Metal contamination in surface sediments of mangroves, lagoons and Southern Bay in Florianopolis Island

Total concentrations for Hg, Pb, Cd, Se, As, Sn, U, Zn, Ni, Cu, Cr, Sb, Sr, Fd and Ag were determined in surface sediments of the mangroves, lagoons and Southern Bay from Florianopolis Island in Brazil, by using a ICP-MS technique and statistic methods. The goal was to estimate the actual level of contamination in metals in Florianopolis Island. The results show, that in many sites, concentrations higher than the mean elemental composition of sediments on earth were found for Hg, Pb, Se, As, Sn, U and Ag. The statistic analysis shows that the metals concentrations follows more preferentially the variation of the fine grain fraction than that of the organic matter. In contrast, U and Hg seem to be more associated with organic matter. The principal component analysis clearly illustrates the distinctions occurring between the zones which included the Southern Bay and the Itacorubi mangrove (likely to be under anthropogenic influence) and the zone of the Peri lagoon where the natural influence is predominating. In the lagoon of Conceicao, metal concentrations very dose to the means earth values have been found except for Ag and Se. According to our results, the decreasing order of the studied areas for anthropogenic inputs is: mangrove of Itacorubi > Southern Bay > lagoon of Conceicaco > mangrove of Ratones > mangrove of Tavares > lagoon of Peri.