WorldWideScience

Sample records for sandy ocean sediments

  1. Geomechanical, Hydraulic and Thermal Characteristics of Deep Oceanic Sandy Sediments Recovered during the Second Ulleung Basin Gas Hydrate Expedition

    Directory of Open Access Journals (Sweden)

    Yohan Cha

    2016-09-01

    Full Text Available This study investigates the geomechanical, hydraulic and thermal characteristics of natural sandy sediments collected during the Ulleung Basin gas hydrate expedition 2, East Sea, offshore Korea. The studied sediment formation is considered as a potential target reservoir for natural gas production. The sediments contained silt, clay and sand fractions of 21%, 1.3% and 77.7%, respectively, as well as diatomaceous minerals with internal pores. The peak friction angle and critical state (or residual state friction angle under drained conditions were ~26° and ~22°, respectively. There was minimal or no apparent cohesion intercept. Stress- and strain-dependent elastic moduli, such as tangential modulus and secant modulus, were identified. The sediment stiffness increased with increasing confining stress, but degraded with increasing strain regime. Variations in water permeability with water saturation were obtained by fitting experimental matric suction-water saturation data to the Maulem-van Genuchen model. A significant reduction in thermal conductivity (from ~1.4–1.6 to ~0.5–0.7 W·m−1·K−1 was observed when water saturation decreased from 100% to ~10%–20%. In addition, the electrical resistance increased quasi-linearly with decreasing water saturation. The geomechanical, hydraulic and thermal properties of the hydrate-free sediments reported herein can be used as the baseline when predicting properties and behavior of the sediments containing hydrates, and when the hydrates dissociate during gas production. The variations in thermal and hydraulic properties with changing water and gas saturation can be used to assess gas production rates from hydrate-bearing deposits. In addition, while depressurization of hydrate-bearing sediments inevitably causes deformation of sediments under drained conditions, the obtained strength and stiffness properties and stress-strain responses of the sedimentary formation under drained loading conditions

  2. Ocean Sediment Thickness Contours

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Ocean sediment thickness contours in 200 meter intervals for water depths ranging from 0 - 18,000 meters. These contours were derived from a global sediment...

  3. Glider observations and modeling of sediment transport in Hurricane Sandy

    Science.gov (United States)

    Miles, Travis; Seroka, Greg; Kohut, Josh; Schofield, Oscar; Glenn, Scott

    2015-03-01

    Regional sediment resuspension and transport are examined as Hurricane Sandy made landfall on the Mid-Atlantic Bight (MAB) in October 2012. A Teledyne-Webb Slocum glider, equipped with a Nortek Aquadopp current profiler, was deployed on the continental shelf ahead of the storm, and is used to validate sediment transport routines coupled to the Regional Ocean Modeling System (ROMS). The glider was deployed on 25 October, 5 days before Sandy made landfall in southern New Jersey (NJ) and flew along the 40 m isobath south of the Hudson Shelf Valley. We used optical and acoustic backscatter to compare with two modeled size classes along the glider track, 0.1 and 0.4 mm sand, respectively. Observations and modeling revealed full water column resuspension for both size classes for over 24 h during peak waves and currents, with transport oriented along-shelf toward the southwest. Regional model predictions showed over 3 cm of sediment eroded on the northern portion of the NJ shelf where waves and currents were the highest. As the storm passed and winds reversed from onshore to offshore on the southern portion of the domain waves and subsequently orbital velocities necessary for resuspension were reduced leading to over 3 cm of deposition across the entire shelf, just north of Delaware Bay. This study highlights the utility of gliders as a new asset in support of the development and verification of regional sediment resuspension and transport models, particularly during large tropical and extratropical cyclones when in situ data sets are not readily available.

  4. Colonization dynamics of ciliate morphotypes modified by shifting sandy sediments.

    Science.gov (United States)

    Risse-Buhl, Ute; Felsmann, Katja; Mutz, Michael

    2014-08-01

    Sandy stream-bed sediments colonized by a diverse ciliate community are subject to various disturbance regimes. In microcosms, we investigated the effect of sediment shifting on the colonization dynamics of 3 ciliate morphotypes differing in morphology, behavior and feeding strategy. The dynamics of the ciliate morphotypes inhabiting sediment pore water and overlying water were observed at 3 sediment shifting frequencies: (1) stable sediments, (2) periodically shifting sediments such as migrating ripples, and (3) continuously shifting sediments as occurring during scour events of the uppermost sediment. Sediment shifting significantly affected the abundance and growth rate of the ciliate morphotypes. The free-swimming filter feeder Dexiostoma campylum was vulnerable to washout by sediment shifting since significantly higher numbers occurred in the overlying water than in pore water. Abundance of D. campylum only increased in pore water of stable sediments. On the contrary, the vagile grasper feeder Chilodonella uncinata and the sessile filter feeder Vorticella convallaria had positive growth rates and successfully colonized sediments that shifted periodically and continuously. Thus, the spatio-temporal pattern of sediment dynamics acts as an essential factor of impact on the structure, distribution and function of ciliate communities in sand-bed streams.

  5. The bioremediation potential of marine sandy sediment microbiota

    Directory of Open Access Journals (Sweden)

    Dan Răzvan POPOVICIU

    2012-11-01

    Full Text Available The natural microbiota from marine sandy sediments on the Romanian sea coast was tested for resilience in case of hydrocarbon contamination, for estimating the number of (culturable hydrocarbon and lipid oil-degrading microorganisms and for determining the influence of inorganic nitrate and phosphate nutrients on hydrocarbon spill bioremediation process, by microcosm experiments.Results show that hydrocarbon contamination affects the bacteriobenthos both in terms of cell numbers and composition. Bacterial numbers showed a rapid decrease (28% in four days, followed by a relatively fast recovery (two weeks. The pollution favoured the increase of Gram-positive bacterial proportion (from around 25% to 33%Sandy sediment microbiota in both sites studied contained microorganisms able to use mineral or lipid oils as sole carbon sources, usually around 103-104/cm3, with variations according to the sediment grain size and substrate used.The biostimulation experiments showed that, in absence of water dynamism (and, implicitly, an efficient oxygenation, the addition of nitrogen and phosphorus can be ineffective and even inhibit the remediation process, probably due to eutrophication.

  6. Respiration in ocean margin sediments

    NARCIS (Netherlands)

    Andersson, J.H.

    2007-01-01

    The aim of this thesis was the study of respiration in ocean margin sediments and the assessments of tools needed for this purpose. The first study was on the biological pump and global respiration patterns in the deep ocean using an empirical model based on sediment oxygen consumption data. In this

  7. Respiration in ocean margin sediments

    NARCIS (Netherlands)

    Andersson, J.H.

    2007-01-01

    The aim of this thesis was the study of respiration in ocean margin sediments and the assessments of tools needed for this purpose. The first study was on the biological pump and global respiration patterns in the deep ocean using an empirical model based on sediment oxygen consumption data.

  8. Respiration in ocean margin sediments

    OpenAIRE

    Andersson, J.H.

    2007-01-01

    The aim of this thesis was the study of respiration in ocean margin sediments and the assessments of tools needed for this purpose. The first study was on the biological pump and global respiration patterns in the deep ocean using an empirical model based on sediment oxygen consumption data. In this thesis the depth dependence of respiration patterns was modelled using a compiled data set of sediment oxygen consumption rates. We showed that the depth relationship can best be described by a do...

  9. Influence of advective bio-irrigation on carbon and nitrogen cycling in sandy sediments

    OpenAIRE

    Na, T.; Gribsholt, B.; Galaktionov, O. S.; T. Lee; Meysman, F. J. R.

    2008-01-01

    In sandy sediments, the burrow ventilation activity of benthic macrofauna can generate substantial advective flows within the sediment surrounding their burrows. Here we investigated the effects of such advective bio-irrigation on carbon and nitrogen cycling in sandy sediments. To this end, we combined a range of complementary experimental and modelling approaches in a microcosm study of the lugworm Arenicola marina (Polychaeta: Annelida). Bio-irrigation rates were determined using uranine as...

  10. Sediment yield computation of the sandy and gritty area based on the digital watershed model

    Institute of Scientific and Technical Information of China (English)

    LIU; Jiahong; WANG; Guangqian; LI; Tiejian; XUE; Hai

    2006-01-01

    The Yellow River is well known as a sediment-laden river, which is the main reason that it cannot be controlled as easily as other rivers. Many researchers, such as Qian Ning et al., have found that the sediment load of the Yellow River comes mainly from the sandy and gritty area of the Loess Plateau. Therefore, it is very important to simulate the sediment yield in this area. This paper proposes a method to compute the sediment production in the sandy and gritty area based on the digital watershed model. The suggested model is calibrated and validated in the Chabagou basin, which is a small catchment in the study area. Finally, the model simulates the sediment yield of the sandy and gritty area in 1967, 1978, 1983, 1994 and 1997, which represents a high water and high sediment year, a mean water and mean sediment year, a high water and low sediment year, a low water and high sediment year, and a low water and low sediment year separately. The simulation results, including the runoff depth and erosion modulus, can well explain the "low water and high sediment" phenomena in the Yellow River basin. The total amount of the sediment production and its distribution generated by the model is very useful for water and soil conservation in the sandy and gritty area of the Loess Plateau.

  11. Dissolved and Bubble Gas Concentrations in Sandy Surficial Sediments of the West Florida Sand Sheet

    Science.gov (United States)

    2016-06-21

    Dissolved and Bubble Gas Concentrations in Sandy Surficial Sediments of the West Florida Sand Sheet Christopher Martens Dept. of Marine Sciences CB...TITLE AND SUBTITLE Dissolved and Bubble Gas Concentrations in Sandy Surficial Sediments of the West Florida Sand Sheet 5a. CONTRACT NUMBER 5b. GRANT...was noted that there was substantially higher organic material in the shallow troughs of the sand ripples than on the crests. Most of this appears

  12. Comparative study on microphytobenthic pigments of muddy and sandy intertidal sediments of the Tagus estuary

    NARCIS (Netherlands)

    Cartaxana, P; Mendes, CR; van Leeuwe, MA; Brotas, [No Value

    2006-01-01

    The abundance and distribution of microphytobenthic pigments determined by HPLC (chlorophylls and carotenoids) were compared between muddy and sandy sediments of the Tagus estuary (Portugal). In the two types of sediment, with similar periods of illuminated emersion, chlorophyll a concentrations on

  13. Comparative study on microphytobenthic pigments of muddy and sandy intertidal sediments of the Tagus estuary

    NARCIS (Netherlands)

    Cartaxana, P; Mendes, CR; van Leeuwe, MA; Brotas, [No Value

    2006-01-01

    The abundance and distribution of microphytobenthic pigments determined by HPLC (chlorophylls and carotenoids) were compared between muddy and sandy sediments of the Tagus estuary (Portugal). In the two types of sediment, with similar periods of illuminated emersion, chlorophyll a concentrations on

  14. Comparative study on microphytobenthic pigments of muddy and sandy intertidal sediments of the Tagus estuary

    Science.gov (United States)

    Cartaxana, P.; Mendes, C. R.; van Leeuwe, M. A.; Brotas, V.

    2006-01-01

    The abundance and distribution of microphytobenthic pigments determined by HPLC (chlorophylls and carotenoids) were compared between muddy and sandy sediments of the Tagus estuary (Portugal). In the two types of sediment, with similar periods of illuminated emersion, chlorophyll a concentrations on a per area basis (mg m -2) were comparable (down to 2 mm). Pigment analysis also revealed similar microphytobenthic communities in terms of algal classes. Diatoms were the dominant microalgae, but cyanophytes, euglenophytes and phanerogam debris were also present. For both muddy and sandy sediments, microphytobenthic biomass showed a high level of variability both within and between two consecutive years. Microphytobenthos was highly stratified in the mud, with most of the chlorophyll a occurring in the top 500 μm. In the sand, relatively constant concentrations were found throughout the sediment profile down to 3 mm. This is probably related to deeper light penetration in sandy sediment and/or increased physical mixing caused by invertebrate activity or overlying currents, leading to the burial of an important fraction of the microphytobenthic cells. Differences observed in the intensity of sediment coloration of muddy and sandy sediments might have resulted from the different vertical distribution of benthic biomass.

  15. Morphosedimentary evolution of carbonate sandy beaches at decadal scale : case study in Reunion Island , Indian Ocean

    Science.gov (United States)

    Mahabot, Marie-Myriam; Pennober, Gwenaelle; Suanez, Serge; Troadec, Roland; Delacourt, Christophe

    2017-04-01

    Global change introduce a lot of uncertainties concerning future trajectory of beaches by directly or indirectly modifying major driving factors. An improved understanding of the past shoreline evolution may help for anticipate future coastline response. However, in tropical environment, studies concerning carbonate beaches dynamics are scarce compared to open sandy beaches. Consequently, coral reef protected beaches morphological adjustment is still poorly understood and long-term evolution rate are poorly quantified in these specific environment. In this context, La Reunion Island, insular department of France located in Indian Ocean, constitute a favoured laboratory. This high volcanic island possesses 25 km of carbonate beaches which experience hydrodynamic forcing specific from tropical environment: cyclonic swell during summer and long period swell during winter. Because of degraded coral reef health and high anthropogenic pressure, 50% of the beaches are in erosion since 1970s. Beach survey has been conducted since 1990s by scientist and are now encompassed as pilot site within a French observatory network which guarantee long-term survey with high resolution observational techniques. Thus, La Reunion Island is one of the rare carbonate beach to be surveyed since 20 years. This study aims to examined and quantify beach response at decadal scale on carbonate sandy beaches of Reunion Island. The study focus on 12 km of beaches from Cap Champagne to the Passe de Trois-Bassins. The analyze of 15 beach profile data originated from historical and DGPS beach topographic data confirm long term trend to erosion. Sediment lost varies between 0.5 and 2 m3.yr-1 since 1998. However longshore current have led to accretion of some part of beach compartment with rate of 0.7 to 1.6 m3.yr-1. Wave climate was examined from in-situ measurement over 15 years and show that extreme waves associated with tropical cyclones and long period swell play a major role in beach dynamics

  16. 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.

  17. 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.

  18. Enhanced benthic activity in sandy sublittoral sediments: Evidence from 13C tracer experiments

    NARCIS (Netherlands)

    Bühring, S.I.; Ehrenhauss, S.; Kamp, A.; Moodley, L.; Prof. Witte, U.

    2006-01-01

    In situ and on-board pulse-chase experiments were carried out on a sublittoral fine sand in the German Bight (southern North Sea) to investigate the hypothesis that sandy sediments are highly active and have fast turnover rates. To test this hypothesis, we conducted a series of experiments where we

  19. Importance of phytodetritus and microphytobenthos for heterotrophs in a shallow subtidal sandy sediment

    NARCIS (Netherlands)

    Evrard, V.; Huettel, M.; Cook, P.L.M.; Soetaert, K.; Heip, C.H.R.; Middelburg, J.J.

    2012-01-01

    The relative importance of allochthonous phytodetritus deposition and autochthonous microphytobenthos (MPB) production for benthic consumers in an organic carbon (C-org)-poor sandy sediment was assessed using a C-13-stable isotope natural abundance study combined with a dual C-13-tracer addition app

  20. Inner-shelf ocean dynamics and seafloor morphologic changes during Hurricane Sandy

    Science.gov (United States)

    Warner, John C.; Schwab, William C.; List, Jeffrey H.; Safak, Ilgar; Liste, Maria; Baldwin, Wayne

    2017-04-01

    Hurricane Sandy was one of the most destructive hurricanes in US history, making landfall on the New Jersey coast on October 30, 2012. Storm impacts included several barrier island breaches, massive coastal erosion, and flooding. While changes to the subaerial landscape are relatively easily observed, storm-induced changes to the adjacent shoreface and inner continental shelf are more difficult to evaluate. These regions provide a framework for the coastal zone, are important for navigation, aggregate resources, marine ecosystems, and coastal evolution. Here we provide unprecedented perspective regarding regional inner continental shelf sediment dynamics based on both observations and numerical modeling over time scales associated with these types of large storm events. Oceanographic conditions and seafloor morphologic changes are evaluated using both a coupled atmospheric-ocean-wave-sediment numerical modeling system that covered spatial scales ranging from the entire US east coast (1000 s of km) to local domains (10 s of km). Additionally, the modeled response for the region offshore of Fire Island, NY was compared to observational analysis from a series of geologic surveys from that location. The geologic investigations conducted in 2011 and 2014 revealed lateral movement of sedimentary structures of distances up to 450 m and in water depths up to 30 m, and vertical changes in sediment thickness greater than 1 m in some locations. The modeling investigations utilize a system with grid refinement designed to simulate oceanographic conditions with progressively increasing resolutions for the entire US East Coast (5-km grid), the New York Bight (700-m grid), and offshore of Fire Island, NY (100-m grid), allowing larger scale dynamics to drive smaller scale coastal changes. Model results in the New York Bight identify maximum storm surge of up to 3 m, surface currents on the order of 2 ms-1 along the New Jersey coast, waves up to 8 m in height, and bottom stresses

  1. Inner-shelf ocean dynamics and seafloor morphologic changes during Hurricane Sandy

    Science.gov (United States)

    Warner, John C.; Schwab, William C.; List, Jeffrey; Safak, Ilgar; Liste, Maria; Baldwin, Wayne E.

    2017-01-01

    Hurricane Sandy was one of the most destructive hurricanes in US history, making landfall on the New Jersey coast on Oct 30, 2012. Storm impacts included several barrier island breaches, massive coastal erosion, and flooding. While changes to the subaerial landscape are relatively easily observed, storm-induced changes to the adjacent shoreface and inner continental shelf are more difficult to evaluate. These regions provide a framework for the coastal zone, are important for navigation, aggregate resources, marine ecosystems, and coastal evolution. Here we provide unprecedented perspective regarding regional inner continental shelf sediment dynamics based on both observations and numerical modeling over time scales associated with these types of large storm events. Oceanographic conditions and seafloor morphologic changes are evaluated using both a coupled atmospheric-ocean-wave-sediment numerical modeling system and observation analysis from a series of geologic surveys and oceanographic instrument deployments focused on a region offshore of Fire Island, NY. The geologic investigations conducted in 2011 and 2014 revealed lateral movement of sedimentary structures of distances up to 450 m and in water depths up to 30 m, and vertical changes in sediment thickness greater than 1 m in some locations. The modeling investigations utilize a system with grid refinement designed to simulate oceanographic conditions with progressively increasing resolutions for the entire US East Coast (5-km grid), the New York Bight (700-m grid), and offshore of Fire Island, NY (100-m grid), allowing larger scale dynamics to drive smaller scale coastal changes. Model results in the New York Bight identify maximum storm surge of up to 3 m, surface currents on the order of 2 ms-1 along the New Jersey coast, waves up to 8 m in height, and bottom stresses exceeding 10 Pa. Flow down the Hudson Shelf Valley is shown to result in convergent sediment transport and deposition along its axis

  2. Microplastics elutriation from sandy sediments: A granulometric approach.

    Science.gov (United States)

    Kedzierski, Mikaël; Le Tilly, Véronique; Bourseau, Patrick; Bellegou, Hervé; César, Guy; Sire, Olivier; Bruzaud, Stéphane

    2016-06-15

    Although relatively easy to extract in the marine environment, microplastics are very difficult to recover when they are trapped in sediments. The elutriation column is one of the best tools currently available for extracting plastics from sediment, but with a high sand recovery yield. This study aims to address the following questions: (i) is it possible to use a sedimentological approach to limit the sand recovery? (ii) does the extraction velocity of the sand and plastic particles vary according to density and granulometry? (iii) what is the relative recovery efficiency obtained for dense polymer particles mixed with marine sand? Based on a new granulometric classification, different plastic particle-size fractions are defined. Their extraction velocities are experimentally determined on particles of sediment and different plastics (PA, PVC). The particle recovery experiments indicate that it is possible to extract >90% of dense plastic particles in cases of negligible sand recovery.

  3. Hydrodynamic Stresses Driving Pore Pressure Changes in Sandy Coastal Sediments

    Science.gov (United States)

    1997-09-30

    Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be...SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as Report (SAR) 18. NUMBER OF PAGES 2 19a. NAME OF RESPONSIBLE PERSON a. REPORT...nature of the sediment properties (Mei and Foda , 1981, Bennett et al. 1982, 1992a and b). A serious deficiency exist in the available in situ data bases

  4. Enhanced benthic activity in sandy sublittoral sediments: Evidence from 13C tracer experiments

    DEFF Research Database (Denmark)

    Bühring, Solveig I.; Ehrenhauss, Sandra; Kamp, Anja

    2006-01-01

    investigated the pathway of settling particulate organic carbon through the benthic food web. The diatom Ditylum brightwellii was labelled with the stable carbon isotope 13C and injected into incubation chambers. On-board incubations lasted 12, 30 and 132 h, while the in situ experiment was incubated for 32 h......In situ and on-board pulse-chase experiments were carried out on a sublittoral fine sand in the German Bight (southern North Sea) to investigate the hypothesis that sandy sediments are highly active and have fast turnover rates. To test this hypothesis, we conducted a series of experiments where we....... The study revealed a stepwise short-term processing of a phytoplankton bloom settling on a sandy sediment. After the 12 h incubation, the largest fraction of recovered carbon was in the bacteria (62%), but after longer incubation times (30 and 32 h in situ) the macrofauna gained more importance (15 and 48...

  5. Experimental study on subharmonic and ultraharmonic acoustic waves in water-saturated sandy sediment.

    Science.gov (United States)

    Kim, Byoung-Nam; Lee, Kang Il; Yoon, Suk Wang

    2007-04-01

    Experimental observations of the subharmonic and ultraharmonic acoustic waves in water-saturated sandy sediment are reported in this paper. Acoustic pressures of both nonlinear acoustic waves strongly depend on the driving acoustic pressure at a transducer. The first ultraharmonic wave reaches a saturation value as the driving acoustic pressure increases. The acoustic pressure levels of both nonlinear acoustic waves exhibit some fluctuations in comparison with that of the primary acoustic wave as the receiving distance of hydrophone increases in sediment. The subharmonic and the ultraharmonic phenomena in this study show close resemblance to those produced in bubbly water.

  6. Groundwater recharge measurements in gravel sandy sediments with monolith lysimeter

    Science.gov (United States)

    Bracic Zeleznik, Branka; Souvent, Petra; Cencur Curk, Barbara; Zupanc, Vesna

    2013-04-01

    Ljubljana field aquifer is recharging through precipitation and the river Sava, which has the snow-rain flow regime. The sediments of the aquifer have high permeability and create fast flow as well as high regeneration of the dynamic reserves of the Ljubljana field groundwater resource. Groundwater recharge is vulnerable to climate change and it is very important for drinking water supply management. Water stored in the soil and less permeable layers is important for water availability under extreme weather conditions. Measurements of water percolation through the vadose zone provide important input for groundwater recharge assessment and estimation of contaminant migration from land surface to the groundwater. Knowledge of the processes governing groundwater recharge in the vadose zone is critical to understanding the overall hydrological cycle and quantifying the links between land uses and groundwater quantity and quality. To improve the knowledge on water balance for Ljubljana field aquifer we establish a lysimeter for measurements of processes in unsaturated zone in well field Kleče. The type of lysimeter is a scientific lysimeter designed to solve the water balance equation by measuring the mass of the lysimeter monolith as well as that of outflow tank with high accuracy and high temporal resolution. We evaluated short period data, however the chosen month demonstrates weather extremes of the local climate - relatively dry periods, followed by high precipitation amount. In time of high water usage of vegetation only subsequent substantial precipitation events directly results in water flow towards lower layers. At the same time, gravely layers of the deeper parts of the unsaturated zone have little or no capacity for water retention, and in the event that water line leaves top soil, water flow moves downwards fairly quickly. On one hand this confirms high recharge capacity of Ljubljana field aquifer from precipitation on green areas; on the other hand it

  7. First-Year Downstream Sediment Budget Following the Marmot Dam Removal from the Sandy River, Oregon

    Science.gov (United States)

    Podolak, C. J.; Wilcock, P. R.; Pittman, A.

    2008-12-01

    The October 2007 removal of the Marmot Dam, from the Sandy River, OR, provides an opportunity to assess the impact of increased sediment flux on a river channel. The Sandy River drains the west flank of Mt Hood and typically carries a large load of sand and gravel. The 14-meter-tall dam impounded over 750,000 m3 of sediment, only a small amount of which was removed during the decommissioning. Using a one- dimensional modeling approach, it was assessed that the river could transport the accumulated sediment without large adverse impacts downstream of the dam (Cui et al, 2008 - abstract submitted). In order to observe the actual changes to the river due to the dam removal and to test the modeled predictions, a significant monitoring effort has be in place on the Sandy River including bedload and suspended load measurements, discharge measurements, high-fidelity topographic surveys, repeat photography, multiple airborne LIDAR flights, long profile surveys, as well as mapping and characterizing the grain sizes throughout several reaches downstream of the dam. A key step in the quest to describe and predict the spatial distribution of the sediment throughout the downstream reach is to first account for all the sediment (both stored in the reservoir and supplied from upstream). Here, we examine the transport and deposition downstream of the dam through a 2-fraction sediment budget approach using the former dam as the upstream limit of the reach and choosing a the mouth of a bedrock gorge 7 km below the dam site as the downstream limit. Suspended sediment and bedload measurements taken by the USGS just below the dam site (Major et al, 2008 - abstract submitted) are combined with suspended sediment and bedload measurements collected just below the mouth of the gorge and the annual hydrograph to define the sediment fluxes into and out of the reach. Repeat surveys in the reach below the dam (Wallick et al, 2008 - abstract submitted) provide the measure of change in storage

  8. Ocean surface waves in Hurricane Ike (2008) and Superstorm Sandy (2012): Coupled model predictions and observations

    Science.gov (United States)

    Chen, Shuyi S.; Curcic, Milan

    2016-07-01

    Forecasting hurricane impacts of extreme winds and flooding requires accurate prediction of hurricane structure and storm-induced ocean surface waves days in advance. The waves are complex, especially near landfall when the hurricane winds and water depth varies significantly and the surface waves refract, shoal and dissipate. In this study, we examine the spatial structure, magnitude, and directional spectrum of hurricane-induced ocean waves using a high resolution, fully coupled atmosphere-wave-ocean model and observations. The coupled model predictions of ocean surface waves in Hurricane Ike (2008) over the Gulf of Mexico and Superstorm Sandy (2012) in the northeastern Atlantic and coastal region are evaluated with the NDBC buoy and satellite altimeter observations. Although there are characteristics that are general to ocean waves in both hurricanes as documented in previous studies, wave fields in Ike and Sandy possess unique properties due mostly to the distinct wind fields and coastal bathymetry in the two storms. Several processes are found to significantly modulate hurricane surface waves near landfall. First, the phase speed and group velocities decrease as the waves become shorter and steeper in shallow water, effectively increasing surface roughness and wind stress. Second, the bottom-induced refraction acts to turn the waves toward the coast, increasing the misalignment between the wind and waves. Third, as the hurricane translates over land, the left side of the storm center is characterized by offshore winds over very short fetch, which opposes incoming swell. Landfalling hurricanes produce broader wave spectra overall than that of the open ocean. The front-left quadrant is most complex, where the combination of windsea, swell propagating against the wind, increasing wind-wave stress, and interaction with the coastal topography requires a fully coupled model to meet these challenges in hurricane wave and surge prediction.

  9. 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.

  10. A new method for measuring bioturbation rates in sandy tidal flat sediments based on luminescence dating

    DEFF Research Database (Denmark)

    Madsen, Anni Tindahl; Murray, Andrew S.; jain, A

    2011-01-01

    The rates of post-depositional mixing by bioturbation have been investigated using Optically Stimulated Luminescence (OSL) dating in two sediment cores (BAL2 and BAL5), retrieved from a sandy tidal flat in the Danish part of the Wadden Sea. A high-resolution chronology, consisting of thirty-six OSL...... ages with ages ranging between 2 4 and 410 20 years, is presented. Slices of sediment (1e2 cm thick) have been dated at least every 5 cm, and from these data mixing depths of 20 cm and 22 cm (BAL5 and BAL2, respectively) are readily identified. Below the mixing zone there is a significant decrease....... The significant change in sedimentation rates at BAL5 may indicate an offset in OSL age of up to 620 years. This paper uses a simple conceptual model for vertical mixing in which all the sediment excreted at the surface by lugworms is assumed to be completely reset before being re-incorporated in the sediment...

  11. A new method for measuring bioturbation rates in sandy tidal flat sediments based on luminescence dating

    DEFF Research Database (Denmark)

    Madsen, Anni Tindahl; Murray, Andrew S.; jain, A

    2011-01-01

    The rates of post-depositional mixing by bioturbation have been investigated using Optically Stimulated Luminescence (OSL) dating in two sediment cores (BAL2 and BAL5), retrieved from a sandy tidal flat in the Danish part of the Wadden Sea. A high-resolution chronology, consisting of thirty-six OSL...... ages with ages ranging between 2 4 and 410 20 years, is presented. Slices of sediment (1e2 cm thick) have been dated at least every 5 cm, and from these data mixing depths of 20 cm and 22 cm (BAL5 and BAL2, respectively) are readily identified. Below the mixing zone there is a significant decrease....... The significant change in sedimentation rates at BAL5 may indicate an offset in OSL age of up to 620 years. This paper uses a simple conceptual model for vertical mixing in which all the sediment excreted at the surface by lugworms is assumed to be completely reset before being re-incorporated in the sediment...

  12. A new method for measuring bioturbation rates in sandy tidal flat sediments based on luminescence dating

    DEFF Research Database (Denmark)

    Madsen, Anni T.; Murray, Andrew S.; Jain, Mayank

    2011-01-01

    The rates of post-depositional mixing by bioturbation have been investigated using Optically Stimulated Luminescence (OSL) dating in two sediment cores (BAL2 and BAL5), retrieved from a sandy tidal flat in the Danish part of the Wadden Sea. A high-resolution chronology, consisting of thirty-six OSL...... ages with ages ranging between 2 ± 4 and 410 ± 20 years, is presented. Slices of sediment (1–2 cm thick) have been dated at least every 5 cm, and from these data mixing depths of 20 cm and 22 cm (BAL5 and BAL2, respectively) are readily identified. Below the mixing zone there is a significant decrease....... The significant change in sedimentation rates at BAL5 may indicate an offset in OSL age of up to 620 years. This paper uses a simple conceptual model for vertical mixing in which all the sediment excreted at the surface by lugworms is assumed to be completely reset before being re-incorporated in the sediment...

  13. MOBILIZATION AND CHARACTERIZATION OF COLLOIDS GENERATED FROM CEMENT LEACHATES MOVING THROUGH A SRS SANDY SEDIMENT

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.; Roberts, K.; Kaplan, D.; Seaman, J.

    2011-09-20

    Naturally occurring mobile colloids are ubiquitous and are involved in many important processes in the subsurface zone. For example, colloid generation and subsequent mobilization represent a possible mechanism for the transport of contaminants including radionuclides in the subsurface environments. For colloid-facilitated transport to be significant, three criteria must be met: (1) colloids must be generated; (2) contaminants must associate with the colloids preferentially to the immobile solid phase (aquifer); and (3) colloids must be transported through the groundwater or in subsurface environments - once these colloids start moving they become 'mobile colloids'. Although some experimental investigations of particle release in natural porous media have been conducted, the detailed mechanisms of release and re-deposition of colloidal particles within natural porous media are poorly understood. Even though this vector of transport is known, the extent of its importance is not known yet. Colloid-facilitated transport of trace radionuclides has been observed in the field, thus demonstrating a possible radiological risk associated with the colloids. The objective of this study was to determine if cementitious leachate would promote the in situ mobilization of natural colloidal particles from a SRS sandy sediment. The intent was to determine whether cementitious surface or subsurface structure would create plumes that could produce conditions conducive to sediment dispersion and mobile colloid generation. Column studies were conducted and the cation chemistries of influents and effluents were analyzed by ICP-OES, while the mobilized colloids were characterized using XRD, SEM, EDX, PSD and Zeta potential. The mobilization mechanisms of colloids in a SRS sandy sediment by cement leachates were studied.

  14. Sandy inland braidplain deposition with local aeolian sedimentation in the lower and middle parts of the buntsandstein and sandy coastal braidplain deposition in the topmost zechstein in the sudetes (Lower Silesia, Poland)

    Science.gov (United States)

    Mroczkowski, Jerzy; Mader, Detlef

    restricted to a narrow range between the end members of a pebbly to sandy highly-braided stream system representing the coarser facies tracts and a sandy to pebbly moderately-braided river complex representing the finer facies tracts. The evolution in time and space is characterized by mainly random lateral shifting and vertical overlapping of two coexistent fluvial styles within an irregularly zoned braidplain lacking organization of the two facies realms into discrete belts. Palaeogeographically, the two end members of the spectrum of fluvial style may sometimes even be equivalent to a more proximal and a more distal facies belt. In terms of position within the general depositional framework of the whole Mid-European Triassic Basin, the inland braidplain of the Sudetes is situated within the transitional reach from the proximal zone to the medial zone I. Based on comparative interpretation of the topmost Zechstein beds in the region of Chemsko and Kochanów in the Intra Sudetic Trough, the overall depositional history in parts of the area comprises the passage from marine carbonate sedimentation via a narrow coastal fluvial braidplain with pedogenesis in semi-arid climate at the margin of the Zechstein sea to an extensive inland fluvial braidplain with probably local aeolian deposition in almost arid climate in the Buntsandstein. Comparative evaluation of the marginal Zechstein in the Intra Sudetic Trough in Lower Silesia in Poland and of the marginal Lower Muschelkalk in Luxembourg allows to assess the Buntsandstein succession near the borders of the basin as an overall symmetrical major clastic wedge prograding into the depositional area with retreat of the Zechstein ocean and retrograding from the basin with transgression of the Muschelkalk sea. In view of a general model of continental sedimentation, the alluvial marginal belt of the Zechstein sea in Lower Silesia in Poland represents a predecessor, and the fluvial marginal seam of the Muschelkalk ocean in Luxembourg

  15. Influences of microbial activity and sediment disturbance on hyporheic exchange in sandy sediments

    Science.gov (United States)

    Mendoza-Lera, C.; Mutz, M.

    2012-04-01

    Besides the vertical hydraulic gradient, sediment permeability is the main controlling factor of water exchange across the stream bed. Reduction of permeability by microbial activity is reported from unidirectional percolated sediment columns. We investigated effects of algal and bacterial activity on hyporheic exchange (vertical water flux, VWF) under semi-natural stream conditions in 16 outdoor sand-bed flumes during 30 day. Variability of bedform was considered by 8 flumes having plane-bed and 8 flumes ripple-bed. To gain information on the relative significance of algae and heterotrophic microorganisms, half of the flumes were operated under constant dark conditions (no-light flumes), while the others were exposed to daylight. After 21 days, the upper 2 cm of the sediments was manually disturbed simulating moderate sediment dynamics which frequently occurs in natural sand-bed streams. VWF was measured by tracing loss of uranine from the water column while flumes were operating in re-circulating mode. Algae and bacterial abundance, organic matter, and CaCO3 content in sediments were determined. Sediment potential respiration (SPR) was measured in flow through respiration chambers and oxygen bubbles from primary production were sampled. As expected, initial VWF was higher in ripple-bed. After 13 days, VWF was completely inhibited in both plane and ripple-bed flumes under daylight conditions. In no-light flumes reduction of VWF was moderate. Microbial precipitation of calcium carbonate and production of oxygen bubbles in the uppermost sediments blocked the pore space. After 3 weeks, abundance and biomass of algae and SPR in the upper 2 cm of sediment were higher in daylight flumes than in no-light flumes, while bacterial abundance was higher in no-light flumes. The sediment disturbance at day 21 released the oxygen bubbles increased bed permeability and therefore restored VWF to initial rates in day-light flumes. SPR was unaffected by the sediment disturbance. In

  16. Sediment chemoautotrophy in the coastal ocean

    Science.gov (United States)

    Vasquez-Cardenas, Diana; Meysman, Filip J. R.; van Breugel, Peter; Boschker, Henricus T. S.

    2016-04-01

    A key process in the biogeochemistry of coastal sediments is the reoxidation of reduced intermediates formed during anaerobic mineralization which in part is performed by chemoautotrophic micro-organisms. These microbes fix inorganic carbon using the energy derived from reoxidation reactions and in doing so can fix up to 32% of the CO2 released by mineralization. However the importance and distribution of chemoautotrophy has not been systematically investigated in these environments. To address these issues we surveyed nine coastal sediments by means of bacterial biomarker analysis (phospholipid derived fatty acids) combined with stable isotope probing (13C-bicarbonate) which resulted in an almost doubling of the number of observations on coastal sedimentary chemoautotrophy. Firstly, sediment chemoautotrophy rates from this study and rates compiled from literature (0.07 to 36 mmol C m-2 d-1) showed a power-law relation with benthic oxygen uptake (3.4 to 192 mmol O2 m-2 d-1). Benthic oxygen uptake was used as a proxy for carbon mineralization to calculate the ratio of the CO2 fixed by chemoautotrophy over the total CO2 released through mineralization. This CO2 efficiency was 3% in continental shelf, 9% in nearshore and 21% in salt marsh sediments. These results suggest that chemoautotrophy plays an important role in C-cycling in reactive intertidal sediments such as salt marshes rather than in the organic-poor, permeable continental shelf sediments. Globally in the coastal ocean our empirical results show that chemoautotrophy contributes ˜0.05 Pg C y-1 which is four times less than previous estimates. Secondly, five coastal sediment regimes were linked to the depth-distribution of chemoautotrophy: 1) permeable sediments dominated by advective porewater transport, 2) bioturbated sediments, and cohesive sediments dominated by diffusive porewater transport characterized by either 3) canonical sulfur oxidation, 4) nitrate-storing Beggiatoa, or 5) electrogenic sulfur

  17. Effects of deposition of heavy-metal-polluted harbor mud on microbial diversity and metal resistance in sandy marine sediments

    DEFF Research Database (Denmark)

    Toes, Ann-Charlotte M; Finke, Niko; Kuenen, J Gijs;

    2008-01-01

    Deposition of dredged harbor sediments in relatively undisturbed ecosystems is often considered a viable option for confinement of pollutants and possible natural attenuation. This study investigated the effects of deposition of heavy-metal-polluted sludge on the microbial diversity of sandy...

  18. A laboratory experiment of intact polar lipid degradation in sandy sediments

    Directory of Open Access Journals (Sweden)

    J. Logemann

    2011-03-01

    Full Text Available Intact polar lipids (IPLs are considered biomarkers for living biomass. Their degradation in marine sediments, however, is poorly understood and complicates interpretation of their occurrence in geological samples. To investigate the turnover of IPLs, a degradation experiment with anoxic sandy sediments from the North Sea was conducted. Intact cells of two organisms that do not naturally occur in North Sea sediments were chosen as IPL sources: (i Saccharomyces cerevisiae, representative for ester-bound acyl lipids that also occur in Bacteria, and (ii the archaeon Haloferax volcanii, representative for ether-bound isoprenoid lipids. Surprisingly, IPLs with phosphoester-bound head groups showed approximately the same degradation rate as IPLs with glycosidic head groups. Furthermore, the results indicate a relatively fast degradation of S. cerevisiae IPLs with ester-bound moieties (analogs of bacterial membrane lipids and no significant degradation of archaeal IPLs with ether-bound moieties. Pore water and 16S rRNA-based DGGE analysis showed only a minor influence of the IPL source on microbial metabolism and community profiles. Due to our results, the IPL-based quantification of Archaea and Bacteria should be interpreted with caution.

  19. A laboratory experiment of intact polar lipid degradation in sandy sediments

    Directory of Open Access Journals (Sweden)

    J. Logemann

    2011-09-01

    Full Text Available Intact polar lipids (IPLs are considered biomarkers for living biomass. Their degradation in marine sediments, however, is poorly understood and complicates interpretation of their occurrence in geological samples. To investigate the turnover of IPLs, a degradation experiment with anoxic sandy sediments from the North Sea was conducted. Intact cells of two organisms that do not naturally occur in North Sea sediments were chosen as IPL sources: (i Saccharomyces cerevisiae, representative for ester-bound acyl lipids that also occur in Bacteria, and (ii the archaeon Haloferax volcanii, representative for ether-bound isoprenoid lipids. Surprisingly, IPLs with phosphoester-bound head groups showed approximately the same degradation rate as IPLs with glycosidic head groups. Furthermore, the results indicate a relatively fast degradation of S. cerevisiae IPLs with ester-bound moieties (analogs of bacterial membrane lipids and no significant degradation of archaeal IPLs with ether-bound moieties. Pore water and 16S rRNA-based DGGE analysis showed only a minor influence of the IPL source on microbial metabolism and community profiles. Due to our results, the IPL-based quantification of Archaea and Bacteria should be interpreted with caution.

  20. Volcanogenic sediments in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.

    ….) and lithic fragments. The secondary component is diagenetic alteration of primary components then transferred to Fe-rich smectite, palagonite and zeolites. Volcanism in different tectonic settings contributes tephra to marine environments. In the Indian... Ocean volcanogenic components are derived from MOR volcanism, hot spot volcanism (ex: Reunion and Kerguelen hot spots) and subduction related volcanism in the Indonesian arc. During IIOE large number of sediment cores was retrieved in the Arabian...

  1. Transport behavior of groundwater protozoa and protozoan-sized microspheres in sandy aquifer sediments

    Science.gov (United States)

    Harvey, R.W.; Kinner, N.E.; Bunn, A.; MacDonald, D.; Metge, D.

    1995-01-01

    Transport behaviors of unidentified flagellated protozoa (flagellates) and flagellate-sized carboxylated microspheres in sandy, organically contaminated aquifer sediments were investigated in a small-scale (1 to 4-m travel distance) natural-gradient tracer test on Cape Cod and in flow-through columns packed with sieved (0.5-to 1.0-mm grain size) aquifer sediments. The minute (average in situ cell size, 2 to 3 ??m) flagellates, which are relatively abundant in the Cape Cod aquifer, were isolated from core samples, grown in a grass extract medium, labeled with hydroethidine (a vital eukaryotic stain), and coinjected into aquifer sediments along with bromide, a conservative tracer. The 2-??m flagellates appeared to be near the optimal size for transport, judging from flowthrough column experiments involving a polydispersed (0.7 to 6.2 ??m in diameter) suspension of carboxylated microspheres. However, immobilization within the aquifer sediments accounted for a log unit reduction over the first meter of travel compared with a log unit reduction over the first 10 m of travel for indigenous, free-living groundwater bacteria in earlier tests. High rates of flagellate immobilization in the presence of aquifer sediments also was observed in the laboratory. However, immobilization rates for the laboratory-grown flagellates (initially 4 to 5 ??m) injected into the aquifer were not constant and decreased noticeably with increasing time and distance of travel. The decrease in propensity for grain surfaces was accompanied by a decrease in cell size, as the flagellates presumably readapted to aquifer conditions. Retardation and apparent dispersion were generally at least twofold greater than those observed earlier for indigenous groundwater bacteria but were much closer to those observed for highly surface active carboxylated latex microspheres. Field and laboratory results suggest that 2- ??m carboxylated microspheres may be useful as analogs in investigating several abiotic

  2. Temporal variations in microbial activities and carbon turnover in subtidal sandy sediments

    Science.gov (United States)

    Böer, S. I.; Arnosti, C.; van Beusekom, J. E. E.; Boetius, A.

    2009-07-01

    Temporal dynamics and vertical patterns in bacterial abundances and activities were studied in a shallow subtidal sand flat in the Sylt-Rømø Basin (North Frisian Wadden Sea, Germany). Extracellular enzymatic activities, bacterial carbon production and community respiration showed strong (factor of 4-5) temporal variations that were mostly related to seasonal temperature change and to changes in substrate availability. These temporal patterns in enzymatic activity were barely reflected in bacterial (200-400 mmol C m-2) and microphytobenthic biomass (800-1500 mmol C m-2) or the sedimentary carbohydrate inventory (1300-2900 mmol C m-2), suggesting that grazing controls the standing stocks of the microphytobenthic and bacterial assemblages. Despite their exposure to strong hydrodynamic forces such as tidal currents and wind-induced wave surge, the subtidal sandy sediments showed persistent vertical gradients in bacterial abundances, carbon production and extracellular enzymatic activities at all times. The vertical distribution of these parameters was tightly coupled to that of the microphytobenthos, dominated by diatoms. Despite the low organic carbon content typical for surge-exposed sandy sediments, high extracellular enzymatic activities and bacterial carbon production rates indicate a very active heterotrophic bacterial community, with a gross secondary productivity of 30-180 mmol C m-2, and a biomass turnover time of 2-18 days. Our data suggest that this high activity is supported by the rapid flux of carbohydrates from microphytobenthic primary productivity. Accordingly, the potential activities of enzymes hydrolyzing carbohydrates cover most of the total bacterial carbon demand during all seasons.

  3. Temporal variations in microbial activities and carbon turnover in subtidal sandy sediments

    Directory of Open Access Journals (Sweden)

    A. Boetius

    2009-07-01

    Full Text Available Temporal dynamics and vertical patterns in bacterial abundances and activities were studied in a shallow subtidal sand flat in the Sylt-Rømø Basin (North Frisian Wadden Sea, Germany. Extracellular enzymatic activities, bacterial carbon production and community respiration showed strong (factor of 4–5 temporal variations that were mostly related to seasonal temperature change and to changes in substrate availability. These temporal patterns in enzymatic activity were barely reflected in bacterial (200–400 mmol C m−2 and microphytobenthic biomass (800–1500 mmol C m−2 or the sedimentary carbohydrate inventory (1300–2900 mmol C m−2, suggesting that grazing controls the standing stocks of the microphytobenthic and bacterial assemblages. Despite their exposure to strong hydrodynamic forces such as tidal currents and wind-induced wave surge, the subtidal sandy sediments showed persistent vertical gradients in bacterial abundances, carbon production and extracellular enzymatic activities at all times. The vertical distribution of these parameters was tightly coupled to that of the microphytobenthos, dominated by diatoms. Despite the low organic carbon content typical for surge-exposed sandy sediments, high extracellular enzymatic activities and bacterial carbon production rates indicate a very active heterotrophic bacterial community, with a gross secondary productivity of 30–180 mmol C m−2, and a biomass turnover time of 2–18 days. Our data suggest that this high activity is supported by the rapid flux of carbohydrates from microphytobenthic primary productivity. Accordingly, the potential activities of enzymes hydrolyzing carbohydrates cover most of the total bacterial carbon demand during all seasons.

  4. The effect of the dominant polychaete Scolelepis squamata on nematode colonisation in sandy beach sediments: An experimental approach

    Science.gov (United States)

    Maria, Tatiana F.; Esteves, André M.; Vanaverbeke, Jan; Vanreusel, Ann

    2011-09-01

    The effect of an abundant sandy beach polychaete, Scolelepis squamata, on the colonisation of defaunated sediments by marine nematodes indicates that sandy beach fauna can be partially controlled by biological interactions within and across size groups. Experimental cores, equipped with windows allowing infaunal colonisation, were filled with defaunated sandy beach sediment containing two different treatments with and without S. squamata. These cores were inserted into microcosms filled with sediment with indigenous meiofauna collected from the field. The treatments were incubated in the laboratory at ambient temperature and salinity for 2, 7, 14 and 21 days, in order to follow the colonisation process of the defaunated sediments by the indigenous nematode fauna over time. Nematodes initially colonised both treatments, with abundances of up to 10% of the densities in the control; after 2 weeks, nematode densities in the cores without S. squamata surpassed the control densities. Nematode assemblages in both treatments were not species rich, and also differed in composition from the natural assemblages. The most successful colonising species, Enoplolaimus litoralis, was rare in the surrounding sediment, suggesting that colonisation was determined by species-specific characteristics such as body size, motility and feeding strategy. Initially the presence of macrofauna did not affect the nematode community composition, but after 2 weeks of the experiment, the presence of the polychaete seemed to facilitate the earlier establishment of non-opportunistic species.

  5. Sound speed in air-filled sand and 03ine shallow-layer sandy sediments

    Institute of Scientific and Technical Information of China (English)

    QIAN Zuwen

    2009-01-01

    Based on the author's theory for acoustic propagation in granular media and by employing the extinction theorem, the sound speed formulae in these media were derived. The numerical computations of sound speed in 03ine sediments and air-filled sand were carried out, and the results demonstrated that under the normal atmosphere the sound speed in air- filled sand is lower than the sound speed in the air. The numerical results also indicated that the influence of scattering interaction between the grains upon the sound speed in the 03ine shallow-layer sandy sediments has to be taken into account; however, the influence of the viscous-wave interaction can be neglected. The theoretical results obtained from the rigid-granular model seem to match the measured data better than from the elastic-granular model, even the latter model fits better for the real situation, indicating further measurements are necessary in order to gain an insight into this problem thoroughly. Through an analysis of experimental data published in journals a conclusion can be drawn that the theory of granular media is suited to deal with the problems of the sound propagation in air-filled sand better than the theory of porous media.

  6. Transport of bisphenol-A in sandy aquifer sediment: Column experiment.

    Science.gov (United States)

    Zakari, Sissou; Liu, Hui; Tong, Lei; Wang, Yan; Liu, Jianfeng

    2016-02-01

    The present paper aims to study the transport behavior of bisphenol-A (BPA) in sandy aquifer so as to provide important parameters for the prediction and control of contaminant plume in aquifer. Miscible displacement experiments were conducted and the breakthrough curves (BTCs) were simulated using HYDRUS-1D software. The effects of pore-water velocity (10-52 cm h(-1)) and initial concentration (2.5-40 mg L(-1)) on the sorption were also investigated. The BTCs of BPA fit the linear first-order non-equilibrium two-site model. The parameters such as partition coefficient (K(d)), the fraction of instantaneous adsorption on "Type-1" sites (F), the first order sorption rate coefficient for the kinetic non-equilibrium (type-2) sites (α), the retardation coefficient (R), and sorption capacity (q(column)) were computed. Results showed that BPA transported 0.11-0.83 m with various pore water velocity in sandy sediment column when water flowed 1 m. The sorption of BPA was mainly caused by the instantaneous surface adsorption as F varied from 0.596 to 0.908. The transport velocity of BPA was affected by pore water velocity (v) and followed the linear equation 1/R = 0.0600 + 0.0110v (r(2) = 0.9724). The parameter K(d) were also closely related to v and followed the equation LnK(d) = 1.0023-0.0482v (r(2) = 0.9690). The sorption capacity was more related to the initial BPA concentration (C0) and followed the linear equation q(column) = 0.265 + 0.253C0 (r(2) = 0.9727). The parameter α was affected by both v and C0 whereas F was not dramatically affected by both.

  7. Impact of redox-stratification on the diversity and distribution of bacterial communities in sandy reef sediments in a microcosm

    Science.gov (United States)

    Gao, Zheng; Wang, Xin; Hannides, Angelos K.; Sansone, Francis J.; Wang, Guangyi

    2011-11-01

    Relationships between microbial communities and geochemical environments are important in marine microbial ecology and biogeochemistry. Although biogeochemical redox stratification has been well documented in marine sediments, its impact on microbial communities remains largely unknown. In this study, we applied denaturing gradient gel electrophoresis (DGGE) and clone library construction to investigate the diversity and stratification of bacterial communities in redox-stratified sandy reef sediments in a microcosm. A total of 88 Operational Taxonomic Units (OTU) were identified from 16S rRNA clone libraries constructed from sandy reef sediments in a laboratory microcosm. They were members of nine phyla and three candidate divisions, including Proteobacteria ( Alpha-, Beta-, Gamma-, Delta-, and Epsilonproteobacteria), Actinobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, Cyanobacteria, Firmicutes, Verrucomicrobia, Spirochaetes, and the candidate divisions WS3, SO31 and AO19. The vast majority of these phylotypes are related to clone sequences from other marine sediments, but OTUs of Epsilonproteobacteria and WS3 are reported for the first time from permeable marine sediments. Several other OTUs are potential new bacterial phylotypes because of their low similarity with reference sequences. Results from the 16S rRNA, gene clone sequence analyses suggested that bacterial communities exhibit clear stratification across large redox gradients in these sediments, with the highest diversity found in the anoxic layer (15-25 mm) and the least diversity in the suboxic layer (3-5 mm). Analysis of the nosZ, and amoA gene libraries also indicated the stratification of denitrifiers and nitrifiers, with their highest diversity being in the anoxic and oxic sediment layers, respectively. These results indicated that redox-stratification can affect the distribution of bacterial communities in sandy reef sediments.

  8. Impact of redox-stratification on the diversity and distribution of bacterial communities in sandy reef sediments in a microcosm

    Institute of Scientific and Technical Information of China (English)

    GAO Zheng; WANG Xin; Angelos K. HANNIDES; Francis J. SANSONE; WANG Guangyi

    2011-01-01

    Relationships between microbial communities and geochemical environments are important in marine microbial ecology and biogeochemistry.Although biogeochemical redox stratification has been well documented in marine sediments,its impact on microbial communities remains largely unknown.In this study,we applied denaturing gradient gel electrophoresis (DGGE) and clone library construction to investigate the diversity and stratification of bacterial communities in redox-stratified sandy reef sediments in a microcosm.A total of 88 Operational Taxonomic Units (OTU) were identified from 16S rRNA clone libraries constructed from sandy reef sediments in a laboratory microcosm.They were members of nine phyla and three candidate divisions,including Proteobacteria (Alpha-,Beta-,Gamma-,Delta-,and Epsilonproteobacteria),Actinobacteria,Acidobacteria,Bacteroidetes,Chloroflexi,Cyanobacteria,Firmicutes,Verrucomicrobia,Spirochaetes,and the candidate divisions WS3,SO31 and AO19.The vast majority of these phylotypes are related to clone sequences from other marine sediments,but OTUs of Epsilonproteobacteria and WS3 are reported for the first time from permeable marine sediments.Several other OTUs are potential new bacterial phylotypes because of their low similarity with reference sequences.Results from the 16S rRNA,gene clone sequence analyses suggested that bacterial communities exhibit clear stratification across large redox gradients in these sediments,with the highest diversity found in the anoxic layer (15-25 mm) and the least diversity in the suboxic layer (3-5 mm).Analysis of the nosZ,and amoA gene libraries also indicated the stratification of denitrifiers and nitrifiers,with their highest diversity being in the anoxic and oxic sediment layers,respectively.These results indicated that redox-stratification can affect the distribution of bacterial communities in sandy reef sediments.

  9. Total Sediment Thickness of the World's Oceans & Marginal Seas

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A digital total-sediment-thickness database for the world's oceans and marginal seas has been compiled by the NOAA National Geophysical Data Center (NGDC). The data...

  10. Effect of advective pore water flow on degradation of organic matter in permeable sandy sediment : - A study of fresh- and brackish water

    OpenAIRE

    2005-01-01

    The carbon metabolism in costal sediments is of major importance for the global carbon cycle. Costal sediments are also subjected to physical forcing generating water fluxes above and through the sediments, but how the physical affect the carbon metabolism is currently poorly known. In this study, the effect of advective pore water flow on degradation of organic matter in permeable sandy sediment was investigated in a laboratory study during wintertime. Sediments were collected from both brac...

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

    DEFF Research Database (Denmark)

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

    2000-01-01

    belonging to Platyhelminthes, Rotifera, Gastrotricha, and Protodriloidae (Polychaeta) occurred only at the sandy locality, whereas Kinorhyncha, Foraminifera, and Cumacea (Crustacea) occurred only at the muddy stations. The larger number of meiofauna individuals at the sandy locality may in part be explained...

  12. Time-lapse imagery of the breaching of Marmot Dam, Oregon, and subsequent erosion of sediment by the Sandy River, October 2007 to May 2008

    Science.gov (United States)

    Major, Jon J.; Spicer, Kurt R.; Collins, Rebecca A.

    2010-01-01

    In 2007, Marmot Dam on the Sandy River, Oregon, was removed and a temporary cofferdam standing in its place was breached, allowing the river to flow freely along its entire length. Time-lapse imagery obtained from a network of digital single-lens reflex cameras placed around the lower reach of the sediment-filled reservoir behind the dam details rapid erosion of sediment by the Sandy River after breaching of the cofferdam. Within hours of the breaching, the Sandy River eroded much of the nearly 15-m-thick frontal part of the sediment wedge impounded behind the former concrete dam; within 24-60 hours it eroded approximately 125,000 m3 of sediment impounded in the lower 300-meter-reach of the reservoir. The imagery shows that the sediment eroded initially through vertical incision, but that lateral erosion rapidly became an important process.

  13. 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; Fisher, Irene

    2016-01-01

    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).

  14. 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).

  15. Benthic solute exchange and carbon mineralization in two shallow subtidal sandy sediments: Effect of advective pore-water exchange

    DEFF Research Database (Denmark)

    Cook, Perran L. M.; Wenzhofer, Frank; Glud, Ronnie N.;

    2007-01-01

    of O-2 distribution across ripples, and also deep subsurface O-2 pools, being observed. Mineralization pathways were predominantly aerobic when benthic mineralization rates were low and advective pore-water flow high as a result of well-developed sediment topography. By contrast, mineralization...... proceeded predominantly through sulfate reduction when benthic mineralization rates were high and advective pore-water flow low as a result of poorly developed topography. Previous studies of benthic mineralization in shallow sandy sediments have generally ignored these dynamics and, hence, have overlooked......We conducted four field campaigns to evaluate benthic O-2 consumption and the effect of advective pore-water flow in nearshore permeable sediments in the North Sea and Baltic Sea. Advective pore-water transport had a marked effect on the benthic exchange of O-2 and TCO2 in benthic chamber...

  16. Temporal dynamics of gastropod fauna on subtidal sandy sediments of the Ensenada de Baiona (NW Iberian Peninsula)

    Science.gov (United States)

    Moreira, J.; Aldea, C.; Troncoso, J. S.

    2010-12-01

    The temporal variation of the gastropod fauna inhabiting sandy sediments of the Ensenada de Baiona (Galicia, Spain) was studied at three subtidal sites from February 1996 to February 1997 by means of quantitative sampling. A total of 5,463 individuals representing 51 gastropod species and 22 families were found. The family Pyramidellidae was the most diverse in number of species (11 species), followed by Rissoidae and Trochidae (4 species each). The dogwhelk, Nassarius reticulatus, and the rissoid snail, Rissoa parva, were the numerically dominant species at the three studied sites; those and other abundant species showed their greatest densities by the end of summer and the beginning of autumn. In general, univariate measures of the assemblage (number of species, abundance, diversity and evenness) showed variations through time; greater values were recorded between summer and autumn depending on the site. Multivariate analyses done on abundance data showed certain seasonality in the evolution of the assemblage as expected for shallow subtidal sandy sediments at temperate latitudes; those seasonal changes were mostly related to variations in abundance of numerically dominant species. Although the measured sedimentary variables did not show significant correlations with faunal univariate parameters, sediment heterogeneity due to the presence of mats of Zostera marina L. and shells of dead bivalves might explain the differences in composition of the gastropod assemblage among sampling sites.

  17. Spatial and temporal changes in interstitial meiofauna on a sandy ocean beach of South America

    Directory of Open Access Journals (Sweden)

    Elaine F. Albuquerque

    2007-06-01

    Full Text Available Spatial and temporal patterns of meiofauna community from a Brazilian sandy beach were investigated. The objective of this work was to analyze the meiofauna distribution using a statistical model that considers the biological data as variables, and granulometric characteristics, organic matter, and temperature as covariables.Four zones were sampled throughout one year in a Brazilian sandy beach and three sediment cores were taken monthly from each zone. The meiofauna was composed by 12 taxa, with tardigrades and nematodes comprising 92% of the total fauna. The meiofauna mean density varied from 1556.25 to 13125.25 ind.10 cm-2, with the highest densities in December. The results of multiple regression showed that the mean effects of zones, vertical layers, and months on the organisms were significantly correlated with the principal taxa of meiofauna. The retention zone and the 0-10 cm layer presented the highest densities. The temporal distribution showed different patterns and some taxa were more abundant in the dry season, and others in the rainy season. Sedimentological variables had strong and significant effects on the meiofauna taxa. According to the results, physical variables at the retention zone create optimal living conditions for the meiobentos, making this zone an area that favors the basic and applied ecological studies.Os padrões de distribuição espacial e temporal da meiofauna em uma praia arenosa do Brasil foram analisados usando um modelo estatístico que considerou os dados biológicos como variáveis e as características granulométricas, % de matéria orgânica, temperatura como covariáveis. Quatro zonas litorais foram amostradas durante o período de um ano e três cores de sedimento foram coletados em cada zona. A meiofauna foi composta de 12 taxa principais e os Tardigrada e Nematoda representaram 92% da fauna total. A densidade média da meiofauna variou de 1.556,25 a 13.125,25 ind.10cm-2, com as mais altas

  18. 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.

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

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  20. Estuarine bed-sediment-quality data collected in New Jersey and New York after Hurricane Sandy, 2013

    Science.gov (United States)

    Fischer, Jeffrey M.; Phillips, Patrick J.; Reilly, Timothy J.; Focazio, Michael J.; Loftin, Keith A.; Benzel, William M.; Jones, Daniel K.; Smalling, Kelly L.; Fisher, Shawn C.; Fisher, Irene J.; Iwanowicz, Luke R.; Romanok, Kristin M.; Jenkins, Darkus E.; Bowers, Luke; Boehlke, Adam; Foreman, William T.; Deetz, Anna C.; Carper, Lisa G.; Imbrigiotta, Thomas E.; Birdwell, Justin E.

    2015-01-01

    This report describes a reconnaissance study of estuarine bed-sediment quality conducted June–October 2013 in New Jersey and New York after Hurricane Sandy in October 2012 to assess the extent of contamination and the potential long-term human and ecological impacts of the storm. The study, funded through the Disaster Relief Appropriations Act of 2013 (PL 113-2), was conducted by the U.S. Geological Survey in cooperation with the U.S. Environmental Protection Agency and the National Oceanographic and Atmospheric Administration. In addition to presenting the bed-sediment-quality data, the report describes the study design, documents the methods of sample collection and analysis, and discusses the steps taken to assure the quality of the data.

  1. Eddy correlation measurements of oxygen uptake in deep ocean sediments

    DEFF Research Database (Denmark)

    Berg, P.; Glud, Ronnie Nøhr; Hume, A.

    2010-01-01

    Abstract: We present and compare small sediment-water fluxes of O-2 determined with the eddy correlation technique, with in situ chambers, and from vertical sediment microprofiles at a 1450 m deep-ocean site in Sagami Bay, Japan. The average O-2 uptake for the three approaches, respectively, was ...

  2. Regional variability in bed-sediment concentrations of wastewater compounds, hormones and PAHs for portions of coastal New York and New Jersey impacted by hurricane Sandy

    Science.gov (United States)

    Phillips, Patrick; Gibson, Cathy A; Fisher, Shawn C.; Fisher, Irene; Reilly, Timothy J.; Smalling, Kelly L.; Romanok, Kristin M.; Foreman, William T.; ReVello, Rhiannon C.; Focazio, Michael J.; Jones, Daniel K.

    2016-01-01

    Bed sediment samples from 79 coastal New York and New Jersey, USA sites were analyzed for 75 compounds including wastewater associated contaminants, PAHs, and other organic compounds to assess the post-Hurricane Sandy distribution of organic contaminants among six regions. These results provide the first assessment of wastewater compounds, hormones, and PAHs in bed sediment for this region. Concentrations of most wastewater contaminants and PAHs were highest in the most developed region (Upper Harbor/Newark Bay, UHNB) and reflected the wastewater inputs to this area. Although the lack of pre-Hurricane Sandy data for most of these compounds make it impossible to assess the effect of the storm on wastewater contaminant concentrations, PAH concentrations in the UHNB region reflect pre-Hurricane Sandy conditions in this region. Lower hormone concentrations than predicted by the total organic carbon relation occurred in UHNB samples, suggesting that hormones are being degraded in the UHNB region.

  3. Hurricane Sandy's Impact on Coastal Sedimentation on Long Island's South Shore: Results from a 2013 Rapid Response Study

    Science.gov (United States)

    Christensen, B. A.; Goff, J. A.; Flood, R. D.; Austin, J. A., Jr.; Browne, C. M.; Saustrup, S.

    2014-12-01

    To understand the impact of Hurricane Sandy on the NY coast, we conducted subsurface and multi-beam analyses, ground-truthed by grab samples, in 3 areas: the western end of Fire Island (FIW), eastern Fire Island (FIE) where a new inlet formed during the storm, and Long Beach (LB). Grab samples yielded sands and muds, a surprise given the shallow (10-25m) water depths. Muds rested on top of sands and were removed for additional analyses. Since percent mud could not be determined absolutely, sediments were washed through a 63 mm sieve, RoTapped for 10 minutes at ¼ Φ, and weight percent calculated for the coarse fraction. At FIW and FIE, fine sands dominate the shallowest depths studied, consistent with previous studies. At FIE, the sedimentary wedge extends to ~15m, with finest sands (peak 3-3.5 Φ) in shallowest waters surveyed (~10m). Slightly coarser (2.5Φ) sediments plus relict gravels are present in swales where the wedge shoals. This supports mapping results indicating sand ridges migrated to the SW. Medium to fine sand is present at the deepest extent of the wedge; the grain size distribution matches a sample taken in the swash zone on the eastern flank of the new breach. Sediments may have been transported shoreward and then reworked post-Sandy. Samples seaward of the new breach were capped by a mud layer, which in turn had a layer of fine sand resting on it, evidence of a nascent ebb tidal deposit. At FIW, sediments in the shallow NE swale are finer (3.5Φ) and better sorted. As the region is underlain by relict sediments, these fine sands may be relicts exposed by storm-driven bedform migration. Deeper water (~22m w.d.) samples at FIW are coarser and contain shell hash. Sand on the lee side of the sand ridge, which CHIRP profiles show did not migrate significantly and accumulated sands, are medium (1.5 Φ), and match the grain sizes found on Fire Island beach. Muds contain heavy metals in concentrations consistent with transport from adjacent estuaries.

  4. Effect of nutrient availability on carbon and nitrogen incorporation and flows through benthic algae and bacteria in near-shore sandy sediment

    NARCIS (Netherlands)

    Cook, P.; Veuger, B.; Böer, S.; Middelburg, J.J.

    2007-01-01

    Carbon and nitrogen uptake in a microbial community comprising bacteria and microalgae in a sandy marine sediment under nutrient-limited and -replete conditions was studied using a mesocosm approach. After 2 wk of incubation, a pulse of H13CO3– and 15NH4+ was added to the mesocosms, and subsequent

  5. Species-specific effect of macrobenthic assemblages on meiobenthos and nematode community structure in shallow sandy sediments.

    Science.gov (United States)

    Urban-Malinga, Barbara; Drgas, Aleksander; Gromisz, Sławomira; Barnes, Natalie

    2014-01-01

    Three functionally different macrofaunal species (the filter- and/or surface deposit-feeding polychaete Hediste diversicolor, and the suspension-feeding bivalves Mya arenaria and Cerastoderma glaucum) were introduced as single- and two-species treatments into microcosms containing sandy sediment with a natural meiofaunal community. H. diversicolor is a burrowing species building a system of galleries, C. glaucum lives actively near the sediment surface acting as a biodiffuser and M. arenaria buries deeply and leads a sessile lifestyle. It is shown that H. diversicolor extended the vertical distribution of meiofauna into deeper sediment layers compared to the control and non-Hediste treatments. The response of the nematode community varied significantly among treatments and was dependant on the macrobenthic species composition but not on the species number. Nematode assemblages in all treatments with the polychaete, both in monoculture and with either bivalve, differed significantly from those recorded in other treatments and were more similar than replicates within any other single treatment. H. diversicolor also appeared to have stimulated nematode species diversity. The present study demonstrated that the impact of macrobenthic assemblages on meiofauna is not a simple summation of individual species effects but is species specific.

  6. Meiofauna in sandy back-reef platforms differently exposed to the monsoons in the Maldives (Indian Ocean)

    Science.gov (United States)

    Semprucci, F.; Colantoni, P.; Sbrocca, C.; Baldelli, G.; Rocchi, M.; Balsamo, M.

    2011-09-01

    Maldives comprise some of the most characteristic and significant atoll systems, but the meiobenthic assemblages of these islands are still largely unknown. A study on meiofauna was conducted on three Maldivian sandy back-reef platforms differently exposed to stronger westerly monsoons. Clear high energy effects of the waves causing currents and erosions were observed at the completely exposed and isolated offshore reef of Thoddoo Island. Wave energy of medium intensity was confirmed at Rasdhoo by depositional structures ( finolhu), while a medium to low energy level was recorded at Gulhi on the basis of the presence of a low sandy bar. The meiofaunal assemblage counted 17 major taxa. Copepods and nematodes were dominant, followed by platyhelminthes and polychaetes. The nematode assemblage was rather rich and composed of 28 families and 84 genera. Desmodoridae were the most abundant family, followed by Draconematidae, Xyalidae, Epsilonematidae and Chromadoridae. The meiofauna resulted strongly affected by erosion effects, both in terms of abundance and richness, but we were not able to distinguish the two different sedimentation rates. Instead, the structure of the nematode community seemed to be more sensitive in distinguishing each type of hydrodynamic condition and energy level.

