Oil spill

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A beach subsequent to an oil spill
A beach subsequent to an oil spill

An oil spill is the unintentional release of a liquid petroleum hydrocarbon into the environment as a result of human activity. The term often refers to marine oil spills, where oil is released into the ocean or coastal waters. 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. 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 man-made oil pollution comes from land-based activity, but public attention and subsequent regulation has tended to focus most sharply on seagoing oil tankers [2].

Contents

Studies of the Exxon Valdez oil spill have shown that the environmental damage caused by oil spills can be greater than was previously thought. Petroleum-based hydrocarbons can negatively impact marine life at concentrations as low as one part per billion.[3]

Birds killed as a result of oil from the Exxon Valdez spill
Birds killed as a result of oil from the Exxon Valdez spill

The lighter fractions of oil, such as benzene and toluene, are highly toxic, but are also volatile and evaporate quickly.[citation needed] Heavier components of crude oil, such as polycyclic aromatic hydrocarbons (PAHs) appear to cause the most damage; while 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 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. The limited foraging ability coupled with the ingestion of the oil quickly causes dehydration and metabolic imbalances. Most birds affected by an oil spill will die without human intervention.[4][5]

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

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

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

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 • 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
Natural environment

By observing the thickness of the film 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 known, the total volume of the oil can be calculated from this information.[12]

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

This section needs additional citations for verification.
Please help improve this article by adding reliable references. Unsourced material may be challenged and removed.
This section has been tagged since December 2007.

A sheen is usually dispersed (but not cleaned up) with detergents which makes oil settle to the bottom. Cleaning up oils that are denser than water could prove difficult as they settle to the bottom making the seabed toxic; PCBs are an example of such a pollutant.

Some of the equipment used in cleaning up include[13]:

  • Booms: floating barriers that rounds up oil
  • 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

Some of the methods used include:

  • Bioremediation: use of microorganisms [2] or biological agents[3] to break down or remove oil
  • Burning: Controlled burning if conducted properly can effectively reduce the amount of oil in water.[13] However, it can be done only when it is not windy[citation needed], and could cause air pollution.[14]
  • Dispersants: Dispersants act as detergents, clustering around oil globules and allowing it to be carried away in the water.[15] While this improves the surface aesthetically, it only serves to mobilise the oil. This may be beneficial since smaller oil droplets, scattered with currents, may cause less harm and may be easier to degrade. However, the dispersed oil droplets increases infiltration into deeper water and can lethally contaminate coral. Moreover, recent research indicates that some dispersants are toxic to corals.[16]
  • Watch and Wait: In some cases, allowing nautral attentuation of oil may be the most appropriate choice 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
  • Solidifying[citation needed]

  • Secondary Containment - methods to prevent releases of oil or hydrocarbons into environment.
  • SPCC - Oil Spill Prevention Containment and Countermeasures program by US EPA.
  • Double hulling - build double hull vessels and rebuild single hull vessels into double hull. A double hull reduces the risk and severity of a spill in case of a collision or grounding.

  1. ^ http://seeps.geol.ucsb.edu/
  2. ^ http://www.planetarios.com/handbook-contamination/petroleumoilspill.html
  3. ^ Long-Term Ecosystem Response to the Exxon Valdez Oil Spill, Science, v.302, 19 December 2003, pp.2082-2085
  4. ^ 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
  5. ^ Untold Seabird Mortality due to Marine Oil Pollution, Elements Online Environmental Magazine.
  6. ^ George Draffan. Major Oil Spills (HTML) (English). Endgame. Retrieved on 2007-07-29.
  7. ^ a b c d e History (HTML) (English). The Mariner Group.
  8. ^ 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) (English). NPG (Nature Publishing Group). Retrieved on 2007-07-29.
  9. ^ a b c d e f g h i j Statistics (HTML) (English). ITOPF. Retrieved on 2007-07-29.
  10. ^ Atlantic Empress/Aegean Captain (HTML) (English). Cedre (2006-04). Retrieved on 2007-07-29.
  11. ^ Oil Spills and Disasters (HTML) (English). infoplease. infoplease. Retrieved on 2007-07-29.
  12. ^ Metcalf & Eddy. Wastewater Engineering, Treatment and Reuse. 4th ed. New York: McGraw-Hill, 2003. 98.
  13. ^ a b http://response.restoration.noaa.gov/topic_subtopic_entry.php?RECORD_KEY(entry_subtopic_topic)=entry_id,subtopic_id,topic_id&entry_id(entry_subtopic_topic)=184&subtopic_id(entry_subtopic_topic)=8&topic_id(entry_subtopic_topic)=1
  14. ^ [1]
  15. ^ Detergent and Oil Spills (HTML) (English). NEWTON BBS (2002-10-12). Retrieved on 2007-07-29.
  16. ^ Barry, Carolyn (2007). Slick Death: Oil-spill treatment kills coral, Science News vol. 172, p. 67.

  • 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

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