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Sample records for bay sediments chile

  1. Bay sedimentation as controlled by regional crustal behaviour, local tectonics and eustatic sea-level changes: Coquimbo Formation (Miocene Pliocene), Bay of Tongoy, central Chile

    Science.gov (United States)

    Le Roux, J. P.; Olivares, Danisa M.; Nielsen, Sven N.; Smith, Norman D.; Middleton, Heather; Fenner, Juliane; Ishman, Scott E.

    2006-02-01

    The north-facing Bay of Tongoy in central Chile is flanked by topographic highs in the west and east. During the Miocene and Pliocene, the bay extended inland at least 30 km farther south than a present. It was filled with muds, sands, coquinas and gravel during a series of transgressions and regressions related to regional and local tectonic movements combined with global sea-level variations. 87Sr/ 86Sr and microfossil dating indicates transgressions between 11.9-11.2 Ma, 10.1-9.5 Ma, 9.0-7.3 Ma, 6.3-5.3 Ma, 4.3-2.2 Ma and 1.7-1.4 Ma. The regional tectonic behaviour of the crust shows general uplifting from 10.5 Ma to 6.9 Ma, associated with subduction of the Juan Fernández Ridge (JFR) beneath this part of the continent. Subsidence followed between 6.9 and 2.1 Ma, in the wake of the southeastward-migrating JFR. The subsequent subduction of an oceanic plateau similar to the JFR caused rapid uplift that led to the final emergence of the bay above sea level. The Puerto Aldea normal fault along the western limit of the study area was reactivated during the regional uplift and subsidence events, with reverse faulting occurring during the latter phase. Sporadic fault reactivation probably triggered the rapid changes in water depth reflected in the recorded vertical succession of facies.

  2. 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...

  3. Fine Sediment Resuspension Dynamics in Moreton Bay

    Institute of Scientific and Technical Information of China (English)

    YOU Zai-jin; YIN Bao-shu

    2007-01-01

    A comprehensive field study has been undertaken to investigate sediment resuspension dynamics in the Moreton Bay, a large semi-enclosed bay situated in South East Queensland, Australia. An instrumented tripod, which housed three current meters, three OBS sensors and one underwater video camera, was used to collect the field data on tides, currents, waves and suspended sediment concentrations at four sites (Sites 1, 2, 4, and 5) in the bay. Site 1 was located at the main entrance, Site 2 at the central bay in deep water, and Sites 4 and 5 at two small bays in shallow water. The bed sediment was fine sand (d50=0.2 mm) at Site 1, and cohesive sediment at the other three sites. Based on the collected field data, it is found that the dominant driving forces for sediment resuspension are a combination of ocean swell and tidal currents at Site 1, tidal currents at Site 2, and wind-waves at Sites 4 and 5. The critical bed shear stress for cohesive sediment resuspension is determined as 0.079 Pa in unidirectional flow at Site 2, and 0.076 Pa in wave-induced oscillatory flow at Site 5.

  4. Biogenic silicate accumulation in sediments, Jiaozhou Bay

    Institute of Scientific and Technical Information of China (English)

    LI Xuegang; SONG Jinming; DAI Jicui; YUAN Huamao; LI Ning; LI Fengye; SUN Song

    2006-01-01

    It has been widely recognized that low silicate content in seawater is a major limiting factor to phytoplankton primary production in Jiaozhou Bay. However the reason of Si-limitation remains poorly understood. In the present study we measured the biogenic silicate content and discussed the accumulation of silicate in Jiaozhou Bay sediment. The results show that the biogenic silica content in the sediment of the Jiaozhou Bay is obviously much higher than those in the Yellow Sea and the Bohai Sea. The BSi:TN ratios and BSi:16P ratios in the sediment are > 1 and the OC:BSi ratio in sediment is lower than these of Redfield ratio (106:16), indicating that the decomposition rate of OC is much higher than that for BSi in similar conditions. Therefore, the majority of the biogenic silicate was buried and thus did not participate in silicate recycling. Silicate accumulation in sediment may explain why Si limits the phytoplankton growth in the Jiaozhou Bay. Comparing the flux of biogenic silicate from sediments with primary production rate, it can be concluded that only 15.5% of biogenic silicate is hydrolyzed during the journey from surface to bottom in seawater, thus approximate 84.5% of biogenic silicate could reach the bottom. The silicate releasing rate from the sediment to seawater is considerably lower than that of sedimentation of biogenic silicate, indicating silicate accumulation in sediment too. In a word, the silicate accumulation in sediment is the key reason of silicate limiting to phytoplankton growth in Jiaozhou Bay.

  5. 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

  6. 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

  7. Spatial variations of mercury in sediment of Minamata Bay, Japan.

    Science.gov (United States)

    Tomiyasu, Takashi; Matsuyama, Akito; Eguchi, Tomomi; Fuchigami, Yoko; Oki, Kimihiko; Horvat, Milena; Rajar, Rudi; Akagi, Hirokatsu

    2006-09-01

    Mercury-contaminated effluent was discharged into Minamata Bay from a chemical plant over a period of approximately 40 years until 1968. In October 1977, the Minamata Bay Pollution Prevention Project was initiated to dispose of sedimentary sludge containing mercury concentrations higher than 25 mg kg(-1). In March 1990, the project was completed. In an effort to estimate current contamination in the bay, the vertical and horizontal distributions of mercury in sediment were investigated. Sediment core samples were collected on June 26, 2002 at 16 locations in Minamata Bay and Fukuro Bay located in the southern part of Minamata Bay. The sediment in Fukuro Bay had not been dredged. The total mercury concentration in surface sediment was 1.4-4.3 mg kg(-1) (2.9+/-0.9 mg kg(-1), n=9) for the dredged area of Minamata Bay and 0.3-4.8 mg kg(-1) (3.6+/-1.6 mg kg(-1), n=4) for Fukuro Bay. In the lower layers of long cores taken from both areas, the total mercury concentration decreased with depth and finally showed relatively uniform low values. These values can be considered to represent the background concentration absent of anthropogenic influence, which was estimated for the study area to be 0.068+/-0.012 mg kg(-1) (n=10). From the surface, the total mercury concentration in Fukuro Bay increased with depth and reached a maximum at 8-14 cm. In Minamata Bay, several centimeters from the surface the total mercury concentration did not change significantly having considerably higher values than the background level. At six stations, the methylmercury concentration was determined. Although the vertical variations were similar to those for total mercury, Fukuro Bay sediment showed a higher concentration of methylmercury than Minamata Bay sediment.

  8. 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

  9. 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...

  10. Magnetic Characteristics of Surface Sediments of Liaodong Bay, China

    Institute of Scientific and Technical Information of China (English)

    WANG ShuangP; WANG Yonghong; LIU Jian; YU Yiyong

    2015-01-01

    Analysis of magnetic properties of marine surface sediments has been gradually proved to be one of the effective means for researching the source of marine sediments. In this paper, samples from 39 sites in Liaodong Bay were collected to analyze the magnetic characteristics of the surface sediments. Magnetic study indicated that the surface sediments of the Liaodong Bay are char-acterized by magnetite. In the middle and eastern part and the southwest corner of the Bay, the main magnetic grains were coarse multi-domain and pseudo-single-domain particles, while in other areas single-domain and pseudo-single-domain particles constitute the majority. Based on grain size and environmental magnetism data, the content of magnetic minerals has a positive correlation with the hydrodynamic environment when the magnetic mineral domain is finer. However, the content of magnetic minerals is in a complex relationship with the hydrodynamic environment in the coarse magnetic domain of magnetic minerals found in central Liaodong Bay and places outside the Fuzhou Bay, implying that the strong hydrodynamic environment accelerates the sedimentation of coarse magnetic minerals. Based on geographic pattern of magnetic properties, it can be inferred that the main provenance of the surface sediments of the Liaodong Bay is the surrounding rivers, and the comparative analysis indicates that Yellow River substances maybe also exist in the bay.

  11. 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...

  12. Sediments of Buzzards Bay acquired in 1963 (MOORE63 shapefile)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A study of bottom sediment samples from Buzzards Bay, Massachusetts, provides a basis for establishing their major depositional facies and their relationships to the...

  13. 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 exposed...

  14. 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...

  15. Characterization of bottom sediments from Osaka Bay, Japan

    Science.gov (United States)

    Tokunaga, S.; Hoshika, A.; Tatsumoto, H.

    1995-06-01

    The physical, chemical, and dewatering characteristics of 19 bottom sediments from Osaka Bay, Japan, have been analyzed to aid in the development of sediments in the coastal bay area. The sediments in the east near Osaka Port were highly polluted from the influence of human activities and were difficult to dewater. These sediments were composed of fine particles, low in pH, zetapotential, and initial settling rate, and were high in ignition loss, metal concentrations, compression volume, specific resistance, cake water content, and drying index. However, the sediments near Akashi Channel showed the reverse where they are affected by strong tidal current. A correlation analysis has been made of all the parameters. There are significant relationships between all the dewatering parameters. Therefore, sediments difficult to dewater by gravity settling are also difficult to dewater by vacuum filtration and solar evaporation. Sediments containing fine particles and pollutants are difficult to dewater. Several forms of pollutants can occur in the sediments.

  16. 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

  17. Biogeochemical characteristics of nitrogen and phosphorus in Jiaozhou Bay sediments

    Institute of Scientific and Technical Information of China (English)

    LI Xuegang; SONG Jinming; YUAN Huamao; DAI Jicui; LI Ning

    2007-01-01

    Sediment samples were cored from 3 locations representing the inner bay, the outer bay and the bay mouth of Jiaozhou Bay in September 2003 to study the source and biogeochemical characteristics of nitrogen and phosphorus in the bay. The content and vertical distributions of total nitrogen (TN), total phosphorus (TP), organic nitrogen (ON), organic phosphorus (OP), inorganic nitrogen (IN), inorganic phosphorus (IP), the ratio of organic carbon and total nitrogen (OC/TN), and the ratio of total nitrogen and total phosphorus (TN/TP) in the sediments were analyzed. The results show that both TN and TP in surface sediments decrease from the inner bay to the outer bay. In general, ON occupies 50%-70% of TN and IP accounts for more than 60% of TP. In ratio of OC:TN, the nitrogen accumulated in the sediments from the inner bay and the bay mouth came mainly from terrestrial sources, and the portion of autogenetic nitrogen was 28.9% and 13.1%, respectively. However, in the outer bay, nitrogen was mainly autogenetic,accounting for 62.1% of TN, whereas phosphorus was mainly land-derived. The sedimentation fluxes of nitrogen and phosphorus varied spatially. The overall diagenesis rate of nitrogen was higher than that of phosphorus. Specifically, the diagenesis rate of OP was higher than that of IP. However, the diagenesis rate of ON was not always higher than that of IN. In species, the diagenesis rate of IN is sometimes much higher than that of the OC. In various environments, the diagenesis rate is, to some degree, affected by OC, pH, Eh, and Es.

  18. 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.

  19. Beach ridges U-Th dating in Tongoy bay and tectonic implications for a peninsula-bay system, Chile

    Science.gov (United States)

    Saillard, M.; Riotte, J.; Regard, V.; Violette, A.; Hérail, G.; Audin, L.; Riquelme, R.

    2012-12-01

    Along the Chilean coast, peninsulas associated with bays seem to behave as a complex system. They act as barrier to propagation of megathrust earthquakes along strike. To better understand how such a system works from ocean side to more inland, we investigated the area between the Tongoy bay and the Altos de Talinay in northern Chile (˜30°S). It represents a forearc peninsula-bay system in which a normal fault (Puerto Aldea fault) has been described as accommodating a relative vertical motion between the two parts, the peninsula being uplifted with respect to the bay. We dated shells from beach ridges by U-Th disequilibria in order to compare the bay area to the peninsula area for which 10Be dating of wave-cut platforms are available (Saillard et al., 2009). These indicate: (1) the Puerto Aldea fault activity probably ceased since at least ˜230 ka, implying the bay and peninsula parts are evolving together since then; (2) the uplift rate is variable and has decreased from ˜0.8 m/ka to ˜0.2 m/ka between ˜300 and 100 ka.

  20. Suspended sediment and sediment-associated contaminants in San Francisco Bay

    Science.gov (United States)

    Schoellhamer, D.H.; Mumley, T.E.; Leatherbarrow, J.E.

    2007-01-01

    Water-quality managers desire information on the temporal and spatial variability of contaminant concentrations and the magnitudes of watershed and bed-sediment loads in San Francisco Bay. To help provide this information, the Regional Monitoring Program for Trace Substances in the San Francisco Estuary (RMP) takes advantage of the association of many contaminants with sediment particles by continuously measuring suspended-sediment concentration (SSC), which is an accurate, less costly, and more easily measured surrogate for several trace metals and organic contaminants. Continuous time series of SSC are collected at several sites in the Bay. Although semidiurnal and diurnal tidal fluctuations are present, most of the variability of SSC occurs at fortnightly, monthly, and semiannual tidal time scales. A seasonal cycle of sediment inflow, wind-wave resuspension, and winnowing of fine sediment also is observed. SSC and, thus, sediment-associated contaminants tend to be greater in shallower water, at the landward ends of the Bay, and in several localized estuarine turbidity maxima. Although understanding of sediment transport has improved in the first 10 years of the RMP, determining a simple mass budget of sediment or associated contaminants is confounded by uncertainties regarding sediment flux at boundaries, change in bed-sediment storage, and appropriate modeling techniques. Nevertheless, management of sediment-associated contaminants has improved greatly. Better understanding of sediment and sediment-associated contaminants in the Bay is of great interest to evaluate the value of control actions taken and the need for additional controls. ?? 2007 Elsevier Inc. All rights reserved.

  1. 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

  2. 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

  3. 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.

  4. 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

  5. Late Quaternary sedimentation in eastern Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

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

    This study presents variations in various size measures, calcium carbonate, organic carbon, clay mineralogy and major and trace elements in a core (5.40 m long, 2713 m depth) from the eastern Bay of Bengal. On a CM diagram, the sediments of the core...

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

    Science.gov (United States)

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

    2012-04-01

    A study to improve the understanding of the primary sediment sources and transfer pathways in catchments disturbed following forest plantation harvesting is being undertaken in South-Central Chile. The study focuses on two sets of paired experimental catchments (treatment and control), located about 400 km apart, with similar soil type but contrasting mean annual rainfall: Nacimiento (1,200 mm year-1) and Los Ulmos (2,500 mm year-1). Sediment source fingerprinting techniques are being used to document the primary fine sediment sources. In each catchment, three potential sediment sources were defined: clearcut slopes (Z1), forest roads (Z2) and the stream channel (Z3). In each catchment, multiple representative composite samples of the different potential source materials were collected before harvest operations from the upper 1 cm layer in Z1, Z2, and from the channel bank and bed for Z3. A time-integrating trap sampler installed in the discharge monitoring station constructed at the outlet of each catchment has been used to collect samples of the suspended sediment and these have been supplemented by sediment collected from the weir pools. Total suspended sediment load is been quantified in the monitoring stations using discharge records and integrated water sampling. Caesium-137 (137Cs), excess lead-210 (210Pbex) and other sediment properties are being used as fingerprints. After air-drying, oven-drying at 40°C and disaggregation, both the source material samples and the sediment samples collected in the discharge monitoring stations were sieved through a 63-μm sieve and the <63-μm fractions were used for subsequent analyses. For radionuclide assay, the samples were sealed in Petri dishes and after 4 weeks the mass activity density (activity concentration) of 137Cs and 210Pbex was determined by gamma analysis, using an ORTEC extended range Ge detector of 53% relative efficiency. The 137Cs and 210Pbex activity and organic carbon (Corg) concentration associated

  7. Climate Controlled Sedimentation in Maxwell Bay, King George Island, Antarctica

    Science.gov (United States)

    Hass, H.; Kuhn, G.; Wittenberg, N.; Woelfl, A.; Betzler, C.

    2012-12-01

    Climatic change in Antarctica is strongest over the Antarctic Peninsula where in places the annual mean temperatures increased by 0.5 K per decade through the past 60 years. The impact of this warming trend is clearly visible in the form of retreating glaciers and melting ice sheets, loss of sea ice and strong meltwater discharge into the coastal zone. While it is generally accepted that the rapidity of the present climate change bears a significant anthropogenic aspect, it is not clear whether the effects caused by the warming trend are exceptional and unprecedented or whether the reaction of the environment is similar to that of earlier climate phases such as the Medieval Warm Period (MWP) about 1,000 years ago. One of the major goals of the joint international research project IMCOAST is to investigate the strength of the recent warming trend and its impact on the marine environment of the West Antarctic Peninsula (WAP). The study we present here reveals the Upper Holocene climatic history based on high-resolution sediment cores from Maxwell Bay (King George Island, WAP) and information on the actual processes triggered or altered by the recent warming trend based on sedimentologic and hydroacoustic investigations in Potter Cove, a tributary fjord to Maxwell Bay. Long sediment cores from Maxwell Bay reveal grain-size changes that can be linked to cold and warm phases such as the Little Ice Age (LIA) and the MWP. Generally, warm phases are finer grained than cold phases as a result of longer and stronger melting processes during the warm phases. It is suggested that meltwater plumes carry fine-grained sediment out of the surrounding fjords into Maxwell Bay where it settles in suitable areas to produce sediments that have a modal value around 16 μm. This mode is largely absent in sediments deposited during e.g. the LIA. However, post LIA sediments are depleted in the 16 μm-mode sediment suggesting slightly different conditions during the last century. One reason

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

    Energy Technology Data Exchange (ETDEWEB)

    Wade, Terry L. [Geochemical and Environmental Research Group, Texas A and M University, 833 Graham Road, College Station, TX 77845 (United States); Sweet, Stephen T. [Geochemical and Environmental Research Group, Texas A and M University, 833 Graham Road, College Station, TX 77845 (United States)], E-mail: sweet@gerg.tamu.edu; Klein, Andrew G. [Geography Department, Texas A and M University, 814B Eller O and M Building, College Station, TX 77843 (United States)

    2008-04-15

    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.

  9. Fish larvae retention linked to abrupt bathymetry at Mejillones Bay (northern Chile during coastal upwelling events

    Directory of Open Access Journals (Sweden)

    Pablo M Rojas

    2014-11-01

    Full Text Available The influence of oceanic circulation and bathymetry on the fish larvae retention inside Mejillones Bay, northern Chile, was examined. Fish larvae were collected during two coastal upwelling events in November 1999 and January 2000. An elevated fish larvae accumulation was found near an oceanic front and a zone of low-speed currents. Three groups of fish larvae were identified: the coastal species (Engraulis ringens and Sardinops sagax, associated with high chlorophyll-a levels; larvae from the families Phosichthyidae (Vinciguerria lucetia and Myctophidae (Diogenichthys laternatus and Triphoturus oculeus, associated with the thermocline (12°C, and finally, larvae of the families Myctophidae (Diogenichthys atlanticus and Bathylagidae (Bathylagus nigrigenys, associated with high values of temperature and salinity. The presence of a seamount and submarine canyon inside Mejillones Bay appears to play an important role in the circulation during seasonal upwelling events. We propose a conceptual model of circulation and particles retention into Mejillones Bay. The assumption is that during strong upwelling conditions the flows that move along the canyon emerge in the centre of Mejillones Bay, producing a fish larvae retention zone. Understanding the biophysical interactions responsible to trap and/or concentrate particles is essential to protect these fragile upwelling ecosystems.

  10. AMS measurement of 10Be concentrations in marine sediments from Chile Trench at the TANDAR laboratory

    Science.gov (United States)

    Rodrigues, D.; Arazi, A.; Fernández Niello, J. O.; Martí, G. V.; Negri, A. E.; Abriola, D.; Capurro, O. A.; Cardona, M. A.; de Barbará, E.; Gollan, F.; Hojman, D.; Pacheco, A. J.; Samsolo, N.; Togneri, M.; Villanueva, D.

    2017-03-01

    The 10Be/9Be ratios in marine sediments samples from the Southern Chile Trench have been measured using accelerator mass spectrometry (AMS). The samples were measured at the TANDAR accelerator, where the discrimination of the 10Be radionuclides was achieved by means of a passive absorber in front of an ionization chamber. This setup along with the high voltage available, provided a complete suppression of the 10B isobar interference. The obtained values for the 10Be concentrations, of the order of 109 atoms/g, are the first 10Be measurements from the Southern Chile Trench and offer an excellent tracer to quantitatively study the recycling of sediments in Andean magmas.

  11. 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.

  12. Sediment data collected in 2014 from Barnegat Bay, New Jersey

    Science.gov (United States)

    Bernier, Julie C.; Stalk, Chelsea, A.; Kelso, Kyle W.; Miselis, Jennifer L.; Tunstead, Rob

    2016-05-23

    In response to the 2010 Governor’s Action Plan to clean up the Barnegat Bay–Little Egg Harbor (BBLEH) estuary in New Jersey, the U.S. Geological Survey (USGS) partnered with the New Jersey Department of Environmental Protection in 2011 to begin a multidisciplinary research project to understand the physical controls on water quality in the bay. Between 2011 and 2013, USGS scientists mapped the geological and morphological characteristics of the seafloor of the BBLEH estuary using a suite of geophysical tools. However, this mapping effort included only surficial characterization of bay sediments; to verify the sub-surface geophysical data, sediment cores were required.This report serves as an archive of sedimentologic data from 18 vibracores collected from Barnegat Bay between May and August of 2014 by the U.S. Department of Agriculture Natural Resources Conservation Service (NRCS) on behalf of the USGS. The vibracores were collected in conjunction with an ongoing NRCS subaqueous soil survey for the BBLEH estuary. The data presented in this report, including descriptive core logs, core photographs, processed grain-size data, and Geographic Information System (GIS) data files with accompanying formal Federal Geographic Data Committee metadata, can be viewed or downloaded from the Data Products and Downloads page.

  13. A survey of molecular marker compounds in sediments of San Francisco Bay, California

    Science.gov (United States)

    Hostettler, Frances D.; Rapp, John B.; Geological Survey (U.S.) Pereira, Wilfred E.; Kvenvolden, Keith A.

    1994-01-01

    An areal survey of surficial sediments in San Francisco Bay has been conducted to evaluate the presence of extractable organic compounds. Molecular marker compounds studied include hydrocarbons (PAH's), chlorinated pesticides, and other organic compounds that provide information on sources of organic input into the Bay. Fairly uniform source profiles are seen throughout the Bay. Biomarker profiles contain mature constituents indicating anthropogenic influences and extensive sediment reworking. The dominant input signatures in San Francisco Bay sediment are those of anthropogenic PAH's from combustion and other sources, and long chain n-alkanes and n-aldehydes from terrigenous vascular plants. A comparison of the sums of the combustion PAH's and the terrigenous n-alkanes shows that an anthropogenic influence is dominant in the most urban parts of the Bay close to shore, and in mid-Bay channel areas, and a terrigenous signature is dominant nearshore in San Pablo Bay and at the southernmost station in South Bay.

  14. Butiltins Compound in Seawater and Sediment of Banten Bay

    Directory of Open Access Journals (Sweden)

    Hamidah Razak

    2004-08-01

    Full Text Available bservation on butiltin (BTs compound content in seawater and sediments from Banten Bay were conducted in August 2003 and October 2003. Butiltin content including TBT, DBT and MBT on August 2003 respectively range between <2ng Sn/l, <2 to 9 ng Sn/l and < 5 to 17 ng Sn/l and on October 2003 was found respectively nd to <2 ng Sn/l, <0.5 to 12 ng Sn/g, 0.5 to 2.7 ng Sn/g and <0.5 to 2.2 ng Sn/g, and on October 2003 was found varied from <0.5 to 4.2ng Sn/g, <0.5 to 1.1ng Sn/g and <0.5 to 1 ng Sn/g. Content of TBT was found on August 2003 higher than October 03 and also the content of TBT compound in sediments was high compared to waters. It indicated that there was accumulation of TBT in sediment. The minimal risk of TBT in seaport and for marine life according to Minister of environment in Keputusan Menteri Negara Kependudukan dan Lingkungan Hidup No.51 tahun 2004 is 10 ng/l. The results showed that Banten Bay is still appropiate for seaport and marine life.

  15. 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.

  16. Environmental evidence of fossil fuel pollution in Laguna Chica de San Pedro lake sediments (Central Chile)

    Energy Technology Data Exchange (ETDEWEB)

    Chirinos, L. [Centro de Ciencias Ambientales EULA-Chile, Universidad de Concepcion, PO Box 160-C, Concepcion (Chile)]. E-mail: lchirin@pucp.edu.pe; Rose, N.L. [Environmental Change Research Centre, University College London, 26 Bedford Way, London WG1HOAP (United Kingdom); Urrutia, R. [Centro de Ciencias Ambientales EULA-Chile, Universidad de Concepcion, PO Box 160-C, Concepcion (Chile); Munoz, P. [Departamento de Biologia Marina, Universidad Catolica del Norte, Larrondo 1281, Coquimbo (Chile); Torrejon, F. [Centro de Ciencias Ambientales EULA-Chile, Universidad de Concepcion, PO Box 160-C, Concepcion (Chile); Torres, L. [Departamento de Botanica, Universidad de Concepcion, Concepcion (Chile); Cruces, F. [Departamento de Botanica, Universidad de Concepcion, Concepcion (Chile); Araneda, A. [Centro de Ciencias Ambientales EULA-Chile, Universidad de Concepcion, PO Box 160-C, Concepcion (Chile); Zaror, C. [Facultad de Ingenieria Quimica, Universidad de Concepcion, Concepcion (Chile)

    2006-05-15

    This paper describes lake sediment spheroidal carbonaceous particle (SCP) profiles from Laguna Chica San Pedro, located in the Biobio Region, Chile (36{sup o} 51' S, 73{sup o} 05' W). The earliest presence of SCPs was found at 16 cm depth, corresponding to the 1915-1937 period, at the very onset of industrial activities in the study area. No SCPs were found at lower depths. SCP concentrations in Laguna Chica San Pedro lake sediments were directly related to local industrial activities. Moreover, no SCPs were found in Galletue lake (38{sup o} 41' S, 71{sup o} 17.5' W), a pristine high mountain water body used here as a reference site, suggesting that contribution from long distance atmospheric transport could be neglected, unlike published data from remote Northern Hemisphere lakes. These results are the first SCP sediment profiles from Chile, showing a direct relationship with fossil fuel consumption in the region. Cores were dated using the {sup 21}Pb technique. - The lake sediment record of SCPs shows the record of fossil-fuel derived pollution in Central Chile.

  17. Estuarine sedimentation, sediment character, and foraminiferal distribution in central San Francisco Bay, California

    Science.gov (United States)

    Chin, John L.; Woodrow, Donald L.; McGann, Mary; Wong, Florence L.; Fregoso, Theresa; Jaffe, Bruce E.

    2010-01-01

    Central San Francisco Bay is the deepest subembayment in the San Francisco Bay estuary and hence has the largest water volume of any of the subembayments. It also has the strongest tidal currents and the coarsest sediment within the estuary. Tidal currents are strongest over the west-central part of central bay and, correspondingly, this area is dominated by sand-size sediment. Much of the area east of a line from Angel Island to Alcatraz Island is characterized by muddy sand to sandy mud, and the area to the west of this line is sandy. The sand-size sediment over west-central bay furthermore is molded by the energetic tidal currents into bedforms of varying sizes and wavelengths. Bedforms typically occur in water depths of 15-25 m. High resolution bathymetry (multibeam) from 1997 and 2008 allow for subdivision of the west-central bayfloor into four basic types based on morphologic expression: featureless, sand waves, disrupted/man-altered, and bedrock knobs. Featureless and sand-wave morphologies dominate the bayfloor of west-central bay. Disrupted bayfloor has a direct association with areas that are undergoing alteration due to human activities, such as sand-mining lease areas, dredging, and disposal of dredge spoils. Change detection analysis, comparing the 1997 and 2008 multibeam data sets, shows that significant change has occurred in west-central bay during the roughly 10 years between surveys. The surveyed area lost about 5.45 million m3 of sediment during the decade. Sand-mining lease areas within west-central bay lost 6.77 million m3 as the bayfloor deepened. Nonlease areas gained 1.32 million m3 of sediment as the bayfloor shallowed slightly outside of sand-mining lease areas. Furthermore, bedform asymmetry did not change significantly, but some bedforms did migrate some tens of meters. Gravity cores show that the area east of Angel and Alcatraz Islands is floored by clayey silts or silty sand whereas the area to the west of the islands is floored

  18. 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

  19. 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

  20. 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.

  1. Distribution and characteristics of methylmercury in surface sediment in Minamata Bay.

    Science.gov (United States)

    Matsuyama, Akito; Yano, Shinichiro; Hisano, Akihiro; Kindaichi, Michiaki; Sonoda, Ikuko; Tada, Akihide; Akagi, Hirokatsu

    2016-08-15

    This study was carried out to evaluate the present-day chemical properties of methylmercury in surface sediment in Minamata Bay where a dredging project was completed 28years ago. Present-day sediment from Minamata Bay consists of sandy silt, and the average loss-on-ignition in surface sediment was 7.0±2.3%. The average methylmercury concentrations in the upper sediment layers were significantly higher than those in the lower sediment layers. Currently, the concentrations in sediments in Minamata Bay do not exceed the Japanese regulatory standard value for mercury. The average concentration of methylmercury in Minamata Bay surface sediment was 1.74±1.0ng/g on a dry weight basis (n=107). The methylmercury concentration in Minamata Bay surface sediment was almost 16 times higher than that in surface sediment from Isahaya Bay surface sediment, which was 0.11±0.045ng/g on a dry weight basis (n=5).

  2. A summary report of sediment processes in Chesapeake Bay and watershed

    Science.gov (United States)

    Langland, Michael; Cronin, Thomas

    2003-01-01

    The Chesapeake Bay, the Nation's largest estuary, has been degraded because of diminished water quality, loss of habitat, and over-harvesting of living resources. Consequently, the bay was listed as an impaired water body due to excess nutrients and sediment. The Chesapeake Bay Program (CBP), a multi-jurisdictional partnership, completed an agreement called ?Chesapeake 2000? that revises and establishes new restoration goals through 2010 in the bay and its watershed. The goal of this commitment is the removal of the bay from the list of impaired waterbodies by the year 2010. The CBP is committed to developing sediment and nutrient allocations for major basins within the bay watershed and to the process of examining new and innovative management plans in the estuary itself and along the coastal zones of the bay. However, additional information is required on the sources, transport, and deposition of sediment that affect water clarity. Because the information and data on sediment processes in the bay were not readily accessible to the CBP or to state, and local managers, a Sediment Workgroup (SWGP) was created in 2001. The primary objective of this report, therefore, is to provide a review of the literature on the sources, transport, and delivery of sediment in Chesapeake Bay and its watershed with discussion of potential implications for various management alternatives. The authors of the report have extracted, discussed, and summarized the important aspects of sediment and sedimentation that are most relevant to the CBP and other sediment related-issues with which resources managers are involved. This report summarizes the most relevant studies concerning sediment sources, transport and deposition in the watershed and estuary, sediments and relation to water clarity, and provides an extensive list of references for those wanting more information.

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

    Science.gov (United States)

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

    2013-01-01

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

  4. Pathways of carbon oxidation in continental margin sediments off central Chile

    DEFF Research Database (Denmark)

    Thamdrup, B; Canfield, Donald Eugene

    1996-01-01

    Rates and oxidative pathways of organic carbon mineralization were determined in sediments at six stations on the shelf and slope off Concepcion Bay at 36.5 degrees S. The depth distribution of C oxidation rates was determined to 10 cm from accumulation of dissolved inorganic C in 1-5-d incubatio...

  5. 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.

  6. 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.

  7. 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})

  8. New assessment of organic mercury formation in highly polluted sediments in the Lenga estuary, Chile.

    Science.gov (United States)

    Yáñez, Jorge; Guajardo, Marjory; Miranda, Cristian; Soto, César; Mansilla, Héctor D; Flegal, A Russell

    2013-08-15

    Anomalously high levels of mercury in sediment in the Lenga estuary, Chile are comparable to the most contaminated sites previously reported elsewhere. Total mercury (Hgtotal) concentrations range from 0.5 to 129 mg kg(-1) and organic mercury (Hgorg) from 11 to 53 μg kg(-1). The highest levels are in areas near the previous wastewater outfall of a chlo-alkali plant. The results show that the proportion of Hgorg/Hgtotal in the sediment varies by more than two orders of magnitude (0.02-5.7%) according to the concentration of Hgtotal. No correlation between the concentration of Hgorg and Hgtotal was found. The lack of correlation does contrast with the findings of other authors in culture media. Our results indicate that even at very high concentrations of Hgtotal and organic matter do not influence organic mercury formation in estuary sediments. The disparity in Hgtotal and Hgorg concentrations also attests to environmental differences in the formation.

  9. Heavy metal pollution in intertidal sediments from Quanzhou Bay, China

    Institute of Scientific and Technical Information of China (English)

    YU Ruilian; YUAN Xing; ZHAO Yuanhui; HU Gongren; TU Xianglin

    2008-01-01

    The concentrations of eight heavy metals (Cu,Zn,Pb,Cd,Cr,Ni,Hg,and As) in the intertidal surface sediments from Quanzhou Bay were determined to evaluate their levels and spatial distribution due to urbanization and economic development of Quanzhou region,southeast China.The ranges of the measured concentrations in the sediments are as foilows:24.8-119.7 mg/kg for Cu,105.5-241.9 mg/kg for Zn,34.3-10n9 mg/kg for Pb,0.28-0.89 mg/kg for Cd,51.1-121.7 mg/kg for Cr,16.1-45.7 mg/kg for Ni,0.17-0.74 mg/kg for Hg,and 17.7-30.2 mg/kg for As.The overall average concentrations of above metals exceed the primary standard criteria but meet the secondary standard criteria of the Chinese National Standard of Marine Sediment Quality.Several contents of Cu and Hg exceed the secondary standard criteria at some stations.The results of geoaccumulation index (Igeo) show that Cd causes strong pollution in most of the study area.There are no significant correlations among most of these heavy metals,indicating they have different anthropogenic and natural sources.Some locations present severe pollution by heavy metals depending on the sources,of which sewage outlets,aquatic breeding,and commercial ports are the main sources of contaminants to the area.

  10. Polychlorinated naphthalenes (PCNs) in riverine and marine sediments of the Laizhou Bay area, North China

    Energy Technology Data Exchange (ETDEWEB)

    Pan Xiaohui [Key Laboratory of Coastal Zone Environmental Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Tang Jianhui, E-mail: jhtang@yic.ac.cn [Key Laboratory of Coastal Zone Environmental Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Chen Yingjun [Key Laboratory of Coastal Zone Environmental Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Li Jun; Zhang Gan [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China)

    2011-12-15

    PCN congeners were analyzed in marine and riverine sediments of the Laizhou Bay area, North China. Concentrations of PCNs ranged from 0.12 to 5.1 ng g{sup -1} dry weight (dw) with a mean value of 1.1 ng g{sup -1} dw. The levels of PCNs varied largely, with industrial group approximately ten folds higher than those of the rural in riverine sediment. A strong impact by direct discharge from local factories was suggested. Similar compositional profiles were found within groups. High resemblance of compositional profiles between industrial samples and Halowax 1014 was observed. It was indicated that PCNs in riverine sediments were mainly from release of industrial usage, with additional contributions from industrial thermal process at certain sites. In marine sediments, it was suggested that PCNs along the coast of Laizhou Bay were mainly controlled by riverine input. While in the central bay, PCN distributions were possibly impacted by combined multiple factors. - Highlights: > We investigated the PCN levels both in the riverine and marine surface sediments of Laizhou Bay. > PCN concentrations in the river sediments of industrial group were ten times higher than in the rural group. > Leakage from industrial materials and thermal processes were the major sources. > PCNs in the coastal sites were more influenced by the river discharge. > In the centre bay, PCN distributions were possibly impacted by combined multiple factors. - A systematic sampling of riverine and marine sediments was conducted in Laizhou Bay area to investigate the distribution and possible sources of PCNs.

  11. 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,...

  12. Sediment Data from the Great Bay Estuarine System acquired in 1986 (NELSON86 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 estuarine system of New Hampshire. Textural data were used to support...

  13. 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...

  14. 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.

  15. Characteristics of Water and Sediment Exchange Between Yangtze Estuary and Hangzhou Bay

    Institute of Scientific and Technical Information of China (English)

    KONG Jun; SONG Zhi-yao; XIA Yun-feng; ZHANG Wei-sheng

    2007-01-01

    Based on the 2-D flow and sediment numerical model of the Yangtze Estuary and the Hangzhou Bay, the characteristics of water and sediment exchange in their joint waters is studied through quantitative calculation and analysis of the characteristics of water flow and sediment transportation. The results show that there is periodical water and sediment exchange in this joint waters, that the net water exchange appears mainly between 0~6 m depth (theoretical datum plane, the same below) offshore and the maximum is near the depth of 2 m, and that the net sediment exchange mainly appears between 0~5 m depth and the maximum is near the depth of 3 m, indicating that the range of water flow passage is different from that of sediment transport from the Yangtze Estuary to the Hangzhou Bay. Combined with the results of numerical simulation, this paper also analyzes the hydrodynamical mechanism influencing water and sediment exchange between the Yangtze Estuary and the Hangzhou Bay, including tidal fluctuation, tidal current kinetic energy, tide-induced residual current and the trace of water particles. Finally, the sediment transportation passage on the Nanhui tidal flat is discussed, and the results show that sediment is transported into the Hangzhou Bay from the south side of Shipilei, while sediment is brought back to the South Channel of the Yangtze Estuary from the north side.

  16. The Record of Giant Earthquakes in the Sediments of Lago Villarrica (South-Central Chile)

    Science.gov (United States)

    Moernaut, J.; de Batist, M.; Pino, M.; Brümmer, R.

    2008-05-01

    South-Central Chile is located where the oceanic Nazca plate actively subducts underneath the continental South American plate. This subduction zone has ruptured in great destructive earthquakes with variable magnitude during historical times, with as tragic highlight the 1960 Valdivia earthquake, which accounts for the largest instrumentally recorded earthquake worldwide (Moment Magnitude: 9.5). Damage from severe ground-shaking was reported from up to 1000 km south of the 1960 earthquake epicenter and a devastating tsunami ravaged across the Pacific. The historical earthquake records in South-Central Chile only cover ~500 yrs, so "natural" archives -in which paleo-earthquake activity has been recorded and preserved- need to be explored to reveal a statistically significant earthquake recurrence. In this study, a high-resolution seismic survey on Lago Villarrica has been executed to study its sedimentary infill for fingerprints of severe shaking. The seismic profiles acquired in our study show a succession of voluminous underwater landslide deposits and their related failure scars. Multiple slope failures occurred simultaneously in calm depositional environments, which points toward a strong, instantaneous basin-wide trigger of slope instability. Evaluation of all possible slope failure processes led us to infer that very strong earthquakes are the most likely triggers of these landslide events. Our seismic profiles also show a distinct stratigraphic level of sediment disturbance, locally overlain by a field of sediment volcanoes, which have dimensions up to 70 m wide and 2 m thick. These structures are interpreted as a result of sudden compaction in a buried landslide deposit and subsequent vertical flow of overpressured pore water and entrained sediments which have been expelled at the paleo-lake bottom. We postulate that this process of subsurface sediment mobilization has been triggered by seismic ground-shaking, as such sediment volcanoes have been commonly

  17. Comparison of sediment supply to San Francisco Bay from Coastal and Sierra Nevada watersheds

    Science.gov (United States)

    McKee, L. J.

    2012-12-01

    Quantifying suspended sediment loads is of paramount importance for managing the world's estuaries. To address this information need, a comprehensive analysis was completed for the San Francisco Bay system by combining a number of formerly disparate data sets. Suspended sediment and optical backscatter measurements near the head of the estuary were used to generate a continuous suspended sediment concentration record. In addition, periodic measurements of velocity and suspended sediment variation in the cross-section were used to validate the use of point samples collected on the edge of the channel for generating loads. Suspended sediment loads were determined by combining daily averaged suspended sediment concentrations with daily flow estimates adjusting for dispersive loads. Sediment loads from 482 small drainages around the Bay were determined using 235 station years of suspended sediment data covering 38 watershed locations, regression analysis, and simple modeling. Over 16 years, net annual load to the head of the estuary from its 154000 km2 watershed varied from 0.13-2.58 (mean = 0.89) million metric t, or 5.8 t/km2/yr. Small drainages in the nine-county Bay Area discharged between 0.089 and 4.35 (mean = 1.43) million metric t with an average yield of 175 metric t/km2/yr. Our results indicate that external loads to the Bay are dominated by the many hundreds of urbanized and tectonically active tributaries that drain just 8145 km2 adjacent to the Bay and that during only 5 years did sediment loads from the Central Valley likely exceed loads from the sum of the local smaller drainages. If San Francisco Bay is typical of other estuaries in active tectonic or climatically variable coastal regimes, managers responsible for water quality, sediment accumulating in shipping channels, or restoring wetlands in the world's estuaries may need to more carefully account for proximal small urban drainages that may dominate allochthonous sediment supply.

  18. 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,...

  19. Sediments of Narragansett Bay acquired in 1960 (MCMASTER60 shapefile)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Gravel, sand, silt, and clay contents were determined for samples from Narragansett Bay and the adjacent Rhode Island Shelf. In the Narragansett Bay system, clayey...

  20. Differential arsenic binding in the sediments of two sites in Chile's lower Loa River basin.

    Science.gov (United States)

    Bugueño, Manuel P; Acevedo, Sara E; Bonilla, Carlos A; Pizarro, Gonzalo E; Pasten, Pablo A

    2014-01-01

    Fluvial sediments from two lower Loa River basin sites in northern Chile were compared in order to probe the effects of vegetation and organic matter (OM) on As accumulation in fluvial environments. The two sites were the Sloman dam, which lacks macrophytes and has a low OM content (2.4%) in sediments, and the Quillagua Oasis, which is 23 km downstream from the Sloman site and has a higher OM (6.2%) in sediments and abundant aquatic plant life. The Quillagua site had preferential As enrichment with a co-occurrence pattern that differed from that of the Sloman site, which had a lower As concentration (1528 vs. 262 mg/kg d.w., respectively). At the Quillagua site, As concentration was strongly correlated with Mn and OM (r = 0.91 and 0.85, respectively); while at the Sloman site, As concentration in sediments was significantly correlated with Ca and Sr (r = 0.63 and 0.54, respectively). Sequential extraction analyses showed that the Sloman site had higher percentage of easily exchangeable As within the surface sediment (12%, 45 mg/kg d.w.) compared with the Quillagua site (3%, 40 mg/kg d.w.). These contrasting results suggest that both vegetation and OM control the immobilization and accumulation of As in the arid Loa River basin.

  1. Invasion of a rocky intertidal shore by the tunicate Pyura praeputialis in the Bay of Antofagasta, Chile.

    Science.gov (United States)

    Castilla, Juan Carlos; Guiñez, Ricardo; Caro, Andrés U; Ortiz, Verónica

    2004-06-08

    Invasion by marine nonindigenous species (NIS) is a spread phenomenon. The tunicate Pyura praeputialis shows pronounced disjoint geographical distribution: along thousands of kilometers in wave-swept headlands on the southeastern coast of Australia, from where it appears to have originated, and exclusively along 60-70 km inside the Bay of Antofagasta, Chile. mtDNA sequences suggested that the species invaded this rocky shore recently. We used field manipulations and juvenile P. praeputialis transplant techniques to test hypotheses regarding the capacity of the tunicate to survive and grow at different sites and tidal heights inside and outside Antofagasta, and its competitive performance for primary space (inside the Bay) against the native mussel Perumytilus purpuratus. We conclude that survival and growth of P. praeputialis showed no significant differences among sites inside and outside the Bay, and suggest that the restrictive distribution of the species in Chile is caused by a specific oceanographic retention mechanism and/or its brief larval dispersal. We demonstrated that, inside the Bay, P. praeputialis outcompetes Perumytilus from the Mid-Low intertidal, constraining Perumytilus to the Upper Mid-Intertidal, modifying the local pattern of intertidal zonation. We show that predation on P. praeputialis juveniles by starfish and snails constitutes a regulatory mechanism for the setting of its low intertidal limit. Major ecological impacts caused by NIS invasions to rocky shores by aggressive primary space users may result in negative aspects, but also may contribute to biodiversity enhancement. We call attention to the need for increment manipulations and testing of ecological hypotheses regarding marine NIS.

  2. Distribution Pattern of Heavy Metals in the Surface Sediments of the Jiaozhou Bay

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Grain size analysis and chemical analysis of heavy metals are made for 312 surface samples of the Jiaozhou Bay. Nineteen samples of the waste water taken from the sewage discharge outlets along the eastern coast of the bay are also analyzed for heavy metals. Results show that heavy metals are richer in the east and poorer in the west of the bay. Sedimentary dynamic studies reveal that the distribution of heavy metals in the surface sediments of the Jiaozhou Bay is under the control of hydrodynamics.

  3. Seasonal changes in magnetic parameters of sediments with changing redox conditions in Hiroshima Bay, Japan

    Science.gov (United States)

    Kawamura, Noriko; Amano, Yuka; Ishikawa, Naoto

    2016-07-01

    To describe and interpret the relationship between spatial and seasonal changes in the sedimentary environment of nearshore sediments and their magnetic properties, magnetic and geochemical analyses were performed on sediment samples from three stations in Hiroshima Bay, Japan. Vertical stratification of the water column in the bay changes throughout the year, and magnetic hysteresis parameters and mineralogy in the bay sediments vary in response to changes in redox conditions of bottom waters. Magnetite and hematite are present year-round at all stations. The presence of maghemitized magnetite is inferred at a station located at the entrance to the bay. Greigite is recognized at all stations in September 2011 but is not found at the entrance to the bay when water column stratification is disturbed from October 2011. The presence of maghemite and goethite is inferred at two stations in the inner bay when the sedimentary environment is oxic. The remanent coercivity/coercivity ratio (Hcr/Hc) also varies, both spatially and temporally, which reflects changes in magnetic mineralogy. Increased of Hcr/Hc values are likely to be caused by goethite and/or maghemite formation when water column stratification is disturbed and the seafloor is oxic. Concentration-dependent magnetic parameters do not respond to seasonal changes in the redox conditions of bottom waters. Reaction times and/or changes in chemical and physical conditions may be insufficient to affect these parameters in the sediments of Hiroshima Bay.

  4. Maps showing textural characteristics of benthic sediments in the Corpus Christi Bay estuarine system, south Texas

    Science.gov (United States)

    Shideler, Gerald L.; Stelting, Charles E.; McGowen, Joseph H.

    1981-01-01

    Corpus Christi Bay is a heavily used estuary on the south Texas coast in the northwest Gulf of Mexico (fig. 1).  The Bay is stressed by diverse activities which could substantially affect its ecosystem.  Such activities include shipping, resource production (oil, gas, and construction aggregate), commercial and sport fishing, and recreation.  Shipping activities alone have had a substantial impact on the bay.  For example, the past maintenance of navigation channels has required extensive dredging and spoil disposal within the estuarine system.  Numerous subaqueous spoil disposal sites and subaerial spoil banks are present throughout the bay (fig. 1), and the selection of future spoil disposal sites is becoming a critical local problem.  As activities in the bay increase, the need for effective environmental management becomes increasingly important, and effective management necessitates a good understanding of the bay's physical characteristics.  The objective of this study is to provide detailed information about the textural composition of bottom sediments within the estuarine system, information which could be used in making environmental-management decisions.  Visual descriptions of bottom sediments in Corpus Christi Bay and adjacent areas have been presented by McGowen and Morton (1979).  Additionally, a study of the textures of sediments on the Inner Continental Shelf adjacent to the bay has been presented by Shideler and Berryhill (1977).

  5. Rare earth element fingerprints in Korean coastal bay sediments: Association with provenance discrimination

    Science.gov (United States)

    Kang, Jeongwon; Woo, Han Jun; Jang, Seok; Jeong, Kap-Sik; Jung, Hoi-Soo; Hwang, Ha Gi; Lee, Jun-Ho; Cho, Jin Hyung

    2016-09-01

    Rare earth elements (REEs: La-Lu) in surface sediments collected from the mouth and middle tidal flats of Gomso Bay, South Korea, in August 2011 and May 2012 were analyzed to investigate the fine-grained sediment provenance. The upper continental crust (UCC)-normalized light REEs (LREEs: La to Nd) were more enriched than the middle REEs (MREEs: Sm to Dy) and heavy REEs (HREEs: Ho to Lu), resulting in large (La/Yb)UCC (1.9 ± 0.4) to (Gd/Yb)UCC (1.4 ± 0.2) ratios. The monthly (La/Yb)UCC values differed between the mouth and middle tidal flats due to deposition of fine-grained sediments that originated from distant rivers (the Geum and Yeongsan) and the Jujin Stream, located on the southern shore of the inner bay. We observed relative reductions in the (La/Yb)UCC value and REE content in the sediments from the mouth of the bay compared with those from Jujin Stream sediments. Confined to the middle tidal flat around the KH Line of Jujin Stream, the sediments, most enriched in LREEs but depleted in Eu, were distributed in August as strong Jujin Stream runs. Here, we suggest that an increase in LREE/HREE and decrease in MREE/LREE ratios can be used as a proxy to identify the Jujin Stream provenance in mixed riverine sediments and to trace Jujin Stream sediments within the Gomso Bay tidal flat, especially in the summer rainy season.

