RESUMO
This investigation evaluated the bioaccumulation potential of the tropical estuarine bivalve Anomalocardia flexuosa for trace metals. To this aim, chemical and sedimentological analyses and bioaccumulation tests were performed. The sediments were mainly composed by fine-sands and mud, with variable levels of organic matter and CaCO3. Muddy sediments from a depositional site (P2) presented the highest concentrations of metals, despite SEM/AVS not indicating bioavailability. Bioaccumulation factors showed high ratios for Cd, Ni, and Zn, while associations between the contents of mud, organic matter, CaCO3 and metals in sediments and tissues of A. flexuosa were indicated by a principal component analysis. The SEM/AVS was not effective to predict the bioavailability through dissolved metals. The results showed that contaminants were bioavailable, while the performed bioaccumulation test proved to be a reliable technique for assessing sediment contamination in estuarine regions. Moreover, A. flexuosa was considered an adequate test organism for bioaccumulation studies.
Assuntos
Bivalves , Metais Pesados , Poluentes Químicos da Água , Animais , Bioacumulação , Monitoramento Ambiental , Sedimentos Geológicos , Metais/análise , Metais Pesados/análise , Poluentes Químicos da Água/análiseRESUMO
The whole-sediment Toxicity Identification Evaluation (TIE) approach is a useful technique that allows for the identification of the contaminants responsible for the toxicity of complex sediment samples. This study aimed to compare the effectiveness of this technique in identifying the causes of toxicity when the test organism used in the toxicity test is capable of ingesting sediment particles. Two forms of exposure were compared: whole-sediment (WS), which integrates dermic and dietary exposures; and sediment-water interface (SWI), which involves dermic exposure only. The combined analysis of the TIE experiments revealed that metals, ammonia and, at one station, organic compounds, were responsible for sediment toxicity. The integrated use of WS and SWI TIE manipulations provided a more complete overview of the causes of toxicity, and thus enabled a better comprehension of complex contamination situations and, consequently, a better ecological assessment.