Metais potencialmente tóxicos em ambiente aquático: utilização de geoprocessamento para identificação de fontes poluidoras.

Abstract

The Pirapora River is an important source that supplies the cities of the region of Sorocaba / SP. The place chosen for this work is located in the city of Salto de Pirapora. The city of Salto de Pirapora stands out in the mining activity and planting of eucalyptus. The objective of this research was to quantify the metals Ba, Cr, Fe, Mn, Pb and Zn in samples of water from the Pirapora River by verifying the total metals (AT), bioavailable (BIO) and in natura (IN) determined with the physical-chemical parameters and with the use and occupation of the soil. In order to do so, water samples were collected in the Pirapora River at 5 different points and quantified in MPAES 4200 equipment. The concentrations of metallic species were evaluated: available in the aquatic ecosystem at the natural pH of the environment (IN), bound to sites that are easily reducible and / or weakly bound to organic matter (MO) in suspension (BIO) and strongly bound to MO and inorganic suspension (TA). The evaluations related to the use and occupation of the soil were analyzed by the application of unsupervised standard methods such as Hierarchical Analysis by Clustering (AHA), Principal Component Analysis (PCA), also using geoprocessing with an interpolation method, Kriging, that allows a continuous spatial representation of a set of samples. The results showed that the concentration of the Cr, Fe, Pb and Zn metals was higher in the AT samples. In this respect it can be inferred that these metals are strongly bound to suspended structures or colloidal material. Potentially toxic metals (Ba, Pb, Cr, Fe, Zn) showed a significant difference in temporal distribution. As for Zn and Mn, the exploratory analysis revealed differences in spatial variability along the Pirapora River. All determined metal species presented lower values than those established by Brazilian Resolution CONAMA 357/05, except for Fe. Fourteen land use patterns were evaluated as possible contaminant sources in the environment.