Determining sediment quality for regulatory proposes using fish chronic bioassays

Sediment quality assessments for regulatory purposes (i.e. dredged material disposal) are characterized by linking chemical and acute ecotoxicological data. The design of chronic bioassays that incorporate more sensible endpoints than acute tests is discussed to address sediment quality for environmental quality assessment and regulatory proposes. The chronic tests use juveniles of commercial species of fish Sparus aurata and Solea senegalensis, to assess sediment toxicity in samples collected along different littoral areas in the North and the South of Spain. The organisms were exposed during 60 days and sublethal endpoints were selected including biomarkers of exposure to metals (metallothioneins - MTs) and to organic contaminants (ethoxyresorufin-O-deethylase activity - EROD activity) and biomarkers of effect (histopathology in different tissues, gill and liver). A Multivariate Analysis Approach was conducted in order to associate these biological responses with sediment metal concentration from the ports and with chemical residues in biological tissues exposed to sediments under laboratory conditions.     

A phytochelatin-based bioassay in marine diatoms useful for the assessment of bioavailability of heavy metals released by polluted sediments

The aim of the present work was to develop a new bioassay involving the presence of phytochelatins (PCs), detoxifying intracellular metal-binding peptides, in microalgae as response to metal bioavailability in re-suspensions of metal-polluted marine sediments. For this purpose, the synthesis of PCs has been studied in laboratory cultures of three marine diatoms, namely Phaeodactylum tricornutum, Thalassiosira weissflogii and Skeletonema costatum, exposed to elutriates of sediments collected in a polluted coastal area in the province of Pisa (Tuscany, Italy). Short- and long-term incubations in the elutriates of two marine sediments (named A and B) exhibited an increase of PCs synthesis in all the phytoplanktonic species examined, when the elutriate concentration increased from 0% to 100%. Elutriate B, which was mainly contaminated by Cd, was shown to be more effective to induce PCs than elutriate A, which was richer in Cu and TOC. The results show that the PCs response, in the microalgae examined, was species-specific. Our data also show that the PCs synthesis occurred before the growth rate was affected, thereby indicating that PCs can be considered as an early warning response of metal exposure. The PCs response in exponentially growing cultures of T. weissflogii, which was found to be the most sensitive alga, increased when the initial cellular density decreased. Finally, the positive relationship obtained between the cellular PCs concentration in T. weissflogii and the degree of metal contamination of the elutriates from twelve sediments collected in a metal-polluted coastal area, confirmed that the PCs-induction test can be applied in field studies. In conclusion, the response of these marine microalgae suggests that these cellular peptides could represent an excellent biomarker of metal exposure, which is useful for the assessment of sediment toxicity, by carrying out PCs-induction tests on sediment elutriates.     

Physico-chemical and toxicological characterization of the historic estuarine sediments: a multidisciplinary approach

The accumulation rates, the geochronology of metals and PAH contamination, and the Microtox toxicity are studied in five sediment cores (50 cm length) covering different areas of the Santander Bay, Northern Spain. Chronology given by (210)Pb and (137)Cs reveals significant differences in accumulation rates between sites (0.2-1.1 cm/year), as well as a variable degree of anthropogenic enrichment factors for Fe, Mn, Cu, Pb, Zn, Ni (from 1 to 15) and concentrations of summation Sigma 16PAHs (from 0.01 to 23.84 mg/kg dw) in sediments over the last 90 years. The results indicate the increasing contamination pressure from industrial and urban activities along the Bay. No toxic results from the Microtox test are obtained either with pore water or with normalised sediment aqueous extracts (European Norm EN 12457), suggesting low water solubility and low availability of contaminants in the studied sediments. However, the EC50 values from the Microtox Basic Solid Phase Test (BSPT) ranged from 0.03% to 2.35%, showing vertical toxicity profiles in accordance with metal and PAHs behaviour. The correlation degrees of Microtox BSPT toxicity to chemical concentration in sediment profiles are widely variable showing a high site-dependent toxicity. The oligochaete Limnodrilus hoffmeisteri has been used as a chronic bioassay over surface sediments of two of the studied sites, showing results coherent with the Microtox BSPT acute test results. Global results of the present work provide regional geochemical baselines for metals and PAHs and toxicological data now make it possible to obtain a preliminary quality assessment of the Santander Bay sediment profiles.     

