Bioremediation of Oil-Contaminated Beach and Restinga Sediments Using a Slow-Release Fertilizer

Bioremediation in petroleum-contaminated sediments was investigated under laboratory conditions, that simulated an oil pipeline coming from the most productive offshore oil basin in Brazil and crossing the restinga ecosystem. Two scenarios were tested in case of an oil leakage of the pipeline: a superficial contamination of the beach sediment from the pipeline's submarine section (P1) and a subsurface contamination of the restinga sediment (P2) in the onshore buried pipeline section. The slow-release fertilizer (SRF) Osmocote1 was used in both P1 and P2 to stimulate oil biodegradation by the indigenous microorganisms, and its effectiveness was tested. After a 92-day experiment, biostimulation with Osmocote1 was efficient, but differences were observed in the biodegradation behavior of the hydrocarbon compounds analyzed. The n-alkanes were biodegraded to trace levels after 28 days in P1 and P2, whereas, pristane and phytane were totally degraded between days 28 and 42 in P1, and 4 weeks later in P2. Natural attenuation also played an important role in removing the n-alkanes and the isoalkanes (pristane and phytane). This research is innovative in using a SRF to develop a clean-up solution for the sensitive restinga ecosystem after an oil contamination event, especially when considering a leakage of the buried pipeline.