Oil spill
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Oil_spill".

A beach after an oil spill
A beach after an oil spill

An oil spill is the release of a liquid petroleum hydrocarbon into the environment due to human activity, and is a form of pollution. The term often refers to marine oil spills, where oil is released into the ocean or coastal waters. The oil may be a variety of 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. Spills take months or even years to clean up.

Oil is also released into the environment from natural geologic seeps on the sea floor. [1] Most human-made oil pollution comes from land-based activity, but public attention and regulation has tended to focus most sharply on seagoing oil tankers. [2]

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Environmental effects

The oil penetrates and opens up the structure of the plumage of birds, reducing its insulating ability, and so making the birds more vulnerable to temperature fluctuations and much less buoyant in the water. It also impairs birds' flight abilities, 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. This and the limited foraging ability quickly causes dehydration and metabolic imbalances. Most birds affected by an oil spill die unless there is human intervention.[3][4]

Marine mammals exposed to oil spills are affected in similar ways as seabirds. Oil coats the fur of Sea otters and seals, reducing its insulation abilities and leading to body temperature fluctuations and hypothermia. Ingestion of the oil causes dehydration and impaired digestion.

Largest oil spills

Volunteers cleaning up the aftermath of the Prestige oil spill
Volunteers cleaning up the aftermath of the Prestige oil spill
Bottsand class oil recovery ship of the German Navy
Bottsand class oil recovery ship of the German Navy
Main article: List of oil spills
Oil Spills of over 100,000 tonnes 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 [5][6]
Ixtoc I oil well Gulf of Mexico June 3, 1979- March 23, 1980 454,000 - 480,000 [7]
Atlantic Empress / Aegean Captain Trinidad and Tobago July 19, 1979 287,000 [8] [9]
Fergana Valley Uzbekistan March 2, 1992 285,000 [6]
Nowruz oil field Persian Gulf February 1983 260,000 [10]
ABT Summer 700 nautical miles (1,300 km) off Angola 1991 260,000 [8]
Castillo de Bellver Saldanha Bay, South Africa August 6, 1983 252,000 [8]
Amoco Cadiz Brittany, France March 16, 1978 223,000 [8] [6]
Amoco Haven tanker disaster Mediterranean Sea near Genoa, Italy 1991 144,000 [8]
Odyssey 700 nautical miles (1,300 km) off Nova Scotia, Canada 1988 132,000 [8]
Sea Star Gulf of Oman December 19, 1972 115,000 [8] [6]
Torrey Canyon Scilly Isles, UK March 18, 1967 80,000 - 119,000 [8] [6]
Irenes Serenade Navarino Bay, Greece 1980 100,000 [8]
Urquiola A Coruña, Spain May 12, 1976 100,000 [8]

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

Estimating the volume of a spill

Pollution
v • d • e
Air pollution
Acid rain • Air Quality Index • Atmospheric dispersion modeling • Chlorofluorocarbon • Global dimming • Global warming • Haze • Indoor air quality • Ozone depletion • Particulate • Smog
Water pollution
Eutrophication • Hypoxia • Marine pollution • Marine debris • 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
Inter-government treaties
Montreal Protocol • Nitrogen Oxide Protocol • Kyoto Protocol • CLRTAP
Major organizations
DEFRA • EPA • Global Atmosphere Watch • Greenpeace • National Ambient Air Quality Standards
Related topics
Environmental Science • Natural environment

By observing the thickness of the film of oil and its appearance on the surface of the water, it is possible to estimate the quantity of oil spilled. If the surface area of the spill is also known, the total volume of the oil can be calculated.[11]

Film Thickness Quantity Spread
Appearance in mm gal/sq mi L/ha
Barely visible 0.0000015 0.0000380 25 0.370
Silvery sheen 0.0000030 0.0000760 50 0.730
First trace of color 0.0000060 0.0001500 100 1.500
Bright bands of color 0.0000120 0.0003000 200 2.900
Colors begin to dull 0.0000400 0.0010000 666 9.700
Colors are much darker 0.0000800 0.0020000 1332 19.500

Methods of cleaning

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Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (December 2007)

A sheen is usually dispersed (but not cleaned up) with detergents which makes oil settle to the bottom. Oils that are denser than water, such as Polychlorinated biphenyls (PCBs), can be more difficult to clean as they make the seabed toxic.

