38536453
Metal bioavailability and bioaccumulation in the polychaete Nereis (Alitta) virens (Sars): The effects of site-specific sediment characteristics.
The present study investigates the relationships between copper (Cu) and zinc (Zn) concentrations in sediment, pore water and their bioaccumulation in the polychaete Nereis (Alitta) virens, as well as the importance of site-specific sediment characteristics in that process. Sediment, pore water and N. virens were sampled from seven sites with different pollution histories along the English Channel coast. Results showed that site-specific metal levels and sediment characteristics were important in determining the bioavailability of metals to worms. Significant correlations were found between Cu in the sediment and in the pore water and between Zn in the pore water and in N. virens. Zn from the pore water was thus more readily available from a dissolved source to N. virens than Cu. Data also showed that metal concentrations in N. virens were lower than those found in other closely related polychaetes, indicating that it may regulate tissue concentrations of Cu and Zn.
129545562
Principles of Ecotoxicology
POLLUTANTS AND THEIR FATE IN ECOSYSTEMS Major Classes of Pollutant Inorganic Ions Organic Pollutants Organometallic Compounds Radioactive isotopes Gaseous Pollutants Summary Further Reading Routes by Which Pollutants Enter Ecosystems Entry into Surface Waters Contamination of Land Discharge into the Atmosphere Quantification of Release of Pollutants Summary Further Reading Long-Range Movements and Global Transport of Pollutants Factors Determining Movement and Distribution of Pollutants Transport in Water Transport in Air Models for Environmental Distribution of Chemicals Summary Further Reading The Fate of Metals and Radioactive Isotopes in Contaminated Ecosystems Introduction Terrestrial Ecosystems Aquatic Systems Summary Further Reading The Fate of Organic Pollutants in Individuals and in Ecosystems Fate within Individual Organisms Organic Pollutants in Terrestrial Ecosystems Organic Pollutants in Aquatic Ecosystems Summary Further Reading EFFECTS OF POLLUTANTS ON INDIVIDUAL ORGANISMS Toxicity Testing General Principles Determination of the Toxicity of Mixtures Toxicity testing with Terrestrial Organisms Toxicity testing with Aquatic Organisms Risk Assessment Toxicity Testing in the Field Alternative Methods in Ecotoxicological Testing Summary Further Reading Biochemical Effects of Pollutants Introduction Protective Biochemical Responses Molecular Mechanisms of Toxicity Examples of Molecular Mechanisms of Toxicity Summary Further Reading Physiological Effects of Pollutants Introduction Effects of Pollutants at the Cellular Level Effects at the Organ Level Effects at the Whole Organism Level in Animals Effects on Plants Energy Costs of Physiological Change Summary Further Reading Interactive Effects of Pollutants Introduction Additive Effects Potentiation of Toxicity Potentiation Due to Inhibition of Detoxification Potentiation Due to Increased Activation The Detection of Potentiation in the Field Summary Further Reading Biomarkers Classification of Biomarkers Specificity of Biomarkers Relationship of Biomarkers to Adverse Effects Discussion of Specific Biomarkers Role of Biomarkers in Environmental Risk Assessment Summary Further Reading In situ Biological Monitoring Introduction Community Effects (Type 1 Biomonitoring) Bioconcentration of Pollutants (Type 2 Biomonitoring) Effects of Pollutants (Type 3 Biomonitoring) Genetically Based Resistance to Pollution (Type 4 Biomonitoring) Conclusions Summary Further Reading EFFECTS OF POLLUTANTS ON POPULATIONS AND COMMUNITIES Changes in Numbers: Population Dynamics Population Abundance Population Growth Rate Population Growth Rate Depends on the Properties of Individual Organisms Density Dependence Identifying Which Factors are Densitivity Dependent: K-Value Analysis Interactions Between Species Field Studies: Three Case Studies Modelling the Effects of Skylarks for Risk Assessment Purposes Summary Further Reading Evolution of Resistance to Pollution Chronic Pollution is Environmental Change The Evolutionary Process in a Constant Environment The Evolution of Resistance When There is a Mortality-Production Trade-Off Evolutionary Responses to Environmental Change Resistance is Often Monogenic Case Studies Summary Further Reading Changes in Communities and Ecosystems Introduction Soil Processes: The Functional Approach Changes in Composition of Communities: The Structural Approach Global Processes Summary Further Reading Extrapolating From Molecular Interactions to Consequent Effects at the Population Level Introduction The Translation of Toxic Effects Across Organizational Boundaries Biomarker Strategies Biomarkers and Environmental Risk Assessment Summary Further Readings Biomarkers in Population Studies DDE-Induced Eggshell Thinning in Raptorial and Fish-Eating Birds Reproductive Failure of Fish-Eating Birds on the Great Lakes of North America Reproductive Failure of Molluscs Caused by Tributyl Tin Forest Spraying in Eastern Canada to Control Spruce Budworm Summary Further Reading Appendix: Introduction to population projection matrices Glossary Bibliography Index
43415410
Soil pH effects on the comparative toxicity of dissolved zinc, non-nano and nano ZnO to the earthworm Eisenia fetida
Abstract To determine how soil properties influence nanoparticle (NP) fate, bioavailability and toxicity, this study compared the toxicity of nano zinc oxide (ZnO NPs), non-nano ZnO and ionic ZnCl2 to the earthworm Eisenia fetida in a natural soil at three pH levels. NP characterisation indicated that reaction with the soil media greatly controls ZnO properties. Three main conclusions were drawn. First that Zn toxicity, especially for reproduction, was influenced by pH for all Zn forms. This can be linked to the influence of pH on Zn dissolution. Secondly, that ZnO fate, toxicity and bioaccumulation were similar (including relationships with pH) for both ZnO forms, indicating the absence of NP-specific effects. Finally, earthworm Zn concentrations were higher in worms exposed to ZnO compared to ZnCl2, despite the greater toxicity of the ionic form. This observation suggests the importance of considering the relationship between uptake and toxicity in nanotoxicology studies.
45296995
Metal-based nanoparticles in soil: fate, behavior, and effects on soil invertebrates.
Metal-based nanoparticles (NPs) (e.g., silver, zinc oxide, titanium dioxide, iron oxide) are being widely used in the nanotechnology industry. Because of the release of particles from NP-containing products, it is likely that NPs will enter the soil compartment, especially through land application of sewage sludge derived from wastewater treatment. This review presents an overview of the literature dealing with the fate and effects of metal-based NPs in soil. In the environment, the characteristics of NPs (e.g., size, shape, surface charge) and soil (e.g., pH, ionic strength, organic matter, and clay content) will affect physical and chemical processes, resulting in NP dissolution, agglomeration, and aggregation. The behavior of NPs in soil will control their mobility and their bioavailability to soil organisms. Consequently, exposure characterization in ecotoxicological studies should obtain as much information as possible about dissolution, agglomeration, and aggregation processes. Comparing existing studies is a challenging task, because no standards exist for toxicity tests with NPs. In many cases, the reporting of associated characterization data is sparse, or missing, making it impossible to interpret and explain observed differences in results among studies.
88602482
A review of the toxicological studies with polychaetous annelids
A total of 48 species in 20 families of polychaetes have been used as test organisms in assessing the effects of toxicants in the marine environment. Members of families Capitellidae, Dinophilidae, Dorvilleidae and Nereidae are the most commonly used species. Tests conducted include 1) acute, in which survival is the criterion; 2) chronic, in which some biological measure, such as growth, is used; and 3) life-cycle tests in which reproduction and the number of offspring produced are the criteria. Toxicants studied include metals, petroleum hydrocarbons, detergents, pesticides, contaminated sediments and radiation. Laboratory cultures have facilitated the testing procedures, especially for the chronic and life-cycle test. The published literature on the effects of loxicants on polychaetes is reviewed by contaminant, and then summarized in tabular forms.
24414696
Exposure to copper induces oxidative and stress responses and DNA damage in the coral Montastraea franksi.
Copper is a common chemical contaminant in coastal environments, including coral reefs. Ecotoxicological studies have demonstrated that exposure to copper can cause stress and detrimental effects in both host cnidarian and algal symbionts. The objective of this study was to investigate the sublethal effects of copper on the reef-building coral Montastraea franksi, by identifying genes with altered expression in corals exposed to dissolved copper, and by measuring the extent of damage to DNA in response to copper exposure. Corals exposed to 30 μg L(-1) copper for 48 h experienced significant DNA damage and displayed changes in expression patterns of genes that are known to play role cellular and oxidative stress responses. Corals also experienced changes in gene expression of genes that are not already known to play roles in oxidative stress in corals. Our data suggest that these genes may either play roles directly in mediating a stress response, or may be genes acting downstream of the stress response. These include an ETS domain-containing transcription factor related to the ETS1 family of transcription factors, known in mammals to mediate development, disease, and stress response, and two genes that are associated with biomineralization: galaxin, a protein from the organic matrix of the coral skeleton, and a coral-specific gene SCRIP2.
