steranes also suggest possible petroleum contamination. There is strong evidence of a common petroleum contamination source in the bay.

  6. Recent sediment transport and deposition in the Cap-Ferret Canyon, South-East margin of Bay of Biscay

    Science.gov (United States)

    Schmidt, Sabine; Howa, Hélène; Diallo, Amy; Martín, Jacobo; Cremer, Michel; Duros, Pauline; Fontanier, Christophe; Deflandre, Bruno; Metzger, Edouard; Mulder, Thierry

    2014-06-01

    The Cap-Ferret Canyon (CFC), a major morphologic feature of the eastern margin of the Bay of Biscay, occupies a deep structural depression that opens about 60 km southwest of the Gironde Estuary. Detailed depth profiles of the particle-reactive radionuclides 234Th and 210Pb in interface sediments were used to characterise the present sedimentation (bioturbation, sediment mass accumulation, and focusing) in the CFC region. Two bathymetric transects were sampled along the CFC axis and the southern adjacent margin. Particle fluxes were recorded from the nearby Landes Plateau by means of sediment traps in 2006 and 2007. This dataset provides a new and comprehensive view of particulate matter transfer in the Cap-Ferret Canyon region, through a direct comparison of the canyon with the adjacent southern margin. Radionuclide profiles (234Th and 210Pb) and mass fluxes demonstrate that significant particle dynamics occur on the SE Aquitanian margin in comparison with nearby margins. The results also suggest show three distinct areas in terms of sedimentary activity. In the upper canyon (2000 m) can be considered inactive at annual or decadal scales. In contrast with the slow and continuous accumulation of relatively fresh material that characterises the middle canyon, the lower canyon receives pulses of sediment via gravity flows on longer time scales. At decadal scale, the CFC can be considered as a relatively quiescent canyon. The disconnection of the CFC from major sources of sediment delivery seems to limit its efficiency in particle transfer from coastal areas to the adjacent ocean basin.

  7. Determination of typical lipophilic marine toxins in marine sediments from three coastal bays of China using liquid chromatography-tandem mass spectrometry after accelerated solvent extraction.

    Science.gov (United States)

    Wang, Yanlong; Chen, Junhui; Li, Zhaoyong; Wang, Shuai; Shi, Qian; Cao, Wei; Zheng, Xiaoling; Sun, Chengjun; Wang, Xiaoru; Zheng, Li

    2015-12-30

    A method based on sample preparation by accelerated solvent extraction and analysis by liquid chromatography-tandem mass spectrometry was validated and used for determination of seven typical lipophilic marine toxins (LMTs) in marine sediment samples collected from three typical coastal bays in China. Satisfactory specificity, reproducibility (RSDs ≤ 14.76%), stability (RSDs ≤ 17.37%), recovery (78.0%-109.0%), and detection limit (3.440 pg/g-61.85 pg/g) of the developed method were achieved. The results obtained from the analysis of samples from Hangzhou Bay revealed okadaic acid as the predominant LMT with concentrations ranging from 186.0 to 280.7 pg/g. Pecenotoxin-2 was quantified in sediment samples from Laizhou Bay at the concentrations from 256.4 to 944.9 pg/g. These results suggested that the proposed method was reliable for determining the typical LMTs in marine sediments and that the sediments obtained from Hangzhou Bay, Laizhou Bay and Jiaozhou Bay were all contaminated by certain amounts of LMTs. PMID:26507511

  8. A geochemical record of environmental changes in sediments from Sishili Bay, northern Yellow Sea, China: Anthropogenic influence on organic matter sources and composition over the last 100 years

    International Nuclear Information System (INIS)

    Highlights: • Increased TOC and TN in the sediment cores indicated a eutrophic trend since 1975. • Marine organic matter sources dominated in Sishili Bay. • Scallop culture displayed mitigation on eutrophication pressures in Sishili Bay. • Increased fertilizer use well matched eutrophic process in Sishili Bay in 1975. -- Abstract: Total organic carbon (TOC), total nitrogen (TN), δ13C and δ15N were measured in sediment cores at three sites in Sishili Bay, China, to track the impacts of anthropogenic activities on the coastal environment over the last 100 years. The increased TOC and TN in the upper section of sediment cores indicated a eutrophic process since 1975. In comparison, the TOC and TN in the sediment core near to a scallop aquaculture area displayed a much slower increase, indicating the contribution of scallop aquaculture in mitigating eutrophication. Combined information from δ13C, δ15N and TOC:TN indicated an increased terrestrial signal, although organic matter sources in Sishili Bay featured a mixture of terrestrial and marine sources, with phytoplankton being dominant. Increased fertilizer use since 1970s contributed to the eutrophic process in Sishili Bay since 1975, and increased sewage discharge from 1990s has added to this process

  9. Modeling the fate of p,p'-DDT in water and sediment of two typical estuarine bays in South China: Importance of fishing vessels' inputs.

    Science.gov (United States)

    Fang, Shu-Ming; Zhang, Xianming; Bao, Lian-Jun; Zeng, Eddy Y

    2016-05-01

    Antifouling paint applied to fishing vessels is the primary source of dichloro-diphenyl-trichloroethane (DDT) to the coastal marine environments of China. With the aim to provide science-based support of potential regulations on DDT use in antifouling paint, we utilized a fugacity-based model to evaluate the fate and impact of p,p'-DDT, the dominant component of DDT mixture, in Daya Bay and Hailing Bay, two typical estuarine bays in South China. The emissions of p,p'-DDT from fishing vessels to the aquatic environments of Hailing Bay and Daya Bay were estimated as 9.3 and 7.7 kg yr(-1), respectively. Uncertainty analysis indicated that the temporal variability of p,p'-DDT was well described by the model if fishing vessels were considered as the only direct source, i.e., fishing vessels should be the dominant source of p,p'-DDT in coastal bay areas of China. Estimated hazard quotients indicated that sediment in Hailing Bay posed high risk to the aquatic system, and it would take at least 21 years to reduce the hazards to a safe level. Moreover, p,p'-DDT tends to migrate from water to sediment in the entire Hailing Bay and Daya Bay. On the other hand, our previous research indicated that p,p'-DDT was more likely to migrate from sediment to water in the maricultured zones located in shallow waters of these two bays, where fishing vessels frequently remain. These findings suggest that relocating mariculture zones to deeper waters would reduce the likelihood of farmed fish contamination by p,p'-DDT. PMID:27016888

  10. Radioanalytical assessment of sedimentation rates in Guajara Bay (Amazon Estuary, N Brazil). A study with unsupported 210Pb and 137Cs modeling

    International Nuclear Information System (INIS)

    Guajara Bay is an integral part of the Amazon Estuary system, and functions as the main receiver of urban and industrial wastes from the city of Belem, capital city of PA State (N Brazil). There is a lack of knowledge regarding quantitative measures of sedimentation, such as sedimentation rates, in the literature for this area of the Amazon Estuary. This study aimed the evaluation of recent (time range of 100 years) sedimentation rates in three sediment profiles collected in the coastal system of Guajara Bay with a radioanalytical approach of unsupported 210Pb and 137Cs modeling. The mean sedimentation rates for the cores obtained were 0.85 ± 0.12 cm year-1 for Anadim core, 1.02 ± 0.17 cm year-1 for Outeiro core and 0.53 ± 0.04 cm year-1 for Tucunduba core. With the use of three models of sedimentation rate models, it was observed that Anadim and Outeiro core presented constant sedimentation rates for the evaluated time range, but Tucunduba did not. This difference in sedimentation rates was probably due to their different sampling locations that present diverse hydrodynamic regime, with deposition of fine sediments in the upper area of the bay and stronger fluvial currents in the southernmost region. (author)

  11. Spatial distribution of organic and pyritic sulfur in surface sediments of eutrophic Jiaozhou Bay, China: clues to anthropogenic impacts.

    Science.gov (United States)

    Chen, Ke-Ke; Zhu, Mao-Xu; Yang, Gui-Peng; Fan, De-Jiang; Huang, Xiang-Li

    2014-11-15

    Anthropogenic perturbations exert important impacts on sulfur geochemistry in marine sediments. In the study, chemical extraction was used to quantify four sulfur pools, i.e., pyrite, humic-acid sulfur (HA-S), fulvic-acid sulfur (FA-S), and residual organic sulfur (ROS), in surface sediments of eutrophic Jiaozhou Bay. Results show that riverine inputs are the main control on organic matter (OM) distribution in the sediments. OM enrichment in the eastern coast is mainly due to discharges of anthropogenic wastes. Spatial coupling of pyrite and FA-S vs. TOC points to the impacts of OM enrichment on formation and preservation of pyrite and FA-S. Poor spatial coupling of HA-S vs. TOC is due to low fractions of diagenetic OS in the pool. ROS is mainly from riverine inputs and anthropogenic OS has been superimposed on this pool. Spatial coupling among TOC, pyrite-S and FA-S is a sensitive indicator of anthropogenic impacts on benthic processes of the bay. PMID:25220315

  12. Sources and distribution of aliphatic and polyaromatic hydrocarbons in coastal sediments from the Ushuaia Bay (Tierra del Fuego, Patagonia, Argentina).

    Science.gov (United States)

    Commendatore, Marta G; Nievas, Marina L; Amin, Oscar; Esteves, José L

    2012-03-01

    The environmental quality of Ushuaia Bay, located at the southernmost tip of South America, is affected by the anthropogenic pressure of Ushuaia city. In this study, levels and sources of hydrocarbons in coastal sediments were assessed. Aliphatic hydrocarbon fractions ranged between 5.5 and 1185.3 μg/g dry weight and PAHs from not detected to 360 ng/g. Aliphatic diagnostic indices, the nalkanes homologous series occurrence, Aliphatic Unresolved Complex Mixtures (AliUCMs), and pristane and phytane isoprenoids indicated a petrogenic input. Some sites showed biogenic features masked by the anthropogenic signature. Particularly in port areas biodegradation processes were evident. PAH ratios showed a mixture of petrogenic and pyrogenic sources. Aliphatic and aromatic UCMs were strongly correlated, reflecting chronic pollution. Three areas were distinguished inside the bay: (1) east, with low hydrocarbons impact; (2) central, where hydrocarbons accumulation was related to source proximity and sediment characteristics; (3) south-west, where sediment characteristics and current circulation favour hydrocarbons accumulation. PMID:22189069

  13. Partitioning of heavy metals in the surface sediments of Quanzhou Bay wetland and its availability to Suaeda australis

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In order to investigate distributions of heavy metal pollution in Quanzhou Bay wetland, the total concentration and chemical partitioning of a number of heavy metals (Cu, Zn, Cd, Pb, Cr, Hg) in sediments of three sampling sites of Quanzhou Bay wetland and their availability to Suaeda australis were analyzed. The Geoaccumulation Index (Igeo) values reveal that the sediments of three sampling sites may all be considered as moderately contaminated for Pb and Zn, and all sediments might be strongly contaminated with cadmium. The partitioning analyses revealed the measured heavy metals in three sites are bound to the exchangeable fraction at lower concentrations. The measured metals in a considerable amount are bound to the reducible and oxidizable fractions, and a high proportion of the measured heavy metals were distributed in the residual fraction in the sediment samples. The concentrations of Cd in each chemical phase extracted from the sediments are above natural global background levels and should be further investigated because of its toxicity. Suaeda australis has different accumulation abilities for the measured heavy metals. For the root and stem, the bioaccumulation ability assessed by bioaccumulation factor (BA F) for the measured heavy metals follows the decreasing order as: Cu>Cr> Zn>Cd, Pb, Hg. In the leaf, stronger bioaccumulation ability for Hg is exhibited. The heavy metal concentrations in Suaeda australis roots have positive correlations with their available fractions, while the exchangeable fraction of Cu and Cd might have be more important to both mature plant roots and seedling roots uptake than other fractions; as for Cr, the oxidizable fraction might make a greater contribution to the plant root uptake; as for Zn, the reducible fraction might make so contribution; and for Pb, the oxidizable fraction might make a significant contribution to the mature plant root uptake, however, the exchangeable fraction might have a significant

  14. Bioturbation depths, rates and processes in Massachusetts Bay sediments inferred from modeling of 210Pb and 239 + 240Pu profiles

    Science.gov (United States)

    Crusius, John; Bothner, Michael H.; Sommerfield, Christopher K.

    2004-01-01

    Profiles of 210Pb and 239 + Pu from sediment cores collected throughout Massachusetts Bay (water depths of 36-192 m) are interpreted with the aid of a numerical sediment-mixing model to infer bioturbation depths, rates and processes. The nuclide data suggest extensive bioturbation to depths of 25-35 cm. Roughly half the cores have 210Pb and 239 + 240Pu profiles that decrease monotonically from the surface and are consistent with biodiffusive mixing. Bioturbation rates are reasonably well constrained by these profiles and vary from ~0.7 to ~40 cm2 yr-1. As a result of this extensive reworking, however, sediment ages cannot be accurately determined from these radionuclides and only upper limits on sedimentation rates (of ~0.3 cm yr-1) can be inferred. The other half of the radionuclide profiles are characterized by subsurface maxima in each nuclide, which cannot be reproduced by biodiffusive mixing models. A numerical model is used to demonstrate that mixing caused by organisms that feed at the sediment surface and defecate below the surface can cause the subsurface maxima, as suggested by previous work. The deep penetration depths of excess 210Pb and 239 + 240Pu suggest either that the organisms release material over a range of >15 cm depth or that biodiffusive mixing mediated by other organisms is occurring at depth. Additional constraints from surficial sediment 234Th data suggest that in this half of the cores, the vast majority of the present-day flux of recent, nuclide-bearing material to these core sites is transported over a timescale of a month or more to a depth of a few centimeters below the sediment surface. As a consequence of the complex mixing processes, surface sediments include material spanning a range of ages and will not accurately record recent changes in contaminant deposition.

  15. Heavy metal determination by X-rays spectrometry for superficial sediments at Guantanamo bay

    International Nuclear Information System (INIS)

    Twelve surface samples of the Guantanamo Bay (Cuba) were collected and analysed by X-Rays Spectrometry. Twenty one elements (Si, Ca, K, Na, P, S, Cl, Al, Fe, Mg, Ti, Mn, C, O, Cr, Cu, Ni, Co, Pb, V and Zn) have been determined. The distribution of the metals is associated with the wastewater from anthropogenic origin that receives the bay, mainly by fluvial currents. Multivariate statistical were used for the analysis of the results. Finally the results analysed were compared with the analysis performed by Engineering Centre for Environmental Management of Bays and Coasts (Cimab) using Inductively Coupled Plasma Emission (ICP) for some elements such as: Cr, Cu, Fe, Ni, Pb, V and Zn. The results show the Guantanamo Bay is less polluted than others Cuban Bays. (Author)

  16. Diversity of Ammonia-Oxidizing Archaea and Bacteria Across Physical-Chemical Gradients in San Francisco Bay Estuary Sediments

    Science.gov (United States)

    Mosier, A. C.; Francis, C. A.

    2006-12-01

    A combination of recent metagenomic analyses and the cultivation of a novel, ammonia-oxidizing, marine crenarchaeota revealed the first evidence for nitrification within the Archaeal domain. Further genetic and metagenomic studies demonstrated the presence of ammonia-oxidizing crenarchaea in diverse marine and terrestrial environments. These discoveries challenge the currently accepted view of the global nitrogen cycle and validate the need for further research on microbial diversity and function. In particular, it is imperative to reexamine the microbial communities involved in ammonia oxidation in marine and estuarine sediments, where this process plays a pivotal role in the cycling and removal of nitrogen. Using phylogenetic analyses of ammonia monooxygenase subunit A (amoA) gene sequences, we examined the distribution and diversity of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in San Francisco Bay, the largest estuary on the West coast of the United States. The highly impacted bay, encompassing nearly 178,000 km2, effectively connects two estuaries with varying physical-chemical characteristics to the Pacific Ocean. We recovered archaeal and bacterial amoA genes from 11 sites distributed throughout the bay, spanning the northern and southern estuaries and the central region where they connect to the ocean. Richness estimates varied considerably across all sites examined, with archaeal amoA estimates being generally higher than bacterial amoA. Several of the bacterial amoA libraries were represented by fewer than 3 genotypes. Archaeal amoA sequences were phylogenetically diverse and grouped within previously described sediment and soil/sediment clusters. Several sequences were closely related to the only cultivated AOA, Nitrosopumilus maritimus. Both the archaeal and bacterial amoA sequences showed significant regional specificity. Distinct populations exist in the northern and southern estuaries and sequences from the northernmost and southernmost sites

  17. Seismically induced soft-sediment deformation structures in the Palaeogene deposits of the Liaodong Bay Depression in the Bohai Bay basin and their spatial stratigraphic distribution

    Science.gov (United States)

    Liu, Lei; Zhong, Yijiang; Chen, Hongde; Xu, Changgui; Wu, Kui

    2016-08-01

    Soft-sediment deformation structures (SSDS) have been identified from well cores in the Palaeogene deposits of the Liaodong Bay Depression in the Bohai Bay basin, China. These deposits formed as interbedded sand and mud at a delta front or on the slope toe of the prodelta. According to criteria proposed by previous research, we established that these SSDS were induced by earthquakes and that they can be divided into two groups: ductile deformation structures (plastic intrusions, ball-and-pillow structures, flame structures, boudinage structures, irregular convolute stratifications, and synsedimentary faults and folds) and brittle deformation structures (sand dykes and autoclastic breccias). Based on their level of deformation, size, and complexity, the SSDS were divided into three Groups, from weak to strong, to reflect the intensity of palaeo-earthquakes. With consideration of the palaeo-sedimentary environment, we proposed a model to account for the production and preservation of these SSDS. According to the classification adopted in this study and the spatial stratigraphic distribution of the SSDS, the tectonic activities of the Tan-Lu faults in the Bohai Bay basin were investigated. The A and B oilfields (assumed names) are located in the tectonically active zones of the west and east branches of these faults, respectively. The extension tectonic activities in the A oilfield region exhibit a sharply decreasing trend from E2s3 to E2s1, and increase again in E3d2; whereas the strike-slip tectonic activities in the B oilfield region exhibit an increasing trend from E2s3 to E2s1, and finally, reach a maximum to E3d3. The results of this study show that the method of analysis of the spatial stratigraphic distribution of SSDS is suitable for determining the evolution of tectonic activity and thus, it can provide a new perspective for basin analysis.

  18. Determination of PAH sources in dated sediments from Green Bay, Wisconsin, by a chemical mass balance model.

    Science.gov (United States)

    Su, M C; Christensen, E R; Karls, J F

    1998-01-01

    Six sediment cores were collected from Green Bay, Wisconsin, in order to identify possible sources of polycyclic aromatic hydrocarbons (PAHs) by a chemical mass balance (CMB) model. The cores which were obtained in 1995 had total PAH concentrations between 8.04 and 0.460 ppm. 210Pb and 137Cs dating was used to determine historical trends of PAH inputs, and elemental carbon particle analysis was done to characterize particles from combustion of coal, wood and petroleum. The results show that coke burning, highway dust, and wood burning are likely sources of PAHs to Green Bay. The contribution of coke oven emissions (CB) for the Green Bay cores is in the range of 5 to 90%. The overall highway dust (HWY) contribution is between 5 and 70%. There is a maximum (approximately 67%) contribution of HWY around 1988 which is in agreement with the historical US petroleum consumption. The wood burning (WB) contribution is between 1 to 30%, except in core GB-A where a maximum (approximately 50%) is found around 1994. The average relative errors of measurement for x2 equal to the number of degrees of freedom, are 52.5, 56.2, 36.2, 52.3, and 42.8 (df = 3) for the Green Bay cores A, B, C, E, and F, respectively. The sums of the contribution factors are less than one, indicating gain of inert biological or other bulk material between source and receptor. The results of carbon particles for Green Bay core D show that coal, oil, and wood burning are consistent with the CMB modeling results. PMID:15093306

  19. Polybrominated diphenyl ethers in dissolved and suspended phases of seawater and in surface sediment from Jiaozhou Bay, North China.

    Science.gov (United States)

    Ju, Ting; Ge, Wei; Jiang, Tao; Chai, Chao

    2016-07-01

    The concentration and distribution of polybrominated diphenyl ethers (PBDEs) in the dissolved phase (DP) and suspended particulate matter (SPM) of seawater and in surface sediment obtained from Jiaozhou Bay (JZB) were determined. The potential sources of these compounds were evaluated. The total concentrations of 14 PBDEs (∑14PBDE) in DP and SPM were 0.09-1.35 and 1.17-5.45ng/L, respectively, indicating that the PBDE congeners are predominantly partitioned into the SPM fraction. The ∑14PBDE concentrations in sediment ranged from 2.18ng/g to 10.59ng/g with a mean value of 6.59ng/g. BDE-209 was dominant among 14 PBDE congeners, and BDE-47 was another abundant congener in the SPM and sediment samples. The PBDE concentration in SPM showed a significantly positive correlation with chlorophyll a level (r(2)=0.496, pparametric multidimensional scaling ordination showed that BDE-209 and BDE-47 are the important products discriminating PBDE contamination. This result is associated with industrial waste discharge from urban areas and with heavy ship traffic, indicating that DecaBDE and PentaBDE products are the potential sources of PBDEs. PBDE concentrations were lower in the sediment in JZB than in other coastal areas in South China, although the PBDE concentrations in DP were higher than those in some coastal areas worldwide. Moreover, the PBDE concentrations in DP and sediment increased in the last decade. PMID:27037878

  20. Significance of dredging on sediment denitrification in Meiliang Bay, China: A year long simulation study

    Science.gov (United States)

    Zhong, Jicheng; Fan, Chengxin; Zhang, Lu; Edward, Hall; Ding, Shiming; Li, Bao; Liu, Guofeng

    2010-01-01

    An experiment for studying the effects of sediment dredging on denitrification in sediments was carried out through a one-year incubation of undredged (control) and dredged cores in laboratory. Dredging the upper 30 cm of sediment can significantly affect physico-chemical characteristics of sediments. Less degradation of organic matter in the dredged sediments was found during the experiment. Denitrification rates in the sediments were estimated by the acetylene blockage technique, and ranged from 21.6 to 102.7 nmol N2/(g dry weight (dw) x hr) for the undredged sediment and from 6.9 to 26.9 nmol N2/(g dw x hr) for dredged sediments. The denitrification rates in the undredged sediments were markedly higher (p < 0.05) than those in the dredged sediments throughout the incubation, with the exception of February 2006. The importance of various environmental factors on denitrification was assessed, which indicated that denitrification was regulated by temperature. Nitrate was probably the key factor limiting denitrification in both undredged and dredged sediments. Organic carbon played some role in determining the denitrification rates in the dredged sediments, but not in the undredged sediments. Sediment dredging influenced the mineralization of organic matter and denitrification in the sediment; and therefore changed the pattern of inherent cycling of nitrogen.

  1. Dinoflagellate cyst production in Hudson Bay, the world's largest inland sea, based on monthly sediment trap data

    Science.gov (United States)

    Heikkilä, Maija; Pospelova, Vera; Forest, Alexandre; Stern, Gary

    2014-05-01

    Phytoplankters, microscopic primary producers of oceans are capable of responding rapidly to environmental fluctuations due to their high cell replication rates. Fast phytoplankton growth maybe balanced out by equally fast consumption by herbivorous grazers. In high-latitude marine systems, seasonal fluctuations in plankton biomass are essentially linked to light regime controlled by the waxing and waning sea-ice cover. In addition, nutrient limitation in surface waters, seasonal temperature fluctuations and changes in freshwater inputs may play important roles. In cold-water seas, many planktonic organisms cope with seasonal harshness by the production of benthic dormant stages. Dinoflagellates are a diverse group of single-celled plankton, constituting major marine primary producers, as well as herbivorous grazers of the microbial loop. Many dinoflagellate species produce highly resistant, organic-walled resting cysts that are archived in sediments and have been increasingly used to reconstruct past environmental conditions, e.g., sea-surface temperature and salinity, productivity, sea-ice cover and eutrophication. Marine sediment core sequences are characterized by slow accumulation rates and high mixing rates: the top centimeter of surface sediment from an arctic shelf may correspond to several years or decades of deposition. Consequently, sedimentary archives do not give direct information on long-term changes in seasonal bloom patterns or cues of annually recurring life-cycle events. We used two particle-intercepting sediment traps moored in eastern and western Hudson Bay, respectively, to study monthly fluctuations in dinoflagellate cyst production from October 2005 to September 2006. The traps were deployed close to the seafloor and recovered during the ArcticNet annual expeditions onboard the CCGS Amundsen in 2005 and the CCGS Pierre Radisson in 2006. We document the seasonal succession of dinoflagellate cyst taxa, together with cyst species composition

  2. [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. PMID:25898662

  3. RHEOLOGICAL PROPERTIES OF SEDIMENT SUSPENSIONS FROM ECKERNF(O)RDE AND KIELER F(O)RDE BAYS, WESTERN BALTIC SEA

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Local areas of fine-grained organic-rich sediments in Eckernforde and Kieler Forde Bays may experience disturbances which cause fluidization of the substrate and create a dense suspension (fluid mud) which exists temporarily as a component of the benthic boundary layer before becoming incorporated into the permanent bottom. Laboratory studies indicate this material behaves rheologically as a non-Newtonian substance, and both shear thinning (pseudoplastic) and shear thickening (dilatant) flow behavior can occur (often within the same sample) under low to intermediate shear stresses (2 - 40 Pa) and shear rates (0.46 - 122.49 s-1).Detailed granulometric analyses (1/4 phi intervals) of the fraction <63 μm show differences in the silt/clay ratio (clay <2 μm) between the two environments. Little change in the silt/clay ratio is seen in the Kieler Forde sediments (from 0.74 to 0.95); however, at Eckemforde, the ratio changed from0.73 to 2.19. Fine silt particles are lacking or were removed from the 4 to 16 μm fraction of the Eckernforde but not from the Kieler Forde sediments. Both shear thickening and shear thinning flow was observed in the Eckemforde sediments. Shear thickening flow behavior was not observed in the Kieler Forde sediments.Samples of organic-rich (10 to 20%) interface sediments from both areas were analyzed rheologically prior to, and after removal of organic matter by H2O2 treatment. Reduction in 'apparent'viscosity occurred through the entire range of shear rates and stresses, shear thickening behavior was reduced or became nonexistent, and yield stress decreased significantly compared to the natural samples. The differences in yield stress and flow behavior of dense suspensions result primarily from differences in grain size distributions but the role of organic matter on those properties is very significant and adds to the effects of the grain size distribution of the sediment.

  4. Sediment transport and development of banner banks and sandwaves in an extreme tidal system: Upper Bay of Fundy, Canada

    Science.gov (United States)

    Li, Michael Z.; Shaw, John; Todd, Brian J.; Kostylev, Vladimir E.; Wu, Yongsheng

    2014-07-01

    Multibeam sonar mapping and geophysical and geological groundtruth surveys were coupled with tidal current and sediment transport model calculations to investigate the sediment transport and formation processes of the complex seabed features off the Cape Split headland in the upper Bay of Fundy. The Cape Split banner bank, composed of coarse to very coarse sand, is a southwest-northeast oriented, large tear-drop shaped sand body with superimposed sand waves that show wavelengths from 15 to 525 m and heights from 0.5 to 19 m. Isolated and chains of barchan dunes occur on top of a shadow bank to the southeast of the banner bank. The barchan dunes are composed of well-sorted medium sand and are oriented northwest-southeast. Their mean height and width are 1.5 and 55 m, respectively. A gravel bank, with an elongated elliptical shape and west-east orientation, lies in the Minas Passage erosional trough east of the headland to form the counterpart to the sandy Cape Split banner bank. The southern face is featureless but the northern face is covered by gravel megaripples. Tidal model predictions and sediment transport calculations show that the formation of the banner bank and the gravel bank are due to the development of the transient counter-clockwise and clockwise tidal eddies respectively to the west and east of the headland. The formation of barchan dunes is controlled by the nearly unidirectional flow regime in outer Scots Bay. Sand waves on the flanks of the Cape Split banner bank show opposite asymmetry and the barchan dunes are asymmetric to the northeast. The tidal current and sediment transport predictions corroborate bedform asymmetry to show that sand wave migration and net sediment transport is to southwest on the northern flank of the banner bank but to northeast on the southern bank. Long-term migration of the Scots Bay barchan dunes is to the northeast. Spring-condition tidal currents can cause frequent mobilization and high-stage transport over the

  5. Paleoenvironmental records from newly recovered sediment cores at the southeast margin of the Salar de Atacama, Chile

    Science.gov (United States)

    Boutt, D. F.; Munk, L. A.; Hynek, S. A.; Corenthal, L.; Huff, H. A.

    2014-12-01

    A suite of new cores recovered from recent boreholes in the southeastern margin of the Salar de Atacama, Chile span a modern environmental gradient from distal alluvial fans, groundwater discharge marshes, sulfate-rich playas, saline lagoons, and the halite nucleus of the salar. These same environments are preserved as stratigraphic records of environmental change in the cores. Cores from the salar nucleus are dominated by halite, and similarly alluvial cores provide a poor paleoenvironmental record. However, the cores from the transition zone between the salar margin and the halite nucleus document alluvial, lagoonal, and evaporite environments. Cores near the halite nucleus record inter-bedded carbonate, gypsum, and halite. Finely laminated carbonates inter-bedded with cm-thick halite beds are a target for U-series geochronology. Cores near modern lagoons contain 2-6 m thick diatomites in addition to microbially-mediated carbonate, organic-rich mud, and minor alluvium. The uppermost 20 cm of diatomite deposits are commonly rooted with vascular plant material which is being processed for 14C geochronology. Ignimbrite and tephra deposits are also encountered and will provide important chronological control. The presence and absence of the 3.5-4.0 Ma Tucucaro ignimbrite in various cores documents a complex pattern of subsidence near the salar margin, some areas have accumulated little sediment since its deposition while in other areas the cores likely record only late Pleistocene deposition. Preliminary interpretations of the stratigraphic records within a paleohydrologic context are tenable. The specific control on this paleohydrologic record is likely to be a combination of increased inflow due to wetter climates and migration of the freshwater/brine interface which underlies the margins of the Salar de Atacama. Stratigraphic variations in the lithium content of evaporite minerals is being explored as a potential indicator of water balance. Lithium concentrations

  6. Response of suspended sediment concentration to tidal dynamics at a site inside the mouth of an inlet: Jiaozhou Bay (China

    Directory of Open Access Journals (Sweden)

    S. L. Yang

    2004-01-01

    Full Text Available Observations of fair weather currents and suspended sediment concentrations (SSC were made using an acoustic Doppler current profiler and two YSI turbidity sensors over a neap to spring time cycle at a site near the inner mouth of a semi-enclosed mesotidal-macrotidal embayment (Jiaozhou Bay to examine the influence of tidal dynamics on concentration and transport of suspended sediment. During the investigation, SSC varied from about 3 to 16 mg L–1 at the surface and about 6 to 40 mg L–1 close to the bed, while the current velocity reached 79 cm s–1 at the surface and 61 cm s–1 near the bed. SSC was tidally cyclic. The near-bed instantaneous SSC was closely related to current velocity with almost no time lag, indicating that the variability of SSC was governed by current-induced settling/resuspension. At the surface, however, instantaneous SSC was poorly related to instantaneous current velocity because the peak SSC tended to occur around ebb slack water. This suggests that the surface SSC was controlled by horizontal advection from landward higher concentration areas. Both at the surface and near the bed, on the other hand, tidally-averaged SSC was well correlated to tidal range and current speed. Current velocity and SSC were flood-dominated for all the tides investigated, which resulted in significant landward residual suspended sediment transport at the study site. The observed flood dominance was mainly attributed to the location of the study site on the landward side of the bay’s inlet where flow separation is favoured during flood tide. It was concluded that tides are the dominant hydrodynamic component controlling the variability of SSC during fair weather at the study area. Keywords: sediment, concentration, suspension, advection, currents, shoalling effect, Jiaozhou Bay, China

  7. Hydrologic, water-quality, and sediment-quality data for the Christmas Bay system, Brazoria County, Texas, February 1999-March 2000

    Science.gov (United States)

    East, Jeffery W.

