Oil spill bioremediation strategies in Brazilian tropical seawater—The role of polycyclic aromatic hydrocarbons degradation

For this research, a 28-day bioremediation experiment was conducted, simulating an oil spill on the Brazilian coast using mesocosm units and two different bioremediation strategies, adding rate-limiting nutrients in the form of NPK fertilizer during the first four days (Bior1) and weekly (Bior2). The gas chromatography–mass spectrometry analysis results showed that oil natural degradation (Control) removed 33.8 wt.% of the alkanes on Day 7, while bioremediation processes plus evaporation in Bior1 and Bior2 contributed to minimizing alkanes in 83.4 and 80.8 wt.%, respectively. Bior1 strategy also accelerated the biodegradation of recalcitrant polycyclic aromatic hydrocarbons (PAH) such as phenanthrene, methyl phenanthrenes, and methyl dibenzothiophenes up to the second week when compared to Bior2. Low-cost NPK fertilizer addition demonstrated efficiency in the bioremediation strategy, especially in the first days of the simulated oil spill (Bior1), leading to savings in time and financial investment in recovering an oil contaminated area. Results also showed the efficiency of the oil-degrading bacteria Pseudomonas mesophilica, identified for the first time in Brazilian seawater. In addition, results confirmed the influence of tropical temperatures over oil natural natural degradation and bioremediation as an oil spill cleanup solution for recovering contaminated areas in tropical countries, especially in sensitive marine environments.