Download or read book Influence of Organic Matter on Trace Metal Flux in Coastal Sediments Sequim Bay written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: These studies indicate that organic matter in coastal sediment constitutes a primary sink for trace metals, both at natural and amended levels. Organic substances are also involved in controlling the mobility and flux of trace metals from sediments. Further, organically-bound trace metals in sediments appear to be an important source to deposit-feeding organisms.

Download or read book Influence of Organic Matter on Trace Metal Flux in Coastal Sediments written by R. L. Schmidt and published by . This book was released on 1978 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1978 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mobilisation of Sedimentary Trace Metals Following Improved Oxygen Conditions written by and published by Nordic Council of Ministers. This book was released on 1999 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Trace Metal and Nutrient Cycling in San Francisco Bay written by and published by . This book was released on 1998 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The long term goals of this project are to examine the influence of metal flux (primarily Cu, Cd, As, Co, Mn and Fe) from sediments on the concentration of dissolved metals in the coastal zone and embayments. The processes that control trace metal exchange across the sediment-water interface within coastal environments regulate the concentration of dissolved, bioactive metals in the water column. These processes include variations in the relative influence of transport mechanisms (diffusion versus bio-irrigation), microbial activity (anaerobic versus aerobic respiration), as well as geochemical reactions (redox reactions, precipitation, complexation and adsorption) that regulate the behavior of dissolved metals in pore waters. All of these processes are controlled by the activity and composition of the sediment community. The role of organic carbon remineralization on trace metal mobility at a biologically active interface is, therefore, the focus of this study.

Download or read book Metal Contaminated Aquatic Sediments written by HerbertE. Allen and published by Routledge. This book was released on 2018-04-27 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade the sediments of many rivers, lakes, and estuaries have been contaminated by inorganic and organic materials. Contaminants from sediments, under certain conditions, can be released into overlying waters. Thus, sediments may be an important source of contaminants to waters in which littoral and atmospheric contaminants have been reduced or eliminated. Often found in aquatic sediments, metals are exposed to many reactions, such as sorption and precipitation, and are greatly influenced by the redox conditions in the sediment. The reactions - usually over a period of time - reflect biotic processing as well as chemical transformations. This book describes these important processes. Metal Contaminated Aquatic Sediments outlines advances in environmental chemistry, effective new modeling techniques, applications for biological treatment, and cycling and transport of trace metals in sedimentary environments. Each chapter contains a detailed reference section that draws upon a stunning array of sources. The book includes many figures and tables that illustrate the process under discussion. Features

Download or read book Trace Metal and Organic Matter Diagenesis in Deep sea Sediments written by Ian Scutton and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Studies on the Interactions Between Organic Matter Trace Metals and Sulfur in Recent and Ancient Sediments written by Erdem Fahri Idiz and published by . This book was released on 1989 with total page 301 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanisms of Metal Release from Contaminated Coastal Sediments written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: By Linda H. Kalnejais.

Download or read book Particulate Trace Metal Fluxes in the Western Arabian Sea and Their Links to Marine Productivity written by Kelly M. Flannery and published by . This book was released on 2015 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many trace elements (e.g., Zn, Cd, Mo) are essential phytoplankton micronutrients, making them crucial to the marine ecosystem and ultimately the carbon cycle. Because of this association trace metals are also utilized in paleoceanographic studies (e.g., Mo, Cd). However, not much is known about what controls the cycling of these trace metals in seawater. The primary goal of this study was to improve our understanding Ag, Mo and Cd cycling, focusing on the particulate phase, so that we can understand what influences their delivery to the seafloor. The concentrations of trace metals (i.e., Ag, Mo, and Cd) and minor elements (i.e., Al, Ba, Mn, Zn) were measured in sediment trap samples collected at three sites in the western Arabian Sea; two high productivity nearshore sites (MS2 and MS3) and one oligotrophic gyre site (MS5). The concentrations of these metals were converted to fluxes and compared to four commonly utilized productivity proxies; particulate organic carbon (POC), total barium (Ba), opal, and carbonate (CaCO3). Particulate Ag flux increases with increasing trap depth at both MS2 and MS3, but decreased with increasing trap depth at MS5. Ag flux also shows a strong positive correlation with particulate organic carbon (POC), as well as opal and Ba. These data suggest that at the high productivity sites, Ag is accumulates in settling, organic-rich particles. There is no evidence that the intense Oxygen Minimum Zone, which characterizes the Arabian Sea, is influencing Ag accumulation. Nor is Ag simply related to the opal flux, refuting the idea that Ag is delivered to the seafloor by diatom frustules. Instead, dissolved Ag concentrations and POC and/or total particle flux are probably the main controls on particulate Ag formation. Particulate Mo flux also positively correlates well with POC flux, suggesting it might be scavenged onto particulate organic matter. There is also evidence of Mo scavenging by Mn oxyhydroxides in the deep trap. Therefore particulate Mo flux to the seafloor seems to be controlled by both POC flux and Mn oxyhydroxide formation. Particulate Cd is organic, despite the fact that Cd and POC fluxes do not correlate particularly well due to the unusual behavior of POC. In summary, all three of the trace metals studied show evidence of a link to organic carbon flux. Particulate Cd and Mo, as well as Ag at MS5, are found within, or possibly absorbed on to, the organic matter. They are cycled with this organic matter and thus their fluxes decrease with water depth. Very little of these metals will make it to the seafloor in deep ocean. Particulate Ag at the high productivity stations (MS2 and MS3) behaves differently. It is scavenged by sinking organic-rich particles and fluxes increase with water depth. Therefore, large amounts of particulate Ag could reach the seafloor, at least in regions characterized by high productivity.

