Preliminary hazard assessment of a new nature-inspired antifouling (NIAF) agent.

A recently synthesized aminated 3,4-dioxygenated xanthone (Xantifoul2) was found to have promising antifouling (AF) effects against the settlement of the macrofouler Mytilus galloprovincialis larvae. Preliminary assessment indicated that Xantifoul2 has reduced ecotoxicological impacts: e.g., being non-toxic to the marine crustacea Artemia salina (<10 % mortality at 50 µM) and showing low bioconcentration factor in marine organisms. In order to meet the EU Biocidal Product Regulation, a preliminary hazard assessment of this new nature-inspired antifouling (NIAF) agent was conducted in this work. Xantifoul2 did not affect the swimming ability of the planktonic crustacean Daphnia magna, the growth of the diatom Phaeodactylum tricornutum, and the cellular respiration of luminescent Gram-negative bacteria Vibrio fischeri, supporting the low toxicity towards several non-target marine species. Regarding human cytotoxicity, Xantifoul2 did not affect the cell viability of retinal human cells (hTERT-RPE-1) and lipidomic studies revealed depletion of lipids involved in cell death, membrane modeling, lipid storage, and oxidative stress only at a high concentration (10 µM). Accelerated degradation studies in water were conducted under simulated sunlight to allow the understanding of putative transformation products (TPs) that could be generated in the aquatic ecosystems. Both Xantifoul2 and photolytic-treated Xantifoul2 in the aqueous matrix were therefore evaluated on several nuclear receptors (NRs). The results of this preliminary hazard assessment of Xantifoul2, combined with the high degradation rates in water, provide strong evidence of the safety of this AF agent under the evaluated conditions, and provide the support for future validation studies before this compound can be introduced in the market.

Emerging pollutants in textile wastewater: an ecotoxicological assessment focusing on surfactants.

Water and several chemicals, including dyestuffs, surfactants, acids, and salts, are required during textile dyeing processes. Surfactants are harmful to the aquatic environment and induce several negative biological effects in exposed biota. In this context, the present study aimed to assess acute effects of five surfactants, comprising anionic and nonionic classes, and other auxiliary products used in fiber dyeing processes to aquatic organisms Vibrio fischeri (bacteria) and Daphnia similis (cladocerans). The toxicities of binary surfactant mixtures containing the anionic surfactant dodecylbenzene sulfonate + nonionic fatty alcohol ethoxylate and dodecylbenzene sulfonate + nonionic alkylene oxide were also evaluated. Nonionic surfactants were more toxic than anionic compounds for both organisms. Acute nonionic toxicity ranged from 1.3 mg/L (fatty alcohol ethoxylate surfactant) to 2.6 mg/L (ethoxylate surfactant) for V. fischeri and from 1.9 mg/L (alkylene oxide surfactant) to 12.5 mg/L (alkyl aryl ethoxylated and aromatic sulfonate surfactant) for D. similis, while the anionic dodecylbenzene sulfonate EC50s were determined as 66.2 mg/L and 19.7 mg/L, respectively. Both mixtures were very toxic for the exposed organisms: the EC50 average in the anionic + fatty alcohol ethoxylate mixture was of 1.0 mg/L ± 0.11 for V. fischeri and 4.09 mg/L ± 0.69 for D. similis. While the anionic + alkylene oxide mixture, EC50 of 3.34 mg/L for D. similis and 3.60 mg/L for V. fischeri. These toxicity data suggested that the concentration addition was the best model to explain the action that is more likely to occur for mixture for the dodecylbenzene sulfonate and alkylene oxide mixtures in both organisms. Our findings also suggest that textile wastewater surfactants may interact and produce different responses in aquatic organisms, such as synergism and antagonism. Ecotoxicological assays provide relevant information concerning hazardous pollutants, which may then be adequately treated and suitably managed to reduce toxic loads, associated to suitable management plans.

Ecotoxicological assessment of biomass-derived furan platform chemicals using aquatic and terrestrial bioassays.

