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Indian Ocean garbage patch

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The Indian Ocean Garbage Patch, discovered in 2010, is a gyre of marine litter suspended in the upper water column of the central Indian Ocean, specifically the Indian Ocean Gyre, one of the five major oceanic gyres.[1][2][3][4][5] The patch does not appear as a continuous debris field. As with other patches in each of the five oceanic gyres, the plastics in it break down to ever smaller particles, and to constituent polymers.[6] As with the other patches, the field constitutes an elevated level of pelagic plastics, chemical sludge, and other debris; primarily particles that are generally invisible to the naked eye.[7][8][9]

Map showing the oceans' five major gyres
There are trash vortices in each of the five major oceanic gyres.

A similar patch of floating plastic debris in the Pacific Ocean, the Great Pacific Garbage Patch, was predicted in 1985, and discovered in 1997 by Charles J. Moore as he passed through the North Pacific Gyre on his return from the Transpacific Yacht Race. The North Atlantic Garbage Patch was discovered in 2010.[10][11]

Discovery

 
The Indian Ocean Garbage Patch on a continuous ocean map centered near the south pole

The existence of the Great Pacific Garbage Patch, the first to be discovered, was predicted in a 1988 paper published by the National Oceanic and Atmospheric Administration (NOAA) of the United States. The prediction was based on results obtained by several Alaska-based researchers between 1985 and 1988 that measured neustonic plastic in the North Pacific Ocean.[12] It was extrapolated from the findings of high concentrations of marine debris, that similar conditions would occur in other parts of the Pacific where prevailing currents were favorable to the creation of relatively stable waters,[13] and this was also verified.[6]

Recent data collected from Pacific albatross populations suggest there may be two distinct zones of concentrated debris in the Pacific.[14]

Research studying trash washed onto beaches in and around the Indian Ocean suggested that there would be plastics found in the water column in the Indian Ocean as well.[2]

In 2010, the Five Gyres Project set off on the first of its planned series of transoceanic voyages to determine whether the South Atlantic, South Pacific, and Indian Ocean gyres were affected in the same way as the North Pacific and North Atlantic gyres.[1][2][4][5] On the Indian Ocean leg of their trip, they travelled between Perth, Australia, and Port Louis, Mauritius (east of Madagascar); each of the water samples they collected in the 3,000 miles between contained plastic.[2]

Formation

Main article: Photodegradation

Researchers into the effects and impact of plastic photodegradation have studied the patches.[15] Unlike debris, which biodegrades, the photodegraded plastic disintegrates into ever smaller pieces while remaining a polymer. This process continues down to the molecular level.[16] Large items readily visible from a boat deck do exist, but are uncommon;[17] most debris consists of small plastic particles 'confetti-like' pieces are clearly visible suspended at or just below the surface,[18] as confirmed by the August 2009 Scripps Institution of Oceanography / Project Kaisei SEAPLEX survey mission of the North Pacific Gyre. Despite its size and density, the patch is not visible from space with conventional satellite photography, since the majority of particles are too small.

The patches form gradually as a result of marine pollution gathered by oceanic currents.[19][20] The gyres' rotational pattern draws in waste material from surrounding waters; the currents prevent the escape of the material but do not prevent the relatively weaker force of wind-driven surface currents gradually moving floating debris toward the center.

Floating debris typically is sampled with a neuston or manta trawl net lined with 0.33 mm mesh. Long-term changes in plastic meso-litter have been reported using surface net tows: in the North Pacific Subtropical Gyre in 1999, plastic abundance was 335 000 items km2 and 5.1 kg km2, roughly an order of magnitude greater than samples collected in the 1980s. Similar dramatic increases in plastic debris have been reported off Japan.[21]

In a 2001 study of the Pacific gyre, in many of the sampled areas, the overall concentration of plastics was seven times greater than the concentration of zooplankton. Samples collected at deeper points in the water column found much lower concentrations of plastic particles (primarily monofilament fishing line pieces).[22] The mass of the Great Pacific Garbage Patch is estimated at 100 million tons.[23]

Sources of pollutants

Ship-generated pollution is a source of concern since a typical 3,000 passenger cruise ship produces over eight tons of solid waste weekly.[24] Pollutants range in size from abandoned fishing nets to micro-pellets used in abrasive cleaners.[25] Moore estimated that 80% of the garbage comes from land-based sources and 20% from ships.[26]

An international research project led by Dr. Hideshige Takada of Tokyo University studying plastic pellets, or nurdles, from beaches around the world may provide further clues about the origins of pelagic plastic.[27]

Ecological studies and conservation efforts

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 concentration in the neuston. Some plastics decompose within a year of entering the water, leaching potentially toxic chemicals such as bisphenol A, PCBs and derivatives of polystyrene.[28]

The food chain in the gyres and surrounding ocean areas are affected, beginning with small fish and jellyfish, and ending in larger fish, birds and humans.[29] Marine plastics also facilitate the spread of invasive species that attach to floating plastic in one region and drift long distances to colonize other ecosystems.[25]

