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Microplastics: The Tiny Particles Plaguing Our Oceans

Updated: Nov 23, 2020

Ruth Spence

Since Blue Planet 2 graced our TV screens in 2017 the general public’s love and fascination with the ocean seemed to grow exponentially - and rightly so! However, along with the programme showcasing the beauty of everything marine, it highlighted the devastation that plastic is having on the ocean (watch this episode). It helped bring the environmental issues surrounding plastic pollution to the forefront of people’s minds. Plastic pollution is still a huge environmental issue, especially in marine habitats. It often makes you think of large pieces of debris on beaches and floating on the surface of the ocean, but something you might not think of is microplastics! So, get ready to learn all about microplastics from how they are formed, to why they are so detrimental to marine habitats and how you can help reduce your plastic pollution!

Where did it all begin?

Plastic became increasingly popular during the 1950s in both industrial and household products. Since the 1950s the worldwide production of plastic per year has grown from 1.5 million tonnes to 359 million tonnes in 2018. Plastic is lightweight, durable, strong and low-cost, making it the perfect material for various products in the consumer market. However, these desirable characteristics of plastic have now become the reason it’s causing a plethora of environmental issues.

"Beach strewn with plastic debris" by USFWS Headquarters is licensed under CC BY 2.0"

What are microplastics?

Microplastics are small pieces of plastic that are less than 5mm in diameter. Their small size means they can’t always be seen by the human eye, so when you’re in the ocean you may not be able to see microplastics floating in the water, but that doesn’t mean they aren’t there! Microplastics are split into two main categories: primary and secondary. Primary microplastics are plastics that have been made to be smaller than 5mm. ‘Microbeads’ are a primary microplastics, which are in toothpaste and face washes, however, these were banned in 2018 in the UK, following the ban in the US in 2015 - hooray! Another common primary microplastic is ‘nurdles’ which are mainly used in an industrial setting. Secondary microplastics are from larger plastics that have broken down into pieces smaller than 5mm over time.

How are they formed?

Secondary microplastics are the main type of microplastics we talk about when discussing the plastic pollution in the ocean. Plastic pollution from land starts from larger pieces of plastic which then breakdown into microplastics and become secondary microplastics, UV radiation, physical abrasion and waves all contribute to the breakdown of plastics. Plastics with a larger surface area are more vulnerable to these factors. Once the plastics have broken down into microplastics they become less affected by these environmental factors due to their smaller surface area, which leads to the accumulation of microplastics within the marine environment.

"Nurdles: pre production plastic pellets." Sustainable Coastlines is licensed under CC BY-NC 2.0 (left), "Microplastics - Beach Clean up - 25g plastics / 22m That's 638KG along the Oregon Coast" by Wolfram Burner is licensed under CC BY-NC 2.0 (right).

Why are there so many microplastics in the ocean?

Plastic is entering our oceans at an alarming rate. It’s estimated that 8 million metric tonnes enter the oceans every year! Now imagine all this plastic breaking down to even smaller pieces… that’s why there are SO many microplastics! Microplastics don’t just stay in one place either, their buoyancy and robust nature mean they have been found across the globe from the Arctic to the Antarctic, in marine sediment, floating in the water column and some of the most remote trenches of the oceans! So where do they all come from? Well, a big cause is the improper disposal of rubbish, such as unwanted waste dumped from ships, wind-blown litter from shorelines and litter left of beaches. Microplastics can also be in the shape of fibres, these fibres can be from synthetic materials like acrylic. A study found that acrylic fabric can potentially release a whopping 728,000 plastic fibres for every 6kg wash load! These fibres are then released into the water systems and eventually find their way into the ocean. These are just some of the ways plastic ends up in the oceans. When you combine the rate that plastic is entering the oceans with the fact that plastics can take more than 500 years to decompose, you start to fully grasp the gravity of the situation!

Why do they pose such a threat to marine life?

OKAY, so there are millions of microplastics in the oceans but you may be thinking if they are so small how are they causing such a big issue? Their small size allows them to be accidentally ingested by fish and larger marine mammals. Ingested plastic has been found throughout the marine food chain. Corals, zooplankton, sea birds, all marine turtle species, 48% of all cetacean species and many commercial fish species have all been found to have ingested plastics! Filter feeders (e.g. Manta rays, whale sharks and Baleen whales), are especially at risk of ingesting microplastics as they feed on zooplankton. Zooplankton are a similar diameter to microplastics meaning as these filter feeders take in large amounts of water their filtering systems can’t distinguish between zooplankton and microplastics. Once ingested the microplastics can leach out chemicals and cause not only blockages in digestive tracts but can affect reproduction and slow down growth rates.

Plastic ingested by an albatross - "Plastic ocean" by Tim Zim is licensed under CC BY-NC 2.0

How does this affect us?

It can sometimes be hard to see how environmental issues affect you, especially if you live far away from the area that’s in trouble. However, even if you don’t live near the coast the likelihood that you are being affected by microplastic pollution is high! A recent study found that humans could be consuming anywhere from 39,000 to 52,000 microplastics a year! These could be entering our bodies from tap water, bottled water, fish and salt (to name a few sources!) This isn’t meant to scare you and swear off all these foods forever, but hopefully, it’ll make you realise that even if you don’t live along the coast or eat commercial fish, microplastics are a global issue that we should all care about and strive to help combat!

What can we do to help?

The number of microplastics in the oceans may make you feel like we are fighting a losing battle, but if everyone reduced their output of plastic waste then we could significantly reduce the number of new microplastics formed! First thing you can do is to get to grips with what plastics can and can’t be recycled (here is information for people in the UK), once you know what can’t be recycled you can start to make changes to first cut out those types of plastics from your daily life. Small changes like a reusable water bottle, shopping bag or choosing to not put your vegetables in a plastic bag, can make a huge reduction in your plastic waste! If you want a more ‘get-up and go’ approach you can help out with beach clean-ups or clean-ups in your local greenspaces - these can usually be found on your local government websites!

Many people can feel overwhelmed by the thought of having to get rid of everything plastic in their homes all at once - which is understandable as we have relied on it for so long. But, it isn’t about a few people doing ‘plastic-free’ perfectly. If everyone does a little bit every day to help reduce their plastic waste, it’ll collectively help to make a change.

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