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Oily residue from the BP Deepwater Horizon oil spill comes ashore in the surf in Gulf Shores, Ala., Friday, June 25, 2010. ((Dave Martin/Associated Press))

Oil cleanup efforts in the Gulf of Mexico are overlapping with the 2010 Atlantic hurricane season that officially started in June.

According to the U.S. National Oceanic and Atmospheric Administration (NOAA), high winds and rough seas will mix and "weather" the spilled oil, which can help accelerate the biodegradation process.

Kelly Hawboldt, associate professor, faculty of engineering and applied science at Memorial University in St. John's, N.L., says a hurricane could also cause oil that had settled to the bottom to be redistributed, potentially ending up in surface areas of the ocean that are home to birds and other animals.

'All the animals that hang out there — they are all vulnerable to it,'—Kelly Hawboldt

Hawboldt is an expert in environmental safeguards for offshore oil platforms.

"Anything that occupies that water interface — all the animals that hang out there — they are all vulnerable to it," Hawboldt told CBC News.

A storm could also create a greater number of tar balls, those globs of oil that coalesce and take a very long time to degrade. "That stuff getting redistributed on the coast would be very bad," she said.

NOAA notes that while high winds may distribute oil over a wider area, it is difficult to model exactly where the oil may be transported. A hurricane's winds rotate counter-clockwise. Thus, in very general terms:

  • A hurricane passing to the west of the oil slick could drive oil to the coast.
  • A hurricane passing to the east of the slick could drive the oil away from the coast.

However, the details of the evolution of any particular storm, the track, the wind speed, the size, the forward motion and the intensity are all unknowns and will affect any warnings or notices that may be issued.

NOAA adds that oil that is beneath the surface of the water is generally already well dispersed — except near the leaking well. It can be measured only in parts per million levels or less, so a hurricane would likely disperse the oil even further.   Other experts have said that high winds could also hamper cleanup efforts, as boats aiding in the process will have to evacuate the area and booms used to contain slicks will be unable to remain in place.

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Beachwalkers check the oil stained shore in Gulf Shores, Ala. Oil cleanup crews are working day and night to keep the beaches as clean as possible despite the oil coming ashore. ((Dave Martin/Associated Press))

NOAA adds that storm surges may carry oil into the coastline and inland as far as the surge reaches. Debris resulting from the hurricane may be contaminated by oil from the Deepwater Horizon incident, but also from other oil releases that may occur during the storm.

Overall, it's unclear what exactly will happen. The only precedent is Hurricane Katrina, which in 2005 led to nearly 50 oil spills in the lower Mississippi corridor, according to John Pine, director of the Disaster Science and Management Department of Geography and Anthropology at Louisiana State University. Pine published a case study on Hurricane Katrina and its impact on coastal and ocean environments in the June 2006 issue of Oceanography.

Pine looked at one spill, by Murphy Oil Corp., which involved the release of 3.1 million litres into a highly populated area called St. Bernard Parish, located southeast of New Orleans. Following the oil spill, 1.2 million litres were recovered, 742,000 litres were contained, 1.2 million litres evaporated and 22,712 litres were never recovered.

By comparison, the current worst-case estimate of what's spewing into the Gulf from BP's spill is about 9.5 million litres a day.

The Murphy spill affected 1,700 homes in a residential neighbourhood nearby and infiltrated local canals. It also affected marshes and other coastal environments.

One possible long-term impact is a decrease in biodiversity in the areas of the Gulf affected by the spill, said Hawboldt. She said that years after the Gulf War of the 1990s, in which an enormous amount of oil was dumped into the Persian Gulf, oil-degrading microbes flourished but other microbial populations dropped off dramatically.

Dispersants could do more harm than good

BP adding millions of litres of chemical dispersants to the oil leak, attempting to break up the oil. It's a move that has angered many environmental groups, including the U.S. Environmental Protection Agency (EPA) which worries that it's essentially a huge scientific experiment that could have big implications for human and animal life.   Dispersants are products with two component parts - one half is more soluble in oil than in water and one half is more soluble in water than in oil. Composed of substances such as polymers, sulfates and glycol, these proprietary blends break up oil slicks into smaller droplets so that they can then be further degraded by microorganisms.

Environmental and public health groups say dispersants can cause human illness, and kill mammals and aquatic life. They also point out that manufacturers of the products do not have to disclose their ingredients.

According to Hawboldt, dispersants are chemically toxic if used in the wrong concentrations. She says that given the current scenario in the Gulf, in which the exact quantities of gushing oil are unknown, it's hard for scientists to know just how much dispersant to use. And with unknown quantities at play, the potential for misuse is high.

"I know they've been distributing boatloads," she told CBC News. "You wouldn't want to be putting [dispersants] on for the next month."

On May 26, the EPA ordered BP to reduce the amount of dispersants it uses against the oil spill by 75 per cent. Before that date, BP was using almost 265,000 litres of dispersants every day.