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Oil spill

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"Oil Slick" redirects here. For the Transformers character, see Oil Slick (Transformers).
A beach after an oil spill
Oil Slick from the Montara oil spill in the Timor Sea, September, 2009.
For the 2010 Oil Spill in the Gulf of Mexico, see Deepwater Horizon 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.[1] Oil also enters the marine environment from natural oil seeps.[2] 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.

Environmental effects

Surf Scoter covered in oil as a result of the 2007 San Francisco Bay oil spill.

The oil penetrates 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 to forage and escape from predators. As they attempt to preen, birds typically ingest oil that covers their feathers, causing kidney damage, altered liver function, and digestive tract irritation. This and the limited foraging ability quickly causes dehydration and metabolic imbalances. Hormonal balance alteration including changes in luteinizing protein can also result in some birds exposed to petroleum.[3] Most birds affected by an oil spill die unless there is human intervention.[4][5] 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 digestions. Because oil floats on top of water, less sunlight penetrates into the water, limiting the photosynthesis of marine plants and phytoplankton. This, as well as decreasing the fauna populations, affects the food chain in the ecosystem.

Cleanup and Recovery

Clean-up efforts after the Exxon Valdez oil spill.
A US Navy oil spill response team drills with a "Harbour Buster high-speed oil containment system".

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.

Recovering the oil is difficult and depends upon many factors, including the type of oil spilled, the temperature of the water (in warmer waters, some oil may evaporate), and the types of shorelines and beaches involved.[6] Methods for cleaning up include:

  • Bioremediation: use of microorganisms[7] or biological agents[8] to break down or remove oil.
  • Bioremediation Accelerator: Oleophilic, hydrophobic chemical, containing no bacteria, which chemically and physically bonds to both soluble and insoluble hydrocarbons. The bioremedation accelerator acts as a herding agent in water and on the surface, floating molecules to the surface of the water, including solubles such as phenols and BTEX, forming gel-like agglomerations. Non-detectable levels of hydrocarbons can be obtained in produced water and manageable water columns. By over spraying sheen with bio remediation accelerator, sheen is eliminated within minutes. Whether applied on land or on water, the nutrient-rich emulsion, creates a bloom of local, indigenous, pre-existing, hydrocarbon-consuming bacteria. Those specific bacteria break down the hydrocarbons into water and carbon dioxide, with EPA tests showing 98% of alkanes biodegraded in 28 days; and aromatics being biodegraded 200 times faster than in nature[9].
  • Controlled burning can effectively reduce the amount of oil in water, if done properly.[10] But it can only be done in low wind,[citation needed] and can cause air pollution.[11]
Oil slicks on Lake Maracaibo.
Volunteers cleaning up the aftermath of the Prestige oil spill.
  • Dispersants act as detergents, clustering around oil globules and allowing them to be carried away in the water.[12] This improves the surface aesthetically, and mobilizes 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 dispersant are toxic to corals.[13]
  • Watch and wait: in some cases, natural attenuation 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
  • Solidifying.[citation needed]

Equipment used includes:[10]

  • Booms: large floating barriers that round up oil and lift the oil off the water
  • Skimmers: skim the oil
  • Sorbents: large absorbents 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
  • Certain Products such as Nokomis 3

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.

Environmental Sensitivity Index (ESI) Mapping

NOAA's Office of Response and Restoration

Environmental Sensitivity Index (ESI) maps are used to identify sensitive shoreline resources prior to an oil spill event in order to set priorities for protection and plan cleanup strategies.[14][15] By planning spill response ahead of time, the impact on the environment can be minimized or prevented. Environmental sensitivity index maps are basically made up of information within the following three categories: shoreline type, and biological and human-use resources.[16]

Shoreline Type

Shoreline type is classified by rank depending on how easy the oil would be to cleanup, how long the oil would persist, and how sensitive the shoreline is.[17] The floating oil slicks put the shoreline at particular risk when they eventually come ashore, covering the substrate with oil. The differing substrates between shoreline types vary in their response to oiling, and influence the type of cleanup that will be required to effectively decontaminate the shoreline. In 1995, the National Oceanic and Atmospheric Administration extended ESI maps to lakes, rivers, and estuary shoreline types.[16] The exposure the shoreline has to wave energy and tides, substrate type, and slope of the shoreline are also taken into account – in addition to biological productivity and sensitivity. The productivity of the shoreline habitat is also taken into account when determining ESI ranking.[18] Mangroves and marshes tend to have higher ESI rankings due to the potentially long-lasting and damaging effects of both the oil contamination and cleanup actions. Impermeable and exposed surfaces with high wave action are ranked lower due to the reflecting waves keeping oil from coming onshore, and the speed at which natural processes will remove the oil.

