Great Pacific Garbage Patch

From Wikipedia, the free encyclopedia

Jump to: navigation, search
The Garbage Patch is located within the North Pacific Gyre, one of the five major oceanic gyres.

The Great Pacific Garbage Patch, also described as the Eastern Garbage Patch or the Pacific Trash Vortex, is a gyre of marine debris in the central North Pacific Ocean located roughly between 135° to 155°W and 35° to 42°N. The patch is characterized by exceptionally high concentrations of suspended plastic and other debris that have been trapped by the currents of the North Pacific Gyre.

Contents

[edit] Discovery

The existence of the Eastern Garbage Patch was predicted in a 1988 paper published by the National Oceanic and Atmospheric Administration (NOAA) of the United States. The prediction was based on experimental results obtained by several Alaska-based researchers between 1985 and 1988 that measured neustonic plastic in the North Pacific Ocean.[1] This research found high concentrations of marine debris accumulating in regions governed by particular patterns of ocean currents. Extrapolating from findings in the Sea of Japan, the researchers postulated that similar conditions would occur in other parts of the Pacific Ocean where prevailing currents were favourable to the creation of relatively stable bodies of water. They specifically indicated the North Pacific Gyre.[2]

The existence of the garbage patch received wider public and scientific attention after it was documented in several articles written by Charles Moore, a California-based sea captain and ocean researcher. Moore, returning home through the North Pacific Gyre after competing in the Transpac sailing race, came upon an enormous stretch of floating debris.

Moore alerted the oceanographer Curtis Ebbesmeyer to the existence of the phenomenon, who subsequently dubbed the region the "Eastern Garbage Patch" (EGP). The area is frequently featured in media reports as an exceptional example of marine pollution.[3]

[edit] Formation

Like other areas of concentrated marine debris in the world's oceans, the Eastern Garbage Patch has formed gradually over time as a result of marine pollution gathered by the action of oceanic currents.

The garbage patch occupies a large and relatively stationary region of the North Pacific Ocean bound by the North Pacific Gyre (a remote area commonly referred to as the horse latitudes). The rotational pattern created by the North Pacific Gyre draws in waste material from across the North Pacific Ocean, including the coastal waters off North America and Japan. As material is captured in the currents, wind-driven surface currents gradually move floating debris toward the center, trapping it in the region.

The size of the affected region is unknown, but estimates range from 700,000 km2 to more than 15 million km2, (0.41% to 8.1% of the size of the Pacific Ocean). The area may contain over 100 million tons of debris.[4] It has also been suggested that the patch may represent two areas of debris that are linked.[5]

[edit] Sources of pollutants

Charles Moore estimates that 80% of the garbage comes from land-based sources, and 20% from ships at sea.[6] Moore states that currents carry debris from the east coast of Asia to the center of the gyre in about five years, and debris from the west coast of North America in a year or less.[6]

[edit] Plastic photodegradation in the ocean

Main article: Photodegradation

The Eastern Garbage Patch has one of the highest levels of plastic particulate suspended in the upper water column. As a result, it is one of several oceanic regions where researchers have studied the effects and impact of plastic photodegradation in the neustonic layer of water.[7] Unlike debris which biodegrades, the photodegraded plastic disintegrates into ever smaller pieces while remaining a polymer. This process continues down to the molecular level.

As the plastic flotsam photodegrades into smaller and smaller pieces, it concentrates in the upper water column. As it disintegrates, the plastic ultimately becomes small enough to be ingested by aquatic organisms which reside near the ocean's surface. Plastic waste thus enters the food chain through its intense concentration in the neuston.

[edit] Density of neustonic plastics

Despite Charles Moore's description, the eastern garbage patch cannot be characterised as a continuous visible field of densely floating marine debris. The process of disintegration means that the plastic particulate in much of the affected region may be too small to be seen. Researchers must estimate the overall extent and density of plastic pollution in the EGP by taking samples. In a 2001 study, researchers (including Moore) found that in certain areas of the patch, concentrations of plastic reached one million particles per square mile.[8] The study found concentrations of plastics at 3.34 pieces with a mean mass of 5.1 milligrams per square meter. In many areas of the affected region, the overall concentration of plastics was greater than the concentration of zooplankton by a factor of seven. Samples collected at deeper points in the water column found much lower levels of plastic debris (primarily monofilament fishing line), confirming earlier observations that most plastic waste concentrates in the upper parts of the water column.

[edit] Impact on wildlife

The remnants of a Laysan Albatross chick which was fed plastic by its parents; the chick was unable to eject the plastic, resulting in death by either starvation or choking.

The floating plastic particles resemble zooplankton, which can be mistakenly consumed by jellyfish. Many of these long-lasting plastics end up in the stomachs of marine birds and animals,[9] including sea turtles, and the Black-footed Albatross.[10] Besides the particle's danger to wildlife, the floating debris can absorb organic pollutants from seawater, including PCBs, DDT and PAHs.[11] Aside from toxic effects,[12] when ingested, some of these are mistaken by the endocrine system as estradiol, causing hormone disruption in the affected animal.[10]

