Earth scientists from the Technical University of Darmstadt in Germany recently published the latest research in the journal "Earth & Environment": Not only are oceans, rivers and farmland polluted by microplastics and nanoplastics, but even forests far away from cities are not immune. Forests store microplastics brought in from the air, and these particles accumulate in the soil through rainfall, defoliation and decomposition processes.
Research leader Dr. Collin J. Weber from the Institute of Applied Geosciences at TU Darmstadt said that most microplastic particles first come from the air and are first deposited on the surface of the leaves of the tree crown. This phenomenon is called the "combing effect" by scientists. These particles then enter forest soil through rainfall or fall leaf fall.
Once in the soil, the decomposition of leaf litter becomes a key factor in capturing microplastics. The team found that the highest concentrations of microplastics are found in the surface leaf litter that has just begun to decompose; at the same time, larger amounts of microplastics can also be carried into deeper soil due to the decomposition of organic matter and soil biological activity.
This research team collected soil samples at four forest sampling points east of Darmstadt, Germany, and accurately measured the concentration of microplastics in soil, leaf litter, and atmospheric deposition through optimized analysis technology. Chemical analysis of the samples was performed using spectroscopic methods, combined with modeling methods, to estimate the input trend of microplastics in the atmosphere since the 1950s.
The results show that microplastics in forest soil mainly come from atmospheric deposition and fallen leaves. Compared with the direct input of chemical fertilizers common in farmland, the forest shows "air diffusion input". Dr. Weber said that this is the first scientific proof that the deposition of atmospheric microplastics directly causes forest soil pollution, laying the foundation for assessing the ecological and environmental risks caused by microplastics.
Researchers point out that climate change has put tremendous pressure on forests, and microplastic pollution may become another new threat to ecosystems. In addition, microplastics can be spread through global atmospheric circulation, and the respiratory health risks of residents in various places also need to be paid attention to.
Compiled from /ScitechDaily