Major ions on the Salto Grande Stream Micro-basin: 22º09`S and 48º19`W, Dourado, SP, Brazil

Abstract

As part of a large research program that involves the study of biotic and abiotic parameters such as periphyton, bacteria and fungi communities, organic pollution (domestic and cattle farming effluent), physiography of the drainage basin and climate data, this is the seventh of a series of ten papers concerning physical and chemical water quality of the Salto Grande Stream. Sampling took place from April/1985 to October/1986. The results showed the rock dominance on the water quality of the Salto Grande Stream, probably without organic contamination interference. The regional climate had secondary importance and there happened some change related to the land moisture. The stream shows 71.83 mg/L, as ionic concentration, corresponding to 1.961 meq/L, that had 56% as cation and 46% as anion, with the following dominance order Ca⁺⁺>Mg⁺⁺>Na⁺>K⁺ and HCO₃^- >Cl^- >S0₄^--. The relations MID (monovalent/divalent), MIM and D/D reinforce the hypothesis that the domestic and cattle sewage did not influence the concentration of the major ions . These relations showed the following medians results: (Na⁺+ K⁺)/(Ca⁺⁺ + Mg⁺⁺) = 0.34; (Na⁺ + K⁺)/Mg⁺⁺ = 1.71; Na⁺ + K⁺/Ca⁺⁺ = 0.63; K⁺/Na⁺ = 0.51; Ca⁺⁺/Mg⁺⁺ = 1.21