June 14, 2010 | 8
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 site 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. This is his first blog post for Scientific American.
Saturday, June 12, 2010
After a busy three weeks of preparations, we sailed from Gulfport, Miss., at 4 p.m. Central Time. The objective of our cruise is to study the natural gas component of the oil spill, estimated by BP scientists to be 40 percent by weight of the material escaping the broken riser pipe. Natural gas in this instance is predominately methane, a potent greenhouse gas and a possible contributor to the loss of dissolved oxygen from the Gulf waters. Our measurement campaign began immediately as we left the dock. Using a continuous technique involving seawater pumps, gas chromatographs and cavity-ring down spectrometers, we measured the dissolved methane and carbon dioxide concentrations and natural stable isotopes in surface waters while the boat was underway. The natural stable isotopes are used to quantify sources, sinks and fluxes of the gases from the surface waters, and these measurements can ultimately determine gas fluxes across the air-sea interface.
Outside of only a few miles from the port, the smell of oil was abundant even though oil was not visible on the sea surface. While most oceanographic research at sea involves long hours, tight living quarters and significant manual labor, the payoff beyond the thrill of scientific discovery is the opportunity to visit beautiful, peaceful and often exotic locations on this planet. This project will most likely not involve those benefits. Nonetheless, the results of this project will contribute to our understanding of not only this spill, but also our planet in general, of which I look forward with great anticipation.
Sunday, June 13, 2010
We arrived at the spill around 3 a.m. local time. I awoke to begin our sampling and measurement campaign. In the distance (where we are not permitted to sail), one can easily see the activity of the attempts to cap the well. This includes the drill ships for the relief wells, gas flaring from the oil recovery efforts, and multiple support and supply ships. In addition to surface water sampling, which began the previous day, we began profiling the chemical and biological properties of dissolved gas in the water column. Large quantities of natural gas appear to be in subsurface water layers, but more measurements are required to characterize this feature.
Daylight revealed a near continuous sheen of oil on the sea surface and intermittent patches of thick cake batter-like oil. Quickly, this spill site is becoming familiar. By sunset, the sight of the containment efforts no longer seems foreign. Our team of scientists is working eagerly and earnestly together. The crew of the boat is remarkably efficient and helpful. We cannot collect the data fast enough to satisfy our curiosity.
Images courtesy of Texas A&M College of Geosciences/John Kessler