Oil spill

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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.[1]

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.[2]

Contents

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.[3]
  • 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.[4] 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.[5]
  • 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 • HerbicidePesticide •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.[6]

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 [7][8]
Ixtoc I oil well Gulf of Mexico June 3, 1979 - March 23, 1980 454,000 - 480,000 [9]
Atlantic Empress / Aegean Captain Trinidad and Tobago July 19, 1979 287,000 [10][11]
Fergana Valley Uzbekistan March 2, 1992 285,000 [8]
Nowruz oil field Persian Gulf February 1983 260,000 [12]
ABT Summer 700 nautical miles (1,300 km) off Angola 1991 260,000 [10]
Castillo de Bellver Saldanha Bay, South Africa August 6, 1983 252,000 [10]
Amoco Cadiz Brittany, France March 16, 1978 223,000 [10][8]
Amoco Haven tanker disaster Mediterranean Sea near Genoa, Italy 1991 144,000 [10]
Odyssey 700 nautical miles (1,300 km) off Nova Scotia, Canada 1988 132,000 [10]
Sea Star Gulf of Oman December 19, 1972 115,000 [10][8]
Torrey Canyon Scilly Isles, UK March 18, 1967 80,000 - 119,000 [10][8]
Irenes Serenade Navarino Bay, Greece 1980 100,000 [10]
Urquiola A Coruña, Spain May 12, 1976 100,000 [10]

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

See also

Notes

  1. Petroleum: Oil Spill Portable Planetariums. Retrieved March 12, 2008.
  2. Welcome to the UCSB Hydrocarbon Seeps web site UCSB Hydrocarbon Seeps Project. Retrieved March 12, 2008.
  3. Oil Program US EPA. Retrieved March 12, 2008.
  4. Detergent and Oil Spills NEWTON BBS. Retrieved March 12, 2008.
  5. Carolyn Barry, 2007, Slick Death: Oil-spill treatment kills coral, Science News 172:67. Retrieved March 12, 2008.
  6. Tchobanoglous, George, Franklin L. Burton, and H. David Stensel, Wastewater Engineering Treatment and Reuse (McGraw-Hill Series in Civil and Environmental Engineering. Boston: McGraw-Hill, 2003, ISBN 0070418780).
  7. Draffan, George. Major Oil Spills Endgame. Retrieved March 12, 2008.
  8. 8.0 8.1 8.2 8.3 8.4 History The Mariner Group. Retrieved March 12, 2008.
  9. John S. Patton, Mark W. Rigler, Paul D. Boehm & David L. Fiest, 1981, Ixtoc 1 oil spill: flaking of surface mousse in the Gulf of Mexico. NPG (Nature Publishing Group). Retrieved March 12, 2008.
  10. 10.0 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 Statistics ITOPF. Retrieved March 12, 2008.
  11. Atlantic Empress/Aegean Captain Cedre. Retrieved March 12, 2008.
  12. Oil Spills and Disasters infoplease. Retrieved March 12, 2008.

References

  • 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 March 12, 2008.

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