PAH residues and toxicity levels two years after an extensive oil spill on the northeast Brazilian coast.

The most extensive oil spill ever recorded in tropical oceans occurred between August 2019 and March 2020, affecting approximately 3000 km of the Brazilian coast. This study assessed the chemical contamination and toxicity of sediments collected from affected reef areas during two sampling surveys conducted 17 and 24 months after the peak of oil slick inputs. Our results indicated that neither PAH levels nor measured toxicity showed a significant contribution from the spilled oil, with concentrations and biological effects indistinguishable from those in unaffected areas. Similarly, no differences were observed between seasons. Furthermore, there was no discernible relationship between sediment toxicity results and the measured PAH concentrations. Therefore, while biological responses indicated toxicity in most assessed areas, these responses are likely related to other local sources. This evidence suggests a natural oil attenuation process contributing to local environmental recovery. Nonetheless, further investigation is needed for other areas affected by oil spills.

Petroleum hydrocarbons in water from a Brazilian tropical estuary facing industrial and port development.

A fast paced industrial and port development has occurred at Suape Estuary, Northeast Brazil, but no information about hydrocarbon concentrations in water is available to this area. Considering that, the contamination level of Suape was determined by UV-Fluorescence in terms of dissolved and/or dispersed petroleum hydrocarbons (DDPHs), during wet and dry seasons. DDPHs ranged between 0.05 and 4.59 µg L(-1) Carmópolis oil equivalents and 0.01-1.39 µg L(-1) chrysene equivalents, indicating DDPHs close to a baseline contamination level. Some relatively high concentrations (>1 µg L(-1)) were probably associated with shipyard operations (hull paintings and ship docking), pollutants remobilization by dredging operations, occasional industrial discharges and oil derivatives released by vessels. DDPHs concentrations were lower in the wet season suggesting that the increased dilution rates caused by rainfall dominated upon the wet deposition of atmospheric combustion-derived PAHs process. Results in this study may be used as baseline to further studies in this area.