Microplastics Can Change Soil Properties and Affect Plant Performance

Microplastics
can affect biophysical properties of the soil. However,
little is known about the cascade of events in fundamental levels
of terrestrial ecosystems, i.e., starting with the changes in soil
abiotic properties and propagating across the various components of
soil–plant interactions, including soil microbial communities
and plant traits. We investigated here the effects of six different
microplastics (polyester fibers, polyamide beads, and four fragment
types: polyethylene, polyester terephthalate, polypropylene, and polystyrene)
on a broad suite of proxies for soil health and performance of spring
onion (Allium fistulosum). Significant
changes were observed in plant biomass, tissue elemental composition,
root traits, and soil microbial activities. These plant and soil responses
to microplastic exposure were used to propose a causal model for the
mechanism of the effects. Impacts were dependent on particle type,
i.e., microplastics with a shape similar to other natural soil particles
elicited smaller differences from control. Changes in soil structure
and water dynamics may explain the observed results in which polyester
fibers and polyamide beads triggered the most pronounced impacts on
plant traits and function. The findings reported here imply that the
pervasive microplastic contamination in soil may have consequences
for plant performance and thus for agroecosystems and terrestrial
biodiversity.