Sediment community oxygen consumption (SCOC) is a proxy for organic matter processing and thus provides a useful proxy of benthic ecosystem function. Oxygen uptake in deep-sea sediments is mainly driven by bacteria, and the direct contribution of benthic macro- and mega-infauna respiration is thought to be relatively modest. However, the main contribution of infaunal organisms to benthic respiration, particularly large burrowing organisms, is likely to be indirect and mainly driven by processes such as feeding and bioturbation that stimulate bacterial metabolism and promote the chemical oxidation of reduced solutes. Here, we estimate the direct and indirect contributions of burrowing shrimp (Eucalastacus cf. torbeni) to sediment community oxygen consumption based on incubations of sediment cores from 490 m depth on the continental slope of New Zealand. Results indicate that the presence of one shrimp in the sediment is responsible for an oxygen uptake rate of about 40 µmol d−1, only 1% of ...
Sediments in the Trinity River were chemically, physically and biologically characterized and assessed for toxicity. Laboratory bioassays were conducted to identify sediments which induced toxic responses in test organisms and to document these responses through time. Metal and organic contaminant concentrations in bottom sediments were measured. Relationships between these concentrations and biological responses observed in laboratory bioassays were determined. Toxicity identification / reduction methods were used to characterize sediment toxicants. Sediment oxygen demand was also measured in resuspended and undisturbed bottom sediments through time. The Background Sediment Chemistry Approach and the Sediment Bioassay Approach were used to assess sediment quality. Sediment toxicity was observed in whole sediment bioassays using Chironomus tentans as the test species. A relationship between sediment contaminant concentration and toxicity was observed in approximately sixty percent of the sediments.
The effects of increasing atmospheric CO2 on ocean ecosystems are a major environmental concern, as rapid shoaling of the carbonate saturation horizon is exposing vast areas of marine sediments to corrosive waters worldwide. Natural CO2 gradients off Vulcano, Italy, have revealed profound ecosystem changes along rocky shore habitats as carbonate saturation levels decrease, but no investigations have yet been made of the sedimentary habitat. Here, we sampled the upper 2 cm of volcanic sand in three zones, ambient (median pCO(2) 419 mu atm, minimum Omega(arag) 3.77), moderately CO2-enriched (median pCO(2) 592 mu atm, minimum Omega(arag) 2.96), and highly CO2-enriched (median pCO(2) 1611 mu atm, minimum Omega(arag) 0.35). We tested the hypothesis that increasing levels of seawater pCO(2) would cause significant shifts in sediment bacterial community composition, as shown recently in epilithic biofilms at the study site. In this study, 454 pyrosequencing of the V1 to V3 region of the 16S rRNA gene ...
Callianassid shrimps are the dominant endofauna of reef-top sediments on John Brewer Reef, a small platform reef in the central section of Australias Great Barrier Reef Province. Sediment reworking by these shrimps was investigated using the 210 Pb radioisotope in conjunction with 14 C radiometry and textural data. 210 Pb analyses of cores from two reef-top sites revealed a classical tripartite subdivision characteristic of depositional settings in which sediment reworking dominates over sediment accumulation: (1) A vertical surface mixed layer (SML) extending to a depth of nearly equal 50 cm beneath the sediment surface and representing a zone of intensive callianassid reworking; (2) An intermediate region of radioactive attenuation in which excess 210 Pb activity decreases logarithmically to a depth of slightly more than one meter beneath the sediment surface, and interpreted as representing a region utilized less frequently by Callianassa for coarse grain storage and predator avoidance; (3) ...
The microbial communities associated with electrodes from underwater fuel cells harvesting electricity from five different aquatic sediments were investigated. Three fuel cells were constructed with marine, salt-marsh, or freshwater sediments incubated in the laboratory. Fuel cells were also deployed in the field in salt marsh sediments in New Jersey and estuarine sediments in Oregon, USA. All of the sediments produced comparable amounts of power. Analysis of 16S rRNA gene sequences after 3-7 months of incubation demonstrated that all of the energy-harvesting anodes were highly enriched in microorganisms in the delta-Proteobacteria when compared with control electrodes not connected to a cathode. Geobacteraceae accounted for the majority of delta-Proteobacterial sequences or all of the energy-harvesting anodes, except the one deployed at the Oregon estuarine site. Quantitative PCR analysis of 16S rRNA genes and culturing studies indicated that Geobacteraceae were 100-fold more abundant on the ...
TY - JOUR. T1 - The effect of particle size on sorption of estrogens, androgens and progestagens in aquatic sediment. AU - Sangster, Jodi L.. AU - Oke, Hugues. AU - Zhang, Yun. AU - Bartelt-Hunt, Shannon L. PY - 2015/12/5. Y1 - 2015/12/5. N2 - There is increasing evidence of enhanced transport and biological effects stemming from steroid hormones associated with soils or sediments; however, there are limited studies evaluating how steroid hormone distribution between various particle sizes within whole sediments affects steroid fate. In this study, sorption of 17β-estradiol, estrone, progesterone, and testosterone was evaluated to different size fractions of two natural sediments, a silty loam and a sandy sediment, to determine the steroid sorption capacity to each fraction and distribution within the whole sediment. Sorption isotherms for all steroid hormones fit linear sorption models. Sorption capacity was influenced more by organic carbon content than particle size. Interactions between ...
Sediment management includes different steps in handling (uptake/dredging, transport and disposal), characterization, and sediment quality assessment, which are necessary during construction activities and for the protection and remediation of water bodies. Often, sediment management concepts need holistic understanding of the processes, which are involved in sediment genesis and erosion under specific conditions in different river basins, to work together with the forces of nature and not against them. Sediment management also includes the understanding of sediment contamination such as source control and remediation. In order to protect water bodies, it is therefore necessary to deepen our knowledge on the interaction of water, sediments, microorganisms and rocks, the mobility and transport of pollutants, the development of new technologies for the remediation of contaminated sediments, and the hydrogeochemical modeling of the interaction of contaminants with the sediments.. The symposium will ...
The factors controlling the relative abundances of Archaea and Bacteria in marine sediments are poorly understood. We determined depth distributions of archaeal and bacterial 16S rRNA genes by quantitative PCR at eight stations in Aarhus Bay, Denmark. Bacterial outnumber archaeal genes 10-60-fold in uppermost sediments that are irrigated and mixed by macrofauna. This bioturbation is indicated by visual observations of sediment color and faunal tracks, by porewater profiles of dissolved inorganic carbon and sulfate, and by distributions of unsupported 210Pb and 137Cs. Below the depth of bioturbation, the relative abundances of archaeal genes increase, accounting for one third of 16S rRNA genes in the sulfate zone, and half of 16S rRNA genes in the sulfate-methane transition zone and methane zone. Phylogenetic analyses reveal a strong shift in bacterial and archaeal community structure from bioturbated sediments to underlying layers. Stable isotopic analyses on organic matter and porewater ...
Lanthanum-modified bentonite clay (Phoslock®) is a lake remediation tool designed to strip dissolved phosphorus (P) from the water column and increase the sediment P-sorption capacity. This study investigated short term alterations in sediment elemental composition and sediment P-fractions based on sediment cores taken 2 days before and 28 days following the application of 24 t of Phoslock® to a 9 ha, man-made reservoir. Following the application, sediment lanthanum (La) content increased significantly (p , 0.05; n = 4) in the top 8 cm of the sediment, thereby theoretically increasing sediment P-binding capacity on the whole reservoir scale by 250 kg. Mass balance calculations were used to estimate the theoretical binding of release-sensitive P (Pmobile; sum of labile P, reductant-soluble P and organic P fraction) by La across the top 4 cm and 10 cm depth of sediment. The amended mass of La in the sediment had the potential to bind 42% of Pmobile present in the top 4 cm or 17% of Pmobile ...