  6. 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

    We investigated the effect of seasonal environmental changes on the rate and distribution of anaerobic oxidation of methane (AOM) in Eckernforde Bay sediments (German Baltic Sea) and identified organisms that are likely to be involved in the process. Surface sediments were sampled during Septembe...

  7. 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,

  8. Interrogation of Chesapeake Bay sediment microbial communities for intrinsic alkane-utilizing potential under anaerobic conditions.

    Science.gov (United States)

    Johnson, Jamie M; Wawrik, Boris; Isom, Catherine; Boling, Wilford B; Callaghan, Amy V

    2015-02-01

    Based on the transient exposure of Chesapeake Bay sediments to hydrocarbons and the metabolic versatility of known anaerobic alkane-degrading microorganisms, it was hypothesized that distinct Bay sediment communities, governed by geochemical gradients, would have intrinsic alkane-utilizing potential under sulfate-reducing and/or methanogenic conditions. Sediment cores were collected along a transect of the Bay. Community DNA was interrogated via pyrosequencing of 16S rRNA genes, PCR of anaerobic hydrocarbon activation genes, and qPCR of 16S rRNA genes and genes involved in sulfate reduction/methanogenesis. Site sediments were used to establish microcosms amended with n-hexadecane under sulfate-reducing and methanogenic conditions. Sequencing of 16S rRNA genes indicated that sediments associated with hypoxic water columns contained significantly greater proportions of Bacteria and Archaea consistent with syntrophic degradation of organic matter and methanogenesis compared to less reduced sediments. Microbial taxa frequently associated with hydrocarbon-degrading communities were found throughout the Bay, and the genetic potential for hydrocarbon metabolism was demonstrated via the detection of benzyl-(bssA) and alkylsuccinate synthase (assA) genes. Although microcosm studies did not indicate sulfidogenic alkane degradation, the data suggested that methanogenic conversion of alkanes was occurring. These findings highlight the potential role that anaerobic microorganisms could play in the bioremediation of hydrocarbons in the Bay.

  9. Historical sediment record and distribution of polychlorinated biphenyls (PCBs) in sediments from tidal flats of Haizhou Bay, China.

    Science.gov (United States)

    Zhang, Rui; Zhang, Fan; Zhang, Tiancheng; Yan, Hongqiang; Shao, Wei; Zhou, Li; Tong, Hebing

    2014-12-15

    The spatial and temporal variations and sources of polychlorinated biphenyls (PCBs) in sediment of tidal flat from Haizhou Bay, China were investigated. PCBs concentrations in surface sediments ranged from 1.33 to 6.27ngg(-1) dry weight. Low-chlorinated PCBs, dominated by the tri-PCB homologs, were identified as the prevalent contaminate of surface sediments. These results were in agreement with the fact that tri-PCB homologs are the dominant contaminants in China. In surface sediment, the highest level appeared in the estuary, and it decreased with distance from the Linhong River estuary. PCBs concentrations started to rise from the mid-1950s, and reached a maximum in 2005. PCBs in sediment might originate from surface runoff and discharges of local source as well as slight atmospheric deposition, based on PCA. Additionally, the PCBs levels in the sediments were considered to rarely pose hazard to the aquatic and human health, based on Sediment Quality Guidelines (SQGs).

  10. 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.

  11. 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-DePasquale, Mark

    2011-01-01

    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 (HgT) 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 δ202Hg 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 δ202Hg 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 δ202Hg 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 δ202Hg source north of SF Bay. Tailings and thermally decomposed ore (calcine) from the New Idria Hg mine in the California Coast Range had average δ202Hg 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 δ202Hg 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.

  12. 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

  13. Interferometric Sidescan Bathymetry, Sediment and Foraminiferal Analyses; a New Look at Tomales Bay, California

    Science.gov (United States)

    Anima, Roberto J.; Chin, John L.; Finlayson, David P.; McGann, Mary; Wong, Florence L.

    2008-01-01

    The United States Geological Survey (USGS) in collaboration with Point Reyes National Sea Shore (PRNS), and the Tomales Bay Watershed Council [http://www.tomalesbaywatershed.org/] has completed a detailed bathymetric survey, and sediment and foraminiferal analyses of the floor of Tomales Bay, California. The study goals are to detail the submarine morphology, the sediment distribution, sedimentary features, and distribution of foraminifera to provide a framework for future studies. The USGS collected swath bathymetric data with a SEA SWATHplus interferometric sidescan sonar system (2004, 2005) and an echo sounder system (2006). The data were processed into continuous mosaic images that show bathymetric detail of the bay floor with 0.2-m vertical and 4.0-m horizontal resolution. Acoustic backscatter data from the 2004 and 2005 surveys were processed into 2-m resolution grids. In addition, 27 sediment samples were collected from various parts of the bay for grain size analyses and a comprehensive study of the distribution of foraminifera in Tomales Bay. The foraminiferal analysis determined that the invasive foraminifera Trochammina hadai from Japan was present in Tomales Bay. The project was conducted in response to a request from the National Park Service, and the Tomales Bay Watershed Council who voiced a need to look at the environmental impacts of human input to the surrounding watersheds that ultimately flow into the bay. The mapping, sediment, and foraminiferal data establish a baseline survey for future comparisons of possible geologic and anthropogenic changes that might occur due to changes in land use or development in the surrounding watershed. These data may also aid in determining the possible pathways of pollutants entering the bay from the surrounding watersheds.

  14. 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.

  15. 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.

  16. Influence of solar radiation on DOM release from resuspended Florida Bay sediments

    Science.gov (United States)

    Shank, G. C.; Evans, A.; Jaffé, R.; Yamashita, Y.

    2009-12-01

    This study investigated dissolved organic matter (DOM) release from resuspended Florida Bay sediments under dark and sunlit conditions. Much of Florida Bay (located between Everglades and Florida Keys) is very shallow (concentration and composition of DOM in the water column. For our study, sediments were collected at several sites across Florida Bay and ranged from 3-11 percent organic carbon (by weight). Sediments were resuspended in oligotrophic seawater for 48 hours in 1 L quartz flasks in the dark and under simulated solar radiation (SunTest XLS+) at concentrations of 100 mg L-1 and 1 g L-1 (wet weight). Final solutions were analyzed for DOC, chromophoric dissolved organic matter (CDOM), and Excitation Emission Matrix (EEM) fluorescence. Results showed little to no DOC increases in the resuspensions performed under dark conditions, but substantial release of DOM in irradiated resuspensions, especially at high sediment concentrations where DOC increases ranged from 100-500%. The sediments also released substantial quantities of CDOM to solution under irradiated conditions. The magnitude of DOC increases in irradiated resuspensions were well-correlated with the amount of particulate organic carbon (POC) added. Data from EEM-PARAFAC analyses suggests the photochemically produced DOM was comprised of desorbed humic material with a smaller fraction from microbial mediated processes. Our study provides evidence that sediment resuspension episodes in shallow sunlit waters such as Florida Bay have the potential to provide an important source of organic carbon to overlying waters.

  17. 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.

  18. Matrix-bound phosphine:A new form of phosphorus found in sediment of Jiaozhou Bay

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Matrix-bound phosphine (PH3), a new form of phosphorus, was found in sediment of Jiaozhou Bay in December 2001. Concentration and distribution of PH3 in different layers of sediment with different stations were analyzed. The results show that PH3 concentrations are various with different layers and different stations. PH3 concentrations in the bottom layer of sediment (20-30 cm) are usually higher than those in the surface layer (0-4 cm). The highest PH3 concentration in our investigation reaches 685 ng/kg (dry), which is much higher than those in terrestrial paddy soil, marsh and landfill that have been reported up to now. The correlation analysis indicates that there is no apparent correlation between the concentrations of PH3 and inorganic phosphorus in sediment. However, the correlation between the concentrations of phosphine and organic phosphorus in the bottom layer of sediment is remarkable (R2=0.83). It is considered that PH3 in sediment of Jiaozhou Bay is mainly produced from the decomposition of organic phosphorus in the anaerobic condition, and so PH3 concentrations are related to organic phosphorus concentration and anaerobic environment in sediment. The discovery of PH3 in sediment will give people some new ideas on the mechanisms of phosphorus supplement and biogeochemical cycle in Jiaozhou Bay.

  19. Mercury-contaminated sediments in the North Bay: A legacy of the Gold Rush

    Science.gov (United States)

    Jaffe, Bruce E.

    2001-01-01

    A legacy of the Gold Rush is mercury-contaminated sediments in the Bay. Miners used mercury to extract gold from tailings during the gold rush. A large amount of this mercury (some estimates are as great as 10,000 tons) was lost during extraction to the watershed during the gold rush era. This mercury-contaminated hydraulic mining debris made its way to the Bay.

  20. 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.

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

    Science.gov (United States)

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

    2006-01-01

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

  2. 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.

  3. 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.

  4. Evaluations of heavy metal pollution in sediment and Mullus barbatus from the Izmir Bay (Eastern Aegean) during 1997-2009.

    Science.gov (United States)

    Kucuksezgin, Filiz; Kontas, Aynur; Uluturhan, Esin

    2011-07-01

    Izmir Bay is one of the great natural bays of the Mediterranean. The surface sediment and fish samples were collected during 1997-2009. The sediment concentrations of inner bay showed significant enrichments during sampling periods. Outer and middle bays exhibited low levels of metal enrichments except the estuary of Gediz River. The concentrations were generally higher than the background levels from the Mediterranean and Aegean except Cd and Pb levels gradually decreased. Metal EF is used as an index to evaluate anthropogenic influences of metals in sediments. Maximum metal enrichment was found for Hg in the outer bay, while Pb indicated maximum enrichment in the middle-inner bays. Metal levels were evaluated in sediments in accordance with the numerical SQG of the USEPA. The levels of fish tissues were lower than the results reported from polluted areas of the Mediterranean. The highest BAFs were detected for Hg and Cd in fish.

  5. Sediment Deposition, Erosion, and Bathymetric Change in Central San Francisco Bay: 1855-1979

    Science.gov (United States)

    Fregoso, Theresa A.; Foxgrover, Amy C.; Jaffe, Bruce E.

    2008-01-01

    Central San Francisco Bay is the hub of a dynamic estuarine system connecting the San Joaquin and Sacramento River Deltas, Suisun Bay, and San Pablo Bay to the Pacific Ocean and South San Francisco Bay. To understand the role that Central San Francisco Bay plays in sediment transport throughout the system, it is necessary to first determine historical changes in patterns of sediment deposition and erosion from both natural and anthropogenic forces. The first extensive hydrographic survey of Central San Francisco Bay was conducted in 1853 by the National Ocean Service (NOS) (formerly the United States Coast and Geodetic Survey (USCGS)). From 1894 to 1979, four additional surveys, composed of a total of approximately 700,000 bathymetric soundings, were collected within Central San Francisco Bay. Converting these soundings into accurate bathymetric models involved many steps. The soundings were either hand digitized directly from the original USCGS and NOS hydrographic sheets (H-sheets) or obtained digitally from the National Geophysical Data Center's (NGDC) Geophysical Data System (GEODAS) (National Geophysical Data Center, 1996). Soundings were supplemented with contours that were either taken directly from the H-sheets or added in by hand. Shorelines and marsh areas were obtained from topographic sheets. The digitized soundings, depth contours, shorelines, and marsh areas were entered into a geographic information system (GIS) and georeferenced to a common horizontal datum. Using surface modeling software, bathymetric grids with a horizontal resolution of 25 m were developed for each of the five hydrographic surveys. Before analyses of sediment deposition and erosion were conducted, interpolation bias was removed and all of the grids were converted to a common vertical datum. These bathymetric grids were then used to develop bathymetric change maps for subsequent survey periods and to determine long-term changes in deposition and erosion by calculating volumes and

  6. 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.

  7. 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.

  8. Reevaluation of Minamata Bay, 25 years after the dredging of mercury-polluted sediments.

    Science.gov (United States)

    Akito, Matsuyama; Shinichiro, Yano; Akihiro, Hisano; Michiaki, Kindaichi; Ikuko, Sonoda; Akihide, Tada; Hirokatsu, Akagi

    2014-12-15

    A detailed investigation of mercury concentrations in the bottom sediments of Minamata Bay was performed in May, 2012. A total of 691 sediment samples were obtained from 107 sampling points in the bay. The weighted average total mercury concentration and the total mass of mercury in the bottom sediments of Minamata Bay were estimated to be 2.3mg/kg dry weight basis and 3.4 tons, respectively. The average concentration of total mercury in the surface layer of the sediments was 3.0mg/kg dry weight basis, and the distribution pattern of total mercury concentrations in the surface layer was found to have changed little in comparison to results reported 25 years ago. In addition, based on the results of seawater monitoring in Minamata Bay from 2010 to 2012, the amounts of total mercury and methylmercury mobilized from sediments and dissolved in the water column were 0.7 and 0.1 kg/yr, respectively.

  9. A seasonal comparison of surface sediment characteristics in Chincoteague Bay, Maryland and Virginia, USA

    Science.gov (United States)

    Ellis, Alisha M.; Marot, Marci E.; Wheaton, Cathryn J.; Bernier, Julie C.; Smith, Christopher G.

    2016-02-03

    Scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center conducted a seasonal collection of surficial sediments from Chincoteague Bay and Tom's Cove, between Assateague Island and the Delmarva Peninsula in late March/early April 2014 and October 2014. The sampling efforts were part of a larger U.S. Geological Survey study to assess the effects of storm events on sediment distribution in back-barrier environments of the United States. By sampling during the spring and fall, a more complete understanding of seasonal variability in the area can help determine baseline conditions. The objective of this study was to characterize the sediments of Chincoteague Bay in order to create baseline conditions to incorporate with the hydrodynamic and sediment transport models used to evaluate pre- and post-storm change and compare with future field measurements.

  10. The sediment budget of an urban coastal lagoon (Jamaica Bay, NY) determined using 234Th and 210Pb

    Science.gov (United States)

    Renfro, Alisha A.; Cochran, J. Kirk; Hirschberg, David J.; Bokuniewicz, Henry J.; Goodbred, Steven L.

    2016-10-01

    The sediment budget of Jamaica Bay (New York, USA) has been determined using the natural particle-reactive radionuclides 234Th and 210Pb. Inventories of excess thorium-234 (234Thxs, half-life = 24.1 d) were measured in bottom sediments of the Bay during four cruises from September 2004 to July 2006. The mean bay-wide inventory for the four sampling periods ranged from 3.5 to 5.0 dpm cm-2, four to six times that expected from 234Th production in the overlying water column. The presence of dissolved 234Th and a high specific activity of 234Thxs on particles at the bay inlet (∼30 dpm g-1) indicated that both dissolved and particulate 234Th could be imported into the bay from the ocean. Based on these observations, a mass balance of 234Th yields an annual input of ∼39 ± 14 × 1010 g sediment into the bay. Mass accumulation rates determined from profiles of excess 210Pb (half-life = 22.3 y) in sediment cores require annual sediment import of 7.4 ± 4.5 × 1010 g. Both radionuclides indicate that there is considerable marine-derived sediment import to Jamaica Bay, consistent with earlier work using 210Pb. Such sediment input may be important in sustaining longer-term accretion rates of salt marshes in the bay.

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

    Science.gov (United States)

    Hu, Ningjing; Huang, Peng

    2016-04-01

    Anthropogenic Pb input into Bohai Bay, China: Evidence from stable Pb isotopic compositions in sediments Hu Ning-jinga, Huang Pengb,, Liu Ji-huaa, a First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China b Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China 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.

  12. Distribution and sources of heavy metals in the sediment of Xiangshan Bay

    Institute of Scientific and Technical Information of China (English)

    SUN Weiping; YU Jianjun; XU Xiaoqun; ZHANG Weiyan; LIU Ruijuan; PAN Jianming

    2014-01-01

    Heavy metals in the surface sediments and sediment core from the Xiangshan Bay, a mariculture base on the coast of the East China Sea, were determined by inductively coupled plasma mass spectrometry (ICP-MS) in order to evaluate their levels and sources. The results showed that the levels of Cu, Pb, Zn, and Cr in the sedi-ments of the bay have been generally influenced by anthropogenic inputs since the founding of the People’s Republic of China. In particular, Cu and Zn were polluted to some extent, as evidenced by high enrich-ment factors. Organic matter, grain size, wastewater discharge, and low energy hydrodynamic environment played dominant roles in the heavy metal enrichment in the sediments. The ratio of terrigenous source to marine biogenic deposit of trace metals in the sediments was calculated, revealing that terrigenous inputs were the main source of Cu, Pb, and Zn, while biological pellets contributed much more to the enrichment of Cr and Cd. Considering the influence of biological sources on the enrichment of Cd and Cr, and the fact that the sediment has been polluted by Cu and Zn, the development of mariculture and discharge of waste-water into the Bay should be restricted.

  13. 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.

  14. Pliocene mass failure deposits mistaken as submarine tsunami backwash sediments - An example from Hornitos, northern Chile

    Science.gov (United States)

    Spiske, Michaela; Bahlburg, Heinrich; Weiss, Robert

    2014-05-01

    In this study we question the former interpretation of a shallow marine backwash tsunami origin of a conspicuous Pliocene coarse clastic unit at Hornitos, northern Chile, and instead argue for a debris flow origin for this unit. We exclude a relation to a tsunami in general and to the Eltanin impact in particular. The observed deposit at Hornitos was not generated either directly (impact-triggered tsunami) or indirectly (submarine mass flow caused by seismic shaking) by an impact. Re-calculation of the alleged impact tsunami including consideration of the Van Dorn effect shows that an impact in the Southern Ocean did not cause a significant tsunami at Hornitos. Impact-related seismic shaking was not able to trigger slides several thousands of kilometers away because the Eltanin event was a deep sea-impact that did not create a crater. Additionally, the biostratigraphic age of 5.1-2.8 Ma of the associated La Portada Formation is not concurrent with the newly established age of 2.511 ± 0.07 Ma for the Eltanin impact. Instead, we argue for an origin of the conspicuous unit at Hornitos as a debris flow deposit caused by an earthquake in the Andean subduction zone in northern Chile. Our re-interpretation considers the local synsedimentary tectonic background, a comparison to recent submarine tsunami sediments, and recent examples of mass wasting deposits along the Chilean margin. The increased uplift during the Pliocene caused oversteepening of the coastal scarp and entailed a contemporaneous higher frequency of seismic events that triggered slope failures and cliff collapses. The coarse clastic unit at Hornitos represents an extraordinary, potentially tsunami-generating mass wasting event that is intercalated with mass wasting deposits on a smaller scale.

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

    Digital Repository Service at National Institute of Oceanography (India)

    DeSouza, F.P.; Garg, A.; Bhosle, N.B.

    percentage distribution of ribose plus fucose, as well as arabinose plus galactose in a sugar fraction (calculated without glucose) to dis- tinguishplantmaterial,bacteria,phytoplanktonandzoo- plankton sources in suspended and sedimented materials 2.1. Study.... As the study site could not be approached during southwest monsoon and sediment samples. Relative inputs from calcareous and siliceous test material in sediment trap samples have been characterized using the arabinose/fucose ratio (Ittekkot, Deuser, & Degens...

  16. Radioisotopic data of sediment collected in Mobile and Bon Secour Bays, Alabama

    Science.gov (United States)

    Marot, Marci E.; Smith, Christopher G.

    2012-01-01

    The focus of this study was to determine the extent of natural and (or) anthropogenic impacts on the sedimentary records of Mobile and Bon Secour Bays, Alabama during the last 150 years. These bays are unique in that anthropogenic activities are generally widespread and span both the eastern and western shorelines. However, there is a clear distinction in the types of human development and infrastructure between the western and eastern shorelines. These activities and the differences in land-use and -change influence the overall supply and remobilization of sediment to and within the bay. These factors could subsequently threaten the health and integrity of these environments and their ability to mitigate against long-term processes associated with climate change. In an attempt to characterize long-term accretion rates within the Mobile Bay Estuarine System (MBES), seven box cores were collected and analyzed for excess lead-210 (210Pbxs, the difference between total and supported 210Pb) and cesium-137 (137Cs) activities. The MBES receives sediment and water from the Alabama and Tombigbee River watersheds, which converge into the Mobile-Tensaw River (MTR) system just prior to discharging into Mobile Bay. Riverine discharge from the MTR system to the bay is second only to the Mississippi River discharge to the Gulf of Mexico for the conterminous United States.

  17. Estimation of historic flows and sediment loads to San Francisco Bay,1849–2011

    Science.gov (United States)

    Moftakhari, H.R.; Jay, D.A.; Talke, S.A.; Schoellhamer, David H.

    2016-01-01

    River flow and sediment transport in estuaries influence morphological development over decadal and century time scales, but hydrological and sedimentological records are typically too short to adequately characterize long-term trends. In this study, we recover archival records and apply a rating curve approach to develop the first instrumental estimates of daily delta inflow and sediment loads to San Francisco Bay (1849–1929). The total sediment load is constrained using sedimentation/erosion estimated from bathymetric survey data to produce continuous daily sediment transport estimates from 1849 to 1955, the time period prior to sediment load measurements. We estimate that ∼55% (45–75%) of the ∼1500 ± 400 million tons (Mt) of sediment delivered to the estuary between 1849 and 2011 was the result of anthropogenic alteration in the watershed that increased sediment supply. Also, the seasonal timing of sediment flux events has shifted because significant spring-melt floods have decreased, causing estimated springtime transport (April 1st to June 30th) to decrease from ∼25% to ∼15% of the annual total. By contrast, wintertime sediment loads (December 1st to March 31st) have increased from ∼70% to ∼80%. A ∼35% reduction of annual flow since the 19th century along with decreased sediment supply has resulted in a ∼50% reduction in annual sediment delivery. The methods developed in this study can be applied to other systems for which unanalyzed historic data exist.

  18. Influence of suspended kelp culture on seabed sediment composition in Heini Bay, China

    Science.gov (United States)

    Liu, Yanxia; Huang, Haijun; Yan, Liwen; Liu, Xiao; Zhang, Zehua

    2016-11-01

    Kelp aquaculture activities occupy large nearshore areas with significant effects on sediment properties, primarily caused by the influence of the suspended kelp on local hydrodynamics. Changes in sediment composition and grain-size distributions were investigated prior to and following the commencement of kelp aquaculture activities in Heini Bay in eastern China. Seabed sediment types and the particulate matter in suspension during the kelp seeding and harvesting periods, and in sediment cores, were analyzed. While suspended sediment in the kelp aquaculture area was up to 20% organic material, sediment organic content on the seabed remained at similar levels as areas lacking aquaculture. The composition of the seabed sediment in the kelp aquaculture area became finer-grained by the capture of fine particles. Within the kelp aquaculture area, the sediments are poorly sorted and positively skewed, whereas at the shoreward and seaward of the aquaculture area the sediments are relatively coarse-grained, well-sorted and nearly symmetrically distributed. Therefore, the kelp aquaculture activities not only increase the fine particulate fraction in the sediments within the aquaculture area, but also result in similar deposits seaward of it, indicating that seabed erosion and accretion is also controlled by the sediment source and the hydrodynamic conditions. The analysis of sediment cores showed that kelp culturing refines the sediment by preferentially capturing particles in the 38-40 μm size class, while having no effect on the <32 μm fractions, as evidenced by the positive skew of the surficial sediments. The captured particle size class became well mixed into the sediment, thereby changing the composition of the sediment in the uppermost layer of the core, indicating the existence of continuous and stable hydrodynamic conditions within the kelp aquaculture area. The same effect was observed in the seabed sediments seaward of the aquaculture area.

  19. 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.

    (>10m). It appears that the sediment distribution in the Kalbadevi Bay is partly controlled by the east-west trending depression along the central offshore profile (OP-02). The study shows enrichment in sand and clay content during post-monsoon period...

  20. 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...

  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. Polychlorinated biphenyl source attribution in Green Bay, Wisconsin, USA, using multivariate similarity among congener profiles in sediment samples.

    Science.gov (United States)

    Cacela, Dave; Beltman, Douglas J; Lipton, Joshua

    2002-08-01

    Polychlorinated biphenyl (PCB) congener concentrations measured in 1,189 sediment samples from Green Bay (MI/WI, USA), Lake Michigan (MI/WI, USA), and the Fox River (WI, USA) were analyzed statistically to evaluate whether PCB congener profiles in outer Green Bay are more similar to those observed in inner Green Bay or Lake Michigan. Similarities among PCB profiles were assessed with complementary multivariate analysis techniques: Principal component analysis (PCA), cluster analysis, and classification trees. The PCA indicated that profiles in outer Green Bay are distinct from those of inner Green Bay or Lake Michigan but are more similar to those of inner Green Bay. The outer bay profiles are dissimilar to profiles that would result from a simple process of mixing contaminated sediments from the inner bay with Lake Michigan sediments and, therefore, support the conclusion that contaminants in outer Green Bay come from discharges of the Fox River. Several classification trees based on small sets of congener proportions defined simple rules that consistently distinguished the regional profiles. Application of these rules to classify the outer bay samples suggests that the profiles of less than 7% of outer bay samples are similar to Lake Michigan profiles. These results are interpreted with respect to physical transport and chemical weathering processes that may account for the observed differences.

  3. Effects of ghost shrimp on zinc and cadmium in sediments from Tampa Bay, FL

    Science.gov (United States)

    Klerks, P.L.; Felder, D.L.; Strasser, K.; Swarzenski, P.W.

    2007-01-01

    This study investigated the effects that ghost shrimp have on the distribution of metals in sediment. We measured levels of HNO3-extractable zinc and cadmium in surface sediment, in ghost shrimp burrow walls and in sediment ejected by the ghost shrimp from their burrows, at five sandy intertidal sites in Tampa Bay. Ghost shrimp densities and their rate of sediment ejection were also quantified, as were sediment organic content and silt + clay content. Densities of ghost shrimp (Sergio trilobata and Lepidophthalmus louisianensis) averaged 33/m2 at our sites, and they ejected sediment at an average rate of 28 g/burrow/day. Levels of both Zn and Cd were significantly higher in burrow walls than in surface sediments. Sediment ejected by the shrimp from their burrows had elevated levels of Zn (relative to surface sediments) at one of the sites. Sediment organic content and silt + clay content were higher in burrow-wall sediments than in ejected sediment, which in turn tended to have values above those of surface sediments. Differences in levels of HNO3-extractable Zn and Cd among sediment types may be a consequence of these sediments differing in other physiochemical characteristics, though the differences in metal levels remained statistically significant for some sites after correcting for differences in organic content and silt + clay content. We conclude that the presence of ghost shrimp burrows contributes to spatial heterogeneity of sedimentary metal levels, while the ghost shrimp bioturbation results in a significant flux of metals to the sediment surface and is expected to decrease heterogeneity of metal levels in sedimentary depth profiles.

  4. Estimation of suspended sediment flux from acoustic Doppler current profiling along the Jinhae Bay entrance

    Institute of Scientific and Technical Information of China (English)

    WANG Yaping; CHU Yong Shik; LEE Hee Jun; HAN Choong Keun; OH Byung Chul

    2005-01-01

    A Nortek acoustic Doppler current profiler (NDP) was installed on a moving vessel to survey the entrance to the Jinhae Bay on August 22~23, 2001. The current velocity and acoustic backscattering signal were collected along two cross-sections; water samples were also collected during the measurement. The acoustic signals were normalized to compensate for the loss incurred by acoustic beam spreading in the seawater. The in situ calibration shows that a significant relationship is present between suspended sediment concentrations (SSC) and normalized acoustic signals. Two acoustic parameters have been determined to construct an acoustic-concentration model.Using this derived model, the SSC patterns along the surveyed cross-sections were obtained by the conversion of acoustic data. Using the current velocity and SSC data, the flux of suspended sediment was estimated. It indicates that the sediment transport into the bay through the entrance has an order of magnitude of 100 t per tidal cycle.

  5. Polycyclic aromatic hydrocarbon pollution in the surface water and sediments of Chabahar Bay, Oman Sea.

    Science.gov (United States)

    Agah, Homira; Mehdinia, Ali; Bastami, Kazem Darvish; Rahmanpour, Shirin

    2017-02-15

    In the present study, the concentrations and distribution of 16 polycyclic aromatic hydrocarbons (PAHs) in the water and surface sediments from the Chabahar Bay, Oman Sea, were investigated in May (premonsoon) and December (postmonsoon) 2012. The concentrations of PAHs in the surface water samples ranged from 1.7 to 2.8ngl(-1) and from 0.04 to 59.6ngl(-1) in pre- and postmonsoon, respectively. In general, the PAH levels of the water samples from Chabahar Bay were higher in postmonsoon than in premonsoon (p<0.05). The concentrations of PAHs in the sediment samples varied from undetectable levels to 92.8ngg(-1) d.w. in both seasons. The seasonal comparison of the results in sediment samples showed that the overall concentration of PAH compounds was higher in the postmonsoon season (p<0.05).

  6. Seasonal changes of magnetic minerals and their grain sizes in the Hiroshima Bay sediments

    Science.gov (United States)

    Kawamura, N.; Ishikawa, N.

    2011-12-01

    Frequent outbreaks of red tide have been reported since 1970 in the Hiroshima bay, and the red tide is caused by a bloom of dinoflagellates. Iron is an essential element for dinoflagellates, and is supplied as bivalent or trivalent ions and iron compounds from lands to sea. For damage predictions of red tide, it is important to research the distribution of iron in the bay. The acidification of seawater during summer has been also observed in the Hiroshima Bay. Increase of CO2 concentration and decrease of dissolved oxygen (DO) content in seawater cause an anoxic condition in the bay. It is known that iron oxides are dissolved and sulfides are formed in an anoxic condition. For clarifying variations of the distribution and mode of iron in sediments and bottom water in the Hiroshima Bay, we investigated kinds of iron compounds in the sediments and the amount of dissolved iron in the bottom waters. Sediment cores of 5cm in depth were taken at three sites in the Hiroshima Bay by using a multiple corer and crab sampler. Data of oceanographic observations at these sites showed that the temperature of the bottom water increased, whereas DO and pH values decreased during the sampling period. The sediment samples were composed of clayey silt. We measured dissolved iron concentration in interstitial and bottom waters filtered above 0.45 um grains, and performed magnetic hysteresis measurements and high temperature magnetometry on the sediment samples. The presence of magnetite (Fe3O4) and hematite (Fe2O3) were recognized in all analyzed samples, whereas greigite (Fe3S4) appeared at these sites with an anoxic condition in the bottom water. Magnetic grain size increased from June to August, while iron concentration increased in the bottom waters. It is suggested that magnetite and hematite were dissolved and greigite was formed, associated with the proceeding of the anoxic condition, and that the grain-size of magnetic minerals and the iron concentration of the bottom water

  7. Sediment geochemistry of Corte Madera Marsh, San Francisco Bay, California: have local inputs changed, 1830-2010?

    Science.gov (United States)

    Takesue, Renee K.; Jaffe, Bruce E.

    2013-01-01

    Large perturbations since the mid-1800s to the supply and source of sediment entering San Francisco Bay have disturbed natural processes for more than 150 years. Only recently have sediment inputs through the Sacramento-San Joaquin Delta (the Delta) decreased to what might be considered pre-disturbance levels. Declining sediment inputs to San Francisco Bay raise concern about continued tidal marsh accretion, particularly if sea level rise accelerates in the future. The aim of this study is to explore whether the relative amount of local-watershed sediment accumulating in a tidal marsh has changed as sediment supply from the Sacramento-San Joaquin Rivers has decreased. To address this question, sediment geochemical indicators, or signatures, in the fine fraction (silt and clay) of Sacramento River, San Joaquin River, San Francisco Bay, and Corte Madera Creek sediment were identified and applied in sediment recovered from Corte Madera Marsh, one of the few remaining natural marshes in San Francisco Bay. Total major, minor, trace, and rare earth element (REE) contents of fine sediment were determined by inductively coupled plasma mass and atomic emission spectroscopy. Fine sediment from potential source areas had the following geochemical signatures: Sacramento River sediment downstream of the confluence of the American River was characterized by enrichments in chromium, zirconium, and heavy REE; San Joaquin River sediment at Vernalis and Lathrop was characterized by enrichments in thorium and total REE content; Corte Madera Creek sediment had elevated nickel contents; and the composition of San Francisco Bay mud proximal to Corte Madera Marsh was intermediate between these sources. Most sediment geochemical signatures were relatively invariant for more than 150 years, suggesting that the composition of fine sediment in Corte Madera Marsh is not very sensitive to changes in the magnitude, timing, or source of sediment entering San Francisco Bay through the Delta. Nor

  8. Dating upper plate normal fault slip events in Late Pleistocene and Holocene sediments of northern Chile

    Science.gov (United States)

    Robinson, R. A.; Binnie, S.; Gonzalez, G.; Cortés, J.

    2011-12-01

    In order to understand how subduction earthquakes along the Nazca-South America plate boundary affect upper plate faults in the coastal forearc of northern Chile, we are developing the first detailed paleoseismological study to characterize the Late Quaternary activity of the Mejillones and Salar del Carmen faults, located around 40 km north and 15 km east of Antofagasta, respectively. There is currently a lack of basic palaeo-seismological data on these and other upper plate faults, such as long term slip rates, amount of slip per event, palaeo-earthquake magnitude and recurrence intervals. This lack of knowledge impedes understanding of how large subduction earthquakes, occurring at depths of around 50 km in this region, relate to upper plate seismicity and deformation. We have used OSL dating of fault-related sediments, and cosmogenic-ray nuclide dating of terrace surfaces, to constrain slips rates over the last 45 ka. Several trenches were excavated across both faults in order to expose and log the most recent fault-related sediments. In the hanging wall of these normal faults, vertically stacked colluvial wedges and hillslope deposits are the product of discrete slip events and post-slip fault scarp degradation. Multiple trenches along each fault permit the spatial variability in slip amount and fault-related sedimentation to be investigated. Long-term slip rates have been measured using cosmogenic-ray nuclide exposure dating of the alluvial terraces offset by the Mejillones Fault. OSL dating of the fault-related sediments in the trenches has been used to compare the ages of individual slip events on both faults, and the age of events recorded along the trace of each fault. The application of both cosmogenic-ray nuclide and OSL methods in this type of setting (hyper-arid with low erosion rates, yet tectonically active) is non-trivial, due to cosmogenic inheritance accumulated in cobbles on the terrace surfaces, low sensitivity of the quartz for OSL dating, and

  9. 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...

  10. Observations of pockmark flow structure in Belfast Bay, Maine, Part 3: implications for sediment transport

    Science.gov (United States)

    Fandel, Christina L.; Lippmann, Thomas C.; Foster, Diane L.; Brothers, Laura L.

    2017-01-01

    Current observations and sediment characteristics acquired within and along the rim of two pockmarks in Belfast Bay, Maine, were used to characterize periods of sediment transport and to investigate conditions favorable to the settling of suspended sediment. Hourly averaged Shields parameters determined from horizontal current velocity profiles within the center of each pockmark never exceed the critical value (approximated with the theoretical model of Dade et al. 1992). However, Shields parameters estimated at the pockmark rims periodically exceed the critical value, consistent with conditions that support the onset of sediment transport and suspension. Below the rim in the near-center of each pockmark, depth-averaged vertical velocities were less than zero (downward) 60% and 55% of the time in the northern and southern pockmarks, and were often comparable to depth-averaged horizontal velocities. Along the rim, depth-averaged vertical velocities over the lower 8 m of the water column were primarily downward but much less than depth-averaged horizontal velocities indicating that suspended sediment may be moved to distant locations. Maximum grain sizes capable of remaining in suspension under terminal settling flow conditions (ranging 10–170 μm) were typically much greater than the observed median grain diameter (about 7 μm) at the bed. During upwelling flow within the pockmarks, and in the absence of flocculation, suspended sediment would not settle. The greater frequency of predicted periods of sediment transport along the rim of the southern pockmark is consistent with pockmark morphology in Belfast Bay, which transitions from more spherical to more elongated toward the south, suggesting near-bed sediment transport may contribute to post-formation pockmark evolution during typical conditions in Belfast Bay.

  11. Observations of pockmark flow structure in Belfast Bay, Maine, Part 3: implications for sediment transport

    Science.gov (United States)

    Fandel, Christina L.; Lippmann, Thomas C.; Foster, Diane L.; Brothers, Laura L.

    2017-02-01

    Current observations and sediment characteristics acquired within and along the rim of two pockmarks in Belfast Bay, Maine, were used to characterize periods of sediment transport and to investigate conditions favorable to the settling of suspended sediment. Hourly averaged Shields parameters determined from horizontal current velocity profiles within the center of each pockmark never exceed the critical value (approximated with the theoretical model of Dade et al. 1992). However, Shields parameters estimated at the pockmark rims periodically exceed the critical value, consistent with conditions that support the onset of sediment transport and suspension. Below the rim in the near-center of each pockmark, depth-averaged vertical velocities were less than zero (downward) 60% and 55% of the time in the northern and southern pockmarks, and were often comparable to depth-averaged horizontal velocities. Along the rim, depth-averaged vertical velocities over the lower 8 m of the water column were primarily downward but much less than depth-averaged horizontal velocities indicating that suspended sediment may be moved to distant locations. Maximum grain sizes capable of remaining in suspension under terminal settling flow conditions (ranging 10-170 μm) were typically much greater than the observed median grain diameter (about 7 μm) at the bed. During upwelling flow within the pockmarks, and in the absence of flocculation, suspended sediment would not settle. The greater frequency of predicted periods of sediment transport along the rim of the southern pockmark is consistent with pockmark morphology in Belfast Bay, which transitions from more spherical to more elongated toward the south, suggesting near-bed sediment transport may contribute to post-formation pockmark evolution during typical conditions in Belfast Bay.

  12. Sediment transport in the San Francisco Bay Coastal System: an overview

    Science.gov (United States)

    Barnard, Patrick L.; Schoellhamer, David H.; Jaffe, Bruce E.; McKee, Lester J.; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

    2013-01-01

    The papers in this special issue feature state-of-the-art approaches to understanding the physical processes related to sediment transport and geomorphology of complex coastal–estuarine systems. Here we focus on the San Francisco Bay Coastal System, extending from the lower San Joaquin–Sacramento Delta, through the Bay, and along the adjacent outer Pacific Coast. San Francisco Bay is an urbanized estuary that is impacted by numerous anthropogenic activities common to many large estuaries, including a mining legacy, channel dredging, aggregate mining, reservoirs, freshwater diversion, watershed modifications, urban run-off, ship traffic, exotic species introductions, land reclamation, and wetland restoration. The Golden Gate strait is the sole inlet connecting the Bay to the Pacific Ocean, and serves as the conduit for a tidal flow of ~ 8 × 109 m3/day, in addition to the transport of mud, sand, biogenic material, nutrients, and pollutants. Despite this physical, biological and chemical connection, resource management and prior research have often treated the Delta, Bay and adjacent ocean as separate entities, compartmentalized by artificial geographic or political boundaries. The body of work herein presents a comprehensive analysis of system-wide behavior, extending a rich heritage of sediment transport research that dates back to the groundbreaking hydraulic mining-impact research of G.K. Gilbert in the early 20th century.

  13. Mercury pollution in sediments, benthic organisms and inshore fishes of Haifa Bay, Israel

    Energy Technology Data Exchange (ETDEWEB)

    Hornung, H.; Krumgalz, B.S.; Cohen, Y.

    1984-01-01

    Total mercury concentrations were determined in surficial sediments, eleven species of benthic organisms and six species of fish from Haifa Bay, Israel. The results show that essentially all of the shallow water zone of the Bay receives anthropogenic mercury. A mercury-cell chlor-alkali plant was identified as the source of pollution. Surficial sediments in vicinity of the plant, containing up to 0.99 micro-g Hg/g dry weight, were up to 157 times enriched in mercury relative to an unpolluted area. Mercury levels in the benthic organisms reflected the levels in the sediments. Maximal concentrations reaching 38.7 and 18.2 micro-g Hg/g dry weight were found in the carnivorous gastropod mollusks Arcularia circumcinta and Arcularia gibbosula, respectively. In all fish species, specimens caught in Haifa Bay had higher mercury concentrations in the muscle tissue than specimens caught south of the Bay. A maximal value of 1.66 micro-g Hg/g wet weight was recorded in Diplodus sargus. 17 references, 3 figures, 3 tables.

  14. Geochemistry and mineralogy of recent sediments of Guanabara Bay (NE sector and its major rivers - Rio de Janeiro State - Brazil

    Directory of Open Access Journals (Sweden)

    FARIA MARCIA DE MELO

    2001-01-01

    Full Text Available Geochemical and clay mineralogical studies of bottom sediments collected along the Macacu and Caceribu rivers and Guanabara Bay were carried out in order to investigate the relationship between major source areas and recent sediments of the bay. Clay mineralogy includes different groups with selective distribution conditioned by geomorphic features and depositional settings. Micaceous clay minerals are abundant near parent rock in the upper course, whereas kaolinite derived from varied sources is gradually concentrated towards the estuary. In the Guanabara Bay, kaolinite accumulates near river mouths, while micaceous clay minerals are converted into mixed layers in the estuary. Analyses of heavy metal contents reveal higher levels of Zn and Cu in sediments of the bay than in river sediments. Profiles along rivers indicate a downstream decrease of heavy metals, whereas in the bay geochemical trends display greater variations. In general river mouth sediments present the lowest concentrations. At the north and east of Paquetá Island anomalous areas with the highest heavy metal contents occur. Cu tends to concentrate in < 2mum grain-size fraction and indicates an association with micaceous clay minerals in the upper river course. However, Cu retention seems to be further controlled by other components of bottom sediments due to changes in physical and chemical conditions of the estuarine environment. Zn shows unstable behavior along the rivers and concentrates in the bay. Pb displays small variations from river to bay sediments, and accumulates mainly in the < 63mum grain-size fraction without any association with clay mineral. Geoaccumulation indexes of Cu, Pb and Zn classify the study area as unpolluted in both studied rivers and in the NE sector of the bay, though the enrichment factors are higher in the bay. The study does not indicate those rivers as major sources of heavy metal pollution to the bay.

  15. Biochemical and microbial features of shallow marine sediments along the Terra Nova Bay (Ross Sea, Antarctica)

    Science.gov (United States)

    Baldi, Franco; Marchetto, Davide; Pini, Francesco; Fani, Renato; Michaud, Luigi; Lo Giudice, Angelina; Berto, Daniela; Giani, Michele

    2010-09-01

    Shallow marine sediments were collected from seven stations (three of which located at Gerlache Inlet, two at Tethys Bay, one at Adelie Cove and one just beneath the Italian Research Base) along the Terra Nova Bay coast (Ross Sea, Antarctica). Their chemical, biochemical and microbiological properties were studied in order to provide further insights in the knowledge of this Antarctic benthic ecosystem. Overall, the organic carbon (OC) represented the major fraction of total carbon (TC) and displayed concentrations similar to or slightly lower than those previously measured in Antarctic bottom sediments. The biopolymeric carbon within OC ranged from 4.1% to 19.9% and showed a wide trophic range (65-834 μg g -1 d.w.). Proteins (PRT) represented on average the main biochemical class contributing to labile organic carbon, followed by lipids (LIP) and carbohydrates (CHO). The activity of aminopeptidase, β- D-glucosidase, alkaline phosphatase and esterase was checked, giving the highest values at Tethys Bay and at the deepest water sediments. The principal component analysis, which was computed considering physical, chemical (elemental and biochemical sedimentary composition) and microbiological parameters (including bacterial abundance, ectoenzymatic activities, T-RFs richness and diversity indices), allowed to obtain two main clusters ("Tethys Bay" and "other stations"). Based on data obtained, two representative 16S rRNA clone libraries using samples from Tethys Bay and Gerlache Inlet were constructed. The sequences of 171 clones were compared to those available in public databases to determine their approximate phylogenetic affiliations. Both aerobic and anaerobic bacteria were disclosed, with the majority of them affiliated with the Gamma- and Deltaproteobacteria, Bacteroidetes and Acidobacteria. The occurrence of strictly anaerobic bacteria suggests that sediments might also undergo anoxic conditions that, in turn, could favor the accumulation of PRT in respect

  16. [Distribution patterns of heavy metals in surface sediments of the Quanzhou Bay and environmental quality assessment].

    Science.gov (United States)

    Li, Yun-hai; Chen, Jian; Huang, Cai-bin; Wang, Ai-jun; Li, Dong-yi

    2010-04-01

    The concentrations of 7 heavy metals were determined in 48 surface sediments in the Quanzhou Bay by an inductively coupled plasma mass spectroscopy (ICP-MS). The average contents of Cr, Ni, Cu, Zn, As, Cd and Pb are 47.66, 52.2, 30.86, 111.6, 5.29, 0.399 and 50.3 microg x g(-1), respectively. The Cd, Pb, Zn and As were mainly discharged into the Quanzhou Bay by Jinjiang River, while the materials near the Bay might supply a considerable amount of Cr, Ni and Cu. The result of the multi-analysis ecological risk index analyses revealed that Cr, Ni, Cu, Zn, Pb and As were moderately contaminated and presented low potential ecological risk, while Cd was heavily contaminated and raised high potential ecological risk. In general, moderately contaminated and potential ecological risk were occurred in whole Quanzhou Bay with the dominated polluted metals were Ni and Cd. The heavily contaminated area was corresponded to the high potential ecological risk area, which located at the confluent area of Jinjiang River and Luoyangjiang River. From the results of this study, we conclude that the Quanzhou Bay has been heavily polluted by heavy metals, therefore much environmental control should be continued and strengthen to Quanzhou Bay and its adjacent areas.

  17. The mineralogy and chemistry of fine-grained sediments, Morphou Bay, Cyprus

    Directory of Open Access Journals (Sweden)

    C. Neal

    2002-01-01

    Full Text Available The mineralogy and chemistry of the less than 20μm fraction of marine sediments at Morphou Bay, north-west Cyprus, are presented to characterise fine-grained sediment supplies from basic and ultrabasic rocks of the Troodos Massif within a typological setting. The sediments comprise a mixture of smectite, illite, kaolinite and iron rich chlorite. They also contain amorphous iron oxides/hydroxides, calcite (with some magnesium substitution for calcium and an amphibole. Spatial patterns in mineralogy occur: the near-shore sediments are rich in smectite, chlorite, amphibole and amorphous iron oxides/hydroxides, while the offshore sediments are rich in illite and calcite. The sediments are calcium, magnesium, iron, aluminium and potassium bearing, due to the presence of significant amounts of calcite (for Ca, clay minerals and aluminium and iron oxides/hydroxides. Potassium is present within the micaceous mineral illite, but it is also contained within other phases that are difficult to pinpoint. Statistical analysis reveals that the chemical composition of the sediments broadly follows the mineralogy with the dominant feature being related to spatial changes in the mineralogy. The patterns of change reflect a three component mix of clay-sized sediment types: (1 localised lithogenous sources rich in smectite with subsidiary amounts of amorphous iron oxides/hydroxides and amphibole, from Cyprus, the Troodos in particular, (2 illite rich and smectite chlorite and chlorite bearing material of lithogenous origin from other parts of the eastern Mediterranean and (3 calcite, mainly of marine origin. Keywords: smectite, illite, chlorite, kaolinite, calcite, sediments, Morphou Bay, Troodos, Cyprus, Mediterranean, calcium, potassium, magnesium, iron, silicon, phosphorus.

  18. 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.

    Amino acid enantiomeric (D/L) ratio is a stratigraphic tool of Recent sediments. The method which came into being 35 years ago1, is not a precise dating tool like, for example, the radiocarbon method, as the extent of racemization may not wholly...

  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 content...

  20. 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...

  1. 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...

  2. 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.

  3. Mineral composition of soils and bottom sediments in bays of Novaya Zemlya

    Science.gov (United States)

    Krupskaya, V. V.; Miroshnikov, A. Yu.; Dorzhieva, O. V.; Zakusin, S. V.; Semenkov, I. N.; Usacheva, A. A.

