The fate of oceans full of plastic
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The existence of the Great Pacific Garbage Slick was predicted in a document published in 1988 by the National Oceanic and Atmospheric Administration of the United States. The predictions were based on results obtained by several Alaska-based researchers who, between 1985 and 1988, measured aggregations of plastic materials in the northern Pacific Ocean.
While floating waste of biological origin is spontaneously biodegraded, an enormous amount of non-biodegradable materials such as plastics and marine debris are accumulating in this ocean area. Instead of biodegrading, plastic photodegrades, that is, it disintegrates into smaller and smaller pieces up to the size of the polymers that compose it; nevertheless, the latter remain plastic and their biodegradation is still very difficult.
Photodegradation of plastics can produce PCB pollution. The buoyancy of plastic particles, which have a hydrostatic behavior similar to that of plankton, induces their ingestion by planktophagous animals, and this causes the introduction of plastic into the food chain.
In some seawater samples taken in 2001, the ratio between the amount of plastic and that of zooplankton, the dominant animal life in the area, was greater than six parts of plastic for each part of zooplankton. The fate of plastic in the ocean environment - a minireview is a study published on the Environmental science.
Processes & impacts, who, in his review said: "The presence of plastics in the marine environment poses a threat to ocean life and has received much scientific and public attention in recent years. Plastics were introduced to the market in the 1950s and since then, global production figures and ocean plastic littering have increased exponentially.
Of the 359 million tonnes (Mt) produced in 2018, an estimated 14.5 Mt has entered the ocean. In particular smaller plastic particles can be ingested by marine biota causing hazardous effects. Plastic marine debris (PMD) is exposed to physical, chemical and biological stressors.
These cause macro and microplastic to break down into smaller fragments, including sub micrometre sized nanoplastic particles, which may account for an important but so far unevaluated fraction of the ocean plastic budget Physicochemical and biological deterioration of PMD also leads to the release of more volatile compounds and the terminal oxidation of PMD, which most likely accounts for an important but also unevaluated fraction in the ocean plastic budget.
This minireview provides an overview on (1) the quantity of plastic production and waste, pathways for plastics to enter the marine realm, the inventory of PMD and the negative effects of PMD to ocean life. (2) We discuss plastic degradation mechanisms in the ocean, expanding on the processes of photodegradation and biodegradation.
(3) This review also highlights the emerging topic of nanoplastics in the sea and provides an overview on their specific physical and chemical properties, potential harm to ocean life, and nanoplastic detection techniques. "