11586629
Influence of metal exposure history on trace metal uptake and accumulation by marine invertebrates.
This paper reviews recent studies on the influence of trace metal exposure history on subsequent metal uptake in marine invertebrates, particularly bivalves and barnacles. Trace metal exposure may induce specific metal-binding ligands. Metallothionein-like proteins appear to play an important role in mediating metal uptake and hence accumulation, especially for Cd. Other ligands such as sulfide are important for Ag biokinetic changes in bivalves. The incorporation of trace metals into metal-rich granules appears to have little if any effect in modifying trace metal uptake. Furthermore, metals also interact strongly in their accumulation by marine animals. Generally, dissolved Hg uptake is reduced following exposure to other metals such as Ag, Cd, Cu, and Zn. Preexposure of marine mussels to Zn also causes concomitant changes in the uptake of other metals such as Cd sharing similar transport pathways. In general, barnacles are less responsive than mussels to trace metal exposure, presumably because of the dominance of detoxificatory pathways in which the accumulated metals are bound in granules (relatively biologically inactive pools). The tissue body burden and the detoxificatory fate of metals in animals seem to be more important in affecting metal accumulation than the nature of the exposure routes (aqueous vs. dietary) or of the exposure regimes. Trace metal accumulation may also be variable in different natural populations of bivalves as a result of different physicochemical environments and histories of exposure. We finally suggest a few areas for future research in this field.
13827043
A COMPARISON OF TWO METHODS FOR DETERMINING COPPER PARTITIONING IN OXIDIZED SEDIMENTS
Abstract Model estimations of the proportion of Cu in oxidized sediments associated with extractable organic materials show some agreement with the proportion of Cu extracted from those sediments with ammonium hydroxide. Data were from 17 estuaries of widely differing sediment chemistry. The modelling and extraction methods agreed best where concentrations of organic materials were either in very high concentrations, relative to other sediment components, or in very low concentrations. In the range of component concentrations where the model predicted Cu should be distributed among a variety of components, agreement between the methods was poor. Both approaches indicated that Cu was predominantly partitioned to organic materials in some sediments, and predominantly partitioned to other components (most probably iron oxides and manganese oxides) in other sediments, and that these differences were related to the relative abundances of the specific components in the sediment. Although the results of the two methods of estimating Cu partitioning to organics correlated significantly among 24 stations from the 17 estuaries, the variability in the relationship suggested refinement of parameter values and verification of some important assumptions were essential to the further development of a reasonable model.
205636007
Long-term incubation of adult Nereis virens (Annelida: Polychaeta) in copper-spiked sediment: the effects on adult mortality, gametogenesis, spawning and embryo development.
Late gametogenic Nereis virens were incubated for up to 2.5 months in environmentally relevant concentrations of copper-spiked sediment. Sequential extraction confirmed that much more labile copper (in actual and percentage terms) was present as spiked concentrations increased, although the residual fractions contained similar amounts across concentrations. This is also reflected in the tissue concentration of the worms which increased in line with the sediment concentrations. Adult mortality was not dependent on the exposure time, but higher concentrations usually induced greater mortality for both sexes. Oocytes were significantly smaller at higher concentrations although pairwise comparisons did not show specific differences. Spawning of males occurred a number of days earlier in the higher concentrations. Differences in the number of embryos developing normally after in vitro fertilizations of oocytes fertilized with sperm from exposed males and non-exposed males showed that sperm were more susceptible to toxicity, but oocytes were also affected at the highest concentration. These results show that there are direct and indirect reproductive consequences of parental exposure to copper with implications for recruitment and subsequent colonization of polluted sediments for this ecologically and commercially important species.
97364357
Trace metal speciation in coastal and off-shore sediments from Ross Sea (Antarctica)
Abstract The information on total metal concentration in sediments is not sufficient to assess the metal behaviour in the environment, while speciation studies are more effective in estimating environmental impact of contaminated sediments. Concerning metal distribution in Antarctic marine sediments, several studies reported total or extractable (by means of a unique reagent) content, but only few publications dealt with metal speciation. This work presents the total content and speciation pattern of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in 12 cm sediment cores, sampled both in coastal and off-shore sites of the Ross Sea shelf area, within the framework of the Italian National Antarctic Programme (PNRA). The total content results of metals are comparable with the background values and the speciation highlights good environmental quality of the studied areas. Only Cd and Pb, in fact, are present in significative amount in non residual phases (acid-extractable and reducible, respectively).
86438568
Relationship between the lability of sediment-bound metals (Cd, Cu, Zn) and their bioaccumulation in benthic invertebrates
The present study has investigated metal contamination at nine sites (10 sampling stations) from the English Channel to the Mediterranean Sea, including low level and highly contaminated sediments. Both total and labile concentrations of metals were determined in superficial sediments. The influence of different pHs was tested and metal lability at pHs encountered in the gut of invertebrates (the ragworm Nereis diversicolor, the blue mussel Mytilus edulis, the Japanese oyster Crassostrea gigas) was compared with the distribution of metals in various operationally defined geochemical fractions. Cd showed the highest lability and Cu the lowest, whereas Zn lability was intermediate. Metal concentrations were determined in bivalves at six sites and in worms at three sites. Cd in living organisms and labile Cd in sediments increased in proportion over the gradient of contamination. This relationship did not always hold for Cu and Zn and these exceptions are discussed. Even if sediments are not the only source of metal contamination in marine invertebrates, the procedure proposed here to assess metal bioavailability by remobilising sediment-bound metals at physiological pHs, seems a significant improvement of the existing methodologies of risk assessment.
31075912
Certification of the extractable contents of Cd, Cr, Cu, Ni, Pb and Zn in a freshwater sediment following a collaboratively tested and optimised three-step sequential extraction procedure.
Sequential extraction procedures have been used during the last decades to study and determine trace element mobility in aquatic sediments. However, the results obtained are operationally defined and, therefore, the significance of the analytical results is related to the extraction scheme used. So, there is a need for suitable reference materials for this type of study to enable the validation of the methodologies and to control the quality of the measurements. This paper describes the preparation of a sediment reference material, BCR-701, the homogeneity and stability studies and the analytical work performed for the certification of the extractable contents of some trace elements, following a collaboratively tested and optimised sequential (three-step) extraction procedure. The paper contains all the results and gives the methods used to certify the extractable contents (mass fractions expressed as mg kg-1 on a dry matter basis) of Cd, Cr, Cu, Ni, Pb and Zn in all steps. Moreover, indicative values are given for the aqua regia extractable contents of the six elements in the sediment and the residue obtained after sequential extraction.
24050566
Physico-chemical and biological parameters determine metal bioavailability in soils.
The Netherlands Stimulation program on System-oriented Ecotoxicological Research focused on three study areas, including two floodplains and a peaty grassland. All three areas were polluted with metals, with total soil concentrations often exceeding Dutch Intervention Values. The floodplain areas showed a homogeneous distribution of metal pollution, while pollution in the peaty area was more heterogeneous. This study aimed at establishing possible general trends in metal bioavailability by combining results obtained at the three different study sites. Available metal concentrations, measured as pore water or 0.01 M CaCl2 extractable concentrations in soil, were lowest in the floodplain soils, probably due to the high pH (> 7.0) and high organic matter (8-30%) and clay contents (13-42%). In the peaty soil, having a lower soil pH (4.5-6.5) but higher organic matter contents (38-60%), in some but not all samples Cu concentrations in pore water and Cu and Pb concentrations in 0.01 CaCl2 extracts were higher than in non-polluted reference areas. Plants in the floodplain areas had only low metal concentrations in their leaves, but soil invertebrates and small mammals did contain elevated concentrations in their body. Cd showed high levels in earthworms, snails and small mammals, while also Cu levels were sometimes increased in earthworms, millipedes and small mammals from the floodplain areas. Earthworms from the peaty area contained increased levels of Cu and Pb. These results suggest that metal bioavailability cannot be predicted from available concentrations in pore water or 0.01 M CaCl2 soil extracts, but requires measurement of biota and more insight into the biodynamics of metal uptake.
58945336
Digestion Methods for Total Heavy Metals in Sediments and Soils
The objectives of this study were to analyze the total contents of Cd, Cr, Cu, Ni, Pb, and Zn in the freshwater sediments and the arable and non-arable soils of Taiwan, and to compare the different digestion methods for their determination. Two hundred and thirty-nine freshwater sediments were collected from the Fei-Tsui Reservoir Watershed (FTRW) in northern Taiwan. Forty-two surface (0–15 cm) and subsurface (15–30 cm) soil samples were likewise collected from 21 representative arable soils derived from various parent materials and with varying weathered degrees in different regions of Taiwan. In addition, one hundred and ninety-four non-arable soils were collected from the different forest regions, industrial parks, resident areas, and commercial areas. Several digestion methods including the aquaregia and different combinations of concentrated acids (HClO4, HNO3, H2SO4, or HF) were compared. All samples were digested both by the aqua regia method and the Baker and Amacher method for Cd, Cr, Cu, Ni, Pb, and Zn. The Reisenauer method was used for Cr and the Burau method for Pb further. The results indicate that the best digestion methods to analyze the total contents of heavy metals in the sediments and soils were recommended as follows: the Baker and Amacher method for Cd, Cr,Cu, Ni, and Zn; the Reisenauer method for Cr, but for simplicity the Baker and Amacher method is also recommended as the flexible method for the total analysis of Cr; the aqua regia method for Cu, Ni, and Zn; and the Burau method for Pb.
