RESUMO

El propósito del presente estudio fue estimar la toxicidad del pesticidas carbofurán sobre los parámetros hematológicos (hematocrito, hemoglobina, glucosa en la sangre y conteo de eritrocitos y leucocitos totales), sobre la excreción de amoníaco y el consumo de oxígeno en individuos juveniles de Oreochromis niloticus (longitud total: 12±0,5 mm). Los espécimenes fueron expuestos a diferentes concentraciones del plaguicida carbofurán (0, 0,1, 0,5, 1,0, 2,0, y 4,0 mg L-1), a diferentes temperaturas (15, 20 y 25 °C) y pH 7. Los valores de LC50 en períodos de 24, 48, 72, 96 h para los juveniles de O. niloticus expuestos al carbofurán fueron 3,00; 2,84; 2,71 e 2,45 mg L−1 para 15 °C; 3,00; 2,69; 2,33 e 2,20 mg L−1 para 20 °C; y 2,84; 2,44; 1,71; 1,62 mg L−1 para 25 °C, respectivamente. Los resultados evidenciaron que con el aumento de la temperatura de 15 a 25 °C hubo un aumento de la sensibilidad de los peces al carbofurán de 21,80%, 9,55%, 31,92% y 30,87%, después de 24, 48, 72 y 96 h de exposición, respectivamente. Por otra parte, se observó que en peces expuestos al carbofurán en concentración de 2 mg L-1 ocurrió una disminución en la tasa de hemoglobina total y una elevación en la tasa de glucosa sanguínea, consumo de oxígeno y excreción de amonio. Estos resultados indican que la exposición al carbofurán, especialmente a altas temperaturas es un factor significativo a ser considerado en el manejo de la acuacultura.

Oreochromis niloticus juveniles (total length 12±0.5 mm) were exposed to different concentrations of carbofuran, using the static renewal method at different temperatures (15, 20 and 25°C) at pH 7. The 24, 48, 72, 96 h LC50 values of carbofuran in Oreochromis niloticus juveniles were 3.00, 2.84, 2.71 and 2.45 mg L−1 at 15°C; 3.00, 2.69, 2.33 and 2.20 mg L−1 at 20°C; and 2.84, 2.44, 1.7 1 and 1.62 mg L−1 at 25°C, respectively. Results show that a temperature increment from 15 to 25°C increased the carbofuran susceptibility in fish by 21.80%, 9.55%, 31.92% and 30.87%, after 24, 48, 72 and 96 hours of exposure, respectively. Furthermore, we found that exposure of fish to carbofuran caused an elevation in total hemoglobin and blood glucose concentration of 2 mg L-1. These results indicate that exposure to carbofuran, especially at lower temperatures is a significant factor to be considered in aquaculture management.

Assuntos

RESUMO

El propósito del presente estudio fue estimar la toxicidad del pesticidas carbofurán sobre los parámetros hematológicos (hematocrito, hemoglobina, glucosa en la sangre y conteo de eritrocitos y leucocitos totales), sobre la excreción de amoníaco y el consumo de oxígeno en individuos juveniles de Oreochromis niloticus (longitud total: 12±0,5 mm). Los espécimenes fueron expuestos a diferentes concentraciones del plaguicida carbofurán (0, 0,1, 0,5, 1,0, 2,0, y 4,0 mg L-1), a diferentes temperaturas (15, 20 y 25 °C) y pH 7. Los valores de LC50 en períodos de 24, 48, 72, 96 h para los juveniles de O. niloticus expuestos al carbofurán fueron 3,00; 2,84; 2,71 e 2,45 mg L−1 para 15 °C; 3,00; 2,69; 2,33 e 2,20 mg L−1 para 20 °C; y 2,84; 2,44; 1,71; 1,62 mg L−1 para 25 °C, respectivamente. Los resultados evidenciaron que con el aumento de la temperatura de 15 a 25 °C hubo un aumento de la sensibilidad de los peces al carbofurán de 21,80%, 9,55%, 31,92% y 30,87%, después de 24, 48, 72 y 96 h de exposición, respectivamente. Por otra parte, se observó que en peces expuestos al carbofurán en concentración de 2 mg L-1 ocurrió una disminución en la tasa de hemoglobina total y una elevación en la tasa de glucosa sanguínea, consumo de oxígeno y excreción de amonio. Estos resultados indican que la exposición al carbofurán, especialmente a altas temperaturas es un factor significativo a ser considerado en el manejo de la acuacultura.(AU)

