Avaliação dos fluxos das principais espécies quimicas dissolvidas no rio Sorocaba (SP)

Abstract

FLUXES EVALUATION OF MAIN CHEMICAL SPECIES DISSOLVED IN THE SOROCABA RIVER (SP). This study aimed to characterize the hydrochemistry of the main chemical species dissolved in the Sorocaba River, as well as evaluate their fluxes in a hydrological cycle and during dry and rainy periods. Between June 2009 and June 2010, twelve river water samples were collected, which showed near neutral pH (6.9 to 7.3) and a marked seasonal variation of conductivity, temperature and concentration of chemical species studied. The regression models adjusted to concentration x discharge relationship were significant (p < 0,01) and indicated an association of Ca2+, Mg2+, K+, HCO3 - and TDS to diffuse sources and Na+, NO3 - and PO4 3- the punctual sources, without clearly identifying the predominant contributions of SiO2, Cl- and SO4 2-. A comparative analysis of the exponents of the adjusted models proposed, which confirmed previous associations and related SiO2, Cl- and SO4 2- to a mix of sources. The dissolved load contribution of the Sorocaba River to Middle Tietê basin was 392.16 x 103 t a-1, the most significant being those of HCO3 - and SiO2, followed by Ca2+, Na+, Cl-, SO4 2-, NO3 -, K+, Mg2+ and PO4 3-, order maintained in the dry and rainy periods, with exception of NO3-which showed similar charge in the three periods.