20774670
Sequential extraction procedure for the speciation of particulate trace metals
An analytical procedure involving sequential chemicai extractions has been developed for the partitioning of particulate trace metals (Cd, Co, Cu, Ni, Pb, Zn, Fe, and Mn) into five fractions: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter, and residual. Experimental results obtained on replicate samples of fluvial bottom sediments demonstrate that the relative standard deviation of the sequential extraction procedure Is generally better than =10%. The accuracy, evaluated by comparing total trace metal concentrations with the sum of the five Individual fractions, proved to be satisfactory. Complementary measurements were performed on the Individual leachates, and on the residual sediments following each extraction, to evaluate the selectivity of the various reagents toward specific geochemical phases. An application of the proposed method to river sediments is described, and the resulting trace metal speciation is discussed.
19174783
Experimental results on bioaccumulation of metals and organic contaminants from marine sediments.
A test-system for the assessment of bioavailability and bioaccumulation of metals and organic contaminants in marine benthic organisms is described and results from studies where this system has been applied are assessed. Sediments tested were polluted harbour sediment (from Norway), and clean sediments spikes with metal containing weight materials for drilling muds. Contaminants that may bioaccumulate under relevant conditions are indicated. The test-system uses two species of ecological relevance (Nereis diversicolor and Hinia reticulata). Interspecies differences in bioaccumulation were found for several compounds, which show the importance of using species with different modes of living in such tests. Compared to other PAHs, pyrene was found to bioaccumulate to a high degree (BioAccumulation Ratio, BAR=213.5>sediment concentration ratio, SCR=97.4; bioaccumulation factor, organism dw. conc. to sediment dw. conc., BAF=1.02), which shows that extrapolating bioaccumulation results between different substances is difficult. When assessing bioavailability of specific compounds, it is most adequate to perform direct measurements on exposed organisms, such as the experiments described here. The high bioaccumulation of compounds such as pyrene and nickel may in some cases be attributed to manipulation of the sediments and (for pyrene) lack of subsequent aging, thereby overestimating bioavailability.
131061079
A simple, inexpensive and large volume pore water sampler for sandy and muddy substrates
Abstract The construction and testing of a low cost, simple, intertidal and sub-tidal pore water sampler for use in sandy and muddy substrates are described in this note. The sampler, “porextractor”, is made of polyvinyl chloride (PVC) plumbing materials that can be readily sourced at any local hardware shop and costs AU $ 15.00 to build. The only mechanical component of the porextractor is a plunger that is used only once at the time of deployment. The porextractor has been designed for use on seagrass beds to collect pore water samples with minimal disturbance to the substratum for nutrient flux studies. The relative efficiency of the porextractor was tested against the widely used “Winger and Lasier” sampler, a vacuum operated diffuser stone pore water sampler. The two samplers were compared for the volume of pore water collected in sandy and muddy substrates in the laboratory, and the concentrations of total nitrogen and total phosphorus in samples collected from a sandy substrate in Amphibolis and Posidonia seagrass meadows off the Adelaide coast. While the porextractor and the Winger and Lasier samplers worked equally well in the sandy sediments, the porextractor was more efficient than the latter in muddy sediments, where clogging was a major problem. In addition, there were no significant differences (p ≤ 0.05) in the concentrations of total nitrogen and total phosphorus measured from the pore water samples collected by the two samplers in situ from the seagrass bed. The simplicity, ease of construction, non-substrate specificity, and large sample volume yield are some of the major merits of the porextractor over other conventional techniques used for pore water sampling.
24233815
Expanding the ecotoxicological toolbox: the inclusion of polychaete reproductive endpoints.
In the last 15 years the diversity of pollutants and routes of impact have increased. However, the polychaete families, species and endpoints investigated have remained fairly constant. Reproductive outputs are more ecologically relevant than adult physiological or biochemical changes. Nevertheless, there remains a paucity of data on the reproductive responses of the popular species to pollutants which limits our ability to understand the true ecological impacts of such contaminants on natural populations. We highlight the current knowledge gaps in our understanding of the impacts of pollutants on the 'model' species' reproductive biology and therefore the potential ecological impacts of such contaminants on their natural populations, and the potential benefits of a wider use of polychaete reproductive endpoints for ecotoxicological assessments. The following priority areas are suggested for inclusion in the polychaete ecotoxicology toolbox: 1. Include reproductive endpoints as assessments of ecotoxicology for the traditional 'model' species and those that have different reproductive traits to ensure broad ecological relevance. 2. Nereids and Arenicola marina should be used to investigate the interaction of pollutants with the endocrine/environmental control of reproduction. 3. Polychaetes are ideal for addressing the under representation of male eco-toxicity effects. 4. Emerging pollutants should be assessed with reproductive endpoints together with the traditional biomarkers. 5. Effects of pollutants on larval behaviour need to be explored considering the limited but equivocal results so far.
32382699
Feeding, growth and respiration in the polychaetes Nereis diversicolor (facultative filter-feeder) and N. virens (omnivorous)-a comparative study
The polychaetes Nereis divers~color and N. virens were fed various amounts of shrimp meat in laboratory experiments and h e a r relationships between specific growth rate and specific respiration rates were found. From this relation the energy cost of growth ('specif~c dynamic action', SDA) was found to be 20 to 26% of the growth. The starvation respiration rate (maintenance) (R,,, p1 O2 h' ind.-') as a function of body mass (W, g dry wt) was: R, = 1306 W' and R, = 704 W' O for N. diversicolor and N. virens, respectively. For worms fed shrimp meat the maximum specific growth rate was 7 % d-l in N, diversicolor and 5.9% d-' in N. virens. In filter-feeding N. diversicolor fed algal cells (6.2 pm &ameter Rhodomonas sp.) there was a strong correlation between ingestion rate and growth rate, the maximum specific growth rate being 3 O/o d.' No functional response was seen even at the highest algal concentration of 2 X 104 cells ml-l. It is possible that filter-feeding In N. diversicoloris a relatively recent adaptation which has resulted in a broader fundamental n~che compared to that of the closely related N. virens. This filter-feeding adaptation may possibly explain the coexistence of the 2 polychaetes in certain braclush water areas.
51783018
Differences in trace metal bioaccumulation kinetics among populations of the polychaete Nereis diversicolor from metal-contaminated estuaries
Aquatic organisms exposed to atypically high local bioavailabilities of a toxic metal may come under selection for changes in one or more physiological processes, including the rate of metal uptake from an available source of the metal, the rate of efflux and the rate of detoxification of accumulated metal into a relatively metabolically inert form. We investigated parameters of the bioaccumulation kinetics of the toxic metals Ag, Cd and Zn in populations of the estuarine polychaete worm Nereis diversicolor from differentially metal-contaminated sediments of 5 metal-rich estuaries in SW England and a relatively non-contaminated control estuary in SE England. One population (from Restronguet Creek, Cornwall) is known to be tolerant to raised availabilities of Zn and Cu. We compared uptake rate constants from solution (Ku) and assimilation efficiencies (AE) from sediment, and subsequent efflux rate constants (Ke) after uptake (from either water or ingested sediment) for each of the 3 metals among all populations. There was some limited interpopulation variation in the biodynamic parameters controlling bioaccumulation (and potential ecotoxicity) of trace metals between populations. There did not, however, appear to be consistent patterns to such variation. The basis of Zn tolerance in the Restronguet Creek population is not due to a reduction of Zn uptake from either solution or ingested sediment, or increased efflux of Zn accumulated after uptake from either route. The most likely mechanism is, therefore, an increased capacity for storage detoxification of Zn accumulated after regulation of Zn body concentration has broken down.