    2002-01-01

    The Christmas Bay system is a group of three small secondary bays (Christmas, Bastrop, and Drum Bays) at the southwestern end of the Galveston Bay estuarine system in Brazoria County, Texas. During February 1999-March 2000, hydrologic, water-quality, and sediment-quality data were collected from each of the three bays to establish baseline conditions. Gage-height fluctuations closely matched open-water tidal fluctuations. Rainfall during February 1999-February 2000 was about 20 percent below the annual average. Specific conductance, pH, water temperature, and dissolved oxygen monitored at 30-minute intervals in Christmas Bay for 13 months showed seasonal variations typical of monitoring stations on the Texas Gulf Coast. Prevailing winds were from the southeast. Monthly water-quality sampling for 13 months showed that in each of the three bays concentrations of major ions were small, and most nutrient concentrations were at or less than minimum reporting levels; indicator bacteria counts were consistently higher in samples collected from Drum Bay. Several trace elements (sampled twice) were detected in small concentrations. The only organochlorine pesticides (sampled once) that were greater than minimum reporting levels were atrazine, deethylatrazine, metolachlor, and simazine. During February 29-March 29, 2000, three semipermeable membrane devices were deployed at the Christmas Bay monitoring station. Seven of 77 semivolatile organic compounds analyzed in the lipids from the devices were detected in minute amounts. Analyses of surficial bed sediment sampled once in each of the three bays yielded detections of a number of semivolatile organic compounds; all concentrations were less than 10 micrograms per liter and much less than the respective benchmark concentration for those compounds that have had a benchmark concentration established for the protection of aquatic life.

  8. Carbon sources supporting benthic mineralization in mangrove and adjacent seagrass sediments (Gazi Bay, Kenya)

    OpenAIRE

    BOUILLON, S; Moens, T.; F. Dehairs

    2004-01-01

    The origin of carbon substrates used by in situ sedimentary bacterial communities was investigated in an intertidal mangrove ecosystem and in adjacent seagrass beds in Gazi bay (Kenya) by δ13C analysis of bacteria-specific PLFA (phospholipid fatty acids) and bulk organic carbon. Export of mangrove-derived organic matter to the adjacent seagrass-covered bay was evident from sedimentary total organic carbon (TOC) and δ13CTOC data. PLFA δ13C data indicate tha...

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

    Digital Repository Service at National Institute of Oceanography (India)

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

    diffraction analysis was performed on powdered sediment samples using a Seifert (JSO-DEBYEFLEX 2002) X-ray diffractometer having a curved graphite crystal diffracted monochromator, with a source of CuK� radiation and a NaI (TI) scintillation counter detector... scale, but are not yet used routinely for sediment analysis (Linge, 2008). Mineralogical investigations were generally performed by using X-ray 1 Dr., CSIR–National Institute of Oceanography...

  10. Humic sulfur in eutrophic bay sediments: Characterization by sulfur stable isotopes and K-edge XANES spectroscopy

    Science.gov (United States)

    Zhu, Mao-Xu; Chen, Liang-Jin; Yang, Gui-Peng; Huang, Xiang-Li; Ma, Chen-Yan

    2014-02-01

    Organic sulfur (OS) is an important sedimentary sulfur pool in marine sediments and chemical extractions are often used for quantification of various OS pools, however, OS sources and mechanisms of OS formation are not well understood. In this study, sulfur stable isotope and sulfur X-ray absorption near edge structure (XANES) spectroscopy were combined to investigate the sources and speciation of humic-acid sulfur (HA-S) and fulvic-acid sulfur (FA-S) in sediments of eutrophic Jiaozhou Bay. Whilst there may be some indication that eutrophication has enhanced FA-S burial in the sediment, this has not substantially modified the characteristically low humic sulfur (i.e., HA-S + FA-S) contents of the sediments. Sulfur isotopic compositions indicate that both HA-S and FA-S are mixtures of diagenetic and biosynthetic OS in origin; HA-S is dominated by biosynthetic sulfur and FA-S by diagenetic source. Sulfur isotopic compositions and contents of pyrite and diagenetic OS indicate that inhibition of sulfurization by pyrite formation, if any, appears insignificant. XANES analysis suggests that the contents of high oxidized OS (i.e., sulfones and ester-sulfates) and strongly reduced OS species are comparable in the HA-S, whereas the FA-S is dominated by strongly reduced OS as a result of enhanced sulfurization.

  11. distributions of radioisotopes in sediment cores from nearshore off Xinghua Bay mouth, Fujian, China

    International Nuclear Information System (INIS)

    Radioisotopes-distributions in two sediment cores have been measured. The cores were collected from nearshore off Xinghua Bay mouth in Fujian, China. The core ZK6 was collected at 25021'02'N, 119047'' 15E, near Haitan Island and the length was 300 cm and was sliced into 150 samples at 2 cm interval. The core ZK18 was collected at 25010'14''N, 119037'09''E, near Nanri Island, and the length was 250 cm and was sliced into 116 samples at 2 or 4 cm interval. The upper 0∼170 cm of the core ZK6 is gray silt, and it is darker below depth of 170 cm. The core of ZK18 was gray silt-sand beside it is yellow fine pebbles in the zones of 108∼120 cm and 125∼140 cm. 210Pb activity in ZK6 increase in upper 17 cm with depth and decrease exponentially in the zone of 17-37 cm but increased rapidly from 37 cm to 50 cm, and then exponentially declined with depth in the zone of 50-100 cm. 210Pb is in secular equilibrium with 226Ra below the depth of 100 cm. For core ZK18, 210Pb concentration is comparable within measured error in upper 23 cm and then decline exponentially with depth from 20 cm to 50 cm. 2l0Pb is in secular equilibrium with 226Ra below the depth of 50 cm. Sedimentation rates of two cores have been estimated by the excess 210Pb data of the exponential decline zone. The sedimentation rate of core ZK6 is 0.607 cm/a above 50 cm and 0.737 cm/a below depth of 50 cm. The sedimentation rate of the core ZK18 was 0.179 cm/a. For the core ZK6, the activities of 40K, 137CS, 226Ra, 228Ra, 228Th and 238U are 684- 795, 2.36- 3.60, 22.4- 27.9, 54.4- 71.9, 53.0- 73.2, 28.6- 67.8 Bq/kg and the averages are 734±58, 3.10±0.46, 24.8±1.3, 63.7±2.8, 64.4±4.3 and 42.6±6.3 Bq/kg respectively. The activity of 40K is comparable within measured error in the whole core. The 137CS has been detected only in upper 17 cm and the zone of 52-80 cm. 226Ra, 228Ra and 228Th increase in upper 20 cm and in zone of 60-100 cm, but they decrease in zone of 20-60 cm, the activities of all nuclides are

  12. 210Pb geochronology of stream sediments from the Guama river and Guajara bay, Belem - Amazon Region

    International Nuclear Information System (INIS)

    This study was able to date three sediment profiles collected at the mouth of the Amazon river using the 210Pb geochronology method. All sediment profiles were sliced into layers of 5 cm and each layer was analyzed for radionuclides by Gamma Spectrometry. The results obtained dated the sediments as far back as 65 years. In addition, the sedimentation rate was also determined. A subsequent interpretation of the results can provide information on pollutants present in the sediment layers and infer possible contamination patterns by operating industries and anthropogenic activities in the area of the Amazon Hydrographic Basin. (author)

  13. Coastal circulation and sediment dynamics in Maunalua Bay, Oahu, Hawaii, measurements of waves, currents, temperature, salinity, and turbidity; November 2008-February 2009

    Science.gov (United States)

    Storlazzi, Curt D.; Presto, M. Katherine; Logan, Joshua B.; Field, Michael E.

    2010-01-01

    High-resolution measurements of waves, currents, water levels, temperature, salinity and turbidity were made in Maunalua Bay, southern Oahu, Hawaii, during the 2008-2009 winter to better understand coastal circulation, water-column properties, and sediment dynamics during a range of conditions (trade winds, kona storms, relaxation of trade winds, and south swells). A series of bottom-mounted instrument packages were deployed in water depths of 20 m or less to collect long-term, high-resolution measurements of waves, currents, water levels, temperature, salinity, and turbidity. These data were supplemented with a series of profiles through the water column to characterize the vertical and spatial variability in water-column properties within the bay. These measurements support the ongoing process studies being done as part of the U.S. Geological Survey (USGS) Coastal and Marine Geology Program's Pacific Coral Reef Project; the ultimate goal of these studies is to better understand the transport mechanisms of sediment, larvae, pollutants, and other particles in coral reef settings. Project Objectives The objective of this study was to understand the temporal variations in currents, waves, tides, temperature, salinity and turbidity within a coral-lined embayment that receives periodic discharges of freshwater and sediment from multiple terrestrial sources in the Maunalua Bay. Instrument packages were deployed for a three-month period during the 2008-2009 winter and a series of vertical profiles were collected in November 2008, and again in February 2009, to characterize water-column properties within the bay. Measurements of flow and water-column properties in Maunalua Bay provided insight into the potential fate of terrestrial sediment, nutrient, or contaminant delivered to the marine environment and coral larval transport within the embayment. Such data are useful for providing baseline information for future watershed decisions and for establishing guidelines for

  14. Carbonate Sedimentation Rates Today and in the Past: Holocene of Florida Bay, Bahamas, and Bermuda vs. Upper Jurassic and Lower Cretaceous of the Jura Mountains (Switzerland and France)

    OpenAIRE

    Strasser, André; Samankassou, Elias

    2005-01-01

    Lagoonal to intertidal sediments from the Holocene in Florida Bay, on the Bahamas, and in Bermuda are compared to similar facies in the Kimmeridgian and Berriasian of the Swiss and French Jura Mountains. Dating by 14C permits the estimation of sediment accumulation rates in the Holocene. In the ancient outcrops, the timing is given by cyclostratigraphic analysis. Elementary depositional sequences formed in tune with the 20-ka precession cycle, although much of this time may have been spent in...

  15. Biogeochemistry of sulfur and iron in Thioploca-colonized surface sediments in the upwelling area off central Chile

    DEFF Research Database (Denmark)

    Zopfi, Jakob; Michael E., Böttcher; Jørgensen, Bo Barker

    2008-01-01

    The biogeochemistry of sedimentary sulfur was investigated on the continental shelf off central Chile at water depths between 24 and 88 m under partial influence of an oxygen minimum zone. Dissolved and solid iron and sulfur species, including the sulfur intermediates sulfite, thiosulfate, and el...

  16. 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

  17. Effects of dredging at Aratu port in All Saints Bay, Brazil: monitoring the metal content in water and sediments.

    Science.gov (United States)

    Rocha, T S; Sales, E A; Beretta, M; Oliveira, I B

    2016-07-01

    This work reports the chemical monitoring of saline water and sediments at Aratu port, All Saints Bay, Brazil, when subjected to a deep dragging process (DDP) over a 2-year period (2010-2012). The aim of this work was to detect which metals had possible deleterious effects on the biota. It analyzed percentage of silt + clay and TOC and metal concentrations (As, Cd, Cu, Cr, Ni, Pb, and Zn) before, during, and after the DDP. The determination of metal concentration in sediments used the following techniques: atomic absorption spectrometer with flame, also with hydrate generation, and cold vapor spectrophotometry. The DDP disturbed the concentrations of metals in sediments and water, but 15 months after the DDP, only Cu and Zn were detectable on the bottom saline water, and 20 months after the DDP, only Zn was detectable in water. This fact indicates that these metals were longer available for absorption by the marine biota with probable deleterious effect. Indeed, studies by others during the DDP in Aratu port, indicated the decrease from 50 to 40 of the number of microalgae species identified. On the other hand, in the sediments, 20 months after the DDP, the concentrations of As, Cr, Cu, Pb, and Hg, returned to the original values, but Ni and Zn did not return to their original values. Comparison with studies by others indicated that the sediments from dredging were inappropriate for disposal at sea. This work indicated that the metals Cu, Ni, and Zn are the most deleterious elements to the marine environment. PMID:27270482

  18. An enhanced MODIS remote sensing model for detecting rainfall effects on sediment plume in the coastal waters of Apalachicola Bay.

    Science.gov (United States)

    Chen, Shuisen; Huang, Wenrui; Chen, Weiqi; Chen, Xiuzhi

    2011-12-01

    Mapping of total suspended solids (TSS) was conducted to investigate rainstorm-induced characteristic of sediment plume in the coastal waters of Apalachicola Bay. An improved TSS quadratic polynomial regression model (Calibration: R2=0.8586, N=32; validation: RMSE of 4.76 mg/l, N=30) for MODIS remote sensing was presented in this study. TSS mapping of MODIS before and after a rainstorm event showed distinct temporal-spatial variability of TSS concentration. Driven by ocean tidal current, a storm plume of width at about 40-50 km was formed flowing towards southwest of study area. The distinct boundary separating the highly turbid (west side) and relatively clear water (east side) was found near Sikes Cut. Further, by taking the TSS mapping under the low river discharge condition due to a local rainstorm as a reference of background TSS, two thresholds of TSS (25 and 45 mg/l respectively) were used to estimate the range of rainstorm plume and the central area of sediment load from surrounding land, and the spatial extent and evolution of the sediment plume during the local rainstorm. Besides, it was found that the storm plume concentration of TSS at east side of Sites Cut was quickly diluted under 25 mg/L, forming a storm plume towards east with width at about 7-8 km. The method developed in this study may be used to support coastal storm water research and management activities. PMID:22051796

  19. Comparing sediment quality in Spanish littoral areas affected by acute (Prestige, 2002) and chronic (Bay of Algeciras) oil spills

    International Nuclear Information System (INIS)

    The quality of sediments collected from two areas of the Spanish coast affected by different sources of contaminants has been compared in this study. The areas studied are the coast of Galicia affected by the oil spill from the tanker Prestige (November 2002) and the Gulf of Cadiz which suffers continuous inputs of contaminants from industries located in the area and from oil spills. Contamination by several chemicals (metals, PCBs and PAHs) that bind to sediments was analyzed, and two toxicity tests (Microtox[reg]) and amphipod 10-day bioassay) were conducted. PAHs were identified as the compounds responsible for the toxic effects. Results show differences between an acute impact related to the sinking of the tanker Prestige and the chronic impact associated with continuous oil spills associated with the maritime and industrial activities in the Bay of Algeciras, this being the most polluted part of the two coastal areas studied in this work. - Littoral sediments affected by low or moderated but continuous oil spills are more polluted than those affected by accidental oil spills such as the Prestige

  20. Holocene hydro-environmental changes in northern Mongolia inferred from lacustrine sediments in Borsog Bay of Lake Khuvsgul

    Institute of Scientific and Technical Information of China (English)

    ORKHONSELENGE A; MINO K; KASHIWAYA K; KRIVONOGOV S; YAMAMOTO T; SAKAGUCHI A; NAKAMURA T

    2011-01-01

    A 13-m long sediment core from Borsog Bay of Lake Khuvsgul, northern Mongolia records hydro-environmental changes during the past 10000 years; three rapid environmental changes (ca. 2700 a BP, ca. 6000 a BP and ca. 8000 a BP based on14C dates of organic carbon materials) are detected in depth proifles of sediment physical properties. Temporal changes in the physical properties of the core (grain size, grain density and water content) also suggest three periods of large discharge from outside and three periods of stable input (200~500 cm, 800~980 cm and 1050~1200 cm). The sedimentation rates in the stable period are 0.102 cm·a–1, 0.085 cm·a–1 and 0.139 cm·a–1, respectively. The periods of large discharge likely correspond to the intervals of the three rapid environmental changes, indicating that there were three rapid and high discharge periods related to melt water and/or heavy rainfall during the past 10000 years in this region. The analytical results also show that the physical properties are valuable in reconstructing past hydro-geomorphological lfuctuations in the lake-catchment system.

  1. An investigation of spatial variation of suspended sediment concentration induced by a bay bridge based on Landsat TM and OLI data

    Science.gov (United States)

    Cai, LiNa; Tang, DanLing; Li, CongYing

    2015-07-01

    This study investigates the spatial variation of suspended sediment concentration (SSC) induced by Hangzhou Bay Bridge (HBB) in the coastal waters of the East China Sea. Based on Landsat Thematic Mapper (TM), Operational Land Imager (OLI) data and in-situ measurements, spectral characteristics of waters in Hangzhou Bay and SSC retrieved from near infrared single band have been analyzed. The results revealed significant difference of SSC in the water on two sides of HBB. SSC increases downstream of the bridge under conditions of low turbidity (SSC 400 mg l-1) upstream. This study shows that the interaction of bridge piers and currents has important influences on SSC distribution by inducing hydrodynamic factors and by changing suspended sediment transport. Remotely sensed data with high spatial resolution as TM and OLI can be applied to investigate SSC variations induced by a bridge in the bay area.

  2. Integrated Assessment of Heavy Metal Pollution in the Surface Sediments of the Laizhou Bay and the Coastal Waters of the Zhangzi Island, China: Comparison among Typical Marine Sediment Quality Indices

    OpenAIRE

    Zhuang, Wen; Gao, Xuelu

    2014-01-01

    The total concentrations and chemical forms of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in the surface sediments of the Laizhou Bay and the surrounding marine area of the Zhangzi Island (hereafter referred to as Zhangzi Island for short) were obtained and multiple indices and guidelines were applied to assess their contamination and ecological risks. The sedimentary conditions were fine in both of the two studied areas according to the marine sediment quality of China. Whereas the probable ef...

  3. Three dimensional numerical modeling of Hydrodynamics and sediment transport in the Mississippi River Diversion at West Bay

    Science.gov (United States)

    Sadid, K. M.; Meselhe, E. A.; Roth, B.; Allison, M. A.

    2013-12-01

    The coastal wetlands of Louisiana have been experiencing high rates of land subsidence and erosion for decades. Anthropogenic alterations to the hydrology and geology, powerful hurricanes, and relative sea level rise have caused major coastal land loss in Louisiana. After years of research and discussions, the use of sediment diversions from the Mississippi River to adjacent embayment areas were proposed and further authorized as a solution for land building. To this end, the West Bay diversion (WBD) was constructed in 2003 to restore approximately 9,831 acres of wetlands in the West Bay area under the Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA). The WBD is located along the right-descending bank of the Mississippi River south of Venice, LA near River Mile (RM) 4.7. The initial size of the channel post-construction was designed to convey 20,000 cubic feet per second (cfs), and over time it was anticipated to support a maximum of 50,000 cfs. This sediment diversion provides an opportunity to examine and analyze the impact of such diversion on the morphology of the river channel, and the retention characteristics and rate of delta growth in the receiving basin. Additionally, the WBD serve as analogue to fully validate morphologic models that could consequently be used to model proposed land building sediment diversions in the Lower Mississippi River. In this study a three-dimensional numerical model is developed for the WBD which includes the main channel of the Mississippi River as well as the receiving basin. The model is being calibrated and validated for hydrodynamics and morphology using detailed field observations. Since 2003 regular monitoring has taken place as per the CWPPRA project guidelines. This includes bathymetric surveys of the receiving basin from 2002 (pre-construction), 2003, 2006, and 2009. A recent monitoring survey has been completed and will be available in the near future. In addition to this monitoring data, the U

  4. Seasonal mercury concentrations and δ15N and δ13C values of benthic macroinvertebrates and sediments from a historically polluted estuary in south central Chile

    International Nuclear Information System (INIS)

    The Lenga Estuary is one of the most industrialized sites in south central Chile where the historic operation of chlor-alkali plants resulted in large quantities of mercury (Hg) being deposited into the estuary. This historical contamination may still represent a risk to the biota in the estuary. To investigate this four macroinvertebrates, Neotrypaea uncinata (ghostshrimp), Elminius kingii (barnacle), Hemigrapsus crenulatus (shore crab) and Perinereis gualpensis (ragworm) were collected seasonally from three different sites in the Lenga Estuary and one in a reference estuary (Tubul Estuary), and analyzed for Hg and stable isotopes (δ15N and δ13C). Mercury concentrations in Lenga sediments ranged from 0.4 ± 0.1 to 13 ± 3 mg/kg, while those in Tubul sediments ranged from 0.02 ± 0.01 to 0.07 ± 0.09 mg/kg. Total Hg concentrations of invertebrates were significantly different between estuaries (p 0.05). In contrast, organic Hg concentrations were different by species and season with shore crab muscle tissues exhibiting the greatest percent difference. Site-specific relationships demonstrated that total Hg concentrations in ragworm best reflected the total Hg sediment mercury concentrations. Signatures of δ13C were correlated to the organic Hg % rather than total Hg. This suggests that organic Hg concentrations in these species were related to the carbon sources. -- Highlights: ► Hg in sediments and biota from Lenga Estuary were elevated compared to nearby estuary. ► Invertebrates showed interspecific and seasonal differences in terms of organic Hg %. ► Total Hg levels in the ragworm best reflect Hg sediment gradient in Lenga Estuary. ► Interspecific variation in δ13C signatures indicated different feeding modes. ► Organic forms of Hg in invertebrates were mainly related to the carbon sources.

  5. Recent DDT and PCB contamination in the sediment and biota of the Como Bay (Lake Como, Italy).

    Science.gov (United States)

    Bettinetti, R; Quadroni, S; Boggio, E; Galassi, S

    2016-01-15

    Due to its peculiar geographical and morphological characteristics, Lake Como (Northern Italy) represents an interesting study-case for investigating the sub-basin scale circulation of persistent organic pollutants (POPs) that, despite being banned since the 1970s, have reached surprisingly high concentrations in some southern alpine lakes as a consequence of their release from melting glaciers in recent years. In particular, the Como Bay, which is located in the city of Como, seems noteworthy because its waters have a longer residence time than the other areas of the lake. The analyses of the historical concentration of PCBs, pp′DDT and its metabolites in a sediment core sampled from the Como Bay covering a time-period from their ban to recent times, showed that the DDTs have never experienced a significant (p PCB metabolite hexa-CB (449.7 ng g(-1) w.w. and 1672.1 ng g(-1) w.w. respectively). The DDT concentrations in the agone (sampled during the years 2006–2009) never exceeded the limits for human consumption in Italy, while concentrations of six selected PCBs exceeded human health advisory recommendations in one of the fish samples analysed, when it was approximately two times higher than the recommended value of 125 ng g(-1) w.w. PMID:26520265

  6. Polycyclic aromatic hydrocarbon contamination in coastal sediments of the Izmit Bay (Marmara Sea): case studies before and after the Izmit Earthquake.

    Science.gov (United States)

    Tolun, L; Martens, D; Okay, O S; Schramm, K W

    2006-08-01

    Izmit Bay and its coastal environment was strongly affected by the August 17th, 1999 Izmit Earthquake. The changes in the Bay ecosystem and its chemical oceanography have been studied in detail previously [Okay, O.S., Tolun, L, Telli-Karakoç, F., Tüfekçi, V., Tüfekçi, H. And Morkoç, E. 2001. Yzmit Bay ecosystem after Marmara earthquake and subsequent fire: The long-term data. Marine Pollution Bulletin 42, 361-369; Balkýs, N. 2003. The effect of Marmara (Izmit ) Earthquake on the chemical oceanography of Izmit Bay, Turkey. Marine Pollution Bulletin 46, 865-878.]. In this study surface sediments collected from the Izmit Bay before and after the earthquake have been analysed for total and individual (14 compounds) polycyclic aromatic hydrocarbons (PAH). Analyses have been performed by high performance liquid chromatography with fluorescence detection (HPLC/FD). Before the earthquake, total PAH concentrations in the Bay sediments ranged from 120 to 8900 ng/g while after the earthquake PAH concentrations varied between 240 and 11,400 ng/g. Molecular indices based on isomeric PAH ratios used to differentiate the pollution sources, clearly indicate the differences in molecular distribution of PAHs before and after the earthquake. Sediment data obtained before the earthquake shows that most of the contamination originated from high temperature pyrolytic inputs while after the earthquake it originated from petrogenic sources. This difference emphasises the environmental impact of uncontrolled discharges from petroleum industries after the earthquake. The LMW/HMW ratio (sum of the low molecular weight PAHs / the sum of higher molecular weight PAHs) predominance also changed after the earthquake as a result of the strong water movements. According to the characteristics of aromatic rings distributed in the bay sediments, the soluble parts of the total PAH were probably transferred to the water column after the earthquake as a result of resuspension process. The TEL

  7. Application of 210Pb-derived sedimentation rates and dinoflagellate cyst analyses in understanding Pyrodinium bahamense harmful algal blooms in Manila Bay and Malampaya Sound, Philippines

    International Nuclear Information System (INIS)

    The number of areas affected by toxic harmful algal bloom (HAB) in the Philippines has been increasing since its first recorded occurrence in 1983. Thus far, HAB has been reported in about 20 areas in the Philippines including major fishery production areas. The HAB-causing organism (Pyrodinium bahamense var. compressum) produces a cyst during its life cycle. Pyrodinium cysts which are deposited in the sediment column may play a role in initiating a toxic bloom. 210Pb-derived sedimentation rate studies in the two important fishing grounds of Manila Bay and Malampaya Sound, Palawan have shown that Pyrodinium cysts may have been present in the sediment even before the first recorded toxic algal bloom in these areas. High sedimentation rates (approximately 1 cm/year) have been observed in the Northern and Western parts of Manila Bay. The results indicate that the sedimentation processes occurring in these bays would require subsurface cyst concentration analysis in evaluating the potential of an area to act as sea bed

  8. Non-stationary Concentration-Discharge Relationships for Nitrogen, Phosphorus, and Sediment for Nine Major Tributaries of the Chesapeake Bay

    Science.gov (United States)

    Zhang, Q.; Ball, W. P.

    2015-12-01

    Derived from river water-quality monitoring data, concentration-discharge (C-Q) relationships are a powerful tool for understanding nutrient and sediment dynamics. Here we first present a brief review of C-Q relationships documented in the scientific literature. Major categories of observed relationships for nutrient and sediment include: (a) "dilution" patterns (i.e., negative C-Q relationships), particularly for point-source dominated rivers; and (b) "concentration" patterns (i.e., positive C-Q relationships), particularly for nonpoint-source dominated rivers. In the second part of our work, we present a comprehensive evaluation of riverine C-Q patterns for multiple water-quality constituents for the nine major non-tidal tributaries of the Chesapeake Bay. Specifically, we have analyzed concentration data sets of total nitrogen, nitrate plus nitrite, total phosphorus, dissolved orthophosphate, and suspended sediment for the period between the 1980s and 2015. Separation of the monitoring data into non-overlapping decadal periods revealed clear non-stationarity in C-Q relationships for many of the selected site-constituent combinations. These temporal changes in C-Q relationships generally reflected changes in dominant watershed sources of nutrients and sediment (e.g., reduction in point-source dominance for total nitrogen in the Patuxent River due to technology upgrade at wastewater treatment plants) and are consistent with trends observed in previous research. The findings also highlight the potential pitfalls of assuming stationary C-Q relationships when estimating riverine concentrations and fluxes or analyzing their trends.

  9. The effect of physical and chemical parameters on the macroinfaunal community structure of San Vicente bay, Chile Efectos de parámetros físicos y químicos en la estructura comunitaria de la macroinfauna en la bahía de San Vicente, Chile

    Directory of Open Access Journals (Sweden)

    ROCÍO A. SIEMENS

    2001-06-01

    Full Text Available San Vicente bay is a heavily industrialised bay located in central Chile, which has a sand beach extending from an area of recreational use in the south to an area of industrial use and discharge in the north. A survey of the macrofauna in the intertidal zone revealed a non-homogeneous distribution; a maximum of five invertebrate species were found with all five only occurring in one of six transects down the beach. The density ranged from 0 to 188 individuals m-2, with the highest density at the recreational end. The most common species, Emerita analoga (Stimpson, was chosen to study the macrofaunal response to beach morphodynamics, physicochemical parameters and metal concentrations. The E. analoga distribution was not significantly correlated with the results of the physicochemical analyses of interstitial water (pH, temperature, salinity and oxygen concentrations. However, oxygen concentrations decreased to 3 ml O2 l-1 in the lower intertidal closest to the recreational area where the highest numbers of intertidal macrofauna were observed. Analyses of 12 metals in the sediments showed three distinct distribution patterns across the beach in which the metals could be classified: a representative metal was chosen for each distribution. The concentration of tin ranged from 3.4 to 11.58 mg g-1DW sediment, representing the `wave' pattern. The concentration of cadmium ranged from 0 to 0.23 mg g-1DW sediment, representing the `banded' pattern. The concentration of chromium ranged from 1.97 to 3.18 mg g-1DW sediment, representing the `intermediate' pattern of metal distribution. The E. analoga distribution was not significantly correlated with the concentrations of any single metal, although multivariate statistical analysis indicated that Sn and Fe had the largest negative effect and Mn had the largest positive one. The distribution of E. analoga across the sandy beach of San Vicente bay was significantly correlated with the relative tidal range

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

    Science.gov (United States)

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

    2013-01-01

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

  11. Distribution of radionuclides in a marine sediment core off the waterspout of the nuclear power plants in Daya Bay, northeastern South China Sea

    International Nuclear Information System (INIS)

    A sediment core was collected and dated using 210Pbex 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 137Cs. 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. - Graphical abstract: A sediment core was collected and dated using 210Pbex dating method, off the waterspout of nuclear power base of Daya Bay, northeastern South China Sea. The γ-emitting radionuclides analyzed using the HPGe γ spectrometry, gross alpha and beta radioactivity as well as other geochemical indicators were deliberated to study the past environment changes and assess the impact of nuclear power plants (NPP) operation. NPP provided no new radioactivity source to sediment, but the mass input of cooling water from nuclear power plants may result into a substantial change in the ecological environment and Daya Bay has been severely impacted by human activities. - Highlights: • A sediment core collected from Daya Bay, South China Sea was dated using 210Pbex method. • The γ-emitting radionuclides, gross α and β, TOC, TIC, TC, LOI were deliberated to assess the impact of nuclear power plants (NPP) operation. • The low activity of 137Cs in sediment suggested NPP provided no new radioactivity source. • Two peaks of TOC, TC and LOI implied that the mass input of NPP cooling water may result

  12. Effects Of Sea Otter Colonization On Soft-Sediment Intertidal Prey Assemblages In Glacier Bay, Alaska

    OpenAIRE

    Weitzman, Benjamin Phillip

    2013-01-01

    The influence of sea otters (Enhydra lutris) on nearshore marine communities has been widely studied in kelp-forest ecosystems, however less is known about their impacts in other systems. In Southeast Alaska, the recolonization by sea otters into areas where they have been long absent (~100 years), provides a natural experiment with which to examine the response of soft-substrate intertidal prey communities to the return of a top predator. Sea otter abundance in Glacier Bay, Alaska increase...

  13. Chincoteague Bay surface sediment physical parameters data from the spring and fall sampling trips of 2014

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center conducted a seasonal collection of surficial sediments from...

  14. Pore water studies reef flat sediments, Kaneohe Bay, Oahu, HI (NODC Accession 0000271)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Geochemical behavior of the upper 70 cm of permeable reef flat sediments on Checker Reef, Oahu, Hawaii was examined using spatial and temporal changes in pore water...