  7. SANDY: A Matlab tool to estimate the sediment size distribution from a sieve analysis

    Science.gov (United States)

    Ruiz-Martínez, Gabriel; Rivillas-Ospina, Germán Daniel; Mariño-Tapia, Ismael; Posada-Vanegas, Gregorio

    2016-07-01

    This paper presents a new computational tool called SANDY© which calculates the sediment size distribution and its textural parameters from a sieved sediment sample using Matlab®. The tool has been developed for professionals involved in the study of sediment transport along coastal margins, estuaries, rivers and desert dunes. The algorithm uses several types of statistical analyses to obtain the main textural characteristics of the sediment sample (D50, mean, sorting, skewness and kurtosis). SANDY© includes the method of moments (geometric, arithmetic and logarithmic approaches) and graphical methods (geometric, arithmetic and mixed approaches). In addition, it provides graphs of the sediment size distribution and its classification. The computational tool automatically exports all the graphs as enhanced metafile images and the final report is also exported as a plain text file. Parameters related to bed roughness such as Nikuradse and roughness length are also computed. Theoretical depositional environments are established by a discriminant function analysis. Using the uniformity coefficient the hydraulic conductivity of the sand as well as the porosity and void ratio of the sediment sample are obtained. The maximum relative density related to sand compaction is also computed. The Matlab® routine can compute one or several samples. SANDY© is a useful tool for estimating the sediment textural parameters which are the basis for studies of sediment transport.

  8. Production of fluorescent dissolved organic matter in Arctic Ocean sediments

    Science.gov (United States)

    Chen, Meilian; Kim, Ji-Hoon; Nam, Seung-Il; Niessen, Frank; Hong, Wei-Li; Kang, Moo-Hee; Hur, Jin

    2016-12-01

    Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the sulfate-methane-transition-zone (SMTZ). The presence of FDOM was concurrent with sulfate reduction and increased alkalinity (R2 > 0.96, p  0.95, p oceans.

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

    DEFF Research Database (Denmark)

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

    2000-01-01

    layers of the sediment. Algal photosynthetic activity and nitrogen uptake reduced nitrogen effluxes and denitrification rates. Sulfate reduction was the most important pathway for carbon mineralization in the sediments of the shallow-water station. In contrast, high bottom-water NO3- concentrations...... and a relatively deep O-2 penetration into the sediment at the deep-water stations ensured high denitrification activity, particularly as a result of an efficient coupling between nitrification and denitrification. Denitrification accounted for up to 33 % of total carbon mineralization in the deep-water sediment......, corresponding to the 3 times higher number of meiofauna found in the upper 2 cm of this sediment. Thus, meiofauna increased the transport of solutes as compared to molecular diffusion by a factor of 1.5 to 3.1, thereby stimulating microbial mineralization...

  10. Study on sound-speed dispersion in a sandy sediment at frequency ranges of 0.5-3 kHz and 90-170 kHz

    Science.gov (United States)

    Yu, Sheng-qi; Liu, Bao-hua; Yu, Kai-ben; Kan, Guang-ming; Yang, Zhi-guo

    2017-03-01

    In order to study the properties of sound-speed dispersion in a sandy sediment, the sound speed was measured both at high frequency (90-170 kHz) and low frequency (0.5-3 kHz) in laboratory environments. At high frequency, a sampling measurement was conducted with boiled and uncooked sand samples collected from the bottom of a large water tank. The sound speed was directly obtained through transmission measurement using single source and single hydrophone. At low frequency, an in situ measurement was conducted in the water tank, where the sandy sediment had been homogeneously paved at the bottom for a long time. The sound speed was indirectly inverted according to the traveling time of signals received by three buried hydrophones in the sandy sediment and the geometry in experiment. The results show that the mean sound speed is approximate 1710-1713 m/s with a weak positive gradient in the sand sample after being boiled (as a method to eliminate bubbles as much as possible) at high frequency, which agrees well with the predictions of Biot theory, the effective density fluid model (EDFM) and Buckingham's theory. However, the sound speed in the uncooked sandy sediment obviously decreases (about 80%) both at high frequency and low frequency due to plenty of bubbles in existence. And the sound-speed dispersion performs a weak negative gradient at high frequency. Finally, a water-unsaturated Biot model is presented for trying to explain the decrease of sound speed in the sandy sediment with plenty of bubbles.

  11. Linking Arenicola marina irrigation behavior to oxygen transport and dynamics in sandy sediments

    DEFF Research Database (Denmark)

    Timmermann, Karen; Banta, Gary T.; Glud, Ronnie Nøhr

    2007-01-01

    In this study we examine how the irrigation behavior of the common lugworm Arenicola marina affects the distribution, transport and dynamics of oxygen in sediments using microelectrodes, planar optodes and diagenetic modeling. The irrigation pattern was characterized by a regular recurring periods...... mediated oxygen uptake of the burrow wall. Approximately 28% of the oxygen was consumed by the feeding pocket/funnel characterized by advective porewater transport. Model simulations indicated that oxygen injected into the sediment was usually consumed in a very narrow zone around the feeding pocket...... concentration in the burrow was high (80% air saturation) and oxygen was detected at distances up to 0.7 mm from the burrow wall. Volume specific oxygen consumption rates calculated from measured oxygen profiles were up to 4 times higher for sediments surrounding worm burrows as compared to surface sediments...

  12. Ocean currents shape the microbiome of Arctic marine sediments.

    Science.gov (United States)

    Hamdan, Leila J; Coffin, Richard B; Sikaroodi, Masoumeh; Greinert, Jens; Treude, Tina; Gillevet, Patrick M

    2013-04-01

    Prokaryote communities were investigated on the seasonally stratified Alaska Beaufort Shelf (ABS). Water and sediment directly underlying water with origin in the Arctic, Pacific or Atlantic oceans were analyzed by pyrosequencing and length heterogeneity-PCR in conjunction with physicochemical and geographic distance data to determine what features structure ABS microbiomes. Distinct bacterial communities were evident in all water masses. Alphaproteobacteria explained similarity in Arctic surface water and Pacific derived water. Deltaproteobacteria were abundant in Atlantic origin water and drove similarity among samples. Most archaeal sequences in water were related to unclassified marine Euryarchaeota. Sediment communities influenced by Pacific and Atlantic water were distinct from each other and pelagic communities. Firmicutes and Chloroflexi were abundant in sediment, although their distribution varied in Atlantic and Pacific influenced sites. Thermoprotei dominated archaea in Pacific influenced sediments and Methanomicrobia dominated in methane-containing Atlantic influenced sediments. Length heterogeneity-PCR data from this study were analyzed with data from methane-containing sediments in other regions. Pacific influenced ABS sediments clustered with Pacific sites from New Zealand and Chilean coastal margins. Atlantic influenced ABS sediments formed another distinct cluster. Density and salinity were significant structuring features on pelagic communities. Porosity co-varied with benthic community structure across sites and methane did not. This study indicates that the origin of water overlying sediments shapes benthic communities locally and globally and that hydrography exerts greater influence on microbial community structure than the availability of methane.

  13. Airflow and sediment movement within an inland blowout in Hulun Buir sandy grassland, Inner Mongolia, China

    Science.gov (United States)

    Sun, Yu; Hasi, Eerdun; Liu, Meiping; Du, Huishi; Guan, Chao; Tao, Binbin

    2016-09-01

    We measured wind flows and sediment transport rates through a blowout in Hulun Buir grassland, Inner Mongolia. Topography and the angle of incidence between the approaching wind and the blowout long-axis significantly affected the air flow. Flow separated and decelerated at the western wall and accelerated towards the east, until maximum wind speed occurred at the top of the depositional lobe, and then decelerated on the lee side. When airflow emerged on the eastern wall, resultant directions were always NW. When winds approached from directions within 17.5° of the blowout axis, both the northwestern and southwestern walls developed turbulent flow, and significant topographic steering occurred. The deceleration zone expanded eastwards from 10.3 to 12.8 m from the western rim. When the wind direction was more oblique than 17.5°, turbulent flow at the southwestern wall disappeared. 'S-shaped' flow intensified, causing more pronounced steering at the bottom, but topographic steering elsewhere was reduced, and the boundary of the deceleration moved to 10 m from the western rim. Minor sediment deposition occurred on the western wall, while other parts were eroded; maximum sediment transport occurred at the top of the depositional lobe. The approaching wind speed affected the sediment transport rate more than the direction; and spatial variability in sediment transport reflected differences in compaction, vegetation coverage, slope, aspect, and upwind sediment availability, resulting in asymmetrical development. Overall, flow-form interactions governed the flow structures and controlled the evolution of the blowout via sediment transport.

  14. Effects of bioturbation on the fate of oil in coastal sandy sediments - An in situ experiment

    DEFF Research Database (Denmark)

    Timmermann, Karen; Banta, Gary T.; Klinge, Lars

    2011-01-01

    –MS and bioturbation activity (feces production and irrigation) was measured regularly during the experiment and used as input parameters in a mechanistic model describing the effects of A. marina on the transport and degradation of oil compounds in the sediment. The chemical analytical data and model results......Effects of bioturbation by the common lugworm Arenicola marina on the fate of oil hydrocarbons (alkanes and PAHs) were studied in situ during a simulated oil spill in a shallow coastal area of Roskilde fjord, Denmark. The fate of selected oil compounds was monitored during 120 d using GC...... indicated that A. marina had profound and predictable effects on the distribution, degradation and preservation of oil and that the net effect depended on the initial distribution of oil. In sediment with an oil contaminated subsurface-layer A. marina buried the layer deeper in the sediment which clearly...

  15. Eruption-related lahars and sedimentation response downstream of Mount Hood: Field guide to volcaniclastic deposits along the Sandy River, Oregon

    Science.gov (United States)

    Pierson, Tom C.; Scott, William E.; Vallance, James W.; Pringle, Patrick T.; O'Connor, Jim; Dorsey, Rebecca; Madin, Ian

    2009-01-01

    Late Holocene dome-building eruptions at Mount Hood during the Timberline and Old Maid eruptive periods resulted in numerous dome-collapse pyroclastic flows and lahars that moved large volumes of volcaniclastic sediment into temporary storage in headwater canyons of the Sandy River. During each eruptive period, accelerated sediment loading to the river through erosion and remobilization of volcanic fragmental debris resulted in very high sediment-transport rates in the Sandy River during rain- and snowmelt-induced floods. Large sediment loads in excess of the river's transport capacity led to channel aggradation, channel widening, and change to a braided channel form in the lowermost reach of the river, between 61 and 87 km downstream from the volcano. The post-eruption sediment load moved as a broad bed-material wave, which in the case of the Old Maid eruption took ~2 decades to crest 83 km downstream. Maximum post-eruption aggradation levels of at least 28 and 23 m were achieved in response to Timberline and Old Maid eruptions. In each case, downstream aggradation cycles were initiated by lahars, but the bulk of the aggradation was achieved by fluvial sediment transport and deposition. When the high rates of sediment supply began to diminish, the river degraded, incising the channel fills and forming progressively lower sets of degradational terraces. A variety of debris-flow, hyperconcentrated-flow, and fluvial (upper and lower flow regime) deposits record the downstream passage of the sediment waves that were initiated by these eruptions. The deposits also presage a hazard that may be faced by communities along the Sandy River when volcanic activity at Mount Hood resumes.

  16. Impacts of ocean acidification on sediment processes in shallow waters of the Arctic Ocean.

    Science.gov (United States)

    Gazeau, Frédéric; van Rijswijk, Pieter; Pozzato, Lara; Middelburg, Jack J

    2014-01-01

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer waters, acidification rates in these areas are faster than those in sub-tropical regions. The present study investigates the effects of ocean acidification on sediment composition, processes and sediment-water fluxes in an Arctic coastal system. Undisturbed sediment cores, exempt of large dwelling organisms, were collected, incubated for a period of 14 days, and subject to a gradient of pCO2 covering the range of values projected for the end of the century. On five occasions during the experimental period, the sediment cores were isolated for flux measurements (oxygen, alkalinity, dissolved inorganic carbon, ammonium, nitrate, nitrite, phosphate and silicate). At the end of the experimental period, denitrification rates were measured and sediment samples were taken at several depth intervals for solid-phase analyses. Most of the parameters and processes (i.e. mineralization, denitrification) investigated showed no relationship with the overlying seawater pH, suggesting that ocean acidification will have limited impacts on the microbial activity and associated sediment-water fluxes on Arctic shelves, in the absence of active bio-irrigating organisms. Only following a pH decrease of 1 pH unit, not foreseen in the coming 300 years, significant enhancements of calcium carbonate dissolution and anammox rates were observed. Longer-term experiments on different sediment types are still required to confirm the limited impact of ocean acidification on shallow Arctic sediment processes as observed in this study.

  17. Wave and sediment dynamics along a shallow subtidal sandy beach inhabited by modern stromatolites.

    Science.gov (United States)

    Eckman, J E; Andres, M S; Marinelli, R L; Bowlin, E; Reid, R P; Aspden, R J; Paterson, D M

    2008-01-01

    To help define the habitat of modern marine stromatolites, wave-dominated flow and sediment transport were studied in the shallow subtidal region (1-2 m depth) along the slightly concave, windward face of Highborne Cay, Exuma, Bahamas - the only face of the cay that includes a population of stromatolites concentrated near the region of highest curvature of the beach. Wave energy impacting this island's most exposed beach was driven by local wind forcing which increases largely in response to the passage of atmospheric disturbances that typically affect the region for periods of a few days. Although some wave energy is almost always noted (maximum horizontal orbital speeds at the bottom are rarely <10 cm s(-1)), wave conditions remain comparatively calm until local winds increase above speeds of approximately 3-4 m s(-1) at which point maximum wave speeds rapidly increase to 50-80 cm s(-1). Stromatolites, which are largely restricted to the shoreward side of a shallow platform reef, are sheltered by the reef beyond which wave speeds are one to four times higher (depending on tidal stage). Moreover, stromatolite populations are predominantly found along a region of this wave-exposed beach that experiences comparatively reduced wave energy because of the curved morphology of the island's face. Maximum wave speeds are 1.4 to 2 times higher along more northern sections of the beach just beyond the locus of stromatolite populations. A quantitative model of sediment transport was developed that accurately predicted accumulation of suspended sediment in sediment traps deployed in the shallow subtidal zone along this beach. This model, coupled with in situ wave records, indicates that gross rates of suspended sediment deposition should be two to three times higher northward of the main stromatolite populations. Regions of the beach containing stromatolites nevertheless should experience significant rates of gross suspended sediment deposition averaging 7-10 g cm(-2) day(-1

  18. Exploring Microbial Life in Oxic Sediments Underlying Oligotrophic Ocean Gyres

    Science.gov (United States)

    Ziebis, W.; Orcutt, B.; Wankel, S. D.; D'Hondt, S.; Szubin, R.; Kim, J. N.; Zengler, K.

    2015-12-01

    Oxygen, carbon and nutrient availability are defining parameters for microbial life. In contrast to organic-rich sediments of the continental margins, where high respiration rates lead to a depletion of O2 within a thin layer at the sediment surface, it was discovered that O2 penetrates several tens of meters into organic-poor sediments underlying oligotrophic ocean gyres. In addition, nitrate, another important oxidant, which usually disappears rapidly with depth in anoxic sediments, tends to accumulate above seawater concentrations in the oxic subsurface, reflecting the importance of nitrogen cycling processes, including both nitrification and denitrification. Two IODP drilling expeditions were vital for exploring the nature of the deep subsurface beneath oligotrophic ocean gyres, expedition 329 to the South Pacific Gyre (SPG) and expedition 336 to North Pond, located on the western flank of the Mid-Atlantic ridge beneath the North Atlantic Gyre. Within the ultra-oligotrophic SPG O2 penetrates the entire sediment column from the sediment-water interface to the underlying basement to depths of > 75 m. At North Pond, a topographic depression filled with sediment and surrounded by steep basaltic outcrops, O2 penetrates deeply into the sediment (~ 30 m) until it eventually becomes depleted. O2 also diffuses upward into the sediment from seawater circulating within the young crust underlying the sediment, resulting in a deep oxic layer several meters above the basalt. Despite low organic carbon contents microbial cells persist throughout the entire sediment column within the SPG (> 75 m) and at North Pond, albeit at low abundances. We explored the nature of the subsurface microbial communities by extracting intact cells from large volumes of sediment obtained from drill cores of the two expeditions. By using CARD-FiSH, amplicon (16s rRNA) and metagenome sequencing we shed light on the phylogenetic and functional diversity of the elusive communities residing in the

  19. Photosynthesis as a Possible Source of Gas Bubbles in Shallow Sandy Coastal Sediments

    Science.gov (United States)

    2012-09-30

    clearly demonstrates that gas bubbles can be formed when photosynthesis by benthic microalgae causes pore water to become supersaturated with oxygen...We also collected sediment samples from the upper few mm of sand to identify the dominant taxa of benthic microalgae present. Although benthic...Jan Rines (Graduate School of Oceanography / University of Rhode Island = GSO/URI) to identify the benthic microalgae in the samples. Following the

  20. Assessment of spatial flow patterns in unsaturated sandy alluvial sediments using high- resolution GPR.

    Science.gov (United States)

    Haarder, E. B.; Looms, M. C.; Nielsen, L.; Jensen, K. H.

    2008-12-01

    Traditional sampling and monitoring techniques have inherent limitations in capturing the detailed spatial patterns of water flow in the unsaturated zone particularly for complex flow conditions such as unstable wetting fronts or preferential flow. Dye tracer experiments can help visualise the dynamics of water flow but they are highly destructive as well. High-resolution Ground Penetrating Radar (GPR) is an attractive technique for non-destructive mapping of soil moisture changes and thus flow patterns in the shallow subsurface. In this study we test the method at a field site in western Denmark developed on a sandy alluvial outwash plane. We compare high-resolution reflection GPR data with visual observations from a dye tracer experiment using Brilliant Blue (BB). 100 mm of BB-stained water was infiltrated over a 5x5 m area and 3D reflection GPR data sets using high-frequency antennae were collected before and after infiltration. Subsequently a 2 m deep trench was excavated for visual observations of the flow patterns in a cross-section as evidenced by the dye staining patterns. The dye infiltration experiment had an overall attenuating effect on the GPR signal, and reflections were delayed significantly because of the increase in soil moisture. In the excavated cross-section we found a reasonable agreement between the areas subject to attenuation of the GPR signal and the areas affected by dye. Also, we found that displacement flow was responsible for a delay of deeper reflections below the extend of the dye staining. An amplitude analysis performed for a shallow 1.3 m thick section shows a general decrease in electromagnetic wave amplitude within the region bounded by the area exposed to infiltration, but also suggests that lateral flow along sedimentary boundaries occurs. The results suggest that high-resolution GPR provides important insight into the spatial patterns of unsaturated flow and highlight the applicability of this method as a non-destructive means

  1. Ground motions on rocky, cliffed, and sandy shorelines generated by ocean waves

    Science.gov (United States)

    Young, Adam P.; Guza, Robert T.; Dickson, Mark E.; O'Reilly, William C.; Flick, Reinhard E.

    2013-12-01

    We compare ground motions observed within about 100 m of the waterline on eight sites located on shorelines with different morphologies (rock slope, cliff, and sand beaches). At all sites, local ocean waves generated ground motions in the frequency band 0.01-40 Hz. Between about 0.01 and 0.1 Hz, foreshore loading and gravitational attraction from ocean swell and infragravity waves drive coherent, in-phase ground flexing motions mostly oriented cross-shore that decay inland. At higher frequencies between 0.5 and 40 Hz, breaking ocean waves and wave-rock impacts cause ground shaking. Overall, seismic spectral shapes were generally consistent across shoreline sites and usually within a few orders of magnitude despite the diverse range of settings. However, specific site response varied and was influenced by a combination of tide level, incident wave energy, site morphology, ground composition, and signal decay. Flexing and shaking increased with incident wave energy and was often tidally modulated, consistent with a local generation source. Flexing magnitudes were usually larger than shaking, and flexing displacements of several mm were observed during relatively large incident wave conditions (Hs 4-5 m). Comparison with traffic noise and earthquakes illustrate the relative significance of local ocean-generated signals in coastal seismic data. Seismic observations are not a simple proxy for wave-cliff interaction.

  2. Balance Between Autotrophic and Heterotrophic Components and Processes in Microbenthic Communities of Sandy Sediments: A Field Study

    Science.gov (United States)

    Sundbäck, Kristina; Nilsson, Per; Nilsson, Claes; Jönsson, Benno

    1996-12-01

    The microscopic community of a microtidal sandy sediment on the Swedish west coast was studied in situat two depths (0·5 and 4 m) on four occasions (January, April, August and October). Biomass of microalgae, bacteria, ciliates and meiofauna, as well as primary and bacterial productivity, were quantified. Meiofaunal grazing on algae and bacteria was measured simultaneously by radiolabelling intact sediment cores. Autotrophic biomass dominated the microbial community at both depths and on all sampling occasions, accounting for 47-87% of the microbial biomass. Meiofauna contributed 10-47%, while bacteria and ciliates together made up less than 6%. The microflora was dominated by attached (epipsammic) diatoms, but occasional ' blooms ' of motile species occurred. Vital cells of planktonic diatoms contributed to benthic algal biomass in spring. Primary productivity exceeded bacterial productivity in April and August at both depths, while the balance was reversed in October and January. Meiofauna grazed between 2 and 12% of the algal biomass per day, and between 0·3 and 37% of the bacterial biomass. Almost an order of magnitude more algal (17-138 mg C m -2) than bacterial (0·1-33 mg C m -2) carbon was grazed daily. At the shallow site, primary productivity always exceeded grazing rates on algae, whereas at the deeper site, grazing exceeded primary productivity in October and January. Bacterial productivity exceeded grazing at both depths on all four occasions. Thus, meiofaunal grazing seasonally controlled microalgal, but not bacterial, biomass. These results suggest that, during summer, only a minor fraction (food web ' through meiofauna. During spring and autumn, however, a much larger fraction (≈30-60%) of primary production may pass through meiofauna. During winter, meiofaunal grazing is a less important link in the shallow zone, but at sublittoral depths, algal productivity may be limiting, and meiofauna depend on other food sources, such as bacteria and

  3. Impacts of ocean acidification on sediment processes in shallow waters of the Arctic Ocean

    NARCIS (Netherlands)

    Gazeau, F.; van Rijswijk, P.; Pozzato, L.; Middelburg, J.J.

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer

  4. Impacts of Ocean Acidification on Sediment Processes in Shallow Waters of the Arctic Ocean

    NARCIS (Netherlands)

    Gazeau, F.; van Rijswijk, P.; Pozzato, L.; Middelburg, J.J.

    2014-01-01

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer

  5. Impacts of ocean acidification on sediment processes in shallow waters of the Arctic Ocean

    NARCIS (Netherlands)

    Gazeau, F.; van Rijswijk, P.; Pozzato, L.; Middelburg, J.J.|info:eu-repo/dai/nl/079665373

    2014-01-01

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer wat

  6. Impacts of Ocean Acidification on Sediment Processes in Shallow Waters of the Arctic Ocean

    NARCIS (Netherlands)

    Gazeau, F.; van Rijswijk, P.; Pozzato, L.; Middelburg, J.J.

    2014-01-01

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer wat

  7. Impacts of Ocean Acidification on Sediment Processes in Shallow Waters of the Arctic Ocean

    NARCIS (Netherlands)

    Gazeau, F.; van Rijswijk, P.; Pozzato, L.; Middelburg, J.J.

    2014-01-01

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer wat

  8. Sediment and discharge yields within a minimally disturbed, headwater watershed in North Central Pennsylvania, USA, with an emphasis on Superstorm Sandy

    Science.gov (United States)

    Maloney, Kelly O.; Shull, Dustin R.

    2015-01-01

    We estimated discharge and suspended sediment (SS) yield in a minimally disturbed watershed in North Central Pennsylvania, USA, and compared a typical storm (September storm, 4.80 cm) to a large storm (Superstorm Sandy, 7.47 cm rainfall). Depending on branch, Sandy contributed 9.7–19.9 times more discharge and 11.5–37.4 times more SS than the September storm. During the September storm, the upper two branches accounted for 60.6% of discharge and 88.8% of SS at Lower Branch; during Sandy these percentages dropped to 36.1% for discharge and 30.1% for SS. The branch with close proximity roads had over two-three times per area SS yield than the branch without such roads. Hysteresis loops showed typical clockwise patterns for the September storm and more complicated patterns for Sandy, reflecting the multipeak event. Estimates of SS and hysteresis in minimally disturbed watersheds provide useful information that can be compared spatially and temporally to facilitate management.

  9. Diagenetic regimes in Arctic Ocean sediments: Implications for sediment geochemistry and core correlation

    Science.gov (United States)

    Meinhardt, A.-K.; März, C.; Schuth, S.; Lettmann, K. A.; Schnetger, B.; Wolff, J.-O.; Brumsack, H.-J.

    2016-09-01

    Dark brown sediment layers are a potential stratigraphic tool in Quaternary Arctic Ocean sediments. They are rich in Mn, Fe, and trace metals scavenged from the water column and were most likely deposited during interglacial intervals. In this study, we combine sediment and pore water data from sediment cores taken in different parts of the Arctic Ocean to investigate the influence of early diagenetic processes on sediment geochemistry. In most studied cores, Mn, Co, and Mo are released into the pore waters from Mn oxide dissolution in deeper (>1.5 m) sediment layers. The relationship between sedimentary Mn, Co, and Mo contents in excess of the lithogenic background (elementxs) shows that Coxs/Moxs values are a diagnostic tool to distinguish between layers with diagenetic metal addition from the pore waters (Coxs/Moxs 10), and unaffected layers (Coxs/Moxs from 1 to 10). Steady-state calculations based on current pore water profiles reveal that in the studied cores, the diagenetic addition of these metals from the pore water pool alone is not sufficient to produce the sedimentary metal enrichments. However, it seems evident that dissolution of Mn oxides in the Mn reduction zone can permanently alter the primary geochemical signature of the dark brown layers. Therefore, pore water data and Coxs/Moxs values should be considered before core correlation when this correlation is solely based on Mn contents and dark sediment color. In contrast to the mostly non-lithogenic origin of Mn in the dark brown layers, sedimentary Fe consists of a large lithogenic (80%) and a small non-lithogenic fraction (20%). Our pore water data show that diagenetic Fe remobilization is not currently occurring in the sediment. The dominant Fe sources are coastal erosion and river input. Budget calculations show that Fe seems to be trapped in the modern Arctic Ocean and accumulates in shelf and basin sediments. The Fe isotopic signal δ56Fe of the solid phase is positive (∼0.2-0.3‰) in

  10. Hurricane Sandy Poster (October 29, 2012)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Hurricane Sandy poster. Multi-spectral image from Suomi-NPP shows Hurricane Sandy approaching the New Jersey Coast on October 29, 2012. Poster size is approximately...

  11. Sedimentation of lithogenic particles in the deep ocean

    Science.gov (United States)

    Honjo, S.; Manganini, S.J.; Poppe, L.J.

    1982-01-01

    Investigation of lithogenic particles collected by sediment traps in open-ocean stations revealed that the sediment flux increased linearly with depth in the water column. This rate of increase decreased with distance of the station from the continent; it was largest at the Panama Basin station and almost negligible at the E. Hawaii Abyssal Plain station. At the Panama Basin station, smectite flux increased with depth. We suggest that smectite resuspended from bottom sediments of the continental slope west of the sediment-trap station is advected by easterly deep currents, and the suspended particles are then possibly entrapped by large settling particles. On the other hand, the flux of hemipelagic clay particles, kaolinite and chlorite, was nearly constant at all depths; this can be explained by incorporation of these particles in fecal pellets which then settle from the surface water. At the Demerara Abyssal Basin Station, flux of illite and chlorite particles increased with depth and the flux of smectite was constant. A sudden increase of the flux of illite and chlorite was observed near the bottom traps at the So??hm Abyssal Plain station. The flux of quartz and feldspar was 10 to 15% of the clay flux. 

  12. Characterization of shallow ocean sediments using the airborne electromagnetic method

    Science.gov (United States)

    Won, I. J.; Smits, K.

    1986-01-01

    Experimental airborne electromagnetic (AEM) survey data collected in Cape Cod Bay are used to derive continuous profiles of water depth, electrical depth, water conductivity, and bottom sediment conductivity. Through a few well-known empirical relationships, the conductivities are used, in turn, to derive density, porosity, sound speed, and acoustic reflectivity of the ocean bottom. A commercially available Dighem III AEM system was used for the survey without any significant modification. The helicopter-borne system operated at 385 and 7200 Hz; both were in a horizontal coplanar configuration. The interpreted profiles show good agreement with available ground truth data. Where no such data are available, the results appear to be very reasonable. Compared with the shipborne electrode array method, the AEM method can determine the necessary parameters at a much higher speed with a better lateral resolution over a wide range of water depths from 0 to perhaps 100 m. The bottom sediment conductivity that can be measured by the AEM method is closely related to physical properties of sediments, such as porosity, density, sound speed, and, indirectly, sediment types that might carry broad implications for various offshore activities.

  13. Marine Microbial Gene Abundance and Community Composition in Response to Ocean Acidification and Elevated Temperature in Two Contrasting Coastal Marine Sediments.

    Science.gov (United States)

    Currie, Ashleigh R; Tait, Karen; Parry, Helen; de Francisco-Mora, Beatriz; Hicks, Natalie; Osborn, A Mark; Widdicombe, Steve; Stahl, Henrik

    2017-01-01

    Marine ecosystems are exposed to a range of human-induced climate stressors, in particular changing carbonate chemistry and elevated sea surface temperatures as a consequence of climate change. More research effort is needed to reduce uncertainties about the effects of global-scale warming and acidification for benthic microbial communities, which drive sedimentary biogeochemical cycles. In this research, mesocosm experiments were set up using muddy and sandy coastal sediments to investigate the independent and interactive effects of elevated carbon dioxide concentrations (750 ppm CO2) and elevated temperature (ambient +4°C) on the abundance of taxonomic and functional microbial genes. Specific quantitative PCR primers were used to target archaeal, bacterial, and cyanobacterial/chloroplast 16S rRNA in both sediment types. Nitrogen cycling genes archaeal and bacterial ammonia monooxygenase (amoA) and bacterial nitrite reductase (nirS) were specifically targeted to identify changes in microbial gene abundance and potential impacts on nitrogen cycling. In muddy sediment, microbial gene abundance, including amoA and nirS genes, increased under elevated temperature and reduced under elevated CO2 after 28 days, accompanied by shifts in community composition. In contrast, the combined stressor treatment showed a non-additive effect with lower microbial gene abundance throughout the experiment. The response of microbial communities in the sandy sediment was less pronounced, with the most noticeable response seen in the archaeal gene abundances in response to environmental stressors over time. 16S rRNA genes (amoA and nirS) were lower in abundance in the combined stressor treatments in sandy sediments. Our results indicated that marine benthic microorganisms, especially in muddy sediments, are susceptible to changes in ocean carbonate chemistry and seawater temperature, which ultimately may have an impact upon key benthic biogeochemical cycles.

  14. Marine Microbial Gene Abundance and Community Composition in Response to Ocean Acidification and Elevated Temperature in Two Contrasting Coastal Marine Sediments

    Directory of Open Access Journals (Sweden)

    Ashleigh R. Currie

    2017-08-01

    Full Text Available Marine ecosystems are exposed to a range of human-induced climate stressors, in particular changing carbonate chemistry and elevated sea surface temperatures as a consequence of climate change. More research effort is needed to reduce uncertainties about the effects of global-scale warming and acidification for benthic microbial communities, which drive sedimentary biogeochemical cycles. In this research, mesocosm experiments were set up using muddy and sandy coastal sediments to investigate the independent and interactive effects of elevated carbon dioxide concentrations (750 ppm CO2 and elevated temperature (ambient +4°C on the abundance of taxonomic and functional microbial genes. Specific quantitative PCR primers were used to target archaeal, bacterial, and cyanobacterial/chloroplast 16S rRNA in both sediment types. Nitrogen cycling genes archaeal and bacterial ammonia monooxygenase (amoA and bacterial nitrite reductase (nirS were specifically targeted to identify changes in microbial gene abundance and potential impacts on nitrogen cycling. In muddy sediment, microbial gene abundance, including amoA and nirS genes, increased under elevated temperature and reduced under elevated CO2 after 28 days, accompanied by shifts in community composition. In contrast, the combined stressor treatment showed a non-additive effect with lower microbial gene abundance throughout the experiment. The response of microbial communities in the sandy sediment was less pronounced, with the most noticeable response seen in the archaeal gene abundances in response to environmental stressors over time. 16S rRNA genes (amoA and nirS were lower in abundance in the combined stressor treatments in sandy sediments. Our results indicated that marine benthic microorganisms, especially in muddy sediments, are susceptible to changes in ocean carbonate chemistry and seawater temperature, which ultimately may have an impact upon key benthic biogeochemical cycles.

  15. Polycyclic aromatic hydrocarbons in ocean sediments from the North Pacific to the Arctic Ocean.

    Science.gov (United States)

    Ma, Yuxin; Halsall, Crispin J; Xie, Zhiyong; Koetke, Danijela; Mi, Wenying; Ebinghaus, Ralf; Gao, Guoping

    2017-08-01

    Eighteen polycyclic aromatic hydrocarbons (PAHs) were measured in surficial sediments along a marine transect from the North Pacific into the Arctic Ocean. The highest average Σ18PAHs concentrations were observed along the continental slope of the Canada Basin in the Arctic (68.3 ± 8.5 ng g(-1) dw), followed by sediments in the Chukchi Sea shelf (49.7 ± 21.2 ng g(-1) dw) and Bering Sea (39.5 ± 11.3 ng g(-1) dw), while the Bering Strait (16.8 ± 7.1 ng g(-1) dw) and Central Arctic Ocean sediments (13.1 ± 9.6 ng g(-1) dw) had relatively lower average concentrations. The use of principal components analysis with multiple linear regression (PCA/MLR) indicated that on average oil related or petrogenic sources contributed ∼42% of the measured PAHs in the sediments and marked by higher concentrations of two methylnaphthalenes over the non-alkylated parent PAH, naphthalene. Wood and coal combustion contributed ∼32%, and high temperature pyrogenic sources contributing ∼26%. Petrogenic sources, such as oil seeps, allochthonous coal and coastally eroded material such as terrigenous sediments particularly affected the Chukchi Sea shelf and slope of the Canada Basin, while biomass and coal combustion sources appeared to have greater influence in the central Arctic Ocean, possibly due to the effects of episodic summertime forest fires. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Total Sediment Thickness of the World's Oceans & Marginal Seas, Version 2

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC's global ocean sediment thickness grid (Divins, 2003) has been updated for the Australian-Antarctic region (60? -155? E, 30? -70? S). New seismic reflection and...

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

    Data.gov (United States)

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

  18. Caesium-137 in sandy sediments of the River Loire (FR): Assessment of an alluvial island evolving over the last 50 years

    Energy Technology Data Exchange (ETDEWEB)

    Detriche, Sebastien; Rodrigues, Stephane; Macaire, Jean-Jacques; Breheret, Jean-Gabriel; Bakyono, Jean-Paul [Universite Francois-Rabelais de Tours, CNRS/INSU UMR 6113 ISTO, Universite d' Orleans Faculte des Sciences et Techniques, Laboratoire de Geologie des Environnements Aquatiques Continentaux, Parc de Grandmont, 37200 Tours (France); Bonte, Philippe [UMR CNRS-CEA 1572, Laboratoire des Sciences du Climat et de l' Environnement - LSCE, CNRS, Domaine du CNRS, Bat. 12, 91198 Gif-sur-Yvette (France); Juge, Philippe [CETU-Elmis ingenieries, Antenne Universitaire en Val de Vienne, 11 quai Danton, 37500 Chinon (France)

    2010-07-01

    Recent sedimentological and morphological evolution of an island in the River Loire (FR) was investigated using the {sup 137}Cs method. This study describes the morphological adjustment of the island in the last 50 years, which corresponds to the increased bed incision of this sandy, multiple-channel environment because of, among other things, the increase in sediment extraction up to 1995. The results show that some {sup 137}Cs can be retained by sandy particles, potentially in clay minerals forming weathering features included in detrital sand grains. From a morphological perspective, significant lateral erosion can be observed in the upstream part of the island, while a weak lateral accretion occurs in its downstream section. Data about {sup 137}Cs and aerial photographs show that the morphology of the island margins has undergone significant changes leading to a lateral migration, while the centre of the island has remained relatively stable or is slowly eroding. The migration of the island depends on: (1) the withdrawal of inherited pre-incision morphological units, such as levees, or the development of new units, such as a channel shelf; (2) water and sediment supply from surrounding channels during flood events; (3) preferential sediment trapping (20 mm year{sup -1}) from the presence of riparian vegetation on the bank of the secondary channel that is subject to narrowing. The sedimentological and morphological response of the island in the context of incision of the Loire river bed is expressed mainly by lateral migration and secondarily by a low vertical adjustment. (authors)

  19. Vertical suspsended sediment fluxes observed from ocean gliders

    Science.gov (United States)

    Merckelbach, Lucas; Carpenter, Jeffrey

    2016-04-01

    Many studies trying to understand a coastal system in terms of sediment transport paths resort to numerical modelling - combining circulation models with sediment transport models. Two aspects herein are crucial: sediment fluxes across the sea bed-water column interface, and the subsequent vertical mixing by turbulence. Both aspects are highly complex and have relatively short time scales, so that the processes involved are implemented in numerical models as parameterisations. Due to the effort required to obtain field observations of suspended sediment concentrations (and other parameters), measurements are scarce, which makes the development and tuning of parameterisations a difficult task. Ocean gliders (autonomous underwater vehicles propelled by a buoyancy engine) provide a platform complementing more traditional methods of sampling. In this work we present observations of suspended sediment concentration (SSC) and dissipation rate taken by two gliders, each equipped with optical sensors and a microstructure sensor, along with current observations from a bottom mounted ADCP, all operated in the German Bight sector of the North Sea in Summer 2014. For about two weeks of a four-week experiment, the gliders were programmed to fly in a novel way as Lagrangian profilers to water depths of about 40 m. The benefit of this approach is that the rate of change of SSC - and other parameters - is local to the water column, as opposed to an unknown composition of temporal and spatial variability when gliders are operated in the usual way. Therefore, vertical sediment fluxes can be calculated without the need of the - often dubious - assumption that spatial variability can be neglected. During the experiment the water column was initially thermally stratified, with a cross-pycnocline diffusion coefficient estimated at 7\\cdot10-5 m2 s-1. Halfway through the experiment the remnants of tropical storm Bertha arrived at the study site and caused a complete mixing of the water

  20. Local inundation distances and regional tsunami recurrence in the Indian Ocean inferred from luminescence dating of sandy deposits in Thailand

    Science.gov (United States)

    Brill, D.; Klasen, N.; Jankaew, K.; Brückner, H.; Kelletat, D.; Scheffers, A.; Scheffers, S.

    2012-07-01

    The Holocene beach-ridge plain of Phra Thong Island (Ko Phra Thong, SW Thailand) provides sedimentary evidence of several palaeotsunamis, in addition to the deposit of the 2004 Indian Ocean tsunami. Due to poor preservation conditions, these palaeoevent layers are restricted to swales. Correlation across beach ridges, which is important e.g. to reconstruct inundation distances, remains a major challenge. A primary tool for establishing a precisely confined correlation of the sand sheets is the use of chronological data. Since the application of radiocarbon dating is limited by the scarcity of appropriate material, this study utilised optically stimulated luminescence (OSL) dating of tsunamigenic quartz grains. Generally, the sediments showed favourable luminescence properties regarding signal intensity, dose recovery and thermal stability. Disturbances of the OSL signal due to partial bleaching were corrected using the minimum age model. At least three palaeoevents - being 490-550, 925-1035 and 1740-2000 yr old - were distinguished by dating the discontinuous sand sheets at four different sites. Besides this chronological framework, the OSL data provide the opportunity to correlate the discontinuous sand sheets between spatially separated sites within the same swale as well as across ridges. This allows for first estimates of inundation distances for the palaeotsunamis documented on Phra Thong Island. Furthermore, the two younger events overlap in age with contemporaneous tsunami and earthquake evidence from other coasts bordering the Indian Ocean.

  1. Local inundation distances and regional tsunami recurrence in the Indian Ocean inferred from luminescence dating of sandy deposits in Thailand

    Directory of Open Access Journals (Sweden)

    D. Brill

    2012-07-01

    Full Text Available The Holocene beach-ridge plain of Phra Thong Island (Ko Phra Thong, SW Thailand provides sedimentary evidence of several palaeotsunamis, in addition to the deposit of the 2004 Indian Ocean tsunami. Due to poor preservation conditions, these palaeoevent layers are restricted to swales. Correlation across beach ridges, which is important e.g. to reconstruct inundation distances, remains a major challenge. A primary tool for establishing a precisely confined correlation of the sand sheets is the use of chronological data. Since the application of radiocarbon dating is limited by the scarcity of appropriate material, this study utilised optically stimulated luminescence (OSL dating of tsunamigenic quartz grains. Generally, the sediments showed favourable luminescence properties regarding signal intensity, dose recovery and thermal stability. Disturbances of the OSL signal due to partial bleaching were corrected using the minimum age model. At least three palaeoevents – being 490–550, 925–1035 and 1740–2000 yr old – were distinguished by dating the discontinuous sand sheets at four different sites. Besides this chronological framework, the OSL data provide the opportunity to correlate the discontinuous sand sheets between spatially separated sites within the same swale as well as across ridges. This allows for first estimates of inundation distances for the palaeotsunamis documented on Phra Thong Island. Furthermore, the two younger events overlap in age with contemporaneous tsunami and earthquake evidence from other coasts bordering the Indian Ocean.

  2. Grain-size distribution characteristics of red sandy sediments in Dongjiang River valley, southern Nanling Mountains,during the MIS2 stage

    Institute of Scientific and Technical Information of China (English)

    ShuHuan Du; BaoSheng Li; DongFeng Niu; XiaoHao Wen; FengNian Wang; XianJiao Ou; Yi Yang; YueJun Si; XinNan Zhao

    2009-01-01

    Layer LJ3 of Linjiang sttrigraphic section in Dongjiang River valley in the south of the Nanling Mountains is a set of red sandy sediments.Measured by thermoluminescence (TL) dating, it was found to be formed in MIS2-9,500±800 yr to 19,600±1,800 yr B.P. After analysis of the grain sizes of the 16 samples (LJ3-100 to LJ3-85) in this layer, it was discovered that (1) The contents of each grain group in different samples are similar. (2) The values of Md, Mz,σ,Sk and Kg vary from LJ3-100 to LJ3-85 in a narrow range. (3) The segments of each sample in the accumulative curves extend parallel with similar slopes. All the three aspects reveal the Aeolian characteristics of Layer LJ3.Therefore, it is thought that Layer LJ3 consists of red sandy sediments formed in MIS2 in the south of Nanling Mountain, which reflects the arid climate at that time.

  3. Regional variation of sediment load of Asian rivers flowing into the ocean

    Institute of Scientific and Technical Information of China (English)

    刘曙光; 丁坚; 华棣; 杨洪林; 李从先; 杨守业

    2001-01-01

    Study of Asian major rivers discharge to the ocean reveals variations of their water discharges and sediment loads, and local characteristic of river sediment concentrations. On the basis of this, the Asian rivers can be divided into three regions: Eurasia Arctic, East Asia, Southeast and South Asia Region. The Eurasia Arctic Region is characteristic of the lowest sediment concentration and load, while the East Asia Region is of the highest sediment concentration and higher sediment load, and the Southeast and South Asia Region yields higher sediment concentration and highest sediment load.

  4. Sediment Monitoring Adjacent to the Barbers Point Ocean Outfall, Oahu, Hawaii, 1986-2002 (NODC Accession 0000819)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sediment in the vicinity of the Barbers Point (Honouliuli) ocean outfall were sampled from 1986-2002. To assess the environmental quality, sediment grain size and...

  5. Geotechnical properties of deep-sea sediments from central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Khadge, N.H.

    Physical and geotechnical properties of 2 sediment cores from the nodule rich area of the Central Indian Ocean Basin are studied to know the sediment characteristics. Average water content of sediment from 2 deep-sea cores is 289% with 151...

  6. Combined Effects of Dam Removal and Past Sediment Mining on a Relatively Large Lowland Sandy Gravelly Bed River (Vienne River, France).

    Science.gov (United States)

    Rodrigues, S.; Ursache, O.; Bouchard, J. P.; Juge, P.

    2014-12-01

    Dam removal is of growing interest for the management of sediment fluxes, morphological evolution and ecological restoration of rivers. If dam removal experiments are well documented for small streams, examples of lowland and large rivers are scarce. We present the morphological response of a relatively large lowland river (Vienne River, France) to a dam removal. The objective is to understand and quantify the morphological adaptation on a reach of 50 km and over 15 years associated with the dam removal and the presence of ancient sand pits located along the riverbed. This study is based on field data collected during 7 surveys performed between 1998 and 2013. This dataset focuses on bed geometry, sediment grain size, and bedload fluxes. It was combined with a 1D numerical model to assess flow dynamics and sediment transport before and after dam removal. Results show that dam removal triggered both regressive and progressive erosions and that discharges higher than 100 m3.s-1 were sufficient to erode the sandy sediments trapped by the dam whereas gravels were mobilised for discharges higher than 300 m3.s-1. Since 1999, large bedload sediment waves coming from upstream migrated downstream at an average celerity of 2.2 km.year-1 and were trapped by three ancient sand pits located downstream. Some of these pits constitute efficient sediment traps even 15 years after dam removal. As a result, between 2002 and 2013, the slope of the river bed adjusted gently and observed morphological processes were minors compared with the time period between 1998 and 2002.

  7. Late Pleistocene glacio-marine sedimentation in the Chukchi Sea, the western Arctic Ocean

    Science.gov (United States)

    Yoon, Seok-Hoon; Joe, Young-Jin; Nam, Seung-Il

    2013-04-01

    In this study, we present the results of sedimentary and echo facies analyses of gravity cores and high-resolution sub-bottom profiling (SBP) data obtained during the 2011 Arctic expedition of R/V Araon (operated by KOPRI) in the Chukchi Sea, the western part of the Arctic Ocean. The gravity cores (248-548 cm long) at 3 stations were collected from the continental shelf and slope areas of the sea, and X-radiographs of sediment slabs were taken from the lengthwise-cut split cores to observe sedimentary structures. Grain size of core sediment was analyzed using standard sieves and a Micrometrics Sedigraph 5000D. High-resolution sub-bottom profiling (SBP) survey was also deployed during the Araon cruise to obtain information on seafloor topography and acoustic characteristics of subsurface sedimentary sequences. On the SBP data (ca. 70 m of the penetration depth), 3 stratigraphic units (SU-1, 2, 3 in ascending order) are recognized by 2 distinctive reflectors within the sequence. In some places, the lowermost boundary (5-20 m deep below seafloor) between SU-1 and 2 is characterized by channel-shaped erosional topography, which is interpreted to have been originated from incision by grounded glaciers or fluvial channels during the sea-level lowstand, most probably LGM. The boundary between SU-2 and 3 is characterized by a prolonged reflection with a relatively flat and low-relief topography in the inner continental shelf, whereas it gradually changes into a higher-relief reflector with small hummocks in the outer shelf and slope areas. Such acoustic and topographic characters are interpreted to indicate the irregular surface of cohesive mass-flow deposits (e.g. debrites and slump deposits). More specifically, the acoustic characters in the SBP data are classified into 5 echo facies on the basis of clarity, continuity, and shape of bottom and sub-bottom echoes together with seafloor topography. Echo facies IIA is most prominent type in SU-3 recorded from the continental

  8. Sediment Load of Asian Rivers flowing into the Oceans and their Regional Variation

    Institute of Scientific and Technical Information of China (English)

    Liu Shuguang; Zheng Yonglai; Zhuge Zhengji; Li Congxian

    2002-01-01

    Study of the major Asian rivers discharge to the ocean reveals variations of their water discharges and sediment loads, and local characteristics of river sediment concentrations. On the basis of this, the Asian rivers fall into three regions, including Eurasia Arctic, East Asia, Southeast and South Asia Regions. The Eurasia Arctic Region is characterized by the lowest sediment concentration and load, while the East Asia Region is of the highest sediment concentration and higher sediment load, and the South-East and South Asia Region yields higher sediment concentration and highest sediment load.The sediment loads of these regions are mainly controlled by climate, geomorphology and tectonic activity. The Eurasia Arctic rivers with large basin areas and water discharge, drain low relief which consists of tundra sediment, thus causing the lowest sediment load. The East Asia rivers with small basin areas and lowest water discharges, drain extensive loess plateau, and transport most erodible loess material, which results in highest sediment concentration. The SE and South Asia rivers originating from the Tibet Plateau have large basin areas and the largest water discharges because of the Summer Monsoon and high rainfall influence, causing the highest sediment load.In Asia, tectonic motion of the Tibet Plateau plays an important role. Those large rivers originating from the Tibet Plateau transport about 50% of the world river sediment load to ocean annually, forming large estuaries and deltas, and consequently exerting a great influence on sedimentation in the coastal zone and shelves.

  9. Assessing the impact of Hurricanes Irene and Sandy on the morphology and modern sediment thickness on the inner continental shelf offshore of Fire Island, New York

    Science.gov (United States)

    Schwab, William C.; Baldwin, Wayne E.; Denny, Jane F.

    2016-01-15

    This report documents the changes in seabed morphology and modern sediment thickness detected on the inner continental shelf offshore of Fire Island, New York, before and after Hurricanes Irene and Sandy made landfall. Comparison of acoustic backscatter imagery, seismic-reflection profiles, and bathymetry collected in 2011 and in 2014 show that sedimentary structures and depositional patterns moved alongshore to the southwest in water depths up to 30 meters during the 3-year period. The measured lateral offset distances range between about 1 and 450 meters with a mean of 20 meters. The mean distances computed indicate that change tended to decrease with increasing water depth. Comparison of isopach maps of modern sediment thickness show that a series of shoreface-attached sand ridges, which are the dominant sedimentary structures offshore of Fire Island, migrated toward the southwest because of erosion of the ridge crests and northeast-facing flanks as well as deposition on the southwest-facing flanks and in troughs between individual ridges. Statistics computed suggest that the modern sediment volume across the about 81 square kilometers of common sea floor mapped in both surveys decreased by 2.8 million cubic meters, which is a mean change of –0.03 meters, which is smaller than the resolution limit of the mapping systems used.

  10. Distribution of detrital minerals and sediment color in western Arctic Ocean and northern Bering Sea sediments: Changes in the provenance of western Arctic Ocean sediments since the last glacial period

    Science.gov (United States)

    Kobayashi, Daisuke; Yamamoto, Masanobu; Irino, Tomohisa; Nam, Seung-Il; Park, Yu-Hyeon; Harada, Naomi; Nagashima, Kana; Chikita, Kazuhisa; Saitoh, Sei-Ichi

    2016-12-01

    This paper describes the distribution of detrital minerals and sediment color in the surface sediments of the western Arctic Ocean and the northern Bering Sea and investigates the relationship between mineral composition and sediment provenance. This relationship was used to determine the provenance of western Arctic Ocean sediments deposited during the last glacial period. Sediment color is governed by water depth, diagenesis, and mineral composition. An a*-b* diagram was used to trace color change during diagenesis in the Arctic Ocean sediments. The mineral composition of surface sediments is governed by grain size and provenance. The feldspar/quartz ratio of the sediments studied was higher on the Siberian side than on the North American side of the western Arctic Ocean. The (chlorite + kaolinite)/illite and chlorite/illite ratios were high in the Bering Sea but decrease northwards in the Chukchi Sea. Thus, these ratios are useful for provenance studies in the Chukchi Sea area as indices of the Beaufort Gyre circulation and the Bering Strait inflow. The sediments deposited during the last glacial period have a lower feldspar/quartz ratio and a higher dolomite intensity than Holocene sediments on the Chukchi Plateau, suggesting a greater contribution of North American grains during the last glacial period.

  11. Reconciling surface ocean productivity, export fluxes and sediment composition in a global biogeochemical ocean model

    Directory of Open Access Journals (Sweden)

    M. Gehlen

    2006-01-01

    Full Text Available This study focuses on an improved representation of the biological soft tissue pump in the global three-dimensional biogeochemical ocean model PISCES. We compare three parameterizations of particle dynamics: (1 the model standard version including two particle size classes, aggregation-disaggregation and prescribed sinking speed; (2 an aggregation-disaggregation model with a particle size spectrum and prognostic sinking speed; (3 a mineral ballast parameterization with no size classes, but prognostic sinking speed. In addition, the model includes a description of surface sediments and organic carbon early diagenesis. Model output is compared to data or data based estimates of ocean productivity, pe-ratios, particle fluxes, surface sediment bulk composition and benthic O2 fluxes. Model results suggest that different processes control POC fluxes at different depths. In the wind mixed layer turbulent particle coagulation appears as key process in controlling pe-ratios. Parameterization (2 yields simulated pe-ratios that compare well to observations. Below the wind mixed layer, POC fluxes are most sensitive to the intensity of zooplankton flux feeding, indicating the importance of zooplankton community composition. All model parameters being kept constant, the capability of the model to reproduce yearly mean POC fluxes below 2000 m and benthic oxygen demand does at first order not dependent on the resolution of the particle size spectrum. Aggregate formation appears essential to initiate an intense biological pump. At great depth the reported close to constant particle fluxes are most likely the result of the combined effect of aggregate formation and mineral ballasting.

  12. Sediment from Northwest Atlantic Ocean acquired in 1978 (ROWE78 shapefile)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Presented in this dataset are data determined from sediments collected by different means during a variety of cruises to the northwest Atlantic Ocean. These data...

  13. Mineralogy of polymetallic nodules and associated sediments from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.

    Todorokite is the dominant mineral phase in the nodules of the northern Central Indian Ocean Basin. These nodules are characterised by a rough surface texture, are relatively rich in Mn, Cu and Ni, and are associated with radiolarian sediments rich...

  14. Google Earth-Based Grand Tours of the World's Ocean Basins and Marine Sediments

    Science.gov (United States)

    St John, K. K.; De Paor, D. G.; Suranovic, B.; Robinson, C.; Firth, J. V.; Rand, C.

    2016-12-01

    The GEODE project has produced a collection of Google Earth-based marine geology teaching resources that offer grand tours of the world's ocean basins and marine sediments. We use a map of oceanic crustal ages from Müller et al (2008; doi:10.1029/2007GC001743), and a set of emergent COLLADA models of IODP drill core data as a basis for a Google Earth tour introducing students to the world's ocean basins. Most students are familiar with basic seafloor spreading patterns but teaching experience suggests that few students have an appreciation of the number of abandoned ocean basins on Earth. Students also lack a valid visualization of the west Pacific where the oldest crust forms an isolated triangular patch and the ocean floor becomes younger towards the subduction zones. Our tour links geographic locations to mechanical models of rifting, seafloor spreading, subduction, and transform faulting. Google Earth's built-in earthquake and volcano data are related to ocean floor patterns. Marine sediments are explored in a Google Earth tour that draws on exemplary IODP core samples of a range of sediment types (e.g., turbidites, diatom ooze). Information and links are used to connect location to sediment type. This tour compliments a physical core kit of core catcher sections that can be employed for classroom instruction (geode.net/marine-core-kit/). At a larger scale, we use data from IMLGS to explore the distribution of the marine sediments types in the modern global ocean. More than 2,500 sites are plotted with access to original data. Students are guided to compare modern "type sections" of primary marine sediment lithologies, as well as examine site transects to address questions of bathymetric setting, ocean circulation, chemistry (e.g., CCD), and bioproductivity as influences on modern seafloor sedimentation. KMZ files, student exercises, and tips for instructors are available at geode.net/exploring-marine-sediments-using-google-earth.

  15. Three perspectives on bedload transport at a sandy gravel beach (Advocate Harbour, Nova Scotia) with focus on sediment properties

    Science.gov (United States)

    Stark, N.; Hay, A. E.; Guest, T.; Hatcher, M. G.; Cheel, R. A.; Barclay, D. J.; Zedel, L. J.; Lake, C. B.

    2012-12-01

    Bedload transport is the major transport mode for coarse sediment in coastal zones. Understanding its mechanisms requires knowledge of the driving force (hydrodynamics), the stabilizing force (sediment properties), and the bed characteristics (bed roughness, bed slope, bedforms). During a 3-week-long field experiment at Advocate Beach, Nova Scotia, bedload transport was targeted from three perspectives: (i) The water column: using a new acoustic Doppler profiler (MFDop), 3D flow velocities were monitored to assess bed shear stress over a range of conditions. Additionally, sediment concentrations close to the bed (~10 cm) were determined by water sampling under calm conditions (0.15-0.6 g/l) and within the shorebreak (1-50 g/l). (ii) The bed: rotary sonars were used to observe the development of ripples and bed elevation change as a measure of ongoing sediment transport. Also, the net displacement of 20 marked cobbles on the seabed surface was measured, revealing significant changes in transport direction and distance (ranging from 0 to 50 m). (iii) The sediment properties: grain size ranged from medium sand to small cobbles. The finer-grained particles were rounded, but showed an elliptic to plate-like shape. Grain size distributions varied significantly across the shoreface as well as under different hydrodynamic conditions. Observed beach cusps were strongly sorted (coarse pebbles at the horns, coarse sand in the bays). Direct shear tests were carried out to determine peak shear strengths of the sediment and friction angles. Peak shear strengths under low normal stress (0.47 kPa) can be compared best to surficial sediment conditions, and did not exceed 9 kPa in the case of the sands. The sediment showed a surprisingly strong dilative behavior during shearing and high friction angles considering the grain size, the low load and low density conditions during the tests. Thus, grain shape and the particle re-organization under shearing played important roles. Finally

  16. Modeling 210Pb-derived mixing activity in ocean margin sediments: Diffusive versus nonlocal mixing

    NARCIS (Netherlands)

    Soetaert, K.E.R.; Herman, P.M.J.; Middelburg, J.J.; Heip, C.H.R.; De Stigter, H.; Van Weering, T.C.E.; Epping, E.; Helder, W.

    1996-01-01

    The influence of sediment mixing on activity versus depth profiles of the radionuclide (210)pb in the upper 20 cm of the sediments has been investigated along a depth transect (208 m- 4500 m, 17 stations) in the OMEX study area (Goban Spur, NE Atlantic Ocean). A hierarchical family of bioturbation/n

  17. Laboratory investigations on the role of sediment surface and ground water chemistry in transport of bacteria through a contaminated Sandy Aquifer

    Science.gov (United States)

    Scholl, M.A.; Harvey, R.W.

    1992-01-01

    The effects of pH and sediment surface characteristics on sorption of indigenous groundwater bacteria were determined using contaminated and uncontaminated aquifer material from Cape Cod, MA. Over the pH range of the aquifer (5-7), the extent of bacterial sorption onto sediment in uncontaminated groundwater was strongly pH-dependent, but relatively pH-insensitive in contaminated groundwater from the site. Bacterial sorption was also affected by the presence of oxyhydroxide coatings (iron, aluminum, and manganese). Surface coating effects were most pronounced in uncontaminated groundwater (pH 6.4 at 10??C). Desorption of attached bacteria (up to 14% of the total number of labeled cells added) occurred in both field and laboratory experiments upon adjustment of groundwater to pH 8. The dependence of bacterial sorption upon environmental conditions suggests that bacterial immobilization could change substantially over relatively short distances in contaminated, sandy aquifers and that effects caused by changes in groundwater geochemistry can be significant.

  18. @iGlobigerina pachyderma@@ (Ehrenberg) in the shelf-slope sediments of northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G

    resulting in the occurrence of this species in the northern Indian Ocean sediments, it is proposed that the forms which occur in the low latitudes (upto 25~'N) in the norhern Indian Ocean be referred to henceforth as (1) (a) @iG. pachyderma@@ (Ehrenberg...

  19. Quantifying trace element and isotope fluxes at the ocean-sediment boundary: a review

    Science.gov (United States)

    Homoky, William B.; Weber, Thomas; Berelson, William M.; Conway, Tim M.; Henderson, Gideon M.; van Hulten, Marco; Jeandel, Catherine; Severmann, Silke; Tagliabue, Alessandro

    2016-11-01

    Quantifying fluxes of trace elements and their isotopes (TEIs) at the ocean's sediment-water boundary is a pre-eminent challenge to understand their role in the present, past and future ocean. There are multiple processes that drive the uptake and release of TEIs, and properties that determine their rates are unevenly distributed (e.g. sediment composition, redox conditions and (bio)physical dynamics). These factors complicate our efforts to find, measure and extrapolate TEI fluxes across ocean basins. GEOTRACES observations are unveiling the oceanic distributions of many TEIs for the first time. These data evidence the influence of the sediment-water boundary on many TEI cycles, and underline the fact that our knowledge of the source-sink fluxes that sustain oceanic distributions is largely missing. Present flux measurements provide low spatial coverage and only part of the empirical basis needed to predict TEI flux variations. Many of the advances and present challenges facing TEI flux measurements are linked to process studies that collect sediment cores, pore waters, sinking material or seawater in close contact with sediments. However, such sampling has not routinely been viable on GEOTRACES expeditions. In this article, we recommend approaches to address these issues: firstly, with an interrogation of emergent data using isotopic mass-balance and inverse modelling techniques; and secondly, by innovating pursuits of direct TEI flux measurements. We exemplify the value of GEOTRACES data with a new inverse model estimate of benthic Al flux in the North Atlantic Ocean. Furthermore, we review viable flux measurement techniques tailored to the sediment-water boundary. We propose that such activities are aimed at regions that intersect the GEOTRACES Science Plan on the basis of seven criteria that may influence TEI fluxes: sediment provenance, composition, organic carbon supply, redox conditions, sedimentation rate, bathymetry and the benthic nepheloid inventory

  20. Environmental change indicated by grain-size variations and trace elements: An example from the sandy-loess sediments from the Doroshivtsy site (Ukraine)

    Science.gov (United States)

    Lehmkuhl, Frank; Schulte, Philipp; Loibl, Christa; Klasen, Nicole; Hauck, Thomas; Kels, Holger

    2014-05-01

    The recently discovered loess section of Doroshivtsy became famous due to archeological findings of the Gravettian. The profile represents a about 9 m sequence of sandy loess, intercalated by more humic horizons. It is situated in a flat gully and at an undercut slope of the Dniester River close to the village Doroshivtsy in the south-western Ukraine. Radiocarbon dating and luminescence ages are conclusive within the expected age range of the Gravettian period (22-28 ka). The loess section is composed mainly of sandy silt and covers the time span from about 26 to 16 ka. This is one of the very few sections in Europe which provides a high resolution sedimentary record including prehistoric finds of the cooling maximum of the last glacial cycle. Based on the field description and the grain size distribution obtained by Laser Diffraction Particle Size Analyzer (Beckman Coulter LS 13 320 PIDS), the profile can be divided into three main genetic units representing changes during the deposition. The upper part (1-3 m) of the profile is characterized by aeolian loess and sand deposition intercalated with a few gravel lines. The middle part (3-6.5 m) of the profile is influenced by aeolian, denudative and weak soil forming processes. The lower part (6.5-9 m) of the section represents a combination of aeolian loess, re-deposited slope material. Additionally, the whole part is affected by hydromorphic conditions. As the sediment is rather homogeneous sandy silt U-ratio and GSI did not show any distinct variations. However, calculations with different grain-size ratios show that a fine silt to fine sand ratio (SiS-ratio) of 3.5 to 8.1 µm and 69.6 to 161.1 µm provide clear peaks. These variations of the SiS-ratio represent environmental changes which are also observed by structures and weak soil formations in the section during field work and fit also to the different archeological layers. In addition, geochemical analysis show comparable results to the SiS-ratio and provide

  1. Certified reference materials for radionuclides in Bikini Atoll sediment (IAEA-410) and Pacific Ocean sediment (IAEA-412)

    DEFF Research Database (Denmark)

    Pham, M. K.; van Beek, P.; Carvalho, F. P.

    2016-01-01

    The preparation and characterization of certified reference materials (CRMs) for radionuclide content in sediments collected offshore of Bikini Atoll (IAEA-410) and in the open northwest Pacific Ocean (IAEA-412) are described and the results of the certification process are presented. The certifi...

  2. Deep ocean ventilation, carbon isotopes, marine sedimentation and the deglacial CO2 rise

    Directory of Open Access Journals (Sweden)

    C. Heinze

    2011-07-01

    Full Text Available The link between the atmospheric CO2 level and the ventilation state of the deep ocean is an important building block of the key hypotheses put forth to explain glacial-interglacial CO2 fluctuations. In this study, we systematically examine the sensitivity of atmospheric CO2 and its carbon isotope composition to changes in deep ocean ventilation, the ocean carbon pumps, and sediment formation in a global 3-D ocean-sediment carbon cycle model. Our results provide support for the hypothesis that a break up of Southern Ocean stratification and invigorated deep ocean ventilation were the dominant drivers for the early deglacial CO2 rise of ~35 ppm between the Last Glacial Maximum and 14.6 ka BP. Another rise of 10 ppm until the end of the Holocene is attributed to carbonate compensation responding to the early deglacial change in ocean circulation. Our reasoning is based on a multi-proxy analysis which indicates that an acceleration of deep ocean ventilation during early deglaciation is not only consistent with recorded atmospheric CO2 but also with the reconstructed opal sedimentation peak in the Southern Ocean at around 16 ka BP, the record of atmospheric δ13CCO2, and the reconstructed changes in the Pacific CaCO3 saturation horizon.

  3. Mineralogical study of surface sediments in the western Arctic Ocean and their implications for material sources

    Institute of Scientific and Technical Information of China (English)

    DONG Linsen; SHI Xuefa; LIU Yanguang; FANG Xisheng; CHEN Zhihua; WANG Chunjuan; ZOU Jianjun; HUANG Yuanhui

    2014-01-01

    Mineralogical analysis was performed on bulk sediments of 79 surface samples using X-ray diffraction. The analytical results, combined with data on ocean currents and the regional geological background, were used to investigate the mineral sources. Mineral assemblages in sediments and their distribution in the study area indicate that the material sources are complex. (1) Feldspar is abundant in the sediments of the middle Chukchi Sea near the Bering Strait, originating from sediments in the Anadyr River carried by the Anadyr Current. Sediments deposited on the western side of the Chukchi Sea are rich in feldspar. Compared with other areas, sediments in this region are rich in hornblende transported from volcanic and sedimentary rocks in Siberia by the Anadyr Stream and the Siberian Coastal Current. Sediments in the eastern Chukchi Sea are rich in quartz sourced from sediments of the Yukon and Kuskokwim rivers carried by the Alaska Coastal Current. Sediments in the northern Chukchi Sea are rich in quartz and carbonates from the Mackenzie River sediments. (2) Sediments of the southern and central Canada Basin contain little calcite and dolomite, mainly due to the small impact of the Beaufort Gyre carrying carbonates from the Canadian Arctic Islands. Compared with other areas, the mica content in the region is high, implying that the Laptev Sea is the main sediment source for the southern and central Canada Basin. In the other deep sea areas, calcite and dolomite levels are high caused by the input of large amounts of sediment carried by the Beaufort Gyre from the Canadian Arctic Islands (Banks and Victoria). The Siberian Laptev Sea also provides small amounts of sediment for this region. Furthermore, the Atlantic mid-water contributes some fine-grained material to the entire deep western Arctic Ocean.

  4. Adsorption and desorption of arsenate on sandy sediments from contaminated and uncontaminated saturated zones: Kinetic and equilibrium modeling.

    Science.gov (United States)

    Hafeznezami, Saeedreza; Zimmer-Faust, Amity G; Dunne, Aislinn; Tran, Tiffany; Yang, Chao; Lam, Jacquelyn R; Reynolds, Matthew D; Davis, James A; Jay, Jennifer A

    2016-08-01

    Application of empirical models to adsorption of contaminants on natural heterogeneous sorbents is often challenging due to the uncertainty associated with fitting experimental data and determining adjustable parameters. Sediment samples from contaminated and uncontaminated portions of a study site in Maine, USA were collected and investigated for adsorption of arsenate [As(V)]. Two kinetic models were used to describe the results of single solute batch adsorption experiments. Piecewise linear regression of data linearized to fit pseudo-first order kinetic model resulted in two distinct rates and a cutoff time point of 14-19 h delineating the biphasic behavior of solute adsorption. During the initial rapid adsorption stage, an average of 60-80% of the total adsorption took place. Pseudo-second order kinetic models provided the best fit to the experimental data (R(2) > 0.99) and were capable of describing the adsorption over the entire range of experiments. Both Langmuir and Freundlich isotherms provided reasonable fits to the adsorption data at equilibrium. Langmuir-derived maximum adsorption capacity (St) of the studied sediments ranged between 29 and 97 mg/kg increasing from contaminated to uncontaminated sites. Solid phase As content of the sediments ranged from 3.8 to 10 mg/kg and the As/Fe ratios were highest in the amorphous phase. High-pH desorption experiments resulted in a greater percentage of solid phase As released into solution from experimentally-loaded sediments than from the unaltered samples suggesting that As(V) adsorption takes place on different reversible and irreversible surface sites.