Oreochromis niloticus juveniles (total length 12±0.5 mm) were exposed to different concentrations of carbofuran, using the static renewal method at different temperatures (15, 20 and 25°C) at pH 7. The 24, 48, 72, 96 h LC50 values of carbofuran in Oreochromis niloticus juveniles were 3.00, 2.84, 2.71 and 2.45 mg L−1 at 15°C; 3.00, 2.69, 2.33 and 2.20 mg L−1 at 20°C; and 2.84, 2.44, 1.7 1 and 1.62 mg L−1 at 25°C, respectively. Results show that a temperature increment from 15 to 25°C increased the carbofuran susceptibility in fish by 21.80%, 9.55%, 31.92% and 30.87%, after 24, 48, 72 and 96 hours of exposure, respectively. Furthermore, we found that exposure of fish to carbofuran caused an elevation in total hemoglobin and blood glucose concentration of 2 mg L-1. These results indicate that exposure to carbofuran, especially at lower temperatures is a significant factor to be considered in aquaculture management.(AU)

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Biomixtures are used for the removal of pesticides from agricultural wastewater. As biomixtures employ high content of lignocellulosic substrates, their bioaugmentation with ligninolytic fungi represents a novel approach for their enhancement. Nonetheless, the decrease in the concentration of the pesticide may result in sublethal concentrations that still affect ecosystems. Two matrices, a microcosm of rice husk (lignocellulosic substrate) bioaugmented with the fungus Trametes versicolor and a biomixture that contained fungally colonized rice husk were used in the degradation of the insecticide/nematicide carbofuran (CFN). Elutriates simulating lixiviates from these matrices were used to assay the ecotoxicological effects at sublethal level over Daphnia magna (Straus) and the fish Oreochromis aureus (Steindachner) and Oncorhynchus mykiss (Walbaum). Elutriates obtained after 30 d of treatment in the rice husk microcosms at dilutions over 2.5% increased the offspring of D. magna as a trade-off stress response, and produced mortality of neonates at dilutions over 5%. Elutriates (dilution 1:200) obtained during a 30 d period did not produce alterations on the oxygen consumption and ammonium excretion of O. mykiss, however these physiological parameters were affected in O. aureus at every time point of treatment, irrespective of the decrease in CFN concentration. When the fungally colonized rice husk was used to prepare a biomixture, where more accelerated degradation is expected, similar alterations on the responses by O. aureus were achieved. Results suggest that despite the good removal of the pesticide, it is necessary to optimize biomixtures to minimize their residual toxicity and potential chronic effects on aquatic life.

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Pesticide biopurification systems contain a biologically active matrix (biomixture) responsible for the accelerated elimination of pesticides in wastewaters derived from pest control in crop fields. Biomixtures have been typically prepared using the volumetric composition 50:25:25 (lignocellulosic substrate/humic component/soil); nonetheless, formal composition optimization has not been performed so far. Carbofuran is an insecticide/nematicide of high toxicity widely employed in developing countries. Therefore, the composition of a highly efficient biomixture (composed of coconut fiber, compost, and soil, FCS) for the removal of carbofuran was optimized by means of a central composite design and response surface methodology. The volumetric content of soil and the ratio coconut fiber/compost were used as the design variables. The performance of the biomixture was assayed by considering the elimination of carbofuran, the mineralization of (14)C-carbofuran, and the residual toxicity of the matrix, as response variables. Based on the models, the optimal volumetric composition of the FCS biomixture consists of 45:13:42 (coconut fiber/compost/soil), which resulted in minimal residual toxicity and ∼99% carbofuran elimination after 3 days. This optimized biomixture considerably differs from the standard 50:25:25 composition, which remarks the importance of assessing the performance of newly developed biomixtures during the design of biopurification systems.