 
The remains of a Laysan Albatross chick which was fed plastic by its parents resulting in death

Some of the long-lasting plastics end up in the stomachs of marine birds and animals, and their young,[6] including sea turtles and the Black-footed Albatross.[30] Besides the particles' danger to wildlife, the floating debris can absorb organic pollutants from seawater, including PCBs, DDT, and PAHs.[31] Aside from toxic effects,[32] when ingested, some of these are mistaken by the endocrine system as estradiol, causing hormone disruption in the affected animal.[30] Research has shown that this plastic marine debris affects at least 267 species worldwide and a few of the 267 species reside in the North Pacific Gyre.[33]

In April 2008 the Environmental Cleanup Coalition was formed to identify methods to safely remove plastic and persistent organic pollutants from the oceans.[34][35] The Algalita Marine Research Foundation built a raft made of plastic junk and sailed it across the Pacific in 2008 to report on the issue;[36][37][38] Project Kaisei, a project to study and clean up the garbage patch was launched in March 2009.[39]

The SEAPLEX expedition, a group of researchers from Scripps Institution of Oceanography, spent 19 days on the ocean in August, 2009 researching the N. Pacific patch. Their primary goal was to describe the abundance and distribution of plastic in the gyre in the most rigorous study to date. Researchers were also looking at the impact of plastic on mesopelagic fish, such as lanternfish.[40][41][42]

In 2010, the Five Gyres Project found that the South Atlantic, South Pacific, and Indian Ocean gyres were affected in the same way as the North Pacific and North Atlantic gyres.[1][2][4][5] Anna Cummins, cofounder of 5 Gyres Institute called the pollution they found "a thin plastic soup".[2]

Further reading

See Great Pacific Garbage Patch
  • Masahisa Kubota (2000). "Movement and accumulation of floating marine debris simulated by surface currents derived from satellite data" (PDF). School of Marine Science and Technology, Tokai University. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  • Gregory, M.R. (1997). "Pelagic plastics and other seaborne persistent synthetic debris: a review of Southern Hemisphere perspectives". In Coe, J.M., Rogers, D.B. (ed.). Marine Debris: Sources, Impacts, Solutions. New York: Springer-Verlag. pp. 49–66. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: multiple names: editors list (link)

