Photochemical degradation increases polycyclic aromatic hydrocarbon (PAH) toxicity to the grouper Epinephelus marginatus as assessed by multiple biomarkers.

The effects of halogen-light-irradiated and non-irradiated PAHs on the grouper Epinephelus marginatus were assessed through biomarkers including morphometric parameters, liver histopathology, biliary PAH concentration, genetic alterations, and enzyme activity modulation. E. marginatus juveniles were divided into three groups: control (C), non-irradiated PAHs (PAHs1), and irradiated PAHs (PAHs2). Test groups were exposed for 14 days to a 0.5 ppm PAH solution in the semi-static system. After this period, fish were anesthetized with benzocaine (2%) and peripheric blood was collected by caudal puncture. Blood smears were prepared and stained with propidium iodide. Fish livers were collected, fixed in McDowell's solution, embedded in paraplast, thin-sectioned, and stained with hematoxylin-eosin (H&E). For biochemical analyses including superoxide dismutase, catalase, and glutathione S-transferase activities, fish livers were collected and preserved in liquid nitrogen. Water samples were analyzed using gas chromatography-mass spectrometry (GC-MS) and bile synchronous fluorescence spectroscopy. Fish in the PAHs2 group had micronuclei (MN) in blood cells, as well as significant differences in nuclear morphology (NMA). Significant morphological alterations were observed in the livers from fish exposed to PAHs as well as inhibition of the catalase activity. Our results show that irradiation altered the bioavailability of PAHs, especially benzanthracene, which has great impact in aquatic ecosystems. Among the consequences of physical and chemical changes to PAHs, we observed a significant increase in NMA and MN incidence in E. marginatus erythrocytes, indicating the potential initiation of mutagenic and carcinogenic processes.

Hybrid sequential treatment of aromatic hydrocarbon-polluted effluents using non-ionic surfactants as solubilizers and extractants.

A treatment train combining a biological and a physical approach was investigated for the first time in order to remediate polycyclic aromatic hydrocarbons (PAHs)-polluted effluents. Given the hydrophobic nature of these contaminants, the presence of non-ionic surfactants is compulsory to allow their bioavailability. The presence of these surfactants also entails an advantage in order to ease contaminant removal by the formation of aqueous two-phase systems (ATPS). The segregation ability of environmentally benign salts such as potassium tartrate, citrate, and oxalate was discussed for extracting phenanthrene (PHE), pyrene (PYR), and benzo[a]anthracene (BaA). The biological remediation efficiency reached circa 60% for PHE and PYR, and more than 80% for BaA. The coupling of ATPS subsequent stage by using potassium citrate allowed increasing the total PAH remediation yields higher than 97% of PAH removal. The viability of the proposed solution was investigated at industrial scale by using the software tool SuperPro Designer.