Search

Featured Application: These preliminary data on the differences among aquatic microoorganisms in their response to benzo-fused nitrogen heterocyclic pollutants can help in selecting the most suitable biotest for environmental toxicity monitoring activities. The evaluation of the ecotoxicological effects of water pollutants is performed by using different aquatic organisms. The effects of seven compounds belonging to a class of widespread contaminants, the benzo-fused nitrogen heterocycles, on a group of simple organisms employed in reference ISO tests on water quality (unicellular algae and luminescent bacteria) have been assessed to ascertain their suitability in revealing different contamination levels in the water, wastewater, and sediments samples. Representative compounds of benzotriazoles, benzothiazoles, and benzenesulfonamides, were tested at a concentration ranging from 0.01 to 100 mg L−1. In particular, our work was focused on the long-term effects, for which little information is up to now available. Species-specific sensitivity for any whole family of pollutants was not observed. On average, the strongest growth rate inhibition values were expressed by the freshwater Raphidocelis subcapitata and the marine Phaeodactylum tricornutum algae. R. subcapitata was the only organism for which growth was affected by most of the compounds at the lowest concentrations. The tests on the bioluminescent bacterium Vibrio fisheri gave completely different results, further underlining the need for an appropriate selection of the best biosensors to be employed in biotoxicological studies. [ABSTRACT FROM AUTHOR]

The evaluation of the ecotoxicological effects of water pollutants is performed by using different aquatic organisms. The effects of seven compounds belonging to a class of widespread contaminants, the benzo-fused nitrogen heterocycles, on a group of simple organisms employed in reference ISO tests on water quality (unicellular algae and luminescent bacteria) have been assessed to ascertain their suitability in revealing different contamination levels in the water, wastewater, and sediments samples. Representative compounds of benzotriazoles, benzothiazoles, and benzenesulfonamides, were tested at a concentration ranging from 0.01 to 100 mg L−1. In particular, our work was focused on the long-term effects, for which little information is up to now available. Species-specific sensitivity for any whole family of pollutants was not observed. On average, the strongest growth rate inhibition values were expressed by the freshwater Raphidocelis subcapitata and the marine Phaeodactylum tricornutum algae. R. subcapitata was the only organism for which growth was affected by most of the compounds at the lowest concentrations. The tests on the bioluminescent bacterium Vibrio fisheri gave completely different results, further underlining the need for an appropriate selection of the best biosensors to be employed in biotoxicological studies.

The high-efficiency and environmentally-friendly electro-oxidation (EO) would lose its competitive edge because of the production of oxychloride by-products (ClO x −), which has not yet drawn significant attention in academic and engineering communities. In this study, the negative effects of the electrogenerated ClO x − were compared among four commonly used anode materials (BDD, Ti 4 O 7 , PbO 2 and Ru-IrO 2) in terms of ClO x − interference on the evaluation of electrochemical COD removal performance and biotoxicity. Apparently, the COD removal performance of various EO systems were highly enhanced with increasing current density in the presence of Cl−, e.g., the amounts of COD removed by various EO systems from the phenol solution with an initial COD content of 280 mg L−1 at 40 mA cm−2 within 120 min decreased in the order: Ti 4 O 7 of 265 mg L−1 > BDD of 257 mg L−1 > PbO 2 of 202 mg L−1 > Ru-IrO 2 of 118 mg L−1, which was different from the case with the absence of Cl− (BDD of 200 mg L−1 > Ti 4 O 7 of 112 mg L−1 > PbO 2 of 108 mg L−1 > Ru-IrO 2 of 80 mg L−1) and the results after removing ClO x − by anoxic sulfite-based method (BDD of 205 mg L−1 > Ti 4 O 7 of 160 mg L−1 > PbO 2 of 153 mg L−1 > Ru-IrO 2 of 99 mg L−1). These results can be ascribed to the ClO x − interference on COD evaluation, the extent of which decreased in the order: ClO 3 − > ClO− (where ClO 4 − cannot impact COD test). The highest overrated electrochemical COD removal performance of Ti 4 O 7 may be associated with its relatively high production of ClO 3 − and the low mineralization extent. The chlorella inhibition ratio of ClO x − decreased in the order: ClO− > ClO 3 − >> ClO 4 −, which accounted for the biotoxicity increasement of the treated water (PbO 2 68%, Ti 4 O 7 56%, BDD 53%, Ru-IrO 2 25%). Generally, the inevitable problems of overrated electrochemical COD removal performance and biotoxicity increasement induced by ClO x − should deserve significant attention and effective countermeasures should be also developed when employing EO process for wastewater treatment. [Display omitted] • ClO x − induced an over-evaluated electrochemical COD removal performance. • Biotoxicity increasement of the EO-treated effluents was highly pertinent to ClO x −. • Anoxic sulfite-based reduction protocol was utilized to remove ClO x − interference. • Real electrochemical COD removal performance was obtained after ClO x − removal. [ABSTRACT FROM AUTHOR]

The photodegradation process of seven glucocorticoids (GCs), cortisone (CORT), hydrocortisone (HCORT), betamethasone (BETA), dexamethasone (DEXA), prednisone (PRED), prednisolone (PREDLO) and triamcinolone (TRIAM) was studied in tap and river water at a concentration close to the environmental ones. All drugs underwent sunlight degradation according to a pseudo-first-order decay. The kinetic constants ranged from 0.00082 min -1 for CORT to 0.024 min -1 for PRED and PREDLO. The photo-generated products were identified by high-pressure liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The main steps of the degradation pathways were the oxidative cleavage of the chain 17 for CORT, HCORT and the rearrangement of the cyclohexadiene moiety for the other GCs. The acute and chronic toxicity of GCs and of their photoproducts was assessed by the V. fischeri and P. subcapitata inhibition assays. The bioassays revealed no significant differences in toxicity between the parent compounds and their photoproducts, but the two organisms showed different responses. All samples produced a moderate acute toxic effect on V. fisheri and no one in the chronic tests. On the contrary, evident hormesis or eutrophic effect was produced on the algae, especially for long-term contact.