Inputs of disinfection by-products to the marine environment from various industrial activities: Comparison to natural production.

Oxidative treatment of seawater in coastal and shipboard installations is applied to control biofouling and/or minimize the input of noxious or invasive species into the marine environment. This treatment allows a safe and efficient operation of industrial installations and helps to protect human health from infectious diseases and to maintain the biodiversity in the marine environment. On the downside, the application of chemical oxidants generates undesired organic compounds, so-called disinfection by-products (DBPs), which are discharged into the marine environment. This article provides an overview on sources and quantities of DBP inputs, which could serve as basis for hazard analysis for the marine environment, human health and the atmosphere. During oxidation of marine water, mainly brominated DBPs are generated with bromoform (CHBr3) being the major DBP. CHBr3 has been used as an indicator to compare inputs from different sources. Total global annual volumes of treated seawater inputs resulting from cooling processes of coastal power stations, from desalination plants and from ballast water treatment in ships are estimated to be 470-800 × 109 m3, 46 × 109 m3 and 3.5 × 109 m3, respectively. Overall, the total estimated anthropogenic bromoform production and discharge adds up to 13.5-21.8 × 106 kg/a (kg per year) with contributions of 11.8-20.1 × 106 kg/a from cooling water treatment, 0.89 × 106 kg/a from desalination and 0.86 × 106 kg/a from ballast water treatment. This equals approximately 2-6% of the natural bromoform emissions from marine water, which is estimated to be 385-870 × 106 kg/a.

The potential for dispersant use as a maritime oil spill response measure in German waters.

In case of an oil spill, dispersant application represents a response option, which enhances the natural dispersion of oil and thus reduces coating of seabirds and coastal areas. However, as oil is transferred to the water phase, a trade-off of potential harmful effects shifted to other compartments must be performed. This paper summarizes the results of a workshop on the current knowledge on risks and benefits of the use of dispersants with respect to specific conditions encountered at the German sea areas. The German North Sea coast is a sensitive ecosystem characterised by tidal flats, barrier islands and salt marshes. Many prerequisites for a potential integration of dispersants as spill response option are available in Germany, including sensitivity maps and tools for drift modelling of dispersed and undispersed oil. However, open scientific questions remain concerning the persistence of dispersed oil trapped in the sediments and potential health effects.

Dry bulk cargo shipping - An overlooked threat to the marine environment?

Approximately 9.5billiontonnes of goods is transported over the world oceans annually with dry bulk representing the largest cargo group. This paper aims to analyse whether the transport and associated inputs of dry bulks into the sea create a risk for the marine environment. For this purpose, we analyse the international regulatory background concerning environmental protection (MARPOL), estimate quantities and identify inputs of such cargoes into the oceans (accidental and operational), and use available information for hazard assessment. Annually, more than 2.15milliontonnes of dry bulk cargoes are likely to enter the oceans, of which 100,000tonnes are potentially harmful to the marine environment according to the definition included in draft maritime regulation. The assessment of the threat to the marine environment is hampered by a lack of available information on chemical composition, bioavailability and toxicity. Perspectives for amendments of the unsatisfying pollution prevention regulations are discussed.

Exploration of Daphnia behavioral effect profiles induced by a broad range of toxicants with different modes of action.

Behavior is increasingly reported as a sensitive and early indicator of toxicant stress in aquatic organisms. However, the systematic understanding of behavioral effects and comparisons between effect profiles is hampered because the available studies are limited to few chemicals and differ in the exposure conditions and effect parameters examined. The aims of the present study were 1) to explore behavioral responses of Daphnia magna exposed to different toxicants, 2) to compare behavioral effect profiles with regard to chemical modes of action, and 3) to determine the sensitivity and response time of behavioral parameters in a new multi-cell exposure system named Multi-DaphTrack compared with currently utilized tests. Twelve compounds covering different modes of toxic action were selected to sample a wide range of potential effect profiles. Acute standard immobilization tests and 48 h of behavioral tracking were performed in the customized Multi-DaphTrack system and a single-cell commercialized biological early warning system. Contrasting behavioral profiles were observed for average speed (i.e., intensity, time of effect onset, effect duration), but no distinct behavioral profiles could be drawn from the chemical mode of action. Most compounds tested in the Multi-DaphTrack system induced an early and significant average speed increase at concentrations near or below the 10% effective concentration (48 h) of the acute immobilization test, demonstrating that the Multi-DaphTrack system is fast and sensitive. To conclude, behavior endpoints could be used as an alternative or complement to the current acute standard test or chemical analysis for the predictive evaluation of ecotoxic effects of effluents or water bodies.

Organic chemicals jeopardize the health of freshwater ecosystems on the continental scale.