The use of a metallothionein-like-proteins (MTLP) kinetic approach for metal bioavailability monitoring in dredged material

Ecotoxicological effects associated with contaminants present in dredged material from Spain were determined using a marine biotest based on the determination of metallothionein-like-protein concentrations (MTLPs) in the shore crab Carcinus maenas. Intermoult female C. maenas were exposed in the laboratory to sediments from three Spanish ports, Ría de Huelva (SW, Spain), La Coru?a (NW, Spain) and Bahía de Cádiz (SW, Spain) per replicate during 21 days. Hepatopancreas samples from crabs were taken for metallothioneins analysis on days 0, 7 and 21. Furthermore, chemical analysis was performed in the stations to determine the degree and nature of sediment contamination (Cr, Ni, Cu, Zn, Cd, Pb, Hg, As, PAHs and PCBs). A significant increase (p<0.05) in metallothionein concentration was observed over time in individuals exposed to sediment from the port Ría de Huelva characterized by high concentrations of metals. A toxicokinetic approach is proposed in this study related to the use of this biomarker in C. maenas to evaluate bioavailability associated with metals present in dredged material. As a first step, this toxicokinetic approach might reveal as a sensitive tool for evaluating bioavailability of contaminants present in dredged material.     

An integrated approach to the toxicity assessment of Irish marine sediments: validation of established marine bioassays for the monitoring of Irish marine sediments

This paper describes the ecotoxicological evaluation of marine sediments from three sites around Ireland representative of a range of contaminant burdens. A comprehensive assessment of potential sediment toxicity requires the consideration of multiple exposure phases. In addition to the evaluation of multi-exposure phases the use of a battery of multi-trophic test species has been advocated by a number of researchers as testing of single or few organisms may not detect toxicants with a specific mode of action. The Microtox(R) solid phase test (SPT) and the 10-d acute amphipod test with Corophium volutator were used to assess whole sediment toxicity. Porewater and elutriates were assessed with the Microtox(R) acute test, the marine prasinophyte Tetraselmis suecica, and the marine copepod Tisbe battagliai. Solvent extracts were assayed with the Microtox(R) and T. battagliai acute tests. Alexandra Basin was identified as the most toxic site according to all tests, except the Microtox(R) SPT which identified the Dunmore East site as being more toxic. However, it was not possible to correlate the observed ecotoxicological effects with a specific and/or class of contaminants based on sediment chemistry alone. Therefore porewaters found to elicit significant toxicity (Dunmore East and Alexandra Basin) with the test battery were selected for further TIE assessment with T. battalgiai and the Microtox(R) system. The results of this study have important implications for risk assessment in estuarine and coastal waters in Ireland, where, at present the monitoring of sediment and water quality is predominantly reliant on chemical analysis alone.     

Availability and plant uptake of heavy metals from contaminated dredged material placed in flooded and upland disposal environments

The availability and plant uptake of heavy metals was evaluated from contaminated dredged material placed in flooded and upland disposal environments using a solid-phase plant bioassay. The objective of the study was to verify previous dredged material research results and to develop a plant bioassay procedure that could indicate phytotoxicity and bioaccumulation of heavy metals in contaminated dredged material. The plant bioassay indicated more uptake and bioaccumulations of cadmium and, to a lesser extent, zinc when contaminated dredged material was placed in an upland environment where the sediment was allowed to air-dry. Placing the contaminated dredged material in a flooded (reduced) environment lowered the availability and plant uptake of cadmium and, to a lesser extent, zinc. Factors that influenced the availability and plant uptake of heavy metals from contaminated sediments included sediment oxidation-reduction potential, organic matter content, total sulfur content, and pH. The plant bioassay showed phytotoxicity and bioaccumulation of arsenic under a flooded environment. Placing the arsenic-contaminated sediment in an upland environment reduced both the phytotoxicity and bioaccumulation of arsenic in the freshwater marsh plant Cyperus esculentus.     

