Published on April 24, 2013

Modelling the effects of copper on soil organisms and processes using the free ion approach: Towards a multi-species toxicity model

env_pollutOur lab has a long history of metal bioavailability research. Here, the results of previous terrestrial studies performed by our lab was used and integrated with other datasets to develop a general biovailability model for copper. The free ion approach has been previously used to calculate critical limit concentrations for soil metals based on point estimates of toxicity. In this study, the approach was applied to dose–response data for copper effects on seven biological endpoints in each of 19 European soils. The approach was applied using the concept of an effective dose, comprising a function of the concentrations of free copper and 'protective' major cations, including H+. A significant influence of H+ on the toxicity of Cu2+ was found, while the effects of other cations were inconsistent. The model could be generalised by forcing the effect of H+ and the slope of the dose–response relationship to be equal for all endpoints. This suggests the possibility of a general bioavailability model for copper effects on organisms. Furthermore, the possibility of such a model could be explored for other cationic metals such as nickel, zinc, cadmium and lead.

Full reference (link)

Published on April 18, 2013

New techniques for the detection of microplastics in sediments and field collected organisms

marinepollutionbulletinMicroplastics have been reported in marine environments worldwide. Accurate assessment of quantity and type is therefore needed. Here, we propose new techniques for extracting microplastics from sediment and invertebrate tissue. The method developed for sediments involves a volume reduction of the sample by elutriation, followed by density separation using a high density NaI solution. Comparison of this methods' efficiency to that of a widely used technique indicated that the new method has a considerably higher extraction efficiency. For fibres and granules an increase of 23% and 39% was noted, extraction efficiency of PVC increased by 100%. The second method aimed at extracting microplastics from animal tissues based on chemical digestion. Extraction of microspheres yielded high efficiencies (94–98%). For fibres, efficiencies were highly variable (0–98%), depending on polymer type. The use of these two techniques will result in a more complete assessment of marine microplastic concentrations.

Full reference (link)

Claessens M, Van Cauwenberghe L, Vandegehuchte M, Janssen CR. 2013. New techniques for the detection

Published on April 15, 2013

Prof. Janssen elected Chair of EU Committee SCHER

eu logo enOn 11 and 12 April 2013, the first meeting of the newly appointed EU Scientific Committee SCHER took place in Luxembourg. After a rigorous selection procedure - i.e. there were more than 400 candidates - based on criteria such as scientific excellence and independence, Prof. Janssen was appointed as one of the 11 members of SCHER (Scientific Committee on Health and Environmental Risks). Committee members are appointed for a three-year term and will provide the Commission with independent scientific advice on issues relating to consumer safety, public health and the environment. Following his appointment Prof. Janssen was then elected by SCHER members to serve as Chair of the Committee.

More information on SCHER and the inaugural meeting:

scher cj

Published on April 10, 2013

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

marinepollutionbulletinThe 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.

Full reference (link)

Ghekiere A, Verdonck F, Claessens M, Monteyne E, Roose P, Wille K, Goffin A, Rappé K, Janssen CR. 2013. Monitoring micropollutants in marine waters, can quality

Published on March 27, 2013

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

chemosphereA 4-year monitoring study - coordinated by our lab - was performed to examine 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. In the present study silicone rubber passive samplers were used. We found that 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)pyrened12, 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 34.8 L/d for the different target compounds, while estimated freely dissolved concentrations for sum 15 PAHs varied between 3.9 and170 ng/L and for sum 14 PCBs between 0.030 and 3.1 ng/L. 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.

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Published on March 20, 2013

Whole sediment toxicity tests for metal risk assessments: On the importance of equilibration and test design to increase ecological relevance

etc cover2Current laboratory-based approaches for predicting metal toxicity in sediments exhibit a number of limitations. The most important are (1) a lack of sufficient equilibration resulting in unrealistically low pH values or unnaturally high pore water metal concentrations and (2) an inadequate test design regarding the metal concentrations selected for spiking. This study illustrates that by explicitly accounting for these limitations, one obtains reliable and environmentally realistic toxicity data, thus advancing the metal risk assessments of sediments. To this end, a toxicity test design with natural sediments was developed in which the administered metal concentrations were selected to comprise a range of [SEM-AVS] (the difference between the molar concentration of simultaneously extracted metals and acid volatile sulfides) closely surrounding zero. In addition, the presented test design includes a 35 or 40 day equilibration period with overlying water renewal during which conductivity, pH and metal concentrations in the overlying water are monitored. This allows toxicity testing to start after equilibrium for these parameters has been reached. This test design was applied to Ephoron virgo (Olivier, 1791), Gammarus pulex (Linnaeus, 1758) and Lumbriculus variegatus (Mueller, 1774) exposed to Zn and Pb. These tests indicated that the general concept of absence of toxicity when [SEM-AVS]<0 could not be rejected. However, the onset of Zn toxicity occurred at lower concentrations than generally assumed.

