A chemometric study on the accumulation of heavy metals along the Mogi Guaçu river basin

A study on the environmental impacts caused by agricultural and industrial activities along the Mogi Guaçu river basin was carried out. Concentrations of some metals (Fe, Cd, Cu, Cr, Zn, Ni, Pb and Mn) were determined for fifteen collection stations in two different seasons: rainy (March/2001) and dry (June/2001). Pattern recognition methods (Principal Component Analysis and Hierarchical Cluster Analysis) were used to group samples collected in São Paulo and Minas Gerais and obtain relevant information on possible polluting sources of the Mogi Guaçu river according to the collection season of the samples. A chemometric analyses performed using samples collected in March/2001 and June/2001 indicated that only the concentrations of Cd, Cu, Cr and Pb discriminate samples collected in São Paulo from those collected in Minas Gerais. The influence of the collection season was also analysed and the results indicated that four metals (Cd, Cr, Zn and Mn) were important to discriminate samples collected in March/2001 (rainy season) from those collected in June/2001 (dry season). We verified that the concentrations of the metals studied are at high levels in all collection stations and this fact characterizes an environment with a high degree of contamination caused mainly by anthropogenic activities.