Tiny plastic particles reach the leaves and needles of trees via the roots and disrupt photosynthesis, researchers at federal technology institute ETH Zurich have discovered. +Get the most important news from Switzerland in your inbox After absorbing plastic particles, the trees no longer used part of the sunlight's 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 200 young trees, half of them torminalis and half spruce. 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. + Switzerland has plastic problem, say most Swiss After just a few weeks, the researchers discovered one to two milligrams of nanoplastics per gram of plant material in the roots.