South Pacific garbage patch
The South Pacific garbage patch is an area of ocean with increased levels of marine debris and plastic particle pollution, within the ocean's pelagic zone. This area is in the South Pacific Gyre, which itself spans from waters east of Australia to the South American continent, as far north as the Equator, and south until reaching the Antarctic Circumpolar Current. The degradation of plastics in the ocean also leads to a rise in the level of toxics in the area. The garbage patch was confirmed in mid-2017, and has been compared to the Great Pacific garbage patch's state in 2007, making the former ten years younger. The South Pacific garbage patch is[when?] impossible to detect using satellites, or other visual means as most particles are smaller than a grain of rice.
Evidence pointing to the existence of a garbage patch in the South Pacific gyre was made in early 2011 and its existence was confirmed in mid-2017. The discovery was made after a research voyage made by the 5 Gyres Institute. The voyage ran from March to April 2011, following a route based on a model of ocean currents developed by Nikolia Maximenko of the University of Hawaii, which predicts floating debris accumulation zones. The expedition started taking samples off the coast of Robinson Crusoe Island, Chile, and began working its way west, collecting new samples every 50 nautical miles, reaching the waters off Easter Island, and eventually Pitcairn Island.
A second water sampling voyage departing from Long Beach, California on November 2, 2016, lasting six months, was led by Charles J. Moore, and a team of researchers from Algalita Marine Research and Education. Upon departure the vessel began its journey south along the Baja California peninsula and on to the Galapagos Islands, continuing southwest on to Easter Island. After departing Easter Island the crew then headed eastward to the Juan Fernandez Islands, after which it continued north following the coast of Chile, with stopping points at Antofagasta, Chile, and Arica, Chile, before heading further out to sea for its return journey to Long Beach.
Composition, concentration and size
During the 5 Gyres expedition, 48 samples were taken from a 2,424 nautical sweep. The researchers found an increase in plastic pollution density, averaging 26,898 particles per square kilometer, but spiking at up to 396,342 particles per square kilometer, peaking near the center of the predicted accumulation zone, with some estimates as high as one million particles per square kilometer.
The composition of the garbage patch consists mainly of microbeads, tiny abrasives less than 5 micrometers in size usually found in certain personal hygiene products, microscopic fibers from washing clothes, fishing debris from southern hemisphere fishermen, and microscopic fragments of larger pieces which have been broken down in the ocean.
The elevated levels of pollutants can be detected over a vast area estimated to be 2.6 million square kilometers (one million square miles), or about 1.5 times the size of Texas, with the debris found along a nearly 2,500 nautical mile straight line route.
Effects on marine life and the ocean
As the plastic particles are primarily found in the pelagic layer of the ocean they experience high levels of Photodegradation, which causes the plastics to break down into ever smaller pieces. These pieces eventually become so small that even microorganisms can ingest and metabolize them, converting the plastics into carbon dioxide. In some instances, these microplastics are absorbed directly into a microorganism's biomolecules. However, before reaching this state, any number of organisms could potentially interact with these plastics. During their expedition in 2016-2017, Charles Moore and Algalita found that more than 35% of south Pacific Lanternfish had consumed plastic particles. When ingested by the fish, the chemical compounds found in these plastics cannot be digested. This can affect humans, as the Lanternfish is a food source for both salmon and tuna.
In their PNAS journal, Dr Van Sebille and his colleagues report data showing that in 1960 less than 5% of seabirds were found to have consumed waste material, while as of August 2015 that figure climbed to about 90%. It is predicted that by 2050, 99% of seabirds will have consumed such materials. Scientists studying the stomach contents of Laysan Albatross chicks report a 40% mortality rate before fledging. When the stomach contents were analyzed following necropsies, they were found to contain plastic waste. Not only do plastic pellets used in manufacturing worldwide absorb toxic chemicals such as DDT and PCBs from the water, but they can even leach chemicals such as biphenyl. It is estimated that up to 267 marine species are affected by plastic pollution.
Researchers led by chemist Katsuhiko Saido, a graduate from Nihon University's College of Pharmacy in Japan, have collected seawater samples worldwide, including from waters of the United States, Japan, India, and Europe. All samples collected were found to contain polystyrene derivatives. Polystyrene is a plastic found in styrofoam and many household and consumer goods. The scientists then simulated the decomposition of polystyrene in the open ocean. The results of this simulation showed that polystyrene, which begins breaking down at temperatures of 86° and higher, breaks down into harmful chemicals, such as Bisphenol A (BPA, which can cause reproductive harm in animals), styrene monomer (a suspected carcinogen), and styrene trimer (a by-product of polystyrene).
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