Weathering impacts on petroleum biomarker, aromatic, and polar compounds in the spilled oil at the northeast coast of Brazil over time

After the wide oil spill reached the northeast of Brazil, the resurgence of oil was recorded and to evaluate this in detail, two samples collected in the state of Pernambuco in 2019 and 2021 were submitted to multiple analytical techniques. For both, we have found similar saturated biomarkers and triaromatic steroid ratios, implying that they are from the same spilled source. The n-alkanes, isoprenoids, and cycloalkanes were almost completely degraded due to evaporation, photooxidation, and/or biodegradation processes. The preferential of less alkylated PAHs than the more alkylated ones suggests that biodegradation was the most active process. This hypothesis is reinforced by the formation of mono and dicarboxylic acids assessed by GC x GC-TOFMS ESI(-) FT-ICR MS high-resolution techniques. Furthermore, based on the ESI(-) FT-ICR MS results, three ratios were proposed to evaluate the progress of the biodegradation process over time: Ox>2/O, SOx/SO, SOx/N.

Automated summary

Through multiple analytical techniques on two samples collected in Pernambuco in 2019 and 2021, it was found that they have similar saturated biomarkers and triaromatic steroid ratios, indicating they are from the same spilled source. The degradation of n-alkanes, isoprenoids, and cycloalkanes was extensive due to evaporation, photooxidation, and/or biodegradation processes, while less alkylated PAHs were more biodegraded than the more alkylated ones. This was supported by the formation of mono and dicarboxylic acids assessed by GC x GC-TOFMS ESI(-) FT-ICR MS techniques. Three ratios were proposed based on ESI(-) FT-ICR MS results to evaluate the progress of the biodegradation process over time: Ox>2/O, SOx/SO, SOx/N.