Acute toxicity of zinc and arsenic to the warmwater aquatic oligochaete <Emphasis Type="Italic">Branchiura sowerbyi</Emphasis> as compared to its coldwater counterpart <Emphasis Type="Italic">Tubifex tubifex</Emphasis> (Annelida,Clitellata)

Purpose

This study aimed at evaluating the acute effects of arsenic and zinc to the warmwater aquatic oligochaete Branchiura sowerbyi. Relative sensitivity with the coldwater species Tubifex tubifex was compared. Implications for the use of B. sowerbyi in the risk assessment of sediments in the tropics are discussed.

Materials and methods

Water-only (96 h) and sediment (14 days) toxicity tests were conducted with both species evaluating a concentration series of arsenic and zinc. The tests were conducted considering the environmental conditions in the natural habitat of T. tubifex (predominantly temperate) and B. sowerbyi (predominantly tropical). Both lethal and sublethal endpoints (autotomy of the posterior body parts, abnormal behavior and appearance) were determined in the tests. The lethal (LC₁₀ and LC₅₀) and effect (EC₁₀ and EC₅₀) concentrations were also determined to assess metal sensitivity for both species.

Results and discussion

Both test species were more sensitive to Zn than As in water-only tests, which is in agreement with previous studies evaluating the toxicity of these metals to aquatic oligochaetes. Sublethal effects were generally noted at concentrations lower than those leading to mortality. The warmwater oligochaete B. sowerbyi was more sensitive to both metals tested than the coldwater species T. tubifex.

Conclusions

Study findings support the need for using indigenous tropical species in risk assessments in the tropics. In addition, sublethal effect parameters should be included in toxicity testing with aquatic oligochaetes.

     

Analysis of burrowing ability as a sublethal endpoint in a marine sediment bioassay with Corophium volutator (Pallas)

Purpose

Acute whole-sediment bioassay with the estuarine and marine amphipod Corophium volutator (Pallas) is widely used to assess toxicity of sediments. According to the guidelines DIN EN ISO 16712, mortality is the determined toxic endpoint. Additionally, the reburrowing ability of the surviving organisms of this acute toxicity test in fresh uncontaminated sediment is suggested as the sublethal endpoint, but insufficient information (e.g., exact measurement protocols) on this endpoint is provided, thus confounding factors and the interpretation of the results. The aim of this study was to provide information on burrowing activity as a sublethal endpoint.

Materials and methods

Amphipod tests were carried out in the laboratory, and the burrowing behavior was examined in a size- and gender-specific manner. For sediment testing, only animals of the same size were used in a defined sex ratio because it was found that female animals buried themselves faster than males and that smaller animals burrowed faster than bigger organisms. Statistical analyses were applied to determine whether burrowing time and ability differ significantly between sexes and sizes. Finally, tests were run to discern whether the burrowing ability could be a more sensitive endpoint than mortality.

Results and discussion

When the burrowing ability was examined in toxicity tests with contaminated sediment, the test organisms were affected in a dose-dependent manner. With rising concentrations of the contaminated sediment in a sublethal testing following the sediment exposure over 10 days, fewer animals buried themselves into the sediment.

Conclusions

The burrowing behavior can be used as an additional endpoint. For the tested sediment, burrowing was found to be more sensitive than the mortality. Guidance on the measurement protocol for this additional endpoint was developed. Under the test conditions examined, burrowing ability is an appropriate sublethal endpoint to supplement the toxicity test procedure.     

The use of a microbial contact toxicity test for evaluating cadmium bioavailability in soil

Background, Aims and Scope

Bioavailability of toxic compounds in soil can be defined as the fraction able to come into contact with biota and to cause toxic effects. The contact toxicity tests may detect the total toxic response of all bioavailable contaminants present in a sample. The objectives of this study were to evaluate the use of microbial contact toxicity tests for cadmium bioavailability assessment and to evaluate the relationship between sorption, soil characteristics and cadmium bioavailability.

Methods

A test soil bacterium,Bacillus cereus, was put in direct contact with the solid sample. Four unpolluted soils were selected to provide solid samples with a variety of physicochemical characteristics. The toxicity and sorption behaviour of cadmium spiked to the soil samples were determined.

Results, Discussion and Conclusions

A significant correlation between contact toxicity test results and partitioning of cadmium in the soil samples (r²= 0.79, p <0.05; n = 26) was found. The results confirm that the bioavailability of cadmium in soil depends on its sorption behaviour. Cadmium sorbed to the cation exchange sites associated with fulvic acids is non-bioavailable in the toxicity test employed in this study. It is concluded that the microbial contact toxicity test is a suitable tool for detecting cadmium bioavailablity in the soils used in this study.