    2017-01-01

    We have analyzed the specific features of the mineralogical composition of bottom sediments of Blagopoluchiya, Tsivol'ki, and Abrosimov bays and soils on Cape Zhelaniya and the coasts of Abrosimov and Stepovoi bays. The data were obtained during two scientific expeditions of the R/V Professor Shtokman in 2014 (cruise 128) and R/V Akademik Mstislav Keldysh in 2015 (cruise 63). These investigations revealed patterns in the transportation of terrigenous material in the coastal zone of the bays: a decrease in the share of nonclay minerals and an increase in that of clay minerals with distance from shore. The increase in kaolinite and smectite content in soil horizons is related to biochemical weathering, while illite is mainly formed as a result of physical weathering.

  4. 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.

  5. Environmental and ecological risk of heavy metals in the marine sediment from Dakhla Bay, Morocco.

    Science.gov (United States)

    Hakima, Zidane; Mohamed, Maanan; Aziza, Mouradi; Mehdi, Maanan; Meryem, El Barjy; Bendahhou, Zourarah; Jean-Francois, Blais

    2017-01-20

    Heavy metal assessment in Dakhla Bay (Atlantic coast) was carried out using different environmental and ecological indices. Heavy metal concentrations were measured using ICP-AES and were compared with consensus-based sediment quality guidelines. The distribution of heavy metal concentrations varies for the three groups: (i) lead distribution is dominated by its associations with copper and chromium. These elements have the same source, most probably related to anthropogenic activities. (ii) Nickel, zinc and cobalt are associated with aluminium and iron indicating their terrigenous origin (natural content), and (iii) cadmium concentration is related to upwelling currents. This paper systematically studied the distributions and pollution levels of heavy metals in sediment in the coastal areas in Dakhla Bay, which is of scientific significance, to discuss the changing rules and the affecting factors of the harmful heavy metals and can be adopted for reference to other coastal areas.

  6. Butyltin speciation in sediments from Todos os Santos Bay (Bahia, Brazil by GC-PFPD

    Directory of Open Access Journals (Sweden)

    Juliana Feitosa Felizzola

    2008-01-01

    Full Text Available Butyltin compounds were investigated in surface sediments from 17 stations in Todos os Santos Bay. Analytical conditions for organotin determination in marine sediments were optimized for GC with pulsed flame photometric detection. Detection limits were: 5.4 µg kg-1 for TBT; 0.2 µg kg-1 for DBT; and 2.1 µg kg-1 for MBT, using a 610-nm filter. In general, TBT concentrations were low and in the range of

    sediments. The presence of paint particles in the sediments and degradation in the water column during resuspension events followed by removal of the more soluble DBT and MBT may explain these observations.

  7. Implications of excess 210Pb and 137Cs in sediment cores from Mikawa Bay, Japan

    Institute of Scientific and Technical Information of China (English)

    LU Xueqiang; MATSUMOTO Eiji

    2009-01-01

    Four sediment cores were collected from Mikawa Bay, Japan, and excess 210Pb and 137Cs were measured by gamma spectrometry. Sedimentation rates for the four cores were determined by 210Pb method. The sedimentation rate range is 0.10--0.70 g/(cm2·year). The bio-mixing depth for each core is less than 7.0 cm, and was determined by the excess 210Pb profiles as well. Therefore, the bioturbation is slight. The 210Pb-derived dates coincide with the results from 137Cs geochronology. Acceleration in sedimentation rate due to environmental alteration has been found in cores A2.5 and 05AS8, representing two depocenters due to their topography. Evidence of the Tokai Flood in 2000 was found in core 05AS8 according to the profiles of both radioisotopes and trace metals.

  8. Regional Sediment Management (RSM) Strategy for Mobile Bay, Alabama

    Science.gov (United States)

    2015-04-01

    sediment and may have long-term negative effects. Beneficial use (BU) activities were reauthorized by WRDA 96 which states that “for the Mobile Harbor... refraction and shoaling, current-induced refraction and shoaling, depth- and steepness-limited wave breaking, wind-wave generation, wave-wave...mandates demonstration that the material requires no physical, biological , or chemical testing. Key elements of this strategy emphasize connection

  9. Coastal lake sediments reveal 5500 years of tsunami history in south central Chile

    Science.gov (United States)

    Kempf, Philipp; Moernaut, Jasper; Van Daele, Maarten; Vandoorne, Willem; Pino, Mario; Urrutia, Roberto; De Batist, Marc

    2017-04-01

    We present an exceptionally long and continuous coastal lacustrine record of ∼5500 years from Lake Huelde on the west coast of Chiloé Island in south central Chile. The study area is located within the rupture zone of the giant 1960 CE Great Chilean Earthquake (MW 9.5). The subsequent earthquake-induced tsunami inundated Lake Huelde and deposited mud rip-up clasts, massive sand and a mud cap in the lake. Long sediment cores from 8 core sites within Lake Huelde reveal 16 additional sandy layers in the 5500 year long record. The sandy layers share sedimentological similarities with the deposit of the 1960 CE tsunami and other coastal lake tsunami deposits elsewhere. On the basis of general and site-specific criteria we interpret the sandy layers as tsunami deposits. Age-control is provided by four different methods, 1) 210Pb-dating, 2) the identification of the 137Cs-peak, 3) an infrared stimulated luminescence (IRSL) date and 4) 22 radiocarbon dates. The ages of each tsunami deposit are modelled using the Bayesian statistic tools of OxCal and Bacon. The record from Lake Huelde matches the 8 regionally known tsunami deposits from documented history and geological evidence from the last ∼2000 years without over- or underrepresentation. We extend the existing tsunami history by 9 tsunami deposits. We discuss the advantages and disadvantages of various sedimentary environments for tsunami deposition and preservation, e.g. we find that Lake Huelde is 2-3 times less sensitive to relative sea-level change in comparison to coastal marshes in the same region.

  10. Spatial distribution and source apportionment of PAHs in marine surface sediments of Prydz Bay, East Antarctica.

    Science.gov (United States)

    Xue, Rui; Chen, Ling; Lu, Zhibo; Wang, Juan; Yang, Haizhen; Zhang, Jie; Cai, Minghong

    2016-12-01

    This paper reports the concentrations of polycyclic aromatic hydrocarbons (PAHs) in marine sediments sampled from Prydz Bay, East Antarctica. Total PAH concentrations ranged from 12.95 to 30.93 ng/g, with a mean of 17.99 ± 5.57 ng/g. Two- and three-ring PAHs were the most abundant compounds found at the majority of the sampling stations of Prydz Bay. Long-range atmospheric transportation was found to play an important role in determining the spatial distribution of PAHs in the sediments sampled here. However, transport by ocean currents and release from melting glaciers were also found to influence PAH distributions in the sediments of East Antarctica. The vertical migration of PAHs in sediments showed a decreasing trend with depth, with higher concentrations in the relatively shallow-water regions (1000 m) of the Amery Basin and associated Canyons, respectively. A Pearson correlation analysis between PAH concentrations and sediment parameters demonstrated that PAHs has poor correlations with grain size, but has positive correlation with total organic carbon, indicated complex processing during transfer to remote environments. The results of qualitative and quantitative analyses indicate that the PAHs sampled here were derived mainly from a mixture of biomass combustion, traffic emissions, and petrogenic sources.

  11. [Distribution of matrix-bound phosphine in surface sediments of Jinpu Bay].

    Science.gov (United States)

    You, Li-Li; Zong, Hai-Bo; Zhang, Shu-Fang; Yin, Guo-Yu; Li, Tao; Hou, Li-Jun

    2013-10-01

    This work investigated the distribution of matrix-bound phosphine in surface sediments of Jinpu Bay and associated environmental factors in summer, using the gas chromatography combined with a pulsed flame detector (GC-PFPD). It showed that phosphine ubiquitously presented in the sediments of Jinpu Bay. Contents of matrix-bound phosphine varied between 62. 58 and 190. 81 ng.kg-1, with the average value of 114.42 ng.kg-1. In addition, the spatial distribution of matrix-bound phosphine indicated that matrix-bound phosphine in inshore sediments had relatively higher contents than those in offshore sediments. Statistical analysis showed that matrix-bound phosphine significantly related to organic phosphorus and alkaline phosphatase activity ( R = 0. 882, P = 0. 01; R = 0. 819, P =0. 023). However, there were no correlations between matrix-bound phosphine and organic nitrogen, inorganic phosphorus and sediment grain sizes. These results implied that accumulation and distribution of matrix-bound phosphined were mainly affected by the decomposition of organic phosphorus by microorganisms.

  12. Distribution Characteristics of Heavy Metals and Grain Size of Sediments from Hailing Bay, China

    Institute of Scientific and Technical Information of China (English)

    QIU Yaowen; ZHU Liangsheng; LI Manqiu

    2005-01-01

    The geochemical properties of sediment in the nearby seawater areas of Hailing Bay of the western Guangdong province were first time investigated in the dry period of 2001 and the flood period of 2002, respectively. The temporal and spatial characteristics of Cu, Pb, Zn, Cd and Hg concentrations, organic carbon and total sulfides contents, and granulometric distribution in the surface sediment from the Hailing Bay were analyzed. Results demonstrated that there were no remarkable changes in the composition of sediment between the dry period and the flood period;the average concentrations of Cu, Pb, Zn, Cd and Hg were 32.1 ± 17.5, 36.1 ± 10.0,respectively; surface sediments were dominated by clayey silt and sand, and their mean grain size was 4.62 ± 2.36 φ and in the range 0.52-7.55 φ; there existed obvious correlation between the concentrations of Cu, Pb, Zn and Hg, and among Cu, Pb, Zn and Hg concentrations, organic carbon contents and grain size of sediments.

  13. 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.

  14. Sediment Chemistry and Toxicity in Barnegat Bay, New Jersey: Pre- and Post- Hurricane Sandy, 2012-2013.

    Science.gov (United States)

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

    2016-01-01

    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.

  15. Presence of selected chemicals of emerging concern in water and bottom sediment from the St. Louis River, St. Louis Bay, and Superior Bay, Minnesota and Wisconsin, 2010

    Science.gov (United States)

    Christensen, Victoria G.; Lee, Kathy E.; Kieta, Kristen A.; Elliott, Sarah M.

    2012-01-01

    The St. Louis Bay of Lake Superior receives substantial urban runoff, wastewater treatment plant effluent, and industrial effluent. In 1987, the International Joint Commission designated the St. Louis Bay portion of the lower St. Louis River as one of the Great Lakes Areas of Concern. Concerns exist about the potential effects of chemicals of emerging concern on aquatic biota because many of these chemicals, including endocrine active chemicals, have been shown to affect the endocrine systems of fish. To determine the occurrence of chemicals of emerging concern in the St. Louis River, the St. Louis Bay, and Superior Bay, the U.S. Geological Survey in cooperation with the Minnesota Pollution Control Agency and the Wisconsin Department of Natural Resources collected water and bottom-sediment samples from 40 sites from August through October 2010. The objectives of this study were to (1) identify the extent to which chemicals of emerging concern, including pharmaceuticals, hormones, and other organic chemicals, occur in the St. Louis River, St. Louis Bay, and Superior Bay, and (2) identify the extent to which the chemicals may have accumulated in bottom sediment of the study area. Samples were analyzed for selected wastewater indicators, hormones, sterols, bisphenol A, and human-health pharmaceuticals. During this study, 33 of 89 chemicals of emerging concern were detected among all water samples collected and 56 of 104 chemicals of emerging concern were detected in bottom-sediment samples. The chemical N,N-diethyl-meta-toluamide (DEET) was the most commonly detected chemical in water samples and 2,6-dimethylnaphthalene was the most commonly detected chemical in bottom-sediment samples. In general, chemicals of emerging concern were detected at a higher frequency in bottom-sediment samples than in water samples. Estrone (a steroid hormone) and hexahydrohexamethyl cyclopentabensopyran (a synthetic fragrance) were the most commonly detected endocrine active chemicals in

  16. Shipboard magnetic field "noise" reveals shallow heavy mineral sediment concentrations in Chesapeake Bay

    Science.gov (United States)

    Shah, Anjana K.; Vogt, Peter R.; Rosenbaum, Joseph G.; Newell, Wayne; Cronin, Thomas M.; Willard, Debra A.; Hagen, Rick A.; Brozena, John; Hofstra, Albert

    2012-01-01

    Shipboard magnetic field data collected over Chesapeake Bay exhibit low-amplitude, short-wavelength anomalies that most likely indicate shallow concentrations of heavy mineral sediments. Piston core layers and black sand beach samples exhibit enhanced magnetic susceptibilities and carry remanent magnetization, with mineralogical analyses indicating ilmenite and trace magnetite and/or maghemite and hematite. The anomalies are subtle and would be filtered as noise using traditional approaches, but can instead be highlighted using spectral methods, thus providing nearly continuous coverage along survey tracks. The distribution of the anomalies provides constraints on relevant sorting mechanisms. Comparisons to sonar data and previous grab samples show that two of three areas surveyed exhibit short-wavelength anomalies that are clustered over sand-covered areas, suggesting initial sorting through settling mechanisms. This is supported by a correlation between core magnetic susceptibility and grain size. Near the Choptank River, where sediment resuspension is wave-dominated, anomalies show a sharp decrease with seafloor depth that cannot be explained by signal attenuation alone. In Pocomoke Sound, where both tidal currents and wave-action impact sediment resuspension, anomalies show a more gradual decrease with depth. Near the mouth of the bay, where there is a higher influx of sediments from the continental shelf, short-wavelength anomalies are isolated and do not appear to represent heavy mineral sand concentrations. These combined observations suggest the importance of further sorting by erosional processes in certain parts of the bay. Additionally, comparisons of these data to cores sampling pre-Holocene sediments suggest that the sorting of heavy minerals in higher energy, shallow water environments provides a mechanism for correlations between core magnetic susceptibility and sea-level changes.

  17. Storm and fair-weather driven sediment-transport within Poverty Bay, New Zealand, evaluated using coupled numerical models

    Science.gov (United States)

    Bever, Aaron J.; Harris, Courtney K.

    2014-09-01

    The Waipaoa River Sedimentary System in New Zealand, a focus site of the MARGINS Source-to-Sink program, contains both a terrestrial and marine component. Poverty Bay serves as the interface between the fluvial and oceanic portions of this dispersal system. This study used a three-dimensional hydrodynamic and sediment-transport numerical model, the Regional Ocean Modeling System (ROMS), coupled to the Simulated WAves Nearshore (SWAN) wave model to investigate sediment-transport dynamics within Poverty Bay and the mechanisms by which sediment travels from the Waipaoa River to the continental shelf. Two sets of model calculations were analyzed; the first represented a winter storm season, January-September, 2006; and the second an approximately 40 year recurrence interval storm that occurred on 21-23 October 2005. Model results indicated that hydrodynamics and sediment-transport pathways within Poverty Bay differed during wet storms that included river runoff and locally generated waves, compared to dry storms driven by oceanic swell. During wet storms the model estimated significant deposition within Poverty Bay, although much of the discharged sediment was exported from the Bay during the discharge pulse. Later resuspension events generated by Southern Ocean swell reworked and modified the initial deposit, providing subsequent pulses of sediment from the Bay to the continental shelf. In this manner, transit through Poverty Bay modified the input fluvial signal, so that the sediment characteristics and timing of export to the continental shelf differed from the Waipaoa River discharge. Sensitivity studies showed that feedback mechanisms between sediment-transport, currents, and waves were important within the model calculations.

  18. {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.

  19. 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.

  20. Surficial geology and distribution of post-impoundment sediment in Las Vegas Bay, Lake Mead

    Science.gov (United States)

    Twichell, David C.; Cross, VeeAnn A.; Rudin, Mark J.; Parolski, Kenneth F.; Rendigs, Richard R.

    2001-01-01

    Sidescan sonar imagery and seismic-reflection profiles were collected in the northwestern part of Las Vegas Bay to map the distribution and volume of sediment that has accumulated in this part of Lake Mead since impoundment. The mapping suggests that three ephemeral streams are the primary source of this sediment, and of these, Las Vegas Wash is the largest. Two deltas off the mouth of Las Vegas Wash formed at different lake elevations and account for 41% of the total volume of post-impoundment sediment within the study area. Deltas off the other two washes (Gypsum and Government) account for only 6% of the total volume. The sediment beyond the front of the deltas is primarily mud, and it only occurs in valley floors, where it forms a flat-lying blanket that is mostly less than 1.5 m thick. Although a thin layer, the fine-grained sediment accounts for approximately 53% of the total post-impoundment sediment volume of 5.7 x 106 m3 that has accumulated in the study area. This sediment appears to have been transported several kilometers from the river sources by density flows.

  1. 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

    mineralization, and occurrence of dense communities of the filamentous sulfur bacteria, Thioploca spp., on the continental shelf off central Chile during the austral summer when high phytoplankton productivity and anoxic bottom water prevailed. Freshly deposited phytodetritus stimulated extremely high sulfate...

  2. Concentrations and distribution of mercury and other heavy metals in surface sediments of the Yatsushiro Sea including Minamata Bay, Japan.

    Science.gov (United States)

    Nakata, Haruhiko; Shimada, Hideaki; Yoshimoto, Maki; Narumi, Rika; Akimoto, Kazumi; Yamashita, Takayuki; Matsunaga, Tomoya; Nishimura, Keisuke; Tanaka, Masakazu; Hiraki, Kenju; Shimasaki, Hideyuki; Takikawa, Kiyoshi

    2008-01-01

    The concentrations and distribution of heavy metals, such as mercury, zinc, copper, lead, and iron in surface sediments from 234 stations of the Yatsushiro Sea including Minamata bay were investigated. High concentrations of mercury were found in sediments from Minamata bay and its vicinity, but the levels decreased gradually with distance from the bay. The concentrations of mercury in sediments decreased gradually from south to north of the Yatsushiro Sea. These imply the lack of movement of mercury from Minamata bay to the northern Yatsushiro Sea. The geographical profiles of zinc and copper were contrary to that found for mercury, indicating the presence of natural and anthropogenic sources of copper and zinc in the northern Yatsushiro Sea.

  3. Bacterial diversity, composition and temporal-spatial variation in the sediment of Jiaozhou Bay, China

    Institute of Scientific and Technical Information of China (English)

    LIU Xin; XIAO Tian; LUAN Qingshan; ZHANG Wenyan; WANG Mengqiang; YUE Haidong

    2011-01-01

    Studies on the diversity and distribution of bacterial populations will improve the overall understanding of the global patterns of marine bacteria and help to comprehend local biochemical processes and environments. We evaluated the composition and the dynamics of bacterial communities in the sediment of Jiaozhou Bay (China) using PCR-denaturing gradient gel electrophoresis (DGGE). Sediment samples were collected from 10 different sites in May, August, and November 2008 and in February 2009.There was significant temporal variation in bacterial community composition at all sites. However, the spatial variation was very small. The DGGE analyses of bacterial communities were used to divide the 10 stations into three types. Canonical correspondence analysis (CCA) revealed that the changes in bacterial communities were driven by sediment properties. Sequence analysis of DGGE band-derived 16S rRNA gene fragments revealed that the dominant bacterial groups in the sediment were of the classes γ-proteobacteria and δ-proteobacteria and phyla Bacteroidetes and Nitrospirae. Our results provide considerable insight into the bacterial community structure in Jiaozhou Bay, China.

  4. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, A.P.; Figueira, R.C.L.; Silva, C.R.A.; Franca, E.J.; Mahiques, M.M.; Bicego, M.C.; Montone, R.C. [Universidade de Sao Paulo (IO/USP), SP (Brazil). Inst. Oceanografico; Martins, C.C. [Universidade Federal do Parana (UFPR), Pontal do Sul, PR (Brazil). Centro de Estudos do Mar; Scapin, M.A.; Scapin, V.O.; Figueiredo, A.M.G.; Ticianelli, R.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2010-07-01

    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 25{sup th} 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 {sup 137}Cs, 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)

  6. Sediment Retention Dynamics and Vegetation Along Three Tributaries of the Chesapeake Bay

    Science.gov (United States)

    Ross, K.; Ross, K.; Hupp, C.; Alexander, L.; Alexander, L.

    2001-12-01

    Coastal Plain riparian wetlands in the Mid-Atlantic United States are the last place for sediment and contaminant storage before reaching critical estuarine and marine environments. The deteriorating health of the Chesapeake Bay has been attributed in part to elevated sediment loads. The purpose of this study is to investigate the effects of channelization and urbanization on sediment deposition and geomorphic processes along the Pocomoke and Chickahominy Rivers and Dragon Run, three Coastal Plain tributaries. Floodplain microtopography was surveyed in 100 x 100 m grids at three characteristic reaches along each river and woody vegetation analyses were conducted. Floodplain suspended sediment concentrations and short and long-term sedimentation rates were estimated at each reach using single stage sediment sampler arrays, clay pads and dendrogeomorphic techniques, respectively. Site hydroperiod and flow characteristics were determined from USGS gaging station records, floodplain water level recorders, and field observations. Channelized floodplain reaches along the Pocomoke River are flooded less frequently, have lower mineral sedimentation rates (2 mm/yr to 6 mm/yr) and woody species diversity than the unchannelized reaches. Along the Chickahominy River, floodplain wetlands close to urban centers are flooded more frequently, but have shorter hydroperiods (3.5 days/yr compared to more than 45 days/yr), lower sedimentation rates (1.8 mm/yr to 6.8 mm/yr), and lower woody species diversity (0.51 to 1.95 on the Shannon-Weiner diversity index) than floodplains further downstream. Suspended sediment delivery and deposition rates are significantly influenced by floodplain hydroperiod duration and channel-floodplain connectivity. These results suggest that understanding floodplain sediment dynamics and geomorphic processes with respect to dominant watershed landuse patterns is critical for effective water quality management and restoration efforts.

  7. 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

  8. 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.

  9. 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.

  10. Sources of suspended-sediment flux in streams of the chesapeake bay watershed: A regional application of the sparrow model

    Science.gov (United States)

    Brakebill, J.W.; Ator, S.W.; Schwarz, G.E.

    2010-01-01

    We describe the sources and transport of fluvial suspended sediment in nontidal streams of the Chesapeake Bay watershed and vicinity. We applied SPAtially Referenced Regressions on Watershed attributes, which spatially correlates estimated mean annual flux of suspended sediment in nontidal streams with sources of suspended sediment and transport factors. According to our model, urban development generates on average the greatest amount of suspended sediment per unit area (3,928 Mg/km2/year), although agriculture is much more widespread and is the greatest overall source of suspended sediment (57 Mg/km2/year). Factors affecting sediment transport from uplands to streams include mean basin slope, reservoirs, physiography, and soil permeability. On average, 59% of upland suspended sediment generated is temporarily stored along large rivers draining the Coastal Plain or in reservoirs throughout the watershed. Applying erosion and sediment controls from agriculture and urban development in areas of the northern Piedmont close to the upper Bay, where the combined effects of watershed characteristics on sediment transport have the greatest influence may be most helpful in mitigating sedimentation in the bay and its tributaries. Stream restoration efforts addressing floodplain and bank stabilization and incision may be more effective in smaller, headwater streams outside of the Coastal Plain. ?? 2010 American Water Resources Association. No claim to original U.S. government works.

  11. Phosphorus speciation and its bioavailability in sediments of the Jiaozhou Bay

    Science.gov (United States)

    Kang, Xuming; Song, Jinming; Yuan, Huamao; Shi, Xin; Yang, Weifeng; Li, Xuegang; Li, Ning; Duan, Liqin

    2017-03-01

    Phosphorus (P) is an important macronutrient that can limit primary productivity in coastal marine ecosystems. In this study, four sediment cores were collected in the Jiaozhou Bay to study the phosphorus forms and their bioavailability, including exchangeable or loosely sorbed P (Ex-P), iron-bound P (Fe-P), authigenic P (Ca-P), detrital P (De-P) and organic P (OP), which were separated and quantified using a sequential extraction method (SEDEX). The results showed that the concentration of total P (TP) in core sediments ranged from 6.23 to 10.46 μmol/g, and inorganic P (IP) was the dominated P form. Fe-P and De-P were the main chemical forms of IP in core sediments. The profile variation of OP presented the most significant among the phosphorus forms. Whereas the concentrations of Ex-P, Fe-P, and Ca-P varied slightly with depth, indicating that the transformation of Ex-P, Fe-P, Ca-P, and OP could occur during sedimentary P burial. Moreover, the distribution of P species was influenced by many factors, including terrigenous input, biological processes, organic matter degradation and increasing human activities. High total organic carbon (TOC)/OP ratio occurred in the Jiaozhou Bay, ranging from 73 to 472 (average, 180 ± 81) in core sediments, which was caused by the increasing terrestrial organic matter. The ratio of TOC/Preactive ranged from 24 to 101 (average 46 ± 15) in core sediments (lower than the Redfield ratio), implying a surplus of sedimentary reactive P compared with TOC. Potential bioavailable P (BAP) accounted for about 28.2-60.8% (average, 47.1 ± 7.4%) of TP in core sediments, and presented an increasing trend since 1980s, which might be responsible for the shift of phytoplankton community composition during these decades.

  12. Subsoil erosion dominates the supply of fine sediment to rivers draining into Princess Charlotte Bay, Australia.

    Science.gov (United States)

    Olley, Jon; Brooks, Andrew; Spencer, John; Pietsch, Timothy; Borombovits, Daniel

    2013-10-01

    The Laura-Normanby River (catchment area: 24,350 km(2)), which drains into Princess Charlotte Bay, has been identified in previous studies as the third largest contributor of sediment to the Great Barrier Reef World Heritage Area. These catchment scale modelling studies also identified surface soil erosion as supplying >80% of the sediment. Here we use activity concentrations of the fallout radionuclides (137)Cs and (210)Pbex to test the hypothesis that surface soil erosion dominates the supply of fine (erosion being the dominant source of fine sediment in this catchment. The hypothesis that surface soil erosion dominates the supply of fine sediment to Princess Charlotte Bay is rejected. River sediment samples were collected using both time-integrated samplers and sediment drape deposits. We show that there is no detectable difference in (137)Cs and (210)Pbex activity concentrations between samples collected using these two methods. Two methods were also used to collect samples to characterise (137)Cs and (210)Pbex concentrations in sediment derived from surface soil erosion; sampling of surface-wash deposits and deployment of surface runoff traps that collected samples during rain events. While there was no difference in the (137)Cs activity concentrations for samples collected using these two methods, (210)Pbex activity concentrations were significantly higher in the samples collected using the runoff traps. The higher (210)Pbex concentrations are shown to be correlated with loss-on-ignition (r(2) = 0.79) and therefore are likely to be related to higher organic concentrations in the runoff trap samples. As a result of these differences we use a three end member mixing model (channel/gully, hillslope surface-wash and hillslope runoff traps) to determine the relative contribution from surface soil erosion. Probability distributions for (137)Cs and (210)Pbex concentrations were determined for each of the end members, with these distributions then used to estimate

  13. [Effects of sediment dredging on benthos community structure and water quality in Zhushan Bay].

    Science.gov (United States)

    Liu, Guo-Feng; Zhang, Zhi-Yong; Liu, Hai-Qin; Zhong, Ji-Cheng; Yan, Shao-Hua; Fan, Cheng-Xin

    2010-11-01

    We surveyed the changes of macro-benthos community composition and nutrients concentration in water in Zhushan Bay after it had been dredged 6 months, which aimed to remove the polluted surface sediments. The results showed that the main benthos in the dredged and un-dredged sediments were Limodrilus hoffmeisteri, Pelopia and Bellamya aeruginosa; compared to the un-dredged sediments, the bio-diversity of dredged areas became lower. However, its biomass became higher than that in un-dredged areas. Concentration range changes of TN and TP in overlying water was 1.64-4.45 mg/L and 0.133-0.258 mg/L, respectively. The post-dredged sediments were still in a higher state of nutrients for the higher concentration nutrients in overlying water, macro-benthos were the species that lived in a serious polluted water environment. Using Shannon-Weaver, Simpson, and Goodnight benthic index to evaluate the results show that the dredged area is in the moderately polluted level, but un-dredged area is in the middle-heavily polluted level. According to the benthos fauna surveys and water quality monitoring results, the effective of sediment dredging could play its role only the strict control on the external pollution resources have been made and reduces the effects of polluted water on the sediments.

  14. (129)I record of nuclear activities in marine sediment core from Jiaozhou Bay in China.

    Science.gov (United States)

    Fan, Yukun; Hou, Xiaolin; Zhou, Weijian; Liu, Guangshan

    2016-04-01

    Iodine-129 has been used as a powerful tool for environmental tracing of human nuclear activities. In this work, a sediment core collected from Jiaozhou Bay, the east coast of China, in 2002 was analyzed for (129)I to investigate the influence of human nuclear activities in this region. Significantly enhanced (129)I level was observed in upper 70 cm of the sediment core, with peak values in the layer corresponding to 1957, 1964, 1974, 1986, and after 1990. The sources of (129)I and corresponding transport processes in this region are discussed, including nuclear weapons testing at the Pacific Proving Grounds, global fallout from a large numbers of nuclear weapon tests in 1963, the climax of Chinese nuclear weapons testing in the early 1970s, the Chernobyl accident in 1986, and long-distance dispersion of European reprocessing derived (129)I. The very well (129)I records of different human nuclear activities in the sediment core illustrate the potential application of (129)I in constraining ages and sedimentation rates of the recent sediment. The releases of (129)I from the European nuclear fuel reprocessing plants at La Hague (France) and Sellafield (UK) were found to dominate the inventory of (129)I in the Chinese sediments after 1990, not only the directly atmospheric releases of these reprocessing plants, but also re-emission of marine discharged (129)I of these reprocessing plants in the highly contaminated European seas.

  15. Community structure of filamentous, sheath-building sulfur bacteria, Thioploca spp, off the coast of Chile

    DEFF Research Database (Denmark)

    Schulz, HN; Jørgensen, BB; Fossing, HA

    1996-01-01

    The filamentous sulfur bacteria Thioploca spp, produce dense bacterial mats in the shelf area off the coast of Chile and Peru. The mat consists of common sheaths, shared by many filaments, that reach 5 to 10 cm dean into the sediment, The structure of the Thioploca communities off the Bay...

  16. Inferior adaptation of bay sediments in a eutrophic shallow lake to winter season for organic matter decomposition.

    Science.gov (United States)

    Song, Na; He, Yu-Hong; Jiang, He-Long

    2016-12-01

    Sediments in lake bays receive the greatest external pollutants mainly including terrestrial plants and river macrophyte detritus. This work investigated response and adaptation of bay sediments to organic matter (OM) decomposition under cold and hot seasons. After three month and incubated at 5 °C, it was found that the total organic carbon (TOC) removal efficiencies ranged from 15.4 to 13.1% in bay sediments to 22.6-25.7% in pelagic zone. These results determined that poorer OM decomposition occurred in the bay zone during the winter months compared to pelagic zone in a eutrophic shallow lake. High-throughput sequencing and network interactions revealed that the reactions were mainly due to the changing microbial community structure and species interaction at selected areas during different seasons. The bay zone communities are poorly adapted to utilizing the more recalcitrant carbon pool than the pelagic communities. Also, even though more taxa reside in bay communities, less co-occurrences interaction between taxa occurs, which mean that less inter taxa competition for the same resource. In consideration of our study, the potential harm, such as the terrestrialization process speeding up and water quality worsening will be happened, we need to exploit ways to enhance litter biodegradation in the bay zone in winter.

  17. 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.

  18. Distribution of heavy metals and foraminiferal assemblages in sediments of Biscayne Bay, Florida, USA

    Science.gov (United States)

    Carnahan, E.A.; Hoare, A.M.; Hallock, P.; Lidz, B.H.; Reich, C.D.

    2008-01-01

    Heavy-metal pollution is an issue of concern in estuaries influenced by agriculture, urban, and harbor activities. Foraminiferal assemblages have been shown to be effective indicators of pollution. Sediment samples (n = 110) from Biscayne Bay were analyzed for heavy metals, foraminiferal assemblages, and grain-size distribution. Highest Cu, Zn, Cr, Hg, Pb, and Ni concentrations were found closest to Miami and near the mouths of several canals along the western margin of the bay. Few samples exceeded limits of possible biological effects as defined by previous studies. Ammonia and Cribroelphidium, two known stress-tolerant genera, correlated positively with Cu, Zn, Hg, and Ni (r ??? 0.43). Symbiont-bearing foraminifers, Archaias, Laevipeneroplis, and Androsina, correlated negatively with Cu, Zn, Hg, and Ni (r ??? -0.26).

  19. Polycyclic aromatic hydrocarbons in surface sediment from Yangpu Bay, China: Distribution, sources and risk assessment.

    Science.gov (United States)

    Li, Ping; Diao, Xiaoping; Zhang, Yu; Xie, Yanli; Yang, Fei; Zhou, Hailong; Han, Qian; Wang, Fuqiang; Cheng, Huamin; Wang, Haihua

    2015-10-15

    The study investigated the occurrence of polycyclic aromatic hydrocarbons (PAHs) in the surface sediment from eleven sites in Yangpu Bay, China in December 2013 (winter) and July 2014 (summer). The 16 US EPA priority PAHs were found in the range of 1583.2-5701.7 ng/g dry weights with an average of 3134.7 ± 1241.3 ng/g in winter and ranged from 2161.8 to 4527.2 ng/g with an average of 3016.6 ± 748.0 ng/g in summer, respectively. The concentrations of the PAHs tended to be relatively high in comparison with other areas from the literatures. The identification using molecular indices analysis indicated that the PAHs originated mainly from pyrogenic and petrogenic sources in most of the sites. According to principle component analysis-multiple linear regression (PCA/MLR) for their source apportionment, the main sources of PAHs were vehicle emissions, petroleum products and biomass combustion. The risk assessment using international sediments quality guidelines and sediments quality criteria indicated that several PAHs, such as Nap, Flu, Phe, Ace, Acy and BghiP in most of the sites would potentially affect organisms in Yangpu Bay.

  20. 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.

  1. Hydrography and bottom boundary layer dynamics: Influence on inner shelf sediment mobility, Long Bay, North Carolina

    Science.gov (United States)

    Davis, L.A.; Leonard, L.A.; Snedden, G.A.

    2008-01-01

    This study examined the hydrography and bottom boundary-layer dynamics of two typical storm events affecting coastal North Carolina (NC); a hurricane and the passages of two small consecutive extratropical storms during November 2005. Two upward-looking 1200-kHz Acoustic Doppler Current Profilers (ADCP) were deployed on the inner shelf in northern Long Bay, NC at water depths of less than 15 m. Both instruments profiled the overlying water column in 0.35 in bins beginning at a height of 1.35 in above the bottom (mab). Simultaneous measurements of wind speed and direction, wave and current parameters, and acoustic backscatter were coupled with output from a bottom boundary layer (bbl) model to describe the hydrography and boundary layer conditions during each event. The bbl model also was used to quantify sediment transport in the boundary layer during each storm. Both study sites exhibited similar temporal variations in wave and current magnitude, however, wave heights during the November event were higher than waves associated with the hurricane. Near-bottom mean and subtidal currents, however, were of greater magnitude during the hurricane. Peak depth-integrated suspended sediment transport during the November event exceeded transport associated with the hurricane by 25-70%. Substantial spatial variations in sediment transport existed throughout both events. During both events, along-shelf sediment transport exceeded across-shelf transport and was related to the magnitude and direction of subtidal currents. Given the variations in sediment type across the bay, complex shoreline configuration, and local bathymetry, the sediment transport rates reported here are very site specific. However, the general hydrography associated with the two storms is representative of conditions across northern Long Bay. Since the beaches in the study area undergo frequent renourishment to counter the effects of beach erosion, the results of this study also are relevant to coastal

  2. Hydrodynamics and Associated Sediment Transport over Coastal Wetlands in Quanzhou Bay,China

    Institute of Scientific and Technical Information of China (English)

    WANG Ai-jun

    2011-01-01

    Coastal salt marshes represent an important coastal wetland system.In order to understand the differences between boundary layer parameters of vegetated and unvegetated areas,as well as the mechanisms of sediment transport,several electromagnetic current meters(AEM HR,products of Alec Electronics Co.Ltd.)were deployed in coastal wetlands in Quanzhou Bay,China,to measure current velocity.During the low tide phase,the surficial sediment was collected at 10 m intervals.In situ measurements show that the current velocities on the bare flat were much higher than those in the Spartina alterniora marsh.Current velocity also varied with distance from marsh edge and plant canopy height and diameter.Around 63% of the velocity profiles in the tidal creek can be described by a logarithmic equation.Over the bare flat and Spartina alterniglora marsh,a logarithmic profile almost occurs during the flood tide phase.Sediment analysis shows that mean grain size was 6.7(D along the marsh edge,and surface sediments were transported from bare flat to marsh;the tidal creeks may change this sediment transport pattern.The hydrodynamics at early flood tide and late ebb tide phases determined the net transport direction within the study area.

  3. The distribution of inorganic phosphorus in modern sediments of the Bay of Biscay; La distribution du phosphore inorganique dans les sediments modernes du golfe de Gasgogne

    Energy Technology Data Exchange (ETDEWEB)

    Anschutz, P.; Hyacinthe, Ch.; Carbonel, P.; Jouanneau, J.M.; Jorissen, F. [Bordeaux-1 Univ., 33 - Talence (France). Dept. de Geologie et d`Oceanographie, UMR CNRS 5805

    1999-06-01

    The phosphorus geochemistry on the bay of Biscay margin shows that modern sediments represent a source of phosphate for overlying seawater. However, particulate phosphorus leached with an ascorbate solution and 1 N HCl remains constant in the sedimentary column which suggests that inorganic particulate phosphorus is trapped in the sediment. This is due to bioturbation, which carries iron oxides with high adsorption capacities for phosphate deep into the sediment, and also, to the precipitation of authigenic phosphate minerals in the anaerobic zone of the sediment. (authors) 17 refs.

  4. Extraordinary sediment delivery and rapid geomorphic response following the 2008-2009 eruption of Chaitén Volcano, Chile

    Science.gov (United States)

    Major, Jon J.; Bertin, Daniel; Pierson, Thomas C.; Amigo, Álvaro; Iroumé, Andrés.; Ulloa, Héctor; Castro, Jonathan

    2016-07-01

    The 10 day explosive phase of the 2008-2009 eruption of Chaitén volcano, Chile, draped adjacent watersheds with a few cm to >1 m of tephra. Subsequent lava-dome collapses generated pyroclastic flows that delivered additional sediment. During the waning phase of explosive activity, modest rainfall triggered an extraordinary sediment flush which swiftly aggraded multiple channels by many meters. Ten kilometer from the volcano, Chaitén River channel aggraded 7 m and the river avulsed through a coastal town. That aggradation and delta growth below the abandoned and avulsed channels allow estimates of postdisturbance traction-load transport rate. On the basis of preeruption bathymetry and remotely sensed measurements of delta-surface growth, we derived a time series of delta volume. The initial flush from 11 to 14 May 2008 deposited 0.5-1.5 × 106 m3 of sediment at the mouth of Chaitén River. By 26 May, after channel avulsion, a second delta amassed about 2 × 106 m3 of sediment; by late 2011 it amassed about 11 × 106 m3. Accumulated sediment consists of low-density vesicular pumice and lithic rhyolite sand. Rates of channel aggradation and delta growth, channel width, and an assumed deposit bulk density of 1100-1500 kg m-3 indicate mean traction-load transport rate just before and shortly after avulsion (˜14-15 May) was very high, possibly as great as several tens of kg s-1 m-1. From October 2008 to December 2011, mean traction-load transport rate declined from about 7 to 0.4 kg-1 m-1. Despite extraordinary sediment delivery, disturbed channels recovered rapidly (a few years).

  5. Extraordinary sediment delivery and rapid geomorphic response following the 2008–2009 eruption of Chaitén Volcano, Chile

    Science.gov (United States)

    Major, Jon J.; Bertin, Daniel; Pierson, Thomas C.; Amigo, Alvaro; Iroume, Andres; Ulloa, Hector; Castro, Jonathan M.

    2016-01-01

    The 10 day explosive phase of the 2008–2009 eruption of Chaitén volcano, Chile, draped adjacent watersheds with a few cm to >1 m of tephra. Subsequent lava-dome collapses generated pyroclastic flows that delivered additional sediment. During the waning phase of explosive activity, modest rainfall triggered an extraordinary sediment flush which swiftly aggraded multiple channels by many meters. Ten kilometer from the volcano, Chaitén River channel aggraded 7 m and the river avulsed through a coastal town. That aggradation and delta growth below the abandoned and avulsed channels allow estimates of postdisturbance traction-load transport rate. On the basis of preeruption bathymetry and remotely sensed measurements of delta-surface growth, we derived a time series of delta volume. The initial flush from 11 to 14 May 2008 deposited 0.5–1.5 × 106 m3 of sediment at the mouth of Chaitén River. By 26 May, after channel avulsion, a second delta amassed about 2 × 106 m3 of sediment; by late 2011 it amassed about 11 × 106 m3. Accumulated sediment consists of low-density vesicular pumice and lithic rhyolite sand. Rates of channel aggradation and delta growth, channel width, and an assumed deposit bulk density of 1100–1500 kg m−3 indicate mean traction-load transport rate just before and shortly after avulsion (∼14–15 May) was very high, possibly as great as several tens of kg s−1 m−1. From October 2008 to December 2011, mean traction-load transport rate declined from about 7 to 0.4 kg−1 m−1. Despite extraordinary sediment delivery, disturbed channels recovered rapidly (a few years).

  6. Steroid markers to assess sewage and other sources of organic contaminants in surface sediments of Cienfuegos Bay, Cuba.

    Science.gov (United States)

    Tolosa, I; Mesa, M; Alonso-Hernandez, C M

    2014-09-15

    Analyses of faecal steroids in coastal sediments from Cienfuegos Bay Cuba indicate chronic sewage contamination at the main outfalls from the city, where concentrations of coprostanol up to 5400ngg(-)(1) (dry wt) were measured. In contrast, steroid concentrations and compositions from sites from the south part of the Bay are characteristic of uncontaminated sewage environments. The levels of coprostanol in the Cienfuegos sediments compares to the lower to mid-range of concentrations reported for coastal sediments on a world-wide basis, with sedimentary levels markedly below those previously reported for heavily impacted sites. This study delivers baseline data for further investigation of the effectiveness of the proposed sewerage plan promoted by the GEF project in Cienfuegos. Investigations on the correlations between faecal steroids and other organic contaminants confirmed that the major source of petroleum hydrocarbons within the bay was associated with the sewage effluents from the Cienfuegos city.

  7. Acute and chronic toxicity of sediment samples from Guanabara Bay (RJ during the rainy period

    Directory of Open Access Journals (Sweden)

    Luciane Alves Maranho

    2010-06-01

    Full Text Available Guanabara Bay is a marine-estuarine environment of high ecological and socio-economic importance, subject to a variety of environmental impacts. Sediment is the eventual repository for most substances introduced into water bodies and may, therefore, provide an integrated measure of the environmental quality, which can be assessed by many different approaches. In this project, the quality of sediments from Guanabara Bay was evaluated by the ecotoxicological approach: whole-sediment toxicity tests, using Tiburonella viscana, and porewater, elutriate and sediment-water interface chronic toxicity tests, using embryos of Lytechinus variegatus, were applied. Sediments were collected at 14 sampling stations, distributed across the bay. Chronic tests showed significant toxicity in most of the sediment samples. Sediments from stations 1, 2, 3, 6, 8, 10, 11, 12 and 15 showed acute toxicity as well. The results of the different tests were well correlated, and their integration showed that the sediments analyzed were considered unsuitable for aquatic life, resulting in the environmental degradation of Guanabara Bay. In this context, the control of pollution sources and multi-purpose management are required to improve the environmental quality.A Baía de Guanabara é um ambiente marinho-estuarino de grande relevância ecológica e sócio-econômica, e sujeita a uma ampla gama de impactos ambientais. O sedimento é o principal destino para a maioria das substâncias introduzidas nos corpos d'água, podendo fornecer uma medida integrada da qualidade ambiental, a qual pode ser avaliada por várias abordagens. Neste projeto, a qualidade de sedimentos da Baía de Guanabara foi por uma abordagem ecotoxicológica, por meio de testes de toxicidade aguda de sedimento integral, utilizando Tiburonella viscana, e testes de toxicidade crônica de água intersticial, elutriato e interface sedimento-água, utilizando embriões de Lytechinus variegatus. Os sedimentos foram

  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.

    2016-01-01

    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.

  9. 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.

  10. Phylogenetic analysis of Beggiatoa spp. from organic rich sediment of Tokyo Bay, Japan.

    Science.gov (United States)

    Kojima, Hisaya; Fukui, Manabu

    2003-07-01

    Nitrate-accumulating filamentous bacteria from organic rich sediment of Tokyo Bay, morphologically similar to Beggiatoa species, were phylogenetically analyzed. From several sites in Tokyo Bay, Beggiatoa-like bacteria were collected. Each sample contained narrower or wider type (10 and 30 microns, respectively) of trichomes. With the nested PCR using specific primers for Beggiatoa, fragments of 16S rRNA gene were amplified and then subjected to denaturing gradient gel electrophoresis (DGGE) analysis. Sequencing and the following phylogenetic analysis indicated that they are related to large Beggiatoa species. The wider type was related to uncultured Beggiatoa clones of other geographical localities and distinct from the narrower type in Tokyo Bay. Among the narrower types, a sample from a tidal flat was genetically distinct from the sample from sites of 10 and 20 m water depth. These narrower types form a new branch in Beggiatoa/Thioploca cluster. The result of phylogenetic analysis was in accordance with the previous studies that indicate possession of nitrate-accumulation capability is congruent with phylogeny based on 16S rRNA sequences.

  11. Polychlorinated biphenyls in sediments and fish species from the Murchison Bay of Lake Victoria, Uganda.

    Science.gov (United States)

    Ssebugere, Patrick; Sillanpää, Mika; Wang, Pu; Li, Yingming; Kiremire, Bernard T; Kasozi, Gabriel N; Zhu, Chaofei; Ren, Daiwei; Zhu, Nali; Zhang, Haidong; Shang, Hongtao; Zhang, Qinghua; Jiang, Guibin

    2014-06-01

    Polychlorinated biphenyls (PCBs) were determined in sediments and two fish species collected from the Murchison Bay in Lake Victoria, using high resolution gas chromatography coupled to a high resolution mass spectrometer. Total PCB concentrations (Σ18PCBs) varied widely with mean values ranging from 777 to 4325pg g(-1) dry weight (dw) for sediments and 80 to 779pg g(-1) wet weight (ww) for fish. The PCB levels in the sediments were significantly higher at the station closest to Nakivubo channel, presumably due to effluents discharged by the channel, which may contain domestically produced commercial PCB mixtures. For fish, the concentrations in Nile perch (Lates niloticus) were significantly greater than those in Nile tilapia (Oreochromis niloticus) at all study stations, possibly due to dietary differences among species. World Health Organization-toxic equivalents (WHO2005-TEQs) for the dioxin-like PCBs were 0.04-0.64pg g(-1) dw and 0.01-0.39pg g(-1) ww for sediments and fish, respectively. The non-ortho PCBs exhibited the highest contribution to the Σ12TEQs (>75%) compared to the mono-ortho PCBs in both fish species. The TEQs in the present study were lower than many reported worldwide in literature for fish and were within the permissible level recommended by the European Commission, implying that the fish did not pose health hazards related to PCBs to the consumers.

  12. An evaluation of temporal changes in sediment accumulation and impacts on carbon burial in Mobile Bay, Alabama, USA

    Science.gov (United States)

    Smith, Christopher G.; Osterman, Lisa E.

    2014-01-01

    The estuarine environment can serve as either a source or sink of carbon relative to the coastal ocean carbon budget. A variety of time-dependent processes such as sedimentation, carbon supply, and productivity dictate how estuarine systems operate, and Mobile Bay is a system that has experienced both natural and anthropogenic perturbations that influenced depositional processes and carbon cycling. Sediments from eight box cores provide a record of change in bulk sediment accumulation and carbon burial over the past 110 years. Accumulation rates in the central part of the basin (0.09 g cm−2) were 60–80 % less than those observed at the head (0.361 g cm−2) and mouth (0.564 g cm−2) of the bay. Sediment accumulation in the central bay decreased during the past 90 years in response to both anthropogenic (causeway construction) and natural (tropical cyclones) perturbations. Sediment accumulation inevitably increased the residence time of organic carbon in the oxic zone, as observed in modeled remineralization rates, and reduced the overall carbon burial. Such observations highlight the critical balance among sediment accumulation, carbon remineralization, and carbon burial in dynamic coastal environments. Time-series analysis based solely on short-term observation would not capture the long-term effects of changes in sedimentation on carbon cycling. Identifying these relationships over longer timescales (multi-annual to decadal) will provide a far better evaluation of coastal ocean carbon budgets.

  13. 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.

  14. 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.

  15. 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.

