Oil residue analysis from Chandeleur Island salt marsh sediments, September 2016 to February 2017

The 2010 Deepwater Horizon (DWH) oil spill resulted in more than 3 million barrels of crude oil being delivered into the Gulf of Mexico with approximately 160,000 barrels of oil residue impacting over 1800 km of shoreline in the northern Gulf of Mexico. These data were generated to determine whether oil residues present in marsh sediments were a match for Macondo 252 (MC252) oil from the spill. Ten compound groups were analyzed and matches to MC252 oil were determined by assessing the quantitative composition of the hopane and sterane biomarker compounds. Heavily weathered oil residue was detected in November and February and was a possible match to MC252. Additional residues detected in February were a non-match to MC252, indicating that they came from a different crude oil than was spilled during the Deepwater Horizon accident.