Outlook

The application of microbial contact toxicity tests for bioavailability assessment can be very useful for the risk identification and remediation of soil-associated contaminants.     

DanTox—a novel joint research project using zebrafish (Danio rerio) to identify specific toxicity and molecular modes of action of sediment-bound pollutants

Introduction

The European Water Framework Directive aims to achieve a good ecological and chemical status in surface water of European rivers by the year 2015. Since sediments and particulate matter act as secondary sources for pollutants, applied sediment toxicology is perceived to play a major role for obtaining new knowledge that can contribute to successful attainment of the goal. However, the existing bioassays for sediment toxicity analyses do not provide sufficient data concerning bioavailability of environmental pollutants. In this regard, there is an urgent need to combine sediment contact assays with gene expression analysis to investigate mechanism-specific sediment toxicity.

Purpose

The aim of the novel joint research project is to develop a eukaryotic test system, which can be used to investigate the ecotoxicological effects of contaminated sediments on gene expression level (DNA-array and RT-PCR). Current ecotoxicological research customarily involves a battery of bioassays to cover different toxicological endpoints (e.g., teratogenicity, genotoxicity, mutagenicity, Ah-receptor-mediated toxicity, neurotoxicity). In contrast, methods that detect alterations in gene expression offer deeper insight by elucidating how chemical exposure and/or environmental challenge affect multiple metabolic pathways leading to these particular kinds of toxic response. Gene expression profiles reflect the way cells and organisms adapt or respond to a changing environment.

Conclusion

The present project aspires to increase the fundamental molecular and physiological knowledge concerning the mode of action of environmental toxicants in zebrafish (Danio rerio). By working with partners from the academic and research institutions as well as from industry and waterway regulations, the success of this basic research-driven joint project in terms of development and implementation of novel sediment toxicity methods will be realized.     

Toxicity survey of Canadian Arctic marine sediments

Purpose

This paper reports a toxicity survey of Canadian Arctic marine sediments. During the Amundsen scientific cruise, eight sites distributed across the Canadian Arctic and sub-Arctic regions were selected to highlight sensitive areas affected by either atmospheric deposition, ocean current, river drainage, or anthropogenic activities. As part of the Canadian-led ArcticNet research program, this study aims to monitor and to better understand potential changes likely to impact the Arctic.

Materials and methods

Surface sediments were investigated with bioanalytical tests to assess sediment toxicity. Testing of sediment elutriates was undertaken with the ARTOXKIT M, Microtox liquid phase (MLPA), and ROTOXKIT M toxicity assays, while whole sediment testing was carried out with the Microtox solid phase assay (MSPA) toxicity test procedure. Sediment mercury (Hg) content was also determined in each sample since Hg transport and toxicity is specifically an important issue in the Arctic and is generally a key indicator of the pollution status in many aquatic ecosystems.

Results and discussion

Based on bioassay results and sediment granulometric criteria, these Arctic sediments must be considered nontoxic. However, based on MSPA half maximal inhibitory concentrations (IC50s) and/or MLPA threshold effect concentration (TEC) values, some degree of toxicity may be measureable particularly in the sediments located in southern and northeast Hudson Bay. The Hudson Bay watershed drains 30% of Canadian rivers and extends to northern USA. Despite the large Hg concern in the Arctic, the input of local or long-range Hg sources does not appear to be a contributing factor to sediment toxicity.

Conclusions

These initial results are valuable in that they set baseline quality levels for these sediments as of 2005. As such, future comparisons can be made to assess temporal and spatial trends. Human activity and climate change is expected to impact these regions in the future, resulting in further reduction of sea ice extent, access to new Arctic seaways, and drilling associated with the exploitation of natural resources.     

The impact of extraction methodologies on the toxicity of sediments in the zebrafish (Danio rerio) embryo test

Purpose

Traditionally, methods for sediment extractions are characterised using chemical analyses. However, in order to evaluate sediment extracts with regard to biological effects and, thus, bioaccessibility, extraction methods have to be compared to effect data obtained from experiments with in situ exposure scenarios, i.e., sediment contact tests. This study compares four extraction methods and sediment contact test data from a previous project with respect to predictive power in the fish embryo test with zebrafish (Danio rerio).

Materials and methods

A natural and an artificial sediment spiked with a mixture of six organic pollutants (2,4-dinitrophenol, diuron, fluoranthene, nonylphenol, parathion and pentachlorophenol) were extracted using (a) membrane dialysis extraction (MDE), (b) a Soxhlet procedure, (c) hydroxypropyl-??-cyclodextrin (HPCD) or (d) Tenax^®-TA. Whereas the former two are regarded being exhaustive with respect to non-covalently bound contaminants, the latter two are considered to predict bioaccessibility. Resulting extracts were tested in the fish embryo assay with D. rerio for embryotoxic and teratogenic potential.

