Wastewater reuse has been addressed to promote the sustainable water utilization in textile industry. However, conventional technologies are unable to deliver treated wastewater with the quality required for reuse, mainly due to the presence of dyes and high salinity. In this work, the feasibility of electrooxidation, using a boron-doped diamond anode, to provide treated textile dyeing wastewater (TDW) with the quality required for reuse, and with complete recovery of salts, was evaluated. The influence of the applied current density on the quality of treated TDW and on the consecutive reuse in new dyeing baths was studied. The ecotoxicological evaluation of the process towards Daphnia magna was performed. After 10 h of electrooxidation at 60 and 100 mA cm−2, discolorized treated TDW, with chemical oxygen demand below 200 (moderate-quality) and 50 mg L−1 (high-quality), respectively, was obtained. Salt content was unchanged in both treatment conditions, enabling the consecutive reuse without any salt addition. For the two reuse cycles performed, both treated samples led to dyed fabrics in compliance with the most restrictive controls, showing that an effective consecutive reuse can be achieved with a moderate-quality water. Besides the water reuse and complete salts saving, electrooxidation accomplished an ecotoxicity reduction up to 18.6-fold, allowing TDW reuse without severe ecotoxicity accumulation.

Antineoplastic agents, vital components of cancer chemotherapy, are designed to inhibit tumor cell proliferation through interactions with DNA and modifications of cellular growth factors. Their release into municipal and hospital effluents raises concerns about potential risks to non-target aquatic organisms, especially when they coexist in complex mixtures. This study investigates the immobilisation, antioxidant and biochemical response and neurotransmission of Daphnia magna when exposed to two distinct antineoplastic agents, doxorubicin (DOX) and oxaliplatin (OXA), with the objective to evaluate the impact of their single and mixture toxic effects. The combined toxicities were assessed using two distinct models, Concentration Addition and Independent Action, alongside with their possible deviations, like synergism, (causing a more severe effect) or antagonism (less severe effect), effects dependent on “dose level” (different deviations at high and low concentration levels) or those dependent on “dose ratio” (deviations depend on the mixture’s composition). Acute effects of single exposure after 48 hours found a fifty percent of immobilisation of D. magna occuring at EC50=0.79 mg/L of DOX and at EC50=59.61 mg/L of OXA. Mixture exposure of DOX and OXA displayed a better fit for dose ratio deviation patterns for both models, showing synergism at higher OXA concentrations while antagonism was mainly caused by increasing DOX concentrations. The evaluation of biomarkers for neurotoxicity, oxidative stress, and cell membrane damage was conducted through D. magna’s exposure to sub-lethal concentrations of DOX and OXA. Biomarkers included Acetylcholinesterase, Catalase, Glutathione peroxidase, Glutathione Reductase, Glutathione S-transferase, Electron Transport System, Cytochrome c Reductase activities, and Lipid Peroxidation. Biomarker analysis elucidates that different mechanisms have been employed to attenuate the cellular-level impact of oxidative stress induced by each isolated antineoplastic on Daphnia. When exposed to mixtures, it is observed a decrease on acetylcholinesterase, especially at higher concentrations of OXA. The ecotoxicological data presented in this study not only highlight the potential environmental risk associated with anticancer drugs, particularly concerning their synergistic effects, but also emphasize the importance of integrating statistical models to assess the environmental impact of these compounds, as their behaviour will be different to the impact the single stressors induce.

Carbon-based nanomaterials exhibit unique properties that make them suitable for a wide variety of industrial and biomedical applications. In this work, we studied the acute toxicity of graphite-diamond nanoparticles (GDN) combined with the fungicide thiabendazole (TBZ) to the immobilization of the cladoceran Daphnia magna in the presence and absence of the micro green algae Raphidocelis subcapitata, supplied as food source. The toxicity of GDN to D. magna decreased in the presence of R. subcapitata, while that of TBZ increased, the latter suggesting a carrier effect to TBZ. GDN-TBZ mixtures were fitted to the most common conceptual models applied to mixture toxicity: Concentration Addition (CA), Independent Action (IA) and Combination Index (CI). For GDN-TBZ mixtures in the absence of food the best fit was obtained with dose ratio deviation from CA model, while in the presence of food, dose level deviation from CA gave a better fit. The binary mixtures of GDN and TBZ showed synergistic toxic interactions at low concentrations, which could be attributed to the increased bioavailability of TBZ adsorbed on GDN. For higher concentrations of GDN, the binary mixtures turned antagonistic due to particle agglomeration. Our study provides evidence that deviations from additivity are dose dependent and relevant for the risk assessment of mixtures of nanoparticles with other chemical pollutants.