Suess, Erwin, von Huene, Roland, Emeis, Kay-Christian, Bourgois, Jacques, Cruzado Castaneda, Jose del C., De Wever, Patrick, Eglinton, Geoffrey, Garrison, Robert, Greenberg, Matt, Paz, Elard Herrera, Hill, Philip R., Ibaraki, Masako, Kastner, Miriam, Kemp, Alan E.S., Kvenvolden, Keith A., Langridge, Robert, Lindsley-Griffin, Nancy, Marsters, Janice, Martini, Erlend, McCabe, Robert; Ocola, Leonidas, Resig, Johanna, Sanchez Fernandez, Agapito Wilfredo, Schrader, Hans-Joachim, Thornburg, Todd M, Wefer, Gerold, and Yamano, Makoto, 1988, Proceedings of the Ocean Drilling Program, Peru continental margin; covering Leg 112 of the cruises of the drilling vessel JOIDES Resolution, 20 October 1986-25 December 1986, in Stewart, Sondra K., ed., Proceedings of the Ocean Drilling Program, Peru continental margin; covering Leg 112 of the cruises of the drilling vessel JOIDES Resolution, 20 October 1986-25 December 1986: Proceedings of the Ocean Drilling Program, Part A: Initial Reports, v. 112, 1015 p. Suess, ...
Aggregates is the collective term for sand, gravel and crushed rock. They are used as raw materials for the construction industry as well as for beach replenishment schemes. During aggregate extraction, the unwanted part of the sediment is discarded back into the water or onto the seabed. Consequently, changes occur to the size of sediment particles, which can alter the natural seabed and the invertebrates living on or inside it (De Groot 1996). Limits for acceptable change in particle size during aggregate extraction can be set, with the aim of reducing the amount of alteration to seabed sediment properties. This may facilitate recovery following cessation of activities post-extraction (Cooper 2013). Additional evidence for intervention related to sediment discard during aggregate extraction and other activities are summarised under "Threat: Energy production and mining - Limit, cease, or prohibit sediment discard during aggregate extraction", "Remove discarded sediment material from the ...
Polynuclear aromatic hydrocarbons (PAHs) are a class of contaminants commonly found in bottom sediments near highly industrialized areas. Resuspension of these sediments can make these contaminants more available for dispersal into the marine environment. The process will also cause the oxidation-reduction characteristics of the sediments to change from anaerobic to aerobic. Bacteria in these sediments have been shown capable of degrading 2 and 3 ring PAHs under aerobic conditions. This research examined the relationship between resuspension and biodegradation of PAHs in laboratory scale slurry reactors. Phenanthrene was used as the model compound. Radiolabeled compound was used to monitor mineralization, and mass balances were performed to determine final partitioning of carbon from degraded phenanthrene. Sediments were kept anaerobic from collection, through the contamination process, and through the loading of test reactors. Aeration of and contaminant release in sediment/water slurries was ...
Article Towards Ecosystem Based Sediment Quality Guidelines for PCB. To investigate whether Sediment Quality Guidelines (SQG) for PCBs in Canada and British Columbia achieve their objective of protecting ecosystems, we measured and compiled concentra...
Quantifying the mass transport through marine sediments, and the geochemical response to such flow with numerical models has become a common and powerful approach for geochemical data interpretation. In this dissertation, I developed and applied transport-reaction models to unravel complex and interdependent reactions involving carbon, sulfur and silica transformations in shallow marine sediments, and the impact of physical (mass transport deposits) and depositional events (volcanic ash input) on the overall geochemical state of the system. Carbon cycling in the gas hydrate bearing sediments of the Ulleung Basin was quantified using both box and kinetic modeling approaches. The box model balances mass, flux, and carbon isotopes of carbon (Chapter 2), and led to a better understanding of how methane is cycled in the marine sediments of this area. This effort demonstrates the significance of CO₂ reduction, a previously overlooked reaction. The picture of reaction network derived from this work ...
River sediment microorganisms have the capacity to metabolize, uptake and decompose flowing water organic materials, which strongly depend on their metabolic capabilities. The changes of microbial functional diversity in river sediments were analysed at five sites along the River Llobregat (NE Spain), using the Biolog EcoPlates incubation method. In parallel, we tested the potential application of the EcoPlates with preserved frozen samples (-80 °C). Although functional diversity (Shannon index) did not show significant differences, the specific carbon substrates that were used differed between sampling sites. The microbial community from the upstream site was the most active as shown by the highest respiratory activity and abundance of living bacteria, being able to metabolize more labile substrates. Downstream sediment communities showed a decrease in bacterial viability, respiration activity and EPS content, suggesting a less structured biofilm. The functional fingerprint analyses clearly ...
TY - JOUR. T1 - Carbon and hydrogen isotopic compositions of sterols from riverine and marine sediments. AU - Chikaraishi, Yoshito. AU - Yamada, Yusuke. AU - Naraoka, Hiroshi. PY - 2005/1/1. Y1 - 2005/1/1. N2 - The sources (marine algae, terrestrial C3 and C4 plants) of sterols deposited to sediments along a riverine-marine transect from Ohtsuchi River in Iwate Prefecture, Japan, to the northwestern Pacific Ocean were estimated using carbon (δ13C) and hydrogen isotopic compositions (δD) in surface sediments. In marine sediments, algal sterols such as 24-methylcholesta-5,22-dien-3β-ol had δ13C values of -22.7 ± 0.4‰ and δD values of -292 ± 3‰. In contrast, sterols derived from multiple potential sources, such as 24-methylcholest-5-en-3β-ol and 24-ethylcholest-5-en-3β-ol, were gradually enriched in 13C from riverine (-30.7‰ and -30.5‰, respectively) to marine sediments (-22.3‰ and -24.4‰, respectively), but showed little variation in δD values (-262 ± 1‰). These isotopic ...
With the yearly increasing marine culture activities in floating cages in Daya Bay, China, the effects of pollution may overlap and lead to more severe water environmental problems. In order to track the impacts of the marine culture in floating cages on water environment, sediments and overlying water were sampled by cylindrical samplers at three representative aquaculture areas of Daya Bay. The water content, porosity, density of sediments as well as the vertical distributions of ammonia nitrogen and active phosphate in pore water along sediments depth were measured. The release rate and annual released quantity of the nutrients across sediment-water interface were calculated using Ficks Law. A horizontal two-dimensional mathematical model was developed to compute the spatial and temporal distributions of the nutrients in seawater after being released across the sediment-water interface. The results showed that the sediments, with a high content and a large annual released quantity of nitrogen and
The following methods of measurement of sediment parameters are discussed: (1) rate of diffusional exchange of reactants and products across the sediment-water interface; (2) the concentration profiles of these reactants and profiles in the sediment, and (3) profiles and integrated rates of reactions in the sediment. The interaction of the processes of reaction and diffusion are illustrated using a simulation model. The effect of increasing organic loading (6.2, 37.2 and 62.0 mmol C m-2 d-1), with organic matter distributed in three ways: close to the sediment surface, a linear gradient downwards or evenly mixed throughout the sediment. Predictable increases in anoxic processes occurred with increasing organic loading. There were higher diffusional losses of dissolved organic matter when organic degradation occurred close to the sediment-water interface. The model predicted that degradation of organic matter at depth could have the following effects: an increase in the depth of oxygen ...
Temperate mangrove and salt marsh sediments are a small methane and nitrous oxide source but important carbon store Journal Articles Refereed ...
Studies of phosphorus (P) dynamics in surface sediments of lakes and coastal seas typically emphasize the role of coupled iron (Fe), sulfur (S) and P cycling for sediment P burial and release. Here, we show that anaerobic oxidation of methane (AOM) also may impact sediment P cycling in such systems. Using porewater and sediment profiles for sites in an oligotrophic coastal basin (Bothnian Sea), we provide evidence for the formation of Fe-bound P (possibly vivianite; Fe-3(PO4)(2)center dot 8H(2)O) below the zone of AOM with sulfate. Here, dissolved Fe2+ released from oxides is no longer scavenged by sulfide and high concentrations of both dissolved Fe2+ (,1 mM) and PO4 in the porewater allow supersaturation with respect to vivianite to be reached. Besides formation of Fe(II)-P, preservation of Fe-oxide bound P likely also contributes to permanent burial of P in Bothnian Sea sediments. Preliminary budget calculations suggest that the burial of Fe-bound P allows these sediments to act as a major ...