  5. Intrinsic rates of petroleum hydrocarbon biodegradation in Gulf of Mexico intertidal sandy sediments and its enhancement by organic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Mortazavi, Behzad, E-mail: bmortazavi@ua.edu [University of Alabama, Department of Biological Sciences, Box 870344, University of Alabama, Tuscaloosa, AL 35487 (United States); Dauphin Island Sea Lab, 101 Bienville Boulevard, Dauphin Island, AL, 36528 (United States); Horel, Agota [University of Alabama, Department of Biological Sciences, Box 870344, University of Alabama, Tuscaloosa, AL 35487 (United States); Dauphin Island Sea Lab, 101 Bienville Boulevard, Dauphin Island, AL, 36528 (United States); Beazley, Melanie J.; Sobecky, Patricia A. [University of Alabama, Department of Biological Sciences, Box 870344, University of Alabama, Tuscaloosa, AL 35487 (United States)

    2013-01-15

    The rates of crude oil degradation by the extant microorganisms in intertidal sediments from a northern Gulf of Mexico beach were determined. The enhancement in crude oil degradation by amending the microbial communities with marine organic matter was also examined. Replicate mesocosm treatments consisted of: (i) controls (intertidal sand), (ii) sand contaminated with crude oil, (iii) sand plus organic matter, and (iv) sand plus crude oil and organic matter. Carbon dioxide (CO{sub 2}) production was measured daily for 42 days and the carbon isotopic ratio of CO{sub 2} (δ{sup 13}CO{sub 2}) was used to determine the fraction of CO{sub 2} derived from microbial respiration of crude oil. Bacterial 16S rRNA clone library analyses indicated members of Actinobacteria, Bacteroidetes, and Chloroflexi occurred exclusively in control sediments whereas Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Firmicutes occurred in both control and oil contaminated sediments. Members of the hydrocarbon-degrading genera Hydrocarboniphaga, Pseudomonas, and Pseudoxanthomonas were found primarily in oil contaminated treatments. Hydrocarbon mineralization was 76% higher in the crude oil amended with organic matter treatment compared to the rate in the crude oil only treatment indicating that biodegradation of crude oil in the intertidal zone by an extant microbial community is enhanced by input of organic matter.

  6. Assessing modern rates of river sediment discharge to the ocean using satellite gravimetry

    Science.gov (United States)

    Mouyen, Maxime; Longuevergne, Laurent; Steer, Philippe; Crave, Alain; Lemoine, Jean-Michel; Save, Himanshu; Robin, Cécile

    2017-04-01

    Worldwide rivers annually export about 19 Gigatons of sediments to the ocean that mostly accumulate in the coastal zones and on the continental shelves. This sediment discharge testifies of the intensity of continental erosion and records changes in climate, tectonics and human activity. However, natural and instrumental uncertainties inherent to the in-situ measurements of sediment discharge prevent from conclusive estimates to better understand these linkages. Here we develop a new method, using the Gravity Recovery and Climate Experiment (GRACE) satellite data, to infer mass-integrative estimates of sediment discharge of large rivers to the ocean. GRACE satellite provides global gravity time series that have proven useful for quantifying mass transport, including continental water redistribution at the Earth surface (ice sheets and glaciers melting, groundwater storage variations) but has been seldom used for monitoring sediment mass transfers so far. Here we pair the analysis of regularized GRACE solutions at high spatial resolution corrected from all known contributions (hydrology, ocean, atmosphere) to a particle tracking model that predicts the location of the sediment sinks for 13 rivers with the highest sediments loads in the world. We find that the resulting GRACE-derived sediment discharges off the mouth of the Amazon, Ganges-Brahmaputra, Changjiang (Yangtze), Indus, Magdalena, Godavari and Mekong rivers are consistent with in-situ measurements. Our results suggest that the lack of time continuity and of global coverage in terrestrial sediment discharge measurements could be reduced by using GRACE, which provides global and continuous data since 2002. GRACE solutions are regularly improved and new satellite gravity missions are being prepared hence making our approach even more relevant in a near future. The accumulation of sediments over time will keep increasing the signal to noise ratio of the gravity time series, which will improve the precision of

  7. Optimizing Standard Sequential Extraction Protocol With Lake And Ocean Sediments

    Science.gov (United States)

    The environmental mobility/availability behavior of radionuclides in soils and sediments depends on their speciation. Experiments have been carried out to develop a simple but robust radionuclide sequential extraction method for identification of radionuclide partitioning in sed...

  8. Organophosphate Ester Flame Retardants and Plasticizers in Ocean Sediments from the North Pacific to the Arctic Ocean.

    Science.gov (United States)

    Ma, Yuxin; Xie, Zhiyong; Lohmann, Rainer; Mi, Wenying; Gao, Guoping

    2017-04-04

    The presence of organophosphate ester (OPE) flame retardants and plasticizers in surface sediment from the North Pacific to Arctic Ocean was observed for the first time during the fourth National Arctic Research Expedition of China in the summer of 2010. The samples were analyzed for three halogenated OPEs [tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), and tris(dichloroisopropyl) phosphate], three alkylated OPEs [triisobutyl phosphate (TiBP), tri-n-butyl phosphate, and tripentyl phosphate], and triphenyl phosphate. Σ7OPEs (total concentration of the observed OPEs) was in the range of 159-4658 pg/g of dry weight. Halogenated OPEs were generally more abundant than the nonhalogenated OPEs; TCEP and TiBP dominated the overall concentrations. Except for that of the Bering Sea, Σ7OPEs values increased with increasing latitudes from Bering Strait to the Central Arctic Ocean, while the contributions of halogenated OPEs (typically TCEP and TCPP) to the total OPE profile also increased from the Bering Strait to the Central Arctic Ocean, indicating they are more likely to be transported to the remote Arctic. The median budget of 52 (range of 17-292) tons for Σ7OPEs in sediment from the Central Arctic Ocean represents only a very small amount of their total production volume, yet the amount of OPEs in Arctic Ocean sediment was significantly larger than the sum of polybrominated diphenyl ethers (PBDEs) in the sediment, indicating they are equally prone to long-range transport away from source regions. Given the increasing level of production and usage of OPEs as substitutes of PBDEs, OPEs will continue to accumulate in the remote Arctic.

  9. Enrichments in authigenic uranium in glacial sediments of the Southern Ocean; Enrichissement en uranium authigene dans les sediments glaciaires de l'ocean Austral

    Energy Technology Data Exchange (ETDEWEB)

    Dezileau, L. [Universidad de Conception, Programa Regional de Oceanografia Fisica y Climat PROFC, Y Centro de Investigacion Oceanografica (Chile); Bareille, G. [Pau Univ., Lab. de Chimie Analytique Bio-Inorganique et Environnement, EP-CNRS 132, 64 (France); Reyss, J.L. [CEA Saclay, Direction des Sciences de la Matiere, Lab. des Sciences du Climat et de L' environnement, Lab. Mixte CEA-CNRS, 91 - Gif-sur-Yvette (France)

    2002-11-01

    Four sediment cores from the Polar frontal zone and the Antarctic zone in the Indian sector of the Southern Ocean present an increase of authigenic uranium during glacial periods. We show that this increase in uranium is due to a combination of (i) an increase in the lateral transport of organic matter, (ii) a decrease in the oxygen in deep waters, and (iii) a process of diagenesis. It appears that uranium concentration cannot be used as a proxy of paleo-productivity in the Southern Ocean, as previously suggested by Kumar et al. in 1995. (authors)

  10. Modeling the sediment transport induced by deep sea mining in the Pacific Ocean

    Science.gov (United States)

    Purkiani, Kaveh; Paul, André; Schulz, Michael; Vink, Annemiek; Walter, Maren

    2017-04-01

    A numerical modeling study is conducted in the German license area in northeastern Pacific Ocean to investigate the sediment dispersal of mining exploitation. A sediment transport module is implemented in a hydrodynamic model. All differently sized particles can aggregate and break up until equilibrium floc sizes are obtained. A nested model approach using the MITgcm (Massachusetts Institute of Technology general circulation model) is applied and validated against hydrographic and hydrodynamic measurements obtained in this region. Two different sediment discharge scenarios have been examined to investigate the effect of flocculation on sediment transport distribution in the deep ocean. The suspended sediment is mainly influenced by a dominant SW current far away from the sediment discharge location. Independent of initial particle size all initial particles larger than 30 μm attain similar floc size equilibrium. In contrast to coastal seas and estuaries where floc size equilibrium can be obtained in a few hours, due to low shear rate (G) the flocculation process at deep ocean is completed within 1˜2 days. Considering temporal evolution of the floc size in the model, an increase in floc sinking velocity consequently enhances the sediment deposition at seafloor. The analysis of different sediment concentration scenarios suggests that floc sinking velocity increases at higher suspended sediment concentration (SSC). The presence of a dominant current in this region induces a fine sediment plume in SW direction. The dispersed SSC plume at 20 km downstream the discharge location is able to form the flocculation process and induces a spatial variation of floc size and floc sinking velocity.

  11. Sand on the move: Post Hurricane Sandy analysis of the coastal sediment budget and bedform migration at Jones Inlet, Long Island, NY

    Science.gov (United States)

    Bales, M. K.; Goff, J. A.; Austin, J. A.; Flood, R. D.; Christensen, B. A.; Browne, C. M.; Saustrup, S.

    2013-12-01

    Hurricane Sandy struck the Northeast coast of the United States on October 29, 2012. Although sustained winds were downgraded to ~70 kts upon landfall, the vast area of the storm along with the direction of impact resulted in major storm-surge flooding and damage, as well as significant changes to the morphology of the coast-line, altering the characteristics of major barrier islands, inlets, and estuaries. A January 2013 post-storm survey aboard the R/V Pritchard, conducted by the University of Texas Institute for Geophysics, Stony Brook University, and Adelphi University, sought to investigate the impact of this post-tropical cyclone on the southwestern coast of Long Island, NY which sustained storm surges of up to 4 m above normal sea level. The objective of this project is to gain insight on the sedimentological volume changes and bathymetrical alterations made on the seafloor within Jones Inlet and the immediate estuaries behind Jones Beach and Long Beach Island. By studying these changes we hope to gain a better understanding of how large cyclonic storms alter sediment volumes and seafloor topography within major inlets and estuarine systems. These modifications can be observed in post-storm multibeam swath bathymetry and backscatter when compared to similar pre-storm data collected in 2010 by Stony Brook University. Post-storm CHIRP seismic reflection data were also collected, in order to define stratigraphic geometries, as well as grab samples to determine grain size distributions and ground truth for the backscatter data. The acoustic reflections imaged in the CHIRP data allow basal reflectors and dominate horizons to be traced throughout the inlet and estuaries. Our analysis focuses on (1) defining and quantifying areas of deposition and erosion from before-and-after bathymetry data; (2) comparing bedform patterns and grain size distributions from before-and-after backscatter and grab sample analysis; and (3) defining stratal geometries of the shallow

  12. Late Quaternary stratigraphy and sedimentation patterns in the western Arctic Ocean

    Science.gov (United States)

    Polyak, L.; Bischof, J.; Ortiz, J.D.; Darby, D.A.; Channell, J.E.T.; Xuan, C.; Kaufman, D.S.; Lovlie, R.; Schneider, D.A.; Eberl, D.D.; Adler, R.E.; Council, E.A.

    2009-01-01

    Sediment cores from the western Arctic Ocean obtained on the 2005 HOTRAX and some earlier expeditions have been analyzed to develop a stratigraphic correlation from the Alaskan Chukchi margin to the Northwind and Mendeleev-Alpha ridges. The correlation was primarily based on terrigenous sediment composition that is not affected by diagenetic processes as strongly as the biogenic component, and paleomagnetic inclination records. Chronostratigraphic control was provided by 14C dating and amino-acid racemization ages, as well as correlation to earlier established Arctic Ocean stratigraphies. Distribution of sedimentary units across the western Arctic indicates that sedimentation rates decrease from tens of centimeters per kyr on the Alaskan margin to a few centimeters on the southern ends of Northwind and Mendeleev ridges and just a few millimeters on the ridges in the interior of the Amerasia basin. This sedimentation pattern suggests that Late Quaternary sediment transport and deposition, except for turbidites at the basin bottom, were generally controlled by ice concentration (and thus melt-out rate) and transportation distance from sources, with local variances related to subsurface currents. In the long term, most sediment was probably delivered to the core sites by icebergs during glacial periods, with a significant contribution from sea ice. During glacial maxima very fine-grained sediment was deposited with sedimentation rates greatly reduced away from the margins to a hiatus of several kyr duration as shown for the Last Glacial Maximum. This sedimentary environment was possibly related to a very solid ice cover and reduced melt-out over a large part of the western Arctic Ocean.

  13. Simulating the modern δ30Si distribution in the oceans and in marine sediments

    Science.gov (United States)

    Gao, S.; Wolf-Gladrow, D. A.; Völker, C.

    2016-02-01

    The δ30Si of biogenic silica (δ30SiBSi) in marine sediments is a promising proxy for the reconstruction of silicic acid utilization by diatoms in the geological past. The application of this proxy, however, requires an understanding of the modern δ30Si distributions and their controlling mechanisms. Here we present results from a modern climate simulation with a coupled ocean-sediment model that includes a prognostic formulation of biogenic silica production with concurrent silicon isotopic fractionation. In agreement with previous studies, biological fractionation combined with physical transport and mixing determines the oceanic distribution of simulated δ30Si. A new finding is a distinct seasonal cycle of δ30Si in the surface ocean, which is inversely related to that of silicic acid concentration and mixed layer depth. We also provide the first simulation results of sedimentary δ30Si, which reveal that (1) the δ30SiBSi distribution in the surface sediment reflects the exported δ30SiBSi signal from the euphotic zone and (2) the dissolution of biogenic silica in the sediment acts as a source of relatively light δ30Si into the bottom waters of the polar oceans, while it is a source of heavier δ30Si to the subtropical South Atlantic and South Pacific.

  14. Ammolagena clavata (Jones and Parker, 1860), an agglutinated benthic foraminiferal species - first report from the Recent sediments, Arabian Sea, Indian Ocean region

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Mazumder, A.; Saraswat, R.

    The rare presence of the agglutinated foraminiferal species Ammolagena clavata is presented for the first time from the Recent sediments of the Indian Ocean region. This species has previously been reported in Recent sediments from all other oceans...

  15. Sediment Monitoring and Benthic Faunal Sampling Adjacent to the Barbers Point Ocean Outfall, Oahu, Hawaii, 1986-2010 (NODC Accession 9900098)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic fauna and sediment in the vicinity of the Barbers Point (Honouliuli) ocean outfall were sampled from 1986-2010. To assess the environmental quality, sediment...

  16. Sediment monitoring and benthic faunal sampling adjacent to the Sand Island ocean outfall, Oahu, Hawaii, 1986-2010 (NODC Accession 9900088)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic fauna and sediment in the vicinity of the Sand Island ocean outfall were sampled from 1986-2010. To assess the environmental quality, sediment grain size and...

  17. Certified reference materials for radionuclides in Bikini Atoll sediment (IAEA-410) and Pacific Ocean sediment (IAEA-412).

    Science.gov (United States)

    Pham, M K; van Beek, P; Carvalho, F P; Chamizo, E; Degering, D; Engeler, C; Gascó, C; Gurriaran, R; Hanley, O; Harms, A V; Herrmann, J; Hult, M; Ikeuchi, Y; Ilchmann, C; Kanisch, G; Kis-Benedek, G; Kloster, M; Laubenstein, M; Llaurado, M; Mas, J L; Nakano, M; Nielsen, S P; Osvath, I; Povinec, P P; Rieth, U; Schikowski, J; Smedley, P A; Suplinska, M; Sýkora, I; Tarjan, S; Varga, B; Vasileva, E; Zalewska, T; Zhou, W

    2016-03-01

    The preparation and characterization of certified reference materials (CRMs) for radionuclide content in sediments collected offshore of Bikini Atoll (IAEA-410) and in the open northwest Pacific Ocean (IAEA-412) are described and the results of the certification process are presented. The certified radionuclides include: (40)K, (210)Pb ((210)Po), (226)Ra, (228)Ra, (228)Th, (232)Th, (234)U, (238)U, (239)Pu, (239+240)Pu and (241)Am for IAEA-410 and (40)K, (137)Cs, (210)Pb ((210)Po), (226)Ra, (228)Ra, (228)Th, (232)Th, (235)U, (238)U, (239)Pu, (240)Pu and (239+240)Pu for IAEA-412. The CRMs can be used for quality assurance and quality control purposes in the analysis of radionuclides in sediments, for development and validation of analytical methods and for staff training. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Bibliography of sandy beaches and sandy beach organisms on the African continent

    CSIR Research Space (South Africa)

    Bally, R

    1986-01-01

    Full Text Available This bibliography covers the literature relating to sandy beaches on the African continent and outlying islands. The bibliography lists biological, chemical, geographical and geological references and covers shallow marine sediments, surf zones off...

  19. [Diversity and bioactivities of culturable marine actinobacteria isolated from mangrove sediment in Indian Ocean].

    Science.gov (United States)

    He, Jie; Zhang, Daofeng; Xu, Ying; Zhang, Xiaomei; Tang, Shukun; Xu, Lihua; Li, Wenjun

    2012-10-04

    In order to explore the diversity, antimicrobial activity and enzyme-producing activity of marine actinobacteria isolated from mangrove sediments in Indian Ocean. Eight sediments collected from mangrove sediments in Indian Ocean were treated by the plate dilution method and spread on 24 isolation media only containing sole carbon source for energy. Marine actinobacteria were isolated and identified by 16S rRNA gene sequence analysis. The antimicrobial activity and enzyme-producing activity of isolated strains were further detected by spot planting method. In total 139 representative strains were selected from 521 isolates, and they were further sequenced and performed phylogenetic analysis based on their 16S rRNA gene sequences. There were 35 strains identified as potential novel species. Antimicrobial activity was detected in Bacillus subtilis, Candida albicans, Escherichia coli, Staphylococcus aureus, Aspergillus niger. Enzyme-producing activity for protease cellulase, amylase and esterase were 36.5%, 26.5%, 22.4% and 15.9%, respectively. Diverse marine actinobacteria were discovered in mangrove sediment in Indian Ocean, which have antimicrobial and enzyme activity.

  20. Potentially bioavailable iron delivery by iceberg-hosted sediments and atmospheric dust to the polar oceans

    Science.gov (United States)

    Raiswell, Robert; Hawkings, Jon R.; Benning, Liane G.; Baker, Alex R.; Death, Ros; Albani, Samuel; Mahowald, Natalie; Krom, Michael D.; Poulton, Simon W.; Wadham, Jemma; Tranter, Martyn

    2016-07-01

    Iceberg-hosted sediments and atmospheric dust transport potentially bioavailable iron to the Arctic and Southern oceans as ferrihydrite. Ferrihydrite is nanoparticulate and more soluble, as well as potentially more bioavailable, than other iron (oxyhydr)oxide minerals (lepidocrocite, goethite, and hematite). A suite of more than 50 iceberg-hosted sediments contain a mean content of 0.076 wt % Fe as ferrihydrite, which produces iceberg-hosted Fe fluxes ranging from 0.7 to 5.5 and 3.2 to 25 Gmoles yr-1 to the Arctic and Southern oceans respectively. Atmospheric dust (with little or no combustion products) contains a mean ferrihydrite Fe content of 0.038 wt % (corresponding to a fractional solubility of ˜ 1 %) and delivers much smaller Fe fluxes (0.02-0.07 Gmoles yr-1 to the Arctic Ocean and 0.0-0.02 Gmoles yr-1 to the Southern Ocean). New dust flux data show that most atmospheric dust is delivered to sea ice where exposure to melting/re-freezing cycles may enhance fractional solubility, and thus fluxes, by a factor of approximately 2.5. Improved estimates for these particulate sources require additional data for the iceberg losses during fjord transit, the sediment content of icebergs, and samples of atmospheric dust delivered to the polar regions.

  1. Fate of copper complexes in hydrothermally altered deep-sea sediments from the Central Indian Ocean Basin.

    Science.gov (United States)

    Chakraborty, Parthasarathi; Sander, Sylvia G; Jayachandran, Saranya; Nath, B Nagender; Nagaraju, G; Chennuri, Kartheek; Vudamala, Krushna; Lathika, N; Mascarenhas-Pereira, Maria Brenda L

    2014-11-01

    The current study aims to understand the speciation and fate of Cu complexes in hydrothermally altered sediments from the Central Indian Ocean Basin and assess the probable impacts of deep-sea mining on speciation of Cu complexes and assess the Cu flux from this sediment to the water column in this area. This study suggests that most of the Cu was strongly associated with different binding sites in Fe-oxide phases of the hydrothermally altered sediments with stabilities higher than that of Cu-EDTA complexes. The speciation of Cu indicates that hydrothermally influenced deep-sea sediments from Central Indian Ocean Basin may not significantly contribute to the global Cu flux. However, increasing lability of Cu-sediment complexes with increasing depth of sediment may increase bioavailability and Cu flux to the global ocean during deep-sea mining. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Nitrogen cycling in a deep ocean margin sediment (Sagami Bay, Japan)

    DEFF Research Database (Denmark)

    Glud, Ronnie Nøhr; Thamdrup, C.; Stahl, H

    2009-01-01

    On the basis of in situ NO3- microprofiles and chamber incubations complemented by laboratory-based assessments of anammox and denitrification we evaluate the nitrogen turnover of an ocean margin sediment at 1450-m water depth. In situ NO3- profiles horizontally separated by 12 mm reflected highly...... metabolism for 12-52 d, contributed only to a minor extent to the overall N-2 production. The microbial activity in the surface sediment is a net nutrient sink of similar to 1.1 mmol N m(-2) d(-1), which aligns with many studies performed in coastal and shelf environments. Continental margin areas can act...

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

    DEFF Research Database (Denmark)

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

    2006-01-01

    In this study, the coccolith compositions of 213 surface sediment samples from the South Atlantic and Southern Ocean were analysed with respect to the environmental parameters of the overlying surface waters. From this data set, the abundance patterns of the main species and their ecological...... species, six surface sediment assemblages have been identified, which reflect the distribution and characteristics of the overlying surface waters. Their distribution appears to be mainly a function of the relative position of the nutricline and thermocline in the overlying photic zone. © 2006 Elsevier...

  4. High rates of microbial carbon turnover in sediments in the deepest oceanic trench on Earth

    DEFF Research Database (Denmark)

    Glud, Ronnie N.; Wenzhöfer, Frank; Middelboe, Mathias

    2013-01-01

    Microbes control the decomposition of organic matter in marine sediments. Decomposition, in turn, contributes to oceanic nutrient regeneration and influences the preservation of organic carbon(1). Generally, rates of benthic decomposition decline with increasing water depth, although given the vast...... deposition in the trench. We conclude that the elevated deposition of organic matter at Challenger Deep maintains intensified microbial activity at the extreme pressures that characterize this environment....

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

    Science.gov (United States)

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

    1999-01-01

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

  6. Empirical evidence reveals seasonally dependent reduction in nitrification in coastal sediments subjected to near future ocean acidification

    NARCIS (Netherlands)

    Braeckman, U.; Van Colen, C.; Guilini, K.; Van Gansbeke, D.; Soetaert, K.; Vincx, M.; Vanaverbeke, J.

    2014-01-01

    Research so far has provided little evidence that benthic biogeochemical cycling is affected by ocean acidification under realistic climate change scenarios. We measured nutrient exchange and sediment community oxygen consumption (SCOC) rates to estimate nitrification in natural coastal permeable

  7. Empirical evidence reveals seasonally dependent reduction in nitrification in coastal sediments subjected to near future ocean acidification

    NARCIS (Netherlands)

    Braeckman, U.; Van Colen, C.; Guilini, K.; Van Gansbeke, D.; Soetaert, K.; Vincx, M.; Vanaverbeke, J.

    2014-01-01

    Research so far has provided little evidence that benthic biogeochemical cycling is affected by ocean acidification under realistic climate change scenarios. We measured nutrient exchange and sediment community oxygen consumption (SCOC) rates to estimate nitrification in natural coastal permeable an

  8. Orbital-Scale Cyclostratigraphy and Ice Volume Fluctuations from Arctic Ocean Sediments

    Science.gov (United States)

    Cronin, T. M.; Marzen, R.; DeNinno, L. H.

    2014-12-01

    Deep-sea foraminiferal oxygen isotope curves (δ18Of) are excellent paleoclimate records but are limited as proxies of global ice volume history during orbital glacial-interglacial cycles (GIC) due to the influence of deep-sea bottom water temperature, regional hydrography, ocean circulation and other factors affecting δ18Of. A more direct source of northern hemisphere [NH] ice history comes from central Arctic Ocean (CAO) submarine ridges (Northwind, Mendeleev, Lomonosov) where, at orbital timescales, sedimentation is controlled by the growth and decay of ice sheets, ice shelves, and sea ice. Calcareous microfossil density in CAO sediments is one of many proxies, such as manganese concentrations, grain size, bulk density, color, mineral content, organic geochemistry, and foraminiferal δ18O, that reveal GIC changes in ice cover, biological productivity, and primary and post-depositional sediment processes. In order to better understand NH ice history, we constructed 600-kyr-long stacked records of Arctic foraminiferal and ostracode density (AFD, AOD) from 19 CAO sediment cores following stacking and astronomical tuning procedures used for deep-sea δ18Of curves. Results show discrepancies between the Arctic AFD and AOD curves, the LR04 δ18Of stack (Lisiecki and Raymo 2005, Paleoceanography), the Red Sea and Mediterranean δ18Of sea level curves (Rohling et al. 2014 Nature), and modeled Antarctic Ice Sheet volume, suggesting asynchronous polar ice sheet behavior in the two hemispheres, notably during MIS 3, 5a, 5c, 7d, and 11.

  9. Biological, physical, nutrients, sediment, and other data from sediment sampler-grab, bottle, and CTD casts in the Arabian Sea, Equatorial Pacific Ocean, Northeast Atlantic Ocean, and Southern Oceans as part of the Long Term Monitoring East-West Flower Garden Banks project from 08 January 1995 to 08 April 1998 (NODC Accession 0001155)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Biological, physical, nutrients, sediment, and other data were collected using sediment sampler-grab, bottle and CTD casts in the Arabian Sea, North/South Pacific...

  10. An ultra-high resolution last deglacial marine sediment records of the Northwest Atlantic Ocean

    Science.gov (United States)

    Rashid, H.; Piper, D.; Marche, B.; Vermooten, M.; Lazar, K.; Brockway, B.

    2016-12-01

    Lack of high sedimentation rate records of past changes pertaining to the late Pleistocene Laurentide ice-sheet (LIS) dynamics has prevented efforts to differentiate the various forcings in modulating abrupt climate changes. Here, we present an ultra-high resolution sediment record spanning approximately 1,500 km of the Eastern Canadian continental margin. The new record comprises four sediment cores which were collected from the northwest Labrador Sea (i.e., Saglek Bank) to southwestern Flemish Pass to the southeast Grand Banks in outer shelf and slope settings. Fifty new 14C-accelerator mass spectrometric dates were obtained to construct the stratigraphy. The total sediment thickness of the new record is 41 m covering the past 26 ka with 1.58/ka mean sediment rate, the highest sediment rate ever reported from the Northwest Atlantic Ocean for this time interval. Further, the temporal resolution of the record varies from a couple of decades to centuries depending on the time interval. X-ray fluorescence (XRF) data in conjunction with physical properties of sediments and petrology allowed us to distinguish sediment delivered by major ice-streams of the LIS namely the Hudson Strait, Hopedale Saddle, and Cumberland Sound ice streams. Heinrich layers 1 and 2 are well identified by their Labrador Sea specific characteristics. The so-called Younger Dryas equivalent Heinrich layer H0 was identified in these cores but the timing of onset of H0 has an offset by nearly 1,000 years with that of the 12.9 ka, suggesting that the YD event was not initiated by the Hudson Strait compared to other Heinrich events.

  11. Deep water masses and sediments are main compartments for polychlorinated biphenyls in the Arctic Ocean.

    Science.gov (United States)

    Sobek, Anna; Gustafsson, Örjan

    2014-06-17

    There is a wealth of studies of polychlorinated biphenyls (PCB) in surface water and biota of the Arctic Ocean. Still, there are no observation-based assessments of PCB distribution and inventories in and between the major Arctic Ocean compartments. Here, the first water column distribution of PCBs in the central Arctic Ocean basins (Nansen, Amundsen, and Makarov) is presented, demonstrating nutrient-like vertical profiles with 5-10 times higher concentrations in the intermediate and deep water masses than in surface waters. The consistent vertical profiles in all three Arctic Ocean basins likely reflect buildup of PCBs transported from the shelf seas and from dissolution and/or mineralization of settling particles. Combined with measurement data on PCBs in other Arctic Ocean compartments collected over the past decade, the total Arctic Ocean inventory of ∑7PCB was estimated to 182 ± 40 t (±1 standard error of the mean), with sediments (144 ± 40 t), intermediate (5 ± 1 t) and deep water masses (30 ± 2 t) storing 98% of the PCBs in the Arctic Ocean. Further, we used hydrographic and carbon cycle parametrizations to assess the main pathways of PCBs into and out of the Arctic Ocean during the 20th century. River discharge appeared to be the major pathway for PCBs into the Arctic Ocean with 115 ± 11 t, followed by ocean currents (52 ± 17 t) and net atmospheric deposition (30 ± 28 t). Ocean currents provided the only important pathway out of the Arctic Ocean, with an estimated cumulative flux of 22 ± 10 t. The observation-based inventory of ∑7PCB of 182 ± 40 t is consistent with the contemporary inventory based on cumulative fluxes for ∑7PCB of 173 ± 36 t. Information on the concentration and distribution of PCBs in the deeper compartments of the Arctic Ocean improves our understanding of the large-scale fate of POPs in the Arctic and may also provide a means to test and improve models used to assess the fate of organic pollutants in the Arctic.

  12. Ocean sequestration of crop residue carbon: recycling fossil fuel carbon back to deep sediments.

    Science.gov (United States)

    Strand, Stuart E; Benford, Gregory

    2009-02-15

    For significant impact any method to remove CO2 from the atmosphere must process large amounts of carbon efficiently, be repeatable, sequester carbon for thousands of years, be practical, economical and be implemented soon. The only method that meets these criteria is removal of crop residues and burial in the deep ocean. We show here that this method is 92% efficient in sequestration of crop residue carbon while cellulosic ethanol production is only 32% and soil sequestration is about 14% efficient. Deep ocean sequestration can potentially capture 15% of the current global CO2 annual increase, returning that carbon backto deep sediments, confining the carbon for millennia, while using existing capital infrastructure and technology. Because of these clear advantages, we recommend enhanced research into permanent sequestration of crop residues in the deep ocean.

  13. Ferromanganese oxide deposits from the Central Pacific Ocean, II. Nodules and associated sediments

    Science.gov (United States)

    Aplin, Andrew C.; Cronan, David S.

    1985-02-01

    Bulk chemical, mineralogical and selective leach analyses have been made on a suite of abyssal ferromanganese nodules and associated sediments from the S.W. equatorial Pacific Ocean. Compositional relations between nodules, sediment oxyhydroxides and nearby ferromanganese encrustations are drawn assuming that the crusts represent purely hydrogenetic ferromanganese material. Crusts, δMnO 2-rich nodules and sediment oxyhydroxides are compositionally similar and distinct from diagenetic todorokitebearing nodules. Compared to Fe-Mn crusts, sediment oxyhydroxides are however slightly enriched, relative to Mn and Ni, in Fe, Cu, Zn, Ti and Al, and depleted in Co and Pb, reflecting processes of non-hydrogenous element supply and diagenesis. δMnO 2 nodules exhibit compositions intermediate between Fe-Mn crusts and sediment oxyhydroxides and thus are considered to accrete oxides from both the water column and associated sediments. Deep ocean vertical element fluxes associated with large organic aggregates, biogenic calcite, silica and soft parts have been calculated for the study area. Fluxes associated with organic aggregates are one to three orders of magnitude greater than those associated with the other phases considered, are in good agreement with element accumulation rates in sediments, and are up to four orders of magnitude greater than element accumulation rates in nodules. Metal release from labile biogenic material in surface sediments can qualitatively explain the differences between the composition of Fe-Mn crusts and sediment oxyhydroxides. Todorokite-rich diagenetic nodules are confined to an eastwards widening equatorial wedge. It is proposed that todorokite precipitates directly from interstitial waters. Since the transition metal chemistry of interstitial waters is controlled dominantly by reactions involving the breakdown of organic carbon, the supply and degradation rate of organic material is a critical factor in the formation of diagenetic nodules. The

  14. Residual β activity of particulate (234)Th as a novel proxy for tracking sediment resuspension in the ocean.

    Science.gov (United States)

    Lin, Wuhui; Chen, Liqi; Zeng, Shi; Li, Tao; Wang, Yinghui; Yu, Kefu

    2016-06-02

    Sediment resuspension occurs in the global ocean, which greatly affects material exchange between the sediment and the overlying seawater. The behaviours of carbon, nutrients, heavy metals, and other pollutants at the sediment-seawater boundary will further link to climate change, eutrophication, and marine pollution. Residual β activity of particulate (234)Th (RAP234) is used as a novel proxy to track sediment resuspension in different marine environments, including the western Arctic Ocean, the South China Sea, and the Southern Ocean. Sediment resuspension identified by high activity of RAP234 is supported by different lines of evidence including seawater turbidity, residence time of total (234)Th, Goldschmidt's classification, and ratio of RAP234 to particulate organic carbon. A conceptual model is proposed to elucidate the mechanism for RAP234 with dominant contributions from (234)Th-(238)U and (212)Bi-(228)Th. The 'slope assumption' for RAP234 indicated increasing intensity of sediment resuspension from spring to autumn under the influence of the East Asian monsoon system. RAP234 can shed new light on (234)Th-based particle dynamics and should benefit the interpretation of historical (234)Th-(238)U database. RAP234 resembles lithophile elements and has broad implications for investigating particle dynamics in the estuary-shelf-slope-ocean continuum and linkage of the atmosphere-ocean-sediment system.

  15. Residual β activity of particulate 234Th as a novel proxy for tracking sediment resuspension in the ocean

    Science.gov (United States)

    Lin, Wuhui; Chen, Liqi; Zeng, Shi; Li, Tao; Wang, Yinghui; Yu, Kefu

    2016-06-01

    Sediment resuspension occurs in the global ocean, which greatly affects material exchange between the sediment and the overlying seawater. The behaviours of carbon, nutrients, heavy metals, and other pollutants at the sediment-seawater boundary will further link to climate change, eutrophication, and marine pollution. Residual β activity of particulate 234Th (RAP234) is used as a novel proxy to track sediment resuspension in different marine environments, including the western Arctic Ocean, the South China Sea, and the Southern Ocean. Sediment resuspension identified by high activity of RAP234 is supported by different lines of evidence including seawater turbidity, residence time of total 234Th, Goldschmidt’s classification, and ratio of RAP234 to particulate organic carbon. A conceptual model is proposed to elucidate the mechanism for RAP234 with dominant contributions from 234Th-238U and 212Bi-228Th. The ‘slope assumption’ for RAP234 indicated increasing intensity of sediment resuspension from spring to autumn under the influence of the East Asian monsoon system. RAP234 can shed new light on 234Th-based particle dynamics and should benefit the interpretation of historical 234Th-238U database. RAP234 resembles lithophile elements and has broad implications for investigating particle dynamics in the estuary-shelf-slope-ocean continuum and linkage of the atmosphere-ocean-sediment system.

  16. Residual β activity of particulate 234Th as a novel proxy for tracking sediment resuspension in the ocean

    Science.gov (United States)

    Lin, Wuhui; Chen, Liqi; Zeng, Shi; Li, Tao; Wang, Yinghui; Yu, Kefu

    2016-01-01

    Sediment resuspension occurs in the global ocean, which greatly affects material exchange between the sediment and the overlying seawater. The behaviours of carbon, nutrients, heavy metals, and other pollutants at the sediment-seawater boundary will further link to climate change, eutrophication, and marine pollution. Residual β activity of particulate 234Th (RAP234) is used as a novel proxy to track sediment resuspension in different marine environments, including the western Arctic Ocean, the South China Sea, and the Southern Ocean. Sediment resuspension identified by high activity of RAP234 is supported by different lines of evidence including seawater turbidity, residence time of total 234Th, Goldschmidt’s classification, and ratio of RAP234 to particulate organic carbon. A conceptual model is proposed to elucidate the mechanism for RAP234 with dominant contributions from 234Th-238U and 212Bi-228Th. The ‘slope assumption’ for RAP234 indicated increasing intensity of sediment resuspension from spring to autumn under the influence of the East Asian monsoon system. RAP234 can shed new light on 234Th-based particle dynamics and should benefit the interpretation of historical 234Th-238U database. RAP234 resembles lithophile elements and has broad implications for investigating particle dynamics in the estuary-shelf-slope-ocean continuum and linkage of the atmosphere-ocean-sediment system. PMID:27252085

  17. Coupling of ocean bottom seismometers to sediment: results of tests with the U.S. Geological Survey ocean bottom seismometer

    Science.gov (United States)

    Trehu, Anne M.

    1985-01-01

    The response of an ocean bottom seismometer (OBS) to a transient pull that excites the natural OBS-sediment coupling resonance can be modeled as a mass-spring-dashpot system in which the resonant frequency and damping are functions of instrument mass and bearing radius and of the physical properties of the sediment (primarily the shear modulus). For the very soft sediments sometimes found on the sea floor, this resonance may be within the main frequency band of interest (2 to 15 Hz) for many common instrument configurations. To test the model and to find an anchor that would shift the coupling resonance to a higher frequency and decrease its amplitude, we conducted a series of tests which measured the response of the vertical and horizontal components of the U.S. Geological Survey OBS to transient pulls as a function of anchor configuration and sediment properties. The tested anchors included a concrete “flowerpot,” a tripod, a plate, and a perforated plate. Sites were on soft, organic-rich ooze and on firm sand. Several small shots were also fired at the ooze site in order to compare the response of the plate and “flowerpot” anchors to seismic signals. For a given anchor at a given site, the observed response was very repeatable. We found that the model predicts the vertical coupling response quite well and that good vertical coupling can be achieved with the plate or perforated-plate anchors. The response to the horizontal pulls, however, was similar and resonant for all anchors.

  18. Sources and cycling of mercury in the paleo Arctic Ocean from Hg stable isotope variations in Eocene and Quaternary sediments

    Science.gov (United States)

    Gleason, J. D.; Blum, J. D.; Moore, T. C.; Polyak, L.; Jakobsson, M.; Meyers, P. A.; Biswas, A.

    2017-01-01

    Mercury stable isotopic compositions were determined for marine sediments from eight locations in the Arctic Ocean Basin. Mass dependent fractionation (MDF) and mass independent fractionation (MIF) of Hg stable isotopes were recorded across a variety of depositional environments, water depths, and stratigraphic ages. δ202Hg (MDF) ranges from -2.34‰ to -0.78‰; Δ199Hg (MIF) from -0.18‰ to +0.12‰; and Δ201Hg (MIF) from -0.29‰ to +0.05‰ for the complete data set (n = 33). Holocene sediments from the Chukchi Sea and Morris Jesup Rise record the most negative Δ199Hg values, while Pleistocene sediments from the Central Arctic Ocean record the most positive Δ199Hg values. The most negative δ202Hg values are recorded in Pleistocene sediments. Eocene sediments (Lomonosov Ridge) show some overlap in their Hg isotopic compositions with Quaternary sediments, with a sample of the Arctic Ocean PETM (56 Ma) most closely matching the average Hg isotopic composition of Holocene Arctic marine sediments. Collectively, these data support a terrestrially-dominated Hg source input for Arctic Ocean sediment through time, although other sources, as well as influences of sea ice, atmospheric mercury depletion events (AMDEs), and anthropogenic Hg (in core top samples) on Hg isotopic signatures must also be considered.

  19. Respiration in ocean margin sediments - Sedimentrespiratie in de overgang van het continentale plat naar de diepe oceaan

    NARCIS (Netherlands)

    Andersson, J.H.

    2007-01-01

    The aim of this thesis was the study of respiration in ocean marginsediments and the assessments of tools needed for this purpose. The first study was on the biological pump and global respirationpatterns in the deep ocean using an empirical model basedon sediment oxygen consumption data. In this

  20. 2012 U.S. Geological Survey Topographic Lidar: Northeast Atlantic Coast Post-Hurricane Sandy

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Binary point-cloud data were produced for a portion of the New York, Delaware, Maryland, Virginia, and North Carolina coastlines, post-Hurricane Sandy (Sandy was an...

  1. 2012 U.S. Geological Survey Topographic Lidar: Northeast Atlantic Coast Post-Hurricane Sandy

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Binary point-cloud data were produced for a portion of the New York, Delaware, Maryland, Virginia, and North Carolina coastlines, post-Hurricane Sandy (Sandy was an...

  2. The "rain of particles" into the deep sea: perspectives of a biological detective who sifts through oceanic sediment traps

    Science.gov (United States)

    Silver, M. W.

    2007-05-01

    The sedimentation of particles from the ocean's sunlit zone to underlying waters is not only key to sustenance of life at depth but also to the sequestration of carbon and surface-derived materials in underlying waters and sediments. Decades of research on particle flux have provided considerable quantitative information about the chemical constituents of sinking materials and their vertical and horizontal variability in the oceans. The biological processes initiating the rain have also received considerable attention, and models demonstrate the importance of particular characteristics of the photosynthetic organisms that initiate the process, as well as the features of the food webs that may control delivery rates. In this presentation, I revisit discoveries dating from sediment trap studies of the early '80s to those of the recent VERTEX project to decipher what the contents of sediment traps, particularly the various photosynthetic and other unicellular organisms, can tell us about biological processes affecting the rain of particles into the deep ocean.

  3. Hurricane Sandy and earthquakes

    OpenAIRE

    MAVASHEV BORIS; MAVASHEV IGOR

    2013-01-01

    Submit for consideration the connection between formation of a hurricane Sandy and earthquakes. As a rule, weather anomalies precede and accompany earthquakes. The hurricane Sandy emerged 2 days prior to strong earthquakes that occurred in the area. And the trajectory of the hurricane Sandy matched the epicenter of the earthquakes. Possibility of early prediction of natural disasters will minimize the moral and material damage.

  4. Impact of Human Activities on the Flux of Terrestrial Sediments to the Coastal Ocean Offshore Northeastern Taiwan

    Science.gov (United States)

    Chen, Tzu-Ting; Su, Chih-Chieh; Liu, Char-Shine; Huang, Chen-fen; Hsu, Ho-Han

    2016-04-01

    Land to ocean material fluxes play an important role in global biogeochemical cycles. Changes in sediment supply not only greatly influence the benthic environment of coastal estuaries but also might threaten human lives and properties. Artificial constructions, such as roads and reservoirs, could affect natural environments and change sediment discharges. Due to its high precipitation, steep slopes, small basin areas, and frequent flood events, Taiwan is characterized with rapid erosion rates and extremely high sediment yields. In northeastern Taiwan, the high mean annual precipitation lead to large amounts of sediments being delivered into the ocean through the Lanyang River. Since 1957, the road constructions along the Lanyang River greatly increased terrestrial sediment flux to the coastal ocean. However, its influence on offshore area is not yet clear. In this study, we combine geochemical and geophysical data to evaluate the modern sedimentation history and discuss the impact of human activities on the Ilan Shelf. The preliminary results of grain size and 210Pb analyses from five sediment cores taken from the upper South Guishan Channel indicate the existence of local differences on hydrodynamic conditions. In addition, we also applied similarity index which based on a quantitative analysis algorithm to the chirp sonar data on echo character classification and calculated continuous grain size variations of the seafloor surface sediments. By combining all geochemical and geophysical data, we may reconstruct the holistic picture of human impacts on offshore environment from sedimentology records.

  5. Island-Arc Collision Dominates Japan's Sediment Flux to the Pacific Ocean

    Science.gov (United States)

    Codilean, A. T.; Korup, O.; Hayakawa, Y. S.; Matsushi, Y.; Saito, H.; Matsuzaki, H.

    2013-12-01

    collisional mountain-building of the Japanese Alps causes the highest erosion rates anywhere on the island arc despite similar uplift and precipitation controls in southwest Japan. We infer that, prior to extensive river damming and reservoir construction, the gross of Japan's total sediment export to the Pacific Ocean entered the accretionary margin of the Nankai Trough as opposed to the comparatively sediment-starved Japan Trench. Although this pattern mimics the long-term mass balance of incoming sediment to these subduction zones, future work will be needed to constrain the relative contribution of terrestrial sediment input on 103-yr timescales.

  6. Stratigraphy and Glacial-Marine Sediments of the Amerasian Basin, Central Arctic Ocean.

    Science.gov (United States)

    1981-02-01

    particles and conducting an electronic si/C analisis of the material that passed through the sieve A, using a I A 11 Coulter counter. I he (oulter...Ocean mechanists. Normal pelagic and glacially dericd fine matelital are glacial-marine sediment should he viewed as a complex process distributed...meatn prain si/(i \\;ei iiade heisseri iis ri r it( f xindil atrca fac sedimencrt I\\. PCs at h Ii 05 0-1irf~ifr I. live) 11it11%~ iisr I tii basic

  7. Rain ratio variation in the Tropical Ocean: Tests with surface sediments in the eastern equatorial Pacific

    Science.gov (United States)

    Mekik, Figen; Loubere, Paul; Richaud, Mathieu

    2007-03-01

    The organic carbon to calcite flux ratio (rain ratio) has a profound effect on the preservation of carbonates in the deep sea and may influence atmospheric pCO 2 over millennia. Unfortunately, the degree to which the rain ratio varies in the more productive regions of the oceans is not well determined with sediment trap data. The rain ratio in the upper ocean appears dominantly linked to diatom productivity, which is not necessarily directly linked to total production and may be regionally variable. However, ballasting and protection of organic carbon by calcareous particles in the deeps may limit ratio variability at the seafloor. Sediment trap data do not exist for the regional determination of rain ratios in key highly productive areas like the eastern equatorial Pacific (EEP). To overcome this, we turn to surface sediment composition and accumulation rates as a representation of modern ratio variation. We present 230Thorium ( 230Th)-normalized carbonate, opal, organic carbon and detrital matter accumulation rates from core top samples in the EEP. We demonstrate a novel approach for estimating modern rain ratios from sedimentary proxies by (1) calculating vertical calcite flux from 230Th-normalized carbonate accumulation rates (CARs) with correction for preservation and (2) calculating organic carbon fluxes with multiple algorithms that depend in varying degrees on ballasting. We find that organic carbon flux estimates from algorithms with and without a ballasting function produce results different from one another. Sediment accumulation rates for opal reflect the likely pattern of diatom production. By contrast, the organic carbon accumulation rate does not correlate well with surface ocean productivity or any of our algorithm-based organic carbon flux estimates. Instead, it correlates with the detrital component of the sediments suggesting an allochthonous input to sedimentary organic carbon accumulation in the EEP, which reduces its value as a productivity

  8. Black carbon in deep-sea sediments from the northeastern equatorial Pacific Ocean

    Science.gov (United States)

    Kim, D.; Lee, Y.; Hyeong, K.; Yoo, C.

    2011-12-01

    Deep-sea sediment core is a good archive for understanding the land-ocean interactions via atmosphere, due to it is little influenced by fluvial and continental shelf processes. This study dealt with black carbon(BC) in a 328 cm-long piston core collected from the northeastern equatorial Pacific Ocean (16°12'N, 125°59'W), covering the last 15 Ma (Hyeong at al., 2004). BC is a common name of carbon continuum formed by incomplete combustion of fossil fuels and plant materials. Though it may react with ozone and produce water-soluble organic carbon, BC has commonly refractory nature. Thus BC in preindustrial sediment can be a tracer of forest-fire events. BC is purely terrestrial in origin, and is transported to marine environments by atmospheric and fluvial processes. Therefore, distribution of BC in deep-sea sediments could be used to understand atmospheric circulation. Chemical oxidation was used to determine BC in this study following Lim and Cachier (1996). Concentration of BC varies from 0.010% to 0.233% of total sediments. Mass accumulation rate (MAR) of BC ranged between 0.077 mg/cm^2/1000 yrs and 47.49 mg/cm^21000 yrs. It is noted that MAR in sediments younger than 8 Ma (av. 9.0 mg/cm^2/1000 yrs) is higher than that in sediments older than 8 Ma (av. 3.2 mg/cm^2/1000 yrs). Stable carbon isotope value of BC increases with time from the low δ13C value near 13 Ma until it reaches the highest value near 4 Ma. Change of MAR seems to be related to the meridional migration of Intertropical Convergence Zone (ITCZ) at around 8 Ma in the study area (cf., Hyeong at al., 2004). Accordingly, higher BC content in sediment younger than 8 Ma seems to be accounted for by its derivation from the Northern Hemisphere compared to that from the Southern Hemisphere in older sediment. Increase of carbon isotope value with time seems to be related to expansion of C4 grassland. C4 grassland expansion might have been caused by change of atmosphreic cycle, which moved dry subtropical

  9. Oxygen isotope compositions of sinistral Neogloboquadrina pachyderma tests in surface sediments: North Atlantic Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Wu, G.; Hillaire-Marcel, C. (Universite de Quebec a Montreal (Canada))

    1994-02-01

    Neogloboquadrina pachyderma (Left-coiled) is a planktonic foraminifer indicator species for polar waters. It is present in both the glacial and interglacial sediments of the high-latitude oceans, and therefore is frequently used as a signal-carrier for constructing late Pleistocene-Holocene planktonic [delta][sup 18]O records. In this study the [delta][sup 18]O compositions of N. pachyderma (L) tests from deep-sea surface sediments are compared with surface water [delta][sup 18]O values and summer sea surface temperatures (SST) in the North Atlantic Ocean, the Norwegian-Greenland Sea, and the Labrador Sea. The authors document that for a temperature range of 2-8[degrees]C, the planktonic [delta][sup 18]O values follow paleotemperature equations with an offset of less than 0.4%, and that above 8[degrees]C the planktonic [delta][sup 18]O compositions become almost independent of SST and remain nearly constant. This pattern suggests that N. pachyderma (L) precipitates its shell nearly at isotopic equilibrium with surface waters colder than 8[degrees]C, and that in warmer surface waters N. pachyderma (L) changes its habitat depth or its growth season to secrete its shell at an ambient temperature around 7-9[degrees]C.

  10. Spatially Resolving Ocean Color and Sediment Dispersion in River Plumes, Coastal Systems, and Continental Shelf Waters

    Science.gov (United States)

    Aurin, Dirk Alexander; Mannino, Antonio; Franz, Bryan

    2013-01-01

    Satellite remote sensing of ocean color in dynamic coastal, inland, and nearshorewaters is impeded by high variability in optical constituents, demands specialized atmospheric correction, and is limited by instrument sensitivity. To accurately detect dispersion of bio-optical properties, remote sensors require ample signal-to-noise ratio (SNR) to sense small variations in ocean color without saturating over bright pixels, an atmospheric correction that can accommodate significantwater-leaving radiance in the near infrared (NIR), and spatial and temporal resolution that coincides with the scales of variability in the environment. Several current and historic space-borne sensors have met these requirements with success in the open ocean, but are not optimized for highly red-reflective and heterogeneous waters such as those found near river outflows or in the presence of sediment resuspension. Here we apply analytical approaches for determining optimal spatial resolution, dominant spatial scales of variability ("patches"), and proportions of patch variability that can be resolved from four river plumes around the world between 2008 and 2011. An offshore region in the Sargasso Sea is analyzed for comparison. A method is presented for processing Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua and Terra imagery including cloud detection, stray lightmasking, faulty detector avoidance, and dynamic aerosol correction using short-wave- and near-infrared wavebands in extremely turbid regions which pose distinct optical and technical challenges. Results showthat a pixel size of approx. 520 mor smaller is generally required to resolve spatial heterogeneity in ocean color and total suspended materials in river plumes. Optimal pixel size increases with distance from shore to approx. 630 m in nearshore regions, approx 750 m on the continental shelf, and approx. 1350 m in the open ocean. Greater than 90% of the optical variability within plume regions is resolvable with

  11. Short Communication Energy and ash contents of sandy beach ...

    African Journals Online (AJOL)

    macrofauna found on three exposed sandy beaches on the west coast ... that they often form the predominant shore type (Bally,. McQuaid ... their sediments are given in Table I. Animals ..... The biochemical composition of the tropical intertida1 ...

  12. Interstitial meiofauna of Namib sandy beaches

    African Journals Online (AJOL)

    1988-03-16

    Mar 16, 1988 ... sandy beaches on the Namibian coast, Langstrand and Cape Cross. A transverse ... prominent in the mid-shore at Cape Cross but occurred in low numbers at Langstrand , where archiannelids ... Koop (1983) recorded the faunal composition of local .... four replicate sediment cores were taken at 15 cm.

  13. Exploring the role of shelf sediments in the Arctic Ocean in determining the Arctic contamination potential of neutral organic contaminants.

    Science.gov (United States)

    Armitage, James M; Choi, Sung-Deuk; Meyer, Torsten; Brown, Trevor N; Wania, Frank

    2013-01-15

    The main objective of this study was to model the contribution of shelf sediments in the Arctic Ocean to the total mass of neutral organic contaminants accumulated in the Arctic environment using a standardized emission scenario for sets of hypothetical chemicals and realistic emission estimates (1930-2100) for polychlorinated biphenyl congener 153 (PCB-153). Shelf sediments in the Arctic Ocean are shown to be important reservoirs for neutral organic chemicals across a wide range of partitioning properties, increasing the total mass in the surface compartments of the Arctic environment by up to 3.5-fold compared to simulations excluding this compartment. The relative change in total mass for hydrophobic organic chemicals with log air-water partition coefficients ≥0 was greater than for chemicals with properties similar to typical POPs. The long-term simulation of PCB-153 generated modeled concentrations in shelf sediments in reasonable agreement with available monitoring data and illustrate that the relative importance of shelf sediments in the Arctic Ocean for influencing surface ocean concentrations (and therefore exposure via the pelagic food web) is most pronounced once primary emissions are exhausted and secondary sources dominate. Additional monitoring and modeling work to better characterize the role of shelf sediments for contaminant fate is recommended.

  14. Three-dimensional distribution of plastic pellets in sandy beaches: shifting paradigms

    Science.gov (United States)

    Turra, Alexander; Manzano, Aruanã B.; Dias, Rodolfo Jasão S.; Mahiques, Michel M.; Barbosa, Lucas; Balthazar-Silva, Danilo; Moreira, Fabiana T.

    2014-03-01

    Plastic pellets are worldwide contaminants that accumulate in the ocean, especially in sandy beaches, where their historic standing-stock quantification relies on surface sediment samples. We demonstrated these particles present a three-dimensional instead of a simple along-across shore distribution, being found as deep as 2.0 m, with surface layers accounting for microplastics and sedimentary environments as a whole should be investigated. This poses criticism in the exactness of standing-stock records and demands urgent discussion of sampling protocols.

  15. The Light-Field of Microbenthic Communities - Radiance Distribution and Microscale Optics of Sandy Coastal Sediments Rid A-1977-2009

    DEFF Research Database (Denmark)

    KUHL, M.; JØRGENSEN, BB

    1994-01-01

    The light field in coastal sediments was investigated at a spatial resolution of 0.2-0.5 mm by spectral measurements (450-850 nm) of field radiance and scalar irradiance using fiber-optic microprobes. Depth profiles of field radiance were measured with radiance microprobes at representative angles...... with the scalar irradiance measured directly by a fiber-optic scalar irradiance microprobe. Close to the sediment surface, the light field was highly anisotropic, dominated by incident collimated light, and the scalar irradiance reached a maximum of 200% of incident scalar irradiance. Below the sediment surface...

  16. 2014 USGS CMGP Lidar: Post Sandy (Long Island, NY)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — TASK NAME: Long Island New York Sandy LIDAR lidar Data Acquisition and Processing Production Task USGS Contract No. G10PC00057 Task Order No. G14PD00296 Woolpert...

  17. Hurricane Sandy: Rapid Response Imagery of the Surrounding Regions

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The imagery posted on this site is of Hurricane Sandy. The aerial photography missions were conducted by the NOAA Remote Sensing Division. The images were acquired...

  18. 2008 USDA Forest Service Lidar: Sandy River Study Area

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Watershed Sciences, Inc. collected Light Detection and Ranging (LiDAR) data for the Sandy River study area in collaboration with the USDA Forest Service. The areas...

  19. 2014 USGS CMGP Lidar: Sandy Restoration (Delaware and Maryland)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Geographic Extent: SANDY_Restoration_DE_MD_QL2 Area of Interest covers approximately 3.096 square miles. Lot #5 contains the full project area Dataset Description:...

  20. Nitrogen isotopic composition of planktonic foraminifera from the modern ocean and recent sediments

    Science.gov (United States)

    Ren, H.; Thunell, R.; Sigman, D. M.; Prokopenko, M. G.

    2010-12-01

    The nitrogen isotopic composition of the organic matter trapped within calcium carbonate matrix of planktonic foraminifera shells (foraminifera-bound δ15N, or FB-δ15N) is being measured in ocean sediment records to reconstruct past changes in the marine nitrogen cycle. Because of the multiple species of foraminifera and their differences in depth and trophic preference, FB-δ15N stands to have unprecedented richness as a paleoceanographic tool, but information on its generation and preservation is so far minimal. In this study, we report measurements of the δ15N of foraminiferal biomass from Sargasso Sea net tow material and shell-bound N from Cariaco Basin sediment traps and from shallow sediments collected in different open ocean regions. Comparison of the Sargasso Sea plankton tow data with FB-δ15N measurements in surface sediments from the low latitude N. Atlantic suggest that the δ15N of shell-bound organic material is similar to its biomass, at least for the symbiotic species, for which there is the most data. Our global data set of FB-δ15N from surface sediments shows a strong correlation between FB-δ15N and changes in the subsurface nitrate δ15N, which is the dominant source of new N to the euphotic zone in the oligotrophic regions. The three euphotic zone dwelling, symbiotic, and spinose species, G. ruber, G. sacculifer, and O. universa are very similar to the annual mean δ15N of the subsurface nitrate, whereas the deeper dwelling, non-spinose and/or asymbiotic forms are coherently higher in δ15N. In the Cariaco Basin sediment trap samples, the FB-δ15N of O. universa varies substantially, in some cases in step with bulk sediment trap δ15N variations, while the sub-euphotic zone dwelling, asymbiotic, and/or non-spinose species are generally higher in FB-δ15N and more stable through the time series. Euphotic zone dwellers such as O. universa probably prey dominantly on zooplankton and eukaryotic phytoplankton in the mixed layer down to the deep

  1. Phylogenetic Characterization of Marine Benthic Archaea in Organic-Poor Sediments of the Eastern Equatorial Pacific Ocean (ODP Site 1225).

    Science.gov (United States)

    Lauer, Antje; Sørensen, Ketil Bernt; Teske, Andreas

    2016-09-06

    Sequencing surveys of microbial communities in marine subsurface sediments have focused on organic-rich, continental margins; the database for organic-lean deep-sea sediments from mid-ocean regions is underdeveloped. The archaeal community in subsurface sediments of ODP Site 1225 in the eastern equatorial Pacific (3760 m water depth; 1.1 and 7.8 m sediment depth) was analyzed by PCR, cloning and sequencing, and by denaturant gradient gel electrophoresis (DGGE) of 16S rRNA genes. Three uncultured archaeal lineages with different depth distributions were found: Marine Group I (MG-I) within the Thaumarchaeota, its sister lineage Marine Benthic Group A (MBG-A), the phylum-level archaeal lineage Marine Benthic Group B (also known as Deep-Sea Archaeal Group or Lokiarchaeota), and the Deep-Sea Euryarchaeotal Group 3. The MG-I phylotypes included representatives of sediment clusters that are distinct from the pelagic members of this phylum. On the scale from fully oxidized, extremely organic carbon-depleted sediments (for example, those the South Pacific Gyre) to fully reduced, organic carbon-rich marine subsurface sediments (such as those of the Peru Margin), Ocean Drilling Program (ODP) Site 1225 falls into the non-extreme organic carbon-lean category, and harbors archaeal communities from both ends of the spectrum.

  2. 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.

  3. EAARL-B Coastal Topography--Eastern New Jersey, Hurricane Sandy, 2012: First Surface, Pre-Sandy

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — ASCII xyz and binary point-cloud data, as well as a digital elevation model (DEM) of a portion of the New Jersey coastline, pre- and post-Hurricane Sandy (October...

  4. Gas production potential of disperse low-saturation hydrateaccumulations in oceanic sediments

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, George J.; Sloan, E. Dendy

    2006-07-19

    In this paper we evaluate the gas production potential ofdisperse, low-saturation (SH<0.1) hydrate accumulations in oceanicsediments. Such hydrate-bearing sediments constitute a significantportion of the global hydrate inventory. Using numerical simulation, weestimate (a) the rates of gas production and gas release from hydratedissociation, (b) the corresponding cumulative volumes of released andproduced gas, as well as (c) the water production rate and the mass ofproduced water from disperse, low-SH hydrate-bearing sediments subject todepressurization-induced dissociation over a 10-year production period.We investigate the sensitivity of items (a) to (c) to the followinghydraulic properties, reservoir conditions, and operational parameters:intrinsic permeability, porosity, pressure, temperature, hydratesaturation, and constant pressure at which the production well is kept.The results of this study indicate that, despite wide variations in theaforementioned parameters (covering the entire spectrum of suchdeposits), gas production is very limited, never exceeding a few thousandcubic meters of gas during the 10-year production period. Such lowproduction volumes are orders of magnitude below commonly acceptedstandards of economic viability, and are further burdened with veryunfavorable gas-to-water ratios. The unequivocal conclusion from thisstudy is that disperse, low-SH hydrate accumulations in oceanic sedimentsare not promising targets for gas production by means ofdepressurization-induced dissociation, and resources for early hydrateexploitation should be focused elsewhere.

  5. Processing of 13C-labelled phytoplankton in a fine-grained sandy-shelf sediment (North Sea): relative importance of different macrofauna species

    DEFF Research Database (Denmark)

    Kamp, Anja; Witte, Ursula

    2005-01-01

    by additional laboratory experiments on the role of the dominant macrofauna organism, the bivalve Fabulina fabula (Bivalvia: Tellinidae), for particulate organic matter subduction to deeper sediment layers. The specific uptake of algal 13C by macrofauna organisms was visible after 12 h and constantly increased...... carbon processing. Predatory macrofauna organisms like Nephtys spp. (Polychaeta: Nephtyidae) also quickly became labelled. The rapid subduction of fresh organic matter by F. fabula down to ca. 4 to 7 cm sediment depth could be demonstrated, and it is suggested that entrainment by macrofauna in this fine...

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

    Indian Academy of Sciences (India)

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

    2008-04-01

    Three sediment cores in a north–south transect (3°N to 13°S) from different sediment types of the Central Indian Ocean Basin (CIOB) are studied to understand the possible relationship between magnetic susceptibility () and Al, Fe, Ti and Mn concentrations. The calcareous ooze core exhibit lowest (12.32 × 10-7m3 kg−1), Al (2.84%), Fe (1.63%) and Ti (0.14%), terrigenous clay core with moderate (29.9 × 10-7 m3 kg−1) but highest Al (6.84%), Fe (5.20%) and Ti (0.44%), and siliceous ooze core with highest (38.06 × 10-7 m3 kg−1) but moderate Al (4.49%), Fe (2.80%) and Ti (0.19%) contents. The distribution of and detrital proxy elements (Al, Fe, and Ti) are identical in both calcareous and siliceous ooze. Interestingly, in terrigenous core, the behaviour of is identical to only Ti content but not with Al and Fe suggesting possibility of Al and Fe having a non-detrital source. The occurrence of phillipsite in terrigenous clay is evident by the Al-K scatter plot where trend line intersects K axis at more than 50% of total K suggesting excess K in the form of phillipsite. Therefore, the presence of phillipsite might be responsible for negative correlation between and Al ( = −0.52). In siliceous ooze the strong positive correlations among , Alexc and Feexc suggest the presence of authigenic Fe-rich smectite. High Mn content (0.5%) probably in the form of manganese micronodules is also contributing to in both calcareous and siliceous ooze but not in the terrigenous core where mean Mn content (0.1%) is similar to crustal abundance. Thus, systematically records the terrigenous variation in both the biogenic sediments but in terrigenous clay it indirectly suggests the presence of authigenic minerals.

  7. LOSCAR: Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir Model v2.0.4

    Directory of Open Access Journals (Sweden)

    R. E. Zeebe

    2012-01-01

    Full Text Available The LOSCAR model is designed to efficiently compute the partitioning of carbon between ocean, atmosphere, and sediments on time scales ranging from centuries to millions of years. While a variety of computationally inexpensive carbon cycle models are already available, many are missing a critical sediment component, which is indispensable for long-term integrations. One of LOSCAR's strengths is the coupling of ocean-atmosphere routines to a computationally efficient sediment module. This allows, for instance, adequate computation of CaCO3 dissolution, calcite compensation, and long-term carbon cycle fluxes, including weathering of carbonate and silicate rocks. The ocean component includes various biogeochemical tracers such as total carbon, alkalinity, phosphate, oxygen, and stable carbon isotopes. LOSCAR's configuration of ocean geometry is flexible and allows for easy switching between modern and paleo-versions. We have previously published applications of the model tackling future projections of ocean chemistry and weathering, pCO2 sensitivity to carbon cycle perturbations throughout the Cenozoic, and carbon/calcium cycling during the Paleocene-Eocene Thermal Maximum. The focus of the present contribution is the detailed description of the model including numerical architecture, processes and parameterizations, tuning, and examples of input and output. Typical CPU integration times of LOSCAR are of order seconds for several thousand model years on current standard desktop machines. The LOSCAR source code in C can be obtained from the author by sending a request to loscar.model@gmail.com.

  8. Distribution and sources of polycyclic aromatic hydrocarbons in surface sediments from the Bering Sea and western Arctic Ocean.

    Science.gov (United States)

    Zhao, Mengwei; Wang, Weiguo; Liu, Yanguang; Dong, Linsen; Jiao, Liping; Hu, Limin; Fan, Dejiang

    2016-03-15

    To analyze the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) and evaluate their potential ecological risks, the concentrations of 16 PAHs were measured in 43 surface sediment samples from the Bering Sea and western Arctic Ocean. Total PAH (tPAH) concentrations ranged from 36.95 to 150.21 ng/g (dry weight). In descending order, the surface sediment tPAH concentrations were as follows: Canada Basin>northern Chukchi Sea>Chukchi Basin>southern Chukchi Sea>Aleutian Basin>Makarov Basin>Bering Sea shelf. The Bering Sea and western Arctic Ocean mainly received PAHs of pyrogenic origin due to pollution caused by the incomplete combustion of fossil fuels. The concentrations of PAHs in the sediments of the study areas did not exceed effects range low (ERL) values.

  9. Correlation of the oldest Toba Tuff to sediments in the central Indian Ocean Basin

    Indian Academy of Sciences (India)

    J N Pattan; M Shyam Prasad; E V S S K Babu

    2010-08-01

    We have identified an ash layer in association with Australasian microtektites of ∼0.77Ma old in two sediment cores which are ∼450 km apart in the central Indian Ocean Basin (CIOB). Morphology and chemical composition of glass shards and associated microtektites have been used to trace their provenance. In ODP site 758 from Ninetyeast Ridge, ash layer-D (13 cm thick, 0.73–0.75 Ma) and layer-E (5 cm thick, 0.77–0.78 Ma) were previously correlated to the oldest Toba Tuff (OTT) eruptions of the Toba caldera, Sumatra. In this investigation, we found tephra ∼3100 km to the southwest of Toba caldera that is chemically identical to layer D of ODP site 758 and ash in the South China Sea correlated to the OTT. Layer E is not present in the CIOB or other ocean basins. The occurrence of tephra correlating to layer D suggests a widespread distribution of OTT tephra (∼3.6 × 107 km2), an ash volume of at least ∼1800 km3, a total OTT volume of 2300 km3, and classification of the OTT eruption as a super-eruption.