84625523
Effects of bait collection on Nereis virens populations and macrofaunal communities in the Solent, UK
The Solent European Marine Sites contain many tiers of habitat and species conservation, but also high levels of bait collection. Effective management strategies must be founded on up-to-date and locally based information from relevant studies of the impacts; these have been lacking for the collection of Nereis virens, a key bait species. The impacts on macrofauna were assessed through two approaches; (a) undug and dug sites in the Solent were compared over two years of repeat sampling; and (b) monitoring the long-term effects of simulated bait collection at an undug site through five years of yearly sampling. Dug sites had significantly higher densities of N. virens, but the mean weight was found to be significantly lower than those collected from the undug sites, but percentage maturity was not different. Organic content and sediment particle sizes differed between sites, and only the presence of gravel had a significant positive correlation with density. No clear patterns of other macrofauna species present were evident, although there was a significantly lower density of the terebellid polychaete Neoamphitrite figulus at the dug sites. Simulated bait collection did not alter overall macrofauna diversity, but certain species were affected. Abundance of N. figulus and the commensal Harmothoë glabra remained consistently lower in the dug area, whilst Cerastoderma edule numbers were reduced initially, but recovered. Numbers of Nephtys hombergii declined in both areas, but at a significantly greater rate in the dug area. A general decline in the abundance of many species, irrespective of digging, occurred over the period. The importance of these changes in Nereis virens populations and in the macrofauna community needs to be investigated prior to any management decisions on collection.
53501251
Macrofaunal Burrows and Irrigation in Marine Sediment: Microbiological and Biogeochemical Interactions
Construction and maintenance of burrows by macrofauna have large implications for the microbiology and biogeochemistry of marine sediments. Although a wealth of new information has become available during the last few decades, there are still significant gaps in our knowledge. In this chapter, we review the current understanding of how the structure and function of irrigated burrows affect the composition of microbial communities and associated biogeochemical processes. Although a general relationship is observed between burrow depth and diameter (inhabitant width), it is difficult to classify burrow architecture in relation to the function and trophic mode of macrofaunal inhabitants. Trophic mode (suspension-feeding versus deposit-feeding) appears to control burrow wall structure and irrigation rate and thus the exchange of solutes between sediment porewaters and the overlying water. The associated translocation of electron acceptors into and inhibitory metabolites out of the sediment in turn affects diagenetic reactions. It is well established that irrigated burrows enhance total microbial metabolism by stimulating oxic (e.g. respiration) and suboxic (e.g. nitrification–denitrification and iron reduction) reactions in the surrounding sediment. In contrast, the impacts of burrowgenerated changes to diffusion scales on anoxic processes like sulfate reduction are less clear. Sediments surrounding burrow structures likely support unique microbial communities that differ from those in surficial sediments due to large differences in environmental conditions. Biogeochemical evidence clearly indicates that the activity and abundance of microorganisms are elevated around burrows. However, the mechanisms controlling microbially mediated geochemical reactions in the burrow zone remain understudied, and very little information is available to assess the impacts of burrow environments on the community structure or diversity of microorganisms. Therefore, we cannot yet generalize about direct relationships between burrows, irrigation and the distribution of microorganisms. However, much progress is already being made through the use of new and exciting experimental tools, such as microsensors and cultivation-independent molecular techniques. 1 The Ecogeomorphology of Tidal Marshes Coastal and Estuarine Studies 59 Copyright 2004 by the American Geophysical Union 10.1029/59CE04 Q1 9738.qxd 3/26/05 1:38 PM Page 1
53637951
Trophic transfer of trace metals from the polychaete worm Nereis diversicolor to the polychaete N. virens and the decapod crustacean Palaemonetes varians
Diet is an important exposure route for the uptake of trace metals by aquatic inverte- brates, with trace metal trophic transfer depending on 2 stages—assimilation and subsequent accu- mulation by the predator. This study investigated the trophic transfer of trace metals from the sedi- ment-dwelling polychaete worm Nereis diversicolor from metal-rich estuarine sediments in southwestern UK to 2 predators—another polychaete N. virens (Cu, Zn, Pb, Cd, Fe) and the decapod crustacean Palaemonetes varians (Cu, Zn, Pb, Cd, Fe, Ag, As, Mn). N. virens showed net accumula- tion of Cu, Zn, Pb and Cd from the prey; accumulation increased with increasing prey concentration, but a coefficient of trophic transfer decreased with increasing prey concentration, probably because a higher proportion of accumulated metal in the prey is bound in less trophically available (insoluble) detoxified forms. The trace metal accumulation patterns of P. varians apparently restricted significant net accumulation of metals from the diet of N. diversicolor to just Cd. There was significant mortality of the decapods fed on the diets of metal-rich worms. Metal-rich invertebrates that have accumulated metals from the rich historical store in the sediments of particular SW England estuaries can poten- tially pass these metals along food chains, with accumulation and total food chain transfer depending on the metal assimilation efficiencies and accumulation patterns of the animal at each trophic level. This trophic transfer may be significant enough to have ecotoxicological effects.
35264714
Chemical sequential extraction for metal partitioning in environmental solid samples.
A comprehensive review of the sequential extraction schemes for metal fractionation in environmental samples (ie., sediment, soil, sewage sludge, fly ash, etc.) is presented. The review contains more than 400 references and covers principally the literature published over the last decade. The use of each reagent involved in these schemes is looked at critically, and guidelines for their selectivity and extraction capacity are given. The operational character of these schemes is emphasised. Topics such as comparability between sequential extraction schemes of widespread use, harmonisation, acceleration, validation, etc. are addressed and future developments outlined.
96643071
Comparison of original and modified BCR sequential extraction procedures for the fractionation of copper, iron, lead, manganese and zinc in soils and sediments
This article describes a detailed comparison between the original BCR sequential extraction procedure, step 2 of which involves treatment with 0.1 mol l(-1) hydroxylammonium chloride at pH 2, and the revised BCR procedure (step 2: 0.5 mol l(-1) hydroxylammonium chloride at pH 1.5). An intermediate protocol was also evaluated in which 0.5 mol l(-1) hydroxylammonium chloride at pH 2 was used. The procedures were applied to five soil and sediment substrates: a sewage sludge-amended soil, two different industrially contaminated soils, a river sediment and an inter-tidal sediment. Extractable iron and manganese concentrations were measured to assess the effects of the procedural modifications on dissolution of the reducible matrix components. Trace elements copper, lead and zinc were also determined. Statistical analysis (two-tailed t-tests at 95% confidence interval) indicated that recovery of iron in step 2 was not markedly enhanced when the intermediate protocol was used. However, significantly greater amounts were isolated with the revised BCR scheme than with the original procedure. Copper behaved similarly to iron. Lead recoveries were increased by use of both modified protocols, with the greatest effect occurring for the revised BCR extraction. In contrast, manganese and zinc extraction did not vary markedly between procedures. The work indicates that the revised BCR sequential extraction provides better attack on the iron-based components of the reducible matrix for a wide range of soils and sediments. (C) 2002 Elsevier Science B.V. All rights reserved.
97215686
Sedimentation pattern and sediments bioavailability in a wastewater discharging area by sequential metal analysis
Abstract Atomic absorption spectrometry was applied to investigate sedimentation pattern and sediments bioavailable phase (BAP) at 41 sites of a wastewater discharging area. The position of sampling sites was confirmed by the aid of a global positioning system (GPS). Contaminants discharged from a large wastewater plant are dispersed to the inner bay and the coastal line rather than the outer bay and the center waterway. The fractional composition of sediment Zn in the discharging area accounted for the presence of exchangeable 239 mg/kg (35.1%)>reducible 163 mg/kg (24.0%)>carbonate 149 mg/kg (22.0%)>residual 98 mg/kg (14.4%)>organic 31 mg/kg (4.6%) in sediment layers of 0–2 cm. However, the order was changed in layers of 15–20 cm as residual>reducible>organic>carbonate>exchangeable. The most abundant fraction of sediment Cu and Fe was organic Cu and residual Fe, respectively. The content of BAP in sediments are quite different with respect to metal species and sediment layer analyzed. It is obvious that sequential metal analysis is a useful tool in understanding dispersion of sediments and sedimentation patterns.
19371965
Sequential Extraction of Copper, Lead, Cadmium, and Zinc in Sediments from Ebro River (Spain): Relationship with Levels Detected in Earthworms
Financial support was obtained from the National Plan for Research (grant AMB95-0138-CO2-01).
12378115
Heavy Metal and Trace Metal Analysis in Soil by Sequential Extraction: A Review of Procedures
Quantification of heavy and trace metal contamination in soil can be arduous, requiring the use of lengthy and intricate extraction procedures which may or may not give reliable results. Of the many procedures in publication, some are designed to operate within specific parameters while others are designed for more broad application. Most procedures have been modified since their inception which creates ambiguity as to which procedure is most acceptable in a given situation. For this study, the Tessier, Community Bureau of Reference (BCR), Short, Galán, and Geological Society of Canada (GCS) procedures were examined to clarify benefits and limitations of each. Modifications of the Tessier, BCR, and GCS procedures were also examined. The efficacy of these procedures is addressed by looking at the soils used in each procedure, the limitations, applications, and future of sequential extraction.
20524083
BCR®-701: a review of 10-years of sequential extraction analyses.