Results and discussion

Mortalities caused by organic extracts from Soxhlet extraction and MDE were high. However, HPCD extracts turned out to be at least as effective as extracts obtained with these two methods. One possible reason might be short ageing time of the spiked sediments. Only Tenax^®-TA extracts gave results comparable to the sediment contact assay for natural sediment, but revealed low reproducibility. Significant differences between natural and artificial sediment were found for extracts obtained with techniques using native (i.e., non-freeze-dried) sediments, i.e., HPCD and Tenax^®-TA. In contrast, MDE and Soxhlet extracts used freeze-dried sediment and did not differentiate between natural and artificial sediment. Therefore, freeze-drying has likely altered and equalised sediment properties that influence accessibility, such as composition of bacterial communities and organic matter quality.

Conclusions

Four extraction methods were successfully characterised with respect to their stringency and predictiveness for bioaccessibility. MDE was confirmed as an alternative to Soxhlet extraction. High mortalities induced by HPCD extracts underline the need to include ageing into consideration when assessing sediments. Although Tenax^®-TA may basically be used to predict bioaccessibility in the fish embryo test, the high variability observed warrants further investigation of the relation between effect and extractability. Apparently, freeze-drying can severely affect sediment properties, potentially eliminating individual properties of natural sediments.     

Evaluating the necessity for thermal treatment in clay-based metal immobilization techniques as an environmentally acceptable sediment remediation process

Purpose

The objective of this research was to apply the same immobilization (stabilization/solidification) clay-based treatments to sediment contaminated with different metals (Pb, Cd, Ni, Zn, Cu, Cr) with different distributions and availabilities in sediment. We also examined the possibility of using clay as an immobilization agent without the application of thermal treatment, in order to reduce the economic cost of this expensive remediation procedure.

Materials and methods

Clay from a canal in Vojvodina, Republic of Serbia, was used as the immobilization agent in a stabilization/solidification treatment to remediate metal-contaminated sediment. Semi-dynamic and toxicity characteristic leaching tests were conducted to assess the effectiveness of the nonthermal and thermal immobilization treatments with clay, and the long-term leaching behavior of these metals was determined using the following parameters: cumulative percentage of metals leached; diffusion coefficients; leachability indices; and toxicity characteristic leaching test concentration.

Results and discussion

Based on these parameters, both clay-based treatments were effective in immobilizing metals in the contaminated sediment. Results suggest that both heating temperature and clay proportion in the sediment–clay mixture impact the degree of metal immobilization.

Conclusions

Clay-based products are potentially good immobilization materials for metal-contaminated sediments, with the distribution of metals in the original sediment not influencing the efficacy of the treatments. Even without the thermal treatment, the metals were effectively immobilized. The leaching of metals was largely inside the regulatory limits and the treated samples can be regarded as nonhazardous materials. This justifies the choice of not applying the more expensive thermal treatment during remediation, especially when treating sediments containing a mixture of pollutants.     

Ecotoxicological risk assessment of a quarry filling with seaport sediments using laboratory freshwater aquatic microcosms

Purpose

In France, contaminated seaport sediments cannot be discharged into the sea according to recent regulation. Hence, they must be managed on land. Among the solutions identified, that of filling terrestrial quarries located in the littoral zone is one of the most promising. However, this requires developing a methodology for ecological risk assessment; which was the aim of the SEDIGEST research program. In the present study, we report the results of toxicological impacts of three sediments on aquatic ecosystems close to a quarry. These results were used to formulate a risk assessment methodology.

Materials and methods

The ecotoxicological approach was based on laboratory microcosm assays applied to leachates obtained from the sediments. The microcosms contained synthetic water and sediment and five pelagic (micro-algae, duckweeds and daphnids) and benthic (chironomids and amphipods) freshwater species. The biota were exposed for 3 weeks to a range of leachate concentrations; metals were monitored in the water column and the effects (i.e. mortality, growth inhibition and midge emergence) were measured.

Results and discussion

The results showed an absence of acute toxicity at concentrations of <10% (v/v) but sublethal effects for concentrations between 1 and 10%. Given the complex nature of the leachates, it was difficult to determine the factors of toxicity. Metals, especially Cu, might have been responsible for some of the effects on the amphipods.

Conclusions

Future quarries filled with seaport sediments might emit pollutants to aquatic ecosystems in their vicinity, and risk assessors should ensure that predicted environmental concentrations of leachates are below the maximum leachate concentration acceptable for the whole ecosystem; for example, by multiplying the concentration safe for the microcosm organisms by a factor of 10.     