Scientific ocean drilling has greatly advanced the understanding of subseafloor sedimentary life. Studies of Ocean Drilling Program (ODP) and Integrated ODP samples and data show that mean per-cell rates of catabolic activity, energy flux, and biomass turnover are orders of magnitude slower in subseafloor sediment than in the surface world. They have also shown that potentially competing metabolic pathways co-occur for hundreds of meter depth in subseafloor sediment deposited over millions of years. Our study of an example site (eastern equatorial Pacific ODP Site 1226) indicates that the energy yields of these competing reactions are pinned to a thermodynamic minimum. The simplest explanation of this long-term coexistence is thermodynamic cooperation, where microorganisms utilize different but coexisting pathways that remove each others reaction products. Our Site 1226 results indicate that the energy flux to subseafloor sedimentary microbes is extremely low. Comparison to biomass turnover ...
A Gram-stain-negative, non-flagellated, non-gliding and rod-shaped bacterial strain, designated TM-6T, was isolated from a tidal flat sediment in the Korean peninsula. Strain TM-6T was found to grow optimally at pH 7.0-8.0, at 30 °C and in the presence of 2-3% (w/v) NaCl. A neighbour-joining phylogenetic tree based on 16S rRNA gene sequences showed that strain TM-6T joined the clade comprising recognized species of the genus Fulvivirga , with which it exhibited 94.7- 95.2 % sequence similarity. Strain TM-6T was found to contain iso-C15 : 0, iso-C15 : 1 G and iso-C17 : 0 3-OH as major fatty acids. The only isoprenoid quinone was menaquinone-7 (MK-7). The major polar lipids were identified as phosphatidylethanolamine and three unidentified lipids. The DNA G+C content of strain TM-6T was 50.9 mol%. Differential phenotypic properties, together with the phylogenetic distinctiveness, revealed that strain TM-6T is distinguishable from recognized Fulvivirgaspecies. On the basis of the data presented, strain
Overview: A primary objective of marine science classes is to learn the location and formation of ocean sediment types. Paper text and online multimedia both fall short of the experience of handling real ocean sediment. Real samples enhance learning through sight, touch, and smell, and microscope slides (smear slides for use with a petrographic microscope) allow students to better comprehend the tiny sizes and forms of various sediment components.. Real samples provide only pinpoint examples of the ocean floor, yet they swim within a virtual ocean of geological data that is best utilized with online visualization tools like Google Earth. We have merged both the real and the virtual by creating a Google Earth based supplemental information resource for each example of ocean sediment from an IODP sediment Core Kit consisting of core catcher sections and sediment smear slides that teachers may borrow for classroom instruction. 47 years of scientific ocean drilling has produced over 50,000 short ...
The aim of present work was to assess the concentration levels as well as vertical distribution of indicator bacteria including total coliform, fecal coliform, Pseudomonas aeruginosa, and Heterotrophic Plate Count (HPC) in the marine environment (seawater and coastal sediments) and evaluate the correlation between indicator bacteria and some physicochemical parameters of surface sediments as well as seawaters. A total number of 48 seawater and sediment samples were taken from 8 stations (each site 6 times with an interval time of 2 weeks) between June and September 2014. Seawater and sediment samples were collected from 30 cm under the surface samples and different sediment depths (0, 4, 7, 10, 15, and 20 cm) respectively, along the Persian Gulf in Bushehr coastal areas. Based on the results, the average numbers of bacterial indicators including total coliform, fecal coliform, and Pseudomonas aeruginosa as well as HPC in seawater samples were 1238.13, 150.87, 8.22 MPN/100 ml and 1742.91 CFU/ml,
Fluxes of TDCu and Cu ligands have been determined at two sites in the Chesapeake Bay for June and October 95, and in March 96. TDCu appears to flux out of the sediments at both sites in both spring and summer. In March 95, the TDCu flux out of site M (mid-Bay) sediments (41 + or - 10 nmol/sq m/d) exceeded that at site S (southern Bay: 7 + or - 3 nmol/sq m/d). However, in June 95, the TDCu flux out at site S (52 + or - 25 nmol/sq m/d) exceeded that at site M (13 + or - 15 nmol/sq m/d). There is a significant out-flux (200 to 800 nmol/sq m/d) of total Cu-binding ligands (TLcu) from the sediments at both sites in both spring and summer, but the TLcu flux at site M exceeded that at site S. The TLcu is 3-60x greater than the TDCu flux, and the ligands fluxing out are comparable in strength (log K=15) to that of the very strong L1 class that controls the speciation of TDCu in most marine surface waters, and previously only observed in these surface waters. Sediment fluxes of this very strong ligand in June
The coupling of subseafloor microbial life to oceanographic and atmospheric conditions is poorly understood. Contreras et al. examined diagenetic imprints and lipid biomarkers of past subseafloor microbial activity to evaluate its response to glacial-interglacial cycles in a sedimentary section drilled on the Peruvian shelf (Ocean Drilling Program Leg 201, Site 1229). Multiple and distinct layers of diagenetic barite and dolomite, i.e., minerals that typically form at the sulfate−methane transition (SMT), occur at much shallower burial depth than the present SMT around 30 meters below seafloor. These shallow layers co-occur with peaks of 13C-depleted archaeol, a molecular fossil of anaerobic methane-oxidizing Archaea. Present-day, non-steady state distributions of dissolved sulfate also suggest that the SMT is highly sensitive to variations in organic carbon flux to the surface shelf sediments that may lead to shoaling of the SMT. Reaction-transport modeling substantiates our hypothesis that ...
We investigated the impact of temperature on the microbial turnover of organic matter (OM) in a hydrothermal vent system in Guaymas Basin, by calculating microbial bio- and necromass turnover times based on the culture-independent D:L-amino acid model. Sediments were recovered from two stations near hydrothermal mounds (8 to 106 cells cm-3 within ∼5 m of sediment depth resulting in a 100-fold lower cell number at this depth than at the cold site where numbers remained constant at 108 cells cm-3 throughout the recovered sediment. There were strong indications that the drop in cell abundance was controlled by decreasing OM quality. The quality of the sedimentary OM was determined by the diagenetic indicators %TAAC (percentage of total organic carbon present as amino acid carbon), %TAAN (percentage of total nitrogen present as amino acid nitrogen), aspartic acid:β-alanine ratios, and glutamic acid:γ-amino butyric acid ratios. All parameters indicated that the OM became progressively degraded with
679 m3 s−1 by the 2090s, an increase of between 23% and 39% relative to the baseline period, depending on the specific climate model run.. In terms of future sediment fluxes, Fig. 6c shows that under the Q0 run sediment loads on the Ganges are projected to significantly increase relative to the 1981-2000 baseline of 521 Mt per year, to 613 Mt per year by the 2050s and then 696 Mt per year by the end of the century, the latter representing an overall increase of 175 Mt per year (34%) relative to the baseline period. Under the Q8 run a similar increase in sediment load with time is also evident, with projected values of 609 Mt per year by the 2050s (a 16% increase relative to the Q8 baseline) and 714 Mt per year by the 2090s, an end of century value which is around 191 Mt per year (37%) greater than the baseline. For the Ganges, sediment loads for the Q16 run are less than both the Q0 and Q8 runs, reflecting the lower precipitation in this catchment for the Q16 run (see Fig. 3). Thus, a mean ...
The porewater chemistry was in broad agreement with the observed petrology and, in the case of the urban site, the data provides evidence of sediment disturbance. The periodic resuspension of the sediment by boat traffic results in a significant change to the surface porewater chemistry of iron and sulphate in the urban sediment and results in changes to the stability of certain authigenic phases, most notably vivianite. In the rural sediment, although physical disturbance of the sediment was observed, there was no chemical evidence in the porewater results. However, it does perhaps subtly enhance the organic matter degradation processes that are occurring, although this could not be confirmed by the results of this investigation ...