An environmental toxicological assessment of fourteen furanic compounds serving as valuable building blocks produced from biomass was performed. The molecules selected included well studied compounds serving as control examples to compare the toxicity exerted against a variety of highly novel furans which have been additionally targeted as potential or current alternatives to biofuels, building blocks and polymer monomers. The impact of the furan platform chemicals targeted on widely applied ecotoxicity model organisms was determined employing the marine bioluminescent bacterium Aliivibrio fischeri and the freshwater green microalgae Raphidocelis subcapitata, while their ecotoxicity effects on plants were assessed using dicotyledonous plants Sinapis alba and Lepidium sativum. Regarding the specific endpoints evaluated, the furans tested were slightly toxic or practically nontoxic for A. fischeri following 5 and 15 min of exposure. Moreover, most of the building blocks did not affect the growth of L. sativum and S. alba at 150 mg L-1 for 72 h of exposure. Specifically, 9 and 11 out of the 14 furan platform chemicals tested were non-effective or stimulant for L. sativum and S. alba respectively. Given that furans comprise common inhibitors in biorefinery fermentations, the growth inhibition of the specific building blocks was studied using the industrial workhorse yeast Saccharomyces cerevisiae, demonstrating insignificant inhibition on eukaryotic cell growth following 6, 12 and 16 h of exposure at a concentration of 500 mg L-1. The study provides baseline information to unravel the ecotoxic effects and to confirm the green aspects of a range of versatile biobased platform molecules.

The Removal of Binary Mixture of Dyes by Heterogeneous Fenton Oxidation: Kinetics, Product Identification and Toxicity Assessment.

The removal of mixture of two azo dyes, Acid blue 29 and Ponceau xylidine, was studied by heterogeneous Fenton and Fenton-type processes using hydrogen peroxide and sodium persulphate as oxidants in the presence of and nano and micro- particles as catalysts. The synthesised nano- particles were characterised using analytical techniques viz. FT-IR, TEM, EDX, powder XRD and VSM. We have examined the effects of particle size on the COD removal efficiency and the reusability of the catalyst after optimising pH, and concentrations of catalyst and oxidant. Combination of nano-  and hydrogen peroxide possessed higher COD removal efficiency, which was accelerated in acidic pH and inhibited at pH > 6. Total consumption of hydrogen peroxide confirmed the efficiency of the optimised parameters. The mechanism of the formation of intermediate ions and products are proposed. COD removal and consumption of hydrogen peroxide follow pseudo-first-order kinetics. The toxicity of the solutions was assessed using Aliivibrio fischeri light loss and Escherichia coli growth inhibition assays. Both the assays showed different toxicity levels for the same solution.

Toxicity assessment of total petroleum hydrocarbons in aquatic environments using the bioluminescent bacterium Aliivibrio fischeri.

Toxicity monitoring of environmental pollutants especially petroleum hydrocarbons as priority pollutants is an important environmental issue. This study addresses a rapid, sensitive and cost effective method for the detection of total petroleum hydrocarbons (TPHs) using Aliivibrio fischeri bioluminescence inhibition bioassay. At the first step, the optimum conditions including time, pH and temperature for growth of A. fischeri were determined. Then, two methods were used to evaluate the toxicity of petroleum compounds. In the first method, short-term (15 min) and long-term (16 h) toxicity assays were performed. In the second method luminescence kinetics of A. fischeri was investigated during 24 h. The results demonstrated the most appropriate time for the bacterial growth occurred 16 h after inoculation and optimum temperature and pH were found 25 °C and 7, respectively. Short-term and long-term toxicity did not indicate any toxicity for various concentrations of TPHs (30, 50, 110, 160, 220 mg/L). Considering the luminescence kinetics of A. fischeri the long-term assay was introduced as 6 h. The half maximal effective concentration (EC50) was achieved 1.77 mg/L of TPHs. It is concluded that the luminescence kinetics of A. fischeri can be a valuable approach for assessing toxicity of TPHs in aquatic environments.

Modelling quantitative structure activity-activity relationships (QSAARs): auto-pass-pass, a new approach to fill data gaps in environmental risk assessment under the REACH regulation.

Reviewing the toxicological literature for over the past decades, the key elements of QSAR modelling have been the mechanisms of toxic action and chemical classes. As a result, it is often hard to design an acceptable single model for a particular endpoint without clustering compounds. The main aim here was to develop a Pass-Pass Quantitative Structure-Activity-Activity Relationship (PP QSAAR) model for direct prediction of the toxicity of a larger set of compounds, combing the application of an already predicted model for another species, and molecular descriptors. We investigated a large acute toxicity data set of five aquatic organisms, fish, Daphnia magna, and algae from the VEGA-Hub, as well as Tetrahymena pyriformis and Vibrio fischeri. The statistical quality of the models encouraged us to consider this alternative for the prediction of toxicity using interspecies extrapolation QSAAR models without regard to the toxicity mechanism or chemical class. In the case of algae, the use of activity values from a second species did not improve the models. This can be attributed to the weak interspecies relationships, due to different aquatic toxicity mechanisms in species.

