Distribution and ecotoxicity of chlorotriazines in the Scheldt Estuary (B-Nl).

As part of the Endis-Risks project, the current study describes the occurrence of the chlorotriazine pesticides atrazine, simazine and terbutylazine in water, sediment and suspended matter in the Scheldt estuary (B-Nl) from 2002 to 2005 (3 samplings a year, 8 sampling points). Atrazine was found at the highest concentrations, varying from 10 to 736 ng/l in water and from 5 up to 10 ng/g in suspended matter. Simazine and terbutylazine were detected at lower concentrations. Traces of the targeted pesticides were also detected in sediments, but these were below the limit of quantification. As part of an ecotoxicological assessment, we studied the potential effect of atrazine on molting of Neomysis integer (Crustacea:Mysidacea), a resident invertebrate of the Scheldt Estuary and a proposed test organism for the evaluation of endocrine disruption. Following chronic exposure ( approximately 3 weeks), atrazine did not significantly affect mysid molting at environmentally relevant concentrations (up to 1 microg/l).

Realistic environmental mixtures of hydrophobic compounds do not alter growth of a marine diatom.

In this paper we determine whether a realistic mixture of hydrophobic chemicals affects the growth dynamics of a marine diatom and how this effect compares to the effect of temperature, light regime and nutrient conditions. To do so, we examine the specific growth rate of Phaeodactylum tricornutum in a 72 h algal growth inhibition test using a full factorial design with three nutrient regimes, two test temperatures, three light intensities and three chemical exposures. Passive samplers were used to achieve exposure to realistic mixtures of organic chemicals close to ambient concentrations. Nutrient regime, temperature and time interval (24, 48 and 72 h) explained 85% of the observed variability in the experimental data. The variability explained by chemical exposure was about 1%. Overall, ambient concentrations of hydrophobic compounds present in Belgian coastal waters, and for which the passive samplers have affinity, are too low to affect the intrinsic growth rate of P. tricornutum.

Passive sampling reversed: coupling passive field sampling with passive lab dosing to assess the ecotoxicity of mixtures present in the marine environment.

This study presents a new approach in aquatic toxicity testing combining passive sampling and passive dosing. Polydimethylsiloxane sheets were used to sample contaminant mixtures in the marine environment. These sheets were subsequently transferred to ecotoxicological test medium in which the sampled contaminant mixtures were released through passive dosing. 4 out of 17 of these mixtures caused severe effects in a growth inhibition assay with a marine diatom. These effects could not be explained by the presence of compounds detected in the sampling area and were most likely attributable to unmeasured compounds absorbed to the passive samplers during field deployment. The findings of this study indicate that linking passive sampling in the field to passive dosing in laboratory ecotoxicity tests provides a practical and complimentary approach for assessing the toxicity of hydrophobic contaminant mixtures that mimics realistic environmental exposures. Limitations and opportunities for future improvements are presented.

Modelling the fate of micropollutants in the marine environment using passive sampling.

Polydimethylsiloxane sheets were used to determine freely dissolved concentrations (C(diss)) of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the Belgian coastal zone. Equilibrium models were used to predict the whole water concentrations (C(ww)) of these compounds as well as their concentrations in sediment, suspended particulate matter (SPM) and biota. In general, contaminant concentrations were predicted well for whole water and biota. C(ww) was increasingly underpredicted as K(oc) increased, possibly because of the presence of black carbon. Concentrations in biota were overestimated by the equilibrium approach when logK(ow) exceeded 6.5, suggesting an increasing role of transformation processes. Concentrations of PAHs and PCBs in sediment and SPM were consistently underpredicted although a good correlation between measured and predicted values was observed. This was potentially due to the use of experimental K(oc) values which have been found to underestimate partitioning of hydrophobic substances to sediment in field studies.

n-Alkanes and stable C, N isotopic compositions as identifiers of organic matter sources in Posidonia oceanica meadows of Alexandroupolis Gulf, NE Greece.

