engleski

Assessment of hazardous organic contamination in freshwater sediments impacted by industrial effluents

There have been several reports in the literature, which indicated that the presence of toxic anthropogenic chemicals in aquatic sediments represents a significant hazard to the benthic systems (Ho et al. 2002). Toxicant classes, indicated to cause adverse effects in aquatic sediments, include ammonia, metals and various organics. Despite the fact that contaminated sediments contain rather complex assemblages of ecotoxic chemical compounds, monitoring programmes are most frequently directed towards just a few classes of regulated pollutants, such as polycyclic aromatic hydrocarbons and PCBs (Gomez-Guiterrez et al. 2007). The aim of this study was to investigate chemical composition of hazardous organic compounds and their toxic potential in freshwater sediments from a small creek, which was heavily impacted by industrial effluents. The Gorjak creek, situated near Zagreb, Croatia, is a small freshwater system, which receives high amounts of industrial wastewaters from baker’s yeast production and manufacture of pharmaceuticals. The creek sediments were extracted using accelerated solvent extraction, employing accelerated solvent extraction (ASE). The extracts were divided into two equal aliquots for chemical analyses and bioassays. In order to facilitate positive identification of non-target compounds in the complex sediment matrices, before instrumental analysis the extracts were fractionated on a simple column filled with 5 g of deactivated (15 % water) silica gel using sequential elution with A) n-hexane, B) dichloromethane and C) methanol. The chemical analyses employed gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/time-of-flight mass spectrometry (LC/Q-ToF), while the battery of bioassays included determination of chronic toxicity with unicellular algae Selenastrum capricornutum, EROD activity in the PLHC-1 cells, glutathione S-transferase (GST) activity in the PLHC-1 cells, inhibitors the multixenobiotic resistance mechanism (MXR), the Ames test and Yeast Estrogen Screen (YES) assay. Comprehensive characterisation of freshwater sediments from the Gorjak creek, using two complementary mass spectrometric techniques and bioassays, indicated a significant contamination by several classes of organic compounds, suggesting that the system requires a thorough remediation. A very good agreement between chemical methods and bioassays was observed. The classical pollutants such as PAH were well-correlated with the EROD activity, while the maximal P-glycoprotein inhibition was found in the polar fraction, which was dominated by several pharmaceutical compounds. References Ho K T, Burgess R M, Pelletier M C, Serbst J R, Ryba S A, Cantwell M G, Kuhn A, Raczelowski P (2002) An overview of toxicant identification in sediments and dredged materials. Mar Poll Bull 44: 286-293. Gomez-Guiterrez A, Garnacho E, Bayona J, Albaiges J, Screening ecological risk assessment of persistent organic pollutants in Mediterranean sea sediments. Environ International 33: 867-876.

organic contaminants ; freshwater sediments ; mass spectroemtry ; bioassays

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