Assessment of the potential bactericide effect of self-cleaning floors: a proposed protocol.

The antibacterial properties of self-cleaning coatings are based on bactericide nanoparticles (NPs). Ecotoxicity of these NPs have been assessed mostly in suspension, using standard bioassays. Here a protocol is proposed to test actual coating samples, using the Vibrio fischeri bioluminescence inhibition bioassay. The protocol was designed to test bactericide properties of specially coated PVC floors being used in hospital environments under quasinatural conditions, such as prolonged exposure or room temperature. To take into consideration that the light output of the bacteria under prolonged exposure naturally changes, a correction factor is proposed.

Investigation of reactive Blue 19 biodegradation and byproducts toxicity assessment using crude laccase extract from Trametes versicolor.

Crude laccase potency on biodegradation and detoxification of Reactive blue 19 (RB-19) were demonstrated, along with prediction of degradation mechanisms, pathways and byproducts analysis. Trametes versicolor, cultured on pampas grass inflorescence (Cortaderia selloana), yielded the best crude laccase activity (15.36 U/g). 10 U CLE activities demonstrated a biodegradation yield (85%) in 210 min, at pH 4, 50 °C and 200 mg/L RB-19 concentrations. Evolution of a brown color that absorbed maximally at 478 nm was observed during biodegradation. Two methods were adopted for byproducts extraction, three methods for toxicity analysis and four models for kinetic parameters (Km and Vmax) determination. 2-ethylanthracene, 2-hydroxycyclohexa-2,4-dien-1-one, 2(4-methylphenyl)-ethan-1-amine, 1-[6-hydroperoxy-4,5-bis(sulfooxy)oxan-3-yl]triaza-1,2-dien-2-ium, naphthalene-2,7-disulfonic acid and N-[(5-oxooxolan-2-yl)methyl]acetamide were detected as toxic byproducts. Brown color evolution was due to 1,1,1-triethyl-3-(methoxycarbonyl)-2,2-dioxo-2λ6-diazathian-1-ium (methoxycarbonyl sulfanyl-triethylammonium hydroxide) inner salt. Increase in color density (light to dark brown) was a function of byproduct(s) biodegradation and polymerization. RB-19 and byproduct acute toxicities were decreased significantly (98% - 6.91%). Kinetic parameters Km (18.05 mg/L) and Vmax (0.31 mg/L. min-1) from the four kinetic models demonstrated higher affinity of CLE to RB-19. CLE yielded a catalytic activity (Vmax/Km =0.017 min-1) demonstrating the flexibility of CLE active site to RB-19 binding over commercial laccase.

Environmental Risk Assessment Resulting from Sediment Contamination with Perfluoroalkyl Substances.

Due to wide use of perfluoroalkyl substances (PFASs) (e.g., in metal-plating, in fire-fighting foam, lubricants) and their resistance to degradation, they occur widely in the environment. The aim of this study was to estimate the environmental risk resulting from the presence of PFASs in the Gulf of Gdansk. Therefore, 17 PFASs concentrations were determined using ultra performance liquid chromatography with tandem mass spectrometry detection (UPLC-MS/MS). Additionally, sediment ecotoxicity was investigated. The results of the chemical analysis were used to asses environmental risk of PFASs. In samples collected around discharge collectors from a wastewater treatment plant and the Vistula mouth, Σ17PFASs values were 0.00403 ÷ 40.6 and 0.509 ÷ 614 ng/g d.w., respectively. In samples collected around discharge collectors, PFHxA, PFPeA, PFHpA, and PFOA were dominating, while at the Vistula River mouth, PFHxS, PFDS, and PFBS were prevalent. For most sediments, no toxic effect was observed in the toxicity tests with Heterocypris inconguens and Aliivibrio ficsheri. There was no observed correlation between the PFASs level and their ecotoxicity. Generally, the results of environmental risk assessment indicate that the PFASs would not generate high impact on the aquatic life (five water samples have shown medium risk related to PFBS and PFDoA).

