Photodegradation modifies microplastic effects on soil properties and plant performance

Microplastics in soil affect plant-soil systems depending on their shape and polymer type. However, previous research has not yet considered the effects of degraded plastics, which are the plastic materials actually present in the environment. We selected 8 microplastics representing different shapes (fibers, films and foams) and polymer types, and exposed them to UV-C degradation. Each microplastic was mixed with soil at a concentration of 0.4% (w/w). The phytometer Daucus carota grew in each pot. At harvest, soil properties and plant biomass were measured.
Photodegradation altered microplastics physical and chemical properties, impacting plant-soil systems. Microplastics degradation effects on plant and soil were observed with fibers and foams, but there were negligible effects with films. The latter could be explained by the polymer structure of films and manufacturer’s additives, potentially delaying their degradation.
Degraded fibers increased soil respiration more than their non-d...