Environmental Impacts of Oil Spills

Instructor: Sarah Friedl

Sarah has two Master's, one in Zoology and one in GIS, a Bachelor's in Biology, and has taught college level Physical Science and Biology.

Oil is very useful to us but is harmful if it gets into the environment. In this lesson you'll learn about how oil is cleaned up after a spill and the effects spilled oil has on the environment.

Oil Spills

We use the products of oil all the time in our everyday lives. Usually, the process of getting this oil from deep below Earth's surface doesn't cause large-scale problems. But when there is an oil spill, it can be disastrous. If you think back to just a few years ago you'll recall the Deepwater Horizon oil spill, which was the largest marine oil spill in U.S. history. Starting April 20, 2010 and lasting 87 days, over 130 million gallons of oil leaked out into the Gulf of Mexico, affecting marine life, coastal economies, and even presenting dangers to human health.

Oil Spill Clean Up

Cleaning up the oil from a spill can be a daunting task, and there are many ways to approach this problem depending on the size and location of the spill, the type of oil, and even the weather.

A skimmer skimming oil off the surface of the water after a spill
skimmer removing oil after a spill

Skimmers are boats that can skim oil off the surface of the water. Burning oil at the surface is another common method of removing oil from the water. Physical barriers such as booms may be used to keep the oil from spreading further out into the water. Oil may be absorbed by sorbents (think of the sorbents as ab-sorbing the oil!). Sorbents can be natural such as hay, straw, sawdust, sand, and clay, or they may be synthetic (man-made) products that are similar to plastic.

A boom may be deployed in the water to help prevent the spread of spilled oil.
a boom preventing oil from spreading after a spill

Eventually, though it may take a long time, the oil will break down or biodegrade. This process can be sped up with dispersants, which are chemicals that break the oil down into smaller particles. Surfactants in the dispersants help the oil mix more easily with the water. Bacteria in the water can then help break these droplets down even more, which can prevent a large oil slick from spreading. Evaporation also plays a role, helping to remove these smaller particles of oil from the water.

A plane deploys dispersants to help break up oil after a spill
spraying dispersants over a spill area

But many people have concerns about dispersants. Dispersants may enter the food chain and can potentially harm wildlife. Dispersants also make oil more accessible to wildlife because the droplets are smaller. Dispersants also don't make the oil magically disappear, and scientists are continuing to research the long-term effects of dispersants, which are not yet fully understood.

Effects on the Environment

No matter their size, oil spills can have long-lasting effects on the environment. Through the use of the clean-up methods just mentioned, oil may look like it is gone but in fact it can persist in the environment for decades. For example, oil can sink down through the sand on beaches into sediments, and can work its way down into the muddy bottoms of marshes and tidal flats.

Tarballs come from oil spills but also from natural seeps
oil tarball

You may have also heard of tarballs, or globby pieces of oil that are left behind after a spill. Of note, tarballs can also be produced from places where oil naturally comes out of the ground, called natural seeps. After a spill, oil spreads along the surface of the water as a slick. Some of this oil will naturally evaporate. But the heavier stuff will be weathered through different processes, and as it gets mixed with water it turns into those sticky, gooey blobs that don't look like what we started with at all. Tarballs can travel hundreds of miles and last in the environment for a very long time.

Effects on Marine Life

Oil can have harmful effects on marine life development and growth (both plants and animals). Animals at the surface of the water, such as otters and sea birds, are at a greater risk of being affected because oil floats. Oil that gets on the feathers of birds can prevent them from flying, swimming, and diving, which is how many find food.

A bird is covered in oil after a spill
bird covered in oil after a spill

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