  10. Mechanisms Leading to Co-Existence of Gas Hydrate in Ocean Sediments [Part 2 of 2

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, Steven; Juanes, Ruben

    2011-12-31

    In this project we have sought to explain the co-existence of gas and hydrate phases in sediments within the gas hydrate stability zone. We have focused on the gas/brine interface at the scale of individual grains in the sediment. The capillary forces associated with a gas/brine interface play a dominant role in many processes that occur in the pores of sediments and sedimentary rocks. The mechanical forces associated with the same interface can lead to fracture initiation and propagation in hydrate-bearing sediments. Thus the unifying theme of the research reported here is that pore scale phenomena are key to understanding large scale phenomena in hydrate-bearing sediments whenever a free gas phase is present. Our analysis of pore-scale phenomena in this project has delineated three regimes that govern processes in which the gas phase pressure is increasing: fracturing, capillary fingering and viscous fingering. These regimes are characterized by different morphology of the region invaded by the gas. On the other hand when the gas phase pressure is decreasing, the corresponding regimes are capillary fingering and compaction. In this project, we studied all these regimes except compaction. Many processes of interest in hydrate-bearing sediments can be better understood when placed in the context of the appropriate regime. For example, hydrate formation in sub-permafrost sediments falls in the capillary fingering regime, whereas gas invasion into ocean sediments is likely to fall into the fracturing regime. Our research provides insight into the mechanisms by which gas reservoirs are converted to hydrate as the base of the gas hydrate stability zone descends through the reservoir. If the reservoir was no longer being charged, then variation in grain size distribution within the reservoir explain hydrate saturation profiles such as that at Mt. Elbert, where sand-rich intervals containing little hydrate are interspersed between intervals containing large hydrate

  11. Mechanisms Leading to Co-Existence of Gas Hydrate in Ocean Sediments [Part 1 of 2

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, Steven; Juanes, Ruben

    2011-12-31

    In this project we have sought to explain the co-existence of gas and hydrate phases in sediments within the gas hydrate stability zone. We have focused on the gas/brine interface at the scale of individual grains in the sediment. The capillary forces associated with a gas/brine interface play a dominant role in many processes that occur in the pores of sediments and sedimentary rocks. The mechanical forces associated with the same interface can lead to fracture initiation and propagation in hydrate-bearing sediments. Thus the unifying theme of the research reported here is that pore scale phenomena are key to understanding large scale phenomena in hydrate-bearing sediments whenever a free gas phase is present. Our analysis of pore-scale phenomena in this project has delineated three regimes that govern processes in which the gas phase pressure is increasing: fracturing, capillary fingering and viscous fingering. These regimes are characterized by different morphology of the region invaded by the gas. On the other hand when the gas phase pressure is decreasing, the corresponding regimes are capillary fingering and compaction. In this project, we studied all these regimes except compaction. Many processes of interest in hydrate-bearing sediments can be better understood when placed in the context of the appropriate regime. For example, hydrate formation in sub-permafrost sediments falls in the capillary fingering regime, whereas gas invasion into ocean sediments is likely to fall into the fracturing regime. Our research provides insight into the mechanisms by which gas reservoirs are converted to hydrate as the base of the gas hydrate stability zone descends through the reservoir. If the reservoir was no longer being charged, then variation in grain size distribution within the reservoir explain hydrate saturation profiles such as that at Mt. Elbert, where sand-rich intervals containing little hydrate are interspersed between intervals containing large hydrate

  12. Hydrofracturing of Sediment and Hydrated MORB's during Subduction of Ocean Crust

    Science.gov (United States)

    Nabelek, P. I.

    2015-12-01

    Dehydration accompanying metamorphism of sediment and hydrated mafic ocean crust during ocean plate subduction can potentially lead to fracturing and intraplate tremors. As rocks are buried, they lose porosity and permeability and eventually pass into the lithostatic pressure regime where the porosity and permeability are thought to be very small. Pore fluid pressure generation stemming from metamorphic reactions was modeled using the program SUTRAMET (Nabelek et al., 2014), which is a modified version of the program SUTRA (Voss & Provost, 2002). The program allows modeling of metamorphic reactions at high pressures and temperatures and incorporates transient porosity and permeability changes due to overpressure and changing volumes of metamorphic assemblages. Permeabilities (k) of 10-18 and 10-20 m2 within the brittle regime were modeled. The model assumes continuous subduction with fluids generated at horizons where specific P-T conditions for reactions exist. Temperature gradient was assumed to be 10°C/km and the vertical component of subduction velocity to be at 0.85 cm/y. The model reactions in sediment (Campito Formation of western California as a proxy) and average MORB were generated by the program Theriak-Domino (de Capitani and Petrakakis, 2010). The initial sediment mineralogy includes albite, K-feldspar, phengite, chlorite, and lawsonite. The final mineralogy for the 10°C/km gradient is quartz, phengite, garnet, and pyroxene with jadeite and acmite components. The initial mineralogy of MORB includes chlorite, amphibole, pumpelyite, albite and quartz and the final eclogite mineralogy includes garnet, cpx, kyanite and quartz. Calculations show that at k = 10-18 m2, pore fluid pressure can reach 450 MPa. Pore pressure is reduced by negative ∆V of mineral assemblages stemming from reactions; nevertheless, for the garnet-forming reaction, pore pressure is about 110 MPa. Assuming a tensile strength of 15 MPa and fracture aperture given by rock

  13. Sediment Transport and Infilling of a Borrow Pit on an Energetic Sandy Ebb Tidal Delta Offshore of Hilton Head Island, South Carolina

    Science.gov (United States)

    Wren, A.; Xu, K.; Ma, Y.; Sanger, D.; Van Dolah, R.

    2014-12-01

    Bottom-mounted instrumentation was deployed at two sites on an ebb tidal delta to measure hydrodynamics, sediment transport, and seabed elevation. One site ('borrow site') was 2 km offshore and used as a dredging site for beach nourishment of nearby Hilton Head Island in South Carolina, and the other site ('reference site') was 10 km offshore and not directly impacted by the dredging. In-situ time-series data were collected during two periods after the dredging: March 15 - June 12, 2012('spring') and August 18 - November 18, 2012 ('fall'). At the reference site directional wave spectra and upper water column current velocities were measured, as well as high-resolution current velocity profiles and suspended sediment concentration profiles in the Bottom Boundary Layer (BBL). Seabed elevation and small-scale seabed changes were also measured. At the borrow site seabed elevation and near-bed wave and current velocities were collected using an Acoustic Doppler Velocimeter. Throughout both deployments bottom wave orbital velocities ranged from 0 - 110 m/s at the reference site. Wave orbital velocities were much lower at the borrow site ranging from 10-20 cm/s, as wave energy was dissipated on the extensive and rough sand banks before reaching the borrow site. Suspended sediment concentrations increased throughout the BBL when orbital velocities increased to approximately 20 cm/s. Sediment grain size and critical shear stresses were similar at both sites, therefore, re-suspension due to waves was less frequent at the borrow site. However, sediment concentrations were highly correlated with the tidal cycle at both sites. Semidiurnal tidal currents were similar at the two sites, typically ranging from 0 - 50 cm/s in the BBL. Maximum currents exceeded the critical shear stress and measured suspended sediment concentrations increased during the first hours of the tidal cycle when the tide switched to flood tide. Results indicate waves contributed more to sediment mobility at

  14. Predicting the Isotopic Composition of Subduction-Filtered Subducted Oceanic Crust and Sediment

    Science.gov (United States)

    White, W. M.

    2010-12-01

    The chemical and isotopic character of mantle plumes, which produce oceanic island volcanoes, are widely thought to reflect the presence of recycled oceanic crust and sediment. Isotopic systematics suggest the “cycle time” for this process is 1 Ga or longer, but it should be possible to use a simple mass balance approach to discern how the presently operating subduction zone filter affects the ratios of radioactive parent to radiogenic daughter isotopes. Simple uniformitarian assumptions can then be used to predict the present isotopic composition of anciently subducted lithosphere. Our underlying assumption in deciphering the subduction zone filter is that the flux of an element into the deep mantle is simply equal to the flux of element into the subduction zone less the flux of that element into subduction zone magmas. The former is readily calculated from published data. The latter can be calculated by estimating parental magma compositions, arc accretion rates, and the assumption that arc magma compositions differ from MORB only because of material derived from subducting crust and sediment. Using this approach for 8 intra-oceanic subduction zones, we find 73% of Th and Pb, 79% of U, 80% of Rb and Sr, 93% of Nd and 98% of Sm survive the subduction zone filter. The subduction zone filter systematically increases Sm/Nd ratios in all subduction zones, but the effect is small, with a weighted mean increase of 1.5%. The effect of subduction is to decrease the Sm/Nd of the mantle, but only slightly. The effect of subduction is to increase the Rb/Sr of the mantle, but the subduction zone filter does not have a systematic effect on Rb/Sr ratios: it significantly increases in Rb/Sr in 3 subduction zones and significantly decreases it in one; the weighted mean shows no significant change. The effect of the subduction zone filter on U/Pb is also not systematic. U/Pb ratios in the mantle fluxes are bimodal, with values equal to or lower than the bulk Earth value in 4

  15. Regime shift in sandy beach microbial communities following Deepwater Horizon oil spill remediation efforts.

    Directory of Open Access Journals (Sweden)

    Annette Summers Engel

    Full Text Available Sandy beaches support a wide variety of underappreciated biodiversity that is critical to coastal ecosystems. Prior to the 2010 Deepwater Horizon oil spill, the diversity and function of supratidal beach sediment microbial communities along Gulf of Mexico coastlines were not well understood. As such, it was unclear if microbial community compositional changes would occur following exposure to beached oil, if indigenous communities could biodegrade oil, or how cleanup efforts, such as sand washing and sediment redistribution, would impact microbial ecosystem resiliency. Transects perpendicular to the shoreline were sampled from public beaches on Grand Isle, Louisiana, and Dauphin Island, Alabama, over one year. Prior to oil coming onshore, elevated levels of bacteria associated with fecal contamination were detected (e.g., Enterobacteriales and Campylobacterales. Over time, significant shifts within major phyla were identified (e.g., Proteobacteria, Firmicutes, Actinobacteria and fecal indicator groups were replaced by taxa affiliated with open-ocean and marine systems (e.g., Oceanospirillales, Rhodospirillales, and Rhodobacterales. These new bacterial groups included putative hydrocarbon degraders, similar to those identified near the oil plume offshore. Shifts in the microbial community composition strongly correlated to more poorly sorted sediment and grain size distributional changes. Natural oceanographic processes could not account for the disrupted sediment, especially from the backshore well above the maximum high-tide levels recorded at these sites. Sand washing and tilling occurred on both open beaches from August through at least December 2010, which were mechanisms that could replace fecal indicator groups with open-ocean groups. Consequently, remediation efforts meant to return beaches to pre-spill compositions caused a regime shift that may have added potential ecosystem function, like hydrocarbon degradation, to the sediment

  16. Regime shift in sandy beach microbial communities following Deepwater Horizon oil spill remediation efforts.

    Science.gov (United States)

    Engel, Annette Summers; Gupta, Axita A

    2014-01-01

    Sandy beaches support a wide variety of underappreciated biodiversity that is critical to coastal ecosystems. Prior to the 2010 Deepwater Horizon oil spill, the diversity and function of supratidal beach sediment microbial communities along Gulf of Mexico coastlines were not well understood. As such, it was unclear if microbial community compositional changes would occur following exposure to beached oil, if indigenous communities could biodegrade oil, or how cleanup efforts, such as sand washing and sediment redistribution, would impact microbial ecosystem resiliency. Transects perpendicular to the shoreline were sampled from public beaches on Grand Isle, Louisiana, and Dauphin Island, Alabama, over one year. Prior to oil coming onshore, elevated levels of bacteria associated with fecal contamination were detected (e.g., Enterobacteriales and Campylobacterales). Over time, significant shifts within major phyla were identified (e.g., Proteobacteria, Firmicutes, Actinobacteria) and fecal indicator groups were replaced by taxa affiliated with open-ocean and marine systems (e.g., Oceanospirillales, Rhodospirillales, and Rhodobacterales). These new bacterial groups included putative hydrocarbon degraders, similar to those identified near the oil plume offshore. Shifts in the microbial community composition strongly correlated to more poorly sorted sediment and grain size distributional changes. Natural oceanographic processes could not account for the disrupted sediment, especially from the backshore well above the maximum high-tide levels recorded at these sites. Sand washing and tilling occurred on both open beaches from August through at least December 2010, which were mechanisms that could replace fecal indicator groups with open-ocean groups. Consequently, remediation efforts meant to return beaches to pre-spill compositions caused a regime shift that may have added potential ecosystem function, like hydrocarbon degradation, to the sediment. Future research will

  17. Analyzing Hurricane Sandy

    Science.gov (United States)

    Convertino, Angelyn; Meyer, Stephan; Edwards, Becca

    2015-03-01

    Post-tropical Storm Sandy underwent extratropical transition shortly before making landfall in southern New Jersey October 29 2012. Data from this system was compared with data from Hurricane Ike (2008) which represents a classic hurricane with a clear eye wall and symmetry after landfall. Storm Sandy collided with a low pressure system coming in from the north as the hurricane made landfall on the US East coast. This contributed to Storm Sandy acting as a non-typical hurricane when it made landfall. Time histories of wind speed and wind direction were generated from data provided by Texas Tech's StickNet probes for both storms. The NOAA Weather and Climate program were used to generate radar loops of reflectivity during the landfall for both storms; these loops were compared with time histories for both Ike and Sandy to identify a relationship between time series data and storm-scale features identified on radar.

  18. Isolation and phylogenetic assignation of actinomycetes in the marine sediments from the Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    YU Yong; LI Huirong; ZENG Yinxin; CHEN Bo

    2005-01-01

    Actinomycetes in five marine sediments collected from the Arctic Ocean at depths of 43 to 3 050 m were cultivated using a variety of media. A total of 61 actinomycete colonies with substrate mycelia only were observed, and no colonies with aerial mycelia were observed under aerobic conditions at 15 ℃. From these colonies, 28 were selected to represent different morphological types.Denaturing gradient gel electrophoresis (DGGE) was used to check the purity of isolates and select representatives for subsequent sequencing. Phylogentic analyses based on nearly full-length 16S ribosomal RNA gene (rDNA) sequences indicated that the actinomycetes isolated were accommodated within genus Rhodococcus of family Nocardiaceae, genus Dietzia of family Dietziaceae,genera Janibacter and Terrabacter of family Instrasporangiaceae and genera Kocuria and Arthrobacter of family Micrococcaceae. One of the strains (P27-24) from the deep-sea sediment at depth of 3 050 m was found to be identical in 16S rDNA sequence(1474/1474)with the radiation-resistant Kocuria rosea ATCC 187T isolated from air. More than halfofthe isolates showed the similarities ranging from 99.5% to 99.9% in 16S rDNA sequence to dibenzofran-degrading, butyl 2-ethylhexanoate-hydrolysising and nitrile-metabolizing actinomycetes. All the strains isolated were psychrotolerant bacteria and grew better on the media prepared with natural seawater than on the media prepared with deionized water. Three of them (Dietzia sp. P27-10, Rhodococcus sp. S11-3 and Rhodococcus sp.P11-5)had an obligate growth requirement for salt, confirming that these strains are indigenous marine actinomycetes.

  19. Maps showing bathymetry and modern sediment thickness on the inner continental shelf offshore of Fire Island, New York, pre-Hurricane Sandy

    Science.gov (United States)

    Schwab, William C.; Denny, Jane F.; Baldwin, Wayne E.

    2014-01-01

    The U.S. Geological Survey mapped approximately 336 square kilometers of the lower shoreface and inner continental shelf offshore of Fire Island, New York, in 2011 by using interferometric sonar and high-resolution chirp seismic-reflection systems. This report presents maps of bathymetry, acoustic backscatter, the coastal plain unconformity, the Holocene marine transgressive surface, and modern sediment thickness. These spatial data support research on the Quaternary evolution of the Fire Island coastal system and provide baseline information for research on coastal processes along southern Long Island.

  20. Processing of 13C-labelled phytoplankton in a fine-grained sandy-shelf sediment (North Sea): relative importance of different macrofauna species

    DEFF Research Database (Denmark)

    Kamp, Anja; Witte, Ursula

    2005-01-01

    during the incubation periods. F. fabula, a facultative (surface) deposit- and suspension-feeder, Lanice conchilega (Polychaeta: Terebellidae), a suspension-feeder and the (sur- face) deposit-feeder Echinocardium cordatum (Echinodermata: Spatangidae) were responsible for the majority of macrofaunal...... carbon processing. Predatory macrofauna organisms like Nephtys spp. (Polychaeta: Nephtyidae) also quickly became labelled. The rapid subduction of fresh organic matter by F. fabula down to ca. 4 to 7 cm sediment depth could be demonstrated, and it is suggested that entrainment by macrofauna in this fine...

  1. 2014 NOAA Ortho-rectified Mosaic of Hurricane Sandy Coastal Impact Area

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains ortho-rectified mosaic tiles at 0.35m GSD created for NOAA Integrated Ocean and Coastal Mapping (IOCM) initiative in Hurricane Sandy coastal...

  2. On the effects of circulation, sediment resuspension and biological incorporation by diatoms in an ocean model of aluminium

    CERN Document Server

    van Hulten, Marco; Middag, Rob; de Baar, Hein; Gehlen, Marion; Dutay, Jean-Claude; Tagliabue, Alessandro

    2014-01-01

    The distribution of dissolved aluminium in the West Atlantic Ocean shows a mirror image with that of dissolved silicic acid, hinting at intricate interactions between the ocean cycling of Al and Si. The marine biogeochemistry of Al is of interest because of its potential impact on diatom opal remineralisation, hence Si availability. Furthermore, the dissolved Al concentration at the surface ocean has been used as a tracer for dust input, dust being the most important source of the bio-essential trace element iron to the ocean. Previously, the dissolved concentration of Al was simulated reasonably well with only a dust source, and scavenging by adsorption on settling biogenic debris as the only removal process. Here we explore the impacts of (i) a sediment source of Al in the Northern Hemisphere (especially north of ~40{\\deg}N), (ii) the imposed velocity field, and (iii) biological incorporation of Al on the modelled Al distribution in the ocean. The sediment source clearly improves the model results, and usin...

  3. Genome sequence of the ocean sediment bacterium Saccharomonospora marina type strain (XMU15T)

    Energy Technology Data Exchange (ETDEWEB)

    Klenk, Hans-Peter [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Lu, Megan [Los Alamos National Laboratory (LANL); Lucas, Susan [U.S. Department of Energy, Joint Genome Institute; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Pitluck, Sam [U.S. Department of Energy, Joint Genome Institute; Goodwin, Lynne A. [Los Alamos National Laboratory (LANL); Han, Cliff [Los Alamos National Laboratory (LANL); Tapia, Roxanne [Los Alamos National Laboratory (LANL); Brambilla, Evelyne-Marie [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Potter, Gabriele [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Land, Miriam L [ORNL; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Rohde, Manfred [HZI - Helmholtz Centre for Infection Research, Braunschweig, Germany; Goker, Markus [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Detter, J. Chris [U.S. Department of Energy, Joint Genome Institute; Li, Wen-Jun [Yunnan University, Kunming, China; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute; Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute

    2012-01-01

    Saccharomonospora marina Liu et al. 2010 is a member to the genomically so far poorly characterized genus Saccharomonospora in the family Pseudonocardiaceae. Members of the genus Sacharomonospora are of interest because they originate from diverse habitats, such as leaf litter, manure, compost, surface of peat, moist, over-heated grain, and ocean sediment, where they might play a role in the primary degradation of plant material by attacking hemicellulose. Organisms belonging to the genus are usually Gram-positive staining, non-acid fast, and classify among the actinomycetes. Next to S. viridis and S. azurea, S. marina is the third member in the genus Saccharomonospora for with a completely sequenced (permanent draft status) type strain genome will be published. Here we describe the features of this organism, together with the complete genome sequence, and annotation. The 5,965,593 bp long chromosome with its 5,727 protein-coding and 57 RNA genes was sequenced as part of the DOE funded Community Sequencing Program (CSP) 2010 at the Joint Genome Institute (JGI).

  4. Provenance analysis of central Arctic Ocean sediments: Implications for circum-Arctic ice sheet dynamics and ocean circulation during Late Pleistocene

    Science.gov (United States)

    Kaparulina, Ekaterina; Strand, Kari; Lunkka, Juha Pekka

    2016-09-01

    Mineralogical and geochemical data generated from the well referred shallow core 96/12-1pc on the Lomonosov Ridge, central Arctic Ocean was used to evaluate ice transport from the circum-Arctic sources and variability in sediment drainage and provenance changes. In this study heavy minerals in central Arctic sediments were used to determine those most prominent provenance areas and their changes related to the Late Pleistocene history of glaciations in the Arctic. Provenance changes were then used to infer variations in the paleoceanographic environment of the central Arctic Ocean, such as variations in the distribution of sea ice, icebergs controlled by the Arctic Ocean circulation. Four critical end-members including Victoria and Banks Islands, the Putorana Plateau, the Anabar Shield, and the Verkhoyansk Fold Belt were identified from the Amerasian and Eurasian source areas, and their proportional contributions were estimated in relation to Late Pleistocene ice sheet dynamics and ocean circulation. The results show changes in transport pathways and source areas within two examined transitions MIS6-5 and MIS4-3. The main source for material during MIS6-5 transition was Amerasian margin due to the high dolomite content in the studied section of sediments inferring strong Beaufort Gyre (BG) and Transpolar Drift (TPD) transport for this material. IRD material during late the MIS6 to 5 deglacial event was from terrigenous input through from the MacKenzie route Banks/Victoria Islands then transported as far as the Lomonosov Ridge area. The transition, MIS4-3 in comparison with MIS6-5, shows a clear shift in source areas, reflected in a different mineralogical composition of sediments, supplied from the Eurasian margin, such as the Anabar Shield, the Putorana Plateau and the Verkhoyansk Fold Belt during active decay of the Barents-Kara Ice Sheet presumable associated with an ice-dammed lake outburst then triggered by a strong TPD over the central Arctic. These two

  5. Sediment wave-forms and modes of construction on Mariana (and other) intra-oceanic arc volcanoes

    Science.gov (United States)

    Embley, R. W.; Stern, R. J.; Chadwick, B.; Tamura, Y.; Merle, S. G.

    2014-12-01

    Most intra-oceanic arc volcanoes are composite edifices constructed primarily in the submarine environment, built up by volcaniclastic sediments derived from hydroclastic and pyroclastic processes at/near the summits, punctuated by occasional lava flows and intrusions. Of particular interest in the mode of construction are extensive fields of large sediment waveforms (SWFs), up to >2 km wavelength and >100 m amplitude, on the submarine flanks of many islands and seamounts within the Mariana and other intra-oceanic subduction zones. These SWFs are composed of coarse-grained volcaniclastic sediments derived from the (approximate) point source summits of the island and submarine volcanoes. SWFs around some seamounts and islands, particularly those with large calderas, define quasi-concentric ring-like ridges, suggesting formation by density currents generated during submarine and island eruptions, and preserved for 10s of thousands of years. Some types of SWFs appear to have formed by progressive slumping of oversteepened slopes without fluidization. General conclusions about the origin of SWFs are hampered by the dearth of samples and high resolution seismic reflection profiles. However, large coherent slumps and debris avalanches documented for some ocean islands (e.g., Hawaiian Islands) are (mostly) are not as evident on the composite arc volcanoes. Submarine Mariana arc (and other intra-oceanic arc) volcanism probably spread volcaniclastic material primarily during submarine "Neptunian" eruptions and by progressive slides and other sediment flow rather than by catastrophic flank collapse. These processes could mitigate the Hawaiian-style of tsumami hazard, but Krakatoa-type tsunami hazards exist.

  6. Fate of copper complexes in hydrothermally altered deep-sea sediments from the Central Indian Ocean Basin.

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Sander, S.G.; Jayachandran, S.; Nath, B.N.; Nagaraju, G.; Chennuri, K.; Vudamala, K.; Lathika, N.; Mascarenhas-Pereira, M.B.L.

    version: Environ. Pollut., vol.194; 2014; 138-144 Fate of copper complexes in hydrothermally altered deep-sea sediments from the Central Indian Ocean Basin Parthasarathi Chakraborty*1, Sylvia G. Sander2, Saranya Jayachandran1, B. Nagender Nath1, , G... sulphide deposits on the seafloor. Mining companies are exploring underwater volcanic vents, hoping to extract metals such as gold (Au), copper (Cu), zinc (Zn), rare earth element etc (Birney et al., 2006). The initial stages of exploration are still...

  7. Metal release from contaminated coastal sediments under changing pH conditions: Implications for metal mobilization in acidified oceans.

    Science.gov (United States)

    Wang, Zaosheng; Wang, Yushao; Zhao, Peihong; Chen, Liuqin; Yan, Changzhou; Yan, Yijun; Chi, Qiaoqiao

    2015-12-30

    To investigate the impacts and processes of CO2-induced acidification on metal mobilization, laboratory-scale experiments were performed, simulating the scenarios where carbon dioxide was injected into sediment-seawater layers inside non-pressurized chambers. Coastal sediments were sampled from two sites with different contamination levels and subjected to pre-determined pH conditions. Sediment samples and overlying water were collected for metal analysis after 10-days. The results indicated that CO2-induced ocean acidification would provoke increased metal mobilization causing adverse side-effects on water quality. The mobility of metals from sediment to the overlying seawater was correlated with the reduction in pH. Results of sequential extractions of sediments illustrated that exchangeable metal forms were the dominant source of mobile metals. Collectively, our data revealed that high metal concentrations in overlying seawater released from contaminated sediments under acidic conditions may strengthen the existing contamination gradients in Maluan Bay and represent a potential risk to ecosystem health in coastal environments.

  8. Untargeted Screening and Distribution of Organo-Iodine Compounds in Sediments from Lake Michigan and the Arctic Ocean.

    Science.gov (United States)

    Peng, Hui; Chen, Chunli; Cantin, Jenna; Saunders, David M V; Sun, Jianxian; Tang, Song; Codling, Garry; Hecker, Markus; Wiseman, Steve; Jones, Paul D; Li, An; Rockne, Karl J; Sturchio, Neil C; Cai, Minghong; Giesy, John P

    2016-09-20

    The majority of halogenated organic compounds present in the environment remain unidentified. To address this data gap, we recently developed an untargeted method (data-independent precursor isolation and characteristic fragment; DIPIC-Frag) for identification of unknown organo-bromine compounds. In this study, the method was adapted to enable untargeted screening of natural and synthetic organo-iodine compounds (NSOICs) in sediments. A total of 4,238 NSOIC peaks were detected in sediments from Lake Michigan. Precursor ions and formulas were determined for 2,991 (71%) of the NSOIC peaks. These compounds exhibited variations in abundances (<10(3) to ∼10(7)), m/z values (206.9304-996.9474), retention times (1.0-29.7 min), and number of iodine atoms (1-4). Hierarchical cluster analysis showed that sediments in closer proximity exhibited similar profiles of NSOICs. NSOICs were screened in 10 samples of sediment from the Arctic Ocean to compare the profiles of NSOICs between freshwater and marine sediments. A total of 3,168 NSOIC peaks were detected, and profiles of NSOICs in marine sediments were clearly distinct from Lake Michigan. The coexistence of brominated and iodinated analogues indicated that some NSOICs are of natural origin. Different ratios of abundances of iodinated compounds to brominated analogues were observed and proposed as a marker to distinguish sources of NSOICs.

  9. Minor impact of ocean acidification to the composition of the active microbial community in an Arctic sediment.

    Science.gov (United States)

    Tait, Karen; Laverock, Bonnie; Shaw, Jennifer; Somerfield, Paul J; Widdicombe, Steve

    2013-12-01

    Effects of ocean acidification on the composition of the active bacterial and archaeal community within Arctic surface sediment was analysed in detail using 16S rRNA 454 pyrosequencing. Intact sediment cores were collected and exposed to one of five different pCO(2) concentrations [380 (present day), 540, 750, 1120 and 3000 μatm] and RNA extracted after a period of 14 days exposure. Measurements of diversity and multivariate similarity indicated very little difference between pCO(2) treatments. Only when the highest and lowest pCO(2) treatments were compared were significant differences evident, namely increases in the abundance of operational taxonomic units most closely related to the Halobacteria and differences to the presence/absence structure of the Planctomycetes. The relative abundance of members of the classes Planctomycetacia and Nitrospira increased with increasing pCO(2) concentration, indicating that these groups may be able to take advantage of changing pH or pCO(2) conditions. The modest response of the active microbial communities associated with these sediments may be due to the low and fluctuating pore-water pH already experienced by sediment microbes, a result of the pH buffering capacity of marine sediments, or due to currently unknown factors. Further research is required to fully understand the impact of elevated CO(2) on sediment physicochemical parameters, biogeochemistry and microbial community dynamics.

  10. The record of India-Asia collision preserved in Tethyan ocean basin sediments.

    Science.gov (United States)

    Najman, Yani; Jenks, Dan; Godin, Laurent; Boudagher-Fadel, Marcelle; Bown, Paul; Horstwood, Matt; Garzanti, Eduardo; Bracialli, Laura; Millar, Ian

    2015-04-01

    The timing of India-Asia collision is critical to the understanding of crustal deformation processes, since, for example, it impacts on calculations regarding the amount of convergence that needs to be accommodated by various mechanisms. In this research we use sediments originally deposited in the Tethyan ocean basin and now preserved in the Himalayan orogeny to constrain the timing of collision. In the NW Himalaya, a number of workers have proposed a ca 55-50 Ma age for collision along the Indus suture zone which separates India from the Kohistan-Ladakh Intraoceanic Island arc (KLA) to the north. This is based on a number of factors including the age of youngest marine sediments in the Indus suture (e.g. Green et al. 2008), age of eclogites indicative of onset of Indian continental subduction (e.g. de Sigoyer et al. 2000), and first evidence of detritus from north of the suture zone deposited on the Indian plate (e.g. Clift et al. 2002). Such evidence can be interpreted as documenting the age of India-Asia collision if one takes the KLA to have collided with the Asian plate prior to its collision with India (e.g. Petterson 2010 and refs therein). However, an increasing number of workers propose that the KLA collided with Asia subsequent to its earlier collision with India, dated variously at 85 Ma (Chatterjee et al. 2013), 61 Ma (Khan et al. 2009) and 50 Ma (Bouilhol et al. 2013). This, plus the questioning of earlier provenance work (Clift et al. 2002) regarding the validity of their data for constraining timing of earliest arrival of material north of the suture deposited on the Indian plate (Henderson et al. 2011) suggests that the time is right for a reappraisal of this topic. We use a provenance-based approach here, using combined U-Pb and Hf on detrital zircons from Tethyan ocean basin sediments, along with petrography and biostratigraphy, to identify first arrival of material from north of the Indian plate to arrive on the Indian continent, to constrain

  11. Mechanisms Leading to Co-Existence of Gas Hydrate in Ocean Sediments [Part 2 of 2

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, Steven; Juanes, Ruben

    2011-12-31

    In this project we have sought to explain the co-existence of gas and hydrate phases in sediments within the gas hydrate stability zone. We have focused on the gas/brine interface at the scale of individual grains in the sediment. The capillary forces associated with a gas/brine interface play a dominant role in many processes that occur in the pores of sediments and sedimentary rocks. The mechanical forces associated with the same interface can lead to fracture initiation and propagation in hydrate-bearing sediments. Thus the unifying theme of the research reported here is that pore scale phenomena are key to understanding large scale phenomena in hydrate-bearing sediments whenever a free gas phase is present. Our analysis of pore-scale phenomena in this project has delineated three regimes that govern processes in which the gas phase pressure is increasing: fracturing, capillary fingering and viscous fingering. These regimes are characterized by different morphology of the region invaded by the gas. On the other hand when the gas phase pressure is decreasing, the corresponding regimes are capillary fingering and compaction. In this project, we studied all these regimes except compaction. Many processes of interest in hydrate-bearing sediments can be better understood when placed in the context of the appropriate regime. For example, hydrate formation in sub-permafrost sediments falls in the capillary fingering regime, whereas gas invasion into ocean sediments is likely to fall into the fracturing regime. Our research provides insight into the mechanisms by which gas reservoirs are converted to hydrate as the base of the gas hydrate stability zone descends through the reservoir. If the reservoir was no longer being charged, then variation in grain size distribution within the reservoir explain hydrate saturation profiles such as that at Mt. Elbert, where sand-rich intervals containing little hydrate are interspersed between intervals containing large hydrate

  12. Insights into deep-sea sediment fungal communities from the East Indian Ocean using targeted environmental sequencing combined with traditional cultivation

    National Research Council Canada - National Science Library

    Zhang, Xiao-yong; Tang, Gui-ling; Xu, Xin-ya; Nong, Xu-hua; Qi, Shu-hua

    2014-01-01

    .... We investigated the fungal community structure in five sediments from a depth of ∼ 4000 m in the East India Ocean using a combination of targeted environmental sequencing and traditional cultivation...

  13. Evidence of Himalayan erosional event at approx. 0.5 Ma from a sediment core from the equatorial Indian Ocean in the vicinityof ODP Leg 116 sites

    Digital Repository Service at National Institute of Oceanography (India)

    Nath, B.N.; Gupta, S.M.; Mislankar, P.G.; Rao, B.R.; Parthiban, G.; Roelandts, I.; Patil, S.K.

    A sediment core collected from an area _100 miles south of the ODP Leg 116 (distal Bengal Fan) in the equatorial Indian Ocean was investigated for microfossils, mineralogy, mineral chemistry, magnetic susceptibility, grain size, major, minor...

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

    Directory of Open Access Journals (Sweden)

    A. Ridgwell

    2007-07-01

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

  15. Amino acid abundances and stereochemistry in hydrothermally altered sediments from the Juan de Fuca Ridge, northeastern Pacific Ocean.

    Science.gov (United States)

    Andersson, E; Simoneit, B R; Holm, N G

    2000-09-01

    The Juan de Fuca Ridge is a hydrothermally active, sediment covered, spreading ridge situated a few hundred kilometres off the west coast of North America in the northeastern Pacific Ocean. Sediments from seven sites drilled during the Ocean Drilling Program (ODP) Legs 139 and 168 were analyzed for total hydrolyzable amino acids (THAA), individual amino acid distributions, total organic C (TOC) and total N (TN) contents. The aim was to evaluate the effects of hydrothermal stress on the decomposition and transformation of sedimentary amino acids. Hydrolyzable amino acids account for up to 3.3% of the total organic C content and up to 12% of the total N content of the upper sediments. The total amounts of amino acids decrease significantly with depth in all drilled holes. This trend is particularly pronounced in holes with a thermal gradient of around 0.6 degrees C/m or higher. The most abundant amino acids in shallow sediments are glycine, alanine, lysine, glutamic acid, valine and histidine. The changes in amino acid distributions in low temperature holes are characterized by increased relative abundances of non-protein beta-alanine and gamma-aminobutyric acid. In high temperature holes the amino acid compositions are characterized by high abundances of glycine, alanine, serine, ornithine and histidine at depth. D/L ratios of samples with amino acid distributions similar to those found in acid hydrolysates of kerogen, indicate that racemization rates of amino acids bound by condensation reactions may be diminished.

  16. Paleosols can promote root growth of recent vegetation - a case study from the sandy soil-sediment sequence Rakt, the Netherlands

    Science.gov (United States)

    Gocke, Martina I.; Kessler, Fabian; van Mourik, Jan M.; Jansen, Boris; Wiesenberg, Guido L. B.

    2016-10-01

    Soil studies commonly comprise the uppermost meter for tracing, e.g., soil development. However, the maximum rooting depth of various plants significantly exceeds this depth. We hypothesized that deeper parts of the soil, soil parent material and especially paleosols provide beneficial conditions in terms of, e.g., nutrient contents, thus supporting their utilization and exploitation by deep roots. We aimed to decipher the different phases of soil formation in Dutch drift sands and cover sands. The study site is located at Bedafse Bergen (southeastern Netherlands) in a 200-year-old oak stand. A recent Podzol developed on drift sand covering a Plaggic Anthrosol that was piled up on a relict Podzol on Late Glacial eolian cover sand. Root-free soil and sediment samples, collected in 10-15 cm depth increments, were subjected to a multi-proxy physical and geochemical approach. The Plaggic Anthrosol revealed low bulk density and high phosphorous and organic carbon contents, whereas the relict Podzol was characterized by high iron and aluminum contents. Frequencies of fine (diameter ≤ 2 mm) and medium roots (2-5 mm) were determined on horizontal levels and the profile wall for a detailed pseudo-three-dimensional insight. On horizontal levels, living roots were most abundant in the uppermost part of the relict Podzol with ca. 4450 and 220 m-2, significantly exceeding topsoil root abundances. Roots of oak trees thus benefited from the favorable growth conditions in the nutrient-rich Plaggic Anthrosol, whereas increased compactness and high aluminum contents of the relict Podzol caused a strong decrease of roots. The approach demonstrated the benefit of comprehensive root investigation to support interpretation of soil profiles, as fine roots can be significantly underestimated when quantified at the profile wall. The possible rooting of soil parent material and paleosols long after their burial confirmed recent studies on the potential influence of rooting to overprint

  17. Geoacoustic character, sedimentology and chronology of a cross-shelf Holocene sediment deposit off Cabo Frio, Brazil (southwest Atlantic Ocean)

    Science.gov (United States)

    Mendoza, Ursula; Ayres Neto, Arthur; C. Abuchacra, Rodrigo; Fernandes Barbosa, Cátia; G. Figueiredo, Alberto; C. Gomes, Manoela; Belem, Andre L.; Capilla, Ramsés; S. Albuquerque, Ana Luiza

    2014-08-01

    The Cabo Frio region in the state of Rio de Janeiro, southeast coast of Brazil, is characterized by a local coastal upwelling system and converging littoral sediment transport systems that are deflected offshore at Cabo Frio, as a consequence of which a thick cross-shelf sediment deposit has developed over time. To investigate the evolution of this muddy deposit, geophysical, sedimentological and geochemical data from four sediment cores (3.8-4.1 m in length) recovered in water depths between 88 and 141 m were analyzed. The high-resolution seismic data show variable sediment thicknesses ranging from 1 to 20 m, comprising two sedimentary units separated by a high-impedance layer at a depth of about 10 m below the seafloor at the coring sites. According to the available age datings, the upper sedimentary unit is late Pleistocene to Holocene in age, whereas the lower unit (not dated) must, by implication, be entirely Pleistocene in age. The boomer-seismic reflection signal can be divided into three echo-types, namely transparent (inner shelf), stratified (middle shelf) and reflective (outer shelf), each type seemingly related to the local sediment composition. The upper 4 m of the upper sedimentary unit is dominated by silty sediment on the middle shelf, and by upward-fining sediments (silty sand to sandy silt) on the inner and outer shelf. The downcore trends of P-wave velocity, gamma-ray density and acoustic impedance are largely similar, but generally reversed to those of water and organic carbon contents. Total organic carbon contents increase with decreasing mean grain size, periodic fluctuations suggesting temporal changes in the regional hydrodynamics and primary productivity fuelled by the local upwelling system. The reconstruction of sedimentation rates in the course of the Holocene is based on 35 AMS age datings of organic material recovered from variable downcore depths. These range from a maximum of 13.3 cm/decade near the base of the inner shelf core (7

  18. Marinomonas profundimaris sp. nov., isolated from deep-sea sediment sample of the Arctic Ocean.

    Science.gov (United States)

    Bai, Xiuhua; Lai, Qiliang; Dong, Chunming; Li, Fuying; Shao, Zongze

    2014-09-01

    A taxonomic study was carried out on strain D104(T), which was isolated from deep-sea subsurface sediment sample from the Arctic Ocean. The bacterium was found to be Gram-negative, oxidase negative and catalase weakly positive, rod shaped, motile by means of polar flagellum. The organism grows between 4 and 37 °C (optimum 25-28 °C) and 0.5-6 % NaCl (optimum 3 %). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain D104(T) belongs to the genus Marinomonas, with highest sequence similarities of 97.7 % to Marinomonas ushuaiensis DSM 15871(T), followed by M. dokdonensis DSW10-10(T) (96.9 %), M. arenicola KMM 3893(T) (96.7 %), M. arctica 328(T) (96.6 %) and other 18 species of the genus Marinomonas (94.4-96.5 %). The average nucleotide identity and estimated DNA-DNA hybridization values between strain D104(T) and M. ushuaiensis DSM 15871(T) were 84.24 % and 20.80 ± 2.33 % respectively. The principal fatty acids were C16:0, sum in feature 3 (C16:1 ω7c/C16:1 ω6c), sum in feature 8 (C18:1 ω7c/C18:1 ω6c) and C12:1 3OH. The G + C content of the chromosomal DNA was determined to be 44.8 mol%. The respiratory quinone was found to be Q8 (100 %). Polar lipids include phosphatidylglycerol and phosphatidylethanolamine as major phospholipids and aminolipid and phospholipid as minor components. The results of the genotypic and phenotypic analyses indicate that strain D104(T) represents a novel species of the genus Marinomonas, for which the name Marinomonas profundimaris sp. nov. is proposed, with the type strain D104(T) (=MCCC 1A07573(T) = LMG 27696(T)).

  19. Glacial interglacial rain ratio changes: Implications for atmospheric CO2 and ocean sediment interaction

    Science.gov (United States)

    Munhoven, Guy

    2007-03-01

    A reduction of the carbonate-carbon to organic-carbon export rain ratio during glacial times has been advanced to explain the glacial-interglacial atmospheric CO2 variations. This hypothesis is tested and implications for the dynamics of sedimentary carbonate preservation and dissolution are explored with a multi-box model ( MBM) of the ocean carbon cycle, fully coupled to a new transient early diagenesis model (called MEDUSA). A peak reduction of the rain ratio by 40% at the Last Glacial Maximum (LGM) was found to produce a net atmospheric pCO2 reduction of about 40 ppm. Changing shelf carbonate accumulation rates and continental weathering inputs produced a 55-60 ppm reduction. The combination of the two mechanisms generates a pCO2 change of 90-95 ppm, which compares well with the observed data. However, the resulting model sedimentary record does not conform to actual sedimentary records. The changes related to continental shelf processes and variable weathering flux depress the calcite saturation horizon (CSH) by about 1 km at the LGM; if rain ratio variations are also considered, that depression increases by another km. In addition to this large amplitude for the CSH, possibly due to the adopted box-model approach, the changing rain ratio also leads to transition zone changes in the model sedimentary record that are opposite in phase with data-based reconstructions. Realistic changes in the aragonite fraction of the carbonate rain were found to have only a minimal impact on atmospheric pCO2. Finally, chemical erosion of deep-sea sediment was shown to reduce the amplitude of variation of the sedimentary CCD by about 10-20%. It may provide a mechanism to improve the model-data agreement.

  20. Hurricane Sandy Washover Deposits on Southern Long Beach Island, NJ

    Science.gov (United States)

    Bishop, J. M.; Richmond, B. M.; Kane, H. H.; Lunghino, B.

    2015-12-01

    Hurricane Sandy washover deposits were investigated at Forsyth National Wildlife Refuge (FNWR) on Southern Long Beach Island, New Jersey in order to map deposit thickness and characterize the sedimentary deposits. FNWR was chosen as a field area because there has been relatively little anthropogenic shoreline modification since washover deposition from Hurricane Sandy. Sediment, elevation, and geophysical data were collected during the April 2015 field campaign, approximately two and a half years after the storm. Sediment deposit data included trenches, stratigraphic descriptions, bulk sediment samples, push cores, Russian cores, and photos. Computed tomography (CT) scanning was conducted on push cores in order to acquire high resolution imaging of density, grain size, and sedimentary structure. Profiles of washover elevation were measured using Differential GPS with Real Time Kinematic processing. Ground Penetrating Radar data was collected to image the depth of the deposit and identify sedimentary structures. These data sets are compared to pre- and post -Sandy lidar surveys in order to determine post-Sandy modification in the two and a half years following the hurricane. We compare sediment thickness and sedimentary characteristics to hurricane Sandy deposits elsewhere along the U.S. eastern seaboard and to tsunami deposits.

  1. Correlating microbial community profiles with geochemical data in highly stratified sediments from the Arctic Mid-Ocean Ridge.

    Science.gov (United States)

    Jorgensen, Steffen Leth; Hannisdal, Bjarte; Lanzén, Anders; Baumberger, Tamara; Flesland, Kristin; Fonseca, Rita; Ovreås, Lise; Steen, Ida H; Thorseth, Ingunn H; Pedersen, Rolf B; Schleper, Christa

    2012-10-16

    Microbial communities and their associated metabolic activity in marine sediments have a profound impact on global biogeochemical cycles. Their composition and structure are attributed to geochemical and physical factors, but finding direct correlations has remained a challenge. Here we show a significant statistical relationship between variation in geochemical composition and prokaryotic community structure within deep-sea sediments. We obtained comprehensive geochemical data from two gravity cores near the hydrothermal vent field Loki's Castle at the Arctic Mid-Ocean Ridge, in the Norwegian-Greenland Sea. Geochemical properties in the rift valley sediments exhibited strong centimeter-scale stratigraphic variability. Microbial populations were profiled by pyrosequencing from 15 sediment horizons (59,364 16S rRNA gene tags), quantitatively assessed by qPCR, and phylogenetically analyzed. Although the same taxa were generally present in all samples, their relative abundances varied substantially among horizons and fluctuated between Bacteria- and Archaea-dominated communities. By independently summarizing covariance structures of the relative abundance data and geochemical data, using principal components analysis, we found a significant correlation between changes in geochemical composition and changes in community structure. Differences in organic carbon and mineralogy shaped the relative abundance of microbial taxa. We used correlations to build hypotheses about energy metabolisms, particularly of the Deep Sea Archaeal Group, specific Deltaproteobacteria, and sediment lineages of potentially anaerobic Marine Group I Archaea. We demonstrate that total prokaryotic community structure can be directly correlated to geochemistry within these sediments, thus enhancing our understanding of biogeochemical cycling and our ability to predict metabolisms of uncultured microbes in deep-sea sediments.

  2. Buried in time: culturable fungi in a deep-sea sediment core from the Chagos Trench, Indian Ocean

    Science.gov (United States)

    Raghukumar, Chandralata; Raghukumar, Seshagiri; Sheelu, G.; Gupta, S. M.; Nagender Nath, B.; Rao, B. R.

    2004-11-01

    The recovery of culturable microorganisms from ancient materials, ranging from a few thousand to several million years old, has generated interest in the long-term survival capabilities of micrororganisms. We report the occurrence of such paleobes for the first time from a deep-sea sediment core obtained from a depth of 5904 m from the Chagos trench in the Indian Ocean. Culturable fungi, direct counts of bacteria, age of the sediments based on the radiolarian assemblage, total organic carbon, Eh and CaCO3 were determined in these sediments. Culturable fungi were obtained from subsections up to 370 cm depth. The age of the sediments from which fungi were isolated was estimated to range from>0.18 to 0.43 million years (Ma), being the oldest recorded age for recovery of culturable fungi. Colony forming units of fungi ranged from 69 to 2493 g-1 dry weight sediment with a maximum abundance recorded at 160 cm depth of the core, corresponding to ∼0.18 Ma. Bacterial numbers in the core showed oscillations corresponding to cycles of approximately 100 ka (kilo years). The fungi comprised non-sporulating forms and a sporulating form identified to be Aspergillus sydowii. Germination of spores of A. sydowii at 100, 300 and 500 bar hydrostatic pressures at 5 °C confirmed its barotolerance and its nativity to deep-sea sediments. We propose that deep-sea sediments are a source of paleobes, which could be useful in studies on palaeoclimate, long-term microbial survival and biotechnology.

  3. Antagonistic Effects of Ocean Acidification and Rising Sea Surface Temperature on the Dissolution of Coral Reef Carbonate Sediments

    Directory of Open Access Journals (Sweden)

    Daniel Trnovsky

    2016-11-01

    Full Text Available Increasing atmospheric CO2 is raising sea surface temperature (SST and increasing seawater CO2 concentrations, resulting in a lower oceanic pH (ocean acidification; OA, which is expected to reduce the accretion of coral reef ecosystems. Although sediments comprise most of the calcium carbonate (CaCO3 within coral reefs, no in situ studies have looked at the combined effects of increased SST and OA on the dissolution of coral reef CaCO3 sediments. In situ benthic chamber incubations were used to measure dissolution rates in permeable CaCO3 sands under future OA and SST scenarios in a coral reef lagoon on Australia’s Great Barrier Reef (Heron Island. End of century (2100 simulations (temperature +2.7°C and pH -0.3 shifted carbonate sediments from net precipitating to net dissolving. Warming increased the rate of benthic respiration (R by 29% per 1°C and lowered the ratio of productivity to respiration (P/R; ΔP/R = -0.23, which increased the rate of CaCO3 sediment dissolution (average net increase of 18.9 mmol CaCO3 m-2 d-1 for business as usual scenarios. This is most likely due to the influence of warming on benthic P/R which, in turn, was an important control on sediment dissolution through the respiratory production of CO2. The effect of increasing CO2 on CaCO3 sediment dissolution (average net increase of 6.5 mmol CaCO3 m-2 d-1 for business as usual scenarios was significantly less than the effect of warming. However, the combined effect of increasing both SST and pCO2 on CaCO3 sediment dissolution was non-additive (average net increase of 5.6 mmol CaCO3 m-2 d-1 due to the different responses of the benthic community. This study highlights that benthic biogeochemical processes such as metabolism and associated CaCO3 sediment dissolution respond rapidly to changes in SST and OA, and that the response to multiple environmental changes are not necessarily additive.

  4. Numerical prediction on the scour burial of cylinder object freely resting on the sandy seabed in the East China Sea using the DRAMBUIE model1

    Institute of Scientific and Technical Information of China (English)

    Chong-guang PANG; Li-qian LIU; Kun LI

    2014-01-01

    After experiencing 8-day combined tidal current, circulation and wave actions, scour depth surrounding cylinder object freely resting on sandy seabed in the East China Sea (ECS) in January is numerically predicted using the DRAMBUIE model designed for scour burial, which has been widely used and verified by in-situ experiments. During the period of numerical integration, the value of time t is generally variable at every time step via the special time-stepped approach developed by this paper to eliminate the time error. The tidal current velocity, wave orbital velocity and the depth-averaged circulation in the ECS have been obtained by numerical simulations with Estuarine Coastal and Ocean Model (ECOM), Simulating Waves Nearshore (SWAN) model and Regional Ocean Modeling System (ROMS) model respectively. The control experiment and several idealized test cases on influential factors in scour depth reveal that the dominant hydrodynamic factor is tidal current in the ECS under normal weather conditions, and the impacts of shelf circulation and wave motion on local scour almost can be ignored with an exception of the Kuroshio area where the high-speed mainstream of Kuroshio flows. It is also indicated that in sandy sediments, the distribution of scour depth nearly follows the pattern of tidal currents, while the secondary influencing factor on scour depth appears to be grain size of sandy sediment in the ECS. Numerical tests on sediment grain size further testify that much finer sand is more easily scoured, and an increasing trend for scour depth with reduction of grain size is displayed due to imposed resistance of larger sized particles. Three aspects explored by this paper, including the empirical equations in the Defense Research Agency Mine Burial Environment (DRAMBUIE) model, the accuracy of inputs and infill process can severely affect the prediction of scour depth surrounding cylinder objects freely resting on sandy seabed in the ECS.

  5. Physical criteria for distinguishing sandy tsunami and storm deposits using modern examples

    Science.gov (United States)

    Morton, Robert A.; Gelfenbaum, Guy; Jaffe, Bruce E.

    2007-01-01

    Modern subaerial sand beds deposited by major tsunamis and hurricanes were compared at trench, transect, and sub-regional spatial scales to evaluate which attributes are most useful for distinguishing the two types of deposits. Physical criteria that may be diagnostic include: sediment composition, textures and grading, types and organization of stratification, thickness, geometry, and landscape conformity. Published reports of Pacific Ocean tsunami impacts and our field observations suggest that sandy tsunami deposits are generally 30 cm thick, generally extend The distinctions between tsunami and storm deposits are related to differences in the hydrodynamics and sediment-sorting processes during transport. Tsunami deposition results from a few high-velocity, long-period waves that entrain sediment from the shoreface, beach, and landward erosion zone. Tsunamis can have flow depths greater than 10 m, transport sediment primarily in suspension, and distribute the load over a broad region where sediment falls out of suspension when flow decelerates. In contrast, storm inundation generally is gradual and prolonged, consisting of many waves that erode beaches and dunes with no significant overland return flow until after the main flooding. Storm flow depths are commonly

  6. The Atlantic Coast of Maryland, Sediment Budget Update: Tier 2, Assateague Island and Ocean City Inlet

    Science.gov (United States)

    2016-06-01

    armoring, and placement of offshore borrow material on the shoreline. Over the past few years, several sediment budgets have been created to identify...sources, sinks, and sediment pathways. The most recent of these budgets covered the 1995 to 2002 and 2004 to 2008 epochs ( Offshore and Coastal...asset/1000361. Offshore and Coastal Technologies, Inc. (OCTI). 2011. Geomorphic and sediment budget analysis of Fenwick and Assateague Islands

  7. Ferromanganese nodules and their associated sediments from the Central Indian Ocean Basin: Rare earth element geochemistry

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Rao, Ch.M.; Migdisov, A.A.; Colley, S.; Higgs, N.C.; Demidenko, L.

    in the nodules are carried by Fe, P, and Ti, whereas in the sediment they are carried by P and Mn phases. A similar REE fractionation pattern with middle REE enrichment over heavy and light REE in both the nodules and their associated sediment suggest...

  8. Geochemistry of ferromanganese nodule-sediment pairs from central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Parthiban, G.

    compared to associated nodules; K and Na are almost in the similar range in nodule–sediment pairs and Mn, Fe, Ti, Mg, P, Ni, Cu, Mo, Zn, Co, Pb, Sr, V, Y, Li and REEs are all enriched in nodules compared to associated sediments (siliceous and calcareous...

  9. Efficacy of 230Th normalization in sediments from the Juan de Fuca Ridge, northeast Pacific Ocean

    Science.gov (United States)

    Costa, Kassandra; McManus, Jerry

    2017-01-01

    230Th normalization is an indispensable method for reconstructing sedimentation rates and mass fluxes over time, but the validity of this approach has generated considerable debate in the paleoceanographic community. 230Th systematics have been challenged with regards to grain size bias, sediment composition (CaCO3), water column advection, and other processes. In this study, we investigate the consequences of these effects on 230Th normalization from a suite of six cores on the Juan de Fuca Ridge. The proximity of these cores (<30 km) suggests that they should receive the same particle rain rate of sediment, but the steep bathymetry of the ridge leads to substantial sediment redistribution and variable carbonate preservation, both of which may limit the usage of 230Th in this region. Despite anticipated complications, 230Th normalization effectively reconstructs nearly identical particle rain rates from all six cores, which are summarily unrelated to the total sedimentation rates as calculated from the age models. Instead the total sedimentation rates are controlled almost entirely by sediment focusing and winnowing, which are highly variable even over the short spatial scales investigated in this study. Furthermore, no feedbacks on 230Th systematics were detected as a consequence of sediment focusing, coarse fraction variability, or calcium carbonate content, supporting the robustness of the 230Th normalization technique.

  10. Modern sediments and Pleistocene reefs from isolated carbonate platforms (Iles Eparses, SW Indian Ocean): A preliminary study

    Science.gov (United States)

    Jorry, Stéphan J.; Camoin, Gilbert F.; Jouet, Gwénaël; Roy, Pascal Le; Vella, Claude; Courgeon, Simon; Prat, Sophie; Fontanier, Christophe; Paumard, Victorien; Boulle, Julien; Caline, Bruno; Borgomano, Jean

    2016-04-01

    Isolated carbonate platforms occur throughout the geologic record, from Archean to present. Although the respective roles of tectonics, sediment supply and sea-level changes in the stratigraphical architecture of these systems are relatively well constrained, the details of the nature and controls on the variability of sedimentological patterns between and within individual geomorphologic units on platforms have been barely investigated. This study aims at describing and comparing geomorphological and sedimentological features of surficial sediments and fossil reefs from three isolated carbonate platforms located in the SW Indian Ocean (Glorieuses, Juan de Nova and Europa). These carbonate platforms are relatively small and lack continuous reef margins, which have developed only on windward sides. Field observations, petrographic characterization and grain-size analyses are used to illustrate the spatial patterns of sediment accumulation on these platforms. The internal parts of both Glorieuses and Juan de Nova platforms are blanketed by sand dunes with medium to coarse sands with numerous reef pinnacles. Skeletal components including coral, green algae, and benthic foraminifera fragments prevail in these sediments. Europa platform exhibits a similar skeletal assemblage dominated by coral fragments, with the absence of wave-driven sedimentary bodies. Fossil reefs from the Last interglacial (125,000 years BP) occur on the three platforms. At Glorieuses, a succession of drowned terraces detected on seismic lines is interpreted as reflecting the last deglacial sea-level rise initiated 20,000 years ago. These findings highlight the high potential of these platforms to study past sea-level changes and the related reef response, which remain poorly documented in the SW Indian Ocean.

  11. Organic carbon and nitrogen in the surface sediments of world oceans and seas: distribution and relationship to bottom topography

    Energy Technology Data Exchange (ETDEWEB)

    Premuzic, E.T.

    1980-06-01

    Information dealing with the distribution of organic carbon and nitrogen in the top sediments of world oceans and seas has been gathered and evaluated. Based on the available information a master chart has been constructed which shows world distribution of sedimentary organic matter in the oceans and seas. Since organic matter exerts an influence upon the settling properties of fine inorganic particles, e.g. clay minerals and further, the interaction between organic matter and clay minerals is maximal, a relationship between the overall bottom topography and the distribution of clay minerals and organic matter should be observable on a worldwide basis. Initial analysis of the available data indicates that such a relationship does exist and its significance is discussed.

  12. A new XRF probe for in-situ determining concentration of multi-elements in ocean sediments

    CERN Document Server

    Ge Liang Quan; Zhou Si Chun; Lin Ling; Lin Yan Chang; Ren Jia Fu

    2001-01-01

    The author introduces a new X-ray fluorescence probe for in-situ determining the concentration of multi-elements in ocean sediments. The probe consists of Si-Pin X-ray detector with an electro-thermal colder, two isotope sources, essential electrical signal processing units and a notebook computer. More than 10 elements can be simultaneously determined at a detection limit of (10-200) x 10 sup - sup 6 and precision of 5%-30% without liquid Nitrogen supply. tests show that the probe can perform the analytical tasks under the water at the depth of less than 1000 meters

  13. Hydrothermal Fe cycling and deep ocean organic carbon scavenging: Model-based evidence for significant POC supply to seafloor sediments

    Science.gov (United States)

    German, C. R.; Legendre, L. L.; Sander, S. G.; Niquil, N.; Luther, G. W.; Bharati, L.; Han, X.; Le Bris, N.

    2015-06-01

    Submarine hydrothermal venting has recently been identified to have the potential to impact ocean biogeochemistry at the global scale. This is the case because processes active in hydrothermal plumes are so vigorous that the residence time of the ocean, with respect to cycling through hydrothermal plumes, is comparable to that of deep ocean mixing caused by thermohaline circulation. Recently, it has been argued that seafloor venting may provide a significant source of bio-essential Fe to the oceans as the result of a close coupling between Fe and organic carbon in hydrothermal plumes. But a complementary question remains to be addressed: does this same intimate Fe-Corg association in hydrothermal plumes cause any related impact to the global C cycle? To address this, SCOR-InterRidge Working Group 135 developed a modeling approach to synthesize site-specific field data from the East Pacific Rise 9°50‧ N hydrothermal field, where the range of requisite data sets is most complete, and combine those inputs with global estimates for dissolved Fe inputs from venting to the oceans to establish a coherent model with which to investigate hydrothermal Corg cycling. The results place new constraints on submarine Fe vent fluxes worldwide, including an indication that the majority of Fe supplied to hydrothermal plumes should come from entrainment of diffuse flow. While this same entrainment is not predicted to enhance the supply of dissolved organic carbon to hydrothermal plumes by more than ∼10% over background values, what the model does indicate is that scavenging of carbon in association with Fe-rich hydrothermal plume particles should play a significant role in the delivery of particulate organic carbon to deep ocean sediments, worldwide.

  14. Estimation of potentially contaminated sediment volume in cases of oil spill in a summer conditions to sandy beaches of Rio Grande do Sul, Brazil; Estimativa do volume sedimentar potencialmente contaminado em casos de derrame de oleo em condicoes de verao para praias arenosas do Rio Grande do Sul

    Energy Technology Data Exchange (ETDEWEB)

    Costi, Juliana; Calliari, Lauro J. [Fundacao Universidade Federal do Rio Grande (FURG), RS (Brazil)

    2008-07-01

    Field experiments relating oil of two different densities with sediment penetration along ocean beaches with distinct morphodynamic behavior along the RS coastline indicates that, for both types of oil, higher penetration is associated to beaches which display higher mean grain size. Based on penetration depth it is possible to estimate the volume of contaminated sediments due to oil spills that eventually can reach the coast. Sediment cores sampled at 80 days interval at two different places characterized by a dissipative and a intermediate beaches indicate a higher variation of the sediment parameters and volume associated to the intermediate beach. (author)

  15. New occurrence of Youngest Toba Tuff in abyssal sediments of the Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

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

    Volcanic glass and pumice found in siliceous abyssal sediments of the Central Indian Basin, south of the Equator, have previously been assigned various origins including intra-basin volcanism, Indonesian arc, and Krakatau. Rhyolitic glass shards...

  16. Microscale response of sediment variables to benthic disturbance in the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, S.; Mohandass, C.; LokaBharathi, P.A.; Sheelu, G.; Raghukumar, C.

    was applied to determine the effect of disturbance on sediment characteris-tics and microbial load. The data were also treated for corelation analysis to find whether a linearity existed betwen the variables. The bacterial data were log... parameters after disturbance. Our study highlights the fact that bacteria play a quantitatively major role in the CIOB,and any biotic or abiotic artifact will directly affect the density and biochemical characteris-tics of the sediments. The magnitude...

  17. The influence of hypercapnia and macrofauna on sediment nutrient flux – will ocean acidification affect nutrient exchange?

    Directory of Open Access Journals (Sweden)

    H. L. Wood

    2009-02-01

    Full Text Available Rising levels of atmospheric carbon dioxide and the concomitant increased uptake of this by the oceans is resulting in hypercapnia-related reduction of ocean pH. Research focussed on the direct effects of these physicochemical changes on marine invertebrates has begun to improve our understanding of impacts at the level of individual physiologies. However, CO2-related impairment of organisms' contribution to ecological or ecosystem processes has barely been addressed. The burrowing ophiuroid Amphiura filiformis, which has a physiology that makes it susceptible to reduced pH, plays a key role in sediment nutrient cycling by mixing and irrigating the sediment, a process known as bioturbation. Here we investigate the role of A. filiformis in modifying nutrient flux rates across the sediment-water boundary and the impact of CO2-related acidification on this process. A 40 day exposure study was conducted under predicted pH scenarios from the years 2100 (pH 7.7 and 2300 (pH 7.3, plus an additional treatment of pH 6.8. This study demonstrated strong relationships between A. filiformis density and cycling of some nutrients; A. filiformis activity increases the sediment uptake of phosphate and the release of nitrite and nitrate. No relationship between A. filiformis density and the flux of ammonium or silicate were observed. Results also indicated that, within the timescale of this experiment, effects at the individual bioturbator level appear not to translate into reduced ecosystem influence. Rather the effect of hypercapnia and lowered pH on bacteria and microphytobenthos may have been of greater significance in understanding the changes to nutrient fluxes seen here. However, long term survival of key bioturbating species is far from assured and changes in both bioturbation and microbial processes could alter key biogeochemical processes in future, more acidic oceans.

  18. Patterns of species richness in sandy beaches of South America

    African Journals Online (AJOL)

    Species richness of the intertidal macroinfauna of exposed sandy beaches around South America is reviewed in relation ... The middle shore is primsediment packing (expressed hae as penetrability of the ..... show significant changes in species composition with lati-.

  19. Detecting Astrobiologically Significant Ocean Floor Sediments in the Tsunami-Battered Coasts of Early Mars

    Science.gov (United States)

    Rodriguez, J. A. P.; Zarroca, M.; Linares, R.; Komatsu, G.; Oehler, D.; Davila, A.; Baker, V.; Bernman, D.; Miyamoto, H.

    2017-10-01

    We document a potential tsunami deposit that was emplaced over a possible early Mars coastal cape. Unlike other deposits proposed to have been due to tsunamis extending far inland, its composition may be dominated by displaced ocean floor materials.

  20. Basalt microlapilli in deep sea sediments of Indian Ocean in the vicinity of Vityaz fracture zone

    Digital Repository Service at National Institute of Oceanography (India)

    Nath, B.N.; Iyer, S.D.

    Two cores recovered from the flanks of Mid-India oceanic ridge in the vicinity of Vityaz fracture zone consist of discrete pyroclastic layers at various depths. These layers are composed of coarse-grained, angular basaltic microlapilli in which...

  1. Spatial and Temporal Variations in the Geomagnetic Field Determined From the Paleomagnetism of Sediment Cores From Scientific Ocean Drilling

    Science.gov (United States)

    Acton, G.

    2014-12-01

    Quantifying the spatial and temporal variations of the main geomagnetic field at Earth's surface is important for understanding underlying geodynamo processes and conditions near the core-mantle boundary. Much of the geomagnetic variability, known as secular variation, occurs on timescales of tens of years to many thousands of years, requiring the use of paleomagnetic observations to derive continuous records of the ancient field, referred to as paleosecular variation (PSV) records. Marine depositional systems where thick sedimentary sections accumulate at high sedimentation rates provide some of the best locations for obtaining long continuous PSV records that can reveal both the short- and long-term changes in the field. Scientific ocean drilling has been successful at recovering many such sections and the paleomagnetic records from these reveal how the amplitude of PSV differs between sites and through time. In this study, several such records cored during Ocean Drilling Program (ODP), Integrated Ocean Drilling Program (IODP), and other cruises from high, mid, and low latitudes will be used to quantify time intervals of low and high PSV, to examine time-average properties of the field, to map spatial variations in the angular dispersion of the virtual geomagnetic pole (VGP), and to assess whether the spatial variation in angular dispersion changes with time.

  2. Fatty acids in sediments and phytoplankton data were collected from the Equatorial Pacific Ocean as part of the Joint Global Ocean Flux Study/Equatorial Pacific Basin Study (JGOFS/EQPAC) project., from 1992-02-03 to 1992-12-13 (NODC Accession 9700180)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fatty acids in sediments and phytoplankton data were collected using plankton tow, sediments sampler - corer, pump and CTD casts from the R/V THOMAS THOMPSON in the...

  3. Investigating Sea Ice Regimes and Glacial Cycles of the Early Pleistocene in a Sediment Record from the Northwind Ridge, Western Arctic Ocean

    Science.gov (United States)

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

    2014-12-01

    We are conducting a comprehensive study of a sediment record from the Arctic Ocean in order to improve our understanding of paleoceanographic conditions during the early Pleistocene, a potential paleo-analog for the current and future states of the Arctic. The study deals with a sediment core raised on the HOTRAX 2005 expedition from the Northwind Ridge, western Arctic Ocean. By comparison with an earlier reported stratigraphy (Polyak et al., 2013), the core dates back to estimated ca. 1.5 Ma. A suite of paleobiological, lithological, and geochemical proxies will be utilized to reconstruct paleoceanographic environments in the early Pleistocene part of the record. In contrast to most Arctic Ocean sediment cores, calcareous microfossils occur in abundance to ca. 1.2 Ma. This enables the use of microfaunal assemblages as proxies for sea-ice conditions, which control the seasonal organic production. Physical properties such as sediment density, grain size, and sediment fabric (based on XCT imagery) will be employed to determine the impact of glaciations on sedimentation. By reconstructing sea-ice history and glacial cycles, we will gain insights into poorly understood controls on the Arctic environments during the early Pleistocene and Mid-Pleistocene Transition.

  4. In situ measurements of thermal diffusivity in sediments of the methane-rich zone of Cascadia Margin, NE Pacific Ocean

    Directory of Open Access Journals (Sweden)

    Kira Homola

    2015-02-01

    Full Text Available Abstract Thermal diffusivity (TD is a measure of the temperature response of a material to external thermal forcing. In this study, TD values for marine sediments were determined in situ at two locations on the Cascadia Margin using an instrumented sediment probe deployed by a remotely operated vehicle. TD measurements in this area of the NE Pacific Ocean are important for characterizing the upslope edge of the methane hydrate stability zone, which is the climate-sensitive boundary of a global-scale carbon reservoir. The probe was deployed on the Cascadia Margin at water depths of 552 and 1049 m for a total of 6 days at each site. The instrumented probe consisted of four thermistors aligned vertically, one sensor exposed to the bottom water and one each at 5, 10, and 15 cm within the sediment. Results from each deployment were analyzed using a thermal conduction model applying a range of TD values to obtain the best fit with the experimental data. TD values corresponding to the lowest standard deviations from the numerical model runs were selected as the best approximations. Overall TDs of Cascadia Margin sediments of 4.33 and 1.15 × 10–7 m2 s–1 were calculated for the two deployments. These values, the first of their kind to be determined from in situ measurements on a methane hydrate-rich continental margin, are expected to be useful in the development of models of bottom-water temperature increases and their implications on a global scale.