Assessment of ecotoxicological risks related to depositing dredged materials from canals in northern France on soil

The implementation of an ecological risk assessment framework is presented for dredged material deposits on soil close to a canal and groundwater, and tested with sediment samples from canals in northern France. This framework includes two steps: a simplified risk assessment based on contaminant concentrations and a detailed risk assessment based on toxicity bioassays and column leaching tests. The tested framework includes three related assumptions: (a) effects on plants (Lolium perenne L.), (b) effects on aquatic organisms (Escherichia coli, Pseudokirchneriella subcapitata, Ceriodaphnia dubia, and Xenopus laevis) and (c) effects on groundwater contamination. Several exposure conditions were tested using standardised bioassays. According to the specific dredged material tested, the three assumptions were more or less discriminatory, soil and groundwater pollution being the most sensitive. Several aspects of the assessment procedure must now be improved, in particular assessment endpoint design for risks to ecosystems (e.g., integration of pollutant bioaccumulation), bioassay protocols and column leaching test design.     

Novel approach for assessing heavy metal pollution and ecotoxicological status of rivers by means of passive sampling methods

In order to study the pollution of fluvial ecosystems, it is necessary to analyze not only the levels of chemical contaminants in water, but also those accumulated in the sediment matrix, as well as to assess its ecotoxicological status. Eleven Catalan (Spain) river sections (one sampling point per river) located near urban and industrial areas were sampled during winter of 2009. Water pollutants were collected by using passive samplers as Diffusive Gradient in Thin-Films (DGTs) and Semi-Permeable Membrane Devices (SPMDs). Point water samples were also collected. The concentrations of potentially toxic elements (PTE) in water, filtered water, DGTs and sediment samples were analyzed. Aqueous and organic solvent extracts of sediments samples and organic extracts of SPMDs were performed to assess acute toxicity to Vibrio fischeri by Microtox(?), and chronic toxicity to the green alga Pseudokirschneriella subcapitata. Microtox(?) test was also performed with DGT extracts. The results show that metals content of Catalan river waters are below the freshwater screening US EPA benchmarks, excepting some industrial areas (for Hg, Pb, and Zn). In contrast, sediments levels of some rivers were far above freshwater sediment screening US EPA benchmarks (for Zn, As, Cr, Pb, Ni, Hg, and Mn), particularly in the most industrialized areas. A good correlation was found between toxicity values of extracts (from sediments and DGTs) and PTE levels in sediments. The current results support the suitability of using combined point and passive sampling methods for assessing the chemical and ecotoxicological status of aqueous environments.     

Using sediment quality guidelines for dredged material management in commercial ports from Spain

Dredged material contamination was assessed in different commercial ports from Spain: Port of Cádiz and Huelva, South West; Bilbao and Pasajes, North; Cartagena and Barcelona, East; Coru?a, North West. Sediment from different locations of these ports was sampled and was characterized following the Spanish recommendations for dredged material management. This characterization included grain size distribution, organic matter content and concentration of the chemical compounds included in the list of pollutants and hazardous substances (As, Cd, Cu, Cr, Hg, Ni, Pb and Zn; PCB congeners IUPAC number 28, 52, 101, 118, 138, 153 and 180; PAHs were also analyzed). The results were compared to the limit values of Spanish Action Levels that define the different categories for assessment and management. A set of empirically derived sediment quality guidelines (SQG) was used to assess the possible toxicity of the dredged materials and to improve the use of the chemical approach to characterize dredged material for its management.     

Chemical speciation of metals in sediment elutriates

Surface sediments from two localities in Lake Ontario (Hamilton Harbour and Portsmouth Harbour in Kingston, Ontario) were elutriated with lake water. The distribution of chemical species of metals (Fe, Cu, Ni, Pb, Mn, Cd, and Zn) and nutrients (N and P) was investigated in the elutriates and in the lake water by using the computer program geochem and separation by Chelex 100 resin. The concentration of Mn in the water increased from 10^?6.44M to 10^?5.09M during the elutriation of Lake Ontario sediments. The concentrations of other investigated metals were smaller and different in each of the elutriates. Both methods, the calculations by geochem and the separation by Chelex 100, showed that only Mn was present in the four elutriates as a free ion. However, the chemical speciation of other metals by these two methods was only partially similar. All four sediments released significant quantities of NH₃ which was associated in the elutriates mainly with H. The pH of the lake water decreased from 8.4 to 7.5 during the elutriation.     

