Environmental Chemistry Highlights from the 2010 SETAC Europe Annual Meeting
John Parsons, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, The Netherlands
This year’s annual meeting in Seville featured many presentations dealing with environmental chemistry, not only in the sessions that were labeled as such but also in other themes such as emerging pollutants and ecotoxicology. With such a large number of presentations it is impossible to present a comprehensive summary. Instead, I will restrict myself to some personal impressions of the highlights regarding environmental organic chemistry.
First of all, the general standard of presentations was very high and I was particularly impressed by the number of presentations of studies dealing with mechanistic aspects of the environmental behavior of organic chemicals. Another general impression is that more and more work is being done on the environmental chemistry of the polar and ionic compounds. Such compounds are becoming increasingly important as many of the emerging pollutants fall into these categories. Partitioning of these compounds is much more complex than that of the “traditional” hydrophobic chemicals but real progress is being made in understanding and quantifying the mechanisms involved in these processes.
Another group of pollutants that is not really new but that is finally receiving attention from environmental chemists is the methylsiloxanes. The environmental behavior and effects of plastics is also an up-and-coming field as shown by the fascinating and very popular session on Thursday morning regarding plastics in the environment.
As far as methods are concerned, it was obvious that passive sampling and dosing techniques are becoming very popular, with not only an entire session being devoted to this topic but with these methods being used in many studies presented in other sessions. The presence of plastic materials in, for example, the marine environment could be regarded as an unintentional passive sampling campaign and this is, in fact, the basis of the international Pellet Watch project. The aim of this project is to analyze persistent pollutants in plastic pellets collected across the globe as a monitoring tool.
A number of presentations in different sessions dealt with the sorption of polar compounds to soil and sediment. A nice example was the presentation by Bonner and Goss given in the Fate of Pesticides session describing a study of the sorption of a number of polar pesticides and pharmaceuticals to soil. Different mechanisms are involved in sorption of these compounds and the overall process could be described successfully with so-called poly-parameter models with different parameters representing different mechanisms. Interestingly, one of the parameters—the S parameter describing molecular polarizability—could successfully predict the linearity of sorption.
The Sorption and Bioavailability of Organic Chemicals session also included a number of interesting presentations on sorption mechanisms of ionic compounds. Droge et al. showed sorption data for cationic amines measured with an elegant method based on an HPLC system. Results from this study indicated cation exchange as an important sorption mechanism for this class of compounds. In contrast, the sorption of sulfamethazine, a compound with a pH-dependent charge, to biochar does not involve ion exchange. In this case, π-π interactions between the chemical and the biochar surface seem to dominate. Other presentations in this session described new techniques to study sorption, such as nanocalorimetry, infrared spectroscopy and scanning transmission x-ray microscopy. The latter technique enables the visualization of phenanthrene sorbed to activated carbon, showing that this compound can penetrate into pores in activated carbon and compete for binding sites there.
A more traditional topic was addressed in a presentation on the in situ partitioning of PAHs in sediment. A novel aspect was that data on an expanded set of PAHs (EPA-34 including alkylated PAHs) were analyzed and it was concluded that partitioning could be described with a Koc-based model. This is surprising considering the important role that is often attributed to black carbon in the sorption of PAHs. Interesting also was that the concentrations of individual PAHs correlated well with the total PAH concentration, suggesting individual PAHs could be used as indicators for the total PAH content and implying that potential structure-dependent degradation processes had only a minor effect on PAH patterns.
Environmental analytical chemistry is an important aspect in the identification of environmental toxicants. The session devoted to this subject included presentations describing the applications of toxicant identification schemes to new matrices such as snow, wastewater treatment plant effluents and blood plasma. An increasing number of endpoints is being applied in these studies and in vitro and in vivo endpoints are being linked. Studies are revealing an increasing number of important toxicants, with polar compounds becoming more important. An important challenge in these studies is the interpretation of mass spectra as a means to elucidate the structures of toxicants in effect-directed analysis.
Advances in Bioaccumulation Assessment was another session including interesting environmental chemistry aspects. A particularly interesting development in this field is the evidence for proteins as important factor in the bioaccumulation of polar compounds. This was concluded from the results of a study using bovine serum albumin as model system. Another model system that has been successfully applied in bioaccumulation studies is the use of liposomes in studies of the bioaccumulation of hydrophobic organic compounds.
The session on poly- and perfluorinated compounds (PFCs) was relatively small this year, but nevertheless included interesting presentations on new developments such as new methods for the isomer-specific analysis of perfluorinated alkyl sulphonates and data on levels and behaviour of PFCs in the Arctic. Relatively high concentrations of these compounds are present in the NE Atlantic Ocean and melting snow seems to be an important source for Arctic. As far as human exposure is concerned, perfluorinated acids are present in significant concentrations in both breast milk and commercial baby food in Flanders, resulting in exposure levels for infants above the tolerable daily intake.
The above represents only a few of the highlights but I hope that it is sufficient to give a good impression of the high standard of the meeting. With all this excellent and important research being carried out in the SETAC community, we can look forward to many interesting presentations at future meetings.
Author contact information: J.R.Parsons@uva.nl
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