We analyzed n-alkane contents and their stable carbon isotope composition, as well as the carbon and nitrogen isotope composition (δ(13)C, δ(15)N) of sediment organic matter and different tissues of Posidonia oceanica seagrass sampled in Alexandroupolis Gulf (A.G.), north-eastern Greece, during 2007-2011. n-Alkane contents in P. oceanica and in sediments showed similar temporal trends, but relative to bulk organic carbon content, n-alkanes were much more enriched in sediments compared to seagrass tissue. Individual n-alkanes in sediments had similar values than seagrass roots and rhizomes and were more depleted in (13)C compared to seagrass leaves and sheaths, with δ(13)C values ranging from -35‰ to -28‰ and from -25‰ to -20‰, respectively. n-Alkane indexes such as the Carbon Preference Index, carbon number maximum, and n-alkane proxy 1 (C23+C25/C23+C25+C29+C31) indicate strong inputs of terrestrial organic matter, while the presence of unresolved complex mixtures suggests potential oil pollution in some sampled areas.

Estrogenic and toxic effects of methoxychlor on zebrafish (Danio rerio).

Although zebrafish (Danio rerio) have been suggested as a good candidate for screening potential endocrine disruptors, little information is available on the effects of weak estrogens on this species. We investigated the sensitivity of different life stages of zebrafish toward toxic and estrogenic properties of methoxychlor (MXC). Short-term tests with adults resulted in a sex-specific 96-h lethal concentration for 50% (LC50) of the test animals of 36 microg/L for males and 129 microg/L for females. To determine the estrogenic capacity of MXC, adult zebrafish were exposed to 0, 0.5, 5, and 50 microg MXC/L for 14 d. Induction of vitellogenin ([VTG] measured with protein electrophoresis and Western blot) in males was detected at 5 and 50 microg MXC/L. Females, however, did not exhibit higher blood VTG concentrations at the tested MXC concentrations. In a second series of experiments, juvenile zebrafish were exposed to 0, 0.05, 0.5, and 5 microg MXC/L for 33 d. Survival, length, weight, and condition of larvae were examined as indicators of toxic stress and the VTG content in whole body homogenates of juveniles was measured to determine xenoestrogenic effects. No effects of the tested concentrations of MXC were observed. Finally, the effect of MXC on zebrafish eggs, exposed to 0, 1, 10, and 32 microg MXC/L, was examined. Hatching and survival of hatched zebrafish were affected at 10 and 32 microg MXC/L. This study demonstrated that adult male zebrafish are sensitive toward the estrogenic effects of MXC. However, the use of VTG induction to detect effects of (xeno)estrogens in early life stages has to be further investigated, as low concentrations of VTG were detectable in exposed as well as unexposed juvenile fish.

Monitoring polycyclic aromatic hydrocarbons in the Northeast Aegean Sea using Posidonia oceanica seagrass and synthetic passive samplers.

The concentrations of 22 polyaromatic hydrocarbons (PAH) in Posidonia oceanica seagrass, sediments, and seawater from the Alexandroupolis Gulf in the Aegean Sea, were investigated from 2007 to 2011. Temporal trends of total PAH contents in P. oceanica and sediments were similar. PAH levels in seawater, sediments, and seagrasses generally decreased with increasing distance from Alexandroupolis Port. Leaves and sheaths of P. oceanica had higher PAH levels than roots and rhizomes. P. oceanica accumulates PAHs and has good potential as a bioindicator of spatiotemporal pollution trends. PAH concentrations were also examined using in situ passive seawater sampling and were compared to results of passive sampling in the laboratory using local sediments and seawater. Levels of high molecular weight PAHs assessed using passive samplers confirmed the decreasing gradient of pollution away from Alexandroupolis Port. Passive sampling also proved useful for investigating sources of PAHs in P. oceanica meadows.

Application of a silicone rubber passive sampling technique for monitoring PAHs and PCBs at three Belgian coastal harbours.

A 4-year monitoring was performed to study the freely dissolved water concentrations of PAHs and PCBs in three coastal harbours and at an offshore station in the North Sea. The results are part of a more extensive study to provide information on occurrence, distribution and effects of pollutants in the Belgian coastal zone. Several methods for the estimation of freely dissolved water concentrations are reported in the literature. In the present study silicone rubber passive samplers were used. The non-linear least-square (NLS) method proved to be suitable for estimating sampling rates when using the following performance reference compounds: fluorene-d10, phenanthrene-d10, fluoranthene-d10, benzo(e)pyrene-d12, coronene-d12, CB10, CB14, CB50, CB104, CB145 and CB204. The application of two NLS methods for estimating the sampling rate (Rs) resulted in significant differences for freely dissolved concentrations for individual compounds of up to 30% between the two methods. A model that takes into account the decrease of sampling rate for compounds with higher molecular weight should give a more accurate Rs and was the preferred estimation method. Rs varied from 0.9 to 34.8Ld(-1) for the different target compounds, while estimated freely dissolved concentrations for sum 15 PAHs varied between 3.9 and 170ngL(-1) and for sum 14 PCBs between 0.030 and 3.1ngL(-1). The stations located within marinas showed the highest level of contamination, while the offshore station (5 mile from coastline) exhibited the lowest level. The implications of the use of passive samplers for monitoring programs are discussed.

