Worst of the Gulf oil spill toxins still remain, research finds

In the months after the April 2010 Deepwater Horizon oil spill, bacteria in the Gulf of Mexico consumed many of the toxic components of the oil, but not the most toxic contaminants, says new research.

According to two studies by Florida State University (FSU) conducted in a deep sea plume, a species of bacteria called Colwellia likely consumed gaseous hydrocarbons and perhaps benzene, toluene, ethylbenzene and xylene compounds that were released as part of the oil spill.

But the research also showed that bacteria did not consume the most toxic parts of the oil spill in the water column plume or in the oil that settled on the seafloor.

The most toxic contaminants are called polycyclic aromatic hydrocarbons or PAHs. PAHs are a group of semi-volatile organic compounds that are present in crude oil and can cause long-term health problems such as cancer.

FSU Assistant Professor Olivia Mason led the research. She said:

Those PAHs could persist for a long time, particularly if they are buried in the ocean floor where lack of oxygen would slow PAH degradation by microorganisms. They’re going to persist in the environment and have deleterious effects on whatever is living in the sediment.

When the Deepwater Horizon spill occurred, more than 4 million barrels of oil spilled into the Gulf of Mexico. Some of that oil has never been accounted for, and thus has unknown environmental and health consequences for the region.

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