Organic chemicals can contribute to local and regional losses of freshwater biodiversity and ecosystem services. However, their overall relevance regarding larger spatial scales remains unknown. Here, we present, to our knowledge, the first risk assessment of organic chemicals on the continental scale comprising 4,000 European monitoring sites. Organic chemicals were likely to exert acute lethal and chronic long-term effects on sensitive fish, invertebrate, or algae species in 14% and 42% of the sites, respectively. Of the 223 chemicals monitored, pesticides, tributyltin, polycyclic aromatic hydrocarbons, and brominated flame retardants were the major contributors to the chemical risk. Their presence was related to agricultural and urban areas in the upstream catchment. The risk of potential acute lethal and chronic long-term effects increased with the number of ecotoxicologically relevant chemicals analyzed at each site. As most monitoring programs considered in this study only included a subset of these chemicals, our assessment likely underestimates the actual risk. Increasing chemical risk was associated with deterioration in the quality status of fish and invertebrate communities. Our results clearly indicate that chemical pollution is a large-scale environmental problem and requires far-reaching, holistic mitigation measures to preserve and restore ecosystem health.

Inter-laboratory trial of a standardized sediment contact test with the aquatic plant Myriophyllum aquaticum (ISO 16191).

A whole-sediment toxicity test with Myriophyllum aquaticum has been developed by the German Federal Institute of Hydrology and standardized within the International Organization for Standardization (ISO; ISO 16191). An international ring-test was performed to evaluate the precision of the test method. Four sediments (artificial, natural) were tested. Test duration was 10 d, and test endpoint was inhibition of growth rate (r) based on fresh weight data. Eighteen of 21 laboratories met the validity criterion of r ≥ 0.09 d(-1) in the control. Results from 4 tests that did not conform to test-performance criteria were excluded from statistical evaluation. The inter-laboratory variability of growth rates (20.6%-25.0%) and inhibition (26.6%-39.9%) was comparable with the variability of other standardized bioassays. The mean test-internal variability of the controls was low (7% [control], 9.7% [solvent control]), yielding a high discriminatory power of the given test design (median minimum detectable differences [MDD] 13% to 15%). To ensure these MDDs, an additional validity criterion of CV ≤ 15% of the growth rate in the controls was recommended. As a positive control, 90 mg 3,5-dichlorophenol/kg sediment dry mass was tested. The range of the expected growth inhibition was proposed to be 35 ± 15%. The ring test results demonstrated the reliability of the ISO 16191 toxicity test and its suitability as a tool to assess the toxicity of sediment and dredged material.

Bioavailability of copper in contaminated sediments assessed by a DGT approach and the uptake of copper by the aquatic plant Myriophyllum aquaticum.

The assessment of the potentially harmful effects of metals on biota depends on the speciation and bioavailability of the metals. In the present study, the authors investigated Cu accumulation and toxicity in the aquatic plant Myriophyllum aquaticum after exposure to artificial sediments varying in peat or ferric hydroxide content and spiked with Cu (5-200 mg kg(-1)). Modeling of the kinetic diffusive gradient in thin film (DGT) measurements revealed fast and slow Cu resupply from the solid phase for sediment formulated with and without peat, respectively. Myriophyllum aquaticum proved to be sensitive to Cu, as the Cu accumulation and growth differed depending on the sediment composition and Cu concentration. Comparing the Cu accumulation in M. aquaticum with total dissolved concentration, free concentration, and concentration in solution derived from DGT measurements (CDGT), Cu concentrations revealed that CDGT concentrations were a better predictor of accumulation than the others. However, the relatively weak correlation observed (r(2) = 0.6) and the fact that plant uptake does not increase proportionally to DGT fluxes suggest that Cu uptake in plants was not diffusion limited. Thus, the free Cu concentrations near the root surface were sufficient to meet the plant's demand during the experiment. Furthermore, labile complexes that continuously resupply the Cu(2+) pool may also contribute to the concentrations available for plant uptake. In the range of Cu concentrations investigated in the present study, saturation of uptake processes as well as toxicity are considered responsible for the poor DGT prediction of plant uptake.

Physiological sensitivity of freshwater macroinvertebrates to heavy metals.

Macroinvertebrate species traits, such as physiological sensitivity, have successfully been introduced in trait-based bioassessment approaches and are important predictors of species sensitivity in the field. The authors ranked macroinvertebrate species according to their physiological sensitivity to heavy metals using toxicity data from acute laboratory assays. Rankings for each of the heavy metals, Cd, Cu, Cr, Ni, Pb, Zn, and Hg, were standardized based on all available species data. Rankings for different heavy metals on the species level showed no significant difference between compounds and were reasonably well correlated pairwise (0.50

Polychlorinated naphthalenes and other dioxin-like compounds in Elbe River sediments.