  15. Heavy metal determination by X-rays spectrometry in superficial sediments at Havana Bay

    International Nuclear Information System (INIS)

    Havana Bay is a typical bag-type located in the Western-North Coast of the Republic of Cuba. Since 1980 it has been the object of a study for sea bottom rehabilitation and improvement of quality of the waters, where the final objective will be the recovery of the coastal and marine ecosystem. Thirteen surface samples of the Havana Bay (Cuba) were collected and analysed by X-Rays spectrometry. Some majority elements (Si, Ca, K, Na, S, Cl, Al, Fe, Mg, C and O) were measured by scanning electron microscopy (SEM) coupled with microanalysis to perform geomorphologic analysis. Nine elements (Ca, Fe, Ti, Mn, Cu, Zn, Sr, Zr and Pb) have been measured using an Energy Dispersive X-Ray Fluorescence (EDXRF) with a Si(Li) detector. Multivariate statistical was used for the analysis. The concentration levels showed this bay as the most polluted in Cuba. The highest contents of Cu, Zn and Pb were obtained in Atares and Marimelena Cove; these elements are indicators of urban as well as industrial pollution. (author)

  16. Heavy metal determination by X-rays spectrometry in superficial sediments at Havana Bay

    Energy Technology Data Exchange (ETDEWEB)

    Gelen, Alina; Izquierdo, Walter; Lopez, Neivy; Corrales, Yasser; Casanova, Amaya O.; Diaz, Oscar; Manso, Maria V.; D' Alessandro, Katia [Institute for Applied Sciences and Technology, Havana (Cuba)], E-mail: alina@instec.cu; Reyes, Enma; Toledo, Carlos [Central Laboratory Criminology, Havana (Cuba); Beltran, Jesus; Perez, Marlen; Ramirez, Marta [Engineering Centre for Environmental Management of Bays and Coasts, Havana (Cuba)], E-mail: beltran@cimab.transnet.cu; Soto, Jesus [Universidad de Cantabria, Santander (Spain)], E-mail: sotoj@unican.es

    2007-07-01

    Havana Bay is a typical bag-type located in the Western-North Coast of the Republic of Cuba. Since 1980 it has been the object of a study for sea bottom rehabilitation and improvement of quality of the waters, where the final objective will be the recovery of the coastal and marine ecosystem. Thirteen surface samples of the Havana Bay (Cuba) were collected and analysed by X-Rays spectrometry. Some majority elements (Si, Ca, K, Na, S, Cl, Al, Fe, Mg, C and O) were measured by scanning electron microscopy (SEM) coupled with microanalysis to perform geomorphologic analysis. Nine elements (Ca, Fe, Ti, Mn, Cu, Zn, Sr, Zr and Pb) have been measured using an Energy Dispersive X-Ray Fluorescence (EDXRF) with a Si(Li) detector. Multivariate statistical was used for the analysis. The concentration levels showed this bay as the most polluted in Cuba. The highest contents of Cu, Zn and Pb were obtained in Atares and Marimelena Cove; these elements are indicators of urban as well as industrial pollution. (author)

  17. Monsoonal effects on beach and offshore sediments from kalbadevi bay, Ratnagiri, Maharashtra state, India.

    Digital Repository Service at National Institute of Oceanography (India)

    Valsangkar, A.B.; Farnnades, D.

    . KEY WORDS: Beach, Environment, Offshore, Ratnagiri, Season, Sand, Sediment, INTRODUCTION Placer deposits from the coastal and offshore areas of Maharashtra are well known and many workers (Roy, 1958; Siddiquie et al., 1979, 1982, 1984; Gujar, 1985... in Ratnagiri to carry out `Environmental Impact Assessment (EIA) studies for placer mining` under the ‘Capacity Building for Sand Mining, Network Program’ of the Council of Scientific and Industrial Research (CSIR), New Delhi. The beach sediment samples from...

  18. Historical trend in heavy metal pollution in the sediments of Cienfuegos Bay (Cuba), defined by 210Pb and 137Cs geochronology

    International Nuclear Information System (INIS)

    The Bay of Cienfuegos, in the southern central part of Cuba, is an enclosed bay with a surface area of 90 km2 and an average depth of 14 m. It is connected to the Caribbean Sea by a narrow channel 3 km long. The bay is divided in two well defined hydrographic basins, due to the presence of a submerged ridge 1 m below the surface. The Northern basin receives most of the anthropic impact from the sewage outlet of the city, from the industrial area and from the fallout of Damuji and Salado rivers. The Southern basin is subject to a smaller degree of anthropic pollution, originating from the Caonao and Arimao rivers. Part of the Southern basin is a natural park. The Bay represents the most important natural resource in the Cienfuegos province, and the surrounding land has been intensively exploited, but in the last three decades some deleterious ecological signals have been observed in the area: loss of biodiversity, shift in benthic communities, reduction in size and capture levels of commercial marine species, erosion of the coastline. The objective of this study is to investigate the concentration level of heavy metals in the sediments of the Bay, reconstructing their 'depositional history' by using radionuclide geochronology, in order to highlight the major changes occurred in the last century and to draw hypotheses on their origin. In 1999 and 2000, sampling campaigns have been carried out to collect sediment cores (about 1 m long), for investigating the depositional history, and surface sediment for evaluation of the spatial distribution of heavy metals. The samples have been analysed using high-resolution gamma spectrometry for natural and anthropogenic radionuclides, and Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) for heavy metals. The vertical profiles of 137Cs and 210Pbex show that in the last 40 years significant changes have affected sedimentation processes in the bay. Up to 1963, sediment were regularly accumulated, both in the northern and

  19. Variabilidad estacional de cadmio en un sistema de surgencia costera del norte de Chile (Bahía Mejillones del Sur, 23° S Seasonal variability of cadmium in a coastal upwelling system off northern Chile (Mejillones bay, 23° S

    Directory of Open Access Journals (Sweden)

    JORGE VALDÉS

    2006-12-01

    observada en esta razón pueden ser explicados ya sea por una mayor eficiencia en la remoción de PO4 que de Cadmio en las aguas superficiales o una mayor remineralización de cadmio en las aguas subsuperficialesTotal and dissolved cadmium were measured from surface to 100 m water depth, between June 2002 and April 2003, in Mejillones bay. Total and dissolved cadmium range concentration was 0.41-10.7 and 0.08-1.61 nM, respectively. Cadmium profiles and water structure were used to study seasonal variability patterns of this metal in this upwelling system. Oceanographic conditions during this period correspond to a normal (non-El Niño year. Water masses present in this bay correspond to subantartic superficial water, subtropical superficial water and Equatorial subsuperficial water with different degree of mixture and stratification during sampling period. Cadmium profiles showed a classic nutrient-type distribution. Whereas some differences in this profiles could be attributed to a water masses mixing condition into the bay. Multivariate analysis indicates that temporal cadmium variations were associated with chlorophyll-a concentration and temperature fluctuation, indicating that, at this temporal resolution, phytoplanktonic biomass production is the principal factor controlling cadmium concentration in surface waters of Mejillones bay. By other hand, in spite of cadmium being a redox-sensitive metal, any significant influence of dissolved oxygen on this metal were founded, thus microxic condition of bottom water of Mejillones bay is not the principal factor that promotes cadmium flux to the sediments. Cd/PO4 ratio is in agreement with normal values reported for the Chilean coast, and its low values, compared with the northeast Pacific coast, can be explained either by the fact that PO4 is more efficiently removed than cadmium from the surface layer, or that cadmium remineralization is occurring much faster than in the case of PO4

  20. Acute sedimentation response to rainfall following the explosive phase of the 2008-2009 eruption of Chaitén volcano, Chile

    Science.gov (United States)

    Pierson, Thomas C.; Major, Jon J.; Amigo, Álvaro; Moreno, Hugo

    2013-01-01

    The 10-day explosive phase at the start of the 2008–2009 eruption of Chaitén volcano in southern Chile (42.83°S, 72.65°W) blanketed the steep, rain-forest-cloaked, 77-km2 Chaitén River drainage basin with 3 to >100 cm of tephra; predominantly fine to extremely fine rhyolitic ash fell during the latter half of the explosive phase. Rain falling on this ash blanket within days of cessation of major explosive activity generated a hyperconcentrated-flow lahar, followed closely by a complex, multi-day, muddy flood (streamflow bordering on dilute hyperconcentrated flow). Sediment mobilized in this lahar-flood event filled the Chaitén River channel with up to 7 m of sediment, buried the town of Chaitén (10 km downstream of the volcano) in up to 3 m of sediment, and caused the lower 3 km of the channel to avulse through the town. Although neither the nature nor rate of the sedimentation response is unprecedented, they are unusual in several ways: (1) Nearly 70 percent of the aggradation (almost 5 m) in the 50–70-m-wide Chaitén River channel was caused by a lahar, triggered by an estimated 20 mm of rainfall over a span of about 24 h. An additional 2 m of aggradation occurred in the next 24–36 h. (2) Direct damage to the town was accomplished by the sediment-laden water-flood phase of the lahar-flood event, not the lahar phase. (3) The volume of sediment eroded from hillslopes and delivered to the Chaitén River channel was at least 3–8 × 106 m3—roughly 15–40 % of the minimum tephra volume that mantled the Chaitén River drainage basin. (4) The acute sedimentation response to rainfall appears to have been due to the thickness and fineness of the ash blanket (inhibiting infiltration of rain) and the steepness of the basin’s hillslopes. Other possible factors such as the prior formation of an ash crust, development of a hydrophobic surface layer, or large-scale destruction of rain-intercepting vegetation did not play a role.

  1. Heavy metal contaminant remediation study of western Xiamen Bay sediment, China: laboratory bench scale testing results.

    Science.gov (United States)

    Zhang, Luoping; Feng, Huan; Li, Xiaoxia; Ye, Xin; Jing, Youhai; Ouyang, Tong; Yu, Xingtian; Liang, Rongyuan; Chen, Weiqi

    2009-12-15

    A surface sediment sample (decontamination study. A series of laboratory-based experiments under various conditions were performed using chemical complexation reagents (e.g., H2C2O4, EDTA-2Na, etc.) and their combination in order to provide information for sediment remediation technology development. In this study, the results suggest that aeration and agitation of the sediment samples in distilled-deionized water (DDW) have either no or weak (metal removal, whereas agitation, aeration and rotation of the samples in chemical complexation solutions yield much better metal removal efficiency (up to 90%). A low pH condition (e.g., pHmetal removal efficiency. The experimental results suggest that 0.20 M (NH4)2C2O4+0.025 M EDTA combination with solid:liquid ratio=1:50 and 0.50 M ammonium acetate (NH4Ac)+0.025 M EDTA combination with solid:liquid ratio=1:50 are the most effective methods for metal removal from the contaminated sediments. This research provides additional useful information for sediment metal remediation technology development. PMID:19631459

  2. Environmental magnetic and geochemical characteristics of Chennai coastal sediments, Bay of Bengal, India

    Indian Academy of Sciences (India)

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

    2011-10-01

    In this study, environmental magnetic, heavy metal and statistical analyses were conducted on 21 surface sediments collected from Chennai coast, India, to examine the feasibility of heavy metal pollution using magnetic susceptibility. The Chennai coastal sediment samples are dominated by ferrimagnetic minerals corresponding to magnetite-like minerals. The percentage of frequency dependent magnetic susceptibility reflects the presence of super-paramagnetic/single domain magnetic minerals in Chennai harbour, Cooum and Adayar rivers sediments. High pollution load index in sample E1, E2, CH7, C11, C12 and A16 is mainly due to anthropogenic activities such as, harbour activities, Cooum and Adayar rivers input and industrial effluent. Factor analysis shows that the magnetic concentration dependent parameters (, ARM and SIRM) covary with the heavy metal concentrations, suggesting that the input of magnetic minerals and heavy metals in Chennai coastal sediments are derived from the same anthropogenic sources. Strong correlation obtained between pollution load index (PLI) and concentration dependent parameters (, ARM and SIRM) for the polluted samples with magnetic susceptibility excess of 50 × 10−8 m3kg−1. Significant correlations between heavy metals and magnetic susceptibility point out the potential of magnetic screening/monitoring for simple and rapid proxy indicator of heavy metal pollution in marine sediments.

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

    Science.gov (United States)

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

    2012-01-01

    The U.S. Geological Survey (USGS) updates information on loads of, and trends in, nutrients and sediment annually to help the Chesapeake Bay Program (CBP) investigators assess progress toward improving water-quality conditions in the Chesapeake Bay and its watershed. CBP scientists and managers have worked since 1983 to improve water quality in the bay. In 2010, the U.S. Environmental Protection Agency (USEPA) established a Total Maximum Daily Load (TMDL) for the Chesapeake Bay. The TMDL specifies nutrient and sediment load allocations that need to be achieved in the watershed to improve dissolved oxygen, water-clarity, and chlorophyll conditions in the bay. The USEPA, USGS, and state and local jurisdictions in the watershed operate a CBP nontidal water-quality monitoring network and associated database that are used to update load and trend information to help assess progress toward reducing nutrient and sediment inputs to the bay. Data collected from the CBP nontidal network were used to estimate loads and trends for two time periods: a long-term period (1985-2010) at 31 "primary" sites (with storm sampling) and a 10-year period (2001-10) at 33 primary sites and 16 "secondary" sites (without storm sampling). In addition, loads at 64 primary sites were estimated for the period 2006 to 2010. Results indicate improving flow-adjusted trends for nitrogen and phosphorus for 1985 to 2010 at most of the sites in the network. For nitrogen, 21 of the 31 sites showed downward (improving) trends, whereas 2 sites showed upward (degrading) trends, and 8 sites showed no trends. The results for phosphorus were similar: 22 sites showed improving trends, 4 sites showed degrading trends, and 5 sites indicated no trends. For sediment, no trend was found at 40 percent of the sites, with 10 sites showing improving trends and 8 sites showing degrading trends. The USGS, working with CBP partners, developed a new water-quality indicator that combines the results of the 10-year trend

  4. Wave Energy Converter (WEC) Array Effects on Wave Current and Sediment Circulation: Monterey Bay CA.

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Jesse D.; Jones, Craig; Magalen, Jason

    2014-09-01

    The goal s of this study were to develop tools to quantitatively characterize environments where wave energy converter ( WEC ) devices may be installed and to assess e ffects on hydrodynamics and lo cal sediment transport. A large hypothetical WEC array was investigated using wave, hydrodynamic, and sediment transport models and site - specific average and storm conditions as input. The results indicated that there were significant changes in sediment s izes adjacent to and in the lee of the WEC array due to reduced wave energy. The circulation in the lee of the array was also altered; more intense onshore currents were generated in the lee of the WECs . In general, the storm case and the average case show ed the same qualitative patterns suggesting that these trends would be maintained throughout the year. The framework developed here can be used to design more efficient arrays while minimizing impacts on nearshore environmen ts.

  5. Concentrations and compositions of organochlorine contaminants in sediments, soils, crustaceans, fishes and birds collected from Lake Tai, Hangzhou Bay and Shanghai city region, China

    International Nuclear Information System (INIS)

    Contamination by persistent organochlorines (OCs), such as DDTs, hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs), hexachlorobenzene (HCB) and polychlorinated biphenyls (PCBs) were examined in sediments, soils, fishes, crustaceans, birds, and aquaculture feed from Lake Tai, Hangzhou Bay, and in the vicinity of Shanghai city in China during 2000 and 2001. OCs were detected in all samples analyzed, and DDT and its metabolites were the predominant contaminants in most sediments, soils and biota. Concentrations of p,p'-DDT and ratio of p,p'-DDT to ΣDDTs were significantly higher in marine fishes than those in freshwater fishes. While the use of DDTs has been officially banned in China since 1983, these results indicate a recent input of technical DDTs into the marine environment around Hangzhou Bay. Comparison of organochlorine concentrations in fishes collected from Lake Tai and Hangzhou Bay suggests the presence of local sources of HCHs, chlordanes and PCBs at Lake Tai. Higher proportions of penta- and hexa-PCB congeners in fishes at Lake Tai may suggest the use of highly chlorinated PCB product, such as PCB5, around this lake. To our knowledge, this is a first comprehensive study to examine the present status of organochlorine contamination in various environmental media, such as sediments, soils and wildlife, in China. - Elevated concentrations of DDTs were detected in sediments, soils, and wildlife collected from China

  6. Using GOCI Retrieval Data to Initialize and Validate a Sediment Transport Model for Monitoring Diurnal Variation of SSC in Hangzhou Bay, China

    Directory of Open Access Journals (Sweden)

    Xuefei Yang

    2016-03-01

    Full Text Available The diurnal variation of the suspended sediment concentration (SSC in Hangzhou Bay, China has been investigated using remotely-sensed SSC derived from the Geostationary Ocean Color Imager (GOCI in combination with a coupled hydrodynamic-ecological model for regional and shelf seas (COHERENS. The SSC maps were inferred through a UV-AC atmospheric correction algorithm and an empirical inversion algorithm from the GOCI Level-1B data. The sediment transport model was initialized from maps of the GOCI-derived SSC and the model results were validated through a comparison with remotely-sensed data. The comparison demonstrated that the model results agreed well with the observations. The relationship between SSC distribution and hydrodynamic conditions was analyzed to investigate the sediment transport dynamics. The model’s results indicate that the action of tidal currents dominate the sediment deposition and re-suspension in the coastal waters of the East China Sea. This is especially the case in Hangzhou Bay where the tidal currents are strongest. The satellite-derived sediment data product can not only dramatically improve the specification of the initial conditions for the sediment model, but can also provide valuable information for the model validation, thereby improving the model’s overall performance.

  7. Diffusion of Nitrogen and Phosphorus Across the Sediment-Water Interface and In Seawater at Aquaculture Areas of Daya Bay, China

    Science.gov (United States)

    Cheng, Xiangju; Zeng, Yingxue; Guo, Zhenren; Zhu, Liangsheng

    2014-01-01

    With the yearly increasing marine culture activities in floating cages in Daya Bay, China, the effects of pollution may overlap and lead to more severe water environmental problems. In order to track the impacts of the marine culture in floating cages on water environment, sediments and overlying water were sampled by cylindrical samplers at three representative aquaculture areas of Daya Bay. The water content, porosity, density of sediments as well as the vertical distributions of ammonia nitrogen and active phosphate in pore water along sediments depth were measured. The release rate and annual released quantity of the nutrients across sediment-water interface were calculated using Fick’s Law. A horizontal two-dimensional mathematical model was developed to compute the spatial and temporal distributions of the nutrients in seawater after being released across the sediment-water interface. The results showed that the sediments, with a high content and a large annual released quantity of nitrogen and phosphorus, constitute a potential inner source of seawater pollution. Influenced by tide and water depth, the scope of diffusion and migration of the nutrients appears as a long belt which is about 1 km long and 50 m wide. Seawater in this area is vulnerable to eutrophication. PMID:24477216

  8. Nitrogen cycling in a deep ocean margin sediment (Sagami Bay, Japan)

    DEFF Research Database (Denmark)

    Glud, Ronnie Nøhr; Thamdrup, C.; Stahl, H; Wenzhofer, F.; Glud, A.; Nomaki, H.; Oguri, K.; Revsbech, N. P.; Kitazato, H.

    2009-01-01

    On the basis of in situ NO3- microprofiles and chamber incubations complemented by laboratory-based assessments of anammox and denitrification we evaluate the nitrogen turnover of an ocean margin sediment at 1450-m water depth. In situ NO3- profiles horizontally separated by 12 mm reflected highl...... significant N sinks and play an important role in regional N budgets....

  9. Assessing diversity and phytoremediation potential of mangroves for copper contaminated sediments in Subic Bay, Philippines

    Science.gov (United States)

    Toxic metal pollution of water and soil is a major environmental problem and most conventional remediation approaches may not provide adequate solutions. An alternative way of reducing copper (Cu) concentration from contaminated sediments is through phytoremediation. Presently, there are few researc...

  10. Time series current meter and other data from moorings in the North Atlantic in support of the Current and Sediment Transport in Buzzards Bay Field program from 05 July 1982 to 05 December 1985 (NODC Accession 0056730)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A field experiment designed to determine the near-bottom circulation in Buzzards Bay and the transport of fine-grained sediments. The transport of fine-grained...

  11. The use of a Cs-137 vertical migration model to study the temporal evolution of heavy metals in coastal sediments of the Bay of Cadiz (Spain)

    International Nuclear Information System (INIS)

    The evolution of heavy metals (Zn, Cd, Pb, Hg) in sea bed sediments of the Bay of Cadiz (Spain) has been studied. Four sediment cores were collected from the Inner Bay zone where sediment textural composition is mainly formed by silt and clay with high organic content, showing a very high absorption capacity for the substances solved in the aquatic medium. The dating of the sediments has been performed using the fallout radionuclide 137Cs as a tracer. Due to the high vertical mobility of this radionuclide in the sediment column, as a consequence of its molecular diffusion and the bioturbation existing in the area, the observed profiles are continuous and the 1963 maximum in fallout activity could not be assigned. The one dimensional diffusion-advection equation has been applied, considering the residence time of the radionuclide in the marshes zone, to develop a model that permits to interpret the profiles and to estimate the sedimentation rate, in order to infer the recent chronology of the sediment layers. By using the 210Pb dating method with the CRS model in one station, it can be showed that the sedimentation rate could be assumed to be constant during a longer period of time. In consequence, the sediment dating has been extended up to 100 years backwards, allowing the study of the evolution of heavy metals during the last century. The sediment dating shows that the heavy metal pollution of the Inner Bay has been produced simultaneously in the whole zone, during the industrial development of the environment. The increase of heavy metals Zn and Cd started in the second half of the XX century, while the enhancement of Pb and Hg concentration started at the beginning of the XX century. Heavy metal concentrations reached maximum levels during the eighties decade, afterward a remarkable decrease in surface sediments has been observed, which could be attributed to the restrictive environmental measurements undertaken at the zone, in particular the control of

  12. Recording of the Holocene sediment infilling in a confined tide-dominated estuary: the bay of Brest (Britanny, France)

    Science.gov (United States)

    Gregoire, Gwendoline; Le Roy, Pascal; Ehrhold, Axel; Jouet, Gwenael; Garlan, Thierry

    2016-04-01

    Modern estuaries constitute key areas for the preservation of sedimentary deposits related to the Holocene period. Several previous studies using stratigraphic reconstructions in such environments allowed to characterise the major parameters controlling the Holocene transgressive sequence and to decipher their respective role in the sedimentary infill: (1) the evolution of main hydrologic factors (wave or tide-dominated environment), (2) the sea level fluctuation and (3) the morphologies of the bedrock and the coastline. Nevertheless, the timing of the transgressive deposits and the detailed facies need to be precise in regard to the stratigraphic schemes. The Bay of Brest (Western Brittany, France) offers the opportunity to examine these points and to compare with previous studies. It constitutes an original tide-dominated estuary that communicates to the open sea (Iroise Sea) by a narrow strait. Two main rivers (Aulne and Elorn) are connected to a submerged paleovalleys network that was incised in the Paleozoic basement during lowstands and still preserved in the present morphology. It delineates the central basin surrounded by tidal flat located in sheltered area. The analysis of high and very-high resolution seismic lines recorded through the whole bay combined with sediment cores (up to 4.5 m long) and radiocarbon dating allow to precise the architecture and the timing of the thick Holocene coastal wedge. It is preserved from the valley network to the shore and presents a longitudinal variability (downstream-upstream evolution). The infill is divided into two successive stages (corresponding to the transgressive and highstand system tracts) which laterally evolve from the paleo-valley to the coast. Two units constitute the transgressive system tract. The oldest, dated from 8200 to 7000 cal B.P. is composed of fine-grained, organic-rich tidal flat deposits located in the sheltered area and organised in levees on the terrace bordering the paleo-valley. A tidal

  13. Sediment quality of the SW coastal Laizhou Bay, Bohai Sea, China: a comprehensive assessment based on the analysis of heavy metals.

    Directory of Open Access Journals (Sweden)

    Xuelu Gao

    Full Text Available Historically, the Bohai Sea is one of the most important fishing grounds in China. Yet, surrounded by one of the biggest economic rims of China, its ecological functions have been declining rapidly in recent two decades under the heavy anthropogenic impacts. The Laizhou Bay is the smallest one of the three main bays in the Bohai Sea. Owing to the rich brine deposits, chemical industries using brine as raw materials are booming in the southern coast of the Laizhou Bay, the scale of which ranks as the largest one in China. In order to monitor and assess the environmental quality, surface sediments were collected from the coastal waters of southwestern Laizhou Bay and the rivers it connects with during summer and autumn in 2012, and analyzed for heavy metals. Several widely adopted methods were used in the overall assessment of heavy metal pollution status and potential ecological risks in these sediments, and the data were analyzed to infer the main sources of the pollutants. The results showed that the remarkably high concentrations of heavy metals were almost all recorded in a small number of riverine sites. Cr, Cu, Ni and Zn were the main environmental threat according to the sediment quality guidelines. The marine area was generally in good condition with no or low risk from the studied metals and adverse effects on biota could hardly occur. Natural sources dominated the concentrations and distributions of Cu, Ni, Pb and Zn in the marine area. Our results indicated that heavy metal pollution was not a main cause of the ecological degradation of the Laizhou Bay at present.

  14. Effects of environmental regulations on heavy metal pollution decline in core sediments from Manila Bay

    International Nuclear Information System (INIS)

    We investigated the high-resolution heavy metal pollution history of Manila Bay using heavy metal concentrations and Pb isotope ratios together with 210Pb dating to find out the effects of environmental regulations after the 1990s. Our results suggested that the rate of decline in heavy metal pollution increased dramatically from the end of the 1990s due to stricter environmental regulations, Administrative Order No. 42, being enforced by the Philippines government. The presented data and methodology should form the basis for future monitoring, leading to pollution control, and to the generation of preventive measures at the pollution source for the maintenance of environmental quality in the coastal metropolitan city of Manila. Although this is the first report of a reduction in pollution in Asian developing country, our results suggest that we can expect to find similar signs of pollution decline in other parts of the world as well.

  15. Plankton Resting Stages in the Marine Sediments of the Bay of Vlorë (Albania)

    OpenAIRE

    Fernando Rubino; Salvatore Moscatello; Manuela Belmonte; Gianmarco Ingrosso; Genuario Belmonte

    2013-01-01

    In the frame of the INTERREG III CISM project, sediment cores were collected at 2 stations in the Gulf of Vlorë to study the plankton resting stage assemblages. A total of 87 morphotypes were identified and produced by Dinophyta, Ciliophora, Rotifera, and Crustacea. In 22 cases, the cyst belonged to a species absent from the plankton of the same period. The most abundant resting stages were those produced by Scrippsiella species (Dinophyta). Some calcareous cysts were identified as fossil spe...

  16. Studies on distribution of natural radionuclides in sediments of Osaka Bay and climatic history, 1

    International Nuclear Information System (INIS)

    Drilling core samples were taken at 5 km off the Senshu coast, where construction of Kansai International Airport is prearranged, for geological survey of the submarine strata by the third harbour bureau of the ministry of transportation. We examined a drilling core sample of about 100 m in length in the concentration of the uranium series nuclides (238U, 226Ra, 210Pb,), thorium series nuclides (228Ra,) and 40K, and mineral composition and ignition loss. Our data obtained were compared with the results that were achieved in geological survey by Nakaseko et al. A high 238U content related to high calcite content was observed in sediment deposited during a temperate period, such as a several thousand years before the present and a high 40K content was also observed in sediments for a period of cold climate. It was confirmed that a curve expressed activity ratios of 210Pb to 238U in sediments as a function of year can be applied for a chronology of around ten thousand years before the present. (author)

  17. 杭州湾湾口水体含沙量的时空分布%Spaciai-temporai distribution of suspended sediment concentration in Hangzhou Bay

    Institute of Scientific and Technical Information of China (English)

    吴明阳; 许家帅; 冯玉林

    2011-01-01

    利用卫星遥感资料,结合现场实测数据,研究杭州湾湾口水体含沙量的时空分布,综合分析得出:杭州湾水体含沙量具有冬大夏小、高浓度悬沙广泛分布的特性,岛屿效应引起的局部高含沙是杭州湾岛屿群的共性.%Based on the information from the satelite remote sensing image and the measured SSC data from the field stations, this paper studies the spacial-temporal distribution of the sediment concentration in the Hangzhou Bay. The SSC of the Hangzhou Bay is high in winter and low in summer and the high SSC distributes extensively in the bay. It is common in the Hangzhou Bay that the locally high sediment concentration is caused by the archipelago effect.

  18. Distributions and fate of chlorinated pesticides, biomarkers and polycyclic aromatic hydrocarbons in sediments along a contamination gradient from a point-source in San Francisco Bay, California

    Science.gov (United States)

    Pereira, W.E.; Hostettler, F.D.; Rapp, J.B.

    1996-01-01

    The distribution and fate of chlorinated pesticides, biomarkers, and polycyclic aromatic hydrocarbons (PAHs) in surficial sediments along a contamination gradient in the Lauritzen Canal and Richmond Harbor in San Francisco Bay was investigated. Compounds were identified and quantified using gas chromatography-ion trap mass spectrometry. Biomarkers and PAHs were derived primarily from weathered petroleum. DDT was reductively dechlorinated under anoxic conditions to DDD and several minor degradation products, DDMU, DDMS, and DDNU. Under aerobic conditions, DDT was dehydrochlorinated to DDE and DBP. Aerobic degradation of DDT was diminished or inhibited in zones of high concentration, and increased significantly in zones of lower concentration: Other chlorinated pesticides identified in sediment included dieldrin and chlordane isomers. Multivariate analysis of the distributions of the DDTs suggested that there are probably two sources of DDD. In addition, DDE and DDMU are probably formed by similar mechanisms, i.e. dehydrochlorination. A steep concentration gradient existed from the Canal to the Outer Richmond Harbor, but higher levels of DDD than those found in the remainder of the Bay indicated that these contaminants are transported on particulates and colloidal organic matter from this source into San Francisco Bay. Chlorinated pesticides and PAHs may pose a potential problem to biota in San Francisco Bay.

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

    Science.gov (United States)

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

    2014-02-01

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

  20. Palaeoceanographic implications of abundance and mean proloculus diameter of benthic foraminiferal species Epistominella exigua in sub-surface sediments from distal Bay of Bengal fan

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.; Nigam, R.; Barreto, L.

    from the distal Bay of Bengal fan sediments, to infer past bottom water conditions (figure 1). 2. Epistominella exigua Epistominella exigua is a trochospirally coiled, calcareous species with smooth surface (Murray 1991). E. exigua is a sporadically... J and Giese M 1995 Deep-sea foraminifera in the South Atlantic Ocean: Eco- logy and assemblage generation; Mar. Micropaleontol. 41 342–358. Murray J W 1991 Ecology and Paleoecology of Benthic Foraminifera. John Wiley, New York and Longman Sci...

  1. Detection and mapping of the iron ore occurrence in the sea floor sediments in the coastal zone of the Sepetiba Bay. Rio de Janeiro. Brasil

    International Nuclear Information System (INIS)

    This work is about the detection and mapping of the iron occurrence in the sea floor sediments in the coastal zone of the Sepetiba Bay. Rio de Janeiro. Brasil. The results of geochemical analysis revealed that the area around the mangrove forest located near the Itacuruca channel, the perpendicular direction to the Muriqui Yacht Club channel and the immediate vicinity of the the Guaiba Island Terminal were respectively the areas of highest iron ore concentration

  2. Diversity, Abundance, and Spatial Distribution of Sediment Ammonia-Oxidizing Betaproteobacteria in Response to Environmental Gradients and Coastal Eutrophication in Jiaozhou Bay, China▿ †

    OpenAIRE

    Dang, Hongyue; Li, Jing; Chen, Ruipeng; Lin WANG; Guo, Lizhong; Zhang, Zhinan; Martin G Klotz

    2010-01-01

    Ongoing anthropogenic eutrophication of Jiaozhou Bay offers an opportunity to study the influence of human activity on bacterial communities that drive biogeochemical cycling. Nitrification in coastal waters appears to be a sensitive indicator of environmental change, suggesting that function and structure of the microbial nitrifying community may be associated closely with environmental conditions. In the current study, the amoA gene was used to unravel the relationship between sediment aero...

  3. Gas exchange rates across the sediment-water and air-water interfaces in south San Francisco Bay

    Science.gov (United States)

    Hartman, Blayne; Hammond, Douglas E.

    1984-01-01

    Radon 222 concentrations in the water and sedimentary columns and radon exchange rates across the sediment-water and air-water interfaces have been measured in a section of south San Francisco Bay. Two independent methods have been used to determine sediment-water exchange rates, and the annual averages of these methods agree within the uncertainty of the determinations, about 20%. The annual average of benthic fluxes from shoal areas is nearly a factor of 2 greater than fluxes from the channel areas. Fluxes from the shoal and channel areas exceed those expected from simple molecular diffusion by factors of 4 and 2, respectively, apparently due to macrofaunal irrigation. Values of the gas transfer coefficient for radon exchange across the air-water interface were determined by constructing a radon mass balance for the water column and by direct measurement using floating chambers. The chamber method appears to yield results which are too high. Transfer coefficients computed using the mass balance method range from 0.4 m/day to 1.8 m/day, with a 6-year average of 1.0 m/day. Gas exchange is linearly dependent upon wind speed over a wind speed range of 3.2–6.4 m/s, but shows no dependence upon current velocity. Gas transfer coefficients predicted from an empirical relationship between gas exchange rates and wind speed observed in lakes and the oceans are within 30% of the coefficients determined from the radon mass balance and are considerably more accurate than coefficients predicted from theoretical gas exchange models.

