Hidrogeochemical comparative study of the Jaú and Jacaré-Gua?u River watersheds, S?o Paulo, Brazil

摘要

The main subject of the present work was to carry out a hydrochemistry comparative study between two river basins in S?o Paulo State: the Jacaré-Gua?u Basin (21°37'-22°22'S and 47°43'-48°57'W) and the Jaú Basin (22°09'-22°28'S and 48°16'-48°47'W). Nine sampling points in the Jacaré-Gua?u River and eight in the Jaú River were established. The water sampling was performed once each two months from March/95 to September/95. The following variables were analyzed: temperature (°C), pH, conductivity (muScm--1), dissolved oxygen (mg/L) and ionic water composition. Comparatively the Jaú River showed higher spatial variability, less oxygenated water and higher mineralization, due to high pedological and geological substrate richness, point sources existence and less riparian forests. The Jacaré-Gua?u River showed less spatial variability, more oxygenated water with lower ionic concentration due to the lower geological and pedological watershed richness, absence of pollution from point sources and higher riparian forest protection.