Characterisation of the dynamics of organic contaminants (n-alkanes, PAHs and PCBs) in a coastal area

摘要

The dynamics of three classes of organic contaminants, namely n-alkanes, polycyclic aromatic hydrocarbons and polychlorinated biphenyls, were evaluated from the settled suspended particulate matter (SPM) of two wastewater treatment plant outlets (O1 and O2) at the Marseille coast. We used a 1-m-high Plexiglas settling column filled with 7 L of seawater to determine the particles' settling rates, size distribution, and the extent of organic contaminants. Six classes of SPM (50-200 mu m particles size) were obtained from 15 fractions of 500-mL successive filtering samples ranging from 30 s to 5 days, including those in the tube wall. The results of the experiment indicated that >68% of the particles settled within 15 min, which highly correlated with the distribution of organic carbon and contaminant contents. Furthermore, we demonstrated that 9%-13% of the SPM, which contained 5%-11% of the organic contaminants, are non-settable even after 5 days. Extrapolating such behaviour in situ using molecular diagnostic indices for organic contaminant source apportionment indicated that these nonsettable contaminant particles are exported to the sea. (C) 2017 Elsevier Ltd. All rights reserved.