Monitoring micropollutants in marine waters, can quality standards be met?

The environmental risks of 33 micropollutants occurring in Belgian coastal zone were assessed as single-substances and as mixtures. Water and sediment samples were taken in harbors, coastal waters and the Scheldt estuary during 2007-2009. Measured environmental concentrations were compared to quality standards such as Predicted No Effect Concentrations (PNECs), Environmental Quality Standards (EQSs), and Ecotoxicological Assessment Criteria (EAC). Out of a total of 2547 samples analyzed, 232 and 126 samples exceeded the EQS and EAC, respectively. Highest risks were observed for TBT, PBDEs, PCBs and the PAHs anthracene, indeno(1,2,3-cd)pyrene, benzo(g,h,i)perylene, benzo(k)fluoranthene, and benzo(b)fluoranthene in the water compartment and for TBT and PCBs in the sediment compartment. Samples taken at all stations during the April 2008 campaign indicate a potential risk of the contaminant mixtures to the aquatic environment (except W06 station). This study argues the need to revise quality standards when appropriate and hence the overall regulatory implication of these standards.

Rapid quantification of pharmaceuticals and pesticides in passive samplers using ultra high performance liquid chromatography coupled to high resolution mass spectrometry.

The presence of both pharmaceuticals and pesticides in the aquatic environment has become a well-known environmental issue during the last decade. An increasing demand however still exists for sensitive and reliable monitoring tools for these rather polar contaminants in the marine environment. In recent years, the great potential of passive samplers or equilibrium based sampling techniques for evaluation of the fate of these contaminants has been shown in literature. Therefore, we developed a new analytical method for the quantification of a high number of pharmaceuticals and pesticides in passive sampling devices. The analytical procedure consisted of extraction using 1:1 methanol/acetonitrile followed by detection with ultra-high performance liquid chromatography coupled to high resolution and high mass accuracy Orbitrap mass spectrometry. Validation of the analytical method resulted in limits of quantification and recoveries ranging between 0.2 and 20 ng per sampler sheet and between 87.9 and 105.2%, respectively. Determination of the sampler-water partition coefficients of all compounds demonstrated that several pharmaceuticals and most pesticides exert a high affinity for the polydimethylsiloxane passive samplers. Finally, the developed analytical methods were used to measure the time-weighted average (TWA) concentrations of the targeted pollutants in passive samplers, deployed at eight stations in the Belgian coastal zone. Propranolol, carbamazepine and seven pesticides were found to be very abundant in the passive samplers. These obtained long-term and large-scale TWA concentrations will contribute in assessing the environmental and human health risk of these emerging pollutants.

Occurrence of estrogens in the Scheldt estuary: a 2-year survey.

Despite the increased research and regulatory interest in numerous bioactive agents, including natural hormones, xeno-hormones and pharmacological agents, little is known about the presence of these compounds in the estuarine and marine environment. In this study, the results of a 2-year survey on the occurrence of the natural female sex hormones, estradiol (E2) and estrone (E1) and the synthetic steroid, ethinylestradiol (EE2) in the Scheldt estuary (Belgium-The Netherlands) are presented. Chemical analysis of the water samples was performed using Speedisk extraction. Suspended matter samples were analyzed with accelerated solvent extraction (ASE) and detection was performed with gas chromatography coupled to multiple ion trap mass spectrometry. Detected concentrations were in the low ng L(-1) range. E1 and betaE2 (beta-isomer of E2) were detected in water and suspended matter, whereas concentrations of EE2 were below the limit of quantification (LOQ). E1 was observed most frequently and at concentrations up to 10 ng L(-1) in water and up to 0.84 ng g(-1) in suspended matter samples.