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.     

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.     

Unraveling the causes of the toxicity of extremely acid waters of volcanic origin

A river ecosystem in East Java, Indonesia, fed by a volcanic lake with high concentrations of dissolved metals and a low pH, was found to support only few macroinvertebrates. To unravel the causes of toxicity and to determine the level of dilution necessary to obtain non-toxic water, a bioassay was conducted with the fairy shrimp Thamnocephalus platyurus. A partial toxicity identification evaluation (TIE) approach was used with EDTA as a chelating agent to relate toxicity to pH and metal concentrations. Three water samples were tested, with pHs ranging from 0.72 to 4.5, and diluted with water from a neutral river to different degrees. The dilution factor necessary to achieve no more than 50% mortality in the Thamnotox test (Ldf(50)) varied from >300 at the most acidic site, to 7 for water of pH 2.6 and 1.5 for water of pH 4.5. Toxicity was best explained from both low pH and high concentrations of metals, especially Al and Fe. The key role of Al and Fe in the toxicity was confirmed by relating concentrations of the different compounds in the river water to toxicity data from the literature. EDTA addition did not significantly influence Ldf(50) or the lethal pH 50% (LpH(50)), suggesting a large effect, besides cationic components and pH, of anions (F, SO(4) and Cl).     

Identification of metal toxicity in sewage sludge leachate

Sewage sludge is a source of organic matter and nutrients with the potential for being used as a fertilizer. However, metals in sewage sludge might accumulate in soil after repeated sludge applications, and metal concentrations might reach concentrations that are toxic to microorganisms, soil organisms and/or plants. This toxicity might change with time due to kinetic factors or abiotic factors such as freezing, drying or rainfall. The objective of this study was to determine toxicity of sewage sludge leachate from a lysimeter with 50 cm of sludge applied. Attempts were also made to identify the cause of toxicity of the sludge leachate by toxicity identification and evaluation (TIE) techniques. Sludge leachate was collected monthly during 1 experimental year (August 2001 to August 2002). Metal concentrations were analysed, and the toxicity was determined with Daphnia magna (48-h immobility). The effect of EDTA or sodium thiosulphate addition, filtration through a CM-resin or a Millex-resin on toxicity was also tested. The results showed that toxicity of the sludge leachate apparently varied during the year, and that filtration through the CM-resin reduced most of the toxicity followed by the addition of EDTA. None of the other treatments reduced the toxicity of the sludge leachate. This indicated that one or more metals were responsible for the observed toxicity. Further calculations of toxic units (TU) suggested that Zn contributed most to the toxicity. Results also indicated that Ca concentrations in the sludge leachate reduced the toxicity of Zn.     

Porewater as a matrix in toxicity bioassays with sea urchins and bivalves: evaluation of applicability to the Venice lagoon (Italy)

Porewater plays an important role in sediment toxicity assessment using bioassays, but the most reliable extracting method and the potential contribution of confounding factors to the real toxicity need to be studied. The applicability of bioassays with the early life stages of Paracentrotus lividus, Mytilus galloprovincialis and Crassostrea gigas on porewaters extracted by centrifugation from the Venice Lagoon (Italy) is evaluated and demonstrated: toxicity tests can discriminate the toxicity of porewaters from sites with different kinds and levels of pollution and, using toxicity scores, data are classified in five toxicity classes. Sulphides do not represent a confounding factor in porewater toxicity; in contrast ammonia exhibited some concentrations above the toxicity threshold for sea urchin embryos.     

Correlation of field-measured toxicity with chemical concentration and pollutant availability.

Direct field toxicity tests were performed in two Louisiana waterways, Bayous Trepagnier and St. John, on sediments containing organic/heavy metal mixtures. Our approach involved bioluminescent bacterial toxicity assays (using DeltaTox, which qualitatively identifies polluted areas, and Microtox, which quantifies toxicity). Samples were more completely analyzed in our laboratory using inductively coupled plasma atomic emission spectroscopy (ICP-AES) and gas chromatography/mass spectrometry (GC/MS). Results indicate that lead is the primary toxic metal at the sites examined, though concentrations of metals fluctuate due to spatial variation and the dynamic nature of the waterways. Polycyclic aromatic hydrocarbons (PAHs) are the most abundant group of organics measured and appear to contribute to the overall toxic response. DeltaTox located toxic hotspots where there was an average light loss of 53-100%. Toxicity results from both assays agree but are well correlated with concentration measurements only for certain sediment fractions. Overall, the DeltaTox/Microtox approach appears to be rapid and cost effective for on-site hotspot identification, and may increase understanding of hazards associated with heavy metal and organic contaminants in these waterways.     

