Oil spill

Aftermath of an oil spill.

An oil spill is the unintentional release of a liquid petroleum hydrocarbon into the environment as a result of human activity. Oil can refer to many different materials, including crude oil, refined petroleum products (such as gasoline or diesel fuel) or by-products, ships' bunkers, oily refuse, or oil mixed in waste. Most man-made oil pollution comes from land-based activity, but the term often refers to the release of oil into the ocean or coastal waters. Public attention and subsequent regulation has tended to focus mainly on seagoing oil tankers.

Petroleum-based hydrocarbons can negatively impact marine life and seabirds even at low concentrations. Oil that is denser than water settles on and penetrates the seabed, and it may take months or even years to clean up. Some methods to clean up an oil spill include the use of bioremediation, dispersants, dredging, and skimming.

It should be noted that oil is also released into the environment from natural geologic seeps on the sea floor.

Environmental effects

Oiled birds

The lighter fractions of oil, such as benzene and toluene, are highly toxic, but they are also volatile and evaporate quickly. Heavier components of crude oil, such as polynuclear aromatic hydrocarbons (PAHs) appear to cause the most damage. Although they are less toxic than the lighter volatiles, they persist in the environment much longer.

A heavy oil spill can also blanket estuaries and shoreline ecosystems, such as salt marshes and tidal pools, preventing gas exchange and blocking light. The oil can mix deeply into pebble, shingle, or sandy beaches, where it may remain for months or even years.

Seabirds are severely affected by spills, as the oil penetrates and opens up the structure of their plumage, reducing the insulating ability of their feathers, making the birds more vulnerable to temperature fluctuations and much less buoyant in the water. The oiled feathers also impairs the birds' ability to fly, making it difficult or impossible to forage and escape from predators. As they attempt to preen, birds typically ingest oil that coats their feathers, causing kidney damage, altered liver function, and digestive tract irritation. The limited foraging ability coupled with the ingestion of oil quickly leads to dehydration and metabolic imbalances. Most birds affected by an oil spill die in the absence of supportive human intervention.

Marine mammals exposed to oil spills are affected in many of the same ways as seabirds. Oil coats the fur of sea otters and seals, reducing the natural insulation ability of their fur, leading to body temperature fluctuations and hypothermia. Ingestion of the oil also causes dehydration, and impaired digestion.

Cleaning up an oil spill

Some equipment used for cleanup:

• Absorbent Boom, Sausage
• Containment Boom (except for gasoline where confinement can cause dangerous levels of fume buildup)
• Skimmers
• Snares

Some methods used for cleanup:

• Bioremediation: use of biological agents to remove oil.
• Burning: It can be done only when it is not windy, the oil has not dispersed, and the sea is calm.
• Dispersants: Dispersants act as detergents, clustering around oil globules and allowing it to be carried away in the water. While this makes the surface look pretty, it only spreads the oil around. This could be a benefit since smaller oil droplets, scattered with currents, may cause less harm and may be easier to degrade. However, the dispersed oil droplets readily sink and can lethally contaminate coral. Moreover, recent research indicates that dispersants themselves are toxic to corals.
• Do nothing: Some have advocated doing nothing and letting the oil evaporate or break down on its own, rather than making matters worse by attempting to clean up. As noted above, cleanup by detergents pollutes the seabed. Also, shoreline cleanup can further disturb the ecology by bleaching all life from the area.
• Dredging: This method is used for oils dispersed with detergents and other oils denser than water.
• Skimming: This approach can't be used if the sea is rough.
• Solidifying the material.

Spill Prevention

• Secondary Containment: This includes methods to prevent releases of oil or hydrocarbons into the environment.
• SPCC: Oil Spill Prevention Containment and Countermeasures program by U.S. Environmental Protection Agency (EPA).
• Double hulling: Building and using double hull vessels and converting single hull vessels into double hull. A double hull reduces the risk and severity of a spill in case of a collision or grounding.