Open full size. Gas bubble emissions from bottom sediments of Lake Baikal. Methane emissions from bottom sediments in Lake Baikal have been known for a long time. Even the first travelers, who visited the lake in the 17th century, noticed gas emissions. Later gas emissions in Baikal were explored by the East Siberian Branch of the Russian Imperial Geographical Society. A review of the available materials on gas seeps in Baikal is presented in the publication [Granin and Granina, 2002]. A new stage of research on gas seeps in Baikal started after the discovery of gas hydrates [Kuzmin et al., 1998] and mud volcanoes at the bottom of the lake [Van Rensbergen et al., 2002] at the turn of the 20th century.. Gas seeps are found in oceans, seas and freshwater bodies. To study gas seeps hydroacoustic methods are used, as they enable an extensive search due to the strong backscattering of sound from the bubbles of floating-up gas. To locate and monitor the activity of gas plumes a digital record of ...
We developed a microsensor for the amperometric detection of dissolved hydrogen sulfide,H2S, in sedirnents and biofilms. The mlcrosensor exhibits a fast (tgOc 0.2 to 0.5 S) and linear response to H2S over a concentration range of 1 to ,l000 pm01 H2S-I and has a low stirring dependency of the microsensor signal (c1 to 2%). We used the new mlcrosensor to obtain the first microprofiles of H2S in an acidic lake sediment with a several cm thick flocculant surface layer. Despite the low pH of 4.6, a relative low SO,- level in the lake water, and a broad O2 respiration zone of ca 6 mm, we were able to measure H2S depth profiles in the sediment at a good resolution, that allowed for calculation of specific sulfate reduction and H2S oxidation activities. Such calculations showed highest sulfate reduction activity in the anoxic sediment down to ca 20 mm depth A comparison of calculated area1 rates of O2 consumption and sulfate reduction Indicated that sulfate reduction accounted for up to 13 % of total ...
Lower Eocene to Holocene sediments recovered from Ocean Drilling Program Sites 918 and 919 were studied to determine the grain-size distribution (sand to clay sizes) and mineralogy of the ,2 m size fraction. The minerals are believed to be of detrital origin. The clay minerals consist of chlorite, smectite, illite, kaolinite, and a mixed-layer illite/smectite. Several non-clay minerals were identified as well, including quartz, plagioclase, alkali-feldspar, amphibole, pyroxene, zeolite, and calcite.. Relative abundances of the clay minerals were semiquantified using an oriented internal standard. Smectite abundances were found to increase with depth, while illite and chlorite abundances decrease with depth.. The Eocene sediments of Site 918 are characterized by a predominance of smectite with some kaolinite and very small amounts of chlorite and illite. This mineral assemblage is indicative of warm climatic conditions at the time of deposition. Oligocene sediments show an increase in chlorite ...
Microbial community diversity and chemodiversity were investigated in marine sediments adjacent to the Okinawan Kaichu-Doro Causeway, which was constructed 46 years ago to connect a group of four islands (Henza-jima, Miyagi-jima, Ikei-jima, Hamahiga-jima) to the Okinawan main island. This causeway was not built on pilings, but by land-filling; hence, it now acts as a long, thin peninsula. The construction of this causeway was previously shown to have influenced the surrounding marine ecosystem, causing ecosystem fragmentation and loss of water circulation. In this study, we collected sediment cores (n = 10) from five paired sites in 1 m water depths. Each pair of sites consisted of one site each on the immediate north and south sides of the causeway. Originally the members of each pair were much closer to each other (
Deep-sea sediments cover ~70% of Earths surface and represent the largest interface between the biological and geological cycles of carbon. Diatoms and zooplankton faecal pellets naturally transport organic material from the upper ocean down to the deep seabed, but how these qualitatively different substrates affect the fate of carbon in this permanently cold environment remains unknown. We added equal quantities of 13C-labelled diatoms and faecal pellets to a cold water (−0.7 °C) sediment community retrieved from 1080 m in the Faroe-Shetland Channel, Northeast Atlantic, and quantified carbon mineralization and uptake by the resident bacteria and macrofauna over a 6-day period. High-quality, diatom-derived carbon was mineralized ,300% faster than that from low-quality faecal pellets, demonstrating that qualitative differences in organic matter drive major changes in the residence time of carbon at the deep seabed. Benthic bacteria dominated biological carbon processing in our experiments, ...
This article is a summary of chapter 5 of the [[Manual Sediment Transport Measurements in Rivers, Estuaries and Coastal Seas]],ref>Rijn, L. C. van (1986). Manual sediment transport measurements. Delft, The Netherlands: Delft Hydraulics Laboratory,/ref>. This article describes different measurement instruments available to measure sediment transport in rivers, coastal seas and estuaries. Many of these instruments are also described in separate articles (see text for links to these articles). ==Introduction== Various instruments for measuring the sediment transport rate are described. Usually the sediment transport is represented as the summation of the [[bed load]] and [[suspended load]] transport. To measure the [[bed load]] transport, two measuring methods are available: simple mechanical trap-type samplers (collecting the sediment particles transported close to the bed) and the recording of the bed profile as a function of time ([[bed form tracking]]). To measure the [[suspended load]] ...
Read "Assessment of the sediment quality of freshwater ecosystems in eastern China based on spatial and temporal variation of nutrients, Environmental Science and Pollution Research" on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
Being a major cause of eutrophication and subsequent loss of water quality, the turnover of phosphorus (P) in lake sediments is in need of deeper understanding. A major part of the flux of P to eutrophic lake sediments is organically bound or of biogenic origin. This P is incorporated in a poorly described mixture of autochthonous and allochthonous sediment and forms the primary storage of P available for recycling to the water column, thus regulating lake trophic status. To identify and quantify biogenic sediment P and assess its lability, we analyzed sediment cores from Lake Erken, Sweden, using traditional P fractionation, and in parallel, NaOH extracts were analyzed using 31P NMR. The surface sediments contain orthophosphates (ortho-P) and pyrophosphates (pyro-P), as well as phosphate mono- and diesters. The first group of compounds to disappear with increased sediment depth is pyrophosphate, followed by a steady decline of the different ester compounds. Estimated half-life times of these ...
Comparative Study on Microphytobenthic Pigments and Total Microbial Biomass by ATP in Intertidal Sediments - microphytobenthos;pigment;Adenosine-5 triphosphate (ATP);intertidal sediments;
The majority of a streams sediment load is carried in solution (dissolved load) or in suspension. The remainder is called the bed load.
A Gram-positive, rod-shaped, endospore-forming organism, strain BL3-6(T), was isolated from tidal flat sediments of the Yellow Sea in the region of Tae-An. A 16S rRNA gene sequence analysis demonstrated that this isolate belongs to the Bacillus cereu
The Haihe River Basin, which is one of the most water-scarce and polluted river basins in China, has abnormally high nitrogen levels. In this study, total hydrolyzable amino acids (THAAs) were measured in surface sediment and sediment core samples in the Haihe River Basin to determine if amino acids were potential sources of ammonium, organic nitrogen, and organic carbon. The rivers were found to be in a state of hypoxia and contain abnormally high levels of ammonium and organic nitrogen. Additionally, NH3-N was the predominant form of inorganic nitrogen in the surface sediments, while organic nitrogen accounted for 92.53% of sedimentary nitrogen. THAAs-C accounted for 14.92% of the total organic carbon, while THAAs-N accounted for more than 49.59% of organic nitrogen and 45.68% of total nitrogen. The major fraction of THAAs were protein amino acids. Three sediment cores of the most heavily polluted rivers also showed high levels of THAAs. Evaluation of the degradation index (DI) of sedimentary organic
D7363 - 13a Standard Test Method for Determination of Parent and Alkyl Polycyclic Aromatics in Sediment Pore Water Using Solid-Phase Microextraction and Gas Chromatography/Mass Spectrometry in Selected Ion Monitoring Mode ,
...An analysis of sediment cores indicates that biological and chemical c...While environmental changes at the lake over the past millennia have b... The past few decades have been unique in the past 200000 years in te...The study was published Oct. 19 in the Proceedings of the National ...,Arctic,lake,sediments,show,warming,,unique,ecological,changes,in,recent,decades,biological,biology news articles,biology news today,latest biology news,current biology news,biology newsletters
Two mud volcanoes in the Gulf of Mexico were examined to understand barium cycling in shallow seafloor sediment at regions of intense methane expulsion. Due to anaerobic oxidation of methane and sulfate reduction, barium interacts with methane and sulfate, producing barite fronts at the sulfate-methane transition and barium-rich pore fluids underneath. Formation waters likely feed volcanoes and deliver large amounts of Ba2+ to the system from below. Locally elevated Ba2+ concentrations amplified cycling, producing sigmodial pore water profiles in the shallowest sediment. The expulsion of Ba-rich fluids directly to the water column concentrates barite in surficial sediments, which can also enhance cycling. Further, two types of barium-rich, carbonate nodules were recovered. Rocky nodules resemble buried carbonate crusts, diagenetically altered by pore fluids. Smooth nodules are likely preserved barite fronts marking past sulfate-methane transitions. Both types of nodules can serve as a modern ...