Toxicity of pharmaceuticals in binary mixtures: Assessment by additive and non-additive toxicity models.

Current risk assessment in many countries, including European Union, is still placing focus on single substances rather than their mixtures, although mixtures are commonly found in the environment. To overcome this problem and gain new insights, six pharmaceuticals, namely: azithromycin (AZM), erythromycin (ERM), carbamazepine (CBA), oxytetracycline (OTC), dexamethasone (DXM), and diclofenac (DCF), were selected in order to analyze their combined toxicity in binary mixtures. Overall, 45 binary mixtures were analyzed. Single component toxicities were determined as well, for modelling purpose. Two most common mathematical models for the description of mixture toxicities were applied: concentration addition (CA) and independent action (IA) model. Comparison of the predicted and experimentally obtained toxicities provided information about the modes of toxicity action in the mixtures. OTC-DCF binary mixture indicated synergism with respect to additive behavior (CA model). All other binary combinations containing OTC or DCF were acting very similarly: the synergism with respect to additive behavior was observed for OTC-CBA and DCF-CBA combinations, while OTC-AZM, OTC-ERM, DCF-AZM and DCF-ERM exhibited antagonistic behavior with respect to CA model. All the remaining binary mixtures indicated additive behavior. The applicability of IA model as a proof of independent toxic action of the components was confirmed in cases of DCF-AZM, DCF-ERM, and OTC-AZM mixtures.

Photolysis and photocatalysis of the non-steroidal anti-inflammatory drug Nimesulide under simulated solar irradiation: Kinetic studies, transformation products and toxicity assessment.

In this study, the degradation of Nimesulide (NIM), a non-steroidal anti-inflammatory drug, using photolysis, heterogeneous (TiO2 in dispersion) and homogeneous (photo-Fenton reactant) photocatalysis, under simulated solar light (SSL) radiation, was investigated. Various parameters affecting the degradation rate of the target compound during the applied processes were optimized. The efficiency of all treatments used (direct photolysis; TiΟ2/SSL; TiΟ2/Η2Ο2/SSL; TiΟ2/S2Ο82-/SSL; Fe3+/H2O2/SSL; Fe3+/S2O82-/SSL and [Fe(C2O4)3]3-/H2O2/SSL) was evaluated by means of initial reaction rate and mineralization. Moreover, the generated transformation products (TPs) by each basic process (photolysis; TiΟ2/SSL and Fe3+/H2O2/SSL) were identified, using liquid chromatography coupled to high resolution mass spectrometry, and their formation kinetic profiles were given. The main transformation routes of NIM were hydroxylation and fragmentation, for all three treatments applied. Finally, toxicity measurements were conducted using Microtox bioassay in order to evaluate the potential risk of NIM and its TPs to aqueous organisms. Although, the acute toxicity increased during the first stages of treatment the final outcome lead to very low toxicity levels even within 60 min of TiO2/SSL treatment. Concluding, the obtained results suggest that the photocatalytic degradation of NIM can lead to its complete elimination and simultaneously to the detoxification of the solution.

Transformation pathway and toxicity assessment of malathion in aqueous solution during UV photolysis and photocatalysis.

In drinking water treatment, complete mineralization of organophosphorus pesticides (OPPs) by UV-based advanced oxidation processes (UV AOPs) is rarely achieved. The formation of intermediate oxidation byproducts would likely have some profound effects on toxicity of the reaction solutions. This study investigated the intermediate oxidation byproducts, transformation pathway and toxicity of malathion solutions during the treatment processes of UV alone, UV/H2O2, UV/TiO2 and UV/Fenton. The main intermediate oxidation byproducts were derived using ultra-performance liquid chromatography - electrospray - time-of-flight mass spectrometry. Thereby the transformation pathway for each of these treatment processes was proposed. The results indicate that in UV photolysis, the transformation pathway of malathion proceeded initially via cleavage of the phosphorus-sulfur bonds while in photocatalysis, the desulfurization from a PS bond to a PO bond was the primary degradation pathway. Interestingly, only in the UV/TiO2 process a small fraction of malathion was found decomposed via a demethylation reaction. At the same time, a toxicity assessment of the treated solutions was conducted by both luminescence inhibition of Vibrio fischeri and inhibition of acetylcholinesterase (AChE). It was found that after UV AOP treatment, the toxicity of the malathion aqueous solution increased sharply. In contrast, no increase in toxicity was observed for the malathion aqueous solution after UV alone treatment. This study demonstrates that the high removal efficiency achieved by OPPs does not imply that detoxification of the water solution has been achieved. On the contrary, the toxicity of the treated solutions by OPPs may be increased significantly depending on the selected treatment processes.

