Monitoring chemical compositional changes of simulated spilled Brazilian oils under tropical climate conditions by multiple analytical techniques

• Published in: Marine pollution bulletin Vol. 164; p. 111985
• Main Authors: Lima, Bárbara D., Martins, Laercio L., de Souza, Eliane S., Pudenzi, Marcos A., da Cruz, Georgiana F.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2021
• Subjects: alkanes; Biomarkers; Brazil; evaporation; irradiation; marine pollution; Oil spill; oil spills; Oils; PAHs; Petroleum - analysis; Petroleum Pollution - analysis; photooxidation; Polar compounds; Polycyclic Aromatic Hydrocarbons - analysis; solar radiation; Tropical Climate; Tropical conditions; tropics; Water Pollutants, Chemical - analysis; Weathering; Brazil; Oil spill; Weathering; Tropical conditions; Biomarkers; PAHs; Polar compounds
• ISSN: 0025-326X; 1879-3363; 1879-3363
• DOI: 10.1016/j.marpolbul.2021.111985

To comprehensively understand the chemical changes over time of spilled oils subject to tropical climate conditions and the active weathering processes, a spill simulation experiment was conducted along 210 days with two distinct Brazilian oils (19 and 24 API) under irradiation and non-irradiation of sunlight. Isoprenoids and n-alkanes showed a great loss after 40 days for both oils under the two conditions due to evaporation. Diagnostic ratios of saturated biomarkers showed no changes, whereas the polycyclic aromatic hydrocarbons had a decreasing concentration under both conditions mainly due to evaporation. Furthermore, oxygenated polar compounds produced by photooxidation were investigated by ESI(−) FT-ICR MS and showed changes only for the oils exposed to sunlight irradiation. Based on the observed polar compositional changes, new parameters are suggested using heteroatom classes to estimate oil spill time under tropical conditions: NO3/NO2; NO3/(NO + NO2); ∑NOx/N1; (O4 + O3)/(O2 + O1); O4/(O2 + O1); and O3/O2. [Display omitted] •Evaporation was an active process depleting n-alkanes, isoprenoids, and PAHs.•Saturated biomarkers were resistant to weathering even in Tropical conditions.•Photooxidation was the responsible process to polar compositional changes.•Indirect photooxidation may have been a significant pathway for O-compound changes.•New ratios using N1, Ox and NOx polar classes to estimate time after the oil spill,