  4. Gas exchange rates across the sediment-water andd air-water interfaces in south San Francisco Bay

    International Nuclear Information System (INIS)

    Radon 222 concentrations in the water and sedimentary columns and radon exchange rates across the sediment-water and air-water interfaces have been measured in a section of south San Francisco Bay. Two independent methods have been used to determine sediment-water exchange rates, and the annual averages of these methods agree within the uncertainity of the determinations, about 20%. The annual average of bethic fluxes from shoal areas is nearly a factor of 2 greater than fluxes from the channel areas. Fluxes from the shoal and channel areas exceed those expected from simple molecular diffusion by factors of 4 and 2, respectively, apparently due to macrofaunal irrigation. Values of the gas transfer coefficient for radon exchange across the air-water inteface were determined by constructing a radon mass balance for the water column and by direct measurement using floating chambers. The chamber method appears to yield results which are too high. Transfer coefficients computed using the mass balance method range from 0.4 m/day to 1.8 m/day, with a 6-year average of 1.0 m/day. Gas exchange is linearly dependent upon wind speed over a wind speed range of 3.2--6.4 m/s, but shows no dependence upon current velocity. Gas transfer coefficients predicted from an empirical relationship between gas exchange rates and wind speed observed in lakes and the oceans are within 30% of the coefficients determined from the radon mass balance and are considerably more accurate than coefficients predicted from theoretical gas exchange models

  5. Environmental control on anaerobic oxidation of methane in the gassy sediments of Eckernforde Bay (German Baltic)

    DEFF Research Database (Denmark)

    Treude, T.; Kruger, M.; Boetius, A.;

    2005-01-01

    and March. Field rates of AOM and sulfate reduction (SR) were measured with radiotracer methods. Additional parameters were determined that potentially influence AOM, i.e., temperature, salinity, methane, sulfate, and chlorophyll a. Methanogenesis as well as potential rates of AOM and aerobic...... oxidation of methane were measured in vitro. AOM changed seasonally within the upper 20 cm of the sediment, with rates being between 1 and 14 nmol cm(-3) d(-1). Its distribution is suggested to be controlled by oxygen and sulfate penetration, temperature, as well as methane supply, leading to a shallow AOM...

  6. The pore water chemistry of sup(239,240)Pu and 137Cs on sediments of Buzzards Bay, Massachusetts

    International Nuclear Information System (INIS)

    The collection of large volumes of pore water and low level radiochemical measurements of sup(239,240)Pu and 137Cs have been combined to produce the first study of these fallout artificial radionuclides in marine pore waters. Profiles from box cores taken in June and September 1982 from Buzzards Bay, Mass., are reported along with profiles of many diagenetic constituents (i.e. SO42-, alkalinity, Fe, Mn, DOC, and nutrients). The sup(239,240)Pu pore water profile is characterized by a subsurface maximum of about 0.28 dpm/100 kg lying between 3 to 11 cm. Overlying seawater, in contrast, has an activity of 0.01 +- 0.02 dpm/100 kg. Below about 11 cm, the pore water sup(239,240)Pu distribution follows that of the solid phase which decreases rapidly with depth. The pore water profiles of 137Cs are characterized by a broad and deeply penetrating maximum where activities of about 35 to 40 dpm/100 kg extend from 3 to 20 cm. Overlying seawater, in contrast, has an activity of 17 to 24 dpm/100 kg. The 137Cs and sup(239,240)Pu pore water data show that there is preferential downward transport of 137Cs and that sup(239,240)Pu does not have an active diagenetic chemistry and is not significantly mobile in these coastal sediments. (author)

  7. Comparing sediment equilibrium partitioning and passive sampling techniques to estimate benthic biota PCDD/F concentrations in Newark Bay, New Jersey (U.S.A.)

    International Nuclear Information System (INIS)

    Sediment and polyethylene sampler-based estimates of polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) concentrations in Newark Bay, New Jersey (USA) benthic biota were compared. Biota concentrations based on sediment were estimated using an organic carbon (OC)-water partitioning model and an OC and black carbon (BC)-water dual model. Biota concentrations based on polyethylene were estimated from samplers deployed in the Newark Bay water column and samplers immersed in a sediment/porewater slurry in the laboratory. Porewater samplers provided the best estimates of biota concentrations (within 3.1×), with best results achieved for deposit-feeders (within 1.6×). Polyethylene deployed in deep water also provided good estimates of biota concentrations (within 4×). By contrast, OC-water partitioning overestimated biota concentrations by up to 7×, while OC and BC combined underestimated biota concentrations by up to 13×. We recommend passive samplers such as polyethylene for estimating concentrations of hydrophobic organic contaminants in field biota given its simplicity and relatively lower uncertainty compared to sediment equilibrium partitioning. -- Highlights: • PE samplers accurately estimate Newark Bay biota PCDD/F concentrations. • A traditional KOC partitioning model overestimated PCDD/F uptake by a factor of 4–7. • A dual KOC and KBC model underestimated biota PCDD/F uptake by a factor of 4–13. • Sediment- and depth-specific KBCs improved predictions of PCDD/F uptake. • Deposit feeder uptake switches from porewater control to ingestion at log KOW 6–7. -- Using polyethylene samplers to measure porewater concentrations is a more efficient approach for estimating site-specific bioavailable organic contaminants than equilibrium partitioning

  8. The impact of urban expansion and agricultural legacies on trace metal accumulation in fluvial and lacustrine sediments of the lower Chesapeake Bay basin, USA.

    Science.gov (United States)

    Coxon, T M; Odhiambo, B K; Giancarlo, L C

    2016-10-15

    The progressively declining ecological condition of the Chesapeake Bay is attributed to the influx of contaminants associated with sediment loads supplied by its largest tributaries. The continued urban expansion in the suburbs of Virginia cities, modern agricultural activities in the Shenandoah Valley, the anthropogenic and climate driven changes in fluvial system hydrodynamics and their potential associated impacts on trace metals enrichment in the bay's tributaries necessitate constant environmental monitoring of these important water bodies. Eight (210)Pb and (137)Cs dated sediment cores and seventy two sediment grab samples were used to analyze the spatial and temporal distributions of Al, Ca, Mg, Cr, Cd, As, Se, Pb, Cu, Zn, Mn, and Fe in the waterways of the Virginia portion of the Chesapeake Bay basin. The sediment cores for trace metal historical fluctuation analysis were obtained in lower fluvial-estuarine environments and reservoirs in the upper reaches of the basin. The trace metal profiles revealed high basal enrichment factors (EF) of between 0.05 and 40.24, which are interpreted to represent early nineteenth century agricultural activity and primary resource extraction. Surficial enrichment factors on both cores and surface grab samples ranged from 0.01 (Cu) to 1421 (Cd), with Pb, Cu, Zn, and Cd enrichments a plausible consequence of modern urban expansion and industrial development along major transportation corridors. Contemporary surficial enrichments of As, Se, and Cr also ranged between 0 and 137, with the higher values likely influenced by lithological and atmospheric sources. Pearson correlation analyses suggest mining and agricultural legacies, coupled with aerosol deposition, are responsible for high metal concentrations in western lakes and headwater reaches of fluvial systems, while metal accumulation in estuarine reaches of the major rivers can be attributed to urban effluence and the remobilization of legacy sediments. PMID:27310532

  9. Application of Constant Rate of Supply model (CRS) in dating of Guanabara Bay sediments using 210Pb measures

    International Nuclear Information System (INIS)

    A geochronological study of the Guanabara Bay (Rio de Janeiro, Brazil) based on 210Pb dating technique to determine sedimentation rates and using the Constant Rate of Supply model (CRS) is presented in this work. Sediment samples were collected from river-head of Estrela, Sao Joao de Meriti, Guapimirim, Guaxindiba e Imbuacu. A low energy gamma spectrometry (210Pb, samples taken from the Estrela and Sao Joao de Meriti rivers. Radiochemical method was applied to determine the amount of 210Pb in samples collected near Guapimirim, Guaxindiba and Imbuacu Rivers. Atomic absorption spectrometry with air-acetylene flame technique was used to determine the amount of copper in all these samples. Experimental data shown the following variation in the concentration levels of copper and 210Pb: (i) copper; from 2.5 μg/g to 37.1 μg/g (Imbuacu River); from 3.6 to 228.1 μg/g (Estrela River); from 11.6 to 73.4 μg/g (Guapimirim River); from 12.0 to 52.9 μg/g (Guaxindiba River) and from 90.8 to to 237.7 μg/g (Sao Joao de Meriti River), (ti) 210Pb; from 2.0 Bq/kg to 27.0 Bq/kg (Imbuacu River); from 25.2 to 136.6 Bq/kg (Estrela River); from 40.0 to 90.0 Bq/kg (Sao Joao de Meriti River); from 7.0 to 70.0 Bq/kg (Guapimirim River); from 10.0 to 48.0 Bq/kg (Guaxindiba River). The sedimentation rates ranged from 0.30 cm/y in the Imbuacu River for a depth below of 35 cm to 1.3 cm/y for 0-30 cm depth in Guaxindiba River. It was concluded that the experimental data found in this work are consistent with those published in the scientific literature and that they can be predicted by the CRS model. (author)

  10. Manganese, Iron, and Sulfur Cycling in a Coastal Marine Sediment, Aarhus Bay, Denmark

    DEFF Research Database (Denmark)

    THAMDRUP, B.; FOSSING, H.; JØRGENSEN, BB

    1994-01-01

    . All of the estimated Mn reduction could be coupled to the reoxidation of reduced S and Fe. Partial oxidation of H2S, forming S0 and pyrite, accounted for 63% of the estimated Fe reduction. The remaining Fe reduction was coupled to complete oxidation of reduced S or to C mineralization. The settling of...... a diatom spring bloom caused distinct maxima in SRR and Mn2+ at 0.5-1 cm depth within two weeks. In autumn, the reactive Mn oxides were depleted due to a net release of Mn2+ to the water column. Thus, the Mn cycle extended significantly into the water column, while a constant Fe pool over the year...... suggests that the Fe cycle was restricted to the sediment....

  11. A 22,000 14C year BP sediment and pollen record of climate change from Laguna Miscanti (23°S), northern Chile

    Science.gov (United States)

    Grosjean, M.; van Leeuwen, J. F. N.; van der Knaap, W. O.; Geyh, M. A.; Ammann, B.; Tanner, W.; Messerli, B.; Núñez, L. A.; Valero-Garcés, B. L.; Veit, H.

    2001-02-01

    Lake sediments and pollen, spores and algae from the high-elevation endorheic Laguna Miscanti (22°45'S, 67°45'W, 4140 m a.s.l., 13.5 km 2 water surface, 10 m deep) in the Atacama Desert of northern Chile provide information about abrupt and high amplitude changes in effective moisture. Although the lack of terrestrial organic macrofossils and the presence of a significant 14C reservoir effect make radiocarbon dating of lake sediments very difficult, we propose the following palaeoenvironmental history. An initial shallow freshwater lake (ca. 22,000 14C years BP) disappeared during the extremely dry conditions of the Last Glacial Maximum (LGM; 18,000 14C years BP). That section is devoid of pollen. The late-glacial lake transgression started around 12,000 14C years BP, peaked in two phases between ca. 11,000 and <9000 14C years BP, and terminated around 8000 14C years BP. Effective moisture increased more than three times compared to modern conditions (˜200 mm precipitation), and a relatively dense terrestrial vegetation was established. Very shallow hypersaline lacustrine conditions prevailed during the mid-Holocene until ca. 3600 14C years BP. However, numerous drying and wetting cycles suggest frequent changes in moisture, maybe even individual storms during the mid-Holocene. After several humid spells, modern conditions were reached at ca. 3000 14C years BP. Comparison between limnogeological data and pollen of terrestrial plants suggest century-scale response lags. Relatively constant concentrations of long-distance transported pollen from lowlands east of the Andes suggest similar atmospheric circulation patterns (mainly tropical summer rainfall) throughout the entire period of time. These findings compare favorably with other regional paleoenvironmental data.

  12. Deposition of the 2011-2012 Cordón Caulle tephra (Chile, 40°S) in lake sediments: Implications for tephrochronology and volcanology

    Science.gov (United States)

    Bertrand, Sébastien; Daga, Romina; Bedert, Robin; Fontijn, Karen

    2014-12-01

    Tephras preserved in lake sediments are commonly used to synchronize sedimentary archives of climate and environmental change and to correlate them with terrestrial environments. They also provide opportunities to reconstruct volcanic explosive activity, e.g., eruption frequency and tephra dispersal. Although sedimentary processes may affect the record of tephras in lakes, lake sediments are generally considered as one of the best archives of tephra stratigraphy. The 2011-2012 eruption of Cordón Caulle volcano (Chile, 40°S) offered an ideal opportunity to study the processes affecting tephra deposition in lakes. Although the prevailing westerlies transported the erupted pyroclastic material away from nearby Puyehue Lake, the tephra was identified within this relatively large lake with a thickness ranging from 1 to >10 cm. This is in contrast with smaller lakes, where tephra thickness was in agreement with ashfall distribution maps. Geomorphological observations and sedimentological analyses provide evidence that the tephra deposited in Puyehue Lake entirely consists of material reworked from the upper watershed, transported by rivers, and distributed by lake currents according to particle size and density. Our results have important implications for tephrochronology and volcanology. They suggest that (1) lakes do not act as passive tephra traps; (2) lakes with large watersheds record more eruptions than smaller lakes, which only register direct ashfalls, affecting conclusions regarding the recurrence of volcanic eruptions; and (3) using lakes with large watersheds for isopach mapping systematically leads to an overestimation of erupted tephra volumes. Smaller lakes with limited drainage basins are generally better suited for volcanological studies.

  13. Soil erosion and sedimentation rates in a small eutrophic lake in southern Chile estimated by 210Pb isotope analysis

    International Nuclear Information System (INIS)

    The purpose of this research is to study the effects of historical land use patterns on soil erosion within the San Pedro Lake watershed (Concepcion, VIII Region, Chile). To this end, a geochronological reconstruction of the last 50 years was accomplished by 210Pb isotope and photo-interpretation analysis through the use of GIS. The erosion rate has varied from 0.40 t ha-1 y-1 in 1955 to 0.86 t ha-1 y-1 in 1994. The decrease in native forest was closely coupled with the increase in exotic forestry. The Total Change, meaning the land use change without considering each typology, shows a constant trend indicating a greater degree of anthropogenic intervention. As opposed to the expected, there is no relationship between land use typologies and erosion rates, however it is possible to recognise some degree of dependency between Total Change and erosion values. It is concluded that over the last 50 years the soil erosion processes in the San Pedro Lake watershed may have been more regulated more by land use changes than by land use typologies themselves. (author)

  14. Distribution of chemical elements in calc-alkaline igneous rocks, soils, sediments and tailings deposits in northern central Chile

    Science.gov (United States)

    Oyarzún, Jorge; Oyarzun, Roberto; Lillo, Javier; Higueras, Pablo; Maturana, Hugo; Oyarzún, Ricardo

    2016-08-01

    This study follows the paths of 32 chemical elements in the arid to semi-arid realm of the western Andes, between 27° and 33° S, a region hosting important ore deposits and mining operations. The study encompasses igneous rocks, soils, river and stream sediments, and tailings deposits. The chemical elements have been grouped according to the Goldschmidt classification, and their concentrations in each compartment are confronted with their expected contents for different rock types based on geochemical affinities and the geologic and metallogenic setting. Also, the element behavior during rock weathering and fluvial transport is here interpreted in terms of the ionic potentials and solubility products. The results highlight the similarity between the chemical composition of the andesites and that of the average Continental Crust, except for the higher V and Mn contents of the former, and their depletion in Mg, Ni, and Cr. The geochemical behavior of the elements in the different compartments (rocks, soils, sediments and tailings) is highly consistent with the mobility expected from their ionic potentials, their sulfates and carbonates solubility products, and their affinities for Fe and Mn hydroxides. From an environmental perspective, the low solubility of Cu, Zn, and Pb due to climatic, chemical, and mineralogical factors reduces the pollution risks related to their high to extremely high contents in source materials (e.g., rocks, altered zones, tailings). Besides, the complex oxyanions of arsenic get bound by colloidal particles of Fe-hydroxides and oxyhydroxides (e.g., goethite), thus becoming incorporated to the fine sediment fraction in the stream sediments.

  15. The Kara Bogaz Gol Bay, Lake Issyk Kul and Aral Sea sediments as archives of climate change in the Aral-Caspian catchment basin

    International Nuclear Information System (INIS)

    A 5-m long core of bottom sediments from the Kara Bogaz Gol Bay of the Caspian Sea, 4- m and 2-m cores from the Issyk Kul Lake of the Thian Shan Mountains, and a 4-m core from the Aral Sea were examined for evidence of climatic and environmental changes in the catchment basin of the Central Asia Region. The distribution of 18O and 13C in the bulk carbonates, 2H in the pore water, radiocarbon age, oxygen and hydrogen isotopes in the lake water, abundance of CaCO3, MgCO3, and the basic salt ions of Na+, K+, Cl-, SO42- in the cores were measured. The isotope and hydrogeochemical data of the Kara Bogaz Gol Bay sediments prove a historical scenario for the basin which suggests that fresh water has been discharged to the Caspian Sea during the Bay's humid episode across the Central Asia Region (∼ 9 Ka BP). Isotope and geochemical evidence indicate that the sedimentation of the upper core segment has taken place during the last ∼2.2 Ka BP in the environment of sea water recharged from the Central Caspian Basin. The period of between 4.3 and 6 Ka BP, which relates to the core depth interval of between 170 cm and 260 cm, demonstrates the most dramatic change in the sedimentation rate in the Issyk Kul Lake. It means that active melting of the mountain glaciers and warming of climate has happened just in this period. The swamp plant peat layers at depths of 230 cm and 130 cm indicate that during 3.5-3.7 Ka BP and 1.6-1.8 Ka BP the Aral Sea dried and broke up into a number of lakes and swamps. Sediment cores taken from the bottom of the Kara Bogaz Gol Bay, Lake Issyk Kul and Aral Sea show periodic rise and fall in water levels during the last ∼10 000 years. Two peat layers within the sediment core of the Aral Sea and dated at 1.6-1.8 Ka BP and 3.5-3.7 Ka BP demonstrate that this reservoir also periodically dried. (author)

  16. Oxygenation variability off Northern Chile during the last two centuries

    Directory of Open Access Journals (Sweden)

    J. A. Díaz-Ochoa

    2010-07-01

    Full Text Available The Peru Chile Current ecosystem is characterized by high biological productivity and important fisheries. Although this system is likely to be severely affected by climate change, its response to current global warming is still uncertain. In this paper we analyze 10–166 year old sediments in two cores collected in Mejillones Bay, an anoxic sedimentary setting favorable for preservation of proxies. Based on a 166 year chronology we used indicators of bottom water oxygenation proxies (Mo, V, S, and the (lycopane+n-C35/n-C31 ratio and surface water productivity (biogenic opal, counts of diatom valves, biogenic Ba, organic carbon and chlorins to reconstruct environmental variations in Mejillones Bay. We find that at decadal scales, and during the last two centuries, a shift in the coastal marine ecosystem off Northern Chile took place which was characterized by intense ENSO-like activity and large fluctuations in biological export productivity, in bottom water oxygenation, and increased eolic activity (inferred from Ti/Al and Zr/Al. On top of this short-term variability, a gradual increase of sulfidic conditions has occurred being even more intensified since the early 1960s.

  17. Microbial Diversity in Sediment Ecosystems (Evaporites Domes, Microbial Mats, and Crusts) of Hypersaline Laguna Tebenquiche, Salar de Atacama, Chile

    Science.gov (United States)

    Fernandez, Ana B.; Rasuk, Maria C.; Visscher, Pieter T.; Contreras, Manuel; Novoa, Fernando; Poire, Daniel G.; Patterson, Molly M.; Ventosa, Antonio; Farias, Maria E.

    2016-01-01

    We combined nucleic acid-based molecular methods, biogeochemical measurements, and physicochemical characteristics to investigate microbial sedimentary ecosystems of Laguna Tebenquiche, Atacama Desert, Chile. Molecular diversity, and biogeochemistry of hypersaline microbial mats, rhizome-associated concretions, and an endoevaporite were compared with: The V4 hypervariable region of the 16S rRNA gene was amplified by pyrosequencing to analyze the total microbial diversity (i.e., bacteria and archaea) in bulk samples, and in addition, in detail on a millimeter scale in one microbial mat and in one evaporite. Archaea were more abundant than bacteria. Euryarchaeota was one of the most abundant phyla in all samples, and particularly dominant (97% of total diversity) in the most lithified ecosystem, the evaporite. Most of the euryarchaeal OTUs could be assigned to the class Halobacteria or anaerobic and methanogenic archaea. Planctomycetes potentially also play a key role in mats and rhizome-associated concretions, notably the aerobic organoheterotroph members of the class Phycisphaerae. In addition to cyanobacteria, members of Chromatiales and possibly the candidate family Chlorotrichaceae contributed to photosynthetic carbon fixation. Other abundant uncultured taxa such as the candidate division MSBL1, the uncultured MBGB, and the phylum Acetothermia potentially play an important metabolic role in these ecosystems. Lithifying microbial mats contained calcium carbonate precipitates, whereas endoevoporites consisted of gypsum, and halite. Biogeochemical measurements revealed that based on depth profiles of O2 and sulfide, metabolic activities were much higher in the non-lithifying mat (peaking in the least lithified systems) than in lithifying mats with the lowest activity in endoevaporites. This trend in decreasing microbial activity reflects the increase in salinity, which may play an important role in the biodiversity. PMID:27597845

  18. Benthic community structure in the Gorgan Bay (Southeast of the Caspian Sea, Iran: Correlation to water physiochemical factors and heavy metal concentration of sediment

    Directory of Open Access Journals (Sweden)

    Mahmood Saghali

    2013-11-01

    Full Text Available Macrobentos frequency and biomass was investigated in the Gorgan Bay in 2011. Five sampling sites were chosen to collect benthos and sediment from the Bay using a Van Veen grab sampler. Samples were collected seasonally. Macrobenthos were indentified and their biomass was recorded. Sediment heavy metals concentration were measured using Atomic Absorption Spectroscopy. A total of 11 families belonging to three phyla of invertebrates were found. The phyla were Annelids (Nereidae, Naididae, Ampharetidae, Lumbriculidae, Tubificidae and Amphiporidae, Arthropods (Pontogammaridae, Balanidae and Chironomidae and Mollusks (Cardiidae and Scrobicularidae. Lumbriculidae (413 individuals m-2, corresponding to 18.7% and Cardiidae (55.2 g m-2, corresponding to 82.4% had the highest frequency and biomass, respectively. Annelids with an average of 1557 individuals m-2 was the most frequent groups, while, mollusks with the average of 141 g per m2 had the highest biomass. Results showed that macrobenthos frequency in summer was significantly higher than those of the other seasons, however, in the case of biomass, there was a significantly higher biomass in the spring than the other seasons. The maximum metal concentration was related to Zn and Pb, whereas, Cr and Cd had the lowest values. There was no significant difference in Zn and Cr concentrations among the sampling seasons. Pb concentration in winter was significantly lower than the other seasons, whereas, Cd concentrations in the spring and summer were significantly lower than the autumn and winter. There were some correlations between benthos frequency and water physiochemical characteristics and sediment heavy metal levels. This study indicated that benthic fauna of the Gorgan Bay and the Caspian Sea are not similar. Also, results showed that benthic fauna communities are affected by sediment heavy metal concentrations and water physiochemical characteristics, however, different benthos groups show

  19. Multivariate Analyses and Evaluation of Heavy Metals by Chemometric BCR Sequential Extraction Method in Surface Sediments from Lingdingyang Bay, South China

    Directory of Open Access Journals (Sweden)

    Linglong Cao

    2015-04-01

    Full Text Available Sediments in estuary areas are recognized as the ultimate reservoirs for numerous contaminants, e.g., toxic metals. Multivariate analyses by chemometric evaluation were performed to classify metal ions (Cu, Zn, As, Cr, Pb, Ni and Cd in superficial sediments from Lingdingyang Bay and to determine whether or not there were potential contamination risks based on the BCR sequential extraction scheme. The results revealed that Cd was mainly in acid-soluble form with an average of 75.99% of its total contents and thus of high potential availability, indicating significant anthropogenic sources, while Cr, As, Ni were enriched in the residual fraction which could be considered as the safest ingredients to the environment. According to the proportion of secondary to primary phases (KRSP, Cd had the highest bioavailable fraction and represented high or very high risk, followed by Pb and Cu with medium risks in most of samples. The combined evaluation of the Pollution Load Index (PLI and the mean Effect Range Median Quotient (mERM-Q highlighted that the greatest potential environmental risk area was in the northwest of Lingdingyang Bay. Almost all of the sediments had a 21% probability of toxicity. Additionally, Principal Component Analysis (PCA revealed that the survey region was significantly affected by two main sources of anthropogenic contributions: PC1 showed increased loadings of variables in acid-soluble and reducible fractions that were consistent with the input from industrial wastes (such as manufacturing, metallurgy, chemical industry and domestic sewages; PC2 was characterized by increased loadings of variables in residual fraction that could be attributed to leaching and weathering of parent rocks. The results obtained demonstrated the need for appropriate remediation measures to alleviate soil pollution problem due to the more aggregation of potentially risky metals. Therefore, it is of crucial significance to implement the targeted

  20. Bacterial Enzymatic Activity and Bioavailability of Heavy Metals in Sediments from Boa Viagem Beach (Guanabara Bay

    Directory of Open Access Journals (Sweden)

    Mirian Crapez

    2003-01-01

    Full Text Available This study focuses on the quality of the organic matter that reaches the sediment from Boa Viagem Beach and through the evaluation of the total bacterial count, the electron transport system activity (ETSA, the esterase activity (EST, as well as the protein and the organic matter contents. Seasonal variations of organic matter, protein content and the number of bacteria were particularly notable in the summer. ETSA reached a maximum of 7.48 µl O 2 h-1 g-1 in the summer. EST activity presented a different pattern once it reached a maximum of 0.17 µg fluorescein h-1 g-1 in the winter. The temporal variation of ETSA and EST activity indicated that biopolymers predominated in the winter, and oligomers or monomers predominated in the summer. These results suggest that organic carbon turnover is more likely to be controlled by organic matter quality. The heavy metals concentrations, especially for Cu, Zn, Ni and Cr, indicated absence of the inhibition of dehydrogenase activity, and they are not bioavailable in the EC 50 values

  1. Coastal Circulation and Sediment Dynamics in Hanalei Bay, Kaua'i, Part IV, Measurements of Waves, Currents, Temperature, Salinity, and Turbidity, June-September 2006

    Science.gov (United States)

    Storlazzi, Curt D.; Presto, M. Katherine; Logan, Joshua B.; Field, Michael E.

    2008-01-01

    High-resolution measurements of waves, currents, water levels, temperature, salinity and turbidity were made in Hanalei Bay, northern Kaua'i, Hawai'i, during the summer of 2006 to better understand coastal circulation, sediment dynamics, and the potential impact of a river flood in a coral reef-lined embayment during quiescent summer conditions. A series of bottommounted instrument packages were deployed in water depths of 10 m or less to collect long-term, high-resolution measurements of waves, currents, water levels, temperature, salinity, and turbidity. These data were supplemented with a series of profiles through the water column to characterize the vertical and spatial variability in water column properties within the bay. These measurements support the ongoing process studies being conducted as part of the U.S. Geological Survey (USGS) Coastal and Marine Geology Program's Pacific Coral Reef Project; the ultimate goal is to better understand the transport mechanisms of sediment, larvae, pollutants, and other particles in coral reef settings. Information regarding the USGS study conducted in Hanalei Bay during the 2005 summer is available in Storlazzi and others (2006), Draut and others (2006) and Carr and others (2006). This report, the last part in a series, describes data acquisition, processing, and analysis for the 2006 summer data set.

  2. Contribution of hydrodynamic conditions during shallow water stages to the sediment balance on a tidal flat: Mont-Saint-Michel Bay, Normandy, France

    Science.gov (United States)

    Desguée, R.; Robin, N.; Gluard, L.; Monfort, O.; Anthony, E. J.; Levoy, F.

    2011-10-01

    Field measurements were conducted in Mont-Saint-Michel Bay, a megatidal embayment (spring tidal range of 15 m), in order to monitor, over the course of a tidal cycle, sediment transport variability due to waves and tides on the upper part of a tidal flat characterised by shallow water depths. Sensors used to measure currents, water depth and turbidity were installed just above the bed (0.04 m). Two experiments were conducted under contrasting hydrodynamic conditions. The results highlight wave activity over the tidal flat even though observed wind waves were largely dissipated due to the very shallow water depths. Very high suspended sediment concentrations (up to 6 kg/m 3) were recorded in the presence of wave activity at the beginning of the local flood, when significant sediment transport occurred, up to 7 times as much as under conditions of no wave activity. This influence may be attributed to the direct action of waves on bed sediments, to wave-induced liquefaction, and to the erosive action of waves on tidal channel banks. The sediment composition, comprising a clay fraction of 2-5%, may also enhance sediment transport by reducing critical shear stress through the sand lubrication effect. The results also show that antecedent meteorological conditions play an important role in suspended sediment transport on the tidal flat. Total sediment flux directions show a net transport towards the inner part of the bay that contributes to deposition over the adjacent salt marshes, and this tendency also prevails during strong wave conditions. Such sediment transport is characterised by significant variability over the course of the tidal cycle. During fair and moderate weather conditions, 83% and 71% of the total flux was observed, respectively, over only 11% and 28% of the duration of the local tidal cycle and with water depths between 0.04 and 0.3 m. These results suggest that in order to improve our understanding of sediment budgets in this type of coastal

  3. Shoreline changes in Concón and Algarrobo bays, central Chile, using an adjustment model Cambios en la línea litoral de las bahías de Algarrobo y Concón, Chile central, a través de un modelo de ajuste

    Directory of Open Access Journals (Sweden)

    Carolina Martinez

    2007-11-01

    Full Text Available Adjustment models for both Algarrobo and Concón bays, central Chile, are presented herein; the results show a nearly logarithmic spiral shape for the shore. Spatial-temporal variations in the shorelines of both bays were found based on aerial photographs from different years. The results indicate important variations in the relative position of the Concón Bay shoreline between 1945 and 2006, with extreme oscillations (-368 to 123.8 m only occurring in the proximal zone, where the Aconcagua Estuary is located. On the other hand, the spatial-temporal variations in the Algarrobo Bay shoreline between 1967 and 2006 are moderate (131 in the proximal and -73 in the distal zone. Whereas Concón Bay exhibits a stable state of equilibrium for the past 60 years, if the estuary zone is excluded, Algarrobo Bay presents a stable state with a tendency for growth in the proximal zone and retreat in the distal zone. The results are discussed in terms of coastal changes associated with highly urbanized shorelines and applications for coastal area management that are derived from the modelsSe presentan los resultados de la aplicación de un modelo de ajuste para las bahías de Algarrobo y Concón en Chile central, cuya forma se aproxima a una espiral logarítmica. A partir del uso de fotografías aéreas correspondientes a diferentes años, se determinaron las variaciones espacio-temporales de la línea litoral en ambas bahías. Los resultados indican que la bahía de Concón ha presentado importantes variaciones en la posición relativa de su línea litoral para el período 1945 a 2006, únicamente en su zona proximal, lugar en donde se localiza el estuario Aconcagua con oscilaciones extremas entre -368 m y 123,8 m. En la bahía de Algarrobo, las variaciones espacio-temporales de la línea litoral son de magnitud moderada para el período comprendido entre 1967 y 2006, presentando valores extremos de 131 m en la zona proximal y de -73 m en la zona distal

  4. Examining (239+240)Pu, (210)Pb and historical events to determine carbon, nitrogen and phosphorus burial in mangrove sediments of Moreton Bay, Australia.