Assessing the impact of uranium mining industry on aquatic ecosystems near mining areas is critical to ensure the long-term health and sustainability of ecosystem services. As so, a transgenerational study with Daphnia magna has been conducted to perceive to what extent intermittent discharges of uranium mine effluents into watercourses may impact the DNA integrity and life history traits of cladocerans. Organisms were exposed for 48 h to a 2% dilution of an uranium mine effluent (UME) and to a corresponding dose of waterborne uranium (WU) that, according to our preliminary studies, induces significant DNA damage in daphnids. After exposure, organisms were transferred to clean medium, where three successive generations were monitored for genotoxicity and other effects at the individual and population level. Despite some differences between WU and UME data, our results revealed that the negative impacts of the short-term exposure gradually disappeared after placing the organisms in clean medium. These results suggest that, under intermittent stress, daphnids are able to recover, since after the 3rd brood release, DNA damage (measured as DNA strand breaks) is no longer observed and has no significant impact on the detectable life traits of offspring. Although our results indicate that populations of D. magna are not affected by intermittent and highly diluted discharges from uranium mining, aquatic systems under this kind of pressure should not be seen as hazardous-free. Future studies in this field are recommended and these should consider radionuclides in the water column, their accumulation in the sediments and also multiple life stages.

O uso de pesticidas é objecto de controvérsia: são geralmente necessários para o sucesso da produção agrícola, mas a contaminação do solo e de sistemas aquáticos (e.g. lagos e rios) é prejudicial para muitas espécies. A utilização de insecticidas é particularmente preocupante porque grande parte da biomassa aquática é composta por artrópodes semelhantes aos organismos-alvo (pragas). A utilização das biomoléculas de ADN e dos seus mecanismos operativos (e.g. formação de ARN mensageiro durante a síntese proteica) é uma das mais recentes biotecnologias aplicadas à análise dos efeitos nefastos de compostos tóxicos. De uma forma simplificada, sabendo que, em condições controlo, um organismo aquático produz X moléculas de ARNm, ao observar que, após exposição a um insecticida, produz 2X ou -2X, pode concluir-se que o organismo foi afectado pela exposição. Posteriormente analisando a função dos genes envolvidos neste processo, pode concluir-se acerca dos mecanismos biológicos que foram inibidos ou estimulados, podendo estimar-se riscos do insecticida para o ecossistema. O objectivo deste estudo foi verificar as alterações na expressão genética de um zooplanctonte (Daphnia magna) após exposição a Metomil, um insecticida muito usado em Portugal. Para tal, utilizou-se um chip de ADN (microarray), que permite o estudo da expressão de milhares de genes numa só leitura.

Este trabalho foi desenvolvido no âmbito do projeto EPIBOOST e teve como objectivo principal estudar o efeito tóxico do cádmio no microcrustáceo de água doce Daphnia magna, num contexto de alterações climáticas. Assim, o principal objetivo deste trabalho foi comparar a sensibilidade de D. magna a cádmio, em três temperaturas diferentes, 15°C, 20°C e 25°C. As culturas foram mantidas em condições controladas de temperatura (15°C, 20°C e 25°C) e fotoperíodo (16L:8N), utilizando meio ASTM, extrato de Ascophyllum nodosum e Raphidocellis subcapitata como fonte de alimento. Foi testada uma gama fixa de sete concentrações de cádmio (2,1 mg/L - 238 mg/L) nas três temperaturas, de acordo com a diretriz da OECD para o teste de imobilização aguda de Daphnia sp. De acordo com os resultados, a temperatura mostrou influenciar a sensibilidade dos organismos a este poluente. Temperaturas mais elevadas aumentaram a sensibilidade ao metal, resultando numa diminuição dos valores de EC (15º C - não se registou imobilização; 20º C - EC50 = 32.294 mg/L; e 25º C - EC50 = 2.130 mg/L). Este trabalho contribuiu para demostrar a influência negativa do aquecimento global num organismo modelo, com um papel essencial na saúde do ecossistema.

