The Rio Grande reservoir lies southeast of the Metropolitan Area of São Paulo. In order to evaluate if the sediments contain
a historical registration of anthropogenic activity, four sediment cores were sampled from the reservoir. In these cores the
Hg concentration was determined by the CV AAS technique, major and trace elements by instrumental neutron activation analysis
and the sedimentation rates by the 210Pb method. The results obtained for Hg are much higher than expected, showing an anthropogenic contribution. As a general
trend, the elemental concentration decreases with depth, indicating recent contamination.