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The USGS Woods Hole Science Center has been an active member of the Woods Hole research community for over 35 years. In that time there have been many sediment collection projects conducted by USGS scientists and technicians for the research and study of seabed environments and processes. These samples are collected at sea or near shore and then brought back to the Woods Hole Science Center (WHSC) for study. While at the Center, samples are stored in ambient temperature, cold or freezing conditions, depending on the best mode of preparation for the study being conducted or the duration of storage planned for the samples. Recently, storage methods and available storage space have become a major concern at the WHSC. The shapefile sed_archive.shp, gives a geographical view of the samples in the WHSCs collections, and where they were collected along with images and hyperlinks to useful resources ...
By inducing artificial turbidity currents to transport the sediments of obstructing bars into deeper water, the natural phenomenon of sediment transport by turbidity currents may be applied to the dredging of navigable channels. The method may be used provided that sufficient slope is present to allow removal of the sediment by currents, that the sediments are of a type which can form turbidity flows, and that equipment is available for mixing the sediment and water. No accurate cost analysis is presently available. ...
Biodegradation of hydrocarbons is a complex process, and a vast amount of hydrocarbon-degradation capacity remains to be exploited in the bioremediation of extensive areas of contaminated land throughout Europe and the world. DECAPAGE proposes to explore the microbial diversity of coastal microbial communities for hydrocarbon compounds degradation. Emphasis will be largely on hydrocarbon degrading microbial consortia adapted to oxic/anoxic oscillations with a special focus on anoxic metabolisms. This proposal has the ambition to characterize the chemical and microbiological aspects involved on hydrocarbons biodegradation. It is based on innovative concepts and the use of the latest technologies. Their combination will allow the description of the dynamic adaptation of bacterial communities to the presence of petroleum and how the oxygenation and redox oscillations affect their functioning. The DECAPAGE proposal seeks to provide : (1) novel analytical approaches for the identification of hydroxylated
INTRODUCTION. The marine sediments are an environmental matrix (Elderfield, 1978) in which the stratigraphic disposition conforms a record of the processes and balances that occur in the surface layers (Stumm & Morgan, 1981; Colombo et al, 1996). The chemical composition of the sediment depends on the mineralogical constitution of the mother rocks that originate it; the grain size, composition, and chemical characteristics of the environment in which it is deposited; the advective processes of the site; and anthropogenic contributions (Ahumada, 1998).. If the fraction of the natural or anthropogenic material that is input into an aquatic system is trapped in the sediments - and depending on its chemical quality - it can alter and/or change the substrate composition and may leave a record of such activity in the sediment column. In order for such a change to be recorded, it must be of a certain magnitude, persist over time, and occur in the absence of physical or biological disturbances ...
Looking for bioturbation? Find out information about bioturbation. The disruption of marine sedimentary structures by the activities of benthic organisms Explanation of bioturbation
Climate change along with anthropogenic activities changes biogeochemical conditions in lake ecosystems, modifying the sediment microbial communities. Wastewater effluents introduce nutrients and organic material but also novel microbes to lake ecosystems, simulating forthcoming increases in catchment loadings. In this work, we first used 16s rRNA gene sequencing to study how the overall sediment microbial community responds to wastewater in six boreal lakes. To examine forthcoming changes in the lake biogeochemistry, we focused on the ammonia‐oxidizing archaea (AOA) and bacteria (AOB), and examined their functional and compositional community response to wastewater. Although we found the least diverse and least resistant prokaryotic communities from the most wastewater‐influenced sediments, the community changed fast toward the natural composition with the diminishing influence of wastewater. Each lake hosted a unique resistant AOA community, while AOB communities were adapting, responding ...
A recent review [49] argued that opportunities for aDNA recovery from sediments in temperate climates are likely to be worse than those in permafrost environments. Indeed, ancient plant DNA as old as 300,000 to 400,000 years old has been recovered from permafrost [43]. However, DNA preservation, degradation and leaching in permafrost settings are likely to be very different from that in lacustrine sedimentary environments and we want to be careful about apples to oranges comparisons. Successful amplification of plant DNA in temperate anaerobic sediments has, until now, been difficult. Holocene aDNA sequences have been recovered from macrofossils [50] and from individual pollen grains [51] in anaerobic peats and lake sediments, but success rates were very low (,10%) in these studies, even for recently deposited material. In our study, success rates are higher than previous analyses and inhibition is lower. On the other hand, the concentration of DNA extracted in our work is often extremely low, ...
PhD students Emily Chua and Claudia Mazur have been awarded Warren-McLeod Fellowships for their marine science work. Chua will use her year-long award to help develop an underwater instrument to investigate biogeochemical processes occurring in marine sediments. Mazur will use her summer grant to study nitrogen cycling in coastal marine sediments. The Warren-McLeod Graduate Fellowship in Marine […]. ...
Nitrogen (N) is a key component of fundamental biomolecules. Hence, its cycling and availability are central factors governing the extent of ecosystems across the Earth. In the organic-lean sediment porewaters underlying the oligotrophic ocean, where low levels of microbial activity persist despite limited organic matter delivery from overlying water, the extent and modes of nitrogen transformations have not been widely investigated. Here we use the N and oxygen (O) isotopic composition of porewater nitrate (NO3−) from a site in the oligotrophic North Atlantic (Integrated Ocean Drilling Program - IODP) to determine the extent and magnitude of microbial nitrate production (via nitrification) and consumption (via denitrification). We find that NO3- accumulates far above bottom seawater concentrations (~ 21 μM) throughout the sediment column (up to ~ 50 μM) down to the oceanic basement as deep as 90 m b.s.f. (below sea floor), reflecting the predominance of aerobic ...
Sediment is a naiturally occurring material that is broken doun bi processes o watherin an erosion, an is subsequently transportit bi the action o wind, watter, or ice, an/or bi the force o gravity actin on the pairticle itself. Sediments are maist eften transportit bi watter (fluvial processes), wind (aeolian processes) an glaciers. Beach sands an river channel deposits are ensaumples o fluvial transport an deposeetion, tho sediment an aa eften settles oot o slow-movin or staundin watter in lochs an oceans. Desert saund dunes an loess are ensaumples o aeolian transport an deposeetion. Glacial moraine deposits an till are ice-transportit sediments. ...
In freshwater systems phosphorus (P) is the limiting element in the cause of eutrophication. In many Swedish lakes, causes of eutrophication have been attributed to more of internal loading than external since the external loading has been fairly well managed. Internal loading is linked to the mobility of sediment P, which are known to be Bioavailable P (BAP). Sediments from Lake Hällerstadsjön in Sweden was studied to know the BAP concentration and its possible release into the water column under reduced conditions. Sediments were sampled at two different depths, 0-5 cm and 5-10cm. BAP was determined by a phosphorus fractionation scheme. Sediments were incubated under oxic and anoxic conditions in the laboratory to evaluate sediment P release. Spatial variation in the distribution of P forms across the lake was also studied, in order to examine possible local patterns, particularly along a transect from the main inlet to the outlet. Fractionation analyses showed a trend of; Residual-P , ...
Multivariate statistical analysis of major and minor element geochemical data is used to analyze dolomite in the offshore facies of the Bonneterre Formation (Cambrian), southern Missouri. Relationships among geochemical data are established, using factor analysis, which differentiate two dolomites having different diagenetic histories. Application of Bayes formula to the geochemical data permit discriminant functions to be constructed, containing only two geochemical parameters, which identify the major dolomite types. The results of factor analysis are consistent with previous analysis of the dolomite based on petrography and stratigraphic occurrence. This method is easy to use and may be useful in cases where petrographic methods or non-statistical analysis of geochemical data are unable to differentiate dolomite types.
