Great Pacific garbage patch
Great Pacific garbage patch
The Great Pacific garbage patch, also described as the Pacific trash vortex, is a gyre of marine debris particles in the north central Pacific Ocean. It is located roughly from 135°W to 155°W and 35°N to 42°N. The collection of plastic and floating trash originates from the Pacific Rim, including countries in Asia, North America, and South America. The patch is actually "two enormous masses of ever-growing garbage". What has been referred to as the "Eastern Garbage Patch" lies between Hawaii and California, while the "Western Garbage Patch" extends eastward from Japan to the Hawaiian Islands. An ocean current about 6,000 miles long, referred to as the Subtropical Convergence Zone, connects both of the patches, which extend over an indeterminate area of widely varying range, depending on the degree of plastic concentration used to define the affected area. The vortex is characterized by exceptionally high relative pelagic concentrations of plastic, chemical sludge, wood pulp, and other debris trapped by the currents of the North Pacific Gyre.
Despite the common public perception of the patch existing as giant islands of floating rubbish, its low density (4 particles per cubic meter) prevents detection by satellite imagery, or even by casual boaters or divers in the area. This is because the patch is a widely dispersed area consisting primarily of suspended "fingernail-sized or smaller bits of plastic", often microscopic, particles in the upper water column. Researchers from The Ocean Cleanup project claimed that the patch covers 1.6 million square kilometers. The plastic concentration is estimated to be up to 100 kilograms per square kilometer in the center, going down to 10 kilograms per square kilometer in the outer parts of the patch. An estimated 80,000 metric tons of plastic inhabit the patch, totaling 1.8 trillion pieces. 92% of the mass in the patch comes from objects larger than 0.5 centimeters, while 94% of the total objects are represented by microplastics.
Some of the plastic in the patch has been found to be over 50 years old, and includes fragments of and items such as "plastic lighters, toothbrushes, water bottles, pens, baby bottles, cell phones, plastic bags, and nurdles". It is estimated that approximately "100 million tons of plastic are generated [globally] each year", and about 10% of that plastic ends up in the oceans. The United Nations Environmental Program recently estimated that "for every square mile of ocean", there are about "46,000 pieces of plastic". The small fibers of wood pulp found throughout the patch are "believed to originate from the thousands of tons of toilet paper flushed into the oceans daily". The patch is believed to have increased "10-fold each decade" since 1945.
The patch was described in a 1988 paper published by the National Oceanic and Atmospheric Administration (NOAA). The description was based on research by several Alaska-based researchers in 1988 who measured neustonic plastic in the North Pacific Ocean. Researchers found relatively high concentrations of marine debris accumulating in regions governed by ocean currents. Extrapolating from findings in the Sea of Korea, 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 Transpacific Yacht Race in 1997, claimed to have come 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.
In 2009, two project vessels from Project Kaisei,/ Ocean Voyages Institute; the New Horizon and the Kaisei, embarked on a voyage to research the patch and determine the feasibility of commercial scale collection and recycling. The Scripps Institute of Oceanography's 2009 SEAPLEX expedition in part funded by Ocean Voyages Institute/Project Kaisei also researched the patch. Researchers were also looking at the impact of plastic on mesopelagic fish, such as lanternfish.
In 2010 Ocean Voyages Institute conducted a 30-day expedition in the gyre which continued the science from the 2009 expeditions and tested prototype cleanup devices.
in July & Aug 2012 Ocean Voyages Institute conducted a voyage from San Francisco to the Eastern limits of the North Pacific Gyre north, (ultimately ending in Richmond British Columbia) and then made a return voyage which also visited the Gyre. The focus on this expedition was surveying the extent of tsunami debris from the Japanese earthquake tsunami.
At TEDxDelft2012, Boyan Slat unveiled a concept for removing large amounts of marine debris from oceanic gyres. Calling his project The Ocean Cleanup, he proposed to use surface currents to let debris drift to collection platforms. Operating costs would be relatively modest and the operation would be so efficient that it might even be profitable. The concept makes use of floating booms that divert rather than catch the debris. This avoids bycatch, while collecting even the smallest particles. According to Slat's calculations, a gyre could be cleaned up in five years' time, amounting to at least 7.25 million tons of plastic across all gyres. He also advocated "radical plastic pollution prevention methods" to prevent gyres from reforming. In 2015, The Ocean Cleanup project was a category winner in the Design Museum's 2015 Designs of the Year awards. A fleet of 30 vessels, including a 32-metre (105-foot) mothership, took part in a month-long voyage to determine how much plastic is present using trawls and aerial surveys.