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A biomixture constitutes the active core of the on-farm biopurification systems, employed for the detoxification of pesticide-containing wastewaters. As biomixtures should be prepared considering the available local materials, the present work aimed to evaluate the performance of ten different biomixtures elaborated with by-products from local farming, in the degradation of the insecticide/nematicide carbofuran (CFN), in order to identify suitable autochthonous biomixtures to be used in the tropics. Five different lignocellulosic materials mixed with either compost or peat and soil were employed in the preparation of the biomixtures. The comprehensive evaluation of the biomixtures included removal of the parent compound, formation of transformation products, mineralization of radiolabeled CFN, and determination of the residual toxicity of the process. Detoxification capacity of the matrices was high, and compost-based biomixtures showed better performance than peat-based biomixtures. CFN removal over 98.5% was achieved within 16 days (eight out of ten biomixtures), with half-lives below 5 days in most of the cases. 3-Hydroxycarbofuran and 3-ketocarbofuran were found as transformation products at very low concentrations suggesting their further degradation. Mineralization of CFN was also achieved after 64 days (2.9 to 15.1%); several biomixtures presented higher mineralization than the soil itself. Acute toxicity determinations with Daphnia magna revealed a marked detoxification in the matrices at the end of the process; low residual toxicity was observed only in two of the peat-based biomixtures. Overall best efficiency was achieved with the biomixture composed of coconut fiber-compost-soil; however, results suggest that in the case of unavailability of coconut fiber, other biomixtures may be employed with similar performance.

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Environmental contamination with pesticides is an undesired consequence of agricultural activities. Biopurification systems (BPS) comprise a novel strategy to degrade pesticides from contaminated wastewaters, consisting of a highly active biological mixture confined in a container or excavation. The design of BPS promotes microbial activity, in particular by white rot fungi (WRF). Due to their physiological features, specifically the production of highly unspecific ligninolytic enzymes and some intracellular enzymatic complexes, WRF show the ability to transform a wide range of organic pollutants. This minireview summarizes the potential participation of WRF in BPS. The first part presents the potential use of WRF in biodegradation of pollutants, particularly pesticides, and includes a brief description of the enzymatic systems involved in their oxidation. The second part presents an outline of BPS, focusing on the elements that influence the participation of WRF in their operation, and includes a summary of the studies regarding the fungal-mediated degradation of pesticides in BPS biomixtures and other solid-phase systems that mimic BPS.

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Penaeid shrimps are important resources for worldwide fisheries and aquaculture. In Brazil, Xiphopenaeus kroyeri is an important commercially exploited species, and is an ideal animal for studying the impairment caused by the effects of heavy metals that are often detected in coastal areas. The main purpose of the present study was to detect the acute toxicity of Cd and Zn to X. kroyeri and to investigate their effects on oxygen consumption and ammonium excretion in different temperatures (25 ºC, 20 ºC, 15 ºC), which have not been carried out in this species before. First of all, we examined the acute toxicity of Cd and Zn to X. kroyeri 24, 48, 72, and 96-h medium lethal concentration (LC50). Furthermore, we also found that exposure of shrimp to Cd and Zn caused an inhibition in oxygen consumption of 52.50% and 52.63%, respectively, relative to the control. However, after separate exposure to Cd and Zn, elevations in ammonium excretion were obtained, which were 85.00% and 89.47% higher than the control, respectively. The results shown that Cd and Zn performs higher toxicities to X. kroyeri at higher temperature.

Os camarões são importantes recursos marinhos explorados pela pesca e aquicultura. No Brasil, Xiphopenaeus kroyeri é uma importante espécie comercialmente explorada e um animal ideal para estudar o impacto causado por efeitos de metais pesados que frequentemente são detectados em áreas costeiras. O principal objetivo do presente trabalho foi determinar a toxicidade aguda do Cd e Zn para o X. kroyeri e investigar seus efeitos no consumo de oxigênio e na excreção de amônia em diferentes temperaturas, uma vez que tais parâmetros ainda não foram determinados para a referida espécie. Primeiramente, foram determinadas a toxicidade aguda (LC50) do Cd e Zn, para X. kroyeri por um período de 24, 48, 72 e 96 horas em três temperaturas (25 ºC, 20 ºC, 15 ºC). Os resultados revelaram que para camarões expostos ao Cd e Zn houve uma inibição do consumo de oxigênio de 52,50% e 52,63%, respectivamente, para a mais baixa temperatura (15 C). Entretanto, para a excreção de amônia, houve um aumento de 85,00% e 89,47% para a mais alta concentração e temperatura utilizadas em relação ao controle. Conclui-se, portanto, que as toxicidades de Cd e Zn foram mais altas nas temperaturas e concentrações mais elevadas.