On April 20, 2010, the offshore drilling rig Deepwater Horizon exploded, spewing almost five million barrels of oil into the Gulf of Mexico. This was the largest marine spill in history.

David Valentine, a UCSB earth science professor, recently returned from his trip to research the effects of BP’s oil spill in April 2010. The findings of his research may prove to be crucial in addressing the environmental consequences of the disaster.

Valentine’s related research at UCSB involving the microbe’s role in natural processes made him a logical candidate to assess the aftermath of the disaster.

“I spend a lot of time in the deep sea studying the interactions of gas-oil-water, so my involvement was natural,” Valentine said.

Since roughly 25 percent of the spill in the Gulf was methane gas (a greenhouse gas), Valentine’s research in studying the ocean’s capacity to act as a biological filter for methane gas was particularly pertinent. Consequently, the spill allowed Valentine a one-time opportunity to conduct new and important research.

Valentine normally conducts his research at local seeps such as UCSB’s Coil Oil Point. In comparison, the Gulf spill provided Valentine a rare opportunity to observe the effects of a large-scale oil contamination.

“The impact of seeps is local, meaning we typically lose the biological signal as mixing processes dilute the compounds of interest,” Valentine said. “In the Gulf, the emission was so massive that we could track the impact for a period of months and study what the bacteria was doing.”

Recognizing Valentine’s research and expertise, the National Science Foundation and Dept. of Energy provided Valentine with the funding necessary to become fully involved with their spill research. Additionally, the National Oceanic and Atmospheric Administration (NOAA) asked Valentine to lead research expeditions.

Especially important in Valentine’s research was his work in determining the very least amount of oil released into the deep sea, providing a good estimate for the rate of the oil’s spread. To estimate the amount of oil that was spilled, Valentine measured the amount of methane gas released. Valentine’s method has proven invaluable in disaster damage assessment.

In an article in Nature, Valentine wrote, “Visual observations of leakage from the ruptured pipe are unreliable because of the turbulent flow and the uncertain water content of the gas-oil-water mixture. Spot measurements of the flux at any given moment can’t be scaled up reliably, because the flow may not be constant. Satellite photos and boat measurements help to assess the distribution and thickness of the surface slick, but these measures are also highly variable with time, place, weather conditions and dispersant application. In what is likely to be the worst oil spill in U.S. history, a more accurate way to estimate the spill’s magnitude [was] needed.”

In addition to quantifying the amount of hydrocarbons that escaped, Valentine also investigated the fate of these gases. His research at UCSB also includes the biodegradation of other hydrocarbons by bacteria. Valentine’s article in Science Xpress reported there were many plumes of methane and other hydrocarbon gases in the deep water of the Gulf in June. However, by September his team found the plumes had disappeared; and in their place were residual methane-eating bacteria, a testament to the marine environment’s ability to clean up after an enormous manmade disaster.

However, Valentine also observed a million-ton decrease in dissolved oxygen that his team attributes to the respiration of methane by these bacteria. In sum, the Gulf’s food web is incredibly delicate, and oxygen depletion may be having detrimental effects on marine life. Valentine believes much of the larger hydrocarbon oils still remain in the deep water, and their effects are still under investigation.