Sediments recovered from your flooded mine workings of the Penn Mine, a Cu-Zn mine abandoned since the early 1960s, were cultured for anaerobic bacteria over a range of pH (4. 2C3 heavier in the mine water, relative to those in surface waters; (3) reduction/oxidation conditions and dissolved gas concentrations consistent with conditions to support AKT1 anaerobic processes such as sulfate reduction. Scanning electron microscope (SEM) analyses of sediment show 1.5-micrometer, spherical ZnS precipitates. Phospholipid fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analyses of Penn Mine sediment show a high biomass level with a moderately diverse community structure composed primarily of iron- and sulfate-reducing bacteria. Cultures of sediment from your mine produced dissolved sulfide at pH values near 7 and near 4, forming precipitates of either iron sulfide or elemental sulfur. DGGE coupled with sequence and phylogenetic analysis of 16S rDNA gene segments showed populations ...
The aim of this study was to determine the spatial variability for total-and methylmercury in surface sediments (0-2 cm) across a single whole-lake basin, and to relate this variability to the sediments geochemical composition. 83 surface sediment samples from Stor-Stromsjon - a lake with multiple sub-basins located in northern Sweden - were analyzed for geochemical composition as well as total-mercury (total-Hg) and methylmercury (methyl-Hg; 35 samples) concentrations. Our results indicate that variations in fine-grained mineral matter (36%) and organic matter (34%) explain an equal amount of the total-Hg variation, but that their relative importance varies between different parts of the lake. Total-Hg concentrations were similar in locations controlled by organic matter or fine-grained mineral matter (average 109 ng g(-1)); however, total-Hg inventories (mass per unit area) were significantly higher in the latter (35 and 53 mu g m(-2), respectively). Methyl-Hg concentrations are largely (55% ...
Sediments within the Okinawa back-arc basin overlay a subsurface hydrothermal network, creating intense temperature gradients with sediment depth and potential limits for microbial diversity. We investigated taxonomic changes across 45 m of recovered core with a temperature gradient of 3°C/m from the dynamic Iheya North Hydrothermal System. The interval transitions sharply from low-temperature marine mud to hydrothermally altered clay at 10 meters below seafloor (mbsf). Here, we present taxonomic results from an analysis of the 16S rRNA gene that support a conceptual model in which common marine subsurface taxa persist into the subsurface, while high temperature adapted archaeal taxa show localized peaks in abundances in the hydrothermal clay horizons ...
BH: Oxygen is needed for the breakdown and decay of organic material settles in the sediment at the bottom of the ocean. By measuring the relative levels of different carbon isotopes, we can track the amount of this breakdown. We also already know that the more oxygen there is in the overlying sea water, the more organic material gets broken down.. But as you go deeper into the sediment, more oxygen is used up, until there just isnt enough oxygen for the breakdown of organic material. This is the anoxic boundary.. We could track this boundary by comparing the levels of carbon isotopes in the shells of Cibicidoides wuellerstorfi, which live just on top of ocean floor sediments, versus Globobulimina spp., a related species which lives burrowed down into sediment, at the anoxic boundary.. By comparing carbon isotope levels between these two species, one of which had lived in seawater and one which had lived at the anoxic boundary, we could work out oxygen concentrations at the bottom of the ...
Background Microorganisms in a shrimp cultural pond ecosystem (SCPE) play important roles for animal and environmental health. While the microbial diversity and assembly mechanism, and how communities of multiple habitats contribute to the SCPE metacommunity are poorly understood. Here, we analy...
These can be linked to the various liquid-transport phases of the hydrologic cycle. At the catchment level, sediment production by soil particle detachment is primarily the result of raindrop impact. Once detachment has taken place, surface runoff acts to transport sediment downslope, first as overland flow (sheet and rill flow), and eventually as stream and river flow. Deposition of sediment occurs at any point downstream where the kinetic energy of the flow is insufficient to support sediment entrainment in the flowing water. Sediment production refers to the processes by which sediment is produced, the identification of sediment sources and amounts, and the determination of sediment yields. The source of sediment can usually be traced back to the upland catchments, although these are by no means the only source. In certain cases, streambank erosion in the lower valleys may constitute an important source of sediment. Sediment from upland catchments is delivered to streams and rivers, wherein ...
Map of This map from the U. S. Geological Survey Water Resources Investigation Report number 96-4063, Hydrology of the Surficial and Intermediate Aquifer Systems in Sarasota and Adjacent Counties, shows the major well fields or utility pumping centers in so...
Review: Ancient plant DNA in lake sediments on Plantae | Fossils have been extremely useful in efforts to reconstruct the past, but recently the analysis of…
The concentrations of metals in bottom sediment in the Tanzanian waters of Lake Victoria and the nature of suspended particulate matter (SPM) were analysed. The objective of the study was to compare levels of metals in sediment from different locations and to establish their sources. Metal concentrations were higher in sediment in locations within urban catchments. There were significant differences between sites for concentrations of Cu, Cr, Zn, Hg and Pb in sediment. Mercury concentration was higher in Nungwe Bay sediment compared to other areas, and Cr was higher in Magu Bay, while Cu, Pb and Zn were higher in Mwanza Gulf. Watershed characteristics such as urbanisation, and lake characteristics such as algal biomass, influence the nature of SPM, and hence the concentration of metals in the sediment. The potential to distinguish between different origins of metals in the lake, if the sources of SPM are well construed, is demonstrated ...
www.MOLUNA.de The Interactions Between Sediments and Water [4094138] - This book focuses on sediments as a pollutant in natural freshwater and marine habitats, and as a vector for the transfer of chemicals such as nutrients and contaminants. Sediment-water research is carried out all over the world within a variety of disciplines. The selected papers cover three main topics:n-assessment and/or
Article ID : 2018/IJPSS/43899 : Ecological Risk Assessment of Heavy Metals in Soil Developed on Coastal Marine Sediment along Coastal Area in Anantigha, Calabar. E. E. Aki1* and I. A. Isong1. 1Department of Soil Science, University of Calabar, Nigeria.. __________________. Article ID : 2018/IJPSS/40790 : Collection and Preparation of Soil, Water and Plant Samples for Analysis. S. M. Acharya1* and Siddesh ...
PANGAEA - Publishing Network for Geoscientific and Environmental Data. (Table 2) Dinoflagellate cysts in surface sediment samples of Meteor cruises M20/2, M23/1, M34/2 and M34/2. Occurrence Dataset https://doi.org/10.1594/pangaea.85166 accessed via GBIF.org on 2018-02-17 ...
D4698 - 92(2013) Standard Practice for Total Digestion of Sediment Samples for Chemical Analysis of Various Metals , chemical analysis, metal, sediment samples, total, total digestion,
Crivellari, Stefano; Chiessi, Cristiano Mazur; Kuhnert, Henning; Häggi, Christoph; Portilho-Ramos, Rodrigo Costa; Zeng, Jing-Ying; Zhang, Yancheng; Schefuß, Enno; Mollenhauer, Gesine; Hefter, Jens; Alexandre, Felipe; Mulitza, Stefan; Sampaio, Gilvan (2018): HS1 records bases on isotope, inorganic and organic geochemistry of sediment cores GeoB16224-1 and GeoB16212-2. PANGAEA, https://doi.org/10.1594/PANGAEA.887797, Supplement to: Crivellari, S et al. (2018): Increased Amazon freshwater discharge during late Heinrich Stadial 1. Quaternary Science Reviews, 181, 144-155, https://doi.org/10.1016/j.quascirev.2017.12.005
Fine particles and colloids, attached to grain surfaces, are abundant in the earths subsurface. Under certain conditions these particles can be released from the matrix and transported with the mobile phase. One of the mechanisms for sudden particle release is a decrease in groundwater salt concentration below the critical salt concentration (CSC), where repulsion forces between fine particles and matrix surfaces exceed binding forces. Typically, CSCs are determined with column experiments, where salt solutions with specific concentrations are applied to the matrix of interest. In this study it was attempted to determine the CSC with batch experiments as well as columns. Two types of sediment were tested: (a) pure, mineralogically homogeneous silica sand; and (b) mineralogically heterogeneous sandy sediment, taken from the Hanford formation in southeast Washington. Stepwise decreasing concentrations of salt solution (NaNO₃) were applied until fine particles were released from the sediments ...
