麻豆淫院

Microplastics and nanoplastics are not only polluting our oceans, rivers and fields, but also our forests, according to geoscientists at TU Darmstadt. Their research is in Communications Earth & Environment.

According to the new study, harmful microplastics are not only stored in agricultural and urban soils, but also in forests. The majority of the tiny plastic particles enter the forests from the air and accumulate in the forest soil.

"The microplastics from the atmosphere initially settle on the leaves of the tree crowns, which scientists refer to as the 'comb-out effect,'" explains lead author Dr. Collin J. Weber from the Institute of Applied Geosciences at TU Darmstadt. "Then, in deciduous forests, the particles are transported to the forest soil by rain or the autumn leaf fall, for example."

There, leaf decomposition plays a central role in storing pollutants in the forest soil, as the authors further discovered. Although the highest levels of microplastics were found in the upper, only slightly decomposed leaf litter layers, large quantities of plastic particles are stored in the deeper soil layers. This can be attributed to leaf decomposition itself, but also to other transport processes such as organisms involved in decomposition.

For the survey, the research team from the Department of Soil Mineralogy and Soil Chemistry took samples at four forest sites east of Darmstadt in Germany. Using a newly developed and adapted analytical method, the scientists were able to measure the microplastic content in soil samples, fallen leaves and atmospheric deposition (the transport of substances from Earth's atmosphere to Earth's surface) and analyze it chemically using spectroscopic methods. They also produced a model estimate of atmospheric inputs since the 1950s in order to determine their contribution to total storage in forest soils.

"Our results indicate that microplastics in forest soils originate primarily from atmospheric deposition and from leaves falling to the ground, known as litterfall. Other sources, on the other hand, have only a minor influence," explains Dr. Weber. "We conclude that forests are good indicators of atmospheric microplastic pollution and that a high concentration of microplastics in forest soils indicates a high diffuse input鈥攁s opposed to direct input such as from fertilizers in agriculture鈥攐f particles from the air into these ecosystems."

The study is the first to demonstrate the pollution of forests with microplastics and the direct link between atmospheric inputs and the storage of microplastics in forest soil, as these issues had not previously been scientifically investigated. The results provide an important basis for assessing the environmental risks posed by microplastics in the air and soil.

"Forests are already threatened by climate change, and our findings suggest that microplastics could now pose an additional threat to forest ecosystems," says Dr. Weber. The findings may also be relevant for assessing health risks, as they highlight the global transport of microplastics in the air and thus also in the air we breathe.