  5. Identifying the sources and processes of mercury in subtropical estuarine and ocean sediments using Hg isotopic composition.

    Science.gov (United States)

    Yin, Runsheng; Feng, Xinbin; Chen, Baowei; Zhang, Junjun; Wang, Wenxiong; Li, Xiangdong

    2015-02-03

    The concentrations and isotopic compositions of mercury (Hg) in surface sediments of the Pearl River Estuary (PRE) and the South China Sea (SCS) were analyzed. The data revealed significant differences between the total Hg (THg) in fine-grained sediments collected from the PRE (8-251 μg kg(-1)) and those collected from the SCS (12-83 μg kg(-1)). Large spatial variations in Hg isotopic compositions were observed in the SCS (δ(202)Hg, from -2.82 to -2.10‰; Δ(199)Hg, from +0.21 to +0.45‰) and PRE (δ(202)Hg, from -2.80 to -0.68‰; Δ(199)Hg, from -0.15 to +0.16‰). The large positive Δ(199)Hg in the SCS indicated that a fraction of Hg has undergone Hg(2+) photoreduction processes prior to incorporation into the sediments. The relatively negative Δ(199)Hg values in the PRE indicated that photoreduction of Hg is not the primary route for the removal of Hg from the water column. The riverine input of fine particles played an important role in transporting Hg to the PRE sediments. In the deep ocean bed of the SCS, source-related signatures of Hg isotopes may have been altered by natural geochemical processes (e.g., Hg(2+) photoreduction and preferential adsorption processes). Using Hg isotope compositions, we estimate that river deliveries of Hg from industrial and urban sources and natural soils could be the main inputs of Hg to the PRE. However, the use of Hg isotopes as tracers in source attribution could be limited because of the isotope fractionation by natural processes in the SCS.

  6. Velocity-porosity relationships for slope apron and accreted sediments in the Nankai Trough Seismogenic Zone Experiment, Integrated Ocean Drilling Program Expedition 315 Site C0001

    Science.gov (United States)

    Hashimoto, Y.; Tobin, H. J.; Knuth, M.

    2010-12-01

    In this study, we focused on the porosity and compressional wave velocity of marine sediments to examine the physical properties of the slope apron and the accreted sediments. This approach allows us to identify characteristic variations between sediments being deposited onto the active prism and those deposited on the oceanic plate and then carried into the prism during subduction. For this purpose we conducted ultrasonic compressional wave velocity measurements on the obtained core samples with pore pressure control. Site C0001 in the Nankai Trough Seismogenic Zone Experiment transect of the Integrated Ocean Drilling Program is located in the hanging wall of the midslope megasplay thrust fault in the Nankai subduction zone offshore of the Kii peninsula (SW Japan), penetrating an unconformity at ˜200 m depth between slope apron sediments and the underlying accreted sediments. We used samples from Site C0001. Compressional wave velocity from laboratory measurements ranges from ˜1.6 to ˜2.0 km/s at hydrostatic pore pressure conditions estimated from sample depth. The compressional wave velocity-porosity relationship for the slope apron sediments shows a slope almost parallel to the slope for global empirical relationships. In contrast, the velocity-porosity relationship for the accreted sediments shows a slightly steeper slope than that of the slope apron sediments at 0.55 of porosity. This higher slope in the velocity-porosity relationship is found to be characteristic of the accreted sediments. Textural analysis was also conducted to examine the relationship between microstructural texture and acoustic properties. Images from micro-X-ray CT indicated a homogeneous and well-sorted distribution of small pores both in shallow and in deeper sections. Other mechanisms such as lithology, clay fraction, and abnormal fluid pressure were found to be insufficient to explain the higher velocity for accreted sediments. The higher slope in velocity-porosity relationship for

  7. 2012-2013 Post-Hurricane Sandy EAARL-B Submerged Topography - Barnegat Bay, New Jersey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Binary point-cloud data for part of Barnegat Bay, New Jersey, post-Hurricane Sandy (October 2012 hurricane), were produced from remotely sensed, geographically...

  8. 2014 U.S. Geological Survey CMGP LiDAR: Post Sandy (New Jersey)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — TASK NAME: USGS New Jersey CMGP Sandy Lidar 0.7 Meter NPS LIDAR lidar Data Acquisition and Processing Production Task USGS Contract No. G10PC00057 Task Order No....

  9. 2012 USGS EAARL-B Coastal Topography: Post-Sandy, First Surface (NJ)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — ASCII xyz and binary point-cloud data, as well as a digital elevation model (DEM) of a portion of the New Jersey coastline, pre- and post-Hurricane Sandy (October...

  10. Late Pleistocene sedimentation: A case study of the central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Borole, D.V.

    - A234) exp (,~.230t), (1) where A230 and A234 are the activities of 23(~1~h and 234U, 2230 is radioactive decay constant, and t is the time since deposition of the sediment stratum. For core F-200B, the age corrected 23°Wh° x values are listed...

  11. Rare earth element studies of surficial sediments from the southwestern Carlsberg Ridge, Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N; Higgs, N

    into these sediments is suggested from the weak positive Eu/Eu anomaly. Shale-normalized (NASC) pattern along with La sub((n)/Yb sub((n) ratio suggest enrichment of heavy REE (HREE) relative to the light REE (LREE) with a negative Ce/Ce anomaly implying retention of a...

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

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  13. Biogenic silica in space and time in sediments of Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Gupta, S.M.; Mudholkar, A.V.; Parthiban, G.

    rate averages 2.25 x 10/5 g.cm/2.y/1 and it is contributed from 33 to 50% of the total silica. Higher biogenic silica content of the surface sediment is well correlated with Mn, Cu and Ni concentration of the overlying manganese nodules. Higher biogenic...

  14. Inventory of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb in marine sediments cores of Southwest Atlantic Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Alice M.R.; Oliveira, Joselene de, E-mail: alice.costa@usp.br, E-mail: jolivei@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Gerencia de Metrologia das Radiacoes. Lab. de Radiometria Ambiental; Figueira, Rubens C.L.; Mahiques, Michel M.; Sousa, Silvia H.M., E-mail: rfigueira@usp.br, E-mail: mahiques@usp.br, E-mail: smsousa@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto Oceanografico

    2015-07-01

    {sup 210}Pb (22.3 y) is a radioactive isotope successfully applied as tracer of sediment dating of the last 100-150 years. The application of {sup 226}Ra and {sup 228}Ra as paleoceanographic tracers (half-lives of 1,600 y and 5.7 y, respectively) also gives some information of ocean's role in past climate change. In this work, it was analyzed 2 sediment cores collect at Southwest Atlantic Ocean. The sediments samples were freeze-dried and acid digested in microwave. It was carried out a radiochemical separation of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb and performed a gross alpha and gross beta measurement of both precipitates Ba(Ra)SO{sub 4} and PbCrO{sub 4} in a low background gas-flow proportional counter. Activity concentrations of {sup 226}Ra ranged from 45 Bq kg{sup -1} to 70 Bq kg{sup -1} in NAP-62 and from 57 Bq kg{sup -1} to 82 Bq kg{sup -1} in NAP-63 samples. The concentration of {sup 228}Ra varied between 37 Bq kg{sup -1} and 150 Bq kg{sup -1} in NAP-62 and between 23 Bq kg{sup -1} and 111 Bq kg{sup -1} in NAP-63 samples. The concentration of total {sup 210}Pb ranged from 126 Bq kg{sup -1} to 256 Bq kg{sup -1} in NAP-62 and from 63 Bq kg{sup -1} to 945 Bq kg{sup -1} in NAP-63 samples. Results of {sup 210}Pb{sub uns} varied from 68 Bq kg{sup -1} to 192 Bq kg{sup -1} for NAP-62, while varied from <4.9 Bq kg{sup -1} to 870 Bq kg{sup -1} in NAP-63 profile. Increased values of {sup 210}Pb{sub uns} were found on the top of both NAP-62 and NAP- 63 sediment profile. (author)

  15. Late Cretaceous - Paleogene forearc sedimentation and accretion of oceanic plateaus and seamounts along the Middle American convergent margin (Costa Rica)

    Science.gov (United States)

    Baumgartner, Peter O.; Baumgartner-Mora, Claudia; Andjic, Goran

    2016-04-01

    The Late Cretaceous-Paleogene sedimentation pattern in space and time along the Middle American convergent margin was controlled by the accretion of Pacific plateaus and seamounts. The accretion of more voluminous plateaus must have caused the temporary extinction of the arc and tectonic uplift, resulting in short lived episodes of both pelagic and neritic biogenic sedimentation. By the Late Eocene, shallow carbonate environments became widespread on a supposed mature arc edifice, that is so far only documented in arc-derived sediments. In northern Costa Rica forearc sedimentation started during the Coniacian-Santonian on the Aptian-Turonian basement of the Manzanillo Terrane. The arrival and collision of the Nicoya Terrane (a CLIP-like, 139-83 Ma Pacific plateau) and the Santa Elena Terrane caused the extinction of the arc during late Campanian- Early Maastrichtian times, indicated by the change to pelagic limestone sedimentation (Piedras Blancas Formation) in deeper areas and shallow-water rudistid - Larger Benthic Foraminfera limestone on tectonically uplifted areas of all terranes. Arc-derived turbidite sedimentation resumed in the Late Maastrichtian and was again interrupted during the Late Paleocene - Early Eocene, perhaps due to the underplating of a yet unknown large seamount. The extinction of the arc resulted in the deposition of the siliceous pelagic Buenavista Formation, as well as the principally Thanetian Barra Honda carbonate platform on a deeply eroded structural high in the Tempisque area. In southern Costa Rica the basement is thought to be the western edge of the CLIP. It is Santonian-Campanian in age and is only exposed in the southwestern corner of Herradura. Cretaceous arc-forearc sequences are unknown, except for the Maastrichtian-Paleocene Golfito Terrane in southeastern Costa Rica. The distribution and age of shallow/pelagic carbonates vs. arc-derived detrital sediments is controlled by the history of accretion of Galápagos hot spot

  16. Sediment transport on the inner shelf off Khao Lak (Andaman Sea, Thailand) during the 2004 Indian Ocean tsunami and former storm events: evidence from foraminiferal transfer functions

    Science.gov (United States)

    Milker, Y.; Wilken, M.; Schumann, J.; Sakuna, D.; Feldens, P.; Schwarzer, K.; Schmiedl, G.

    2013-12-01

    We have investigated the benthic foraminiferal fauna from sediment event layers associated with the 2004 Indian Ocean tsunami and former storms that have been retrieved in short sediment cores from offshore environments of the Andaman Sea, off Khao Lak, western Thailand. Species composition and test preservation of the benthic foraminiferal faunas exhibit pronounced changes across the studied sections and provide information on the depositional history of the tsunami layer, particularly on the source water depth of the displaced foraminiferal tests. In order to obtain accurate bathymetric information on sediment provenance, we have mapped the distribution of modern faunas in non-tsunamigenic surface sediments and created a calibration data set for the development of a transfer function. Our quantitative reconstructions revealed that the resuspension of sediment particles by the tsunami wave was restricted to a maximum water depth of approximately 20 m. Similar values were obtained for former storm events, thus impeding an easy distinction of different high-energy events.

  17. Determination of rare earth, major and trace elements in authigenic fraction of Andaman Sea (Northeastern Indian Ocean) sediments by inductively coupled plasma-mass spectrometry

    Digital Repository Service at National Institute of Oceanography (India)

    Alagarsamy, R.; You, C.-F.; Nath, B.N.; SijinKumar, A.V.

    Downcore variation of rare earth elements (REEs) in the authigenic Fe-Mn oxides of a sediment core (covering a record of last approx. 40 kyr) from the Andaman Sea, a part of the Indian Ocean shows distinctive positive Ce and Eu anomalies...

  18. Controls on organic carbon and molybdenum accumulation in Cretaceous marine sediments from the Cenomanian-Turonian interval including Oceanic Anoxic Event 2

    NARCIS (Netherlands)

    Dale, A.W.|info:eu-repo/dai/nl/340288221; Meyers, S.R.; Aguilera, D.R.; Arndt, S.|info:eu-repo/dai/nl/304835706; Wallmann, K.

    This study investigates the controls on organic carbon and molybdenum (Mo) accumulation in sediments deposited within the Western Interior Seaway across the Cenomanian–Turonian boundary interval (94.34–93.04 Ma) including Oceanic Anoxic Event 2 (OAE2). Carbon fluxes to the sediment–water interface

  19. The impact of ocean deoxygenation on iron release from continental margin sediments

    OpenAIRE

    Scholz, Florian; McManus, James; Mix, Alan C; Hensen, Christian; Schneider, Ralph

    2014-01-01

    In the oceans’ high-nitrate–low-chlorophyll regions, such as the Peru/Humboldt Current system and the adjacent eastern equatorial Pacific1, primary productivity is limited by the micronutrient iron. Within the Peruvian upwelling area, bioavailable iron is released from the reducing continental margin sediments2. The magnitude of this seafloor source could change with fluctuations in the extension or intensity of the oxygen minimum zones3, 4. Here we show that measurements of molybdenum, urani...

  20. Phylogenetic diversity and biological activity of actinobacteria isolated from the Chukchi Shelf marine sediments in the Arctic Ocean.

    Science.gov (United States)

    Yuan, Meng; Yu, Yong; Li, Hui-Rong; Dong, Ning; Zhang, Xiao-Hua

    2014-03-06

    Marine environments are a rich source of Actinobacteria and have the potential to produce a wide variety of biologically active secondary metabolites. In this study, we used four selective isolation media to culture Actinobacteria from the sediments collected from the Chukchi Shelf in the Arctic Ocean. A total of 73 actinobacterial strains were isolated. Based on repetitive DNA fingerprinting analysis, we selected 30 representatives for partial characterization according to their phylogenetic diversity, antimicrobial activities and secondary-metabolite biosynthesis genes. Results from the 16S rRNA gene sequence analysis indicated that the 30 strains could be sorted into 18 phylotypes belonging to 14 different genera: Agrococcus, Arsenicicoccus, Arthrobacter, Brevibacterium, Citricoccus, Janibacter, Kocuria, Microbacterium, Microlunatus, Nocardioides, Nocardiopsis, Saccharopolyspora, Salinibacterium and Streptomyces. To our knowledge, this paper is the first report on the isolation of Microlunatus genus members from marine habitats. Of the 30 isolates, 11 strains exhibited antibacterial and/or antifungal activity, seven of which have activities against Bacillus subtilis and Candida albicans. All 30 strains have at least two biosynthetic genes, one-third of which possess more than four biosynthetic genes. This study demonstrates the significant diversity of Actinobacteria in the Chukchi Shelf sediment and their potential for producing biologically active compounds and novel material for genetic manipulation or combinatorial biosynthesis.

  1. Phylogenetic Diversity and Biological Activity of Actinobacteria Isolated from the Chukchi Shelf Marine Sediments in the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Meng Yuan

    2014-03-01

    Full Text Available Marine environments are a rich source of Actinobacteria and have the potential to produce a wide variety of biologically active secondary metabolites. In this study, we used four selective isolation media to culture Actinobacteria from the sediments collected from the Chukchi Shelf in the Arctic Ocean. A total of 73 actinobacterial strains were isolated. Based on repetitive DNA fingerprinting analysis, we selected 30 representatives for partial characterization according to their phylogenetic diversity, antimicrobial activities and secondary-metabolite biosynthesis genes. Results from the 16S rRNA gene sequence analysis indicated that the 30 strains could be sorted into 18 phylotypes belonging to 14 different genera: Agrococcus, Arsenicicoccus, Arthrobacter, Brevibacterium, Citricoccus, Janibacter, Kocuria, Microbacterium, Microlunatus, Nocardioides, Nocardiopsis, Saccharopolyspora, Salinibacterium and Streptomyces. To our knowledge, this paper is the first report on the isolation of Microlunatus genus members from marine habitats. Of the 30 isolates, 11 strains exhibited antibacterial and/or antifungal activity, seven of which have activities against Bacillus subtilis and Candida albicans. All 30 strains have at least two biosynthetic genes, one-third of which possess more than four biosynthetic genes. This study demonstrates the significant diversity of Actinobacteria in the Chukchi Shelf sediment and their potential for producing biologically active compounds and novel material for genetic manipulation or combinatorial biosynthesis.

  2. Biogeographical distribution and diversity of microbes in methane hydrate-bearing deep marine sediments, on the Pacific Ocean Margin

    DEFF Research Database (Denmark)

    Inagaki, F.; Nunoura, T.; Nakagawa, S.

    2006-01-01

    The deep subseafloor biosphere is among the least-understood habitats on Earth, even though the huge microbial biomass therein plays an important role for potential long-term controls on global biogeochemical cycles. We report here the vertical and geographical distribution of microbes and their ......The deep subseafloor biosphere is among the least-understood habitats on Earth, even though the huge microbial biomass therein plays an important role for potential long-term controls on global biogeochemical cycles. We report here the vertical and geographical distribution of microbes...... in prokaryotic distribution patterns in sediments with or without methane hydrates, we studied > 2,800 clones possessing partial sequences (400-500 bp) of the 16S rRNA gene and 348 representative clone sequences (approximate to 1 kbp) from the two geographically separated subseafloor environments. Archaea...... of the JS1 group, Planctomycetes, and Chloroflexi. Results from cluster and principal component analyses, which include previously reported data from the West and East Pacific Margins, suggest that, For these locations in the Pacific Ocean, prokaryotic communities from methane hydrate-bearing sediment cores...

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

    Science.gov (United States)

    Bridoux, Maxime C.; Ingalls, Anitra E.

    2010-07-01

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

  4. Quantitative and phylogenetic study of the Deep Sea Archaeal Group in sediments of the arctic mid-ocean spreading ridge

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    Steffen Leth eJørgensen

    2013-10-01

    Full Text Available In marine sediments archaea often constitute a considerable part of the microbial community, of which the Deep Sea Archaeal Group (DSAG is one of the most predominant. Despite their high abundance no members from this archaeal group have so far been characterized and thus their metabolism is unknown. Here we show that the relative abundance of DSAG marker genes can be correlated with geochemical parameters, allowing prediction of both the potential electron donors and acceptors of these organisms. We estimated the abundance of 16S rRNA genes from Archaea, Bacteria and DSAG in 52 sediment horizons from two cores collected at the slow-spreading Arctic Mid-Ocean Ridge, using qPCR. The results indicate that members of the DSAG make up the entire archaeal population in certain horizons and constitute up to ~ 50% of the total microbial community. The quantitative data were correlated to 30 different geophysical and geochemical parameters obtained from the same sediment horizons. We observed a significant correlation between the relative abundance of DSAG 16S rRNA genes and the content of organic carbon (p < 0.0001. Further, significant co-variation with iron oxide, and dissolved iron and manganese (all p < 0.0000, indicated a direct or indirect link to iron and manganese cycling. Neither of these parameters correlated with the relative abundance of archaeal or bacterial 16S rRNA genes, nor did any other major electron donor or acceptor measured. Phylogenetic analysis of DSAG 16S rRNA gene sequences reveals three monophyletic lineages with no apparent habitat-specific distribution. In this study we support the hypothesis that members of the DSAG are tightly linked to the content of organic carbon and directly or indirectly involved in the cycling of iron and/or manganese compounds. Further, we provide a molecular tool to assess their abundance in environmental samples and enrichment cultures.

  5. Applying machine learning to global surface ocean and seabed data to reveal the controls on the distribution of deep-sea sediments

    Science.gov (United States)

    Dutkiewicz, Adriana; Müller, Dietmar; O'Callaghan, Simon

    2017-04-01

    World's ocean basins contain a rich and nearly continuous record of environmental fluctuations preserved as different types of deep-sea sediments. The sediments represent the largest carbon sink on Earth and its largest geological deposit. Knowing the controls on the distribution of these sediments is essential for understanding the history of ocean-climate dynamics, including changes in sea-level and ocean circulation, as well as biological perturbations. Indeed, the bulk of deep-sea sediments comprises the remains of planktonic organisms that originate in the photic zone of the global ocean implying a strong connection between the seafloor and the sea surface. Machine-learning techniques are perfectly suited to unravelling these controls as they are able to handle large sets of spatial data and they often outperform traditional spatial analysis approaches. Using a support vector machine algorithm we recently created the first digital map of seafloor lithologies (Dutkiewicz et al., 2015) based on 14,400 surface samples. This map reveals significant deviations in distribution of deep-sea lithologies from hitherto hand-drawn maps based on far fewer data points. It also allows us to explore quantitatively, for the first time, the relationship between oceanographic parameters at the sea surface and lithologies on the seafloor. We subsequently coupled this global point sample dataset of 14,400 seafloor lithologies to bathymetry and oceanographic grids (sea-surface temperature, salinity, dissolved oxygen and dissolved inorganic nutrients) and applied a probabilistic Gaussian process classifier in an exhaustive combinatorial fashion (Dutkiewicz et al., 2016). We focused on five major lithologies (calcareous sediment, diatom ooze, radiolarian ooze, clay and lithogenous sediment) and used a computationally intensive five-fold cross-validation, withholding 20% of the data at each iteration, to assess the predictive performance of the machine learning method. We find that

  6. Growth rate and size effect on carbon isotopic fractionation in diatom-bound organic matter in recent Southern Ocean sediments

    Science.gov (United States)

    Stoll, Heather M.; Mendez-Vicente, Ana; Abrevaya, Lorena; Anderson, Robert F.; Rigual-Hernández, Andrés S.; Gonzalez-Lemos, Saul

    2017-01-01

    Carbon isotopic fractionation during photosynthesis (εp) is used to reconstruct past CO2 and phytoplankton growth rates, typically by measuring the δ13C of biomarkers produced by coccolithophorids. However, organic molecules bound within diatom frustules represent another phase for measurement of δ13C and offer the opportunity to obtain εp for specific diatom sizes and geometries. Here, from core top sediments covering a strong productivity gradient in the Southern Ocean, we present determinations of δ13C and εp from frustule-bound organic matter from a fine opal fraction dominated by pennate diatoms and a coarse opal fraction dominated by larger centric diatoms. The δ13C of the pennate diatom fraction is typically 2.8‰ more positive than that of the centric fraction. Both fractions show a comparable range of 9-10‰ over the core top transect. εp is lowest (6.3‰ in pennate fraction) between the Polar Front (PF) and Southern Antarctic Circumpolar Current Front (SACCF) and increases both to the north and south, with maximum values at greatest distance from the PF (18‰ in the pennate fraction). These spatial changes in εp are too large to arise from the rather modest variation in dissolved CO2 in surface waters across the core top transect. We suggest instead that the maximum εp reflects higher diatom growth rates, and in the case of pennate diatom F. kerguelensis also an increase in the frustule width and volume to surface area ratio. Both processes may result from enhanced Fe supply due to upwelling of circumpolar deep water between the PF and SACCF. Farther south, diatom growth is strongly Fe-limited and farther north it is Fe and Si co-limited. The optima of growth rates between the PF and SACCF appears to be a general feature in all sectors of the Southern Ocean. Such growth rate-induced changes in diatom εp allow us to resolve a 5° northward displacement of the PF during glacial times compared to interglacial times. By estimating CO2 aq in

  7. Variations in Organic Matter Burial and Composition in Sediments from the Indian Ocean Continental Margin Off SW Indonesia (Sumatra - Java - Flores) Since the Last Glacial Maximum

    Science.gov (United States)

    Jennerjahn, T. C.; Gesierich, K.; Schefuß, E.; Mohtadi, M.

    2014-12-01

    Global climate change is a mosaic of regional changes to a large extent determined by region-specific feedbacks between climate and ecosystems. At present the ocean is forming a major sink in the global carbon cycle. Organic matter (OM) storage in sediments displays large regional variations and varied over time during the Quaternary. Upwelling regions are sites of high primary productivity and major depocenters of organic carbon (OC), the least understood of which is the Indian Ocean upwelling off Indonesia. In order to reconstruct the burial and composition of OM during the Late Quaternary, we analyzed five sediment cores from the Indian Ocean continental margin off the Indonesian islands Sumatra to Flores spanning the last 20,000 years (20 kyr). Sediments were analyzed for bulk composition, stable carbon and nitrogen isotopes of OM, amino acids and hexosamines and terrestrial plant wax n-alkanes and their stable carbon isotope composition. Sedimentation rates hardly varied over time in the western part of the transect. They were slightly lower in the East during the Last Glacial Maximum (LGM) and deglaciation, but increased strongly during the Holocene. The amount and composition of OM was similar along the transect with maximum values during the deglaciation and the late Holocene. High biogenic opal covarying with OM content indicates upwelling-induced primary productivity dominated by diatoms to be a major control of OM burial in sediments in the East during the past 20 kyr. The content of labile OM was low throughout the transect during the LGM and increased during the late Holocene. The increase was stronger and the OM less degraded in the East than in the West indicating that continental margin sediments off Java and Flores were the major depocenter of OC burial along the Indian Ocean margin off SW Indonesia. Temporal variations probably resulted from changes in upwelling intensity and terrestrial inputs driven by variations in monsoon strength.

  8. Hidráulica do escoamento e transporte de sedimentos em sulcos em solo franco-argilo-arenoso Flow hydraulics and sediment transport in rills of a sandy clay loam soil

    Directory of Open Access Journals (Sweden)

    José Ramon Barros Cantalice

    2005-07-01

    capacity to deform the rill and alter flow hydraulics, responsible for rill formation dynamics. The objective of this study was to evaluate flow hydraulic conditions that can provide important information on erosion relationships, soil erodibility and sediment transport in furrows of a recently-tilled Palleudult. Rills were pre-formed in a sandy clay loam soil with an average slope of 0.067 m m-1. Simulated rainfall with an intensity of 74 mm h-1 was applied during 80 min, while rainfall and extra inflows of 0, 10, 20, 30, 40, and 50 L min-1 were jointly applied for the last 20 min of each run in the rill. Results indicated that the rill flow regime varied from transitional subcritical to turbulent subcritical. The rill erosion detachment rates were linear to shear stress. Rill erodibility (Kr was 0.0024 kg-1 s-1 N and critical shear stress (tauc was 2.75 Pa. Two functions to predict sediment transport based on stream power explained 53% of data variability, which indicates the inherent difficulty of predicting solid transport through shallow flows on eroding agricultural lands, and the physical and mineralogical diversity of particles and aggregates of the studied soil.

  9. Testing of pressurised cores containing gas hydrate from deep ocean sediments

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, C.; Kingston, E.; Priest, J. [Southampton Univ., Highfield, Southampton (United Kingdom). School of Civil Engineering and the Environment; Schultheiss, P. [Geotek Ltd., Daventry, Northamptonshire (United Kingdom)]|[Indian National Gas Hydrate Program Expedition 01, New Delhi (India)

    2008-07-01

    The geotechnical properties of hydrate-bearing sediments were investigated given their importance in predicting the stability of wellbores drilled in hydrate bearing sediments. The properties can also be used to assess the potential for submarine slope instability during exploration or development activity or environmental change. This paper reported on a program of laboratory testing conducted on samples obtained using the hydrate autoclave coring equipment (HYACE) pressurized core barrel system, received at Southampton University following the Indian National Gas Hydrate Program (NGHP) 01 Expedition. The paper described the techniques used at Southampton University, the difficulties encountered, and the results obtained from geotechnical testing of these samples. The program involved a number of stages of testing, including initial appraisal of the geometry, disturbance and hydrate content of the frozen cores using computerized tomography scanning; creation of a photographic record of the frozen cores following their removal from plastic liners; identification of different sections and masses of core to be used in subsequent testing; testing of the best preserved core in the GHRC; selection of small sub-samples for moisture content, organic content and salinity testing; unfreezing of core, and collection of dissociating gas; imaging of subsamples using scanning electron microscopy; particle size distribution (PSD) testing of subsamples; analysis of subsamples for moisture content, salinity and organic content; and a combination of samples to provide sufficient mass for subsequent geotechnical testing. Other stages that were discussed in the paper included a geotechnical description of the sediment; plasticity testing at as received salinity; unconsolidated undrained triaxial shear strength testing at as-received salinity; washing to remove salts; and determination of plasticity with zero salinity pore fluid. The results of the geotechnical testing were reported

  10. Directional analysis of the storm surge from Hurricane Sandy 2012, with applications to Charleston, New Orleans, and the Philippines.

    Directory of Open Access Journals (Sweden)

    Carl Drews

    Full Text Available Hurricane Sandy in late October 2012 drove before it a storm surge that rose to 4.28 meters above mean lower low water at The Battery in lower Manhattan, and flooded the Hugh L. Carey automobile tunnel between Brooklyn and The Battery. This study examines the surge event in New York Harbor using the Weather Research and Forecasting (WRF atmospheric model and the Coupled-Ocean-Atmosphere-Wave- Sediment Transport/Regional Ocean Modeling System (COAWST/ROMS. We present a new technique using directional analysis to calculate and display maps of a coastline's potential for storm surge; these maps are constructed from wind fields blowing from eight fixed compass directions. This analysis approximates the surge observed during Hurricane Sandy. The directional analysis is then applied to surge events at Charleston, South Carolina, New Orleans, Louisiana, and Tacloban City, the Philippines. Emergency managers could use these directional maps to prepare their cities for an approaching storm, on planning horizons from days to years.

  11. Directional analysis of the storm surge from Hurricane Sandy 2012, with applications to Charleston, New Orleans, and the Philippines.

    Science.gov (United States)

    Drews, Carl; Galarneau, Thomas J

    2015-01-01

    Hurricane Sandy in late October 2012 drove before it a storm surge that rose to 4.28 meters above mean lower low water at The Battery in lower Manhattan, and flooded the Hugh L. Carey automobile tunnel between Brooklyn and The Battery. This study examines the surge event in New York Harbor using the Weather Research and Forecasting (WRF) atmospheric model and the Coupled-Ocean-Atmosphere-Wave- Sediment Transport/Regional Ocean Modeling System (COAWST/ROMS). We present a new technique using directional analysis to calculate and display maps of a coastline's potential for storm surge; these maps are constructed from wind fields blowing from eight fixed compass directions. This analysis approximates the surge observed during Hurricane Sandy. The directional analysis is then applied to surge events at Charleston, South Carolina, New Orleans, Louisiana, and Tacloban City, the Philippines. Emergency managers could use these directional maps to prepare their cities for an approaching storm, on planning horizons from days to years.

  12. Organic carbon and nitrogen isotopes in surface sediments from the western Arctic Ocean and their implications for sedimentary environments

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhihua; SHI Xuefa; CAI Deling; HAN Yibing; YANG Zuosheng

    2006-01-01

    Surface sediments from the Chukchi Sea and adjacent arctic deep sea were investigated for organic carbon and nitrogen isotopes (in δ13Corg and δ15Norg) as well as biogenic silica (BSiO2). δ13Corg and δ15Norg values of surface sediments in the study area fall between the end-member values of marine and terrestrial organic matter from the surrounding lands and seas, their variations reflect the changes of marine productivity and terrestrial supply in the study area. BSiO2 shows a similar distribution pattern with δ13Corg and δ15Norg, and can be used as an indicator of marine productivity. In the central-west Chukchi Sea and the Chukchi Rise, sediments have higher δ13Corg, δ15Norg and BSiO2 values, indicating the region has high marine productivity influenced by the nutrient-rich branches of the Pacific waters. In the coastal zone off northwestern Alaska, δ13Corg and δ15Norg values become lighter, indicating a weakening marine productivity and an increasing terrigenous supply due to the effects of the least nutrient-rich branch of the Pacific waters. In the north and the northeast of the study area (including the Chukchi Plateau, the Canada Basin and the Beaufort shelf), δ13Corg, δ15Norg and BSiO2 have the lowest values, and the terrigenous organic matter becomes dominant in surface sediments because this region has the longest ice-covered duration, the least nutrient-rich seawater and the increasing supply of terrestrial materials from the Mackenzie River and the northern Alaska under the action of the clockwise Beaufort gyre. Because the subarctic Pacific waters are continuously discharged into the central basin of the Arctic Ocean through the study area, the nutrient pool in the Chukchi Sea can be considered as a typical open system, the ratio of δ15N to BSiO2 content show some tracers that the level of nutrient utilization is contrary to nutrient supply and marine productivity formed in seawater.

  13. Distributions of the C37:4 alkenone in the water column, surface sediments and sediment cores of the northern high latitude oceans: implications for palaeoceanography

    Science.gov (United States)

    Bendle, J. A.; Rosell-Melé, A.; Ziveri, P.

    2003-04-01

    Unlike the di- and tri-unsaturated C37 alkenones, C37:4 is rare outside of polar- sub polar waters and the temperature response is less certain. In the northern latitudes increasing values of %C37:4 are coincident with increasing scatter in the relationship of UK37' to SST, moreover, in some studies %C37:4 measurements have demonstrated a closer correlation with SSS than with SST (Rosell-Melé, 1998; Rosell-Melé et al., In press; Sicre et al., 2002). Therefore it has been suggested that %C37:4 may be used as a guide to the reliable limits of the UK37' index and moreover, that %C37:4 may have potential as a palaeo-salinity proxy. However, other studies have found no discernable relationship of %C37:4 to SST or SSS on a global scale (Sikes &Sicre, 2001). To investigate further the relationship between the C37:4 alkenone and sea surface variables we have conducted analysis of a large number of water and sediment samples from the Nordic and Barents seas. We report the highest values of %C37:4 yet measured in the open ocean (up to 72%). The data shows a strong trend towards higher values of %C37:4 at locations with a greater input of low salinity, cold polar water. This suggests that %C37:4 may have potential as palaeoceanographic indicator for the presence of polar water masses. The source of this polar water C37:4 is intriguing given that Emiliania huxleyi is rare in polar waters and the more common polar coccolithophore, Coccolithus pelagicus is not known to produce alkenones. Therefore, we also report data investigating the relationship of C37:4 to standing stocks of coccolithophores in sea surface filters. ROSELL-MELÉ, A. (1998) Interhemispheric appraisal of the value of alkenone indices as temperature and salinity proxies in high-latitude locations. Paleoceanography, 13(6), 694-703. ROSELL-MELÉ, A., JANSEN, E. &WEINELT, M. (In press) Appraisal of a molecular approach to infer variations in surface ocean freshwater inputs into the North Atlantic during the last

  14. IODP workshop: developing scientific drilling proposals for the Argentina Passive Volcanic Continental Margin (APVCM) - basin evolution, deep biosphere, hydrates, sediment dynamics and ocean evolution

    Science.gov (United States)

    Flood, Roger D.; Violante, Roberto A.; Gorgas, Thomas; Schwarz, Ernesto; Grützner, Jens; Uenzelmann-Neben, Gabriele; Hernández-Molina, F. Javier; Biddle, Jennifer; St-Onge, Guillaume; Workshop Participants, Apvcm

    2017-05-01

    The Argentine margin contains important sedimentological, paleontological and chemical records of regional and local tectonic evolution, sea level, climate evolution and ocean circulation since the opening of the South Atlantic in the Late Jurassic-Early Cretaceous as well as the present-day results of post-depositional chemical and biological alteration. Despite its important location, which underlies the exchange of southern- and northern-sourced water masses, the Argentine margin has not been investigated in detail using scientific drilling techniques, perhaps because the margin has the reputation of being erosional. However, a number of papers published since 2009 have reported new high-resolution and/or multichannel seismic surveys, often combined with multi-beam bathymetric data, which show the common occurrence of layered sediments and prominent sediment drifts on the Argentine and adjacent Uruguayan margins. There has also been significant progress in studying the climatic records in surficial and near-surface sediments recovered in sediment cores from the Argentine margin. Encouraged by these recent results, our 3.5-day IODP (International Ocean Discovery Program) workshop in Buenos Aires (8-11 September 2015) focused on opportunities for scientific drilling on the Atlantic margin of Argentina, which lies beneath a key portion of the global ocean conveyor belt of thermohaline circulation. Significant opportunities exist to study the tectonic evolution, paleoceanography and stratigraphy, sedimentology, and biosphere and geochemistry of this margin.

  15. Rebuilding natural coastlines after sediment mining: the example of the Brittany coasts (English Channel and Atlantic Ocean).

    Science.gov (United States)

    Regnauld, Herve

    2016-04-01

    Rebuilding natural coastlines after sediment mining: the example of the Brittany coasts (English Channel and Atlantic Ocean). H.Regnauld (1) , J.N. Proust (2) and H.Mahmoud (1) (1) University of Rennes 2, (2) CNRS-University of Rennes 1, France A large part of the coasts of Brittany (western France) have been very heavily impacted by sand mining for the building of military equipments and of a large tidal power station. In some places more then 90 % of the sediment has been extracted during the late 40ies up to the 60ies. The mined site were all sink sites, were sediment had been accumulating for centuries. After the sand and or gravel extraction was stopped the coastal sites were largely used for tourism and most of the eroded dune fields were turned into car parks. Storms produced large floods inland as most of the gravel or sand barrier didn't exist any more. Some local outcrops of inherited Holocene periglacial material with archaeological remains were eroded, some disappeared. During the 80ies a complete shift in planning policies took place and these sites were progressively changed into nature preserves. The aim was to make them behave in a "natural" way again. The "natural" behaviour was intended in a very precise way: barriers should be able to withstand storms again and to protect inland fields from floods. In order to allow for dune re building wooden fences were erected and marram grass was artificially planted. As, from a sedimentological point of view, these sites were sink sites, accumulation was rather rapid (up to 0.25m a year behind wooden fences) and new barrier began to build. The only problem is that they did not always build-up exactly in the same place or with the same material. Some parts of the coasts were left "unprotected" by these new barriers, ancient exposed sites became protected. Today the system as a whole may be considered as having been able to reach some level of equilibrium with the average wave conditions. It has been able to

  16. Modeling Sediment Bypassing around Rocky Headlands

    Science.gov (United States)

    George, D. A.; Largier, J. L.; Pasternack, G. B.; Erikson, L. H.; Storlazzi, C. D.; Barnard, P.

    2016-12-01

    Sediment bypassing rocky headlands remains understudied despite the importance of characterizing littoral processes and sediment budgets for erosion abatement, climate change adaptation, and beach management. This study was developed to identify controlling factors on and the mechanisms supporting sediment bypassing. Sediment flux around four idealized rocky headlands was investigated using the hydrodynamic model Delft3D and spectral wave model SWAN. The experimental design involved 120 simulations to explore the influence of headland morphology, substrate composition, sediment grain size, and oceanographic forcing. Headlands represented sizes and shapes found in natural settings, grain sizes ranged from fine to medium sand, and substrates from sandy beds to offshore bedrock reefs. The oceanography included a constructed representative tide, an alongshore background current, and four wave conditions derived from observational records in the eastern Pacific Ocean. A bypassing ratio was developed for alongshore flux between upstream and downstream cross-shore transects to determine the degree of blockage by a headland. Results showed that northwesterly oblique large waves (Hs = 7 m, Tp = 16 s) generated the most flux around headlands, whereas directly incident waves blocked flux across a headland apex. The headland shape heavily influenced the sediment fate by changing the relative angle between the shoreline and the incident waves. The bypassing ratio characterized each headland's capacity to allow alongshore flux under different wave conditions. All headlands may allow flux, although larger ones block sediment more effectively, promoting their ability to be littoral cell boundaries compared to smaller headlands. The controlling factors on sediment bypassing were determined to be wave angle, shape and size of the headland, and sediment grain size. This novel numerical modeling study advances headland modeling from the generic realm to broadly applicable classes of

  17. Exopolysaccharide production by a marine Pseudoalteromonas sp. strain isolated from Madeira Archipelago ocean sediments.

    Science.gov (United States)

    Roca, Christophe; Lehmann, Mareen; Torres, Cristiana A V; Baptista, Sílvia; Gaudêncio, Susana P; Freitas, Filomena; Reis, Maria A M

    2016-06-25

    Exopolysaccharides (EPS) are polymers excreted by some microorganisms with interesting properties and used in many industrial applications. A new Pseudoalteromonas sp. strain, MD12-642, was isolated from marine sediments and cultivated in bioreactor in saline culture medium containing glucose as carbon source. Its ability to produce EPS under saline conditions was demonstrated reaching an EPS production of 4.4g/L within 17hours of cultivation, corresponding to a volumetric productivity of 0.25g/Lh, the highest value so far obtained for Pseudoalteromonas sp. strains. The compositional analysis of the EPS revealed the presence of galacturonic acid (41-42mol%), glucuronic acid (25-26mol%), rhamnose (16-22mol%) and glucosamine (12-16mol%) sugar residues. The polymer presents a high molecular weight (above 1000kDa). These results encourage the biotechnological exploitation of strain MD12-642 for the production of valuable EPS with unique composition, using saline by-products/wastes as feedstocks. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. The finding of natural GaN crystals in sediments from the East Pacific Ocean

    Institute of Scientific and Technical Information of China (English)

    CHEN Jing; SHI Xuefa; ZHANG Haiping; Lü Huahua; FU Zhendong

    2006-01-01

    The first finding of natural GaN crystals is reported in sediments from the East Pacific. They are identified by multiple micro-beam techniques such as TEM, EDS and EELS. Detailed examinations show that these GaN crystals are euhedral and authigenic, and belong to the hexagonal system (space group P63mc) with cell parameters: a = b = 0.3186 nm, c = 0.5178 nm. Structure data fit closely with those of the synthetic GaN crystals obtained from high-temperature and high-pressure experiments. Moreover, the nearly perfect euhedral form of the sample excludes the possible synthetic origin of the GaN crystals as artifacts with long transport. The sampling localities are located between the Clarion and Clipperton Fracture Zone in the East Pacific where ongoing hydrothermal activities, deformation, and volcanic eruptions are very intensive. It is suggested that the natural GaN crystals may form at relatively high-temperature and high-pressure conditions in geologic environments that have been affected by intense hydrothermal activities.

  19. Assimilation of sediments embedded in the oceanic arc crust: myth or reality?

    Science.gov (United States)

    Bezard, Rachel; Davidson, Jon P.; Turner, Simon; Macpherson, Colin G.; Lindsay, Jan M.; Boyce, Adrian J.

    2014-06-01

    Arc magmas are commonly assumed to form by melting of sub-arc mantle that has been variably enriched by a component from the subducted slab. Although most magmas that reach the surface are not primitive, the impact of assimilation of the arc crust is often ignored with the consequence that trace element and isotopic compositions are commonly attributed only to varying contributions from different components present in the mantle. This jeopardises the integrity of mass balance recycling calculations. Here we use Sr and O isotope data in minerals from a suite of volcanic rocks from St Lucia, Lesser Antilles arc, to show that assimilation of oceanic arc basement can be significant. Analysis of 87Sr/86Sr in single plagioclase phenocrysts from four Soufrière Volcanic Complex (SVC; St Lucia) hand samples with similar composition (87Sr/86Sr = 0.7089-0.7091) reveals crystal isotopic heterogeneity among hand samples ranging from 0.7083 to 0.7094 with up to 0.0008 difference within a single hand sample. δO18 measurements in the SVC crystals show extreme variation beyond the mantle range with +7.5 to +11.1‰ for plagioclase (n=19), +10.6 to +11.8‰ for quartz (n=10), +9.4 to +9.8‰ for amphibole (n=2) and +9 to +9.5‰ for pyroxene (n=3) while older lavas (Pre-Soufriere Volcanic Complex), with less radiogenic whole rock Sr composition (87Sr/86Sr = 0.7041-0.7062) display values closer to mantle range: +6.4 to +7.9‰ for plagioclase (n=4) and +6 to +6.8‰ for pyroxene (n=5). We argue that the 87Sr/86Sr isotope disequilibrium and extreme δO18 values provide compelling evidence for assimilation of material located within the arc crust. Positive correlations between mineral δO18 and whole rock 87Sr/86Sr, 143Nd/144Nd and 206,207,208Pb/204Pb shows that assimilation seems to be responsible not only for the isotopic heterogeneity observed in St Lucia but also in the whole Lesser Antilles since St Lucia encompasses almost the whole-arc range of isotopic compositions. This

  20. Influence of permeability on hydrothermal circulation in the sediment-buried oceanic crust

    Institute of Scientific and Technical Information of China (English)

    WANG Xingtao; ZHAI Shikui; MENG Fanshun; LI Huaiming; YU Zenghui; SUN Ge; XUE Gang

    2006-01-01

    Hydrothermal convection in the upper oceanic crust has been inferred to be a common and important process. Under the simplified conditions of planar boundaries, permeability provides a strong constraint on the pattern of circulation, the dimensions of convective cells and flow field of hydrothermal circulation. By applying an advanced numerical modeling method, to our knowledge, it is the first time to investigate convection as it is influenced by different strata permeability structures,formational anisotropy, fracture zone and cooling intrusion. The simplified geological model is composed of 3 layers, sedimentary layer, high permeable basement layer and low permeable basement layer from top to bottom. When permeability in high permeable layer is 10 times larger than that in sedimentary layer, convection occurs in high permeable layer. The pattern of hydrothermal circulation and flow velocity of hydrothermal fluid are strongly influenced by strata permeability structures,changes of permeability in high permeable basement layer, fracture zone and cooling intrusion.However, formational anisotropy relatively exerts weak influence on hydrothermal circulation, with the ratio up to 1.5 of vertical permeability to lateral permeability in high permeable layer. Fracture zone existing in basement is the most important factor affecting the circulation field. The effects of a local intrusion are limited to convection intensity above the intrusion and have little impact on the fluid flow on a regional scale. As the result of numerical modelling, key factors affecting the hydrothermal circulation are good permeable zone and long-term heat source, not including fluid source.

  1. Tsunami characteristics and formation potential of sandy tsunami deposit in Sanriku Coast: implications from numerical modeling

    Science.gov (United States)

    Sugawara, D.; Haraguchi, T.; Takahashi, T.

    2013-12-01

    Geological investigation of paleotsunami deposit is crucial for knowing the history and magnitude of tsunami events in the past. Among various kinds of grain sizes, sandy tsunami deposit has been best investigated by previous studies, because of its potential for identification in the sedimentary column. Many sandy tsunami deposits have been found from coastal plains, which have sandy beach and low-lying wetlands. However, sandy tsunami deposits in narrow valleys at rocky ria coast have rarely been found. It may be presumed that formation potential of sandy tsunami layer in the rocky coasts is generally lower than coastal plains, because of the absence of sandy beach, tsunami run-up on steeper slope and stronger return flow. In this presentation, characteristics of the 2011 Tohoku-oki earthquake tsunami in Sanriku Coast, a continuous rocky ria coast located in the northeast Japan, is investigated based on numerical modeling. In addition, the formation potential of sandy tsunami deposit is also investigated based on numerical modeling of sediment transport. Preliminary result of tsunami hydrodynamics showed that the waveform and amplification of the tsunami are clearly affected by the local bathymetry, which is associated with submerged topography formed during the last glacial stage. Although the tsunami height in the offshore of each bay is around 8.0 m, the tsunami height at the bay head was increased in different way. The amplification factor at the bay head was typically 2.0 among most of V-shaped narrow embayments; meanwhile the amplification factor is much lower than 1.0 at some cases. The preliminary result of the modeling of sediment transport predicted huge amount of sediments may be suspended into the water column, given that sandy deposit is available there. Massive erosion and deposition of sea bottom sediments may commonly take place in the bays. However, formation of onshore tsunami deposit differs from each other. Whether the suspended sediments

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

    Science.gov (United States)

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

    2014-05-01

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

  3. Impacts of ocean acidification on the carbonate system at the sediment-water interface: a case-study in the NW Mediterranean Sea

    Science.gov (United States)

    Rassmann, Jens; Lansard, Bruno; Gazeau, Frédéric; Grenz, Christian; Alliouane, Samir; Petit, Franck; Pozzato, Lara; Bombled, Bruno; Rabouille, Christophe

    2016-04-01

    According to common predictions, carbon dioxide (CO2) uptake from the atmosphere into the oceans will decrease the average pH of seawater by 0.06-0.32 pH units by 2100. Ocean acidification alters chemical equilibria in seawater and thus potentially impacts marine ecosystem structure and functioning. Shelf regions play a key role for an important fraction of marine life and represent an important part of the global carbon cycle. Due to shallow water depth, chemistry in the water column is strongly coupled with biogeochemistry in the sediments. The aim of the present work is to investigate the impact of ocean acidification on carbonate chemistry. It focuses especially on exchange fluxes of dissolved inorganic carbon (DIC), total alkalinity (TA) and calcium through the sediment-water interface, and its impact on calcium carbonate precipitation or dissolution. For this purpose, sediment cores were incubated ex situ with an open flow of CO2 enriched seawater for 22 days (pHT=7,4, pH reported on the total proton scale). In parallel, sediment cores were incubated as a control with untreated seawater. Incubations took place in a water bath in a dark room with controlled temperature (14°C). Oxygen and pH microprofiles were recorded in the top first mm of the sediment during the whole experiment every 3 days. On 7 occasions, cores were isolated and incubated for 12 hours to estimate fluxes of DIC, TA, oxygen and nutrients. Porewater profiles of DIC, TA, calcium and nutrients were analyzed before and after incubation. On the solid phase, the content of particulate organic carbon, the C:N ratio and its isotopic δ15N and δ13C signature have been determined. In addition, total carbon contents have been measured and X-Ray diffraction was used to look for phase shifts between calcite and aragonite. A net decrease of pH was observed in the upper sediment layers, as well as an increase of DIC and TA pore water concentrations. The acidified cores showed higher DIC and TA exchange

  4. Sandy PMO Disaster Relief Appropriations Act of 2013 Financial Data

    Data.gov (United States)

    Department of Homeland Security — Sandy PMO: Disaster Relief Appropriations Act of 2013 (Sandy Supplemental Bill) Financial Data. This is the Sandy Supplemental Quarterly Financial Datasets that are...

  5. Hurricane Sandy science plan: New York

    Science.gov (United States)

    Ransom, Clarice N.

    2013-01-01

    Hurricane Sandy is a stark reminder of why the Nation must become more resilient to coastal hazards. More than one-half of the U.S. population lives within 50 miles of a coast, and this number is increasing. The U.S. Geological Survey (USGS) is one of the largest providers of geologic and hydrologic information in the world. Federal, State, and local partners depend on the USGS science to know how to prepare for hurricane hazards and reduce losses from future hurricanes. The USGS works closely with other bureaus within the Department of the Interior, the Federal Emergency Management Agency, the National Oceanic Atmospheric Administration, the U.S. Army Corps of Engineers, the Environmental Protection Agency, and many State and local agencies to identify their information needs before, during, and after hurricanes.

  6. 2013-2014 U.S. Geological Survey CMGP LiDAR: Post Sandy (New York City)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — TASK NAME: USGS New York CMGP Sandy Lidar 0.7 Meter NPS LIDAR lidar Data Acquisition and Processing Production Task USGS Contract No. G10PC00057 Task Order No....

  7. Fluid composition of the sediment-influenced Loki's Castle vent field at the ultra-slow spreading Arctic Mid-Ocean Ridge

    Science.gov (United States)

    Baumberger, Tamara; Früh-Green, Gretchen L.; Thorseth, Ingunn H.; Lilley, Marvin D.; Hamelin, Cédric; Bernasconi, Stefano M.; Okland, Ingeborg E.; Pedersen, Rolf B.

    2016-08-01

    The hydrothermal vent field Loki's Castle is located in the Mohns-Knipovich bend (73°N) of the ultraslow spreading Arctic Mid-Ocean Ridge (AMOR) close to the Bear Island sediment fan. The hydrothermal field is venting up to 320° C hot black smoker fluids near the summit of an axial volcanic ridge. Even though the active chimneys have grown on a basaltic ridge, geochemical fluid data show a strong sedimentary influence into the hydrothermal circulation at Loki's Castle. Compelling evidence for a sediment input is given by high alkalinity, high concentrations of NH4+, H2, CH4, C2+ hydrocarbons as well as low Mn and Fe contents. The low δ13C values of CO2 and CH4 and the thermogenic isotopic pattern of the C2+ hydrocarbons in the high-temperature vent fluids clearly point to thermal degradation of sedimentary organic matter and illustrate diminution of the natural carbon sequestration in sediments by hydrothermal circulation. Thus, carbon-release to the hydrosphere in Arctic regions is especially relevant in areas where the active Arctic Mid-Ocean Ridge system is in contact with the organic matter rich detrital sediment fans.

  8. Nature and distribution of manganese nodules from three sediment domains of the Central Indian Basin, Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, R.; Mukhopadhyay, R.

    Manganese nodules from the Central Indian Basin (5 degrees-10 degrees S) vary in abundance, morphology, mineralogy, and chemistry with water depth and sediment type. Nodules from the southern region, dominatEd. by siliceous sediment, differ markedly...

  9. Input of Terrestrial Palynomorphs since the Last Deglaciation from Sediments of the Chukchi Sea Shelf, Western Arctic Ocean

    Science.gov (United States)

    Delusina, I.; Kim, S. Y.; Nam, S. I.; Woo, K. S.

    2014-12-01

    We report the palynology of marine sediment core ARA02B/01A-GC from the Western margin of the shallow shelf of the Chukchi Sea in the Arctic, a site which was synchronously influenced by climatic changes during the last deglaciation with those in the Bering Strait. The core contains a rich concentration of continental palynomorphs, even though the coring location is quite a distance from land. The catchment area for the observed palynomorphs includes the territories of both North America (Alaska and North Canada) and Northern Siberia (Chukotka peninsula and Northern East-Siberian coast). Based on this fact, we can reconstruct a common paleoenvironmental history for this location and the Bering Strait during the postglacial interval. We hypothesize that palynomorphs were carried to the sea during low sea-ice coverage intervals by large rivers (Yukon, Mackenzie and Siberian rivers) and were then transferred by oceanic currents. During intervals of extensive sea-ice coverage the source of the palynomorphs was predominantly eroded shelf sediments. The percentage ratio of tree-herb pollen and spores in the palynomorph assemblages shows that favorable conditions for an increase in forest vegetation took place between ~8 and 4 kyr BP, which coincides with maximum freshwater input to the sea. During a climatic optimum at ~5 kyr BP, as inferred from the total dominance of tree and herb pollen, the Chukchi Sea was apparently warmer than today. This represents the maximum ice-free period for the sea. The low sea-ice interval ended ~3 kyr BP, as suggested by a sharp drop in tree pollen, a reduction in fresh water input, and a drop in the concentration of the algae Pediastrum. Our data correlate well with data from marine core HLY0501-5 from the Bering Strait (Polyak et al., 2009) for the interval of 10-8 kyr BP, but shows a divergence since ~4 kyr BP, which may correspond to the beginning of the differentiation of North American and East-Siberian ecosystem zones.

  10. Macroinfauna and sediment data from swash zones of sandy beaches along the SE Gulf of Mexico and SE Florida coast, 2010-2011 in response to the Deepwater Horizon Oil Spill (NODC Accession 0083190)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sampling for macroinfauna from swash zones of beaches along the SE Gulf of Mexico and SE coast of Florida was conducted from May 2010- July 2011. At each site,...

  11. The influence of hypercapnia and the infaunal brittlestar Amphiura filiformis on sediment nutrient flux – will ocean acidification affect nutrient exchange?

    Directory of Open Access Journals (Sweden)

    S. Widdicombe

    2009-10-01

    Full Text Available Rising levels of atmospheric carbon dioxide and the concomitant increased uptake of this by the oceans is resulting in hypercapnia-related reduction of ocean pH. Research focussed on the direct effects of these physicochemical changes on marine invertebrates has begun to improve our understanding of impacts at the level of individual physiologies. However, CO2-related impairment of organisms' contribution to ecological or ecosystem processes has barely been addressed. The burrowing ophiuroid Amphiura filiformis, which has a physiology that makes it susceptible to reduced pH, plays a key role in sediment nutrient cycling by mixing and irrigating the sediment, a process known as bioturbation. Here we investigate the role of A. filiformis in modifying nutrient flux rates across the sediment-water boundary and the impact of CO2- related acidification on this process. A 40 day exposure study was conducted under predicted pH scenarios from the years 2100 (pH 7.7 and 2300 (pH 7.3, plus an additional treatment of pH 6.8. This study demonstrated strong relationships between A. filiformis density and cycling of some nutrients; activity increases the sediment uptake of phosphate and the release of nitrite and nitrate. No relationship between A. filiformis density and the flux of ammonium or silicate were observed. Results also indicated that, within the timescale of this experiment, effects at the individual bioturbator level appear not to translate into reduced ecosystem influence. However, long term survival of key bioturbating species is far from assured and changes in both bioturbation and microbial processes could alter key biogeochemical processes in future, more acidic oceans.

  12. Extensive lake sediment coring survey on Sub-Antarctic Indian Ocean Kerguelen Archipelago (French Austral and Antarctic Lands)

    Science.gov (United States)

    Arnaud, Fabien; Fanget, Bernard; Malet, Emmanuel; Poulenard, Jérôme; Støren, Eivind; Leloup, Anouk; Bakke, Jostein; Sabatier, Pierre

    2016-04-01

    Recent paleo-studies revealed climatic southern high latitude climate evolution patterns that are crucial to understand the global climate evolution(1,2). Among others the strength and north-south shifts of westerlies wind appeared to be a key parameter(3). However, virtually no lands are located south of the 45th South parallel between Southern Georgia (60°W) and New Zealand (170°E) precluding the establishment of paleoclimate records of past westerlies dynamics. Located around 50°S and 70°E, lost in the middle of the sub-Antarctic Indian Ocean, Kerguelen archipelago is a major, geomorphologically complex, land-mass that is covered by hundreds lakes of various sizes. It hence offers a unique opportunity to reconstruct past climate and environment dynamics in a region where virtually nothing is known about it, except the remarkable recent reconstructions based on a Lateglacial peatbog sequence(4). During the 2014-2015 austral summer, a French-Norwegian team led the very first extensive lake sediment coring survey on Kerguelen Archipelago under the umbrella of the PALAS program supported by the French Polar Institute (IPEV). Two main areas were investigated: i) the southwest of the mainland, so-called Golfe du Morbihan, where glaciers are currently absent and ii) the northernmost Kerguelen mainland peninsula so-called Loranchet, where cirque glaciers are still present. This double-target strategy aims at reconstructing various independent indirect records of precipitation (glacier advance, flood dynamics) and wind speed (marine spray chemical species, wind-borne terrigenous input) to tackle the Holocene climate variability. Despite particularly harsh climate conditions and difficult logistics matters, we were able to core 6 lake sediment sites: 5 in Golfe du Morbihan and one in Loranchet peninsula. Among them two sequences taken in the 4km-long Lake Armor using a UWITEC re-entry piston coring system by 20 and 100m water-depth (6 and 7m-long, respectively). One

  13. On Sandy Shores. Teacher's Guide.

    Science.gov (United States)

    Strang, Craig; And Others

    The activities in this guide (for grades 2-4) transport students to the sandy shore, one of the most fascinating ecosystems on the planet. At this ecological juncture a multiplicity of life forms find ways to survive, thrive, and interact with each other. Using a wide variety of learning formats, students explore and deepen their understanding of…

  14. Geochemical fractionation of Ni, Cu and Pb in the deep sea sediments from the Central Indian Ocean Basin: An insight into the mechanism of metal enrichment in sediment

    Digital Repository Service at National Institute of Oceanography (India)

    Sensarma, S.; Chakraborty, P.; Banerjee, R.; Mukhopadhyay, S.

    microns). The procedure has been vividly described by Ramaswamy and Rao (2006). 2.3. Total carbon (TC), inorganic carbon (TIC) and organic carbon (TOC) analysis: The total carbon (TC) content of the studied sediment samples were analyzed in a carbon... and nitrogen elemental analyzer (Thermo Scientific Flash-EA 1112). Precision of the analysis was within ±5%. Total inorganic carbon (TIC) content of the sediments was determined by Coulometer (UIC, Inc-CM5130 acidification module). Analytical grade calcium...

  15. Sediments overlying exhumed continental mantle: a proxy for the morphotectonic evolution of the Ocean Continent Transition in magma-poor rifted margins

    Science.gov (United States)

    Karpoff, A. M.; Manatschal, G.; Bernoulli, D.; Lagabrielle, Y.

    2003-04-01

    Observations from ancient and present-day magma-poor rifted margins in the Alps and Iberia provide compelling evidence that within the ocean-continent transition (OCT) crustal and sub-continental mantle rocks were exhumed along downward-concave faults which were active during final rifting and accommodated high amounts of extension. The faults are overlain by stranded allochthons of continental origin, pillow basalts, and pelagic sediments, i.e. radiolarites and/or pelagic limestones, and hemipelagic shales. Associated with the faults are tectono-sedimentary breccias and various types of clastic sediments, ranging from debris flow deposits to laminated sandstone, and quartz-rich silt- and claystones. Mineralogical studies of the shales, red jaspers, and red cherts overlying mantle rocks in the Alps of eastern Switzerland are typically quartz-rich and contain variable amounts of phyllosilicates (chlorite and/or mica), feldspars, ± calcite, oxides, pyrite, and epidote. Their main geochemical characteristic is the high silica and low iron and manganese content, which contrasts with that of "metalliferous" Fe-Mn-Si-rich sediments overlying oceanic basalts. High Fe, Ba, REE, U/Th values measured in black shales overlying mantle rocks in the proximal OCT point to a strong hydrothermal activity associated with mantle exhumation. The clastic sediments in the OCT show a wide range of compositions related to mantle, continental crust, and/or pelagic contributions. In particular, the fact that these sediments contain abundant material derived from continental basement rocks seems at odds with their occurrence on top of tectonized mantle rocks. However, drilling in the Iberia margin, where tectonized mantle rocks are overlain by sedimentary breccias (e.g. ODP Sites 1068, 1070), shed new light on the observations in the Alps. Based on drill-hole and seismic data, the tectono-sedimentary breccias drilled in the OCT off Iberia may be interpreted to result from a conveyor

  16. Complex, dynamic combination of physical, chemical and nutritional variables controls spatio-temporal variation of sandy beach community structure.

    Science.gov (United States)

    Ortega Cisneros, Kelly; Smit, Albertus J; Laudien, Jürgen; Schoeman, David S

    2011-01-01

    Sandy beach ecological theory states that physical features of the beach control macrobenthic community structure on all but the most dissipative beaches. However, few studies have simultaneously evaluated the relative importance of physical, chemical and biological factors as potential explanatory variables for meso-scale spatio-temporal patterns of intertidal community structure in these systems. Here, we investigate macroinfaunal community structure of a micro-tidal sandy beach that is located on an oligotrophic subtropical coast and is influenced by seasonal estuarine input. We repeatedly sampled biological and environmental variables at a series of beach transects arranged at increasing distances from the estuary mouth. Sampling took place over a period of five months, corresponding with the transition between the dry and wet season. This allowed assessment of biological-physical relationships across chemical and nutritional gradients associated with a range of estuarine inputs. Physical, chemical, and biological response variables, as well as measures of community structure, showed significant spatio-temporal patterns. In general, bivariate relationships between biological and environmental variables were rare and weak. However, multivariate correlation approaches identified a variety of environmental variables (i.e., sampling session, the C∶N ratio of particulate organic matter, dissolved inorganic nutrient concentrations, various size fractions of photopigment concentrations, salinity and, to a lesser extent, beach width and sediment kurtosis) that either alone or combined provided significant explanatory power for spatio-temporal patterns of macroinfaunal community structure. Overall, these results showed that the macrobenthic community on Mtunzini Beach was not structured primarily by physical factors, but instead by a complex and dynamic blend of nutritional, chemical and physical drivers. This emphasises the need to recognise ocean-exposed sandy

  17. Complex, Dynamic Combination of Physical, Chemical and Nutritional Variables Controls Spatio-Temporal Variation of Sandy Beach Community Structure

    Science.gov (United States)

    Ortega Cisneros, Kelly; Smit, Albertus J.; Laudien, Jürgen; Schoeman, David S.

    2011-01-01

    Sandy beach ecological theory states that physical features of the beach control macrobenthic community structure on all but the most dissipative beaches. However, few studies have simultaneously evaluated the relative importance of physical, chemical and biological factors as potential explanatory variables for meso-scale spatio-temporal patterns of intertidal community structure in these systems. Here, we investigate macroinfaunal community structure of a micro-tidal sandy beach that is located on an oligotrophic subtropical coast and is influenced by seasonal estuarine input. We repeatedly sampled biological and environmental variables at a series of beach transects arranged at increasing distances from the estuary mouth. Sampling took place over a period of five months, corresponding with the transition between the dry and wet season. This allowed assessment of biological-physical relationships across chemical and nutritional gradients associated with a range of estuarine inputs. Physical, chemical, and biological response variables, as well as measures of community structure, showed significant spatio-temporal patterns. In general, bivariate relationships between biological and environmental variables were rare and weak. However, multivariate correlation approaches identified a variety of environmental variables (i.e., sampling session, the C∶N ratio of particulate organic matter, dissolved inorganic nutrient concentrations, various size fractions of photopigment concentrations, salinity and, to a lesser extent, beach width and sediment kurtosis) that either alone or combined provided significant explanatory power for spatio-temporal patterns of macroinfaunal community structure. Overall, these results showed that the macrobenthic community on Mtunzini Beach was not structured primarily by physical factors, but instead by a complex and dynamic blend of nutritional, chemical and physical drivers. This emphasises the need to recognise ocean-exposed sandy

  18. Review of estimation of global fluvial sediment discharge to oceans%全球河流入海沙量估算述评

    Institute of Scientific and Technical Information of China (English)

    刘成; 何耘; 陈建国; 史红玲

    2015-01-01

    The amount of global fluvial sediment discharge to the oceans is an important and sensitive indicator, reflecting changes in the operation of the Earth, and has a significant influence on global socio-economic and environmental problems. Global river-to-ocean sediment flux has attracted the attention of many scholars around the world. Due to the lack of reliable and complete fluvial sediment load data, it is difficult to estimate the amount and variation of global fluvial sediment discharge to the oceans. There are large differences and inconsistencies between the values estimated by previous studies. In this paper, typical results obtained from 27 recently published papers in regards to the estimations of the global fluvial sediment discharge to the oceans are reviewed. The investigation shows that there have been large differences between estimates of the amount of global fluvial sediment discharge to the oceans in the early stages of such research, but, with increasingly in-depth examination, the estimated results in recent years have tended to be reasonable, with the amount mostly ranging from 12 to 20 billion tons per year. It is concluded that the amount of fluvial sediment discharge to the oceans before and after human activities can be considered 19 billion tons per year and 13 billion tons per year, respectively.%全球河流入海沙量作为地球系统运行变化的重要而敏感的指标,在一定程度上会对全球社会、经济和环境问题产生重要影响,从而引起国内外研究者的高度关注。针对由于缺乏可靠、完整的河流输沙量数据,很难准确估算全球河流入海沙量的数值及其变化,且已有文献估算值差别很大,缺乏统一认识的问题,收集整理了20世纪50年代至今国内外27篇文献中全球河流入海沙量的估算值,并对近期相关典型研究成果进行述评。调查发现,早期估算的入海沙量数值差异很大,随着人们对这一问题的深

  19. Hurricane Sandy washover deposits on Fire Island, New York

    Science.gov (United States)

    La Selle, SeanPaul M.; Lunghino, Brent D.; Jaffe, Bruce E.; Gelfenbaum, Guy; Costa, Pedro J.M.

    2017-02-16

    Washover deposits on Fire Island, New York, from Hurricane Sandy in 2012 were investigated a year after the storm to document the sedimentary characteristics of hurricane washover features. Sediment data collected in the field includes stratigraphic descriptions and photos from trenches, bulk sediment samples, U-channels, and gouge and push cores. Samples and push cores were further analyzed in the laboratory for grain size, density variations using x-ray computed tomography (CT), and surface microtexture using a scanning electron microscope (SEM). Elevation profiles of washover features were measured using Differential Global Positioning System (DGPS) with Real Time Kinematic processing. The DGPS elevations were compared to lidar (light detection and ranging) data from pre- and post-Sandy surveys to assess the degree to which washover deposit thicknesses changed within the year following deposition. Hurricane Sandy washover deposits as much as 1 meter thick were observed in trenches. Initial results show that the upper parts of the deposits have been reworked significantly in some places by wind, but there are still areas where the deposits are almost entirely intact. Where mostly intact, the washover deposits consist of massive or weakly laminated sand near the base, overlain by more strongly laminated sands.