Stapel, Janina Gabriele; Schirrmeister, Lutz; Overduin, Pier Paul; Wetterich, Sebastian; Strauss, Jens; Horsfield, Brian; Mangelsdorf, Kai (2016): Biogeochemistry of sediment core BK-8. PANGAEA, https://doi.org/10.1594/PANGAEA.867980, In supplement to: Stapel, JG et al. (2016): Microbial lipid signatures and substrate potential of organic matter in permafrost deposits: Implications for future greenhouse gas production. Journal of Geophysical Research: Biogeosciences, 121, 15 pp, https://doi.org/10.1002/2016JG003483
The sediment to water diffusive flux of PAHs and PCBs was measured under field conditions with a novel infinite-sink benthic flux chamber that deployed semipermeable membrane devices (SPMD) as a sorbing material. Fluxes were measured before and after in situ capping of sediments in Oslo Harbour with clean clay. The fluxes of native pyrene and PCB 52 from uncapped contaminated sediment measured with the flux chamber were 0.3-1.6 mu g m(-2) d(-1) and 2-8 ng m(-2) d(-1), respectively. Fluxes from the capped sediment were reduced by 93-97%. The in situ measured fluxes were compared to fluxes independently calculated from freely dissolved concentrations in pore water and overlying water, measured using equilibrium passive samplers, diffusive boundary layer (DBL) thickness, measured by an alabaster dissolution method and literature values of diffusion coefficients. Measured fluxes from the uncapped sediment agreed well with calculated fluxes, the median of the ratio of the measured flux over the ...
Primary research in my Sediment Geochronology and Seabed Processes group centers on sediment dispersal and the accumulation of fine-grained sediments in continental margin environments. We study the environmental record preserved in marine sedimentary sequences to provide insight into continental margin evolution, human and natural changes, paleoclimate, and paleoseismicity. The formation of marine sedimentary strata rarely results from the simple settling of sedimentary material to the sea floor, but rather from the complex interaction of physical, chemical, and biological processes operating in the marine environment. These processes, such as resuspension and biological mixing, impart characteristic signatures to the sediment and control the burial and preservation of important sedimentary components such as organic carbon and anthropogenic materials. We are investigating the characteristics of recent sedimentary strata on spatial scales ranging from less than a mm to 100s of meters and on ...
Looking for Organic sediment? Find out information about Organic sediment. a necessary minor component of soils, surface and subterranean waters, most rocks , and also the atmosphere . Plants are the primary source for organic... Explanation of Organic sediment
The FVGR is dropped to the seafloor; once there, it lowers four, square "grabs" into the sediment. The grabs enclose a specified volume of sediments, the water overlying the sediments, and the animals and microbes living within them. Right now, and for up to five days from now, these grabs will be left in place, measuring oxygen concentrations in the overlying water to measure the amount of biological activity occurring in the sediment. Through these measurements, estimates of sediment community oxygen consumption (SCOC)-a way of measuring biological activity on the seafloor-have been tracked for over 20 years at Station M. Through long-term sampling, the Smith lab has learned that the benthos (seafloor) at Station M, and probably other regions of the deep sea, appears to consume oxygen at a higher rate than the food arriving to the seafloor would suggest is possible. However, episodic events such as intense falls of detrital aggregates, or "marine snow," from surface waters may provide the ...
Purpose: Recently, a proof-of-concept study revealed the suitability of transcriptome analyses to obtain and assess changes in the abundance of transcripts in zebrafish (Danio rerio) embryos after exposure to organic sediment extracts. The present study investigated changes in the transcript abundance in zebrafish embryos exposed to whole sediment samples and corresponding organic extracts in order to identify the impact of different exposure pathways on sediment toxicity.. Materials and Methods: Danio rerio embryos were exposed to sublethal concentrations of three sediment samples from the Danube River, Germany. The sediment samples were investigated both as freeze-dried samples and as organic extracts. Silica dust and a process control of the extraction procedure were used as references. After exposure, mRNA was isolated and changes in profiles of gene expression levels were examined by an oligonucleotide microarray. The microarray results were compared with bioassays, chemical analysis of the ...
We present data showing that arsenic (As) was codeposited with organic carbon (OC) in Bengal Delta sediments as As and OC concentrations are highly (p , 0.001) positively correlated in core profiles collected from widely dispersed geographical sites with different sedimentary depositional histories. Analysis of modern day depositional environments revealed that the As−OC correlations observed in cores are due to As retention and high OC inputs in vegetated zones of the deltaic environment. We hypothesize that elevated concentrations of As occur in vegetated wetland sediments due to concentration and retention of arsenate in aerated root zones and animal burrows where copious iron(III) oxides are deposited. On burial of the sediment, degradation of organic carbon from plant and animal biomass detritus provides the reducing conditions to dissolve iron(III) oxides and release arsenite into the porewater. As tubewell abstracted aquifer water is an invaluable resource on which much of Southeast ...
Vancouver, July 10, 2020 - Canasil Resources Inc. (TSX-V: CLZ, DB Frankfurt: 3CC, Canasil or the Company) announces that the drill rig has been positioned on site and the planned drill program is underway to test the Candy vein, the initial silver-gold ve ...
PANGAEA - Publishing Network for Geoscientific and Environmental Data. (Table 1) Counts and concentrations of pollen, spores and dinoflagellate cysts in sediment core MD01-2378. Occurrence Dataset https://doi.org/10.1594/pangaea.738109 accessed via GBIF.org on 2017-12-15 ...
View Research Brief as PDF(204KB). Release Date: 03/04/2009. Background: Sediments are the recipients of most organic and inorganic contaminants released into the environment. They are often contaminated with mixtures of polycyclic aromatic hydrocarbons (PAHs), as well as polychlorinated biphenyls (PCBs), pesticides, heavy metals, and other compounds. While there are extensive data to confirm that PAHs and other sediment contaminants are toxic to aquatic receptors, information about the bioavailability and genotoxicity of complex mixtures to aquatic organisms is limited.. The results of chemical analysis generally do not predict toxicity in a biological system, particularly for complex pollutant mixtures such as PAHs or PCBs. Dr. K.C. Donnelly, Texas A&M University SBRP, believes that a battery of biomarkers provides a valuable tool that can adequately characterize subtle, sublethal, or genotoxic effects of chemical mixtures. Much like different instruments or detectors can be used to detect ...
Figure 3: Colored shaded relief bathymetric image of the Chile Triple Junction region based on SEABEAM swath data acquired by the R/V Robert D. Conrad, showing the locations of seismic lines 745 and 751. The SEABEAM system is a hull-mounted array of acoustic transducers and associated control and recording computers and other electronics that measures the depth of the water in many discreet points ont he seafloor in a wide swath, widdth roughly 80% of the water depth, to the sides of the vessel. This enables scientists to quickly produce extremely accurate bathymetric maps of the seafloor. In regions where the shape of the seafloor reflects active tectonic or sedimentary processes, this kind of data is very important for understanding those processes. Also shown are Ocean Drilling Program Leg 141 drillsites 859, 860, and 861. The toe of the landward trench slope adjacent to the pre-contact zone is characterized by an escarpment varying between 300 and 500 m high. The strike and position of the ...
This dataset was compiled to quantify degradation of terrigenous organic carbon in surface sediments across the Laptev and East Siberian Sea. It includes raw data that has been published in different studies as well as derived parameters such as fraction terrigenous, fraction fine, transport time and degradable fraction terrigenous organic carbon.
In this present study, petroleum hydrocarbons were statistically analyzed in three different coastal sediment cores viz., (N1, P1 and P2) from the Southeast coast of Tamil Nadu, India to examine the viability of PHCs. The significant positive relationship between mud (silt+clay+sand) and PHC unveiled that high specific surface of area of mud content raise the level of PHCs. Cluster analysis was used to discriminate the sediment samples based on their degree of contamination. The present study shows that instead of expensive and destructive PHC chemical methods, magnetic susceptibility is found to be a suitable, cheap and rapid method for detailed study of PHC in marine sediments ...
