Estimating Incident Ultraviolet (UV) Radiation Exposure in the Northern Gulf of Mexico During the Deepwater Horizon Oil Spill

Abstract

Millions of barrels of oil were released into the Gulf of Mexico (GoM) following the 2010 explosion of the Deepwater Horizon (DWH) oil rig. Polycyclic aromatic hydrocarbons (PAHs) are toxic components of crude oil, which may become more toxic in the presence of ultraviolet radiation (UV) in a phenomenon known as photo-induced toxicity. The DWH spill impacted offshore and estuarine sites, where biota may be co-exposed to UV and PAHs. Penetration of UV into the water column is affected by site-specific factors. Therefore, measurements and/or estimations of UV are necessary when assessing the risk posed by photo-induced toxicity to biota. Here, we describe how estimates of incident UV were determined for the area impacted by the DWH oil spill, using monitoring data from radiometers near the spill, in conjunction with reference spectra characterizing the composition of solar radiation. Furthermore, we provide UV attenuation coefficients for both near- and off-shore sites in the GoM. These estimates are specific to the time and location of the spill, and fall within the range of intensities utilized during photo-induced toxicity tests performed in support of the DWH Natural Resource Damage Assessment (NRDA). These data further validate the methodologies and findings of photo-toxicity tests included in the DWH NRDA, while underscoring the importance of considering UV exposure when assessing risk posed following oil spills. This article is protected by copyright. All rights reserved

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