Speciation of heavy metals in marine sediments from the East China Sea by ICP-MS with sequential extraction

Twelve elements (V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Sn, Cd and Pb) in 24 sediment samples at eight sites (S1-S8) from the East China Sea were analyzed with the BCR sequential extraction (SE) protocol to obtain the metal distribution patterns in this region. The results showed that the heavy metal pollutions in S4 and S8 were more severe than in other sampling sites, especially Cd and Pb pollution. In the top sediments at S4 and S8, both the total contents and the most dangerous non-residual fractions of Cd and Pb were extremely high. More than 90% of the total concentrations of V, Cr, Mo and Sn existed in the residual fraction. Fe, Co, Ni, Cu and Zn mainly (more than 60%) occurred in the residual fraction. While Mn, Pb and Cd dominantly presented in the non-residual fractions in the top sediments. The metal distribution patterns with depth and the correlations between total organic carbon (TOC) and the total Fe-Mn content were also investigated. The results showed that, for most of the elements except Fe, the concentration of elements in fraction A in the top sediments was higher than that in other depth. The similar rule was also found in fraction B but not in fraction C. Besides, the distributions of V, Cd in fraction B and Pb, Cd, Cu in fraction C might be affected by TOC.     

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.     

MEAD (part II)-Predictions of radioactivity concentrations in the Irish Sea

The predictions from MEAD, a model that simulates the transport of radionuclides in the marine environment, are presented for the Irish Sea. MEAD predictions for (137)Cs and Pu(alpha) are presented following discharges from BNFL Sellafield and the predictions compared to measured data from near the discharge location and further a field in the Irish Sea. The model performs well in most circumstances given the uncertainties involved in both modelling and data collection although some inconsistencies in the predictions are found. MEAD is also compared to other models of radionuclide transport in the Irish Sea.     

Impact of dredging in a shallow coastal lagoon: Microtox Basic Solid-Phase Test, trace metals and Corophium bioassay

The aim of this work was to measure survival of the amphipod Corophium insidiosum and luminescence inhibition in the marine bacterium Vibrio fisheri on surface sediment samples collected from a shallow coastal lagoon (Pialassa Baiona, northern Adriatic Italian coast) before execution of dredging operations to deepen the main inner channel of the lagoon and restore the water circulation. Trace metal (Cd, Cu, Cr, Hg, Ni, Pb) concentrations, grain size and organic carbon matter content as loss of ignition were also measured. Toxicity testing with V. fisheri was carried out according to the Microtox Basic Solid-Phase Test (BSPT) protocol. The preliminary outcomes of this work show that: (a) the investigated area can be categorised as moderately degraded; (b) there is no evident spatial pattern in sediment toxicity and trace metal concentrations; (c) Microtox responses are not biased by sediment characteristics such as silt, clay and organic matter content.     

An assessment of toxicity in profundal lake sediment due to deposition of heavy metals and persistent organic pollutants from the atmosphere

A Tier I Sediment Ecological Risk Assessment of profundal lake sediment contaminated by diffuse pollution of heavy metals and POPs deposited from the atmosphere was completed. The concentrations of seven heavy metals and four groups of POPs (OCs, PCBs, PAHs, PBDEs) were determined in the profundal sediment of ten lakes in the United Kingdom and two sediment toxicity tests completed (chironomid survival and emergence and cladoceran survival and reproduction). The results showed that around half the lakes are at least moderately contaminated by Pb, Zn, Cd, As and PAHs deposited from the atmosphere and the toxicity quotient suggests that the contaminants of concern are Pb, As and PAHs, and not the other metals nor OCs and PCBs. There was toxicity in the sediment of four of the lakes. The Probable Effect Concentration Quotient values indicated that metals in the sediments of Scoat Tarn, Agden Reservoir and Llyn Llagi were likely to be responsible for the laboratory toxicity found in these lakes, with PAHs also contributing in Agden Reservoir.     

