Quantifying Methane Oxidation Rates and Flux During the Deepwater Horizon Oil Spill with Measurements of Methane Stable Isotopic Ratios and Concentrations

Friday, 19 December 2014: 3:10 PM
Mengran Du, Sanya Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China, John D Kessler, University of Rochester, Rochester, NY, United States and Sean Sylva, Woods Hole Science Center Woods Hole, Woods Hole, MA, United States
Several independent techniques have been developed to measure the rate of methane oxidation and the source flux. However, none of these methods measure them concurrently. Here we present a stable isotope model incorporating measurements of methane stable isotopic ratios and concentrations, and current velocity, which can be used to determine methane oxidation rates, as well as the flux from the seafloor. This model was tested on 20 samples taken from 1 to 12 km from the wellhead from 11 June through 20 June 2010 during the Deepwater Horizon oil spill. Results suggest that rate of methane oxidation ranged from 22 to 844 nM d-1 in mid-June 2010 and that the flux from the seafloor was 8.4×107 moles d-1. Both estimated here are in agreement with previous estimates determined independently.