About 13 million tonnes of plastic reach the oceans each year, but little is yet known about its impact on marine ecosystems. This researcher has received one of the L’Oréal-UNESCO awardsFor Women in Science for studying its effects.
Crowd ofplastics of all kinds end up in the sea, creating in some areas artificial islands ofwaste. In contact with water and exposed to sunlight, these polymers degrade releasing additives that are harmful to the environment.
The researcher Cristina Romera placeholder image(Jaén, 1982) is in charge of analyzing the conditions that favor the migration of these organic compounds from microplastics to the sea at the Institute of Marine Sciences (CSIC) in Barcelona. For this reason, the scientist has just obtained the grantInternational Rising Talent of the L’Oréal-UNESCO programFor Women in Science.
With this award, she has been selected as one of the 15 young researchersmost promising in the world. “I am very happy because the scientific career is quite hard and many times we do not see our work recognized. This is a motivation to continue ”, he tells SINC.
Recognition givesvisibility not only to his work, but also to the problem of plastic pollution in the sea. "In addition, it creates awareness in society," he emphasizes.
Millions of tons of plastics drift at sea. What actually happens once they reach the oceans?
Plastic is not pure, it has additives, and when it is in contact with water it begins to release these compounds. Even with degradation, monomer - a simple molecule - is released from the plastic, which forms the polymers. In an article we published inNature Communications We show that 23,600 tons of dissolved organic carbon are released each year from plastic entering the sea.
What happens next
We saw that there are marine bacteria that consume it, and that makes them reproduce faster. Now we want to find out what bacteria they are to know if they could be used in the future or could give us a clue towards a degradation pathway.
What environmental implications does the release of this organic carbon have?
It is altering the marine ecosystem. Until now, the effects of plastic were seen in larger animals, which were trapped in them or ingested them and had their stomachs full of plastic. But nothing was known about how it affects the lowest part of the food chain, microorganisms. Bacteria, in particular. For now, we have seen that they do suffer an alteration, but we still do not know the magnitude. More studies are needed to know the global implication.
What hypotheses exist so far?
The release of tons of carbon each year could contribute to the organic carbon pool already in the ocean. But what effects this would have on the carbon cycle remains to be studied.
What global consequences could there be in this case?
Overall, I still don't dare to say that the contribution is significant. However, from the experiments we have done, compared to the amount of organic carbon that is already in the sea - about 700 gigatons - these tons generated by plastic are still a small number. But they can be important on the surface, more polluted, because it is where the floating plastic is and where the sunlight hits it that causes it to photodegrade faster. 10% of the carbon found in that area could come from plastic. In this way it could contribute on a small scale.
Any type of plastic that falls into the sea is susceptible to releasing this compound, right?
Yes, we have done experiments with all kinds of plastics and they all release carbon. But some are more exposed to sunlight than others, which is the factor that contributes the most to degradation. Those on the surface receive that sunlight. Then there are those that sink, that no longer receive light and degrade much more slowly. Temperatures in the deep ocean are also much colder.
The use of plastic exploded in the middle of the last century. What elements are the most polluting?
It mostly started with single-use plastic, not just mass production. In the beach cleanings that are carried out, they are mainly of this type. This has greatly increased pollution because it is a plastic that is used for a few minutes and then thrown away and lasts for years in the environment.
Would it be possible to return to the state of the oceans before the existence of plastics?
If we take the right measures, everything returns to a balance. I think that this could be achieved, although the plastic that is already in the sea will remain there. In the end it will end up sedimentation at the bottom and will be buried or inside the animals. But it would be the end if we stop throwing plastic into the sea. 80% of the plastic that reaches the sea comes from the land, rivers, water treatment plants, etc. This is a measure that is in our power to stop.
How can we really stop it?
Reducing the manufacture of single-use plastic, which is expendable in most cases. You can also prevent the arrival of waste into the sea by putting adequate systems. In Barcelona, for example, every time it rains, the sewage system becomes saturated and waste passes into the sea without a filter. With the storm Gloria, the beaches were full of plastics and other debris that it is not understood how people can flush the toilet. Infrastructure could be improved to prevent plastic from reaching the sea.
What mechanisms could be implemented?
The plastic that is already in the sea is very difficult to treat, but degradation mechanisms could be put in place before it reaches the water in the waste plants. Furthermore, we do not know the magnitude of the problem either because of all the plastic that enters the sea, only 1% has been accounted for. 99% of the plastic that roams the oceans is lost. We do not know if it is sunk or if it slips through the nets when trying to catch it. We do not even know how small the plastic reaches once it is fragmented into pieces or where it is (in the water column, sedimenting or so small that we cannot measure it).