[edit] References

  1. ^ Day, Robert H.; Shaw, David G.; Ignell, Steven E. (4) (PDF), Quantitative distribution and characteristics of neustonic plastic in the North Pacific Ocean. Final Report to US Department of Commerce, National Marine Fisheries Service, Auke Bay Laboratory. Auke Bay, AK (published 1988), pp. 247–266, http://swfsc.noaa.gov/publications/TM/SWFSC/NOAA-TM-NMFS-SWFSC-154_P247.PDF 
  2. ^ "After entering the ocean, however, neuston plastic is redistributed by currents and winds. For example, plastic entering the ocean in Japan is moved eastward by the Subarctic Current (in Subarctic Water) and the Kuroshio (in Transitional Water, Kawai 1972; Favorite et al. 1976; Nagata et al. 1986). In this way, the plastic is transported from high-density areas to low-density areas. In addition to this eastward movement, Ekman stress from winds tends to move surface waters from the subarctic and the subtropics toward the Transitional Water mass as a whole (see Roden 1970: fig. 5). Because of the convergent nature of this Ekman flow, densities tend to be high in Transitional Water. In addition, the generally convergent nature of water in the North Pacific Central Gyre (Masuzawa 1972) should result in high densities there also." Day, etc... 1988, p. 261 (Emphasis added)
  3. ^ Berton, Justin (October 19 2007), "Continent-size toxic stew of plastic trash fouling swath of Pacific Ocean", San Francisco Chronicle (San Francisco: Hearst): W–8, Friday, October 19, http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/10/19/SS6JS8RH0.DTL, retrieved on 2007-10-22 
  4. ^ http://www.independent.co.uk/environment/the-worlds-rubbish-dump-a-garbage-tip-that-stretches-from-hawaii-to-japan-778016.html
  5. ^ La Canna, Xavier (February 4, 2008), "Floating rubbish dump 'bigger than US'", News.com.au (Australia: news.com.au), Friday, February 4, http://www.news.com.au/story/0,23599,23156399-2,00.html, retrieved on 2008-02-26 
  6. ^ a b "Garbage Mass Is Growing in the Pacific". National Public Radio. 2008-03-28. http://www.npr.org/templates/story/story.php?storyId=89099470. 
  7. ^ Thompson, Richard C. (7 May 2004), "Lost at Sea: Where Is All the Plastic?,", Science 304 (5672): 843, doi:10.1126/science.1094559, http://www.sciencemag.org/cgi/content/full/304/5672/838/DC1, retrieved on 2008-07-19 
  8. ^ Moore, Charles; Moore, S. L.; Leecaster, M. K.; Weisberg, S. B. (4), "A Comparison of Plastic and Plankton in the North Pacific Central Gyre" (PDF), Marine Pollution Bulletin 42 (12): 1297–1300, 2001-12-01, doi:10.1016/S0025-326X(01)00114-X, http://www.alguita.com/gyre.pdf 
  9. ^ Moore, Charles (November 2003). "Across the Pacific Ocean, plastics, plastics, everywhere". Natural History Magazine. http://www.naturalhistorymag.com/1103/1103_feature.html. 
  10. ^ a b Moore, Charles (2002-10-02). "Great Pacific Garbage Patch". Santa Barbara News-Press. http://www.mindfully.org/Plastic/Ocean/Pacific-Garbage-Patch27oct02.htm. 
  11. ^ Rios, L.M.; Moore, C. and Jones, P.R. (2007). "Persistent organic pollutants carried by Synthetic polymers in the ocean environment". Marine Pollution Bulletin 54: 1230–1237. doi:10.1016/j.marpolbul.2007.03.022. 
  12. ^ Tanabe, S.; Watanabe, M., Minh, T.B., Kunisue, T., Nakanishi, S., Ono, H. and Tanaka, H. (2004). "PCDDs, PCDFs, and coplanar PCBs in albatross from the North Pacific and Southern Oceans: Levels, patterns, and toxicological implications". Environmental Science & Technology 38: 403–413. doi:10.1021/es034966x. 

[edit] Further reading

  • Oliver J. Dameron, Michael Parke, Mark A. Albins and Russell Brainard (April 2007). "Marine debris accumulation in the Northwestern Hawaiian Islands: An examination of rates and processes", Marine Pollution Bulletin 54 (4), 423-433.
  • Floating plastic in the Kuroshio Current area, western North Pacific Ocean — Rei Yamashita and Atsushi Tanimura [Marine Pollution Bulletin; volume 54, issue 4, pages 485-488 (2007)]
  • Movement and accumulation of floating marine debris simulated by surface currents derived from satellite data — Masahisa Kubota, Katsumi Takayama and Noriyuki Horii [School of Marine Science and Technology, Tokai University (2000)]
  • Pelagic plastics and other seaborne persistent synthetic debris — M R Gregory and P G Ryan [Marine Debris: Sources, Impacts, Solutions; pages 49-66 — J M Coe and D B Rogers (1997)]
  • A comparison of plastic and plankton in the North Pacific Central Gyre — Charles J Moore, Shelly L Moore, Molly K Leecaster and Stephen B Weisberg
  • Density of plastic particles found in zooplankton trawls from coastal waters of California to the North Pacific Central Gyre — Charles J Moore, Gwen L Lattin and Ann F Zellers
  • The quantitative distribution and characteristics of neuston plastic in the North Pacific Ocean, 1984-1988 — R H Day, D G Shaw and S E Ignell (1988)
  • Thomas Morton, ‘Oh, This is Great, Humans Have Finally Ruined the Ocean’, Vice Magazine, Vol. 6, No. 2 (2007), pp. 78-81.

[edit] External links

 This article's external links may not follow Wikipedia's content policies or guidelines. Please improve this article by removing excessive or inappropriate external links.
v • d • e
Oceanic Gyres
North Pacific Gyre The five major oceanic gyres
South Pacific Gyre
North Atlantic Gyre
South Atlantic Gyre
Indian Ocean Gyre
Non-tropical gyres
Key concepts
Marine debris · Great Pacific Garbage Patch · Commons images
Retrieved from "http://en.wikipedia.org/wiki/Great_Pacific_Garbage_Patch"
Personal tools