A detailed quantitative analysis was performed on data presented in the literature that focused on the sequential extraction of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) from the certified reference material BCR-701 (lake sediment) using the three-step harmonized BCR(®) procedure. The accuracy of data reported in the literature, including precision and different measures of trueness, was assessed relative to the certified values for BCR-701. Forty data sets were accepted following extreme outlier removal, and statistically summarized with measures of central tendency, dispersion, and distribution form. In general, literature data were similar in their measurement precision to the expert laboratories used to certify the trace element contents in BCR-701. The overall median precision for literature reported data was 10% (range 6-19%), compared to certifying laboratories of 9% (range 4-33%). One measure of literature data trueness was assessed via a confirmatory approach using a robust bootstrap method. Only 22% of the comparisons indicated significantly different (all were lower) concentrations reported in the literature compared to certified values. The question of whether the differences are practically significant for environmental studies is raised. Bias was computed as a measure of trueness, and literature data were more frequently negatively biased, indicating lower concentrations reported in the literature for the six trace elements for the three-step sequential procedure compared to the certified values. However, 95% confidence intervals about the average bias for the 18 comparisons indicated only four instances when a mean bias of 0 (i.e., measured=certified) was not incorporated-suggesting statistical difference. Finally, Z-scores incorporating a Horwitz-type function were used to assess the general trueness of laboratory data. Of the 468 laboratory Z-score values computed, 92% were considered to be satisfactory, 5% were questionable, and 3% were unsatisfactory. A detailed examination of the methodology sections of the various studies showed that despite claiming adherence to the harmonized BCR sequential extraction protocol, significant deviations were commonly observed; particularly in moisture correction, sample mass, centrifugation specifics, shaking specifics, and incorporation of filtration. It is likely that failure to strictly adhere to the protocol adversely impacted accuracy, by increasing the degree of imprecision and resulting in more discrepant trueness values.
206933119
Porewater evidence of metal (Cu, Ni, Co, Zn, Cd) mobilization in an acidic, ombrotrophic bog impacted by a smelter, Harjavalta, Finland and comparison with reference sites.
Porewaters were collected from three Finnish peat bogs subjected to varying inputs of atmospheric trace metals: Hietajärvi (HIJ), a low-background site, Outokumpu (OUT), near a Cu-Ni mine, and Harjavalta (HAR), near a Cu-Ni smelter. Samples for metal analyses were collected at depths ranging from 10 to 70 cm using a purpose-built syringe-type sampler. Metal concentrations were determined using inductively coupled plasma-sector field-mass spectrometry (ICP-SF-MS). Porewater concentrations at HIJ and OUT (Cd <0.3 nM, Co <1.4 nM, Cu, Ni <8 nM, Zn <250 nM) are independent of metal concentrations in the solid phase (peat). At OUT there is a limited release of Ni to the porewaters, but concentrations in the aqueous phase are generally below 0.3% of the total concentration in any given peat sample. These data are consistent with the immobility of these metals after deposition from the air. In contrast, porewaters at HAR are enriched in trace metals compared to the other sites by a factor of 2 (Zn), 10 (Cd), 20 (Co), and 100 (Cu and Ni) with dissolved fractions of Cu and Ni accounting for ca. 20% of the metal inventories in the cores. The elevated release of metals from solid phases at HAR is consistent with the postdepositional migration of metals at this site and reflects the predominance of oxide phases supplied to the bog surface and the much lower pH values (<3.4). The elevated proton concentrations not only promote mineral dissolution but also compete with cation exchange processes and hinder the formation of metal complexes with organic ligands.
46585536

Accumulation and Soluble Binding of Cadmium, Copper, and Zinc in the Polychaete Hediste diversicolor from Coastal Sites with Different Trace Metal Bioavailabilities
Bioaccumulation of cadmium, copper, and zinc was examined in common ragworms Hediste diversicolor from control (Bay of Somme, Blackwater) and metal-rich (Seine estuary, Boulogne harbor, Restronguet Creek) sites in France and the United Kingdom. The degree of exposure in the field was assessed by considering both total concentrations in superficial sediment and the quantities of metals which may be released in vitro at different pH levels. Among the three contaminated sites, release of the three metals was not detectable in Boulogne harbor, in correlation with limited enhancement of the metal concentrations in the common ragworms from this site. Even at those sites where zinc could be released in vitro from the sediment, zinc concentrations were not enhanced in common ragworms, in agreement with previous findings indicating that the body content of this metal is regulated in H. diversicolor. At all the studied sites, bioaccumulated zinc was mainly in cytosolic form. The distribution of cadmium and copper varied according to the origin of the common ragworms, the insoluble fraction increasing with the degree of contamination (cadmium in the Restronguet Creek, copper in the Seine estuary, and even more in Restronguet Creek). In the cytosolic fraction, metals were partly linked to cytosolic heat-stable thiolic compounds (CHSTC) with molecular masses (5–6 kDa and about 12 kDa) consistent with metallothionein-like proteins (MTLP). Metal-binding to MTLP varied with the degree of contamination and with the metal studied. In contrast to many invertebrates, the presence of metal-binding CHSTC (MM about 2 kDa) other than MTLP seems to be a peculiar feature of H. diversicolor.
85057248
The effect of size, weight, body compartment, sex and reproductive status on the bioaccumulation of 19 trace elements in rope-grown Mytilus galloprovincialis
Abstract Numerous trace elements (TEs) can be considered as potential pollutants of the environment, their mining productions and industrial uses increasing worldwide. Their monitoring can be achieved through the use of bioindicator species, such as the Mediterranean mussel Mytilus galloprovincialis (Lamarck, 1819). That species has been widely used to monitor the chemical pollution of coastal ecosystems by Cr, Ni, Cu, Zn, Cd, Pb, As, Ag and V. Conversely, environmental levels of Be, Al, Fe, Mn, Co, Se, Mo, Sn, Sb and Bi have been little or not monitored so far in mussel watch programs. Bioaccumulation processes of these 19 TEs in rope-grown M. galloprovincialis purchased from a salt pond with good chemical water quality were thus investigated in the present study. Mussels efficiently accumulated the 19 studied TEs. Bioaccumulation processes were driven by numerous mutually dependent biological parameters such as the mussel size and flesh weight, the sex and the reproductive status and the body compartment considered. TE bioaccumulation was a power function of the mussel soft body dry weight; total contents linearly increased with the shell length. Small-size mussels overall concentrated more TEs, with a high inter-individual variability, consequently influencing the modelling of their bioaccumulation in the whole rope population. Although a large range of rope-grown M. galloprovincialis sizes can be used for monitoring purposes, one will thus take care not to use extreme size individuals. The influence of gametogenesis in determining female body higher TE concentrations prior to spawning could not be neglected and varied depending on the element. TEs were preferentially accumulated in the hepatopancreas, except for Zn, Se, Cd and Mo, more concentrated in gills. Gametogenesis did not influence TE distribution between body compartments, but likely diluted their concentrations as a direct consequence of massive reproductive tissue production. So, results from the present study underline the potential use of M. galloprovincialis in the biomonitoring of numerous little studied TEs and give some insights into the decisive role played by some relevant biological parameters in bioaccumulation processes of the 19 investigated TEs in rope-grown mussels.
86251475
Use of semi-quantitative kit methods to study the heterotrophic bacterial community of Posidonia oceanica meadows: Limits and possible applications
Rapid, easy and low cost semi-quantitative methods were tested to study the heterotrophic bacterial community of Posidonia oceanica meadows and were compared to techniques commonly used in microbial ecology. Free and pore-water bacterial densities were estimated by luminescence, and principal enzymatic activities, metabolic capabilities and benthic mineralisation processes were studied with microtitration methods: ApiZym galleries, Biolog microplates and BART™ tests. Bacterial densities varied little throughout the year and were around 5.0·105 and 6.0·106 cells ml−1 of free and pore-water, respectively. The combined use of the ApiZym gallery and the Biolog microtitration plate permitted highlighting bacterial enzymatic activities susceptible to degrade principal organic polymers present in the Posidonia meadow, and to correlate these enzymatic activities to the subsequent potential utilization of resulting monomeric products. Levels of enzymatic activities (1.80–8.36 nmolessubstrates h−1 ml−1) and energetic bacterial metabolism (1.80–6.42 nmolessubstrates h−1 ml−1) presented seasonality relying on the temperature regime and on the primary production (Posidonia and phytoplankton). Main mineralization processes of buried organic matter through sulfate and iron reduction activities were successfully detected. Despite the complexity of the studied ecosystem, results obtained by this semi-quantitative approach, compared to studies applying commonly used methods in microbial ecology, highlighted the same bacterial dominant key processes. Their low cost, rapid and easy use, and the low level of expertise and sophistication they require means that these techniques are of use to many employed in environmental surveys.
