Geophysical investigation using the GPR method: a case study on the contamination of lead in the Santo Amaro town, Bahia, Brazil

Abstract

In Brazil, until the 1970s, industrial and urban waste was directly disposed of in the soil, as it was believed that the soil was an unlimited receptor for disposable and noxious substances. However, this capability was overestimated, causing irreparable damage to the environment. Geophysics has been shown to be effective in identifying areas contaminated by waste disposal, contributing to the greater efficiency of soundings programs and the installation of monitoring wells. In this work we have evaluated the potential of the Ground Penetrating Radar (GPR) method in the characterization of a hazardous waste site generated by the lead ore processing, where the slag resulting from this process was used to pave streets and backyard residences in the town of Santo Amaro, state of Bahia, situated on the domain of the massapê soil. The used method enabled the identification of geophysical anomalies, which characterized the presence of contamination from slag material. It was also possible to define the interface between the paving and the soil-slag, as well as the interface between the soil-slag and the massapê soil. Chemical analysis of the soil confirmed the contamination, with high concentrations of lead found in at least three drill holes. The geophysical method used in the investigation provided an excellent tool for environmental characterization of the area, and could be applied in the study of similar areas elsewhere.