Trace metal and rare earth elements in a sediment profile from the Rio Grande Reservoir, São Paulo, Brazil: determination of anthropogenic contamination, dating, and sedimentation rates

The Rio Grande Reservoir supplies water to four counties. Two sediment cores were collected, one was sliced every 2 cm for INAA and dating determinations; the other was cut every 5 cm, for grain size and Hg, Cd, Pb, Ni, Mn and Cu determinations. Sedimentation rates and sediment ages of every layer were determined by 210 Pb method. Enrichment Factor (EF) and Geoaccumulation Index ( I geo ) were calculated. Significant enrichment was found for Na, Mn, Ni, Pb, Sb and Zn and extremely high enrichment for Hg, Cu and Cd, in upper layers. A 90 year pollution history of this reservoir was traced.