Aeolian contributions of trace metals to marine sediments of Kuwait

Concentrations of silver, cadmium, chromium, iron, manganese, nickel, lead, vanadium, and zinc were determined in dust fallout samples from eight inland locations in Kuwait. Results were used to calculate enrichment factors for metals relative to their abundance in the continental crust using Fe as the conservative element. Five metals (Cu, Cr, Mn, Ni, and V) showed enrichment factors that were approximately unity (1.3–4.7). Higher enrichment factors for the rest (24–421) suggested an anthropogenic contribution for Ag, Cd, Pb, and Zn. However, all metals in dust fallout (except Pb and Zn) showed a degree of enrichment relative to unpolluted marine sediments that was approximately unity, suggesting a substantial aeolian contribution to trace metals in marine surface sediments. Higher enrichments for Pb and Zn probably reflect a larger input from local pollution sources. This is particularly true for lead, the enrichment of which showed a stronger association with the distribution of urban population. Probable contributions of aeolian transport to a band of elevated lead concentrations in marine surface sediments are discussed.     

A new hazard index of complex mixtures integrates bioconcentration and toxicity to refine the environmental risk assessment of effluents

A new methodology to evaluate the overall environmental hazard of unknown mixtures, based on bioconcentration potential and toxicity, was developed using a combination of two methodologies: 1) the estimation of the octanol-water partition coefficient (K(ow)) using reverse-phase high performance liquid chromatography (RP-HPLC) and 2) the toxicity identification evaluation (TIE). Forty seven compounds with known K(ow) and different molecular structures where used for the calibration of the log K(ow) in relation to the retention time in reverse-phase high performance liquid chromatography (RP-HPLC). A linear regression with an R(2)=0.81 and an sd=0.69 was established between log K(ow) and RP-HPLC retention time. This K(ow) estimation method was furthermore validated using seven additional compounds, showing acceptable estimations of the log K(ow) of unknown substances. Two different mixtures were tested, one containing 3,4 Dichloroaniline, Diazinon and 4-Nonylphenol and another one containing a mixture of 16 pesticides. Both mixtures were first tested as a whole effluent and then fractionated and tested, using a miniaturized Daphnia magna test. An equation is presented, that combines both methodologies and establishes a relative hazard index RHI, ranging from 1 to 10 for any particular mixture of chemicals. The results show how the method presented can refine the security factors that could be included in the environmental risk assessment of effluents in the future.     

An estimation of radiation doses to benthic invertebrates from sediments collected near a Canadian uranium mine.

A new method is described for calculating radiation doses to benthic invertebrates from radionuclide concentrations in freshwater sediment. Both internal and external radiation doses were estimated for all 14 principal radionuclides of the uranium-238 decay series. Sediments were collected from three sites downstream of a uranium mining operation in northern Saskatchewan, Canada. Sediments from two sites, located approximately 1.6 and 4.4 km downstream from mining operations, yielded absorbed doses to both larval midges, Chironomus tentans, and adult amphipods, Hyalella azteca, of 59-60 and 19 mGy/year, respectively, compared to 3.2 mGy/year for a nearby control site. External beta radiation from protactinium-234 (234Pa) and alpha radiation from uranium (U) contributed most of the dose at the impacted sites, whereas polonium-210 (210Po) was most important at the control site. If a weighting factor of 20 was employed for the greater biological effect of alpha vs. beta and gamma radiation, then total equivalent doses rose to 540-560 mGy/year at the site closest to uranium operations. Such equivalent doses are above the 360-mGy/year no-observed-effect level for reproductive effects in vertebrates from gamma radiation exposure. Data are not available to determine the effect of such doses on benthic organisms, but they are high enough to warrant concern. Detrimental effects have been observed in H. azteca at similar uranium concentration in laboratory toxicity tests, but it remains unclear whether the radiotoxicity or the chemotoxicity of uranium is responsible for these effects.     