Assessing the risk of a 50-year-old dump site in the Baltic Sea by combining chemical analysis, bioaccumulation, and ecotoxicity

Purpose

During the late 1950s and early 1960s, industrial waste material highly enriched with various contaminants (e.g., heavy metals, polycyclic aromatic hydrocarbons (PAHs)) was dumped in the inner Bay of Mecklenburg, western Baltic Sea. Between 2002 and 2004, a research program was initiated using chemical analysis in combination with bioanalytical techniques to assess the extent and variability in contamination at this dump site (DS). The data were compared to a reference area (RS) with similar environmental conditions, which is representative of the western Baltic Sea.

Materials and methods

Twelve PAHs were investigated to assess their ecological hazard, as they were identified as major pollutants in the dumped material. In addition to analyzing the actual PAH contamination status in the sediments, PAHs measured in the soft tissue of Arctica islandica were also used as an indicator of contaminant bioaccumulation. A biotest battery was applied to determine the toxic effects of contaminants in the sediment.

Results and discussion

Significantly elevated PAH concentrations (sum of 12 PAHs) of ～3,000 ng g^?1 dw and higher bioaccumulation factors (BAFs) were determined in the soft body tissue of A. islandica collected at DS (t test, p?=?0.025). The results also showed that the sediment PAH contamination was significantly higher at DS (1,952–5,466 ng g^?1 dw) than at RS (1,384–2,315 ng g^?1 dw). The results revealed a major heterogeneity in the PAH concentration at DS due to an attempt to cover the toxic material with clean clay. This resulted in a more heterogeneous distribution of the dump material rather than covering it up completely. However, not all relevant contaminants were included in this study, not only because it is too costly to determine them all but also because unidentified contaminants present at concentrations below the limit of detection cannot be measured. Bioassays were used to fill this gap in the hazard assessment in a cost-effective way by investigating the possible effects of sediment contamination on benthic organisms. The results showed a high variability and magnitude of growth and luminescence inhibition. Bacterial contact tests with marine organisms showed a high toxicity response (>80 % inhibition) from DS sediments. In contrast, the luminescent bacteria test (Vibrio fischeri) showed equivalent effects of sediments from both DS and RS.

Conclusions

The spatial distribution of toxicity in DS, the bioaccumulation in mussels and the analytical evidence of PAH pollution clearly show that the dumped material still represents a potential risk even after 60 years.     

The use of <Emphasis Type="Italic">Daphnia magna</Emphasis> immobilization tests and soil microcosms to evaluate the toxicity of dredged sediments

Purpose  

This paper evaluates the feasibility of using the buffering capacity of natural soil for the remediation of dredged material before being disposed in soil landfills. To achieve that, an Integrated Soil Microcosms (ISM) system was designed to produce elutriates and leachates from the sediment/soil percentage mixtures. Furthermore, to investigate the biological effects of the contaminated sediments, the toxicity behavior of leachates and elutriates was assessed and compared by performing acute (48 h) toxicity assays with the cladoceran Daphnia magna as test organism.     

Sublethal effects of contaminated sediment on Arenicola marina

Purpose

The highest concentrations of environmental contaminants are generally found in marine sediments, and there is a need for knowledge concerning how and whether they affect sediment-dwelling organisms. This study aimed to assess sublethal effects in Arenicola marina exposed to two sediments from a contaminated fjord and two reference locations with different sediment characteristics.

Materials and methods

Duplicate contaminated sediments were used to investigate the robustness of current protocols for sediment testing. The two reference sediments, with different grain sizes and total organic carbon, were collected from the outer Oslofjord and the two contaminated sediments from Frierfjord. Polychaetes were exposed in quadruplicate sediment microcosms and sampled after 1, 2, 4 and 8?weeks of exposure. Oxidative stress resistance (total oxyradical scavenging capacity, TOSC) and components comprising the energy budget (cellular energy allocation, CEA) were determined for individual polychaetes.

Results and discussion

Arenicola maintained and increased body weights over the initial 4?weeks of exposure in all groups, except in one reference sediment (Elle). There were no differences between treatments in the scavenging capacity (TOSC). The most striking difference in how polychaetes partitioned energy resources was a difference in lipid and carbohydrate allocations for Arenicola held in the contaminated sediments over the initial weeks. Cellular respiration appeared to increase in polychaetes held in the Elle sediment and decreased for polychaetes held in the two Frierfjord sediments by weeks?4 and 8. In the overall CEA, this was offset by increased energy per weight stored in the Elle group, which resulted in an overall positive CEA for polychaetes held in that sediment, whereas polychaetes in the other treatments were close to neutral. Although CEA would thus indicate that Elle polychaetes had good health status, their body weight also decreased significantly over the experimental period compared to other treatments, indicating an overall negative effect.

