Oil spill in Ilha Grande Bay: analysis of the impact mitigation process

Abstract

In Brazilian waters, the main oil spills occurred near maritime terminals and oil refineries. In 2015, a leak spilled more than 25,000 liters of oil into the sea, during oil transfer operations between ships at the terminal's mooring pier. This event reached an area of 459 kilometers, between the bays of Ilha Grande and Sepetiba, with oil adhering to several coastal and island points. Impact assessments and mitigating measures were carried out during 3 months of daily technical monitoring in the field. Impact mitigation measures were agreed with the environmental inspection body, and low pressure washes, at room temperature with sea water, of shores with adhered oil, were carried out. Along the impacted area, several coastal points with populations of barnacles covered by oil were recorded, which subsequently showed high mortality rates. The washing of the points that had a large amount of adhered oil proved to be effective in cleaning the shores, and mainly in the release of substrate, for a new repopulation of organisms of the biological communities that occur in these ecosystems.