The 2012 Algalita/5 Gyres Asia Pacific Expedition began in the Marshall Islands on 1 May, investigated the patch, collecting samples for the 5 Gyres Institute, Algalita Marine Research Foundation and several other institutions, including NOAA, Scripps, IPRC and Woods Hole Oceanographic Institute. In 2012, the Sea Education Association (SEA) conducted research expeditions in the gyre. One hundred and eighteen net tows were conducted and nearly 70,000 pieces of plastic were counted.
In 2012, researchers Goldstein, Rosenberg and Cheng found that microplastic concentrations in the gyre had increased by two orders of magnitude in the prior four decades.
In June 2019, Ocean Voyages Institute, the same organization behind the 2009, 2010 & 2012 expeditions, conducted a cleanup in the gyre and removed over 84,000 pounds of polymer nets and consumer plastic trash from the ocean.
In 2015, a study published in the journal Science sought to discover where exactly all of this garbage is coming from. According to the researchers, the discarded plastics and other debris floats eastward out of countries in Asia from six primary sources: China, Indonesia, the Philippines, Vietnam, Sri Lanka and Thailand. In fact, the Ocean Conservancy reported that China, Indonesia, Philippines, Thailand, and Vietnam dump more plastic in the sea than all other countries combined. China alone is responsible for 30% of worldwide plastic ocean pollution. Efforts to slow land generated debris and consequent marine debris accumulations have been undertaken by the Coastal Conservancy, Earth Day, and World Cleanup Day.
The Great Pacific garbage patch formed gradually as a result of ocean or marine pollution gathered by ocean currents. It occupies a relatively stationary region of the North Pacific Ocean bounded by the North Pacific Gyre in the horse latitudes. The gyre's rotational pattern draws in waste material from across the North Pacific, incorporating coastal waters off North America and Japan. As material is captured in the currents, wind-driven surface currents gradually move debris toward the center, trapping it.
In a 2014 study researchers sampled 1571 locations throughout the world's oceans, and determined that discarded fishing gear such as buoys, lines and nets accounted for more than 60% of the mass of plastic marine debris. 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. Debris is generated at sea from fishing vessels, stationary platforms, and cargo ships." Constituents range in size from miles-long abandoned fishing nets to micro-pellets used in cosmetics and abrasive cleaners. A computer model predicts that a hypothetical piece of debris from the U.S. west coast would head for Asia, and return to the U.S. in six years; debris from the east coast of Asia would reach the U.S. in a year or less. While microplastics make up 94% of the estimated 1.8 trillion plastic pieces, they amount to only 8% of the 79,000 metric tons of plastic there, with most of the rest coming from the fishing industry.
The size of the patch is indefinite, as is the precise distribution of debris, because large items are uncommon. Most debris consists of small plastic particles suspended at or just below the surface, evading detection 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) (about the size of Russia). 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.
Net-based surveys are less subjective than direct observations but are limited regarding the area that can be sampled (net apertures 1–2 m and ships typically have to slow down to deploy nets, requiring dedicated ship's time). The plastic debris sampled is determined by net mesh size, with similar mesh sizes required to make meaningful comparisons among studies. Floating debris typically is sampled with a neuston or manta trawl net lined with 0.33 mm mesh. Given the very high level of spatial clumping in marine litter, large numbers of net tows are required to adequately characterize the average abundance of litter at sea. 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. However, caution is needed in interpreting such findings, because of the problems of extreme spatial heterogeneity, and the need to compare samples from equivalent water masses, which is to say that, if an examination of the same parcel of water a week apart is conducted, an order of magnitude change in plastic concentration could be observed.— Ryan et al
In August 2009, the Scripps Institution of Oceanography/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 path of 1,700 miles (2,700 km) through the patch. The survey found that, although the patch contains large pieces, it is on the whole made up of smaller items that increase in concentration toward the gyre's centre, and these 'confetti-like' pieces that are visible just beneath the surface suggests the affected area may be much smaller. 2009 data collected from Pacific albatross populations suggest the presence of two distinct debris zones.
