Researchers have discovered a new way to track the presence of oil in water even after visible slicks have vanished, a tool that could help give scientists a better idea of how oil spills impact the environment.
(ByThe method involves tracking the levels of carbon dioxide and oxygen released by underwater marine microbes in order to tell how much oil is still present after a spill.
The team of researchers led by Xinping Hu, an assistant professor of chemistry at Texas A&M University — Corpus Christi, found underwater areas where there was oil present the ratio of carbon dioxide and oxygen released by marine life varied significantly.
The team studied samples of subsurface waters taken before and after the 2010 Gulf of Mexico oil spill. Samples were taken from 2006 to 2012.
According to a Texas A&M release, the ratio of carbon dioxide to oxygen found underwater is typically fairly steady, kept level as marine microbes feed on oxygen from decomposing microalgae.
In areas where oil is present, however, that ratio is thrown out of whack as those same microbes consume the petroleum.
Tracking the changes allows researchers to study where oil travels and how long it remains in the water even after it has disappeared from the water’s surface.
Hu said the method is a big step forward in scientist’s ability to track how broad an impact a spill can have.
“Oil in the water can do a lot of damage to sea life,” Hu said. “If you know it is there, you have to study the consequences.”
The method has already been used to measure the 2010 oil spill’s impact on Louisiana coastal waters.
Samples taken from subsurface waters west of the mouth of the Mississippi River after the spill showed different ratios of carbon dioxide to oxygen, indicating oil in the water.
By 2011 and 2012, ratios in those areas had returned to normal levels, suggesting those areas were clear.
Hu cautioned there are limits to the method. Surface waters may test clean, but still be affected by oil residue present in sediment on the ocean floor and floating in the water, he said.
Hu and his team plan to continue their research in the Gulf, studying how quickly carbon is put into and removed from the water as well as how outside factors influence that process.
The research was conducted in partnership with experts from the Louisiana Universities Marine Consortium, the University of Delaware and the University of Texas Marine Science Institute.
The National Oceanic and Atmospheric Administration and the Gulf of Mexico Research Initiative funded the work.
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