Heavy-metal pollution in basin of Sapucai-Mirim River (Northeast of Sao Paulo State, Brazil), by hide industry

Contamination of the limnic environment is occurring at a fast rate all over the world due to the wide industrial expansion and, at the same time, to the lack of infrastructure for previous treatment of effluents that are dumped into fresh water sources, significantly contributing to the high rates of pollution affecting small and large rivers close to urban centers. The objective of the present study was to analyze the sediment and water of the Sapucai'-Mirim River, an important river in the Northeastern part of the State of Sao Paulo that receives industrial effluents from Franca and Sao Joaquim da Barra, where the major source of pollution is the leather industry which mainly uses Cr for tanning. In the present study we investigated the presence of the metals Cd, Cr, Cu, Pb and Zn at the sites where the Ribeirao dos Bagres stream empties into the Sao Joaquim stream and the Sapucai'-Mirim River. High metal levels were detected in both regions, with no significant differences between them. The differences detected were local, with the highest indices being found in the tributaries of the Sapucai'-Mirim River. The metals detected in the water were limited to Cr and Zn, with levels of the order of 0.006 mu g/ml to 0.168 mu g/ml Cr and 0.002 mu g/ml to 0.033 mu g/ml Zn. All the metals analyzed were detected in the sediment, with Cr and Zn again being present at highest concentrations. Cr ranged from 17.800 mu g/g to 242.425 mu g/g and Zn ranged from 142.000 mu g/g to 1024.000 mu g/g. With respect to Cr, the contamination in the region studied was attributed to the leather industry for the manufacturing of shoes.