Trace metal and rare earth elements in a sediment profile from the Rio Grande Reservoir, Sao 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 Pb-210 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.