6 Sediment 6 Carbon Combo - 20 x 2.5 - Quantity of Six Sediment and Six Carbon Block (20 Inch x 2 1/2 Inch) Water Filters This sale is for six (6) 20 inch x 2.5 inch sediment filters and six (6) ...
Rainfresh Sediment Filters reduce sediment, dirt, rust , silt, sand and other particles from water. A sediment filter is a must have for every home.
In this study, sediment samples were collected from 24 sites in the East China Sea (ECS) to investigate the distribution characteristics, co-occurrence correlations, and ecological risks of metals....
As SAS is readily biodegradable and not strongly adsorptive to solids, e.g. sediment, exposure of sediment is limited. According REACH Regulation 2006/1907/EEC, Annex X, 9.4, column 2, sediment effects studies need only to be carried out if direct and indirect exposure is indicated by the chemical safety assessment. As demonstrated in the CSR chapters 9 and 10, sediment exposure and risk is very low. Nevertheless a 3-day chronic nematode study was carried out resulting in a NOEC reproduction of 939 mg/kg dw. Based on this NOEC a PNEC freshwater sediment of 9.4 mg/kg dw (a.i.) was calculated and can be compared with the PNEC freshwater sediment equil. partit. of 2.9 mg/kg dw based on aquatic effect data. ...
doi:10.2973/odp.proc.sr.138.1995. For more information about how to use this volume, where to download Adobe Reader, or comments, see the User Guide. In cooperation with the Ocean Drilling Program, the Texas A&M University Digital Library produced this electronic version from the original print volume. Volume and chapter citations have been updated since original publication to include a Digital Object Identifier (DOI) to facilitate online access to scholarly and professional content (see Citations Related to ODP Legs for updated citations).. ...
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The earliest sediments identified of late Pleistocene age are quiet-water calcarenites, containing abundant molluscs but few corals. As waters shallowed these were replaced by emergent intertidal sediments, probably colonized by mangroves. Further emersion into subaerial conditions resulted in cementation and solution of the limestones to form a dissected karst topography. Perhaps concurrent with this, phosphates, probably originally derived from sea birds, were deposited in open cavities. Further marine withdrawal caused the erosion and re-deposition of these phosphatic sediments at a lower level. A succeeding event was the formation of a sand cay at the western end of the atoll. Its emergent surface was colonized by tortoises, birds, crocodiles and snails, and the youngest deposits indicate the presence of at least seasonal bodies of standing fresh water. This terrestrial interlude was followed by inundation by a sea, perhaps 2-3 m higher than the present level, in which was deposited a fairly ...
Field lysimetry and porewater sampling allow researchers to evaluate the fate of chemicals applied to soils and established vegetation. ...
Bed sediments and a dated sediment core were collected upstream and downstream from the city of Lyon (France) to assess the spatial and temporal trends of contamination by per- and polyfluoroalkyl substances (PFASs) in this section of the Rhône River. Upstream from Lyon, concentrations of total PFASs (ΣPFASs) in sediments are low (between 0.19 and 2.6 ng g⁻¹ dry weight - dw), being characterized b ...
RISK ASSESSMENT OF SCIENTIFIC SONARSELKE BURKHARDT1, OLAF BOEBEL1, HORST BORNEMANN1 AND CHRISTOPH RUHOLL11 Alfred Wegener Institute for Polar and Marine Research, P.O. Box 12016, 27515 Bremerhaven, GERMANY. [email protected] Introduction Scientific sonars form an important asset to conduct oceanographic, geophysical and biological research and are hence installed in many research vessels. Multibeam deep-sea echosounder map the sea-floor topography at high resolution, enabling researchers to identify sites of environmental importances such as cold water coral reefs and sea mounts, to locates suitable sites for oceanographic, geophysical and biological studies such as deep water passages and ice-berg grounding sites, and to develop navigational charts, also in the context of defining marine protected areas. Sediment echosounder explore the upper sediment layer stratification to determine location and thickness of sediment layers for coring sites for paleooceangraphic and sedimentological ...
Alkaline phosphatase (AP) catalyzes the hydrolytic cleavage of phosphate monoesters under alkaline conditions and plays important roles in microbial ecology and molecular biology applications. Here, we report on the first isolation and biochemical characterization of a thermolabile AP from a metagenome. The gene encoding a novel AP was isolated from a metagenomic library constructed with ocean-tidal flat sediments from the west coast of Korea. The metagenome-derived AP (mAP) gene composed of 1,824 nucleotides encodes a polypeptide with a calculated molecular mass of 64 kDa. The deduced amino acid sequence of mAP showed a high degree of similarity to other members of the AP family. Phylogenetic analysis revealed that the mAP is shown to be a member of a recently identified family of PhoX that is distinct from the well-studied classical PhoA family. When the open reading frame encoding mAP was cloned and expressed in recombinant Escherichia coli, the mature mAP was secreted to the periplasm and lacks an
98% to the coast). However, further partition of the fluvial sediment reaching the coast heavily favored one distributary over the others (i.e., the Chilia; ∼70%). Consequently, the two active delta lobes of St. George II and Chilia III were built. contemporaneously but not only the morphologies of these lobes were strikingly different (i.e., typical river dominated for Chilia and wave-dominated for St. George; Fig. 2) but also their morphodynamics was vastly dissimilar reflecting sediment availability and wave climate (Fig. 3). The second major distributary, the CB-839 St. George, although transporting only ∼20% of the fluvial sediment load, was able to maintain progradation close to the mouth on a subaqueous quasi-radial "lobelet" asymmetrically offset downcoast. Remarkably, this lobelet was far smaller than the. whole St. George lobe. However, it had an areal extent half the size of the Chilia lobe at one third its fluvial sediment feed and was even closer in volume to the Chilia lobe ...
Developed a numerical sedimentary process model for subsurface characterization and evaluation of contaminant transport; specifically, the model simulated the deposition of sediments in a meandering river and its floodplain and the resulting depositional patterns were assessed for contaminant transport behavior. The model simulated annual floods, sediment transport, channel migration and cut-off, overbank flow and deposition, and crevasse-splay development. The depositional patterns predicted by the model were related to the hydrologic and sediment inputs, compared to those observed in a subsurface formation, and assessed for an impact on contaminant transport. Supporting activities included interpretation of geophysical logs, stratigraphic correlation, and statistical analysis of depositional patterns.. PUBLICATIONS AND PRESENTATIONS. Juergens, L.J. and Small, M.J. April 1990. "A Model of Channel Deposition and Resulting Interconnectedness and Dispersion," EOS Transactions, American Geophysical ...
Introduction. Salt marshes in temperate regions are very productive natural vegetations. These vegetations frequently reach an above-ground production of more than 1 kg of dry weight per m 2per year. Herbivores consume only a small proportion of the annual plant production. Almost the entire amount of above ground plants dies after senescence. A small proportion may be washed away by the tides, but the major part remains at the salt marsh where it decomposes in the canopy or at the sediment surface.. Dead plant material is primarily decomposed by micro-organisms, such as fungi and bacteria. The chemical composition of the detritus to a large extent determines the rate of decomposition. A number of abiotic factors, such as temperature and humidity, also influence the decomposition process. In addition the process may be affected by fauna, present on the decomposing plant material.. In this thesis the role of nematodes in decomposition of Spartina anglica was studied. This plant species commonly ...
My research interests are primarily in the area of fluvial geomorphology, with a particular focus on sediment transport. I use a combination of numerical modelling and field measurements to quantify sediment processes. In both approaches I am interested in the application of new techniques, for example the use of Discrete Element and Cellular Automaton models, CT scanning and Terrestrial Laser Scanning. See http://www.nercpatches.org for a current project. A key focus of my research is the way in which small scale processes upscale, for example the way in which the properties and interactions of sediment grains affect sediment flux at the reach scale. I am happy to be contacted about possible PhD projects in these areas. ...