Use of effect-directed analysis for the identification of organic toxicants in surface flow constructed wetland sediments.

Wetlands constitute one of the most efficient ecosystems with a great capacity to recycle the organic matter and able to attenuate or mitigate the chemical pollution. However, limited information exists on the ecotoxicological effects that may be caused due to the presence of these pollutants in wetland sediments. In this work, a bioassay-directed approach was used to identify toxicologically active compounds retained in sediments from a surface flow constructed wetland located in the North-Eastern of Spain. Sediment fractionation was accomplished by pressurized-liquid extraction (PLE) followed by semipreparative normal phase high performance liquid chromatography (NP-HPLC). During the extraction procedure, different solvents were sequentially applied in order to selectively extract the compounds as a function of their polarity. The cytotoxicity of the resulting fractions was assessed on the fish hepatoma cell line PLHC-1 by using the thiazolyl blue tetrazolium bromide (MTT) assay, while the presence of CYP1A inducing agents was determined by measuring the activity 7-ethoxyresorufin-O-deethylase (EROD) in exposed cells. Identification of the compounds was performed by gas chromatography coupled to mass spectrometry (GC/MS). Compounds such as polycyclic aromatic hydrocarbons (PAHs), non-steroidal anti-inflammatory drugs (NSAIDs), polycyclic musk fragrances and pesticides were identified in the most toxic fractions.