  16. Distribution and sources of hydrocarbons in surface sediments of Gemlik Bay (Marmara Sea, Turkey).

    Science.gov (United States)

    Unlü, Selma; Alpar, Bedri

    2006-07-01

    Seabottom sediments from Gemlik Bay, one of the most polluted spots in SW Marmara Sea, were analyzed for parent polycyclic aromatic hydrocarbons (PAHs) using gas chromatography-mass spectrometry. The concentration of 14 PAH compounds in sediment samples collected from 61 locations are distributed in a broad spectrum from low to very high concentration levels (50.8-13482 ng g-1). No significant correlation was found between summation operatorPAHs and organic carbon content while summation operatorPAHs increase slightly with silt/clay ratio. Therefore the distribution and concentrations of PAHs would be determined more by direct input, rather than by the type of sediment found locally. The most polluted areas are distributed nearshore eastern (Gemlik) and southern (Kursunlu, Mudanya and Trilye) coasts which are mainly influenced by rapid ecotourism development, direct discharges from rivers, surface run-off and drainage from port areas, domestic and industrial effluent discharges through outfalls and various contaminants from ships. Special PAH compound ratios, such as Phe/Anth, Flu/Py, B[a]A/Chry; LMWPAH/HMWPAH; Per/; Per/summation operatorPAH; Per/summation operator(penta-aromatics) and Flu/(Py+Flu), were calculated to evaluate different hydrocarbon origins and their relative importance. Pyrolytic activity is dominant along the highly-populated eastern and southern coasts. Meanwhile, petrogenic activity mixed with pyrolytic activity is a matter of fact in front of the main industrial-tourism ports and anchoring areas as well. Higher concentration of perylene are distributed along the mostly polluted eastern and southern coastal areas, however, the concentrations of perylene relative to the penta-aromatic isomers are dominant especially in the northern and deepest sectors of the bay, indicating diagenetic origin for the presence of perylene.

  17. Relative Contribution of Endocrine-disrupting Chemicals to the Estrogenic Potency of Marine Sediments of Osaka Bay, Japan

    OpenAIRE

    KOYAMA, Jiro; KITOH, Asami; NAKAI, Makoto; KOHNO, Kumiko; Tanaka, Hiroyuki; Uno, Seiichi; コヤマ, ジロウ; キトウ, アサミ; ナカイ, マコト; コウノ, クミコ; タナカ, ヒロユキ; ウノ, セイイチ; 小山, 次朗; 中井, 誠; 河野, 久美子

    2013-01-01

    Although concentrations of endocrine-disrupting chemicals (EDCs) in seawaters of Japan are relatively low, vitellogenin and ovotestis inductions are still being observed in some males of mullet and flounder collected in coastal areas. These fish species are benthic and could be affected by EDCs in marine sediments. Therefore, the concentrations of EDCs in marine sediments of Osaka Bay were determined by LC-MS/MS. In addition, the estrogen receptor binding potencies as estrogenic potencies of ...

  18. Diatoms and aquatic palynomorphs in surface sediments of the White Sea bays as indicators of sedimentation in marginal filters of rivers

    Science.gov (United States)

    Polyakova, Ye. I.; Novichkova, Ye. A.; Lisitzin, A. P.; Shevchenko, V. P.; Kravchishina, M. D.

    2016-03-01

    Diatom algae, aquatic palynomorphs, and the grain-size of surface sediments from bays of the White Sea were investigated in a program dedicated to the study of marginal filters (MF) in the Severnaya Dvina, Onega, and Kem rivers. Three microalgal assemblages are established in surface sediments, which replace each other successively with distance from river mouths and are characterized by a gradual decrease in a share of freshwater species of diatoms and Chlorophyceae algae, significantly varying concentrations of marine diatoms and dinocysts due to changes in water salinity, grain-size composition of sediments, quantitative distribution of suspended particulate matter (SPM), and water productivity at different marginal filter stages.

  19. Controls on subsurface methane fluxes and shallow gas formation in Baltic Sea sediment (Aarhus Bay, Denmark)

    Science.gov (United States)

    Flury, Sabine; Røy, Hans; Dale, Andrew W.; Fossing, Henrik; Tóth, Zsuzsanna; Spiess, Volkhard; Jensen, Jørn Bo; Jørgensen, Bo Barker

    2016-09-01

    Shallow gas accumulates in coastal marine sediments when the burial rate of reactive organic matter beneath the sulfate zone is sufficiently high and the methanogenic zone is sufficiently deep. We investigated the controls on methane production and free methane gas accumulation along a 400 m seismo-acoustic transect across a sharp transition from gas-free into gas-bearing sediment in Aarhus Bay (Denmark). Twelve gravity cores were taken, in which the pore water was analyzed for inorganic solutes while rates of organic carbon mineralization were measured experimentally by 35SO42- radiotracer method. The thickness of organic-rich Holocene mud increased from 5 to 10 m along the transect concomitant with a shallowing of the depth of the sulfate-methane transition from >4 m to 2.5 m. In spite of drastic differences in the distribution of methane and sulfate in the sediment along the transect, there were only small differences in total mineralization, and methanogenesis was only equivalent to about 1% of sulfate reduction. Shallow gas appeared where the mud thickness exceeded 8-9 m. Rates of methanogenesis increased along the transect as did the upward diffusive flux of methane. Interestingly, the increase in the sedimentation rate and Holocene mud thickness had only a modest direct effect on methanogenesis rates in deep sediments. This increase in methane flux, however, triggered a shallowing of the sulfate-methane transition which resulted in a large increase in methanogenesis at the top of the methanogenic zone. Thus, our results demonstrate a positive feedback mechanism that causes a strong enhancement of methanogenesis and explains the apparently abrupt appearance of gas when a threshold thickness of organic-rich mud is exceeded.

  20. Diversity and distribution of bacterial community in the coastal sediments of Bohai Bay, China

    Institute of Scientific and Technical Information of China (English)

    WANG Liping; ZHENG Binghui; LEI Kun

    2015-01-01

    In order to understand the diversity and distribution of the bacterial community in the coastal sediment of the Bohai Bay, China, high-throughput barcoded pyrosequencing of the 16S rRNA gene was used. Metagenomic DNA was extracted from the sediment samples, and was sequenced using a 454 GS FLX Titanium system. At 97%similarity, the sequences were assigned to 22 884 operational taxonomic units (OTUs) which belonged to 41 phyla, 84 classes, 268 genera and 789 species. At the different taxonomic levels, both the dominants and their distribution varied significantly among the six coastal sediments. Proteobacteria was the first dominant phylum across all the six coastal sediments, representing 57.52%, 60.66%, 45.10%, 60.92%, 56.63% and 56.59%, respectively. Bacteroidetes was the second dominant phylum at Stas S1, S2 and S4, while Chloroflexi was the second dominant phylum at Stas S3, S5 and S6. At class level,γ-Proteobacteria was the first dominant class at Stas S1, S2, S4 and S6, whileδ-Proteobacteria became the first dominant class at Stas S3 and S5. In addition, a large proportion of unclassified representatives have distributed at the different taxonomic levels. Canonical correspondence analysis (CCA) results indicated that the sediment texture, water depth (D), dissolved oxygen (DO), total nitrogen (TN) and nine EPA priority control polycyclic aromatic hydrocarbons (PAHs) including naphthalene, acenaphthylene, acenaphthene, fluorine, phenanthrene, fluoranthene, pyrene, benzo[a]anthracene and indeno[1,2,3-cd]pyrene were the important factors in regulating the bacterial community composition. Those results are very important to further understand the roles of bacterial community in the coastal biogeochemical cycles.

  1. Relation of lead exposure to sediment ingestion in mute swans on the Chesapeake Bay, USA

    Science.gov (United States)

    Beyer, W.N.; Day, D.; Morton, Alexandra; Pachepsky, Y.

    1998-01-01

    Forty-two mute swans (Cygnus olor ) were collected from unpolluted portions of central Chesapeake Bay in spring 1995. Their intestinal digesta were analyzed for 13 metals (Al, B, Ba, Cd, Cu, Fe, Mg, Mn, Ni, Pb, Sr, V, Zn) and for acid-insoluble ash, a marker of sediment. Because metal concentrations in digesta depend on recent exposure, they are appropriate for evaluating local contamination. Swan livers and sediment samples also were analyzed for the same metals. Group method of data handling demonstrated that the digesta Al was the best predictor of digesta Pb, and that adding concentrations of other metals as predictors did not improve the accuracy of the estimates of Pb concentrations from Al concentrations. The r2 of the equation relating the log of digesta Pb to the log of digesta Al was 0.86, whereas the r2 of the equation relating the log of digesta Pb to the log of digesta acid-insoluble ash was 0.50. Sediment ingestion was critical in determining exposure to Pb, as well as to some of the other metals, and should be considered in ecotoxicological risk assessments of waterfowl. The mean of 7.4% acid-insoluble ash in the digesta corresponded to an estimated 3.2% sediment in the diet. The Pb concentrations in the digesta were 2-3 times the concentration that would have been predicted from sediment Pb concentrations; presumably the swans had ingested clays high in Pb that had settled on the vegetation. The swans were not thought to have been exposed to high Cu concentrations but they had hepatic Cu concentrations that would be considered very high if found in other species.

  2. Seasonal and spatial characteristics of seawater and sediment at Youngil Bay, southeast coast of Korea.

    Science.gov (United States)

    Lee, Mikyung; Bae, Wookeun; Chung, Jinwook; Jung, Hoi-Soo; Shim, Hojae

    2008-01-01

    The seasonal geochemical characteristics of the seawater and sediments and the major factors causing heavy metal contamination were investigated at the Youngil bay and the Hyungsan river estuary in the Southeast Coast of Korea, where a world-scale steel-industry complex (Pohang iron and steel industrial complex, POSCO) is located. The seasonal and spatial distribution characteristics of temperature, dissolved oxygen (DO), pH, and nutrients of the seawater were studied at 45 fixed stations, especially focusing on the river mouth area. Sediments at 27 stations were examined during winter and summer to determine the major controlling factors for the distribution of metals, using correlation matrix and R-mode factor analyses, and to evaluate the pollution status, using the modified geoaccumulation (I(geo)(')) index. Temperatures for the effluent from the POSCO located at the Hyungsan river mouth were 2-3 degrees C higher compared to other sampling areas, due to the thermal discharge from the POSCO. The DO concentration of the surface water at the Pohang old port was as low as 2-4 mg/L. In spring, the DO value at the Hyungsan river mouth was higher than 12 mg/L, by the mass multiplication of phytoplanktons at the river mouth where seawater temperature and nutrients concentrations were relatively high, resulting in the pH value of higher than 8.3. The nitrogen to phosphorus (N/P) ratios at the river mouth were 20-150 times higher compared to other areas, implying that the nitrogen loading into this semi-enclosed bay is significantly higher than phosphorus and the major nitrogen sources are not only the domestic sewage from the city but the industrial wastewater from the POSCO and other steel factories nearby. The phosphorus concentrations at the Pohang old port were shown 3-10 times higher than those at other stations, due to the inflow of pollutants generated from the nearby ships anchoring and the release of phosphate from the bottom sediment. Results from the sediment

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

    Science.gov (United States)

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

    2003-01-01

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

  4. Seasonal changes of viable diatom resting stages in bottom sediments of Xiamen Bay, China

    Science.gov (United States)

    Chen, Chang-ping; Sun, Lin; Gao, Ya-hui; Zhou, Qian-qian; Zheng, Min-hua; Li, Bin-qian; Yu, Yang; Lu, Dou-ding

    2009-02-01

    The seasonal abundance of planktonic diatoms in the water column of Xiamen Bay, China, was investigated monthly during 2007 and 2008, and the viability of their resting stages in the bottom sediments was estimated using the extinction dilution method (most probable number method, MPN). The dominant genera in the planktonic diatom community were Skeletonema, Chaetoceros and Thalassiosira, whose viable resting stages were also the most abundant in the sediments. The highest concentration of viable diatom resting stages occurred 1 to 2 months after the maximum cell density of diatom communities occurred in the water column. The viability of Skeletonema resting cells increased in the sediments in either April or May at each station before the start of a Skeletonema bloom in June or July, suggesting that the germination of resting cells suspended in water could have influenced the blooming of Skeletonema species in the summer. Canonical correspondence analysis and multiple linear regression analysis revealed that the MPN of viable diatom resting stages was negatively correlated with silicate ( p concentration ( p > 0.05). The distribution of viable Chaetoceros resting spores and viable Skeletonema resting cells was different, possibly due to the different silicate cost in sea water during the formation of resting spores and resting cells, and also their survival ability in unfavorable environments.

  5. Chemistry and toxicity of sediments from San Diego Bay, including a biomarker (P450 RGS) response

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, J.W. [Columbia Analytical Services, Carlsbad, CA (United States); Newton, F.C.; Hardin, J. [MEC Analytical Systems, Carlsbad, CA (United States); Tukey, R.H. [Univ. of California, San Diego, CA (United States). Dept. of Pharmacology; Richter, K.E. [NRaD, San Diego, CA (United States)

    1996-12-31

    Thirty sediment samples were collected from the vicinity of the Naval Docking Facility in San Diego Bay and used to conduct bioassays with amphipods, oyster larvae, Microtox, and a new rapid screening test called the cytochrome P450 Reporter Gene System (RGS). This RGS cell line, from a human liver cancer cell, has been engineered to produce luciferase, when the CYP1A1 gene on the chromosome is induced by toxic and carcinogenic organics (dioxin, coplanar PCBs, PAHs). Elutriates were tested with both Microtox and oyster larvae, and organic extracts of sediments were tested with Microtox and the P450 RGS assay. Chemical analyses included total organic carbon (TOC), and acid volatile sulfides (AVS) along with a wide range of metals and organic chemicals. The simultaneously extracted metals (SEM) to AVS ratio was compared to the toxic response of oyster larvae and amphipods. Along each of the piers sampled, contaminant concentrations decreased with distance from shore. A correlation matrix analysis of all biological and chemical data was conducted. The strongest correlation between a chemical measurement and a biological response was that of total PAH versus the P450 RGS response. The use of P450 RGS as a screening tool to assess the relative risk of contaminants on sediments is biologically meaningful, and is a rapid and inexpensive means of determining which samples require complete chemical characterization.

  6. High Prevalence of Gammaproteobacteria in the Sediments of Admiralty Bay and North Bransfield Basin, Northwestern Antarctic Peninsula

    Science.gov (United States)

    Franco, Diego C.; Signori, Camila N.; Duarte, Rubens T. D.; Nakayama, Cristina R.; Campos, Lúcia S.; Pellizari, Vivian H.

    2017-01-01

    Microorganisms dominate most Antarctic marine ecosystems, in terms of biomass and taxonomic diversity, and play crucial role in ecosystem functioning due to their high metabolic plasticity. Admiralty Bay is the largest bay on King George Island (South Shetland Islands, Antarctic Peninsula) and a combination of hydro-oceanographic characteristics (bathymetry, sea ice and glacier melting, seasonal entrance of water masses, turbidity, vertical fluxes) create conditions favoring organic carbon deposition on the seafloor and microbial activities. We sampled surface sediments from 15 sites across Admiralty Bay (100–502 m total depth) and the adjacent North Bransfield Basin (693–1147 m), and used the amplicon 454-sequencing of 16S rRNA gene tags to compare the bacterial composition, diversity, and microbial community structure across environmental parameters (sediment grain size, pigments and organic nutrients) between the two areas. Marine sediments had a high abundance of heterotrophic Gammaproteobacteria (92.4% and 83.8% inside and outside the bay, respectively), followed by Alphaproteobacteria (2.5 and 5.5%), Firmicutes (1.5 and 1.6%), Bacteroidetes (1.1 and 1.7%), Deltaproteobacteria (0.8 and 2.5%) and Actinobacteria (0.7 and 1.3%). Differences in alpha-diversity and bacterial community structure were found between the two areas, reflecting the physical and chemical differences in the sediments, and the organic matter input. PMID:28210255

  7. 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...

  8. Pyrosequencing evidence for iron-cycling microbial communities in sediments of the Skagerrak and Bothnian Bay

    Science.gov (United States)

    Reyes, Carolina; Dellwig, Olaf; Noriega-Ortega, Beatriz; Dähnke, Kirstin; Gehre, Matthias; Böttcher, Michael E.; Friedrich, Michael W.

    2015-04-01

    The diversity and metabolic pathways of microorganisms linked to Fe cycling in marine sediments are still poorly understood. Marine microorganisms in general are difficult to isolate and those that have been successfully isolated may not represent the main endogenous population. Various culture-independent techniques have been applied to characterize marine microbial communities, but only recently, has high throughput pyrosequencing been applied in marine sediment studies. Initial results are promising in capturing the full complexity of microbial communities in sediments. We performed a pyrosequencing-based study in marine and brackish sediments of the Baltic Sea; to our knowledge this is the first pyrosequencing study focused on the zone of Fe cycling. The goal of this study was to determine the bacterial and archaeal community composition near the sediment surface showing ongoing Fe cycling as a first step in characterizing the microorganisms potentially involved in Fe cycling. Two 35-cm-cores were sampled from ferruginous sediments in the Skagerrak, SK, North-Baltic Sea and the Bothnian Bay, BB, Northern Baltic Sea. Porewater (Fe2+, Mn2+, SO42-) and solid phase (Fe, Mn, total S) concentrations were measured and 16S rRNA genes were analysed using 454-pyrosequencing. Additionally, stable S and O isotope signatures of dissolved sulfate were measured at SK site. Sediment biogeochemistry indicated an intense suboxic zone with accumulation of dissolved Fe in the top 30 cm but only minor net sulfate (SO42-) reduction at both sites. Pore water profiles showed Fe2+ and Mn2+ levels of ~140-150 µM throughout the core below a 6 cm thick oxidized surface layer in SK sediments and ~300 µM below a 2 cm thick surface layer in BB sediments. Dissolved sulfide levels were below the detection limit in both sediments. Stable S and O isotope signatures suggest only minor net sulfate reduction. Fe reduction in the studied sediments is dominated by microbial dissimilatory Fe

  9. 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

  10. Seasonal variability in the surface sediments of Mobile Bay, Alabama, recorded by geochemistry and foraminifera, 2009–2010

    Science.gov (United States)

    Umberger, D.K.; Osterman, L.E.; Smith, C.G.; Frazier, J.; Richwine, K.A.

    2012-01-01

    A study was undertaken in order to document and quantify recent environmental change in Mobile Bay, Alabama. The study was part of the Northern Gulf of Mexico (NGOM) Ecosystem Change and Hazard Susceptibility project, a regional project funded by the Coastal and Marine Geology Program to understand how natural forcings and anthropogenic modifications influence coastal ecosystems and their susceptibility to coastal hazards. Mobile Bay is a large drowned-river estuary that has been modified significantly by humans to accommodate the Port of Mobile. Examples include repeated dredging of a large shipping channel down the central axis of the bay and construction of a causeway across the head of the bay and at the foot of the bayhead delta. In addition to modifications, the bay is also known to have episodic periods of low oxygen (hypoxia) that result in significant mortality to fish and benthic organisms (May, 1973). For this study a series of surface sediment samples were collected. Surface benthic foraminiferal and bulk geochemical data provide the modern baseline conditions of the bay and can be used as a reference to changing environmental parameters in the past (Osterman and Smith, in press) and into the future. This report archives data collected as part of the Mobile Bay Study that may be used in future environmental change studies.

  11. Definition of a mobilizing volume of sediment in a valley interested by volcanic eruption: Rio Blanco valley (Chile)

    Science.gov (United States)

    Oss-Cazzador, Daniele; Iroumé, Andrés; Picco, Lorenzo

    2016-04-01

    Volcanic explosive activity can strongly affect the riverine environments. Deposition of tephra, pyroclastic and hyperconcentrated flows along both the valley bottom and hillslopes can radically change the environmental morphology. Accumulation and transport of pyroclastic material can increase hazards and risks for anthropic activities. The aims of this research are to evaluate and quantify the amount of erodible sediment that can be transported along a gravel bed river affected by a volcanic eruption. The Rio Blanco valley (Chile) was upset by the plinian-type eruption of Chaiten volcano in 2008. The great amount of tephra released in the initial phase and the subsequent pyroclastic flows, accumulated up to 8 m of sediment over a great portion of the Rio Blanco valley. Using aerial photographs was possible to define the extension of vegetated zones affected by the eruption. The area was interested by a high mortality of vegetation, as confirmed by field surveys. Dendrometric measurements permitted to quantify the volume of wood and observe that renewal and herbal layer are almost absent, determining low soil cohesion and easier erosion by superficial and river erosion processes. Analysis of sediment accumulation allowed quantifying the volume of sediment that can be transported downstream. The analyses were carried out considering 7 km-long a reach, from the river mouth to the confluence between Caldera creek and Rio Blanco. After the eruption, was possible to define as a total area of about 2.19 km2 was affected by tephra deposition, the 40% (0,87 km2) was eroded by flows, while 60% (1,32 km2) is still present and composed by tephra, buried large wood (LW) and dead standing trees. Considering an average high of 5 m, the potential erodible sediment is around 6,5 x 106 m3, moreover there is a potential amount of about 7,3 x 104 m3 of LW that can be transported towards mouth. These analyses can be useful to better define the management plan for the river delta. In

  12. 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

  13. 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.

  14. 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.

    to 6.3 g rnw2 year-’ m the deep trap (Fig. 5). Similarly, in the central traps, annual illite flux increased with depth from 3.6 to 4.7 g me2 year-‘. Smectite fluxes also increased with depth from 1.1 to 3.3 g m-’ year-’ and 3.7 to 5.0 g mP2 year... of the cup rotating mechanism, Cup no. 11 of the deep trap in the central Bay of Bengal collected material for a period of 54 days from 26 August to 19 October 1988. The northern mooring had three time-series sediment traps (968, 1498 and 2029 m below...

  15. 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.

  16. 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.

  17. Temporal changes in TBT pollution in water, sediment, and oyster from Jinhae Bay after the total ban in South Korea.

    Science.gov (United States)

    Kim, Nam Sook; Hong, Sang Hee; Yim, Un Hyuk; Shin, Kyung-Hoon; Shim, Won Joon

    2014-09-15

    Temporal change in tributyltin (TBT) levels in Jinhae Bay, which has various TBT sources, was investigated in water, sediments, and oysters from 2003 to 2013 after its total ban in South Korea. The seawater TBT levels decreased over 500-fold from 1995/97 to 2008/09. The oyster TBT levels were about fourfold lower in 2012/13 than in 1995/97. However, the sediment TBT levels did not significantly change, even 10 years after the partial TBT ban on small ships and 7 years after the total TBT ban on all oceangoing vessels in Korea. The total ban of TBT use effectively reduced water and oyster TBT levels in Jinhae Bay, but TBT levels in water, oysters, and sediment remained above the global environmental quality standards established to protect marine organisms.

  18. 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.

  19. 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.

  20. 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

  1. Effects of dam construction on sediment phosphorus variation in a semi-enclosed bay of the Seto Inland Sea, Japan

    Science.gov (United States)

    Jin, Guangzhe; Onodera, Shin-ichi; Amano, Atsuko; Saito, Mitsuyo; Shimizu, Yuta; Satou, Takaharu

    2013-12-01

    This study investigated the effects of dam construction on sediment phosphorus concentrations in a semi-enclosed bay in western Japan. Long sediment core samples spanning over 100 years were collected from the bay, and their P fractions were analyzed. Sediment P concentrations and the P accumulation rate in an artificial lake increased after the construction of a coastal dam in 1959. The amount of P accumulated in the 60 years after the dam construction was ˜1.7 times that prior to the dam construction. Moreover, concentrations of mobile forms of P, primarily redox-sensitive P species, were higher in freshwater sediments above the dam than in saline sediments below the dam. The redox-sensitive forms of P in freshwater sediments increased sharply after the dam construction, from 100 to ˜900 μg/g, accompanied by a decrease in chloride (Cl-) concentrations to 1980s, the lake still has a high trophic level. The presently high mobile P concentrations in surface sediments may lead to high-magnitude P releases with environmental changes in the future.

  2. 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.

  3. Glaciomarine sedimentation and landforms in Admiralty Bay, South Shetland Islands, Antarctica

    Science.gov (United States)

    Magrani, Fabio; Ayres Neto, Arthur; Vieira, Rosemary

    2015-04-01

    This work consists on the integration and interpretation of high-resolution seismic profiles, geological sampling and multibeam bathymetry in order to analyze and understand the evolution of the deglaciation of Admiralty Bay, South Shetland Islands, Antarctica, since the Last Glacial Maximum (LGM). Data were obtained from three expeditions to Antarctica between 2009 and 2013, totaling 500 km of seismic lines and five geological cores. The characterization of the bottom geology was performed by analyzing the echocharacters and the sedimentary thickness of the glaciomarine deposits. Its correlation with the collected samples provided interpretation of the depositional paleoenvironments, allowing the reconstruction and evolution of the glaciers since the LGM and the recognition of glaciomarine processes. Multibeam bathymetry also provided records of submarine landforms related to glacial events and changes in positions of glaciers in the region. In this way, we ought to answer the question: which glaciomarine records are present in Admiralty Bay that can broaden our understanding of the evolution of its deglaciation during the advances and retreats of glaciers that once dominated the fjord, and its sedimentary processes? Four different echocharacters have been identified. Echoes I and II show good resolution and are characterized by continuous and sharp echoes with sub-parallel reflections and the presence of glaciomarine muds. Very prolonged echoes and absence of sub-parallel reflectors characterizes Echoes III and IV. Eco III is associated with the shallower portions of the bay, with little sediment thickness, sandier content and presence of ice rafted debris. Eco IV is associated with morainical banks and grounding zones. Seabed landform features show that the region experienced major glacial advance, with subsequent rapid retreat of the glaciers in the deeper parts of the fjord, followed by slower retreat, with the presence of several recessional moraines in the

  4. 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.

  5. The intertidal soft sediments and their macrofauna in the Greater Swansea Bay area (Worm's Head to Nash Point), South Wales

    Science.gov (United States)

    Shackley, Susan E.

    1981-05-01

    The zonation and abundance of the infauna of 11 soft shores in the Greater Swansea Bay area are described in relation to sediment grain size composition and exposure to wave action. Faunal associations are more characteristic of a boreal sand community but with reduced species diversity. Exposure to wave action accounts, at least in part, for this reduced fauna but the combined effects of industrial and urban development in the Swansea Bay area cannot be ignored. This study provides a baseline for future work in a region subject to pollution, completing the infaunal species lists for the northern coastline of the Bristol Channel.

  6. Temporal and spatial distributions of sediment mercury at salt pond wetland restoration sites, San Francisco Bay, CA, USA

    Science.gov (United States)

    Miles, A.K.; Ricca, M.A.

    2010-01-01

    Decommissioned agricultural salt ponds within south San Francisco Bay, California, are in the process of being converted to habitat for the benefit of wildlife as well as water management needs and recreation. Little is known of baseline levels of contaminants in these ponds, particularly mercury (Hg), which has a well established legacy in the Bay. In this study we described spatial and short-term temporal variations in sediment Hg species concentrations within and among the Alviso and Eden Landing salt ponds in the southern region of San Francisco Bay. We determined total Hg (Hgt) and methylmercury (MeHg) in the top 5 cm of sediment of most ponds in order to establish baseline conditions prior to restoration, sediment Hgt concentrations in a subset of these ponds after commencement of restoration, and variation in MeHg concentrations relative to sediment Hgt, pH, and total Fe concentrations and water depth and salinity in the subset of Alviso ponds. Inter-pond differences were greatest within the Alviso pond complex, where sediment Hgt concentrations averaged (arithmetic mean) 0.74 ??g/g pre and 1.03 ??g/g post-restoration activity compared to 0.11 ??g/g pre and post at Eden Landing ponds. Sediment Hgt levels at Alviso were fairly stable temporally and spatially, whereas MeHg levels were variable relative to restoration activities across time and space. Mean (arithmetic) sediment MeHg concentrations increased (2.58 to 3.03 ng/g) in Alviso and decreased (2.20 to 1.03 ng/g) in Eden Landing restoration ponds during the study. Differences in MeHg levels were related to water depth and pH, but these relationships were not consistent between years or among ponds and were viewed with caution. Factors affecting MeHg levels in these ponds (and in general) are highly complex and require in-depth study to understand.

  7. Geochemical records of phosphorus in Jiaozhou Bay sediments-Implications for environmental changes in recent hundred years

    Institute of Scientific and Technical Information of China (English)

    DAI Jicui; SONG Jinming; LI Xuegang; YUAN Huamao; ZHENG Guoxia; LI Ning

    2007-01-01

    Phosphorus is a key element and plays an important role in global biogeochemical cycles. The evolution of sedimentary environment is also influenced by phosphorus concentrations and fractions as well as phosphate sorption characteristics of the marine sediments. The geochemical characteristics of phosphorus and their environmental records were presented in Jiaozhou Bay sediments.Profiles of different forms of phosphorus were measured as well as the roles and vertical distributions of phosphorus forms in response to sedimentary environment changes were investigated. The results showed that inorganic phosphorus (IP) was the major fraction of total phosphorus (TP); phosphorus which is bound to calcium, iron and occluded phosphorus, as well as the exchangeable phosphorus were the main forms of IP, especially calcium - phosphorus, including detrital carbonate-bound phosphorus (Det- P) and authigenic apatite-bound phosphorus (ACa- P), are the uppermost constituent of IP in Jiaozhou Bay sediments. Moreover, the lead-210 chronology technology was employed to estimate how much phosphorus was buried ultimately in sediments. And the research showed that the impacts of human activities have increased remarkably in recent years especially between the 1980s and 2000. According to research, the development of Jiaozhou Bay environment in the past hundred years can be divided into three stages: (1) before the 1980s characterized by the relatively low sedimentation rate, weak land-derived phosphorus inputs and low anthropogenic impacts; (2) from the 1980s to around 2000, accelerating in the 1990s, during which high sedimentation rates, high phosphorus abundance and burial fluxes due to the severe human activities impacted on the whole environmental system; (3) after 2000, the period of the improvement of environment, the whole system has been improved including the decreasing sedimentation rates, concentration and the burial fluxes of phosphorus.

  8. Distribution of total mercury in surface sediments of the western Jade Bay, Lower Saxonian Wadden Sea, southern North Sea.

    Science.gov (United States)

    Jin, Huafang; Liebezeit, Gerd; Ziehe, Daniel

    2012-04-01

    A total of 114 surface sediment samples was equidistantly collected in the western part of the Jade Bay, southern North Sea, to analyse total mercury contents as well as grain size distribution and total organic carbon (TOC) contents. Total mercury was determined by oxygen combustion-gold amalgamation. Validation, precision and accuracy of the method were evaluated and controlled with two certified reference materials (HISS-1 and MESS-3). Total mercury contents varied between 8 and 243 ng/g dry sediment with a mean value of 103 ng/g dw. The mercury levels in surface sediments showed an inhomogeneous spatial distribution with higher contents in near-dike areas. The values are mostly in the range of natural background values (50–100 ng/g dw) and positively related to TOC and clay/silt contents (Jade Bay are not mercury contaminated. These results also suggested that the current mercury contents of Jade Bay surficial sediments are mostly affected by atmospheric deposition and re-emission.

  9. Heavy mineral analysis for assessing the provenance of sandy sediment in the San Francisco Bay Coastal System

    Science.gov (United States)

    Wong, F. L.; Woodrow, D. L.; McGann, M. L.

    2012-12-01

    Heavy minerals have been used to trace the sources and transportation of sandy sediment in San Francisco Bay and nearby coastal areas since the 1960s. We have the opportunity to sample similar environments and revisit the heavy mineral populations under the current San Francisco Coastal System study of the provenance of beach sand. Most of the sandy sediment in San Francisco Bay can be traced to distant sources including the Sierra Nevada batholith and associated terranes with local contributions from the Franciscan Complex. Heavy minerals from Sierran sources include ordinary hornblende, metamorphic amphiboles, and hypersthene while those from the Franciscan Complex include other types of pyroxene, epidote, basaltic hornblende, and glaucophane... Tertiary strata and volcanics in the surrounding hills and displaced Sierran rocks found on the continental shelf west of the San Andreas Fault Zone introduce similar minerals, but perhaps in a lesser volume to be identified as major contributors... The primary result of cluster analysis of heavy minerals separated from sand-sized sediment taken within San Francisco Bay, the adjacent continental shelf, local beaches, cliffs outside the Golden Gate, and upstream drainages indicate a widespread occurrence of sediment traceable to the Sierra Nevada. A second cluster of samples identifies samples of mixed Sierran and Franciscan lineage within the strait of the Golden Gate, on the San Francisco bar, and on coastal beaches. Sediment samples with predominantly Franciscan mineral content appear on beaches around Point Reyes, possibly transported from the Russian River. The heavy mineral composition supports transport from the east, through San Francisco Bay and out the Golden Gate to the San Francisco bar and southward.

  10. Increased terrestrial to ocean sediment and carbon fluxes in the northern Chesapeake Bay associated with twentieth century land alteration

    Science.gov (United States)

    Saenger, C.; Cronin, T. M.; Willard, D.; Halka, J.; Kerhin, R.

    2008-01-01

    We calculated Chesapeake Bay (CB) sediment and carbon fluxes before and after major anthropogenic land clearance using robust monitoring, modeling and sedimentary data. Four distinct fluxes in the estuarine system were considered including (1) the flux of eroded material from the watershed to streams, (2) the flux of suspended sediment at river fall lines, (3) the burial flux in tributary sediments, and (4) the burial flux in main CB sediments. The sedimentary maximum in Ambrosia (ragweed) pollen marked peak land clearance (~1900 a.d.). Rivers feeding CB had a total organic carbon (TOC)/total suspended solids of 0.24??0.12, and we used this observation to calculate TOC fluxes from sediment fluxes. Sediment and carbon fluxes increased by 138-269% across all four regions after land clearance. Our results demonstrate that sediment delivery to CB is subject to significant lags and that excess post-land clearance sediment loads have not reached the ocean. Post-land clearance increases in erosional flux from watersheds, and burial in estuaries are important processes that must be considered to calculate accurate global sediment and carbon budgets. ?? 2008 Coastal and Estuarine Research Federation.

  11. Contaminant profiles for surface water, sediment, flora and fauna associated with the mangrove fringe along middle and lower East Tampa Bay

    Science.gov (United States)

    Contaminant concentrations are reported for surface water, sediment, seagrass, mangroves, Florida Crown conch, blue crabs and fish collected during 2010-2011 from the mangrove fringe along eastern Tampa Bay. Concentrations of trace metals, chlorinated pesticides, atrazine, total ...

  12. 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 sites...

  13. 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...

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

    Science.gov (United States)

    Ligero, R A; Barrera, M; Casas-Ruiz, M

    2005-01-01

    This second part of the study reports the development of a model to describe the vertical migration of the artificial radioisotope (137)Cs 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 (137)Cs 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.

  15. Influential factors on the exchange rate of dissolved inorganic nutrients at the sediment-water interface in Jiaozhou Bay, China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Incubation experiments are carried out to study the exchange rates of dissolved inorganic nutrients including silicate, phosphate, ammonium, nitrite, and nitrate (vSiO3-Si, vPO4-P, vNH4-N, vNO2-N and vNO3-N) at the sediment-water interface in the Jiaozhou Bay. Major factors influencing the exchange rates are discussed in detail, which include the dissolved inorganic nutrient concentrations in porewater (Cpw), water and clay contents,and grain size of the sediments (CH2O, Cclay and GSsed). The results may provide insight into the dynamics of nutrient transport and the environmental capacity of nutrients in Jiaozhou Bay, and should be beneficial to solving the problems caused by excessive nutrient input this area.

  16. Metal pollution status in Zhelin Bay surface sediments inferred from a sequential extraction technique, South China Sea.

    Science.gov (United States)

    Gu, Yang-Guang; Lin, Qin; Jiang, Shi-Jun; Wang, Zhao-Hui

    2014-04-15

    Surface sediments collected from Zhelin Bay, the largest mariculture base of eastern Guangdong Province, were analyzed for total metal concentrations and chemical speciation. The results demonstrated that the average total concentration (mg/kg) ranges were 36.7-65.8 (Pb), 53.8-98.8 (Cr), 39.0-87.1 (Ni), 50.9-144.5 (Cu), and 175.0-251.2 (Zn), which were clearly higher with respect to their corresponding benchmark values. The predominant speciation of Pb was reducible and comprised a residual fraction, whereas a major portion (57.6-95.4%) of Cr, Ni, Cu, and Zn was strongly associated with the residual fractions. Taking as a whole, surface sediments of Zhelin Bay had a 21% probability of toxicity based on the mean effects range-median quotient.

  17. 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.

  18. 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.

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

    Science.gov (United States)

    Fan, Wenhong; Xu, Zhizhen; Wang, Wen-Xiong

    2014-08-01

    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.

  20. [Heavy metals in the surface sediment of the dumping ground outside Jiaozhou Bay and their potential ecological risk].

    Science.gov (United States)

    Cao, Cong-hua; Zhang, Nai-xing; Wu, Feng-cong; Sun, Bin; Ren, Rong-zhu; Sun, Xu; Lin, Sen; Zhang, Shao-ping

    2011-05-01

    Based on the monitoring data of heavy metals (Cr, Hg, Cd, Pb, Zn, Cu) in the surface sediment of the dumping ground outside Jiaozhou Bay from 2003 to 2008, the distribution patterns, factors controlling the distribution, and the potential ecological risks of heavy metals were studied with the data in 2007-08, and the fluctuation trends of heavy metals in the surface sediment over the 6 years were also discussed. The average concentrations of heavy metals Cr, Hg, Cd, Pb, Zn, Cu in the surface sediment were 29.47, 0.065, 0.105, 1.145, 9.63, 3.355 microg/g, respectively. Except for Cr, the concentration of heavy metals was high in the central dumping area while low outside the dumping ground, suggesting that the dredged material dumped was the main source of heavy metals. Organic carbon content in the surface sediment had a significant positive correlation with heavy metals except for Cr. Based on the results of ecological risk assessment, Hg had a medium potential ecological risk, while the other heavy metals had low potential ecological risk. The overall risk index (RI) of the heavy metals was 100.50, which was considered as a level of low potential ecological risk. The average concentration of heavy metals showed a decreasing trend over the 6 years, except Hg. In conclusion, the quality of surface sediment in term of heavy metals in the dumping ground outside Jiaozhou Bay is relatively good.

  1. Biogeochemical study of water and bottom sediments from the Khai river - Nha Trang Bay estuarine system, South China Sea

    Science.gov (United States)

    Shulga, Natalia; Lobys, Nikolay; Drozdova, Anastasia; Peresypkin, Valery

    2014-05-01

    The present study was carried out in Nha Trang Bay (Southern Vietnam, the South China Sea). The samples of water, suspended matter and bottom sediments were collected in summer 2010-2012 in section from the estuary of the Khai River to the marine part of the bay. The samples were analyzed in the stationary lab of IO RAS, Moscow, by TOC-V-CPH, GC/MS and pirolysis methods. We report here the novel data on sources, transformation and burial of OM coming from the Khai river waters. The investigation is focused on ontent and distribution of suspended matter (SM) in the estuary, dissolved organic carbon (DOC), particulated organic carbon (POC); molecular and group composition of hydrocarbons (n-alkanes, steranes, hopanes) and mercury content in water, SM and bottom sediments. It was found that concentration of POC and SM decrease in the Nha Trang Bay waters from estuary to the open part of the bay. However, major changes in the concentration of SM and POC belong to the zone of salinity gradient.DOC behavior is more stable throughout the study area. Organic-geochemical indicators estimation allowed recognition of genesis and transformation degree of organic matter in the study area. The estuary is characterized by mixed genesis of SM with a predominance of allochthonous organic matter whereas outlying parts of the Nha Trang bay are characterized by autochthonous OM. Composition of OM in sediments reflects regularities identified above, despite of the interannual and seasonal variability in the study area. The investigation reveals a predominance of terrestrial organic matter in the silt sediments of the estuary, transported by the Khai river. Distribution of OM in sediments of marine part of the bay is mosaic, with a predominance of planktonogenic, bacterial or terrestrial input at their complex combination. Local anthropogenic pollution as well as an impact of industrial city effluents are found in river- and seaport areas. According to obtained data sedimentation rate

  2. 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,...

  3. Modeling bed-load transport of coarse sediments in the Great Bay Estuary, New Hampshire

    Science.gov (United States)

    Bilgili, A.; Swift, M. R.; Lynch, D. R.; Ip, J. T. C.

    2003-12-01

    Current, sea level and bed-load transport are investigated in the Lower Piscataqua River section of the Great Bay Estuary, New Hampshire, USA—a well-mixed and geometrically complex system with low freshwater input, having main channel tidal currents ranging between 0.5 and 2 m s -1. Current and sea level forced by the M 2M 4M 6 tides at the estuarine mouth are simulated by a vertically averaged, non-linear, time-stepping finite element model. The hydrodynamic model uses a fixed boundary computational domain and accounts for flooding-drying of tidal flats by making use of a groundwater component. Inertia terms are neglected in comparison with pressure gradient and bottom friction terms, which is consistent with the observed principal dynamic balance for this section of the system. The accuracy of hydrodynamic predictions in the study area is demonstrated by comparison with four tidal elevation stations and two cross-section averaged current measurements. Simulated current is then used to model bed-load transport in the vicinity of a rapidly growing shoal located in the main channel of the lower system. Consisting of coarse sand and gravel, the shoal must be dredged every five to eight years. Two approaches are taken—an Eulerian parametric method in which nodal bed-load flux vectors are averaged over the tidal cycle and a Lagrangian particle tracking approach in which a finite number of sediment particles are released and tracked. Both methods yield pathways and accumulations in agreement with the observed shoal formation and the long-term rate of sediment accumulation in the shoal area.

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

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaswamy, V.; Parthiban, G.

    with generally higher fluxes during December and January. Annual fluxes decreased from 41.2 g m/2 y/1 in the northern Bay of Bengal to 19.69 g m/2 y/1 in the southern Bay of Bengal. As compared to the Arabian Sea, the observed particle fluxes in the Bay of Bengal...

  5. 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.

  6. Diversity of mercury resistance determinants among Bacillus strains isolated from sediment of Minamata Bay.

    Science.gov (United States)

    Narita, Masaru; Chiba, Kazuyuki; Nishizawa, Hiroshi; Ishii, Hidenori; Huang, Chieh-Chen; Kawabata, Zen'ichiro; Silver, Simon; Endo, Ginro

    2003-06-06

    Thirty mercury-resistant (Hg R) Bacillus strains were isolated from mercury-polluted sediment of Minamata Bay, Japan. Mercury resistance phenotypes were classified into broad-spectrum (resistant to inorganic Hg(2+) and organomercurials) and narrow-spectrum (resistant to inorganic Hg(2+) and sensitive to organomercurials) groups. Polymerase chain reaction (PCR) product sizes and the restriction nuclease site maps of mer operon regions from all broad-spectrum Hg R Bacillus were identical to that of Bacillus megaterium MB1. On the other hand, the PCR products of the targeted merP (extracellular mercury-binding protein gene) and merA (intracellular mercury reductase protein gene) regions from the narrow-spectrum Hg R Bacillus were generally smaller than those of the B. megaterium MB1 mer determinant. Diversity of gene structure configurations was also observed by restriction fragment length polymorphism (RFLP) profiles of the merA PCR products from the narrow-spectrum Hg R Bacillus. The genetic diversity of narrow-spectrum mer operons was greater than that of broad-spectrum ones.

  7. 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.

  8. 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%-67%, respectively

  9. Application of {sup 137}Cs and {sup 210}Pb radionuclides to determine sedimentation rates of recent sediments from Admiralty Bay, Antarctica Peninsula

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Mylene Giseli do; Martins, Cesar de Castro [Universidade Federal do Parana (UFPR), Pontal do Parana, PR (Brazil). Centro de Estudos do Mar (CEM); Figueira, Rubens C.L.; Montone, Rosalinda C.; Mahiques, Michel M. de; Tessler, Moyses G., E-mail: rfigueira@usp.b [Universidade de Sao Paulo (USP), SP (Brazil). Inst. Oceanografico. Dept. de Oceanografia Fisica, Quimica e Geologica; Vendrame, Antonio C. [Universidade Cruzeiro do Sul, Sao Paulo, SP (Brazil)

    2009-07-01

    Studies about natural and artificial radionuclides in areas such as the Antarctic are key to understand natural and dynamic processes in marine environments. These studies are important to determine levels of radioactive elements and local sedimentation rates. Five marine sediment cores were collected in different points of Admiralty Bay, in the Antarctic Peninsula. The purpose of this study was to determine {sup 137}Cs, {sup 226}Ra and {sup 210}Pb and sedimentation rates at each site. {sup 137}Cs, {sup 210}Pb and {sup 226}Ra were assayed by gamma-counting through direct measurement of the peak at 661 keV, 47 keV and 609 keV, respectively. Sedimentation rates were obtained by {sup 137}Cs and {sup 210}Pb (CIC and CRS). The activities for {sup 137}Cs ranged from 0.84 to 7.09 Bq kg{sup -1}; to {sup 226}Ra from 6.77 to 31.07 Bq kg{sup -1} for {sup 210}Pb ranged from 1.10 to 36.90 Bq kg{sup -1}. The sedimentation rates obtained by the three models ranged from 0.11+-0.01 cm y{sup -1} to 0.46+-0.05 cm y{sup -1}. The levels of {sup 137}Cs registered in this study, as well as in other studies in the Antarctic region indicate that global fallout is the main cause of artificial radionuclides present in this environment, since the Antarctic has not suffered a direct action of human activities that released radioactive elements. The possible grain size variations that occur in the studied points of Admiralty Bay may explain the differences found in the vertical distribution of radionuclides, because of the different values of sedimentation rates and respective dating determined in their profiles. (author)

  10. 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

  11. 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.

  12. The deep biosphere in terrestrial sediments in the Chesapeake Bay area, Virginia, USA

    Directory of Open Access Journals (Sweden)

    Anja eBreuker

    2011-07-01

    Full Text Available For the first time quantitative data on the abundance of Bacteria, Archaea and Eukarya in deep terrestrial sediments are provided using multiple methods (total cell counting, quantitative real-time PCR (Q-PCR and catalyzed reporter deposition – fluorescence in situ hybridization (CARD-FISH. The oligotrophic (organic carbon content of ~ 0.2 % deep terrestrial sediments in the Chesapeake Bay area at Eyreville, Virginia, USA, were drilled and sampled up to a depth of 140 m in 2006. The possibility of contamination during drilling was checked using fluorescent microspheres. Total cell counts decreased from 109 to 106 cells per g dry weight (dw within the uppermost 20 m depth, and did not further decrease with depth below. A significant proportion of the total cell counts could be detected with CARD-FISH within the uppermost 7 m depth. The CARD-FISH numbers for Bacteria were about an order of magnitude higher than those for Archaea. The dominance of Bacteria over Archaea was confirmed by Q-PCR. The down core quantitative distribution of prokaryotic and eukaryotic small subunit ribosomal RNA genes as well as functional genes involved in different biogeochemical processes was revealed by Q-PCR for the uppermost 10 m and for 80-140 m depth. Eukarya and the Fe(III- and Mn(IV-reducing bacterial group Geobacteriaceae were almost only found in the uppermost meter (arable soil, where reactive iron was detected in higher amounts. The bacterial candidate division JS-1 and the classes Anaerolineae and Caldilineae of the phylum Chloroflexi, highly abundant in marine sediments, were found up to the maximum sampling depth in high copy numbers at this terrestrial site as well. A similar high abundance of the functional gene cbbL encoding for the large subunit of RubisCO suggests that autotrophic microorganisms could be relevant in addition to heterotrophs. The functional gene aprA of sulfate reducing bacteria was found within distinct layers up to ca. 100 m depth

  13. Potential sources of hydrogel stabilization of Florida Bay lime mud sediments and implications for organic matter preservation

    Science.gov (United States)

    Louda, J.W.; Loitz, J.W.; Melisiotis, A.; Orem, W.H.