Metal-contaminated soil remediation by using sludges of the marble industry: toxicological evaluation

The major risks due to metal pollution of sediments consist of leaching to groundwater and potential toxicity to animals and/or plants. The objective of this study was to evaluate by means of an ecotoxicological approach the effects of the addition of cutting marble sludges on the mobile metal fraction of sediments polluted with heavy metals. The study was carried out on two sediments derived from mining activities in Portman Bay (SE, Spain) polluted by heavy metals. These sediments were mixed with sludges left after the cutting of marble. The results obtained by leaching experiments showed that the addition of marble cutting sludge, consisting mainly of carbonates, to a heavy-metal polluted sediment produces a decrease of available metal forms. The carbonate content seems to play a role in chemical stabilisation of metals and in a decrease of toxicity of sediments. The leached solutions have a non-toxic effect. The mild remediation by addition of sludge has moreover effects to long term.     

Polycyclic aromatic hydrocarbons and effects on marine organisms in the Istanbul Strait

Surficial sediments and mussels (Mytilus galloprovincialis) from the Istanbul Strait and Marmara Sea were analysed for sixteen parent polycyclic aromatic hydrocarbon (PAH) contents by gas chromatography-mass spectrometry (GC-MS) employing isotope dilution technique. Microalgae toxicity testing was applied to sediment elutriates and biological responses in terms of filtration rate and lysosomal stability were measured in mussels. Total PAH concentrations ranged from 2.1 to 3152 ng g^? 1 dry wt in sediments and from 43–601 ng g^? 1 wet weight in mussels. Molecular indices of phenanthrene/ anthracene, fluoranthene/pyrene and benzo(a)anthracene/chrysene were used to differentiate between pyrolytic and petroleum origin. Results showed that most of the contamination originates from high temperature pyrolytic inputs with some slight contribution of petrogenic PAH. PAH in sediments were frequently lower than the National Oceanic and Atmospheric Administration (NOAA)–ERM (Effects Range Medium) index. Results of sediment elutriate toxicity testing and biomarkers indicate that the cause of negative effects in sediments may result from different classes of pollutants and does not only relate with PAH contamination. Mussels from most of the stations showed both reduced lysosomal membrane stability and filtration rate indicating disturbed health although the two biomarker results did not always complement each other. The effect studies showed that the pollutants in the strait ecosystem have more pronounced effects in the middle parts than those at the Black Sea entrance.     

Comparative sediment quality assessment in different littoral ecosystems from Spain (Gulf of Cadiz) and Brazil (Santos and São Vicente estuarine system)

The goal of this work was to establish comparisons among environmental degradation in different areas from Southern Spain (Gulf of Cádiz) and Brazil (Santos and S?o Vicente estuary), by using principal component analyses (PCA) to integrate sediment toxicity (amphipods mortality) and chemical-physical data (Zn, Cd, Pb, Cu, Ni, Co, V, PCBs, PAHs concentrations, OC and fines contents). The results of PCA extraction of Spanish data showed that Bay of Cádiz, CA-1 did not present contamination or degradation; CA-2 exhibited contamination by PCBs, however it was not related to the amphipods mortality. Ría of Huelva was the most impacted site, showing contamination caused principally by hydrocarbons, in HV-1 and HV-2, but heavy metals were also important contaminants at HV-1, HV-2 and HV-3. Algeciras Bay was considered as not degraded in GR-3 and -4, but in GR-3' high contamination by PAHs was found. In the Brazilian area, the most degraded sediments were found in the stations situated at the inner parts of the estuary (SSV-2, SSV-3, and SSV-4), followed by SSV-6, which is close to the Submarine Sewage Outfall of Santos - SSOS. Sediments from SSV-1 and SSV-5 did not present chemical contamination, organic contamination or significant amphipod mortality. The results of this investigation showed that both countries present environmental degradation related to PAHs: in Spain, at Ría of Huelva and Gudarranque river's estuary areas; and in Brasil, in the internal portion of the Santos and S?o Vicente estuary. The same situation is found for heavy metals, since all of the identified metals are related to toxicity in the studied areas, with few exceptions (V for both Brazil and Spain, and Cd and Co for Brazilian areas). The contamination by PCBs is more serious for Santos and S?o Vicente estuary than for the investigated areas in Gulf of Cádiz, where such compound did not relate to the toxicity.     

