Chemical dispersants are substances applied to floating oil slicks that are designed to break the oil into smaller droplets.
Dispersants do not remove oil from the water. Instead, the droplets mix into the water column.
This results in less oil on the surface of the water. In some situations, dispersing the oil may be preferable to an oil slick on the surface that could contaminate sensitive shorelines.
However, there is a tradeoff. Marine animals in the water column are exposed to the tiny droplets and the dispersant chemical.
Studying dispersants in Alaska waters
Most research on dispersants has been done on water that is warmer and saltier than waters in Alaska. To fill this gap, the Council has sponsored years of research, studying questions such as:
- Are these products successful at dispersing oil in waters similar to conditions in Prince William Sound?
- Do dispersants and dispersed oil affect local marine species? If so, how?
Overall, the Council’s research has shown that:
- Dispersants do not work as well in our cold, less salty waters.
- Dispersed oil has a negative effect on some of our local species.
More details available in our studies
Because of these concerns, the Council has long endorsed mechanical recovery as the primary tool to clean up an oil spill. Unlike dispersant use, mechanical recovery with booms and skimmers removes oil from the water. Current state and federal laws and regulations hold that dispersants should be used only if it is clear that mechanical cleanup methods such as booming and skimming won’t work.
Position on Dispersant Use:
It is the position of the Prince William Sound Regional Citizens’ Advisory Council that chemical dispersants should not be used on Alaska North Slope crude oil spills in the waters of Prince William Sound and the Exxon Valdez oil spill affected region.
Full, detailed position
See also: Summary of supporting literature (PDF)
In 2022, the Board held a 4-part series of workshops to help members understand the science of how dispersants work; how decision-makers evaluate whether to use dispersants; and the tradeoffs of using, or not using, dispersants.
After careful review and discussion, the resulting position opposed the use of chemical dispersants in Prince William Sound and the region affected by the Exxon Valdez oil spill. The update is evidence-based and adds rationale behind the position.
A report by Nuka Research & Planning summarized the workshops and process for the update: Dispersants Use Position Update – Summary of Board of Directors WorkshopsÂ