Oil spills can happen on land or at sea, and can include leaks from ships, wells, pipelines and other carriers of oil. The scale of the spill is dependent on the amount and type of oil, and the location and climate of the leak.
On the types of oils, there are light oils and heavy oils. Light oils, such as gasoline or diesel fuel evaporate rather quickly so they do not remain in the environment for too long but are comparatively more toxic. Heavy oils on the other hand, are able to persist in the environment for a longer amount of time but are less toxic.
Oils spills at sea or in coastal areas are of particular concern because of the risk to fragile ecosystems and associated livelihoods. Because most oils float on top of water, the greatest effect of oil spills is on life that on or near the surface of the water,
Oil can harm birds and marine mammals as it can coat their fur or feathers and limit their ability to swim, float or fly. Oil is toxic to many fishes and the oil can block sunlight from reaching algae.
People who live in the immediate area of an oil spill face exposure to toxic compounds such as benzene that can become airborne. There is also a risk that people could ingest small quantities of oil if they eat shellfish or other sea creatures that have been contaminated. People in communities affected by oil spills also show a higher incidence of post-traumatic stress disorder and depression. However, by far the greatest health threats that an oil spill poses will be to the people who work to clean up the oil.
Beyond these direct environmental and health threats, there can also be significant direct economic impacts, not including the cost of cleaning up a spill. The economies of coastal communities that depend on fishing or tourism are particularly vulnerable to marine oil spills.
Despite all of the potential impacts of oil spills, the natural environment is remarkably resilient to them over the long term, as natural chemical and biological processes can break down many of the components of oil. However, some of the toxic components of oil are thought to be able to accumulate in the food chain. If so, they could be causing problems many years after the event.
Oil spills can take months or years to clean up. Various methods can be used to contain oils spills or try to minimize their effects, but in situations where remediation could create additional problems for sensitive environments it may be appropriate to let nature take its course.
Options include using living organisms such as fungi or microbes to break the oil down into safer chemicals (known as bioremediation), or using chemicals to disperse, solidify or absorb the oil. Scientists warn, however, that some of these cleaning chemicals can also harm marine life.
More mechanical approaches include skimming (collecting oil that gathers on the surface of land or water), and dredging (for dense oil that has sunk to the bottom of the sea). To facilitate skimming or dredging, large floating booms are often deployed to contain and concentrate the oil.
An expensive but effective tactic that is used at sea is to suck up water and oil with a vacuum pump and then use a centrifuge to separate the two components. The water can be returned to the sea, while the oil can be stored on a tanker.
Controlled burning can be used to stop oil leaking from oil rigs or wells, whether at land or sea, but this can cause serious air pollution. This is a trade-off because by burning the oil — and destroying its most toxic element — the overall impact on the environment may be less than if the oil was allowed to continue to leak.
Oil spills, particularly those that affect delicate coastal environments, may look worse than they really are so journalists need to take care to report the true scale of the threat. It is important to bear in mind that natural oil seeps have occurred on Earth for millions of years and that oil itself is a natural substance than can degrade over time.
Oil spills in deep ocean water are less damaging than those in which oil reaches shorelines. But while images of sea-birds smothered in oil are what many people associate with oil spills, much of the oil that leaks because of human activities does so on land.
Journalists who are focusing on environmental impacts of an oil spill should pay close attention to the methods that are used in any clean-up operations. Some detergents that can be used are themselves harmful chemicals that are strictly controlled. In some cases they may cause unnecessary additional damage to the environment.
It is also important to know what kind of oil has leaked. Some are more toxic than others. Some evaporate more quickly than others.
Companies that are responsible for oil spills, and governments that want to manage public opinion, have a vested interest in downplaying the effects of the spill. As a result, they may try to stop journalists from reporting on the situation. Reporters claimed that this happened in 2010 following the Deepwater Horizon oil spill in the Gulf of Mexico (see this article in the Columbia Journalism Review).
CASE STUDY – Nigeria’s oil-stained delta
The 2010 Deepwater Horizon oil spill was massive in scale and received considerable media coverage as a result. But in recent decades, vast quantities of oil have leaked every year into the land and wetlands where poor communities live in Nigeria’s Niger Delta. Media coverage of this story outside of Nigeria has been minimal.
The delta is the source of some of the finest quality oil in the world, and big multinational companies have been extracting it since the 1950s. Hundreds of pipelines carry all through the region, but the pipes are often leaky and the oil spills out to contaminate farmland, wells for drinking water, forests and waterways from which people seek fish and crabs to eat.
The situation has led to social conflict and numerous allegations of human rights abuses. Local people accuse the oil companies of negligence and their government of corruption and collusion. The oil companies say, however, that most of the oil spills are caused by vandalism, theft or sabotage by militants.
With hundreds of spills happening every year, this is a story that shows no signs of going away any time soon. For more details, see these articles in The Guardian, the New York Times and this video report by Aljazeera.
NOAA on 2012 Gulf Oil Spill
Wikipedia – Environmental Issues in the Niger Delta
US Environmental Protection Agency – Oil spills: emergency management
The Guardian – Oil Spills