Characterization of heavy metals contamination in a mangrove, Santos Municipality (SP)

Abstract

This study aimed at evaluating the contamination of soil and superficial and ground waters by heavy metals in a mangrove in Santos Municipality (São Paulo State), where waste from port operations has been disposed for over 50 years. Chemical analyses of soil and water samples collected in the study area indicated that the concentrations of heavy metals ions (Pb, Zn, Cu, Ni) are above the reference values of the Companhia Ambiental do Estado de São Paulo - CETESB (São Paulo State Environmental Agency). The high content of organic matter in the mangrove is probably the main cause of ionic fixation of these metals in the soils. Chemical analysis of the percolated liquid from the landfill, collected in a lagoon, also showed high concentration of Pb. Metal extraction from soils with water (soluble phase) and HNO3 (soluble and adsorbed phases) indicates that the lixiviation of these ions occurred under specific conditions, which can increase the dispersion of these contaminants in the environment.