Evaluation of lead (pb), mercury (hg) and cadmium (cd) in the margin sediment of the Guarapiranga dam, a public health issue

Abstract

One of the largest reservoirs of water in the southern zone of Sao Paulo, the Guarapiranga dam, witnessed the irregular occupation of the source, take irreversible proportions, compromising water quality with the launch of domestic and industrial sewage without previous treatment, generating an increase in the levels of environmental pollution. The high concentration of heavy metals in particular in the sediments can be a good indication of pollution often attributed to anthropogenic influences, rather than a natural enrichment of geological sediments by weathering. In this work, six collection points were investigated, observing the access of users to the Guarapiranga dam to the so-called "small beaches", where they seek their leisure and rest time with their families. In the laboratory of Santo Amaro University in São Paulo, the samples were dried at room temperature, dismantled, sieved and underwent to acid digestion before sent to be analyzed in atomic absorption spectrometer. The results of the investigation showed a contamination of Cd above the permitted values as well as the presence of Pb with values above and close to the quality benchmark. A contamination of Hg was not observed in the collected samples. The concentrations of the Cd and Pb metals that exceeded the limits in the collected samples confirm the need for continuous monitoring of this system and evidence the direct anthropogenic action in the conditions of the Guarapiranga dam.