Download or read book Trace Metal organic Matter Interactions During Early Diagenesis in Anoxic Estuarine Sediments written by George Daniel Templeton and published by . This book was released on 1982 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nutrient and Trace Metal Cycling in Beach Sediments and Its Constituent Fluxes Across the Sediment water Interface written by Janis Ahrens and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Redox sensitive Trace Metals and Nutrients in Sediments and Pore Waters of the Gulf of Mexico written by Claire Miller and published by . This book was released on 2014 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Trace Metal organic Matter Interactions During Early Diagenesis in Anoxic Estuarine Sediments written by George Daniel Templeton III. and published by . This book was released on 1980 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Trace Metals in Sediments on the Continental Margin of the Northwest Atlantic Ocean written by Daniel L. Marsh and published by . This book was released on 2013 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trace metals in the ocean are derived from natural and anthropogenic sources. Despite increased human impact on the marine environment and biological productivity of continental margins, trace metal studies in marine sediments have focused primarily on near-shore regions. I investigated 22 metals in sediments on the continental margin of the northwest Atlantic Ocean to calculate enrichment factors (EF) relative to upper continental crust and identify spatial variations with distance from shore and depth below the sediment-seawater interface. Metals were well correlated with Al, Fe, organic matter, or CaCO3. No clear trends in metal EFs with distance from shore were evident on a station by station basis, but consistent differences among regions of the continental margin were evident. Significant near-shore enrichment was observed. Enrichment was also evident for As, Hg, Mn, and Ni in sediments farther off-shore, suggesting the influence of human activities or hydrothermal vent emissions have enriched deep ocean sediments.

