German scientists have conducted the first investigation into the physical and biological effects of microplastic particles on the soil and its microbes.
The research provided the first experimental evidence that microplastics can change the biophysical conditions of soil as well as the functional activity of microbes. However, the team say that more studies are needed to show whether, and if so, how plastics – as anthropogenic, or human-induced – stressors – have a long-term effect on the ecosystem of the Earth.
Professor Matthias C. Rillig, one of the leaders of the work published in the latest issue of Environmental Science & Technology, said: “It might be too early to fully elaborate on the mechanism driving the microbial responses and to predict its consequences, but the fact is that microbes are perceiving the environmental change initiated by microplastics pollution and responded to it.”
In the experiments soil was contaminated with four different types of microplastics in increasing concentrations. The scientists incubated these soil samples under natural conditions for five weeks in an experimental garden at the Freie Universität in Berlin. They fond plastic particles, especially polyester fibers, exerted an influence on fundamental structural properties of the soil and its interaction with water. The soil bulk density and the interaction of those particles in forming aggregates changed when microplastics were present in the soil. It was also seen that plastic particles changed the size of pore space in the soil and influenced how much water the soil could absorb. The microorganisms in the soil samples were thus forced to change in response to the new environmental conditions.
The authors point out that this is the first study of its kind. Therefore, it is not yet clear whether these changes will have a long-term negative impact on the soil and its ecosystems.