Polyvinyl Chloride and Polypropylene Microplastics Impact Soil Total Antioxidant Capacity and Exoenzyme Secretions

Microplastics (MPs), notably polyvinyl chloride (PVC) and polypropylene (PP), are major pollutants in terrestrial and aquatic ecosystems. PVC and PP are the most used polymers for manufacturing plastic goods and therefore constitute bulk of plastic debris which are the major sources of MPs. This study examines the impact of PVC and PP MPs on soil total antioxidant capacity (TAC) and microbial exoenzyme activities. A 0.25% (w/w) MP addition significantly reduced soil TAC and the activities of amylase, invertase, and dehydrogenase over 72 h, while cellulase activity increased. The effects varied by MP type, with molecular docking revealing stronger MP binding affinities to exoenzymes for PP than PVC, particularly with cellulase. The findings indicate MPs reduce soil antioxidants and most exoenzyme activities, except for cellulase.