Download or read book Distribution and Partitioning of Trace Metals and Tributyltin in Estuarine Sediments written by Edward D. Burton and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: An improved understanding of the geochemical partitioning of trace metals and tributyltin (TBT) in sediments is of great importance in risk assessment and remedial investigation. The aim of this thesis was to examine the distribution and partitioning behaviour of trace metals and TBT in benthic, estuarine sediments. This was achieved by a series of field- and laboratory-based studies investigating factors controlling the geochemical behaviour of trace metals and TBT in sediments from south-east Queensland, Australia. The distribution and enrichment of selected trace metals in benthic sediments of the Southport Broadwater (a semi-enclosed coastal body of water adjacent to the Gold Coast city, south-eastern Queensland, Australia) was studied. Sediment contamination for Cd, Cr, Cu, Ni, Pb, Sn and Zn was assessed by (1) comparison with Australian sediment quality guidelines, (2) calculation of the index of geoaccumulation based on regional background values, and (3) geochemical noi-malisation against Al (i.e. the abundance of alumino-silicate clay minerals). Based on this approach, several sites were found to be strongly enriched with Cu, Pb, Sn and Zn, arising from sources related to either urban runoff or vessel maintenance activities. The geochemical partitioning of Cu, Pb and Zn was examined in sediments collected from three of these sites of sediment contamination. Total Cu, Pb and Zn concentrations in coarse-textured (65 to 90 % sand sized particles), sub-oxic sediments (Eh + 120 to +260 mV) ranged from 8.3 to 194 mg/kg for Cu, 16.3 to 74.8 mg/kg for Pb and 30.1 to 220 mg/kg for Zn, and were related to vertical trends in sediment texture. The association of Cu, Pb and Zn with amorphous oxides, crystalline oxides and organic matter was linearly dependent on the abundance of each phase. For retention by amorphous oxide minerals, the trace metal retention ranged from 5.2 to 23.7 mgcjgFe oxide as Fe for Cu, 1 2.8 to 21 .5 mgpb/gFe oxide as Fe for Pb, and 23. I to 85.7 mgm/gFe oxide as Fe for Zn. Corresponding values for association with crystalline oxides were an order of magnitude less than those for amorphous oxides, indicating a weaker affinity of trace metals for crystalline oxides. The relationships describing association with organic matter ranged from 17.6 to 54.0 mgcu/gorg c for Cu, 6.1 to 9.6 mgpb/gorg c for Pb and 6.4 to 16.4 mgzn/gorg c for Zn. The in-situ solid/pore-water partitioning of TBT and the degradation products, dibutyltin (DBT) and monobutyltin (MBT), was determined for an estuarine sediment profile with previously identified elevated Sn concentrations. Total butyltin levels were (depending on depth) 220 to 8750 jig/kg for TBT, 150 to 5450 jig/kg for DBT and 130 to 4250 jig/kg for MBT. Pore-water butyltin concentrations ranged from 0.05 to 2.35 jig/L for TBT, 0.07 to 3.25 jiglL for DBT, and 0.05 to 0.53 J.tgIL for MBT. The organic carbon normalised distribution ratios (Doc) were similar for TBT, DBT and MBT, and were io to 106 L/kg. Values for the Butyltin Degradation Index (BDI) were larger than I at depths greater than 10 cm below the sediment/water-column interface, indicating that substantial TBT degradation has occurred in the sediments. This suggests that natural attenuation may be a viable sediment remediation strategy. Factors controlling the partitioning behaviour of Cu, Pb and Zn in nonsulfidic, estuarine sediments were examined in controlled laboratory-based studies with the use of combined sorption curve - sequential extraction analysis. This allowed determination of sorption parameters for Cu, Pb and Zn partitioning to individual geochemical fractions. Partitioning behaviour in sulfidic sediments was also determined by sequentially extracting Cu, Pb and Zn from synthetic sulfide minerals, and from natural sediment and pure quartz sand after spiking with acid-volatile sulfide (AVS). Trace metal sorption to the 'carbonate' fraction (pH 5, NaOAc extraction) increased with metal loading due to saturation of sorption sites associated with the 'Fe-oxide' (NH2OH. HCI extraction) and 'organic' (H202 extraction) fractions in non-sulfidic sediments. Freundlich isotherm parameters describing sorption to the 'Fe-oxide' and 'organic' fractions were dependent on the sediment Fe-oxide and organic carbon content, respectively. Sequential extraction of Cu from pure CuS, AVS-spiked sediment and AVS-spiked quartz sand showed that AVS-bound Cu was quantitatively recovered in association with the 'organic' fraction. However, some AVS-bound Pb and Zn were recovered by the NH2OH. HCI step (which has been previously interpreted as 'Fe-oxide' bound metals) in the sequential extraction procedure used in this study. This indicates that the sequential extraction of Pb and Zn in sulfidic sediments may lead to AVS-bound metals being mistaken as Fe-oxide bound species. Caution should therefore be exercised when interpreting sequential extraction results for Pb and Zn in anoxic sediments. Tributyltin (TBT) sorption to four natural sediment samples in artificial seawater was also examined under a range of modified pH and salinity conditions in controlled laboratory-based studies. Three of the sediment samples were relatively pristine with regard to TBT contamination, but the fourth was a TBT-contaminated sediment from a commercial marina. Sorption of TBT was described well by linear sorption isotherms, with distribution coefficients ranging from 6.1 to 5210 L/kg depending on pH and salinity. Sediment organic C content and particle size distribution were important determinants of sorption behaviour. The presence of resident TBT in the contaminated marina sediment caused a substantial reduction in TBT sorption due to satuaration of high selectivity sites. Desorption of TBT from the marina sediment was described by relatively large observed distribution coefficients ranging from 5100 to 9400 L/kg, suggesting that aging effects may reduce sorption reversibility. Increased artificial seawater salinity generally reduced TBT sorption at pH 4 and pH 6, but enhanced TBT sorption at pH 8. Regardless of salinity, maximum sorption of TBT was observed at pH 6, which is attributed to an optimal balance between abundance of the cationic TBT species and deprotonated surface ligands. Consideration of aqueous TBT speciation along with octanol-water partitioning behaviour suggest that hydrophobic partitioning of TBTCI to non-polar organic matter was important for pH (up to) 6, whilst partitioning of TBTOH was important at higher pH. The effect of aging on the solid/pore-water partitioning and desorption behaviour of TBT in sediments was examined. Three sediment samples with contrasting physical and chemical properties were spiked with 10 mg/kg TBT and aged under sterile conditions for periods of time ranging from I to 84 days. Aging had a negligible effect in a sandy sample with very low organic carbon content (0.2 % w/w). In contrast, for samples with larger amounts of organic carbon (2.6 and 4.8 % w/w), the effect of aging on the solid/pore-water partitioning behaviour was significant. For these samples, the apparent distribution coefficients (Ks) obtained from sequential two hour desorption experiments exhibited a two-fold increase between spiked sediments subjected to aging for 1 day and 84 days. This study demonstrates that aging effects may be an important aspect of TBT fate in contaminated sediments. Overall, the results described in this thesis demonstrate that environmental factors (i.e. pH, salinity, Eh, aging) and sediment composition (i.e. abundance of fine alumino-silicate minerals, organic matter, Fe-oxides, reactive sulfides) exert substantial effects on trace metal and TBT partitioning. The current reliance on measurement of total trace metal and TBT concentrations in contaminated sediment management may consequently lead to inaccurate estimates of environmental risk and inappropriate remediation measures if other factors regulating contaminant distribution and partitioning are ignored.