97017153
Effect of sedimentary organic matter composition on the partitioning and bioavailability of dieldrin to the oligochaete Lumbriculus variegatus
Current hypotheses link the bioavailability of contaminants in sediments to their partitioning behavior to organic matter in sediments. Because contaminant partitioning varies with sediment composition, it follows that composition should also affect contaminant bioavailability. In this study, variations in dieldrin partitioning and bioavailability, as measured by organic carbon/lipid-normalized bioac cumulation factors for Lumbriculus variegatus, were related to sediment composition. Study sediments covered a wide range of composition and organic matter content. Normalizing the bioaccumulation factors to the organic carbon content of sediments and lipid content of organisms reduced ranges of measured dieldrin accumulation factors from 38-fold to 8-fold. Factors describing sediment composition were tested to determine whether they explained the remaining variability between sediments. Variations in partitioning were best explained by the proportion of sedimentary organic matter that was solvent extractable...
23646020
Correlations of extractable heavy metals with organic matters in contaminated river sediments.
In southern Taiwan, almost all the main rivers have been contaminated by anthropogenic heavy metals and organic matters. The main pollution sources include agricultural, industrial, and domestic activities. River sediments potentially have large capacities to accumulate heavy metals and organic matters when the river water flows through it. The sediments sampled from high contaminated river (the Yenshui River) and moderately contaminated rivers (the Tsengwen, Chishui, Potzu, and Peikang Rivers) were used to realize correlations between each kind of aqua regia extractable heavy metals (Co, Cr, Cu, Zn, Ni, Pb, Mn, and Fe) and organic matters in vertical sediment cores. Organic matters and aqua regia extractable heavy metal concentrations, analyzed by strong acid-digested extraction, were determined in vertical profile segments from downstream sediments of the five rivers. Sum of six aqua regia extractable heavy metals (Co, Cr, Cu, Zn, Ni, and Pb) were below 3,000 mg/kg in sediments of the Yenshui River, and below 500 mg/kg in the other four rivers' sediments. Strongly positive correlations (r = 0.83-0.95) between each kind of aqua regia extractable heavy metals and organic matters (concentration range between 0.6 to 3.8%) were observed in sediments of the Yenshui River. The slopes of the linear regressive lines approximated the average metal complexation ratios with organic matters in the sediments. In sediments of the other four rivers, smaller positive correlation coefficients between aqua regia extractable heavy metals and organic matters (below 2.6%) were observed. The complexation ratios derived from the four moderately polluted river sediments were smaller than those derived from the highly contaminated river sediments, indicating that the importance of organic matters in the accumulation of heavy metals in river sediments.
85263838
Sources and Potential Effects of Copper and Zinc Concentrations in the Estuarine Waters of Essex and Suffolk, United Kingdom
Abstract This paper evaluates the possible biological significance of routine monitoring data for dissolved copper and zinc collected from nine lightly industrialized Essex and Suffolk estuaries by the Environment Agency during the years 1992–96, and investigates the relative importance of the various sources. The annual average concentration data from several locations in each estuary are compared with the proposed revised UK annual average Environmental Quality Standards (EQSs) for dissolved copper (5 μ g l−1) and zinc (10 μ g l−1) in seawater. In summary, 21.7% of sampling-location/year combinations exceeded the revised EQS for copper, and 53.6% exceeded the revised EQS for zinc, and one or more locations on each estuary failed each EQS for at least one year in the five-year period. In some of the nine estuaries, riverine and treated sewage discharges contribute a significant proportion of the total copper and zinc input, but the single largest source of both metals is almost certainly boating traffic employing copper-based antifouling paints and zinc-based sacrificial anodes. The data suggest that both metals may be causing ecological damage, but this cannot be firmly concluded because an unknown proportion of each was probably complexed with dissolved organic matter, and therefore less bioavailable. This question can only be addressed by field studies of the biological status of indicator species in these waters.
96094763
Pore water sampling with sediment peepers
Abstract The use of in situ equilibrium dialysis samplers (peepers) for the collection of sediment pore waters for trace metal analysis is reviewed. Optimum peeper designs, construction and preparation procedures are described. Field deployment and sampling protocols are outlined with their utility illustrated by dissolved metal profiles obtained from field studies.
84506645
An Assessment of the Contamination and Toxicity of Marine Sediments in the Holy Loch, Scotland
Abstract Following the closure of the United States Navy Submarine Base in 1992, video surveys revealed that a considerable amount of debris, largely scrap metal, was present on the bed of the Holy Loch. A working group was set up to examine ways of `cleaning-up' the loch. Consultants were employed by the UK Ministry of Defence to carry out an environmental survey of the Holy Loch, including an assessment of the consequences of lifting the debris from the loch bed. This survey revealed that a number of contaminants were present at high concentrations in the bed sediments. These contaminants included persistent, toxic and bioaccumulable substances such as trace organic contaminants and trace metals. Concern was expressed that the debris removal operation may lead to the release of sediment-bound contaminants, which may in turn exert toxic effects on local flora and fauna. Consequently, the Scottish Environment Protection Agency carried out a survey to verify the levels of persistent organic contaminants and trace metals in the sediments, to set these in context on a UK scale, and to assess the toxicity of sediment/water mixtures. Contamination of Holy Loch sediments by polychlorinated biphenyls (PCBs) and by trace metals, especially copper and zinc, was confirmed as severe but localized. Sediment bioassays indicated that acute water column toxicity was unlikely to arise from the release of sediment-bound contaminants during the debris removal operation. Contaminant levels in mussels collected before and after the initial phase of the debris removal operation showed little change, suggesting no impact on local flora and fauna.
84227291
Methods for assessing the toxicological significance of metals in aquatic ecosystems: bio-accumulation–toxicity relationships, water concentrations and sediment spiking approaches☆
Abstract Although the published literature abounds with studies showing contamination of aquatic environments by metals, there are very few data which actually demonstrate the biological impact of this contamination. Biological impacts such as alteration of in situ communities and demonstration of toxicity in environmental samples often occur at sites with elevated metal concentrations, but this does not prove that metals are actually responsible for these effects. Correlation is not proof of cause and effect. Metal-induced biological effects cannot usually be inferred from measured environmental concentrations because metal bio-availability can vary dramatically from site to site. Differences in metal bio-availability lead to differences in metal bio-accumulation, which in turn lead to differences in metal-induced effects. On the other hand, metal concentrations in biota are often much better indicators of potential biological impact than concentrations in the environment, because differences in metal bi...
128484326
Pitfalls of sequential extractions
Abstract An increasing number of researchers are using sequential extractions to determine the speciation of trace elements in sediments. Unfortunately, sequential extraction methods have not been successfully validated. The results are simply taken as providing “operational definitions” of the phases one is trying to measure. A more rigorous approach is required to gain insight into the geochemistry of trace elements or their bioavailability.
45096849
Influence of acid volatile sulfides and simultaneously extracted metals on the bioavailability and toxicity of a mixture of sediment-associated Cd, Ni, and Zn to polychaetes Neanthes arenaceodentata.
Laboratory microcosm experiments were conducted to investigate the influence of acid volatile sulfides (AVS) and simultaneously extracted metals (SEM) in sediments on the bioavailability and toxicity of Cd, Ni, and Zn in sediments to polychaete worms Neanthes arenaceodentata. Cohorts of juvenile N. arenaceodentata were exposed to sediments spiked with metal mixtures containing Cd, Ni, and Zn (0.5-15 micromol x g(-1) of total SEM) with Low- (approximately 1 micromol x g(-1)), Medium- (approximately 5 micromol x g(-1)), and High-AVS concentrations (approximately 10 micromol x g(-1)) for 20 days to determine mortality, growth rate, and metal bioaccumulation. Tissue Cd and Zn concentrations at the end of the exposure were significantly higher in sediments with the low-AVS concentration at a given SEM concentration due to the increased dissolved metal concentrations in overlying water (OW). However, tissue Ni concentrations were not related to dissolved Ni in the OW. AVS concentrations also influenced the toxicity of metals to the worms. Significant mortality was observed only at the highest SEM treatments at Low-AVS series. Most individuals survived at the highest SEM treatments at Medium- and High-AVS series. Similarly, the growth rates of worms were reduced in treatments having higher molar differences between SEM and AVS ([SEM-AVS]). Overall, the bioavailability and toxicity of metals in sediments was not well predicted by sediment metal concentrations only, but considering the influence of geochemical factors (AVS) on the metal bioavailability improved the prediction of toxicity. Also, the relationship between tissue metal concentration and toxicity was used to determine which contaminant was most responsible for the observed toxicity of the metal mixture.
