Assessing the environmental impact of oil spills in beach environments: a case study using the Capacitive Resistivity Method

Abstract

The accident involving oil spill that occurred on the Brazilian coast in 2019 reached 2,880 km in extension, and more than 200 tons of oily material was removed from coastal environments in the northeast of the country in about five months. In the impact on beach environment there may still be non-visible residues and its by-products in subsurface, so that geophysical prospecting can be the suitable to evaluate the presence of remaining material. The evolution of environmental studies has required new research technologies. Geophysical methods have shown to be efficient in environmentalstudies, with the use of relatively new methods in Brazil that provide results with excellent coverage in the area and quickly. Among these methods stands out the Capacitive Resistivity Method. Environmental research work with this method has been reported with good results, but it is necessary to take into account the operational physical bases of the method so that the data is reliable. This work presents the results of tests carried out in a beach environment that was affected by oil. This environment is characterized by a medium of high conductivity, where data acquisition with equipment configured with smaller dipolar cables results in extremely noisy data. On the other hand, the configuration with larger dipolar cables allowed the transmission of higher electrical current to the ground resulting in the acquisition of good quality data. The results showed that there are no more indications of oil residues on the beach studied.