Published on March 14, 2013

Using additive modelling to quantify the effect of chemicals on phytoplankton diversity and biomass

scitotenvEnvironmental authorities require the protection of biodiversity and other ecosystem properties such as biomass production. However, the endpoints listed in available ecotoxicological datasets generally do not contain these two ecosystem descriptors. Inferring the effects of chemicals on such descriptors from micro- or mesocosm experiments is often hampered by inherent differences in the initial biodiversity levels between experimental units or by delayed community responses. Here we introduce additive modelling to establish the effects of a chronic application of the herbicide linuron on 10 biodiversity indices and phytoplankton biomass in microcosms. We found that communities with a low (high) initial biodiversity subsequently became more (less) diverse, indicating an equilibrium biodiversity status in the communities considered here. Linuron adversely affected richness and evenness while dominance increased but no biodiversity indices were different from the control treatment at linuron concentrations below 2.4 μg/L. Richness-related indices changed at lower linuron concentrations (effects noticeable from 2.4 μg/L) than other biodiversity indices (effects noticeable from 14.4 μg/L) and, in contrast to the other indices, showed no signs of recovery following chronic exposure. Phytoplankton biomass was unaffected by linuron due to functional redundancy within the phytoplankton community. Comparing thresholds for biodiversity with conventional toxicity test results showed that standard ecological risk assessments also protect biodiversity in the case of linuron.

Published on February 14, 2013

Dr. ir. Frederik De Laender joined the Young Academy

jongeacademie Recently, the Royal Flemish Academy of Belgium decided to establish a Young Academy. Forty young researchers, amongst whom Frederik De Laender of our lab, have joined the Young Academy. They were selected from as many as 146 high-potential candidates who responded to the call for membership. These young researchers have three objectives: (international) interdisciplinary research, reflection about the current science policy, and science communication to the youth. Congratulations, Frederik!

Update: In total 13 researchers of Ghent University were selected. More information: (Dutch)

Published on February 13, 2013

Best oral presentation award on the 18th national symposium on applied biological sciences

awardA few days ago, the 18th National Symposium on Applied Biological Sciences took place in Ghent at which we were present with four oral presentations and four poster presentations. It was a successful symposium, not the least for our lab-member David Deruytter who won the award for best oral presentation in the Environmental Quality session with his talk entitled "The combined effect of DOC and salinity on the accumulation and toxicity of copper in mussel larvae". Congratulations, David!

Published on February 12, 2013

Interactive effects of a bacterial parasite and the insecticide carbaryl to life-history and physiology of two Daphnia magna clones differing in carbaryl sensitivity

aquatic toxicologyNatural and chemical stressors occur simultaneously in the aquatic environment. Their combined effects on biota are usually difficult to predict from their individual effects due to interactions between the different stressors. Several recent studies have suggested that synergistic effects of multiple stressors on organisms may be more common at high compared to low overall levels of stress. In this study, we used a three-way full factorial design to investigate whether interactive effects between a natural stressor, the bacterial parasite Pasteuria ramosa, and a chemical stressor, the insecticide carbaryl, were different between two genetically distinct clones of Daphnia magna that strongly differ in their sensitivity to carbaryl. Interactive effects on various life-history and physiological endpoints were assessed as significant deviations from the reference Independent Action (IA) model, which was implemented by testing the significance of the two-way carbaryl × parasite interaction term in two-way ANOVA's on log-transformed observational data for each clone separately. Interactive effects (and thus significant deviations from IA) were detected in both the carbaryl-sensitive clone (on survival, early reproduction and growth) and in the non-sensitive clone (on growth, electron transport activity and prophenoloxidase activity). No interactions were found for maturation rate, filtration rate, and energy reserve fractions (carbohydrate, protein, lipid). Furthermore, only antagonistic interactions were detected in the non-sensitive clone, while only synergistic interactions were observed in the carbaryl sensitive