    2004-01-01

    The fine grained carbonate mud sediments of central Florida Bay are resuspended quite easily. However, this disturbance is usually limited to the surficial ('floc') layer, as the underlying sediments appear to be stabilized by an hydrogelation involving the bulk organic matter. That gelation has occurred within these sediments is suggested from their physical behavior and an observed mathematical relationship between the percentages of organic carbon (C org) and water. Specifically, when extruded from a core barrel, the sediment maintains its integrity and has the consistency of a fine spackling compound. However, upon homogenization, as with a stirring rod prior to sieving, these sediments break into two distinct phases, 1/2-2/3 milky water and 1/3-1/2 sediment grains, by volume. The relationship observed between Corg and water was modeled as both linear (% water = (0.0777) Corg + 0.2984, R2 = 0.8664) and logarithmic (% water = 0.2489 Ln Corg + 0.2842, R2 = 0.9455) functions. As this relationship tends to be asymptotic at higher Corg (>3.5% dry)/water values (>60%) and given an higher correlation, the relationship appears better modeled as a logarithmic function. Values of C org from 1.2 to over 6.5%dry wt. and water contents from 30 to over 70%wt. were observed. The calculated intercept revealed that, without organic carbon (viz. hydrogel formation), these carbonates would likely contain only ???30% water by weight ('m' from linear model). This gelation is proposed to involve exopolymeric substances (EPS), likely polysaccharides, derived from diatoms and cyanobacteria of the microphytobenthos. A cyanobacterial-diatomaceous biofilm/mat underlain by purple sulfur bacteria was shown, by pigment based chemotaxonomy, to form the main components of the microphytobenthos. Additional water column detrital biomass, also mainly cyanobacteria and diatoms, is admixed with the living microphytobenthos in a flocculent/nephloid layer above the sediments prior to final

  14. Polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardants (aBFRs) in sediments from four bays of the Yellow Sea, North China.

    Science.gov (United States)

    Zhen, Xiaomei; Tang, Jianhui; Xie, Zhiyong; Wang, Runmei; Huang, Guopei; Zheng, Qian; Zhang, Kai; Sun, Yongge; Tian, Chongguo; Pan, Xiaohui; Li, Jun; Zhang, Gan

    2016-06-01

    The distribution characteristics and potential sources of polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardants (aBFRs) were investigated in 54 surface sediment samples from four bays (Taozi Bay, Sishili Bay, Dalian Bay, and Jiaozhou Bay) of North China's Yellow Sea. Of the 54 samples studied, 51 were collected from within the four bays and 3 were from rivers emptying into Jiaozhou Bay. Decabromodiphenylethane (DBDPE) was the predominant flame retardant found, and concentration ranged from 0.16 to 39.7 ng g(-1) dw and 1.13-49.9 ng g(-1) dw in coastal and riverine sediments, respectively; these levels were followed by those of BDE 209, and its concentrations ranged from n.d. to 10.2 ng g(-1) dw and 0.05-7.82 ng g(-1) dw in coastal and riverine sediments, respectively. The levels of DBDPE exceeded those of decabromodiphenyl ether (BDE 209) in most of the samples in the study region, whereas the ratio of DBDPE/BDE 209 varied among the four bays. This is indicative of different usage patterns of brominated flame retardants (BFRs) and also different hydrodynamic conditions among these bay areas. The spatial distribution and composition profile analysis indicated that BFRs in Jiaozhou Bay and Dalian Bay were mainly from local sources, whereas transport from Laizhou Bay by coastal currents was the major source of BFRs in Taozi Bay and Sishili Bay. Both the ∑PBDEs and ∑aBFRs (sum of pentabromotoluene (PBT), 2,3-diphenylpropyl-2,4,6-tribromophenyl ether (DPTE), pentabromoethylbenzene (PBEB), and hexabromobenzene (HBB)) were at low concentrations in all the sediments. This is probably attributable to a combination of factors such as low regional usage of these products, atmospheric deposition patterns, coastal currents transportation patterns, and degradation processes for higher BDE congeners. This paper is the first study that has investigated the levels of DBDPE in the coastal sediments of China's Yellow Sea.

  15. 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).

  16. Sediment and Vegetation as Reservoirs of Vibrio vulnificus in the Tampa Bay Estuary and Gulf of Mexico

    Science.gov (United States)

    Chase, Eva; Young, Suzanne

    2015-01-01

    The opportunistic pathogen Vibrio vulnificus occurs naturally in estuarine habitats and is readily cultured from water and oysters under warm conditions but infrequently at ambient conditions of <15°C. The presence of V. vulnificus in other habitats, such as sediments and aquatic vegetation, has been explored much less frequently. This study investigated the ecology of V. vulnificus in water by culture and quantitative PCR (qPCR) and in sediment, oysters, and aquatic vegetation by culture. V. vulnificus samples were taken from five sites around Tampa Bay, FL. Levels determined by qPCR and culture were significantly correlated (P = 0.0006; r = 0.352); however, V. vulnificus was detected significantly more frequently by qPCR (85% of all samples) compared to culture (43%). Culturable V. vulnificus bacteria were recovered most frequently from oyster samples (70%), followed by vegetation and sediment (∼50%) and water (43%). Water temperature, which ranged from 18.5 to 33.4°C, was positively correlated with V. vulnificus concentrations in all matrices but sediments. Salinity, which ranged from 1 to 35 ppt, was negatively correlated with V. vulnificus levels in water and sediments but not in other matrices. Significant interaction effects between matrix and temperature support the hypothesis that temperature affects V. vulnificus concentrations differently in different matrices and that sediment habitats may serve as seasonal reservoirs for V. vulnificus. V. vulnificus levels in vegetation have not been previously measured and reveal an additional habitat for this autochthonous estuarine bacterium. PMID:25636843

  17. 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.

    behavior of marine calcareous sediments of biogenic origin. Consolidation and drained triaxial tests indicate that mixed sediments have higher compressibilities and lower strengths compared to high-carbonate sediments. Differences in gradation among high...

  18. 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.

  19. Application of neural network and MODIS 250 m imagery for estimating suspended sediments concentration in Hangzhou Bay, China

    Science.gov (United States)

    Wang, Fan; Zhou, Bin; Xu, Jianming; Song, Lishong; Wang, Xin

    2009-01-01

    Suspended sediments concentration (SSC) in surface water derived from bottom sediment resuspension or discharge of sediment-laden rivers is an important indication of coastal water quality and changes rapidly in high-energy coastal area. Since artificial neural networks (ANN) had been proven successful in modeling a variety of geophysical transfer functions, an ANN model to simulate the relationship between surface water SSC and satellite-received radiances was employed. In situ SSC measurements from the Hangzhou Bay and the Moderate-resolution Imaging Spectroradiometer (MODIS) 250 m daily products were adopted in this study. Significant correlations were observed between in situ measurements and band 1-2 reflectance values of MODIS images, respectively. Results indicated that application of ANN model with one hidden layer appeared to yield superior simulation performance ( r 2 = 0.98; n = 25) compared with regression analysis method. The RMSE for the ANN model was less than 10%, whereas the RMSE for the regression analysis was more than 25%. Results also showed that different tidal situations affect the model simulation results to some extent. The SSC of surface water in Hangzhou Bay is high and changes rapidly due to tidal flood and ebb during a tidal cycle. The combined utilization of Terra and Aqua MODIS data can capture the tidal cycle induced dynamic of surface water SSC. This study demonstrated that MODIS 250 m daily products and ANN model are useful for monitoring surface SSC dynamic within high-energy coastal water environments.

  20. 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.

  1. Vertical profiles of dioxin-like and estrogenic activities associated with a sediment core from Tokyo Bay, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Kannan, K.; Villeneuve, D.L.; Yamashita, N.; Imagawa, T.; Hashimoto, S.; Miyazaki, A.; Giesy, J.P. [Michigan State University, East Lansing, MI (USA). Dept. of Zoology

    2000-09-01

    In vitro bioassays were used to measure dioxin-like and estrogenic activities associated with florisil fractions of extracts from a sediment core collected from Tokyo Bay, Japan. Florisil fractions 2(F2) and 3(F3) elicited significant dioxin-like responses in vitro. Dioxin-like activity of F2 samples were correlated with the vertical profile of PAH concentrations (R{sup 2} = 0.85). Contribution of PAHs to Ah receptor-mediated activities in sediments was greater than those by PCDDs/DFs, PCBs, and PCNs. The dioxin-like activity of F3 samples suggests the presence of relatively polar, Ah receptor-active compounds in the Tokyo Bay sediment core. Significant estrogenic activities, which may be related to the presence of certain estrogenic PAHs, were observed for F2 samples. Estrogen equivalents (E2-EQs) calculated from the concentrations and relative potencies of known estrogenic compounds in F2 were greater than bioassay-derived E2-EQs. This suggests that complex interactions between estrogenic and antiestrogenic compounds (PAHs, PCDD/DFs, and PCNs) may have modulated the activity. F3 samples were toxic to MVLN cells; therefore, their estrogenic activities could not be estimated. 27 refs., 4 figs., 3 tabs.

  2. 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

  3. CHARACTERIZING THE ORGANIC MATTER IN SURFACE SEDIMENTS FROM THE SAN JUAN BAY ESTUARY

    Science.gov (United States)

    The San Juan Bay Estuary (SJBE) is located on the north coast of Puerto Rico and includes the San Juan Bay, San José Lagoon, La Torrecilla Lagoon and Piñones Lagoon, as well as the Martín Peña and the Suárez Canals. The SJBE watershed has the highest...

  4. CHARACTERIZING THE ORGANIC MATTER IN SURFACE SEDIMENTS FROM THE SAN JUAN BAY ESTUARY.

    Science.gov (United States)

    The San Juan Bay Estuary (SJBE) is located on the north coast of Puerto Rico and includes the San Juan Bay, San José Lagoon, La Torrecilla Lagoon and Piñones Lagoon, as well as the Martín Peña and the Suárez Canals. The SJBE watershed has the highest...

  5. Effects of Sediment Characteristics on the Accumulation and Transfer Rate of Heavy Metals in Mangrove Trees (Case Study: Nayband Bay and Qeshm Island

    Directory of Open Access Journals (Sweden)

    H. Moradi

    2014-09-01

    Full Text Available In this paper, the accumulation of heavy metals of Nickel (Ni and Vanadium (V was measured in habitat sediments, mangrove roots and leaves (Avicennia marina. Besides, the transfer of Ni and V from the sediment to root and to the leaves in Nayband Bay and Qeshm Island were studied. The samples were gathered by Systematic-random Sampling using selective transects at 16 stations at the end of mangrove cover in both sides of land and sea in two habitats with three replicates of sediment, root and leave samples. The bed characteristics including sediment texture, pH, EC and organic matters were determined. The concentration of Ni and V was measured by atomic absorption spectroscopy (AAS, and then the metal transfer factor from sediment to root and root to leave was calculated. The correlation of the metal transfer factor and sediment characteristics was analyzed using the SPSS software (version 19. In the sample of sediments, roots and leaves respectively, the most concentrations of nickel and vanadium were measured. About transfer of Ni and V, transfer rate from sediment to root was much higher than from root to leave. In addition, the highest transfer factor from sediment to root and from root to leave was obtained for V in Qeshm habitat (0.502 and for Ni (0.749 in Nayband Bay. It seems that the difference between sediment textures in the two habitats and widespread oil and gas activities in Nayband Bay might be the notable reasons for the difference in transfer rates in two the habitats. Therefore, we conclude that the finer texture of Qeshm habitat increased transfer of V from sediment to root, and the coarser texture associated with increasing air pollution in Nayband Bay caused more Ni to accumulate in the leaves.

  6. 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.

  7. 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.

  8. 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

  9. Sediment chronology in San Francisco Bay, California, defined by 210Pb, 234Th, 137Cs, and 239,340Pu

    Science.gov (United States)

    Fuller, C.C.; van Geen, Alexander; Baskaran, M.; Anima, R.

    1999-01-01

    Sediment chronologies based on radioisotope depth profiles were developed at two sites in the San Francisco Bay estuary to provide a framework for interpreting historical trends in organic compound and metal contaminant inputs. At Richardson Bay near the estuary mouth, sediments are highly mixed by biological and/or physical processes. Excess  penetration ranged from 2 to more than 10 cm at eight coring sites, yielding surface sediment mixing coefficients ranging from 12 to 170 cm2/year. At the site chosen for contaminant analyses, excess  activity was essentially constant over the upper 25 cm of the core with an exponential decrease below to the supported activity between 70 and 90 cm. Both  and  penetrated to 57-cm depth and have broad subsurface maxima between 33 and 41 cm. The best fit of the excess  profile to a steady state sediment accumulation and mixing model yielded an accumulation rate of 0.825 g/cm2/year (0.89 cm/year at sediment surface), surface mixing coefficient of 71 cm2/year, and 33-cm mixed zone with a half-Gaussian depth dependence parameter of 9 cm. Simulations of  and  profiles using these parameters successfully predicted the maximum depth of penetration and the depth of maximum  and  activity. Profiles of successive 1-year hypothetical contaminant pulses were generated using this parameter set to determine the age distribution of sediments at any depth horizon. Because of mixing, sediment particles with a wide range of deposition dates occur at each depth. A sediment chronology was derived from this age distribution to assign the minimum age of deposition and a date of maximum deposition to a depth horizon. The minimum age of sediments in a given horizon is used to estimate the date of first appearance of a contaminant from its maximum depth of penetration. The date of maximum deposition is used to estimate the peak year of input for a contaminant from the depth interval with the highest concentration of that contaminant

  10. Influence of climate on deep-water clastic sedimentation: application of a modern model, Peru-Chile Trough, to an ancient system, Ouachita Trough

    Science.gov (United States)

    Edgar, N. Terence; Cecil, C. Blaine

    2003-01-01

    Traditionally, an abrupt and massive influx of siliciclastic sediments into an area of deposition has been attributed to tectonic uplift without consideration of the influence of climate or climatic change on rates of weathering, erosion, transportation, and deposition. With few exceptions, fluvial sediment transport is minimal in both extremely arid climates and in perhumid (everwet) climates. Maximum sediment transport occurs in climates characterized by strongly seasonal rainfall, where the effect of vegetation on erosion is minimal. The Peru–Chile trench and Andes Mountain system (P–CT/AMS) of the eastern Pacific Ocean clearly illustrates the effects of climate on rates of weathering, erosion, transport, and deep-sea sedimentation. Terrigenous sediment is virtually absent in the arid belt north of lat. 30° S in the P–CT, but in the belt of seasonal rainfall south of lat. 30° S terrigenous sediment is abundant. Spatial variations in the amount and seasonality of annual precipitation are now generally accepted as the cause for this difference. The spatial variation in sediment supply to the P–CT appears to be an excellent modern analogue for the temporal variation in sediment supply to certain ancient systems, such as the Ouachita Trough in the southern United States. By comparison, during the Ordovician through the early Mississippian, sediment was deposited at very slow rates as the Ouachita Trough moved northward through the southern hemisphere dry belt (lat. 10° S to lat. 30° S). The deposystem approached the tropical humid zone during the Mississippian, coincident with increased coarse clastic sedimentation. By the Middle Pennsylvanian (Atokan), the provenance area and the deposystem moved well into the tropical humid zone, and as much as 8,500 m of mineralogically mature (but texturally immature) quartz sand was introduced and deposited. This increase in clastic sediment deposition traditionally has been attributed solely to tectonic activity

  11. Preserving Chile

    OpenAIRE

    Brennand, Charlotte P.

    2010-01-01

    The best way to preserve chile depends on how you plan to use it and your available storage space. Frozen or canned chile is best for chile rellenos and salsas. Stews can use frozen, canned or dried chile. Dried chile has minimal storage requirements and is light-weight for taking on camping trips. Pickled chiles can be used on a relish plate or as an ingredient in other dishes.

  12. 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.

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

    Institute of Scientific and Technical Information of China (English)

    Surajit DAS; P.S.LYLA; S.AJMAL KHAN

    2008-01-01

    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.200m,500m,and 1000m 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 1000m depth.Two-way analysis of variance showed significant variation among stations (ANOVA two-way,P0.05),but no significance was found between the two cruises (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.

  14. Geochemistry of organic carbon and nitrogen in surface sediments of coastal Bohai Bay inferred from their ratios and stable isotopic signatures.

    Science.gov (United States)

    Gao, Xuelu; Yang, Yuwei; Wang, Chuanyuan

    2012-06-01

    Total organic carbon (TOC), total nitrogen (TN) and their δ(13)C and δ(15)N values were determined for 42 surface sediments from coastal Bohai Bay in order to determine the concentration and identify the source of organic matter. The sampling sites covered both the marine region of coastal Bohai Bay and the major rivers it connects with. More abundant TOC and TN in sediments from rivers than from the marine region reflect the situation that most of the terrestrial organic matter is deposited before it meets the sea. The spatial variation in δ(13)C and δ(15)N signatures implies that the input of organic matter from anthropogenic activities has a more significant influence on its distribution than that from natural processes. Taking the area as a whole, surface sediments in the marine region of coastal Bohai Bay are dominated by marine derived organic carbon, which on average accounts for 62±11% of TOC.

  15. 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

  16. From Sediment to Top Predators: Broad Exposure of Polyhalogenated Carbazoles in San Francisco Bay (U.S.A.).

    Science.gov (United States)

    Wu, Yan; Tan, Hongli; Sutton, Rebecca; Chen, Da

    2017-02-21

    The present study provides the first comprehensive investigation of polyhalogenated carbazoles (PHCZs) contamination in an aquatic ecosystem. PHCZs have been found in soil and aquatic sediment from several different regions, but knowledge of their bioaccumulation and trophodynamics is extremely scarce. This work investigated a suite of 11 PHCZ congeners in San Francisco Bay (United States) sediment and organisms, including bivalves (n = 6 composites), sport fish (n = 12 composites), harbor seal blubber (n = 18), and bird eggs (n = 8 composites). The most detectable congeners included 3,6-dichlorocarbazole (36-CCZ), 3,6-dibromocarbazole (36-BCZ), 1,3,6-tribromocarbazole (136-BCZ), 1,3,6,8-tetrabromocarbazole (1368-BCZ), and 1,8-dibromo-3,6-dichlorocarbazole (18-B-36-CCZ). The median concentrations of ΣPHCZs were 9.3 ng/g dry weight in sediment and ranged from 33.7 to 164 ng/g lipid weight in various species. Biomagnification was observed from fish to harbor seal and was mainly driven by chlorinated carbazoles, particularly 36-CCZ. Congener compositions of PHCZs differed among species, suggesting that individual congeners may be subject to different bioaccumulation or metabolism in species occupying various trophic levels in the studied aquatic system. Toxic equivalent (TEQ) values of PHCZs were determined on the basis of their relative effect potencies (REP) compared to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The median TEQ was 1.2 pg TEQ/g dry weight in sediment and 4.8-19.5 pg TEQ/g lipid weight in biological tissues. Our study demonstrated the broad exposure of PHCZs in San Francisco Bay and their characteristics of bioaccumulation and biomagnification along with dioxin-like effects. These findings raise the need for additional research to better elucidate their sources, environmental behavior, and fate in global environments.

  17. Sediment and Crustal Structure along 85oE and Ninetyeast Ridges in the Bay of Bengal: Geodynamic Implications

    Science.gov (United States)

    Munukutla, R.; Gangumalla, S. R.; Sreejith, K. M.; Krishna, K. S.; Bull, J. M.

    2015-12-01

    The Bay of Bengal (BOB) region is characterized by the presence of two linear N-S trending aseismic ridges, the 85°E and Ninetyeast ridges which have progressively buried below thick sediments towards north. We present here the results of an integrated interpretation of geophysical data using multichannel seismic reflection, gravity and magnetic datasets over these two ridges to study the crustal structure and mode of their emplacement. The ridges divide the deep sedimentary BOB region into three major sub-basins. Considering the sediment deposition pattern within the sub-basins and over the ridges, it is found that both ridge structures have played a role in sediment dispersal pattern during the pre- and post Bengal Fan sedimentation. The Geoid-Topography Ratio (GTR) analysis indicates that both the ridges are compensated at shallow depths. Seismically constrained gravity and magnetic models and flexural gravity modeling over these ridges support their volcanic origin, and suggest the following: i) 85°E Ridge was emplaced in off-ridge environment (Te=10-15 km); ii) the higher Te values of ~ 25 km over the Afanasy Nikitin Seamount (ANS) reflect the secondary emplacement of the seamount peaks in off-ridge environment, iii) that the emplacement of the Ninetyeast Ridge north of 2°N occurred in an off-ridge environment as indicated by higher Te values (25-30 km). These results attain significance in terms of understanding of the interactions between plume- volcanism and lithosphere in the Bay of Bengal.

  18. Contenido de metales en Cancer polyodon (Crustacea: Decapoda en un sistema de bahías del norte de Chile (27°S Metal contents in Cancer polyodon (Crustacea: Decapoda in a bay system of northern Chile (27°S

    Directory of Open Access Journals (Sweden)

    Alexis Castillo

    2011-11-01

    Full Text Available El contenido de Zn, Cu, Cd, Pb, Fe, Al y Ni fue analizado en tejido muscular de Cancer polyodon en las bahías de Caldera, Calderilla, Inglesa y Salada (Atacama, Chile. Los resultados fueron comparados con estudios similares desarrollados por otros autores y la normativa de carácter nacional e internacional relacionada con el contenido de metales pesados en crustáceos para consumo humano. El orden de abundancia de los metales analizados en C. polyodon fue CdThe contents of Zn, Cu, Cd, Pb, Fe, Al and Ni in the muscle tissue of Cancer polyodon from Caldera, Calderilla, Inglesa, and Salada bays (Atacama, Chile were quantified. The results were compared with similar studies by other authors and with the national and international regulatory standards for heavy metal contents in crustaceans for human consumption. In increasing order, the metal contents in C. polyodon were: Cd< Ni< Cu< Pb< ZnBay: Cu and Ni were highest in Caldera Bay; and Zn was highest in Inglesa Bay. All the metals except Cu differed significantly (P < 0.05 among the analyzed bays. Of the seven metals analyzed, Pb, Fe, and Al concentrations in C. polyodon were higher than those reported for other coastal systems. Concentrations of Cu (except Calderilla, Cd (except Caldera and Inglesa, and Pb exceeded the threshold values indicated by the national and international standards, suggesting that the presence of these metals in C. polyodon represents a potential risk for human health.

  19. Monitoring of dredged-dumped sediment dispersal off the Bay of the Seine (northern France) using environmental magnetism

    Science.gov (United States)

    Nizou, Jean; Demory, François; Dubrulle-Brunaud, Carole

    2016-07-01

    In this study, we developed a novel approach for fingerprinting dredged-dumped sediments at sea using magnetic susceptibility. Several magnetic measurements were performed on discrete sedimentary samples from the dredged areas in the Seine River and from the Bay of Seine seafloor before and after dumping. The dredged sediments showed higher susceptibility values than the undisturbed seafloor, which allowed the mapping of the dispersion of dredged-dumped sediments. In the vicinity of the coast and the estuary, high-susceptibility terrestrial input from rivers could also be mapped by this technique, therefore monitoring of the dumping by the susceptibility proxy is limited to the offshore areas. This susceptibility signal is controlled by the ferromagnetic fraction of the sediment. Furthermore, a constant magnetite-dominated magneto-mineralogy is observed in the study area. In addition to the susceptibility, a magnetic grain size parameter of the low-coercive fraction was also found to be sensitive to dumping. Both tracers showed an in progress resilience of the sedimentary environment during a 6-month survey.

  20. Contrasting sedimentation patterns in two semi-enclosed mesotidal bays along the west and south coasts of Korea controlled by their orientation to the regional monsoon climate

    Science.gov (United States)

    Hong, Seok Hwi; Chun, Seung Soo; Chang, Tae Soo; Jang, Dae Geon

    2016-11-01

    Sedimentation patterns of tidal flats along the Korean west coast have long been known to be largely controlled by the monsoon climate. On the other hand, much less is known about the effect of the monsoon on sedimentation in coastal embayments with mouths of different geographic orientations. Good examples are Hampyeong and Yeoja bays along the west and south coasts, respectively. Both have narrow entrances, but their mouths open toward the northwest and the south, respectively. With mean tidal ranges of 3.46 and 3.2 m, respectively, the two bays experience similar tidal regimes and are hence excellent candidates to compare the effect of different exposure to the same regional monsoon climate on their respective sediment distribution patterns. The winter monsoon, in particular, is characterized by strong northwesterly winds that directly impact the west coast, but blow offshore along the south coast. For the purpose of this study, surficial sediment samples were collected from intertidal and subtidal flats of the two bays, both in summer and winter. Grain-size analyses were carried out by sieving (sand fraction) and Sedigraph (mud fraction). In the case of Yeoja Bay, the sediments consist mostly of mud (mean grain sizes of 5.4 to 8.8 phi). Seasonal changes are very subtle, the sediments being slightly coarser in summer when silt-dominated sediments are supplied by two streams to the northern parts of the bay in response to heavy rainfall. With the exception of the deeper tidal channels, Yeoja Bay is characterized by a thick mud blanket the year round, which is modulated by processes associated with the summer monsoon that predominantly blows from the east. Textural parameters suggest severely restricted sediment mixing on the subtidal and intertidal flats, the overall low energy situation preventing sands from reaching the tidal flats. The sediments of Hampyeong Bay, by contrast, are characterized by a distinct shoreward fining trend. Mean grain sizes average

  1. Trajectory of early tidal marsh restoration: elevation, sedimentation and colonization of breached salt ponds in the northern San Francisco Bay

    Science.gov (United States)

    Brand, L. Arriana; Smith, Lacy M.; Takekawa, John Y.; Athearn, Nicole D.; Taylor, Karen; Shellenbarger, Gregory; Schoellhamer, David H.; Spenst, Renee

    2012-01-01

    Tidal marsh restoration projects that cover large areas are critical for maintaining target species, yet few large sites have been studied and their restoration trajectories remain uncertain. A tidal marsh restoration project in the northern San Francisco Bay consisting of three breached salt ponds (≥300 ha each; 1175 ha total) is one of the largest on the west coast of North America. These diked sites were subsided and required extensive sedimentation for vegetation colonization, yet it was unclear whether they would accrete sediment and vegetate within a reasonable timeframe. We conducted bathymetric surveys to map substrate elevations using digital elevation models and surveyed colonizing Pacific cordgrass (Spartina foliosa). The average elevation of Pond 3 was 0.96 ± 0.19 m (mean ± SD; meters NAVD88) in 2005. In 2008–2009, average pond elevations were 1.05 ± 0.25 m in Pond 3, 0.81 ± 0.26 m in Pond 4, and 0.84 ± 0.24 m in Pond 5 (means ± SD; meters NAVD88). The largest site (Pond 3; 508 ha) accreted 9.5 ± 0.2 cm (mean ± SD) over 4 years, but accretion varied spatially and ranged from sediment loss in borrow ditches and adjacent to an unplanned, early breach to sediment gains up to 33 cm in more sheltered regions. The mean elevation of colonizing S. foliosa varied by pond (F = 71.20, df = 84, P S. foliosa. Our results suggest that sedimentation to elevations that enable vegetation colonization is feasible in large sites with sufficient sediment loads although may occur more slowly compared with smaller sites.

  2. 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...

  3. 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

  4. Continuous water-quality and suspended-sediment transport monitoring in the San Francisco Bay, California, water years 2011-13

    Science.gov (United States)

    Buchanan, Paul A.; Downing-Kunz, Maureen A.; Schoellhamer, David H.; Shellenbarger, Gregory; Weidich, Kurt W.

    2014-01-01

    The U.S. Geological Survey (USGS) monitors water quality and suspended-sediment transport in the San Francisco Bay. The San Francisco Bay area is home to millions of people, and the bay teems with both resident and migratory wildlife, plants, and fish. Fresh water mixes with salt water in the bay, which is subject both to riverine and marine (tides, waves, influx of salt water) influences. To understand this environment, the USGS, along with its partners, has been monitoring the bay’s waters continuously since 1988. Several water-quality variables are of particular importance to State and Federal resource managers and are monitored at key locations throughout the bay. Salinity, which indicates the relative mixing of fresh and ocean waters in the bay, is derived from specific conductance measurements. Water temperature, along with salinity, affects the density of water, which causes gravity driven circulation patterns and stratification in the water column. Turbidity is measured using light-scattering from suspended solids in water, and is used as a surrogate for suspended-sediment concentration (SSC). Suspended sediment often carries adsorbed contaminants; attenuates sunlight in the water column; deposits on tidal marsh and intertidal mudflats, which can help sustain these habitats as sea level rises; and deposits in ports and shipping channels, which can necessitate dredging. Dissolved oxygen, which is essential to a healthy ecosystem, is a fundamental indicator of water quality, and its concentration is affected by water temperature, salinity, ecosystem metabolism, tidal currents, and wind. Tidal currents in the bay reverse four times a day, and wind direction and intensity typically change on a daily cycle: consequently, salinity, water temperature, suspendedsediment concentration, and dissolvedoxygen concentration vary spatially and temporally throughout the bay, and continuous measurements are needed to observe these changes. The purpose of this fact sheet

  5. Geochemistry of trace metals in shelf sediments affected by seasonal and permanent low oxygen conditions off central Chile, SE Pacific (˜36°S)

    Science.gov (United States)

    Muñoz, Praxedes; Dezileau, Laurent; Cardenas, Lissette; Sellanes, Javier; Lange, Carina B.; Inostroza, Jorge; Muratli, Jesse; Salamanca, Marco A.

    2012-02-01

    Trace metals (Cd, U, Co, Ni, Cu, Ba, Fe, Mn), total organic carbon (TOC) and C and N stable isotope signatures (δ 13C and δ 15N) were determined in short sediments cores from the inner and outer shelf off Concepción, Chile (˜36°S). The objectives were to establish the effect of environmental conditions on trace metal distributions at two shelf sites, one affected by seasonal oxygenation and the other by permanent low oxygen conditions due to the presence of the oxygen minimum zone (OMZ). We evaluate trace metals as proxies of past changes in primary productivity and the bottom water oxygen regime. Concentrations of pore water sulfides and NH4+ were also measured as indicators of the main diagenetic pathways at each site. Our results for the inner shelf (seasonal suboxia) suggest that the oxidative state of the sediments responds to seasonal pulses of organic matter and that seasonal oxygenation develops during high and low primary productivity in the water column. Here, positive fluxes (to the water column) estimated from pore water concentrations of several elements were observed (Ba, Co, Ni, Fe and Mn). The less reduced environment at this site produces authigenic enrichment of Cu associated with the formation of oxides in the oxic surface sediment layer, and the reduction of U within deeper sediment sections occur consistently with negative estimated pore water fluxes. In the outer shelf sediments (permanent suboxia, OMZ site), negative fluxes (to the sediment) were estimated for all elements, but these sediments showed authigenic enrichments only for Cd, Cu and U. The short oxygenation period during the winter season did not affect the accumulation of these metals on the shelf. The distribution of Cu, Cd and U have been preserved within the sediments and the authigenic accumulation rates estimated showed a decrease from the deep sections of the core to the surface sediments. This could be explained by a gradual decrease in the strength of the OMZ in the

  6. Runoff nutrient and suspended sediment fluxes, cycling, and management in southern Kaneohe Bay, Hawaii

    Science.gov (United States)

    Ringuet, S.; Young, C. W.; Hoover, D. J.; de Carlo, E. H.; MacKenzie, F. T.

    2003-12-01

    Urban runoff and its impact on water quality in Hawaii, especially after heavy rainfall, is highly dynamic. In the past, water quality was determined through "grab samples" that were merely snapshots in time of an ever-changing environment. In contrast, continuous measurements of water quality can capture data that reflect the effects of significant storm runoff events unobtainable using even frequent manual sampling. Continuous multiparameter monitoring facilitates investigation of the both the magnitude and persistence of impacts of storm runoff on coastal waters, which can eventually be related to the health of coral reef ecosystems. Taking advantage of recent technological developments in oceanographic instrumentation, our study assembled an instrument package dubbed Coral Reef Instrumented Monitoring Platform (CRIMP). CRIMP was designed to include probes that measure physical and biological parameters (temperature, salinity, pH, dissolved oxygen, turbidity, and chlorophyll-a), nutrient analyzers (nitrate and phosphate), and a particle analyzer based on laser in-situ scattering and transmissometry. Various components of the CRIMP were previously used in conjunction with grab samples with the objective of elucidating the water quality of southern Kaneohe Bay and its relationship to physical, biological, and chemical processes operating in the bay, and to coral reef ecosystems. All instruments are now being combined on the CRIMP, and will allow us to study in near real time changes in fluvial inputs to the bay during storm runoff conditions and their impact on bay water quality and the coral reef ecosystem. In this presentation we discuss effects of freshwater delivery on adjacent coastal waters during high rainfall episodes (May 2002 and Feb 2003) that result in large runoff events and increased nutrient loading to coastal waters. Dissolved inorganic nitrogen to phosphorus ratios (DIN:DIP) in the Bay normally range from 2 to 4, suggesting a nitrogen

  7. Radiolarian fluxes from the southern Bay of Bengal: sediment trap results

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, S.M.; Mohan, R.; Guptha, M.V.S.

    ; Radiolarians; Foraminifers; Monsoon flux; Bay of Bengal UNCORRECTED PROOF 37 graphic provinces (Gupta, 1991).Radio larians 49 39 have been used to reconstruct the paleomonsoon during the late Miocene at ODP Leg 116 sites 51 41 (Nigrini, 1991... Equatorial Current and microscope at 100 C2 for species identification and 89 an eastward flowing Monsoon Current in the at 40 C2 magnification for counting.Radio larian 43 northern Bay of Bengal.Along the eastern coast of species were identified and counted.Radio...

  8. Endospore abundance and D:L-amino acid modeling of bacterial turnover in holocene marine sediment (Aarhus Bay)

    Science.gov (United States)

    Langerhuus, Alice T.; Røy, Hans; Lever, Mark A.; Morono, Yuki; Inagaki, Fumio; Jørgensen, Bo B.; Lomstein, Bente Aa.

    2012-12-01

    In order to study bacterial activity, and turnover times of bacterial necromass and biomass in marine sediment, two stations from the Aarhus Bay, Denmark were analyzed. Sediment cores were up to 11 m deep and covered a timescale from the present to ˜11,000 years ago. Sediment was analyzed for total hydrolysable amino acids (THAA), total hydrolysable amino sugars, the bacterial endospore marker dipicolinic acid (DPA), and amino acid enantiomers (L- and D-form) of aspartic acid. Turnover times of bacterial necromass and vegetative cells, as well as carbon oxidation rates were estimated by use of the D:L-amino acid racemization model. Diagenetic indicators were applied to evaluate the diagenetic state of the sedimentary organic matter. The contribution of amino acids to total organic carbon, and the ratio between the amino acids aspartic acid and glutamic acid, and their respective non protein degradation products, β-alanine and γ-amino butyric acid, all indicated increasing degradation state of the organic matter with sediment depth and age. Quantification of DPA showed that endospores were abundant, and increased with depth relative to vegetative cells. Most of the amino acids (97%) could be ascribed to microbial necromass, i.e. the remains of dead bacterial cells. Model estimates showed that the turnover times of microbial necromass were in the range of 0.5-1 × 105 years, while turnover times of vegetative cells were in the range of tens to hundreds of years. The turnover time of the TOC pool increased with depth in the sediment, indicating that the TOC pool became progressively more refractory and unavailable to microorganisms with depth and age of the organic matter.

  9. 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

    was confined to hot spots. The in situ benthic O2 uptakes, measured during four cruises, reflected a seasonal signal overlying the observed small-scale variability. The annual benthic mineralization balanced ,50% of the estimated pelagic production. However, the central bay is characterized by a significant......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...... downslope sediment transport, and mass balance estimates indicate 90% retention of the total organic material reaching the bottom of the central bay....

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

    Science.gov (United States)

    Zhou, Peng; Li, Dongmei; Li, Haitao; Fang, Hongda; Huang, Chuguang; Zhang, Yusheng; Zhang, Hongbiao; Zhao, Li; Zhou, Junjie; Wang, Hua; Yang, Jie

    2015-07-01

    A sediment core was collected and dated using (210)Pbex dating method off the waterspout of nuclear power base of Daya Bay, northeastern South China Sea. The γ-emitting radionuclides were analyzed using HPGe γ spectrometry, gross alpha and beta radioactivity as well as other geochemical indicators were deliberated to assess the impact of nuclear power plants (NPP) operation and to study the past environment changes. It suggested that NPP provided no new radioactivity source to sediment based on the low specific activity of (137)Cs. Two broad peaks of TOC, TC and LOI accorded well with the commercial operations of Daya Bay NPP (1994.2 and 1994.5) and LNPP Phase I (2002.5 and 2003.3), implying that the mass input of cooling water from NPP may result into a substantial change in the ecological environment and Daya Bay has been severely impacted by human activities.

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

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Caselles, C. [Instituto de Ciencias Marinas de Andalucia (ICMAN-CSIC), Avda. Republica Saharaui s/n, Puerto Real 11510, Cadiz (Spain); Unidad Asociada de Calidad Ambiental y Patologia (CSIC and UCA), Avda. Republica Saharaui s/n, Puerto Real 11510, Cadiz (Spain); Kalman, J. [Instituto de Ciencias Marinas de Andalucia (ICMAN-CSIC), Avda. Republica Saharaui s/n, Puerto Real 11510, Cadiz (Spain); Unidad Asociada de Calidad Ambiental y Patologia (CSIC and UCA), Avda. Republica Saharaui s/n, Puerto Real 11510, Cadiz (Spain); Riba, I. [Instituto de Ciencias Marinas de Andalucia (ICMAN-CSIC), Avda. Republica Saharaui s/n, Puerto Real 11510, Cadiz (Spain); Unidad Asociada de Calidad Ambiental y Patologia (CSIC and UCA), Avda. Republica Saharaui s/n, Puerto Real 11510, Cadiz (Spain); DelValls, T.A. [UNESCO UNITWIN/UNICOP, Facultad de Ciencias del Mar y Ambientales, Universidad de Cadiz, Poligono Rio San Pedro s/n, Puerto Real 11510, Cadiz (Spain) and Unidad Asociada de Calidad Ambiental y Patologia - CSIC and UCA, Avda. Republica Saharaui s/n, Puerto Real 11510, Cadiz (Spain)]. E-mail: angel.valls@uca.es

    2007-03-15

    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.

  12. Distribution and source identification of trace metals in the sediment of Yellow River Estuary and the adjacent Laizhou Bay

    Science.gov (United States)

    Wang, Yan; Ling, Min; Liu, Ru-hai; Yu, Ping; Tang, Ai-kun; Luo, Xian-xiang; Ma, Qimin

    2017-02-01

    Rapid economic development in the Yellow River basin has inevitably resulted in increase of pollution in the estuary, and concern for both the environment and protection against pollutants is increasing. Contents of trace metals (Cu, Pb Zn, Cr, Cd, As, Hg), Fe, Al, total organic carbon (TOC), and their granulometry were determined in surface sediment samples from the Yellow River estuary and its adjacent areas. Metal contents were significantly correlated each other. Clay, TOC and heavy metal contents showed similar distribution characteristics, with concentrations increased from the land to the sea. The distribution of grain size plays an important role in influencing the distribution of trace metals. Heavy metal concentrations showed a significant relationship with Fe and Al content, while most heavy metals were not enriched. These results were also confirmed by the analysis of enrichment factors and principal component analysis of the metals. The metal content of the Yellow River Estuary sediments was similar to the content observed 20 years ago, but the concentrations of most metals in Laizhou Bay decreased. The decrease in the carrying sediment of the Yellow River might be responsible for this pattern.

  13. Heavy metal pollution status in surface sediments of Swan Lake lagoon and Rongcheng Bay in the northern Yellow Sea.

    Science.gov (United States)

    Huang, Lili; Pu, Xinming; Pan, Jin-Fen; Wang, Bo

    2013-11-01

    The national 'Shandong Peninsula Blue Economic Zone Development Plan' compels the further understanding of the distribution and potential risk of metals pollution in the east coast of China, where the rapid economic and urban development have been taken off and metal pollution has become a noticeable problem. Surface sediments collected from the largest swan habitat in Asia, the Swan Lake lagoon and the surrounding coastal area in Rongcheng Bay in northern Yellow Sea, were analyzed for the total metal concentrations and chemical phase partitioning of five heavy metals (Cu, Zn, Pb, Cd, and Cr). Metal contents in the studied region have increased significantly in the past decade. The speciation analyzed by the sequential extraction showed that Zn and Cr were present dominantly in the residual fraction and thus of low bioavailability, while Cd, Pb and Cu were found mostly in the non-residual fraction thus of high potential availability, indicating significant anthropogenic sources. Among the five metals, Cd is the most outstanding pollutant and presents high risk, and half of the surface sediments in the studied region had a 21% probability of toxicity based on the mean Effect Range-Median Quotient. At some stations with comparable total metal contents, remarkably different non-residual fraction portions were determined, pointing out that site-specific risk assessment integrating speciation is crucial for better management practices of coastal sediments.

  14. Early diagenesis and authigenic mineral formation in anoxic sediments of Kau Bay, Indonesia

    NARCIS (Netherlands)

    Middelburg, Jack

    1990-01-01

    Kau Bay (island of Halmahera, Eastern Indonesia) is a 470 m deep basin separated from the Pacific Ocean by a sill that is at present only 40 m below sea-level. The presence of this sill has two major implications. Firstly, during Weichselian time, the sea-level dropped below the depth of the sill, K

  15. Modeling Benthic Sediment Processes to Predict Water Quality and Ecology in Narragansett Bay

    Science.gov (United States)

    The benthic sediment acts as a huge reservoir of particulate and dissolved material (within interstitial water) which can contribute to loading of contaminants and nutrients to the water column. A benthic sediment model is presented in this report to predict spatial and temporal ...

  16. 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.

    -ray 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.... The maximum value of crystallinity indicates the minerals are in ordered form and the minimum value is taken as disordered form. Therefore, it is important to find the crystallinity of quartz rather than the other associated minerals. Crystallinity index...

  17. Assessment of Bioflocculant Production by Bacillus sp. Gilbert, a Marine Bacterium Isolated from the Bottom Sediment of Algoa Bay

    Directory of Open Access Journals (Sweden)

    Okoh I. Anthony

    2011-07-01

    Full Text Available The bioflocculant-producing potentials of a marine bacteria isolated from the bottom sediment of Algoa Bay was investigated using standard methods. The 16S rDNA sequence analysis revealed 98% similarity to that of Bacillus sp. HXG-C1 and the nucleotide sequence was deposited in GenBank as Bacillus sp. Gilbert with accession number HQ537128. Bioflocculant was optimally produced when sucrose (72% flocculating activity and ammonium chloride (91% flocculating activity were used as sole sources of carbon and nitrogen, respectively; an initial pH 6.2 of the production medium; and Mg2+ as cation. Chemical analysis of the purified bioflocculant revealed the compound to be a polysaccharide.

  18. 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

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

    Science.gov (United States)

    Sombrito, E Z; Bulos, A dM; Sta Maria, E J; Honrado, M C V; Azanza, Rhodora V; Furio, Elsa F

    2004-01-01

    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 seed bed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sombrito, E.Z. E-mail: ezsombrito@pnri.dost.gov.ph; Bulos, A.M.; Sta Maria, E.J.; Honrado, M.C.V.; Azanza, Rhodora V.; Furio, Elsa F

    2004-07-01

    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. {sup 210}Pb-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.

  1. Thirty years of coral reef change in relation to coastal construction and increased sedimentation at Pelekane Bay, Hawai'i.

    Science.gov (United States)

    Stender, Yuko; Jokiel, Paul L; Rodgers, Kuʻulei S

    2014-01-01

    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, Hawai'i 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.

  2. 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.

  3. 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...

  4. Curstal evolution and sedimentation history of the Bay of Bengal since the cretaceous

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, D.G.; Krishna, K.S.; Sar, D.

    blocks buried under thick sediments, and associated gravity and magnetic anomalies mark the bounday between continental and oceanic rocks at the foot of continental slope, about 80 km seaward of the present continental shelf edge. Eight seismic sequences...

  5. 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 Chincoteague...

  6. Characterization of selected bed-sediment-bound organic and inorganic contaminants and toxicity, Barnegat Bay and major tributaries, New Jersey, 2012

    Science.gov (United States)

    Romanok, Kristin M.; Reilly, Timothy J.; Lopez, Anthony R.; Trainor, John J.; Hladik, Michelle L.; Stanley, Jacob K.; Farrar, Daniel

    2014-01-01

    A study of bed-sediment toxicity and organic and inorganic contaminants was conducted by the U.S. Geological Survey (USGS) in cooperation with the New Jersey Department of Environmental Protection (NJDEP). Bed-sediment samples were collected once from 22 sites in Barnegat Bay and selected major tributaries during August–September 2012 and analyzed for toxicity and a suite of organic and inorganic contaminants by the USGS and the U.S. Army Corps of Engineers. Sampling sites were selected to coincide with an existing water-quality monitoring network used by the NJDEP and others in order to evaluate water-quality conditions in Barnegat Bay and the surrounding watershed. Two of the 22 sites are reference sites and are within or adjacent to the study area; bed-sediment samples from reference sites allow for comparisons of results for the Barnegat Bay watershed to results from less affected settings within the region. Toxicity testing was conducted by exposing the estuarine amphipod Leptocheirus plumulosus and the freshwater amphipod Hyalella azteca to sediments for 28 days, and the percent survival, difference in biomass, and individual dry weights were measured. Reproductive effects also were evaluated for estuarine samples. Bed-sediment samples from four sites within Barnegat Bay were subjected to a toxicity identification evaluation to determine probable causes of toxicity. Samples were analyzed for a suite of 94 currently-used pesticides, 21 legacy pesticides, 24 trace elements, 40 polycyclic aromatic hydrocarbons, 7 polychlorinated biphenyls (PCBs) as Arochlor mixtures, and 145 individual PCB congeners. Concentrations of detected compounds were compared to sediment-quality guidelines, where appropriate.

  7. Instrument packages to study long-term sediment transport processes in a shallow bay

    Science.gov (United States)

    Strahle, William J.; Martini, Marinna A.; Davis, Ray E.

    1994-01-01

    Pressure and near-surface and near-bottom measurements of current, temperature, salinity and light transmission were required in Mobile Bay, a 3 m deep estuary on the Gulf of Mexico. This environment presented several obstacles to obtaining long term observations. Boat traffic, soft estuary bottom, heavy biofouling, rapid sample rates and large data storage were overcome by using instrumentation techniques that are applicable to other estuary systems. Nearly two years of continuous data was collected.

  8. 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)

  9. 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

  10. Quantifying the erosion processes and land-uses which dominate fine sediment supply to Moreton Bay, Southeast Queensland, Australia.

    Science.gov (United States)

    Wallbrink, Peter J

    2004-01-01

    In this paper, the contributions from the three major erosion sources in the catchments of Moreton Bay are quantified, specifically for the erosion sources are classified as (i) sheet erosion from cultivated land, (ii) sheet erosion from uncultivated land, and (iii) subsoil erosion from gullies and channels. The catchments were the Brisbane and Logan rivers as well as the coastal catchments. A GIS based analysis of erosion risk was used to define areas of high erosion potential in each of the erosion source types. Radionuclide concentrations of 137Cs and 226Ra were measured on the soils from these areas and then compared to concentrations on the same size fraction on deposited sediments within the rivers. A mixing model was then used to calculate the contributions from the different sources to the sediments. The contributions in the Brisbane and Logan catchments were found to be subsoil erosion (approximately 66 +/- 10%); sheet erosion from cultivated lands 33 +/- 10% and sheet erosion of uncultivated land 1 +/- 10%. Surface and subsoil erosion contributions from the coastal catchments were found to be variable.

  11. Assessing heavy metal pollution in the recent bottom sediments of Mabahiss Bay, North Hurghada, Red Sea, Egypt.

    Science.gov (United States)

    Attia, Osama E A; Ghrefat, Habes

    2013-12-01

    Thirty-nine samples of recent bottom sediments were collected from Mabahiss Bay, north of Hurghada City, Red Sea, Egypt. The collected samples were subjected to a total digestion technique and analyzed by absorption spectrometer for metals including Pb, Zn, Cd, Ni, Co, Cu, and Mn. Concentration data were processed using correlation analysis, principal component analysis, and hierarchical cluster analysis. Multivariate statistical analysis classified heavy metals in the study area into different groups. The pollution level attributed to these metals was evaluated using geoaccumulation index and contamination factor in order to determine anthropogenically derived sediment contamination. The results of both geoaccumulation index and contamination factor results reveal that the study area is not contaminated with respect to Zn, Ni, Cu, and Mn; uncontaminated to moderately contaminate with Pb; and moderately to strongly contaminate with Cd. The high contents of Pb, Cd, and Co in the study area result from various anthropogenic activities including dredging, land filling, localized oil pollution, using of antifouling and anticorrosive paints from fishing and tourist boats, and sewage discharging from various sources within the study area.

  12. 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.

