It isn’t just marine wildlife that suffers from the plight of plastic pollution. New research has highlighted that nanoplastics can be absorbed and internalized by land-dwelling plants through their roots.
While it's still unclear whether this affects things like crop yields and food safety, the uptake of nanoplastic particles was shown to reduce the biomass of the plant, indicating the health of the plant may be compromised.
Reported in the journal Nature Nanotechnology, researchers led by Shandong University in China and the University of Massachusetts Amherst planted Arabidopsis thaliana, a much-studied weed also known as thale cress, in soil that contained minuscule pieces of plastics smaller than 100 nanometres and compared it to plants grown in normal soil.
After seven weeks of growth, the plants that were exposed to nanoplastics were found to be shorter in height and lower in biomass.
"Nanoplastics reduced the total biomass of model plants," Baoshan Xing from the University of Massachusetts Amherst said in a statement. "They were smaller and the roots were much shorter. If you reduce the biomass, it's not good for the plant, yield is down and the nutritional value of crops may be compromised."
Before being placed in the soil, the nanoplastics were either positively or negatively charged, as well as given a fluorescent marking so the researchers could track their whereabouts. A number of analysis techniques were then used to show the nanoplastics had been taken up by the plants’ roots.
"We found that the positively charged particles were not taken up so much, but they are more harmful to the plant. We don't know exactly why, but it's likely that the positively charged nanoplastics interact more with water, nutrients, and roots, and triggered different sets of gene expression,” said Xing. “That needs to be explored further in crop plants in the environment. Until then, we don't know how it may affect crop yield and food crop safety."
It’s worth noting that nanoplastics are extremely small. The pieces used in this research were less than 100 nanometres, which is approximately 1,000 times smaller than the width of a human hair or about the size of some viruses. Although very hard to detect, these tiny nanoplastics are found abundantly in the environment as they are shed from larger pieces of plastic pollution.
This is the first study to look at the effect of nanoplastics on terrestrial plants, so there is still much to learn. Even on the wider subject of nanoplastics in general, not a huge amount is known, although increasing evidence is starting to show these microscopic particles are a major problem throughout the planet’s natural environments.
A study published in 2017 found that “nanoplastics” can accumulate in fish brains and potentially cause strange alterations in behavior that make the fish less likely to survive.