  20. Detection of hydrocarbons in sandy sediments analyzing velocity and amplitude of electromagnetic pulses (GPR-Ground Penetrating Radar); Deteccao de hidrocarbonetos em sedimentos arenosos analisando velocidade e amplitude dos pulsos eletromagneticos (GPR)

    Energy Technology Data Exchange (ETDEWEB)

    Dourado, Tiago C.; Botelho, Marco A.B. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Centro de Pesquisa em Geofisica e Geologia; Machado, Sandro L.; Amparo, Nelson S. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Lab. de Geotecnia Ambiental - GeoAmb

    2004-07-01

    We estimate a hydrocarbon saturation of sandy soils on the basis of the velocity and amplitude of GPR (Ground Penetrating Radar) electromagnetic signals. We acquire CMP (Common Mid Point) data on a tank filled with clean sand. The tank, which has dimensions 1,0 m x 0,7 m x 0,7 m, has filled with water and diesel oil. The velocity decreases from 15 cm/ns for 3% water saturation to 5 cm/ns for 24% water saturation. The presence of hydrocarbon only causes small velocity variations, from 13 cm/ns to 15 cm/ns in the first case. We also investigate the AVO (amplitude variations with offset) of a dry sand/water-saturated sand interface and compare the results to those of the oil-saturated sand/water-saturated sand interface. These results are further compared to the Fresnel equations after the estimation of the reflection coefficient from the reflection hyperbole. The agreement is excellent, and the methodology can be usual to evaluate the type of saturating fluid and the corresponding saturating level. Future experiments will involve the detection and modeling of the critical and Brewster angles to obtain additional information. (author)

  1. Distributional patterns in an insect community inhabiting a sandy beach of Uruguay

    Science.gov (United States)

    Mourglia, Virginia; González-Vainer, Patricia; Defeo, Omar

    2015-12-01

    Most studies of sandy beach macrofauna have been restricted to semiterrestrial species and do not include insects when providing species richness and abundance estimates. Particularly, spatio-temporal patterns of community structure of the entomofauna inhabiting these ecosystems have been scarcely documented. This study assessed spatio-temporal distributional patterns of the night active entomofauna on a beach-dune system of Uruguay, including variations in species richness, abundance and diversity, and their relationship with environmental factors. A deconstructive taxonomic analysis was also performed, considering richness and abundance patterns separately for the most abundant insect Orders (Hymenoptera and Coleoptera) to better understand the factors which drive their patterns. We found clear temporal and across-shore patterns in the insect community inhabiting a land-ocean interface, which matched spatiotemporal variations in the environment. Abundance and species richness were highest in spring and summer, concurrently with high temperatures and low values of sediment moisture and compaction. Multivariate ordinations showed two well-defined species groups, which separated summer, autumn and spring samples from winter ones. Generalized Linear Models allowed us to describe a clear segregation in space of the most important orders of the insect community, with specific preferences for the terrestrial (Hymenoptera) and beach (Coleoptera) fringes. Hymenoptera preferred the dune zone, characterized by high elevation and low sand moisture and compaction levels, whereas Coleoptera preferred gentle slopes and fine and humid sands of the beach. Our results suggest that beach and dune ecosystems operate as two separate components in regard to their physical and biological features. The high values of species richness and abundance of insects reveal that this group has a more significant ecological role than that originally considered so far in sandy beach ecology.

  2. Barrier island breach evolution: Alongshore transport and bay-ocean pressure gradient interactions

    Science.gov (United States)

    Safak, Ilgar; Warner, John C.; List, Jeffrey H.

    2016-12-01

    Physical processes controlling repeated openings and closures of a barrier island breach between a bay and the open ocean are studied using aerial photographs and atmospheric and hydrodynamic observations. The breach site is located on Pea Island along the Outer Banks, separating Pamlico Sound from the Atlantic Ocean. Wind direction was a major control on the pressure gradients between the bay and the ocean to drive flows that initiate or maintain the breach opening. Alongshore sediment flux was found to be a major contributor to breach closure. During the analysis period from 2011 to 2016, three hurricanes had major impacts on the breach. First, Hurricane Irene opened the breach with wind-driven flow from bay to ocean in August 2011. Hurricane Sandy in October 2012 quadrupled the channel width from pressure gradient flows due to water levels that were first higher on the ocean side and then higher on the bay side. The breach closed sometime in Spring 2013, most likely due to an event associated with strong alongshore sediment flux but minimal ocean-bay pressure gradients. Then, in July 2014, Hurricane Arthur briefly opened the breach again from the bay side, in a similar fashion to Irene. In summary, opening and closure of breaches are shown to follow a dynamic and episodic balance between along-channel pressure gradient driven flows and alongshore sediment fluxes.

  3. Preliminary study on detection sediment contamination in soil affected by the Indian Ocean giant tsunami 2004 in Aceh, Indonesia using laser-induced breakdown spectroscopy (LIBS)

    Energy Technology Data Exchange (ETDEWEB)

    Idris, Nasrullah, E-mail: nasrullah.idris@unsyiah.ac.id [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Jl. Syech Abdurrauf No. 3 Darussalam, 23111 Banda Aceh, Aceh (Indonesia); Ramli, Muliadi [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Jl. Syech Abdurrauf No. 3 Darussalam, 23111 Banda Aceh, Aceh (Indonesia); Hedwig, Rinda; Lie, Zener Sukra [Department of Computer Engineering, Bina Nusantara University, 9 K. H. Syahdan, Jakarta 14810 (Indonesia); Kurniawan, Koo Hendrik [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630, Jakarta (Indonesia)

    2016-03-11

    This work is intended to asses the capability of LIBS for the detection of the tsunami sediment contamination in soil. LIBS apparatus used in this work consist of a laser system and an optical multichannel analyzer (OMA) system. The soil sample was collected from in Banda Aceh City, Aceh, Indonesia, the most affected region by the giant Indian Ocean tsunami 2004. The laser beam was focused onto surface of the soil pellet using a focusing lens to produce luminous plasma. The experiment was conducted under air as surrounding gas at 1 atmosphere. The emission spectral lines from the plasma were detected by the OMA system. It was found that metal including heavy metals can surely be detected, thus implying the potent of LIBS technique as a fast screening tools of tsunami sediment contamination.

  4. 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

  5. Impact of open-ocean convection on particle fluxes and sediment dynamics in the deep margin of the Gulf of Lions

    Directory of Open Access Journals (Sweden)

    M. Stabholz

    2013-02-01

    Full Text Available The deep outer margin of the Gulf of Lions and the adjacent basin, in the western Mediterranean Sea, are regularly impacted by open-ocean convection, a major hydrodynamic event responsible for the ventilation of the deep water in the western Mediterranean Basin. However, the impact of open-ocean convection on the flux and transport of particulate matter remains poorly understood. The variability of water mass properties (i.e., temperature and salinity, currents, and particle fluxes were monitored between September 2007 and April 2009 at five instrumented mooring lines deployed between 2050 and 2350-m depth in the deepest continental margin and adjacent basin. Four of the lines followed a NW–SE transect, while the fifth one was located on a sediment wave field to the west. The results of the main, central line SC2350 ("LION" located at 42°02.5′ N, 4°41′ E, at 2350-m depth, show that open-ocean convection reached mid-water depth (≈ 1000-m depth during winter 2007–2008, and reached the seabed (≈ 2350-m depth during winter 2008–2009. Horizontal currents were unusually strong with speeds up to 39 cm s−1 during winter 2008–2009. The measurements at all 5 different locations indicate that mid-depth and near-bottom currents and particle fluxes gave relatively consistent values of similar magnitude across the study area except during winter 2008–2009, when near-bottom fluxes abruptly increased by one to two orders of magnitude. Particulate organic carbon contents, which generally vary between 3 and 5%, were abnormally low (≤ 1% during winter 2008–2009 and approached those observed in surface sediments (≈ 0.6%. Turbidity profiles made in the region demonstrated the existence of a bottom nepheloid layer, several hundred meters thick, and related to the resuspension of bottom sediments. These observations support the view that open-ocean deep convection events in the Gulf of Lions can cause significant remobilization

  6. Impact of open-ocean convection on particle fluxes and sediment dynamics in the deep margin of the Gulf of Lions

    Science.gov (United States)

    Stabholz, M.; Durrieu de Madron, X.; Canals, M.; Khripounoff, A.; Taupier-Letage, I.; Testor, P.; Heussner, S.; Kerhervé, P.; Delsaut, N.; Houpert, L.; Lastras, G.; Dennielou, B.

    2013-02-01

    The deep outer margin of the Gulf of Lions and the adjacent basin, in the western Mediterranean Sea, are regularly impacted by open-ocean convection, a major hydrodynamic event responsible for the ventilation of the deep water in the western Mediterranean Basin. However, the impact of open-ocean convection on the flux and transport of particulate matter remains poorly understood. The variability of water mass properties (i.e., temperature and salinity), currents, and particle fluxes were monitored between September 2007 and April 2009 at five instrumented mooring lines deployed between 2050 and 2350-m depth in the deepest continental margin and adjacent basin. Four of the lines followed a NW-SE transect, while the fifth one was located on a sediment wave field to the west. The results of the main, central line SC2350 ("LION") located at 42°02.5' N, 4°41' E, at 2350-m depth, show that open-ocean convection reached mid-water depth (≍ 1000-m depth) during winter 2007-2008, and reached the seabed (≍ 2350-m depth) during winter 2008-2009. Horizontal currents were unusually strong with speeds up to 39 cm s-1 during winter 2008-2009. The measurements at all 5 different locations indicate that mid-depth and near-bottom currents and particle fluxes gave relatively consistent values of similar magnitude across the study area except during winter 2008-2009, when near-bottom fluxes abruptly increased by one to two orders of magnitude. Particulate organic carbon contents, which generally vary between 3 and 5%, were abnormally low (≤ 1%) during winter 2008-2009 and approached those observed in surface sediments (≍ 0.6%). Turbidity profiles made in the region demonstrated the existence of a bottom nepheloid layer, several hundred meters thick, and related to the resuspension of bottom sediments. These observations support the view that open-ocean deep convection events in the Gulf of Lions can cause significant remobilization of sediments in the deep outer margin and

  7. Pseudoracemization (Biological Accumulation of D-amino Acids) in the Antarctic Cryptoendolithic Microbial Ecosystem, a Model for Oceans, Sediments, and Soils

    Science.gov (United States)

    Sun, H. J.; McDonald, G. D.; McKay, C. P.; Friedmann, I. E.

    2006-12-01

    Amino acids exist in right-handed and left-handed forms, different in that they are mirror images of each other. In organisms, with few exceptions, only left-handed forms are present. In non-living systems, left-handed forms slowly convert, through the physico-chemical process of racemization, into right-handed ones until the two forms reach equilibrium. We found that in microorganisms in Antarctic rocks right-handed amino acids accumulate from bacterial cell walls, through the biological process pseudoracemization. We suggest that the same process is responsible for the fact that large amounts of right-handed amino acids exist in oceans, sediments and soils.

  8. Erosion of soil organic carbon at high latitudes and its delivery to Arctic Ocean sediments: New source to sink insight from radiocarbon dating

    Science.gov (United States)

    Hilton, Robert; Galy, Valier; Gaillardet, Jerome; Dellinger, Mathieu; Bryant, Charlotte; O'Regan, Matt; Grocke, Darren; Coxall, Helen

    2016-04-01

    Soils of the northern high latitudes store carbon over thousands of years and contain almost double the carbon stock of the atmosphere. Erosion processes can mobilise this pre-aged soil organic carbon from the landscape and supply it to rivers. If it escapes degradation during river transport and is delivered to the coastal ocean, this carbon may be sequestered for much longer periods of time (>104 yr) as a geological CO2 sink. Despite this recognition, the erosional flux and fate of particulate organic carbon (POC) in large rivers draining the high latitudes remains poorly constrained. Using radiocarbon activity, we quantify POC source, flux and fate in the Mackenzie River, the main sediment supplier to the Arctic Ocean. When combined with stable carbon isotopes and element ratios, the radiocarbon activity of POC allows us to distinguish inputs of POC from sedimentary rocks and quantify the average age of biospheric POC (from vegetation and soil) transported through the river system. We find that the eroded biospheric POC has resided in the basin for millennia, with a mean radiocarbon age of 5800±800 years. This is much older than large tropical rivers where we have equivalent data (Amazon River, Ganges River), and likely reflects the longer residence time of organic matter in cold, wet, high latitude soils. Based on the measured biospheric POC content and annual sediment flux, we calculate a biospheric POC flux of 2.2 (+1.3/-0.9) TgC yr-1 from the Mackenzie River. This is the largest input of aged organic carbon to the Arctic Ocean, more than the combined POC flux from the Eurasian Rivers. Offshore, we use a marine core to investigate organic carbon burial over the Holocene period. Radiocarbon measurements of bulk organic carbon reveal a significant offset from benthic foraminifera radiocarbon ages throughout the core, which is dependent upon the grain size of the sediments. Organic matter in sediments >63μm are offset from foraminifera by ˜ 6,000 14C years

  9. Oceanic Density Fronts Steering Bottom-Current Induced Sedimentation Deduced from a 50 ka Contourite-Drift Record and Numerical Modeling (off NW Spain)

    Science.gov (United States)

    Hanebuth, T. J. J.; Zhang, W.; Hofmann, A. L.; Lowemark, L. A.; Schwenk, T.

    2015-12-01

    How bottom-near hydrographic and sedimentary processes control the formation of bottom-current related confined deep-sea depocenters remains widely speculative. The geological approach of this study uses a transect of sediment cores and sediment echosounder profiles across a whole contourite system off NW Spain. This "mounded patch"-type contourite drift (18 km long, 20 km wide) with a 150-m deep moat has formed around an 800-m high structural obstacle. Past deposition was characterized by alternating calm and high-energy bottom-flow conditions. Calm conditions (Last Glacial period: 27-17 cal ka BP; late Holocene times: current-influenced deposition of fine-grained sediments (10 µm) over the entire basin. In contrast, waxing-and-waning high-energy conditions (D/O events during Marine Isotope Stage 3; the Deglacial/early Holocene time interval at 17-4 cal ka BP) resulted in coarse grained (70 µm) deposition. Process-based numerical modelling demonstrates that pulse-like oceanic density fronts travelling within the transition zone of two water masses (Labrador Sea Water, Mediterranean Outflow Water) provide a powerful mechanism for contouritic deposition, rather than the core of a water mass itself. These gravity-driven density fronts lead to local re-suspension of sand from the moat and to subsequent upward transport over the crest. Here, the oceanic density fronts produce additional km-scale eddies. These migrating eddies provide an efficient mechanism for further widespread sediment re-distribution. In comparison with paleoceanographic reconstructions, a downward migration or expansion of the Mediterranean Outflow Water by about 300 m led most probably to such temporary contouritic sand deposition. We finally propose a conceptual model to explain how seafloor obstacles redirect and perturbate bottom currents. This model proposes water mass transition zone as an important high-energy medium, for oceanic density fronts to travel. On the respective time scale, the

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

    Science.gov (United States)

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

    2010-12-01

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

  11. Luminescence Dating of Tsunami sediments : Residual Signal Levels in Sediments from the 26th December 2004 Indian Ocean Event in Thailand.

    Science.gov (United States)

    Sanderson, D. C.; Bishop, P.; Hansom, J.; Curry, G.; Chaimanee, N.

    2007-05-01

    Luminescence dating has been applied in the past to several tsunami deposits, notably from Northern Australia, the Scilly Isles, Scotland and Chile. Providing initial signals levels are close to zero, optically stimulated luminescence (OSL) dating is a promising method for dating palaeo-tsunami sediments, and providing an indication of past frequencies of occurrence of at least large scale events. The time resolution available, however, is critically dependent on initial signal levels in zero age deposits. With that in mind we have undertaken a study of sediments deposited in Phang Nga province and Phuket in Thailand by the 26th December 2004 tsunami. Approximately 250 sediment samples were collected from a diverse range of settings early in 2005 and prior to monsoonal disturbance. A newly developed portable OSL reader was used to assist fieldwork by making real- time measurements during the fieldwork period of more than 100 samples. This proved invaluable in confirming that all tsunami deposited material retained measureable luminescence signals, and guiding sampling towards an examination of the underlying factors that influence residual levels. Samples were collected from pre-tsunami ground surfaces, from basal and superficial tsunami deposits, from stratified sediments showing multiple sequences of coarse and fine sediments associated with different parts of the wavetrain, from a series of open and shaded back-beach locations, and from a transect reaching inland for approximately 1 km. Laboratory studies have now been conducted to extend initial screening measurements to all samples, and to perform calibrated analyses of mineral separates from selected samples. The work has confirmed that non-zero initial signal levels are present in all samples. The magnitude of such signals ranges over 4 orders of magnitude apparently controlled by the inherited age of the source sediment being entrained in the tsunami wave prior to redeposition. The lowest residual signal

  12. Implementation of the vortex force formalism in the coupled ocean-atmosphere-wave-sediment transport (COAWST) modeling system for inner shelf and surf zone applications

    Science.gov (United States)

    Kumar, Nirnimesh; Voulgaris, George; Warner, John C.; Olabarrieta, Maitane

    2012-01-01

    The coupled ocean-atmosphere-wave-sediment transport modeling system (COAWST) enables simulations that integrate oceanic, atmospheric, wave and morphological processes in the coastal ocean. Within the modeling system, the three-dimensional ocean circulation module (ROMS) is coupled with the wave generation and propagation model (SWAN) to allow full integration of the effect of waves on circulation and vice versa. The existing wave-current coupling component utilizes a depth dependent radiation stress approach. In here we present a new approach that uses the vortex force formalism. The formulation adopted and the various parameterizations used in the model as well as their numerical implementation are presented in detail. The performance of the new system is examined through the presentation of four test cases. These include obliquely incident waves on a synthetic planar beach and a natural barred beach (DUCK' 94); normal incident waves on a nearshore barred morphology with rip channels; and wave-induced mean flows outside the surf zone at the Martha's Vineyard Coastal Observatory (MVCO).

  13. Occurrence of @iNeogloboquadrina pachyderma@@ new subspecies in the shelf-slope sediments of northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.

    ~'N in the Bay of Bengal. Studies of hydrological conditions in the Indian Ocean reveal that the Subtropical Subsurface Water Mass is traceable as far north as the Gulf of Aden, and the Indian Ocean Deep Bottom Water Mass originating in the deepest...

  14. 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

  15. Analyze of waves dynamic over an intertidal mudflat of a sandy-gravely estuarine beach - Field survey and preliminary modeling approach

    Science.gov (United States)

    Morio, Olivier; Sedrati, Mouncef; Goubert, Evelyne

    2014-05-01

    As well as marine submersion or erosive phenomena, clay-silted sediment in-filling on estuarial and bay beaches are a main issue in these human-attractive areas. Coupled sandy/gravely and clay/silty intertidal areas can be observed in these particular coastal areas, depending of rivers characteristic (discharge of particle, water flow), ocean dynamics (wave exposure, current) and sediments sources. All around the world, sandy/gravely beaches are exposed to punctual or continuous input clay sediments. Vilaine estuary, Bay of Arcachon and Bay of Seine in France, Plymouth Bay in UK and also Wadden Sea in Deutschland are few examples of muddy/sandy coupled or mixed system. The beach of Bétahon (Ambon town, Brittany - France) is located on the external Vilaine estuary and is an example of this issue. This meso-macrotidal intermediate (low tide terrace) beach presents heterogeneous sediments. The upper intertidal zone is composed by sand and gravel and characterized by a steep slope. A very gentle slope characterized the lower part of the beach and is constituted by silt and clay. Clay/sand limit is characterized by a decimetric erosion cliff of mudflat along the beach. In order to understand bed variations and sediment transport of this complex heterogeneous beach, a well understanding of wave dynamic across the beach is necessary. This study focus on wave dynamics over the beach, using field observations and MIKE 21 3D wave numerical model. This paper is a preliminary approach of an upcoming global understanding of this estuarial beach behavior. Swell from deep-sea to near-shore area is modeled over a 100 km² area and real wind, deep sea wave characteristic, river water flow and tidal level are defined as open boundary conditions for the regional model. This last one is based on multiple bathymetric surveys over the last 50 years. Local model, triangular mesh gridded to 5 meters, covering Bétahon beach , is based on topographic and photographic survey of the mudflat

  16. The composition and the source of hydrocarbons in sediments taken from the tectonically active Andaman Backarc Basin, Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Chernova, T.G.; Rao, P.S.; Pikovskii, Yu.I.; Alekseeva, T.A.; Nath, B.N.; Rao, B.R.; Rao, Ch.M.

    or hydrothermal organic matter. Anthropogenic sources in region studied are of minor importance. From the results obtained, it may be deduced that the hydrocarbons in the sediments of the tectonically active part of the Andaman Basin are mainly due...

  17. Denitrification coupled to pyrite oxidation and changes in groundwater quality in a shallow sandy aquifer

    NARCIS (Netherlands)

    Zhang, Y.-C.; Slomp, C.P.; Broers, H.P.; Passier, H.F.; Cappellen, P. van

    2009-01-01

    This study focuses on denitrification in a sandy aquifer using geochemical analyses of both sediment and groundwater, combined with groundwater age dating (3H/3He). The study sites are located underneath cultivated fields and an adjacent forested area at Oostrum, The Netherland

  18. Hard substrate in the deep ocean: How sediment features influence epibenthic megafauna on the eastern Canadian margin

    Science.gov (United States)

    Lacharité, Myriam; Metaxas, Anna

    2017-08-01

    Benthic habitats on deep continental margins (> 1000 m) are now considered heterogeneous - in particular because of the occasional presence of hard substrate in a matrix of sand and mud - influencing the distribution of megafauna which can thrive on both sedimented and rocky substrates. At these depths, optical imagery captured with high-definition cameras to describe megafauna can also describe effectively the fine-scale sediment properties in the immediate vicinity of the fauna. In this study, we determined the relationship between local heterogeneity (10-100 sm) in fine-scale sediment properties and the abundance, composition, and diversity of megafauna along a large depth gradient (1000-3000 m) in a previously-unexplored habitat: the Northeast Fan, which lies downslope of submarine canyons off the Gulf of Maine (northwest Atlantic). Substrate heterogeneity was quantified using a novel approach based on principles of computer vision. This approach proved powerful in detecting gradients in sediment, and sporadic complex features (i.e. large boulders) in an otherwise homogeneous environment because it characterizes sediment properties on a continuous scale. Sediment heterogeneity influenced megafaunal diversity (morphospecies richness and Shannon-Wiener Index) and community composition, with areas of higher substrate complexity generally supported higher diversity. However, patterns in abundance were not influenced by sediment properties, and may be best explained by gradients in food supply. Our study provides a new approach to quantify fine-scale sediment properties and assess their role in shaping megafaunal communities in the deep sea, which should be included into habitat studies given their potential ecological importance.

  19. Radiocarbon dating of mangrove sediments to constrain Holocene relative sea-level change on Zanzibar in the southwest Indian Ocean.

    OpenAIRE

    2015-01-01

    Mangrove sedimentary deposits are sensitive to changes in sea level and can be used to reconstruct mid- to late Holocene sea-level fluctuations in intermediate and far-field locations, distant to the former polar ice sheets. However, they can be difficult to date using 14C because mangrove sediment can contain mixtures of carbon of different ages. The two main potential causes of error are younger mangrove roots penetrating down through the sediment column and bioturbation by burrowing animal...

  20. The oceanic mass balance of copper and zinc isotopes, investigated by analysis of their inputs, and outputs to ferromanganese oxide sediments

    Science.gov (United States)

    Little, S. H.; Vance, D.; Walker-Brown, C.; Landing, W. M.

    2014-01-01

    The oceanic biogeochemical cycles of the transition metals have been eliciting considerable attention for some time. Many of them have isotope systems that are fractionated by key biological and chemical processes so that significant information about such processes may be gleaned from them. However, for many of these nascent isotopic systems we currently know too little of their modern oceanic mass balance, making the application of such systems to the past speculative, at best. Here we investigate the biogeochemical cycling of copper (Cu) and zinc (Zn) isotopes in the ocean. We present estimates for the isotopic composition of Cu and Zn inputs to the oceans based on new data presented here and published data. The bulk isotopic composition of dissolved Cu and Zn in the oceans (δ65Cu ∼+0.9‰, δ66Zn ∼+0.5‰) is in both cases heavier than their respective inputs (at around δ65Cu = +0.6‰ and δ66Zn = +0.3‰, respectively), implying a marine process that fractionates them and a resulting isotopically light sedimentary output. For the better-known molybdenum isotope system this is achieved by sorption to Fe-Mn oxides, and this light isotopic composition is recorded in Fe-Mn crusts. Hence, we present isotopic data for Cu and Zn in three Fe-Mn crusts from the major ocean basins, which yield δ65Cu = 0.44 ± 0.23‰ (mean and 2SD) and δ66Zn = 1.04 ± 0.21‰. Thus for Cu isotopes output to particulate Fe-Mn oxides can explain the heavy isotopic composition of the oceans, while for Zn it cannot. The heavy Zn in Fe-Mn crusts (and in all other authigenic marine sediments measured so far) implies that a missing light sink is still to be located. These observations are some of the first to place constraints on the modern oceanic mass balance of Cu and Zn isotopes.

  1. The Early Shorebird Will Catch Fewer Invertebrates on Trampled Sandy Beaches

    Science.gov (United States)

    Schlacher, Thomas A.; Carracher, Lucy K.; Porch, Nicholas; Connolly, Rod M.; Olds, Andrew D.; Gilby, Ben L.; Ekanayake, Kasun B.; Maslo, Brooke; Weston, Michael A.

    2016-01-01

    Many species of birds breeding on ocean beaches and in coastal dunes are of global conservation concern. Most of these species rely on invertebrates (e.g. insects, small crustaceans) as an irreplaceable food source, foraging primarily around the strandline on the upper beach near the dunes. Sandy beaches are also prime sites for human recreation, which impacts these food resources via negative trampling effects. We quantified acute trampling impacts on assemblages of upper shore invertebrates in a controlled experiment over a range of foot traffic intensities (up to 56 steps per square metre) on a temperate beach in Victoria, Australia. Trampling significantly altered assemblage structure (species composition and density) and was correlated with significant declines in invertebrate abundance and species richness. Trampling effects were strongest for rare species. In heavily trafficked plots the abundance of sand hoppers (Amphipoda), a principal prey item of threatened Hooded Plovers breeding on this beach, was halved. In contrast to the consistently strong effects of trampling, natural habitat attributes (e.g. sediment grain size, compactness) were much less influential predictors. If acute suppression of invertebrates caused by trampling, as demonstrated here, is more widespread on beaches it may constitute a significant threat to endangered vertebrates reliant on these invertebrates. This calls for a re-thinking of conservation actions by considering active management of food resources, possibly through enhancement of wrack or direct augmentation of prey items to breeding territories. PMID:27564550

  2. The Early Shorebird Will Catch Fewer Invertebrates on Trampled Sandy Beaches.

    Science.gov (United States)

    Schlacher, Thomas A; Carracher, Lucy K; Porch, Nicholas; Connolly, Rod M; Olds, Andrew D; Gilby, Ben L; Ekanayake, Kasun B; Maslo, Brooke; Weston, Michael A

    2016-01-01

    Many species of birds breeding on ocean beaches and in coastal dunes are of global conservation concern. Most of these species rely on invertebrates (e.g. insects, small crustaceans) as an irreplaceable food source, foraging primarily around the strandline on the upper beach near the dunes. Sandy beaches are also prime sites for human recreation, which impacts these food resources via negative trampling effects. We quantified acute trampling impacts on assemblages of upper shore invertebrates in a controlled experiment over a range of foot traffic intensities (up to 56 steps per square metre) on a temperate beach in Victoria, Australia. Trampling significantly altered assemblage structure (species composition and density) and was correlated with significant declines in invertebrate abundance and species richness. Trampling effects were strongest for rare species. In heavily trafficked plots the abundance of sand hoppers (Amphipoda), a principal prey item of threatened Hooded Plovers breeding on this beach, was halved. In contrast to the consistently strong effects of trampling, natural habitat attributes (e.g. sediment grain size, compactness) were much less influential predictors. If acute suppression of invertebrates caused by trampling, as demonstrated here, is more widespread on beaches it may constitute a significant threat to endangered vertebrates reliant on these invertebrates. This calls for a re-thinking of conservation actions by considering active management of food resources, possibly through enhancement of wrack or direct augmentation of prey items to breeding territories.

  3. Regional variations in provenance and abundance of ice-rafted clasts in Arctic Ocean sediments: Implications for the configuration of late Quaternary oceanic and atmospheric circulation in the Arctic

    Science.gov (United States)

    Phillips, R.L.; Grantz, A.

    2001-01-01

    The composition and distribution of ice-rafted glacial erratics in late Quaternary sediments define the major current systems of the Arctic Ocean and identify two distinct continental sources for the erratics. In the southern Amerasia basin up to 70% of the erratics are dolostones and limestones (the Amerasia suite) that originated in the carbonate-rich Paleozoic terranes of the Canadian Arctic Islands. These clasts reached the Arctic Ocean in glaciers and were ice-rafted to the core sites in the clockwise Beaufort Gyre. The concentration of erratics decreases northward by 98% along the trend of the gyre from southeastern Canada basin to Makarov basin. The concentration of erratics then triples across the Makarov basin flank of Lomonosov Ridge and siltstone, sandstone and siliceous clasts become dominant in cores from the ridge and the Eurasia basin (the Eurasia suite). The bedrock source for the siltstone and sandstone clasts is uncertain, but bedrock distribution and the distribution of glaciation in northern Eurasia suggest the Taymyr Peninsula-Kara Sea regions. The pattern of clast distribution in the Arctic Ocean sediments and the sharp northward decrease in concentration of clasts of Canadian Arctic Island provenance in the Amerasia basin support the conclusion that the modem circulation pattern of the Arctic Ocean, with the Beaufort Gyre dominant in the Amerasia basin and the Transpolar drift dominant in the Eurasia basin, has controlled both sea-ice and glacial iceberg drift in the Arctic Ocean during interglacial intervals since at least the late Pleistocene. The abruptness of the change in both clast composition and concentration on the Makarov basin flank of Lomonosov Ridge also suggests that the boundary between the Beaufort Gyre and the Transpolar Drift has been relatively stable during interglacials since that time. Because the Beaufort Gyre is wind-driven our data, in conjunction with the westerly directed orientation of sand dunes that formed during

  4. Subsidence of River Delta Systems and Enclosed Basins Caused by Multi-decadal to Millennial Scale Sediment and Ocean Loading

    Science.gov (United States)

    Blom, Ronald G.; Ivins, Erik R.; Klemann, Volker; Dokka, Roy K.; Lohman, Rowena; Fielding, Eric J.

    2010-05-01

    The causes of multi-decadal coastal subsidence that exceed the rate of 20th-21st Century mean sea-level rise are numerous. A host of causal relationships between anthropogenic activity and coastal erosion and subsidence are both compelling and well understood. A short list of these processes should include: fluid extraction, reservoir compaction; fluid-induced motion of shallow growth-faults; decomposition of organic sediments (left in the wake of major water diversion projects) and sediment empoundment and/or diversion. Non-anthropogenic post-glacial sediment loading-induced subsidence has also been demonstrated to be a candidate mechanism that could dominate the GPS-mapped subsidence in the Mississippi-Atchafalaya Rive Delta system (Ivins, Dokka and Blum, GRL, 34, L16303, 2007). More recent changes in sediment load can also have a substantial impact on the active subsidence of the crust and mantle. These can be of both anthropogenic and natural origins. Here we examine, in varying degrees of detail, the world's major delta systems wherein the necessary and sufficient conditions are met that allow sediment plus water load to drive gravitationally-layered, hydrostatically pre-stressed viscoelastic Earth model simulations far enough away from gravitational equilibrium that a detectable geodetic signal in tide-gauges and GPS vertical position would be predicted. Sediment-load-induced subsidence occurs over horizontal length scales, λ, comparable to thickness of the lithosphere: λ ≥ 40-60 km and has amplitudes ranging from of 0.5 to 8 mm/yr (Ivins et al. GRL34, 2007; Syvitski Sustain. Sci., 3, 2008). The cases of the pan-Arctic deltas, the Atchafalya -Mississippi River Delta system, the Yangzte River and Yellow River Deltas of China, the Danube River Delta Plain, and the generally complex postglacial water-sediment loading of the Black Sea and Caspian Sea.

  5. Bathymetric variations in vertical distribution patterns of meiofauna in the surface sediments of the deep Arctic ocean (HAUSGARTEN, Fram strait)

    Science.gov (United States)

    Górska, Barbara; Grzelak, Katarzyna; Kotwicki, Lech; Hasemann, Christiane; Schewe, Ingo; Soltwedel, Thomas; Włodarska-Kowalczuk, Maria

    2014-09-01

    Deep-sea benthic communities and their structural and functional characteristics are regulated by surface water processes. Our study focused on the impact of changes in water depth and food supplies on small-sized metazoan bottom-fauna (meiobenthos) along a bathymetric transect (1200-5500 m) in the western Fram Strait. The samples were collected every summer season from 2005 to 2009 within the scope of the HAUSGARTEN monitoring program. In comparison to other polar regions, the large inflow of organic matter to the sea floor translates into relatively high meiofaunal densities in this region. Densities along the bathymetric gradient range from approximately 2400 ind. 10 cm-2 at 1200 m to approximately 300 ind. 10 cm-2 at 4000 m. Differences in meiofaunal distribution among sediment layers (i.e., vertical profile) were stronger than among stations (i.e., bathymetric gradient). At all the stations meiofaunal densities and number of taxa were the highest in the surface sediment layer (0-1 cm), and these decreased with increasing sediment depth (down to 4-5 cm). However, the shape of the decreasing pattern differed significantly among stations. Meiofaunal densities and taxonomic richness decreased gradually with increasing sediment depth at the shallower stations with higher food availability. At deeper stations, where the availability of organic matter is generally lower, meiofaunal densities decreased sharply to minor proportions at sediment depths already at 2-3 cm. Nematodes were the most abundant organisms (60-98%) in all the sediment layers. The environmental factors best correlated to the vertical patterns of the meiofaunal community were sediment-bound chloroplastic pigments that indicate phytodetrital matter.

  6. High-density turbidity currents: Are they sandy debris flows?

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugam, G. [Mobil Exploration and Producing Technical Center, Dallas, TX (United States)

    1996-01-01

    Conventionally, turbidity currents are considered as fluidal flows in which sediment is supported by fluid turbulence, whereas debris flows are plastic flows in which sediment is supported by matrix strength, dispersive pressure, and buoyant lift. The concept of high-density turbidity current refers to high-concentration, commonly non-turbulent, flows of fluids in which sediment is supported mainly by matrix strength, dispersive pressure, and buoyant lift. The conventional wisdom that traction carpets with entrained turbulent clouds on top represent high-density turbidity currents is a misnomer because traction carpets are neither fluidal nor turbulent. Debris flows may also have entrained turbulent clouds on top. The traction carpet/debris flow and the overriding turbulent clouds are two separate entities in terms of flow rheology and sediment-support mechanism. In experimental and theoretical studies, which has linked massive sands and floating clasts to high-density turbidity currents, the term high-density turbidity current has actually been used for laminar flows. In alleviating this conceptual problem, sandy debris flow is suggested as a substitute for high-density turbidity current. Sandy debris flows represent a continuous spectrum of processes between cohesive and cohesionless debris flows. Commonly they are rheologically plastic. They may occur with or without entrained turbulent clouds on top. Their sediment-support mechanisms include matrix strength, dispersive pressure, and buoyant lift. They are characterized by laminar flow conditions, a moderate to high grain concentration, and a low to moderate mud content. Although flows evolve and transform during the course of transport in density-stratified flows, the preserved features in a deposit are useful to decipher only the final stages of deposition. At present, there are no established criteria to decipher transport mechanism from the depositional record.

  7. Distribution of major, trace and rare-earth elements in surface sediments of the Wharton Basin, Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Rao, Ch.M.; Higgs, N.C.; Colley, S.; Parthiban, G.

    lithologies (including calcareous ooze, siliceous and red clays) with variable pro- ductivity, aeolian input and influence of Antarc- tic Bottom Water have been studied to address the source, abundance, mode of incorporation and factors controlling....G. and Bruland, K.W., 1985. Rare earth elements in the Pacific and Atlan- tic Oceans. Geochim. Cosmochim. Acta, 49: 1943-1957. Dehairs, F., Chesselet, R. and Jedwab, J., 1980. Discrete sus- pended particles of barite and the barium cycle in the open ocean...

  8. Compostos orgânicos em sedimentos marinhos: uma viagem ao fundo do Oceano Atlântico Norte Organic compounds in marine sediments: a journey to the bottom of the North Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    Luiz Augusto dos Santos Madureira

    2002-09-01

    Full Text Available The present study investigates the origin and distribution of several classes of organic compounds present in recently deposited abyssal sediments in the North East Atlantic Ocean. Six cores were sampled (multicorer along 20ºW longitude as part of the UK's Biogeochemical Ocean Flux Study (BOFS. The sediments underlie diverse water columns, ranging from the Iceland Basin, an area of high primary productivity but presumed low aeolian inputs, to an area off West Africa characterized by oligotrophic and upwelling waters and high aeolian input. Concentration of predominantly marine (e.g. sterols and alkenones and terrestrial (n-alkanes compounds showed remarkable changes along the transect.

  9. 2012 USACE Post Sandy Topographic LiDAR: Virginia and Maryland

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — TASK ORDER NAME: VIRGINIA AND MARYLAND LIDAR ACQUISITION FOR SANDY RESPONSE CONTRACT NUMBER: W912P9-10-D-0533 TASK ORDER NUMBER: W81C8X2314841 Woolpert Project...

  10. 2012 USACE Post-Hurricane Sandy Topographic LiDAR: Eastern Long Island, New York

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — TASK ORDER NAME: EASTERN LONG ISLAND, NEW YORK LIDAR ACQUISITION FOR HURRICANE SANDY RESPONSE CONTRACT NUMBER: W912P9-10-D-0533 TASK ORDER NUMBER: W81C8X23208588...

  11. 2012 USACE Post Hurricane Sandy Topographic LiDAR: Virginia and Maryland

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — TASK ORDER NAME: VIRGINIA AND MARYLAND LIDAR ACQUISITION FOR HURRICANE SANDY RESPONSE CONTRACT NUMBER: W912P9-10-D-0533 TASK ORDER NUMBER: W81C8X2314841 Woolpert...

  12. OahuS_baseline - Offshore baseline used to cast shore-perpendicular transects for measurement of historical shoreline positions along South Oahu, Hawaii (Barbers Point to Sandy Beach)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  13. Offshore baseline for New Jersey North coastal region generated to calculate shoreline change rates from Sandy Hook to Little Egg Inlet, New Jersey (NJN_baseline.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  14. OahuS_shorelines - Shorelines of the southern coastal region of Oahu, Hawaii, from Barbers Point to Sandy Beach, used in shoreline change analysis.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  15. Shorelines of the New Jersey North coastal region used in shoreline change analysis from Sandy Hook to Little Egg Inlet, New Jersey (NewJerseyN_shorelines.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  16. OahuS_shorelines - Shorelines of the southern coastal region of Oahu, Hawaii, from Barbers Point to Sandy Beach, used in shoreline change analysis.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  17. Investigation of superstorm Sandy 2012 in a multi-disciplinary approach

    Directory of Open Access Journals (Sweden)

    M. Kunz

    2013-10-01

    Full Text Available At the end of October 2012, Hurricane Sandy moved from the Caribbean Sea into the Atlantic Ocean and entered the United States not far from New York. Along its track, Sandy caused more than 200 fatalities and severe losses in Jamaica, The Bahamas, Haiti, Cuba, and the US. This paper demonstrates the capability and potential for near-real-time analysis of catastrophes. It is shown that the impact of Sandy was driven by the superposition of different extremes (high wind speeds, storm surge, heavy precipitation and by cascading effects. In particular the interaction between Sandy and an extra-tropical weather system created a huge storm that affected large areas in the US. It is examined how Sandy compares to historic hurricane events, both from a hydro-meteorological and impact perspective. The distribution of losses to different sectors of the economy is calculated with simple input-output models as well as government estimates. Direct economic losses are estimated about USD 4.2 billion in the Caribbean and between USD 78 and 97 billion in the US. Indirect economic losses from power outages is estimated in the order of USD 16.3 billion. Modelling sector-specific dependencies quantifies total business interruption losses between USD 10.8 and 15.5 billion. Thus, seven years after the record impact of Hurricane Katrina in 2005, Hurricane Sandy is the second costliest hurricane in the history of the United States.

  18. Investigation of superstorm Sandy 2012 in a multi-disciplinary approach

    Science.gov (United States)

    Kunz, M.; Mühr, B.; Kunz-Plapp, T.; Daniell, J. E.; Khazai, B.; Wenzel, F.; Vannieuwenhuyse, M.; Comes, T.; Elmer, F.; Schröter, K.; Fohringer, J.; Münzberg, T.; Lucas, C.; Zschau, J.

    2013-10-01

    At the end of October 2012, Hurricane Sandy moved from the Caribbean Sea into the Atlantic Ocean and entered the United States not far from New York. Along its track, Sandy caused more than 200 fatalities and severe losses in Jamaica, The Bahamas, Haiti, Cuba, and the US. This paper demonstrates the capability and potential for near-real-time analysis of catastrophes. It is shown that the impact of Sandy was driven by the superposition of different extremes (high wind speeds, storm surge, heavy precipitation) and by cascading effects. In particular the interaction between Sandy and an extra-tropical weather system created a huge storm that affected large areas in the US. It is examined how Sandy compares to historic hurricane events, both from a hydro-meteorological and impact perspective. The distribution of losses to different sectors of the economy is calculated with simple input-output models as well as government estimates. Direct economic losses are estimated about USD 4.2 billion in the Caribbean and between USD 78 and 97 billion in the US. Indirect economic losses from power outages is estimated in the order of USD 16.3 billion. Modelling sector-specific dependencies quantifies total business interruption losses between USD 10.8 and 15.5 billion. Thus, seven years after the record impact of Hurricane Katrina in 2005, Hurricane Sandy is the second costliest hurricane in the history of the United States.

  19. Carbon and nitrogen stoichiometry regulates the magnitude and temporal dynamics of nitrogenous nutrient regeneration in sandy beach pore water

    Science.gov (United States)

    Goodridge, B. M.; Melack, J. M.

    2013-12-01

    Sandy beaches are located at the interface of terrestrial and marine ecosystems, lining about 70% of the world's ice-free coastline. They can be conduits for fresh groundwater delivery of dissolved inorganic nitrogen (DIN), a vital and often limiting nutrient source, to oceans along coastlines where a hydrologic connection exists with shallow coastal aquifers. However, even along such coastlines, the majority of water within beach sands is recirculated seawater (i.e., pore water), and the regeneration of DIN from the mineralization of marine organic matter (OM) is considered the dominant source of DIN in beach pore water and flux to coastal oceans. The biogeochemical mechanisms regulating the magnitude of and temporal changes in DIN regeneration in saline beach pore water are therefore of prime importance in assessing the role of beaches in coastal marine nitrogen cycling. We assessed the potential stoichiometric control of resource carbon to nitrogen (C:N) on pore water DIN regeneration at four sandy beach study locations, and temporal evolution of pore water C:N at two of the four study locations, along the Santa Barbara, California coastline during synoptic sampling events over the course of a year. We identified pore water dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) as the resources most likely available to microbial heterotrophic metabolism (i.e., C:N), the dominant catalyst of DIN regeneration in marine sediments, finding a negative exponential correlation of DIN with DOC:TDN ratios (673 × 173 e-1.05 × 0.30(DOC:TDN); R2 = 0.55, n = 123). DOC:TDN ratios also demonstrated a negative exponential correlation with residence time (10.0 × 1.7 e-1.08 × 0.48(RT) + 1.61 × 0.54; R2 = 0.79, n = 46), estimated using radon-222 as a pore water residence time tracer. Using model-derived DOC:TDN ratios as the independent variable in the DIN vs. DOC:TDN relationship, we explored temporal changes in DIN regeneration. The modeled DIN vs. residence time

  20. The first actual record of deep open-ocean conditions in the Ediacaran: Fe speciation in pelagic deep-sea sediments in accretionary complexes in Wales, UK

    Science.gov (United States)

    Sato, T.; Asanuma, H.; Okada, Y.; Maruyama, S.; Shozugawa, K.; Matsuo, M.; Windley, B. F.

    2014-12-01

    The first oxidation of a deep ocean in Earth history is considered to have occurred in the Neoproterozoic, coincident with the metazoan diversification; however, the Neoproterozoic geological record has so far been limited to only continental shelves, slopes, or basins at the deepest. Here, we document Neoproterozoic pelagic deep-sea sediments in reconstructed oceanic plate stratigraphy (OPS) in accretionary complexes (ACs) in Anglesey and Lleyn, Wales, UK. The OPS mostly consists of mid-ocean ridge basalts, pelagic red-bedded cherts, hemipelagic siliceous mudstones and turbidite sandstones, in ascending order. Only at Porth Felen in Lleyn Peninsula does the OPS contain black mudstones (ca. 10 m-thick) instead of pelagic red-bedded cherts. Based on the tectonic reconstruction of these ACs, the OPS at Porth Felen has the oldest depositional age. Our new U-Pb date of detrital zircons separated from the turbidite sandstones at Porth Felen has the youngest age of 580±13 Ma. These results suggest that the black mudstones at Porth Felen were deposited no later than the early Ediacaran. We have analyzed these black mudstones by 57Fe Mössbauer spectroscopy, and found that about a quarter of their iron content is contained in pyrite, while the other components are paramagnetic Fe2+ or occasionally paramagnetic Fe3+ in clay minerals. The red cherts in the younger OPS contain hematite as the main iron mineral, paramagnetic Fe3+, and paramagnetic Fe2+. The occurrence of hematite in a deep-sea chert essentially indicates a primary oxidizing depositional condition, whereas pyrite is indicative of a reducing environment. The present data confirm that a reducing deep-sea existed in the early Ediacaran during the black mudstone deposition, and that an oxidizing deep-sea had been established by the late Ediacaran. In conclusion, our results provide the first direct evidence of an actual deep open-ocean in the Ediacaran to clarify the timing and extent of the Neoproterozoic

  1. Late Paleozoic sedimentation and tectonics of rift and limited ocean basin at southern margin of the Qinling

    Institute of Scientific and Technical Information of China (English)

    孟庆任; 张国伟; 于在平; 梅志超

    1996-01-01

    The rifting and occurrence of limited oceanic basin at southern margin of Qinling separated south Qinling from Yangtze Block in late Paleozoic. Detailed sedimentary studies were carried out at two localities at southern flank of this rift-limited oceanic basin zone. and depositional architectures were then established accordingly. The results show that tectono-sedimentary stories are differing in different positions but clearly demonstrate spatial development of the rift. It is obvious that the rift in west part of Mianlue underwent two developmentary phases, early rapid subsidence and late slow subsidence, and there occurred breakup unconformity between the seccessions of the two subsidence phases. Combined with the data of structural, geochemical and chronological studies on the ophiolitic complex within the Mianlue zone. it is demonstrated that the rifting-drifting transition occurred, leading to the development of limited oceanic basin during the late Paleazoic. Spatial and temporal evolution of the

  2. Integrated ocean drilling program expedition 341 Preliminary report: Southern Alaska margin- Interactions of tectonics, climate, and sedimentation

    Digital Repository Service at National Institute of Oceanography (India)

    Jaeger, J.M.; Asahi, H.; Gulick, S.S.; Bahlburg, H.; LeVay, L.J.; Belanger, C.L.; Slagle, A.L.; Berbel, G.B.B.; Drab, L.; Childress, L.B.; Cowan, E.A.; Konno, S.; Forwick, M.; Marz, C.E.; Fukumura, A.; Matsuzaki, K.M.; Ge, S.; McClymont, E.L.; Gupta, S.M.; et al.

    global increase in erosion rates and sediment delivery to basins. The effects of this increased erosion may be profound, as worldwide analyses of orogenic belts have shown that Earth systems cannot be considered to be the product of a series of distinct...

  3. Major, trace, and rare earth elements in the sediments of the Central Indian Ocean Basin: Their source and distribution

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Jauhari, P.

    positive correlation with each other suggesting their association with a single authigenic phase such as Mn oxide. Biogenic opal contributes 30-50% of the total silica in the siliceous sediment. Aluminum, Fe, and K have contributed greater than 60 % from...

  4. Sediment Management Options for Galveston Island, Texas

    Science.gov (United States)

    2015-06-15

    considered the “Face of Galveston.” Sediment Budget Morang (2006) calculated a sediment budget for the north Texas shore between Sabine Pass and San Luis...cross- shore beach profiles. The sediment budget was completed by hand and then the results were added to the Sediment Budget Analysis System (SBAS...University (Dellapenna, personal communications 2003) conducted seismic studies detecting sandy facies offshore of the south jetty making an

  5. Rare earth element and neodymium isotope tracing of element input and past ocean circulation. Study from north and south pacific seawater and sediments

    Energy Technology Data Exchange (ETDEWEB)

    Froellje, Henning

    2016-08-09

    Ocean circulation and cycling of trace elements within the oceanic water column is of great significance for modern and past climates. The global overturning circulation is responsible for the distribution of water masses, heat and particulate and dissolved compounds, while biological and chemical processes, such as primary productivity or particle scavenging, control the cycling of nutrients and trace elements in the ocean, and ultimately influence the ocean-atmosphere exchange of carbon. Rare earth elements (REE) and neodymium (Nd) isotopes are widely used as tracers for lithogenic element fluxes and modern and past ocean circulation and water mass mixing. The use of Nd isotopes in paleoceanographic investigations is based on the precise knowledge of processes involved in REE cycling and of the modern oceanic Nd isotope distribution. The Pacific is the largest of the world oceans, but it is highly underrepresented in present-day and past seawater Nd isotope and REE investigations compared to the Atlantic Ocean. In this study, Nd isotopes and REEs are analysed in North Pacific seawater (chapter 2) and sediment samples from the South Pacific (chapters 3-5) to contribute to a better understanding of sources and cycling of REEs and Nd isotopes in present-day seawater and to investigate past water mass mixing and circulation changes during the last glacial termination and throughout the last glacial-interglacial cycle. Neodymium isotopes in seawater and sedimentary archives (fossil fish teeth and debris, foraminifera, ferromanganese oxides, lithogenic particles) were analysed using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), and REE concentrations were analysed using isotope dilution ICP-MS. Results from combined analysis of REEs, and Nd and radium isotopes from North Pacific seawater (coastal seawaters of the Hawaiian Island of Oahu and seawater from the offshore Hawaii Ocean Time-series Station ALOHA) show a clear influence of the

  6. Clay mineral distribution in surface sediments between Indonesia and NW Australia - source and transport by ocean currents

    OpenAIRE

    F. X. Gingele; P. De Deckker; Hillenbrand, C. -D.

    2001-01-01

    The clay mineral distribution in sediments between Indonesia and NW Australia has been assessed on the basis of 166 core-top samples. Clay mineral assemblages are closely related to the geology and weathering regime of the adjacent hinterland and allow the distinction of four clay mineral provinces. Three provinces, Western, Central and Eastern Province are situated along the Indonesian Islands Arc, from Sumatra in the west to Timor in the east. Illite is the major clay mineral of the Western...

  7. Methane oxidation in permeable sediments at hydrocarbon seeps in the Santa Barbara Channel, California

    Science.gov (United States)

    Treude, T.; Ziebis, W.

    2010-03-01

    A shallow-water area in the Santa Barbara Channel (California), known collectively as the Coal Oil Point seep field, is one the largest natural submarine oil and gas emission areas in the world. Both gas and oil are seeping constantly through a predominantly sandy seabed into the ocean. This study focused on the methanotrophic activity within the surface sediments (0-15 cm) of the permeable seabed in the so-called Brian Seep area at a water depth ~10 m. Detailed investigations of biogeochemical parameters in the sediment surrounding active gas vents indicated that methane seepage through the permeable seabed induces a convective transport of fluids within the surface sediment layer, which results in a deeper penetration of oxidants (oxygen, sulfate) into the sediment, as well as in a faster removal of potentially inhibiting reduced end products (e.g. hydrogen sulfide). Methanotrophic activity was often found close to the sediment-water interface, indicating the involvement of aerobic bacteria. However, biogeochemical data suggests that the majority of methane is consumed by anaerobic oxidation of methane (AOM) coupled to sulfate reduction below the surface layer (>15 cm), where sulfate is still available in high concentrations. This subsurface maximum of AOM activity in permeable sands is in contrast to known deep-sea seep habitats, where upward fluid advection through more fine-grained sediments leads to an accumulation of AOM activity within the top 10 cm of the sediments, because sulfate is rapidly depleted.

  8. Soft sediment deformation associated with the passage of North Atlantic Deep water through the deep Ariel Graben, Mozambique Ridge southwest Indian Ocean.

    Science.gov (United States)

    Wiles, Errol; Green, Andrew; Watkeys, Mike; Jokat, Wilfried; Krocker, Ralph

    2014-05-01

    Interactions between bottom water currents and seafloor sediments are well known. Bottom current generated bedforms are varied both morphologicaly and sedimentologicaly. Sediment transport and deposition, associated with bottom water circulation, plays a significant role is sculpting seafloor morphology in all ocean basins. Indeed, bedforms have been used to great effect to define the presence, direction and strength of bottom water circulation globally. Here we present new multibeam swath bathymetry and high frequency seismic data from the Natal Valley and Mozambique Ridge, southwest Indian Ocean. These data show a deep (-3200 m) channel-like feature (Ariel Graben, situated at 28° 30"S on the Mozambique Ridge) connecting the northern Natal Valley to the Mozambique Basin. A distinct W - E change in seafloor morphology and seismic character is noted moving from the Natal Valley through the Ariel Graben. The northern flank of the graben exhibits smooth plastered drifts which give way to undulating seafloor in the east. The plastered drifts are characterised by distinct bottom echoes, with several discontinuous sub-bottom reflections. In contrast, the undulating seafloor is characterised by distinct hyperbolic echoes, with occasional indistinct sub-bottom reflectors. The W - E orientated undulations are straight crested, parallel / sub-parallel to the local isobaths. Wavelength is variable, ranging from 600 m to 1200 m. Cross-sectional symmetry of these features varies from symmetrical to asymmetrical, with board crests and narrow troughs. When asymmetrical, the lower (south-facing) limb is the longer (511.76 m average) than the upper (north-facing) limb (323.53 m average). The lower limbs are also steeper than the upper limbs; calculated averages being 3.80° and 1.55°, respectively. Overall, the slope on which the undulations are found, is south-facing with a gradient of 1.54°, however, the area affected by undulations is slightly steeper (average slope of 1.75

  9. Stable isotope hydrology in fractured and detritic aquifers at both sides of the South Atlantic Ocean: Mar del Plata (Argentina) and the Rawsonville and Sandspruit river catchment areas (South Africa)

    Science.gov (United States)

    Glok Galli, Melisa; Damons, Matthew E.; Siwawa, Sitembiso; Bocanegra, Emilia M.; Nel, Jacobus M.; Mazvimavi, Dominic; Martínez, Daniel E.

    2017-01-01

    The aim of this work is to characterize the isotope composition of water (2H and 18O) in order to establish the relationship between fractured and detritic aquifers in similar hydrological environments located at both sides of the Atlantic Ocean. The Mar del Plata zone, placed in the Argentine Buenos Aires province in South America, and the Rawsonville and Sandspruit river catchment areas, situated in the Western Cape province in South Africa were compared. Rainwater and groundwater samples from fractured and detritic aquifers were analyzed through laser spectroscopy. In both Argentina and South African study sites, stable isotopes data demonstrate an aquifers recharge source from rainfall. For the Mar del Plata region, two different groups of detritic aquifer's samples with distinct recharge processes can be identified due to the close relationship existing between the present hydrogeological environments, the aquifer's grain size sediments and the isotopes contents: one representing rapid infiltration in aquifer sediments of the creeks' palaeobeds and hills zones (sandy or silt sandy sediments) and the other with slow infiltration of evaporated water in plain zones with an aquitard behavior. In the last group, the evaporation process occurs previous infiltration or in the aquifer's non-saturated zone, because of the existence of very low topographic gradients and fine-grained sediments. The evaporation phenomenon is not evident in the Sandspruit river catchment site's detritic aquifer, because its sandy composition allows a faster infiltration rate than in the loess that compounds the Pampeano aquifer in the interfluves zones of the Argentinian study area.

  10. Pyrite framboid size distribution as a record for relative variations in sedimentation rate: An example on the Toarcian Oceanic Anoxic Event in Southiberian Palaeomargin

    Science.gov (United States)

    Gallego-Torres, David; Reolid, Matías; Nieto-Moreno, Vanesa; Martínez-Casado, Francisco Javier

    2015-12-01

    The Early Toarcian Oceanic Anoxic Event (T-OAE) represents one of the major alterations of the carbon cycle of the Mesozoic period. Despite being globally recognized, and particularly represented within the Tethys realm, its expression in the sedimentary record is highly variable depending on the studied section, which suggests local environmental factors exert a major control on the resulting lithological appearance of the event. We investigated the Fuente Vidriera section, in the eastern External Subbetic of the Betic Cordillera (Spain), where the Lower Jurassic is represented by alternate layers of marls and marly limestones, and the T-OAE is identified by a major δ13C excursion, micropalaeontological, ichnofacies and geochemical evidences. For this study, we analyzed pyrite framboid size distribution of the sedimentary sequence in Fuente Vidriera. The outcome, according to previous studies on pyrite framboid distribution, is contradictory when compared to all other evidences, suggesting oxygen depletion during the T-OAE. The results have been reinterpreted in the light of Crystal Size Distribution Theory and we conclude that not only growth time but also geochemical environment controls pyrite formation. Since growth time is directly related to burial rates, this approach allows us to reconstruct relative variations of sedimentation rates during the Early Jurassic in this location. Based on the obtained results, we provide new evidences for wide-spread transgression during the Early Toarcian in the South Iberian palaeomargin, which induced low sedimentation rate and lower energetic conditions, as well as favored oxygen impoverished bottom waters.

  11. Biosignatures in chimney structures and sediment from the Loki's Castle low-temperature hydrothermal vent field at the Arctic Mid-Ocean Ridge.

    Science.gov (United States)

    Jaeschke, Andrea; Eickmann, Benjamin; Lang, Susan Q; Bernasconi, Stefano M; Strauss, Harald; Früh-Green, Gretchen L

    2014-05-01

    We investigated microbial life preserved in a hydrothermally inactive silica–barite chimney in comparison with an active barite chimney and sediment from the Loki's Castle low-temperature venting area at the Arctic Mid-Ocean Ridge (AMOR) using lipid biomarkers. Carbon and sulfur isotopes were used to constrain possible metabolic pathways. Multiple sulfur (dδ34S, Δ33S) isotopes on barite over a cross section of the extinct chimney range between 21.1 and 22.5 % in δ34S, and between 0.020 and 0.034 % in Δ33S, indicating direct precipitation from seawater. Biomarker distributions within two discrete zones of this silica–barite chimney indicate a considerable difference in abundance and diversity of microorganisms from the chimney exterior to the interior. Lipids in the active and inactive chimney barite and sediment were dominated by a range of 13C-depleted unsaturated and branched fatty acids with δ13C values between -39.7 and -26.7 %, indicating the presence of sulfur-oxidizing and sulfate-reducing bacteria. The majority of lipids (99.5 %) in the extinct chimney interior that experienced high temperatures were of archaeal origin. Unusual glycerol monoalkyl glycerol tetraethers (GMGT) with 0–4 rings were the dominant compounds suggesting the presence of mainly (hyper-) thermophilic archaea. Isoprenoid hydrocarbons with δ13C values as low as -46 % also indicated the presence of methanogens and possibly methanotrophs.

  12. Fungal community analysis in the deep-sea sediments of the Pacific Ocean assessed by comparison of ITS, 18S and 28S ribosomal DNA regions

    Science.gov (United States)

    Xu, Wei; Luo, Zhu-Hua; Guo, Shuangshuang; Pang, Ka-Lai

    2016-03-01

    We investigated the diversity of fungal communities in 6 different deep-sea sediment samples of the Pacific Ocean based on three different types of clone libraries, including internal transcribed spacer (ITS), 18S rDNA, and 28S rDNA regions. A total of 1978 clones were generated from 18 environmental clone libraries, resulting in 140 fungal operational taxonomic units (OTUs), including 18 OTUs from ITS, 44 OTUs from 18S rDNA, and 78 OTUs from 28S rDNA gene primer sets. The majority of the recovered sequences belonged to diverse phylotypes of the Ascomycota and Basidiomycota. Additionally, our study revealed a total of 46 novel fungal phylotypes, which showed low similarities (<97%) with available fungal sequences in the GenBank, including a novel Zygomycete lineage, suggesting possible new fungal taxa occurring in the deep-sea sediments. The results suggested that 28S rDNA is an efficient target gene to describe fungal community in deep-sea environment.

  13. Application of sediment core modelling to understanding climates of the past: An example from glacial-interglacial changes in Southern Ocean silica cycling

    Directory of Open Access Journals (Sweden)

    A. Ridgwell

    2006-12-01

    Full Text Available Paleoceanographic evidence from the Southern Ocean reveals an apparent stark meridional divide in biogeochemical dynamics associated with the glacial-interglacial cycles of the late Neogene. South of the present-day position of the Antarctic Polar Front biogenic opal is generally much more abundant in sediments during interglacials compared to glacials. To the north, an anti-phased relationship is observed, with maximum opal abundance instead occurring during glacials. This antagonistic response of sedimentary properties is an important model validation target for testing hypotheses of glacial-interglacial change, particularly with respect to understanding the causes of the variability in atmospheric CO2. Here, I illustrate a time-dependent modelling approach to helping understand past climatic change by means of the generation of synthetic sediment core records. I find a close match between model-predicted and observed down-core changes in sedimentary opal content is achieved when changes in seasonal sea-ice extent is imposed, suggesting that the cryosphere is probably the primary driver of the striking features exhibited by the paleoceanographic record of this region.

  14. Intense photooxidative degradation of planktonic and bacterial lipids in sinking particles collected with sediment traps across the Canadian Beaufort Shelf (Arctic Ocean

    Directory of Open Access Journals (Sweden)

    J.-F. Rontani

    2012-06-01

    Full Text Available The lipid content of seven samples of sinking particles collected with sediment traps moored at ~100 m depth in summer and fall across the Canadian Beaufort Shelf (Arctic Ocean was investigated. Our main goal was to quantify and characterize the biotic and abiotic degradation processes that acted on sinking material during these periods. Diatoms, which dominated the phytoplanktonic assemblage in every trap sample, appeared to be remarkably sensitive to Type II (i.e. involving singlet oxygen photodegradation processes in summer, but seemed to be relatively unaffected by biotic degradation at the same time. Hence, the relative recalcitrance of phytodetritus towards biodegradation processes during the Arctic midnight sun period was attributed to the strong photodegradation state of heterotrophic bacteria, which likely resulted from the efficient transfer of singlet oxygen from photodegraded phytoplanktonic cells to attached bacteria. In addition, the detection in trap samples of photoproducts specific to wax ester components found in herbivorous copepods demonstrated that zooplanktonic faecal material exported out of the euphotic zone in summer were as well affected by Type II photodegradation processes. By contrast, sinking particles collected during the autumn were not influenced by any light-driven stress. Further chemical analyses showed that photodegraded sinking particles contained an important amount of intact hydroperoxides, which could then induce a strong oxidative stress in underlying sediments.

  15. Rb-Sr, Sm-Nd, K-Ca, O, and H isotopic study of Cretaceous-Tertiary boundary sediments, Caravaca, Spain Evidence for an oceanic impact site

    Energy Technology Data Exchange (ETDEWEB)

    Depaolo, D.J.; Kyte, F.T.; Marshall, B.D.

    1983-09-01

    The results of isotopic and trace-element-abundance analyses of Ir-enriched Cretaceous-Tertiary-boundary clay sediments from Caravaca, Spain, and of adjacent carbonate and marl layers, are presented. Acetic-acid and HCl leachates and residues were analyzed by isotope dilution to determine K, Rb, Sr, Sm, and Nd concentrations and Sr-87/Sr-86 and Nd-143/Nd-144 ratios. The stable isotope ratios delta-D, delta-(C-13), and delta-(0-18) were also determined. The results are presented in tables and graphs and compared with published data on the Caravaca sediments and on samples from other locations. The boundary clay is found to be distinguished from the adjacent layers by its isotopic ratios and to be of mainly terrestrial, lithospheric (deeper than 3-km) origin. Although submarine-weathering effects are evident and difficult to quantify, the degree of variation in Ni, Ir, Sr, and REE concentrations is considered too large to be attributed to postdepositional processes alone. These findings are seen as evidence for the ocean impact of a large single asteroid producing a worldwide blanket of ejecta, a large injection of water vapor into the atmosphere, and perhaps a gigantic tsunami, at the end of the Cretaceous period.

  16. Sediment distribution in the offshore regions of Goa

    Digital Repository Service at National Institute of Oceanography (India)

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

    grades just adjacent to the beaches followed by either silty sands or sandy silts. Further seaward, the nearshore area off Calangute shows sandy mud in the south and mud in the north while clay occurs in the Colva area. Relatively coarse grained sediments...

  17. Recycled oceanic crust and marine sediment in the source of alkali basalts in Shandong, eastern China: Evidence from magma water content and oxygen isotopes

    Science.gov (United States)

    Liu, Jia; Xia, Qun-Ke; Deloule, Etienne; Chen, Huan; Feng, Min

    2015-12-01

    The magma water contents and cpx δ18O values in alkali basalts from the Fuyanyshan (FYS) volcano in Shandong, eastern China, were investigated by an inverse calculation based on the water content of clinopyroxene (cpx) phenocrysts, the ivAlcpx-dependent water partitioning coefficient Dwatercpx>/melt, and secondary ion mass spectrometer, respectively. The calculated water content (H2O wt.) of magma ranges from 0.58% to 3.89%. It positively correlates with heavy rare earth element concentrations and bulk rock 87Sr/86Sr ratios, and it negatively correlates with Nb/U ratios. However, it is not correlated with bulk Mg# (Mg# = 100 × Mg / (Mg + Fe)) and (La/Yb)n (n represents primitive mantle normalization). Combined with the rather homogenous distribution of water content within cpx grains, these correlations indicate that the water variations among different samples represent the original magma signature, rather than results of a shallow process, such as degassing and diffusion. The δ18O of cpx phenocrysts varies from 3.6‰ to 6.3‰ (±0.5‰, 2SD), which may be best explained by the involvement of components from the lower and upper oceanic crust with marine sediments within the mantle source. The H2O/Ce ratios of the calculated melts range from 113 to 696 and form a positive trend with bulk rock 87Sr/86Sr, which cannot be explained by the recycled Sulu eclogite or by the metasomatized lithospheric mantle. Our modeling calculation shows that the decoupling of ɛHf and ɛNd could be caused by the involvement of marine sediments. Combing the high Ba/Th ratios, positive Sr spikes, and low Ce/Pb ratios for the Fuyanshan basalts, we suggest that the hydrous nature of the FYS basalts was derived from the hydrous mantle transition zone with ancient sediments.

  18. IMPLEMENTASI SANDI HILL UNTUK PENYANDIAN CITRA

    Directory of Open Access Journals (Sweden)

    JJ Siang

    2002-01-01

    Full Text Available Hill's code is one of text encoding technique. In this research, Hill's code is extended to image encoding. The image used is BMP 24 bit format. 2x2 and 3x3 matrices is used as a key. The results show that Hill's code is suitable for image whose RGB values vary highly. On the contrary, it is not suitable for less varied RGB images since its original pattern is still persisted in encrypted image. Hill's code for image encoding has also disadvantage in the case that the key matrix is not unique. However, for daily application, with good key matrix, Hill's code can be applied to encode image since it's process only deals with simple matrix operation so it become fast. Abstract in Bahasa Indonesia : Sandi Hill merupakan salah satu teknik penyandian teks. Dalam penelitian ini, pemakaian sandi Hill diperluas dari teks ke citra bertipe BMP 24 bit. Matriks yang dipakai berordo 2x2 dan 3x3. Hasil percobaan menunjukkan bahwa sandi Hill cocok untuk enkripsi citra dengan variasi nilai RGB antar piksel berdekatan yang tinggi (seperti foto, tapi tidak cocok untuk citra dengan variasi nilai RGB yang rendah (seperti gambar kartun karena pola citra asli masih tampak dalam citra sandi. Sandi Hill juga memiliki kelemahan dalam hal tidak tunggalnya matriks kunci yang dapat dipakai. Akan tetapi untuk pemakaian biasa, dengan pemilihan matriks kunci yang baik, sandi Hill dapat dipakai untuk penyandian karena hanya melibatkan operasi matriks biasa sehingga prosesnya relatif cepat. Kata kunci: Sandi Hill, Citra, Relatif Prima.

