Analyses of the sediment toxicity of Monjolinho River, São Carlos, São Paulo State, Brazil, using survey, growth and gill morphology of two fish species (Danio rerio and Poecilia reticulata)

The objective of this work was to evaluate the toxicity of the sediments of the Monjolinho River (São Carlos - São Paulo/Brazil), through partial chronic toxicity bioassays with juveniles of D. rerio and P. reticulata. Histological analyses of the gills and biometric measurements were conducted to detect the possible deleterious effects that caused the death. In all points the sampled the alterations were found in the gills (hyperplasia, fusion of secondary lamellas and dilation of blood vessels), with the most intense lesions (second stage) occurring at the point two. The biometric analysis pointed to inadequate conditions for the growth of the test-organisms when exposed to the sediment samples. These results showed that the conditions of these environments were not suitable for the survival and growth of these fishes.

Este trabalho teve como objetivo avaliar a toxicidade dos sedimentos do rio Monjolinho (São Carlos - São Paulo/Brasil), por meio de bioensaios de toxicidade crônicos parciais com juvenis de D. rerio e P. reticulata. Foram realizadas análises histológicas das brânquias dos organismos para detectar possíveis efeitos deletérios que antecedam a mortalidade. Em todos os pontos amostrados, foram verificadas alterações nas brânquias (hiperplasia, fusão de lamelas secundárias e dilatação de vasos sanguíneos), sendo no ponto dois foram encontradas lesões mais acentuadas (segundo estágio). A análise biométrica dos indivíduos expostos em amostras de sedimento demonstrou condições inadequadas para o crescimento e desenvolvimentos dos organismos-teste em todo o ambiente estudado. Os sedimentos apresentaram maior toxicidade no período chuvoso, sendo estes resultados confirmados por meio das análises histológicas das brânquias dos organismos expostos, as quais demonstraram lesões mais acentuadas no mesmo período. Tal situação possivelmente decorre dos impactos antrópicos os quais o sistema está suscetível (efluentes domésticos, industriais e agrícolas), que foram constatados pelas análises físicas e químicas dos sedimentos.

Methods for Sediment Toxicity Evaluation / 环境与健康杂志

Three widely used methods of sediment toxicity evaluation were introduced in the present paper, including organism toxicity tests, toxicity identification evaluation(TIE) and sediment quality guidelines(SQGs). Compared with the chemical analysis, toxicity tests have an advantage of taking the bioavailability of POPs into account, however, it fails to identify the causative toxicants. TIE, integrating with physicochemical analysis, implicates the specific pollutants in a tiered approach, and by which effective remediation can be designed accordingly. The sediment toxicity can be identified more quickly and appropriately by SQGs than by the former two methods. The differences among the different SQGs constituted by different standards may affect their values for toxicity evaluation. Extensive and reliable SQGs had been acquired to improve their utility. Finally, the combination of chemical analysis, toxicity tests and in situ bioassays will be the trend of sediment toxicity evaluation in the future.