Biodegradation of Dispersed Crude Oil

The biodegradation process is fundamental to oil spill science and understanding the fate of oil, whether it is burned, dispersed, or dealt with mechanically. Biodegradation is the process through which oil is broken down into smaller compounds.

The fate of spilled oil and its byproducts is important to residents of our region who depend upon healthy marine resources for subsistence, food, and their living.

Biodegradation of oil projects:

Biodegradation of dispersed oil in Prince William Sound waters

This Council project will help us understand whether chemically dispersed oil in Prince William Sound conditions would be biodegraded by indigenous microfauna or float around until it either resurfaces or is carried downstream.

Microfauna are essentially marine bacteria and other plankton that can eat and digest dispersed oil, breaking it down into simple molecules such as carbon dioxide, water, or methane.

The project will compare the biodegradation by microfauna of chemically dispersed Alaska North Slope crude oil with physically dispersed crude oil at ambient Prince William Sound conditions. The project also supports the council’s mission by providing the organization with the best scientific knowledge to help make informed, scientifically justified, decisions and comments on spill response policy and regulatory development.

The Council contracted with Michel Boufadel at the New Jersey Institute of Technology to conduct the experiments.

The project began in 2012 with three consecutive microcosm trials conducted to investigate biodegradation of dispersed oil in seawater in the lab. These trials were performed under conditions with low nutrients (background seawater) and high nutrients (additional nutrients added to the background seawater). These first tests were aimed at refining an oil dispersion technique prior to conducting a full experiment which will take place in Summer 2013.

Once the project is completed, the study results will be published in a peer review journal. The research can then be used as the basis for council comments on spill response policy and regulatory reviews by regulatory agencies and the Regional Response Team.

Incomplete biodegradation of dispersed oil

The Council’s Scientific Advisory Committee decided to commission a report in 2013 on the incomplete biodegradation of crude oil.

The committee had been studying the biodegradation of dispersed oil and its toxicity. The problem they found is that the biodegradation of oil is generally not a complete process. In theory, hydrocarbon should break down completely into carbon dioxide and water. Since it does not, many different compounds are formed as part of this incomplete process. In addition, standard methods analyzing biodegradation shows that as much as 75% of the product will be missed or that the breakdown would be overstated by as much as 4 times.

Another problem is that some of the biodegraded products are more toxic to aquatic life than the original compounds.

Improved analytical methods and recommendations for further work are included in the report.

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