The induction of RIBE (Radiation Induced Bystander Effect) is a non-target effect of low radiation doses that has already been verified at an inter-organismic level in fish and small mammals. Although the theoretical impact in the field of environmental risk assessment (ERA) is possible, there is a gap of knowledge regarding this phenomenon in invertebrate groups and following environmentally relevant exposures. To understand if RIBE should be considered for ERA of radionuclide-rich wastewaters, we exposed Daphnia magna (<24 h and 5d old) to a 2% diluted uranium mine effluent for 48 h, and to a matching dose of waterborne uranium (55.3 μg L-1). Then the exposed organisms were placed (24 and 48 h) in a clean medium together with non-exposed neonates. The DNA damage observed for the non-exposed organisms was statistically significant after the 24 h cohabitation for both uranium (neonates p = 0.002; 5 d-old daphnids p = <0.001) and uranium mine effluent exposure (only for neonates p = 0.042). After 48 h cohabitation significant results were obtained only for uranium exposure (neonates p = 0.017; 5 d-old daphnids p = 0.013). Although there may be some variability associated to age and exposure duration, the significant DNA damage detected in non-exposed organisms clearly reveals the occurrence of RIBE in D. magna. The data obtained and here presented are a valuable contribution for the discussion about the relevance of RIBE for environmental risk assessment.

Mudanças climáticas podem alterar a dinâmica de ecossistemas e, sendo um problema que atualmente motiva preocupações, tem integrado agendas internacionais, designadamente no âmbito das Nações Unidas e da União Europeia. Numa perspetiva de Educação para Desenvolvimento Sustentável (EDS), importa promover o desenvolvimento de competências necessárias à compreensão de dimensões sociais e económicas de mudanças ambientais globais, em particular as relacionadas com comportamentos quotidianos necessários para implementar estratégias de resolução ou mitigação de problemas ambientais. Neste texto apresentam-se e discutem-se atividades realizadas com alunos do Ensino Secundário, no âmbito do programa de Ocupação Científica de Jovens nas Férias 2010, em se procurou envolvê-los na aprendizagem de conceitos estruturantes em Biologia, abordando problemas globais atuais, associados a alterações climáticas (e.g. salinização de lagoas costeiras de água doce e aumento de temperatura). As atividades práticas realizadas incluíram um design experimental: duas espécies de cladóceros de água doce (Daphnia longispina e Daphnia magna) foram sujeitas a agentes de stress abióticos – salinidade e temperatura. Verificou-se que a salinidade, em conjunto com a temperatura, pode causar perturbações em populações das espécies de cladóceros estudadas e, consequentemente, alterar a sua função na regulação das teias tróficas, e.g. num lago, comprometendo todo o ecossistema. Com base na observação dos desempenhos dos alunos e na análise das suas respostas a um questionário de avaliação, verificou-se que as atividades práticas realizadas fomentaram o desenvolvimento de competências necessárias para tratar e interpretar dados, assim como para estabelecer relações entre os resultados obtidos e problemas ambientais.

Complex mixtures makes the assessment of environmental hazards difficult due to possible antagonistic or synergistic interactions that can occur between chemicals, or even more complex effect patterns like dose-level or dose-ratio dependent responses. The aim of the present work was to investigate the acute and sublethal responses of Daphnia magna Straus exposed to four single chemical compounds (imidacloprid, thiacloprid, nickel chloride, and chlorpyrifos) and three binary chemical mixtures. In the immobilization and feeding inhibition bioassays, chlorpyrifos was the most toxic to D. magna, followed by nickel chloride, and imidacloprid and thiacloprid, which showed similar levels of toxicity. The MIXTOX was used to evaluate mixture toxicity. Observed data was compared with the expected mixture effects predicted by concentration addition (CA) and independent action (IA) models; deviations for synergistic/antagonistic interactions, dose-level and dose-ratio dependency were also used. In the mixture toxicity assessment, several patterns of response were obtained depending on the mixture but also on the endpoint tested. For imidacloprid and thiacloprid, deviations for synergism were observed in acute exposures (immobilization), and antagonism for feeding rates at sublethal concentrations. For imidacloprid and chlorpyrifos, antagonism was found in both exposures. In the nickel and chlorpyrifos case study, deviations for synergism were observed in the acute exposure; a dose-ratio deviation was observed in the feeding inhibition test, with a pattern for antagonism, except for where nickel exerts more than 60% of the mixture toxicity. Environ. Toxicol. Chem. 2010;29:1716-1726. (C) 2010 SETAC