Elimination of trichloroanisoles by UV/H2O2: Kinetics, degradation mechanism, water matrix effects and toxicity assessment.

The elimination of 2,3,6-trichloroanisole (2,3,6-TCA), which produces a musty-earthy off-odor in water, by an ultraviolet (UV)/H2O2 process was assessed. The removal of 88.1% of 2,3,6-TCA in ultrapure water (UPW) was achieved using an initial 2,3,6-TCA concentration of 1 µg L-1 (4.73 nM), a H2O2 concentration of 20 mg L-1 (0.588 mM), a UV intensity of 1.44 mW cm-2 and a pH of 8.2. The reaction was found to be pseudo first order with a rate constant (kobs) of 0.0340 min-1. Both the removal efficiency and kobs increased significantly upon increasing the H2O2 concentration from 10 to 50 mg L-1. The second order rate constant (kHO·,2,3,6-TCA) in competition kinetic trials was determined to be 8.17 × 107 M-1s-1. Degradation products generated during both the UV photolysis and UV/H2O2 treatment of 2,3,6-TCA solutions were analyzed using ultrahigh resolution gas chromatography/mass spectrometry, and the degradation mechanism was proposed. The toxicities of water solutions during both processes were assessed via a luminescence method in conjunction with Vibrio fischeri. The pH and Cl-, HCO3- and natural organic matter concentrations of the aqueous medium were all found to significantly affect the removal of 2,3,6-TCA. The degradation rates of trichloroanisoles (TCAs) in real-world water samples demonstrated that UV/H2O2 has significant potential with regard to controlling TCAs as pollutants in water.

Assessment of water quality from the Blue Lagoon of El Cobre mine in Santiago de Cuba: a preliminary study for water reuse.

The creation of pit lakes is usually an acceptable solution from the landscaping point of view for voids left by discontinued open-pit mines. However, without rehabilitation, these voids represent a potential environmental risk. The aim of the present work was to assess, for the first time, the water quality, i.e., physicochemical characteristics, metal and metalloid (MM) content, and ecotoxicity of the waters of the El Cobre Blue Lagoon, a pit lake formed in an open-pit copper mine in Cuba. Potential effects of rainy season vs. dry season and spatial location (different depths) on water characteristics were considered. Results revealed that water contained was moderately acidic (pH = 4.6 ± 0.2), with high electrical conductivity (EC = 3.02 ± 0.03 mS cm-1), whatever the season. Dissolved oxygen (DO = 9.9 ± 2.0 mg L-1), total dissolved solid (TDS = 7003 ± 245 mg L-1), and sulfate concentration (6556 ± 1410 mg L-1) in the El Cobre Blue Lagoon water were above acceptable limits for sources of surface water as recommended by Cuban standard (NC 1021:2014). High copper (43.6 ± 1.7 mg L-1) and manganese (24.1 ± 1.1 mg L-1) contents were detected. Except for EC, sulfates, chlorides, TDS, nitrates, and phosphates, other physicochemical parameters were stable between dry and rainy seasons (p < 0.05). El Cobre Blue Lagoon waters showed an ecotoxicological impact on Vibrio fischeri. No significant differences were detected between all sampling points in the lake for each parameter monitored for a given time. These first results show the spatial homogeneity but poor quality of waters from El Cobre Blue Lagoon. Remediation processes need to be implemented in order to lessen the human and environmental health risk and favor potential water reuse. We suggest the use of constructed wetlands for water treatment. This preliminary research work can serve to alert Cuban local public authorities to the need to rehabilitate such sites.

Integration of fish cell cultures in the toxicological assessment of effluents.