    Science.gov (United States)

    Sanders, Christian J; Santos, Isaac R; Maher, Damien T; Breithaupt, Joshua L; Smoak, Joseph M; Ketterer, Michael; Call, Mitchell; Sanders, Luciana; Eyre, Bradley D

    2016-01-01

    Two sediment cores were collected in a mangrove forest to construct geochronologies for the previous century using natural and anthropogenic radionuclide tracers. Both sediment cores were dated using (239+240)Pu global fallout signatures as well as (210)Pb, applying both the Constant Initial Concentration (CIC) and the Constant Rate of Supply (CRS) models. The (239+240)Pu and CIC model are interpreted as having comparable sediment accretion rates (SAR) below an apparent mixed region in the upper ∼5 to 10 cm. In contrast, the CRS dating method shows high sediment accretion rates in the uppermost intervals, which is substantially reduced over the lower intervals of the 100-year record. A local anthropogenic nutrient signal is reflected in the high total phosphorus (TP) concentration in younger sediments. The carbon/nitrogen molar ratios and δ(15)N values further support a local anthropogenic nutrient enrichment signal. The origin of these signals is likely the treated sewage discharge to Moreton Bay which began in the early 1970s. While the (239+240)Pu and CIC models can only produce rates averaged over the intervals of interest within the profile, the (210)Pb CRS model identifies elevated rates of sediment accretion, organic carbon (OC), nitrogen (N), and TP burial from 2000 to 2013. From 1920 to 2000, the three dating methods provide similar OC, N and TP burial rates, ∼150, 10 and 2 g m(-2) year(-1), respectively, which are comparable to global averages. PMID:26004816

  5. Residues of Polychlorinated Biphenyls (PCBs) in Sediment from CauBay River and Their Impacts on Agricultural Soil, Human Health Risk in KieuKy Area, Vietnam.

    Science.gov (United States)

    Toan, Vu Duc; Quy, Nguyen Phuong

    2015-08-01

    An evaluation of the PCB residues from CauBay River and KieuKy area, Vietnam was carried out. CauBay River has been playing an important role in irrigated water supply for agriculture activities at KieuKy area in the downstream. The PCBs concentrations of sediment, soil samples were analyzed and obtained results indicated the wide extent of contamination of PCBs in CauBay River (from 30.74 to 167.35 ng g(-1) dry weight) and KieuKy area (from 21.62 to 60.22 ng g(-1) dry weight). This clearly reflected the effect of PCB residues from CauBay River to the quality of agricultural soil of the KieuKy area. The PCBs composition analyses in the samples reflect their long-time release. The total cancer risk of PCBs in the soil of KieuKy fell into the very low range suggesting low risk. However, since PCBs were the species of POPs with more concern in this area, ecological risk assessment should be further investigated. PMID:26088763

  6. Sediment profile image data from October 1994 in Lower Bay of New York/New Jersey Harbor

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sediment profile images (SPI) of the sediment-water interface were collected using a sediment profiling camera at pre-determined locations in the harbor. Physical,...

  7. Sediment profile image data from October 1995 in the inland bays of New York/New Jersey Harbor

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sediment profile images (SPI) of the sediment-water interface were collected using a sediment profiling camera at pre-determined locations in the harbor. Physical,...

  8. Measurement of pollution levels of organochlorine and organophosphorus pesticides in water, soil, sediment, and shrimp to identify possible impacts on shrimp production at Jiquilisco Bay.

    Science.gov (United States)

    Nomen, Rosa; Sempere, Julià; Chávez, Francisco; de López, Nelly Amaya; Rovira, Ma Dolores

    2012-09-01

    This study aims to identify levels of several organochlorine and organophosphorus compounds in shrimp-raising areas of coastal El Salvador, to assess potential impacts on shrimp growth and survival that hamper the sustainability of aquaculture in the region. The paper reports the current levels of γ-HCH, 4,4'-DDT, 4,4'-DDE, 4,4'-DDD, endrin, dieldrin, heptachlor, parathion, methyl parathion, and etoprophos in soils (depth 20 cm), sediments (depth 5 cm), shrimp (Penaeus sp.), and water of three rearing ponds and also in the sediment (depth 5 cm) and water surrounding those ponds in Jiquilisco Bay. Sampling was carried out during the dry (January-March) and rainy (June-August) seasons of 2008. The presence of pesticides in the samples of water, shrimp, and sediment at shrimp ponds was not detected in either season; however, in soil samples (depth 20 cm) taken from these ponds, heptachlor, endrin, dieldrin, 4,4'-DDD, and 4,4'-DDT were identified at concentrations below the method limit of quantification (LOQ), and 4,4'-DDE was found in a concentration falling in the range from 3.85 to 19.61 ng/g. In samples of water taken at the bay water intakes to the rearing ponds, we observed dieldrin concentrations in the range between 0.085 ng/mL and 0.182 ng/mL during the dry season. In the samples of sediments taken in the surrounding areas of shrimp ponds, we found-for both seasons-that in 60 % of the samples, 4,4'-DDE was present in concentrations ranging from 3.75 ng/g to 30.97 ng/g. Additionally, in the rainy season, we observed heptachlor in sediment at concentrations below the method quantification limit. It was concluded that organochlorine compounds from pesticides are still present in Jiquilisco Bay, trapped in deep sediment, even though they have been banned since the 1980s. These were not detected in shrimp tissue, surface water, and shallow sediment in rearing ponds, and hence, we do not believe their presence has any major impact on shrimp production in sampled

  9. Estructura comunitaria de diatomeas presentes en los sedimentos superficiales de ocho lagos andinos de Chile central Diatoms community structure in superficial sediments of eight Andean lakes of central Chile

    Directory of Open Access Journals (Sweden)

    INGRID E ALVIAL

    2008-03-01

    Full Text Available En este trabajo se analizó la estructura comunitaria de diatomeas depositadas en los sedimentos superficiales de ocho lagos andinos chilenos ubicados entre los 32°49' y 38°48' S. Se encontró un total de 99 taxa de diatomeas, distribuidos en 48 géneros. Del total de taxa, 74 fueron identificados a nivel de especie siendo todos ellos cosmopolitas a excepción de Eunotia andinofrequens, Gomphonema punae, Pinnularia araucanensis y Pinnularia acidicola, entre otras, que están descritos solo para el Hemisferio Sur. Por otro lado, las muestras analizadas presentaron distinta composición florística de diatomeas. De esta manera, en los ensambles diatomológicos depositados en los sedimentos de las lagunas de altura Ocho, Huifa, Ensueño y Negra ubicadas sobre los 2.860 m del nivel del mar, abundaron especies bentónicas, típicas de aguas oligotróficas y acidas como Achnanthidium exiguum, Achnanthidium minutissimum, Encyonema minutum, Pinnularia acidicola y Planothidium lanceolatum. En los ensambles diatomológicos de los lagos Galletué, Icalma y Laja, ubicados bajo los 1.360 m del nivel del mar, abundaron diatomeas planctónicas, características de aguas alcalinas y mesotróficas como Asterionella formosa, Aulacoseira distans, Aulacoseira granulata, Cyclotella stelligera y Rhopalodia gibbaIn this research the taxonomic structure of diatoms in sediments of high mountain lakes was studied. These lakes are located in Chile between 32°49' and 38°48' S in the Andean Cordillera. A total of 99 diatom taxa distributed in 48 genera were identified and all this taxa are cosmopolitan excepting a Eunotia andinofrequens, Gomphonema punae, Pinnularia araucanensis and Pinnularia acidicola, which are know only for the Southern Hemisphere. The assemblages of diatoms were different in the studied lakes. So the high mountain lakes Ocho, Huifa, Ensueño and Negra, dominated benthic diatoms which are typical of oligotrophic and acid waters as Achnanthidium

  10. Reconstructing historical changes in combustion patterns by means of black carbon and PAH evaluation in dated sediments from Guanabara Bay, Rio de Janeiro

    International Nuclear Information System (INIS)

    The accumulation history of combustion products from the metropolitan area around Guanabara Bay was evaluated using black carbon and polycyclic aromatic hydrocarbons as indicators. BC concentration varied between 0.23 and 0.51%, with an increasing mass accumulation tendency over the last 118 years, whereas a decrease in the values of the ratio BC/organic carbon was observed in the upper sediment layers, probably reflecting the enhancement of bay's eutrophication process in the last 30 years. Higher concentrations of pyrolytic PAH were observed between 1925 and 1976, being consistent with the subsequent deforestation, urbanization, and industrialization that occurred in the Guanabara basin in the period. These PAHs were best characterized by the BFl/(BFl+BePy) diagnostic ratio. The data obtained allowed the characterization of the main events that influenced the combustion patterns in the region: burning of biomass and fossil fuel, economic crisis of 1970 and 1990 and the introduction of ethanol in the Brazilian energetic matrix. (author)

  11. Distribution and diversity of diatom assemblages in surficial sediments of shallow lakes in Wapusk National Park (Manitoba, Canada) region of the Hudson Bay Lowlands.

    Science.gov (United States)

    Jacques, Olivier; Bouchard, Frédéric; MacDonald, Lauren A; Hall, Roland I; Wolfe, Brent B; Pienitz, Reinhard

    2016-07-01

    The hydrology of shallow lakes (and ponds) located in the western Hudson Bay Lowlands (HBL) is sensitive to climate warming and associated permafrost thaw. However, their biological characteristics are poorly known, which hampers effective aquatic ecosystem monitoring. Located in northern Manitoba along the southwestern coast of Hudson Bay, Wapusk National Park (WNP) encompasses numerous shallow lakes representative of the subarctic zone. We analyzed the distribution and diversity of diatom (microscopic algae; class Bacillariophyceae) assemblages in surficial sediments of 33 lakes located in three different ecozones spanning a vegetation gradient, from NE to SW: the Coastal Fen (CF), the Interior Peat Plateau (IPP), and the Boreal Spruce Forest (BSF). We found significant differences (P inventory of the diatom assemblages in the WNP region needed for monitoring programs to detect changes in shallow lake ecosystems and ecozonal shifts in response to climate variations. PMID:27386094

  12. Water, organic matter, nitrogen and phosphorus contents in sediment of a large-scale mariculture area in the Zhelin Bay of eastern Guangdong Province, China

    Institute of Scientific and Technical Information of China (English)

    DONG Qiaoxiang; LIN Junda; SHANG Xu; LI Jin; HUANG Changjiang

    2008-01-01

    The Zhelin Bay is one of the most important bays for large-scale maricuhure in Guangdong Province,China.Owing to the increas-ing human population and the expanding marieuhure in the last two decades,the ecological environment has greatly changed with frequent harmful algal blooms.A monthly survey of water content,organic matter ( TOM ),and various forms of nitrogen and phosphorous in sediment from July 2002 to July 2003 in the bay was conducted.The results showed that the water content was cor-related significantly with TOM and various forms of nitrogen and phosphorus and can be used as proxy for quick and rough estimate of these factors in the future surveys.TOM was also correlated significantly with various forms of nitrogen and phosphorus,indica-ting that it was one of the key factors affecting the concentrations and distributions of nitrogen and phosphorus in the investigated waters. Average total Kjeldhal nitrogen (TkN) Content was( 1113.1±382.5 )μg/g and average total phosphorus (TP) content was(567.2 ± 223.3)μg/g, and both were much higher than those of similar estuaries in China and elsewhere. Average nitrogen and phosphorus tended to be higher inside than outside the bay,higher at aquaculture than non-aquacuhure areas,and higher at fish-cage culture than oyster culture areas,suggesting that large-scale mariculture inside the bay played an important role in the eutrophication of the Zhelin Bay.Various forms of nitrogen and phosphorus concentrations were higher during the warm season (July--September),which was due to the increased decomposition and concentration of organic matter resulted from the fast growth and high mortality of the cultured species.Compared with July 2002,TkN and TP contents were much higher in July 2003,in consonance with the eut~'ophication of the Zhelin Bay.Because exchangeable phosphorus ( Ex-P),iron-bounded phos-phorus (Fe-P) and organic phosphorus (OP) combined accounted for 34.3% of the TP and authigenie phosphorus (Au-P) ac

  13. Biogeochemical redox cycling of arsenic in mine-impacted lake sediments and co-existing pore waters near Giant Mine, Yellowknife Bay, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, C.F. [Queen' s University, Department of Geological Sciences and Geological Engineering, Kingston, K7L 3N6 (Canada); Jamieson, H.E., E-mail: jamieson@geol.queensu.ca [Queen' s University, Department of Geological Sciences and Geological Engineering, Kingston, K7L 3N6 (Canada); Kyser, T.K. [Queen' s University, Department of Geological Sciences and Geological Engineering, Kingston, K7L 3N6 (Canada); Praharaj, T.; Fortin, D. [University of Ottawa, Department of Earth Sciences, Ottawa, K1A 3N5 (Canada)

    2010-02-15

    Lacustrine sediments, submerged tailings, and their pore waters have been collected at several sites in Yellowknife Bay, Great Slave Lake, Canada, in order to investigate the biogeochemical controls on the remobilization of As from mining-impacted materials under different depositional conditions. Radiometric dating confirms that a mid-core enrichment of Pb, Zn, Cu and Sb corresponds to the opening of a large Au mine 60 a ago. This was evident even in a relatively remote site. Arsenic was enriched at mid-core, coincident with mining activity, but clearly exhibited post-depositional mobility, migrating upwards towards the sediment water interface (SWI) as well as down-core. Deep-water (15 m) Yellowknife Bay sediments that contain buried mine waste are suboxic, relatively organic-rich and abundant in microbes with As in pore waters and sediments reaching 585 {mu}g/L and 1310 mg/kg, respectively. Late summer pore waters show equal proportions of As(III) and As(V) (16-415 {mu}g/L) whereas late winter pore waters are dominated by As(III) (284-947 {mu}g/L). This can be explained by As(III) desorption mechanisms associated with the conversion of FeS to FeS{sub 2} and the reduction of As(V) to As(III) through the oxidation of dissolved sulfide, both microbially-mediated processes. Processes affecting As cycling involve the attenuating efficiency of the oxic zone at the SWI, sediment redox heterogeneity and the reductive dissolution of Fe(hydr)oxides by labile organic matter, temporarily and spatially variable.

  14. Antibacterial agents and heavy metal resistance in Gram-negative bacteria isolated from seawater, shrimp and sediment in Iskenderun Bay, Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Matyar, Fatih [Cukurova University, Faculty of Education, Department of Science and Technology Education, 01330 Balcali, Adana (Turkey)], E-mail: fmatyar@cu.edu.tr; Kaya, Aysenur; Dincer, Sadik [Cukurova University, Faculty of Science and Letters, Department of Biology, 01330 Balcali, Adana (Turkey)

    2008-12-15

    The aim of the present study was to determine the level of antibiotic resistance patterns and distribution of heavy metal resistance of bacterial isolates from seawater, sediment and shrimps, and to determine if there is a relationship between antibiotic and heavy metal resistance. We undertook studies in 2007 in the industrially polluted Iskenderun Bay, on the south coast of Turkey. The resistance of 236 Gram-negative bacterial isolates (49 from seawater, 90 from sediment and 97 from shrimp) to 16 different antibiotics, and to 5 heavy metals, was investigated by agar diffusion and agar dilution methods, respectively. A total of 31 species of bacteria were isolated: the most common strains isolated from all samples were Escherichia coli (11.4%), Aeromonas hydrophila (9.7%) and Stenotrophomonas maltophilia (9.3%). There was a high incidence of resistance to ampicillin (93.2%), streptomycin (90.2%) and cefazolin (81.3%), and a low incidence of resistance to imipenem (16.5%), meropenem (13.9%) and cefepime (8.0%). Some 56.8% of all bacteria isolated from seawater, sediment and shrimp were resistant to 7 or more antibiotics. Most isolates showed tolerance to different concentrations of heavy metals, and minimal inhibition concentrations ranged from 12.5 {mu}g/ml to > 3200 {mu}g/ml. The bacteria from seawater, sediment and shrimp showed high resistance to cadmium of 69.4%, 88.9%, and 81.1% respectively, and low resistance to manganese of 2%, 6.7% and 11.3% respectively. The seawater and sediment isolates which were metal resistant also showed a high resistance to three antibiotics: streptomycin, ampicillin and trimethoprim-sulphamethoxazole. In contrast, the shrimp isolates which were metal resistant were resistant to four antibiotics: cefazolin, nitrofurantoin, cefuroxime and ampicillin. Our results show that Iskenderun Bay has a significant proportion of antibiotic and heavy metal resistant Gram-negative bacteria, and these bacteria constitute a potential risk for

  15. Antibacterial agents and heavy metal resistance in Gram-negative bacteria isolated from seawater, shrimp and sediment in Iskenderun Bay, Turkey

    International Nuclear Information System (INIS)

    The aim of the present study was to determine the level of antibiotic resistance patterns and distribution of heavy metal resistance of bacterial isolates from seawater, sediment and shrimps, and to determine if there is a relationship between antibiotic and heavy metal resistance. We undertook studies in 2007 in the industrially polluted Iskenderun Bay, on the south coast of Turkey. The resistance of 236 Gram-negative bacterial isolates (49 from seawater, 90 from sediment and 97 from shrimp) to 16 different antibiotics, and to 5 heavy metals, was investigated by agar diffusion and agar dilution methods, respectively. A total of 31 species of bacteria were isolated: the most common strains isolated from all samples were Escherichia coli (11.4%), Aeromonas hydrophila (9.7%) and Stenotrophomonas maltophilia (9.3%). There was a high incidence of resistance to ampicillin (93.2%), streptomycin (90.2%) and cefazolin (81.3%), and a low incidence of resistance to imipenem (16.5%), meropenem (13.9%) and cefepime (8.0%). Some 56.8% of all bacteria isolated from seawater, sediment and shrimp were resistant to 7 or more antibiotics. Most isolates showed tolerance to different concentrations of heavy metals, and minimal inhibition concentrations ranged from 12.5 μg/ml to > 3200 μg/ml. The bacteria from seawater, sediment and shrimp showed high resistance to cadmium of 69.4%, 88.9%, and 81.1% respectively, and low resistance to manganese of 2%, 6.7% and 11.3% respectively. The seawater and sediment isolates which were metal resistant also showed a high resistance to three antibiotics: streptomycin, ampicillin and trimethoprim-sulphamethoxazole. In contrast, the shrimp isolates which were metal resistant were resistant to four antibiotics: cefazolin, nitrofurantoin, cefuroxime and ampicillin. Our results show that Iskenderun Bay has a significant proportion of antibiotic and heavy metal resistant Gram-negative bacteria, and these bacteria constitute a potential risk for public

  16. Coastal circulation and sediment dynamics in Pelekane and Kawaihae Bays, Hawaii--measurements of waves, currents, temperature, salinity, turbidity, and geochronology: November 2010--March 2011

    Science.gov (United States)

    Storlazzi, Curt D.; Field, Michael E.; Presto, M. Katherine; Swarzenski, Peter W.; Logan, Joshua B.; Reiss, Thomas E.; Elfers, Timothy C.; Cochran, Susan A.; Torresan, Michael E.; Chezar, Hank

    2012-01-01

    Coral reef communities on the Island of Hawaii have been heavily affected by the construction of Kawaihae Harbor in the 1950s and by subsequent changes in land use in the adjacent watershed. Sedimentation and other forms of land-based pollution have led to declines in water quality and coral reef health over the past two decades (Tissot, 1998). Erosion mitigation efforts are underway on land, and there is a need to evaluate the impact of these actions on the adjacent coastal ecosystem. The Kohala Center and Kohala Watershed Partnership was awarded $2.69 million from the National Oceanographic and Atmospheric Administration’s (NOAA) Restoration Center as part of the American Recovery and Reinvestment Act of 2009 to stabilize soil and improve land-use practices in the Pelekane Bay watershed. The grant allowed the Kohala Watershed Partnership to implement various upland watershed management activities to reduce land-based sources of pollution into Pelekane Bay. However, a number of questions must be answered in order to: (1) evaluate the effectiveness of the terrestrial watershed remediation efforts; (2) understand the potential of the local marine ecosystem to recover; and (3) understand the potential threat that existing mud deposits in the bay pose to adjacent, relatively pristine coral reef ecosystems. The goal of this experiment was to help address these questions and establish a framework to evaluate the success of the Kohala Watershed Partnership restoration efforts. This research program will also provide resource managers with information relevant to other watershed restoration efforts currently being planned in neighboring watersheds. This project involved an interdisciplinary team of coral reef biologists from the University of Hawaii Coral Reef Assessment and Monitoring Program, who focused on the impact of sedimentation on the biota of Pelekane Bay, and a team of geologists and oceanographers from the U.S. Geological Survey (USGS), who focused on the

  17. Pollen record and paleoenvironment of a 4210 years B.P.old sediment in the Bay of Guanabara, Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    Barth Ortrud M.

    2004-01-01

    Full Text Available Pollen analysis of a sediment sample obtained at 222 cm from the top of a drilling core collected in the Bay of Guanabara, Rio de Janeiro, was used as a tool to obtain more knowledge about pre-historical human living and environment. 14C datation revealed the age of 4210 years B.P. Most frequent pollen grains came from plants like Alchornea (Euphorbiaceae, Celtis (Ulmaceae, Lecythidaceae, Meliaceae, Ochnaceae and spores from forest Pteridophyta. Palynology and environmental studies revealed that agricultural activities could not be detected. The dense tropical rain forest was the dominant vegetation occurring in this region.

  18. Paleoenvironment interpretation of a 1760 years B.P. old sediment in a mangrove area of the Bay of Guanabara, using pollen analysis

    Directory of Open Access Journals (Sweden)

    Barth Ortrud M.

    2006-01-01

    Full Text Available A sediment sample was obtained at 122 cm from the top of a drilling core in the Guapimirim mangrove, Bay of Guanabara, and analyzed using pollen analysis. This muddy core reached a sandy ground at 133 cm. 14C datation got the age of 1760 ? 50 years B.P. The most frequent pollen grains were mangrove species of Rhizophora mangle, Laguncularia racemosa and Avicennia schaueriana. "Restinga" and tropical rain forest vegetation was recognized behind the mangrove. After the last sea transgression at 2500 years B.P., the water level lowered to its actual size, allowing the installation of this mangrove.

  19. Evaluating the potential effects of hurricanes on long-term sediment accumulation in two micro-tidal sub-estuaries: Barnegat Bay and Little Egg Harbor, New Jersey, U.S.A.

    Science.gov (United States)

    Marot, Marci E.; Smith, Christopher G.; Ellis, Alisha M.; Wheaton, Cathryn J.

    2016-01-01

    Barnegat Bay, located along the eastern shore of New Jersey, was significantly impacted by Hurricane Sandy in October 2012. Scientists from the U.S. Geological Survey (USGS) developed a multidisciplinary study of sediment transport and hydrodynamics to understand the mechanisms that govern estuarine and wetland responses to storm forcing. This report details the physical and chemical characteristics of surficial and downcore sediments from two areas within the bay. Eleven sites were sampled in both the central portion of the bay near Barnegat Inlet and in the southern portion of the bay in Little Egg Harbor. Laboratory analyses include Be-7, Pb-210, bulk density, porosity, x-radiographs, and grain-size distribution. These data will serve as a critical baseline dataset for understanding the current sedimentological regime and can be applied to future storms for understanding estuarine and wetland evolution.

  20. Deposition of the 2011 Cordón Caulle Tephra (Chile, 40ºS) in Lake Sediments: Implications for Tephrochronology and Volcanology

    Science.gov (United States)

    Bertrand, S.; Daga, R.; Bedert, R.; Fontijn, K.

    2014-12-01

    Tephras preserved in lake sediments are commonly used to synchronize sedimentary archives of climate and environmental change, and to correlate them with terrestrial environments. They also provide an opportunity to reconstruct explosive volcanic activity, e.g., eruption frequency and tephra dispersal. Although it is known that sedimentary processes may affect the record of tephras in lakes, lake sediments are generally considered as one of the best archives of tephra stratigraphy. The June 2011 eruption of the Cordón Caulle (CC, Chile, 40ºS) offered an ideal opportunity to study the processes affecting tephra deposition in lakes. During the 2011 CC eruption, the prevailing westerly winds transported the erupted pyroclastic material away from Puyehue Lake. Yet, the tephra was identified within the lake with a thickness ranging from 1 cm to >10 cm. This is in contrast with smaller lakes, where tephra thickness was in agreement with ash fall distribution maps. Geomorphological observations and sedimentological analyses provide evidence that the tephra deposited in Puyehue Lake entirely consists of material reworked from the upper watershed, transported by rivers, and distributed by lake currents according to particle size and density. Proximal basins mostly received coarse tephra particles via underflows, while in distal basins the deposits consisted of low amounts of fine-grained particles transported by interflows. Pumice transported by overflows reached most lake basins. These results have important implications for tephrochronology and volcanology. First, they show that lakes do not act as passive tephra traps, and they illustrate how two nearby lakes can contain very distinct tephra records, simply due to the size and orientation of their drainage basins. Second, they show that lakes with large watersheds, such as Puyehue, record many more eruptions than smaller lakes, which only register direct ash falls, leading to very different conclusions regarding the

  1. An examination of historic inorganic sedimentation and organic matter accumulation in several marsh types within the Mobile Bay and and Mobile-Tensaw River Delta region

    Science.gov (United States)

    Smith, Christopher G.; Osterman, Lisa E.; Poore, Richard Z.

    2013-01-01

    Mass accumulation rates (MAR; g cm-2 y-1), linear sedimentation rates (LSR; cm y-1), and core geochronology derived from excess lead-210 (210Pb) profiles and inventories measured in six sediment cores collected from marsh sites from the MobileTensaw River Delta and Mobile Bay region record the importance of both continuous and event-driven inorganic sedimentation over the last 120 years. MAR in freshwater marshes varied considerably between sites and through time (0.24 and 1.31 g cm-2 y-1). The highest MARs occurred in the 1950s and 1960s and correspond to record discharge events along the Mobile and Tensaw Rivers. In comparison, MAR at salt marsh sites increased almost threefold over the last 120 years (0.05 to 0.18 g cm-2 y-1 or 0.23 to 0.48 cm y-1). From 1880 to 1960, organic accumulation remained fairly constant (20%), while intermittent pulses of high inorganic sedimentation were observed following 1960. The pulses in inorganic sedimentation coincide with several major hurricanes (e.g., Hurricanes Camille, Fredric, Georges, and Ivan). The nearly threefold increase in MAR in salt marshes during the last 120 years would thus appear to be partially dependent on inorganic sedimentation from storm events. This study shows that while hurricanes, floods, and other natural hazards are well-known threats to human infrastructure and coastal ecosystems, these events also transport sediment to marshes that help abate other pressures such as sea-level rise (SLR) and subsidence.

  2. Contents of Cd, Cu and Zn in sediments of swamp areas in Santa Marta's Big Marsh and the Bay of Chengue, Colombian Caribbean

    International Nuclear Information System (INIS)

    With the purpose of determining the contents of the metals Cd, Cu and Zn in sediments of swamp areas, they were selected 4 stations in Santa Marta's Big Marsh and one in the Bay of Chengue in the Natural National Park Tayrona. Four collections of samples of sediments were made along one year and they were analyzed by spectrum photometry of atomic absorption, the concentrations of the metals Cd, Cu and Zn. Parallelly the salinity, the pH, the potential redox and the content of organic matter in the fine fraction was measured. The results were compared with those reported in other places of the world, being proven that you/they are in many cases below those registered in the literature

  3. A new depositional model for glacial sediments in Killiney Bay during the Late Devensian deglaciation - East Central Ireland

    Science.gov (United States)

    Clerc, S.; Portier, E.; Buoncristiani, J. F.

    2009-04-01

    During the last glaciation in northwestern Europe, major studies are consistent with the hypothesis of an ice-stream flowing southward in the Irish Sea Basin, in connection with tributary flows on the eastern of the Irish Cap. During deglaciation, sediment deposition processes are predominant, leaving a record of glacially influenced environments. Evidence of such deposits still remains on the coast of the UK and Ireland today. Although these deposits have been studied for many decades, their depositional environment is still under debate and interpretations are evolving, together with new concepts. The present work focuses on the study of the Killiney Bay section, South Dublin, located in a topographic depression, expected to be a former subglacial tunnel valley in connection with an offshore canyon in the Irish Sea. Geometry and architecture have been approached by using panoramic photographs. In addition, fifteen detailed logs describe the stratigraphic succession, erosive surfaces and variations of small-scale sedimentary features. Seven Facies Associations were defined and used to reconstruct depositional environments. Although the section is affected by glaciotectonic deformation, primary sedimentological figures are well preserved. Within the section, a 600m long depression has been observed, in which a Gilbert-type delta has developed. Laterally, this delta evolves into prograding sheet-like structures interpreted as subaqueous fans. The corresponding facies association is composed of four main facies: -Matrix-supported coarse-grained facies (granules to cobbles) arranged in prograding sheet-like structures (dip angle 5-9° N160). -Massive sand to diffusely graded sand. -Coarse-to-medium sand facies with long wavelength ripples (1-2m), oriented N160. -Medium-to-coarse sand with climbing ripples and current ripples. These facies associations are characteristic of subaqueous (probably glaciolacustrine) environments. The transition from delta to fan delta has

  4. Distribution and biological effects of agricultural chemicals and other environmental contaminants in the sediments of Back Bay, Virginia

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Back Bay is the northernmost extension of the Albemarle- Pamlico-Currituck Sound estuary. It is located entirely within the city limits of Virginia Beach, Virginia....

  5. Sediment transport and deposition during extreme sea storm events at the Salerno Bay (Tyrrhenian Sea: comparison of field data with numerical model results

    Directory of Open Access Journals (Sweden)

    F. Budillon

    2006-01-01

    Full Text Available Seismic stratigraphy and core litho-stratigraphy in the Salerno Bay inner shelf (Southern Tyrrhenian Sea reveal significant storm deposition episodes over the last 1 ky. Three major events are preserved as decimetre thick silt/sand layers bounded at their base by erosional surfaces and sealed in the muddy marine sequences between 25 and 60 m of depth. Geochronology and chrono-stratigraphy on core sediment point towards a recurrence of major sea storms between 0.1 and 0.3 ky and put the last significant event in the 19th century, when no local meteorological time series is available. A modelling of extreme sea-storms with a return period of about 0.1 ky is here proposed based on historical hindcast and aims at explaining the occurrence of such unusual deep and thick sand deposits in the northern sector of the bay. Results highlight the vulnerability of the northern coast of the Salerno Bay to the south western sea storms which can drive waves up to about 8 m high and wave period of about 13 s. With these conditions an intense combined flow current is formed and might account for winnowing fine sand down to the depth of 40 m at least. The numerical model thus confirms a possible sand transport in the bottom boundary layer due to wave-current interaction and could corroborate the interpretation of the most recent sand layers, included in the cores, as being generated under extreme sea storm conditions.

  6. Determination of volatile, toxic hydrogen phosphides in the sediments of the Elbe river, the Elbe estuaries and the Heligoland Bay

    International Nuclear Information System (INIS)

    The distribution and concentraion of phosphines in the sediments of the Elbe river were determined by selective preparation and analysis. The concentration of phosphines in one kilogram wet sediment was in the range of 0.1 to 57 n g with the bulking, anaerobic mud from harbors having the highest and the sandy, aerobic sediments having the lowest concentrations. Phosphines in fluvial sediments were detected successfully for the first time applying the method described. (orig.)

  7. A rapid procedure for the determination of thorium, uranium, cadmium and molybdenum in small sediment samples by inductively coupled plasma-mass spectrometry: Application in Chesapeake Bay

    Science.gov (United States)

    Zheng, Yen; Weinman, B.; Cronin, T.; Fleisher, M.Q.; Anderson, Robert F.

    2003-01-01

    This paper describes a rapid procedure that allows precise analysis of Mo, Cd, U and Th in sediment samples as small as 10 mg by using a novel approach that utilizes a "pseudo" isotope dilution for Th and conventional isotope dilution for Mo, Cd and U by ICP-MS. Long-term reproducibility of the method is between 2.5 and 5% with an advantage of rapid analysis on a single digestion of sediment sample and the potential of adding other elements of interest if so desired. Application of this method to two piston cores collected near the mouth of the Patuxent River in Chesapeake Bay showed that the accumulation of authigenic Mo and Cd varied in response to the changing bottom water redox conditions, with anoxia showing consistent oscillations throughout both pre-industrial and industrial times. Accumulation of authigenic U shows consistent oscillations as well, without any apparent increase in productivity related to anoxic trends. Degrees of Mo and Cd enrichment also inversely correlate to halophilic microfaunal assemblages already established as paleoclimate proxies within the bay indicating that bottom water anoxia is driven in part by the amount of freshwater discharge that the area receives. ?? 2002 Elsevier Science Ltd. All rights reserved.

