Plastic: rivers and rivers are less polluted than expected

Plastic: rivers and rivers are less polluted than expected

Plastic leftovers are literally drowning our seas and rivers. It’s really rare to see some plastic waste abandoned around an aquatic environment. These plastics are the source of worrying pollution, and its full consequences are not yet known. For a long time, rivers have been presented as the main source of plastic pollution. It is estimated that they drain several million tons of plastic into our oceans each year due to mismanagement of terrestrial waste. However, estimates of plastic pollution in rivers and streams made previously would be tens or even hundreds of times higher than the amount of plastic floating on the ocean surface. An unanswered question remains: Where does excess plastic from rivers end up? Are there plastic “basins” in the ocean? Or are the estimates wrong?

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at A study published by ScienceFrench and Spanish researchers have shown that estimates of the flow of plastics in rivers and streams are exaggerated. These numbers will be 100 to 1,000 times less significant than what has been announced. This would explain in particular the important differences previously observed between the number of plastics found in rivers and oceans. Overestimating the flow of plastic does not mean that this pollution is less problematic. Scientists in the study also found that plastics stayed on the ocean surface for much longer than expected, exacerbating the effects of plastic pollution on ecosystems.

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Estimation errors

Previous estimates indicate that rivers are the main source of plastic release into the oceans. Microplastics floating in the oceans – between 10 and 100 tons – represent only a small part of the plastic pollution in the river, which can be calculated in millions of tons, hence the hypothesis of plastic “basins”. Today, this interpretation and the numbers are disputed by the study authors. For them, previous estimates contained significant methodological errors at the level of particle flows as well as at the level of the total mass of microplastics. Errors occurred in particular due to systematic overestimation of the average weight of microplastics in waterways, inconsistent data integration and erroneous estimates between microplastic fluxes and the number of bad plastic waste. And so the search for mysterious plastic pits ended thanks to the research team’s modifications.

Be warned, the orders of magnitude placed by the study scientists are also only estimates. Until proven otherwise, these estimates reveal only a mathematical truth.

In this study, the scientists also found that the average lifespan of microplastics at the surface of the oceans was much longer than expected. While plastics were previously thought to float for a few days, it turns out they can stay on the surface for a few years.

A microplastic particle seen under a microscope. © CEFREM / UPVD

Microplastics and toxic particles

The main environmental risk of plastic is its decomposition. When plastic is found in an aqueous environment for some time, it breaks down into small particles, especially under the influence of currents, friction with rocks or sand and ultraviolet rays. Plastic particles can also come from industrial waste or cosmetics. Microplastics are plastic particles less than 5 mm in size. The problem with fine particles is that they are ubiquitous in the environment. Scientists on the schooner Tara note that all water samples taken from the nine European rivers contain microplastics.

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The harm of microplastics is well known. It is a real “polluting sponge”, in which many toxic products accumulate on the surface of waterways and oceans. Animals absorbing microplastics are harmful to their bodies. Microplastics can be endocrine disruptors and interfere with reproduction.

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The new global challenge against plastic pollution

Plastic pollution affects all ocean environments. It not only comes from developing countries that often have inadequate waste management policy, it can also come from countries with well-established waste management systems. According to Professor Wolfgang Ludwig, CEFREM Laboratory Director and co-author of the study: “The only way to have any chance of winning in the fight against plastic pollution is to target the sources where microplastic waste is generated. We must act at the human level. We need to change our consumption habits, and manage Better waste our time and do it on a global scale, so the solution seems more political than scientific.

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