Decadal stability and forensic reliability of petroleum biomarkers in tropical coastal environments: Validating laboratory kinetics against 10-year field residues

H) remained virtually invariant throughout the simulation. Crucially, these ratios precisely matched authentic field residues, including 10-year archived samples from the 2008 Morning Sun incident and dynamically weathered residues from the 2017 Green Island spill. These findings establish C30-hopane as a highly recalcitrant, conservative internal standard for quantifying NAPL mass transfer in complex coastal systems. Furthermore, the systematic depletion of alkylated polycyclic aromatic hydrocarbons (APAHs) marks a kinetic shift from initial physical sequestration to chemical and microbial oxidation. This oxidative transition governs the leaching of water-soluble, toxic oxygenated PAHs (OPAHs) into underlying coastal aquifers. Ultimately, our results provide a robust, tiered forensic framework to calibrate groundwater transport models and predict the environmental persistence of legacy petroleum sources at vulnerable maritime-terrestrial interfaces.