Plant Biology Blog

Microplastics harm water plants

By Matevz Likar

November 17, 2017

Microplastics are small plastic particles less than 5 mm in diameter that can be found in the environment. Microplastics can be classified with the regard to the origin as primary and secondary microplastics. Primary microplastics are manufactured and are a direct result of human material and product use, whereas secondary microplastics are microscopic plastic fragments derived from the breakdown of larger plastic debris.

Primary microplastics

These are particles of plastics that are purposefully manufactured to be microscopic. They are usually used in facial cleansers and cosmetics, but are also used in air blasting technology. Microplastic particles are used as coarse parts in exfoliating hand cleansers and facial scrubs. A single cleansing product can contain as many as 360,000 microbeads.

Primary microplastics are also used in air blasting technology. This process involves blasting acrylic, melamine or polyester microplastic scrubbers at different surfaces to remove eg. rust and paint. These scrubbers are used repeatedly until they diminish in size and their cutting power is lost, therefore they often become contaminated with heavy metals such as cadmium, chromium, and lead.

Secondary microplastics

Secondary microplastics are microscopic plastic fragments derived from the breakdown of larger plastic debris. It is considered that microplastics might further degrade to be smaller in size, although the smallest microparticle reportedly detected in the oceans at present is 1.6 micrometres in diameter.

Environmental problems

Microplastics in the aquatic environments is today recognized as a serious, emerging global environmental issue. There already exists scientific evidence of sea pollution with microplastics (Law and Thompson 2014), with negative effects for marine animals (Wright et al. 2014). Furthermore, they also contaminate the fresh water ecosystems (Eerkes-Medrano et al. 2015), where they pose danger to animals and plants inhabiting these ecosystems. Among others, Slovenian researchers (Kalčíková et al. 2017; https://doi.org/10.1016/j.envpol.2017.07.050) demonstrated that microbeads significantly affected the root growth of duckweed (Lemna minor), a freshwater floating plant, by mechanical blocking. Sharp particles of the microplastics also reduced the viability of root cells. They concluded that microbeads from cosmetic products can have significant negative impact on floating plants in freshwater ecosystems.

 

microplastics
Graphical abstract depicting the experiment on Lemna minor (Kalčíková et al. 2017, Environmental Pollution, Elsevier.

Beat the microbeads

Many beauty brands have already stopped using microplastics or committed to do so, but until a blanket ban comes into force, you can check by yourself the cosmetic products in order to avoid microplastics.

If you’re unsure, check the label and avoid products containing polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polytetrafluoroethylene (PTFE) and nylon.

Beat the Bead campaign has a free smartphone app that scans a product’s barcode for plastics. You can also help and add new products to their database.

References

Eerkes-Medrano, D., Thompson, R. C. and Aldridge, D. C. (2015) Microplastics in fresh water systems: A review of the emerging threats, identification ofknowledge gaps and prioritisation of research needs. Water Research 75,63-82. http://dx.doi.org/10.1016/j.watres.2015.02.012

Kalčíková G., Žgajnar Gotvajn A., Kladnik A., Jemec A. (2017) Impact of polyethylene microbeads on the floating freshwater plant duckweed Lemna minor. Environmental Pollution 230, 1108-1115.
https://doi.org/10.1016/j.envpol.2017.07.050

Law, K.L. and Thompson R.C. (2014) Microplastics in the seas. Science, 345, 144-145.  http://dx.doi.org/10.1126/science.1254065

Wright, S.L., Rowe, D. Thompson, R.C. and Galloway T.S. (2014) Microplastic ingestion decreases energy reserves in marine worms. Current Biology 23, R1031-R1033, http://dx.doi.org/10.1016/j.cub.2013.10.068

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