Conclusions

This study has shown the importance of sediment characteristics when evaluating toxicity and how resource allocation can differ dramatically over a short time span in polychaetes held in similarly contaminated sediments. There were no clear effects of sediment contamination on CEA or TOSC in the polychaete A. marina. The findings are relevant for the design of both short- and long-term sediment studies.     

Comparison of approaches towards ecotoxicity evaluation for the application of dredged sediment on soil

Purpose

The toxicity of 36 dredged sediments from the Czech Republic was investigated using a large battery of bioassays. The aim of this study was to investigate the feasibility of ecotoxicity testing in general and of individual bioassays more specific and to investigate how the results of bioassays are determined by the physicochemical properties of sediment samples and/or sediment contamination.

Material and methods

In 2008 and 2010, 36 sediment samples were collected from rivers and ponds and from sediment heaps in different parts of the Czech Republic. Both their physicochemical properties and their levels of contamination with POPs and heavy metals were analyzed. The ecotoxicities of the sediments were evaluated using the four bioassays from the new Czech directive 257/2009 Coll. concerning the application of dredged sediments on agricultural land (Enchytraeus crypticus reproduction, Folsomia candida reproduction, Lactuca sativa root elongation, and potential ammonium oxidation). The results of the four directive bioassays were compared with the results of other soil bioassays (Caenorhabditis elegans mortality, Eisenia fetida avoidance and reproduction) and eluate bioassays (Daphnia magna immobilization, Pseudokirchneriella subcapitata growth inhibition test, and Vibrio fischeri luminescence).

Results and discussion

We demonstrate that the battery suggested in Czech directive 257/2009 Coll. is highly effective in identifying toxic samples; these bioassays clearly revealing different types of toxicity and different exposure routes. Shorter alternative bioassays may be added especially when fast toxicity identification is needed. Eluate bioassays identified samples potentially hazardous to aquatic ecosystems. Their inclusion into the assessment scheme should be considered if the goal of assessment is also the protection of aquatic ecosystems. The results of our multivariate analysis show that specific physicochemical properties and contamination may affect bioassay responses. C. elegans was the most sensitive bioassay to physicochemical properties and also to organic contamination, while eluate bioassays were sensitive to heavy metal pollution.

Conclusions

Most effects detected by the bioassays could not be explained by the levels of toxicants measured or by the natural characteristics of sediments. Our results show that bioassays are irreplaceable in dredged sediment risk assessment because they complement information provided by chemical analyses.     

Integrated toxicity evaluation of a pulp deposit using organisms of different trophic levels

Purpose

In order to assess possible adverse effects originating from pulp deposits in a Swiss lake, a sediment quality triad approach was applied with chemical, ecotoxicological and ecological assessment methods.

Materials and methods

To obtain an integrative picture of the potential ecotoxicological effects on organisms of different trophic levels, four test procedures were applied. The acute effects of pulp deposit pore water on a decomposer, the amphipod Gammarus fossarum, were monitored. Chronic toxicity of the pore water was evaluated on primary producers via a growth inhibition test with unicellular green algae (Pseudokirchneriella subcapitata) and on secondary consumers in a reproduction test with the water flea Ceriodaphnia dubia. To evaluate the effects of the pulp deposit on sediment inhabitants, a whole-life-cycle test with the non-biting midge Chironomus riparius was undertaken. Chemical assessment included dissolved organic carbon, extractable organic halogenic compounds, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and heavy metals. The composition of the macrozoobenthos community was analysed in order to assess the ecological effects.

Results and discussion

G. fossarum displayed increased locomotor activity at 12.5% but not at 25% sample concentration during a short-time exposure of 20 h. Chronic effects compromised the reproduction and growth of C. dubia (lowest observed effect concentration, 12.5% sample concentration) with zero population growth in 100% pulp deposit pore water. In 100% pulp deposit, C. riparius exhibited increased mortality at 10 and 17 days after oviposition. Pulp deposits of 50% and 100% concentration caused a significantly lower emergence compared with the reference treatments (lake sediment and quartz sand). Additionally, the locomotor activity of chironomids decreased significantly in 25–100% pulp deposit. No chronic effects of pulp deposit pore water on algae photosynthesis and growth could be detected. The bioassay results were in accordance with an elevated content of PAHs, PCBs and metals in the pulp deposit. Significantly more organisms known to be tolerant to organic pollution were present within the macrozoobenthos community.

Conclusions

In general, for sediment inhabitants such as chironomids, the pulp deposit has to be classified toxic. In the present test setup, the toxicity of the pulp deposit was reflected better by the chronic test systems applied than by the acute ones. The applied testing framework could be a suitable tool to assess the risk of contaminated sites, and this information will help decide whether risk mitigation measures should be taken. In addition, with a similar approach, the success of any mitigation measures taken can be assessed.     

