Major and trace element assessment of Tietê river sediments, São Paulo, Brazil

The objective of this study was to quantify major and trace elements present in sediments collected from the one of Brazil’s most important rivers, Tiete River. Sediments from 5 different sampling points (P0–P4), in 3 campaigns (2008/2009), from the headwaters to Suzano County upstream from Sao Paulo city were collected. X-ray fluorescence was applied for measuring total concentration of major elements and instrumental neutron activation analysis (INAA) for trace elements. The elements Cd, Hg and Pb were determined by atomic absorption spectrometry after digestion using the US EPA 3,051 procedure. These metal concentrations were compared to the PEL and TEL oriented values from CCME. The sampling sites P3 and P4, near industrialized areas, showed the highest concentrations for potentially bioavailable metals, mainly Pb and Hg. The results obtained by INAA were compared to upper continental crust values. A strong enrichment was found for the elements As, Br, Sb, Th, U and Zn. These results evidenced contamination by industrial effluents and sewage even relatively close to the Tiete River headwaters. The worst biological effects (acute toxicity) on benthonic organism Hyalella azteca were also observed at P3 and P4.