The Geochemical Partitioning and Bioavailability of Trace Metals in Marine Sediments PDF Download
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Author: Stewart M. Oakley
Publisher:
ISBN:
Category : Biogeochemistry
Languages : en
Pages : 84
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Book Description
Author: Stewart M. Oakley
Publisher:
ISBN:
Category : Biogeochemistry
Languages : en
Pages : 84
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Book Description
Author: Stewart M. Oakley
Publisher:
ISBN:
Category : Marine sediments
Languages : en
Pages : 92
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Book Description
Trace metals in the aquatic environment are generally concentrated on the surface of solid geochemical phases which eventually become incorporated into estuarine and marine sediments. The mechanism of trace metal concentration is believed to be adsorption with various geochemical phases such as hydrous metal oxides, clays, and organic matter. Metals in estuarine or marine sediments can thus be expected to be partitioned between different phases, depending on the concentration of the phase and the strength of the adsorption bond. The bioavailability of sediment-bound metals to deposit-feeding organisms will depend on trace metal partitioning and the kinetics of biological metal uptake from each geochemical phase. The present study was undertaken to develop models for trace metal partitioning and bioavailability in marine sediments. An equilibrium adsorption model was developed that can be used to predict the partitioning of trace metals between different geochemical phases in aquatic sediments from laboratory studies. The model uses conditional equilibrium constants determined from the linear portion of an adsorption isotherm. Conditional equilibrium constants deterit mined for the adsorption of Cu and Cd on bentonite clay, Fe(OH)3, Mn02, and humic acid in seawater show that the model is applicable for trace metal concentrations existing in the natural environment. Based on the laboratory results, the model predicts that the clay fraction may be a major sink for Cu and Cd in marine sediments. A kinetic bioavailability model was then developed which can be used to estimate the relative bioavailability of trace metals from both different sediment phases and seawater under short-term laboratory conditions. This model was used to determine the bioavailability of Cu and Cd from several sediment phases (bentonite clay, humic acid, Fe(OH)3) and seawater to the deposit-feeding polychaete worm, Abarenicola pacifica. The results suggest that, under natural conditions similar to those used in this study, the bioavailability of sediment-bound Cu and Cd to A. pacifica can be much more significant than that of seawater.
Author: Stewart M. Oakley
Publisher:
ISBN:
Category :
Languages : en
Pages : 92
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Book Description
Author: P. G. C. Campbell
Publisher:
ISBN:
Category : Aquatic organisms
Languages : en
Pages : 326
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Book Description
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309040957
Category : Science
Languages : en
Pages : 506
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Book Description
The pervasive, widespread problem of contaminated marine sediments is an environmental issue of national importance, arising from decades of intentionally and unintentionally using coastal waters for waste disposal. This book examines the extent and significance of the problem, reviews clean-up and remediation technologies, assesses alternative management strategies, identifies research and development needs, and presents the committee's major findings and recommendations. Five case studies examine different ways in which a variety of sediment contamination problems are being handled.
Author: Arthur J. Horowitz
Publisher: CRC Press
ISBN:
Category : Business & Economics
Languages : en
Pages : 152
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Book Description
This book provides a basic introduction to sediment-heavy metal interactions and how sediment chemical data can be used to address environmental questions and issues. It is designed to promote self-teaching and is written so that students and professionals with a minimum of formal training in the environmental sciences can understand it. The book addresses all of the major physical and chemical factors that control sediment-trace element chemistry, as well as sampling and sampling design, data manipulation, and data interpretation. Following in the steps of the successful first edition, which was used as a text for a three day short course for U.S. Geological Survey professionals interested in sediment trace chemistry and its application to water quality issues, A Primer on Sediment-Trace Element Chemistry, 2nd Edition is ideal for academics, geochemists, chemists, hydrologists, environmental lawyers, and water quality professionals needing a comprehensive introduction to this field.
Author: Edward D. Burton
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages :
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Book Description
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.
Author: A. Tessier
Publisher:
ISBN:
Category : Trace elements
Languages : en
Pages :
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Author:
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 692
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Book Description
Author: Gehan Mohamed El Zokm
Publisher: Springer Nature
ISBN: 3031292030
Category : Heavy metals
Languages : en
Pages : 118
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Book Description
The goal of this one-of-a-kind book was to provide a critical and in-depth understanding of various AVS-SEM models as predictors for assessing the ecological impact of heavy metals (particularly dibasic cations; Zn, Cd, Ni, Cu, and Pb) on aquatic environments, including the theories underlying these models, descriptive equations, modes of action, methodology, efficiency, applicability, and statistical approaches, as well as comparison with other pollution assessment techniques in the aquatic environments. Metals in interstitial water can be reduced in sediments that co-precipitate with iron (Fe) and manganese (Mn) in FeS or MnS minerals, as well as replace them. This book outlines a system that can be used to track heavy metal contamination in countries with coastal regions that extend over water bodies that are subjected to pollution sources, such as the Mediterranean Basin countries. Moreover, this book will be of great interest to academics, professionals, practitioners, post-graduate students (M.Sc. and Ph.D.), and undergraduates because it gives a clear overview of heavy metal assessment for people interested in environmental studies focusing on the marine environment. It also provides decision-makers with a realistic perspective of the environmental file, allowing them to address environmental issues and directing stockholders to safer locations for environmental activity. From a future perspective, management is advised to overcome the difficulties within that technique, such as accurate handling procedures and different approaches to sampling onshore and offshore. Sequential leaching strategies, especially geochemical fractionation analysis, and knowledge of the interactions and significance of AVS in the marine sector, especially toxicity tests (bioassay) are recommended.