  13. 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

  14. Textural and geochemical characteristics of off shore sediment of North Bay of Bengal:A statistical approach for marine metal pollution

    Institute of Scientific and Technical Information of China (English)

    Sanghamitra Palleyi; Sabnam Banoo; Rabi Narayan Kar; Chitta Ranjan Panda

    2015-01-01

    abstract Metal pollution study on sediments of North Bay of Bengal sediments presented in this paper is based on existing Lithostratigraphy of upstream, mineralogy and geochemical analysis of 42 sediment samples. The statistical analysis identifies the metal pollution as well as its apparent source in the off shore regions. Samples were analyzed for grain size, organic content and heavy metals (Fe, Mn, Cr, Cu, Ni, Pb, Cd, Zn and Co) using the sequential extraction method to evaluate geochemical processes and pollution load. In an effort to surmise anthropogenic input, several approaches including classification by quantitative indexes such as enrichment factor, contamination factor, degree of pollution, pollution load index and geo accumulation index, were attempted. Metal speciation results indicate high%of Cd in exchangeable fraction of Mahanadi transect sediments where as a considerable amount of oxidizable fraction of Cr was detected at Dhamra. Quantitative indexes place North Bay of Bengal under moderately polluted zone due to high level of Cd. Normalization of metals to Fe indicated relatively high enrichment factors for Cd and Cr. Factor analysis identified seven possible types of geochemical associations where sediment pH plays a major role for the heavy metal mobility. The higher Cd concentration in exchangeable fraction as well as the higher EF for Cd and Cr present in sediment may pose a risk of secondary water pollution under slightest disturbance in the geo-chemistry of sediments. Comparison study with available data of near costal zones and upstream stratigraphy revealed that open cast mining, overburden dumping, mineral based industrial effluents were the major source of pollution for catchment area contamination. Bay of Bengal is likely to face a serious threat of metal pollution with the present deposition rates unless rigorous pollution control norms are applied.

  15. Mercury methylation by a microbial community from sediments of the Adour Estuary (Bay of Biscay, France)

    Energy Technology Data Exchange (ETDEWEB)

    Duran, R. [Equipe Environnement et Microbiologie, Institut Pluridisciplinaire de Recherche sur l' Environnement et les Materiaux, UMR CNRS 5254, Universite de Pau et des Pays de l' Adour, Avenue de l' Universite, IBEAS BP1155, 64013 Pau Cedex (France)], E-mail: robert.duran@univ-pau.fr; Ranchou-Peyruse, M.; Menuet, V. [Equipe Environnement et Microbiologie, Institut Pluridisciplinaire de Recherche sur l' Environnement et les Materiaux, UMR CNRS 5254, Universite de Pau et des Pays de l' Adour, Avenue de l' Universite, IBEAS BP1155, 64013 Pau Cedex (France); Monperrus, M.; Bareille, G. [Equipe Chimie Analytique Bio-Inorganique et Environnement, Institut Pluridisciplinaire de Recherche sur l' Environnement et les Materiaux, UMR CNRS 5254, Universite de Pau et des Pays de l' Adour, 64013 Pau Cedex (France); Goni, M.S.; Salvado, J.C. [Equipe Environnement et Microbiologie, Institut Pluridisciplinaire de Recherche sur l' Environnement et les Materiaux, UMR CNRS 5254, Universite de Pau et des Pays de l' Adour, Avenue de l' Universite, IBEAS BP1155, 64013 Pau Cedex (France); Amouroux, D. [Equipe Chimie Analytique Bio-Inorganique et Environnement, Institut Pluridisciplinaire de Recherche sur l' Environnement et les Materiaux, UMR CNRS 5254, Universite de Pau et des Pays de l' Adour, 64013 Pau Cedex (France); Guyoneaud, R. [Equipe Environnement et Microbiologie, Institut Pluridisciplinaire de Recherche sur l' Environnement et les Materiaux, UMR CNRS 5254, Universite de Pau et des Pays de l' Adour, Avenue de l' Universite, IBEAS BP1155, 64013 Pau Cedex (France); Donard, O.F.X. [Equipe Chimie Analytique Bio-Inorganique et Environnement, Institut Pluridisciplinaire de Recherche sur l' Environnement et les Materiaux, UMR CNRS 5254, Universite de Pau et des Pays de l' Adour, 64013 Pau Cedex (France)] (and others)

    2008-12-15

    In order to study the influence of microorganisms on the mercury biogeochemistry, the metal content and the structure of microbial communities were determined in sediments from stations along the Adour Estuary. The comparison of the bacterial communities and their distribution in function of the environmental parameters by Canonical Correspondence Analysis (CCA) revealed the influence of metals on the bacterial communities structure. Sediments where the bacterial communities are mostly influenced by methylmercury were incubated in slurries with or without mercury, under oxic and anoxic conditions. Methylmercury production was detected in the anoxic biotic slurries with a net methylation yield of 0.3% after 24 h. CCA based on T-RFLP profiles revealed the impact of mercury addition on the bacterial communities structure. In addition, 17 bacterial strains, mainly sulphate-reducing bacteria involved in mercury methylation, were isolated and identified. - Role of oxic/anoxic cycles and microbial activities on the methylmercury formation in Adour (France) estuarine sediments.

  16. 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.

  17. Concentrations and compositions of organochlorine contaminants in sediments, soils, crustaceans, fishes and birds collected from Lake Tai, Hangzhou Bay and Shanghai city region, China

    Energy Technology Data Exchange (ETDEWEB)

    Nakata, Haruhiko [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan)]. E-mail: nakata@sci.kumamoto-u.ac.jp; Hirakawa, Yuko [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Kawazoe, Masahiro [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, (Japan); Nakabo, Tetsuji [Kyoto University Museum, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); Arizono, Koji [Faculty of Environmental and Symbiotic Sciences, Kumamoto Prefectural University, 3-1-100 Tsukide, Kumamoto 862-8502 (Japan); Abe, Shin-Ichi [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Kitano, Takeshi [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Shimada, Hideaki [Faculty of Education, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Watanabe, Izumi [Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchuu-city, Tokyo 183-8509 (Japan); Li Weihua [Shanghai Institute of Planned Parenthood Research, 2140 Xie Tu road, Shanghai 200032 (China); Ding Xucheng [Shanghai Institute of Planned Parenthood Research, 2140 Xie Tu road, Shanghai 200032 (China)

    2005-02-01

    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 {sigma}DDTs 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 PCB{sub 5}, 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.

  18. Modeling of Waves, Hydrodynamics and Sediment Transport for Protection of Wetlands at Braddock Bay, New York

    Science.gov (United States)

    2015-03-01

    maximum wave heights near the backbay shoreline from the Jan 1971 storm for S-0, S-1, S-2, and S-3. Table 4-6 presents the calculated maxi - mum wave...decreases inside the bay. At the high water level, it appears wave overtopping pro- duces more flow in the lee of two structures, but flows are weak at...waves and currents significantly in the central backbay peninsula region preceding the wetlands. The maxi - mum wave height calculated for the Hurricane

  19. Seasonal occurrence of unique sediment plume in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Sridhar, P.N.; Ali, M.M.; Vethamony, P.; Babu, M.T.; Ramana, I.V.; Jayakumar, S.

    color monitor (OCM) sensor along with a microwave sensor. Using the OCM data, we studied the suspended sediment concentrations (SSC) during 1999-2006 and observed a plume coming off the Krishna-Godavari River Basin (KGB) that is the only plume within...

  20. Sediment pathways and emergence of Himalayan source material in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

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

    region (about 50 km seaward of the foot-of-the-slope) in water depth of 2678 m. The bore hole penetrated a thickness of 4373 m of sediments and went into the Precambrian basement for 43 m. The second well B is located at a water depth of 2841 m...

  1. An Investigation of the Influence of Waves on Sediment Processes in Skagit Bay

    Science.gov (United States)

    2012-09-30

    coupled wave- current model will resolve the influence of external processes, including tidal forcing, buoyant river discharge, fluvial sediment...panel: energy vs. depth. Fetch calculation includes water level, direction, and position of the observation (Fig 2). 2. Erosion Potential...to set the boundary condition for the momentum equations. Maximum stresses are used to compute the potential cumulative erosion (PCE) in meters. For

  2. 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...

  3. 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...

  4. Characterization of streamflow, suspended sediment, and nutrients entering Galveston Bay from the Trinity River, Texas, May 2014–December 2015

    Science.gov (United States)

    Lucena, Zulimar; Lee, Michael T.

    2017-02-21

    The U.S. Geological Survey (USGS), in cooperation with the Texas Water Development Board and the Galveston Bay Estuary Program, collected streamflow and water-quality data at USGS streamflow-gaging stations in the lower Trinity River watershed from May 2014 to December 2015 to characterize and improve the current understanding of the quantity and quality of freshwater inflow entering Galveston Bay from the Trinity River. Continuous streamflow records at four USGS streamflow-gaging stations were compared to quantify differences in streamflow magnitude between upstream and downstream reaches of the lower Trinity River. Water-quality conditions were characterized from discrete nutrient and sedi­ment samples collected over a range of hydrologic conditions at USGS streamflow-gaging station 08067252 Trinity River at Wallisville, Tex. (hereinafter referred to as the “Wallisville site”), approximately 4 river miles upstream from where the Trinity River enters Galveston Bay.Based on streamflow records, annual mean outflow from Livingston Dam into the lower Trinity River was 2,240 cubic feet per second (ft3/s) in 2014 and 22,400 ft3/s in 2015, the second lowest and the highest, respectively, during the entire period of record (1966–2015). During this study, only about 54 percent of the total volume measured at upstream sites was accounted for at the Wallisville site as the Trinity River enters Galveston Bay. This difference in water volumes between upstream sites and the Wallisville site indicates that at high flows a large part of the volume released from Lake Livingston does not reach Galveston Bay through the main channel of the Trinity River. These findings indicate that water likely flows into wetlands and water bodies surrounding the main channel of the Trinity River before reaching the Wallisville site and is being stored or discharged through other channels that flow directly into Galveston Bay.To characterize suspended-sediment concentrations and loads in

  5. 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

  6. Accumulation patterns of lipophilic organic contaminants in surface sediments and in economic important mussel and fish species from Jakarta Bay, Indonesia.

    Science.gov (United States)

    Dwiyitno; Dsikowitzky, Larissa; Nordhaus, Inga; Andarwulan, Nuri; Irianto, Hari Eko; Lioe, Hanifah Nuryani; Ariyani, Farida; Kleinertz, Sonja; Schwarzbauer, Jan

    2016-09-30

    Non-target screening analyses were conducted in order to identify a wide range of organic contaminants in sediment and animal tissue samples from Jakarta Bay. High concentrations of di-iso-propylnaphthalenes (DIPNs), linear alkylbenzenes (LABs) and polycyclic aromatic hydrocarbons (PAHs) were detected in all samples, whereas phenylmethoxynaphthalene (PMN), DDT and DDT metabolites (DDX) were detected at lower concentrations. In order to evaluate the uptake and accumulation by economic important mussel (Perna viridis) and fish species, contaminant patterns of DIPNs, LABs and PAHs in different compartments were compared. Different patterns of these contaminant groups were found in sediment and animal tissue samples, suggesting compound-specific accumulation and metabolism processes. Significantly higher concentrations of these three contaminant groups in mussel tissue as compared to fish tissue from Jakarta Bay were found. Because P. viridis is an important aquaculture species in Asia, this result is relevant for food safety.

  7. Characterization of Suspended Sediment Plumes Resulting from Barge Decanting in San Francisco Bay

    Science.gov (United States)

    2015-06-01

    vicinity of the dredging operation. Assuming that mobile or drifting organisms were present, exposure to suspended sediments would be very short term, as...of the standpipe and be discharged. A video showing the wave forming as the bucket placed material into the scow can be seen in Video IMG -1909...fell out of suspension to the point where the decant water became relatively clear. This is illustrated in Video IMG 2038. While overflow, as used

  8. Trace metal levels in nearshore sediments close to industrial discharges off Cuddalore (Bay of Bengal)

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, T.; Balachandran, K.K.; Nair, M.; Das, V.K.; Nair, K.K.C.; Paimpillii, J.S.

    97.23 2.75 0.02 °e Table 2 - Sediment Characteristics alon/? different transects(Ran/?es!~ndA vera/?esj ! Transect Sand % Clay % Silt % Organic carbon (mg/g) ! Tl 54.32-98.73 0.30- 8.00 0.02-37.68 2.58.14.21 (89.24) (3.85) (6.90) (5.44) T2 16...

  9. 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.

  10. Distribution of Heavy Metals in Surface Sediments of the Bay of Bengal Coast.

    Science.gov (United States)

    Khan, M Z H; Hasan, M R; Khan, M; Aktar, S; Fatema, K

    2017-01-01

    The concentrations of major (Si, Al, Ca, Fe, and K) and minor (Cd, Mn, Ni, Pb, U, Zn, Co, Cr, As, Cu, Rb, Sr, and Zr,) elements in the surficial sediments were studied in an attempt to establish their concentration in the Bengal coast. It was revealed that the majority of the trace elements have been introduced into the Bengal marine from the riverine inflows that are also affected by the impact of industrial, ship breaking yard, gas production plant, and urban wastes. The concentration of heavy metals was measured using Atomic Absorption Spectroscopy and Energy Dispersive X-ray fluorescence instruments. The highest concentrations for several trace elements were thus recorded which generally decrease with distance from the coast. It was observed that the heavy metal concentrations in the sediments generally met the criteria of international marine sediment quality. However, both the contamination factor and pollution load index values suggested the elevation of some metals' concentrations in the region. Constant monitoring of the Bengal coast water quality needs to be recorded with a view to minimizing the risk of health of the population and the detrimental impacts on the aquatic ecosystem.

  11. Geospatial approach towards enumerative analysis of suspended sediment concentration for Ganges-Brahmaputra Bay

    Science.gov (United States)

    Pandey, Palak; Kunte, Pravin D.

    2016-10-01

    This study presents an easy, modular, user-friendly, and flexible software package for processing of Landsat 7 ETM and Landsat 8 OLI-TIRS data for estimating suspended particulate matter concentrations in the coastal waters. This package includes 1) algorithm developed using freely downloadable SCILAB package, 2) ERDAS Models for iterative processing of Landsat images and 3) ArcMAP tool for plotting and map making. Utilizing SCILAB package, a module is written for geometric corrections, radiometric corrections and obtaining normalized water-leaving reflectance by incorporating Landsat 8 OLI-TIRS and Landsat 7 ETM+ data. Using ERDAS models, a sequence of modules are developed for iterative processing of Landsat images and estimating suspended particulate matter concentrations. Processed images are used for preparing suspended sediment concentration maps. The applicability of this software package is demonstrated by estimating and plotting seasonal suspended sediment concentration maps off the Bengal delta. The software is flexible enough to accommodate other remotely sensed data like Ocean Color monitor (OCM) data, Indian Remote Sensing data (IRS), MODIS data etc. by replacing a few parameters in the algorithm, for estimating suspended sediment concentration in coastal waters.

  12. Distribution of Heavy Metals in Surface Sediments of the Bay of Bengal Coast

    Science.gov (United States)

    Hasan, M. R.; Khan, M.; Aktar, S.; Fatema, K.

    2017-01-01

    The concentrations of major (Si, Al, Ca, Fe, and K) and minor (Cd, Mn, Ni, Pb, U, Zn, Co, Cr, As, Cu, Rb, Sr, and Zr,) elements in the surficial sediments were studied in an attempt to establish their concentration in the Bengal coast. It was revealed that the majority of the trace elements have been introduced into the Bengal marine from the riverine inflows that are also affected by the impact of industrial, ship breaking yard, gas production plant, and urban wastes. The concentration of heavy metals was measured using Atomic Absorption Spectroscopy and Energy Dispersive X-ray fluorescence instruments. The highest concentrations for several trace elements were thus recorded which generally decrease with distance from the coast. It was observed that the heavy metal concentrations in the sediments generally met the criteria of international marine sediment quality. However, both the contamination factor and pollution load index values suggested the elevation of some metals' concentrations in the region. Constant monitoring of the Bengal coast water quality needs to be recorded with a view to minimizing the risk of health of the population and the detrimental impacts on the aquatic ecosystem. PMID:28255298

  13. Response of Microbial Community to Petroleum Stress and Phosphate Dosage in Sediments of Jiaozhou Bay, China

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yangguo; CHEN Min; BAI Jie; LI Xinwei; Farhana Zulfiqar; WANG Qianli

    2014-01-01

    The dynamic microcosms were used to evaluate the effect of oil spills on microbial ecological system in marine sedi-ment and the enhancement of nutrient on the oil removal. The function and structure of microbial community caused by the oil pollu-tion and phosphate dosage were simultaneously monitored by dehydrogenase activity assay and PCR-denaturing gradient gel elec-trophoresis (DGGE) techniques. The results indicated that the amount of total bacteria in all dynamic microcosms declined rapidly with incubation time. The number of petroleum-degrading bacteria and the activity of sediment dehydrogenase were gradually en-hanced by petroleum in the oil-treated microcosms, while they both showed no obvious response to phosphate dosage. In comparison, phosphate spiked heterotrophic bacteria and they showed a significant increase in amount. DGGE profiles indicated that petroleum dosage greatly changed community structure, and the bacteria belonged to class Deltaproteobacteria, and phyla Bacteroidetes and Chlorobi were enriched. This study demonstrated that petroleum input greatly impacted the microbial community structure and con-sequently the marine sediment petroleum-degrading activity was enhanced. Phosphate dosage would multiply heterotrophic bacteria but not significantly enhance the petroleum degradation.

  14. Comparison of two regression-based approaches for determining nutrient and sediment fluxes and trends in the Chesapeake Bay watershed

    Science.gov (United States)

    Moyer, Douglas; Hirsch, Robert M.; Hyer, Kenneth

    2012-01-01

    Nutrient and sediment fluxes and changes in fluxes over time are key indicators that water resource managers can use to assess the progress being made in improving the structure and function of the Chesapeake Bay ecosystem. The U.S. Geological Survey collects annual nutrient (nitrogen and phosphorus) and sediment flux data and computes trends that describe the extent to which water-quality conditions are changing within the major Chesapeake Bay tributaries. Two regression-based approaches were compared for estimating annual nutrient and sediment fluxes and for characterizing how these annual fluxes are changing over time. The two regression models compared are the traditionally used ESTIMATOR and the newly developed Weighted Regression on Time, Discharge, and Season (WRTDS). The model comparison focused on answering three questions: (1) What are the differences between the functional form and construction of each model? (2) Which model produces estimates of flux with the greatest accuracy and least amount of bias? (3) How different would the historical estimates of annual flux be if WRTDS had been used instead of ESTIMATOR? One additional point of comparison between the two models is how each model determines trends in annual flux once the year-to-year variations in discharge have been determined. All comparisons were made using total nitrogen, nitrate, total phosphorus, orthophosphorus, and suspended-sediment concentration data collected at the nine U.S. Geological Survey River Input Monitoring stations located on the Susquehanna, Potomac, James, Rappahannock, Appomattox, Pamunkey, Mattaponi, Patuxent, and Choptank Rivers in the Chesapeake Bay watershed. Two model characteristics that uniquely distinguish ESTIMATOR and WRTDS are the fundamental model form and the determination of model coefficients. ESTIMATOR and WRTDS both predict water-quality constituent concentration by developing a linear relation between the natural logarithm of observed constituent

  15. Evaluation of sediment trace metal records as paleoproductivity and paleoxygenation proxies in the upwelling center off Concepción, Chile (36°S)

    Science.gov (United States)

    Muñoz, Praxedes; Dezileau, Laurent; Lange, Carina; Cardenas, Lissette; Sellanes, Javier; Salamanca, Marco A.; Maldonado, Antonio

    2012-01-01

    This study analyzes the records of several trace metals sensitive to redox conditions in continental shelf sediments off Concepción, Chile (36°S). The continental margin off Concepción (36°S; 73°W) lies beneath an important upwelling center characterized by high primary production rates and, consequently, high fluxes of organic matter. In spring and summer, this material settles to the seafloor where it decays, producing periods of very low oxygen content in bottom waters (oxygen minimum zone develops at ∼100-400 m water depth, where dissolved oxygen levels are events, when dissolved oxygen at the bottom increases drastically (>1 mL L -1). The goals of this study were to determine the input of trace metals to the sediment and to decipher how this information can be used to reveal variations in primary productivity or bottom oxygenation. Gravity cores collected at two stations - VG06-2 over the mid-shelf station (88 m water depth, upper boundary of the oxygen minimum zone) and VG06-3 over the outer shelf (120 m water depth, within the oxygen minimum zone) - were sampled for high resolution profiles (1 cm) of trace metals, biogenic opal, stable isotopes, and total organic carbon. The results suggest that the variability in the trace metal distribution on the continental shelf off Concepción is determined by redox conditions and the organic carbon flux to the bottom. Some sections of the sediment cores from the outer shelf showed appreciable authigenic enrichment of U, Cd, and Mo (EF: 5-10, 2-5, and 10-16 respectively) along with heavier values of δ 15N, suggesting periods of suboxic conditions. During these periods, fluxes of organic material to the bottom were higher, as indicated by elevated TOC and opal contents. Alternating periods of higher and lower trace metal contents were not observed mid-shelf as they were on the outer shelf. Rather, the mid-shelf samples showed authigenic enrichment of U, Cd, and Mo (EF: 1-6, 4-5, and 10-20, respectively

  16. 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.

  17. 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.

  18. Dynamics of REE accumulation and fractionation in the subcolloidal fraction of bottom sediments in the Razdol'naya River-Amur Bay section, Sea of Japan

    Science.gov (United States)

    Polyakov, D. M.

    2016-05-01

    The REE contents (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) are determined by atomic emission spectroscopy in the subcolloidal fraction of bottom sediments in the Razdol'naya River-Amur Bay section. The mean contents of lanthanides in soils and river bottom sediments (before the mixing zone) are calculated. The increase in REE content and the fractioning in the series from light to middle and heavy REE in sediments of different estuary zones (river, water mixing, and marine), with the latter related to flocculation, sorption on iron and manganese hydroxides, clay minerals (hydromica, smectites), and lifetime accumulation of marine plankton, are dtermined. Via extraction of 0.5 N sodium hydroxide solution, the content of lanthanides associated with humic substances of subcolloidal fraction from the Amur Bay sediments are determined: 1.3 to 8.2% of La; 1.1 to 11% of Ce; and 0.3 to 1.5 of Gd.

  19. 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.

  20. 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

  1. 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

    -scale measurements showed that it extended to the upper 0-2.5 mm during summer, when the zones of Mn and Fe reduction were compressed towards the surface. Most of the H2S produced precipitated as iron sulfides and S0 by reaction with Fe. Both Fe(III) and a nonsulfur-bound authigenic Fe(II) pool reacted efficiently...... with H2S. The authigenic Fe(II) pool was present at one hundredfold higher concentration than dissolved Fe2+. Only 15% of the precipitated sulfide was buried permanently. Most of the reoxidation of reduced S occurred within 1 cm of the sediment-water interface and was supported by upward bioturbation....... 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...

  2. Examination of factors dominating the sediment-water diffusion flux of DDT-related compounds measured by passive sampling in an urbanized estuarine bay.

    Science.gov (United States)

    Feng, Yan; Wu, Chen-Chou; Bao, Lian-Jun; Shi, Lei; Song, Lin; Zeng, Eddy Y

    2016-12-01

    The fate of hydrophobic organic compounds in aquatic environment are largely determined by their exchange at sediment-water interface, which is highly dynamic and subject to rapidly evolving environmental conditions. In turn, environmental conditions may be governed by both physicochemical parameters and anthropogenic events. To examine the importance of various impact factors, passive sampling devices were deployed at the seafloor of Hailing Bay, an urbanized estuarine bay in Guangdong Province of South China to measure the sediment-water diffusion fluxes of several metabolites of dichlorodiphenyltrichloroethane (DDT), p,p'-DDE, p,p'-DDD and o,p'-DDD. The physicochemical properties of water (temperature, pH, salinity and dissolved oxygen) and surface sediment (sediment organic matter, physical composition, pH, water content, colony forming unit and catalase activity) were also measured. The results showed that the diffusion fluxes of o,p'-DDD, p,p'-DDD and p,p'-DDE at sites A1 and A2 near a fishing boat maintenance facility ranged from 0.42 to 4.73 ng m(-2) d(-1) (from sediment to overlying water), whereas those at offshore sites varied between -0.03 and -3.02 ng m(-2) d(-1) (from overlying water to sediment), implicating A1 and A2 as the sources of the target compounds. The distribution patterns of the diffusion fluxes of the target compounds were different from those of water and sediment parameters (water temperature, salinity, sediment texture, pH, colony forming unit and catalase activity) at six sampling sites. This finding suggested that none of these parameters were critical in dictating the sediment-water diffusion fluxes. Besides, decreases in the contents of kerogen and black carbon by 6.7% and 11% would enhance the diffusion fluxes of the target compounds by 11-14% and 12-23%, respectively, at site A1, indicating that kerogen and black carbon were the key factors in mediating the sediment-water diffusion fluxes of DDT-related compounds in field

  3. 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.

  4. Sediment profile image data from June 1995 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,...

  5. Sediment profile image 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 profile images (SPI) of the sediment-water interface were collected using a sediment profiling camera at pre-determined locations in the harbor. Physical,...

  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. Variability of the internal tide on the southern Monterey Bay continental shelf and associated bottom boundary layer sediment transport

    Science.gov (United States)

    Rosenberger, Kurt; Storlazzi, Curt; Cheriton, Olivia

    2016-01-01

    A 6-month deployment of instrumentation from April to October 2012 in 90 m water depth near the outer edge of the mid-shelf mud belt in southern Monterey Bay, California, reveals the importance regional upwelling on water column density structure, potentially accounting for the majority of the variability in internal tidal energy flux across the shelf. Observations consisted of time-series measurements of water-column currents, temperature and salinity, and near-bed currents and suspended matter. The internal tide accounted for 15–25% of the water-column current variance and the barotropic tide accounted for up to 35%. The subtidal flow showed remarkably little shear and was dominated by the 7–14 day band, which is associated with relaxations in the dominant equatorward winds typical of coastal California in the spring and summer. Upwelling and relaxation events resulted in strong near-bed flows and accounted for almost half of the current stress on the seafloor (not accounting for wave orbital velocities), and may have driven along-shelf geostrophic flow during steady state conditions. Several elevated suspended particulate matter (SPM) events occurred within 3 m of the bed and were generally associated with higher, long-period surface waves. However, these peaks in SPM did not coincide with the predicted resuspension events from the modeled combined wave–current shear stress, indicating that the observed SPM at our site was most likely resuspended elsewhere and advected along-isobath. Sediment flux was almost equal in magnitude in the alongshore and cross-shore directions. Instances of wave–current shear stress that exceeded the threshold of resuspension for the silty-clays common at these water depths only occurred when near-bed orbital velocities due to long-period surface waves coincided with vigorous near-bed currents associated with the internal tide or upwelling/relaxation events. Thus upwelling/relaxation dynamics are primarily responsible for

  9. Variability of the internal tide on the southern Monterey Bay continental shelf and associated bottom boundary layer sediment transport

    Science.gov (United States)

    Rosenberger, Kurt J.; Storlazzi, Curt D.; Cheriton, Olivia M.

    2016-06-01

    A 6-month deployment of instrumentation from April to October 2012 in 90 m water depth near the outer edge of the mid-shelf mud belt in southern Monterey Bay, California, reveals the importance regional upwelling on water column density structure, potentially accounting for the majority of the variability in internal tidal energy flux across the shelf. Observations consisted of time-series measurements of water-column currents, temperature and salinity, and near-bed currents and suspended matter. The internal tide accounted for 15-25% of the water-column current variance and the barotropic tide accounted for up to 35%. The subtidal flow showed remarkably little shear and was dominated by the 7-14 day band, which is associated with relaxations in the dominant equatorward winds typical of coastal California in the spring and summer. Upwelling and relaxation events resulted in strong near-bed flows and accounted for almost half of the current stress on the seafloor (not accounting for wave orbital velocities), and may have driven along-shelf geostrophic flow during steady state conditions. Several elevated suspended particulate matter (SPM) events occurred within 3 m of the bed and were generally associated with higher, long-period surface waves. However, these peaks in SPM did not coincide with the predicted resuspension events from the modeled combined wave-current shear stress, indicating that the observed SPM at our site was most likely resuspended elsewhere and advected along-isobath. Sediment flux was almost equal in magnitude in the alongshore and cross-shore directions. Instances of wave-current shear stress that exceeded the threshold of resuspension for the silty-clays common at these water depths only occurred when near-bed orbital velocities due to long-period surface waves coincided with vigorous near-bed currents associated with the internal tide or upwelling/relaxation events. Thus upwelling/relaxation dynamics are primarily responsible for variability

  10. 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

  11. 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.

  12. Processes influencing the transport and fate of contaminated sediments in the coastal ocean: Boston Harbor and Massachusetts Bay

    Science.gov (United States)

    Bothner, Michael H.; Butman, Bradford

    2007-01-01

    Most of the major urban centers of the United States including Boston, New York, Washington, Chicago, New Orleans, Miami, Los Angeles, San Francisco, and Seattle—are on a coast (fig. 1.1). All of these cities discharge treated sewage effluent into adjacent waters. In 2000, 74 percent of the U.S. population lived within 200 kilometers (km) of the coast. Between 1980 and 2002, the population density in coastal communities increased approximately 4.5 times faster than in noncoastal areas of the U.S. (Perkins, 2004). More people generate larger volumes of wastes, increase the demands on wastewater treatment, expand the area of impervious land surfaces, and use more vehicles that contribute contaminants to street runoff. According to the National Coastal Condition Report II (U.S. Environmental Protection Agency, 2005a), on the basis of coastal habitat, water and sediment quality, benthic index, and fish tissue, the overall national coastal condition is only poor to fair and the overall coastal condition in the highly populated Northeast is poor. Scientific information helps managers to prioritize and regulate coastal-ocean uses that include recreation, commercial fishing, transportation, waste disposal, and critical habitat for marine organisms. These uses are often in conflict with each other and with environmental concerns. Developing a strategy for managing competing uses while maintaining sustainability of coastal resources requires scientific understanding of how the coastal ocean system behaves and how it responds to anthropogenic influences. This report provides a summary of a multidisciplinary research program designed to improve our understanding of the transport and fate of contaminants in Massachusetts coastal waters. Massachusetts Bay and Boston Harbor have been a focus of U.S. Geological Survey (USGS) research because they provide a diverse geographic setting for developing a scientific understanding of the geology, geochemistry, and oceanography of

  13. 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

  14. A chemostratigraphic method to determine the end of impact-related sedimentation at marine-target impact craters (Chesapeake Bay, Lockne, Tvären)

    Science.gov (United States)

    Ormö, Jens; Hill, Andrew C.; Self-Trail, Jean M.

    2010-01-01

    To better understand the impact cratering process and its environmental consequences at the local to global scale, it is important to know when in the geological record of an impact crater the impact-related processes cease. In many instances, this occurs with the end of early crater modification, leaving an obvious sedimentological boundary between impactites and secular sediments. However, in marine-target craters the transition from early crater collapse (i.e., water resurge) to postimpact sedimentation can appear gradual. With the a priori assumption that the reworked target materials of the resurge deposits have a different chemical composition to the secular sediments we use chemostratigraphy (δ13Ccarb, %Corg, major elements) of sediments from the Chesapeake Bay, Lockne, and Tvären craters, to define this boundary. We show that the end of impact-related sedimentation in these cases is fairly rapid, and does not necessarily coincide with a visual boundary (e.g., grain size shift). Therefore, in some cases, the boundary is more precisely determined by chemostratigraphy, especially carbonate carbon isotope variations, rather than by visual inspection. It is also shown how chemostratigraphy can confirm the age of marine-target craters that were previously determined by biostratigraphy; by comparing postimpact carbon isotope trends with established regional trends.

  15. 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.

  16. 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.

    2016-06-23

    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.

  17. Wind-enhanced resuspension in the shallow waters of South San Francisco Bay: Mechanisms and potential implications for cohesive sediment transport

    Science.gov (United States)

    Brand, Andreas; Lacy, Jessica R.; Hsu, Kevin; Hoover, Daniel; Gladding, Steve; Stacey, Mark T.

    2010-01-01

    We investigated the driving forces of sediment dynamics at the shoals in South San Francisco Bay. Two stations were deployed along a line perpendicular to a 14 m deep channel, 1000 and 2000 m from the middle of the channel. Station depths were 2.59 and 2.19 m below mean lower low water, respectively. We used acoustic Doppler velocimeters for the simultaneous determination of current velocities, turbulence, sediment concentration and fluxes. Maximum current shear velocities were 0.015 m s−1 at the station further from the channel (closer to the shore) and 0.02 m s−1 at the station closer to the channel. Peak wave-induced shear velocities exceeded 0.015 m s−1 at both stations. Maximum sediment concentrations were around 30 g m−3 during calm periods (root mean square wave height −3 and sediment fluxes were 5 times higher than in calm conditions (0.02 g m−2 s−1 versus >0.10 g m−2 s−1) at the station further from the channel 0.36 m above the bed. Closer to the channel, sediment concentrations and vertical fluxes due to wind wave resuspension were persistently lower (maximum concentrations around 50 g m−3 and maximum fluxes around 0.04 g m−2 s−1). Most resuspension events occurred during flood tides that followed wave events during low water. Although wave motions are able to resuspend sediment into the wave boundary layer at low tide, the observed large increases in sediment fluxes are due to the nonlinear interaction of wind waves and the tidal currents.

  18. Variabilidad espacial y temporal en la hidrografía invernal del sistema de bahías frente a la VIII región (Chile centro-sur Spatial and temporal variability of winter hydrography in the bay system off the VIII region (central-south Chile

    Directory of Open Access Journals (Sweden)

    PATRICIA FAÚNDEZ-BÁEZ

    2001-12-01

    Full Text Available En la zona centro-sur de Chile (VIII región existe un sistema de bahías (~ 36°30'-37° S, que incluye las bahías de Concepción (BC, San Vicente (BSV y Coronel en el sector oriental del Golfo de Arauco (SOGA, conocido como un importante centro de desove y reclutamiento de especies de peces durante el período invernal. En el presente estudio se analizó la variabilidad hidrográfica (temperatura, salinidad y estratificación, en la dimensión espacial (dentro y entre bahías y temporal (entre años de muestreo, así como su relación con las condiciones meteorológicas (viento y precipitaciones y aporte fluvial (caudal de ríos, durante el período invernal (julio-agosto entre 1993 y 1996. A nivel superficial (1 m y estrato 1-10 m las tres bahías mostraron heterogeneidad espacial en las distribuciones de temperatura y salinidad, especialmente entre las zonas del saco y la boca. A este nivel, además, los menores valores de temperatura y salinidad ocurrieron generalmente en SOGA, la que además presentó una mayor estratificación por efecto de la presencia de aguas de mayor dilución (The central-south area of Chile (VIII region presents a system of bays (~36°30'-37º S, including the bays of Concepcion (BC, San Vicente (BSV and Coronel in the eastern boundary of the Gulf of Arauco (SOGA. This system has been recognized as an important center for the spawning and recruitment of fish species during the winter. In the present study the hydrographic variability (temperature, salinity and density, both in space (inside and between the bays and time (between sampling years, during the winter period (July-August between 1993 and 1996, was analyzed. As well, its relationship to the meteorological conditions (wind and rainfall and fluvial contribution (river discharge was explored. At the surface level (1 m and 1-10 m depth stratum, the three bays showed spatial heterogeneity in temperature and salinity distributions, especially between the inner

  19. 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....

  20. 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.

  1. 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.

  2. Polychlorinated biphenyls (PCBs) and Polybrominated Diphenyl Ethers (PBDEs) in surface sediments from Monastir Bay (Tunisia, Central Mediterranean): occurrence, distribution and seasonal variations.

    Science.gov (United States)

    Nouira, Taoufik; Risso, Christine; Chouba, Lassaad; Budzinski, Hélène; Boussetta, Hamadi

    2013-09-01

    An assessment of PCB and PBDE contamination of surface sediments in Monastir Bay was carried out in two contrasted seasons of the year. Samples were collected from 5 sites and analyzed for the ∑7 marker PCBs (i.e. PCBs 28, 52, 101, 118, 138, 153 and 180) and ∑4 PBDE congeners (PBDEs 47, 99, 119 and 153) by GC/ECD. Concentrations of both PCBs and PBDEs showed seasonal variations. PCB concentrations were in the range of 3.1-9.3 ng g(-1) and 1.1-8.1 ng g(-1) in wet and dry season respectively, and sediments were considered moderately contaminated with PCBs. All PCBs analyzed were detected in surface sediments. PCB 153 and 52 congeners showed the highest relative abundance in both winter and summer. PBDE concentrations ranged from not detect to 0.1 ng g(-1), with only BDE-47 congener detected in sediments and only in winter. Analysis of spatial and seasonal variations indicated that PCB distribution is governed by hydrodynamics and temporal variability of inputs. While the PCB contamination appeared to be mainly land-based, PBDEs are suspected to originate from atmospheric deposition.

  3. Geologic columns for the ICDP-USGS Eyreville A and B cores, Chesapeake Bay impact structure: Sediment-clast breccias, 1096 to 444 m depth

    Science.gov (United States)

    Edwards, L.E.; Powars, D.S.; Gohn, G.S.; Dypvik, H.

    2009-01-01

    The Eyreville A and B cores, recovered from the "moat" of the Chesapeake Bay impact structure, provide a thick section of sediment-clast breccias and minor stratified sediments from 1095.74 to 443.90 m. This paper discusses the components of these breccias, presents a geologic column and descriptive lithologic framework for them, and formalizes the Exmore Formation. From 1095.74 to ??867 m, the cores consist of nonmarine sediment boulders and sand (rare blocks up to 15.3 m intersected diameter). A sharp contact in both cores at ??867 m marks the lowest clayey, silty, glauconitic quartz sand that constitutes the base of the Exmore Formation and its lower diamicton member. Here, material derived from the upper sediment target layers, as well as some impact ejecta, occurs. The block-dominated member of the Exmore Formation, from ??855-618.23 m, consists of nonmarine sediment blocks and boulders (up to 45.5 m) that are juxtaposed complexly. Blocks of oxidized clay are an important component. Above 618.23 m, which is the base of the informal upper diamicton member of the Exmore Formation, the glauconitic matrix is a consistent component in diamicton layers between nonmarine sediment clasts that decrease in size upward in the section. Crystalline-rock clasts are not randomly distributed but rather form local concentrations. The upper part of the Exmore Formation consists of crudely fining-upward sandy packages capped by laminated silt and clay. The overlap interval of Eyreville A and B (940-??760 m) allows recognition of local similarities and differences in the breccias. ?? 2009 The Geological Society of America.

  4. 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)

  5. 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

  6. 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)

    Kristi S Shaw

    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

  7. Composition and vertical distribution of metazoan meiofauna assemblages on the continental shelf off central Chile

    Directory of Open Access Journals (Sweden)

    Eulogio Soto

    2015-11-01

    Full Text Available A quantitative study of metazoan meiofauna was carried out in Valparaiso Bay (33°S 71°W which is affected by seasonal hypoxia in central Chile. The contents of bottom water, dissolved oxygen (BWDO, organic carbon, chloroplast pigments and composition of stable carbon isotope (δ13C in the sediment were used as a measure of the contribution of primary production in the water column, which accumulates in the sediment. Meiofauna abundances in the three sampling stations (80-140 m depth ranged from 2.218 ± 643 to 1.592 ± 148 ind 10 cm-2. Nine upper metazoan meiofauna groups were recorded, with nematodes as the dominant group, contributing with more than 95% of total abundances. The abundance vertical distribution was concentrated in the first layers of sediment in most groups except Acari and nauplii larvae. Canonical correspondence analysis revealed significant correlations (P < 0.05 between the meiofauna abundance and organic content, depth and redox potential from sediments. These results represent a first approach to understanding the ecology of meiofaunal assemblages in the Valparaiso Bay and may be useful as a baseline for future comparisons and descriptions of the ENSO (El Niño Southern Oscillation and seasonal variations of these unknown benthic communities.

  8. 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

    , 133 , 227 ? 248. 21. Prell, W. C., Hutson, W. H., Williams, D. F., Be, A. W. H., Gei t senauer, K. and Molfineo, B., Quat. Res ., 1980, 14 , 309 ? 336. 22. Ramaswamy, V. and Parthiban, G., Geol. Surv. India Spec. Publ ., 1992 , 29 , 25...: Inf erence from clay mi n eral studies in a core from the Western Bay of Bengal N. P. C. Reddy* and K. Mohana Rao Regional Centre, National Institute of Oceanography, 176, Lawson?s Bay, Visakhapatnam 530 017, India Clay mineral studies...

  9. PAH-biodegradation potential of indigenous microorganisms: evidence from the respiratory activity of surface sediments in the Quanzhou Bay in China

    Institute of Scientific and Technical Information of China (English)

    GU Tihua; WANG Zhaoshou; TIAN Yun; HUANG Bangqin; ZHENG Tianling

    2009-01-01

    Seven stations were established in the Quanzhou Bay (24.73°-24.96°N, 118.50°-118.70°E) in China on three cruises to determine the concentrations of polycyclic aromatic hydrocarbons (PAHs) and the numbers of PAH-degrading bacteria in surface sediments. Assessing the biodegradation poten-tial of indigenous microorganisms by measuring the respiratory intensity with the addition of PAHs in sediment samples was also one of the aims of this study. The results show that the total PAH concentrations of the sediments were 99.23-345.53 ng/g dry weight (d.w.), and the PAHs compo-sition pattern in the sediments was dominated by phenanthrene, fluoranthene and pyrene. The numbers of phenanthrene, fluoranthene and pyrene-degrading bacteria during three cruises were 1.42×103-8.93×104 CFU/g d.w., 8.29×103-9.43×104 CFU/g d.w. and 7.05×103-9.43×4 CFU/g d.w., respectively. The addition of three model PAH compounds (phenanthrene, fluoranthene and pyrene) showed a great influence on the increasing of the microbial activity in the sediments. And there was a significant correlation among the change of respiratory activity, PAH concentration and the number of PAH-degrading bacteria. The change in respiratory activity under PAHs selective pressure could, to a certain extent, indicate the potential degradative activity of the PAH-degrading microbial community.

  10. 博贺湾海域悬沙输移机制分析%Analyses of mechanism of suspended sediment transport in Bohe Bay

    Institute of Scientific and Technical Information of China (English)

    樊立东; 童朝锋; 孟艳秋

    2016-01-01

    According to measured hydrological and suspended sediment data from spring tides in Bohe Bay, the suspended sediment transport flux was divided into several dynamic items using the mechanism decomposition method, and the mechanism of suspended sediment transport was analyzed in terms of the advection sediment transport, tidal pumping effect, and vertical circulation transport. The results show that the Lagrangian residual current basically moves in the direction of the flood tide and its value increases with the distance from the shore. The Euler residual current has a value similar to the Lagrangian residual current, while the value of the Stokes residual current is close to zero. The advection is the leading factor affecting the suspended sediment transport and the transport effect of the Euler residual current is correlated with preferential flow in the tidal process. The tidal pumping effect in Bohe Bay does not have a strong influence on the suspended sediment transport, and it is induced by the asymmetry of the tidal current and suspended sediment concentration. The vertical residual circulation has a weak effect on the suspended sediment transport and is related to the vertical distributions of the Lagrange residual current and suspended sediment concentration.%根据博贺湾海域大潮期间的水文泥沙实测资料,采用悬沙通量机制分解法将悬沙净输移通量分解为多个动力项,并分别从平流输沙、潮泵输沙和垂向净环流输沙三方面分析了悬沙输移机制。结果表明:博贺湾海域大潮期间拉格朗日余流基本沿涨潮方向,离岸越远,余流值越大,欧拉余流大小与拉格朗日余流相近,斯托克斯余流接近于零;平流输沙在悬沙净输移中占主导作用,其中欧拉余流输沙作用方向与涨落潮优势流相关;博贺湾海域潮泵效应输沙作用不强,潮泵作用由涨落潮潮流和含沙量在潮周期的不对称性引起;垂向余环流输

  11. 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...

  12. Consistent assessment of trace metal contamination in surface sediments and suspended particulate matter: a case study from the Jade Bay in NW Germany.

    Science.gov (United States)

    Beck, Melanie; Böning, Philipp; Schückel, Ulrike; Stiehl, Thorsten; Schnetger, Bernhard; Rullkötter, Jürgen; Brumsack, Hans-Jürgen

    2013-05-15

    Recently, within the framework of European directives, the importance of marine monitoring programs has increased. In this study, a dense sampling grid was applied for a detailed assessment of the metal contents of surface sediments and suspended particulate matter from the Jade Bay, one of the tidal basins in the southern North Sea. The local lithogenic background was defined and compared with average shale, a common reference material. Based on the calculated non-lithogenic fraction and a cluster analysis, the metals are distributed in two groups: (i) elements of mainly natural origin (Co, Cr, and a major portion of Cd) and (ii) elements associated with anthropogenic activity (As, Cd, Cu, Ni, Pb, Sn, and Zn). However, even the metals of the second group are enriched by at most a factor of two relative to the local background, suggesting minimal anthropogenic impact. Spatial distribution maps show that the harbor area of Wilhelmshaven may be a particularly important source of metal.

  13. A novel approach for characterization of polycyclic aromatic hydrocarbon (PAH) pollution patterns in sediments from Guanabara Bay, Rio de Janeiro, Brazil.

    Science.gov (United States)

    Christensen, Jan H; Tomasi, Giorgio; de Lemos Scofield, Arthur; de Fatima Guadalupe Meniconi, Maria

    2010-10-01

    A novel multivariate method based on principal component analysis of pre-processed sections of chromatograms is used to characterize the complex PAH pollution patterns in sediments from Guanabara Bay, Brazil. Five distinct sources of 3- to 6-ring PAHs could be revealed. The harbour is the most contaminated site in the bay, its plume stretches in a South West to North East direction and the chemical profile indicates mainly pyrogenic sources mixed with a fraction of high-molecular-weight petrogenic PAHs. Rio São João de Meriti is the second largest source of PAHs, and introduces mainly a fraction of low-molecular-weight petrogenic PAHs from the western region of Rio de Janeiro. The sites close to the ruptured pipeline at the Duque de Caxias Refinery show a distinctive pollution pattern indicating a heavy petroleum fraction. The method also led to the identification of new potential indicator ratios also involving coeluting peaks (e.g., triphenylene and chrysene).

  14. 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)

  15. 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 lakes, and CF and BSF lakes, but not between IPP and BSF lakes. These results are consistent with water chemistry measurements, which indicated distinct limnological conditions for CF lakes. Diatom communities in CF lakes were generally dominated by alkaliphilous taxa typical of waters with medium to high conductivity, such as Nitzschia denticula. In contrast, several IPP and BSF lakes were dominated by acidophilous and circumneutral diatom taxa with preference for low conductivity (e.g., Tabellaria flocculosa, Eunotia mucophila, E. necompacta var. vixcompacta). This exploratory survey provides a first detailed 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.

  16. Geologic columns for the ICDP-USGS Eyreville A and C cores, Chesapeake Bay impact structure: Postimpact sediments, 444 to 0 m depth

    Science.gov (United States)

    Edwards, L.E.; Powars, D.S.; Browning, J.V.; McLaughlin, P.P.; Miller, K.G.; ,; Kulpecz, A.A.; Elbra, T.

    2009-01-01

    A 443.9-m-thick, virtually undisturbed section of postimpact deposits in the Chesapeake Bay impact structure was recovered in the Eyreville A and C cores, Northampton County, Virginia, within the "moat" of the structure's central crater. Recovered sediments are mainly fine-grained marine siliciclastics, with the exception of Pleistocene sand, clay, and gravel. The lowest postimpact unit is the upper Eocene Chickahominy Formation (443.9-350.1 m). At 93.8 m, this is the maximum thickness yet recovered for deposits that represent the return to "normal marine" sedimentation. The Drummonds Corner beds (informal) and the Old Church Formation are thin Oligocene units present between 350.1 and 344.7 m. Above the Oligocene, there is a more typical Virginia coastal plain succession. The Calvert Formation (344.7-225.4 m) includes a thin lower Miocene part overlain by a much thicker middle Miocene part. From 225.4 to 206.0 m, sediments of the middle Miocene Choptank Formation, rarely reported in the Virginia coastal plain, are present. The thick upper Miocene St. Marys and Eastover Formations (206.0-57.8 m) appear to represent a more complete succession than in the type localities. Correlation with the nearby Kiptopeke core indicates that two Pliocene units are present: Yorktown (57.8-32.2 m) and Chowan River Formations (32.2-18.3 m). Sediments at the top of the section represent an upper Pleistocene channel-fill and are assigned to the Butlers Bluff and Occohannock Members of the Nassawadox Formation (18.3-0.6 m). ?? 2009 The Geological Society of America.

  17. 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.

