Slick Manoeuvres

There is a company in Canada that really knows how to get around. They have been hired to work in places such as Scotland, South America, Kuwait, and most recently, Russia. Can you think of something that all of these places have in common? If not, does the Exxon Valdeez ring a bell? Well, their common ground is oil spills. Oil can be introduced into our waterways by natural or unnatural causes. One way is by accidental oil spills of huge tankers that transport oil from one country to another. Natural disasters such as earthquakes can also cause oil and water to be mixed. In order to preserve wildlife and decrease possible damage from excess oil, Oil Spill Control Services of Toronto, Ontario uses chemical techniques to locate the spill as well as to do their dirty work.

When oil and water are mixed, they are immiscible (will not mix) and most oils, being less dense (mass/volume) than water, will float. Oil (petroleum) consists of the elements carbon, hydrogen, oxygen, sulfur and nitrogen. Carbon and hydrogen are present in the largest proportions and therefore, most oils are called hydrocarbons. Oil that contains only carbon and hydrogen is light coloured and odourless whereas oil that also contains nitrogen, sulfur, and oxygen, tends to be dark, viscous (resistance to flow), dense, and odouriferous (stinky). The many different types of oil have different physical and chemical properties that influence their behaviour. For example, the extent to which the oil spreads is influenced by properties of the oil such as viscosity, density, and wax content as well as by weather conditions and temperature. Once the oil spreads, processes such as evaporation, dissolution (some compounds dissolve), dispersion (compounds separate from each other), emulsification (water is incorporated into floating oil), and photooxidation (oxidation by the Sun's light energy) are enhanced.

When oil finds its way into water, the course of action is to find the exact location of the oil spill. This cannot be done effectively from a boat and therefore, Dr. R. Goodman of ESSO in Calgary has developed an aerial surveillance protocol that uses such techniques as side looking airborne radar (SLAR), ultraviolet radiation (UV), and infrared radiation (IR). SLAR is used to determine surface roughness of the water (when oil is present, the water involved becomes very calm), UV light is used to detect whether there are hydrocarbons in the water, and IR is used, by temperature differences, to detect the thickness of the slick.

Depending on the location, oil spills are all treated differently. When an oil spill occurs away from the shoreline, the most important task is to prevent the spreading of the slick. This is accomplished by the use of oil booms. A boom is a major piece of equipment used to contain oil spills and comes in many shapes and sizes. Every oil spill has its unique properties and therefore every boom must be custom made depending on the nature of the oil spill. These oil booms encircle the oil and contain it, otherwise, the oil will continue to spread until there is a monolayer (single layer) of oil molecules at the surface of the water, affecting marine animals over very large distances.

Once contained, the second task is to recover the oil from the ocean. There are three methods by which the oil can be removed from the ocean. Mechanical skimmers can be used that skim the oil from the surface of the water like a large vacuum cleaner. The second source of removal is the use of sorbents. These are based on the principle of like molecules being attracted to like molecules. In other words, the surface of these sorbents are lipophilic (nonpolar) so that the oil (which is also nonpolar) will adhere (stick) to them and, consequently, be removed from the ocean. The third method is manual removal by a clean-up work force using chemical surfactants (a surfactant contains polar and nonpolar components so that the nonpolar oil can be released into the polar water) to increase the formation of droplets, which helps oil-eating bacteria, fungi, and yeast have easier access to the oil.

When an oil spill occurs close to, or at the shoreline, it has the greatest effects on wildlife because this is where most marine and land life resides. Under these circumstances, there are different cleanup procedures. One procedure is the use of beach cleaners. These cleaners are chemicals used to strip the oil from the rocks and flush the oil back into the water where it can be cleaned up using the methods described above. Another procedure is the use of natural processes such as photooxidation and bioremediation. Photooxidation is the break down of compounds in the oil by energy supplied by the Sun and bioremediation is the use of oil-eating bacteria to break down or metabolize the compounds. As you can see, Nature also plays a role in the constant battle to preserve its balance against the hazards of the environment.