One study has estimated that of the 275 million tonnes of plastic waste generated by 192 countries in 2010, 4.8–12.7 million tonnes could have entered the ocean. That’s a serious amount in just one year.
Luckily, some plastic waste is recyclable…However, many of the world’s coastal countries currently do not have such recycling policies nor the technical capabilities, and so large quantities of plastic are not recycled and enter landfill. The durable properties of plastics make them persistent and slow to degrade in the environment, and ultimately non-recycled plastics on land and in the rivers are left to work their way into the oceans.
It’s at this point the story of plastic ocean pollution seems to become synonymous with microplastics. Typically less than 5 mm in size, microplastics can be eroded to particles as small as 1–100 nm – nanoplastics. Using modelling tools it has been estimated a total of 15–51 trillion microplastic particles have accumulated in the ocean. Some start out as large plastic pieces, slowly eroded by water; others start off as microplastics specifically produced for certain uses, eg microbeads in cosmetic products such as facewash, soaps and shower creams. Microbeads … after they have been washed down the drain, they have been found to evade filtration systems at water treatment works and are discharged directly into the oceans…
Another emerging source of marine microplastics from household wastewater is microfibres leaching from clothing when washed. Microfibres are 1/100th the diameter of a human hair and are used for better waterproofing, breathability and flexibility in sportswear. The most common types of microfibers are made from polyesters and polyamides, and according to researchers giving evidence to the UK House of Commons Environmental Audit Committee in 2016, the number of leached microfibres in wastewater could be as many as 1900 fibres per garment.
Although it is relatively easy to develop policies and bans for microbeads and microfibers, these sources are just a drop in the ocean in terms of tonnage….
[P]lastic waste can travel great lengths. As such, waste from one place can become an issue in a region geographically distant from the original source, due to the oceans’ powerful currents…. Microplastics…, can also exist on beaches and in deeper waters of the oceans where animals feed, and it’s here the main large scale threats to wildlife…[T]he main problem is marine wildlife mistaking micro- and nanoplastics for food. Once ingested, they can cause gut blockage, physical injury, changes to oxygen levels in cells in the body, altered feeding behaviour and reduced energy levels, which impacts growth and reproduction….
[T]here is a need to change the way plastic is viewed by society: from ubiquitous, disposable waste to a valuable, recyclable raw material, much like metal and glass. It’s hoped this will increase the economic value of plastic waste.
Better process design is also needed to improve the issue, especially with regards to recyclability and biodegradability. ..[T]he invention of new, bio-based polymers could lead to improved biodegradability, and this would be greatly helped by further research into the degradation of plastics in the environment. The new plastics must retain functionality but degrade to innocuous substances much quicker.