  18. Coupling of bacterial nitrification with denitrification and anammox supports N removal in intertidal sediments (Arcachon Bay, France)

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, S.O.; Javanaud, C.; Michotey, V.D.; Guasco, S.; Anschutz, P.; Bonin, P.

    variations in prokaryotic abundance (Bacteria, Archaea) and of functional groups responsible for nitrification and denitrification were studied by qPCR and for anammoxifiers by cloning. Bacterial density in both sediment types varied between 107-8

  19. 2002 Sediment Grab Data for Catlett and Goodwin Islands on the York River, Chesapeake Bay, Virginia (Ches_2002sedgrabs)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set represents the sediment grain size gathered from grab sampling in 2002 (56 stations).In Fall/Winter 2002, researchers from the Virginia Institute of...

  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.K.; Mahalaxmi, P.; Joao, H.M.; Jisha, R.

    -G and Mahanadi sediments, respectively. The Fe2O3 vs TiO2 plot (Fig. 4 B) 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... (Taylor and McLennan, 1985). The La/Sc ratios of K-G and Mahanadi sediments range from 0.15-2.5 (avg.: 1.57) and 1.7- 3.2 (2.4), respectively. The data clusters in the La-Th-Sc ternary diagram (Figs. 6A and B) fall between average basalt and granite...

  1. 2003 Sediment Grab Data for Catlett and Goodwin Islands on the York River, Chesapeake Bay, Virginia (Ches_2003sedgrabs)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set represents the sediment grain size gathered from grab sampling in 2003 (24 stations).In Fall/Winter 2002, researchers from the Virginia Institute of...

  2. 2004 Sediment Grab Data for Catlett and Goodwin Islands on the York River, Chesapeake Bay, Virginia (Ches_2004sedgrabs)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set represents the sediment grain size gathered from grab sampling in 2004 (12 stations). In Fall/Winter 2002, researchers from the Virginia Institute of...

  3. 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

  4. 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 of

  5. 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.

  6. Younger Dryas and Holocene oceanography of the western Labrador Sea region based on foraminifera and sediment proxies from Placentia Bay, Newfoundland

    Science.gov (United States)

    Sheldon, Christina; Pearce, Christof; Seidenkrantz, Marit-Solveig; Kuijpers, Antoon; Reynisson, Njáll F.; Zilmer Christensen, Eva; Juncker Hansen, Mette

    2014-05-01

    Benthic foraminiferal assemblages and geochemical analyses from three marine sediment cores from Placentia Bay on the southwest coast of Newfoundland captured the evolving surface and subsurface environment of the eastern Labrador Sea during the late glacial and Holocene. The area, which is today located in the boundary zone between the Arctic Labrador current and the warm Gulf Stream in the eastern margin of the Labrador Sea was during the early part of the Younger Dryas (13.0-12.3 cal. kyr BP) dominated by cold, Arctic conditions and heavy sea-ice cover linked to a strong Polar Water component of the Inner Labrador Current. In the later part of the Younger Dryas (12.3-11.5 kyr BP) the influence of the Labrador Current (LC) became less pronounced resulting in more unstable conditions with varying sea-ice cover and increased influence of Gulf Stream water, presumably linked to an increased strength of the Atlantic Meridional Overturning Circulation (AMOC). The earliest Holocene (11.5-10.4 kyr BP) saw slightly warmer subsurface conditions in Placentia Bay and increased productivity, presumably caused by a decreased southward transport of Polar Water via the LC. The onset of a strong AMOC caused the northward movement of the frontal zone between the Subpolar Gyre and the North Atlantic Subtropical Gyre in the western North Atlantic region to closer proximity to the southern coast of Newfoundland compared to previously. From ca. 10.4-9.65 kyr BP increased bottom-current speeds and the presence of species often found in connection to oceanic fronts, suggest a further strengthening of the AMOC causing inflow of Atlantic-source water into Placentia Bay. This tendency was further strengthened at 9.65-7.3 kyr BP, which saw a relatively strong inflow of Atlantic-source Gulf Stream water into Placentia Bay, evidenced by high frequencies of Cassidulina neoteretis. This inflow of Atlantic was however temporarily halted around 8.2 kyr BP, when a short-lived, extreme peak in

  7. Sediment magnetism constraints on the age and paleoclimate implications of a Holocene lacustrine record from the headwater region of the Rio Claro, Elqui Valley, Regíon de Coquimbo, Chile

    Science.gov (United States)

    Tiner, R.; Negrini, R. M.; Antinao, J. L.; Maldonado, A.; Bobbitt, M.; Casas, K.; Kayser, M.

    2015-12-01

    Magnetostratigraphy and paleolimnological proxies are reported for a Holocene lake sediment record from the headwater region of the Rio Claro of the Elqui Valley in Northern Chile. Laguna Cerritos Blancos (LCB), the lake cored, is located at approximately 30° S latitude and 3844 m asl. This lake is fed by a stream that cut through a terminal moraine and is damned by an older moraine/rock glacier complex. This site sits at the boundary between important circulation features of the southern hemisphere, including the Southeast Pacific Subtropical Anticyclone and the Westerly winds. Any major movements of these circulation features should be reflected in the climate record of the study area (Garreaud, 2009). The Natural Remanent Magnetization (NRM) recorded in the sediments exhibits demagnetization behavior dominated by a single component of magnetization and shows a paleomagnetic secular variation (PSV) signal similar to that of a marine core (ODP Leg 202, Site 1233) from offshore Valparaíso (Lund et al., 2006) suggesting that the 1.5 m of lake record represents the past ~5,000 years. The continuous nature of the PSV record and a lack of sedimentary features, indicating a lack of unconformities, suggests that the current low lake levels are anomalous for the late Holocene. However, gradually decreasing clay percent up section shows a coarsening upward trend suggesting gradual shallowing of the lake over the past ~5,000 yrs. Over this time period LCB has been characterized by stable conditions and gradual shallowing with few disruptions to this trend. These initial paleoclimate hypotheses are currently being tested with the acquisition of additional paleoclimate proxies on these core sediments including C/N ratios, total inorganic carbon, palynology, and additional measurements of sediment magnetism.

  8. 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.

    ). This is consistent with the important role that climate has on the present-day erosion over the Himalaya, with most of sediments delivered to the BoB by rivers during the southwest monsoon (Islam et al., 1999; Goodbred, 2003). In contrast, some of the studies...-178. http://www.gemswater.org/atlas-gwq/table3-e.html Islam, M. R., Begum, S. F., Yamaguchi, Y. and Ogawa, K. (1999) The Ganges and Brahmaputra rivers in Bangladesh: Basin denudation and sedimentation, Hydrol. Proc., 13, 2907-2923. Kessarkar, P. M...

  9. 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.

  10. Corroded planktic foraminifer (Globorotalia menardii) in the southern Bay of Bengal sediment trap sample of February 1992

    Digital Repository Service at National Institute of Oceanography (India)

    Mohan, R.; Guptha, M.V.S.

    Press, New York and London, pp. 269-294. HONJO, S., MANGANINI, S.J. and COLE, J.J. (1982) Sedimentation of biogenic matter in the deep sea. Deep Sea Res., v. 29, pp. 609- 625. KOLLA, V., HENDERSON, L. and BISCAYE, P.E. (1976) Clay mineralogy...

  11. 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.

    ). Researches based on sediment flux and their chemical and isotopic properties have demonstrated that the ongoing physical erosion in these river basins is by and large regulated by climate (rainfall) over millennium time scale (Islam et al., 1999; Singh... method of Bhushan et al., (2001), whereas carbonate content were determined using a CO2 Coulometer (Model 5012, UIC Inc., Illinois, USA). Organic carbon was taken as difference between measured total carbon and inorganic carbon concentrations. A few...

  12. Distribution of natural radionuclide concentrations in sediment samples in Didim and Izmir Bay (Aegean Sea-Turkey).

    Science.gov (United States)

    Aközcan, S

    2012-10-01

    Natural and artificial radionuclide pollutants of the marine environment have been recognized as a serious environmental concern. The natural radioactivity activity concentrations of (226)Ra, (238)U, (232)Th and (40)K were measured by gamma spectrometry in sediment samples collected from two different areas in Aegean Sea Turkish Coast. There is no information about radioactivity level in the study areas sediments so far. The results showed that the concentrations of activity in the sediment samples are 9 ± 0.6 Bq kg(-1)-12 ± 0.7 Bq kg(-1), 7 ± 0.4 Bq kg(-1)-16 ± 1.0 Bq kg(-1), 6 ± 0.3 Bq kg(-1)-16 ± 1.0 Bq kg(-1) and 250 ± 13 Bq kg(-1)-665 ± 33 Bq kg(-1) for (226)Ra, (238)U, (232)Th and (40)K, respectively. In general, the distribution of activity concentrations along the coast of the Aegean Sea area were in the same order as international levels.

  13. 大连湾石油污染沉积物中细菌群落结构分析%Bacterial communities in Dalian Bay petroleum pollution sediments

    Institute of Scientific and Technical Information of China (English)

    高小玉; 明红霞; 陈佳莹; 李江宇; 韩俊丽; 林凤翱; 樊景凤

    2014-01-01

    大连新港“7.16”输油管道爆炸溢油事故发生后,为探究石油污染与细菌群落结构变化之间的关系及在石油生物降解过程中起重要作用的细菌菌群,本研究对大连湾表层沉积物中石油烃含量和细菌宏基因组16 S rDNA V3区进行分析。结果表明:溢油初期2010年8月DLW01站位表层沉积物石油烃含量高达1492 mg/kg,符合第三类沉积物质量标准,随着时间推移,2011年4月、2011年7月、2011年12月航次各站位沉积物中石油烃含量基本呈下降趋势,且均符合第一类沉积物质量标准;16S rDNA PCR-DGGE方法分析表明,石油烃含量高的区域优势细菌种类少,反之则较丰富;海洋环境中同一地点的细菌群落能保持一定稳定性;大连湾石油污染沉积物中变形菌门γ-变形菌纲和拟杆菌门一直保持较高的优势度,是在石油生物降解过程中起重要作用的细菌菌群,而厚壁菌门只在石油烃含量低的区域出现;此外,出现的对污染物敏感的嗜冷杆菌可作为石油污染指示生物进行深入研究。%In order to explore the connection between petroleum pollution and bacterial community structure change, the important dominant bacteria communities in the process of oil biodegradation,after the“7.1 6”pipeline explo-sion and oil spill accident happened in Dalian Xingang,the content of petroleum hydrocarbon and bacterial metage-nome were studied in Dalian Bay.Results showed that the petroleum hydrocarbon content in the surface sediment of DLW01 in August 2010 was 1 492 mg/kg ,according with the third standard of marine sediment quality.As time went on,the content of petroleum the presented basic downward thrend,and all conformed to the first stand-ard of marine sediment quality in April 2011,July 2011,December 2011.16S rDNA targeted PCR-DGGE results suggested that the dominant bacteria communities were monotonous in high petroleum hydrocarbons areas,while conversely rich in low oil

  14. Sediment Dynamics and the Burial and Exhumation of Bedrock Reefs as Elucidated by High-resolution Repetitive Sonar Surveys: Northern Monterey Bay, CA

    Science.gov (United States)

    Storlazzi, C. D.; Fregoso, T. A.; Golden, N. E.; Finlayson, D. P.

    2011-12-01

    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 bedrock reef habitats. The surveys extended from water depths of 4 m to 22 m and covered an area of 3.14 km2, of which 45.8% was bedrock, gravel, and coarse-grained sand and 54.2% was fine-grained sand. Our analysis 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 exposed 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 seabed slope and rugosity. Much of the detected change was at the boundary between bedrock and unconsolidated sediment due to burial or exhumation of bedrock. In a number of cases, however, the change in seabed character was apparently due to fluctuations in sediment grain size, where scour exposed what appeared to be an underlying coarser-grained lag or fine-grained sand buried coarser-grained sand. These findings suggest that, in some places, (a) single acoustic surveys typically employed for geologic characterization and/or habitat mapping may not adequately characterize the geomorphology and sedimentologic nature of rocky, energetic inner shelves, and (b) burial and exhumation likely play a role in the life history of the numerous organisms that inhabit these reefs and thus information on the frequency and magnitude of such processes may better constrain our understanding of physical controls on benthic species' distribution patterns.

  15. 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, Laura L.; Kelley, Joseph T.; Belknap, Daniel F.; Barnhardt, Walter A.; Andrews, Brian D.; Maynard, Melissa Landon

    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

  16. 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)

  17. 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

  18. Authigenic Gypsum in Gas-Hydrate Associated Sediments from the East Coast of India (Bay of Bengal)

    Digital Repository Service at National Institute of Oceanography (India)

    Kocherla, M.

    operation respectively. This is NIO contribution no… 10 4.0 References. Aharon, P., Graber, E. R. Roberts, H. H., 1992. Dissolved carbon and delta c-13 anomalies in the water column caused by hydrocarbon seeps on the northwestern Gulf of Mexico... hydrate. Geology, 24: 655–658. Botz, R., Faber, E., Whiticar, M, Brooks, J.M., 1988. Authigenic carbonates in sediments from the Gulf of Mexico. Earth and Planetary Science Letters, 88: 263-272. Bohrmann, G., Greinert, J., Suess, E., Torres, M., 1998...

  19. 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.

  20. An approximation to short-term evolution and sediment transport pathways along the littoral of Cadiz Bay (SW Spain)

    Science.gov (United States)

    Anfuso, G.; Benavente, J.; Del Río, L.; Gracia, F. J.

    2008-11-01

    This work presents the results of a beach-monitoring program carried out in the Bay of Cadiz (SW Spain), which consists of urban, natural and nourished beaches. In the present study, 24 topographic profiles have been monthly monitored during the 1996 1998 period, in order to draw the morphodynamic behavior of this coast and the general characterization of short-term coastal trends. This way, total volumetric budgets have been calculated for each beach profile in order to group beaches in different erosive/accreting sectors. Studied beaches recorded both erosion and accretion: the greatest accretionary trends have been observed at Aguadulce, La Costilla and Rota beaches, with values ranging from 30 to 70 m3/m. The largest erosion episodes have been recorded in the southernmost end of Valdelagrana spit, with values over 50 m3/m, and in Rota and Vistahermosa, after nourishment works. Main erosion and accretion pathways have been related to the existence of natural and human structures, which blocked the longshore drift suggesting the existence of littoral cells.

  1. Pollution characteristics and ecological risk assessment of HCHs and DDTs in estuary wetland sediments from the Bohai Bay, North China.

    Science.gov (United States)

    Liu, Qing; Tian, Shengyan; Jia, Rui; Liu, Xianbin

    2015-12-09

    Hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) tend to persist in the environment for long periods of time. The concentration and distribution of HCHs and DDTs were investigated in surface sediments of Yongdingxinhe wetland and Binhai wetland by gas chromatography-mass spectrometer (GC-MS). All isomers of HCHs and DDTs were detected in all of the samples. The concentrations of total HCHs (ΣHCHs) in two wetland sediments ranged from 69.81 to 379.28 ng · g (-1), with a mean value of 224.55 ng · g (-1). The concentrations of total DDTs (ΣDDTs) ranged from 98.32 to 129.10 ng · g (-1), with a mean value of 113.71 ng · g (-1). The results of an ecological risk assessment demonstrated that there was high-risk ecological effect of organochlorine pesticides (OCPs) on the estuary wetlands. Lindane and technical DDTs were found to be the main sources of OCPs.

  2. 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.

  3. Retrospective analysis by data processing tools for comprehensive two-dimensional gas chromatography coupled to high resolution time-of-flight mass spectrometry: a challenge for matrix-rich sediment core sample from Tokyo Bay.

    Science.gov (United States)

    Zushi, Yasuyuki; Hashimoto, Shunji; Tamada, Masafumi; Masunaga, Shigeki; Kanai, Yutaka; Tanabe, Kiyoshi

    2014-04-18

    Data processing tools for non-target analysis using comprehensive two-dimensional gas chromatography coupled with high-resolution time-of-flight mass spectrometry (GC×GC-HRTOFMS) were developed and applied to a sediment core in Tokyo Bay, focusing on chlorinated compounds in this study. The processing tools were classified in two different methods: (1) the consecutive use of mass defect filter followed by artificial neutral loss scan (MDF/artificial NLS) as a qualitative non-target screening method and (2) Entire Domain Combined Spectra Extraction and Integration Program (ComSpec) and two-dimensional peak sentinel (T-SEN) as a semi-quantitative target screening method. MDF/artificial NLS as a non-target screening approach revealed that PCBs, followed by octachlorodibenzo dioxin (OCDD), were the main chlorinated compounds present in all sediment layers. Furthermore, unknown peaks thought to be chlorinated compounds were found in increasing numbers, some in increasing amounts. T-SEN and ComSpec as a target screening approach were adapted for automatic semi-quantitative analysis showed that, in decreasing concentration order, PCBs, OCDD, and dichlorodiphenyltrichloroethane and its metabolites (DDEs, DDDs) were the main chlorinated pollutants in the sediments. The complementary use of both techniques allows us to extract significant chlorinated pollutants, including non-targeted compounds. This retrospective analysis by this approach performed well even on matrix-rich sediment samples and provided us an interesting insight of historical trends of pollution in Tokyo Bay.

  4. Fluvial response to sudden input of pyroclastic sediments during the 2008-2009 eruption of the Chaitén Volcano (Chile): The role of logjams

    Science.gov (United States)

    Umazano, Aldo M.; Melchor, Ricardo N.; Bedatou, Emilio; Bellosi, Eduardo S.; Krause, Javier M.

    2014-10-01

    The rhyolitic Plinian eruption of the Chilean Chaitén Volcano, initiated on May 2, 2008, suddenly introduced abundant pyroclastic sediments in the Blanco River catchment area, which experienced important modifications. Before May 2, the river was characterised by gravelly and moderate to low-sinuosity channels crossing a vegetated and locally urbanised (Chaitén City) floodplain. This river, limited by steep and densely forested highlands, was connected with the Pacific Ocean via a tidally-influenced delta plain. After heavy rains in May 11-20, the river discharge increased and triggered several responses including logjam formation and breakage, crevassing, avulsion (and channel abandonment), changes in the pattern and dimensions of channels, and construction of a new delta plain area. In this context, the goals of this contribution were: i) to document the sedimentological processes within a detailed geomorphic framework and ii) to understand the influence of logjams on fluvial dynamics. Upstream of the logjam zone, the deposits are mostly composed of ash and lapilli with abundant palaeovolcanic (epiclastic) sediments, which were produced by dilute currents and debris flows. Downstream of the logjam zone, deposits are composed by ash and lapilli, both pumice-rich and lacking important participation of older (epiclastic) sediments. The abandoned and filled palaeochannel, and the proximal part of crevasse splays experienced transient dilute flows with variable sediment concentration and, subordinately, hyperconcentrated flows. The distal sectors of crevasse splays mostly record settling from suspension. At the delta plain, tephra transported by the Blanco River was mixed with older sediments by tide and wave action (dilute flows). We conclude that immediately after eruption, both geomorphic and sedimentary processes of the river were mainly controlled by a combination of high availability of incoherent pyroclastic sediments on steep slopes, abundant rains, large

  5. 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 toareas. Due to hydrodynamic forcing (wave climate and tidal currents), about 50% (MABIO) and 75% (MASED) of the volume of dredged material remained at the end

  6. The combined impact of land use change and aquaculture on sediment and water quality in oligotrophic Lake Rupanco (North Patagonia, Chile, 40.8°S).

    Science.gov (United States)

    León-Muñoz, Jorge; Echeverría, Cristian; Marcé, Rafael; Riss, Wolfgang; Sherman, Bradford; Iriarte, Jose Luis

    2013-10-15

    Water and sediment quality in North Patagonia's large, oligotrophic lakes are expected to suffer as native forest continues to be fragmented and degraded by its conversion to cropping and pasture land uses. These changes in land use are expected to increase diffuse nutrient loads to the region's lakes. In addition, these lakes are home to the world's second largest salmon aquaculture industry which provides additional point sources of nutrients within the lakes. We studied the combined influences of land use change and salmon farming on the nutrient concentrations in a North Patagonian lake (Lake Rupanco, 233 km(2) water surface, 163 m average depth) in four sub-watersheds ranging in disturbance from near-pristine forest to 53% converted to cropping and pasture. Nitrogen exports from the tributary sub-watersheds increased from 33 kg TN/km(2)/y to 621 kg TN/km(2)/y as the proportion of crop and pasture land increased. The combined nutrient load from land use change and salmon farming has led to significant differences in the nitrogen concentrations of the lake's water column and sediments in the near-shore zones across the lake. Total nitrogen concentrations in the sediments varied from 37 ± 18 mg/kg in near-pristine sub-watersheds without salmon farming to 6400 ± 698 mg/kg where the sub-watershed was dominated by crop and pasture lands combined with the presence of salmon farming. These results demonstrate the importance of considering the impacts of both salmon farming and land use on water and sediment quality for future environmental planning, management and decision making.

  7. 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.

  8. A multivariate analytical method to characterize sediment attributes from high-frequency acoustic backscatter and ground-truthing data (Jade Bay, German North Sea coast)

    Science.gov (United States)

    Biondo, Manuela; Bartholomä, Alexander

    2017-04-01

    One of the burning issues on the topic of acoustic seabed classification is the lack of solid, repeatable, statistical procedures that can support the verification of acoustic variability in relation to seabed properties. Acoustic sediment classification schemes often lead to biased and subjective interpretation, as they ultimately aim at an oversimplified categorization of the seabed based on conventionally defined sediment types. However, grain size variability alone cannot be accounted for acoustic diversity, which will be ultimately affected by multiple physical processes, scale of heterogeneity, instrument settings, data quality, image processing and segmentation performances. Understanding and assessing the weight of all of these factors on backscatter is a difficult task, due to the spatially limited and fragmentary knowledge of the seabed from of direct observations (e.g. grab samples, cores, videos). In particular, large-scale mapping requires an enormous availability of ground-truthing data that is often obtained from heterogeneous and multidisciplinary sources, resulting into a further chance of misclassification. Independently from all of these limitations, acoustic segments still contain signals for seabed changes that, if appropriate procedures are established, can be translated into meaningful knowledge. In this study we design a simple, repeatable method, based on multivariate procedures, with the scope to classify a 100 km2, high-frequency (450 kHz) sidescan sonar mosaic acquired in the year 2012 in the shallow upper-mesotidal inlet of the Jade Bay (German North Sea coast). The tool used for the automated classification of the backscatter mosaic is the QTC SWATHVIEWTMsoftware. The ground-truthing database included grab sample data from multiple sources (2009-2011). The method was designed to extrapolate quantitative descriptors for acoustic backscatter and model their spatial changes in relation to grain size distribution and morphology. The

  9. 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.

  10. Microbial diversity of mangrove sediment in Shenzhen Bay and gene cloning, characterization of an isolated phytase-producing strain of SPC09 B. cereus.

    Science.gov (United States)

    Zhang, Shengpeng; Liao, Shao-An; Yu, Xiaoyuan; Lu, Hongwu; Xian, Jian-An; Guo, Hui; Wang, Anli; Xie, Jian

    2015-06-01

    Phytases hydrolyze phytate to release inorganic phosphate, which decreases the requirement for phosphorus in fertilizers for crops and thus reduces environmental pollutants. This study analyzed microbial communities in rhizosphere sediment, collected in September 2012 from Shenzhen Bay, Guangdong, China, using high-throughput pyrosequencing; the results showed that the dominant taxonomic phyla were Chloroflexi, Firmicutes, and Proteobacteria, and the proportion of the beneficial bacteria, Bacillus, was 4.95 %. Twenty-nine culturable, phytase-producing bacteria were isolated, their phosphorus solubilization capacity was analyzed, and they were taxonomically characterized. Their phylogenetic placement was determined using 16S ribosomal RNA (rRNA) gene sequence analysis. The result shows that most of the isolates are members of the order Bacillales, although seven strains of Enterobacteriales, two strains of Pseudomonadales, and one strain of Oceanospirillales were also identified. The phytase gene was cloned from SPC09, Bacillus cereus, which showed the highest phosphorus solubilizing ability among the isolated strains. The gene encoded a primary translation product of 335 amino acids. A construct including the 1005-nt ORF fragment, Bc-phy, was transformed into Escherichia coli. The recombinant phytase was produced and purified, which revealed the temperature optima at 60 °C and pH optima at 6.5. The assessment by quantitative PCR (qPCR) showed an abundance of bacteria containing the Bc-phy gene; the level was generally higher in the mangrove forest than in the tidal flats and in surface soil compared to bottom soil, and the highest value was obtained in June. Herein, we report on the cloning, characterization, and activity of a novel phytase isolated from a mangrove system.

  11. Distribution characteristics of sterols in surface sediment of Dalian Bay%大连湾表层沉积物中甾醇的分布特征

    Institute of Scientific and Technical Information of China (English)

    冀平; 赵元凤; 徐恒振; 王洪艳; 姚子伟; 马新东

    2013-01-01

    11 sterols in the surface sediment samples in Dalian Bay were determined by GC/MS,and the distribution characteristics at 17 stations in this area were discussed.The results show that the total concentration range was (0 ~ 6.833) × 10-6,the sterols range was (1.627 ~34.617) × 10-6.The distribution appeared that the concentration of total sterols around the sewage ouffall was higher than that far away from the outfall.The main kinds of sterols were C27 sterols and C29 sterols and the source of sterols was a large number of domestic sewage.%采用气相色谱/质谱对大连湾表层沉积物中11种甾醇进行了监测,探讨了大连湾17个站位的表层沉积物中甾醇的分布特征.结果表明,大连湾17个站位的表层沉积物中11种甾醇的含量范围为1.627×10-6~34.617×10-6;甾醇分布呈现出近岸区高于离岸海区,近排污口区高于远排污口区的态势;甾醇种类主要为C27甾醇和C29甾醇;其来源主要是大量生活污水的输入.

  12. Carbon and nitrogen isotopes analysis and sources of organic matter in surface sediments from the Sanggou Bay and its adjacent areas, China

    Institute of Scientific and Technical Information of China (English)

    XIA Bin; CUI Yi; CHEN Bijuan; CUI Zhengguo; QU Keming; MA Feifei

    2014-01-01

    Naturally existing stable carbon and nitrogen isotopes are important in the study of sedimentary organic matter sources. To identify the sources of sedimentary organic matter in Sanggou Bay and its adjacent areas, which is characterized by high-density shellfish and seaweed aquaculture, the grain size, organic carbon (OC), total nitrogen (TN), carbon and nitrogen isotopic composition (δ13C andδ15N) of organic matter in the surface sediment were determined. The results showed that, in August, sedimentary OC and TN ranged from 0.17% to 0.76% and 0.04% to 0.14%, respectively. In November, OC and TN ranged from 0.23% to 0.87% and 0.05% to 0.14%, respectively. There was a significant positive correlation between OC and TN (R=0.98, P<0.0001), indicating that OC and TN were homologous. In August, theδ13C andδ15N of organic matter varied from −23.06‰ to −21.59‰ and 5.10‰ to 6.31‰, respectively. In November,δ13C andδ15N ranged from −22.87‰ to −21.34‰ and 5.13‰ to 7.31‰, respectively. This study found that the major sources of sedimentary organic matter were marine shellfish biodeposition, seaweed farming, and soil organic matter. Using a three-end-member mixed model, we estimated that the dominant source of sedimentary organic matter was shellfish biodeposition, with an average contribution rate of 65.53% in August and 43.00% in November. Thus, shellfish farming had a significant influence on the coastal carbon cycle.

  13. 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.

    2016-01-13

    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

  14. 渤海湾西部表层沉积物粒度及黏土矿物特征分析%The sediment grain size characteristics and analysis of sources in the western Bohai Bay

    Institute of Scientific and Technical Information of China (English)

    冯秀丽; 魏飞; 刘杰; 刘潇; 徐芳

    2015-01-01

    对渤海湾西部海域和西岸入海河流中76个表层沉积物样品进行粒度及黏土矿物分析,研究表明该区有3种沉积物类型,黏土质粉砂分布于整个研究区,约占表层样的90%,是研究区最主要的沉积物类型;研究区黏土矿物以伊利石为主,黏土矿物组合为伊利石-高岭石-绿泥石-蒙皂石;渤海湾西部表层沉积物主要来源于海河等渤海湾西岸入海河流中的陆源碎屑物,滦河对研究区基本没有影响,黄河对研究区的影响变得比较小。对于研究渤海湾西岸的沉积特征及沉积物物源、了解陆地河流对于研究区海洋沉积环境的影响有着一定的科学意义。%This paper shows that there are 3 types of sediments in the study area according to analysis of 76 surface samples which were sampled from the western Bohai Bay waters and rivers that flow into the sea from the west coast. Clayey silt distributes throughout the study area, and is the most important type of sediments in the study area, accounting for about 90% of the surface samples. The sediment dynamic environmental characteristics of the sur-face sediments in the area were studied using the Flemming triangle graphic method and the results indicate that the sedimentary dynamics in the study area was relatively weak. The clay mineral analysis of 60 surface samples shows that the illite is the main clay mineral, and the clay mineral assemblage in the study area is illite - kaolinite - chlorite - smectite stone. The exploration of sediment source based on grain size and clay minerals shows that the surface sediments of the western Bohai Bay were mainly from the terrigenous detritus, which were carried by the rivers flowing into the sea in the western Bohai coast, such as the Haihe River, while the Luanhe River had nearly no effect on the surface sediments in the study. The influence of the Yellow River on the sea surface sediments was weak.

  15. Imposex and butyltin contamination still evident in Chile after TBT global ban.

    Science.gov (United States)

    Batista, Rodrigo Moço; Castro, Italo Braga; Fillmann, Gilberto

    2016-10-01

    Imposex in gastropods (Acanthina monodon, Oliva peruviana and Xanthochorus cassidiformis), butyltin levels in surface sediments (Coquimbo and Concepcion) and tissues (Valparaiso and Concepcion) were assessed in three areas under the influence of maritime activities along the central Chilean coast. The highest TBT concentrations were observed in São Vicente Bay (Concepcion), reaching 122.3ngSng(-1) in surface sediments and 59.7ngSng(-1) in gastropods tissue, while in Valparaiso ranged from 7.4 to 15.8ngSng(-1) in biota. The lowest TBT concentrations were detected in sediments from Coquimbo (TBT free products) in association to local oceanographic conditions. Despite DBT and MBT were the predominant analytes, recent inputs of TBT were evident in some areas. In fact, fishing boats may be a relevant source since they were the predominant maritime activity in the most contaminated sites. In addition, the absence of significant differences within BTs levels between both genders of A. monodon suggests that tissues from distinct sexes can be indistinctly used for future contamination studies. Imposex incidence was detected in 11 out of 15 sampled sites, indicating that environmental levels of TBT have been sufficient to induce deleterious effects on the exposed organisms. Thus, the impacts caused by TBT in Chilean coastal areas were detectable and consistent with other studies performed in South America. This present environmental contamination is probably due to the lack of regulations forbidding the use of TBT-based antifouling paints in Chile.

  16. 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

  17. The effect of freshwater inflow on meiofaunal consumption of sediment bacteria and microphytobenthos in San Antonio Bay, Texas, U.S.A.

    Science.gov (United States)

    Montagna, Paul A.; Yoon, Won Bae

    1991-12-01

    If meiofauna are food-limited then they should respond with increased feeding rates when microbial production is stimulated. River inflow into estuaries is a source of organic matter that can be limiting to bacterial production, and nutrients that might limit primary production. Therefore, inflow should stimulate microbial primary and secondary production, and eventually meiofauna grazing rates should increase as a functional response to increased food availability and quality. To determine if meiofauna grazing rates were affected by inflow, two replicate stations were sampled in the upper, river-dominated end, of San Antonio Bay and contrasted with two replicate stations at the lower end of the estuary. The experiments were performed three times. Water column nutrients and sediment organic matter were higher in the upper end of the estuary than in the lower end. Benthic primary production was 2·5 times higher in the upper end than in the lower end. Benthic metabolism (measured by oxygen consumption) was also higher in the upper end, but bacterial production (measured by thymidine uptake) was not significantly different between the two ends. Grazing rates were 3·5 times higher on bacteria, and 2·5 times higher on microalgae in the upper end of the estuary than in the lower end, confirming our hypothesis that inflow would stimulate grazing rates. Grazing rates were dominated by juvenile molluscs (temporary meiofauna) which accounted for 39% of the microalgae and 68% of the bacteria ingested by the community. Juvenile molluscs were most prevalent in the upper, fresh-water zone. Harpacticoid copepods and nematodes had higher grazing rates in the lower end of the estuary. Grazing rates were higher on microalgae than on bacteria: 4% of the microalgae were removed per hour, compared to only 1% of the bacteria. Grazing rates on microalgae were 2·6 times higher than productivity, indicating meiofauna might be food-limited. Grazing on bacteria was low, and production

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. Characterastics of Surface Sediments Diatom Distribution in Zhenzhu Bay of Guangxi%广西珍珠湾表层沉积硅藻分布特征

    Institute of Scientific and Technical Information of China (English)

    黄玥; 黄元辉

    2016-01-01

    Sixteen surface sediments diatoms were studied from Zhenzhu Bay of Guangxi.A total of 131 species belonging to 44 genera was identified of which Cocconeis disculus got the highest abundance.The results of mutianalysis indicated that the diatom assemblage was mainly affected by sea-surface salinity. Achnanthes spp.(mainly consists of A.delicatula ,A.fugei ,A.hauckiana and A.levanderi),Amphora spp.(mainly includes A.delicatissima ,A.exigua ,A.eximia ,A.holsatica and A.normanii )and Nitzschia ovalis were being the good indicators of low sea-surface salinity,Cocconeis disculus was always found in the brackish areas,while Cyclotella striata/C.stylorum,Thalassiosira spp.(mainly consists of T .eccentrica ,T .leptopus and T .oestrupii )and Thalassionema nitzschioides could be used as index for high sea-surface salinity.The surface diatom assemblage was rarely influenced by the fresh water on land. Whereas,the abundance of fresh water diatoms along the shore was mainly affected by the human activi-ties.Sixteen surface sediments diatoms could be divided into three diatom zones,corresponding to the dif-ferent sea-surface salinity which closely mapped to their actual regional distribution.%在广西珍珠湾16个表层沉积物站位取样并对其中硅藻进行分析,鉴定出硅藻131种,分属44属。其中Cocconeis disculus 是研究区域内数量最多的硅藻种类。多元分析结果表明,珍珠湾沉积硅藻分布主要受到海水盐度的控制,其中 Achnanthes spp.(主要包括 A.delicatula,A.fugei,A.hauckiana 和 A .levanderi),Amphora spp.(主要包括 A.delicatissima,A.exigua,A.eximia,A.holsatica 和A .normanii)和 Nitzschia ovalis 可以作为低盐度海水环境的指示种;Cocconeis disculus 多集中分布于海水盐度适中的海域;Cyclotella striata/C.stylorum, Thalassiosira spp.(主要包括 T.eccentrica,T.leptopus 和 T .oestrupii)和 Thalassionema nitzschioides 则可以很好地指示高盐度环境。陆上淡水河流对珍珠湾表层

  3. Historical environmental pollution trend and ecological risk assessment of trace metals in marine sediments off Adyar estuary, Bay of Bengal, India.

    Digital Repository Service at National Institute of Oceanography (India)

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

    .07. Based on AF, PLI, and sediment quality guidelines values for trace metals, significant metal enrichment and ecological risk were obtained in upper-most sediment layer. Multivariate statistical methods such as correlation matrix, principal component...

  4. Mercury distribution and speciation in the sediments of mangrove wetland in Quanzhou Bay%泉州湾红树林湿地沉积物中汞分布及形态特征

    Institute of Scientific and Technical Information of China (English)

    于瑞莲; 胡恭任; 刘越; 杨翼

    2011-01-01

    采集了泉州湾红树林湿地表层沉积物样品,测定了沉积物中不同形态汞的含量,研究了汞的分布特征、赋存形态及其生物有效性.泉州湾红树林湿地表层沉积物中总汞含量范围0.03~0.22 mg·kg-1,除14#采样点外,其余各采样点均符合海洋沉积物质量(GB 18668-2002) Ⅰ类标准;沉积物中不同形态汞占总汞的比例为可氧化态(84.0%)>残渣态(14.0%)>可还原态(1.8%)>弱酸溶态(0.2%);沉积物中汞的生物有效性较高,对红树林生态系统存在一定的潜在危害.%Surface sediments were sampled from the mangrove wetland in Quanzhou Bay to study the distribution, speciation, and bio-availability of mercury in the sediments. The total mercury content in the sediments ranged in 0. 03-0. 22 mg · kg-1, which met the first class standard of Marine Sediment Quality ( GB 18668-2002) , with the exception of that at site 14. The average proportion of different speciation mercury to total mercury in the sediments presented a sequence of oxidizable ( 84. 0% ) > residual ( 14. 0% ) > reducible ( 1. 8% ) > weak acid soluble ( 0. 2% ) . The relatively high bio-availability of mercury in the sediments indicated certain potential hazard to the mangrove ecosystem.

  5. Sediment Grain-size Data from sediment grab samples and box cores collected in May 2014 from Barnegat Bay, New Jersey (U.S. Geological Survey Field Activity Numbers 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...

  6. Chile: Its Conventional Threats

    Science.gov (United States)

    2005-03-18

    Bolivia’s gas to Mexico and North America. Chile’s President Lagos likewise invited Bolivia to construct a plant in Chile to facilitate gas production at...tdf.htm>. Internet. Accessed 30 October 2004. 20 21 BIBLIOGRAPHY Barros, Van Buren Mario. Historia Diplomatica de Chile . Santiago: Editorial Andres

  7. Living (stained calcareous benthic foraminifera from recent sediments off Concepción, central-southern Chile (~36° S Foraminíferos bentónicos calcáreos vivos (teñidos en sedimentos recientes de Concepción, Chile centro-sur (~36° S

    Directory of Open Access Journals (Sweden)

    RAÚL TAPIA

    2008-09-01

    Full Text Available This study examines onshore-offshore and vertical distribution of living (Rose Bengal stained benthic foraminifera (> 180 μm fraction from three sediment stations along a bathymetric transect off Concepción, Chile (station 18 = 88 m water depth, station 26 = 120 m, station 40 = 1,030 m, within and below the oxygen minimum zone. All cores were collected in austral winter. Calcareous foraminifera dominated the three stations. The species composition, living foraminifera density, and vertical distribution patterns within the sediment changed in accordance with bottom water dissolved oxygen concentration and food availability. Onshore-offshore pattern revealed overall highest living foraminiferal densities at shelf stations 18 and 26 where bottom water dissolved oxygen was lowest (~ 0.2 mL-1 and content in labile organic matter highest. Within the sediment, maximum relative abundances (50-60 % of living organisms were found in the 0-1 cm interval at the organic-rich and oxygen-poor shelf stations 18 and 26. In the well-oxygenated (2.7 mL-1 slope station 40, 70 % of living foraminifera were observed deeper than the first centimeter. The number of species and the contribution of the > 250 μm fraction to the total fauna larger than 180 μm increased offshore. Nonionella auris (d'Orbigny dominated at stations 18 and 26 while a more diverse foraminifera fauna was found at station 40. This study provides the first quantitative data on living benthic foraminifera in the area; seasonal and interannual changes are not addressed.Este estudio examina la distribución costa-océano y vertical de los foraminíferos bentónicos calcáreos (fracción > 180 im vivos (teñidos en tres estaciones a lo largo de un transecto batimétrico frente al área de Concepción, Chile (estación 18 = 88 m, estación 26 = 120 m, estación 40 = 1.030 m de profundidad, dentro y bajo la zona mínima de oxígeno. Todos los testigos de sedimento fueron recolectados durante el per

  8. 大连湾沉积物-水界面BAP交换通量的影响因素%The influencing factors of BAP exchange flux at the sediment-water interface in Dalian Bay

    Institute of Scientific and Technical Information of China (English)

    宗虎民; 张志锋; 王燕; 张哲

    2012-01-01

    The influencing factors of BAP (bio-available phosphorus) exchange flux at the sediment-water interface in Dalian Bay were studied by laboratory incubation experiment, and the BAP fluxes between sediment and water in the dredged area and in the area near the sediment dredging location were analyzed with the methods of laboratory incubation experiment and nutrient concentration gradients in the pore water. The results showed that the fluxes of BAP from sediment to water increased with the increase of pH and temperature in overlying water, and it also increased by the condition of applying sterilized sediment and aerating in overlying water during the incubation experiment. The fluxes from sediment to water decreased when the concentrations of phosphorus increased in the overlying water, and the flux direction reversed with the continuous increase of the concentrations. Both results of the two methods showed that the annual average exchange flux of BAP between sediment and water in the area near the sediment dredging location was higher than that in dredged area affected by dredging works. The exchange fluxes of BAP between sediment and water in Dalian Bay were different in four seasons, which was highest in summer and lowest in winter. However, it was at a high level in the area near the sediment dredging location in winter due to the impact of dredging.%利用实验室培养法研究了不同因素对大连湾沉积物-水界面间生物可利用磷(BAP)交换通量的影响,并利用实验室培养法和间隙水浓度梯度法估算了大连湾已疏浚区和疏浚点邻近海域沉积物-水界面BAP的交换通量.结果表明,随着上覆水pH和温度的增加,BAP由沉积物向水体释放量逐渐增加;灭菌和贫氧条件下,也会导致沉积物BAP的释放量增加;上覆水中磷酸盐浓度的升高会导致BAP由沉积物向水体释放通量降低,且随着上覆水磷酸盐浓度的不断升高,BAP逐渐转化为由水体向沉积物中扩散.

  9. Historical methyl mercury in San Francisco Bay

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — San Francisco Bay, California is considered a mercury-impaired watershed. Elevated concentrations of mercury are found in water and sediment as well as fish and...

  10. Contents analysis of arsenic and heavy metals in seawater and sediment in Meizhou Bay%湄洲湾水域海水、沉积物中砷及重金属的含量分析

    Institute of Scientific and Technical Information of China (English)

    席英玉; 杨妙峰

    2011-01-01

    根据湄洲湾20个点位4批次水样,1次沉积物样,用原子荧光、原子吸收和多功能极谱仪测定海水和沉积物中砷及重金属的含量。采用单因子污染指数法和内梅罗综合污染指数法对湄洲湾水域海水和沉积物中的砷及重金属进行综合评价。结果表明,湄洲湾水域海水中的砷及重金属单因子污染指数Pi〈1,均符合第二类海水水质标准,内梅罗指数I〈1,总体处于清洁水平,质量状况良好。沉积物中的砷及重金属单因子污染指数Pi〈1,均符合第一类海洋沉积物质量标准,内梅罗指数I〈1,一总体处于清洁水平,质量状况良好。简要分析了湄洲湾水域海水、沉积物中砷及重金属分布特征、季节变化情况。%To investigate into the water pollution caused by arsenic and heavy metal in Meizhou Bay, Fujian China, 4 batches of water samples and I batches of sediment from 20 sites are collected and the contents of As, Hg, Cu, Pb, Zn, Cd are meas- ured with the application of atomic fluorescence spectrophotometer and atomic absorption spectrometry and Multi - functional Po- larograph method. The results show that Meizhou Bay waters and sediments of arsenic and heavy metals are in good condition. We also analyze the distribution, seasonal variation and pollution of arsenic and heavy metals in water and sediment in the Meizhou Bay.

  11. 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.

    fractions from shallow depth (less than 5 m) during the SW monsoon and deposition in deeper depths (more than 10 m) during post-monsoon. It is further inferred that the E-W trending depression in the central part of the Bay partially controls the sand...

  12. Long-Term Oceanographic Monitoring in Massachusetts Bay (1989-2006) for Assessment of the Transport and Fate of Sediments and Associated Contaminants.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Long-term oceanographic observations made in western Massachusetts Bay at long-term site LT-A (42 degrees 22.6 minutes N., 70 degrees 47.0 minutes W.; nominal water...

  13. Foraminifera and paleoenvironment of the Plio-Pleistocene Kallithea Bay section, Rhodes, Greece: Evidence for cyclic sedimentation and shallow-water sapropels

    DEFF Research Database (Denmark)

    Rasmussen, Tine Lander; Thomsen, Erik

    2005-01-01

    Nearly 250 species of benthic foraminifera have been identified from the Plio-Pleistocene strata of the Kallithea Bay section on the eastern coast of Rhodes. The section comprises an overall transgressive succession ranging from fluviatile and brackish-water gravel at the base to fine-grained dee...

  14. Sediment Pore Water Ammonium and Phosphate Concentrations in Choctawhatchee Bay as?Determined by the Diffusive Equilibration in Thin Films (DET) Technique

    Science.gov (United States)

    Choctawhatchee Bay (CB) is a large estuarine ecosystem in northwest Florida that provides quality of life and economic benefits to local residents. The CB watershed is largely forested, but with significant agriculture in its northern part and intense residential and commercial ...

  15. Geotechnical and Geoacoustic Properties of Sediments Off South Florida: Boca Raton, Indian River Beach, Lower Tampa Bay, and the Lower Florida Keys

    Science.gov (United States)

    1997-06-24

    from one to two meters (U.S. Department of Commerce, 1995). Holocene sediment thicknesses average 2.5 to 4.5 m. The Holocene sediments overlie the Key...Perry Murexflorifer dilectus A Adams It lives in a wide variety of habitats from mangrove , muddy areas to protected rocks and frequently in clear, sandy

  16. Stronger Ties With Chile

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Chile was the first South American country to establish diplomatic relations with China. It was also the first Latin American country to support China’s entry into the WTO,recognize China’s full market

  17. Dinoflagellate Cysts Records from Core Samples of Modern Marine Sediment at the Luoyuan Bay Mouth%罗源湾口柱状沉积物中的甲藻孢囊

    Institute of Scientific and Technical Information of China (English)

    孙爱梅; 李超; 蓝东兆; 祝跃

    2007-01-01

    Thirty species of dinoflagellate cysts in 15 genus are identified from KMZK5 Core samples of recent marine sediment at the Luoyuan Bay mouth, Fujian. All of these dinoflagellate cysts are first recorded in the Luyuan Bay, 12 species of them are not distributing in the near sea area such as Sansha Bay and Minjiang estuary, including 6 kinds of toxic species, such as Alexandrium affine,A. minutum, A. tamarense, Gonyaulax spinifera, Gymnodinium catenatum and Scrippsiella trochoidea. The abundance and vertical distribution characterestics of the main and the toxic dinoflgellate cysts are also studied in the paper.%通过对福建罗源湾口海域 KMZK5 柱状沉积物中甲藻孢囊的分析,共鉴定出 15 属 30 种甲藻孢囊.对比发现这 30 种甲藻孢囊是该湾以前未被记录的种类.其中 12 种是附近海域也未曾发现的种类,6 种为有毒种类:缘亚历山大藻、小型亚历山大藻、塔玛亚历山大藻、具刺膝沟藻、链状裸甲藻、锥状斯氏藻.同时对甲藻孢囊的主要属种和有毒种类的丰度、分布在垂直方向上的变化特征进行了初步研究.

  18. 南极普里兹湾表层沉积物的元素组合特征及物源分析%STATISTICAL EVALUATION OF THE ELEMENTAL COMPOSITION AND SOURCE ANALYSIS OF SURFACE SEDIMENTS IN PRYDZ BAY, ANTARCTICA

    Institute of Scientific and Technical Information of China (English)

    蓝木盛; 于培松; 韩正兵; 扈传昱; 潘建明; 张海生

    2015-01-01

    利用中国南极科学考察第18—27航次在普里兹湾获得的20个表层沉积物样品,测定了其中C、N、Ca和Ti等多种常、微量元素的含量,分析了元素组合对指示物源的意义,探讨了普里兹湾的沉积环境和物质来源。结果表明:研究海域表层沉积物中元素含量的变异系数均较大,元素的平面分布、相关性和聚类特征出现两种模式;一类以OC、TN和S元素为主的元素组合指示了海洋生物来源,而另一类元素组合K、Ti和Rb等指示了陆源碎屑来源;湾内中心及东南部区域的沉积作用主要受控于上层水体的生物生产,而西侧的弗拉姆浅滩和艾默里冰架前缘陆架区的沉积物则包含大量冰筏碎屑的输入。%A number of major and trace elements including C, N, Ca, and Al were measured in 20 surface sediment samples collected from Prydz Bay, Antarctica, during the CHINARE 18—27 cruises.The distributions of these ele-ments and their characteristics of association were used to explore the sedimentary environment and material sources within the study area.The results showed that the values of most of the elements in the surface sediments changed over a wide range.Furthermore, the elemental distribution, correlation, and clustering features presented two pat-terns.One represented by OC, TN, and S that indicated a source of marine organisms, and the other represented by K, Ti, and Rb that indicated a source of terrigenous clastics.The results also suggested that sedimentation at the center of Prydz Bay and the southeastern area was controlled by biological production, whereas sedimentation near the Fram Bank and continental shelf in front of the Amery Shelf, contained a large number of ice-rafted clasts.

