Learning from the Gulf Oil Spill

The impact of the oil spill in the Gulf of Mexico is still creating headlines two years later. Helen White, assistant professor of chemistry at Haverford College, Haverford, Pennsylvania, USA, has published a paper on her group’s findings from the spill. Kate Mosford of LCGC Europe spoke to her to find out more.

Was the impact of the oil spill greater or smaller than you had believed it to be?

White: Considering the magnitude of the oil spill and the fact that it occurred in the deep water, it seemed possible that deep-sea coral communities in the Gulf of Mexico might be impacted. During a 3-week research cruise in November 2010, coral communities >20 km from the Macondo well blowout were observed to be healthy, but impacted corals were observed closer to the Macondo well, at a distance of 11 km.

Can you say approximately how long, if at all, it can take a coral community to recover from such damage?

White: The impacted corals exhibited varying degrees of stress including bare skeleton, excess mucous production and covering by the brown floc material. One coral that had a light covering of floc in November appeared to have recovered when we returned in December. Other corals or parts of corals covered by floc died. We are continuing to document the health of corals at the impacted site so that we can determine their ability to rebound.

An analysis was carried out to identify the source of the oil. Can you detail how you collected samples and how you identified the specific oil?

White: As a geochemist, my primary aim in this research was to determine the composition of the brown flocculent material covering the corals and the source of any petroleum hydrocarbons present. Because oil can naturally seep from cracks in the sea floor of the Gulf, pinpointing the source of petroleum hydrocarbons in Gulf samples can be challenging to scientists, especially since oil is comprised of a complex mixture of different chemical compounds. There are, however, slight differences in oils that can be used to trace their origin. To identify the oil found in the coral communities, I worked with marine chemist Christopher Reddy and research specialist Robert Nelson from Woods Hole Oceanographic Institution. We used an advanced technique called comprehensive two-dimensional gas chromatography to analyse.

Oil spills are appearing to be a more regular occurrence. What can we learn from the spill?

White: Our research findings are important because they underscore the unprecedented nature of the spill in terms of its magnitude, release in deep water, and impact to deep-water ecosystems. Because corals do not move, they are an excellent indicator of what has flowed past them. The impact to a century-old coral community may have consequences for the greater ecosystem. For instance, coral mucus is a food source for other organisms living in deep-water communities, and as such, oil may be transferred through the food chain via coral mucus. Future work will explore these effects and determine if other coral communities were impacted by the oil spill.

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