Natural background assessment and Its anthropogenic contamination of Cd, Pb, Cu, Cr, Zn, Al and Fe in the sediments of the southern area of Patos Lagoon

The Patos Lagoon, located in Southern Brazil, is the world's largest choked coastal lagoon with an approximately 151000 km2 watershed. It receives untreated domestic, agricultural and industrial wastes associated with the populations living along its margins. This study examined the distribution of Cd, Pb, Cu, Cr, Zn, Al and Fe in 15 sediment cores of the lagoon in an attempt to establish natural background levels of these metals and to assess anthropogenic influences on them. Al and Fe were tested as normalizes among which Al was chosen as the most appropriated for the sampling sites. In some stations anomalous concentrations for Cd, Pb and Cu were found and contamination of sediments with Zn, Cr,Al and Fe was also observed