Marine Technology Meets the Gulf Oil Disaster
Florida researchers are monitoring the long-term dynamics of the Deepwater Horizon Disaster
Larry Langebrake is director of the marine technology program at SRI International in St. Petersburg. Researchers there study marine environments — surface-level and undersea — using some of the world's most sophisticated sensors. After the Gulf spill, SRI deployed a highly sensitive instrument called a mass spectrometer, which is lowered into the water and then raised back to the surface, providing continuous onsite readings of the chemical composition of the water, including the presence of toluene, methane and other hydrocarbons associated with oil.
The St. Petersburg program is a branch of SRI International, a California-based non-profit research institute that conducts client-sponsored research and development for government agencies, commercial businesses, foundations and other organizations. Executive Editor Mark Howard talked with Langebrake for a scientist's perspective on the long-term dynamics of the spill. Following are highlights and themes from that conversation:
We need to find out exactly where the oil is below the surface and in what concentrations. "That's the real issue," says Langebrake. "We have a large quantity of oil and a large quantity of dispersants introduced continuously over a long period of time. The oil is affecting much more than what we see on the surface. The first thing that needs to be done is to quantify in three dimensions what's going on under the surface. So far it's only been looked at in very select areas with a minimum number of instruments. Candidly, there are very few instruments that can measure exactly what the hydrocarbon presence is."
Forget discussion of oil "plumes." The oil, says Langebrake, "is not uniform. It's not like one big cloud in the sky. It's structured three dimensionally and likely to be very disconnected or layered. There are likely to be regions of hydrocarbons, each with a complex mix of chemicals, ranging from very dense tarballs to lighter regions with components of something like paint thinner and everything in between."
Natural bacteria and oxygen-rich conditions near the surface help break down the oil, but we need to learn what happens to oil deep undersea. News coverage of the Loop Current and movement of the oil on the surface can leave the impression that the entire Gulf is a swirling mass of constantly moving water, but water in deeper regions of the Gulf doesn't necessarily move as much. In the depths, the water might not be moved by strong currents for years, decades or longer — meaning very little new oxygen is introduced into that environment. The bacteria that consume hydrocarbons need oxygen, however. If concentrations of oil and other hydrocarbons end up sitting more or less stationary at depth, Langebrake says, one possibility is that the oil-consuming bacteria adapt and become opportunistic. Another possibility is that the process of consuming the oil could be substantially slowed.
"These processes are really not well enough understood to say what will happen," Langebrake says. "Our speculation is that if water doesn't move much, it could be decades, if not longer, for things to return to normal."
We need to understand the effects of so much oil on the Gulf's ecosystem. At great depths, the consumption of oxygen by the bacteria that attack the oil could leave "big areas of decreased oxygen and more CO2." The impact of those conditions on other creatures is unknown — if there's no oxygen, for example, what happens to the other deep-sea organisms that need it? And what will the oil do to organisms — from plankton to fish — that are part of the complex, linked and diverse sea-life community in the Gulf, from the smallest bacteria to fish. "It's going to impact the food web, and it's important to know whether the impact will be minimal or far-reaching," Langebrake says. "The answers could influence our decisions on everything from state investment priorities to whether we can order Gulf seafood for dinner."