  19. Uncertainties in sandy shorelines evolution under the Bruun rule assumption

    Directory of Open Access Journals (Sweden)

    Gonéri eLe Cozannet

    2016-04-01

    Full Text Available In the current practice of sandy shoreline change assessments, the local sedimentary budget is evaluated using the sediment balance equation, that is, by summing the contributions of longshore and cross-shore processes. The contribution of future sea-level-rise induced by climate change is usually obtained using the Bruun rule, which assumes that the shoreline retreat is equal to the change of sea-level divided by the slope of the upper shoreface. However, it remains unsure that this approach is appropriate to account for the impacts of future sea-level rise. This is due to the lack of relevant observations to validate the Bruun rule under the expected sea-level rise rates. To address this issue, this article estimates the coastal settings and period of time under which the use of the Bruun rule could be (invalidated, in the case of wave-exposed gently-sloping sandy beaches. Using the sedimentary budgets of Stive (2004 and probabilistic sea-level rise scenarios based on IPCC, we provide shoreline change projections that account for all uncertain hydrosedimentary processes affecting idealized coasts (impacts of sea-level rise, storms and other cross-shore and longshore processes. We evaluate the relative importance of each source of uncertainties in the sediment balance equation using a global sensitivity analysis. For scenario RCP 6.0 and 8.5 and in the absence of coastal defences, the model predicts a perceivable shift toward generalized beach erosion by the middle of the 21st century. In contrast, the model predictions are unlikely to differ from the current situation in case of scenario RCP 2.6. Finally, the contribution of sea-level rise and climate change scenarios to sandy shoreline change projections uncertainties increases with time during the 21st century. Our results have three primary implications for coastal settings similar to those provided described in Stive (2004 : first, the validation of the Bruun rule will not necessarily be

  20. Buried in time: Culturable fungi in a deep-sea sediment core from the Chagos Trench, Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Raghukumar, C.; Raghukumar, S.; Sheelu, G.; Gupta, S.M.; Nath, B.N.; Rao, B.R.

    was estimated from 25-30 microscopic fields, each containing 15-20 spores (Raghukumar and Raghukumar, 1998). 3. Results Biostratigraphic dating using radiolarian fossil index species showed three distinct litho-biounits of the sediment core (Table 1... was not found below 280 cm. Therefore, this unit of the core up to 280 cm, was estimated to be younger than 7 0.18 Ma. Collosphaera tuberosa was found to occur up to a depth of 370 cm, while the fossil species Stylatractus universus, with a last appearance...

  1. A documentation on burrows in hard substrates of ferromanganese crusts and associated soft sediments from the Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, R.

    , the photographic records of recent bioturbation (Figure 4 a and b) on soft sediments were taken using a deep-towed camera. Extensive fossil burrows are seen in the cla ystone and altered pumice substrates of many ferromanganese en- crustations and nodules...). One of the associated organisms collected with these samples is Echinodermata (Figure 3 i). The diameter of the fossil burrows varies from 3 to 10 mm. Their length ranges between 1 and 10 cm in different substrates (Figure 3 a?g). Some burrows...

  2. Benthic Epiphytic Diatoms in Deep-sea Southern Ocean Sediments as a New Tool for Reconstructing Antarctic Paleoclimatic and Paleoceanographic History: Implications of Floating 'Macroalgal Biotic Oases'

    Science.gov (United States)

    Harwood, D. M.; Porter, N.; OConnell, S.

    2014-12-01

    A new paleobiological proxy for Antarctic paleoclimate history provides insight into past extent of open marine shelves on Wilkes Land margin, and calls for reassessment of IRD interpretations in the deep-sea. Marine, epiphytic benthic diatoms that grow attached to macroalgae (seaweed) are recovered in Miocene sediment from DSDP Site 269. They suggest periodic presence of floating rafts or 'biotic oases' in the Southern Ocean comprising buoyant macroalgae, attached benthic diatoms, and biota associated with this displaced coastal community. Macroalgae attach to the substrate with a holdfast, a multi-fingered structure that serves as an anchor. Uprooted holdfasts attached to buoyant macroalgae can raft sedimentary particles, some large (>50 kg), into the deep-sea. In addition, a rich biota of associated invertebrates live in cavities within the holdfast, the dispersal of which may explain the biogeographic distribution of organisms on Subantarctic islands. The stratigraphic occurrence of large, benthic epiphytic diatoms of genera Arachnoidiscus, Isthmia, Rhabdonema, Gephyra, Trigonium, and smaller Achnanthes, Cocconeis, Grammatophora, and Rhaphoneis in sediment cores from DSDP Site 269 reflect a rich, productive epiphytic diatom flora that maintained its position in the photic zone attached to their buoyant seaweed hosts. Amphipods and other herbivores grazed the benthic diatoms and produced diatom-rich fecal pellets that were delivered to the sea-floor. The discontinuous stratigraphic occurrence of the epiphytic diatoms, amongst the background of planktonic diatoms in Core 9 of DSDP Site 269, suggests environmental changes induced by either warm or cold events may have controlled the production and/or release of the macroalgae into the deep-sea. Warm events led to increased shelf areas, and cold events led to formation of ice on the macroalgae to increase their buoyancy and lift-off. Complicating the distinction between warm and cold events is the potential for the

  3. Constraining the Time-Scale of Interaction of Sea Ice Sediments and Surface Sea Water in the Arctic Ocean Using Short-Lived Radionuclide Tracers

    Science.gov (United States)

    Baskaran, M.; Andersson, P. S.; Jweda, J.; Dahlqvist, R.; Ketterer, M. E.

    2007-12-01

    We measured the activities of short-lived radionuclides (Th-234, Be-7, Po-210, Pb-210, Cs-137, Th-234, Ra-226 and Ra-228) and concentrations of several elements (Be, Pb, Fe, Al, Co, Ni, Cu and Zn) on a suite of ice-rafted sediments (IRS) collected during BERINGIA-2005 in the Western Arctic Ocean. A suite of water samples were also collected and analyzed for particulate and dissolved Be-7, Po-210, Pb-210, Th-234, Ra-226 and Ra-228. The activities of Be-7 and Pb-210 in the IRS are 1-2 orders of magnitude higher than those reported in the source sediments. Presence of excess Th-234 in the IRS indicates that the removal of Th-234 from surface seawater took place on time scales comparable to the mean-life of Th-234. While the Po-210/Pb-210 activity ratios in the source sediments (1.0) and the atmospheric depositional input (~0.1) are known, varying ratios of 0.78 to 1.0 were found in the IRS. This ratio can be utilized to obtain the residence time of the IRS in sea ice. The activity of Ra-226 and Ra-228 in all the IRS is nearly constant (within a factor of 1.6) and are comparable to the benthic sediments in the source region. The activities of atmospherically-delivered radionuclides, Be-7 and Pb-210, in IRS varied by factors of ~4.5 and 9, respectively, and this variation is attributed to differences in the extent of interaction of surface water with IRS and differences in the mean-lives of these nuclides. While significant enrichment of Be-7 and Pb-210 has been found, there is no enrichment of stable Pb or Be. The Al-normalized enrichment factor for elements measured (Co, Ni, Cu, Zn, Pb and Be) indicate that there is no significant enrichment of these elements, with Al-normalized enrichment factors less than 1.3.

  4. EAARL Coastal Topography-Sandy Hook 2007

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A first surface/bare earth elevation map (also known as a Digital Elevation Model, or DEM) of the Gateway National Recreation Area's Sandy Hook Unit in New Jersey...

  5. Heterotrophic bacterial populations in tropical sandy beaches

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, S.; LokaBharathi, P.A.

    Distribution pattern of heterotrophic bacterial flora of three sandy beaches of the west coast of India was studied. The population in these beaches was microbiologically different. Population peaks of halotolerant and limnotolerant forms were...

  6. REE and (э)Nd of clay fractions in sediments from the eastern Pacific Ocean: Evidence for clay sources

    Institute of Scientific and Technical Information of China (English)

    LIU Jihua; SHI Xuefa; CHEN Lirong; HUANG Yongyang; WANG Yinxi; CUI Yingchun; BU Wenrui

    2005-01-01

    Clay fractions in the non-calcareous surface sediments from the eastern Pacific were analyzed for clay minerals, REE and 143Nd/144Nd. Montmorillonite/illite ratio (M/I ratio), total REE contents ((REE), LREE/HREE ratio and cerium anomaly (бCe) may effectively indicate the genesis of clay minerals. Clay fractions with M/I ratio >1, бCe (0.85, (REE (400 μg/g, LREE/HREE ratio (4, and REE patterns similar to those of pelagic sediments are terrigenous and autogenetic mixed clay fractions and contain more autogenetic montmorillonite. Clay fractions with M/I ratio <1, бCe=0.86 to 1.5, ΣREE=200 to 350 μg/g, LREE/HREE ratio (6 and REE distribution patterns similar to that of China loess are identified as terrigenous clay fraction. The 143Nd/144Nd ratios or (э)Nd values of clay fractions inherit the features of terrigenous sources of clay minerals. Clay fractions are divided into 4 types according to (э)Nd values. Terrigenous clay minerals of type I with the (э)Nd values of -8 to -6 originate mainly from North American fluvial deposits. Those of type II with the (э)Nd values of -9 to -7 are mainly from the East Asia and North American fluvial deposits. Those of type III with (э)Nd values of -6 to -3 could come from the central and eastern Pacific volcanic islands. Those of type IV with (э)Nd values of -13 to -12 may be from East Asia eolian. The terrigenous and autogenetic mixed clay fractions show patchy distributions, indicating that there are volcanic or hot-spot activities in the eastern Pacific plate, while the terrigenous clay fractions cover a large part of the study area, proving that the terrigenous clay minerals are dominant in the eastern Pacific.

  7. Anaerobic oxidation of methane at a marine methane seep in a forearc sediment basin off Sumatra, Indian Ocean

    Directory of Open Access Journals (Sweden)

    Michael eSiegert

    2011-12-01

    Full Text Available A cold methane-seep was discovered in a forearc sediment basin off the island Sumatra, exhibiting a methane-seep adapted microbial community. A defined seep centre of activity, like in mud volcanoes, was not discovered. The seep area was rather characterized by a patchy distribution of active spots. The relevance of AOM was reflected by 13C depleted isotopic signatures of dissolved inorganic carbon (DIC. The anaerobic conversion of methane to CO2 was confirmed in a 13C-labelling experiment. Methane fuelled a vital microbial and invertebrate community which was reflected in cell numbers of up to 4 x 109 cells cm 3 sediment and 13C depleted guts of crabs populating the seep area. The microbial community was analysed by total cell counting, catalyzed reporter deposition – fluorescence in situ hybridisation (CARD-FISH, quantitative real-time PCR (qPCR and denaturing gradient gel electrophoresis (DGGE. CARD-FISH cell counts and qPCR measurements showed the presence of Bacteria and Archaea, but only small numbers of Eukarya. The archaeal community comprised largely members of ANME-1 and ANME-2. Furthermore, members of the Crenarchaeota were frequently detected in the DGGE analysis. Three major bacterial phylogenetic groups (δ-Proteobacteria, candidate division OP9 and Anaerolineaceae were abundant across the study area. Several of these sequences were closely related to the genus Desulfococcus of the family Desulfobacteraceae, which is in good agreement with previously described AOM sites. In conclusion, the majority of the microbial community at the seep consisted of AOM related microorganisms, while the relevance of higher hydrocarbons as microbial substrates was negligible.

  8. Effects of Continental Weathering and Sedimentary Sorting on the Hf, Nd, and Pb Isotopic Composition of Sediments and Implications for Dissolved Input to the Ocean

    Science.gov (United States)

    van de Flierdt, T.; Hemming, S. R.; Goldstein, S. L.

    2005-05-01

    The application of radiogenic isotopes of dissolved trace metals (Hf, Pb, Nd) in the ocean to study climate induced weathering changes on the continents is a relatively new and exciting field of research. Most studies on the radiogenic isotope composition of past seawater are based on chemical sediments such as ferromanganese crusts, and suggest a strong linkage in changes in the style of weathering (chemical vs. physical/glacial) on the continents and the isotopic composition of seawater for elements such as Hf and Pb. This is evidenced by records from the northwest Atlantic, which show significant changes in the Hf and Pb isotopic composition of seawater associated with the onset of Northern Hemisphere Glaciation (NHG) over the past 3 Myr. On the other hand, the impact of glacial weathering on the Nd isotopic composition of seawater is generally thought to be negligible. In order to better understand the systematics and mechanisms of weathering, erosion, and run-off, as well as their bearing on the isotopic composition of the ocean we choose the following strategy: sediments from the Amerilik and Gothabs Fjords near Nuuk (Greenland) have been analyzed for their bulk rock and grain size specific Hf, Nd, and Pb isotopic compositions (sand, silt, mud). Both Fjords are surrounded by early Archean gneisses, among the oldest rocks on Earth, and are filled with glacially floured sediments. Precambrian rocks surround a large fraction of the circum-North Atlantic area that was covered by ice sheets during the NHG, and the source rocks in this region are the most extreme examples. Current knowledge about the impact of weathering processes on isotope systematics implies that the largest changes in the Hf (and Pb) isotopic composition of seawater are expected to arise from glacial weathering of old continental sources. Our data reveal large differences in grain size specific isotope ratios, e.g. between the mud and sand fractions, for sediments with an old provenance

  9. Simulation and control of morphological changes due to dam removal in the Sandy River, Oregon, USA

    Science.gov (United States)

    Ding, Y.; Altinakar, M. S.

    2015-03-01

    A one-dimensional channel evolution simulation model (CCHE1D) is applied to assess morphological changes in a reach of the Sandy River, Oregon, USA, due to the Marmot Dam removal in 2007. Sediment transport model parameters (e.g. sediment transport capacity, bed roughness coefficient) were calibrated using observed bed changes after the dam removal. The validated model is then applied to assess long-term morphological changes in response to a 10-year hydrograph selected from historical storm water records. The long-term assessment of sedimentation gives a reasonable prediction of morphological changes, expanding erosion in reservoir and growing deposition immediately downstream of the dam site. This prediction result can be used for managing and planning river sedimentation after dam removal. A simulation-based optimization model is also applied to determine the optimal sediment release rates during dam-removal that will minimize the morphological changes in the downstream reaches.

  10. Decadal changes in carbon fluxes at the East Siberian continental margin: interactions of ice cover, ocean productivity, particle sedimentation and benthic life

    Science.gov (United States)

    Boetius, A.; Bienhold, C.; Felden, J.; Fernandez Mendez, M.; Gusky, M.; Rossel, P. E.; Vedenin, A.; Wenzhoefer, F.

    2015-12-01

    The observed and predicted Climate-Carbon-Cryosphere interactions in the Arctic Ocean are likely to alter productivity and carbon fluxes of the Siberian continental margin and adjacent basins. Here, we compare field observations and samples obtained in the nineties, and recently in 2012 during the sea ice minimum, to assess decadal changes in the productivity, export and recycling of organic matter at the outer East Siberian margin. In the 90s, the Laptev Sea margin was still largely ice-covered throughout the year, and the samples and measurements obtained represent an ecological baseline against which current and future ecosystem shifts can be assessed. The POLARSTERN expedition IceArc (ARK-XXVII/3) returned in September 2012 to resample the same transects between 60 and 3400 m water depth as well as stations in the adjacent deep basins. Our results suggest that environmental changes in the past two decades, foremost sea ice thinning and retreat, have led to a substantial increase in phytodetritus sedimentation to the seafloor, especially at the lower margin and adjacent basins. This is reflected in increased benthic microbial activities, leading to higher carbon remineralization rates, especially deeper than 3000 m. Besides a relative increase in typical particle degrading bacterial types in surface sediments, bacterial community composition showed little variation between the two years, suggesting that local microbial communities can cope with changing food input. First assessments of faunal abundances suggest an increase in polychaetes,holothurians and bivalves at depth, which fits the prediction of higher productivity and particle deposition rates upon sea ice retreat. The presentation also discusses the controversial issue whether there is evidence for an Arctic-wide increase in carbon flux, or whether we are looking at a spatial shift of the productive marginal ice zone as the main factor to enhance carbon flux to the deep Siberian margin.

  11. Trophic niche shifts driven by phytoplankton in sandy beach ecosystems

    Science.gov (United States)

    Bergamino, Leandro; Martínez, Ana; Han, Eunah; Lercari, Diego; Defeo, Omar

    2016-10-01

    Stable isotopes (δ13C and δ15N) together with chlorophyll a and densities of surf diatoms were used to analyze changes in trophic niches of species in two sandy beaches of Uruguay with contrasting morphodynamics (i.e. dissipative vs. reflective). Consumers and food sources were collected over four seasons, including sediment organic matter (SOM), suspended particulate organic matter (POM) and the surf zone diatom Asterionellopsis guyunusae. Circular statistics and a Bayesian isotope mixing model were used to quantify food web differences between beaches. Consumers changed their trophic niche between beaches in the same direction of the food web space towards higher reliance on surf diatoms in the dissipative beach. Mixing models indicated that A. guyunusae was the primary nutrition source for suspension feeders in the dissipative beach, explaining their change in dietary niche compared to the reflective beach where the proportional contribution of surf diatoms was low. The high C/N ratios in A. guyunusae indicated its high nutritional value and N content, and may help to explain the high assimilation by suspension feeders at the dissipative beach. Furthermore, density of A. guyunusae was higher in the dissipative than in the reflective beach, and cell density was positively correlated with chlorophyll a only in the dissipative beach. Therefore, surf diatoms are important drivers in the dynamics of sandy beach food webs, determining the trophic niche space and productivity. Our study provides valuable insights on shifting foraging behavior by beach fauna in response to changes in resource availability.

  12. Fukushima-derived radionuclides in sediments of the Japanese Pacific Ocean coast and various Japanese water samples (seawater, tap water, and coolant water of Fukushima Daiichi reactor unit 5)

    OpenAIRE

    Shozugawa, Katsumi; Riebe, Beate; Walther, Clemens; Brandl, Alexander; Steinhauser,Georg

    2016-01-01

    We investigated Ocean sediments and seawater from inside the Fukushima exclusion zone and found radiocesium (134Cs and 137Cs) up to 800 Bq kg-1 as well as 90Sr up to 5.6 Bq kg-1. This is one of the first reports on radiostrontium in sea sediments from the Fukushima exclusion zone. Seawater exhibited contamination levels up to 5.3 Bq kg-1 radiocesium. Tap water from Tokyo from weeks after the accident exhibited detectable but harmless activities of radiocesium (well below the regulatory limit)...

  13. Fukushima-derived radionuclides in sediments of the Japanese Pacific Ocean coast and various Japanese water samples (seawater, tap water, and coolant water of Fukushima Daiichi reactor unit 5)

    OpenAIRE

    Shozugawa, Katsumi; Riebe, Beate; Walther, Clemens; Brandl, Alexander; Steinhauser,Georg

    2015-01-01

    We investigated Ocean sediments and seawater from inside the Fukushima exclusion zone and found radiocesium (134Cs and 137Cs) up to 800 Bq kg−1 as well as 90Sr up to 5.6 Bq kg−1. This is one of the first reports on radiostrontium in sea sediments from the Fukushima exclusion zone. Seawater exhibited contamination levels up to 5.3 Bq kg−1 radiocesium. Tap water from Tokyo from weeks after the accident exhibited detectable but harmless activities of radiocesium (well below the regulatory limit)...

  14. Sediment Budget Analysis; Masonboro Inlet, North Carolina

    Science.gov (United States)

    2017-08-15

    littoral sediments or sediments derived principally from the beaches, consisting of generally sandy material. Other sediments consisting of fine-grain...propagate only from the seaward boundary toward shore . It includes features such as wave generation, wave reflection, and bottom frictional dissipation...analysis. The regional shore line adopted in the study is oriented at 36.17o clockwise from north, as shown in Figure 8. Statistics were performed for

  15. Occurrence of soft sediment deformation at Dive Agar beach, west coast of India: possible record of the Indian Ocean tsunami (2004)

    Digital Repository Service at National Institute of Oceanography (India)

    Meshram, D.C.; Sangode, S.J.; Gujar, A.R.; Ambre, N.V.; Dhongle, D.; Porate, S.

    by approx.30-cm-thick intermixed beach sand and terrigenous sand (layer B1) followed by complex load structures and convolutions (8–15 cm) within a coarse sandy layer (B2). The layer B2 is scoured by terrigenous sand (layer C1) which is capped with a silty...

  16. Luminescence dating of Holocene lacustrine sediments from the southeastern Mu Us sandy land:Comparison of quartz OSL and K-feldspar pIRIR150 ages%毛乌素沙地东南缘全新世湖相地层石英和钾长石释光测年对比∗

    Institute of Scientific and Technical Information of China (English)

    冯玉静; 隆浩; 黄银洲; 王洪娇; 王乃昂; 高磊; 沈吉

    2015-01-01

    samples were well bleached before deposition, and the resultant ages of quartz fraction are reliable. For K-feldspar fraction, a new post-IR IRSL protocol measured at 150℃ ( pIRIR150 ) was used to determine the De. Dose recovery tests and lumi-nescence characteristics of K-feldspar meet the requirement well. A set of tests, such as residual test and fading test, was carried out. Residual doses of pIRIR150 signal are between-0. 2 and 0. 026 Gy, which can be considered negligible for the Holocene sedi-ments. The g-values of pIRIR150 signal (0. 55 1. 71(% /decade)) are much lower, comparing with that of IRSL50 signal, or even negligible. Thus, we propose that the use of pIRIR150 signal is able to reduce anomalous fading to a negligible level. Subse-quently, the K-feldspar pIRIR150 ages are not corrected for anomalous fading. For the three samples, the quartz ages are 11. 3 ± 0. 9, 6. 5 ± 0. 6 and 2. 7 ± 0. 2 ka BP, respectively, and the K-feldspar ages are 10. 0 ± 0. 7, 6. 9 ± 0. 5 and 2. 4 ± 0. 2 ka BP, re-spectively. Both ages from the two methods agree with each other within the error ranges. Therefore, K-feldspar pIRIR150 protocol can be applied for dating the Holocene lacustrine sediments from southeast Mu Us sandy land. Our research found a method to date the samples that their luminescence signal intensity of quartz is too low to be detected, and a geochronology to support for environ-mental changes in the Holocene, especially in the historical period ( past 2000 years) .

  17. Hurricane Sandy washover deposits on southern Long Beach Island, New Jersey

    Science.gov (United States)

    Bishop, James M.; Richmond, Bruce M.; Zaremba, Nicholas J.; Lunghino, Brent D.; Kane, Haunani H.

    2016-07-22

    Sedimentologic and topographic data from Hurricane Sandy washover deposits were collected from southern Long Beach Island, New Jersey, in order to document changes to the barrier-island beaches, dunes, and coastal wetlands caused by Hurricane Sandy and subsequent storm events. These data will provide a baseline dataset for use in future coastal change descriptive and predictive studies and assessments. The data presented here were collected as part of the U.S. Geological Survey’s Barrier Island and Estuarine Wetland Physical Change Assessment Project (http://coastal.er.usgs.gov/sandy-wetland-assessment/), which aims to assess ecological and societal vulnerability that results from long- and short-term physical changes to barrier islands and coastal wetlands. This report describes data that were collected in April 2015, approximately 2½ years after Hurricane Sandy’s landfall on October 29, 2012. During the field campaign, washover deposits were photographed and described, and sediment cores, sediment samples, and surface-elevation data were collected. Data collected during this study, including sample locations and elevations, core photographs, computed tomography scans, descriptive core logs, sediment grain-size data, and accompanying Federal Geographic Data Committee metadata, are available in the associated U.S. Geological Survey data release (Bishop and others, 2016; http://dx.doi.org/10.5066/F7PK0D7S).

  18. Revealing accumulation zones of plastic pellets in sandy beaches.

    Science.gov (United States)

    Moreira, Fabiana T; Balthazar-Silva, Danilo; Barbosa, Lucas; Turra, Alexander

    2016-11-01

    Microplastics such as pellets are reported worldwide on sandy beaches, and have possible direct and indirect impacts on the biota and physical characteristics of the habitats where they accumulate. Evaluations of their standing stock at different spatial scales generate data on levels of contamination. This information is needed to identify accumulation zones and the specific beach habitats and communities that are likely to be most affected. Standing stocks of plastic pellets were evaluated in 13 sandy beaches in São Paulo state, Brazil. The sampling strategy incorporated across-shore transects from coastal dunes and backshores, and vertical profiles of the accumulated pellets down to 1 m depth below the sediment surface. Accumulation zones were identified at regional (among beaches) and local (between compartments) scales. At the regional scale pellet density tended to increase at beaches on the central and southwestern coast, near ports and factories that produce and transport the largest amounts of pellets in the country. At the local scale coastal dunes showed larger accumulations of pellets than backshores. For both compartments pellets tended to occur deeper in areas where standing stocks were larger. Most of the pellets were concentrated from the surface down to 0.4 m depth, suggesting that organisms inhabiting this part of the sediment column are more exposed to the risks associated with the presence of pellets. Our findings shed light on the local and regional scales of spatial variability of microplastics and their consequences for assessment and monitoring schemes in coastal compartments. Copyright © 2016. Published by Elsevier Ltd.

  19. Oceanisphaera aquimarina sp. nov., Isolated from Oil-Contaminated Sediment of Ocean Coastal Area from South Korea.

    Science.gov (United States)

    Cho, Seonghyeon; Lee, Sang-Seob

    2016-11-01

    Strain S33(T) was isolated from oil-contaminated sediment of Tae-an coastal region of South Korea. Cells are aerobic, motile, Gram staining-negative, and coccoid shaped. Strain S33(T) grew optimally at the temperature of 25 °C (range of 4-40 °C), pH 6.0 (range of pH 6.0-10.0), and in the presence of 1 % (w/v) NaCl (range of 0-10 %). Ubiquinone-8 was the predominant respiratory quinone. C16:0, summed feature 3 (comprising C16:1ω7c/C16:1ω6c) and C18:1ω7c were the major fatty acids. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. Strain S33(T) showed the ability to degrade benzene, toluene, and ethylbenzene after 3 days incubation. 16S rRNA gene sequence analysis showed that the strain S33(T) was most closely related to Oceanisphaera sediminis TW92(T) (97.3 %), Oceanisphaera profunda SM1222(T) (97.2 %), and Oceanisphaera ostreae T-w6(T) (97.1 %) and <97 % with other members of the genus Oceanisphaera. The genomic DNA G+C mol% content of strain S33(T) was 51.0 mol%. Based on distinct phenotypic, genotypic, and phylogenetic analysis, strain S33(T) was proposed to represent a novel species in the genus Oceanisphaera as Oceanisphaera aquimarina sp. nov. (= KEMB 1002-058(T) = JCM 30 794(T)).

  20. Broadband Scattering from Sand and Sand/Mud Sediments with Extensive Environmental Characterization

    Science.gov (United States)

    2017-01-30

    frequency sound speed and attenuation measurements in sandy sediments with a portable velocimeter.” (4) Proceedings from the 2nd International...Bay, FL off the shore of Shell Island. The sediment consisted of the 15 cm mud layer overlying a muddy, coarse sand basement. Scattering data was...Demoulin, X., L. Guillon, and B.T. Hefner (2017), “High-frequency sound speed and attenuation measurements in sandy sediments with a portable

  1. Penetration grouting reinforcement of sandy gravel

    Institute of Scientific and Technical Information of China (English)

    YANG Ping; PENG Zhen-bin; TANG Yi-qun; PENG Wen-xiang; HE Zhong-ming

    2008-01-01

    To study the relationship between grouting effect and grouting factors, three factors (seven parameters) directionless pressure and small cycle grouting model experiment on sandy gravel was done, which was designed according to uniform design method. And regressing was applied to analysis of the test data. The two models test results indicate that when the diffusing radius of grout changes from 26 to 51 era, the grouted sandy gravel compressing strength changes fTom 2.13 to 12.30 MPa; the relationship between diffusing radius(R) and water cement ratio(m), permeability coefficient(k), grouting pressure(p), grouting time(t) is R=19.953m0.121k0.429p0.412t0.437, the relationship between compressing strength(P) and porosity(n), water cement ratio, grouting pressure, grouting time is P=0.984n0.517m-1.488p0.118t0.031.So the porosity of sandy gravel, the permeability coefficient of sandy gravel, grouting pressure, grouting time, water cement ratio are main factors to influence the grouting effect. The grouting pressure is the main factor to influence grouting diffusing radius, and the water cement ratio is the main factor to influence grouted sandy gravel compressing strength.

  2. Comparative study of vertical suspension fluxes from the water column, rates of sedimentation, and absolute masses of the bottom sediments in the White Sea basin of the Arctic Ocean

    Science.gov (United States)

    Lisitzin, A. P.; Novigatsky, A. N.; Aliev, R. A.; Shevchenko, V. P.; Klyuvitkin, A. A.; Kravchishina, M. D.

    2015-12-01

    A new approach using dispersed organic matter of the water column in sedimentation traps in comparison with the surface layer of the bottom sediments is applied for the study of marine sedimentation. This approach provides the opportunity for an in situ (by fluxes of sedimentary matter in the water column) study of modern sedimentation in the surface layers of the bottom sediments and tracing the changes in the environment and climate at a new technological level. This also allows us to choose the reverse task: to reconstruct the fluxes of the matter and chemical elements in ancient seas by the rates (or absolute masses) of sedimentation.

  3. New Insights on Long Term Geomagnetic Moment Variation from Cosmogenic Nuclide and Paleointensity Signatures along Ocean Sediment Cores.

    Science.gov (United States)

    Thouveny, N.; Bourles, D. L.; Valet, J. P.; Bassinot, F. C.; Ménabréaz, L.; Simon, Q.; Demory, F.; Valery, G.; Vidal, L.; Beaufort, L.; de Garidel-Thoron, T.

    2015-12-01

    Some numerical and experimental simulations suggest that precession might supply enough power to influence planetary dynamos. The demonstration of a causal relationship between the Earth's orbital motion and variations of the geomagnetic field intensity, would open interesting perspective for modelling the past and future geomagnetic field behaviour and its eventual relationships to past and future orbitally constrained, climatic changes. Although pristine geomagnetic signals can be extracted by filtering and stacking multiple normalized intensity records, the reconstruction of high resolution geomagnetic field variations still raises questions. Namely, significant variance at orbital frequencies in relative paleointensity (RPI) records are generally considered as clues of residual contamination by paleoclimatically induced variations of magnetic carriers size ranges or mineralogy. Such questions can be adressed using other indicators of the geomagnetic dipole moment variation, such as the cosmogenic production modulated by the magnetospheric shielding. During the MAGORB project (ANR-09-BLAN-053-001) cosmogenic nuclide geochemistry, d18O, and paleomagnetic records were constructed along thick clayey-carbonate sequences deposited in the equatorial pacific and indian oceans over the last million of years. Authigenic 10Be/9Be ratio and RPI variations generally exhibit similar ranges of oscillations. However significant offsets appear between some RPI lows and their corresponding 10Be/9Be peaks, suggesting delayed lock-in of the remanent magnetization. After transfer on time scales the new geomagnetic moment series can be compared with the PISO-1500 and SINT-2000 stacks, and with the 10Be ice core record of EPICA Dome C. These new authigenic 10Be/9Be ratio records provide new opportunities to: 1) assess the validity of high resolution RPI records, 2) evaluate address the question of the presence of orbital periods in the paleo-field geomagnetic spectrum, and 3) to

  4. 2013-2014 U.S. Geological Survey CMGP LiDAR: Post Sandy (MA, NH, RI)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — TASK NAME: New England CMGP Sandy Lidar LiDAR Data Acquisition and Processing Production Task USGS Contract No. G10PC00057 Task Order No. G13PD00796 Woolpert Order...

  5. Shorelines of the Greater Boston coastal region from the southern side of Cape Ann, Massachusetts to Sandy Neck Beach in Sandwich, Massachusetts, used in shoreline change analysis (GreaterBoston_shorelines.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  6. Digital Shoreline Analysis System version 4.1 Transects with Long-Term Rate Calculations for the Greater Boston region from the southern side of Cape Ann, Massachusetts to Sandy Neck Beach in Sandwich, Massachusetts (GreaterBoston_LT.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  7. OahuS_ST- Digital Shoreline Analysis System (DSAS) version 4.2 transects with short-term weighted linear regression rate calculations for the Oahu south region from Barbers Point to Sandy Beach, Hawaii.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  8. Shorelines of the Greater Boston coastal region from the southern side of Cape Ann, Massachusetts to Sandy Neck Beach in Sandwich, Massachusetts, used in shoreline change analysis (GreaterBoston_shorelines.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  9. Digital Shoreline Analysis System version 4.1 Transects with Long-Term Rate Calculations for the Greater Boston region from the southern side of Cape Ann, Massachusetts to Sandy Neck Beach in Sandwich, Massachusetts (GreaterBoston_LT.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  10. Digital Shoreline Analysis System version 4.1 Transects with Short-Term Rate Calculations for the Greater Boston region from the southern side of Cape Ann, Massachusetts to Sandy Neck Beach in Sandwich, Massachusetts (GreaterBoston_ST.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  11. Offshore baseline for Greater Boston coastal region from the southern side of Cape Ann, Massachusetts to Sandy Neck Beach in Sandwich, Massachusetts, generated to calculate shoreline change rates (GreaterBoston_baseline.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  12. OahuS_LT - Digital Shoreline Analysis System (DSAS) version 4.2 transects with long-term weighted linear regression rate calculations for the Oahu south region from Barbers Point to Sandy Beach, Hawaii

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  13. OahuS_ST- Digital Shoreline Analysis System (DSAS) version 4.2 transects with short-term weighted linear regression rate calculations for the Oahu south region from Barbers Point to Sandy Beach, Hawaii.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  14. Digital Shoreline Analysis System version 4.1 Transects with Long-Term Rate Calculations for the New Jersey North region from Sandy Hook to Little Egg Inlet, New Jersey (NewJerseyN_LT.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  15. Offshore baseline for Greater Boston coastal region from the southern side of Cape Ann, Massachusetts to Sandy Neck Beach in Sandwich, Massachusetts, generated to calculate shoreline change rates (GreaterBoston_baseline.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  16. OahuS_LT - Digital Shoreline Analysis System (DSAS) version 4.2 transects with long-term weighted linear regression rate calculations for the Oahu south region from Barbers Point to Sandy Beach, Hawaii

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  17. Digital Shoreline Analysis System version 4.1 Transects with Short-Term Rate Calculations for the Greater Boston region from the southern side of Cape Ann, Massachusetts to Sandy Neck Beach in Sandwich, Massachusetts (GreaterBoston_ST.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  18. Digital Shoreline Analysis System version 4.1 Transects with Short-Term Rate Calculations for the New Jersey North region from Sandy Hook to Little Egg Inlet, New Jersey (NewJerseyN_ST.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  19. Holocene cyclic climatic variations and the role of the Pacific Ocean as recorded in varved sediments from northeastern China

    Science.gov (United States)

    Chu, Guoqiang; Sun, Qing; Xie, Manman; Lin, Yuan; Shang, Wenyu; Zhu, Qingzen; Shan, Yabing; Xu, Deke; Rioual, Patrick; Wang, Luo; Liu, Jiaqi

    2014-10-01

    . Meanwhile, decreasing SST in the Okhotsk Sea may strengthen the Okhotsk high, bringing more moisture into northeastern China. We suggest that the Pacific Ocean is a main regulator for summer monsoon rainfall in northeastern China at present and at different time scales during the Holocene.

  20. Currents, temperature, conductivity, and attenuation data from moorings deployed from the ASTERIAS in the North Atlantic Ocean as part of the Current and Sediment Transport in Cape Cod Bay field program from February 10, 1986 to April 30, 1986 (NODC Accession 0058714)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A pilot winter-time study to determine the effect of winter storms in causing sediment movement at two potential dredge spoil disposal areas.

  1. [Simulation alfalfa growth in Wulanbuhe sandy region].

    Science.gov (United States)

    Bai, Wenming; Bao, Xuemei

    2002-12-01

    Based on the theories of accumulated temperature and on the physio-ecological characteristics of Medicago sativa, a simulation model for its growth under soil water stress in arid sandy region was developed. The model was mainly composed of four modules: the stage module of growth, the dynamic module of leaf area index, the accumulated module of dry matter, and the distributive module of dry matter. After simulating and calculating, the model could be used to predict the growing progress and dynamic changes of leaf area and yield for herbage in sandy region. The result shows that the application of the model to production is usually effective.

  2. Coupled Response of Bacterial Production to a Wind-induced Fall Phytoplankton Bloom and Sediment Resuspension in the Chukchi Sea Shelf, Western Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Mario Uchimiya

    2016-11-01

    Full Text Available Heterotrophic bacterial abundance and production, dissolved free amino acid (DFAA and dissolved combined amino acid (DCAA concentrations, and other microbial parameters were determined for seawater samples collected at a fixed station (maximum water depth, 56 m deployed on the Chukchi Sea Shelf, in the western Arctic Ocean, during a 16-day period in September 2013. During the investigation period, the sampling station experienced strong winds and a subsequent phytoplankton bloom, which was thought to be triggered by enhanced vertical mixing and upward nutrient fluxes. In this study, we investigated whether bacterial and dissolved amino acid parameters changed in response to these physical and biogeochemical events. Bacterial abundance and production in the upper layer increased with increasing chlorophyll a concentration, despite a concomitant decrease in seawater temperature from 3.2°C to 1.5°C. The percentage of bacteria with high nucleic acid content during the bloom was significantly higher than that during the prebloom period. The ratio of the depth-integrated (0–20 m bacterial production to primary production differed little between the prebloom and bloom period, with an overall average value of 0.14 ± 0.03 (± standard deviation, n = 8. DFAA and DCAA concentrations varied over a limited range throughout the investigation, indicating that the supply and consumption of labile dissolved amino acids were balanced. These results indicate that there was a tightly coupled, large flow of organic carbon from primary producers to heterotrophic bacteria during the fall bloom. Our data also revealed that bacterial production and abundance were high in the bottom nepheloid (low transmittance layer during strong wind events, which was associated with sediment resuspension due to turbulence near the seafloor. The impacts of fall wind events, which are predicted to become more prominent with the extension of the ice-free period, on bacterial

  3. Abyssicoccus albus gen. nov., sp. nov., a novel member of the family Staphylococcaceae isolated from marine sediment of the Indian Ocean.

    Science.gov (United States)

    Jiang, Zhao; Yuan, Chang-Guo; Xiao, Min; Tian, Xin-Peng; Khan, Inam-Ullah; Kim, Chang-Jin; Zhi, Xiao-Yang; Li, Wen-Jun

    2016-08-01

    A Gram-stain positive, aerobic, non-motile, asporogenous, coccoid shaped bacterium, designated YIM M12140(T), was isolated from a marine sediment sample collected from the Indian Ocean. Phylogenetic analysis showed that strain YIM M12140(T) forms a separate clade within the family Staphylococcaceae. Strain YIM M12140(T) shares high 16S rRNA gene sequence similarity with Macrococcus brunensis DSM 19358(T) (92.9 %). The isolate was found to grow at 0-10 % (w/v) NaCl (optimum, 2-3 %), pH 6.0-10.0 (optimum, pH 8.0) and temperature 5-40 °C (optimum, 28 °C). The polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol, one unidentified aminophospholipid and two unidentified polar lipids. The major cellular fatty acids of the strain were identified as anteiso-C15:0, -C17:0, iso-C16:0, anteiso-C19:0 and C20:0. The respiratory menaquinones were found to be MK-6 (94 %) and MK-7 (6 %). The cell wall amino acids were found to contain Lys, Ala, Glu, Gly, Asp, Ser and Thr. Whole cell sugars were identified as mannose, ribose, rhamnose, glucose, galactose and xylose. The G+C content of the genomic DNA of strain YIM M12140(T) was determined to be 42.4 mol %. Based on phenotypic, chemotaxonomic data and phylogenetic analysis, it is proposed that strain YIM M12140(T) represents a novel species of a new genus in the family Staphylococcaceae, for which the name Abyssicoccus albus gen. nov., sp. nov. is proposed. The type strain is YIM M12140(T) (= DSM 29158(T) = CCTCC AB 2014213(T)).

  4. Is these a link between eustatic variations, platform drowning, oceanic anoxic events, and ammonite faunal turnovers ? Case study of the Aptian sediments along the northern Tethyan margin

    Science.gov (United States)

    Pictet, Antoine; Föllmi, Karl; Spangenberg, Jorge

    2014-05-01

    appearance of Dufrenoyia, Eotetragonites, Aconoceras, Colombiceras, and other genera (Daupin, 2002; Dutour, 2005). A third drowning phase, reported from the latest early Aptian (late D. furcata zone), occurred with the establishment of a second emersion phase, characterised by a significant karstified discontinuity. Just above, organic-rich sediments were deposited. This third phase is marked by the complete disappearance of platforms in favour of marl deposits, and coincides with the emergence of the anoxic 'Niveau Noir level' which is considered as a document of an important phase of widespread dys- to anaerobic conditions within the Selli Episode (Föllmi, 2012). The ammonite fauna is marked by a second turnover with the replacement of Dufrenoyia, Cheloniceras, and Pseudohaploceras, by Epicheloniceras, Zucherella, Gabbioceras, and other genera (Daupin, 2002; Dutour, 2005). In conclusion, the combined effect of sea-level change and subsequent oceanic anoxia as the consequence of climatic change is a key element in the platform crises and associated important faunal turnover. References DAUPHIN L. (2002) Litho-, bio-, et chronostratigraphie comparées dans le bassin vocontien à l'Aptien. Phd Univ. des sciences et technologies - Lille I. DUTOUR, Y. (2005).- Biostratigraphie, évolution et renouvellements des ammonites de l'Aptien supérieur (Gargasien) du bassin vocontien (Sud-Est de la France).- Thèse Université Claude Bernard-Lyon 1, 302 p. (inedit) FÖLLMI, K.B. (2012).- Early Cretaceous life, climate and anoxia.- Cretaceous Research (2012), doi:10.1016/ j.cretres.2011.12.005 LARSON, R.L., ERBA, E., 1999. Onset of the mid-Cretaceous greenhouse in the BarremianeAptian: igneous events and the biological, sedimentary, and geochemical responses. Paleoceanography 14, 663-678.

  5. A Study of Variations in Atmospheric Turbulence Kinetic Energy on a Sandy Beach

    Science.gov (United States)

    Koscinski, J. S.; MacMahan, J. H.; Wang, Q.; Thornton, E. B.

    2016-12-01

    A 6-m high, meteorological tower consisting six evenly spaced ultrasonic anemometers and temperature-relative humidity sensors was deployed at the high tide line on sandy, wave-dissipative, meso-tidal beach in southern Monterey Bay, CA in October 2015. The micro-meteorology study focus is to explore the momentum fluxes and turbulent kinetic energy influenced by the interaction between an intensive wave-breaking surf zone and a sandy beach associated with onshore & cross-shore winds, diurnal heating, and differences in ocean-air temperatures. The tower was deployed for approximately 1-month and experienced diurnal wind variations and synoptic storm events with winds measuring up to 10 m/s and an air temperature range of 5-28 oC. This beach environment was found to be primarily unstable in thermal stratification indicating that the air temperature is colder than underlying surface, either the ocean or the sandy beach. The drag coefficient was found to be dependent upon the atmospheric stability. Direct-estimates of atmospheric stability were obtained with the sonic anemometer. The direct estimates are a ratio of w*/u*, where the w*, vertically scaled buoyancy velocity, is greater than u*, horizontally scaled friction velocity. Hypotheses for the enhanced buoyancy are 1) diurnal heating of the sandy beach, 2) warmer ocean temperatures relative to air temperatures, and 3) the wave breaking within the surf zone. Further exploration into these hypotheses is conducted by using vertical tower sensor pairs for estimating the temporal variability of the mechanical shear production and buoyancy production terms in turbulent kinetic energy budget. These results are part of the Coastal Land Air Sea Interaction (CLASI) experiment.

  6. 77 FR 74341 - Establishing the Hurricane Sandy Rebuilding Task Force

    Science.gov (United States)

    2012-12-14

    ... the Hurricane Sandy Rebuilding Task Force By the authority vested in me as President by the.... Hurricane Sandy made landfall on October 29, 2012, resulting in major flooding, extensive structural damage... assist the affected region. A disaster of Hurricane Sandy's magnitude merits a comprehensive...

  7. Turbidite megabeds in an Oceanic Rift Valley recording jokulhlaups of late Pleistocene glacial lakes of the western United States

    Science.gov (United States)

    Zuffa, G.G.; Normark, W.R.; Serra, F.; Brunner, C.A.

    2000-01-01

    Escanaba Trough is the southernmost segment of the Gorda Ridge and is filled by sandy turbidites locally exceeding 500 m in thickness. New results from Ocean Drilling Program (ODP) Sites 1037 and 1038 that include accelerator mass spectrometry (AMS) 14C dates and revised petrographic evaluation of the sediment provenance, combined with high-resolution seismic-reflection profiles, provide a lithostratigraphic framework for the turbidite deposits. Three fining-upward units of sandy turbidites from the upper 365 m at ODP Site 1037 can be correlated with sediment recovered at ODP Site 1038 and Deep Sea Drilling Program (DSDP) Site 35. Six AMS 14C ages in the upper 317 m of the sequence at Site 1037 indicate that average deposition rates exceeded 10 m/k.yr. between 32 and 11 ka, with nearly instantaneous deposition of one ~60-m interval of sand. Petrography of the sand beds is consistent with a Columbia River source for the entire sedimentary sequence in Escanaba Trough. High-resolution acoustic stratigraphy shows that the turbidites in the upper 60 m at Site 1037 provide a characteristic sequence of key reflectors that occurs across the floor of the entire Escanaba Trough. Recent mapping of turbidite systems in the northeast Pacific Ocean suggests that the turbidity currents reached the Escanaba Trough along an 1100-km-long pathway from the Columbia River to the west flank of the Gorda Ridge. The age of the upper fining-upward unit of sandy turbidites appears to correspond to the latest Wisconsinan outburst of glacial Lake Missoula. Many of the outbursts, or jokulhlaups, from the glacial lakes probably continued flowing as hyperpycnally generated turbidity currents on entering the sea at the mouth of the Columbia River.

  8. African dust phosphorus fertilizing the Amazon and the Atlantic Ocean is derived from marine sediments and igneous rocks - no indication for Bodélé diatomite contribution

    Science.gov (United States)

    Gross, Avner; Castido, Danilo; Pio, Casimero; Angert, Alon

    2013-04-01

    Dust eroded from West Africa is blown across the Atlantic Ocean towards the tropics and constitutes a major external source of phosphorus (P) to the Amazon and marine surface waters. It is usually assumed that the P concentration in dust is ~700 µg P g/dust based on the average concentrations in crust material. In addition, previous studies have claimed that diatomites from the Bodélé depression in Chad are a major source of P to the equatorial Atlantic Ocean and the Amazon. In this study we have utilized the oxygen isotopes in resin extractable inorganic phosphate (δ18OP) of dust particles to identify their P sources. The data presented here is from over 100 PM10 dust samples, collected during major dust events in October- April 2011 and 2012, as part of the CV-DUST project in Cape-Verde. This archipelago is located downwind of the Sahara and Sahel dust producing areas, and is thus well suited for collecting dust blown out from Africa. Air mass back trajectories computations show that the dust origin can be classified to 3 sectors: the north and west Saharan sector, south and central Saharan sector and the Sahel sector. Dust particles approaching from these 3 sectors shows distinct resin-P concentrations (in the range of 1160 µg P g/dust to 7260 µg P g/dust) and distinct δ18OP values which ranges from 7.2‰ to 21.7‰. Major elements concentrations also showed distinct pattern. Dust particles approaching from the north and west Saharan sector shows the lowest P concentrations and a δ18OP values of ~21‰ which are typical for P originating from marine sediments at the Sahara area. Dust particles from the south west Saharan sector are richest in P and have the lowest δ18OP values of 7.2‰ , which are typical for P originated from igneous source. Dust approaching from the Sahel sector shows mid-range P concentrations and δ18OP values of ~14‰ , and fall on isotopic mixing line (R2=0.91) between the dust samples with igneous and marine sedimentary

  9. Early Paleogene variations in the calcite compensation depth : New constraints using old borehole sediments from across Ninetyeast Ridge, central Indian Ocean

    NARCIS (Netherlands)

    Slotnick, B. S.; Lauretano, V.; Backman, J.; Dickens, G. R.; Sluijs, A.; Lourens, L.

    2015-01-01

    Major variations in global carbon cycling occurred between 62 and 48 Ma, and these very likely related to changes in the total carbon inventory of the ocean-atmosphere system. Based on carbon cycle theory, variations in the mass of the ocean carbon should be reflected in contemporaneous global ocean

  10. Structure and Variability of Mediterranean Outflow Water Flow Recorded in Contourite Sedimentation in the Gulf of Cadiz and west of Portugal

    Science.gov (United States)

    Flood, R. D.; Ducassou, E.; Covelli, V.; Hernandez-Molina, F. J.; Stow, D. A.; Alvarez Zarikian, C. A.

    2013-12-01

    Water exchange between the Atlantic Ocean and the Mediterranean Sea has important effects on world hydrography, and the exchange varies on both shorter and longer time scales in response to climate change, sea-level change and tectonic land movements. The modern exchange can be studied with instrumental and observational records, but the longer-term variability of climate and water exchange requires the analysis of sedimentary records. Mediterranean Outflow Water (MOW) has influenced global circulation and climate and created a number of sediment drifts along the continental slope of Iberia. MOW history has been particularly important since the reconnection of the Mediterranean and the Atlantic about 5.3 Ma ago. New information about water exchange comes through study of cores collected from Iberian margin drift deposits during IODP Exp. 339. These cores contain sediments from the last 6.2 Ma in an array of sites. Drift deposits are thick sediment accumulations formed where and when currents flow along the seabed. Drift sediments are primarily muddy but they often include coarser layers which include some silt and sand-sized material which are often termed silty or sandy contourites. Several coarser layers are being studied in detail using high-resolution grain size and CAT scanning techniques, along with the analysis of the sand fraction, supplemented with thin section, X-ray and XRF to characterize the beds and the events which created them. Initial results suggest that many beds are formed of a mixture of finer sediment, often similar in grain size to the sediment deposited before and/or after the silty or sandy contourite, and coarser sediment which often overlaps in grain size with the finer sediment. The coarser sediments may have been deposited during short episodes of higher-speed flow, and later bioturbation has mixed the two grain size populations. Grain-size grading patterns within, and sharp contacts associated with, the coarser contourite layers appear

  11. Sedimentation in a river dominated estuary

    CSIR Research Space (South Africa)

    Cooper, JAG

    1993-10-01

    Full Text Available The Mgeni Estuary on the wave dominated cast coast of South Africa occupies a narrow, bedrock confined, alluvial valley and is partially blocked at the coast by an elongate sandy barrier. Fluvial sediment extends to the barrier and marine depositon...

  12. Transitions of redox state and nutrient status in the Southern Ocean since the last glacial: Evidence from speciation analyses of C, Fe, and P in sediments at the Conrad Rise

    Science.gov (United States)

    Shimode, N.; Yamaguchi, K. E.; Ikehara, M.

    2016-12-01

    The Southern Ocean, a high-nutrient and low-chlorophyll (HNLC) region, has played an important role in regulating global climate system. The Southern Ocean became suboxic during the last glacial period ( 40 to 19 kyr ago) and changed to oxic toward Holocene. In order to elucidate changes of the seawater for its the redox state and corresponding nutrient status, we performed C, Fe and P speciation analyses of the marine sediments (COR-1bPC) recovered in 2010 at the Conrad Rise in the Southern Ocean (KH10-7 cruise). Thirty-seven samples were quantified for five P-bearing species (Pabs, PFe, Pauth, Pdet & Porg) by modified SEDEX method of Ruttenberg (1992) and four Fe-bearing species (FeHCl, Fecarb, Feox & Femag) by the method of Poulton et al. (2005). The abundance and stable isotope compositions of organic carbon were measured using EA-irMS at Kochi University. Higher abundance of Corg, Fe and P were observed in the last glacial period when compared to interglacial period. In the deglaciation period, abundance of Corg decreased but that of all P-bearing phases, FeHCl, and Feox abruptly increased to the maximum values. Fepy was only detected in the last glacial. Abundance of FeHCl was highly variable among other species. A major sink of P in the analyzed samples is found to be Pauth throughout the profile (Avg. = 0.0142 wt.%). The d13Corg values in last glacial period (Avg. = -23.63 ‰) were isotopically lighter than those in the interglacial period (Avg. = -21.73 ‰). These results suggest that primary productivity was higher in last glacial by increased supply of nutrients (Fe and P) to surface ocean, most likely due to expansion of sea ice supported by occurrence of IRD. Suppression by sea ice expansion of atmosphere-ocean interactions would have allowed CO2 to be stored in deep ocean. Retreat of the sea ice and recovery of upwelling would have increased supply of P and Fe to the surface ocean and of dissolved oxygen to the deep ocean, leading to enhanced

  13. Microplastics in coastal and marine environments of the western tropical and sub-tropical Atlantic Ocean.

    Science.gov (United States)

    Costa, Monica F; Barletta, Mário

    2015-11-01

    Microplastic pollution is a global issue. It is present even in remote and pristine coastal and marine environments, likely causing impacts of unknown scale. Microplastics are primary- and secondary-sourced plastics with diameters of 5 mm or less that are either free in the water column or mixed in sandy and muddy sediments. Since the early 1970s, they have been reported to pollute marine environments; recently, concern has increased as soaring amounts of microplastics in the oceans were detected and because the development of unprecedented processes involving this pollutant at sea is being unveiled. Coastal and marine environments of the western tropical and sub-tropical Atlantic Ocean (WTAO) are contaminated with microplastics at different quantities and from a variety of types. The main environmental compartments (water, sediments and biota) are contaminated, but the consequences are still poorly understood. Rivers and all scales of fishery activities are identified as the most likely sources of this pollutant to coastal waters; however, based on the types of microplastics observed, other maritime operations are also possible sources. Ingestion by marine biota occurs in the vertebrate groups (fish, birds, and turtles) in these environments. In addition, the presence of microplastics in plankton samples from different habitats of estuaries and oceanic islands is confirmed. The connectivity among environmental compartments regarding microplastic pollution is a new research frontier in the region.

  14. Long-term vegetation, climate and ocean dynamics inferred from a 73,500 years old marine sediment core (GeoB2107-3) off southern Brazil

    Science.gov (United States)

    Gu, Fang; Zonneveld, Karin A. F.; Chiessi, Cristiano M.; Arz, Helge W.; Pätzold, Jürgen; Behling, Hermann

    2017-09-01

    Long-term changes in vegetation and climate of southern Brazil, as well as ocean dynamics of the adjacent South Atlantic, were studied by analyses of pollen, spores and organic-walled dinoflagellate cysts (dinocysts) in marine sediment core GeoB2107-3 collected offshore southern Brazil covering the last 73.5 cal kyr BP. The pollen record indicates that grasslands were much more frequent in the landscapes of southern Brazil during the last glacial period if compared to the late Holocene, reflecting relatively colder and/or less humid climatic conditions. Patches of forest occurred in the lowlands and probably also on the exposed continental shelf that was mainly covered by salt marshes. Interestingly, drought-susceptible Araucaria trees were frequent in the highlands (with a similar abundance as during the late Holocene) until 65 cal kyr BP, but were rare during the following glacial period. Atlantic rainforest was present in the northern lowlands of southern Brazil during the recorded last glacial period, but was strongly reduced from 38.5 until 13.0 cal kyr BP. The reduction was probably controlled by colder and/or less humid climatic conditions. Atlantic rainforest expanded to the south since the Lateglacial period, while Araucaria forests advanced in the highlands only during the late Holocene. Dinocysts data indicate that the Brazil Current (BC) with its warm, salty and nutrient-poor waters influenced the study area throughout the investigated period. However, variations in the proportion of dinocyst taxa indicating an eutrophic environment reflect the input of nutrients transported mainly by the Brazilian Coastal Current (BCC) and partly discharged by the Rio Itajaí (the major river closest to the core site). This was strongly related to changes in sea level. A stronger influence of the BCC with nutrient rich waters occurred during Marine Isotope Stage (MIS) 4 and in particular during the late MIS 3 and MIS 2 under low sea level. Evidence of Nothofagus pollen

  15. Fukushima-derived radionuclides in sediments of the Japanese Pacific Ocean coast and various Japanese water samples (seawater, tap water, and coolant water of Fukushima Daiichi reactor unit 5).

    Science.gov (United States)

    Shozugawa, Katsumi; Riebe, Beate; Walther, Clemens; Brandl, Alexander; Steinhauser, Georg

    We investigated Ocean sediments and seawater from inside the Fukushima exclusion zone and found radiocesium ((134)Cs and (137)Cs) up to 800 Bq kg(-1) as well as (90)Sr up to 5.6 Bq kg(-1). This is one of the first reports on radiostrontium in sea sediments from the Fukushima exclusion zone. Seawater exhibited contamination levels up to 5.3 Bq kg(-1) radiocesium. Tap water from Tokyo from weeks after the accident exhibited detectable but harmless activities of radiocesium (well below the regulatory limit). Analysis of the Unit 5 reactor coolant (finding only (3)H and even low (129)I) leads to the conclusion that the purification techniques for reactor coolant employed at Fukushima Daiichi are very effective.

  16. Degradation of the Pesticides Mecoprop and Atrazine in Unpolluted Sandy Aquifers

    DEFF Research Database (Denmark)

    Klint, Mikala; Arvin, Erik; Jensen, Bjørn K.

    1993-01-01

    The potential for biodegradation of the pesticides mecoprop ((+/-)-2-(4-chloro-2-methyl-phenoxy)propionic acid) and atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) in an aerobic aquifer was investigated in laboratory batch experiments. The experiments were performed with groundwater...... and suspensions of groundwater and aquifer sediment collected from a pristine sandy aquifer. Following a lag period of 35 to 40 d, mecoprop in a concentration of 100 mu-g/L was degraded in 30 d in groundwater at 10 degree C. New additions of 100 to 140 mu-g mecoprop/L were degraded within a week. In suspensions...... of groundwater and aquifer sediment, mecoprop in the concentration range 75 to 300 mu-g/L was degraded in 15 d, following a lag period of less than 7 d. Experiments performed with sediments taken from different depths indicate that there was a considerable variation in the degradation potential within...

  17. An assessment of Hyalella azteca burrowing activity under laboratory sediment toxicity testing conditions.

    Science.gov (United States)

    Doig, Lorne E; Liber, Karsten

    2010-09-01

    Burrowing of the freshwater amphipod Hyalella azteca was evaluated under laboratory conditions similar to those recommended for standard sediment toxicity testing in Canada (EPS 1/RM/33; Environment Canada, 1997) and the United States (EPA/600/R-99/064; US EPA, 2000). Sediment type, time of day (light versus dark), size of animal, and the presence or absence of food were varied to assess their effects on burrowing activity. Hyalella azteca were found to burrow rapidly in fine, organic-rich sediments, but were slower to burrow in a sandy sediment. There was no increase in the number of animals occupying the sediment surface of a fine, organic-rich sediment after 4h of darkness compared to the previous 4h of light. Over a 9- to 10-d duration, a higher percentage of animals occupied the surface of the sandy sediment. The addition of food promoted burrowing in sandy sediment, as did using smaller animals. Overall, longer-duration tests involving older animals and coarse sediments may require formal observation to confirm burrowing and ensure adequate sediment exposure. The addition of food during a test may promote the burrowing of larger animals in coarse sediments, but may not be necessary in field-collected sediments that are not excessively sandy.

  18. Screening of cellulose decomposing fungi in sandy dune soil of Horqin Sandy Land

    Institute of Scientific and Technical Information of China (English)

    ShaoKun Wang; XueYong Zhao; XiaoAn Zuo; XinPing Liu; Hao Qu; Wei Mao; JianYing Yun

    2015-01-01

    Cellulose decomposing fungi play an important role in litter decomposition and are decisive in nutrient cycling in sandy land ecosystems. Thirty-one strains were isolated to select efficient cellulose decomposers, and four efficient cellulose decomposing fungi (NM3-1, NM3-2, NM3-3, and NM3-4) were screened using a CMC (carboxymethyl cellulose) carbon source in dune soil of Horqin Sandy Land. They were identified as Asperigillus calidoustus, Fusarium oxysporum, Fusarium solani, and Hypocrea lixii by rDNA-ITS molecular biological methods. Cloth decomposition rates were 15.71%, 15.89%, 17.29%, and 17.89%by the four efficient decomposers incubated for 30 days, respectively. Screening of efficient cellulose decomposers can not only increase the dune soil functional microbe bank, but can also accelerate litter decom-position and available nutrient input in the Horqin Sandy Land.

  19. Atmospheric significance of aeolian salts in the sandy deserts of northwestern China

    Directory of Open Access Journals (Sweden)

    B.-Q. Zhu

    2015-12-01

    Full Text Available Large sandy deserts in the middle latitudes of northwestern China were investigated for soluble salt variations in modern and ancient aeolian sediments, aiming to explore the environmental significance of "aeolian salts". Results revealed that aeolian salt variations have a clear relationship with the changing meridional and zonal gradients of the desert locations and the aeolian differentiation effect, but are weakly linked to local geological conditions. It suggests that the natural system of aeolian salts is hydrologically open and the chemistry of the parent brines are different from that predicted for hydrologically closed systems. Atmospheric depositions of water-soluble chemical species are an important process/source contributing to aeolian salt. Sequential variations of soluble salts in sedimentary profiles interbedded with aeolian and non-aeolian deposits and their palaeoenvironmental implications in the hinterland areas of these deserts were further evaluated, based on the constraints of OSL dating and radiocarbon dating data. The results indicate that the inorganic salts may be a latent geoproxy in revealing regional palaeoclimatic changes in desert areas for the sediments deposited under onefold depositional environment, but the interpretation should be more careful for the sediments deposited under diverse depositional conditions. This study presents the evidence of atmospheric origin of aeolian salt in sandy deserts, with limited climatic significance in palaeoenvironmental reconstruction.

  20. Influence of Particle Shape on Drag Coefficient for Commonly Occuring Sandy Particles in Coastal Areas

    Directory of Open Access Journals (Sweden)

    Chitra Arora

    2010-06-01

    Full Text Available A well defined relationship connecting settling velocity with sediment geometry and ambient properties is an essential pre-requisite for coastal and hydraulic engineering studies. An established relationship for settling velocity of sandy particles assuming spherical shape geometry is available in the literature. In reality, the sediment particles need not be spherical at all times, which influences settling velocity that is strongly biased to the drag coefficient. Based on quantitative comparison with measured data collected at Oahu Islands located in the Hawaiian archipelago, USA this work provides a relationship between drag coefficient and particle shape factor for sand grains viz; sand, sandy loam and fine sandy loam typically found in coastal environment (typical size ranges from 0.05 to 2.0 mm. The particle Reynolds number and shape factor are evaluated for each grain. The drag coefficient evaluated as function of nominal diameter and Reynolds number show a positive correlation over a wide range of shape factors used in this study. A comprehensive correlation has been developed of the drag coefficient for non-spherical particles as a function of Reynolds number and particle shape. Further a regression analysis was performed on the functional dependence of drag coefficient on particle shape. Based on this study, it could be advocated the validity of Krumbien shape factor holds well for the above characterized grain size and various particle shapes considered. Hence, the settling velocity of particles has a functional dependence on estimated drag coefficient with important implications for modeling sediment transport and swash zone hydrodynamics.

  1. Predominance of Viable Spore-Forming Piezophilic Bacteria in High-Pressure Enrichment Cultures from ~1.5 to 2.4 km-Deep Coal-Bearing Sediments below the Ocean Floor

    Science.gov (United States)

    Fang, Jiasong; Kato, Chiaki; Runko, Gabriella M.; Nogi, Yuichi; Hori, Tomoyuki; Li, Jiangtao; Morono, Yuki; Inagaki, Fumio

    2017-01-01

    Phylogenetically diverse microorganisms have been observed in marine subsurface sediments down to ~2.5 km below the seafloor (kmbsf). However, very little is known about the pressure-adapted and/or pressure-loving microorganisms, the so called piezophiles, in the deep subseafloor biosphere, despite that pressure directly affects microbial physiology, metabolism, and biogeochemical processes of carbon and other elements in situ. In this study, we studied taxonomic compositions of microbial communities in high-pressure incubated sediment, obtained during the Integrated Ocean Drilling Program (IODP) Expedition 337 off the Shimokita Peninsula, Japan. Analysis of 16S rRNA gene-tagged sequences showed that members of spore-forming bacteria within Firmicutes and Actinobacteria were predominantly detected in all enrichment cultures from ~1.5 to 2.4 km-deep sediment samples, followed by members of Proteobacteria, Acidobacteria, and Bacteroidetes according to the sequence frequency. To further study the physiology of the deep subseafloor sedimentary piezophilic bacteria, we isolated and characterized two bacterial strains, 19R1-5 and 29R7-12, from 1.9 and 2.4 km-deep sediment samples, respectively. The isolates were both low G+C content, gram-positive, endospore-forming and facultative anaerobic piezophilic bacteria, closely related to Virgibacillus pantothenticus and Bacillus subtilis within the phylum Firmicutes, respectively. The optimal pressure and temperature conditions for growth were 20 MPa and 42°C for strain 19R1-5, and 10 MPa and 43°C for strain 29R7-12. Bacterial (endo)spores were observed in both the enrichment and pure cultures examined, suggesting that these piezophilic members were derived from microbial communities buried in the ~20 million-year-old coal-bearing sediments after the long-term survival as spores and that the deep biosphere may host more abundant gram-positive spore-forming bacteria and their spores than hitherto recognized. PMID:28220112

  2. Turbidite Megabeds in an Oceanic Rift Valley Recording Jökulhlaups of Late Pleistocene Glacial Lakes of the Western United States.

    Science.gov (United States)

    Zuffa; Normark; Serra; Brunner

    2000-05-01

    Escanaba Trough is the southernmost segment of the Gorda Ridge and is filled by sandy turbidites locally exceeding 500 m in thickness. New results from Ocean Drilling Program (ODP) Sites 1037 and 1038 that include accelerator mass spectrometry (AMS) 14C dates and revised petrographic evaluation of the sediment provenance, combined with high-resolution seismic-reflection profiles, provide a lithostratigraphic framework for the turbidite deposits. Three fining-upward units of sandy turbidites from the upper 365 m at ODP Site 1037 can be correlated with sediment recovered at ODP Site 1038 and Deep Sea Drilling Program (DSDP) Site 35. Six AMS 14C ages in the upper 317 m of the sequence at Site 1037 indicate that average deposition rates exceeded 10 m/k.yr. between 32 and 11 ka, with nearly instantaneous deposition of one approximately 60-m interval of sand. Petrography of the sand beds is consistent with a Columbia River source for the entire sedimentary sequence in Escanaba Trough. High-resolution acoustic stratigraphy shows that the turbidites in the upper 60 m at Site 1037 provide a characteristic sequence of key reflectors that occurs across the floor of the entire Escanaba Trough. Recent mapping of turbidite systems in the northeast Pacific Ocean suggests that the turbidity currents reached the Escanaba Trough along an 1100-km-long pathway from the Columbia River to the west flank of the Gorda Ridge. The age of the upper fining-upward unit of sandy turbidites appears to correspond to the latest Wisconsinan outburst of glacial Lake Missoula. Many of the outbursts, or jökulhlaups, from the glacial lakes probably continued flowing as hyperpycnally generated turbidity currents on entering the sea at the mouth of the Columbia River.

  3. Can sandy beach molluscs show an endogenously controlled circatidal migrating behaviour? Hints from a swash rig experiment

    OpenAIRE

    Vanagt, T.; Vincx, M.; Degraer, S.

    2008-01-01

    Many macrofaunal species inhabiting exposed sandy beaches are dependent on the swash for their nutrition and for migration and are highly adapted to the harsh physical conditions of the swash. The most important physical factors that determine the distribution and behaviour of swash related fauna, next to the swash itself, are sediment grain size and beach slope. Crucial swash parameters are swash period and swash velocity. Studying the influence of these factors on the animals in the field i...

  4. 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

  5. Threats to sandy beach ecosystems: A review

    Science.gov (United States)

    Defeo, Omar; McLachlan, Anton; Schoeman, David S.; Schlacher, Thomas A.; Dugan, Jenifer; Jones, Alan; Lastra, Mariano; Scapini, Felicita

    2009-01-01

    We provide a brief synopsis of the unique physical and ecological attributes of sandy beach ecosystems and review the main anthropogenic pressures acting on the world's single largest type of open shoreline. Threats to beaches arise from a range of stressors which span a spectrum of impact scales from localised effects (e.g. trampling) to a truly global reach (e.g. sea-level rise). These pressures act at multiple temporal and spatial scales, translating into ecological impacts that are manifested across several dimensions in time and space so that today almost every beach on every coastline is threatened by human activities. Press disturbances (whatever the impact source involved) are becoming increasingly common, operating on time scales of years to decades. However, long-term data sets that describe either the natural dynamics of beach systems or the human impacts on beaches are scarce and fragmentary. A top priority is to implement long-term field experiments and monitoring programmes that quantify the dynamics of key ecological attributes on sandy beaches. Because of the inertia associated with global climate change and human population growth, no realistic management scenario will alleviate these threats in the short term. The immediate priority is to avoid further development of coastal areas likely to be directly impacted by retreating shorelines. There is also scope for improvement in experimental design to better distinguish natural variability from anthropogenic impacts. Sea-level rise and other effects of global warming are expected to intensify other anthropogenic pressures, and could cause unprecedented ecological impacts. The definition of the relevant scales of analysis, which will vary according to the magnitude of the impact and the organisational level under analysis, and the recognition of a physical-biological coupling at different scales, should be included in approaches to quantify impacts. Zoning strategies and marine reserves, which have not

  6. LDEO Carbonate Data - CaCO3 Percentages for 328 Sediments Cores, Principally from The Atlantic Ocean Spanning 100,000 to 200,000 Years bp

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — LDEO Carbonate data were compiled under the direction of A. Esmay and W.F. Ruddiman at the Lamont-Doherty Earth Observatory of Columbia University. Data include...

