Using oyster shells to track the 2010 Deepwater Horizon oil spill in the Gulf of Mexico

The Deepwater Horizon oil spill is the largest accidental oil spill in history, releasing approximately 4.9 million barrels of oil into the Gulf of Mexico between April 20 and July 15, 2010. In this study, shells of the economically and ecologically important oyster species Crassostrea virginica that lived through the spill were serially sampled through ontogeny and analyzed for oxygen isotopic ratios (δ18O) and concentrations of elements associated with hydrocarbon contamination to develop a chronology of the impact of oil contamination in the Gulf Coast over the past year. Concentrations of vanadium, barium, nickel, lead and manganese were measured using LA-ICP-MS and used as proxies for tracking levels of hydrocarbon contamination, as these elements are abundant in crude oil. Oxygen isotopic ratios were used to infer a formation date for each shell sample. It is hoped that the results of this study will help to help clarify the mechanisms and timing of past and present hydrocarbon infiltration into Gulf Coast food webs.