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Conservation Science for a Healthy Planet

Microplastics — an emerging threat to terrestrial ecosystems.

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These are polyacrylic fibers in soil. Credit: Anderson Abel de Souza Machado
  • Over 400 million tons of plastic are produced globally each year. It is estimated that one third of all plastic waste ends up in soils or freshwaters.
  • Terrestrial microplastic pollution is much higher than marine microplastic pollution — an estimate of four to 23 times more, depending on the environment.
  • When plastic particles break down, they gain new physical and chemical properties, increasing the risk that they will have a toxic effect on organisms
  • 80 to 90 per cent of the particles contained in sewage, such as from garment fibres, persist in the sludge. Sewage sludge is then often applied to fields as fertilizer, meaning that several thousand tons of microplastics end up in our soils each year.
  • The intake and uptake of small microplastics could turn out to be the new long-term stress factor for the environment.

February 5, 2018 Forschungsverbund Berlin read full ScienceDaily article here

Tiny plastic particles also present a threat to creatures on land and may have damaging effects similar or even more problematic than in our oceans. Researchers warn: the impact of microplastics in soils, sediments and the freshwaters could have a long-term negative effect on terrestrial ecosystems throughout the world.

Over 400 million tons of plastic are produced globally each year. It is estimated that one third of all plastic waste ends up in soils or freshwaters. Most of this plastic disintegrates into particles smaller than five millimetres, referred to as microplastics, and breaks down further into nanoparticles, which are less than 0.1 micrometre in size.

In fact, terrestrial microplastic pollution is much higher than marine microplastic pollution — an estimate of four to 23 times more, depending on the environment. Sewage, for example, is an important factor in the distribution of microplastics. In fact, 80 to 90 per cent of the particles contained in sewage, such as from garment fibres, persist in the sludge. Sewage sludge is then often applied to fields as fertilizer, meaning that several thousand tons of microplastics end up in our soils each year.

Some microplastics exhibit properties that might have direct damaging effects on ecosystems. For instance, the surfaces of tiny fragments of plastic may carry disease-causing organisms and act as a vector that transmits diseases in the environment. Microplastics can also interact with soil fauna, affecting their health and soil functions. Earthworms, for example, make their burrows differently when microplastics are present in the soil, affecting the earthworm’s fitness and the soil condition.Generally speaking, when plastic particles break down, they gain new physical and chemical properties, increasing the risk that they will have a toxic effect on organisms. And the more likely it is that toxic effects will occur, the larger the number of potentially affected species and ecological functions……..Humans also ingest microplastics via food: they have already been detected not only in fish and seafood, but also in salt, sugar and beer. It could be that the accumulation of plastics in terrestrial organisms is already common everywhere, the researchers speculate, even among those that do not “ingest” their food. For example, tiny fragments of plastic can be accumulated in yeasts and filamentous fungi.The intake and uptake of small microplastics could turn out to be the new long-term stress factor for the environment.

 

Anderson Abel de Souza Machado, Werner Kloas, Christiane Zarfl, Stefan Hempel, Matthias C. Rillig. Microplastics as an emerging threat to terrestrial ecosystems. Global Change Biology, 2018; DOI: 10.1111/gcb.14020
These are polyacrylic fibers in soil. Credit: Anderson Abel de Souza Machado
And another recent study:
Melanie Bläsing, Wulf Amelung. Plastics in soil: Analytical methods and possible sources. Science of the Total Environment. 2017
H I G H L I G H T S
• Analytical methods and possible input pathways of plastic in soil were discussed.
• Organic matter challenges plastic quantification in soil.
• Soil amendments and irrigation are likely major plastic sources in agricultural soils.
• Flooding, atmospheric input and littering can potentially pollute even remote soil.
• Leaching of small plastics from soil into groundwater cannot be excluded.

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