  8. A rapid procedure for the determination of thorium, uranium, cadmium and molybdenum in small sediment samples by inductively coupled plasma-mass spectrometry: application in Chesapeake Bay

    International Nuclear Information System (INIS)

    This paper describes a rapid procedure that allows precise analysis of Mo, Cd, U and Th in sediment samples as small as 10 mg by using a novel approach that utilizes a 'pseudo' isotope dilution for Th and conventional isotope dilution for Mo, Cd and U by ICP-MS. Long-term reproducibility of the method is between 2.5 and 5% with an advantage of rapid analysis on a single digestion of sediment sample and the potential of adding other elements of interest if so desired. Application of this method to two piston cores collected near the mouth of the Patuxent River in Chesapeake Bay showed that the accumulation of authigenic Mo and Cd varied in response to the changing bottom water redox conditions, with anoxia showing consistent oscillations throughout both pre-industrial and industrial times. Accumulation of authigenic U shows consistent oscillations as well, without any apparent increase in productivity related to anoxic trends. Degrees of Mo and Cd enrichment also inversely correlate to halophilic microfaunal assemblages already established as paleoclimate proxies within the bay indicating that bottom water anoxia is driven in part by the amount of freshwater discharge that the area receives

  9. Distribution and ecological risk of organic pollutants in the sediments and seafood of Yangtze Estuary and Hangzhou Bay, East China Sea.

    Science.gov (United States)

    Adeleye, Adedayo O; Jin, Haiyan; Di, Yanan; Li, Donghao; Chen, Jianfang; Ye, Ying

    2016-01-15

    A wide variety of persistent organic pollutants (POPs) in the surface marine sediments and seafood from four geographic areas of the East China Sea were investigated. The POP concentrations were analyzed and their possible ecotoxicological risks assessed. The total concentrations of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) in the sediments were found to be ND-22.40, ND-5.10, 32.10-171.70, and 0.60-63.00 ng/g dry weight (dw), respectively. Low-chlorinated biphenyl congeners and HCHs were predominantly found at the Hangzhou Bay and Yangtze River areas. The sediment ecotoxicological risk was assessed, indicating the toxic effect of PCBs and DDTs on benthic organisms. In marine organisms of economic importance, the concentration of total PAHs, PCBs, and organochlorine pesticides (OCPs) ranged from 43.20 to 291.20, 2.60 to 96.20, and 12.70 to 235.20 μg/kg dw, respectively. The bioaccumulation in marine organisms did not pose a significant health risk to consumers. As indicated by the POP residues in both marine sediments and organisms, POPs were persistent over time, posing a long-term risk to the local ecosystem and human health via the food chain. PMID:26479920

  10. Contaminant profiles for surface water, sediment, flora and fauna associated with the mangrove fringe along middle and lower eastern Tampa Bay.

    Science.gov (United States)

    Lewis, M A; Russell, M J

    2015-06-15

    Contaminant concentrations are reported for surface water, sediment, flora and fauna collected during 2010-2011 from the mangrove fringe along eastern Tampa Bay, Florida. Concentrations of trace metals, chlorinated pesticides, atrazine, total polycyclic aromatic hydrocarbons, and polychlorinated biphenyls were species-, chemical- and location-specific. Contaminants in sediments did not exceed proposed individual sediment quality guidelines. Most sediment quality assessment quotients were less than one indicating the likelihood of no inhibitory effect based on chemical measurements alone. Faunal species typically contained more contaminants than plant species; seagrass usually contained more chemicals than mangroves. Bioconcentration factors for marine angiosperms were usually less than 10 and ranged between 1 and 31. Mercury concentrations (ppm) in blue crabs and fish did not exceed the U.S. Environmental Protection Agency fish tissue criterion of 0.3 and the U.S. Food and Drug Administration action level of 1.0. In contrast, total mercury concentrations in faunal species often exceeded guideline values for wildlife consumers of aquatic biota. PMID:25931177

  11. Seasonal cycles of particle and solute transport processes in nearshore sediments: 222Rn/226Ra and 234Th/238U disequilibrium at a site in Buzzards Bay, MA

    International Nuclear Information System (INIS)

    Particle mixing rates and irrigation rates in the sediments of a site in Buzzards Bay, Massachusetts, have been estimated over two nearly full seasonal cycles. Seasonal variability is consistent with biologically driven transport mechanisms. 234Th/238U disequilibrium measurements were used to estimate particle mixing rates, a cold-season average rate of 5.6 cm2/yr and a warm-season average rate of 17 cm2/yr were found. Excess 234Th inventories in the upper 5 cm of the sediments also varied seasonally, with a cold-season average value of 1.8 dmp/cm2, and a warm-season value of 3.4 dpm/cm2. 222Rn/226Ra disequilibrium in sediment pore waters was used to estimate sediment irrigation. Three seasonal groupings of results were made: (1) December through March, when 222Rn deficits could be explained by vertical molecular diffusion alone, (2) early summer (June), when irrigation was important to at least 20 cm, (3) early fall, when irrigation was important to about 10 cm. A nonlocal exchange/vertical molecular diffusion model (Emerson et al., 1984) was used to obtain quantitative estimates of irrigation rates; model Rn deficit profiles could be fitted to measured profiles quite well. (author)

  12. Accumulation of Pb and Cu heavy metals in sea water, sediment, and leaf and root tissue of Enhalus sp. in the seagrass bed of Banten Bay

    Energy Technology Data Exchange (ETDEWEB)

    Fauziah, Faiza, E-mail: faiza.fauziah@gmail.com; Choesin, Devi N., E-mail: faiza.fauziah@gmail.com [School of Life Sciences and Technology, Institut Teknologi Bandung, Jalan Ganeca 10, Bandung 40132 (Indonesia)

    2014-03-24

    Banten Bay in Indonesia is a coastal area which has been highly affected by human activity. Previous studies have reported the presence of lead (Pb) and copper (Cu) heavy metals in the seawater of this area. This study was conducted to measure the accumulation of Pb and Cu in seawater, sediment, leaf tissue, and root tissue of the seagrass species Enhalus sp. Sampling was conducted at two observation stations in Banten Bay: Station 1 (St.1) was located closer to the coastline and to industrial plants as source of pollution, while Station 2 (St.2) was located farther away offshore. At each station, three sampling points were established by random sampling. Field sampling was conducted at two different dates, i.e., on 29 May 2012 and 30 June 2012. Samples were processed by wet ashing using concentrated HNO{sub 3} acid and measured using Atomic Absorption Spectrometry (AAS). Accumulation of Pb was only detected in sediment samples in St.1, while Cu was detected in all samples. Average concentrations of Cu in May were as follows: sediment St.1 = 0.731 ppm, sediment St.2 = 0.383 ppm, seawater St.1 = 0.163 ppm, seawater St.2 = 0.174 ppm, leaf St.1 = 0.102 ppm, leaf St.2 = 0.132 ppm, root St.1= 0.139 ppm, and root St.2 = 0.075 ppm. Average measurements of Cu in June were: sediment St.1 = 0.260 ppm, leaf St.1 = 0.335 ppm, leaf St.2 = 0.301 ppm, root St.1= 0.047 ppm, and root St.2 = 0.060 ppm. In June, Cu was undetected in St.2 sediment and seawater at both stations. In May, Cu concentration in seawater exceeded the maximum allowable threshold for water as determined by the Ministry of the Environment. Spatial and temporal variation in Pb and Cu accumulation were most probably affected by distance from source and physical conditions of the environment (e.g., water current and mixing)

  13. Impact of Hurricane Irene on Vibrio vulnificus and Vibrio parahaemolyticus concentrations in surface water, sediment and cultured oysters in the Chesapeake Bay, Maryland, USA

    Directory of Open Access Journals (Sweden)

    KristiSShaw

    2014-05-01

    Full Text Available To determine if a storm event (i.e., high winds, large volumes of precipitation could alter concentrations of Vibrio vulnificus and Vibrio parahaemolyticus in aquacultured oysters (Crassostrea virginica and associated surface water and sediment, this study followed a sampling timeline before and after Hurricane Irene impacted the Chesapeake Bay estuary in late August 2011. Aquacultured oysters were sampled from two levels in the water column: surface 0.3 m and near-bottom just above the sediment. Concentrations of each Vibrio spp. and associated virulence genes were measured in oysters with a combination of real-time PCR and most probable number enrichment methods, and in sediment and surface water with real-time PCR. While concentration shifts of each Vibrio species were apparent post-storm, statistical tests indicated no significant change in concentration change for either Vibrio species by location (surface or near bottom oysters or date sampled (oyster tissue, surface water and sediment concentrations. V. vulnificus in oyster tissue was correlated with total suspended solids (r=0.41, p=0.04, and V. vulnificus in sediment was correlated with secchi depth (r=-0.93, p< 0.01, salinity (r=-0.46, p=0.02, tidal height (r=-0.45, p=0.03, and surface water V. vulnificus (r=0.98, p< 0.01. V. parahaemolyticus in oyster tissue did not correlate with environmental measurements, but V. parahaemolyticus in sediment and surface water correlated with several measurements including secchi depth (r=-0.48, p=0.02[sediment]; r=-0.97 p< 0.01[surface water] and tidal height (r=-0.96. p< 0.01[sediment], r=-0.59,p< 0.01 [surface water]. The concentrations of Vibrio spp. were higher in oysters relative to other studies (average V. vulnificus 4x105 MPN g-1, V. parahaemolyticus 1x105 MPN g-1, and virulence-associated genes were detected in most oyster samples. This study provides a first estimate of storm-related Vibrio density changes in oyster tissues, sediment and

  14. Sobrevivencia y crecimiento de post-larvas de Argopecten purpuratus (Lamarck, 1819 en Bahía Inglesa, Chile: efectos del origen, distribución en la bahía y bacterioflora larval Postlarval survival and growth of Argopecten purpuratus (Lamarck,1819 in Bahia Inglesa, Chile: effects of origin, distribution in the bay and larval bacterioflora

    Directory of Open Access Journals (Sweden)

    RUBÉN E. AVENDAÑO

    2001-09-01

    Full Text Available Argopecten purpuratus es uno de los recursos marinos de mayor importancia comercial en Chile. Una de las etapas críticas en el cultivo de esta especie, es el traspaso de las post-larvas al medio natural, ya que durante este período se produce un significativo descenso en el número de post-larvas. Los factores que provocan estas bajas sobrevivencias pueden ser diversos, pero aún son desconocidos. En el presente estudio se evaluó la incidencia en la sobrevivencia y crecimiento de las variables origen de las larvas, distribución de los colectores en diferentes estaciones de Bahía Inglesa, III región (27° 03' 24" S, 70° 51' 30" O y los cambios en la bacterioflora asociadas a las post-larvas. Los organismos utilizados en el estudio fueron obtenidas desde los "hatcheries" de Cultivos Marinos Internacionales (III región y Cultivos Guayacán (IV región. Los resultados del estudio indican claramente que la ubicación y origen de las post-larvas en la bahía incide en la sobrevivencia de éstas. Sin embargo, el crecimiento no es afectado por las variables estudiadas (P Argopecten purpuratus is one of the most commercially important marine resources in Chile. One of the most critical steps in the massive culture of this species is the transference of postlarvae from hatchery production to the sea where significant mortality regularly occurs. The factors behind this low survival rate are probably diverse, and are as yet unknown. In the present study, postlarval survival and growth was observed as a function of origin of postlarvae, distribution of postlarvae in the bay, and microbial loading of the postlarvae. Survival rates were measured for different sites in Bahia Inglesa, Chile (27° 03' 24" S, 70° 51' 30" W as well as changes in the bacterioflora of the postlarvae. Postlarvae utilized in the study were obtained from Cultivos Marinos Internacionales (III Región and Cultivos Guayacan (IV Región. Results of the study clearly indicated that

  15. Historical decline and altered congener patterns of polychlorinated dibenzo-p-dioxins and dibenzofurans in fish and sediment in response to process changes at a pulp mill discharging into Jackfish Bay, Lake Superior.

    Science.gov (United States)

    Dahmer, Shari C; Tetreault, Gerald R; Hall, Roland I; Munkittrick, Kelly R; McMaster, Mark E; Servos, Mark R

    2015-11-01

    Improved regulations for pulp and paper mill effluents and an industry shift away from elemental chlorine bleaching in the 1990s greatly reduced the release of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) into the environment. However, the high potential of these contaminants to persist in sediment and bioaccumulate in biota means that they have remained a concern. To document current contamination from bleached kraft pulp mill effluent, PCDD/Fs were measured in white sucker (Catostomus commersoni) collected from Jackfish Bay, Lake Superior. These values were contrasted to historically reported fish data as well as PCDD/F patterns from dated sediment cores. Patterns of PCDD/Fs in sediment cores from Jackfish Bay and reference sites demonstrated a relationship between contamination and mill process changes. During the peak PCDD/F contamination period (1991), when the mill was still using elemental chlorine, the contamination patterns in fish and sediment were distinct and dominated by 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran. Following the reduction in the use of elemental chlorine during the early 1990s, a rapid decline was observed in PCDD/F contamination of fish tissue, and levels are now approaching background conditions with congener patterns more reflective of atmospheric sources. Although surface sediments from Jackfish Bay continue to have elevated PCDD/Fs, with some locations exceeding sediment quality guidelines, they do not appear to be highly bioavailable to benthic fish. PMID:26468966

  16. Evaluation of the activity concentration of 226Ra, 228Ra and 210Pb in sediments from Antarctica in the Admiralty bay region

    International Nuclear Information System (INIS)

    The natural radionuclides from radioactive series of 238U, 235U and 232Th have been applied as tracers in environmental studies for understanding the dynamics that occur in both marine and terrestrial environment, as for example, in research of oceanic processes and management of the coastal region. In the marine environment, these radionuclides can be used to estimate biogeochemical fluxes of marine particles and nutrients that occur in the water column as well as in the sediment. Several research works applied the distribution and the respective disequilibrium degree of natural radionuclides in the environment, including geochronological models for obtaining historical information on samples of certain sediment profile. In this study we performed a radiochemical characterization of the distribution of 226Ra, 228Ra and 210Pb from a sedimentary column called 1B (248 cm long) collected in the Admiralty Bay, Antarctic Peninsula region. The methodology used included the acid leaching of sediment samples followed by the radiochemical sequential separation of 226Ra and 228Ra by co-precipitation with Ba(Ra)SO4 and 210Pb by co-precipitation with PbCrO4. All measurements were carried out by counting of gross alpha and gross beta measures in a low background gas flow proportional detector. The activity concentrations of 226Ra and 210Pb were used to estimate the unsupported 210Pb activities present in sediment profile 1 B. Based on unsupported 210Pb data and the application of the CIC model (Constant Initial Concentration), it was possible to determine the sedimentation rate of 0.59 ± 0.05 cm /year. (author)

  17. Sediment distribution and dynamics inferred by integrated electromagnetic, optical and acoustic benthic profiling in the western Bay of Plenty (New Zealand)

    Science.gov (United States)

    Kulgemeyer, T.; von Dobeneck, T. F.; Müller, H.; Bryan, K. R.; de Lange, W. P.; Battershill, C.

    2015-12-01

    In October 2011, New Zealand experienced a marine pollution disaster after the MV RENA ran aground in the western Bay of Plenty. To estimate the transport and burial potential of contaminants, local sediment distribution and dynamics had to be assessed quickly. Our study made use of the benthic profiler NERIDIS III of the University of Bremen. 33 cross-shore profiles, each ca. 8 km long, have been surveyed. The main instrument is a controlled-source electromagnetic (CSEM) sensor, which is measuring the electric conductivity and magnetic susceptibility of the seafloor. High-resolution, overlapping seafloor photos have been taken by a bow-mounted digital camera. An on-board CTD with turbidity sensor complete the sensor arrangement. From the EM data, porosity and magnetite concentrations have been calculated and interpolated. The resulting maps show specific zones of magnetite enrichment, higher concentrations are correlated to low porosity. Photos have been used along with acoustic backscatter measured by a sidescan sonar to sketch out a preliminary map of sediment facies. Based on this, sides for grab sampling were selected. By taking grain size and mineralogy into account, a detailed map of the regional lithofacies could be created. Local sediment dynamics have been inferred by the observation of bedforms, the turbidity of bottom water and lithofacies. The results show two anti-parallel longshore transport paths dependent on differing weather conditions and water depths. The longshore magnetite distribution indicates that the heavy mineral fraction is mainly affected by storm-induced sediment transport. Our study demonstrates how integrated benthic profiling adds to the interpretability of data obtained by established methods. By bridging the gap between area-covering, but indirect data from hydroacoustics and precise, but punctual data from samples, benthic profiling enables fast and detailed assessment of sediment distribution and dynamics on a large scale.

  18. Relationships between Heavy Metal Concentrations in the American Oyster (Crassostrea virginica and Metal Levels in the Water Column and Sediment in Apalachicola Bay, Florida

    Directory of Open Access Journals (Sweden)

    Dennis A. Apeti

    2005-01-01

    Full Text Available This study aims to assess baseline concentrations of heavy metals (Cd, Cr, Cu, Pb and Zn in the oyster soft tissue as they relate to concentrations in the water column (particulate phase and sediment in Apalachicola Bay. In order to conduct these assessments, a total of 360 samples, collected in two seasons (winter and summer and were analyzed using atomic absorption spectrometry. Results indicated that elemental concentrations in particulate phase correlate significantly with concentration in the tissue than those in the sediment. Moreover, assessment of seasonal and spatial variations have indicated that oysters collected in the winter have significantly higher (P<0.05 Cu, Pb and Zn concentrations than oysters collected in the summer. However, metal concentrations in sediment did not show such patterns. These observations confirmed the fact that metals in the particulate phase are more bioavailable to oysters and that the oysters can be used as good indicators of the spatial and temporal variation of the heavy metals in the aquatic system.

  19. The geochemistry model of the surface sediment determined by using ED-XRF technique: a case study of the Boka Kotorska bay, Adriatic Sea.

    Science.gov (United States)

    Tanaskovski, Bojan; Jović, Mihajlo; Miličić, Ljiljana; Pezo, Lato; Mandić, Milica; Stanković, Slavka

    2016-06-01

    The spatial distribution of major oxides (Na2O, K2O, SiO2, Al2O3, Fe2O3, CaO, MgO, MnO, TiO2, P2O5) and numerous elements (Cr, Co, Ni, Cu, Zn, As, Se, Pb, Sn, Sb, Ba, Sr, Br, Rb, Zr, Mo, Cs, Y, V, Ga, La, U, Th, Nb, W, Sc, Ge, Gd, Yb, Hf, and Ce) was determined by using energy dispersive X-ray fluorescence spectrometry on the basis of previously measured organic matter and carbonates. The optimal measuring variables for the investigated oxides and elements were determined by using five standard reference materials. The carbonated sediment type can be determined on the basis of the highest Sr, Sc, La, Nb, Hf, and Yb concentrations followed with the lowest concentrations of the remaining elements and the negative Ce anomaly. The complexity of the obtained data was also examined by principal component analysis (PCA) and cluster analysis (CA) in the identifying geochemical composition of the surface sediment. Boka Kotorska bay's geographical position, orographical configuration, and hydrographic characteristics influence the geochemistry model of the surface sediment, quite different from the open sea. PMID:26948969

  20. Influence of oxygenation and quality of sediment on the survival of Scolelepis chilensis (Spionidae: Polychaeta in Guanabara Bay, Rio de Janeiro

    Directory of Open Access Journals (Sweden)

    Evelyn Machado Silva

    2013-11-01

    Full Text Available This study aimed to evaluate the tolerance of the polychaete Scolelepis chilensis to variation in oxygenation and sediment to obtain data for environmental impact studies. Individuals were collected at Flamengo Beach, Rio de Janeiro. Favorable combinations of environmental characteristics of Guanabara Bay explain the survival of the organisms, although the introduction of pollutants produces heavily degraded areas. Among the groups of benthic fauna, polychaetes especially play an important role in the functioning and structure of aquatic communities. Scolelepis chilensis is widely distributed due to its morphological characteristics, which allow it to adapt to diverse marine environments. However, this study showed that this polychaete has a high mortality rate under hypoxic conditions, meaning that this species is more sensitive to environments with low oxygen. Furthermore, the mortality rate increases considerably in situations of hypoxia associated with contaminated sediment, indicating that this species is sensitive to environments with contaminated sediment and low oxygen supply. Thus, the intense and continuous input of pollutants could lead to a future deficit of oxygen and extreme anaerobic conditions, which may cause destruction of various marine ecosystems.

  1. Distribution and ecological risk assessment of HCHs and DDTs in surface seawater and sediment of the mariculture area of Jincheng Bay, China

    Science.gov (United States)

    Hu, Yanbing; Sun, Shan; Song, Xiukai; Ma, Jianxin; Ru, Shaoguo

    2015-04-01

    The distribution of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in the surface seawater and sediment of Jincheng Bay mariculture area were investigated in the present study. The concentration of total HCHs and DDTs ranged from 2.98 to 14.87 ng L-1 and were quotient of α-HCH, β-HCH, γ-HCH and δ-HCH to marine species was 0.030, 0.157, 3.008 and 0.008, respectively. It was estimated that the overall probability of adverse biological effect from HCHs was less than 5%, indicating that its risk to seawater column species was low. The threshold effect concentration exceeding frequency of γ-HCH, p, p'-DDD, p, p'-DDE and p, p'-DDT in sediment ranged from 8.3% to 100%, and the relative concentration of the HCH and DDT mixture exceeded their probable effect level in sediment. These findings indicated that the risk to marine benthos was high and potentially detrimental to the safety of aquatic products, e.g., sea cucumber and benthic shellfish.

  2. Sediment Pore Water Ammonium Concentrations in Old Tampa Bay as Determined by the Diffusive Equilibration in Thin Films (DET) Technique

    Science.gov (United States)

    Increased nitrogen loading, associated with rapid human population growth, was thought to be a major driver of Tampa Bay water quality degradation in the decades immediately after the Second World War. Improvements in wastewater treatment in the early 1980s led to marked reductio...

  3. Late Glacial to Holocene Indian Summer Monsoon Variability Based upon Sediment Records Taken from the Bay of Bengal

    Directory of Open Access Journals (Sweden)

    Harunur Rashid

    2011-01-01

    Full Text Available Paleoclimatic records from the Bay of Bengal are rare. We reconstruct the sea-surface temperature (SST and salinity from paired S18O and Mg/Ca measurements in planktonic foraminifera Globigerinoides ruber from the western Bay of Bengal core VM29-19. Our data suggest that SST and seawater S18O (S18Osw were ~3C colder and ~0.6 o/oo depleted, respectively, during the Last Glacial Maximum (LGM compared to the early Holocene. The most enriched S18Osw values were found between 18.2 and 15.6 ka interval. Depleted LGM S18Osw values suggest a wet climate which freshened the Bay of Bengal sea surface. Our data further indicate that the monsoon was stronger in the Bolling/Allerod and weaker in the Younger Dryas periods. The most depleted early Holocene S18Osw values suggest that the monsoon was stronger and wetter resulting in a humid climate. After ~5 ka the Indian summer monsoon weakened significantly, indicating less dilution of the sea surface by the Ganges-Brahmaputra-Meghna outflow and/or less direct rainfall. We hypothesize that the prevailing late Holocene dry climate may have caused the diminishment and subsequent abandonment of the settlements of the great Indus Valley Civilizations. Our Bay of Bengal climate records are consistent with those from the Andaman Sea, corroborating broad regional changes in the Indian summer monsoon during the last 25 ka. The general pattern and timing of monsoon variability in the Bay of Bengal and Andaman Sea seems to parallel the Arabian Sea, Africa, and Asian ice cores and speleothem records suggesting that a common tropical forcing may have induced these abrupt climate changes.

  4. Trace elements, pesticides and PCBs levels in sediments of a bay influenced by anthropogenic activities (Thermaikos bay, N.W. Aegean Sea)

    International Nuclear Information System (INIS)

    Surface sediment samples recovered from the study area over a grid of 13 stations during 1995 were examined for organic carbon, Fe, Cr, Ni, Mn, Zn, Co, Cu, Pb, herbicides, DDTs and polychlorinated biphenyls (PCBs). The organic carbon was obtained according to Gaudette et al. The extraction of the metals was achieved with 2N HCl and the determination of the metal content was performed on a Perkin-Elmer 305B AAS. The pesticides and PCBs after extraction on a Soxhlet apparatus and clean-up on an alumina column were determined by gas chromatography on a Varian 3400 Gas Chromatograph equipped with TSD and ECD

  5. The distribution and speciation of trace metals in surface sediments from the Pearl River Estuary and the Daya Bay, Southern China

    International Nuclear Information System (INIS)

    Surface sediments collected from the Pearl River Estuary (PRE) and the Daya Bay (DYB) were analyzed for total metal concentrations and chemical phase partitioning. The total concentrations of Cr, Cu, Ni, Pb, and Zn in the PRE were obviously higher than those in DYB. The maximum concentrations of trace metals in DYB occurred in the four sub-basins, especially in Dapeng Cove, while the concentrations of these metals in the western side of the PRE were higher than those in the east side. Such distribution pattern was primarily due to the different hydraulic conditions and inputs of anthropogenic trace metals. The chemical partitioning of metals analyzed by the BCR sequential extraction method showed that Cr, Ni, and Zn of both areas were present dominantly in the residual fraction, while Pb was found mostly in the non-residual fractions. The partitioning of Cu showed a significant difference between the two areas.

  6. Reconstructing historical changes in combustion patterns by means of black carbon and PAH evaluation in dated sediments from Guanabara Bay, Rio de Janeiro

    Energy Technology Data Exchange (ETDEWEB)

    Mauad, Cristiane R.; Wagener, Angela de L. R.; Farias, Cassia de O.; Carreira, Renato S.; Godoy, Jose M.; Scofield, Arthur de L., E-mail: angela@puc-rio.b [Pontificia Universidade Catolica do Rio de Janeiro (LABMAM/PUC-Rio), Rio de Janeiro, RJ (Brazil). Departamento de Quimica. Lab. de Estudos Marinhos e Ambientais; Ruiz, Naira M. S.; Menezes, Sonia M.C. de [Centro de Pesquisas e Desenvolvimento Leopoldo A. Miguez de Melo (CENPES/PETROBRAS), Rio de Janeiro, RJ (Brazil); Vasconcelos, Crisogono [Laboratory of Geomicrobiology, ETH/Zuerich, Zuerich (Switzerland)

    2013-11-15

    The accumulation history of combustion products from the metropolitan area around Guanabara Bay was evaluated using black carbon and polycyclic aromatic hydrocarbons as indicators. BC concentration varied between 0.23 and 0.51%, with an increasing mass accumulation tendency over the last 118 years, whereas a decrease in the values of the ratio BC/organic carbon was observed in the upper sediment layers, probably reflecting the enhancement of bay's eutrophication process in the last 30 years. Higher concentrations of pyrolytic PAH were observed between 1925 and 1976, being consistent with the subsequent deforestation, urbanization, and industrialization that occurred in the Guanabara basin in the period. These PAHs were best characterized by the BFl/(BFl+BePy) diagnostic ratio. The data obtained allowed the characterization of the main events that influenced the combustion patterns in the region: burning of biomass and fossil fuel, economic crisis of 1970 and 1990 and the introduction of ethanol in the Brazilian energetic matrix. (author)

  7. Thirty years of coral reef change in relation to coastal construction and increased sedimentation at Pelekane Bay, Hawaiʻi

    Directory of Open Access Journals (Sweden)

    Yuko Stender

    2014-03-01

    Full Text Available Coral reefs are being critically impacted by anthropogenic processes throughout the world. Long term monitoring is essential to the understanding of coral reef response to human impacts and the effectiveness of corrective management efforts. Here we reevaluated a valuable coral reef baseline established in Pelekane Bay, Hawaiʻi during 1976 and subsequently resurveyed in 1996. During this time interval substantial impacts occurred followed by extensive corrective measures. Coral and fish communities showed dramatic declines from 1977 to 1996 due to massive harbor construction and suboptimal land management practices on the watershed. More recently, corrective measures in the form of watershed stabilization and fishing regulations have been implemented. Consequently our 2012 survey reveals that coral cover since 1996 has increased slightly accompanied by a significant increase in fish abundance, diversity, and evenness. This improvement can be attributed to lower fishing pressure since 1996 due to reduced shoreline access, tighter fishing regulations and increased monitoring of legal and illegal fishing activities. Stabilization of the coral community can be attributed partially to reduced sedimentation resulting from watershed restoration that included installation of sediment check dams, control of feral ungulates, controlled grazing and replanting of native vegetation. Insights into the mechanism that removes sediment from reefs was provided by a major storm event and a tsunami that remobilized and flushed out sediment deposits. The increase in herbivorous fishes probably played a role in reducing algal competition in favor of corals. The data suggest that the precipitous reef decline in this area has been arrested and offers support for the corrective actions previously undertaken.

  8. Diversity and Abundance of Ammonia-Oxidizing Archaeal Nitrite Reductase (nirK) Genes in Estuarine Sediments of San Francisco Bay

    Science.gov (United States)

    Reji, L.; Lee, J. A.; Damashek, J.; Francis, C. A.

    2013-12-01

    Nitrification, the microbially-mediated aerobic oxidation of ammonia to nitrate via nitrite, is an integral component of the global biogeochemical nitrogen cycle. The first and rate-limiting step of nitrification, ammonia oxidation, is carried out by two distinct microbial groups: ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA). Molecular ecological studies targeting the amoA gene have revealed the abundance and ubiquity of AOA in terrestrial as well as aquatic environments. In addition to the ammonia oxidation machinery that includes the amoA gene, AOA also encode a gene for copper-containing nitrite reductase (nirK). The distribution patterns and functional role of nirK in AOA remain mostly unknown; proposed functions include the indirect involvement in ammonia oxidation through the production of nitric oxide during nitrite reduction, and (2) nitrite detoxification. In the present study, the diversity and abundance of archaeal nirK genes in estuarine sediments were investigated using quantitative polymerase chain reaction, cloning and sequencing approaches. In sediment samples collected from the San Francisco Bay estuary, two archaeal nirK variants (AnirKa and AnirKb) were amplified using specific primer sets. Overall, AnirKa was observed to be significantly more abundant than AnirKb in the sediment samples, with variation in relative abundance spanning two to three orders of magnitude between sampling sites. Phylogenetic analysis revealed a number of unique archaeal nirK sequence types, as well as many that clustered with sequences from previous estuarine studies and cultured AOA isolates, such as Nitrosopumilus maritimus. This study yielded new insights into the diversity and abundance of archaeal nirK genes in estuarine sediments, and highlights the importance of further investigating the physiological role of this gene in AOA, as well as its suitability as a marker gene for studying AOA in the environment.

  9. Determination of chronological heavy metal deposition and pollution intensity in the bottom sediments of Mumbai Harbour Bay, India using 137Cs as tracer

    International Nuclear Information System (INIS)

    Downcore variation of trace metals in sediment cores along the coastal line is one of the markers to assess the intrusion of industrial pollutants into the aquatic environment. Fifty sediment core samples from the Mumbai Harbour Bay (MHB), were studied for the trace element content. MHB is a recipient of effluents from different industries situated all along its coast around Thane-Belapur region. The average concentrations of Titanium (Ti), Manganese (Mn), Iron (Fe), Nickel (Ni), Copper (Cu), Zinc (Zn) were determined by inductively coupled plasma-optical emission spectroscopy and complemented by analysing with energy dispersive X-ray fluorescence spectrometry. In addition to this, depth profiles of K and Ca were also studied to assess the homogeneity of the geological strata of the region. Trace metals such as Cu, Ni and Zn show enrichment between 16 to 28 cm, whereas, uniform distribution through out the core was observed for K, Ca, Ti, Mn and Fe. Chronology of the heavy metal deposition was predicated based on the average sedimentation rate (0.92 ± 0.08 cm year-1) derived using depth-wise 137Cs concentration profile in core of bottom sediment. The results of the analysis showed that MHB had received excess inputs of Cu, Ni and Zn in the year 1981, 1988 and 1982, respectively. Surface concentration of Cu, Ni, Zn and Fe compared to the reference site indicates moderate pollution in the recent years whereas for elements K, Ca, Ti and Mn, the values are normal indicating MHB unpolluted for the latter elements. (author)

  10. Major and trace element geochemistry of Bay of Bengal sediments: Implications to provenances and their controlling factors

    Digital Repository Service at National Institute of Oceanography (India)

    Tripathy, G.R.; Singh, S.K.; Ramaswamy, V.