Biological Resources

Habitats of plants and animals that may be at risk from oil spills are referred to as “elements” and are divided by functional group. Further classification divides each element into species groups with similar life histories and behaviors relative to their vulnerability to oil spills. There are eight element groups: Birds, Reptiles and Amphibians, Fish, Invertebrates, Habitats and Plants, Wetlands, and Marine Mammals and Terrestrial Mammals. Element groups are further divided into sub-groups, for example, the ‘marine mammals’ element group is divided into dolphins, manatees, pinnipeds (seals, sea lions & walruses), polar bears, sea otters and whales.[16][18] Issues taken into consideration when ranking biological resources include the observance of a large number of individuals in a small area, whether special life stages occur ashore (nesting or molting), and whether there are species present that are threatened, endangered or rare.[19]

Human-Use Resources

Human use resources are divided into four major classifications; archaeological importance or cultural resource site, high-use recreational areas or shoreline access points, important protected management areas, or resource origins.[16][19] Some examples include airports, diving sites, popular beach sites, marinas, natural reserves or marine sanctuaries.

Estimating the volume of a spill

File:Bottsand.jpg
Bottsand class oil recovery ship of the German Navy.

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.[20]


Film thickness Quantity spread
Appearance in mm nm gal/sq mi L/ha
Barely visible 0.0000015 0.0000380 38 25 0.370
Silvery sheen 0.0000030 0.0000760 76 50 0.730
First trace of color 0.0000060 0.0001500 150 100 1.500
Bright bands of color 0.0000120 0.0003000 300 200 2.900
Colors begin to dull 0.0000400 0.0010000 1000 666 9.700
Colors are much darker 0.0000800 0.0020000 2000 1332 19.500

Oil spill model systems are used by industry and government to assist in planning and emergency decision making. Of critical importance for the skill of the oil spill model prediction is the adequate description of the wind and current fields. There is a worldwide oil spill modelling (WOSM) program.[21]

Largest oil spills

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 *Tons of crude oil Reference
Gulf War oil spill Persian Gulf January 21, 1991 1,360,000–1,500,000 (9,968,800-10,995,000 barrels) [22][23]
Ixtoc I oil well Gulf of Mexico June 3, 1979–March 23, 1980 454,000–480,000 (3,328,000–3,518,000 barrels) [24]
Atlantic Empress / Aegean Captain Trinidad and Tobago July 19, 1979 287,000 (2,104,000 barrels) [25][26]
Fergana Valley Uzbekistan March 2, 1992 285,000 (2,089,000 barrels) [23]
Nowruz oil field Persian Gulf February 1983 260,000 (1,906,000 barrels) [27]
ABT Summer 700 nautical miles (1,300 km) off Angola 1991 260,000 (1,906,000 barrels) [25]
Castillo de Bellver Saldanha Bay, South Africa August 6, 1983 252,000 (1,847,000 barrels) [25]
Amoco Cadiz Brittany, France March 16, 1978 223,000 (1,635,000 barrels) [23][25]
Amoco Haven tanker disaster Mediterranean Sea near Genoa, Italy 1991 144,000 (1,056,000 barrels) [25]
Odyssey 700 nautical miles (1,300 km) off Nova Scotia, Canada 1988 132,000 (968,000 barrels) [25]
Sea Star Gulf of Oman December 19, 1972 115,000 (843,000 barrels) [23][25]
Torrey Canyon Scilly Isles, UK March 18, 1967 80,000–119,000 (586,000–872,000 barrels) [23][25]
Irenes Serenade Navarino Bay, Greece 1980 100,000 (733,000 barrels) [25]
Urquiola A Coruña, Spain May 12, 1976 100,000 (733,000 barrels) [25]
Deepwater Horizon Gulf of Mexico April 20, 2010 TBD [25]

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

  • The BP/Deepwater Horizon oil spill flow rate has not been reliably established. Based on estimates of industry experts,[28][29][30][31][32][33][34][35][36] it has reached 170,000 barrels of oil leaked by May 24, 2010 but the amount of oil spilling into the Gulf of Mexico may be 20 times the size of BP's claims (2.4 million barrels spilled as of May 24, 2010), according to an exclusive analysis conducted for NPR.[37]

