Characterization of Surface Waters of a Tropical Reservoir using UV-vis Spectroscopy and Chemical Properties

Surface water samples were collected at 19 sites of the Capivara reservoir, Brazil, to characterize the natural waters of the lake and to verify the impact of the urban activities on its water composition. The dissolved organic matter was analyzed by UV-Vis spectroscopy and the concentrations of Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Zn, Cl⁻, NO^2-NO^3-, SO4^2-, PO4^3-, total S and total P dissolved in the water samples were determined. Other variables studied were the depth, Secchi disk, chlorophyll-a, pH, redox potential, alkalinity, dissolved organic carbon and electrical conductivity. The principal components analysis identified two clusters of sites using all variables: the tributary Tibagi River and the tributary Paranapanema River (I) and the central part of the lake (II). It was verified a little but worrying impact of urban activities in the water composition, more evident close to the city of Primeiro de Maio were the highest concentrations of Cr, Cu and Ni were determined indicating anthropogenic interference.