Wednesday, November 2, 2011

Oil spill facts

An oil spill is an unintentional release of crude oil or refined oil products into the environment. Oil spill is a form of pollution. The term often refers to marine oil spills, where oil is released into the ocean or coastal waters.

Main causes of oil spills are deliberate sabotages (wars) and oil drilling accidents. Major oil spill can also occur when transporting oil with huge tankers or tank-trucks. Minor causes of oil spills are boat fuel spills, road motor oil leakage and deliberate dumping of motor oil or other oil products into the environment. Not all spills are consequences of human activity: oil spills can also be caused by tectonic events causing oil escape, especially in the ocean.

Oil spills can be categorized into two main categories: spills on land and spills on sea. Both can result in multiple types of pollution: water pollution, soil pollution and air pollution. A common thing for all mentioned types of pollution is huge impact on living organisms in surrounding area. 

Land oil spills are mainly localized events and pollution usually happens only near the spill site. Main long-term pollution effect from land oil spills is soil pollution which can also lead to underground water contamination. Land oil spill can extend if the spill is located near surface or underground water flows and consequential pollution is in this case much harder to control.

US planes over Kuwaiti oil fires.
 Sea oil spills (or marine oil spills) can contaminate water and oil miles away from main spill cause. This makes marine oil spills hard to control and clean because they are usually spread over vast areas. Marine oil spill may contaminate coasts and coastal soil areas if spill is not stopped offshore and then it is much more difficult to clean contaminated soil.

Offshore (sea or marine) oil spills are much easier to clean because there are special boats equipped just for this task and because of the fact that oil floats on water. Main task is to surround polluted area with oil barriers and then collect floating oil with special boats. If a marine oil spill cannot be controlled with barriers then special chemicals can be sprayed over floating oil for faster oil disintegration.

Oil spills can be controlled by chemical dispersion, combustion, mechanical containment, and/or adsorption. Spills may take weeks, months or even years to clean up.

The largest marine oil spill is Gulf war oil spill (1991) with released approximately 800,000 tons of oil. Iraqi forces opened valves at the Sea Island oil terminal and dumped oil from several tankers into the Persian Gulf.

The second largest (and largest unintentional) marine oil spill in history is the Deepwater Horizon accident in the Gulf of Mexico. This accident in year 2010 released about 570,000 tons of crude oil into sea. Because this accident was very near to the US coast huge media coverage caused great popularity of “oil safety discussions”. This accident also triggered new safety regulations in oil drilling processes.

Definitely the largest oil spill in history is Kuwaiti oil fires and oil lakes. Kuwaiti oil fires and oil lakes were caused by retreating Iraqi army as part of a scorched earth policy while retreating from Kuwait in 1991 after invading the country but being driven out by Coalition military force. The oil fires caused a dramatic decrease in air quality, causing respiratory problems for many Kuwaitis. This oil spill is classified as land oil spill and the released quantity of oil is more than 300 times the released volume in Deepwater Horizon spill in the Gulf of Mexico (around 160,000,000 tons in Kuwait vs. approximately 570,000 tons in the Gulf of Mexico).

Consequences of Exxon Valdez oil spill
The largest unintentional land oil spill is the Lakeview Gusher accident. Lakeview Gusher Number One was an out-of-control pressurized oil well in the Midway-Sunset Oil Field in Kern County, California, lasting 18 months and releasing about 1,200,000 of crude oil.

The largest tanker oil spill is the Exxon Valdez oil spill with about 40,000 tons of spilled crude oil and has occurred in Prince William Sound, Alaska, on March 24, 1989. It is considered to be one of the most devastating human-caused environmental disasters.

One gallon of used motor oil can contaminate 1 million gallons of fresh water - a year's supply of water for 50 people. The United States generates a total of 1.3 billion gallons of waste oil each year of which 800 million gallons are recycled and 500 million are disposed of improperly.

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