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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.
[ 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.
[ edit ]Environmental effects
A US Navy oil spill response team drills with a "Harbour Buster high-speed oil containment system".
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
dehydrationand
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 light 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.
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.
Methods for cleaning up include:
- Bioremediation : use of microorganisms [ 6 ] or biological agents [ 7 ] 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 [ 8 ] .
- Controlled burning can effectively reduce the amount of oil in water, if done properly. [ 9 ] But it can only be done in low wind , [ citation needed ]and can cause air pollution . [ 10 ]
- Dispersants act as detergents , clustering around oil globules and allowing them to be carried away in the water. [ 11 ] 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. [ 12 ]
- 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:
[ 9 ]- 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
[ edit ]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.
[ edit ]Environmental Sensitivity Index (ESI) Mapping
[ edit ]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.
[ 13 ] [ 14 ] 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.
[ 15 ][ edit ]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 sensitivity of the shoreline.
[ 16 ] 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.
[ 15 ] 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.
[ 17 ] 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.
[ edit ]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 .
[ 15 ] [ 17 ] 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.
[ 18 ][ edit ]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.
[ 15 ] [ 18 ] Some examples include airports, diving sites, popular beach sites, marinas, natural reserves or marine sanctuaries.
[ edit ]Estimating the volume of a spill
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.
[ 19 ]
| 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 |
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.
[ 20 ][ edit ]Largest 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 | 1,360,000–113,293,207 (36 billion gallons) | [ 21 ] [ 22 ]
|
| Ixtoc I oil well | Gulf of Mexico | June 3, 1979–March 23, 1980 | 454,000–480,000 | [ 24 ] |
| Atlantic Empress / Aegean Captain | Trinidad and Tobago | July 19, 1979 | 287,000 | [ 25 ] [ 26 ] |
| Fergana Valley | Uzbekistan | March 2, 1992 | 285,000 | [ 22 ] |
| Nowruz oil field | Persian Gulf | February 1983 | 260,000 | [ 27 ] |
| ABT Summer | 700 nautical miles (1,300 km) off Angola | 1991 | 260,000 | [ 25 ] |
| Castillo de Bellver | Saldanha Bay , South Africa | August 6, 1983 | 252,000 | [ 25 ] |
| Amoco Cadiz | Brittany , France | March 16, 1978 | 223,000 | [ 22 ] [ 25 ] |
| Amoco Haven tanker disaster | Mediterranean Sea near Genoa , Italy | 1991 | 144,000 | [ 25 ] |
| Odyssey | 700 nautical miles (1,300 km) off Nova Scotia , Canada | 1988 | 132,000 | [ 25 ] |
| Sea Star | Gulf of Oman | December 19, 1972 | 115,000 | [ 22 ] [ 25 ] |
| Torrey Canyon | Scilly Isles , UK | March 18, 1967 | 80,000–119,000 | [ 22 ] [ 25 ] |
| Irenes Serenade | Navarino Bay , Greece | 1980 | 100,000 | [ 25 ] |
| Urquiola | A Coruña , Spain | May 12, 1976 | 100,000 | [ 25 ] |
a One tonne of crude oil is roughly equal to 308 US gallons, or 7.33 barrels.
[ edit ]See also
[ edit ]References
- ^ "Hindsight and Foresight, 20 Years After the Exxon Valdez Spill" . National Oceanic and Atmospheric Administration. 2010-03-16 . Retrieved 2010-04-30 .
- ^ http://seeps.geol.ucsb.edu/
- ^ C. Michael Hogan (2008) Magellanic Penguin , GlobalTwitcher.com, ed. N. Stromberg
- ^ 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
- ^ Untold Seabird Mortality due to Marine Oil Pollution , Elements Online Environmental Magazine.
- ^ http://www.enviroliteracy.org/article.php/540.html
- ^ http://www.epa.gov/oilspill/ncp/bagents.htm
- ^ http://www.epa.gov/emergencies/content/ncp/products/s200.htm
- ^ a b "Emergency Response: Responding to Oil Spills" . Office of Response and Restoration . National Oceanic and Atmospheric Administration. 2007-06-20 .
- ^ Oil Spills
- ^ "Detergent and Oil Spills" . NEWTON BBS . 2002-10-12 .
- ^ Barry, Carolyn (2007). Slick Death: Oil-spill treatment kills coral , Science News vol. 172, p. 67.
- ^ http://response.restoration.noaa.gov/resource_resourcetopic.php?RECORD_KEY(resourcetopics)=resourcetopic_id&resourcetopic_id(resourcetopics)=37
- ^ http://response.restoration.noaa.gov/
- ^ 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.
- ^ Gundlach, ER and MO Hayes (1978). Vulnerability of Coastal Environments to Oil Spill Impacts. Marine Technology Society. 12 (4): 18-27.
- ^ 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.
- ^ 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.
- ^ Metcalf & Eddy. Wastewater Engineering, Treatment and Reuse. 4th ed. New York: McGraw-Hill, 2003. 98.
- ^ Anderson, EL, 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.
- ^ George Draffan. "Major Oil Spills" . Endgame . Retrieved 2007-07-29 .
- ^ a b c d e "History" . The Mariner Group .
- ^ "Gulf Oil Spill Is Bad, but How Bad?" .
- ^ 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 .
- ^ a b c d e f g h i j "Statistics" . ITOPF . Retrieved 2007-07-29 .
- ^ "Atlantic Empress/Aegean Captain" . Cedre . 2006-04 .
- ^ "Oil Spills and Disasters" . infoplease . infoplease .
[ edit ]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
[ edit ]External links
