Scientists suspect they lack nearly 99 percent of the plastic that should be in the environment. Unfortunately, it did not disappear by itself, most likely it was lost somewhere in the ocean.
In the last few years, researchers have solved at least part of this puzzle: rubbish does not disappear, it only spreads across the ocean. Macroplastics such as bags and bottles break down into microplastics less than 5 mm in diameter, which swirl in the water column and then sink to the bottom.
In an article published in the journal Nature Communications, scientists at the UK’s National Oceanographic Center say they already know where the missing plastic is. Thus, they also show the astonishing scale of pollution of the seas and oceans.
After examining 12 sites in the middle of the Atlantic, between the UK and the Falkland Islands, the researchers calculated that there were between 12 and 21 million tons of plastic in the upper 200 meters of the ocean. It should be emphasized, however, that the researchers only searched a narrow layer of the ocean, the depth of which could reach 8 km, and searched for only the three most common types of plastic – polyethylene, polypropylene and polystyrene. This means that there can actually be much more microplastics in the Atlantic.
The above studies are part of a larger research project led by specialists who are trying to sketch the microplastic cycle in the environment and analyze how these tiny particles move between land, sea and air. So far, the results are worrying to say the least.
Initially, scientists were convinced that microplastics were left in the ocean, which acted like a sink, but recently it has been found that particles can also get out of sea water and return to the land by the wind, and there also reach our lungs. Similarly, the wind lifts microplastics from land to the atmosphere, from where they fall back to the surface in the form of plastic rain.
By studying the oceans, scientists check by which processes microplastics move to different parts of the ocean and how they move vertically along the water column. Earlier this year, researchers showed that strong deep-sea currents transport particles to the ocean floor depressions, effectively contaminating them. A year ago, another group of scientists discovered that small fish confuse microplastics for food. Larger fish will eat small fish and these will eat even larger ones. This is how microplastics find their way into e.g. seafood. Scientists have confirmed some time ago that sardine oysters are full of plastic.
In this latest study, scientists focused on the top 200 meters of the Atlantic, which is full of microplastics. The floating microplastic particles usually collect a specific biofilm of organic matter around them, weighing them down and pulling them towards the bottom. This means that plastics do not remain on the surface, and over time they sink to the bottom of water bodies.
Pabortsava believes that one reason why the millions of tons of plastic bags and bottles that end up in the oceans every year simply disappear is because we are looking for microplastics of the wrong size. The larger the sieve we will use to catch microplastics, the less we will find.
Previously, we were unable to find nearly 99 percent of the plastics that end up in the ocean because we did not collect the right-sized particles on the surface, or because they break down and are transported down towards the ocean floor.
Going down to a particle size of 25 micrometers, Pabortsava found all the missing plastic. Although other researchers note that Pabortsava took samples from the ocean, among others, in the two most polluted subtropical regions of the ocean, and then extrapolated these measurements to the entire Atlantic. In this way – they write – precise data cannot be obtained.
However, it is worth remembering that 12-21 million tons of microplastics, according to the article, are found only in the upper 200 meters of the ocean. This means that there is actually a lot more plastic in the ocean. There is still a lot of water left under those 200 meters.
The upper 200 meters of the ocean contain up to 21 million tons of plastic. And no, this figure does not include the microfiber