Evaluation of heavy metals levels in the Paraı́ba do Sul River by SRTXRF in muscle, gonads and gills of Geophagus brasiliensis

Abstract

It is known that fish may accumulate heavy metals through direct absorption, or via their food chain and pass them to human beings, by consumption, causing chronic or acute diseases. The metals bioaccumulation causes biochemical or pathological effects in individual fish, resulting in decrease of growth, fecundity and survival (Al-Yousuf et al., 2000). Biological strategies have evolved to detoxify metals, or to otherwise reduce the exposure of species to high concentrations of trace elements in their tissues. Total reflection X-ray fluorescence with synchrotron radiation (SRTXRF) become a competitive multi-element technique for the determination of trace elements in tissue samples (Baur et al., 2001). Since concentrations of most trace elements in tissues are lower than 100mgl , the direct determination of these elements is very difficult. In this work the concentration levels of heavy metals in selected tissues (muscle, gonads and gills) of Geophagus brasiliensis from the Paraiba do Sul River are determined using SRTXRF. This river, located in a region between the two most important urban and industrial centers of Brazil, has been changed along the last years by the human activity. Consequently, a decline in the diversity and abundance of the species has been observed.