Pacific Trash Vortex: differenze tra le versioni

Versione delle 17:17, 29 ott 2007

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{{WIP}}{{S|ecologia}}{{T|argomento=ecologia|lingua=inglese|ottobre 2007| [[Utente:91.122.170.39|91.122.170.39]] 16:17, 29 ott 2007 (CET)}}

<!--The '''North Pacific Gyre''' (also known as the '''North Pacific Subtropical Gyre''') is a swirling [[vortex]] of ocean currents comprising most of the northern [[Pacific Ocean]]. It is located between the [[equator]] and 50º N [[latitude]] and occupies an area of approximately ten million [[square miles]] (34 million&nbsp;km²).<!--I've put in the metric equivalent assuming that the miles referred to are nautical miles-->

The North Pacific [[Gyre]] has a clockwise circular pattern and comprises four prevailing [[ocean currents]]: the [[North Pacific Current]] to the north, the [[California Current]] to the east, the [[North Equatorial Current]] to the south, and the [[Kuroshio Current]] to the west.

== Waste ==

{{citations needed}}

The centre of the North Pacific Gyre is relatively stationary region of the Pacific Ocean (the area it occupies is often referred to as the [[horse latitudes]]) and the circular rotation around it draws waste material in. This has led to the accumulation of [[flotsam]] and other debris in huge floating 'clouds' of [[waste]] which have taken on informal names, the '''Great Pacific Garbage Patch''', the '''Eastern Garbage Patch''' or the '''Pacific Trash Vortex'''. While historically this debris has [[biodegradation|biodegraded]], the gyre is now accumulating vast quantities of [[plastic]] and [[marine debris]]. Rather than biodegrading, plastic [[photodegradation|photodegrades]], disintegrating in the ocean into smaller and smaller pieces. These pieces, still [[polymer]]s, eventually become individual molecules, which are still not easily digested.[http://www.mindfully.org/Plastic/Ocean/Pacific-Garbage-Patch27oct02.htm] The photodegraded plastic can produce [[pollutant]]s such as [[Polychlorinated biphenyl|PCBs]]. The floating particles also resemble [[zooplankton]], which can lead to them being consumed by [[jellyfish]], thus entering the ocean [[food chain]]. In samples taken from the gyre in 2001, the mass of plastic exceeded that of zooplankton (the dominant animalian life in the area) by a factor of six.

Occasionally, shifts in the ocean currents release [[flotsam]] lost from [[cargo ship]]s into the currents around the North Pacific Gyre, leading to predictable patterns of garbage washing up on the shores around the outskirts of the gyre. The most famous was the loss of approximately 80,000 [[Nike, Inc.|Nike]] sneakers and boots from the ship ''[[Hansa Carrier]]'' in [[1990]]: the currents of the gyre distributed the shoes around the shores of [[British Columbia]], [[Washington]], [[Oregon]], and [[Hawaii]] over the following three years. Similar cargo spills have involved tens of thousands of [[Friendly Floatees|bathtub toys]] in [[1992]] and hockey equipment in [[1994]]. These events have become a major source of data on global-scale ocean currents. Various institutions have asked the public to report the landfall locations of the objects (trainers, rubber ducks, etc.) that wash up as a method of tracking surface waters' response to the deeper ocean currents. [http://www.timesonline.co.uk/tol/news/uk/article1996553.ece]

For several years ocean researcher [[Charles Moore (marine researcher)|Charles Moore]]

has been investigating a concentration of floating plastic [[debris]]

in the North Pacific Gyre. He has reported concentrations of plastics

on the order of 3.34x10⁶pieces/km² with a mean

mass of 5.1kg/km² collected using a manta trawl with a

rectangular opening of 0.9x0.15m² at the surface. Trawls at

depths of 10m found less than half, consisting primarily of

[[Monofilament fishing line|monofilament line]] fouled with diatoms and other plankton.

Some sources<ref>{{Citation

| last=Berton

| first=Justin

| author-link=

| publication-date=Friday, October 19

| date=Friday, October 19

| year=2007

| title=Continent-size toxic stew of plastic trash fouling swath of Pacific Ocean

| periodical=San Francisco Chronicle

| publication-place=San Francisco

| publisher=Hearst

| pages=W-8

| url=http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/10/19/SS6JS8RH0.DTL

| accessdate=2007/10/22

}}</ref> have reported

that the size of the "island" is twice the size of [[Texas]], however

Moore's investigation does not state this.

Many of these long-lasting pieces wind up in the stomachs of marine

birds and animals.

[http://www.naturalhistorymag.com/1103/1103_feature.html]

== References ==

{{cleanup-section}}

* [http://marine-litter.gpa.unep.org/documents/World's_largest_landfill.pdf UNEP: World's Largest Landfill (pdf)]

* [http://www.naturalhistorymag.com/1103/1103_feature.html Trashed: Across the Pacific Ocean, plastics, plastics, everywhere]

* [http://www.acfnewsource.org/environment/plastic_plankton.html ACF: Plastics in the Plankton]

* [http://edition.cnn.com/2003/TECH/science/05/28/coolsc.oceansecrets/ CNN: How sneakers, toys and hockey gear help ocean science]

* [http://www.nrdc.org/news/newsDetails.asp?nID=2133 The Problem with Plastic: Waves of Junk Are Flowing Into Food Chain]

* C. J. Moore, S. L. Moore, M. K. Leecaster and S. B. Weisberg (December 2001). "A Comparison of Plastic and Plankton in the North Pacific Central Gyre", ''Marine Pollution Bulletin'' '''42''' (12), 1297-1300.

* [http://today.reuters.co.uk/news/CrisesArticle.aspx?storyId=N05174536 "Plastic trash vortex menaces Pacific sealife: study" Reuters article from 11-5-2006]

* [http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2007/10/19/SS6JS8RH0.DTL&type=politics "Continent-size toxic stew of plastic trash fouling swath of Pacific Ocean", San Francisco Chronicle, October 19, 2007]

* [http://oceans.greenpeace.org/en/the-expedition/news/trashing-our-oceans/ocean_pollution_animation Animated Pacific trash vortex showing drift of ocean pollution]

* [http://www.mindfully.org/Plastic/Ocean/Pacific-Garbage-Patch27oct02.htm Plastic Turning Vast Area of Ocean into Ecological Nightmare]

* 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.

<references/>

== External links ==

* [http://www.latimes.com/news/local/oceans/la-oceans-series,0,7842752.special LA Times special Altered Oceans]

* [http://www.algalita.org/newsletters.html Algalita Marine Research Foundation accounts of the North Pacific Gyre]

* [http://video.google.com/videoplay?docid=3892310789953943147 Google video: A world of unknown plastic pollution]

* [http://www.bestlifeonline.com/cms/publish/travel-leisure/Our_oceans_are_turning_into_plastic_are_we.shtml Best Life Magazine: Plastic Ocean]

* [http://www.mindfully.org/Plastic/Ocean/Trashing-Oceans-Plastic4nov02.htm Trashing the Oceans U.S. News & World Report 4th November 2002]

* [http://oceans.greenpeace.org/en/our-oceans/pollution/trash-vortex Greenpeace facts about the North Pacific Gyre]

* [http://www.npr.org/templates/story/story.php?storyId=15713260 NPR: Navigating the Pacific's 'Garbage Patch']

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