Microplastics affect activity and spatial distribution of C, N, and P hydrolases in rice rhizosphere

Microplastics provide a new ecological niche for microorganisms, and the accumulation levels of microplastics (MPs) in terrestrial ecosystems are higher than those in marine ecosystems. Here, we applied the zymography to investigate how MPs — polyethylene [PE], and polyvinyl chloride [PVC]) at two levels (0.01% and 1% soil weight) impacted the spatial distribution of soil hydrolases, nutrient availability, and rice growth in paddy soil. MPs increased the above-ground biomass by 13.0%–15.5% and decreased the below-ground biomass by 8.0%–15.1%. Addition of 0.01% and 1% MPs reduced soil NH4+ content by 18.3%–63.2% and 52.2%–80.2%, respectively. The average activities of N- and P-hydrolases increased by 0.8%–4.8% and 1.9%–6.3% with addition of MPs, respectively. The nutrient uptake by rice plants and the enzyme activities in hotspots increased with MP content in soil. The accumulation of MPs in paddy soil could provide an ecological niche that facilitates microbial survival, alters the spatial distribution of soil hydrolases, and decreases nutrient availability.