What Is an Emergency Response Team's Oil Spill Technique for Solubility?

Dispersants

• Dispersants are detergents, chemicals that belong to a class of molecules called surfactants. Like other similar chemicals, detergent molecules have a water soluble, or hydrophilic, region and a water insoluble, or hydrophobic, region. When strewn across an oil slick, the dispersants form clusters called micelles. The hydrophobic region of each dispersant molecule points inward toward the center of the micelle, while the hydrophilic region points outward. At the center of the micelle lies a cluster of oil molecules, shielded from direct contact with the water.

Solubility

• The dispersant and oil micelles are much more soluble, because the hydrophilic region of each dispersant molecule interacts with surrounding water molecules, while the hydrophobic oil molecules remain hidden inside. If all goes well, the dispersants break up the oil slick and scatter the oil in the form of countless tiny droplets; waves and currents carry these droplets away. Both the dispersants and the oil molecules are organic compounds, and various ocean microbes can exploit them as a source of carbon and energy.

Pros and Cons

• By scattering the oil in the form of countless tiny droplets, dispersants greatly increase the rate at which microbes can break it down. They also help to defer its arrival at the coastline. These benefits don't necessarily imply, however, that these chemicals are always the best solution for an oil spill. In calm waters, for example, dispersants are much less effective. Depending on the type of chemical, the concentration and the local conditions, dispersants themselves may also be toxic to marine life.

Considerations

• Wildlife are more likely to come in contact with oil scattered over a wider area, especially in the form of water-soluble droplets. That's why dispersants can potentially increase wildlife exposure to crude oil and thereby cause more damage. Scientists don't yet know a lot about how dispersants and oil behave in the deep sea. Consequently, although dispersants are a standard tool in oil spill cleanup, like all other such tools they come with both advantages and disadvantages. Whether it's better to make the oil more soluble and disperse it or try to concentrate and contain it depends on the weather, the conditions and the extent of the spill.