  7. Surficial sediment distribution interpretation of the sidescan sonar mosaic of National Oceanic and Atmospheric Administration (NOAA) survey H11043 off Branford, Connecticut

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey, in cooperation with the National Oceanic and Atmospheric Administration and the Connecticut Department of Environmental Protection, has...

  8. Seafloor Surficial Sediments (Deck 41)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The National Geophysical Data Center (NGDC) "Deck41" database contains surficial sediment descriptions for over 36,000 seafloor samples worldwide. The file was begun...

  9. NorthShoreB_shorelines_uncertainty.dbf - uncertainty table for lidar-derived shorelines used when calculating rates in the Digital Shoreline Analysis System software Renamed from: GreaterBoston_shorelines_uncertainty.dbf for the Greater Boston region from the southern side of Cape Ann, Massachusetts to Sandy Neck Beach in Sandwich, Massachusetts

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  10. SouthShore_shorelines_uncertainty.dbf - uncertainty table for lidar-derived shorelines used when calculating rates in the Digital Shoreline Analysis System software Renamed from: NewEnglandN_shorelines_uncertainty.dbf for the Greater Boston region from the southern side of Cape Ann, Massachusetts to Sandy Neck Beach in Sandwich, Massachusetts

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  11. Climate-change impacts on sandy-beach biota: crossing a line in the sand.

    Science.gov (United States)

    Schoeman, David S; Schlacher, Thomas A; Defeo, Omar

    2014-08-01

    Sandy ocean beaches are iconic assets that provide irreplaceable ecosystem services to society. Despite their great socioeconomic importance, beaches as ecosystems are severely under-represented in the literature on climate-change ecology. Here, we redress this imbalance by examining whether beach biota have been observed to respond to recent climate change in ways that are consistent with expectations under climate change. We base our assessments on evidence coming from case studies on beach invertebrates in South America and on sea turtles globally. Surprisingly, we find that observational evidence for climate-change responses in beach biota is more convincing for invertebrates than for highly charismatic turtles. This asymmetry is paradoxical given the better theoretical understanding of the mechanisms by which turtles are likely to respond to changes in climate. Regardless of this disparity, knowledge of the unique attributes of beach systems can complement our detection of climate-change impacts on sandy-shore invertebrates to add rigor to studies of climate-change ecology for sandy beaches. To this end, we combine theory from beach ecology and climate-change ecology to put forward a suite of predictive hypotheses regarding climate impacts on beaches and to suggest ways that these can be tested. Addressing these hypotheses could significantly advance both beach and climate-change ecology, thereby progressing understanding of how future climate change will impact coastal ecosystems more generally.

  12. Numerical modeling of the effects of Hurricane Sandy and potential future hurricanes on spatial patterns of salt marsh morphology in Jamaica Bay, New York City

    Science.gov (United States)

    Wang, Hongqing; Chen, Qin; Hu, Kelin; Snedden, Gregg A.; Hartig, Ellen K.; Couvillion, Brady R.; Johnson, Cody L.; Orton, Philip M.

    2017-03-29

    The salt marshes of Jamaica Bay, managed by the New York City Department of Parks & Recreation and the Gateway National Recreation Area of the National Park Service, serve as a recreational outlet for New York City residents, mitigate flooding, and provide habitat for critical wildlife species. Hurricanes and extra-tropical storms have been recognized as one of the critical drivers of coastal wetland morphology due to their effects on hydrodynamics and sediment transport, deposition, and erosion processes. However, the magnitude and mechanisms of hurricane effects on sediment dynamics and associated coastal wetland morphology in the northeastern United States are poorly understood. In this study, the depth-averaged version of the Delft3D modeling suite, integrated with field measurements, was utilized to examine the effects of Hurricane Sandy and future potential hurricanes on salt marsh morphology in Jamaica Bay, New York City. Hurricane Sandy-induced wind, waves, storm surge, water circulation, sediment transport, deposition, and erosion were simulated by using the modeling system in which vegetation effects on flow resistance, surge reduction, wave attenuation, and sedimentation were also incorporated. Observed marsh elevation change and accretion from a rod surface elevation table and feldspar marker horizons and cesium-137- and lead-210-derived long-term accretion rates were used to calibrate and validate the wind-waves-surge-sediment transport-morphology coupled model.The model results (storm surge, waves, and marsh deposition and erosion) agreed well with field measurements. The validated modeling system was then used to detect salt marsh morphological change due to Hurricane Sandy across the entire Jamaica Bay over the short-term (for example, 4 days and 1 year) and long-term (for example, 5 and 10 years). Because Hurricanes Sandy (2012) and Irene (2011) were two large and destructive tropical cyclones which hit the northeast coast, the validated coupled

  13. Hurricane Sandy science plan: coastal impact assessments

    Science.gov (United States)

    Stronko, Jakob M.

    2013-01-01

    Hurricane Sandy devastated some of the most heavily populated eastern coastal areas of the Nation. With a storm surge peaking at more than 19 feet, the powerful landscape-altering destruction of Hurricane Sandy is a stark reminder of why the Nation must become more resilient to coastal hazards. In response to this natural disaster, the U.S. Geological Survey (USGS) received a total of $41.2 million in supplemental appropriations from the Department of the Interior (DOI) to support response, recovery, and rebuilding efforts. These funds support a science plan that will provide critical scientific information necessary to inform management decisions for recovery of coastal communities, and aid in preparation for future natural hazards. This science plan is designed to coordinate continuing USGS activities with stakeholders and other agencies to improve data collection and analysis that will guide recovery and restoration efforts. The science plan is split into five distinct themes: coastal topography and bathymetry, impacts to coastal beaches and barriers, impacts of storm surge, including disturbed estuarine and bay hydrology, impacts on environmental quality and persisting contaminant exposures, impacts to coastal ecosystems, habitats, and fish and wildlife. This fact sheet focuses assessing impacts to coastal beaches and barriers.

  14. Event sedimentation in low-latitude deep-water carbonate basins, Anegada passage, northeast Caribbean

    Science.gov (United States)

    Chaytor, Jason D.; ten Brink, Uri S.

    2015-01-01

    The Virgin Islands and Whiting basins in the Northeast Caribbean are deep, structurally controlled depocentres partially bound by shallow-water carbonate platforms. Closed basins such as these are thought to document earthquake and hurricane events through the accumulation of event layers such as debris flow and turbidity current deposits and the internal deformation of deposited material. Event layers in the Virgin Islands and Whiting basins are predominantly thin and discontinuous, containing varying amounts of reef- and slope-derived material. Three turbidites/sandy intervals in the upper 2 m of sediment in the eastern Virgin Islands Basin were deposited between ca. 2000 and 13 600 years ago, but do not extend across the basin. In the central and western Virgin Islands Basin, a structureless clay-rich interval is interpreted to be a unifite. Within the Whiting Basin, several discontinuous turbidites and other sand-rich intervals are primarily deposited in base of slope fans. The youngest of these turbidites is ca. 2600 years old. Sediment accumulation in these basins is low (−1) for basin adjacent to carbonate platform, possibly due to limited sediment input during highstand sea-level conditions, sediment trapping and/or cohesive basin walls. We find no evidence of recent sediment transport (turbidites or debris flows) or sediment deformation that can be attributed to the ca. M7.2 1867 Virgin Islands earthquake whose epicentre was located on the north wall of the Virgin Islands Basin or to recent hurricanes that have impacted the region. The lack of significant appreciable pebble or greater size carbonate material in any of the available cores suggests that submarine landslide and basin-wide blocky debris flows have not been a significant mechanism of basin margin modification in the last several thousand years. Thus, basins such as those described here may be poor recorders of past natural hazards, but may provide a long-term record of past oceanographic

  15. 78 FR 32296 - Second Allocation of Public Transportation Emergency Relief Funds in Response to Hurricane Sandy...

    Science.gov (United States)

    2013-05-29

    ... Response to Hurricane Sandy: Response, Recovery & Resiliency AGENCY: Federal Transit Administration (FTA... recipients most severely affected by Hurricane Sandy: the Metropolitan Transportation Authority, New Jersey... Federal Register notice, bringing the total amount of Hurricane Sandy Emergency Relief funds allocated...

  16. Organic matter dynamics in coarse sandy calcareous soils

    NARCIS (Netherlands)

    Pronk, A.A.; Reuler, van H.

    2011-01-01

    The decomposition of organic matter in coarse sandy calcareous soils (beach sand) is thought to be much higher than in acid fine sandy soils but relatively little research is performed on these soils. Laboratory incubation experiments in which the release of soil carbon (C) is determined may overest

  17. Dynamics of Small-Scale Topographic Heterogeneity in European Sandy Salt Marshes

    Directory of Open Access Journals (Sweden)

    Kelly Elschot

    2016-03-01

    Full Text Available Heterogeneity can boost biodiversity, as well as increase the resilience of an ecosystem to changing environmental conditions; therefore, it is important to understand how topographic heterogeneity in ecosystems is formed. Sandy tidal marshes have a repetitive pattern of higher elevated hummocks surrounded by lower elevated depressions, representing topographic heterogeneity at the scale of a few square meters. The aims of this study were to determine when this topographic heterogeneity forms, how it is structured, and whether it persists during marsh development. The soil topography of marshes consists of coarse-grained sediment formed before marsh vegetation development, with an overlaying fine-grained sediment layer formed after initial marsh development. To gain insight into the formation of topographic heterogeneity, we studied the underlying soil topography of four European sandy marshes, where topographic heterogeneity at a scale of a few square meters was present. The differences in elevation between hummocks and depressions can either be caused by heterogeneity in the coarse-grained sediment or by heterogeneity in the top layer containing the fine-grained sediment. Our results showed that the largest percentage of elevational differences between hummocks and depressions could be attributed to heterogeneity in the underlying coarse-grained substratum. Therefore, we conclude that the patterns in all four marshes were primarily formed before marsh development, before fine-grained sediment was deposited on top of the coarse-grained sediment. However, a smaller percentage of the elevational difference between hummocks and depressions can also be explained by the presence of thicker fine-grained sediment layers on top of hummocks compared with depressions. This implies that marsh accretion rates were higher on hummocks compared with depressions. However, this result was limited to very early stages of marsh development, as marsh accretion

  18. Microhabitat use by two rocky shore gastropods in an intertidal sandy substrate with rocky fragments.

    Science.gov (United States)

    Turra, A; Denadai, M R

    2006-02-01

    Sandy beaches in some areas of the São Sebastião Channel in southeastern Brazil have unremittingly undergone a variety of impacts, including the deposition of rock fragments in the intertidal region. Consequently, these environments support a rich fauna comprising both sandy beach and rocky shore organisms. Two rocky shore gastropods, Tegula viridula and Morula nodulosa, are particularly abundant in such environments. An evaluation of the use of microhabitats by these two species revealed that they occupy the available microhabitats in different proportions and the presence of one species is associated with the absence of the other. Morula nodulosa is randomly dispersed, occupying mostly areas with rock fragments covered with sediment and branching brown algae. Tegula viridula shows a clumped dispersion associated with the patchiness of the microhabitats used: the presence of encrusting green algae and absence of sediment and branching brown algae covering the rocks. These findings suggest T. viridula has a lower tolerance than M. nodulosa to sand inundation of the rocky fragments, a stochastic event common to the environment in question.

  19. Microhabitat use by two rocky shore gastropods in an intertidal sandy substrate with rocky fragments

    Directory of Open Access Journals (Sweden)

    A. Turra

    Full Text Available Sandy beaches in some areas of the São Sebastião Channel in southeastern Brazil have unremittingly undergone a variety of impacts, including the deposition of rock fragments in the intertidal region. Consequently, these environments support a rich fauna comprising both sandy beach and rocky shore organisms. Two rocky shore gastropods, Tegula viridula and Morula nodulosa, are particularly abundant in such environments. An evaluation of the use of microhabitats by these two species revealed that they occupy the available microhabitats in different proportions and the presence of one species is associated with the absence of the other. Morula nodulosa is randomly dispersed, occupying mostly areas with rock fragments covered with sediment and branching brown algae. Tegula viridula shows a clumped dispersion associated with the patchiness of the microhabitats used: the presence of encrusting green algae and absence of sediment and branching brown algae covering the rocks. These findings suggest T. viridula has a lower tolerance than M. nodulosa to sand inundation of the rocky fragments, a stochastic event common to the environment in question.

  20. Nature, distribution and origin of clay minerals in grain size fractions of sediments from manganese nodule field, Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Nath, B.N.

    -rich montmorillonite). Montmorillonite is present in all size fractions of sediments, whereas Fe-rich montmorillonite is present only in 1 and 1-2 mu m fractions of siliceous and 1 mu m fractions of pelagic clays. Distribution of clay minerals suggests that illite...

  1. Spatial distribution of calcareous dinoflagellate cysts in surface sediments of the Atlantic Ocean between 13 degrees N and 36 degrees S.

    Science.gov (United States)

    Zonneveld; Brune; Willems

    2000-09-01

    To enhance the limited information available about the palaeo-ecological significance of calcareous dinoflagellates, we have studied their lateral distribution in surface sediments of the equatorial and south Atlantic between 13 degrees N and 36 degrees S. Calcareous dinoflagellate cysts appear to be widely distributed throughout the studied area. In the surface sediments, concentrations (cyst per gram dry sediment) of the vegetative stage Thoracosphaera heimii are generally higher than that of the (presumably) calcareous resting cysts. Distribution patterns in surface sediments of Orthopithonella granifera (Fütterer) Keupp and Versteegh, Rhabdothorax spp. Kamptner., Sphaerodinella albatrosiana (Kamptner) Keupp and Versteegh S. albatrosiana praratabulated, Sphaerodinella tuberosa var. 1 (Kamptner) Keupp and Versteegh and S. tuberosa var. 2 and the ratios between these species have been compared with temperature, salinity, density and stratification gradients in the upper water column. Rhabdothorax spp. is characteristically present in sediments of more temperate regions characterized by high seasonality. Dinoflagellates producing these cysts are able to tolerate high nutrient concentrations, and mixing of the water column. S. albatrosiana is abundant in regions characterized by high sea surface temperatures and oligotrophic surface water conditions. In contrast, the distribution of S. tuberosa var. 2 is negatively related to temperature. The other cyst species did not show a characteristic pattern in relation to the studied environmental gradients.The ratio of Sphaerodinella tuberosa var. 2 to Orthopithonella granifera can be used for reconstructing the presence of stratification in the upper 50m of the water column, whereas the ratios of S. tuberosa var. 2 to Sphaerodinella albatrosiana and of O. granifera to Rhabdothorax spp. might be used for palaeotemperature reconstructions. Calcareous dinoflagellate cysts are abundant in oligotrophic areas and may be useful

  2. Effects of Super Strom Sandy on Depositional Environments Offshore Long Island, New York

    Science.gov (United States)

    Hosseini, P.; McHugh, C. M.; Christensen, B. A.; Dutton, J.; Brownawell, B.; Gurung, D.

    2013-12-01

    Hurricane Sandy's landfall affected the coastlines over a broad swath of mid-Atlantic including New York, New Jersey, Delaware, Maryland, Virginia, and North Carolina. The effects included breaching, overwash and erosion of barrier islands, some of which are heavily populated and sustained extensive damage. The peak storm-tide elevation produced by Hurricane Sandy measured by USGS stations in Jamaica Bay was about 3.5 m, 1.4 m more than the historical peak-water level elevations in the same area. As part of a National Science Foundation RAPID response we sampled the sediment in West Bay, Middle Bay, East Bay, Jones Inlet and Reynolds Channel of Long Island, New York from the R/V Pritchard. The sediment sampling took place 4 months after the storm and prior to any similar large storms. The sampling strategy was designed to characterize the post-storm sedimentation in distinct depositional environments. In this survey 156 grab samples were recovered from areas, many of which had been sampled prior to the storm. The samples were analyzed for grain size variability, short-lived radioisotopes and x-ray fluorescence elemental analyses. Google Earth images from before and after the storm reveal moderate to severe erosion and overwash of the dunes in Jones inlet, and Middle and East Bays. The Long Beach barrier island tidal marshes were submerged for several days post Sandy and underwent severe erosion. The storm surge brought from offshore a layer of coarse sand that was deposited over mussel beds. Most of the mussels were dead indicative of the strength of the waves. Be-7 concentrations allowed tracking the path of the storm from the bays and inlets, to the offshore. Some of the highest Be-7 concentrations ever detected in the local estuaries: 5,329, 4,955 and 4,553 pCi/kg were measured in West Bay and Middle Bay Channels. Additionally, unusually high Be-7 concentrations of 2,130 pCi/kg were recorded ~5.24 km offshore from Long Beach barrier island four months after the

  3. Morphological impacts of extreme storms on sandy beaches and barriers

    Science.gov (United States)

    Morton, R.A.; Sallenger, A.H.

    2003-01-01

    Historical extreme storms that struck the Gulf Coast and Atlantic Coast regions of the United States caused several different styles of morphological response and resulted in a wide range of washover penetration distances. The post- storm erosional responses included dune scarps, channel incisions, and washouts, whereas depositional responses included perched fans, washover terraces, and sheetwash lineations. Maximum inland extent of washover penetration ranged from approximately 100 to 1000 m and estimated sediment volumes associated with these deposits ranged from about 10 to 225 m 3/m of beach. Unusual styles of morphological response (sheetwash lineations and incised channels) and maximum washover penetration distances are closely correlated, and they also correspond to storm intensity as denned by the Saffir-Simpson wind-speed scale. The regional morphological responses and washover penetration distances are controlled primarily by the interactions among heights and durations of storm surge relative to adjacent land elevations, differences in water levels between the ocean and adjacent lagoon, constructive and destructive interference of storm waves, and alongshore variations in nearshore bathymetry. For barrier segments that are entirely submerged during the storm, impacts can be enhanced by the combined influences of shallow water depths and organized flow within the wind field. The greatest washover penetrations and sediment accumulations are products of shallow water, confined flow, and high wind stress. Transport and deposition of washover sediments across barrier islands and into the adjacent lagoon are common processes along the Gulf of Mexico but not along the western Atlantic Ocean. This fundamental difference in storm impact underscores how microtidal and mesotidal barriers respond respectively to extreme storms, and provides insight into how different types of barrier islands will likely respond to future extreme storms and to a relative rise in sea

  4. Rediscovering community--reflections after Hurricane Sandy.

    Science.gov (United States)

    See, Sharon

    2013-01-01

    Hoboken, New Jersey, is a town of 50,000 residents located across the Hudson River from New York City. Most of Hoboken's infrastructure was compromised during Hurricane Sandy as a result of flooding and power outages that rendered many businesses inoperable, including all of the pharmacies in town. Despite a focus on emergency preparedness since Hurricane Katrina and 9/11, there were no contingencies in place to facilitate and assess the medication needs of the community in the event of a natural disaster. This essay describes how the author rediscovered the meaning of community, and through working with colleagues in other health care disciplines and non-health care volunteers, provided care to patients in suboptimal circumstances.

  5. Nitrate reduction in an unconfined sandy aquifer

    DEFF Research Database (Denmark)

    Postma, Diederik Jan; Boesen, Carsten; Kristiansen, Henning;

    1991-01-01

    Nitrate distribution and reduction processes were investigated in an unconfined sandy aquifer of Quaternary age. Groundwater chemistry was studied in a series of eight multilevel samplers along a flow line, deriving water from both arable and forested land. Results show that plumes of nitrate...... processes of O2 and NO3- occur at rates that are fast compared to the rate of downward water transport. Nitrate-contaminated groundwater contains total contents of dissolved ions that are two to four times higher than in groundwater derived from the forested area. The persistence of the high content...... of total dissolved ions in the NO3- free anoxic zone indicates the downward migration of contaminants and that active nitrate reduction is taking place. Nitrate is apparently reduced to N2 because both nitrite and ammonia are absent or found at very low concentrations. Possible electron donors...

  6. 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....

  7. Spatial distribution of organochlorine contaminants in soil, sediment, and fish in Bikini and Enewetak Atolls of the Marshall Islands, Pacific Ocean.

    Science.gov (United States)

    Wang, Jun; Caccamise, Sarah A L; Wu, Liejun; Woodward, Lee Ann; Li, Qing X

    2011-08-01

    Several nuclear tests were performed at Enewetak and Bikini Atolls in the Marshall Islands between 1946 and 1958. The events at Bikini Atoll involved several ships that were tested for durability during nuclear explosions, and 24 vessels now rest on the bottom of the Bikini lagoon. Nine soil samples were collected from different areas on the two islands of the atoll, and eighteen sediment, nine fish, and one lobster were collected in the vicinity of the sunken ships. Organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polychlorinated terphenyls (PCTs) in these samples were analyzed using gas chromatography/ion trap mass spectrometry (GC/ITMS). The average recoveries ranged from 78% to 104% for the different PCB congeners. The limits of detection (LOD) for PCBs, PCTs, DDE, DDT, and dieldrin ranged 10-50 pg g(-1). Some fish from Enewetak contained PCBs at a concentration range of 37-137 ng g(-1), dry weight (dw), and most of the soils from Enewetak showed evidence of PCBs (22-392 ng g(-1)dw). Most of the Bikini lagoon sediment samples contained PCBs, and the highest was the one collected from around the Saratoga, an aircraft carrier (1555 ng g(-1)dw). Some of the fish samples, most of the soil samples, and only one of the sediment samples contained 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (DDE) and PCBs. In addition to PCBs, the soils from Enewetak Atoll contained PCTs. PCTs were not detected in the sediment samples from Bikini Atoll. The results suggest local pollution sources of PCBs, PCTs, and OCPs.

  8. Geomorphic response of the Sandy River, Oregon, to removal of Marmot Dam

    Science.gov (United States)

    Major, Jon J.; O'Connor, Jim E.; Podolak, Charles J.; Keith, Mackenzie K.; Grant, Gordon E.; Spicer, Kurt R.; Pittman, Smokey; Bragg, Heather M.; Wallick, J. Rose; Tanner, Dwight Q.; Rhode, Abagail; Wilcock, Peter R.

    2012-01-01

    The October 2007 breaching of a temporary cofferdam constructed during removal of the 15-meter (m)-tall Marmot Dam on the Sandy River, Oregon, triggered a rapid sequence of fluvial responses as ~730,000 cubic meters (m3) of sand and gravel filling the former reservoir became available to a high-gradient river. Using direct measurements of sediment transport, photogrammetry, airborne light detection and ranging (lidar) surveys, and, between transport events, repeat ground surveys of the reservoir reach and channel downstream, we monitored the erosion, transport, and deposition of this sediment in the hours, days, and months following breaching of the cofferdam. Rapid erosion of reservoir sediment led to exceptional suspended-sediment and bedload-sediment transport rates near the dam site, as well as to elevated transport rates at downstream measurement sites in the weeks and months after breaching. Measurements of sediment transport 0.4 kilometers (km) downstream of the dam site during and following breaching show a spike in the transport of fine suspended sediment within minutes after breaching, followed by high rates of suspended-load and bedload transport of sand. Significant transport of gravel bedload past the measurement site did not begin until 18 to 20 hours after breaching. For at least 7 months after breaching, bedload transport rates just below the dam site during high flows remained as much as 10 times above rates measured upstream of the dam site and farther downstream. The elevated sediment load was derived from eroded reservoir sediment, which began eroding when a meters-tall knickpoint migrated about 200 m upstream in the first hour after breaching. Rapid knickpoint migration triggered vertical incision and bank collapse in unconsolidated sand and gravel, leading to rapid channel widening. Over the following days and months, the knickpoint migrated upstream more slowly, simultaneously decreasing in height and becoming less distinct. Within 7 months

  9. Landscape Visual Quality and Meiofauna Biodiversity on Sandy Beaches

    Science.gov (United States)

    Felix, Gabriela; Marenzi, Rosemeri C.; Polette, Marcos; Netto, Sérgio A.

    2016-10-01

    Sandy beaches are central economic assets, attracting more recreational users than other coastal ecosystems. However, urbanization and landscape modification can compromise both the functional integrity and the attractiveness of beach ecosystems. Our study aimed at investigating the relationship between sandy beach artificialization and the landscape perception by the users, and between sandy beach visual attractiveness and biodiversity. We conducted visual and biodiversity assessments of urbanized and semiurbanized sandy beaches in Brazil and Uruguay. We specifically examined meiofauna as an indicator of biodiversity. We hypothesized that urbanization of sandy beaches results in a higher number of landscape detractors that negatively affect user evaluation, and that lower-rated beach units support lower levels of biodiversity. We found that urbanized beach units were rated lower than semiurbanized units, indicating that visual quality was sensitive to human interventions. Our expectations regarding the relationship between landscape perception and biodiversity were only partially met; only few structural and functional descriptors of meiofauna assemblages differed among classes of visual quality. However, lower-rated beach units exhibited signs of lower environmental quality, indicated by higher oligochaete densities and significant differences in meiofauna structure. We conclude that managing sandy beaches needs to advance beyond assessment of aesthetic parameters to also include the structure and function of beach ecosystems. Use of such supporting tools for managing sandy beaches is particularly important in view of sea level rise and increasing coastal development.

  10. Acidification of sandy grasslands - consequences for plant diversity

    DEFF Research Database (Denmark)

    Olsson, Pål Axel; Mårtensson, Linda-Maria; Bruun, Hans Henrik

    2009-01-01

    Questions: (1) Does soil acidification in calcareous sandy grasslands lead to loss of plant diversity? (2) What is the relationship between the soil content of lime and the plant availability of mineral nitrogen (N) and phosphorus (P) in sandy grasslands? Location: Sandy glaciofluvial deposits...... in south-eastern Sweden covered by xeric sand calcareous grasslands (EU habitat directive 6120). Methods: Soil and vegetation were investigated in most of the xeric sand calcareous grasslands in the Scania region (136 sample plots distributed over four or five major areas and about 25 different sites...

  11. The status of sandy beach science: Past trends, progress, and possible futures

    Science.gov (United States)

    Nel, Ronel; Campbell, Eileen E.; Harris, Linda; Hauser, Lorenz; Schoeman, David S.; McLachlan, Anton; du Preez, Derek R.; Bezuidenhout, Karien; Schlacher, Thomas A.

    2014-10-01

    Open-ocean sandy beaches are coastal ecosystems with growing relevance in the face of global change. They provide key ecosystem services, such as storm buffering, nutrient cycling, water purification, nursery habitats for resource species, and feeding-breeding habitats for focal species (e.g. endangered sea turtles and shorebirds), and have also become nodes for economic development and cultural use. As a result, beaches face a range of threats, primarily from extractive use, habitat modification and development, sea-level rise and coastal squeeze. Consequently, balancing conservation of the ecosystem and sustainable use of the goods and services is particularly important for sandy shores. Thus, the only way to ensure their protection and continued provision of their valuable services, especially in a period of rapid global change, will be to apply knowledge generated from sound science in beach conservation and management. Here we aim to (1) identify and outline the broad ecological paradigms in sandy beach science; (2) report on a citation analysis of the published literature of the past 63 years (1950-2013) to provide context regarding the topics and location of research, the size and institutional composition of the research teams; and (3) investigate whether beach ecology can and has been incorporated into integrated coastal zone management practices. Past research was framed by specific paradigms (chiefly the Swash Exclusion Hypothesis and derivatives), which can be identified with distinct principles and concepts unique to beaches. Most of the sandy beach literature comes from only a few countries (dominated by USA, South Africa, Brazil and Italy), published by small research teams (theory. Despite the constraints, beach science is responding to new challenges, with increasing use of the latest techniques. However, research in conservation and management specifically remains limited, with stronger focus on anthropogenic impacts, in turn leading to management

  12. CapeCodBay_shorelines_uncertainty.dbf - uncertainty table for lidar-derived shorelines used when calculating rates in the Digital Shoreline Analysis System software. Renamed from: GreaterBoston_shorelines_uncertainty.dbf - uncertainty table for lidar-derived shorelines used when calculating rates in the Digital Shoreline Analysis System software for the Greater Boston region from the southern side of Cape Ann, Massachusetts to Sandy Neck Beach in Sandwich, Massachusetts.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the...

  13. Mineral Features of Surface Sediments and Analysis of Solid-State Mineral Resources in Southeastern China Sea

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    With the development of modern industry and the increase of human demand, it is increasingly important to prospect and exploit marine mineral resources. Based on the oceanic geological investigation references obtained from the regional geological surveying and mapping of China Sea (“Shantoufu, F-50” 1: 1 000 000) and on the data (“Marine Engineering Geological Investigation Project in the Pearl River Mouth basin in the South China Sea” 1: 200 000), the authors elaborate the grain size composition, mineral composition, mineral features and distribution pattern of the surface sediments in the sea at 114°- 120°E and 20°-24°N. Moreover, the analysis of the regional solid-state mineral resources in the coast of iFujian, Guangdong and the west of Taiwan, shows that the main resources include littoral/neritic placers, littoral/neritic sandy gravel and ferromanganese nodule (crust). In addition, the future focus should be on the placers and sandy gravels in this littoral area.

  14. On the Impact Angle of Hurricane Sandy's New Jersey Landfall

    Science.gov (United States)

    Hall, Timothy M.; Sobel, Adam H.

    2013-01-01

    Hurricane Sandy's track crossed the New Jersey coastline at an angle closer to perpendicular than any previous hurricane in the historic record, one of the factors contributing to recordsetting peak-water levels in parts of New Jersey and New York. To estimate the occurrence rate of Sandy-like tracks, we use a stochastic model built on historical hurricane data from the entire North Atlantic to generate a large sample of synthetic hurricanes. From this synthetic set we calculate that under long-term average climate conditions, a hurricane of Sandy's intensity or greater (category 1+) makes NJ landfall at an angle at least as close to perpendicular as Sandy's at an average annual rate of 0.0014 yr-1 (95% confidence range 0.0007 to 0.0023); i.e., a return period of 714 years (95% confidence range 435 to 1429).

  15. James J. Howard Marine Sciences Laboratory @ Sandy Hook

    Data.gov (United States)

    Federal Laboratory Consortium — The James J. Howard Marine Sciences Laboratory, located on the New Jersey shore at Sandy Hook, is a state-of-the-art marine research facility shared by the National...

  16. Studies on Thiobacilli spp. isolated from sandy beaches of Kerala

    Digital Repository Service at National Institute of Oceanography (India)

    Gore, P.S.; Raveendran, O.; Unnithan, R.V.

    Occurrence, isolation and oxidative activity of Thiobacilli spp. from some sandy beaches of Kerala are reported. These organisms were encountered in polluted beaches and were dominant during monsoon in all the beaches...

  17. James J. Howard Marine Sciences Laboratory @ Sandy Hook

    Data.gov (United States)

    Federal Laboratory Consortium — The James J. Howard Marine Sciences Laboratory, located on the New Jersey shore at Sandy Hook, is a state-of-the-art marine research facility shared by the National...

  18. Extension of 239+240Pu sediment geochronology to coarse-grained marine sediments

    Science.gov (United States)

    Kuehl, Steven A.; Ketterer, Michael E.; Miselis, Jennifer L.

    2012-01-01

    Sediment geochronology of coastal sedimentary environments dominated by sand has been extremely limited because concentrations of natural and bomb-fallout radionuclides are often below the limit of measurement using standard techniques. ICP-MS analyses of 239+240Pu from two sites representative of traditionally challenging (i.e., low concentration) environments provide a "proof of concept" and demonstrate a new application for bomb-fallout radiotracers in the study of sandy shelf-seabed dynamics. A kasten core from the New Zealand shelf in the Southern Hemisphere (low fallout), and a vibracore from the sandy nearshore of North Carolina (low particle surface area) both reveal measurable 239+240Pu activities at depth. In the case of the New Zealand site, independently verified steady-state sedimentation results in a 239+240Pu profile that mimics the expected atmospheric fallout. The depth profile of 239+240Pu in the North Carolina core is more uniform, indicating significant sediment resuspension, which would be expected in this energetic nearshore environment. This study, for the first time, demonstrates the utility of 239+240Pu in the study of sandy environments, significantly extending the application of bomb-fallout isotopes to coarse-grained sediments, which compose the majority of nearshore regions.

  19. Suspended sediment concentration profiles from synoptic satellite observations

    Digital Repository Service at National Institute of Oceanography (India)

    Ramakrishnan, R.; Rajawat, A.S.; Chauhan, O.S.

    A method is developed to estimate vertical suspended sediment concentration (SSC) profiles in Gulf of Kachchh, from the sediment concentration values derived from synoptic observations of Ocean Colour Monitor (OCM). Under the influence of currents...

  20. Chemistry and behaviour of B, Ca and Mg in interstitial waters of sediments from the coastal and estuarine regions of Mandovi river along the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; SenGupta, R.

    processes. Salinity remains high in most of the sediments rich in clay and silt as compared to the sandy sediments, due to the semi-permeable character of clay and silt. Organic carbon in sediments (av. 1.6%) does not seem to indicate a definite relation...

  1. Human threats to sandy beaches: A meta-analysis of ghost crabs illustrates global anthropogenic impacts.

    Science.gov (United States)

    Schlacher, Thomas A.; Lucrezi, Serena; Connolly, Rod M.; Peterson, Charles H.; Gilby, Ben L.; Maslo, Brooke; Olds, Andrew D.; Walker, Simon J.; Leon, Javier X.; Huijbers, Chantal M.; Weston, Michael A.; Turra, Alexander; Hyndes, Glenn A.; Holt, Rebecca A.; Schoeman, David S.

    2016-02-01

    Beach and coastal dune systems are increasingly subjected to a broad range of anthropogenic pressures that on many shorelines require significant conservation and mitigation interventions. But these interventions require reliable data on the severity and frequency of adverse ecological impacts. Such evidence is often obtained by measuring the response of 'indicator species'. Ghost crabs are the largest invertebrates inhabiting tropical and subtropical sandy shores and are frequently used to assess human impacts on ocean beaches. Here we present the first global meta-analysis of these impacts, and analyse the design properties and metrics of studies using ghost-crabs in their assessment. This was complemented by a gap analysis to identify thematic areas of anthropogenic pressures on sandy beach ecosystems that are under-represented in the published literature. Our meta-analysis demonstrates a broad geographic reach, encompassing studies on shores of the Pacific, Indian, and Atlantic Oceans, as well as the South China Sea. It also reveals what are, arguably, two major limitations: i) the near-universal use of proxies (i.e. burrow counts to estimate abundance) at the cost of directly measuring biological traits and bio-markers in the organism itself; and ii) descriptive or correlative study designs that rarely extend beyond a simple 'compare and contrast approach', and hence fail to identify the mechanistic cause(s) of observed contrasts. Evidence for a historically narrow range of assessed pressures (i.e., chiefly urbanisation, vehicles, beach nourishment, and recreation) is juxtaposed with rich opportunities for the broader integration of ghost crabs as a model taxon in studies of disturbance and impact assessments on ocean beaches. Tangible advances will most likely occur where ghost crabs provide foci for experiments that test specific hypotheses associated with effects of chemical, light and acoustic pollution, as well as the consequences of climate change (e

  2. Trophic connectivity and basal food sources sustaining tropical aquatic consumers along a mangrove to ocean gradient

    Science.gov (United States)

    Claudino, Marlucy Coelho; Pessanha, André Luiz Machado; Araújo, Francisco Gerson; Garcia, Alexandre Miranda

    2015-12-01

    Variations in the relative importance of autotrophic sources to aquatic consumers along environmental gradients and the trophic role of mangrove-derived detritus to marine coastal food webs are still poorly investigated in tropical systems. In this study, we employed stable isotope analyses to investigate the relative importance of basal food sources to macroconsumers (decapod crustaceans and fishes) in a tropical estuary along an environmental gradient extending from the mangroves to the ocean. Additionally, we evaluated the 'outwelling hypothesis', which hypothesizes that mangrove-derived detritus exported to the adjacent marine area is a food source for marine macroconsumers at open and reef-protected sandy beaches. Primary producers and macroconsumers (62 and 214 samples, respectively) were collected at five locations across the main longitudinal axis of the Mamanguape estuary, a tropical Southwestern Atlantic estuary. There were marked shifts in carbon and nitrogen isotope values for both food sources and consumers along the estuarine-marine gradient, and the mixing model results revealed similar patterns of assimilation of basal food sources by decapod crustaceans and fishes. In the inner section of the estuary, consumers tended to assimilated nutrients derived mainly from mangrove and macroalgae, whereas nearer the mouth of the estuary and in the adjacent marine area they assimilated nutrients derived mainly from macroalgae, seagrass and organic matter in the sediment (SOM). These findings support the hypothesis that the relative importance of basal food sources to macroconsumers in this tropical estuarine system reflects the dominant autochthonous primary production at each location. In contrast, our results did not support the outwelling hypothesis that mangrove-originated detritus, in the form of senescent mangrove leaves, makes a significant contribution as a primary source of carbon to high-order consumers inhabiting adjacent ocean sandy beaches.

  3. Benthic foraminifera records in marine sediments during the Holocene from Pescadero basin, Gulf of California, Mexico

    Science.gov (United States)

    Valdez, M.; Perez-Cruz, L. L.; Roy, P.; Monreal, M.; Fenero, R.

    2013-05-01

    Gravity core T-56 (256 cm length) was collected in Pescadero Basin located on the western side of the Gulf of California within the oxygen minim zone (OMZ) at 597 cm depth, aboard of the R/V "El Puma". Pescadero basin is located at mouth of the gulf; because of its location is sensitive to record the changes in the gulf and in the Eastern Pacific Ocean. The sedimentary sequence is analyzed to contribute to the understanding the oceanographic variability in the southern part of the gulf of California during the Holocene using benthic foraminifera assemblages and organic carbon as proxies of organic matter flux and bottom water oxygenation. In general, the core is characterized by silty-clay sediments, and it exhibits a turbidite between 198 and 134 cm, distinguished by sandy sediments and reworking material. From 134 cm to the top shows a visible laminated structure. The initial chronology is based on three AMS radiocarbon dates, and estimated sedimentation rates are 0.22 and 0.19 mm/yr for the first 32 cm of the core. Six radiocarbon dates are in progress. Preliminary results of benthic foraminiferal assemblages showed that species of Bolivina are dominated, mainly megalospheric forms, from 134 cm to top of the core. They are small and thin-shelled forms (e.g., Bolivina subadvena, Bolivina minuta, Bolivina seminuda, Bolivina plicata), and also Buliminella, Cassidulina and Epistominella are abundant. In particular, species of Bolivina are environmental indicators and exhibit a typical reproductive dimorphism. The predominance of the genus Bolivina suggest organic flux variations, because of the productivity changes that might be related to changes in ocean circulation and in the environmental variability in the region.

  4. Evidence for the zircon origin of cadmium anomalies in bottom sediments from the littoral zone of the northern part of Lake Ladoga

    Science.gov (United States)

    Ivanter, E. V.; Slukovskii, Z. I.; Dudakova, D. S.; Medvedev, A. S.; Svetov, S. A.

    2016-06-01

    The minor-element composition of bottom sediments from the littoral zone of the northern part of Lake Ladoga was studied. Close relationships between the anomalous Cd concentrations in lake sediments and Quaternary glacial formations on the territory of Karelia were shown. A negative correlation of Cd with other heavy metals and a positive correlation with Zr were observed. Most likely, Cd is an impurity in zircons from sandy and sandy loam sedimentary formations on the northern coastal area of Lake Ladoga.

  5. Biodiversity and distribution of macroinfauna assemblages on sandy beaches along the Gulf of Cadiz (SW Spain

    Directory of Open Access Journals (Sweden)

    M. José Reyes-Martínez

    2015-09-01

    Full Text Available In the current study, the macroinfauna communities inhabiting 12 sandy beaches along the Spanish coast of the Gulf of Cadiz were describe in order to characterize their unexplored biodiversity, their zonation patterns and their environmental features. A total of 66 macroinfauna taxa were recorded on 12 sandy beaches, ranging from 4 to 33 species. Density reached 848 individual per m2. The individual zonation pattern ranged from two to three zones, regardless of the morphodynamic state. A common zonation pattern of the whole set of beaches was established, comprising three across-shore biological zones. Generally, the supralittoral zone was typified by the air-breathing amphipod Talitrus saltator and coleopterans; the middle zone was dominated by true intertidal species, such as Haustoriidae amphipods (Haustorius arenarius, Cirolanidae isopods (Eurydice affinis, Spionidae polychaetes (Scolelepis spp. and nemerteans; and the lower or sublittoral zone was typified by Pontoporeiidae amphipods, mysids and spionid polychaetes. Sediment moisture, average grain size, organic matter content and elevation were the main predictor variables of zonation patterns. We used the conservation and recreation potential indices to show how this information can be useful for coastal management. Most beaches studied show a score above 5 on the conservation index, so the beaches have a reasonable potential for conservation management.

  6. Zonation of macrobenthos across a mesotidal sandy beach: Variability based on physical factors

    Science.gov (United States)

    Carcedo, M. Cecilia; Fiori, Sandra M.; Bremec, Claudia S.

    2017-03-01

    The dynamic and unstable nature of sandy beaches results in a highly variable distribution of macroinfauna inhabiting the intertidal fringe. Storm-induced sediment movement on the beaches could alter the distribution of organisms, leading to an indistinct zonation scheme. In this context, the zonation pattern of macroinfauna was studied monthly during 2010 in an exposed mesotidal sandy beach on the SW Atlantic coast of Argentina (39°S). Faunal samples were collected with a plastic core (0.02 m2) at 10 to 12 levels along five replicated transects extending from above the drift line to the low tide swash zone. Sand samples were also taken at each level. Wave height and period were measured in situ and data of wind speed and direction were provided by the National Weather Service (SMN). The relationship between the formation of zonation schemes, meteorological data and the physical features of the beach were explored. The results show some significant trends: the supralittoral zone was characterized by the absence of organisms on all sampling occasions. During most of the year the zonation scheme comprised two zones, both within the littoral zone; during winter months, no zonation schemes were found. This contrasting pattern could have been determined by the harsh wind-driven waves, leading to sand movements and thus promoting variations in faunal distribution. Sedimentological changes driven by storms could therefore be the cause of a hidden zonation scheme occurring during winter months, highlighting the importance of a climatic variable in the detection of macrofaunal zonation patterns.

  7. Brazilian sandy beach macrofauna production: a review

    Directory of Open Access Journals (Sweden)

    Marcelo Petracco

    2012-12-01

    Full Text Available The state of the art of the studies on the production of Brazilian sandy beach macrofauna was analyzed on the basis of the data available in the literature. For this purpose, the representativeness of the production dataset was examined by latitudinal distribution, degree of exposure and morphodynamic state of beaches, taxonomic groups, and methods employed. A descriptive analysis was, further, made to investigate the trends in production of the more representative taxonomic groups and species of sandy beach macrofauna. A total of 69 macrofauna annual production estimates were obtained for 38 populations from 25 studies carried out between 22º56'S and 32º20'S. Production estimates were restricted to populations on beaches located on the southern and southeastern Brazilian coast. Most of the populations in the dataset inhabit exposed dissipative sandy beaches and are mainly represented by mollusks and crustaceans, with a smaller number of polychaetes. The trends in production among taxonomic groups follow a similar pattern to that observed on beaches throughout the world, with high values for bivalves and decapods. The high turnover rate (P/B ratio of the latter was due to the presence of several populations of the mole crab Emerita brasiliensis, which can attain high values of productivity, in the dataset. Most of the studies focus on the comparison of production and, especially, of P/B ratio according to life history traits in populations of the same species/taxonomic group. Despite the importance of life history-production studies, other approaches, such as the effect of man-induce disturbances on the macrofauna, should be undertaken in these threatened environments.O estado da arte dos estudos de produção da macrofauna de praias arenosas brasileiras foi analisado a partir de informações disponíveis na literatura. Para essa finalidade, a representatividade dos dados de produção foi examinada de acordo com a distribuição latitudinal

  8. Transport and distribution of bottom sediments at Pirita Beach

    Directory of Open Access Journals (Sweden)

    Soomere, Tarmo

    2007-12-01

    Full Text Available The basic factors affecting sediment supply for and transport processes at Pirita Beach, a sandy section of the south­eastern coast of Tallinn Bay, are analysed. Observations of bathymetry, sediment properties and sources, sediment transport processes and their changes arising from coastal engineering activities are reported. The mean grain size is about 0.12 mm, with the fine sand fraction (0.063–0.125 mm accounting for about 77% of the sediments. Coarse sand dominates only along the waterline. The content of coarser sediments is greater in the northern part of the beach. A number of coastal engineering structures have blocked natural sediment supplies. The beach suffers from sediment deficit now and has lost about 400 m3 of sand annually from the dry beach between 1997 and 2005.

  9. Sediment Sources in the Persian Gulf

    Science.gov (United States)

    Mahoutian, Mehrab

    2014-05-01

    Sediment Constituent Analysis is an effective tool for identifying sediment sources. Based on several sediment samples taken from different sites all over the Iranian coastlines, we have been able to show that an important portion of sediment on the beaches in the Persian Gulf is bio-clastic; that is, biologically created from the coral environment as well as other marine habitats. Unlike mineral (clastic) sediments, carbonate sediments are born not made. Furthermore, carbonate sand constituents are generally less durable than their quartz and mineral counterparts, and break down relatively quickly. Therefore, destruction of reefs and degradation of marine habitat are certain to reduce the sand supply to the shoreline in the Persian Gulf that is necessary to maintain beaches. Carbonate sands are also found on the coastline of the Oman Sea. One of the striking things about the sediments along the coastline of Iran is the high percentage of carbonate material. Molluscan debris is common, even ubiquitous. This reflects the populations living in the offshore waters. Some molluscs thrive in high-energy sandy environments, others like finer sediments. Some live at the surface, while some burrow down as much as a half-metre. A great deal of information can be gained from the study of the species of mollusk and their distribution in the sediments. This paper introduces a few case studies done in different parts of the Persian Gulf by using this method as a general assessment toolbox.

  10. Natural persistence of the coastal plant Glehnia littoralis along temperate sandy coasts

    Science.gov (United States)

    Yang, Hong-Xiao; Chu, Jian-Min; Liu, Xiao-Shan

    2017-01-01

    We studied germination behaviors and persistence mechanism of wild Glehnia littoralis, a typical coastal species at temperate sandy coasts of the North Pacific Ocean, and tested the hypothesis that the coastal plants may have evolved special seeds adapting to the coasts, by which they recruit and persist easily, occupying the coasts as ideal habitats. In the Shandong Peninsula, China, we investigated temperature and moisture conditions of coast sand in relation to germination and evaluated effects of sand burial, seawater immersion and sowing time on germination. When germination began, daily dawn temperatures of sand were about 10 °C and daily noon temperatures were about 25 °C; the temperatures were not different in the sand seeds exhibited large germination rates if sand burial was at depths >= 3 cm and winter freezing was kept longer than 2.5 months. Seeds experiencing seawater immersion were able to germinate well. These evidences suggest that G. littoralis has evolved special seeds adapting to seawater dispersal and specific season rhythm. By the seeds, G. littoralis occupies temperate sandy coasts as ideal habitats to persist. PMID:28211487

  11. Spatial variability of hydraulic conductivity of an unconfined sandy aquifer determined by a mini slug test

    DEFF Research Database (Denmark)

    Bjerg, Poul Løgstrup; Hinsby, Klaus; Christensen, Thomas Højlund;

    1992-01-01

    The spatial variability of the hydraulic conductivity in a sandy aquifer has been determined by a mini slug test method. The hydraulic conductivity (K) of the aquifer has a geometric mean of 5.05 × 10−4 m s−1, and an overall variance of 1n K equal to 0.37 which corresponds quite well to the results...... obtained by two large scale tracer experiments performed in the aquifer. A geological model of the aquifer based on 31 sediment cores, proposed three hydrogeological layers in the aquifer concurrent with the vertical variations observed with respect to hydraulic conductivity. The horizontal correlation...... length of the hydraulic conductivity has been determined for each of the three hydrogeological layers and is found to be small (1–2.5 m). The asymptotic longitudinal dispersivity of the aquifer has been estimated from the variance in hydraulic conductivity and the horizontal correlation length...

  12. The protection of sandy shores - Can we afford to ignore the contribution of seagrass?

    Science.gov (United States)

    Paul, Maike

    2017-08-15

    Shore nourishment is considered an effective soft coastal protection measure for sandy shorelines. However, sand demand and costs are high, especially as nourishment has to be repeated regularly due to ongoing erosion. Seagrass meadows are able to trap and stabilise sediment by reducing bed shear stress. Moreover, they reduce flow velocity and wave energy in regions beyond their boundaries. Especially small species may not provide these ecosystem services sufficiently to protect shorelines from erosion, but they may stabilise beach profiles enough to increase nourishment intervals. This review discusses the potential benefits of integrating ecosystem services provided by seagrass meadows, both existing and newly planted, in nourishment plans, and also addresses potential limitations such as unsuitable hydrodynamic conditions and seasonality. Finally, it highlights knowledge gaps that should be addressed by interdisciplinary research to improve nourishment plans and use seagrass ecosystem services to their full potential. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. The importance of biological interactions for the vertical distribution of nematodes in a temperate ultra-dissipative sandy beach

    Science.gov (United States)

    Maria, Tatiana F.; Vanaverbeke, Jan; Esteves, André M.; De Troch, Marleen; Vanreusel, Ann

    2012-01-01

    This study of the vertical distribution of nematode communities in an ultra-dissipative sandy beach on the North Sea coast at De Panne, Belgium showed species-specific vertical migrations occurred over a tidal cycle. During the period of submersion, smaller deposit feeders were dominant at the subsurface, whereas large nematodes (originally classified as predators) were concentrated at the surface. The interstitial water content showed a weak correlation to the observed patterns and biological interactions among nematodes, such as predation and competition, which were measured through stable isotopes, also explained the observed segregation. The predator Enoplolaimus litoralis and its potential prey species did not co-exist in the same part of the sediment, suggesting avoidance of predation by prey species. In addition, the different prey species inhabited different subsurface layers, which can be explained by avoidance of competition for food. Stable isotope signatures further showed that the two major biological components of sandy beaches (macrofauna and meiofauna, including some species assumed to be predators) partly depend on microphytobenthos, demonstrating the importance of in situ primary producers in the diet of the fauna from ultra-dissipative sandy beaches. However, meiofauna and macrofauna do not seem to compete for these food sources. The combined examination of environmental and biological factors revealed the additional importance of the latter in controlling the vertical distribution of nematodes in environments that were previously assumed to be mainly physically controlled.

  14. Sandy River Delta Habitat Restoration Project, Annual Report 2001.

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Virginia; Dobson, Robin L.

    2002-11-01

    The Sandy River Delta is located at the confluence of the Sandy and Columbia Rivers, just east of Troutdale, Oregon. It comprises about 1,400 land acres north of Interstate 84, managed by the USDA Forest Service, and associated river banks managed by the Oregon Division of State Lands. Three islands, Gary, Flag and Catham, managed by Metro Greenspaces and the State of Oregon lie to the east, the Columbia River lies to the north and east, and the urbanized Portland metropolitan area lies to the west across the Sandy River. Sandy River Delta was historically a wooded, riparian wetland with components of ponds, sloughs, bottomland woodland, oak woodland, prairie, and low and high elevation floodplain. It has been greatly altered by past agricultural practices and the Columbia River hydropower system. Restoration of historic landscape components is a primary goal for this land. The Forest Service is currently focusing on restoration of riparian forest and wetlands. Restoration of open upland areas (meadow/prairie) would follow substantial completion of the riparian and wetland restoration. The Sandy River Delta is a former pasture infested with reed canary grass, blackberry and thistle. The limited over story is native riparian species such as cottonwood and ash. The shrub and herbaceous layers are almost entirely non-native, invasive species. Native species have a difficult time naturally regenerating in the thick, competing reed canary grass, Himalayan blackberry and thistle. A system of drainage ditches installed by past owners drains water from historic wetlands. The original channel of the Sandy River was diked in the 1930's, and the river diverted into the ''Little Sandy River''. The original Sandy River channel has subsequently filled in and largely become a slough. The FS acquired approximately 1,400 acres Sandy River Delta (SRD) in 1991 from Reynolds Aluminum (via the Trust for Public Lands). The Delta had been grazed for many years

  15. Vertical distribution of soil moisture and surface sandy soil wind erosion for different types of sand dune on the southeastern margin of the Mu Us Sandy Land, China

    Institute of Scientific and Technical Information of China (English)

    ChaoFeng Fu; JingBo Zhao; FanMin Mei; TianJie Shao; Jun Zuo

    2015-01-01

    Soil moisture is a critical state affecting a variety of land surface and subsurface processes. We report investigation results of the factors controlling vertical variation of soil moisture and sand transport rate of three types of dunes on the south-eastern margin of the Mu Us Sandy Land. Samples were taken from holes drilled to a depth of 4 m at different topographic sites on the dunes, and were analyzed for soil moisture, grain-size distribution and surface sediment discharge. The results show that: (1) The average soil moisture varies in different types of dunes, with the following sequences ordered from highest to lowest: in the shrubs-covered dunes and the trees-covered dunes the sequence is from inter-dunes lowland to windward slope to leeward slope. The average moisture in the bare-migratory sand dunes is sequenced from inter-dunes lowland to leeward slope to windward slope. (2) Vegetation form and surface coverage affect the range of soil moisture of different types of dunes in the same topographic position. The coefficient of variation of soil moisture for shrubs-covered dunes is higher than that of other types of dune. (3) The effect of shrubs on dune soil moisture is explained in terms of the greater ability of shrubs to trap fine-grained atmospheric dust and hold moisture. (4) The estimated sand transport rates over sand dunes with sparse shrubs are less than those over bare-migratory dunes or sand dunes with sparse trees, indi-cating that shrubs are more effective in inhibiting wind erosion in the sandy land area.

  16. EAARL Coastal Topography - Sandy Hook 2007

    Science.gov (United States)

    Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Stevens, Sara; Yates, Xan; Bonisteel, Jamie M.

    2008-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the National Park Service (NPS), Northeast Coastal and Barrier Network, Kingston, RI; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of Gateway National Recreation Area's Sandy Hook Unit in New Jersey, acquired on May 16, 2007. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL) was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then

  17. Benthic faunal sampling adjacent to the Sand Island ocean outfall, Oahu, Hawaii, 1986-2010 (NODC Accession 9900088)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic fauna in the vicinity of the Sand Island ocean outfall were sampled from 1986-2010. To assess the environmental quality, sediment grain size and sediment...

  18. Nearshore sediment thickness, Fire Island, New York

    Science.gov (United States)

    Locker, Stanley D.; Miselis, Jennifer L.; Buster, Noreen A.; Hapke, Cheryl J.; Wadman, Heidi M.; McNinch, Jesse E.; Forde, Arnell S.; Stalk, Chelsea A.

    2017-04-03

    Investigations of coastal change at Fire Island, New York (N.Y.), sought to characterize sediment budgets and determine geologic framework controls on coastal processes. Nearshore sediment thickness is critical for assessing coastal system sediment availability, but it is largely unquantified due to the difficulty of conducting geological or geophysical surveys across the nearshore. This study used an amphibious vessel to acquire chirp subbottom profiles. These profiles were used to characterize nearshore geology and provide an assessment of nearshore sediment volume. Two resulting sediment-thickness maps are provided: total Holocene sediment thickness and the thickness of the active shoreface. The Holocene sediment section represents deposition above the maximum flooding surface that is related to the most recent marine transgression. The active shoreface section is the uppermost Holocene sediment, which is interpreted to represent the portion of the shoreface thought to contribute to present and future coastal behavior. The sediment distribution patterns correspond to previously defined zones of erosion, accretion, and stability along the island, demonstrating the importance of sediment availability in the coastal response to storms and seasonal variability. The eastern zone has a thin nearshore sediment thickness, except for an ebb-tidal deposit at the wilderness breach caused by Hurricane Sandy. Thicker sediment is found along a central zone that includes shoreface-attached sand ridges, which is consistent with a stable or accretional coastline in this area. The thickest overall Holocene section is found in the western zone of the study, where a thicker lower section of Holocene sediment appears related to the westward migration of Fire Island Inlet over several hundred years.

  19. Beryllium-10 in continental sediments

    Energy Technology Data Exchange (ETDEWEB)

    Brown, L.; Sacks, I.S.; Tera, F. (Carnegie Institution of Washington, DC (USA). Dept. of Terrestrial Magnetism); Klein, J.; Middleton, R. (Pennsylvania Univ., Philadelphia (USA). Dept. of Physics)

    1981-11-01

    The concentration of /sup 10/Be has been measured in 10 samples taken from a transect of surface sediments beginning in the Atchafalaya River and extending across the Bay 136 km into the Gulf of Mexico. If corrected for a lower retentivity of sand for Be, they have a concentration that is constant within 13%. This concentration is about an order of magnitude smaller than that of deep ocean sediments. For comparison, measurements of /sup 10/Be in rainwater, in a sample of soil and in a deep ocean core were made.

  20. Influence of HCl/HF treatment on organic matter in aquifer sediments: A Rock-Eval pyrolysis study

    NARCIS (Netherlands)

    Tambach, T.J.; Veld, H.; Griffioen, J.

    2009-01-01

    Rock-Eval pyrolysis is increasingly used for the routine characterization of natural organic matter in soils and sediments. In this work the bulk composition of sedimentary organic matter (SOM) in sandy aquifer sediments is studied, as well as purified samples (isolation of SOM) by HCl/HF treatment.

  1. Modern seasonal variability of central Arctic Ocean sea-ice cover: Reconstruction based on biomarker ("IP25" and "PIP25") data from sediment trap samples

    Science.gov (United States)

    Fahl, K.; Stein, R.

    2012-04-01

    During the Polarstern 1995 Expedition, a long-term mooring system with two cone-shaped multi-sampling traps was deployed at the dominantly ice-covered western slope of the southern Lomonosov Ridge (81°04.5'N, 138°54.0'E, 1712 m water depth). One trap was installed at 150 m below the sea surface, the other at 150 m above the bottom at 1550 m depth; material was collected in 20 time intervals between September 1995 and August 1996. For background data see Fahl and Nöthig (2007). Here, we present new biomarker data recording the seasonal variability of sea-ice cover. This type of data representing modern seasonal variability of the sea-ice biomarker proxies, was not available so far from the central Arctic Ocean but may help significantly the interpretation of these proxies to be used in sedimentary records for reconstruction of paleo-sea-ice distributions. In this study, we have focused on the novel sea ice proxy "IP25", a direct proxy for sea ice coverage (Belt et al., 2007). Furthermore, we used the phytoplankton-IP25 index ("PIP25" Index), a further development of the IP25 index, based on the coupling of the environmental information carried by IP25 (sea ice) and brassicasterol (open-water phytoplankton productivity) (Müller et al., 2011). The interval November 1995 to June 1996 is characterized by the absence of the sea-ice proxy IP25 (except very minor values for January and April), suggesting a predominantly permanent sea-ice cover at the trap location. During July/August 1996, maximum fluxes of the diatom-specific fatty acids and brassicasterol as well as maximum contents of biogenic opal (Fahl and Nöthig, 2007) indicate increased primary productivity. The marine organic matter (here POC, brassicasterol, and fatty acids) and the IP25 values decrease systematically from 150 to 1550m depth, indicating the typical biogeochemical degradation with increasing water depth. Due to the coincidence of maximum abundances of sea-ice proxies and open-ocean primary

  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. The NGDC Seafloor Sediment Geotechnical Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NGDC Seafloor Sediment Geotechnical Properties Database contains test engineering properties data coded by students at NGDC from primarily U.S. Naval...

  4. Scripps Sediment Description File- OCSEAP Portion

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Scripps Institution of Oceanography compiled descriptions of sediment samples in the Alaskan Outer Continental Shelf area, funded through the NOAA Outer...

  5. The NGDC Seafloor Sediment Grain Size Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NGDC (now NCEI) Seafloor Sediment Grain Size Database contains particle size data for over 17,000 seafloor samples worldwide. The file was begun by NGDC in 1976...

  6. Deck41 Surficial Seafloor Sediment Description Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Deck41 is a digital summary of surficial sediment composition for 36,401 seafloor samples worldwide. Data include collecting source, ship, cruise, sample id,...

  7. Rb-Sr, Sm-Nd, K-Ca, O, and H isotopic study of Cretaceous-Tertiary boundary sediments, Caravaca, Spain: Evidence for an oceanic impact site

    Energy Technology Data Exchange (ETDEWEB)

    DePaolo, D.J.; Kyte, F.T.; Marshall, B.D.; O' Neil, J.R.; Smit, J.

    1983-09-01

    Isotopic ratios and trace element abundances were measured on samples of IR-enriched clay at the Cretaceous-Tertiary boundary, and in carbonate and marl from 5 cm below and 3 cm above the boundary. Samples were leached with acetic acid to remove carbonate, and with hydrochloric acid. Leachates and residues were measured. The Sr, Nd, O and H isotopic compositions of the boundary clay residues are distinct from those of the stratigraphically neighboring materials. The data indicate that most of the clay material was derived from a terrestrial source with relatively low /sup 87/Sr//sup 86/Sr and high /sup 143/Nd//sup 144/Nd ratios. The delta/sup 18/O data suggest that the detritus has been modified by submarine weathering. K-Ca and Rb-Sr systematics, as well as O isotope ratios of K-feldspar spherules within the boundary clay, suggest that they are predominantly authigenic and may have formed after the time of deposition. However, Sm-Nd and Rb-Sr isotopic data indicate that the spherules contain relict material that provides information on the nature of the original detritus. The isotopic evidence for foreign terrestrial detritus in the boundary clay, the low rare earth element concentrations and high Ni concentration, support the hypothesis of a terminal Cretaceous asteroidal impact that produced a global layer of fallout. The data are most easily explained if the impact sites was on oceanic crust rather than continental crust, and if a substantial fraction of the fallout was derived from relatively deep within the lithosphere (> 3 km). This would probably require a single large impactor. 60 references.

  8. Did Hurricane Sandy influence the 2012 US presidential election?

    Science.gov (United States)

    Hart, Joshua

    2014-07-01

    Despite drawing on a common pool of data, observers of the 2012 presidential campaign came to different conclusions about whether, how, and to what extent "October surprise" Hurricane Sandy influenced the election. The present study used a mixed correlational and experimental design to assess the relation between, and effect of, the salience of Hurricane Sandy on attitudes and voting intentions regarding President Barack Obama and Mitt Romney in a large sample of voting-aged adults. Results suggest that immediately following positive news coverage of Obama's handling of the storm's aftermath, Sandy's salience positively influenced attitudes toward Obama, but that by election day, reminders of the hurricane became a drag instead of a boon for the President. In addition to theoretical implications, this study provides an example of how to combine methodological approaches to help answer questions about the impact of unpredictable, large-scale events as they unfold.

  9. Hurricane Sandy, Disaster Preparedness, and the Recovery Model.

    Science.gov (United States)

    Pizzi, Michael A

    2015-01-01

    Hurricane Sandy was the second largest and costliest hurricane in U.S. history to affect multiple states and communities. This article describes the lived experiences of 24 occupational therapy students who lived through Hurricane Sandy using the Recovery Model to frame the research. Occupational therapy student narratives were collected and analyzed using qualitative methods and framed by the Recovery Model. Directed content and thematic analysis was performed using the 10 components of the Recovery Model. The 10 components of the Recovery Model were experienced by or had an impact on the occupational therapy students as they coped and recovered in the aftermath of the natural disaster. This study provides insight into the lived experiences and recovery perspectives of occupational therapy students who experienced Hurricane Sandy. Further research is indicated in applying the Recovery Model to people who survive disasters. Copyright © 2015 by the American Occupational Therapy Association, Inc.

  10. Family Structures, Relationships, and Housing Recovery Decisions after Hurricane Sandy

    Directory of Open Access Journals (Sweden)

    Ali Nejat

    2016-04-01

    Full Text Available Understanding of the recovery phase of a disaster cycle is still in its infancy. Recent major disasters such as Hurricane Sandy have revealed the inability of existing policies and planning to promptly restore infrastructure, residential properties, and commercial activities in affected communities. In this setting, a thorough grasp of housing recovery decisions can lead to effective post-disaster planning by policyholders and public officials. The objective of this research is to integrate vignette and survey design to study how family bonds affected rebuilding/relocating decisions after Hurricane Sandy. Multinomial logistic regression was used to investigate respondents’ family structures before Sandy and explore whether their relationships with family members changed after Sandy. The study also explores the effect of the aforementioned relationship and its changes on households’ plans to either rebuild/repair their homes or relocate. These results were compared to another multinomial logistic regression which was applied to examine the impact of familial bonds on respondents’ suggestions to a vignette family concerning rebuilding and relocating after a hurricane similar to Sandy. Results indicate that respondents who lived with family members before Sandy were less likely to plan for relocating than those who lived alone. A more detailed examination shows that this effect was driven by those who improved their relationships with family members; those who did not improve their family relationships were not significantly different from those who lived alone, when it came to rebuilding/relocation planning. Those who improved their relationships with family members were also less likely to suggest that the vignette family relocate. This study supports the general hypothesis that family bonds reduce the desire to relocate, and provides empirical evidence that family mechanisms are important for the rebuilding/relocating decision

  11. Optical sedimentation recorder

    Science.gov (United States)

    Bishop, James K.B.

    2014-05-06

    A robotic optical sedimentation recorder is described for the recordation of carbon flux in the oceans wherein both POC and PIC particles are captured at the open end of a submersible sampling platform, the captured particles allowed to drift down onto a collection plate where they can be imaged over time. The particles are imaged using three separate light sources, activated in sequence, one source being a back light, a second source being a side light to provide dark field illumination, and a third source comprising a cross polarized light source to illuminate birefringent particles. The recorder in one embodiment is attached to a buoyancy unit which is capable upon command for bringing the sedimentation recorder to a programmed depth below the ocean surface during recordation mode, and on command returning the unit to the ocean surface for transmission of recorded data and receipt of new instructions. The combined unit is provided with its own power source and is designed to operate autonomously in the ocean for extended periods of time.

  12. Dispersion of Sound in Marine Sediments

    Science.gov (United States)

    2014-09-30

    Marine Geology , 209, 147-172, (2004). Jiang, Y. and N.R. Chapman. The Impact of Ocean Sound Speed Variability on the Uncertainty of Geoacoustic...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Dispersion of Sound in Marine Sediments N. Ross...our understanding of the interaction of sound with the ocean bottom is the frequency dependence of sound speed and attenuation in marine sediments

  13. An open ocean record of the Toarcian oceanic anoxic event

    OpenAIRE

    2011-01-01

    Oceanic anoxic events were time intervals in the Mesozoic characterized by widespread distribution of marine organic matter-rich sediments (black shales) and significant perturbations in the global carbon cycle. These perturbations are globally recorded in sediments as carbon isotope excursions irrespective of lithology and depositional environment. During the early Toarcian, black shales were deposited on the epi- and pericontinental shelves of Pangaea, and these sedimentary rocks are associ...

  14. 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,...

  15. 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,...

  16. 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,...

  17. 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,...

  18. ICE - COVERAGE, ICE - TYPE, SEDIMENTS - PERCENT COVER, SPECIES IDENTIFICATION - COUNT and precipitation type visual observation data collected in the South Atlantic Ocean and South Pacific Ocean on the NATHANIEL B. PALMER cruises NBP0103, NBP0104 and others as part of the Southern Ocean GLOBEC project from 2001-04-29 to 2002-09-09 (NODC Accession 0112763)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0112763 includes meteorological, visual observation and physical data collected aboard the NATHANIEL B. PALMER during cruises NBP0103, NBP0104,...

  19. Turbulence-Resolving Coherent Acoustic Sediment Flux Probe Device and Method for Using

    OpenAIRE

    Stanton, Timothy Peter

    2001-01-01

    Patent This invention describes a new method to estimate the sediment flux in front of a Coherent Acoustic Sediment Probe (CASP) instrument. Also, described is a newly invented Bistatic Doppler Velocity and Sediment Profiler (BDVSP) device for measuring sediment concentration, sediment velocity, and the resultant sediment transport in a sediment bed, and for the measurement of turbulent stresses and dissipation in the ocean. This invention describes a new method to ...

  20. Turbulence-Resolving Coherent Acoustic Sediment Flux Probe Device and Method for Using

    OpenAIRE

    2001-01-01

    Patent This invention describes a new method to estimate the sediment flux in front of a Coherent Acoustic Sediment Probe (CASP) instrument. Also, described is a newly invented Bistatic Doppler Velocity and Sediment Profiler (BDVSP) device for measuring sediment concentration, sediment velocity, and the resultant sediment transport in a sediment bed, and for the measurement of turbulent stresses and dissipation in the ocean. This invention describes a new method to ...