Passive samplers versus surfactant extraction for the evaluation of PAH availability in sediments with variable levels of contamination
Institut des sciences de la mer à Rimouski (ISMER), Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski (Qc), Canada G5L 3A1. Chemosphere
(Impact Factor: 3.34).
04/2008; 71(8):1486-93. DOI: 10.1016/j.chemosphere.2007.12.015
The purpose of this study was to test the efficiency of passive solid samplers, polyoxymethylene (POM) strips and polydimethylsiloxane (PDMS) silicon tubing, to predict the bioavailability of native PAHs in contaminated sediments. Results were compared with worm bioaccumulation data and solid/liquid extraction using the surfactant Brij((R)) 700 (B700). The two passive samplers were found to act differently. The PDMS sampler overestimated the availability of PAHs in all studied sediments. The POM method provided results in accordance with those obtained with the B700 extraction. However, POM and B700 methods underestimated PAH availability in low contaminated sediments where biological factors (digestible organic matter) become important. Bioavailability of total PAHs was correctly predicted by POM and B700 in highly contaminated aluminum smelter sediments. A closer examination of individual PAH results indicated that both techniques overestimated the availability of large molecules with logK(ow)>6 suggesting a biological mechanism limiting uptake of larger PAHs which seems to be related to the molecular size of compounds.
Available from: Aurelija Spiric
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ABSTRACT: Smoked meat products are still produced in traditional way in Zlatibor region, Serbia. Beef and pork ham were smoked by beech wood smoke, both in traditional (TS) and industrial smokehouses (IS). Smoke samples were collected from both smokehouses using different types of tubes (PUF and XAD-2) during meat smoking. The sum of 16 EU priority PAHs in final smoked beef and pork ham was (µg/kg): beef ham - 3.9/TS, 1.9/IS; pork ham - 4.9/TS, 4.2/IS. The total emission of the analysed PAHs in smoke samples was (mg/m3): in PUF 1.1/TS, 3.8/IS and in XAD-2 0.9/TS, 11.0/IS. PAH fingerprints in smoke and smoked beef and pork ham were compared. Chrysene was found to be the most predominant PAH compound in smoke, both in PUF and XAD-2 tubes from TS, while benzo(c)fluorene (BcL) was the most predominant PAH in smoke from IS. For PAHs with lower MW (BcL to BaP) similar fingerprints between smoke-beef and smoke-pork ham were observed, while the fingerprints for dibenzopyrenes (MW=302) were different, both in TS and IS. BaP equivalent concentrations (BaPeq) were calculated, both in smoke and smoked meat products.
Available from: Emilien Pelletier
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ABSTRACT: In this review we consider the current state of the field of ecotoxicology, with an emphasis on aquatic environments, and explore its strengths and weaknesses. We compare and contrast the environmental behaviour of organic and inorganic contaminants, and identify a number of challenges for the future development of the field. The uptake of synthetic organic contaminants normally occurs by simple passive diffusion across a cell membrane. Given the lipidic and thus hydrophobic nature of biological membranes, the octanol-water partitioning coefficient of an organic contaminant (Kow) is often a good predictor of its tendency to bioaccumulate. In contrast, metals present in the aquatic environment are generally present in hydrated and hydrophilic forms, which cannot cross biological membranes by simple diffusion. Thus their uptake normally occurs by facilitated transport involving membrane carriers or channels. The octanol-water partitioning coefficients of these metallic species thus have no bearing on the relative facility with which they can cross biological membranes. It follows that the modeling approaches will differ greatly between organic and inorganic (metallic) contaminants. For metals, two types of models are currently popular: equilibrium models (e.g., the "Biotic Ligand Model" or BLM) and kinetic models of metal uptake and elimination. In both cases, the biological parameters of the models are considered as "constants", which are unaffected by the ambient water quality (e.g., pH; hardness) or by prior exposure to the metal. However, recent research suggests that the key epithelial properties of aquatic organisms that govern metal accumulation and toxicity are not constant, thus compromising the application of the models to real-world cases of chronic exposure to metals. In the case of organic contaminants, ecotoxicological concerns tend to focus on their capacity to resist various degradation mechanisms and on their bioavailability. Fugacity models can be used to predict the distribution of organic molecules among various environmental compartments for systems at equilibrium, but many chemical and biological constraints limit the application of such models. Case studies with polycyclic aromatic hydrocarbons (PAH) and organometallic species are presented to illustrate these constraints. Finally, among new, frontiers and opportunities for ecotoxicology, we briefly consider the development of toxicogenomics, the need to consider the effects of contaminants on trophic interactions in a truly ecosystemic approach, and the challenge posed by nanoparticles of industrial origin. The future of ecotoxicology will necessarily involve: (1) the collection of high quality data in the laboratory and in the field; (2) an improved understanding of the mechanisms of toxicity at the molecular and cellular levels; (3) the development of theoretical and empirical models that better integrate physiological and ecological reality; and (4) the development of ecosystem indicators that can be used to evaluate the quality of aquatic environments, despite their inherent complexity.
Available from: Peter G. C. Campbell
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