The pollution by industrial and municipal effluents are major sources of concerns. Fish cell cultures were applied in different strategies of the evaluation of effluents, particularly whole toxicity, toxicity identification evaluation and mode of action studies based in adverse outcome pathways. Whole effluent toxicity was evaluated using a battery of five model systems from four trophic levels: Daphnia magna was the most sensitive system, followed by the hepatoma fish cell line PLHC-1, the bacterium Allivibrio fischeri, the fibroblastic fish cell line RTG-2 and the algae Chlorella vulgaris, detecting a risk of eutrofization. The uptake of neutral red was more sensitive than the content of protein assay. The main morphological alterations observed were cell loss, hydropic degeneration, and a general loss of lysosomes and of their perinuclear distribution. The toxicity was characterized in PLHC-1 cells through toxicity identification evaluation, in which a partial reduction with graduation at pH 11, filtration, aeration and addition of thiosulfate or EDTA was shown; on the other hand, a low sorption in solid phase extraction suggested that the main responsible were not organic compounds. Consequently, it was not necessary to apply an effect directed analysis HPLC fractionation. In the chemical identification phase, Zn, Cd, As, Cu and Pb were quantified in decreasing concentrations. In the toxicity confirmation phase, a reconstituted sample and individual solutions, presented decreasing toxicity: Zn > Pb > As+5 > Cd > Cu > As+3, the global toxicity being explained by response addition. In the last step, the mode of action was investigated using five specific biomarkers. While metallothionein and succinate dehydrogenase activity were increased, no changes occurred for lysosomal function, acetylcholinesterase and EROD activities, the responsibility of the toxicity for the elements found being confirmed.

Comparative assessment of acute and chronic ecotoxicity of water soluble fractions of diesel and biodiesel on Daphnia magna and Aliivibrio fischeri.

The widespread use of diesel as a transportation fuel and the introduction of biodiesel into the world energy matrix increase the likelihood of aquatic contamination with these fuels. In this case, it is important to know the environmental impacts caused by water-soluble fraction (WSF) of these fuels, since it is the portion that can result in long-term impacts and affect regions far away from the location of a spill. Therefore, we evaluated and compared the aquatic ecotoxicity of the WSF of biodiesel and diesel through acute ecotoxicity tests with the aquatic microcrustacean Daphnia magna and the marine bacteria Aliivibrio fischeri, as well as chronic ecotoxicity tests with D. magna. The WSF of diesel was 2.5-4 folds more toxic than the WSF of biodiesel in acute ecotoxicity tests. Similarly, a comparison of the chronic ecotoxicity demonstrated that the WSF of diesel was more toxic than the WSF of biodiesel. WSF of diesel causes chronic effects on reproduction, longevity and growth of D. magna (NOEC was 12.5, 12.5, 6.25%, respectively), while WSF of biodiesel did not present significantly different results compared to the control for any of the parameters evaluated in any of the dilutions tested (NOEC> 25%). To the best of our knowledge, this is the first study that compares the chronic ecotoxicity of WSF of diesel and biodiesel on D. magna.

Degradation of carbendazim in water via photo-Fenton in Raceway Pond Reactor: assessment of acute toxicity and transformation products.

This study aimed at investigating the degradation of fungicide carbendazim (CBZ) via photo-Fenton reactions in artificially and solar irradiated photoreactors at laboratory scale and in a semi-pilot scale Raceway Pond Reactor (RPR), respectively. Acute toxicity was monitored by assessing the sensibility of bioluminescent bacteria (Aliivibrio fischeri) to samples taken during reactions. In addition, by-products formed during solar photo-Fenton were identified by liquid chromatography coupled to mass spectrometry (UFLC-MS). For tests performed in lab-scale, two artificial irradiation sources were compared (UVλ > 254nm and UV-Visλ > 320nm). A complete design of experiments was performed in the semi-pilot scale RPR in order to optimize reaction conditions (Fe2+ and H2O2 concentrations, and water depth). Efficient degradation of carbendazim (> 96%) and toxicity removal were achieved via artificially irradiated photo-Fenton under both irradiation sources. Control experiments (UV photolysis and UV-Vis peroxidation) were also efficient but led to increased acute toxicity. In addition, H2O2/UVλ > 254nm required longer reaction time (60 minutes) when compared to the photo-Fenton process (less than 1 min). While Fenton's reagent achieved high CBZ and acute toxicity removal, its efficiency demands higher concentration of reagents in comparison to irradiated processes. Solar photo-Fenton removed carbendazim within 15 min of reaction (96%, 0.75 kJ L-1), and monocarbomethoxyguanidine, benzimidazole isocyanate, and 2-aminobenzimidazole were identified as transformation products. Results suggest that both solar photo-Fenton and artificially irradiated systems are promising routes for carbendazim degradation.