    ,2,*, Sunil Kumar Singh1 and V Ramaswamy2 1Geosciences Division, Physical Research Laboratory, Ahmedabad-380009, India 2National Institute of Oceanography, Dona Paula, Goa-403004, India *Corresponding Author: grtripathy@gmail.com Keywords: Bay... of these rivers to the global drainage area underscoring the important role of physical erosion in these river basins on the global sedimentary budget. Further, the erosion patterns of these river basins and their spatio-temporal variations have received...

  11. Sediment grab data from June 1995 in the inland bays of New York/New Jersey Harbor

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sediment grab samples were collected using a Shipek grab at pre-determined locations in the harbor. Grain size distributions and organic content were measured and...

  12. Coupling between suboxic condition in sediments of the western Bay of Bengal and southwest monsoon intensification: A geochemical study

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Mir, I.A.; Parthiban, G.; Karapurkar, S.G.; Matta, V.M.; Naidu, P.D.; Naqvi, S.W.A.

    , particularly redox- sensitive elements, in the sediments have been used extensively to reconstruct redox conditions in the bottom water at the time of deposition (Brumsack, 1980; Wignall and Myres, 1988, Calvert and Pedersen, 1993; Dean et al., 1999...

  13. Amino acid biogeochemistry and bacterial contribution to sediment organic matter along the western margin of the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, L.; Garg, A.; Borole, D.V.

    influence burial of organic carbon (Cowie and Hedges, 1992; Burdige, 2007). OM buried in the marine sediments forms a major link between the "active" surface pools of carbon and inactive and/or slow cycling carbon pools (Burdige, 2007). In the open ocean... preserved in the marine sediments (Keil et al., 2000; Vandewiele et al., 2009). Moreover, natural occurrence and geochemical behavior of amino acids have been evaluated in several types of samples (Cowie and Hedges, 1992; Gupta and Kawahata, 2000...

  14. Authigenic 10Be/9Be ratios and 10Be-fluxes (230Thxs-normalized) in central Baffin Bay sediments during the last glacial cycle: Paleoenvironmental implications

    Science.gov (United States)

    Simon, Quentin; Thouveny, Nicolas; Bourlès, Didier L.; Nuttin, Laurence; Hillaire-Marcel, Claude; St-Onge, Guillaume

    2016-05-01

    Authigenic 10Be/9Be ratios and 10Be-fluxes reconstructed using the 230Thxs normalization, proxies of the cosmogenic radionuclide 10Be production rate in the atmosphere, have been measured in a sedimentary core from Baffin Bay (North Atlantic) spanning the last 136 ka BP. The normalization applied on the exchangeable (authigenic) 10Be concentrations using the authigenic 9Be isotope and 230Thxs methods yield equivalent results strongly correlated with sedimentological parameters (grain-size and mineralogy). Lower authigenic beryllium (Be) concentrations and 10Be/9Be ratios are associated with coarse-grained carbonate-rich layers, while higher authigenic Be values are related to fine-grained felspar-rich sediments. This variability is due to: i) sediment composition control over beryllium-scavenging efficiency and, ii) glacial history that contributed to modify the 10Be concentration in Baffin Bay by input and boundary scavenging condition changes. Most paleo-denudation rates inferred from the 10Be/9Be ratio vary weakly around 220 ± 76 tons.km-2.yr-1 (0.09 ± 0.03 mm.yr-1) corresponding to relatively steady weathering fluxes over the last glacial cycle except for six brief intervals characterized by sharp increases of the denudation rate. These intervals are related to ice-surging episodes coeval with Heinrich events and the last deglaciation period. An average freshwater flux of 180.6 km3.yr-1 (0.006 Sv), consistent with recent models, has been calculated in order to sustain glacially-derived 10Be inputs into Baffin Bay. It is concluded that in such environments, the authigenic 10Be measured mainly depends on climatic effects related to the glacial dynamics, which masks the 10Be production variation modulated by geomagnetic field changes. Altogether, these results challenge the simple interpretation of 10Be-concentration variation as a proxy of Interglacial/Glacial (interstadial/stadial) cycles in Arctic and sub-Arctic regions. They rather suggest the effect

  15. Numerical simulation of the Tohoku-oki tsunami and implications for the tsunami sedimentation in the offshore, nearshore and onshore of Sendai Bay

    Science.gov (United States)

    Sugawara, D.; Goto, K.; Imamura, F.

    2012-12-01

    The 11th March 2011 Tohoku-oki earthquake tsunami struck the Pacific coast of northeast Japan, and reached maximum run-up of 40 m at the rocky ria coast and maximum inundation distance around 4-5 km in the flat coastal plains, causing more than 19,000 dead and missing, and massive impacts on the societies. The tsunami heights have been investigated at more than 5,000 locations. Numbers of tsunami source models have been proposed during these 17 months, based on the geodetic, seismic and tide records, as well as the measured tsunami heights. Extensive field surveys have been carried out in the coastal plains of Sendai Bay, where the sandy beach ridges are developed along the coastline, and a lot of new findings on sedimentary feature of tsunami deposits have been obtained. For example, previous researches reported that the sandy tsunami deposits were found to be distributed only 60% of the inundation distance, in case the tsunami invaded more than 3 km from the coastline. Small contribution of marine materials to onshore tsunami deposits was inferred from the micropaleontological and geochemical analysis. These findings will be applied to develop the framework for deposit-based estimation of paleotsunami magnitude and to establish the identification criteria of paleotsunami deposit. In this regard, increase of our understanding of relationship between tsunami hydrodynamics and sedimentation is essential to further advance of tsunami researches. Numerical simulations are a powerful tool to investigate the generation, propagation and inundation process of tsunamis, and to analyze its relevance to sediment transport and deposition. The simulations provide temporal and spatial variation of flow depths and speeds. In case of the Tohoku-oki tsunami, numbers of observational data and video footages are applicable for validation of the simulated results. In this presentation, the tsunami sedimentation by the Tohoku-oki event will be discussed from the viewpoint of numerical

  16. A summary of chemical and biological testing of proposed disposal of sediment from Richmond Harbor relative to the Deep Off-Shelf Reference Area, the Bay Farm Borrow Area, and the Alcatraz Environs Reference Area

    Energy Technology Data Exchange (ETDEWEB)

    Mayhew, H.L.; Karle, L.M.; Gruendell, B.D.; Pinza, M.R. [Battelle/Marine Sciences Lab., Sequim, WA (United States)

    1993-12-01

    The US Army Corps of Engineers was authorized to dredge Richmond Harbor to accomodate large, deep-draft vessels. An ecological evaluation of the Harbor sediments was performed describing the physical characteristics, toxic substances, effects on aquatic organisms,and potential for bioaccumulation of chemical contaminants. The objective of this report is to compare the sediment chemistry, acute toxicity, and bioaccumulation results of the Richmond Harbor sediments to each of the reference areas; i.e., the Deep Off-Shelf Reference Area, the Bay Farm Borrow Area, and the Alcatraz Environs Reference Area. This report will enable the US Army Corps of Engineers to determine whether disposal at a reference area is appropriate for all or part of the dredged material from Richmond Harbor. Chemical analyses were performed on 30 sediment samples; 28 of those samples were then combined to form 7 composites. The seven composites plus sediment from two additional stations received both chemical and biological evaluations.

  17. In situ microscale variation in distribution and consumption of O2: A case study from adeep ocean margin sediment (Sagami Bay, Japan)

    DEFF Research Database (Denmark)

    Glud, Ronnie Nøhr; Stahl, Henrik; Berg, Peter;

    2009-01-01

    A transecting microprofiler documented a pronounced small-scale variation in the benthic O2 concentration at 1450-m water depth (Sagami Bay, Japan). Data obtained during a single deployment revealed that within a sediment area of 190 cm2 the O2 penetration depth varied from 2.6 mm to 17.8 mm...... increased the average diffusive O2 uptake by a factor of 1.26 6 0.06. Detailed 2D calculations on the volume-specific O2 consumption exhibited high variability. The oxic zone was characterized by a mosaic of sediment parcels with markedly different activity levels. Millimeter- to centimeter-sized ‘‘hot...... spots’’ with O2 consumption rates up to 10 pmol cm23 s21 were separated by parcels of low or insignificant O2 consumption. The variation in aerobic activity must reflect an inhomogeneous distribution of electron donors and suggests that the turnover of material within the oxic zone to a large extent was...

  18. Historical records from dated sediment cores reveal the multidecadal dynamic of the toxic dinoflagellate Alexandrium minutum in the Bay of Brest (France).

    Science.gov (United States)

    Klouch, Khadidja Z; Schmidt, Sabine; Andrieux-Loyer, Françoise; Le Gac, Mickaël; Hervio-Heath, Dominique; Qui-Minet, Zujaila N; Quéré, Julien; Bigeard, Estelle; Guillou, Laure; Siano, Raffaele

    2016-07-01

    The multiannual dynamic of the cyst-forming and toxic marine dinoflagellate Alexandrium minutum was studied over a time scale of about 150 years by a paleoecological approach based on ancient DNA (aDNA) quantification and cyst revivification data obtained from two dated sediment cores of the Bay of Brest (Brittany, France). The first genetic traces of the species presence in the study area dated back to 1873 ± 6. Specific aDNA could be quantified by a newly developed real-time PCR assay in the upper core layers, in which the germination of the species (in up to 17-19-year-old sediments) was also obtained. In both cores studied, our quantitative paleogenetic data showed a statistically significant increasing trend in the abundance of A. minutum ITS1 rDNA copies over time, corroborating three decades of local plankton data that have documented an increasing trend in the species cell abundance. By comparison, paleogenetic data of the dinoflagellate Scrippsiella donghaienis did not show a coherent trend between the cores studied, supporting the hypothesis of the existence of a species-specific dynamic of A. minutum in the study area. This work contributes to the development of paleoecological research, further showing its potential for biogeographical, ecological and evolutionary studies on marine microbes. PMID:27162179

  19. Evaluating local and regional scales of environmental change from sediment characteristics of a tributary of the upper Chesapeake Bay: a geospatial approach to understanding the role of humans on elemental transport and fate

    Science.gov (United States)

    Krahforst, C.; Hartman, S.; Eisen-Cuadra, A.; Bruce, S.; Sherman, L.; Kehm, K.

    2013-12-01

    Most of our coastal systems have experienced changes in ecosystem quality due to increased anthropogenic activities, often resulting in the degradation of water and habitat quality. Estuaries are often the first of marine systems that experience these changes. The distribution of trace elements (V, Cr, Cu, Ni, Pb, As, Sn, Ag, Zn, and Cd) and other sediment characteristics in surface sediments and sediment cores from the Chester River - an estuary located in a predominantly agricultural watershed of the upper Chesapeake Bay, USA - is being determined in order to add to the understanding of contaminant transport and fate and evaluate the likelihood for success of strategies designed to meet or improve the ecological condition of estuaries. The high amount of suspended sediment in the Chester River (10-20 mg L-1) is an important factor controlling water quality conditions and a prime focus for environmental management. Sources of suspended mater and its elemental composition are the result of local runoff, atmospheric deposition, local resuspension, and exchange with the Chesapeake Bay. Preliminary results from multivariate analytic and geospatial mapping analyses of sediment surface grabs display significant covariance with Al for many of the elements investigated which may indicate limited exogenic sources of contamination for of sediments of this watershed. For example total Pb sediment concentrations were mostly below the NOAA's low toxic effects level (94%) and appear to be dominated by crustal weathering or from accelerated soil erosion (Pb vs. Al, r2 = 0.84). These analyses, coupled with sequential leaching of elements from these sediments, sediment organic carbon, activities of selected radionuclides of sediment cores and main stem water quality surveys provide added information of the roles of local land use and region scale processes on ecosystem condition and may direct future management for improving environmental quality of estuaries.

  20. Geochemical characterization of the Krishna–Godavari and Mahanadi offshore basin (Bay of Bengal) sediments: A comparative study of provenance

    Digital Repository Service at National Institute of Oceanography (India)

    Mazumdar, A.; Kocherla, M.; Carvalho, M.A.; Peketi, A.; Joshi, R; Mahalaxmi, P.; Joao, H.M.; Jisha, R

    and sub-sampling The coring operation (NGHP-EXP1-3 B, 5C and 18A) was carried out using conventional coring systems including the IODP’s Advanced Piston Corer (APC) and the Extended Core Barrel (XCB). Both systems collect cores approximately 9.6 m long...-G and Mahanadi sediments, respectively. The Fe2O3 vs TiO2 plot (Fig. 4B) defines two distinct fields for K-G and Mahanadi sediments. The TiO2 concentrations for K-G and Mahanadi sediments are 0.88-1.95 wt% (avg: 1.3 wt %) and 0.6-1.0 wt% (avg: 0.9 wt...

  1. Contaminants in sediment, food-chain biota, and bird eggs from the Newport Bay watershed, Orange County, California.

    Science.gov (United States)

    Santolo, Gary M; Byron, Earl R; Ohlendorf, Harry M

    2016-02-01

    Groundwater-related discharges in the San Diego Creek/Newport Bay watershed in Orange County, California have the potential to adversely affect the surface waters within the watershed and would likely not comply with the established total maximum daily loads (TMDLs) for the watershed. In 2004 and 2005, we studied the concentrations of contaminants of TMDL concern (particularly selenium [Se]) in birds that are at risk of exposure to contaminated food items because they feed and nest in the Newport Bay watershed. Most bioaccumulation is from elevated Se in groundwater downstream of a historic terminal swamp. Se bioaccumulation was observed in all biota tested, and DDE was found in fish and bird egg samples. Effects of contaminants on fish and birds are inconclusive due to the management disturbances in the watershed (e.g., flood control) and lack of bird nesting habitat. Although a significant relationship was observed between DDE concentrations and eggshell thinning in American avocet (Recurvirostra americana) eggs, the shell thinning in avocet and other species examined was not enough to result in hatching failure. Further focused monitoring efforts will be needed to characterize the exposure and risk levels. PMID:26803663

  2. 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.

    ruled out the penins u lar river source to the middle fan during mid - Holocene. In contrast, Sha s- tri et al . 9 concluded that the transportation of sediments is from shelf to slope to deeper western Be n gal Fan. In view of the above, we pla n...

  3. Sediment dispersal during ne monsoon over northern Bay of Bengal: Preliminary results using IRS-P4 OCM data

    Digital Repository Service at National Institute of Oceanography (India)

    Anuradha, T.; Suneethi, J.; Dash, S.K.; Pradhan, Y.; Prasad, J.S.; Rajawat, A.S.; Nayak, S.R.; Chauhan, O.S.

    waters. These sediments appear to sink along the coastal stretches of southern Orissa and Northern A.P. It has also been observed development of offshore curl in the deeper waters. This curl enhances with an increase in the width and augmentation...

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

    Science.gov (United States)

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

  5. Seasonal sediment transport pathways in Lirquen Harbor, Chile, as inferred from grain-size trends Patrones estacionales de transporte de sedimentos en puerto Lirquén, Chile, inferidos mediante el análisis de las tendencias granulométricas

    Directory of Open Access Journals (Sweden)

    Felipe Ríos

    2002-01-01

    Full Text Available Bottom sediment samples were collected in June and December 1997 at 166 stations on a rectangular grid in a small port (Lirquén Harbor, BíoBío Region, Central Southern Chile facing siltation problems with a view to determining local seasonal sediment transport pathways through the application of three different methodologies based on grain-size trends. Measured winds and near-bottom currents together with hindcast wave allowed to establishing the influence of the prevailing meteorological and hydrodynamic conditions on local sediment circulation. The results suggest that transport of deep and shallow water sediments occur rarely under high-energy conditions. The current data suggest that tidal asymmetry would be an important agent of sediment transport in Lirquen Harbor. The sediment transport pathways inferred from grain-size trends are compared with the measured water circulation of the study area and sediment dispersal patterns on aerial photographs. The results yielded by the grain-size trend methodologies of Gao-Collins (1992 and Le Roux (1994b indicate a possible seasonal variation in transport pathways agreeing with the prevailing meteo-hydrodynamic conditions, whereas the McLaren-Bowles (1985 approach does not show a significant difference. It is suggested that the latter methodology may represent transport on a spatial macroscale as opposed to the mesoscale patterns yielded by the other two techniques. Based on the results of the three grain-size trend methodologies, the observed current and wind data, the hindcast wave data and aerial photographs a conceptual model of net annual sediment transport is proposed for Lirquén HarbourEn junio y diciembre de 1997 se realizaron dos campañas de muestreo sedimentológico en un puerto afectado por el embancamiento (Puerto Lirquén, Región del Biobío, Chile con el fin de determinar la circulación sedimentaria del área de estudio a través de la aplicación de tres metodologías basadas en

  6. Assessment of Total Suspended Sediment Distribution under Varying Tidal Conditions in Deep Bay: Initial Results from HJ-1A/1B Satellite CCD Images

    Directory of Open Access Journals (Sweden)

    Liqiao Tian

    2014-10-01

    Full Text Available Using Deep Bay in China as an example, an effective method for the retrieval of total suspended sediment (TSS concentration using HJ-1A/1B satellite images is proposed. The factors driving the variation of the TSS spatial distribution are also discussed. Two field surveys, conducted on August 29 and October 26, 2012, showed that there was a strong linear relationship (R2 = 0.9623 between field-surveyed OBS (optical backscatter measurements (5-31NTU and laboratory-analyzed TSS concentrations (9.89–35.58 mg/L. The COST image-based atmospheric correction procedure and the pseudo-invariant features (PIF method were combined to remove the atmospheric effects from the total radiance measurements obtained with different CCDs onboard the HJ-1A/1B satellites. Then, a simple and practical retrieval model was established based on the relationship between the satellite-corrected reflectance band ratio of band 3 and band 2 (Rrs3/Rrs2 and in-situ TSS measurements. The R2 of the regression relationship was 0.807, and the mean relative error (MRE was 12.78%, as determined through in-situ data validation. Finally, the influences of tide cycles, wind factors (direction and speed and other factors on the variation of the TSS spatial pattern observed from HJ-1A/1B satellite images from September through November of 2008 are discussed. The results show that HJ-1A/1B satellite CCD images can be used to estimate TSS concentrations under different tides in the study area over synoptic scales without using simultaneous in-situ atmospheric parameters and spectrum data. These findings provide strong informational support for numerical simulation studies on the combined influence of tide cycles and other associated hydrologic elements in Deep Bay.

  7. Chronic sublethal effects of San Francisco Bay sediments on Nereis (neanthes) arenaceodentata: Non treatment factors. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Moore, D.W.; Dillon, T.M.

    1992-09-01

    Initial development of a chronic sublethal sediment bioassay with the polychaete Nereis (Neanthes) arenaceodentata is described. The test was initiated with 2 to 3-week-old postemergent juvenile worms and terminated after 21 days. The sublethal test end point was estimated individual somatic growth rate (milligrams dry weight/day). The potential bias due to selected nontreatment factors on polychaete survival and growth was evaluated. For example, grain size had no effect, while the number of worms added to each exposure vessel was critical. Direct transfer from 30 ppt to salinities < or = ppt had a highly significant and adverse effect on survival and growth. Both survival and growth of juvenile worms may be adversely affected if test conditions involve exposures to > or = mg/L ammonia or > or = mg/L hydrogen sulfide.... Chronic, Growth, Neanthes, Sediment, Sublethal.

  8. Heavy metals in Mercenaria mercenaria and sediments from the New Bedford Harbor region of Buzzard's Bay, Massachusetts

    Energy Technology Data Exchange (ETDEWEB)

    Genest, P.E. (Southeastern Massachusetts Univ., North Dartmouth); Hatch, W.I.

    1981-01-01

    M. mercenaria and sediments from the New Bedford region were analyzed for cadmium, copper, iron, lead, and zinc to investigate some of the relationships between environmental and organismal levels. It appears that at present there is no major contamination of clams or sediments in the areas studied. However, since levels of some metals approached the permissible limits at times, it would obviously be beneficial if all sources of pollution to the area could be identified and regulated. It is suggested that harvesting of clams could be managed seasonally so that tissue contaminants are at their periodic minima. For these metals late summer, fall, and winter appear to be favorable times. It is also suggested that clams harvested in the vicinity of recently dredged areas be monitored for heavy metal levels. The need for a continuous monitoring program for heavy metals and other toxic substances for New Bedford and surrounding areas to insure public safety is recommended.

  9. Presence of surfactants and their degradation intermediates in sediment cores and grabs from the Cadiz Bay area

    International Nuclear Information System (INIS)

    The occurrence and distribution of the major surfactants - LAS, AES, APEOs and AEOs - and their degradation intermediates - SPCs, AP and APECs - in a marine-estuarine environment at Spain are presented. Results show that their concentration in surface sediments is clearly correlated with their usage and the existence of wastewater discharges. The degradation processes appear to lead to the formation of SPCs in the case of LAS, and to the shortening of the average ethoxylated chain length in the case of NPEOs, AEOs and AES. Vertical profiles for AEOs and AES are reported for the first time and present the highest values nearest the surface, followed by a sharp decrease with depth for all surfactants, as well as the appearance of degradation intermediates in deeper sedimentary layers. Shorter LAS homologues and SPCs tend to be present in pore water while strongly non-polar intermediates like NP are firmly attached to the sediments. -- The presence of vertical and longitudinal distribution of the major surfactants and their intermediates in sediments and pore water is reported for the first time

  10. More than a century of bathymetric observations and present-day shallow sediment characterization in Belfast Bay, Maine, USA: Implications for pockmark field longevity

    Science.gov (United States)

    Brothers, L.L.; Kelley, J.T.; Belknap, D.F.; Barnhardt, W.A.; Andrews, B.D.; Maynard, M.L.

    2011-01-01

    Mechanisms and timescales responsible for pockmark formation and maintenance remain uncertain, especially in areas lacking extensive thermogenic fluid deposits (e.g., previously glaciated estuaries). This study characterizes seafloor activity in the Belfast Bay, Maine nearshore pockmark field using (1) three swath bathymetry datasets collected between 1999 and 2008, complemented by analyses of shallow box-core samples for radionuclide activity and undrained shear strength, and (2) historical bathymetric data (report and smooth sheets from 1872, 1947, 1948). In addition, because repeat swath bathymetry surveys are an emerging data source, we present a selected literature review of recent studies using such datasets for seafloor change analysis. This study is the first to apply the method to a pockmark field, and characterizes macro-scale (>5 m) evolution of tens of square kilometers of highly irregular seafloor. Presence/absence analysis yielded no change in pockmark frequency or distribution over a 9-year period (1999-2008). In that time pockmarks did not detectably enlarge, truncate, elongate, or combine. Historical data indicate that pockmark chains already existed in the 19th century. Despite the lack of macroscopic changes in the field, near-bed undrained shear-strength values of less than 7 kPa and scattered downcore 137Cs signatures indicate a highly disturbed setting. Integrating these findings with independent geophysical and geochemical observations made in the pockmark field, it can be concluded that (1) large-scale sediment resuspension and dispersion related to pockmark formation and failure do not occur frequently within this field, and (2) pockmarks can persevere in a dynamic estuarine setting that exhibits minimal modern fluid venting. Although pockmarks are conventionally thought to be long-lived features maintained by a combination of fluid venting and minimal sediment accumulation, this suggests that other mechanisms may be equally active in

  11. Evaluation of the activity concentration of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb in sediments from Antarctica in the Admiralty Bay region

    Energy Technology Data Exchange (ETDEWEB)

    Mora, Tamires de A.; Oliveira, Joselene de, E-mail: tamires.mora@usp.br, E-mail: jolivei@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); 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

    In this study, we performed the radiochemical characterization of a sedimentary record (1B profile), collected in the vicinity of Admiralty Bay, King George Island in Antarctic Operation XXXI (January/2013). The activities of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb were determined by the counting of gross alpha and gross beta activities in the precipitates of Ba(Ra)SO{sub 4} and PbCrO{sub 4}. Those measurements were carried out in a low background gas flow proportional detector. The {sup 226}Ra and {sup 228}Ra were measured after 21 days of the final precipitation. The {sup 210}Pb activity was determined after 10 days of the precipitation date by gross beta counting of its {sup 210}Bi decay product. The activity concentration of {sup 226}Ra ranged from 11±1 (mBq g-1) to 54±3 (mBq g{sup -1}), and the {sup 228}Ra ranged from 48±5 (mBq g{sup -1}) to 155±16 (mBq g{sup -1}). The activity concentration of {sup 210}Pb varied from 8±1 (mBq g{sup -1}) to 458±46 (mBq g{sup -1}), while unsupported {sup 210}Pb ranged from 6±1 (mBq g{sup -1}) to 434±65 (mBq g{sup -1}). The {sup 210}Pb concentrations in sediments have often been used to dating events like deposition and accumulation in various marine environments. Taking into account the results of {sup 210}Pb and {sup 226}Ra activities obtained in testimony-1B it was estimated the unsupported {sup 210}Pb activity which was applied to the CIC geochronological dating model (Constant Initial Concentration). Based in these data, the sedimentation rate obtained was 0.63±0.02 cm year{sup -1}. (author)

  12. Anthropogenic impact on the sedimentation in coastal regions: an example in Saco do Bracui - Ribeira Bay, Angra dos Reis, Brazil

    International Nuclear Information System (INIS)

    The Saco do Bracui, located in the littoral zone of the Brazilian southeast, receives run off from the region of Angra dos Reis. Anthropological intervention in this area has modified local morphology during the last 40 years. These modifications include an intense deforestation of mangrove regions, construction of the Bracui Boat Yard, the dredging of part of the draining basin and development of the coastal plain. Results from seismic surveys identify three different stratigraphic units separated by two reflectors as well as Holocenic paleodeltas and paleochannels of the Bracui and Gratau rivers. Results from this study and previous work indicate an age of 6800 years for the top of the superior unit. Areal photographs from the years 1964, 1965, 1978 and 1991 reveal the principal modifications occurring during the last 40 years in the area. Field observations from this study as well as bathymetric profiles based on the nautical maps of 1980 and 1944 reveal shoaling and erosion areas in the Saco do Bracui. Sedimentation rates, using lead-210 profiles, are between 0,17 - 1,90 cm/year and lead-210 inventory values are between 16-6-dpm/cm2/year. The results for sedimentation rate and inventory show a high accumulation around Bracui, Gratau and Frade mouth rivers and agree with results from the bathymetric profiles with respect to the site of erosion and shoaling in the Saco do Bracui. The results for grain size and lead-210 analyses support the idea that the Saco do Bracui is suffering shoaling processes in specific sites and erosion in others. Comparison between long term sedimentation rates obtained by seismic results and short term rates obtained by lead-210 shows an increase of the sedimentary discharge in the 1960's, when the intense anthropological intervention in the area began. (author)

  13. Sr–Nd isotope composition of the Bay of Bengal sediments: Impact of climate on erosion in the Himalaya

    Digital Repository Service at National Institute of Oceanography (India)

    Tripathy, G.R.; Singh, S.K.; Bhushan, R.; Ramaswamy, V.

    using Sr-Nd isotopes (France-Lanord et al., 1993; Colin et al., 1999; Pierson-Wickmann et al., 2001; Ahmad et al., 2005; Kessarkar et al., 2005; Galy et al., 2008). Over Ma time scale, the sources of sediments to the BoB have remained roughly the same... since the Miocene (Bouquillon et al., 1990; France-Lanord et al., 1993). The sources are dominated by contributions from the Higher Himalaya (HH) with subordinate supply from the Lesser Himalaya (LH). However, on millennial timescale...

  14. Inversion of suspended sediment concentration at the Hangzhou Bay based on the high-resolution satellite HJ-1A/B imagery

    Science.gov (United States)

    Meng, Qinghui; Mao, Zhihua; Huang, Haiqing; Shen, Yuzhang

    2013-09-01

    HJ-1A/B were two small satellite constellations, that were launched for the environment and disaster monitoring and forecasting on September 6th, 2008. Based on the advantages of high temporal and spacial resolution of the HJ CCD data, this paper aims at evaluate four inversion algorithms of suspended sediments concentration by the remote sensing reflectance in the Hangzhou Bay. First, the atmospheric correction of HJ-1 A/B CCD imagery was carried out using fast line-of-sight atmospheric analysis of spectral hypercubes (FLAASH) model, in which aerosol optical depth was retrieved from synchronous Terra/MODIS data. Then, four classical band ratio algorithms were evaluated. Results show that He's GOCI model was better than others with 12.75% relative error. At last, we compare the discrepancy between He's GOCI algorithm and any other three model, results indicate that the other three empirical algorithms performance not very good because of the difference come from different satellite data, various study area, different research season, distinct correction result. This research has an important practical significance to improving the SSC inversion in the HZB.

  15. Carbon and Sulfur Isotopic Composition of Yellowknife Bay Sediments: Measurements by the Sample Analysis at Mars (SAM) Quadrupole Mass Spectrometer

    Science.gov (United States)

    Franz, H. B.; Mahaffy, P. R.; Stern, J. C.; Eigenbrode, J. L.; Steele, A.; Ming, D. W.; McAdam, A. C.; Freissinet, C.; Glavin, D. P.; Archer, P. D.; Brunner, A. E.; Grotzinger,J. P.; Jones, J. H.; Leshin, L. A.; Miller, K.; Morris, R. V.; Navarro-Gonzalez, R.; Niles, P. B.; Owen, T. C.; Summons, R. E.; Sutter, B.; Webster, C. R.

    2014-01-01

    Since landing at Gale Crater in Au-gust 2012, the Sample Analysis at Mars (SAM) instru-ment suite on the Mars Science Laboratory (MSL) “Curiosity” rover has analyzed solid samples from the martian regolith in three locations, beginning with a scoop of aeolian deposits from the Rocknest (RN) sand shadow. Curiosity subsequently traveled to Yellowknife Bay, where SAM analyzed samples from two separate holes drilled into the Sheepbed Mudstone, designated John Klein (JK) and Cumberland (CB). Evolved gas analysis (EGA) of all samples revealed the presence of H2O as well as O-, C- and S-bearing phas-es, in most cases at abundances below the detection limit of the CheMin instrument. In the absence of definitive mineralogical identification by CheMin, SAM EGA data can help provide clues to the mineralogy of volatile-bearing phases through examination of tem-peratures at which gases are evolved from solid sam-ples. In addition, the isotopic composition of these gas-es may be used to identify possible formation scenarios and relationships between phases. Here we report C and S isotope ratios for CO2 and SO2 evolved from the JK and CB mudstone samples as measured with SAM’s quadrupole mass spectrometer (QMS) and draw com-parisons to RN.

  16. 乐清湾养殖区表层沉积物重金属含量分布及污染评价%Distribution and pollution assessment of heavy metals in surface sediments of aquaculture area in Yueqing bay

    Institute of Scientific and Technical Information of China (English)

    王传花; 崔灵周; 王栋

    2015-01-01

    Yueqing bay is one of the key sea farming areas in Zhejiang province. Because of the rapid development of coastal economy, large quantities of industrial and agricultural wastewater and domestic sewage have been discharged into Yueqing bay. The environmental reports by the local government state that water quality of Yueqing bay has degraded since 1980s, which has caused a serious threat to the sustainable development of mariculture and coastal ecology. Sediments are sinks of various pollutants and inversely affect water quality. But there are lacks in understanding on heavy metals and other pollutants in sediments. In order to understand the current situation of environment pollution and carry out heavy metal pollution assessment to providing reference for pollution remediation, we studied the pollution of heavy metals including copper (Cu), cadmium (Cd), chromium (Cr), lead (Pb), zinc (Zn), mercury (Hg) and arsenic (As) in surface sediment of mariculture area in Yueqing bay. Based on field investigation, 10 samples of surface sediment were collected in typical aquaculture area. By using atomic fluorescence spectrometer (AFS-930) and atomic absorption spectrometer (AA240Fs), heavy metal contents of the surface sediment samples were determined. According to standard value of the first class in China Marine Sediment Quality Standard (GB18668-2002), single factor index method, nemerow comprehensive pollution index method and sediment quality guideline method were used to evaluate pollution degree of individual heavy metal, integrated pollution effects of several heavy metals and potential biological toxicity risk of heavy metal. The results showed that contents of Cu, Cr, Pb and Zn in sampling point S1 were the highest, which were 69.0, 74.0, 36.7 and 190.0 mg/kg respectively. The highest content values of Cd, As and Hg were 0.30, 26.6 and 0.82 mg/kg from sampling points S9 and S5 respectively. Variation coefficient of Hg content was 0.77, which was the highest and

  17. Trace metal content in sediments and autochthonous intertidal organisms from two adjacent bays near Ushuaia, Beagle Channel (Argentina).