Residual leachability of CCA-contaminated soil after treatment with biodegradable chelating agents and lignite-derived humic substances

Purpose

The aim of this study was to enhance the soil remediation of timber treatment sites; the potential application of biodegradable chelating agents and humic substances as enhancing agents was assessed in terms of the residual leachability of chromium, copper and arsenic (CCA).

Materials and methods

This study applied four leachability tests on a field-contaminated soil after 48-h washing with ethylenediamine-N,N-disuccinic acid (EDDS), glutamic-N,N-diacetic acid, ethylenediaminetetraacetic acid and humic substances derived from lignite and two other sources.

Results and discussion

It was noteworthy that the reduction in the total metal concentrations after soil washing was not predictive of the leaching behaviour. When assessed by toxicity characteristic leaching procedure (TCLP) and waste extraction test (WET), Cu and As leachability was decreased as a result of their extraction by soil washing. By contrast, when assessed by synthetic precipitation leaching procedure (SPLP) and European Council Waste Acceptance Criteria (ECWAC) tests, Cu and As leachability was found to increase, probably because the effect of destabilization of residual metals during soil washing was more observable in unbuffered leaching solutions. On the other hand, Cr leachability was acceptably low in TCLP and WET but still exceeded drinking water standard in SPLP and ECWAC tests.

Conclusions

The three chelating agents were able to meet the criteria for Cu in all leachability tests, while the limits of As concentrations could only be met by EDDS in TCLP test. The three humic substances reduced the leachate concentrations of Cu and As without destabilizing the residual metals; however, the reduction was insufficient to meet the required limits in all leachability tests considered.     

The dioRAMA project: assessment of dioxin-like activity in sediments and fish (Rutilus rutilus) in support of the ecotoxicological characterization of sediments

Introduction

Given the complex interactions of re-suspension processes and bioavailability of sediment-bound pollutants such as dioxin-like chemicals, there is need for a better integrative understanding of the cause–effect relationship of these pollutants. Currently, the majority of studies investigating potential risks of these chemicals only focus on characterizing sediment extracts via in vitro bioassays, thereby disregarding bioavailability, uptake, metabolism, and elimination rates of these compounds in vivo. To determine to which extent mechanism-specific effects in vitro reflect possible adverse effects in vivo, the research project dioRAMA, involving partnership between the Institute for Environmental Research of RWTH Aachen University and the Department Biochemistry/Ecotoxicology of the German Federal Institute of Hydrology, was established.

Methods

Animals from an elevated trophic level—common roach (Rutilus rutilus)—will be exposed to sediments from two major German rivers. Exposure will be performed in a system that enables a concurrent monitoring of environmental parameters. In parallel, in vitro studies will be conducted to determine dioxin-like potentials of sediment and fish extracts from the in vivo exposure experiments using different cell lines with varying endpoints. Moreover, extract fractionation procedures, using the strategy of effect-directed analysis, will enable the detection of specific contaminant groups responsible for the biological activity observed.

Conclusion

A closer interconnection between applied ecotoxicological science and regulatory needs will facilitate the improved assessment of dioxin-like compounds in sediment and biota. Consequently, this will enable their application in sediment management programs, which is one of the main goals of the dioRAMA project.     

A combined hydraulic and toxicological approach to assess re-suspended sediments during simulated flood events. Part I–multiple biomarkers in rainbow trout

Purpose

One of the central issues related to global changes in weather is the increasing occurrence of flood events that can result in the re-suspension of contaminated sediments in rivers. Here, we report on a proof-of-concept study combining hydraulic engineering and ecotoxicology in a new interdisciplinary approach to assess the toxicity of re-suspended polluted sediments after a simulated flood event.

Materials and methods

Rainbow trout (Oncorhynchus mykiss) were exposed for 5 days under simulated flood conditions in an annular flume with artificial sediments that were spiked with a mixture of polycyclic aromatic hydrocarbons (PAH) at environmentally relevant concentrations. Specifically, the objective of this study was to bridge the gap between the physical re-suspension of pollutants and resulting toxicological impacts on aquatic organisms. A suite of different molecular, biochemical and histological markers was used to test the hypothesis that re-suspension of sediments can lead to re-mobilization of PAHs and subsequently to effects on aquatic organisms.

Results and discussion

The micronucleus frequency was significantly 4.3-fold elevated after exposure. There was no significant indication of Aryl hydrocarbon receptor signaling (no EROD induction or increased CYP1A protein content, only slight induction of CYP1A gene expression). Biliary metabolite concentration was the most sensitive marker of PAH exposure. Results for other biomarkers (glutathione-S-transferase, catalase and lipid peroxidation) were inconclusive.

Conclusions

In combination with chemical analyses of suspended matter, the presented approach will be used to improve understanding of the re-mobilization of pollutants from sediments in support of environmental risk assessment.     