Containment area sizing for disposal of dredged material

Procedures are given for containment area sizing for retention of suspended solids based on the settling characteristics of the dredged material. Separate sizing procedures for freshwater and saltwater sediments provide for determination of the respective surface area or detention time required to accomodate continuous dredged material disposal. Procedures are given for the laboratory testing required to obtain data for sediment characterization, containment area sizing, and estimates of storage capacity required. These procedures can also be used for designing containment areas for other slurries having high suspended solids concentrations. Settling tests performed in a 20-cm-diam column were found to be satisfactory for defining dredged material settling behavior. Settling behavior in the freshwater environment was best described by a flocculent settling test, while behavior in a saltwater environment was best described by a zone settling test. The same settling columns were used for both tests withonly minor procedural changes. Procedures are presented for designing new containment areas for suspended solids retention and for evaluating the suspended solids retention potential of existing containment areas during planned disposal activities.     

A bioassay approach to determine the dioxin-like activity in sediment extracts from the Danube River: ethoxyresorufin-O-deethylase induction in gill filaments and liver of three-spined sticklebacks (Gasterosteus aculeatus L.)

Sediment samples from the upper Danube River in Germany have previously been characterized as ecotoxicologically hazardous and contaminants in these sediments may contribute to the observed decline of fish populations in this river section. For the investigation of sediment toxicity there is a need for development, standardization and implementation of in vivo test systems using vertebrates. Therefore, the main objective of this study was to apply and evaluate a recently established fish gill EROD assay as a biomarker in sediment toxicity assessment by using extracts of well characterised sediment samples from the upper Danube River. This to our knowledge is the first application of this novel assay to sediment extracts. Sediments from four different sites along the upper Danube River were Soxhlet-extracted with acetone and dissolved in DMSO. Three-spined sticklebacks (Gasterosteus aculeatus L.) were exposed for 48 h to various concentrations of the extracts, to the positive control beta-naphthoflavone or to the solvent. Measurements of EROD activity in gill filaments and liver microsomes followed the exposure. Concentration-dependent induction of EROD in both gill and liver was found for all sediment extracts. The highest EROD-inducing potency was determined for extracts of sediments from the sites "Opfinger See" and "Sigmaringen" and the EROD activities in gill and liver correlated well. The results from the gill and liver assays were in accordance with in vitro results of previous investigations. The EROD activities measured in the present study corresponded with the concentrations of PAHs, PCBs and PCDD/Fs in the sediment samples derived in a previous study. The sticklebacks in this study were in the reproductive phase and a stronger EROD induction was obtained in the females than in the males. Implementation of the EROD assay in testing of sediment extracts gave highly reliable results which make this assay an ecotoxicologically relevant method for assessment of contamination with Ah receptor agonists in sediments.     

Toxicological availability of nickel to the benthic oligochaete Lumbriculus variegatus

It is generally accepted that the bioavailability of metals in sediments is influenced by the presence of acid volatile sulfides (AVS). The pore water hypothesis predicts that, if the molar concentration of simultaneously extracted metals (SEM) in a sediment is smaller than the molar concentration of AVS, the free metal ion activity in the pore water is very small and that consequently no metal toxicity in short-term toxicity tests is observed. In this study we examined (1) if this concept can be extended to predict the absence of chronic Ni toxicity to the oligochaete deposit-feeding worm Lumbriculus variegatus and (2) if the organic carbon normalized excess SEM; i.e. [SEM-AVS]/f(OC) predicts the magnitude of Ni toxicity to L. variegatus. A 28-day toxicity experiment was performed in which biomass production of L. variegatus was determined in two natural sediments with different [AVS] and f(OC), spiked at different Ni concentrations. The absence of toxicity is predicted correctly by the [SEM-AVS]<0 criterion when only the 0-1 cm surface layer of the sediment is considered, but not when the whole bulk sediment is considered (0-3 cm). In both sediments, the same [SEM-AVS]/f(OC) at the surface corresponds with a similar decrease in L. variegatus biomass. Thus, [SEM-AVS]/f(OC) in the surface layer accurately predicts the magnitude of toxicity. This measure is therefore a good estimator of toxicologically available Ni. On the other hand, the free Ni(2+) ion activity in the overlying water appeared to be an equally good predictor of the magnitude of toxicity. Consequently, it was not possible to determine the relative importance of the overlying water and pore water exposure route with the semi-static laboratory experiments.     