Download or read book Oxygen and Dissolved Organic Carbon Dynamics in Permeable Coastal Sediments written by Lindsay Chipman and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: A large fraction of the continental shelf is covered by permeable sediments that are flushed by wave, wind, and tide generated bottom currents. Elevated dissolved organic carbon (DOC) concentrations in coastal zones, a diverse and abundant sediment microbial community, and advective filtration of seawater through the surface layers of permeable sediments, make these environments important zones for the cycling of organic matter. This research investigates the role of permeable sediments in the dynamics of two central components of the carbon cycle: DOC and oxygen. In Chapter 2, published in Limnology & Oceanography, I investigate decomposition rates and compositional changes of DOC when filtered through permeable sediments contained in laboratory column reactors. Substantial amounts of DOC were mineralized in the sediments and could be linked to incorporation by aerobic and anaerobic microbes. In DOC pore-water profiles measured at two study sites with permeable sediment, we observed a concave shape of the profiles in the upper 10 cm of permeable sediment resulting from transport of DOC with advective pore water flows into the sand, and DOC decomposition in the subsurface layers. We found that the flushed sand layer between the water column and deeper anoxic sediment layers acts as an effective DOC filter, with subsurface horizontal pore-water flows promoting decomposition of DOC, suggesting that permeable sediments play a key role in the cycling of organic matter. In Chapter 3, submitted to Continental Shelf Research, I use the findings of Chapter 2 for the interpretation of field time series data of DOC, DIC, and TN concentrations in the water column and coastal sediment pore waters. We use these time series to investigate the spatial and temporal dynamics of dissolved organic matter and how benthic pelagic coupling influences DOC concentrations in the permeable sediments. Our results reveal that DOC in the upper layer (0-12 cm) of the shallow sands is controlled by benthic-pelagic coupling facilitated by advective pore water filtration modulated by the regional wave climate. For the quantification of oxygen fluxes in the permeable coastal sands resulting from the benthic organic matter production and consumption and the current-induced sediment flushing, I deployed the eddy correlation technique. In order to make this technique more suitable for our shallow coastal zone with relatively rough hydrodynamic conditions (as compared to deeper marine environments), we adapted existing eddy correlation instruments for use with more durable and repairable oxygen optodes. This development is described in detail in Chapter 4 that has been submitted for publication in Limnology and Oceanography Methods. Our results show that optodes have a comparable response time to electrodes, produce similar fluxes in field deployments, and are a viable alternative for use with the eddy correlation measurement in coastal environments with strong currents and wave action. These hydrodynamic conditions are an important factor controlling production and decomposition processes at the sediment-water interface and within the sediment because they can largely control the availability of DOC and oxygen to microbial communities in the sediments. In Chapter 5, which is presently is being prepared for submission to Marine Ecology - Progress Series, we investigate the relationship between flow, wave height, DOC concentration, temperature, light, and the benthic oxygen fluxes. The results reveal a large range of production and consumption rates in the permeable coastal sediments with distinct seasonal changes. The latter are caused by the availability of degradable organic matter and the magnitude of the pore water flushing process that carries these organic substrates and oxygen into the permeable coastal sands. We conclude that the highly degradable DOC produced by pelagic and benthic primary producers enhances water column - sediment biogeochemical coupling in the coastal zone thereby increasing the contribution of the sediment surface layer in the cycling of carbon and nutrients.