Concentrations and enrichment of metals in sediment cores: geochemistry and correlations with geoaccumulation index

Resumen

The Mãe d?Água dam was built in 1962 to supply the Federal University of Rio Grande do Sul?s water demanding. Thus, the paper aims to measure Nickel (Ni) and Zinc (Zn) concentrations in many depths of the dam?s bottom, sampling cores of sediments silted in it. The samplings were carried out in June, 2014, and it was sampled four sediment cores in pre-defined points of the dam. The methodology for extraction of sediment cores was ?Piston Core?. Sediment particles smaller than 63 µm were separated and used for chemical analysis. EPA 3050 acid digestion methodology is used by the U.S. Environment Protection Agency and it was also used in this study. Analyses were carried out in duplicate and two USGS reference materials were used for quality control: SGR-1b and SCO-1. Zn and Ni concentrations were over than local background values and increasing concentrations of the deepest sendiments to the most recent layers as a result of urbanization activities. Geoaccumulation index was able to characterize decreasing of metal concentrations in depth.