Clean-up efforts after Exxon Valdez oil spill.
Clean-up efforts after Exxon Valdez oil spill.

Methods for cleaning up include:

  • Bioremediation: use of microorganisms [1] or biological agents [2] to break down or remove oil
  • Controlled burning can effectively reduce the amount of oil in water, if done properly.[12] But it can only be done in low windcitation needed, and can cause air pollution.[13]
  • Dispersants act as detergents, clustering around oil globules and allowing them to be carried away in the water.[14] This improves the surface aesthetically, and mobilises the oil. Smaller oil droplets, scattered by currents, may cause less harm and may degrade more easily. But the dispersed oil droplets infiltrate into deeper water and can lethally contaminate coral. Recent research indicates that some dispersants are toxic to corals.[15]
  • Watch and wait: in some cases, nautural attentuation of oil may be most appropriate, due to the invasive nature of facilitated methods of remediation, particularly in ecologically sensitive areas.citation needed
  • Dredging: for oils dispersed with detergents and other oils denser than water.
  • Skimming: Requires calm waters
  • Solidifyingcitation needed

Equipment used includes[12]:

  • Booms: large floating barriers that round up oil and lift the oil off the water
  • Skimmers: skim the oil
  • Sorbents: large sponges that absorb oil
  • Chemical and biological agents: helps to break down the oil
  • Vacuums: remove oil from beaches and water surface
  • Shovels and other road equipments: typically used to clean up oil on beaches

Prevention

  • Secondary containment - methods to prevent releases of oil or hydrocarbons into environment.
  • Oil Spill Prevention Containment and Countermeasures (SPCC) program by the United States Environmental Protection Agency.
  • Double hulling - build double hulls into vessels, which reduces the risk and severity of a spill in case of a collision or grounding. Existing single-hull vessels can also be rebuilt to have a double hull.

See also

References

  1. ^ http://seeps.geol.ucsb.edu/
  2. ^ 16. Petroleum: Oil Spill
  3. ^ Dunnet, G., Crisp, D., Conan, G., Bourne, W. (1982) "Oil Pollution and Seabird Populations [and Discussion]" Philosophical Transactions of the Royal Society of London. B 297(1087): 413–427
  4. ^ Untold Seabird Mortality due to Marine Oil Pollution, Elements Online Environmental Magazine.
  5. ^ George Draffan. "Major Oil Spills" (HTML) (in English). Endgame. Retrieved on 2007-07-29.
  6. ^ a b c d e "History" (HTML) (in English). The Mariner Group.
  7. ^ John S. Patton, Mark W. Rigler, Paul D. Boehm & David L. Fiest (1981-03-19). "Ixtoc 1 oil spill: flaking of surface mousse in the Gulf of Mexico" (HTML) (in English). NPG (Nature Publishing Group). Retrieved on 2007-07-29.
  8. ^ a b c d e f g h i j "Statistics" (HTML) (in English). ITOPF. Retrieved on 2007-07-29.
  9. ^ "Atlantic Empress/Aegean Captain" (HTML) (in English). Cedre (2006-04). Retrieved on 2007-07-29.
  10. ^ "Oil Spills and Disasters" (HTML) (in English). infoplease. infoplease. Retrieved on 2007-07-29.
  11. ^ Metcalf & Eddy. Wastewater Engineering, Treatment and Reuse. 4th ed. New York: McGraw-Hill, 2003. 98.
  12. ^ a b "Emergency Response: Responding to Oil Spills". Office of Response and Restoration. National Oceanic and Atmospheric Administration (2007-06-20).
  13. ^ Oil Spills
  14. ^ "Detergent and Oil Spills" (HTML) (in English). NEWTON BBS (2002-10-12). Retrieved on 2007-07-29.
  15. ^ Barry, Carolyn (2007). Slick Death: Oil-spill treatment kills coral, Science News vol. 172, p. 67.

Further reading

  • The World Almanac and Book of Facts, 2004
  • Oil Spill Case Histories 1967-1991, NOAA/Hazardous Materials and Response Division, Seattle WA, 1992
  • Nelson-Smith, Oil Pollution and Marine Ecology, Elek Scientific, London, 1972; Plenum, New York, 1973

External links

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