See also

Citations

  1. ^ a b c First Voyage to South Atantic (sic) Pollution Site SustainableBusiness.com News
  2. ^ a b c d e f New garbage patch discovered in Indian Ocean, Lori Bongiorno, Green Yahoo, 27 Jul 2010]
  3. ^ Opinion: Islands are 'natural nets' for plastic-choked seas Marcus Eriksen for CNN, Petroleum, CNN Tech 24 June 2010
  4. ^ a b c Our Ocean Backyard: Exploring plastic seas, Dan Haifley, 15 May 2010, Santa Cruz Sentinel
  5. ^ a b c Life aquatic choked by plastic 14 November 2010, Times Live
  6. ^ a b c Moore, Charles (November 2003). "Across the Pacific Ocean, plastics, plastics, everywhere". Natural History Magazine. {{cite journal}}: Cite journal requires |journal= (help) Cite error: The named reference "natural history" was defined multiple times with different content (see the help page).
  7. ^ For a discussion of the current sampling techniques and particle size, see Peter Ryan, Charles Moore et al., Monitoring the abundance of plastic debris in the marine environment. Phil. Trans. R. Soc. B 27 July 2009 vol. 364 no. 1526 1999–2012, doi:10.1098/rstb.2008.0207
  8. ^ http://www.katu.com/outdoors/featured/112901159.html
  9. ^ Transoceanic Trash: International and United States Strategies for the Great Pacific Garbage Patch, Susan L. Dautel, 3 Golden Gate U. Envtl. L.J. 181 (2009)
  10. ^ Lovett, Richard A. (2 March 2010). "Huge Garbage Patch Found in Atlantic Too". National Geographic News. National Geographic Society.
  11. ^ Victoria Gill (24 February 2010). "Plastic rubbish blights Atlantic Ocean". BBC. Retrieved 16 March 2010.
  12. ^ Day, Robert H.; Shaw, David G.; Ignell, Steven E. (4). "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" (PDF) (published 1988). pp. 247–266. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)
  13. ^ "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)
  14. ^ Young LC, Vanderlip C, Duffy DC, Afanasyev V, Shaffer SA (2009) Bringing Home the Trash: Do Colony-Based Differences in Foraging Distribution Lead to Increased Plastic Ingestion in Laysan Albatrosses? PLoS ONE 4(10): e7623. doi:10.1371/journal.pone.0007623 {{doi}}: unflagged free DOI (link)
  15. ^ Thompson, Richard C.; Olsen, Y; Mitchell, RP; Davis, A; Rowland, SJ; John, AW; McGonigle, D; Russell, AE (7 May 2004). "Lost at Sea: Where Is All the Plastic?,". Science. 304 (5672): 843. doi:10.1126/science.1094559. PMID 15131299. Retrieved 19 July 2008. {{cite journal}}: More than one of |periodical= and |journal= specified (help)
  16. ^ D.K.A. Barnes et al., Accumulation and fragmentation of plastic debris in global environments, Phil. Trans. R. Soc. B 27 July 2009 vol. 364 no.1526, 1985–1998 doi:10.1098/rstb.2008.0205
  17. ^ August 2009 Scripps Institution of Oceanography / Project Kaisei SEAPLEX survey mission
  18. ^ Marks, Kathy (5 February 2008). "The world's rubbish dump". The Independent. London. Retrieved 4 May 2010.
  19. ^ David M. Karl, A Sea of Change: Biogeochemical Variability in the North Pacific Subtropical Gyre, Ecosystems, Vol. 2, No. 3 (May – Jun., 1999), pp. 181–214
  20. ^ Sverdrup HU, Johnson MW, Fleming RH. 1946. The oceans, their physics, chemistry and general biology. New York: Prentice-Hall
  21. ^ Ryan, Moore et al (2009)HI
  22. ^ 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. Vol. 42, no. 12 (published 2001-12-01). pp. 1297–1300. doi:10.1016/S0025-326X(01)00114-X. PMID 11827116. {{cite news}}: Check date values in: |date= and |year= / |date= mismatch (help); More than one of |periodical= and |journal= specified (help)
  23. ^ "The world's rubbish dump: a tip that stretches from Hawaii to Japan," Kathy Marks AND Daniel Howden. 5 February 2008. Independent.co.uk [1] accessed 15 March 2011
  24. ^ Clemmitt, Marcia. "New Rules Sought for 'Floating Cities.'" Saving the Oceans 15.39 (4 Nov 2005): n. pag. CQ Researcher Online. Web. 5 Oct 2009. <http://library.cqpress.com/cqresearcher/document.php?id=cqresrre2005110420&type=hitlist>.
  25. ^ a b Ferris, David (May/June 2009). "Message in a bootttttllleeee". Sierra. San Francisco: Sierra Club. Retrieved 13 August 2009. {{cite news}}: Check date values in: |date= (help)
  26. ^ Postulated in Moore 2004
  27. ^ "International Pellet Watch". Laboratory of Organic Geochemistry, Dr. Hideshige Takada. Retrieved 27 May 2009.
  28. ^ Barry, Carolyn (20 August 2009). "Plastic Breaks Down in Ocean, After All – And Fast". National Geographic News. National Geographic Society. Retrieved 30 August 2009.
  29. ^ Rogers, Paul. "'Pacific Garbage Patch' expedition finds plastic, plastic everywhere." The Contra Costa Times [Walnut Creek, CA] 1 Sep 2009: n. pag. Web. 4 Oct 2009. <http://www.contracostatimes.com/search/ ci_13258216?nclick_check=1>.
  30. ^ a b Moore, Charles (2 October 2002). "Great Pacific Garbage Patch". Santa Barbara News-Press. {{cite journal}}: Cite journal requires |journal= (help)
  31. ^ Rios, L.M. (2007). "Persistent organic pollutants carried by Synthetic polymers in the ocean environment". Marine Pollution Bulletin. 54 (8): 1230–1237. doi:10.1016/j.marpolbul.2007.03.022. PMID 17532349. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  32. ^ Tanabe, S. (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. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  33. ^ http://oceans.greenpeace.org/raw/content/en/documents-reports/plastic_ocean_report.pdf
  34. ^ Bradshaw, Kate (29 January 2009). "The Great Garbage Swirl". Maui Time Weekly. Maui: Linear Publishing. Retrieved 26 April 2009.
  35. ^ The Environmental Cleanup Coalition's "Gyre Cleanup" plan
  36. ^ Yap, Britt (28 August 2008). "A raft made of junk crosses Pacific in 3 months". USA Today. Archived from the original on 30 September 2009. Retrieved 30 September 2009.
  37. ^ "Raft made of junk bottles crosses Pacific". msnbc. 28 August 2008. Archived from the original on 30 September 2009. Retrieved 30 September 2009.
  38. ^ Jeavans, Christine (20 August 2008). "Mid-ocean dinner date saves rower". BBC News. Archived from the original on 30 September 2009. Retrieved 30 September 2009.
  39. ^ Walsh, Bryan (1 August 2009). "Expedition Sets Sail to the Great Plastic Vortex". Time. Retrieved 2 August 2009.
  40. ^ "SEAPLEX Day 11 Part 1: Midwater Fish « SEAPLEX". Seaplexscience.com. 12 August 2009. Retrieved 28 July 2010.
  41. ^ Staff Writers. "Scientists Find 'Great Pacific Ocean Garbage Patch.'" Space Daily 2 Sep 2009: n. pag. Gale. Web. 12 Oct 2009
  42. ^ http://shipsked.ucsd.edu/Ships/New_Horizon/specs.php http://sio.ucsd.edu/Expeditions/Seaplex/Science/
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