Can plants remove micro- and nanoplastics from the environment?

Plants can absorb micro- and nanoplastics in their stems and roots, raising concerns about how natural ecosystems cope when plastic particles invade.

However, a Danish-Chinese research team is proposing a new perspective: Why not use plants as an eco-friendly tool to collect and degrade plastic particles?

The concept is explored in a scientific article in the Eco-Environment and Health journal. The lead authors are from Hubei Key Laboratory of Wetland Evolution & Ecological Restoration in China, with contributions from the University of Southern Denmark ecotoxicologist Elvis Genbo Xu from the Department of Biology. The article is freely available online here. 

Global plastic production is staggering. So far, 9 billion tons have been produced, but only 9 percent has been recycled, the authors note.

The big question is, what happens to all the plastic we haven't recycled? Much of it has ended up in nature, breaking into smaller pieces over the years. Today, micro- and nanoplastics in the environment are widespread and serious problems because the particles can be absorbed and ingested by animals, plants, and humans.

- We believe plants can effectively supplement existing methods for removing plastic from nature. Many plants absorb or adsorb micro- and nanoparticles, but we need to identify the most effective ones to achieve the best results, says Elvis Genbo Xu.

The research team has studied various plants' ability to uptake micro- and nanoplastics. Their article reports that the fava bean (Vicia faba) can adsorb 100 nm nanoplastic particles via its roots within two days. Adsorption, a process where the particles adhere to the roots, should not be confused with absorption, which is when the particles are taken up into the plant.

Other plants like wheat and lettuce can also bind plastic particles to their roots or absorb them into their leaves or stems, according to the researchers' experiments.

Aquatic plants are of particular interest because they can remove plastic particles from the aquatic environment, where higher concentrations of plastic particles are often found, the researchers write.

The common water hyacinth (Eichhornia crassipes) has shown the ability to adsorb plastic particles, making it and other aquatic plants like duckweed (Lemna minor) suitable for use as filters to capture micro- and nanoplastics in wetlands.

- It would make sense to establish belts of plastic-absorbing plants in areas where nano- and microplastics are known to accumulate, such as along highways where large amounts of microplastics wear off from car tires. The belts could function as a filter, capturing plastic particles before they spread to the wider landscape or are washed into streams by rain, says Elvis Genbo Xu, adding:

- Similarly, strategic belts of aquatic plants could be placed in streams or rows of trees could capture plastic particles from upstream and the air.

Optimistic about aquatic environments

Xu emphasizes that getting plants to absorb micro- and nanoplastics is not enough to solve the global problem of plastic pollution. Micro- and nanoplastics are everywhere: in the air, in the water, and in the soil. No one can avoid them, as they are present in the air we breathe and the water we drink. Therefore, many different methods are needed to remove them before they pollute the environment. Bacteria, fungi, and microalgae can also be employed. Letting plants do part of the work is just one of many solutions.

Whether plants will become a widespread solution remains to be seen, but Elvis Genbo Xu is optimistic:

- Our lab experiments have been successful. I am optimistic that we can scale this up to remove particles from the environment—at least from aquatic environments, where aquatic plants have proven very effective.

Other researchers want to use jellyfish

At the Department of Biology, marine biologist and jellyfish researcher Jamileh Javidpour has investigated whether jellyfish could be used to remove micro- and nanoplastics from the aquatic environment.

Jellyfish produce slime, and in laboratory experiments, this slime has proven capable of removing up to 90 percent of nanoplastics in water from treatment plants.

- We’ve found that jellyfish slime is super effective at removing nano-sized plastic particles. It could be a part of the solution - I can imagine using dried jellyfish slime to create filers for washing machines, for example, says Javidpour.

Wenke Yuan, Elvis Genbo Xu, Soha Shabaka, Peng Chen, Yuyi Yang: The power of green: Harnessing phytoremediation to combat micro/nanoplastics.

https://www.sciencedirect.com/science/article/pii/S2772985024000292?via%3Dihub