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(38-70) Effect of different dissolved organic materials on bioaccumulation of polycyclic aromatic hydrocarbons by Daphnia magna. Gourlay, Catherine*,1, Tusseau-Vuillemin, Marie-Hélène2, Garric, Jeanne3, Mouchel, Jean-Marie1, 1 CEREVE, Marne La Vallée, France2 Cemagref, Antony, France3 Cemagref, Lyon, France ABSTRACT- In aquatic ecosystems, dissolved organic matter (DOM) can greatly affect bioavailability of polycyclic aromatic hydrocarbons (PAHs) to pelagic organisms. Since they strongly bind PAHs, humic substances have been extensively studied. However, no comprehensive study of the effect of other DOM components is available. In this study, the effect of different types of DOM on bioaccumulation of fluoranthene, pyrene and benzo[a]pyrene in Daphnia magna was investigated. The general objective was to evaluate the evolution of the bioavailability of PAHs along the naturally occurring processes of mineralization of DOM and production of refractory matter. Among tested DOM were humic substances, DOM from waste water treatment plant outflows, highly degradable DOM compounds such as algae or animal extracts. In exposure media, DOM concentrations ranged between 0 and 30 mg/L DOC. Bioaccumulation of fluoranthene was slightly reduced by humic substances and unaffected by other substances tested. Pyrene and benzo[a]pyrene were much more significantly affected by humic substances and significant reductions of bioaccumulation could be demonstrated with more labile DOM. For both PAHs, the decrease was the strongest with humic substances and the less pronounced with highly biodegradable DOM. Assuming that organically bound PAHs become unavailable, the relative reduction of bioaccumulation can be expressed as a function of the partition coefficient for PAH KDOC. In this study decreases of bioaccumulation were used to "biologically" estimate KDOC. Our results confirm the great ability for humic substances to reduce the bioaccumulation of PAHs. More interestingly they show that non-humic and degradable DOM can also significantly affect their bioavailability. Key words: polycyclic aromatic hydrocarbons, bioaccumulation, dissolved organic matter, Daphnia magna |
