Scientific Support Provided by Fisheries and Oceans Canada During the Gulf of Mexico Oil Spill Response Operations Boosts Canada's Oil Spill Preparedness
Following the Deepwater Horizon oil platform explosion in the Gulf of Mexico in 2010, the U.S. Environmental Protection Agency called on Fisheries and Oceans Canada to provide scientific and technical expertise in the spill response operations. Over a four month period, a team of research scientists and technicians from the Department assisted the Unified Command to monitor the fate and transport of an estimated 4.9 million barrels of crude oil that were spilled into the Gulf.
"We've been collaborating on oil spill research with the United States since the early 1990s," says Dr. Kenneth Lee, the Canadian team lead in the Gulf of Mexico and Executive Director of the Centre for Offshore Oil, Gas and Energy Research (COOGER), a DFO centre of expertise. The experience gained from working together in the Gulf of Mexico has enhanced our knowledge on how to select the best clean-up techniques and design monitoring protocols to confirm their effectiveness and potential detrimental effects." says Dr. Lee.
Chemical oil dispersants
Dr. Lee is a leading expert on the use of chemical dispersants to clean up oil spills; one of the techniques used and evaluated during the Deepwater Horizon spill. Chemical oil dispersants work much like dish soap by changing the surface tension of the oil so it breaks apart into very small droplets that mix more easily with water. Tides, currents and other physical processes help to disperse the oil into the water column (below the water surface), where naturally occurring bacteria can break down much of the oil into non-toxic compounds. Less oil on the surface of the ocean also helps protect wildlife such as sea birds and mammals from becoming oiled, and reduces the probability of oil reaching shoreline environments.
"Chemical oil dispersants are only used when the environment is contaminated by oil. Approval for their use is based on the results of a net environmental benefit analysis that indicates its use to be more beneficial than natural recovery and other treatment strategies," says Dr. Lee.
Using dispersants at depth
During the spill response, considerable effort was made to prevent the oil from reaching shore and sensitive wetlands where it would be more difficult to clean up. This included the deployment of skimming vessels, the installation of absorbent booms to protect the coastline, and the use of chemical oil dispersants applied to the surface oil slick. Concern was also raised over the concentration of volatile organic compounds Footnote 1 around the spill site that were potentially dangerous to the health of people working on clean-up operations. To address these issues, a decision was made to add chemical dispersants directly to the oil as it leaked from the wellhead at a depth of 1,500-metres, to increase the effectiveness of the dispersants and reduce the amount required. In comparison to aerial spraying, this application method enhanced the contact of oil with dispersant and reduced the amount of more viscous emulsified oil that formed when the oil mixed with water and rose to the surface. Emulsified oil is much more difficult to clean up, so preventing its formation was critical.
The COOGER field team arrived in the Gulf of Mexico on May 8, 2010 just as the first attempts to stop the flow of oil from the wellhead were underway. COOGER's main goals were to:
- determine the effectiveness of the chemical oil dispersants that were used; and
- conduct ongoing water column sampling and analysis to track the subsurface oil plume from the blown-out wellhead.
In collaboration with U.S. counterparts, the Canadian team carried out a 24/7, on-site monitoring program over a four month period using two research vessels. The team set up protocols for monitoring the oil plume using three types of analysis: CDOM fluorescence Footnote 2, Small Particle Concentration (SPC) Footnote 3, and the sum of BTEX compounds Footnote 4. LISST-100X analysis Footnote 5 was also used to measure the concentration of oil droplets in the water column and to assess oil droplet size, which is an indication of how well the oil has been dispersed. The greater the dispersion, the smaller the droplets will be.
The techniques used in the Gulf were the result of years of research conducted at the Bedford Institute of Oceanography (BIO). "We have developed a method that uses fluorescence to distinguish whether oil has been chemically or physically dispersed, and we assessed this technique in the Gulf of Mexico," says Dr. Lee. Following up on information collected during the Gulf response, the U.S. Government subsequently funded two major experiments at BIO in 2011 to compare various methods of using fluorescence to monitor oil in water.
"The research findings from the Deepwater Horizon spill have provided evidence that the chemical oil dispersants used in the Gulf of Mexico helped break the oil into very small droplets in the water column and that, subsequently, bacteria degraded much of the oil very quickly," says Dr. Lee. "The consensus is that chemical oil dispersants probably accounted for the removal of 25 to 26 percent of the oil, which is much more than other methods including burning, which accounted for roughly three percent of the oil. So, chemical oil dispersants are now seen as one of the technologies that can be highly effective." Another concern was that the degradation of oil by bacteria might deplete oxygen in the water and impact marine life, however water sample analyses revealed that this didn't happen.
The oil spill response operations in the Gulf of Mexico have provided new insights for development of international guidelines on the use of chemical oil dispersants such as when and when not to use them, how much and what type to use, and potentially how effective they might be when applied beneath the surface of the ocean. A considerable amount of additional research and international collaboration is underway following the Gulf spill to improve upon response techniques and develop new international standards and regulations. For his part, Dr. Lee has been asked by the International Maritime Organization to co-chair a Working Group on the development of updated guidelines for chemical oil dispersant use.
The findings from the Gulf have a direct relation to Canadian interests. "As a result of the Gulf of Mexico research, the petroleum industry is interested in chemical oil dispersants and in-situ (on-site) burning for possible use in the event of an oil spill in the Canadian Arctic, where there is potential for exploratory and production drilling in the Beaufort Sea," says Dr. Lee. "Ice could act as a boom to prevent the oil from spreading so it could potentially be ignited if it was thick enough, and chemical oil dispersants could be applied over a large area by aircraft or used at depth in the event of a subsurface blowout."
If anyone had asked Dr. Lee 20 years ago if he would consider using chemical oil dispersants on the east coast of Canada, he would have said 'no', because they were thought to be ineffective for the viscous "waxy crude oils" found in fields such as Hibernia. Over the last decade or more, however, Dr. Lee says new formulations of chemical oil dispersants have been developed that could work on some heavier oils and there is also a push to develop formulations specifically for use in the Arctic. Fisheries and Oceans Canada research is a long-standing, major contributor to the science of how to best use these substances to help marine environments rebound from even massive oil spills.
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