Temporal monitoring of contamination in three sandy beaches from the 2019 oil spill near Cabo de Santo Agostinho, Northeastern Brazil

Abstract

In 2019, a massive oil spill impacted coastal ecosystems in eleven Brazilian states; these ecosystems were diverse with regard to their different geological settings (sandy beaches, rocky coasts, estuaries, tidal flats, mangroves, and reef systems) being impacted. Here, we present a temporal analysis on the occurrence of remaining contaminants on three beaches (Paiva, Itapuama, and Enseada) of the Cabo de Santo Agostinho City, Pernambuco State. The approach focuses on the systematic mapping of residues, collection of sediment samples, photographic documentation, and qualitative microscopic analysis. Grain size, calcium carbonate, and total organic matter content analyses provided a faciological and energetic characterization of the environment. The objective was to verify the relationship between the remaining contaminants and the geological setting. The results showed intense weathering of the remaining oil residues due to the high energy environment. We found tar balls reworked by seasonal erosion on the three beaches and no tar residues in shallow subsurface sediments. A large quantity of tar residues remains on rock surfaces in Itapuama Beach, which bears the higher permanence of contamination because it is less affected by weathering and beach erosion. This investigation allowed for an impact assessment of the geological-morphological characteristics of the beaches.