Seasonal study of concentration of heavy metals in waters from lower São Francisco River basin, Brazil.

A M Souza,P N Ramos,C S Belém,J F B Melo,W P Felix,A M Salviano

doi:10.1590/1519-6984.05215

Abstract

In this study we determined the concentration of metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in the water lower São Francisco River basin, to evaluate the influence of urbanization and industrialization on environmental changes in the water resource. All samples were analyzed using the IUPAC adapted method and processed in an atomic absorption spectrophotometer. The sampling stations located near the industrial areas were influenced by industrialization because they presented higher concentrations of Cd, Cr, Ni and Cu. The other sampled locations showed changes with regard the trace elements probably originating in the soil, like Fe, Zn and Pb. There was a gradual increase in the concentrations of metals, in general, in the period of highest rainfall of the hydrographic network. Overall, except for Zn and Mn, the trace elements exceeded the maximum allowed value established by national legislation (CONAMA). Lower São Francisco River basin has suffered interference from urbanization and industrialization, so awareness programs should be developed so as to control and lessen future problems.

Highlights

The impacts of human activity on aquatic systems have been reported for over 200 years
The main objective of this study is to evaluate the presence and average concentration total of heavy metals in the water of lower São Francisco River basin, in the Petrolina-PE and Juazeiro-BA section, investigating the possible natural sources and influences of anthropogenic activities on the water quality
The area to be studied is located in the West region of the states of Pernambuco and Bahia, Brazil, comprising the municipalities of Petrolina-PE and Juazeiro-BA

Summary

Introduction

The impacts of human activity on aquatic systems have been reported for over 200 years. Coupled to fast population growth, industrialization, as well as some agricultural activities, increased the risks of pollution in natural environments like water, soil and the atmosphere in the last 150 years (Santoyo et al, 2000). The problems of contamination with toxic metals started in the Middle Age, with the mining activities, but were accelerated in the beginning of the nineteen century, with the processing of metals in chemical and foundry plants (Vink et al, 1999).

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