The mystery of the missing methane part II

03 June 2011 - Deepwater Horizon

Back in January Kessler et al. were sure most of the methane released by a faulty vent in the Gulf of Mexico was gobbled up by bacteria (See earlier blog) but Joye et al. in a recent comment in Science are not convinced (DOI). Here is what they think:

  • The new estimate for the amount of methane released is 10 times the number used in the Kessler model
  • The Kessler team only looked for methane where they thought it had gone to (south-west of the well-head) but other areas are also affected
  • Methanol was distributed at the disaster location as part of the relief effort adding more carbon for the bacteria to chew on. One of the bacteria found (Methylophaga) that showed the largest increase in numbers is known to consumer methanol but not methane
  • You can find midwater oxygen-depleted areas all over the place if you look for them, for example in the Mississippi Canyon
  • Kessler should have considered other techniques to back up his claim for example relative abundance of carbon-13 in the remaining methane

  • Luckily the same issue of Science also contains the Kessler rebuttal (DOI) so here we go:
  • No, even when new higher but unconfirmed estimates of total carbon output are accepted the new value is at the most 3 times higher but not 10 times higher
  • No, Kessler did hunt for methane in other directions than just that of the plume
  • No, some bacteria consume methane and release methanol, which is then consumed by other bacteria such as Methylophaga. Industrial methanol has nothing to do with it.
  • Kessler did collect data on oxygen depletion in the Mississippi Canyon but trends were not revealed
  • 13C measurements of residual methane proved difficult because most methane had disappeared

  • So who is right here? Of course, when the total amount of methane released gets a new higher figure the Kessler model has a problem. On the other hand if Joye still thinks there is a lot of methane still out there she should get on a boat and start doing measurements. The matter of the methanol is intriguing: where does it come from? An earlier blog here took a closer look at the nature of the surfactant used in vast amounts by BP with the purpose of dispersing the oil. No methanol there but another alcohol. Could 2-butoxyethanol have messed things up?