Abstract

Contamination of hydroelectric reservoir sediment in South East Brazil is a common. This may be because of the many uses of these environments: they are either located close to metropolitan area; or are impacted by soil leachates from an intense agri-bussiness park. This work presents data on nutrients and metals, and on bioessays associated to sediments from several reservoirs. Its is shown that if the equilibrium partitioning sediment guidelines proposed by the U.S. EPA are applied, toxicity due to metals can not be postulated as the acid volatile sulphide (AVS) and sediment pore water guidelines are not violated. It appears that AVS, as well as total organic carbon (TOC) in bulk sediments and the dissolved organic carbon (DOC) in pore waters are sufficiently high to prevent heavy metal toxicity. In spite of this, many of these sediments have tested toxic and on-going experiments to identify this toxicity have shown in at least one case (Rasgão reservoir) that ammonia is responsible for this toxicity as extremely high concentration of this species has been measured.