  19. Enrichment and bioavailability of heavy metals in sediments of the Bangkok Bay%曼谷湾沉积物重金属元素的富集效应与生物有效性

    Institute of Scientific and Technical Information of China (English)

    乔淑卿; 石学法; 高晶晶; 朱爱美; Narumol Kornkanitnan; 胡利民; 张杨硕

    2015-01-01

    2010年在曼谷湾(泰国湾北部)及其北部主要河口(湄干河、拉塞河、湄南河和邦巴功河)采集了46个表层沉积物样品,分析了样品中重金属元素(Cd、Co、Cu、Pb、Zn)的含量水平,并用Al均一化数据,获得消除了粒度效应的重金属地球化学特征.利用1mol/L的HCl对该区沉积物进行了处理,通过分析沉积物重金属在酸溶相和残渣相的分布,揭示其生物有效性.结果表明,曼谷湾周边河流沉积物中重金属元素含量明显高于曼谷湾;曼谷湾沉积物中重金属(Co、Cu、Pb、Zn)从北向南随着离岸距离的增加而增加,Cd没有明显分布规律;地累积指数显示Cd和Pb存在显著的地球化学富集特征.Cd和Pb在酸溶相中的比例相对较高,表明其生物有效性较高,易引发二次污染.%Forty-six surface sediment samples were collected from the Bangkok Bay (Upper/Northern Gulf of Thailand) and adjacent river-mouths (Mae Klong River, Tha Chin River, Chao Phraya River, and Bang Pakong River) in 2010. The geochemical characteristics of heavy metals (Cd, Co, Cu, Pb and Zn) were studied using Al as a reference element to normalize the grain-size effect. The biological availability was assessed based on heavy metal concentrations in acid-soluble and residual fractions after the bulk sediment samples were pretreated with 1mol/L HCl. The results showed that the concentrations of heavy metals in sediments of the river-mouths were higher than that of the Bangkok Bay. The concentrations of heavy metals increased in a seaward direction from north to south except Cd and geo-accumulation index indicates that Cd and Pb were significantly enriched in the sediments. Higher concentrations of Cd and Pb in the soluble fractions showed strong bioavailability which may easily cause secondary pollution.

  20. Environmental impact of aquaculture - sedimentation and nutrient loadings from shrimp culture of the southeast coastal region of the Bay of Bengal

    Institute of Scientific and Technical Information of China (English)

    Biplob Das; Yusuf Sharif Ahmed Khan; Pranab Das

    2004-01-01

    Nutrient loadings were measured for surface seawater and bottom sediments of semi-intensive and improved extensive shrimp culture pond, adjacent estuary, and fallow land in the south-east coastal region of Bangladesh during August, 2000 - January, 2001 to evaluate the impact of shrimp culture. The mean levels of nutrients found in the pond surface water were 108.780 mg/L for CaCO3, 0.526 mg/L for NH4+-N, 3.075 wt% for organic carbon, 7.00 mg/L for PO4-P, 5.57 mg/L for NO3-N, and 7.33 mg/L for chlorophyll-a. The maximum mean value of H2S(0.232 mg/L) was found in estuarine water. Nutrients loading were found to be decreased with distance from the shrimp farm discharge unit in estuarine water. The mean level of organic matter, total nitrogen, and organic carbon were found in higher concentrations in sediments of cultured pond compared to bottom soil of adjacent fallow land at the same elevation. Extractable Ca values were found in higher concentration(550.33 ppt) in adjacent fallow land, as; the shrimps for molting in shrimp ponds use extractable Ca. The relation between seawater H2S value and sediment pH (r = - 0.94); sediment organic carbon and sediment pH values (r = - 0.76), sediment total nitrogen and sediment pH (r = - 0.74) were found to be highly negatively correlated. Whereas the relation between seawater H2S value and sediment total nitrogen (r = 0.92), water NH4+-N and sediment pH (r = 0.66) were found to be positively correlated. The results revealed that load of nutrients at eutrophic level in estuarine water, and decrease of soil pH; leading to acid sulphate soil formation indicates a negative impact of shrimp culture.

  1. Extraction procedure compared to attenuation model to assess heavy metals mobility in sediments from Sepetiba Bay, Rio de Janeiro; Procedimento de fracionamento comparado a modelo de atenuacao para a avaliacao de mobilidade de metais pesados em sedimentos da Baia de Sepetiba, Rio de Janeiro

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Andreza Portella

    2006-07-01

    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 {sigma}[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

  2. Sediment Texture Units of the Sea Floor from Nahant to Northern Cape Cod Bay, Massachusetts (NAH_CCB_sedcover polygon shapefile, Geographic, WGS84)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data are qualitatively derived interpretive polygon shapefiles and selected source raster data defining surficial geology, sediment type and distribution, and...

  3. Pore water composition of Permeable reef flat sediments on Checker Reef in Kaneohe Bay, Oahu, Hawaii from 07 October 1996 to 03 July 1997 (NODC Accession 0000271)

    Data.gov (United States)

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

  4. 2004 Sediment Profile Imaging (SPI) Data for Catlett and Goodwin Islands on the York River, Chesapeake Bay, Virginia (Ches_2004SPI)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set represents the sediment profile imaging data from 2004 (79 stations).In Fall/Winter 2002, researchers from the Virginia Institute of Marine Science...

  5. 2002 Sediment Profile Imaging (SPI) Data for Catlett and Goodwin Islands on the York River, Chesapeake Bay, Virginia (Ches_2002SPI)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set represents the sediment profile imaging data from 2002.In Fall/Winter 2002, researchers from the Virginia Institute of Marine Science (VIMS) and the...

  6. Bioaccumulation Potential of Contaminants from Bedded and Suspended Oakland Harbor Deepening Project Sediments to San Francisco Bay Flatfish and Bivalve Mollusks

    Science.gov (United States)

    1994-08-01

    Turbidity Bioassay Facility developed at the University of California Bodega Marine Laboratory and used in the San Francisco Bay Dredge Disposal Study...I, endosulfan II , DDE, DDT, DDD, dieldrin, endrin, endrin aldehyde, endrin ketone, medhoxychlor, and dibutylchlorendate (USEPA, Research Triangle...following pesticides and PCBs were < DL in all samples: c-BHC, f-BHC, ’y-BHC, 5-BHC, aldrin, endosulfan I and II , dieldrin, endrin aldehyde

  7. Palaeoceanographic implications of abundance and mean proloculus diameter of benthic foraminiferal species Epistominella exigua in sub-surface sediments from distal Bay of Bengal fan

    Indian Academy of Sciences (India)

    R Saraswat; R Nigam; Lea Barreto

    2005-10-01

    Temporal variation in abundance and mean proloculus diameter of the benthic foraminiferal species Epistominella exigua has been reconstructed over the last ∼ 50,000 yr BP,from a core collected from the distal Bay of Bengal fan,to assess its potential application in palaeoceanographic reconstruction studies.The down-core variation shows significant change in abundance of E. exigua during the last ∼50,000 yr BP.In view of the present day abundance of this species from areas with strong seasonal organic matter supply, we conclude that at ∼7, ∼22, ∼33 and ∼46 kyr BP, strong seasonality prevailed in the distal Bay of Bengal fan,probably indicating either strong or prolonged north–east monsoon or weakened south–west monsoon.For the first time,a strong correlation is observed in abundance and mean proloculus diameter of E. exigua Based on coherent variation in mean proloculus diameter and abundance,it is postulated that mean proloculus diameter can also be used to infer increased seasonality in organic matter production,thus variation in strength or duration of monsoon.Thus,this study establishes that the down-core variation in the abundance and mean proloculus diameter of Epistominella exigua can be used to infer past climatic variations from the distal Bay of Bengal fan.

  8. Sedimentos laminados de la Bahía Mejillones como registro de cambios temporales en la productividad fitoplanctónica de los últimos ~ 200 años Temporal changes in phytoplankton productivity over the last ~ 200 years recorded from Mejillones Bay laminated sediments

    Directory of Open Access Journals (Sweden)

    MAGALY CANIUPÁN

    2009-03-01

    más frías asociado a una intensificación de los vientos y de la surgencia costera. Nuestro trabajo sugiere que la productividad desde AD 1820 ha estado fuertemente condicionada por la producción primaria silícea, y que especialmente a partir de AD 1877 se habría acoplado una mayor producción primaria calcárea.We analyzed the contents of total organic carbon, biogenic opal, chlorins, and alkenones (as productivity proxies from a laminated sediment core recovered within Bahía Mejillones, northern Chile, in order to reconstruct recent temporal changes in phytoplankton productivity. Physical parameters (water content, dry bulk density, magnetic susceptibility, X-radiography, and grey scale intensity were also used to characterize the sediments. A sedimentation rate of 0.18 cm year¹ (based on 210Pb measurements was determined for the core (Core 3; 23°03' S, 70°27' W, which was recovered with a box-corer (water column depth: 80 m. By extrapolating this sedimentation rate to the base of the core, it yielded a total age of ~223 years. The sediments were characterized by a succession of light and dark millimetre-thick laminae, which differed in both physical properties and composition; the denser dark laminae had less water content and represented periods of increased phytoplankton productivity, whereas the less dense, light laminae had higher water content and reflected less productive periods. The good preservation of the laminae^ the absence of structures associated with processes of bioturbation, and the high sedimentary δ15N values ( = 11.37 %o suggest low dissolved oxygen levels in the bay's bottom water during the two centuries of sedimentary deposition reported herein. Our record is divided into two large productivity intervals: one prior to AD 1820, with lower phytoplankton productivity and relatively warmer conditions, and another from ~AD 1877 to the present, characterized by higher productivity, high variability, and relatively colder conditions, and

  9. Ultrasound-assisted extraction combined with reverse phase-dispersive liquid-liquid micro extraction as a new approach for preconcentration and spectrophotometric determination of total phenol in marine sediments of Chabahar Bay.

    Science.gov (United States)

    Ziyaadini, Morteza; Zahedi, Mir Mahdi; Khosravinia, Saeid

    2016-08-15

    In this study, Reverse phase dispersive liquid-liquid micro extraction (RP-DLLME) technique have been successfully developed to preconcentrate trace amount of phenol from sediment samples as a prior step to its derivatization with 4-aminoantipyrine and enhanced determination by UV-Vis spectrophotometry after primary ultrasonic extraction. In this procedure, 50μL 0.7M NaOH solution was chosen as extraction solvent and other factors including pH, extraction time, concentration of 4-aminoantipyrine, type and volume of dispersive solvents were optimized. Under selected conditions, the limit of detection, the linearity range, relative standard deviation and enrichment factor of method were obtained 15μg·kg(-1), 50-1800μg·kg(-1), 4.8% (n=10) and 33, respectively. Finally, using the high sensitivity, low organic solvent consumption and waste generation method, total phenol content in marine sediments from several locations in Chabahar Bay (southeast Iran) was estimated at 55.8-73.2μg·kg(-1).

  10. Change of the Surface Soil in the Ohno River Drainage and its Impact on the Detrital Composition of the Sediments in the Beppu Bay, the Southwestern Japan, during the Holocene

    Science.gov (United States)

    Irino, T.; Yamamoto, M.; Ikehara, K.; Kuwae, M.; Takemura, K.

    2012-12-01

    Detrtal fraction contained in marine sediments can be generally used as climate proxies because variations in provenance and mineralogy could be affected by the precipitation distribution and weathering intensity. Change in the surface soil composition could be observed if a well-preserved depositional soil sequence was found. In order to detect the change in provenances and interpret the terrestrial environment using detrital proxies in the marine sediments, it is necessary to know the variability or range of the mineral composition of a particular provenance during the targeted time periods. The Ohno River is located in the northeast Kyushu Island, the southwestern Japan, which has the head water region at the Mt. Kuju and Mt. Aso, flows eastward combining some tributaries from the south, and then flows northward to the Beppu Bay. Surface geology of the drainage area is roughly divided into two as andosol in the northeast and brown forest soil in the south. Such contrasting detrital provenances could provide a variety of grain composition to the marine sediments deposited in the Beppu Bay. The No. 5 boring core was drilled at a landfill site on the mouth of the Ono River. The core continuously recovers 97 m length and consists of Holocene marine sediments which could be a good record of the terrestrial environment of hinterland (the Ohno River Basin). We also found a soil sequence on the foot of the Mt. Kuju at 850 m altitude, which covers the similar time interval as the No.5. The soil sequence consists of brown loam overlain by the alternation of tephra and andosol. We tried to compare the variations in mineral compositions both for this soil sequence and the No.5 core since about 8,000 yrs age. The No. 5 core mainly consists of smectite, illite, chlorite (or kaolinite), amphiboles, quartz, feldspars, and amorphous materials with minor calcite. Amorphous material is supposed to mainly consists biogenic opal. Amorphous material is higher during 7000 to 3500 yrs

  11. The risk assessment of heavy metals in Futian mangrove forest sediment in Shenzhen Bay (South China) based on SEM-AVS analysis.

    Science.gov (United States)

    Chai, Minwei; Shen, Xiaoxue; Li, Ruili; Qiu, Guoyu

    2015-08-15

    The risks of heavy metal in Futian mangrove forest sediment were assessed using the acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) methods. The results indicated that AVS distributions were more variable than the SEM distributions at all 16 sampling sites. The positive correlation between AVS and SEM indicated that their similar formative and existing conditions and that AVS acted as an important carrier for SEM. The major SEM component was Zn (69.7.3-94.2%), whereas the Cd contribution (the most toxic metal present) to SEM was no more than 1%. The possible adverse effects caused by heavy metals at ten sampling sites may be due to higher levels of SEMs, rather than AVSs. The total organic carbon (TOC) was an important metal-binding phase in the sediments. Taking into account the TOC concentration, there were no adverse effects due to heavy metals in any of the Futian mangrove forest sediments.

  12. In situ experimentation at the water/sediment interface in the deep sea: 2. Biotransformation of dissolved organic substrates by microbial communities at 2000m depth in the Bay of Biscay

    Science.gov (United States)

    Cahet, Guy; Daumas, Raoul; Sibuet, Myriam

    Few attempts have been made to quantify the utilization of organic matter by the bacteria of the superficial layers of deep sea sediment. During two BIOCYAN cruises (August 1986 and June 1987) we used the submersible Cyana, to incubate sediment samples in situ in a specially designed box core in presence of 14C-glutamic acid and 3H leucine. These experiments were conducted at 2000m depth in the Bay of Biscay. Bacterial activity was stopped by the injection of formaldehyde. Samples were retrieved with the research submersible Cyana and its accompanying free vehicle shuttle. Sediment organic matter was fractioned into four components: 1) 14CO 2; 2) nucleic components and polysacharids; 3) labile proteins; and 4) condensed hydrolysable polymers. To evaluate the barotolerance of deep-sea bacteria, undisturbed superficial layer samples were also incubated with the same labelled substrates at 4°C at the atmospheric pressure. In both cases, and except for glucose, our results show that distributions of radioactivity in the different components of the organic material were almost similar. However, the rate of incorporation was usually higher for in situ experiments than for decompressed samples. Bacterial utilization of both 14C glutamic acid and 14C glucose were higher in June than in August. Such differences may result from changes in the food supply arriving as sinking particles and deriving from the photosynthetically productive surface waters. Food input was probably more important in June than in August leading to corresponding increases in: 1) the abundance of derived bacteria, and 2) deep-sea bacterial activities.

  13. 太湖竺山湾污染底泥环保疏浚深度的推算%Calculation of environmental dredging depth of contaminated sediments in Zhushan Bay of Taihu Lake

    Institute of Scientific and Technical Information of China (English)

    王雯雯; 姜霞; 王书航; 金相灿

    2011-01-01

    根据颜色、气味、粒径、黏稠度等理化指标,将太湖竺山湾柱状底泥样品由上至下依次分为氧化层(A)、污染层(B)、污染过渡上层(C1)、污染过渡下层(C2)和健康层(D).通过对底泥中氨氮、总磷、总氮和烧失量垂直分布规律的分析,结合柱状底泥各分层氮、磷吸附/解吸实验,推算出竺山湾污染底泥环保疏浚层及其深度.结果表明,底泥中氨氮、总磷、总氮和烧失量含量随深度的增加呈下降趋势.A层和B层中污染物含量明显高于其他层;无机磷吸附/解吸平衡浓度随深度的增加而下降,在C1层与C2层间出现拐点;而氨氮的吸附/解吸平衡浓度变化趋势较复杂.结合上覆水中无机磷与氨氮浓度,推算出竺山湾底泥环保疏浚层次为C1层,疏浚平均深度为0.40~0.70m.%According to physical and chemical indexes of sediment, such as color, odor, particle size and viscosity, column sediments of Zhushan Bay were divided into oxide layer(A), polluted layer(B), upper polluted transition layer(C1), lower polluted transition layer(C2)and healthy mud layer(D) from top to bottom. To calculate the environmental dredging layer and depth of Zhushan Bay, vertical distributions of ammonia nitrogen(NH4+-N), total phosphorus(TP), total nitrogen(TN) and loss of ignition(LOI) were analyzed. Nitrogen and phosphorus adsorption/desorption experiments about every layer were also conducted. Concentrations of NH4+-N, TP, TN and LOI decreased with depths, and concentrations of contaminants in layer A and layer B were significantly higher than those in other layers. Adsorption/desorption equilibrium concentrations of inorganic phosphorus(IP) in sediment decreased with depths, and there was an inflection point between C1 layer and C2 layer. Changes of adsorption/desorption equilibrium concentrations of NH4+-N with depths were complex. Combined with concentrations of IP and NH4+-N in overlying water, environmental dredging (env

  14. Chile's Madam President

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    After becoming the first female to win a presidential election in the socially conservative country, Chilean President-elect Michelle Bachelet created history again when unveiling a cabinet that was absolutely gender-balanced on January 30. Following similar breakthroughs of women politicians in Liberia and Germany, what happened in Chile is considered another case of women gaining power worldwide.

  15. Determination of the sedimentation rates in the Sepetiba bay northeastern area by using dating with the excesses {sup 210} Pb radioisotope; Determinacao das taxas de sedimentacao na porcao nordeste da baia de Sepetiba utilizando datacao com o radioisotopo {sup 210} Pb em excesso

    Energy Technology Data Exchange (ETDEWEB)

    Forte, Cristiane Maria Sampaio

    1996-07-01

    {sup 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. {sup 210} Pb was leached from samples using dilute HBr and subsequently separated onto anionic exchange columns, followed by re-extraction and precipitation as Pb CrO{sub 4}. 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{sup -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)

  16. Seasonal accumulations of some heavy metal in water, sediment and tissues of black-chinned tilapia Sarotherodon melanotheron from Biétri Bay in Ebrié Lagoon, Ivory Coast.

    Science.gov (United States)

    Coulibaly, Safiatou; Atse, Boua Célestin; Koffi, Kouamé Mathias; Sylla, Soumaïla; Konan, Kouadio Justin; Kouassi, N'Guessan Joël

    2012-04-01

    The seasonal accumulation of cadmium, copper, lead, mercury and zinc was determined in sediments, water, and black-chinned tilapia (Sarotherodon melanotheron; muscle, brain, kidney and liver tissues) collected monthly from Biétri Bay. The mean water concentration of metals (in mg L(-1)) ranged from 0.01 to 0.30 (mercury), 0.02-0.26 (cadmium), 2.40-4.80 (lead), 9.05-9.68 (copper), and 12.05-19.87 (zinc). The seasonal variations showed a significant difference in the levels of mercury, cadmium and lead among season. The highest mercury (0.30 ± 0.02 μg L(-1)), cadmium (0.26 ± 0.02 mg L(-1)) and lead (4.80 ± 1.03 mg L(-1)) levels were observed during dry season, while the lowest levels (0.21 ± 0.01, 0.02 ± 0.01 and 2.40 ± 0.02 mg L(-1), respectively mercury, cadmium and lead) were measured during rainy season. The average cadmium (0.58 ± 0.36 mg L(-1)), copper (42.15 ± 19.40 mg L(-1)), lead (58.47 ± 38.10 mg kg(-1)), mercury (0.79 ± 0.47 μg kg(-1)) and zinc (187.58 ± 76.99 mg kg(-1)) concentrations determined in Biétri Bay sediments showed a similar trend as in water. The seasonal variations of mercury, cadmium and lead in tissues revealed that these metals were higher concentrated during dry and swelling seasons. The levels of zinc and copper followed by lead were higher in the tissues. The order of tissues metals concentrations was: kidney > liver > brain > muscle.

  17. Sedimentation of Particulate Organic Matter in the Dona Paula Bay, West Coast of India during November to May 1995-97.

    Digital Repository Service at National Institute of Oceanography (India)

    Bhaskar, P.V.; Cardozo, E.; Giriyan, A.; Garg, A.; Bhosle, N.B.

    % of the gross POC and was highest (45%) in April 1997. The mean net POC flux was 197 ± 90 mg C m -2 d-1and accounts for 4.6% of the TPM. The average C:N (w:w) ratio of the sedimented material was 13.2± 6.6. The POC/Chl a ratio was relatively higher...

  18. Distribution and ecotoxicology of bioavailable metals and As in surface sediments of Paraguaçu estuary, Todos os Santos Bay, Brazil.

    Science.gov (United States)

    Pereira, Taís de S; Moreira, Ícaro T A; de Oliveira, Olívia M C; Rios, Mariana C; Filho, Wilton A C S; de Almeida, Marcos; de Carvalho, Gilson Correia

    2015-10-15

    Surface sediments collected in the intertidal zone of Paraguaçu estuary in July, 2013, were analyzed for organic matter, nitrogen, phosphorus, grain size fractions and partial concentrations of 16 metals. The USEPA 3051A method and ICP-OES and CV-AAS techniques were chosen to metal analysis. Pollution indices (EF, Igeo and PIN) and a comparison with sediment quality guidelines (UET, ERL, ERM, TEL and PEL of NOAA) were conducted in order to evaluate the potential metal impacts over the area. Principal Component Analysis (PCA) and Pearson correlation results showed the importance of organic matter content and the fine-grained fraction of sediments on the control of the bioavailable metals distribution. The Paraguaçu estuary already has anthropogenic enrichment relative to the background level, especially for Mn, whose values exceeded almost 30 times the background at one site (Mn: 1197.30 mg kg(-1)). However, metal levels are still below the reference values with the exception of Hg at one site (Hg: 0.25 mg kg(-1), exceeded TEL and ERL).

  19. Diversidad y biomasa de macro-invertebrados en matrices intermareales del tunicado Pyura praeputialis (Heller, 1878 en la Bahía de Antofagasta, Chile Diversity and biomass of macro-invertebrates in intertidal matrices of the tunicate Pyura praeputialis (Heller, 1878 in the Bay of Antofagasta, Chile

    Directory of Open Access Journals (Sweden)

    MAURICIO CERDA

    2001-12-01

    . Three sites were studied inside the Bay: one located approximately at the center P. praeputialis geographical distribution in the bay and two around the north and south limits respectively (ecotones. The crevices and interstices between individuals in the dense matrices of P. praeputialis provide bio-habitat, such as those described for ecosystem-engineer species. A total of 96 taxa of macro-invertebrates (gama diversity, corresponding to nine phyla, associated to P. praeputialis matrices were recorded. The richer taxa were: gastropod (28 %, polychaeta (26 %, decapod (15 % and bivalve (14 %. The mean biomass of invertebrate registered was of 246,40 g m-2. The paper discusses the elevated diversity of macro-invertebrates recorded in the Antofagasta´s P. praeputialis matrices, the observed patterns along the geographical distribution inside the bay and the role of this tunicate as a bio-engineer species. The results are compared with a similar study on P. stolonifera carried out in Natal, South Africa and with respect to the diversity of macro-invertebrate associated to other bio-engineer species

  20. USGS Tampa Bay Pilot Study

    Science.gov (United States)

    Yates, K.K.; Cronin, T. M.; Crane, M.; Hansen, M.; Nayeghandi, A.; Swarzenski, P.; Edgar, T.; Brooks, G.R.; Suthard, B.; Hine, A.; Locker, S.; Willard, D.A.; Hastings, D.; Flower, B.; Hollander, D.; Larson, R.A.; Smith, K.

    2007-01-01

    Many of the nation's estuaries have been environmentally stressed since the turn of the 20th century and will continue to be impacted in the future. Tampa Bay, one the Gulf of Mexico's largest estuaries, exemplifies the threats that our estuaries face (EPA Report 2001, Tampa Bay Estuary Program-Comprehensive Conservation and Management Plan (TBEP-CCMP)). More than 2 million people live in the Tampa Bay watershed, and the population constitutes to grow. Demand for freshwater resources, conversion of undeveloped areas to resident and industrial uses, increases in storm-water runoff, and increased air pollution from urban and industrial sources are some of the known human activities that impact Tampa Bay. Beginning on 2001, additional anthropogenic modifications began in Tampa Bat including construction of an underwater gas pipeline and a desalinization plant, expansion of existing ports, and increased freshwater withdrawal from three major tributaries to the bay. In January of 2001, the Tampa Bay Estuary Program (TBEP) and its partners identifies a critical need for participation from the U.S. Geological Survey (USGS) in providing multidisciplinary expertise and a regional-scale, integrated science approach to address complex scientific research issue and critical scientific information gaps that are necessary for continued restoration and preservation of Tampa Bay. Tampa Bay stakeholders identified several critical science gaps for which USGS expertise was needed (Yates et al. 2001). These critical science gaps fall under four topical categories (or system components): 1) water and sediment quality, 2) hydrodynamics, 3) geology and geomorphology, and 4) ecosystem structure and function. Scientists and resource managers participating in Tampa Bay studies recognize that it is no longer sufficient to simply examine each of these estuarine system components individually, Rather, the interrelation among system components must be understood to develop conceptual and

  1. The Structures of Sediment Microbial Communities in Different Mariculture Models at Xiangshan Bay of China%象山港南沙岛不同养殖模式沉积物微生物群落结构分析

    Institute of Scientific and Technical Information of China (English)

    孙超; 朱玲; 毛玉泽; 范艳君; 周春娅; 杨傲傲; 朱伟; 庄志猛

    2014-01-01

    通过构建16S rDNA克隆文库对象山港南沙岛不同养殖模式(贝类养殖、藻类养殖及网箱养殖)表层沉积物微生物多样性和群落结构特征进行了比较和分析,共获取136个OUT。其中,贝类养殖区、藻类养殖区和网箱养殖区OTU分别为58、48和57个。各站位OTU分布差异明显,表现出高度的多样性。基于16S rDNA序列的生物多样性和丰富度分析表明,网箱养殖区丰富度指数ACE为739,香浓指数H¢为3.8,均为最高值,丰富度指数Chao为245,略低于于贝类养殖区。贝类养殖区丰富度指数Chao为303,在各养殖区中最高。藻类养殖区丰富度指数ACE为174、Chao为89,香浓指数H¢为3.6,均为最低值。系统发育分析表明,南沙岛各养殖区的优势种群均为变形菌门(Proteobacteria),但是藻类养殖区微生物群落结构与其他养殖区域相比,16S rDNA克隆文库差异显著,其中根瘤菌属(Rhizobium)及其他光合细菌在藻类养殖区分布较多。网箱养殖区沉积物表层微生物群落中出现了与环境污染密切相关的菌群,如志贺氏菌属(Shigella)、埃希氏菌属(Escherichia)和ε-变形菌纲的微生物种群,揭示网箱养殖对底质沉积物环境的影响较大。%Xiangshan Bay, the biggest marine aquaculture base in Zhejiang Province, is a semi- enclosed bay with slow water exchange rate. In the center of Xiangshan Bay lies Nansha Bay where a variety of mariculture models are applied. To better understand the structures and diversity of sediment microbial communities in different mariculture models, we constructed the 16S rDNA clone library for the analysis of samples from the shellfish culture, the seaweed culture and the fish cage culture. We obtained 136 OTUs from three sampling models that included 58 OTUs from the shellfish culture, 48 from the seaweed culture, and 57 from the fish cage culture. The distribution patterns of OTUs were highly different

  2. Occurrence and distribution of perfluoroalkyl acids (PFAAs) in surface water and sediment of a tropical coastal area (Bay of Bengal coast, Bangladesh).

    Science.gov (United States)

    Habibullah-Al-Mamun, Md; Ahmed, Md Kawser; Raknuzzaman, Mohammad; Islam, Md Saiful; Negishi, Junya; Nakamichi, Shihori; Sekine, Makoto; Tokumura, Masahiro; Masunaga, Shigeki

    2016-11-15

    This study reports the first evidence of perfluoroalkyl acids (PFAAs) in surface waters and sediments collected from the coastal area of Bangladesh. Fifteen target PFAAs, including C4-14-PFCAs (perfluoroalkyl carboxylates) and C4, C6, C8, and C10-PFSAs (perfluoroalkyl sulfonates), were quantified by HPLC-MS/MS. The ΣPFAAs in surface water and sediment samples were in the range of 10.6 to 46.8ng/L and 1.07 to 8.15ng/gdw, respectively. PFOA in water (3.17-27.8ng/L) and PFOS in sediment samples (0.60-1.14ng/gdw) were found to be the most abundant PFAAs, and these concentrations were comparable to or less than most other reported values, particularly those recorded from the coastal areas of China, Japan, Korea and Spain. The majority of the monitored PFAAs did not show clear seasonal variation. The southeastern part (Cox's Bazar and Chittagong) of the Bangladeshi coastal area was more contaminated with PFAAs than the southern (Meghna Estuary) and southwestern parts (Sundarbans). Industrial and municipal wastewater effluents, ship breaking and port activities were identified as potential sources of the PFAA contamination in this region. Field-based sediment water distribution coefficients (KD) were calculated and corrected for organic carbon content (KOC), which reduced the variability between samples. The values of log KD (1.63-2.88) and log KOC (4.02-5.16) were higher than previously reported values, which may indicate that the partitioning of PFAAs in a tropical coastal ecosystem is different from other ecosystems, such as temperate and sub-tropical regions. Although a preliminary environmental hazard assessment indicated that PFOA or PFOS levels do not currently exceed the acute safety thresholds, we should keep in mind that they are bioavailable and can accumulate in the food chain. Therefore, the ubiquity of PFAAs in the coastal area of Bangladesh warrants further studies characterizing their specific sources and the potential long-term risks they present to both

  3. 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.

    stream_size 22164 stream_content_type text/plain stream_name J_Earth_Syst_Sci_114_453.pdf.txt stream_source_info J_Earth_Syst_Sci_114_453.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859... changes. The climatic history preserved in marine sediments can unfold mysteries by using various proxies. In order to have a comprehensive and compatible reconstruction of climate, different parameters of marine microfossils are used. Among various...

  4. 东南极阿曼达湾湖泊沉积物物源的元素分析%GEOCHEMICAL ANALYSIS TO DETERMINE THE SOURCES OF LAKE SEDIMENTS FROM AMANDA BAY, EAST ANTARCTICA

    Institute of Scientific and Technical Information of China (English)

    黄涛; 孙立广

    2012-01-01

    2008年在东南极阿曼达湾帝企鹅聚集区附近岛屿开展了野外工作,于岛屿湖泊集水区采集到两个短沉积柱样,分别命名为EPI和PI.根据野外实地考察情况和室内分割样品发现EPI柱样主要为泥炭沉积,含有大量水生藻类;PI柱样为黑色泥质沉积,散发出浓烈的粪臭味,沉积物中含有大量的幼年帝企鹅绒毛和少量的残骨.对EPI和PI柱样沉积物、当地风化母岩及水生湖藻进行了部分生源元素和重金属元素浓度分析与对比,结果显示EPI柱样元素含量主要来源于背景母岩和湖藻沉积.PI柱样为帝企鹅粪土沉积序列,沉积物中的TC、TN、TP、Cu、Zn、Hg和Se的含量远远高于风化母岩中的浓度,其主要来源于帝企鹅粪的输入,而Pb元素主要来源于当地风化母岩的贡献.研究显示帝企鹅活动同样可以为南极贫瘠的陆地湖泊系统带来大量的营养物质,但同时也输入了大量的重金属污染元素.%Two short lake sediment cores,EPI and PI,were collected at N Island,Amanda Bay,East Antarctica,during the 2007-2008 seasons.The lithology and sedimentology of the EPI profile indicated a predominance of peat deposit.The PI sediments were composed of black mud,contained many penguin feathers and bones,and had a strong and unpleasant smell of penguin guano.Elemental concentrations in the sediments of the EPI and PI cores,local bedrock,and lake algae,were analyzed.The results indicated that elemental concentrations in the sediments of the EPI core were primarily derived from bedrock and lake algae.The abundance of total carbon (TC) ,total nitrogen (TN) ,total phosphorus (TP) ,Cu,Zn,Hg,and Se in the PI core sediments was much higher than that in local bedrock,suggesting that the sediments were mainly composed of emperor penguin guano,while the element Pb was derived from the geochemical background.This study demonstrates that emperor penguins transport marine-derived nutrients and heavy metal

  5. Nearshore continental shelf: Morphology, paleomorphology, and sediment transport based on high-resolution geophysical profiling of Monterey Bay National Marine Sanctuary

    Science.gov (United States)

    Anima, Roberto Juan

    The intertwining of the shoreline with its coastal streams, headlands, pocket beaches, coves, and sea cliffs is tied to a nearshore with sea floor outcrops, shore-normal sand-filled low areas, subbottom channels, and variations in sediment texture. The stitching together of the two aspects of this high-energy environment was accomplished by geophysical surveying techniques that uncovered direct connections to each facet of the coastal area between Ano Nuevo and New Brighton Beach. What this work has accomplished is the expansion of our view of a high energy, active margin coastline in a way that reveals aspects of the nearshore that connect onshore coastal features, to previously unknown offshore features in a three dimensional view that incorporates morphology, processes, and time. This work gives a look at a nearshore that hints of a low sea level stand coastal scene not unlike our present. It uncovers relic stream channels that are direct ancestors of the present coastal streams. And finally, it proposes a conceptual model of how modern processes are constantly at work to shape and reshape this dynamic environment in order to fulfill its goal of moving sediment alongshore.

  6. Variación fenotípica y genética en el tunicado Pyura praeputialis (Heller, 1878 en el área norte de la Bahía de Antofagasta, Chile Phenotypic and genetic variation in tunicate Pyura praeputialis (Heller, 1878 in the northern sac of the Antofagasta Bay

    Directory of Open Access Journals (Sweden)

    MARCELA ASTORGA

    2002-09-01

    localities in the northern sac of the Bay of Antofagasta, Chile, and distributed along a wave exposure gradient. A total of 17 enzymatic loci were assayed by horizontal starch-gel electrophoresis, three of which (IDH-1, MDH-1 and PGM-1 were polymorphic. The results showed significant genetic differences among localities, but not among morphotypes. These results are contrasted with similar studies conducted on the same species in Australia, on the base that P. praeputialis has recently colonized Antofagasta from Australia. It is suggested that the differences among the morphotypes from Antofagasta are intraspecifics and those from Australia are interspecifics. The possible explanations for the genetic and morphological differences among localities are discussed

  7. Chile exploits LNG

    Energy Technology Data Exchange (ETDEWEB)

    1980-03-01

    Simultaneously with its exploitation of offshore hydrocarbon reservoirs Chile is developing the production and selling of LNG. Chile produces a large quantity of associated gas from its reservoirs at Megallanes and processes it at the Manantiales, Cullen and Posesion plants recovering propane, butane and natural gas liguids. The stripped gas is reinjected for pressure maintenance operations. With the completion of the LNG program full use of the gas will be achieved. It will totally meet the needs of combustible liquids for the central and northern parts of the country, a volume of 2200 million cu m/yr. For its treatment natural gas is sent through gas pipelines to the LNG plant at Cabo Negro. By means of a cooling process, the gas is cooled to -160 C where it becomes a liquid and its volume is reduced by a factor of 600. It is then stored in tanks at atmospheric pressure.

  8. Composición, estructura y flujo energético del meiobentos frente a Chile central Composition, structure and energy flux of the meiobenthos off central Chile

    Directory of Open Access Journals (Sweden)

    JAVIER SELLANES

    2003-09-01

    Full Text Available Se estudió la estructura de la meiofauna metazoaria (a nivel de grandes grupos taxonómicos y su rol en el flujo de energía en el subsistema bentónico frente a Concepción (~3630' S. Las muestras se recolectaron en mayo y noviembre de 1997 y mayo de 1998 en cinco sitios correspondientes a: interior de la Bahía de Concepción (28 m, boca de la bahía (35 m, plataforma interior (64 m, plataforma intermedia (88 m y plataforma externa (120 m. El periodo de estudio coincidió con el evento El Niño 1997-1998 (EN. El meiobentos resultó ser poco diverso a nivel de grandes grupos, pero con abundancias y biomasas moderadas a altas, en comparación con los valores promedio reportados en la literatura para el sublitoral fangoso. Nematoda fue el grupo dominante, con más de un 95 % (10³­10(4 ind 10 cm­2 de la densidad total, seguidos por Copepoda y Polychaeta. Las mayores abundancias y biomasas totales se encontraron siempre en la boca de la bahía, seguida de su parte interior y de la plataforma interior, mientras que los menores valores se ubicaron en la plataforma intermedia y externa. Frente a Concepción el meiobentos juega un importante rol en el flujo de energía a través del subsistema bentónico. Se estimó que estos organismos podrían estar remineralizando y/o convirtiendo a biomasa hasta un 36 y 45 % del carbono orgánico que llega desde la columna de agua a los sedimentos en el centro y en la boca de la bahía, respectivamente.The general objective of this study was to determine the structure of metazoan meiofauna (at a high taxonomic level and to estimate its role in the energy flux of the benthic sub-system off Concepción, Chile (~3630' S. Samples were collected in May and November 1997 and May 1998 at five sites located at the: inner Bay of Concepción (28 m, bay-mouth (35 m, inner-shelf (64 m, mid-shelf (88 m and outer-shelf (120 m. The study period coincided with the El Niño 1997-1998 (EN event. The diversity of the meiobenthos

  9. Nelson River and Hudson Bay

    Science.gov (United States)

    2002-01-01

    Rivers that empty into large bodies of water can have a significant impact on the thawing of nearshore winter ice. This true-color Moderate Resolution Imaging Spectroradiometer (MODIS) image from May 18, 2001, shows the Nelson River emptying spring runoff from the Manitoba province to the south into the southwestern corner of Canada's Hudson Bay. The warmer waters from more southern latitudes hasten melting of ice near the shore, though some still remained, perhaps because in shallow coastal waters, the ice could have been anchored to the bottom. High volumes of sediment in the runoff turned the inflow brown, and the rim of the retreating ice has taken on a dirty appearance even far to the east of the river's entrance into the Bay. The sediment would have further hastened the melting of the ice because its darker color would have absorbed more solar radiation than cleaner, whiter ice. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  10. 青岛灵山湾潮间带沉积物粒度参数高光谱定量反演%Quantitative inversion of sandy intertidal sediment grain size parameters content with hyperspectral in Lingshan Bay of Qingdao

    Institute of Scientific and Technical Information of China (English)

    陈晓琳; 孙根云; 徐方建; 赵永芳; 王振杰

    2015-01-01

    The sediment grain-size parameters of intertidal zone is not only a reference object for the research of modern coastal dynamics but also a basis for the evaluation of the sustainable development of human activities. This paper takes the surface sediment and the hyperspectral information of the intertidal zone in Lingshan Bay as study objects to analyze the ability in grain size parameters identifying. Mathematical transformations were taken aiming at solving the extraction difficulties in hyperspectral data. Multi-layer perceptron ANN (Artificial Neural Network) was established to build a relation model between the parameters and spectral reflectance to explore the feasibility of quantitative inversion of sediment characteristics. The final results show that using hyperspectral data to determine sediment grain-size parameters of intertidal zone is feasible. The advantages, i.e. fast and accurate, provide a new method for determining the intertidal zone sediment parameters. This would provide a reference for accurately monitoring and researching on the changes of intertidal zone.%潮间带表层沉积物粒度参数不仅是研究现代海岸动态和变迁的参照,也是评价人类活动可持续发展的依据。本文以灵山湾潮间带野外实地采集潮滩表层沉积物及其表面实时光谱信息为研究对象,分析高光谱用于粒度参数识别的能力。针对高光谱信息提取的困难,对光谱数据进行数学变换,利用多层感知器神经网络建立沉积物粒度参数与光谱反射率之间的关系模型,探索了利用表层沉积物反射光谱特性进行沉积物特征定量反演的可行性。结果表明:基于高光谱对沉积物粒度参数的定量预测是可行的,建立的预测模型可以较准确地反映潮间带沉积物粒度特征,其快速、准确的优点为测定潮间带表层沉积物粒度参数提供了一种新方法。该模型的建立为进一步提高潮间带变化监测和

  11. Humboldt Bay Initiative: Adaptive Management in a Changing World

    OpenAIRE

    Schlosser, Susan

    2009-01-01

    The Humboldt Bay Initiative seeks to bring people together to help envision the desired future state of the Humboldt Bay ecosystems, to help understand past, current and future conditions, and to move forward in the spirit of collaboration towards a sustainable and dynamic future. In order to address priority stresses to the ecosystems due to human activities, climate change, excessive sediment, and invasive species, the Humboldt Bay Initiative proposes a set of strategies that help create th...

  12. National Status and Trends: Bioeffects Program - Kachemak Bay Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This study was based on the sediment quality triad (SQT) approach. A stratified probabilistic sampling design was utilized to characterize the Kachemak Bay system in...

  13. National Status and Trends: Bioeffects Program - San Francisco Bay Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This study was based on the sediment quality triad (SQT) approach. A stratified probabilistic sampling design was utilized to characterize the San Francisco Bay...

  14. Isopachs--Salt Point to Drakes 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 Salt Point to Drakes Bay, California, region. The raster data file is included in...

  15. Environmental Contaminants Evaluation of St. Andrew Bay, Florida: Volume 1

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Between 1985 and 1997, a general survey of St. Andrew Bay, Florida, was conducted to measure chemical contaminant concentrations in the sediments and selected biota....

  16. Chile: segundo tiempo Chile: Half-time

    Directory of Open Access Journals (Sweden)

    ROBERT L FUNK

    2009-01-01

    Full Text Available El artículo examina el año político chileno, ofreciendo un análisis crítico del concepto de 'segundo tiempo' autoimpuesto por la presidenta Michelle Bachelet a comienzos del 2008. Resumiendo algunas de las políticas implementadas, el trabajo cuestiona si se logró marcar una linea y dejar atrás los dos primeros y difíciles años del cuarto gobierno de la Concertación. Analizando las medidas tomadas y las encuestas de opinión pública, se encuentra que el reenfoque de las prioridades del gobierno y una complicada coyuntura externa ayudó a levantar los niveles de apoyo de la presidenta y su gobierno.The article examines the political year in Chile, offering a critical analysis of the concept of 'Second Period' which President Michelle Bachelet defined at the beginning of 2008. Summarising some of the policies implemented, the piece asks whether the government was able to draw a line, leaving behind the first, difficult two years of the Concertación s fourth government. Analyzing the measures taken and public opinion polls, the paper finds that a re-focussing of the government's priorities together with a complicated external environment helped to raise support for the president as well as her government.

  17. Fluid channeling and their effect on the efficiency of benthic methane filter in various seep habitats and sediments

    Science.gov (United States)

    Steeb, Philip; Linke, Peter; Treude, Tina

    2014-05-01

    Marine sediments and sub-seafloor gas hydrates build one of the largest methane reservoirs on Earth. Most of the methane ascending in sediments is oxidized by anaerobic oxidation of methane (AOM) with sulfate as terminal electron acceptor, the so-called "benthic microbial methane filter". The efficiency of the benthic microbial methane filter is controlled by diffusive sulfate supply from seawater and advective methane flux from deep reservoirs. High fluid fluxes reduce the penetration depth of sulfate and limit the filter to a very narrow zone close to the sediment-water interface. However natural and catastrophic fluctuations of methane fluxes (caused e.g. by gas hydrate melting, earthquakes, slope failure) can change the fluid regime and reduce the capability of this greenhouse gas sink. A new Sediment-Flow-Through (SLOT) system was developed to incubate intact sediment cores under controlled fluid regimes. To mimic natural fluid conditions sulfate-free, methane-loaded artificial seawater medium was pumped from the bottom and sulfate-enriched seawater medium was supplied from above. Media and system were kept anoxic and seepage medium was tracked with bromide tracer. Over the entire experiment, the change of geochemical gradients inside the sediment column was monitored in monthly time intervals using porewater extraction/analyses and microsensor measurements. In addition, in- and outflow samples were analyzed for the calculation of methane turnover rates. In the above manner, sediments from different seeps (Eckernförde Bay, Costa Rica, Chile, and the Eastern Mediterranean Sea) and types (gassy sediments, gas hydrates containing sediments, mud volcanoes, sulfur bacteria mats, pogonophoran fields, clam fields) were incubated and monitored up to one year. Moderate to high advective fluid flow rates, which have been reported from natural seeps, were chosen to challenge the benthic microbial methane filter and investigate the response to pulses of methane loaded

  18. Primary Medical Care in Chile

    DEFF Research Database (Denmark)

    Scarpaci, Joseph L.

    Primary medical care in Chile: accessibility under military rule [Front Cover] [Front Matter] [Title Page] Contents Tables Figures Preface Chapter 1: Introduction Chapter 2: The Restructuring of Medical Care Financing in Chile Chapter 3: Inflation and Medical Care Accessibility Chapter 4: Help......-Seeking Behavior of the Urban Poor Chapter 5: Spatial Organization and Medical Care Accessibility Chapter 6: Conclusion...

  19. Assessment of suspended sediment concentration at the Hangzhou Bay using HJ CCD imagery%杭州湾HJ CCD影像悬浮泥沙遥感定量反演

    Institute of Scientific and Technical Information of China (English)

    刘王兵; 于之锋; 周斌; 蒋锦刚; 潘玉良; 凌在盈

    2013-01-01

    This research explored the potential of the use of the CCD image of the HJ satellite to derive Suspended Sediment Concentrations (SSC) of dynamic water bodies at Hangzhou Bay,which is a typical turbid water body in China.Through the analysis on the correlation between Remote Sensing Reflectance (RTS) and SSC,two apparent reflectance peaks at approximately 690 and 830 nm have been found in the third and fourth bands,respectively.The result also shows that a good correlation exists between Rrs and SSC when the wavelength is more than 700 nm.Based on the measured correlation between SSC and Rrs,the retrieval model is established using the ratio of band4 and band3 as remote sensing factor,and the model determination coefficient of 0.90 is reached.Through the Moderate Resolution Imaging Spectroradiometer (MODIS)-derived Aerosol Optical Depth (AOD) data,which are calculated from the Near Infrared-Short Wave Infrared (NIR-SWIR) atmospheric correction,the atmospheric correction of HJ CCD imagery is realized.The correction-relative errors of the third and fourth bands are 5.54% and 6.97%,respectively.The result demonstrates that the relative error of SSC derived from HJ CCD imagery is 7.12%,and SSC at Hangzhou Bay,which also has significant internal diversity,is much higher than that in the entrance of the Yangtze River.This research demonstrated that HJ CCD imagery can be used to evaluate SSC at Hangzhou Bay,if the appropriate atmospheric correction method and retrieval algorithm are used.%利用环境小卫星CCD(HJ CCD)影像对杭州湾悬浮泥沙浓度(SSC)进行了反演研究.通过对杭州湾水体遥感反射率(Rrs)与SSC进行相关性分析发现,在690nm和830nm左右出现显著的反射峰,分别位于HJCCD影像的第3和第4波段范围内;大于700nm波长处的Rrs与SSC相关性较好.基于实测Rrs和SSC之间的相关关系,利用第4和第3波段比值作为遥感因子建立SSC反演模型,模型决定系数达到0.90.借鉴近红外-短

  20. 沉积物扰动下太湖月亮湾中生物有效磷的变化规律%Variation of Bioavailable Phosphorus in Yueliang Bay of Tai Lake Under Sediment Disturbance Conditions

    Institute of Scientific and Technical Information of China (English)

    李大鹏; 王晶; 黄勇

    2013-01-01

    采用藻类吸收的方法,研究了太湖月亮湾沉积物在高强度扰动下,上覆水和悬浮物上生物有效磷(BAP)的变化规律,并分析了溶解性总磷(DTP)的生物有效性.结果表明,沉积物扰动导致上覆水中BAP含量增加,但其却低于DTP,说明DTP中含有生物无效的磷.沉积物扰动下,悬浮物上BAP呈降低趋势.通过悬浮物上BAP含量来计算上覆水中可被生物利用颗粒态磷(BAPP),发现DTP中具有生物有效性的磷占77%左右.与化学方法相比,采用藻类吸收测得的上覆水和悬浮物上BAP均较低,并且扰动过程中BAP的变化趋势也明显不同.从而说明,以往研究可能过高地估计了内源磷释放对浅水湖泊富营养化的贡献.%By using algae to det