    Science.gov (United States)

    Duarte, Claudia Alejandra; Giarratano, Erica; Gil, Mónica N

    2012-08-01

    The aim of this work was to monitor levels of Cd, Cu, Pb, Zn and Fe in sediments, mussels (Mytilus edulis chilensis) and limpets (Nacella magellanica) from the Industrial zone (IZ); fuel dock (FD) and Ushuaia Peninsula (UP) on the Beagle Channel. In sediments, seasonal variations showed high values of Cu and Pb in spring and Zn in autumn. Comparing among sites, Cd concentration was superior in UP (2.07 μg/g); while Pb was maximum in FD (41.00 μg/g). In mussels, a higher bioaccumulation in winter was found. Mussels from UP showed the highest bioaccumulation of Cu (5.95 μg/g) and those from FD presented the highest of Zn (170.15 μg/g). A seasonal trend was not found for limpets, while differences among sites were observed for Cd being the highest at IZ (3.02 μg/g). Although pollution level found was low, anthropic activities at the studied sites could result in deterioration, further monitoring is recommended. PMID:22681905

  18. National Uranium Resource Evaluation Program. Hydrogeochemical and stream sediment reconnaissance basic data for Green Bay NTMS Quadrangle, Wisconsin

    International Nuclear Information System (INIS)

    Field and laboratory data are presented for 695 groundwater samples, 546 stream sediment samples, and 401 stream water samples. Statistical and areal distributions of uranium and other possibly uranium-related variables are displayed. A generalized geologic map of the survey area is provided, and pertinent geologic factors which may be of significance in evaluating the potential for uranium mineralization are briefly discussed. Greater than 85th percentile concentrations of uranium in all sample types define an area of about 2,000 km2 (780 mi2) in the central and north central portions of the survey area as the most probable area for potential uranium mineralization within the quadrangle. Bedrock of the area includes granitic and monzonitic batholiths of Precambrian age. A 500 km2 area is also outlined by uranium in groundwater samples coincident with a Precambrian fault-shear zone in Marathon County. Anomalous uranium concentrations occur in stream sediments from Marathon, Wood, and Portage Counties; however, other associated variables suggest that the uranium is associated with refractory minerals which are less favorable for commercial potential. Concentrations of uranium above the 85th percentile are also found in Waushara, Winnebago, Outagamie, and Shawano Counties within the area of Cambrian sandstone and Prairie du Chien outcrop. Groundwater and stream water representing the Sinnipee and Ancell Rock Groups, and the Richmond and Silurian Formations are characterized by high conductivity, calcium, magnesium, sulfate, total alkalinity, and pH, but moderate to low concentrations of uranium

  19. Sediment dynamics and the burial and exhumation of bedrock reefs along an emergent coastline as elucidated by repetitive sonar surveys: Northern Monterey Bay, CA

    Science.gov (United States)

    Storlazzi, C.D.; Fregoso, T.A.; Golden, N.E.; Finlayson, D.P.

    2011-01-01

    Two high-resolution bathymetric and acoustic backscatter sonar surveys were conducted along the energetic emergent inner shelf of northern Monterey Bay, CA, USA, in the fall of 2005 and the spring of 2006 to determine the impact of winter storm waves, beach erosion, and river floods on biologically-important siliclastic bedrock reef habitats. The surveys extended from water depths of 4 m to 22 m and covered an area of 3.14 km2, 45.8% of which was bedrock, gravel, and coarse-grained sand and 54.2% was fine-grained sand. Our analyses of the bathymetric and acoustic backscatter data demonstrates that during the 6 months between surveys, 11.4% of the study area was buried by fine-grained sand while erosion resulted in the exposure of bedrock or coarse-grained sand over 26.5% of the study area. The probability of burial decreased with increasing water depth and rugosity; the probability of exhumation increased with increasing wave-induced near-bed shear stress, seabed slope and rugosity. Much of the detected change was at the boundary between bedrock and unconsolidated sediment due to sedimentation and erosion burying or exhuming bedrock, respectively. In a number of cases, however, the change in seabed character was apparently due to changes in sediment grain size when scour exposed what appeared to be an underlying coarser-grained lag or the burial of coarser-grained sand and gravel by fine-grained sand. These findings suggest that, in some places, (a) burial and exhumation of nearshore bedrock reefs along rocky, energetic inner shelves occurs over seasonal timescales and appears related to intrinsic factors such as seabed morphology and extrinsic factors such as wave forces, and (b) single acoustic surveys typically employed for geologic characterization and/or habitat mapping may not adequately characterize the geomorphologic and sedimentologic nature of these types of environments that typify most of the Pacific Ocean and up to 50% of the world's coastlines.

  20. Seasonal mercury concentrations and {delta}{sup 15}N and {delta}{sup 13}C values of benthic macroinvertebrates and sediments from a historically polluted estuary in south central Chile

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Jaramillo, Mauricio, E-mail: mdiazjaramillo@conicet.gov.ar [Aquatic Systems Research Unit, EULA Chile Environmental Sciences Centre, Universidad de Concepcion (Chile); Munoz, Claudia; Rudolph, Ignacio [Aquatic Systems Research Unit, EULA Chile Environmental Sciences Centre, Universidad de Concepcion (Chile); Servos, Mark [Department of Biology, University of Waterloo, ON (Canada); Barra, Ricardo [Aquatic Systems Research Unit, EULA Chile Environmental Sciences Centre, Universidad de Concepcion (Chile)

    2013-01-01

    The Lenga Estuary is one of the most industrialized sites in south central Chile where the historic operation of chlor-alkali plants resulted in large quantities of mercury (Hg) being deposited into the estuary. This historical contamination may still represent a risk to the biota in the estuary. To investigate this four macroinvertebrates, Neotrypaea uncinata (ghostshrimp), Elminius kingii (barnacle), Hemigrapsus crenulatus (shore crab) and Perinereis gualpensis (ragworm) were collected seasonally from three different sites in the Lenga Estuary and one in a reference estuary (Tubul Estuary), and analyzed for Hg and stable isotopes ({delta}{sup 15}N and {delta}{sup 13}C). Mercury concentrations in Lenga sediments ranged from 0.4 {+-} 0.1 to 13 {+-} 3 mg/kg, while those in Tubul sediments ranged from 0.02 {+-} 0.01 to 0.07 {+-} 0.09 mg/kg. Total Hg concentrations of invertebrates were significantly different between estuaries (p < 0.05), but not by species or season for each estuary (p > 0.05). In contrast, organic Hg concentrations were different by species and season with shore crab muscle tissues exhibiting the greatest percent difference. Site-specific relationships demonstrated that total Hg concentrations in ragworm best reflected the total Hg sediment mercury concentrations. Signatures of {delta}{sup 13}C were correlated to the organic Hg % rather than total Hg. This suggests that organic Hg concentrations in these species were related to the carbon sources. -- Highlights: Black-Right-Pointing-Pointer Hg in sediments and biota from Lenga Estuary were elevated compared to nearby estuary. Black-Right-Pointing-Pointer Invertebrates showed interspecific and seasonal differences in terms of organic Hg %. Black-Right-Pointing-Pointer Total Hg levels in the ragworm best reflect Hg sediment gradient in Lenga Estuary. Black-Right-Pointing-Pointer Interspecific variation in {delta}{sup 13}C signatures indicated different feeding modes. Black

  1. Anthropization in Montevideo Bay during the Holocene

    International Nuclear Information System (INIS)

    This work is about the anthropogenic historic impacts in subtidal environments in Montevideo Bay. The studies carried out in the sediments enable to conclude that the increase of the industrial discharges (nutrients, heavy metals) are the cause of the chemical changes in the sediment of the Montevideo Bay

  2. An experimental study on dredge spoil of estuarine sediments in the bay of seine (France): A morphosedimentary assessment

    Science.gov (United States)

    Marmin, Stella; Lesueur, Patrick; Dauvin, Jean Claude; Samson, Sandrine; Tournier, Patrice; Gallicher Lavanne, Albert; Dubrulle-Brunaud, Carole; Thouroude, Coralie

    2016-03-01

    Studies on the consequences of dredging on estuarine morphology and its sedimentary dynamics are common, but the impacts of dumping dredge spoil in coastal open settings are rarely found in scientific literature. An experimental study was conducted over the period 2012-2013 to monitor the physical impacts of dredged material dumped at two adjacent sites (one million cubic metres at each) on the inner shelf of the Bay of Seine in France (eastern part of the English Channel, La Manche). As recently reinforced in the EU Marine Strategy Framework Directive (MSFD), knowledge on the location and intensity of human impacts (e.g. on marine ecosystems) is critical for effective marine management and conservation. So, two methods of disposition were tested to evaluate the impacts of dumping on the environment and thus propose recommendations for future dumping. The strategy is based on a Before-After-Control-Impact (BACI) approach, in which the spatio-temporal variability was studied by analysing the morphological and sedimentological characteristics over a period of 28 months, from November 2011 to April 2014, also including recovery of the seafloor after cessation of the dumping activities. The first experimental dumping operation (MASED) was carried out regularly for 8 months at a single point and generating a conical deposit of 5 m in height, while the second dumping (MABIO) lasted for 12 months involving four steps in the dumping process. In the second case, a wider area was covered, leading to the formation of a smaller deposit of 2 m in height. The dumped deposits consisted of muddy fine sand, whereas the inner shelf seafloor in this area is covered with fine to medium sand. As a result, muddy fine sand accumulated at or near the two dumping sites, with a maximum mud (i.e. particles4 Φ) content of 50% compared to<5% before dumping operations. Videos obtained from a LVB200 Seabotix ROV, highlighted the heterogeneity of the sea floor around the dumping areas. Due to

  3. 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)

    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

  4. Concentration of polybrominated diphenyl ethers (PBDEs) in sediment cores of Sundarban mangrove wetland, northeastern part of Bay of Bengal (India)

    Energy Technology Data Exchange (ETDEWEB)

    Binelli, Andrea [Department of Biology, University of Milan, Via Celoria 26, 20133 Milan (Italy)]. E-mail: andrea.binelli@unimi.it; Sarkar, Santosh Kumar [Department of Marine Science, University of Calcutta, 35 Ballygunge Circular Road, Calcutta 700 019 (India); Chatterjee, Mousumi [Department of Marine Science, University of Calcutta, 35 Ballygunge Circular Road, Calcutta 700 019 (India); Riva, Consuelo [Department of Biology, University of Milan, Via Celoria 26, 20133 Milan (Italy); Parolini, Marco [Department of Biology, University of Milan, Via Celoria 26, 20133 Milan (Italy); Bhattacharya, Bhaskar deb [Department of Marine Science, University of Calcutta, 35 Ballygunge Circular Road, Calcutta 700 019 (India); Bhattacharya, Asok Kumar [Department of Marine Science, University of Calcutta, 35 Ballygunge Circular Road, Calcutta 700 019 (India); Satpathy, Kamala Kanta [Indira Gandhi Center for Atomic Research, Environmental and Industrial Safety Section, Safety Group, Kalpakkam 603 102, Tamil Nadu (India)

    2007-08-15

    The paper presents the first comprehensive survey of congener profiles (12 congeners) of polybrominated diphenyl ethers (PBDEs) in core sediment samples (<63 {mu}m) covering seven sites in Sundarban mangrove wetland (India). Gas-chromatographic analyses were carried out in GC-Ms/Ms for tri- to hepta- brominated congeners. Results pointed out a non-homogenous contamination of the wetland with {sigma}{sub 12} PBDE values ranging from 0.08 to 29.03 ng g{sup -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.

  5. Characterization and phylogenetic analysis of novel polyene type antimicrobial metabolite producing actinomycetes from marine sediments:Bay of Bengal India

    Institute of Scientific and Technical Information of China (English)

    Valan; Arasu; M; Asha; KRT; Duraipandiyan; V; Ignacimuthu; S; Agastian; P

    2012-01-01

    Objective:To isolate and indentify the promising antimicrobial metabolite producing Streptomyces strains from marine sediment samples from Andraprudesh coast of India.Methods:Antagonistic aetinomycetes were isolated by starch casein agar medium and modified nutrient agar medium with 1%glucose used as a base for primary screening.Significant antimicrobial metabolite producing strains were selected and identified by using biochemical and 16S rDNA level.Minimum inhibitory concentrations of the organic extracts were done by using broth micro dilution method.Results:Among the 210 actinomyeetes,64.3%exhibited activity against Gram positive bacteria,48.5%showed activity towards Cram negative bacteria,38.8%exhibited both Cram positive and negative bacteria and 80.85%isolates revealed significant antifungal activity.However,five isolates AP-5,AP-18,AP-41 and AP-70 showed significant antimicrobial activity.The analysis of cell wall hydrolysates showed the presence of LL-diaminopimelic acid and glycine in all the isolates.Sequencing analysis indicated that the isolates shared 98.5%-99.8%sequence identity to the 16S rDNA gene sequences of the Streptomyces taxons.The antimicrobial substances were extracted using hexane and ethyl acetate from spent medium in which strains were cultivated at 30X for five days.The antimicrobial activity was assessed using broth micro dilution technique.Each of the culture extracts from these five strains showed a typical polyenelike property.The lowest minimum inhibitory concentrations of ethyl acetate extracts against Escherichia coli and Cumularia lunula were 67.5 and 125.0μg/mL,respectively.Conclusions:It can be concluded that hexane and ethyl acetate soluble extracellular products of novel isolates are effective against pathogenic bacteria and fungi.

  6. Benthic foraminifera distribution in high polluted sediments from Niterói Harbor (Guanabara Bay, Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    Claudia G. Vilela

    2004-03-01

    Full Text Available Dockyards and harbors are recognized as being important locations where sediment-associated pollutants can accumulate, which constitutes an environmental risk to aquatic life due to potential uptake and accumulation of heavy metals in the biota. The aim of this paper is to assess the concentrations and the effects of some heavy metals in the benthic foraminifera assemblage in Niterói Harbor. Low concentrations in the benthic foraminifera as well as the dominance of indicative species such as Ammonia tepida, Buliminella elegantissima and Bolivina lowmani can be associated with an environment under stress. In addition, the occurrence of test abnormalities among foraminifera may represent a useful biomarker for evaluating long-term environmental impacts in a coastal region.Estaleiros e portos são locais reconhecidamente importantes onde poluentes associados a sedimentos podem acumular, constituindo um risco ambiental para a vida aquática devido ao potencial de captação e acumulação de metais pesados na biota. O propósito deste trabalho é avaliar as concentrações e os efeitos de alguns metais pesados na assembléia de foraminíferos bentônicos no Porto de Niterói. Baixas concentrações de foraminíferos bentônicos bem como a dominância de espécies indicativas como Ammonia tepida, Buliminella elegantissima e Bolivina lowmani podem ser associadas a um ambiente sob estresse. A ocorrência de anormalidades entre os foraminíferos pode representar um útil biomarcador para avaliação de impactos ambientais de longo termo em uma região costeira.

  7. ISOLATION AND DIVERSITY OF ACTINOMYCETES IN THE CHESAPEAKE BAY

    Science.gov (United States)

    Chesapeake Bay was investigated as a source of actinomycetes to creen for production of novel bioactive compounds. he presence of relatively large populations of actinoplanetes, chemotype IID actinomycetes in Chesapeake Bay sediment samples indicates that is an eminently suitable...

  8. Algae Reefs in Shark Bay, Western Australia, Australia

    Science.gov (United States)

    1990-01-01

    Numerous algae reefs are seen in Shark Bay, Western Australia, Australia (26.0S, 113.5E) especially in the southern portions of the bay. The south end is more saline because tidal flow in and out of the bay is restricted by sediment deposited at the north and central end of the bay opposite the mouth of the Wooramel River. This extremely arid region produces little sediment runoff so that the waters are very clear, saline and rich in algae.

  9. Application of a Weighted Regression Model for Reporting Nutrient and Sediment Concentrations, Fluxes, and Trends in Concentration and Flux for the Chesapeake Bay Nontidal Water-Quality Monitoring Network, Results Through Water Year 2012

    Science.gov (United States)

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

    2016-01-01

    In the Chesapeake Bay watershed, estimated fluxes of nutrients and sediment from the bay’s nontidal tributaries into the estuary are the foundation of decision making to meet reductions prescribed by the Chesapeake Bay Total Maximum Daily Load (TMDL) and are often the basis for refining scientific understanding of the watershed-scale processes that influence the delivery of these constituents to the bay. Two regression-based flux and trend estimation models, ESTIMATOR and Weighted Regressions on Time, Discharge, and Season (WRTDS), were compared using data from 80 watersheds in the Chesapeake Bay Nontidal Water-Quality Monitoring Network (CBNTN). The watersheds range in size from 62 to 70,189 square kilometers and record lengths range from 6 to 28 years. ESTIMATOR is a constant-parameter model that estimates trends only in concentration; WRTDS uses variable parameters estimated with weighted regression, and estimates trends in both concentration and flux. WRTDS had greater explanatory power than ESTIMATOR, with the greatest degree of improvement evident for records longer than 25 years (30 stations; improvement in median model R2= 0.06 for total nitrogen, 0.08 for total phosphorus, and 0.05 for sediment) and the least degree of improvement for records of less than 10 years, for which the two models performed nearly equally. Flux bias statistics were comparable or lower (more favorable) for WRTDS for any record length; for 30 stations with records longer than 25 years, the greatest degree of improvement was evident for sediment (decrease of 0.17 in median statistic) and total phosphorus (decrease of 0.05). The overall between-station pattern in concentration trend direction and magnitude for all constituents was roughly similar for both models. A detailed case study revealed that trends in concentration estimated by WRTDS can operationally be viewed as a less-constrained equivalent to trends in concentration estimated by ESTIMATOR. Estimates of annual mean flow

  10. Sediment Quality of the SW Coastal Laizhou Bay, Bohai Sea, China: A Comprehensive Assessment Based on the Analysis of Heavy Metals

    OpenAIRE

    Gao, Xuelu; Zhuang, Wen; Chen, Chen-Tung Arthur; Zhang, Yong

    2015-01-01

    Historically, the Bohai Sea is one of the most important fishing grounds in China. Yet, surrounded by one of the biggest economic rims of China, its ecological functions have been declining rapidly in recent two decades under the heavy anthropogenic impacts. The Laizhou Bay is the smallest one of the three main bays in the Bohai Sea. Owing to the rich brine deposits, chemical industries using brine as raw materials are booming in the southern coast of the Laizhou Bay, the scale of which ranks...

  11. The bacterial community of coastal sediments influenced by cage culture in Xiangshan Bay, Zhejiang, China%象山港网箱养殖对近海沉积物细菌群落的影响

    Institute of Scientific and Technical Information of China (English)

    裘琼芬; 张德民; 叶仙森; 郑珍珍

    2013-01-01

    Microorganisms play important roles in biogeochemical cycling such as organic matter decomposition and energy transformation. Recently, rapid development of aquaculture has caused a large influx of introduced organic matter into Xiangshan Bay, Zhejiang Province, China. At the same time, many ecological problems have developed in this coastal site. Study of the influence of aquaculture on microbial diversity in sediments is important for the structural and functional assessment of coastal ecosystems. In this paper, sediments in three sites were investigated in July 2011: a control or check site ( CK) , an intersection site 6-8 km from the aquaculture site (IS ) , and a cage culture site ( AC ). As the physicochemical background showed, total organic carbon in those three sites was different. Several physiochemical factors (T, pH, Eh and SO2-4 ) were analyzed. The temperatures of sediments in Xiangshan Bay decreased with depth, but remained between 23.0-26.5℃ in the upper 55 cm layer. The pH of sediments was slightly alkaline, but was elevated slightly in the AC site, although all of the sediments had pH values of 7.6-7.9. The effect of aquaculture on SO2-4 was not significant. However, as expected, the measurement of Eh showed sediment in the CK site had the highest oxidation-reduction potential. Following with physiochemical analysis, the structure and diversity of bacterial communities in sediments from Xiangshan Bay were analyzed by Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis and cloning/sequencing. Total nucleic acids was extracted from the sediment core, T-RFLP analysis was conducted after amplification of the bacterial 16S rRNA partial gene using a fluorescent primer pair 27-FAM/907R and digestion by Msp I (C'CGG). A bacterial 16S rRNA partial gene clone library was constructed using DNA extracted from the upper 5 cm sediment layer of the CK region, and the phylogenic relationships were analyzed using the neighbor-joining method in

  12. Trace Elements and oil-related contaminants in sediment, bivalves, and eelgrass from Padilla and Fidalgo Bays, Skagit County, Washington, 1988

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Padilla Bay is a tidal estuary in Puget Sound, Washington with extensive eelgrass beds and mudflats. The estuary is an important natural resource which provides...

  13. Sediment Sample Locations Collected in May 2014 from Barnegat Bay, New Jersey (U.S. Geological Survey Field Activity Number 2014-310-FA)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Barnegat Bay, located along the eastern shore of New Jersey, was significantly impacted by Hurricane Sandy in October 2012. Scientists from the U.S. Geological...

  14. Gamma spectroscopy data for box core sediments collected from Barnegat Bay, New Jersey in May 2014 (U.S. Geological Survey Field Activity Number 2014-310-FA)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Barnegat Bay, located along the eastern shore of New Jersey, was significantly impacted by Hurricane Sandy in October 2012. Scientists from the U.S. Geological...

  15. Barnegat Bay surface and subsurface sediment physical parameters data from May 2014 (U.S. Geological Survey Field Activity Number 2014-310-FA)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Barnegat Bay, located along the eastern shore of New Jersey, was significantly impacted by Hurricane Sandy in October 2012. Scientists from the U.S. Geological...

  16. Distribution of biochemical constituents in the surface sediments of western coastal Bay of Bengal: Influence of river discharge and water column properties

    Digital Repository Service at National Institute of Oceanography (India)

    Kumar, B.S.K.; Sarma, V.V.S.S.; Krishna, M.S.

    of discharged water and associated biogeochemical processes in the water column. The northwest (NW) region of coastal Bay of Bengal was influenced by discharges from Ganges river while peninsular (monsoonal) rivers influenced the southwest (SW) region. The NW...

  17. MEJORAMIENTO DE TRIGOS HARINEROS (Triticum aestivum L. EN LA ZONA CENTRO SUR DE CHILE: CONTENIDO Y PRODUCCIÓN DE PROTEINA, Y VOLUMEN DE SEDIMENTACIÓN EN TRIGOS INVERNALES, ALTERNATIVOS Y PRIMAVERALES Genetic improvement of bread wheat (Triticum aestivum L. in the South Central zone of Chile: Protein content, production and sedimentation volume of winter, alternative and spring wheats

    Directory of Open Access Journals (Sweden)

    Mario Mellado Z.

    2001-04-01

    Full Text Available Se realizaron cuatro experimentos de campo con diez variedades de trigos de invierno y hábito alternativo (grupo 1, y cuatro experimentos con once variedades de trigos de primavera (grupo 2, para evaluar el porcentaje y producción de proteína del grano, y el volumen de sedimentación. Los genotipos fueron desarrollados en el Proyecto de Mejoramiento de Trigo del Instituto de Investigaciones Agropecuarias (INIA, Centro Regional de Investigación Quilamapu. Lilifén fue la primera variedad mejorada en el grupo 1, y Mexifén en el grupo 2; por lo tanto ambas fueron usadas como referencia. Los experimentos se llevaron a cabo en suelos Andisoles del Campo Experimental Santa Rosa (INIA, Chillán, Chile, desde el año 1995 a 1998. Los porcentajes medios de proteína de las variedades de los grupos 1 y 2 fueron 9,6 %, y 10,8%, respectivamente. El promedio de producción de proteína de las variedades del grupo 1 fue 894,6 kg ha-1 mientras que en el grupo 2 este valor fue 968,4 kg ha-1. Los valores medios para sedimentación fueron 3,4 mL en el grupo 1 y 4,3 mL en el grupo 2. En relación a las variedades, los resultados demostraron que el trabajo de mejoramiento de trigo realizado entre 1968 y 1993 fue más exitoso en mejorar el contenido de proteína del grano que su calidadFour field experiments with ten winter and alternative varieties (group 1 and four experiments with eleven spring wheat varieties (group 2, were carried out to assess grain protein percentage, grain production and sedimentation volume. The tested genotypes were developed at the Quilamapu Wheat Breeding Program, Institute of Agricultural Research, INIA. Lilifen was the first breed variety improved in group 1, and Mexifen in group 2; as such both were used as references. The experiments were carried out in Andisoil soils at the Santa Rosa Experimental Field, Chillán, Chile, from 1995 to 1998. The mean protein percentage of varieties of groups 1 and 2 were 9.6 and 10

  18. The role of sediment composition and behavior under dynamic loading conditions on slope failure initiation: a study of a subaqueous landslide in earthquake-prone South-Central Chile

    Science.gov (United States)

    Wiemer, Gauvain; Moernaut, Jasper; Stark, Nina; Kempf, Philipp; De Batist, Marc; Pino, Mario; Urrutia, Roberto; de Guevara, Bruno Ladrón; Strasser, Michael; Kopf, Achim

    2015-07-01

    Subaqueous slope failure mechanisms are still poorly understood partly because they are difficult to study due to the remote location of submarine landslides. Landslides in lakes are smaller in size and more readily accessible and therefore represent a good alternative to their marine counterparts. Lake Villarrica, located in South-Central Chile, experienced significant slope failure and serves here as an exemplary study area for subaqueous landslide initiation mechanisms in tectonically active settings. Coring and CPTU testing were undertaken with the MARUM free-fall CPTU deployed adjacent to the coring sites where all lithological units involved in the slope failure were sampled. Using geotechnical methods such as pseudo-static factor of safety analysis and cyclic triaxial testing, three types of soils (i.e., diatomaceous ooze, volcanic ash, and quick clay) were analyzed for their role in slope failure, and earthquake shaking was identified as the primary trigger mechanism. The investigated landslide consisted of two distinct phases. During the first phase, slope failure was initiated above a tephra layer. In the second phase, retrogression led to the shoreward extension of the slide scarp along a second failure plane located in a stratigraphically deeper, extremely sensitive lithology (i.e., quick clay). Results show that liquefaction of buried tephra layers was unlikely, but such layers might still have contributed to a reduction in shear strength along the contact area with the neighboring sediment. Furthermore, cyclic shaking-induced pore pressure in diatomaceous ooze may be similar to that in granular soils. We generally infer that failure mechanisms observed in this study are equally important for landslide initiation in submarine settings as diatomaceous ooze intercalated with volcanic ash may be abundantly present along active continental margins.

  19. Community structure of the macroinfauna in the sediments below an intertidal mussel bed (Mytilus chilensis (Hupe of southern Chile Estructura comunitaria de la macroinfauna en los sedimentos bajo un banco intermareal de bivalvos (Mytilus chilensis (Hupe en el sur de Chile

    Directory of Open Access Journals (Sweden)

    CRISTIAN DUARTE

    2006-09-01

    two separate from that of the other stations (i.e. located outside the mussel bed. Results of ANOVA showed significant differences for all sediment variables, with the exception of percentages of gravel particles and mean grain size of sands. The most noticeable difference was that shown by station 1 (lower contents of sand and higher content of mud, biogenic aggregates and total organic matter. The results of BIO-ENV routine showed that the best fit between the taxonomic composition of the macroinfauna and single sediment variables, was reached with percentages of sand and mud. It is concluded, that mussel beds of sedimentary bottoms of southern Chile have a significant role on the sediment quality and community structure of the macroinfauna, a probable combined effect of physiological processes (ingestion of larvae, biodeposition and the complex physical matrix of the bedEl bivalvo Mytilus chilensis (Hupe puede formar densos bancos en áreas sedimentarias de la costa protegida de los archipiélagos norpatagónicos de la costa de Chile (ca. 40-43º S. Durante el otoño del 2002, se recolectaron muestras replicadas en cinco estaciones en la zona intermareal de Panitao (Golfo de Reloncaví a lo largo de un transecto paralelo a la línea de marea baja y extendido desde el centro de un banco de bivalvos (estaciones uno y dos con 100 y ca. 25 % de cobertura, respectivamente hasta una zona libre de bivalvos (estaciones tres, cuatro y cinco. La macroinfauna estuvo dominada numéricamente por los grupos Polychaeta, Olygochaeta y Crustacea Peracarida. El número total de especies recolectadas fue 14, siendo las más abundantes el poliqueto Perinereis vallata, oligoquetos de la familia Tubificidae y el crustáceo anfípodo Corophium insidiosum. El número de especies, el índice de diversidad de Shannon-Wiener y la abundancia total de la macroinfauna no presentaron diferencias significativas entre las estaciones de muestreo. Sin embargo, la contribución porcentual de los

  20. Late Holocene precipitation variability recorded in the sediments of Reloncaví Fjord (41°S, 72°W), Chile

    Science.gov (United States)

    Rebolledo, Lorena; Lange, Carina B.; Bertrand, Sébastien; Muñoz, Práxedes; Salamanca, Marco; Lazo, Pablo; Iriarte, José L.; Vargas, Gabriel; Pantoja, Silvio; Dezileau, Laurent

    2015-07-01

    We present reconstructions of late Holocene changes in the source of organic matter and siliceous export production in the Relocanví Fjord (41°S, 72°W), Northern Chilean Patagonia, based on organic carbon content, δ13Corg, N/C ratio, diatom assemblages and biogenic silica contents from three sediment cores. The age models are based on a combination of 210Pb profiles, AMS 14C dating, and on the first occurrence of the diatom Rhizosolenia setigera f. pungens, as a stratigraphic marker in the fjords. The cores span the last 300 to 700 yr. Diatoms dominate the siliceous assemblages in the three cores (98% on average). Our results suggest that precipitation seasonality in the region of Reloncaví was high in CE 1300-1400 and CE 1700-1850, with a clear decreasing trend since CE 1850. The latter trend is in agreement with instrumental records and tree-ring reconstructions. These fluctuations seem to be associated with the Southern Annular Mode (SAM).

  1. Extracting Length and Time Scales of Downstream Suspended Transport from Sediment Budget Data: ~100 to 1000-yr Travel Times from the Appalachians to the Chesapeake Bay, U.S.A

    Science.gov (United States)

    Pizzuto, J. E.; Schenk, E.; Hupp, C. R.; Gellis, A.; Noe, G. B.; Williamson, E.; Karwan, D. L.; O'Neal, M. A.; Marquard, J.; Aalto, R. E.; Newbold, J. D.

    2013-12-01

    Watershed Best Management Practices (BMPs) are often designed to reduce loadings of sediments and particle-borne contaminants, but the temporal lag between BMP implementation and improvement in receiving water quality is difficult to assess because particles spend long periods in storage between transport events. Here we present a theory that describes the downstream movement of suspended sediment particles accounting for the time particles spend in storage based on sediment budget data (by grain-size fraction) and information on particle transit times through storage reservoirs. The theory is used to define a suspended-sediment transport-length scale that describes how far particles are carried during transport events, and to estimate a downstream particle velocity that includes time spent in storage. At five upland watersheds of the mid-Atlantic region of the U.S.A., transport-length scales for silt-clay range from 3.5-76.1 km, while those for sand range from 0.9-139.6 km. Stratigraphic data and radiometric dating for a typical eroding bank section suggest an averaged sediment transit time through floodplain storage of 488 years. Mean sediment velocities for silt-clay range from 0.0072-0.16 km/yr, while those for sand range from 0.0008-0.25 km/yr, 4 to 6 orders of magnitude slower than the velocity of water in the channel. These results suggest lag times of 100-1000 years between BMP implementation and effectiveness in receiving waters such as the Chesapeake Bay (where BMPs are located upstream of the characteristic transport length scale). Many particles likely travel much faster than these average values, so further