Freshwater reservoirs can be impacted by several hazardous substances through inputs from agricultural activity, sewage discharges, and groundwater leaching and runoff. The water quality assessment is very important for implementation of the monitoring and remediation programs to minimize the risk promoted by hazardous substances in aquatic ecosystems. Evaluation of the degree of contamination of aquatic environments must not take in account only its chemical characterization but it must be complemented with biological assays, which determine potential toxic effects and allows an integrated evaluation of its effects in populations and aquatic ecosystem communities. The application of this type of strategy has clear advantages allowing a general evaluation of the effects from all the water components, including those due to unknown substances and synergic, antagonistic, or additive effects. There are only a few studies that reported ecotoxicological acute end points, for the assessment of surface water quality, and the relationship among toxicity results and the anthropogenic pollution sources and the seasonal period. The aim of this study was to assess the ecotoxicological characterization of the surface water from Alqueva reservoir (South of Portugal) and to evaluate the influence of anthropogenic sources of pollution and their seasonal variation in its toxicity. The construction of Alqueva reservoir was recently finished (2002) and, to our knowledge, an ecotoxicological assessment of its surface water has not been performed. Because of that, no information is available on the possible impact of pollutants on the biota. The surface water toxicity was assessed using acute and chronic bioassays. The results are to be used for developing a monitoring program, including biological methods. Water samples were collected during 2006-2007, at each of the nine sampling sites selected in Alqueva reservoir. These sampling points allow an assessment at the upstream (Sra. Ajuda, Alcarrache, Alamos-Capta double dagger o), at the middle (Alqueva-Montante, Alqueva-Mouro, Lucefecit), and at the downstream of the water line (Alqueva-Jusante; Ardila-confluncia; Moinho das Barcas). The campaigns occurred in February, March, May, July, September, and November of 2006 and February, March, and May of 2007. The rainy season comprised November, February, and March, and the dry season included May, July, and September. A total of 81 samples were collected during the study period. The physical-chemical parameters were analyzed following standard and recommended methods of analysis (APHA et al. 1998). The pesticide analyses were performed using gas chromatography according to DIN EN ISO 6468 (1996). Surface water ecotoxicity was evaluated using the following bioassays: Vibrio fischeri luminescence inhibition, Thamnocephalus platyurus mortality, and Daphnia magna immobilization and reproduction assay. The Spearman rank correlation coefficients were used to evaluate the associations between the water sample physicochemical properties (from each sampling station in each season) and the acute and chronic toxicological effects, with a level of significance p < 0.05. In the acute toxicity study, the species that was found to be the most sensitive was T. platyurus. T. platyurus detected a higher number of toxic water samples during the dry season. Concerning the luminescent inhibition of V. fischeri, the results showed that this organism detected a great number of toxic water samples in rainy seasons. The water samples, which promoted higher toxic effects towards this species, were from the north and from the middle of the reservoir. The correlation analysis showed that V. fischeri luminescent inhibition (%) was positively correlated with total phosphorus, chlorpyrifos, iron, and arsenic. T. platyurus mortality (%) was positively correlated with the water pH, 5-day biochemical oxygen demand (BOD(5)), chlorides, atrazine, simazine, terbuthylazine, and endosulfan sulfate contents. Although the surface waters did not promote acute toxicity to the crustacean D. magna, in the chronic exposure, a significant decrease in the number of juveniles per female was observed, mainly at the dry period. The number of juveniles per female, in the reproduction test of D. magna, was negatively correlated with pH, temperature, BOD(5), chloride, atrazine, simazine, terbuthylazine, and endosulfan sulfate. The water toxicity of the Alqueva water might be due principally to the intensive agriculture activities surrounding the reservoir and to the municipal wastewater discharges. The physicochemical parameters and the pesticide concentrations indicated that the water quality was worse in the north part of the reservoir system. These results are characteristic of the majority of reservoirs, once the construction of the dam promoted, by itself, the impounding of water flow and the increase of compound residence time. The toxicity tests corroborate with the chemical characterization. Acute toxicity of Alqueva water may be a result of the effect promoted by chlorpyrifos, endosulfan sulfate, phosphorus, and iron. Chronic toxicity may be a result of the effect of herbicides, arsenic, organic matter, endosulfan sulfate in mixture. Hence, the water toxicity of the Alqueva might be due principally to the intensive agriculture activities surrounding the reservoir and to the municipal wastewater discharges. This study has shown that a large number of samples from different sites of the Alqueva reservoir contained potentially toxic contaminants. The sites with impaired water quality were those located at the north of the reservoir and in the surrounding areas of intensive agricultural activity. The results demonstrated that the use of a screening of acute and chronic toxicity tests with organisms from different trophic levels and with distinct sensibilities allowed the detections of several patterns of toxicity from spatial and temporal variability promoted by natural or anthropogenic sources. The chronic responses showed, especially in the dry season, that some of the species belonging to this aquatic ecosystem might be at risk. The V. fischeri and T. platyurus are two species that should be used in the acute bioassays for the ecotoxicological monitoring programs of this reservoir. It is recommended that other species, such as a productive organism (algae), be included in the next study, once the water reservoir had high levels of herbicides. Ecotoxicological assessment of surface water must integrate initial screening based on acute tests followed always by chronic bioassays. The results implicitly suggest that the implementation of processes of remediation by reducing pollutant input into the reservoir and by the implementation of water treatment processes is important and necessary.