June 16, 2010 | 3
Editor’s Note: A team of researchers led by John Kessler, Texas A&M College of Geosciences chief scientist and assistant oceanography professor, has traveled to the Deepwater Horizon disaster area to study the methane leaking into the Gulf of Mexico (along with tens thousands of barrels of crude oil) daily at the site of the damaged Macondo 252 well. Kessler, along with David Valentine (a professor of marine sediment geochemistry, biogeochemistry and geomicrobiology at the University of California, Santa Barbara) and the rest of his colleagues are hoping to come away with a rough estimate of the spill’s size by the time his team returns home on June 20, followed by more accurate estimates as they complete their analysis of the information collected. Other objectives of the expedition onboard the RV Cape Hatteras include trying to determine how the methane might be removed from the water (whether eaten by waterborne microorganisms or released into the atmosphere) and how methane concentrations will change over time. Valentine filed the following dispatch. This is the team’s third blog post for Scientific American.
Wednesday, June 16, 2010
After several days of waiting, we received approval to begin sampling within five nautical miles of the wellhead, but not closer than 500 meters, and nowhere to the east side of the wellhead. We were given a period of 24 hours and told that the clock was now started. Our entry into this scene of industrial disaster reminded me of seeing the band Pink Floyd while in college, waiting in line all night to get tickets to the inner circle.
But instead of good music and a laser show there was a flame taller than any I have ever seen, and it sounded like a jet engine across the water. Fortunately, our mandatory breathing masks kept us from feeling the effects of organic vapors that persist near the wellhead (and at the concert too I recall). We quickly agreed as a science party that we would sample for the next 24 hours straight, despite all having been awake for almost 12 hours already—this chance probably would not come again.
We decided to sample the full depth of the water column at as many stations as we could, in the area opened to us, and to perform gas surveys in the surface water around the rigs while we were processing the samples brought up from the depth. Darkness never truly descended as the night was more and more dominated by the large jet of burning methane emanating from the drill ship Discoverer Enterprise (see photo). This display served as a constant reminder for one of our collective scientific goals: to understand the fate and impact of the natural gases that silently make up half this spill and that have played such a critical role in the anatomy of the disaster.
Methane has been the focus of much discussion, and is something we are looking at in great detail. In addition we are considering two close cousins of methane, the often-ignored ethane and propane. We are not only sampling for their distribution in the waters, but also developing new approaches to determine how rapidly bacteria will consume them, and identifying who those organisms are. One question we would like to address is what effect these gases have on the reduction in oxygen that we observe at discrete horizons in virtually every cast we make. We brought with us unique tools to measure the abundance of (non-radioactive) isotopes in methane and carbon dioxide and are beginning to apply these tools for this purpose.
Lastly, we have an acronym for this cruise, PLUMES, which stands for Persistent and Localized Underwater Methane Emission Study. This barely beat out PLUNGES (Persistent and Localized Underwater Natural Gas Emission Study) among others.
Image of burning methane at the Deepwater site courtesy of David Valentine