An innovative stabilization/solidification treatment For contaminated soil remediation: demonstration project results

Background, aim, and scope

An innovative stabilization/solidification (S/S) process using high-performance additivated concrete technology was developed for remediating soil contaminated by metals from abandoned industrial sites. In order to verify the effectiveness of this new ex situ S/S procedure, an area highly contaminated by metallic pollutants (As, Cd, Hg, and Pb), due to the uncontrolled discharge of waste generated from artistic glass production on the island of Murano (Venice, Italy), was selected as a case study. The technique transforms the contaminated soil into an aggregate material suitable for reuse as on-site backfill. This paper reports the main results of the demonstration project performed in collaboration with the local environmental protection agency (ARPAV).

Materials and methods

An ex situ treatment for brownfield remediation, based on the transformation of contaminated soil into very dense, low porous, and mechanically resistant granular material, was set up and tested. Specific additives (water reducers and superplasticizers) to improve the stabilized material properties were developed and patented. A demonstration plant assembled on the study area to treat 6 m³ h^–1was then tested. After excavation, the contaminated soil was screened to remove coarse material. The fraction Ø?>?4 mm (coarse fraction), mainly composed of glass, brick, concrete, and stone debris, was directly reused on site after passing through a washing treatment section. The highly polluted fraction Ø?≤?4 mm (fine fraction) was treated in the S/S treatment division of the plant (European patent WO/2006/097272). The fine fraction was mixed with Portland cement and additives defined on the basis of the high performance concrete technique. the mixture was then granulated in a rolling-plate system. After 28 days curing in an onsite storage area to allow for cement hydration, the stabilized material was monitored before its in situ relocation. The chemical, mechanical, and ecotoxicological reliability and performance of the treatment was checked. Metal leachability was verified according to four leaching test methods: Italian Environmental Ministry Decree (1998), EN 12457 (2002) tout court, amended only with MgSO₄ and, lastly, with artificial sea water. The mechanical properties were measured according to BS (1990) and AASHTO (1999) to obtain the Aggregate Crushing Value and California Bearing Ratio, in that order. Moreover, leachate samples prepared with artificial seawater were assessed via the Crassostrea gigas embryotoxicity test and Vibrio fischeri bioluminescence inhibition test to discriminate the presence of potential ecotoxicological effects for the brackish and saltwater biota.

Results

Outcomes from all leachate samples highlighted the effectiveness of the remediation treatment, fully complying with the Italian legislation for non-hazardous material reuse under a physicochemical viewpoint. The stabilized granular material demonstrated high mechanical strength, low porosity, and leachability. Moreover, ecotoxicological surveys indicated the presence of low toxicity levels in leachate samples according to both toxicity tests.

Discussion

Remediated soil samples revealed a significant decrease in leachability of heavy metals as a consequence of the application of additivated cement that enhanced granular material properties, resulting in improved compactness due to the reduction in water content. The toxicity data confirmed this state-of-the-art technique, indicating that leachates could be deemed as minor acutely toxic.

Conclusions

The proposed S/S treatment proved to be able to remediate soil contaminated by heavy metals through trapping pollutants in pellet materials presenting adequate physicochemical, mechanical, and ecotoxicological properties in order to prevent leachability phenomena, their reclamation, and reuse being made easier by its granular form.

Recommendation and perspectives

This project foresees long-term monitoring activity over several years (until 2014) to consider treatment durability.     

Applying a GLM-based approach to model the influence of soil properties on the toxicity of phenmedipham to Folsomia candida

Purpose

Soil properties are the main explanation to the different toxicities obtained in different soils due to their influence on chemical bioavailability and the test species performance itself. However, most prediction studies are centred on a few soil properties influencing bioavailability, while their direct effects on test species performance are usually neglected. In our study, we develop prediction models for the toxicity values obtained in a set of soils taking into account both the chemical concentration and their soil properties.

Materials and methods

The effects on the avoidance behaviour and on reproduction of the herbicide phenmedipham to the collembolan Folsomia candida is assessed in 12 natural soils and the Organisation for Economic Co-operation and Development (OECD) artificial soil. The toxicity outcomes in different soils are compared and explanatory models are constructed by generalised linear models (GLMs) using phenmedipham concentrations and soil properties.

Results and discussion

At identical phenmedipham concentrations, the effects on reproduction and the avoidance response observed in OECD soil were similar to those observed in natural soils, while effects on survival were clearly lower in this soil. The organic matter and silt content explained differences in the avoidance behaviour in different soils; for reproduction, there was a more complex pattern involving several soil properties.

Conclusions

Our results highlight the need for approaches taking into account all the soil properties as a whole, as a necessary step to improve the prediction of the toxicity of particular chemicals to any particular soil.     

