Contamination by oil spills in coastal ecosystems, especially in mangrove zones, has been common in countries with oil industry. The aim of this study was, therefore, to evaluate the efficiency of application of the two models developed for pilot-scale remediation, intrinsic bioremediation (indigenous microorganisms), and phytoremediation (Avicennia schaueriana). The degradation of hydrocarbons was determined by gas chromatography (GS) with flame ionization detector. The metals Al, Fe, Pb, Cr, Cu, Zn, and Ni were determined by flame atomic absorption spectrometry in the mangrove simulated with sediment of Todos os Santos Bay, Brazil. These models also monitor other biogeochemical parameters (nitrogen, phosphorus, total organic carbon, pH, redox potentioal, dissolved oxygen, salinity, temperature, bacterial density). The integrated assessment of data showed that both techniques were effective in degrading organic compounds from oil but that phytoremediation is the most efficient (89% removal). The intrinsic bioremediation model has no direct correlation with metal concentrations, but a positive correlation with Al and Ni was found in the hydrocarbon removal by phytoremediation. Avicennia schaueriana represents efficiency in phytoextraction and phytostimulation. The results suggest that the phytoremediation model, through its various mechanisms, may become a technique for the removal of petroleum hydrocarbons in the presence of metals in mangrove ecosystems near industrial areas.

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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) Osmocote® 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 Osmocote® 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 four 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.

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This work combines the outcomes from the electron spin resonance (ESR) analysis of crude oils with the results of their chemical composition from elemental analysis (CHN), gas chromatography with flame ionization detection, Fourier-transform ion cyclotron resonance mass spectrometry using electrospray ionization in negative mode [ESI(−) FT-ICR MS], and Fouriertransform infrared spectroscopy analyses, searching for correlations to identify paramagnetic constituents associated with the presence of vanadyl species and free radicals in three Brazilian oils and in their resin and asphaltene fractions. The ESR analysis of the light oil SO02 (43°API) was able to differentiate it from biodegraded oils C19 (25°API) and C10 (19°API), through the quantification of free radicals in C19 (10.60 au) and C10 (9.39 au) when compared to SO02 (6.16 au), as a result of the electron paramagnetic resonance present in compounds that make up their polar fractions. The ESR response of the C19 resin fraction was the one that came closest to the oil's response, probably due to the greater relative abundance of compounds of N and NO classes in the C19 oil, observed through the results of the FT-ICR MS analysis. The ESR technique was also able to differentiate the biodegraded oils, due to the higher response of the vanadyl species in the C19 oil when compared to the C10 oil. O 2 compounds (carboxylic acids) present in high abundance in the C10 oil confirmed that it had undergone more extensive biodegradation than the C19 oil, and we suggest that this oxidation process may have decreased the response of the vanadyl species signal. The knowledge of the existing correlation between the response of the ESR technique of oils and their chemical composition aims at the application of this technique in the oil characterization during exploration, production, and refining operations.