Intro

Explore one of the biggest ethical issues facing today’s environment (and its animals!) as you make a mock oil spill and try your best to clean it up!

Volunteers: 2-4

1: to discuss the procedure/background science.
1-3: to hands-on assist with the procedure.

Equipment

• Large plastic salad bowls/wash basins
• Small plastic bowls
• Paper bags (for clean-up kits)
• Clean-up kits (sponges, paper towels, strings, plastic spoons, straws, etc.)
• *Gloves (optional, all materials are safe)
• *Hand sanitizer (optional, to clean hands afterward)
• **Garbage bags, paper towels/surface cleaner (or other safe disposal method)
• **Access to a sink

Materials

• Water (room temperature)
• Oil (vegetable oil works well, but any type should be fine)
• Cocoa powder
• Feathers (craft feathers are fine, the bigger the better)

Procedure

1. Create several mock oil spills by filling large plastic bowls/basins with water and then layering on top some vegetable oil mixed with cocoa powder (for the oil colour and consistency)(you can have the students create these mock oil spills if you’d like)
2. Have students dip craft feathers into the oily water, explain how this replicates what would happen to an animal’s feathers/fur, what happens to it?
3. Tell students they are environmentalists in charge of clean up and provide them with a “clean up kit” (of various materials, as above, plus whatever else you can think of)
4. Allow students to try to (a) clean the oil off of the feather and (b) remove the oil from the water (provide a small plastic bowl to transfer the oil to), is it easy?

Background Science

Learning Question: What are oil spills? What consequences do they have? Are the easy to clean up?

An oil spill is defined as the release of liquid petroleum hydrocarbons into the environment due to human activity. Oil spills are a form of pollution. The term is usually used with marine oil spills, where oil is released into the ocean or coastal waters, but oil spills may occur on land as well and be just as much of a problem.

Oil spills may be due to releases of crude oil (unrefined petroleum products) from tankers, offshore platforms, drilling rigs and wells as well as releases of refined petroleum products (gasoline and diesel), heavier fuels used by large ships and any oily refuse or waste oil from industry.

Oil spills have disastrous consequences for society; economically, socially, and environmentally. Clean-up and recovery is difficult and depends on many factors including the type of oil, the amount of oil, the temperature of the water and the types of water bodies, shorelines, and beaches affected. Spills can take weeks, months or even years to completely clean up.

Typically when we talk about oil spills, we’re referring to the distribution of crude oils into marine environments. Crude oils are made of hydrocarbons (hydrogen-carbon molecular chains) that formed via the compression under the earth of decomposed (dead) organic material (dinosaurs and other living things!) that existed millions of years ago. Crude is a synonym for unprocessed, meaning crude oil has been extracted directly from the earth in underground reservoirs and has not undergone any refinement.

The way that these oils then behave in the environment and the effect they have on marine life depends largely on the chemical and physical properties of the hydrocarbon molecules that make them up. However, all oils are chemically non-polar and are what is called hydrophobic, this means that they do not mix with water. Another factor to consider is density or the amount of oil packed into a given area. The hydrocarbons that make up all oils tend to be less dense than water molecules meaning they will always float to the surface. At the surface, these crude oils form an oil slick, a layer of oil that can’t dissolve in the water it rests on.

Once oil reaches the surface, two other processes begin to take place. Firstly, fluids like to spread out. The same thing happens to oil at the water’s surface. The degree to which a particular compound can spread out is called viscosity. You can think of viscosity as thickness. Highly viscous oils will spread out slowly and less so whereas low viscosity oils will spread out rapidly and much more so. In addition to spreading, oil at the surface of water can begin to evaporate (turn from a liquid to a gas). Volatility is the term chemists use to describe the ability of a compound to turn from a liquid to a gas, which is what happens to some of the oil in surface slicks. Unfortunately, evaporation creates another issue. When the molecules in liquid oil become gaseous they then act as air pollutants above the ocean’s surface. This is a health hazard not only to humans when coastal winds carry these air toxins to shore but also for other air-breathing marine mammals like dolphins, turtles, and whales who come up to breathe air above the water.

Only so much of the oil in a spill can evaporate or spread out. What happens to the rest of it? To answer this question scientists analyze the environmental persistence of various crude oil/refined oil/petroleum compounds, or the degree to which they remain in the environment without being broken down by natural means.

Some of the oil molecules will combine with organic material nearby and become dense enough to sink below the surface. As these compounds sink deeper and deeper into the ocean they become more persistent. All water also contains microbes, microscopic organisms that will take in oil molecules (eat them), metabolize them and spit them back out as less harmful substances through a process called biodegradation. However, microbes need a steady oxygen supply to do this work. There is little oxygen present at the bottom of the ocean so if these oil molecules travel far enough down they become extremely persistent and form tar balls or black lumps of solidified crude oil. These tar balls often wash up on shore posing health threats to humans and other wildlife through direct exposure to toxins. This is the fate of roughly 10-30% of the oil dispersed in a spill.

Oil that is not cleaned up will often penetrate the structure of feathers and plumage on birds and the fur on mammals. This reduces the insulating ability of these feathers and fur layers, making the animals much more vulnerable to temperature fluctuations. In particular, oil coverage on feathers also structurally destroys their ability to lend buoyancy (the abilities to float and fly) to a bird. The added weight of the oil on their feathers also increases the difficulty of floating and flying for a bird.

Oil that does not undergo the processes discussed above must be cleaned up by humans. There are lots of different clean-up methods employed depending on what the situation calls for but these efforts are ineffective, time-consuming and expensive.

In this activity students will use various materials to try and remove an oil slick layer from the top of a water basin. They will come to find that none of the materials they have work very well and that it takes a very long time to make any progress.

Students will also get the chance to dip a craft feather (imitating a real bird’s feather) into the oil slick in order to see how the feather’s structure is destroyed. They may then place this feather in water and notice how it is less effective at floating.