Researchers at the University of California, Santa Barbara, recently published a study describing how underwater topography and currents affected the disappearance of methane plumes in the Gulf of Mexico following the April 2010 Deepwater Horizon oil spill.

The study, published in the Proceedings of the National Academy of Sciences follows up on oil spill researcher and UCSB geochemist David Valentine’s older publications. Valentine’s previous work has examined the ecological aftermath of the oil spill.

“Our original study was in 2010, published in the journal Science,” Valentine said. “We also had a series of papers in 2011, including another in Science, a third in Environmental Science and Technology and a fourth in PNAS. Each of these previous papers captured a snapshot of what was happening in the deep plumes. The current paper builds on these observational works and develops the theoretical framework to explain the many seemingly disparate observations.”

Valentine collaborated with Igor Mezić, professor of mechanical engineering at UCSB. Mezić’s previous work helped to predict how the oil would spread following the spill. Together, the two researchers combined Mezić’s hydrodynamic data and Valentine’s bacterial work to create a single, comprehensive model explaining how methane broke down and disappeared in the Gulf.

The model explained how physical components of the Gulf contributed to bacterial consumption of methane.

“Igor led the physical motion component of the effort and developed the physical framework and interpretation,” Valentine said. “These components were fundamental to the study.”

Specifically, Valentine and Mezić’s expert knowledge in their respective fields and attention to the Gulf’s unique marine conditions proved crucial in predicting and explaining the relationship between the bacteria and methane plumes present after the spill.

“The Northern Gulf at these depths is somewhat restricted with regard to water motion as it is bounded on three sides and has no prevailing current at these depths,” Valentine said. “The result is that the plumes sloshed around the northern gulf, frequently encountering the wellhead on multiple occasions. This impacted the bacterial response through pulsed accelerations of metabolism for select hydrocarbons, as bacterial blooms would return to the wellhead.”

The resulting model from Valentine and Mezić’s collaboration accurately describes how methane vanished from the surrounding waters following the Deepwater Horizon spill.

The researchers hope that this model will help to prevent future disasters before they occur.

“Understanding these processes at a drill site should be done before drilling, using models such as the ones we have developed,” Mezić said. “We use models to build planes — why not use them to understand potential environmental impact of a spill?”