How much plastic in the Ocean

Post by DPM Diving

July 28, 2021

Plastic of all sizes has become the most dominant form of marine litter.

It has been estimated that at least 5.25 trillion plastic pieces are floating in the Ocean. Moreover, at least 8 million metric tons of plastic are introduced to the oceans annually. The equivalent of a truckload of plastic every 60 seconds.

In this post we will be exploring more about this issue, sharing with you some details regarding:

A plastic ocean: The production

Plastics production increased rapidly from 2.3 million tons in the 1950s, to a global production reaching about 367 million tons in 2020. Half of all plastics ever manufactured have been made in the last 15 years.

Plastics have been used increasingly in place of more traditional materials in many sectors, including construction, transportation, household goods and packaging.

The low cost, lightweight, strength and durability of plastics are properties that make them suitable for manufacture on a wide range of daily use products. Virtually everything is made of plastic nowadays. 

There are many different varieties of polymer produced but in volume terms the market is dominated by a handful of main types:

  • Polyethylene (PE, high and low density)
  • Polyethylene terephthalate (PET) Polypropylene (PP)
  • Polyvinyl chloride (PVC)
  • Polystyrene (PS, including expanded EPS)
  • Polyurethane (PUR)

Most types of plastic contain additives making them stronger, more flexible, and durable. But many of these additives can extend the life of products if they become litter, with some estimates ranging to at least 400 years to break down.

Land a Sea-based Pollution Sources

Land-based plastic pollution sources

According to the United Nations Environment Programme, an estimated 80 per cent of all marine pollution is caused by human activities on land in the form of solid waste leakage including plastic from inadequate waste management.

Sewage disposal in rivers and coastal waters; urban storm-water run-off; sediment mobilization; inadequately treated waters from industries; discharges of phosphorus and nitrogen used in agriculture; and dumping of heavy metals and persistent organic pollutants.

Some of the most important land-based sources of larger plastic objects (macroplastics) include: construction, household goods, packaging, coastal tourism, and food and drink packaging. Around 40% of all plastic production is used for packaging. And much of this is designed for single-use. 

plastic straws collected in beach cleanup

Sea-based plastic pollution sources

Sea-based sources appear to be dominated by the fisheries and shipping sectors. The commercial fisheries sector has adopted plastics widely, because of the many advantages plastics offer over more traditional natural fibers.

Losses in the fisheries sector comprise loss of fishing gear (e.g. nets, ropes, floats, fishing line), loss of ancillary items (e.g. gloves, fish boxes, strapping bands), and release of fibers and other fragments due to normal wear and tear (e.g. use of ground ropes).

Fishing gear may be lost at sea by accident, abandonment or deliberate disposal.

This is commonly referred to as abandoned, lost or otherwise discarded fishing gear, and probably represents the largest category in terms of volume and potential impact out of all the sea-based sources.

fishing gear plastic pollution

Microplastics: how does plastic get into the ocean?

What are Microplastics?

Microplastics are defined as small particles or fragments of plastic measuring less than 5 mm in diameter.

Scientists of the Commonwealth Scientific and Industrial Research Organization (CSIRO), an Australian Government agency, estimated that 14 million tons of microplastic exist on the whole ocean floor. 

Primary Microplastics

Some microplastics are purposefully manufactured for industrial and domestic purposes (‘primary’ microplastics). These include ‘microbeads’ used in cosmetic and personal healthcare products, such as toothpaste.

The total numbers of microplastics in a typical cosmetic product can be considerable; for example, it has been estimated that 4,600 – 94,500 microbeads may be released per application of a skin exfoliant.

microplastic in toothpaste
Your toothpaste contains Microplastics

It is inevitable that substantial numbers of microbeads will enter waterways, depending on the existence and efficacy of wastewater treatment facilities.

The plastics industry tends to produce and transport plastics as circular or cylindrical resin pellets, a few mm in diameter. These are transported to other facilities where the plastic is further processed and ultimately used in the manufacture of either a finished product or component for a more complex product.

There have been many instances of accidental loss of resin pellets during transport, transshipment or at manufacturing facilities. Resin pellets have become widely distributed in the marine environment as a result. 

Secondary Microplastics

‘Secondary’ microplastics are created by the weathering and fragmentation of larger plastic objects.

Release of fibers from textiles and clothing is recognized as a major potential source of microplastic sized pieces, especially during mechanical washing.

microplastic from fabrics
Consider this when buying clothing

The emission of plastic particle dust from tire wear has been recognized recently as potentially a major source of microplastic contamination to the sea.