Ecotoxicological evaluation of Harbour sediments using marine organisms from different trophic levels

Background, Aim and Scope  The toxicity of contaminated sediments should be evaluated considering the direct exposure of laboratory organisms to whole sediments and the indirect exposure to elutriates or extracts (Tay et al. 1992, Byrne and Halloran 1999, Nendza 2002). The alga Dunaliella tertiolecta is indicated for the use in toxicity bioassays because it is highly sensitive to several xenobiotics. Harpacticoid copepods have been already used for toxicity testing and Tigriopus fulvus is a promising Mediterranean target-species in ecotoxicology (Todaro et al. 2001, Faraponova et al. 2003, Pane et al. 2005a). In this study, the toxicity of sediments collected in harbour sites of the Northeastern Adriatic Sea was evaluated by growth inhibition test with free living and alginate-immobilized Dunaliella tertiolecta and acute toxicity test with nauplii and adult Tigriopus fulvus with the aim of pointing out the importance to utilize model organisms from different trophic levels in sediment ecotoxicology. Methodology  Elutriates and whole sediments were tested on free living and immobilized (Pane et al. 1998) algal cells, and on laboratory reared copepods. Free-living D. tertiolecta were exposed to diluted elutriates in a static, multi-well plate system. Naalginate immobilized D. tertiolecta were placed in polystyrene inserts fitted with polyester mesh bottoms and exposed to a thin layer (2 mm) of whole sediments in multi-well plates (EPS 1992, Pane and Bertino 1999). Toxicity tests with copepods were carried out on Tigriopus fulvus nauplii (elutriates) and adults (whole sediments and elutriates). Same-aged nauplii useful for toxicity tests were obtained by egg sac detaching and consequent hatching stimulation (Pane et al. 2006). Newborn nauplii (I–II stage) were exposed to elutriates in multi-well plates provided with polystyrene inserts. Adult T. fulvus maintained in polystyrene inserts fitted with polyester mesh bottoms were placed in contact with a thin layer (2 mm) of whole sediment placed on multi-well plate bottoms. All end-points were evaluated after 96 h. Results  In general, the effects increased with the increasing of elutriate concentration up to 50%; the stimulation or inhibition of algal growth was statistically significant in comparison to the control. The inhibiting elutriates induced EC₅₀ variations of algal growth ranging from 66.9% to 74.3%. The mortality of T. fulvus nauplii was always < 25% after treatment with 100% elutriates and < 10% after treatment with 50% dilution; no effect was shown up with 25% dilution; therefore LC₅₀ was not calculable. The effect of elutriates was negligible on adult copepods and LC₅₀ values were never calculable; percent mortality always resulted in < 10% after treatment with whole sediments. Discussion  Both experimental systems gave substantially similar results after exposition to whole sediments and elutriates. During the experiment with algal cells, the immobilization in Na-alginate and the employment of inserts which allowed the contact of organisms with sediments and their easy counting were particularly useful. Likewise, the employment of inserts of adequate mesh size in the tests with copepods allowed the contact of organisms with the sediment and made organism handling and counting easy, as well as the evaluation of mortality. The methodology here described and the utilization of the proposed test-species could have an importance also considering that the current trend in ecotoxicological research is towards finding the most appropriate organism for specific areas of concern by using indigenous species (Mariani et al. 2006) and towards the major significance of chronic and reproductive end-points. Conclusions  Based on the above results, it can be stated that the bioassay with Dunaliella tertiolecta could be a good estimation tool for the ecotoxicological assessment of marine sediments. The immobilization of algae in Na-alginate was seen to be useful to evaluate the toxicity of whole sediments; the employment of polystyrene inserts allowed an improvement of the procedures. T. fulvus nauplii and adults, as other harpacticoids such as Tigriopus japonicus (Yoon et al. 2006), satisfy the basic criteria for the employment of a standard species in marine bioassays. To date only pelagic Acartia tonsa are utilized in the standardized procedure to evaluate the risk assessment of chemicals or wastewaters (ISO 1999). As, on the contrary, the exposure of copepods to solid-phase contaminants it is not yet standardized, the employment of polystyrene inserts improved the procedures for T. fulvus too. So, the rapidity and the possibility to solve practical problems could be the main attractive features of this technique (Pane et al. 2005a) when applied to whole sediments. Recommendations and Perspectives  The methodology here developed being also applicable to long term and reproduction tests should be recommended because it provides relevant information in comparison with other frequently applied, standardized biotests with crustaceans (ISO 1999). The procedure has been shown to be easily applicable to selected marine organisms. ESS-Submission Editor: Prof. Dr. Henner Hollert (henner.hollert@bio5.rwth-aachen.de)