Blue mussels and Pacific oysters in Belgian coastal harbours as test organisms for environmental stress

Harbours receive, as semi-enclosed structures, high loads of chemical substances through river inputs, direct discharges (oil spills) as well as by indirect ways such as shipping traffic, atmospheric deposition, wastewater, etc. This means that organisms living in harbours are exposed to a wide range of pollutants which have the potential to cause stress by disturbing the normal functioning of the biological organisation. As part of the INRAM project, in which the risk of micropollutants is studied for the Belgian coastal zone, a cage experiment with mussels and oysters was conducted in the harbour of Zeebrugge and in the Sluice dock of Oostende to study the susceptibility of these bivalves to the prevealing stress. The cage experiment ran over a period of five months, from June 2007 till October 2007. Mussels (Mytilus edulis) and oysters (Crassostrea gigas) collected in a subtidal area of the Eastern Scheldt were transplanted to cages at four stations: outer harbour of Zeebrugge, inner harbour of Zeebrugge, Sluice Dock in Oostende and one at open sea. Mussels were sampled monthly, oysters bimonthly. Growth, condition index and gonad development were recorded. Soft tissue was saved for concentration measurements. Abiotic parameters were recorded fortnightly. First results show significant differences in growth and condition index between the sites. The shell length increment and condition indices show a significant decrease according to a spatial gradient from outer harbour towards inner harbour, towards the sluice dock. The experiment allows an evaluation of the existence of biometric differences between the different sampling stations. In the near future a possible correlation with the body burdens will be studied

Prediction of the Atomization Energy of Molecules Using Coulomb Matrix and Atomic Composition in a Bayesian Regularized Neural Networks

Exact calculation of electronic properties of molecules is a fundamental step for intelligent and rational compounds and materials design. The intrinsically graph-like and non-vectorial nature of molecular data generates a unique and challenging machine learning problem. In this paper we embrace a learning from scratch approach where the quantum mechanical electronic properties of molecules are predicted directly from the raw molecular geometry, similar to some recent works. But, unlike these previous endeavors, our study suggests a benefit from combining molecular geometry embedded in the Coulomb matrix with the atomic composition of molecules. Using the new combined features in a Bayesian regularized neural networks, our results improve well-known results from the literature on the QM7 dataset from a mean absolute error of 3.51 kcal/mol down to 3.0 kcal/mol.Comment: Under review ICANN 201

Observation of individual molecules trapped on a nanostructured insulator

For the first time, ordered polar molecules confined in monolayer-deep rectangular pits produced on an alkali halide surface by electron irradiation have been resolved at room temperature by non-contact atomic force microscopy. Molecules self-assemble in a specific fashion inside pits of width smaller than 15 nm. By contrast no ordered aggregates of molecules are observed on flat terraces. Conclusions regarding nucleation and ordering mechanisms are drawn. Trapping in pits as small as 2 nm opens a route to address single molecules

ENDIS-RISKS: endocrine disruption in the Scheldt estuary - a field study

ENDIS-RISKS, a multidisciplinary research project with five institutes, evaluates the distribution, exposure and effects of endocrine disruptors in the Scheldt Estuary. This estuary is known to be one of the most polluted estuaries in the world. Untreated domestic wastewater and effluents of the industrial areas of Ghent and Antwerp are to a large extent responsible for this pollution. During an intensive field study of four years, eight sampling campaigns were executed on seven sampling points along the Scheldt Estuary. A detailed analysis of the distribution of endocrine disrupting substances in the Scheldt Estuary was executed. Water, sediment, suspended solids and biota were analysed for seven groups of chemicals: estrogens, pesticides, organotins, polyaromatic components, polyaromatic hydrocarbons and phenols. Special attention was given to the estuarine mysid shrimp Neomysis integer. Its ecotoxicology and population characteristics were studied in detail. A selection of results of this field study is put forward. Water samples, tested in vitro for their potential to bind with estrogen, revealed more estrogenic activity in the more upstream stations. Concentrations of chlorotriazine herbicides in water samples, were higher in the upstream reaches compared to the downstream sites. Analyses of TBT in mysid shrimps revealed high concentrations (>2mg.kg-1 dry weight) which suggests a high bioaccumulation capacity. Population characteristics results of N. integer show that it has a broader distribution range, with a shift more upstream, in comparison with historical data (Mees et al., 1995). On the other hand, length distribution of developmental stages of N. integer along the estuary indicates some environmental stress, caused by the estuarine gradient or by pollutants. Some hypotheses will be put forward to explain these patterns