A Coupled Lagrangian-Earth System Model for Predicting Oil Photooxidation

During the Deepwater Horizon (DWH) blowout, photooxidation of surface oil led to formation persistent photooxidized compounds, still found in shoreline sediments a decade later. Studies demonstrated that modified both biodegradation rates and effectiveness aerial dispersant applications. Despite significant consequences this weathering pathway, lack measurements prevented be accounted for DWH budget calculations most predictive models. Here we develop Lagrangian module estimates dose solar radiation individual droplets receive while moving ocean, quantifies likelihood photooxidative changes, continues track transport these compounds. We estimate upper layers water column case by coupling net shortwave from NOGAPS application Connectivity Modeling System (oil-CMS). The upon droplet is computed with intensity incoming irradiance at ocean’s surface, light attenuation coefficient, depth droplets. Considering range empirical thresholds, find can happen short time scales hours days, agreement new paradigm photooxidation. Furthermore, oxidized compounds are likely form 110 km radius around response site, suggesting reaching coastline was already photooxidized. This dynamic provides powerful tool test hypotheses, refine during DWH, ultimately inform rapid future spills.