See also

References

  1. ^ "Hindsight and Foresight, 20 Years After the Exxon Valdez Spill". NOAA. 2010-03-16. Retrieved 2010-04-30. {{cite web}}: |first= missing |last= (help)
  2. ^ http://seeps.geol.ucsb.edu/
  3. ^ C. Michael Hogan (2008), "Magellanic Penguin", GlobalTwitcher.com, ed. N. Stromberg.
  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. ^ http://www.commondreams.org/views04/0322-04.htm Lingering Lessons of the Exxon Valdez Oil Spill
  7. ^ http://www.enviroliteracy.org/article.php/540.html
  8. ^ http://www.epa.gov/oilspill/ncp/bagents.htm
  9. ^ http://www.epa.gov/emergencies/content/ncp/products/s200.htm
  10. ^ a b "Emergency Response: Responding to Oil Spills". Office of Response and Restoration. National Oceanic and Atmospheric Administration. 2007-06-20.
  11. ^ Oil Spills
  12. ^ "Detergent and Oil Spills". NEWTON BBS. 2002-10-12. {{cite web}}: Unknown parameter |access date= ignored (|access-date= suggested) (help)
  13. ^ Barry, Carolyn (2007). Slick Death: Oil-spill treatment kills coral, Science News vol. 172, p. 67.
  14. ^ http://response.restoration.noaa.gov/resource_resourcetopic.php?RECORD_KEY(resourcetopics)=resourcetopic_id&resourcetopic_id(resourcetopics)=37
  15. ^ http://response.restoration.noaa.gov/
  16. ^ a b c d NOAA (2002). Environmental Sensitivity Index Guidelines, version 3.0. NOAA Technical Memorandum NOS OR&R 11. Seattle: Hazardous Response and Assessment Division, National Oceanic and Atmospheric Administration, 129p.
  17. ^ Gundlach, E.R. and M.O. Hayes (1978). Vulnerability of Coastal Environments to Oil Spill Impacts. Marine Technology Society. 12 (4): 18-27.
  18. ^ a b NOAA (2008). Introduction to Environmental Sensitivity Index maps. NOAA Technical Manual. Seattle: Hazardous Response and Assessment Division, National Oceanic and Atmospheric Administration, 56p.
  19. ^ a b IMO/IPIECA (1994). Sensitivity Mapping for Oil Spill Response. International Maritime Organization/ International Petroleum Industry Environmental Conservation Association Report Series, Volume 1. 22p.
  20. ^ Metcalf & Eddy. Wastewater Engineering, Treatment and Reuse. 4th ed. New York: McGraw-Hill, 2003. 98.
  21. ^ Anderson, E.L., E. Howlett, K. Jayko, V. Kolluru, M. Reed, and M. Spaulding. 1993. The worldwide oil spill model (WOSM): an overview. Pp. 627–646 in Proceedings of the 16th Arctic and Marine Oil Spill Program, Technical Seminar. Ottawa, Ontario: Environment Canada.
  22. ^ George Draffan. "Major Oil Spills". Endgame. Retrieved 2007-07-29.
  23. ^ a b c d e "History". The Mariner Group.
  24. ^ 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". NPG (Nature Publishing Group). Retrieved 2007-07-29.{{cite web}}: CS1 maint: multiple names: authors list (link)
  25. ^ a b c d e f g h i j k "Statistics". ITOPF. Retrieved 2007-07-29.
  26. ^ "Atlantic Empress/Aegean Captain". Cedre. 2006-04. {{cite web}}: Check date values in: |date= (help); Unknown parameter |access date= ignored (|access-date= suggested) (help)
  27. ^ "Oil Spills and Disasters". infoplease. infoplease. {{cite web}}: Unknown parameter |access date= ignored (|access-date= suggested) (help)
  28. ^ Taley, Ian (2010-04-30). "Experts: Oil May Be Leaking at Rate of 25,000 Barrels a Day in Gulf". The Wall Street Journal.
  29. ^ AMICO, CHRIS (2010-05-09). "How Much Oil Has Leaked Into the Gulf of Mexico?". PBS NewsHour. {{cite news}}: Check |url= value (help)
  30. ^ John M. Broder, Campbell Robertson and Clifford Krauss (2010-05-04). "Amount of Spill Could Escalate, Company Admits". New York Times.
  31. ^ Eric Beech (2010-05-05). "BP exec says oil leak could flow at 60,000 bpd". Reuters.
  32. ^ Emily Gertz (APRIL 29, 2010). "Gulf Oil Spill Far Worse Than Officials, BP Admit, Says Independent Analyst". Natural Resources Defense Council. Retrieved 12 May 2010. {{cite web}}: Check date values in: |date= (help)
  33. ^ CAIN BURDEAU and HOLBROOK MOHR (2010-05-01). "Expert: Surface area of Gulf oil spill has tripled". Associated Press.
  34. ^ Julie Cart (2010-05-01). "Tiny group has big impact on spill estimates". Los Angeles Times.
  35. ^ Taley, Ian (2010-04-30). "Interior Secretary Salazar: US Gulf Oil Spill May Be Worse Than Valdez". DOW JONES NEWSWIRES.
  36. ^ John Amos (2010-05-09). "BP / Gulf Oil Spill - How Big Is It?". SkyTruth.
  37. ^ Richard Harris (2010-05-13). "Gulf Spill Could Be Much Worse Than Believed". NPR.

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

Wikimedia Commons has media related to Oil spill.
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