In March 2018, The Ocean Cleanup published a paper summarizing their findings from the Mega- (2015) and Aerial Expedition (2016). In 2015, the organization crossed the Great Pacific garbage patch with 30 vessels, to make observations and take samples with 652 survey nets. They collected a total of 1.2 million pieces, which they counted and categorized into their respective size classes. In order to also account for the larger, but more rare debris, they also overflew the patch in 2016 with a C-130 Hercules aircraft, equipped with LiDAR sensors. The findings from the two expeditions, found that the patch covers 1.6 million square kilometers with a concentration of 10–100 kg per square kilometer. They estimate an 80,000 metric tons in the patch, with 1.8 trillion plastic pieces, out of which 92% of the mass is to be found in objects larger than 0.5 centimeters.
While "Great Pacific Garbage Patch" is a term often used by the media, it does not paint an accurate picture of the marine debris problem in the North Pacific Ocean. The name "Pacific Garbage Patch" has led many to believe that this area is a large and continuous patch of easily visible marine debris items such as bottles and other litter—akin to a literal island of trash that should be visible with satellite or aerial photographs. This is not the case.— Ocean Facts, National Ocean Service
Photodegradation of plastics
The patch is one of several oceanic regions where researchers have studied the effects and impact of plastic photodegradation in the neustonic layer of water. Unlike organic debris, which biodegrades, plastic disintegrates into ever smaller pieces while remaining a polymer (without changing chemically). This process continues down to the molecular level. Some plastics decompose within a year of entering the water, releasing potentially toxic chemicals such as bisphenol A, PCBs and derivatives of polystyrene. As the plastic flotsam photodegrades into smaller and smaller pieces, it concentrates in the upper water column. As it disintegrates, the pieces become small enough to be ingested by aquatic organisms that reside near the ocean's surface. Plastic may become concentrated in neuston, thereby entering the food chain.
Disintegration means that much of the plastic is too small to be seen. In a 2001 study, researchers found concentrations of plastic particles at 334,721 pieces per km2 with a mean mass of 5.1 kg (11.3 lbs) per km2, in the neuston. The overall concentration of plastics was seven times greater than the concentration of zooplankton in many of the sampled areas. Samples collected deeper in the water column found much lower concentrations of plastic particles (primarily monofilament fishing line pieces).
Effect on marine life and humans
The United Nations Ocean Conference estimated that the oceans might contain more weight in plastics than fish by the year 2050. Some long-lasting plastics end up in the stomachs of marine animals. Plastic attracts seabirds and fish. When marine life consumes plastic allowing it to enter the food chain, this can lead to greater problems when species that have consumed plastic are then eaten by other predators.
Animals can also become trapped in plastic nets and rings, which can cause death. Sea turtles are most affected by this. Cetaceans have been sighted within the patch, which poses entanglement and ingestion risks to animals using the Great Pacific garbage patch as a migration corridor or core habitat.
Affected species include sea turtles and the black-footed albatross. Midway Atoll receives substantial amounts of marine debris from the patch.
Direct harm to species
Of the 1.5 million Laysan albatrosses that inhabit Midway Atoll, nearly all are likely to have plastic in their gastrointestinal tract. Approximately one-third of their chicks die, and many of those deaths are from plastic unwittingly fed to them by their parents. Twenty tons of plastic debris washes up on Midway every year with five tons ending up in the bellies of albatross chicks. Fish and whales may also mistake the plastic as a food source.
Indirect harm via the food chain
On the microscopic level, debris can absorb organic pollutants from seawater, including PCBs, DDT and PAHs. Aside from toxic effects, some of these are mistaken by the endocrine system as estradiol, disrupting hormone levels in affected animals. These toxin-containing plastic pieces are also eaten by jellyfish, which are then eaten by fish and then by humans.
Spreading invasive species
Increasing microplastic concentrations has released the insect Halobates sericeus from substrate limitation. A positive correlation between H. sericeus and microplastic was observed, along with increasing H. sericeus egg densities.
Ecosystem of the North Pacific Subtropical Gyre
Indian Ocean garbage patch
North Atlantic garbage patch
Plastic resin pellet pollution
South Pacific garbage patch
World Cleanup Day