Routine wear and tear of fishing gear and other equipment results in the introduction of a variety of secondary microplastics. 

Marine Plastic Distribution 

Marine plastics are distributed throughout the ocean, from the Arctic to the Antarctic. This is due to the durability of plastics, the global nature of potential sources and the ease to which surface currents will carry floating plastics.

There are several persistent features such as the five sub-tropical gyres in the Indian Ocean, North and South Atlantic, and North and South Pacific. These are areas with relatively high concentrations of floating microplastics. 

However, higher abundances of plastics (especially macroplastics) are also found in coastal waters, particularly in regions with: high coastal populations with inadequate waste collection and management; intensive fisheries; and, high levels of coastal tourism.

Larger floating objects are also driven by winds, accumulating on mid-ocean islands and on shores distant from the source. Many types of plastic are denser than seawater so will sink once any initial buoyancy is removed.

For example, empty drinks bottles made with the plastic PET are very common litter items on shorelines, but their ultimate fate is often the ocean sea floor. Most fishing gear will sink if the floatation buoys are removed. For this reason, much of the plastic debris in the ocean is out of sight, and will remain so for the foreseeable future. 

Plastics marked as ‘biodegradable’ do not degrade rapidly in the ocean. The extent to which biodegradation takes place in the ocean is difficult to estimate but is considered to be extremely slow.

Once plastic becomes buried, enters the water column or gets covered in biological and inorganic coatings, which happens rapidly in seawater, then the rate of degradation becomes extremely slow due to decreased UV exposure, lower temperature and lower oxygen levels. 

Ecological Impact of plastic in the ocean

Marine plastics can have significant ecological impacts.

The most visible and disturbing are the ingestion, suffocation and entanglement of hundreds of marine species.

Seabirds, whales, fishes and turtles mistake plastic waste for prey, and most die of starvation as their stomachs are filled with plastic debris. They also suffer from lacerations, infections, reduced ability to swim, and internal injuries.

sea turtle eating plastic bag

Another major impact relates to habitat damage

Coral reefs are very susceptible to damage from abandoned, lost or discarded fishing gear. The movement of nets and ropes under the influence of winds or tidal currents can cause extensive damage. 

Microplastics have been found in many fish and shellfish species, and some cetaceans, but the impact is much more difficult to quantify and remains a knowledge gap.

The ocean is contaminated with a wide range of organic and inorganic compounds as a legacy of decades of industrial development and economic growth. Many organic pollutants are lipophilic, meaning they sorb readily to fats and oils in fish, mammals and other organisms. 

Plastics have similar properties to natural fats, acting as a ‘sponge’ to remove and concentrate contaminants from the water column. If an animal, such as a fish, bird or marine mammal, ingests plastic particles then there is the potential for transfer of these absorbed chemicals into the tissue causing diseases, abnormalities and death.

And not only animals are under threat.

People whose diets include large amounts of fish and shellfish are at very high risk.

How can we help the ocean from plastic?

By refusing plastic. Easy answer. But that is not an easy solution. At all. It certainly requires a lot of effort. Plastic is cheap and easy to find whereas most sustainable replacements could be less affordable and reachable. 

So here are a few ideas to encourage you to take the pledge for the ocean!

  • Start with single use plastic: water bottles, plastic cutlery, coffee cups, plastic bags, straws, polystyrene food containers, etc. All these pollutants can be easily replaceable with items you have at home. Don’t be lazy and remember to have your kit ready every time you go out.
  • Think twice before doing any purchase:  fast fashion and seasonal stuff are easy to avoid. Buy less. Borrow and swap more. Or go for second-hand options!
  • Long lasting personal health-care products: metal razors, cloth face pads, the moon cup, are just a few examples of sustainable options that save you money and plastic in the ocean! 
  • Do it yourself: there are eco-friendly shampoo and conditioner recipes, toothpaste and facial creams tutorials (among others) available in most social media platforms made of natural and easy to find ingredients. Better for your health and better for the ocean!
  • Do not take for granted that somebody else will do it: in your walks to the park, at the street, on the beach… pick up any trash you see around. It may not be your garbage but it’s your planet.

Last but not least: try to do your personal best. One day at a time.

Remember that the ocean doesn’t need a handful of people doing zero waste perfectly but millions of people doing it imperfectly!

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