Sediment Ramped Pyrolysis and Isotope Data from the northern Gulf of Mexico, October 12, 2010 to June 19, 2015

The purpose of this study was to analyze the recovery of oil contaminated deep-sea sediment from by analyzing the carbon isotopic composition of bulk sedimentary organic carbon and the thermochemical stability of sediment from 5 sites in the northern Gulf of Mexico, using ramped pyrolysis/oxidation. There were clear differences between crude oil (low temperature), natural hydrocarbon seep sediment (medium temperature; Δ14C = -912‰) and our control site (medium temperature; Δ14C = -189‰), in both the thermographs and carbon isotope signatures. We observed recovery in the bulk Δ14C in sites further from the wellhead in ~4 years, while sites in closer proximity took 5-6 years to recover. The thermographs also indicated changes over time in the composition of the sediment, with shifts towards higher temperatures over time at sites near the wellhead, and losses of higher temperature CO2 peaks at more distal sites.