16100005
Complexity of spatial and temporal trends in metal concentrations in macroinvertebrate biomonitor species in the Severn Estuary and Bristol Channel
Cadmium, chromium, copper, nickel, lead and zinc concentrations in the bivalve mollusc Macoma balthica and the polychaete annelids Hediste diversicolor and Arenicola marina were measured, during winter and summer, at sites throughout the Severn Estuary and Bristol Channel. The mean concentration of each metal in A. marina was greater in the lower Severn Estuary than in the far less contaminated outer Bristol Channel and the concentration of a given metal, e.g. Cr, in a species occasionally peaked at a site, reflecting local metal contamination. The concentrations of each metal in each of these biomonitor species almost invariably differed significantly among sites and often seasons and there were sometimes interactions between site and season. This indicates that the various factors that determine the concentration of a metal in a species operate in a complex manner and that their individual effects can vary among sites and/or seasons. The rank order of each metal concentration in each species at a site within the estuary frequently did not match the sequence for the concentration of that metal measured in the sediment at that site at the same time. This lack of correspondence is likely to be due, at least in part, to one or both of the following: (1) variations in the bioavailability of certain metals among sites due to differences in such features as the metal-binding properties of the sediments; (2) the effects of the constant transport and redistribution of the sediments and thus also of their associated trace metals by the very strong tidal action that characterizes the Severn Estuary. This would mean that single time measurements do not accurately reflect the overall trace metal environment to which the biomonitor organism had been exposed in the weeks/months prior to sampling. Marked differences in the concentrations of certain metals, e.g. Cu and Zn, in co-occurring biomarker species could frequently be related to differences between the ability of these species to regulate certain metals. Non-metric multi-dimensional scaling ordination and associated tests emphasize that the relationships between the concentrations of the various metals differed markedly among species and between sites and seasons in individual species and elucidated which metals contributed most to those differences. If the proposed scheme for harnessing tidal power in the Severn Estuary proceeds, the data in this paper provide a baseline for assessing the impact of such major changes on the bioavailability of trace metals in this estuary. This information will also be invaluable for predicting the changes likely to occur in other estuaries that become subjected to major structural changes.
85651961
Adaptation of the polychaete Nereis diversicolor to estuarine sediments containing high concentrations of heavy metals. I. General observations and adaptation to copper
The concentration of copper in Nereis diversicolor O. F. Miiller is roughly related to the total concentration in the sediment and particularly high concentrations are found where mining pollution occurs. In contrast, the concentration ofzinc in Nereis remains remarkably constant despite wide variations in the environment and appears to be accurately regulated.
83716164
Kinetics of trace metal accumulation and excretion in the polychaete Nereis diversicolor
The comparative kinetics of the accumulation of the trace metals copper, zinc and cadmium have been measured in the estuarine burrowing polychaete worm Nereis (Hediste) diversicolor from two sites: (a) a metal-rich site, Restronguet Creek, Cornwall, UK, which hosts a copper- and zinc-tolerant population of worms, and (b) the Blackwater estuary, Essex, UK as a control site. A sediment transfer experiment showed that the Blackwater worms responded to the increased copper bioavailability in Restronguet Creek sediment by accumulating significantly increasing copper concentrations over 50 days. The Restronguet Creek worms showed no significant change in copper concentration over 50 days in sediment from either site or in sand. Nevertheless, electron microscopy showed that some Restronguet Creek worms do appear to excrete accumulated copper, probably in association with renewal of the cuticle over a long time scale. The Blackwater worms did not accumulate extra zinc from the zinc-rich Restronguet Creek sediment, in probable reflection of the regulation of body zinc concentration by N. diversicolor. Radiolabelled zinc and cadmium were accumulated from labelled sediment and labelled solution by worms from both sites. The rate of uptake of labelled zinc from sediment was significantly greater in the Restronguet Creek worms, as was the rate of uptake of labelled cadmium from 10 μg l−1 dissolved exposure; other rates of uptake did not differ between populations. Mucus, which is secreted by Restronguet Creek worms in response to enhanced copper exposure, adsorbed very small proportions of zinc and cadmium present in solution, indicating that the mucus does not act as an adsorption barrier against excessive metal uptake by these worms.
96838711
Bioaccumulation of Heavy Metals in Thionic Fluvisols by a Marine Polychaete: The Role of Metal Sulfides
Bioavailable heavy metals have been widely studied in recent years because of their toxicity to natural ecosystems. Despite the number of studies carried out, relatively little is known about the metal fraction that is biologically available. In this study, we analyzed seasonal concentrations of acid-volatile sulfide (AVS) as well as heavy metals associated with the reactive (soluble in 1 M HCI) and pyrite (soluble in HNO 3 ) fractions of the soils of three salt marshes in the ria of Ortigueira (NW Iberian Peninsula). Heavy metal concentrations in polychaete worms (Nereis diversicolor) collected from each salt marsh were also determined and compared with metal contents in the different fractions of the soil. We did not find a relationship between the concentration of total metal or metal incorporated into the reactive fraction in the soil and the tissue-metal concentration in N. diversicolor. The results appear to indicate that this species preferentially accumulates metals associated with reduced forms of sulfur (pyrite and presumably AVS). Oxidation of these metal sulfides would lead to release of Cu and Ni into interstitial water and they would then be readily available to be taken up by these organisms, either by absorption through the body surface or across the digestive tract.
84802931
Accumulation and detoxification of copper and zinc by the decapod crustacean Palaemonetes varians from diets of field-contaminated polychaetes Nereis diversicolor
Abstract In an investigation of the trophic transfer of ecotoxicologically significant amounts of trace metals from prey to predator, Palaemonetes varians were fed with diets of Nereis diversicolor from two metal-contaminated estuaries, the Tavy and Restronguet Creek in SW England, and a control estuary, the Blackwater in SE England. The decapods accumulated increased concentrations of copper (but not zinc) from the metal-contaminated worms above an initial apparently regulated body copper concentration, in response to a high dietary copper input over a period up to 30 days. High dietary challenges of copper caused the induction of MTLP (metallothionein-like proteins) in the hepatopancreas of the feeding decapods as a detoxification response, although the non-detoxified subcellular component of hepatopancreas accumulated copper also increased over time, probably in association with sublethal toxic effects.
86874810
Tolerance and accumulation of the trace metals zinc, copper and cadmium in three populations of the polychaete Nereis diversicolor
The comparative tolerance and accumulation of the trace metals zinc, copper and cadmium in populations of the littoral polychaete worm Nereis diversicolor from three sites: (a) heavily metal-contaminated Dulas Bay in Anglesey, north Wales, (b) the Blackwater estuary, Essex, as a control site, and (c) West Thurrock, the Thames estuary as a site of intermediate metal contamination, were investigated. Worms from Dulas Bay did not show increased tolerance to any metal, but worms from West Thurrock showed significantly increased copper sensitivity compared to the worms from Dulas Bay and the Blackwater. Worms accumulated zinc and copper from sediments with raised zinc and copper concentrations, and all three metals from solution in proportion to dissolved concentration. Accumulated metal was not excreted in 21 days and field concentrations of zinc and copper in the worms differed between sites. There was no evidence for inter-populational differences in accumulation rates of zinc and cadmium from solution, but worms from Dulas Bay accumulated copper from solution at a significantly higher rate than did worms from the other two sites. Nereis diversicolor takes up and accumulates zinc and cadmium from solution at similar rates per unit molar exposure, but cadmium is taken up at a greater rate per unit free metal ion molar exposure. Although N. diversicolor from Dulas Bay is exposed to very high availabilities of zinc and copper, accumulation and detoxification mechanisms are sufficient to cope with the extra metal influx (accentuated for dissolved copper) without selection for a metal-tolerant population.
93123697
Principles of Aquatic Chemistry
An introductory text on aquatic chemistry, emphasizing a mathematical, quantitative approach to the field. Covers conservation of mass, thermodynamics and kinetics, chemical equilibrium calculations, acid-base, precipitation-dissolution, coordination, redox, and surface chemistry.
40502983
Sequential extraction analysis of heavy metals using a chelating agent (NTA) to counteract resorption.
The geochemical partitioning of Pb, Ni and Zn in contaminated quartz-rich sediment and soil samples was characterized by sequential extraction analysis in the presence and absence of nitrilotriacetic acid (NTA). With NTA, levels of metals recovered are higher in the earlier steps and lower in the later steps of the procedure. This suggests that post-extraction resorption is effectively counteracted by chelation, thereby improving the accuracy of the method. An NTA concentration of 200 mg liter(-1) appears to be sufficient for counteracting resorption without causing significant dissolution of non-targeted phases in the samples studied. However, experiments using reference materials spiked with solutions containing Pb, Ni, Cu and Zn suggest that resorption will remain a problem when large amounts of strong sorbents such as organic matter are present. The results also show that although post-extraction resorption does occur in the absence of NTA, the magnitude of resorption is small (<20 to 30% of the summed total of metal present in the sample) in quartz-rich sediments.
86726218
Partitioning of trace metals in sediments: Relationships with bioavailability
As a result of complex physical, chemical and biological processes, a major fraction of the trace metals introduced into the aquatic environment is found associated with the bottom sediments, distributed among a variety of physico-chemical forms. As these different metal forms will generally exhibit different chemical reactivities, the measurement of the total concentration of a particular metal provides little indication of potential interactions with the abiotic or biotic components present in the environment. In principle, the partitioning of sediment-bound metals could be determined both by thermodynamic calculations (provided equilibrium conditions prevail) and by experimental techniques. The modelling of sediment-bound metals is far less advanced than is that of dissolved species, primarily because the thermodynamic data needed for handling sediment-interstitial water systems are not yet available. The partitioning of a metal among various fractions obtained by experimental techniques (e. g., sequential extraction procedures) is necessarily operationally defined. These methods have, however, provided significant insight into the physico-chemical factors influencing the bioavailability of particulate trace metals; some of these factors are discussed.