从清洁生产到循环经济

清洁生产和循环经济是20世纪90年代以来在我国引人注目的两项实践。正确认识、积极推进清洁生产和循环经济,对于转变我国经济增长方式与发展模式、促进可持续发展具有重要意义。在将资源环境要素纳入经济系统内部,转变经济增长方式,促进资源环境和经济结合一体化发展模式的概念意义下,本文从宏观历史层面阐述了我国清洁生产和循环经济的发展过程、必然趋势及其长期曲折、交错推进的过程特征。分析了以废物循环作为循环经济的认识和实践误区,提出了以清洁生产为基础推进产业生态化,结合强化末端管制,以及围绕建立“绿色”市场进行制度创新为基本内容的发展我国循环经济的建议。     

Fixation of Cs to marine sediments estimated by a stochastic modelling approach

Dumping of nuclear waste in the Kara Sea represents a potential source of radioactive contamination to the Arctic Seas in the future. The mobility of 137Cs ions leached from the waste will depend on the interactions with sediment particles. Whether sediments will act as a continuous permanent sink for released 137Cs, or contaminated sediments will serve as a diffuse source of 137Cs in the future, depends on the interaction kinetics and binding mechanisms involved. The main purpose of this paper is to study the performance of different stochastic models using kinetic information to estimate the time needed for Cs ions to become irreversibly fixed within the sediments. The kinetic information was obtained from 134Cs tracer sorption and desorption (sequential extractions) experiments, conducted over time, using sediments from the Stepovogo Fjord waste dumping site, on the east coast of Novaya Zemlya. Results show that 134Cs ions interact rapidly with the surfaces of the Stepovogo sediment, with an estimated distribution coefficient Kd(eq) of 300 ml/g (or 13m2/g), and the 134Cs ions are increasingly irreversibly fixed to the sediment over time. For the first time, stochastic theory has been utilised for sediment-seawater systems to estimate the mean residence times (MRTs) of Cs ions in operationally defined sediment phases described by compartment models. In the present work, two different stochastic models (i) a Markov process model (MP) being analogous to deterministic compartment models, and (ii) a semi-Markov process model (SMP) which should be physically more relevant for inhomogeneous systems, have been compared. As similar results were obtained using the two models, the less complicated MP model was utilised to predict the time needed for an average Cs ion to become irreversibly fixed in the Stepovogo sediments. According the model, approximately 1100 days of contact time between Cs ions and sediments is needed before 50% of the 134Cs ion becomes fixed in the irreversible sediment phase. while about 12.5 years are needed before 99.7% of the Cs ions are fixed. Thus, according to the model estimates the contact time between 137Cs ions leached from dumped waste and the Stepovogo Fjord sediment should be about 3 years before the sediment will act as an efficient permanent sink. Until then a significant fraction of 137Cs should be considered mobile. The stochastic modelling approach provides useful tools when assessing sediment-seawater interactions over time, and should be easily applicable to all sediment-seawater systems including a sink term.     

Irreversible sorption of pentachlorophenol to sediments: experimental observations

The partitioning behavior of pentachlorophenol (PCP) in five sediments was studied using equilibrium sorption experiments and multiple cycles of sorption and desorption experiments. The results of the equilibrium sorption experiments showed that the isotherms of PCP on five sediments were linear and the partitioning coefficients (Kd) were proportional to the organic carbon content of the sediments. The average organic carbon content normalized partitioning coefficient (logK oc) of five sediments was 2.83 +/- 1.48. In multiple cycles of sorption and desorption experiments, the five sediments were found to exhibit statistically significant sorption-desorption hysteresis, and the hysteresis indices (HI) varied over a wide range (0.72 - 11.82). Correlations between the HI value and the percentage of lipid in the total organic matter in the sediment indicated that lipid was the main fraction to affect the hysteresis phenomenon, i.e., the higher the lipid percentage the greater the HI value. The hysteresis phenomenon was mostly caused by irreversible sorption of PCP on lipids, including entrapment by lipids, which induced the slow desorption rate from the sediment. Because of hysteresis in the sorption and desorption, the PCP ecological toxicity would be lower than expected.     

