Environment Tiny plastic particles reach the leaves of trees

Tiny plastic particles reach the leaves and needles of trees via the roots and disrupt photosynthesis. This was shown by researchers at ETH Zurich in an experiment.

After absorbing plastic particles, the trees no longer used part of the sunlight energy for photosynthesis, but dissipated it as heat. This is a typical stress reaction of trees, wrote the Swiss National Science Foundation (SNSF) in a press release on the study on Thursday. The SNSF funded the research project.

For their experiment, the researchers grew two hundred young trees, half wild service trees and half spruce trees. They placed their roots in nutrient-enriched water instead of soil. They added different concentrations of tiny plastic particles, known as nanoplastics, to the water.

After just a few weeks, the researchers discovered one to two milligrams of nanoplastics per gram of plant material in the roots. In the trunk and in the leaves and needles, it was around ten to a hundred times less.

Trees do not die as a result

Measurements showed that the effectiveness of photosynthesis in the service tree fell by a third within two weeks and by a tenth in the spruce within four weeks. However, the plastic particles had no effect on the growth of the trees. According to the researchers, this could also be due to the fact that the study was only conducted over a short period of time.

"Our study should not give the impression that trees could die as a result of nanoplastics," ETH researcher Denise Mitrano was quoted as saying in the press release. But it could be an additional stress factor.

SDA