22669841
A review of the biology, ecology and potential use of the common ragworm Hediste diversicolor (O.F. Müller) (Annelida: Polychaeta)
AbstractThe common ragworm Hediste diversicolor inhabits the shallow marine and brackish waters in the North Temperate Zone of the Atlantic. This infaunal species builds U or Y-shaped burrows in the soft sediments. H. diversicolor is gonochoristic and remains atokous throughout its life. Due to the facility of harvesting of individuals by hand and their maintenance, this species represents a good biological material for experimental studies. In consequence, the common ragworm served as a model for endocrine control of reproduction in Polychaeta and played a fundamental role in the study of immune defence in Polychaeta.Life history characteristics (longevity, spawning season, feeding tactics and growth) and population dynamics (sex ratio, density and biomass) vary greatly according to geographical location of the populations. In addition, inter-population morphological, biochemical and physiological differences have been noticed in individuals from different areas and different environmental conditions in the same areas and could be related to the limited dispersal capacity of the species.
H. diversicolor interacts with its environment. The construction of burrows by individuals increases the sediment–water interface. When they ventilate their burrows, individuals verticalize oxic zones into the sediment and promote microbial and meiofaunal growth alongside their burrows. Moreover, the common ragworm is a species of commercial interest because of its use as bait in recreational fishing and as food in aquaculture. In order to alleviate environmental pressure caused by excessive demand over optimal sustainable yield of bait fisheries, intensive aquaculture has been proposed. The common ragworm could be also used as biomonitor of pollution in estuarine ecosystems.
38287839
Accumulation of cadmium by Nereis virens.
Cadmium concentration in Nereis virens exposed to sediment spiked with cadmium increased linearly with time, no equilibrium concentration being indicated by 24 days of exposure. The concentration with N. virens also increased with concentration of Cd in the sediment, and smaller worms accumulated higher amounts per unit weight than larger worms. With exposure to sediment containing 1 to 4 ppm Cd, accumulation rates ranged from 0.018 to 0.037 microgram Cd/g dry wt/hr for 1- to 2-g worms and from 0.014 to 0.024 microgram Cd/g dry wt/hr for 5- to 7-g worms. N. virens exposed to 0.03 to 9.2 ppm Cd in sea water for 14 days had accumulation rates of 0.019 to 2.217 microgram Cd/g dry wt/hr for 1- to 2-g worms and 0.013 to 1.327 microgram Cd/g dry wt/hr for 5- to 7-g worms. There was practically no excretion of cadmium for N. virens with initial concentrations of 5 to 20 microgram Cd/g dry wt during 75 days in clean conditions. Sediment containing 1 and 4 ppm Cd produced concentrations of about 0.03- and 0.1-ppm cd in the overlying water. The accumulation rates from sediment with 1 and 4 ppm Cd are equal to the rates from sea water with 0.03 and 0.1 ppm Cd, respectively, indicating that cadmium uptake by N. virens is primarily from the aqueous phase.
85768127
Modelling cadmium accumulation by benthic invertebrates in situ: The relative contributions of sediment and overlying water reservoirs to organism cadmium concentrations
An in situ experiment was designed (1) to determine the relative importance of Cd in the sediment versus Cd in the overlying water for its accumulation in benthic animals and (2) to test in situ the acid volatile sulfide (AVS) model. Sediments of a low-Cd shield lake were artificially contaminated with various amounts of Cd and placed at a littoral site in open plastic containers in the lake bottom for 11 months to allow colonization by indigenous lake bcnthos. Gradients in sedimentary and interstitial water Cd concentrations were, thus, created in situ, although Cd concentrations in the overlying water remained low. Accumulation of Cd by benthic invertebrates was significantly and linearly correlated with sediment Cd concentrations across treatment levels for most taxa. The magnitude of the response to the sediment Cd gradient was taxon specific and consistent with differences in animal ecology. Despite the high Cd contamination levels attained in the experiment, the population densities of most taxa appear to have been unaffected by the presence of Cd. We used the results from the experimental containers to predict the sources of Cd for benthic animals in the environs. For almost all of the taxa studied, individuals living in the lowCd sediments outside the experimental containers accumulated their Cd almost exclusively from the overlying water; only the burrowing, sediment-feeding taxa Chironomus stuegeri and members of the Tubificidae obtained substantial Cd from the sediment. Cadmium activities in the pore waters of the containers were in agreement with the AVS model, but the Cd concentrations found in the benlhic organisms did not. Our results from this shield lake suggest that predictions of Cd concentrations in most benthic animals would be more accurate if they were based on water column rather than on sedimentary Cd concentrations. Metals associated with sediments pose a potential threat to benthic organisms and from there to upper trophic levels. Before expensive remedial actions are undertaken, the extent to which benthic animals accumulate sedimentary metals, the biological effects of these contaminants, and the effects of various remedial actions on both water quality and organisms need to be determined. To accomplish these tasks, environmental agencies need reliable predictive tools; however, the majority of the tools currently available are unsatisfactory (Luoma 1995). Our ability to predict the biological consequences of metal-contaminated sediments would be improved by the development of reliable models relating metal bioaccumulation or toxicity to metal concentrations in the environment of benthic organisms. For general application, such models should be based on solid scientific grounds, i.e., they should have a theoretical rather than a
82864943
The estuary as a habitat an analysis of data on the soft-bottom Macrofauna of the Estuarine area of the rivers rhine, Meuse, and Scheldt
CONTENTS 1. Introduction 5 2. Methods 8 2.1. Sampling methods 8 2.2. Sorting and preservation of the samples 10 2.3. Measuring methods for the environmental factors....... 10 2.3.1. Introduction 10 2.3.2. The grain-size data 10 2.3.3. Amount of organic matter 12 2.3.4. The interstitial water 14 2.3.5. Exposure to waves 14 2.4. Mathematical methods 15 3. The environment 17 3.1. Weather and climate 17 3.2. The morphology of the Delta area 19 3.3. Substrate and sediments 20 3.3.1. Types of sediments and substrate 20 3.3.2. Distribution of sediments..... ...... 22 3.3.3. Sorting of sediments 25 3.3.4. Important characteristics of sediments........ 25 3.3.4.1. Water circulation 25 3.3.4.2. Interstitial temperature 29 3.3.4.3. Interstitial salinity 29 3.3.4.4. Oxygen in the interstitial environment...... 34 3.3.5. Organic matter 35
56274973
Trace metals in populations of Marphysa sanguinea (Montagu, 1813) from Sado estuary: effect of body size on accumulation
Concentrations of Fe, Zn, Cu, Pb and Cd were measured in four surface sediments, whole worm tissues and faeces collected along Aguas de Moura channel in Sado estuary. Six wet-weight worm classes were used to analyze the influence of weight. The metal concentration in colonized sediments is high for Fe and Cu, moderate for Pb and Zn, and low for Cd. The analyses of whole worm tissues show that Zn, Cd and Cu are accumulated. Considering the elevated sediment concentrations to which this species is exposed, the high levels of Zn and Cu suggest sequestration and Cu adaptation. However, the low Fe concentration indicates that this metal is not readily available. The similar Pb behaviour also suggests low availability or Fe interference. The high correlation in the sediment between Pb and Fe reinforces this suggestion. The results obtained show that Pb, Zn and Fe are the most important metals in the different weight classes. The overall results of this study show: (1) that this worm is able to adapt physiologically to elevated levels of metals; and (2) that the weight of the worms needs to be taken into account in environmental management programmes.
25363497
The metabolic and fitness costs associated with metal resistance in Nereis diversicolor.
The population of Nereis diversicolor inhabiting the upper reaches of Restronguet Creek, Cornwall, UK is highly resistant to acute zinc and copper toxicity. Here we employ bioenergetic accounting and fecundity counts to demonstrate the energetic costs associated with this phenomenon in terms of the worms' allocation of metabolic resources and reproductive output [P(r)]. Metal-resistant animals exhibited a scope for growth that was 46-62% less than that of animals from two non-resistant reference populations, corresponding to a mean metabolic cost of 1.31 mJ h(-1)mg DW(-1). The resistant population also contained 13% less lipid than animals from the reference populations and 73-81% less carbohydrates. Consequently, mass-specific fecundity was reduced in resistant animals by 39-45%, although material investment in individual gametes did not appear to vary. This demonstrates fitness costs associated with metal resistance in this ecologically important polychaete and adds to our understanding of phenotypic trade-offs associated with resistance.