Contamination of Elbe River (Germany) sediments with dioxin-like toxicants was investigated following the 500-year flood (flood that statistically occurs once in 500 years) of 2002. It was hypothesized that large amounts of particulate matter from river beds and associated dioxin-like toxicants were mobilized and transported during this flood event. The investigation focused on polychlorinated naphthalenes (PCNs) that have not been determined previously in the Elbe River. The in vitro H4IIE-luc assay was used as an overall measure for toxicants capable of binding to the aryl hydrocarbon receptor (AhR). The assay was combined with congener-specific instrumental analyses and fractionation to quantify PCN contributions to total AhR-mediated activity relative to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs). Penta- to octachloronaphthalene concentrations of 30 ng/kg dry weight up to 13 microg/kg dry weight were found in Elbe River sediments downstream of Bitterfeld. Concentrations of penta- to octachloronaphthalenes, however, were only approximately 3 microg/kg dry weight at a site in the vicinity of Bitterfeld, where a level of approximately 3 mg/kg dry weight was reported before the flood. Also, the congener pattern of PCNs at this site changed after the flood, and PCN patterns reported previously for Bitterfeld and assigned to chlor-alkali electrolysis with graphite electrodes could now be observed at the sites from downstream of Bitterfeld and Magdeburg. Whereas PCDD/Fs dominated the dioxin-like activity in the middle and lower Elbe River, PCNs contributed as much as 10% of the total AhR-mediated activity. The contribution of PCBs was less significant (maximum, 0.2%). Thus, in Elbe River sediments, PCNs should be considered as relevant contaminants and be included in future monitoring and risk assessment programs.

On the mode of action of N-phenyl-2-naphthylamine in plants.

N-phenyl-2-naphthylamine, a sediment contaminant previously identified as a major toxicant of site-specific importance was investigated for its mode of toxic action. From short-term bioassays with daphnids, fish eggs, bacteria, and algae it appears that this compound has specific phytotoxic properties at concentrations below 100 microg/L, which cannot be explained assuming an unspecific narcosis type of action in plants. Also, hydroxy-, nitro-, and methylderivatives show clear excess toxicity as compared to baseline toxic effects. Of several plant-specific growth and development processes investigated, only photosynthesis could be demonstrated to be affected at short exposure times and low concentrations. Disturbance of primary photosynthetic reactions such as oxygen evolution and fluorescence quenching, however, becomes only apparent after 2-3 h of exposure, which is in sharp contrast to known specific inhibitors targeting processes such as electron transport or ATP production. This, and concentration-time-effect modeling lead to the suggestion that N-phenyl-2-naphthylamine acts intracellular as a reactive compound in cell membranes producing irreversible, and thus cumulative, damage over time in algae. The effects may become first apparent in membrane-rich compartments such as the algal chloroplast.

Identification of toxicants from marine sediment using effect-directed analysis.

Effect-directed analysis (EDA) has been reported to be a powerful tool for the identification of the responsible toxicants in contaminated, hazardous environmental samples. The aim of this study was to investigate whether it also is possible to use currently available EDA methodology to identify potentially relevant toxicants in samples that do not pose obvious problems. For this purpose, compounds extracted from a marine sediment sample from the west coast of Sweden were separated into distinct fractions, using two preparative chromatographic techniques. One algal bioassay using Scenedesmus vacuolatus and two bacterial bioassays using Vibrio fischeri were applied as detectors of toxicity, representing acute and chronic end points. Chronic algal toxicity was a powerful tool for discriminating between toxic and nontoxic fractions, whereas acute and chronic bacterial toxicity failed to identify toxic fractions. Eight compounds were identified as potentially relevant toxicants by chemical analysis of toxic fractions: anthracene, fluoranthene, pyrene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[a]pyrene, benzo[k]fluoranthene, and indeno[1,2,3-cd]pyrene.

Confirmation of cause-effect relationships using effect-directed analysis for complex environmental samples.

The establishment of causal links between chemical contamination and observed ecotoxic effects of environmental samples is a major challenge in ecotoxicology. Effect-directed analysis is an approach combining fractionation with toxicity testing before chemical nontarget analysis to separate and subsequently identify toxic compounds in environmental samples. A final confirmation step in this procedure evaluates how much of the observed toxicity in the environmental sample can be attributed to the mixture of identified toxicants. The aim of the present study is to advance the methodology for the confirmation of mixtures in effect-directed analysis by using tools for the assessment of mixture toxicity accounting for unknown modes of action and heterogeneity of concentration-response curves. For this purpose, toxicants were identified in sediment extracts from two different sites. All identified compounds were tested both individually as pure compounds and in mixtures at ratios equal to those found in the sediment extracts. The observed extract toxicity was then compared with the expected combined effects calculated according to the models of concentration addition and independent action as well as with the observed toxicity of the synthetic mixture. Drawbacks of the established approach using toxic unit summation are demonstrated, and the Index of Confirmation Quality, an easy-to-read representation that allows a quantitative measure of confirmation over a range of different effect levels, is introduced.

