Metal bioavailability potential of São Francisco river sediments in Três Marias (Minas Gerais - Brazil)

Abstract

Sediment contamination by metals is very common and frequently researched worldwide with the objective of assessing the environmental impact of these contaminants. The bulk metal concentration in sediments is not enough for assessing toxicity and therefore, needs additional research and assays. To estimate the potentially bioavailable fraction of the metals in the sediment, the acid-volatile sulfides / simultane ously extracted metals (AVS/SEM) method was used. Seven samples in duplicate were collected from the Sao Francisco River and its tributary, near a zinc metallurgical plant in the city of Tres Marias (MG). The AVS/SEM results suggest that, although the bulk metal concentrations are above TEL (Threshold Effects Level: A chemical concentration above which some adverse effect to biota is expected), samples from the Sao Francisco River presented relatively low potential for bioavailability (uncertain toxicity). These results should be taken into consideration before deciding about contaminated sediment management. Keyword: AVS-SEM, bioavailability, metals, Sao Francisco River