(Toxicological evaluation of metais in reservoir of South East São Paulo, Brazil)

Abstract

As part of the project "Tipology of reservoirs of the State of São Paulo" (FAPESP), 17 reservoirs, located at rivers of the Paraná River Basin (8), Ribeira de Iguape River Basin (4), Paraí­­ba do Sul River Basin (2) and Billings Complex (3), were studied during the year of 1979. Most of reservoirs are recent and 30 m or less deep. The region investigated (43°31'-48°57'W and 22°40' - 24°20'S) shows two climatic seasons, warm and raining (October-March), and cold and dry (April-September). The concentration of metallic elements was estimated by atomic absorption spectrophotometry, at quarterly intervals. The higher concentrations(ppm),3.11 Fe,3.18 Mn, 1.49 Al and 0.03 Cd, were registered at reservoirs of the Paraná River Basin, while Pb (0.1)and Ni (0.04) occurred in reservoirs of Paraná and Ribeira de Iguape Rivers; Zn (0.3), Cr (0.09), As (0.08) and Ni (0.04) were detected in Billings Complex reservoirs. Cu, B and Ag were only registered at the minimum limit of detection, respectively 0.02, 1.0 and 0.05 ppm. The sensitivity of the analysis of Ag and Cu did not permit the detection of toxic concentrations, as well for Cd (0.02 ppm) and Pb (0.05 ppm), although higher concentrations of Cd and Pb were registered. Metallic elements in toxic concentration for aquatic organisms were detected at the 4 studied basins, as follows: Cr (0.05 - 0.09 ppm) toxic for zooplankton, at 4 reservoirs; Pb (0.05 - 0.l0 ppm) toxic for fishes, at 7; Ni (0.03 - 0.04 ppm), toxic for zooplankton and fishes, at 7; Zn (0.06 - 0.30 ppm), for zooplankton and fishes at 8; Al (0.20 - 1.49 ppm) for zooplankton and fishes at 3 and Cd (0.02 - 0.03 ppm) for phytoplankton, zooplankton and fishes, at 5. The other elements analyzed were not detected at toxic concentrations for aquatic organisms.