Modeling photoinduced algal toxicity of polycyclic aromatic hydrocarbons.

The influence of light conditions on the toxicity of polycyclic aromatic hydrocarbons (PAHs) to different organisms has long been recognized. The aim of this study was to investigate whether previously proposed models can be used to qualitatively and quantitatively predict photoinduced toxicity to the green algae Scenedesmus vacuolatus. For this purpose 14 different PAH compounds were tested under three different light conditions for their effects on the algae reproduction. Illumination conditions comprised standard algae growth light, simulated sunlight aiming to mimic environmental light conditions, and UV-filtered light in order to minimize light influence on PAH toxicity. Models proposed for the prediction of photoinduced toxicity were modified in order to account for different exposure conditions and toxic endpoints used in the bioassay. The results of this study show that the gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) proposed as an indication for photoinduced toxicity to Daphnia magna can be used as a qualitative indication of a potential photoinduced toxicity to the green algae Scenedesmus vacuolatus. The impact of light conditions on PAH toxicity can be quantified by a linear model which allows the estimation of the ED50 of each compound from the amount of absorbed photons and an empirically determined relative phototoxic efficacy value of the compound.

Light as a confounding factor for toxicity assessment of complex contaminated sediments.

Polycyclic aromatic hydrocarbons (PAHs) are contaminants often found in sediments. Their relevant contribution to toxic effects induced by environmental samples has been demonstrated using effect-directed analysis (EDA). Toxicity of PAHs previously has been reported to depend on light conditions. The aim of this study was to analyze the influence of simulated sunlight, in comparison to standard algal growth light, on the toxicity of samples, in which PAHs were identified as major toxicants using EDA. Additionally, toxicity of identified toxicants and mixtures of these compounds were assessed. It can be shown that the samples, the PAH compounds, and the created mixtures exhibit photoenhanced toxicity. The combined effects of the mixtures can be predicted using the model of concentration addition. This is surprising because different modes of action have been reported to contribute to phototoxicity of the identified toxicants. For the confirmation step in EDA, the toxicity assessment under simulated sunlight reveals that less of the samples' toxicity can be explained by the identified compounds, compared to the assessment conducted under standard growth light. Finally, the relevance of light conditions in the toxicity assessment is demonstrated for eight out of 13 transect samples of sediment extracts from river Elbe, Germany.

What contributes to the combined effect of a complex mixture?

The effect of a mixture of 10 compounds, which have previously been identified in an effect-directed analysis as potentially relevant for a specific contaminated riverine sediment (Brack et al. Arch. Environ. Contam. Toxicol. 1999, 37, 164), were investigated for the underlying joint effect. Components identified in an organic sediment extract included several PAHs (benzo[ghi]fluoranthene, benz[a]anthracene, fluoranthene, pyrene, 2-phenylnaphthalene, anthracene, and phenanthrene) plus prometryn, N-phenyl-2-naphthylamine, and parathion-methyl. Experiments were performed using a one-generation algal bioassay with the unicellular green algae Scenedesmus vacuolatus as well as chlorophyll fluorescence quenching analysis to describe the effects of the components and mixtures thereof. Analysis of the mixture effects based on concentration-response modeling of the effect data reveals that indeed effect contributions of several components can be expected although the mixture ratio is not equitoxic and the individual components vary greatly with respect to biological effect. Comparing predicted and observed mixture effects, the combined effect may not be attributed to a joint narcotic effect of the mixture components. Evidently, some of the components act specifically and dissimilar and may therefore be best described in their combined effect by response addition while for others a similar mode of action seems plausible. Chlorophyll fluorescence quenching analysis supports to discriminate between prometryn, N-phenyl-2-naphthylamine, and PAHs. A joint model for calculating the combined effect using concentration addition for the suspected unspecifically acting components in algae (PAHs and parathion-methyl) and subsequently response addition for this group and the other components clearly improves the description of the observed combined effect. Allocation of effect contributions to specific components using toxic units or effect contributions lead to different judgments. The observed combined effect of a 3-compound mixture of prometryn, N-phenyl-2-naphthylamine, and benzo[ghi]fluoranthene is indistinguishable from the effects of the original 10-compound mixture, demonstrating the need in site-specific assessment of complex contamination to account for the mode of action of contaminants. Implications forthe confirmation step in effect-directed analysis of substances causing effects in complex contaminated samples are discussed.