Great Pacific Garbage Patch

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 litter in the central North Pacific Ocean located roughly between 135° to 155°W and 35° to 42°N and estimated to be twice the size of Texas.^[1] 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. Despite its size and density, the patch is not visible from satellite photography because it consists of very, very small pieces, almost invisible to the naked eye ^[2] and most of its contents are suspended beneath the surface of the ocean. ^[3]

Discovery

The Patch is created in the gyre of the North Pacific Subtropical Convergence Zone

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 results obtained by several Alaska-based researchers between 1985 and 1988 that measured neustonic plastic in the North Pacific Ocean.^[4] 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 hypothesized that similar conditions would occur in other parts of the Pacific where prevailing currents were favourable to the creation of relatively stable waters. They specifically indicated the North Pacific Gyre.^[5]

The garbage patch received wider public and scientific attention after it was documented 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 in 1997, came upon an enormous stretch of floating debris. Feature-stories and video-reports in the UK mainstream media from early 2008, increased public attention to the plastic patch.

Moore alerted the oceanographer Curtis Ebbesmeyer, 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.^[6]

Formation

The north pacific garbage patch on a continuous ocean map

Like other areas of concentrated marine debris in the world's oceans, the Eastern Garbage Patch formed gradually as a result of marine pollution gathered by 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 gyre's rotational pattern draws in waste material from across the North Pacific Ocean, including 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 patch's size is unknown, as large items readily visible from a boat deck are uncommon. Most debris consists of small plastic particles suspended at or just below the surface, making it impossible to detect by aircraft or satellite.^[7] Estimates on size range from 700,000 square kilometres (270,000 sq mi) to more than 15,000,000 square kilometres (5,800,000 sq mi) (0.41% to 8.1% of the size of the Pacific Ocean), or "twice the size as continental United States".^[8] The area may contain over 100 million tons of debris.^[9] It has also been suggested that the patch may represent two linked areas.^[10]

In August 2009, the Scripps Institute / Project Kaisei SEAPLEX survey mission of the Gyre, found that plastic debris was present in 100 consecutive samples taken at varying depths and net sizes along a 1,700 miles (2,700 km) path through the patch.^[11] The survey also confirmed that while the debris field does contain large pieces, it is on the whole made up of smaller items which increase in concentration towards the Gyre's centre, and these 'confetti-like' pieces are clearly visible just beneath the surface.^[12]

Sources of pollutants

An estimated 80% of the garbage comes from land-based sources, and 20% from ships. A typical 3,000 passenger cruise ship produces over eight tons of solid waste weekly, much of which ends up in the patch. ^[13]Pollutants range in size from abandoned fishing nets to micro-pellets used in abrasive cleaners.^[14] Currents carry debris from the west coast of North America to the gyre in about five years, and debris from the east coast of Asia in a year or less.^[15][16] 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.^[17]

Plastic photodegradation in the ocean

The Eastern Garbage Patch has one of the highest levels known 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.^[18] 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 concentration in the neuston.

Some plastics decompose within a year of entering the water, leaching potentially toxic chemicals such as bisphenol A and derivatives of polystyrene.^[19]

Density of neustonic plastics

The patch is not a visibly dense field of floating debris. The process of disintegration means that the plastic particulate in much of the affected region is too small to be seen. Researchers must estimate the patch's overall extent and debris density from samples. In a 2001 study, researchers (including Moore) found that in certain areas, concentrations of plastic reached 1,000,000 per square mile (3,900 /ha).^[20] The study found concentrations of plastics at 3.34 pieces with a mean mass of 5.1 milligrams per square meter. In many areas the overall concentration of plastics was seven-fold greater than the concentration of zooplankton. Samples collected at deeper points in the water column found much lower levels of debris (primarily monofilament fishing line), confirming earlier observations that most plastic waste concentrates in the upper water column.

Impact on wildlife

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

Some of these long-lasting plastics end up in the stomachs of marine birds and animals,^[21] including sea turtles, and the Black-footed Albatross.^[22] Besides the particles' danger to wildlife, the floating debris can absorb organic pollutants from seawater, including PCBs, DDT, and PAHs.^[23] Aside from toxic effects,^[24] when ingested, some of these are mistaken by the endocrine system as estradiol, causing hormone disruption in the affected animal.^[22] These toxin-containing plastic pieces are also eaten by jellyfish, which are then eaten by larger fish. Many of these fish are then consumed by humans, resulting in their ingestion of toxic chemicals. ^[25] 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.^[14]

Cleanup

In April 2008, Richard Sundance Owen, a building contractor and scuba dive instructor, formed the Environmental Cleanup Coalition to address the issue North Pacific pollution. ECC collaborates with other groups to identify methods to safely remove plastic and persistent organic pollutants from the oceans.^[1][26]

The JUNK raft project was a trans-Pacific sailing voyage from June to August 2008 made to highlight the plastic in the patch, organised by the Algalita Marine Research Foundation.^[27][28][29]

Project Kaisei is a project to study and cleanup the garbage patch launched in March 2009. In August 2009 two project vessels, the New Horizon and the Kaisei, embarked on a voyage to research the patch and determine the feasibility of commercial scale collection and recycling.^[30]

The SEAPLEX expedition, a group of graduate students from the Scripps Institution of Oceanography, spent 19 days on the ocean in August researching the patch. They took samples and spread awareness; two steps essential to the cleaning-up process.^[31]

The Plastiki is a boat-building project by David Mayer de Rothschild hoping to highlight cleanup issues and sustainable plastic technologies.

References

Further reading

External links

• Scripps Environmental Accumulation of Plastic Expedition (SEAPLEX) — Scripps Institution of Oceanography, UC San Diego
• The Project Kaisei Voyage Tracker — Project Kaisei and Ojingolabs
• The trash vortex — Greenpeace
• Navigating the Pacific's 'Garbage Patch' — National Public Radio
• Marine Research, Education and Restoration — Algalita Marine Research Foundation
• Images & video from the North Pacific gyre — WordPress.com
• Sea of Trash - New York Times Magazine
• Captain Charles Moore on the seas of plastic
• Charles Moore: Sailing the Great Pacific Garbage Patch - TED Conference talk (2009)
• Skeptoid #132: The Sargasso Sea and the Pacific Garbage Patch
• E-Mails From the Great Pacific Garbage Patch by Laurie David, The Huffington Post, June 15 2009

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