Avaliação da qualidade do sedimento do baixo estuário do rio Itajaí-Açu (SC) através de testes de toxicidade crônica

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

After CONAMA resolution 344 of 2004, environmental agencies have required the quality assessment of the aquatic environments sediments that are subject to remobilization by dredging activities, mainly in port areas. By toxicity tests of embryo-larval development of sea urchin Arbacia lixula, this study analyzed the spatial-temporal quality variation of Itajaíaçú river sediments, linking it to dredging activities, sediments textural characteristics, organic matter content and fluvial discharge. Results showed high content of un-ionized ammonia (NH3) in most samples, interfering in the toxicity evaluation of the sediments sampled. The distinction between the sections located upstream the port and the ones constantly dredged was observed, the latter region displayed less toxicity and greater temporal variability. Overall, margins were more toxic than the navigation channel. Toxicity of the coastal region corresponded to periods of sediments dredged disposal, however, their dispersion to adjacent areas occurred. Percentage of fines were followed by equivalent contents of organic matter and toxicity followed the same patter of these variables. The nonrelationship between sediments toxicity and fluvial discharge demonstrates the predominant influence of dredging activities on the quality of Itajaí-açú estuary sediments. The toxicity identification method (TIE) indicated metal and ammonia contamination inside the estuary, prevalenting metals in coastal regions. Chemical analysis identified high concentrations of Zn and Ag, at toxic levels to Arbacia lixula. The presence of Cu was also observed, however, at concentrations below the sensibility limit to this test organism

ASSUNTO(S)

oceanografia dragagem estuário, itajaí-açú, sedimento, toxicidade. dredging, estuary, itajaí-açú, sediment, toxicity

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