Evaluation of mercury contamination in sediments from Santos - Sao Vicente Estuarine System, Sao Paulo State, Brazil

The distribution of mercury contamination in the Santos - Sao Vicente Estuarine System was observed through the analysis of 31 sediments samples collected from that system, including mangrove areas under urban, industrial and harbor influence zones. The range of values obtained was between 0.04 and 1.19 mu g g(-1). About 90% of samples presented Hg > 0.13 mu g g(-1) levels, which is the limit established by Canadian legislation and adopted by the environmental control agency of Sao Paulo State - Brazil ( CETESB), below which no adverse effect on the biological community has been observed. About 35% of these samples presented concentrations of Hg > 0.70 mu g g(-1), the probable level of occurrence of adverse effect on the biological community. These results indicate an increase in the mercury levels caused by industrial, port and urban activities. A statistical study was carried out, using the SPSS-10.0 software, to verify relationships among all the investigated parameters. Normalization of mercury with mud content was used to detect the degree of mercury contamination in this area.