Estimating the volume of a spill

Pollution

Air pollution

Acid rain • Air Pollution Index • Air Quality Index • Atmospheric dispersion modeling • Chlorofluorocarbon • Global dimming • Global warming • Haze • Indoor air quality • Ozone depletion • Particulate • Smog • Roadway air dispersion

Water pollution

Eutrophication • Hypoxia • Marine pollution • Ocean acidification • Oil spill • Ship pollution • Surface runoff • Thermal pollution • Wastewater • Waterborne diseases • Water quality • Water stagnation

Soil contamination

Bioremediation • Herbicide • Pesticide •Soil Guideline Values (SGVs)

Radioactive contamination

Actinides in the environment • Environmental radioactivity • Fission product • Nuclear fallout • Plutonium in the environment • Radiation poisoning • radium in the environment • Uranium in the environment

Other types of pollution

Invasive species • Light pollution • Noise pollution • Radio spectrum pollution • Visual pollution

Government acts

Clean Air Act • Clean Water Act • Kyoto Protocol • Water Pollution Control Act • Environmental Protection Act 1990

Major organizations

DEFRA • Environmental Protection Agency • Global Atmosphere Watch • Greenpeace • National Ambient Air Quality Standards

Related topics

Natural environment

For an oil spill on water, one can calculate the total volume of oil by measuring the surface area of the spill and the average thickness of the film.

	Film Thickness		Quantity Spread
Appearance	in	mm	gal/sq mi	L/ha
Barely visible	0.0000015	0.0000381	25	0.365
Silvery sheen	0.0000030	0.0000762	50	0.731
First trace of color	0.0000060	0.0001524	100	1.461
Bright bands of color	0.0000120	0.0003048	200	2.922
Colors begin to dull	0.0000400	0.0010160	666	9.731
Colors are much darker	0.0000800	0.0020320	1332	19.463

Largest oil spills

Volunteers cleaning up the aftermath of the Prestige oil spill.

Oil Spills of over 100,000 metric tons or 30 million US gallons, ordered by Tonnes^[a]

Spill / Tanker	Location	Date	*Tonnes of crude oil	Reference
Gulf War oil spill	Persian Gulf	January 23, 1991	136,000 - 1,500,000
Ixtoc I oil well	Gulf of Mexico	June 3, 1979 - March 23, 1980	454,000 - 480,000
Atlantic Empress / Aegean Captain	Trinidad and Tobago	July 19, 1979	287,000
Fergana Valley	Uzbekistan	March 2, 1992	285,000
Nowruz oil field	Persian Gulf	February 1983	260,000
ABT Summer	700 nautical miles (1,300 km) off Angola	1991	260,000
Castillo de Bellver	Saldanha Bay, South Africa	August 6, 1983	252,000
Amoco Cadiz	Brittany, France	March 16, 1978	223,000
Amoco Haven tanker disaster	Mediterranean Sea near Genoa, Italy	1991	144,000
Odyssey	700 nautical miles (1,300 km) off Nova Scotia, Canada	1988	132,000
Sea Star	Gulf of Oman	December 19, 1972	115,000
Torrey Canyon	Scilly Isles, UK	March 18, 1967	80,000 - 119,000
Irenes Serenade	Navarino Bay, Greece	1980	100,000
Urquiola	A Coruña, Spain	May 12, 1976	100,000

One metric ton of crude oil is roughly equal to 308 US gallons, or 7.33 barrels.

See also

• Hydrocarbon
• Oil
• Petroleum
• Pollution

References

ISBN links support NWE through referral fees

• Fingas, Mervin F., and Jennifer Charles. 2001. The Basics of Oil Spill Cleanup. Boca Raton, Fla: Lewis Publishers. ISBN 1566705371
• Nelson-Smith, A. 1973. Oil Pollution and Marine Ecology. London, UK: Elek Scientific. ISBN 0236154117
• Park, Ken (ed.). 2004. The World Almanac and Book of Facts. New York, NY: World Almanac. ISBN 0886879116
• Reis, John C. 1996. Environmental Control in Petroleum Engineering. Houston, TX: Gulf Publ. ISBN 0884152731
• Tchobanoglous, George, Franklin L. Burton, and H. David Stensel. 2003. Wastewater Engineering Treatment and Reuse. McGraw-Hill Series in Civil and Environmental Engineering. Boston: McGraw-Hill. ISBN 0070418780
• Oil Spill Case Histories 1967-1991 NOAA/Hazardous Materials and Response Division. Retrieved March 12, 2008.

External links

All links retrieved November 17, 2022.

• www.cedre.fr Centre of Documentation, Research and Experimentation on Accidental Water Pollution
• International Tanker Owners Pollution Federation

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