Screening ecological risk assessment of persistent organic pollutants in Mediterranean sea sediments

A screening ecological risk assessment (ERA) was conducted for the first time in the Mediterranean basin in order to assess the toxicity posed to the benthic community by PCBs, DDTs and HCB in marine sediments. The characterization of the exposure was conducted by means of an extensive literature survey, generating a database with more than 2000 samples. The effects were assessed by the adoption of guidelines previously developed in the literature, because ecotoxicological information about persistent organic pollutants (POPs) in the Mediterranean sediments was lacking. Existing sediment quality guidelines (SQGs) for the target pollutants were compiled and consensus values were calculated for three different categories of toxicity, namely threshold effect concentration (TEC), probable effect concentration (PEC) and extreme effect concentration (EEC). The combination of exposure and effects characterization enabled the identification of some areas of concern in the vicinity of industrial and urban locations and in the mouths of the main Mediterranean rivers. Beyond the Mediterranean continental shelf, the level of toxicity for the benthic community was generally low. The evaluation of the toxicity induced by the mixture of the target pollutants spotted the importance of DDT contamination in the Mediterranean sediments, despite the fact that main inputs to the sea have been significantly reduced during the last decades.     

Sediment quality in Rio Guadiamar (SW, Spain) after a tailing dam collapse: contamination, toxicity and bioavailability

An integrated assessment of sediment quality in the Guadiamar River after a mining spill was conducted. The concentration of different metals and other conventional parameters were measured in sediments located along the river. Four sediment toxicity tests (Hyalella azteca 28-day survival and growth test; Chironomus riparius 10-day survival and growth test; Hexagenia spp. 21-day survival and growth test; and Tubifex tubifex 28-day reproduction and survival test) were carried out to determine the effects associated with the accidental spill. The geochemical fractions of 6 metals (Fe, Mn, Zn, Cu, Pb, and Cd) were determined to establish the bioavailability of the metals. The relationship found in the concentrations of metals associated with the mobile fractions of the sediments in the sites studied is similar to the toxic mud from tailing pond and confirms that the toxic effects are associated with the metals Zn and Cd originating from the spill.     

Alteration of steroidogenesis in H295R cells by organic sediment contaminants and relationships to other endocrine disrupting effects

A novel bioassay with the human adrenocortical carcinoma cell line H295R can be used to screen for endocrine disrupting chemicals that affect the expression of genes important in steroidogenesis. This assay was employed to study the effects of organic contaminants associated with the freshwater pond sediments collected in the Ostrava-Karvina region, Czech Republic. The modulation of ten major genes involved in the synthesis of steroid hormones (CYP11A, CYP11B2, CYP17, CYP19, 17betaHSD1, 17betaHSD4, CYP21, 3betaHSD2, HMGR, StAR) after exposure of H295R cells to sediment extracts was investigated using quantitative real-time polymerase chain reaction (PCR). Crude sediment extracts, containing high concentrations of polycyclic aromatic hydrocarbons (PAHs) and moderate amounts of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) significantly stimulated expression of the CYP11B2 gene (up to 10-fold induction), and suppressed expression of 3betaHSD2 and CYP21 genes. A similar pattern was observed with the extracts after treatment with concentrated sulfuric acid to remove labile chemicals (including PAHs) leaving only persistent PCBs, OCPs and potentially PCDD/Fs. Comparison of the results with other mechanistically based bioassays (arylhydrocarbon receptor, AhR, mediated responses in H4IIE-luc cells, and estrogen receptor mediated effects in MVLN cells) revealed significant endocrine disrupting potencies of organic contaminants present in the sediments (most likely antiestrogenicity). Pronounced effects were observed particularly in sediment extracts from the Pilnok Pond which harbors an unusual intersexual population of the narrow-cawed crayfish Pontastacus leptodactylus (Decapoda, Crustacea). This pilot study provided the first experimental evidence of the wider application of the H295R bioassay for screening complex environmental samples, and the results support the hypothesis of chemical-induced endocrine disruption in intersexual crayfish.