Development and application of an innovative expert decision support system to manage sediments and to assess environmental risk in freshwater ecosystems

With the aim of supporting decision makers to manage contamination in freshwater environments, an innovative expert decision support system (EDSS) was developed. The EDSS was applied in a sediment quality assessment along the Bormida river (NW, Italy) which has been heavily contaminated by an upstream industrial site for more than a century. Sampling sites were classified by means of comparing chemical concentrations with effect-based target values (threshold and probable effect concentrations). The level of each contaminant and the combined toxic pressure were used to rank sites into three categories: (i) uncontaminated (8 sites), (ii) mildly contaminated (4) and (iii) heavily contaminated (19). In heavily contaminated sediments, an environmental risk index (EnvRI) was determined by means of integrating chemical data with ecotoxicological and ecological parameters (triad approach). In addition a sediment risk index (SedRI) was computed from combining chemical and ecotoxicological data. Eight sites exhibited EnvRI values ≥ 0.25, the safety threshold level (range of EnvRI values: 0.14–0.31) whereas SedRI exceeded the safety threshold level at 6 sites (range of SedRI values: 0.16–0.36). At sites classified as mildly contaminated, sublethal biomarkers were integrated with chemical data into a biological vulnerability index (BVI), which exceeded the safety threshold level at one site (BVI value: 0.28). Finally, potential human risk was assessed in selected stations (11 sites) by integrating genotoxicity biomarkers (GTI index falling in the range 0.00–0.53). General conclusions drawn from the EDSS data include: (i) in sites classified as heavily contaminated, only a few exhibited some significant, yet limited, effects on biodiversity; (ii) restrictions in re-using sediments from heavily contaminated sites found little support in ecotoxicological data; (iii) in the majority of the sites classified as mildly contaminated, tested organisms exhibited low response levels; (iv) preliminary results on genotoxicity biomarkers indicate possible negative consequences for humans if exposed to river sediments from target areas.     

Application of a magnetic extraction technique to assess radionuclide-mineral association in Cumbrian shoreline sediments

An assessment has been made of the association of (239+240)Pu, 241Am and 210Po (in secular equilibrium with 210Pb) with iron minerals using a magnetic extraction technique. Grab samples of beach sand from the Cumbrian (UK) coastline were subjected to successive extractions with an approximately 0.1 T ferrite magnet and an approximately 0.3 T rare-earth magnet procedure to separate magnetic iron oxide minerals. Radionuclide concentrations in the magnetic extracts were enhanced (by approximately 4-6-fold) relative to the residue. Those in the approximately 0.1 T magnet extracts were broadly similar to those in the antiferromagnetic material extracted by the approximately 0.3 T magnet, despite the very large differences in magnetic property values between the two fractions (one to two orders of magnitude). The percentage of magnetic material in terms of mass was small and therefore, the majority of these radionuclides (on average 88%) were associated with the residue. Removal of stable Fe was incomplete. Given that the radionuclides may also bind to paramagnetic (nonmagnetic) Fe minerals, the data were extrapolated by normalising the results to quantitative Fe removal. This yielded average values of 37%, 45% and 46% for (239+240)Pu, 241Am and 210Po(210Pb), respectively, as upper limits for the fraction associated with magnetic + nonmagnetic Fe minerals. There are significant uncertainties inherent in quantifying data from this extraction technique. Nevertheless, it seems reasonable to conclude that radionuclide association with Fe minerals is unlikely to have a significant impact upon the physical dispersion of sediment contaminated by Sellafield discharges in the Irish Sea. However, it may be an important factor in governing Pu redox and redissolution behaviour.     

Scavenging of 234Th in the Eastern Irish Sea

Measurements of the disequilibria of ²³⁴Th/²³⁸U in seawater and in suspended particulate and seabed sediment in the eastern Irish Sea reveal that the residence time of dissolved ²³⁴Th (0·5–7·7 days) is controlled by the concentration of particles in suspension (0·4–6·9 mg litre⁻¹, which reflects the rate of sediment resuspension (0·5–5·9 kg m⁻²y⁻¹). The residence time of ²³⁴Th with respect to removal to the seabed is longer (7–50 d) and is less dependent on variations in the suspended load. Anthropogenic sources of ²³⁸U contribute up to 8–15% of the water column production of ²³⁴Th. Enhanced scavenging occurs near the coast and there appears to be a net horizontal flux of ²³⁴Th within this region.