Triad-based screening risk assessment of the agricultural area exposed to the long-term PAHs contamination.

The aim of the study was ecological risk assessment (ERA) of the agricultural soils located in the vicinity of the highly industrialized area and exposed to different emission sources of polycyclic aromatic hydrocarbons (PAHs). In this study, we demonstrated the combination of generic and site-specific ERA approach for screening assessment and delineation of the area of a high ecological risk. Generic approach was based on a hazard quotient and indicated that 62% of the research area needs further assessment. For site-specific evaluation, the Triad approach was utilized. Information from three lines of evidence (LoE): chemical, ecotoxicological and ecological, was integrated into one environmental risk (EnvRI) index. The chemical risk was derived from toxic pressure coefficients based on the total PAHs concentration. The ecotoxicological LoE included an acute toxicity testing: the luminescent bacteria Aliivibrio fischeri activity in both liquid- and solid-phase samples and the ability of crustacean Thamnocephalus platyurus to food uptake. The ecological LoE comprised microbial parameters related to soil respiration and enzymatic activity. Integrated EnvRI index ranged from 0.44 to 0.94 and was mainly influenced by high values of chemical LoE risk, while the ecotoxicological and ecological LoE indicated no or low risk. Due to the relatively high uncertainty associated with the contradictory information given by LoEs, there is the need to confirm potential risk in a tier 2 analysis.

Assessment the ecotoxicity and inhibition of imidazolium ionic liquids by respiration inhibition assays.

The ecotoxicity and inhibition of 12 imidazolium ionic liquids (ILs) with alkyl chain from C4 to C10 and chloride (Cl-), tetrafluoroborate (BF4-) and bis(trifluoromethanesulfonyl)imide (NTf2-) anions have been studied by means of respiration inhibition assays using activated sludge collected from a wastewater treatment plant. This test represents an alternative easy, economic and quick way to evaluate the true impact of ILs on activated sludge-based wastewater treatment. For comparison purposes, the EC50 values were also determined by the Microtox test (Vibrio fischeri). It was observed that this widely used microbial test overestimates the effect of the ILs on biological wastewater treatment facilities, especially in the case of ILs with lower ecotoxicity. The results of the biological tests showed that the alkyl chain length plays a crucial role in the ecotoxicity of ILs. A significant increase of the toxicity with the length of the n-alkyl chain was found. Regarding to the impact of the anion, the ecotoxicity measured by respiration inhibition assays follows the order NTf2- > Cl- > BF4-, being the anion effect higher as decreasing the length of cation alkyl chain. According to the hazard substances ranking for aquatic organisms (Passino and Smith, 1987), imidazolium ILs with C4 alkyl chain can be classified as "practically harmless" compounds whereas those with alkyl chains C8 or C10 correspond to "highly toxic" species.

Radiolysis of sulfonamide antibiotics in aqueous solution: Degradation efficiency and assessment of antibacterial activity, toxicity and biodegradability of products.

Numerous studies have been published on the radiolysis of sulfonamide antibiotic solutions but little effort has been made to monitor the biological properties of degradation products. A complex approach should also clarify the changes in antibacterial activity and biodegradability, besides the usual screening of toxicity. To fill this gap, the ionizing radiation induced degradation of four sulfonamide antibiotics was investigated in dilute aqueous solutions, with emphasis on the biological assessment of decomposition products. Complete removal of sulfonamides was achieved by a low absorbed dose (1.5kGy). 2-2.5kGy dose was needed to transform the persistent initial molecules to substances biodegradable in both river water and activated sludge. The ratio of the biological and chemical oxygen demand increased from <0.21 to at least 0.59, but values as high as 0.80 were also measured. It was demonstrated that antibacterial activity is due to the initial molecules, as it disappeared when the sulfamethoxazole concentration decreased below the minimal inhibitory concentration (30 µM). This means that the products have no antibacterial activity. Toxicity testing performed on test organisms from three different trophic levels and activated sludge evidenced that the toxicity depends both on the test organism and on the sulfonamide used. The degradation of initial molecules is not always enough to eliminate the environmental risk due to the toxic products formed e.g. inhibitory effects to Vibrio fischeri increased by 34% at 2.5kGy. For this reason, complex biological assessment of treated solutions has to play an important role in development and optimization of advanced treatment techniques.