The Great Pacific
Garbage Patch

What is it?

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The Great Pacific garbage patch, also described as the Pacific trash vortex, is a gyre of marine debris particles in the central North Pacific Ocean located roughly between 135°W to 155°W and 35°N and 42°N. The patch extends over an indeterminate area, with estimates ranging very widely depending on the degree of plastic concentration used to define the affected area.

The patch is characterized by exceptionally high relative concentrations of pelagic plastics, chemical sludge and other debris that have been trapped by the currents of the North Pacific Gyre. Despite its enormous size and density (4 particles per cubic meter), the patch is not visible from satellite photography, nor is it necessarily detectable to casual boaters or divers in the area, as it consists primarily of a small increase in suspended, often-microscopic particles in the upper water column.

Estimates of size range from 700,000 square kilometres (about the size of Texas) to more than 15,000,000 square kilometres (0.41% to 8.1% of the size of the Pacific Ocean)

Size

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The size of the patch 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. Instead, the size of the patch is determined by sampling. Estimates of size range from 700,000 square kilometres (270,000 sq mi) (about the size of Texas) 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, in some media reports, up to "twice the size of the continental United States". Such estimates, however, are conjectural given the complexities of sampling and the need to assess findings against other areas. Further, although the size of the patch is determined by a higher-than-normal degree of concentration of pelagic debris, there is no standard for determining the boundary between "normal" and "elevated" levels of pollutants to provide a firm estimate of the affected area.

Discovery

The Great Pacific 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. This research found high concentrations of marine debris accumulating in regions governed by 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 favorable to the creation of relatively stable waters. They specifically indicated the North Pacific Gyre.

Charles J. 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. 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. The patch is not easily visible, because it consists of very small pieces that are almost invisible to the naked eye. Most of its contents are suspended beneath the surface of the ocean, and the relatively low density of the plastic debris is, according to one scientific study, 5.1 kilograms per square kilometer of ocean area. A similar patch of floating plastic debris is found in the Atlantic Ocean.

The gyre's rotational pattern draws in waste material from across the North Pacific Ocean, including waste from the coastal waters off of North America and Japan.

Formation

It is thought that, like other areas of concentrated marine debris in the world's oceans, the Great Pacific 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.

Pollutants range in size from abandoned fishing nets to micro-pellets used in abrasive cleaners. Currents carry debris from the west coast of North America to the gyre in about six years, and debris from the east coast of Asia in a year or less. An international research project led by Dr. Hideshige Takada of Tokyo University of Agriculture and Technology studying plastic pellets, or nurdles, from beaches around the world may provide further clues about the origins of pelagic plastic.

There are no strong scientific data concerning the origins of pelagic plastics. According to a 2011 EPA report, "The primary source of marine debris is the improper waste disposal or management of trash and manufacturing products, including plastics (e.g., littering, illegal dumping)...Debris is generated on land at marinas, ports, rivers, harbors, docks, and storm drains and is generated at sea from fishing vessels, stationary platforms and cargo ships."

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Effect on Wildlife

Some of these long-lasting plastics end up in the stomachs of marine birds and animals, and their young, including sea turtles and the Black-footed Albatross. Midway Atoll receives substantial amounts of marine debris from the patch. Of the 1.5 million Laysan Albatrosses that inhabit Midway, nearly all are found to have plastic in their digestive system. Approximately one-third of their chicks die, and many of those deaths are due to being fed plastic from their parents. Twenty tons of plastic debris washes up on Midway every year with five tons of that debris being fed to Albatross chicks.

Besides the particles' danger to wildlife, on the microscopic level the floating debris can absorb organic pollutants from seawater, including PCBs, DDT, and PAHs. Aside from toxic effects, when ingested, some of these are mistaken by the endocrine system as estradiol, causing hormone disruption in the affected animal. 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. 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.

On the macroscopic level, the physical size of the plastic kills fish, birds and turtles as the animals' digestion cannot break down the plastic that is taking up space inside their stomachs. A second effect of the macroscopic plastic is to make it much more difficult for animals to detect their normal sources of food. While eating their normal source of food plastic ingestion can be unavoidable. 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.