Effects of polystyrene nanoparticles on soil microbiota

The increasing production of nanoplastic and the fragmentation of microplastics into smaller particles pause a plausible yet unclear hazard in the natural environment, such as soil. In this research the effects of polystyrene nanoparticles (PS NPs) on the activity and biomass of soil microbes were investigated. Soil samples were spiked with environmentally relevant concentrations of 0 (control), 10, 100 and 1000 µg PS NPs kg-1 dry soil, respectively. Ecotoxicological effects were assessed at 1, 14, and 28 days of the incubation periods. The results showed a significant decrease in MBC in the PSNP-100 and PSNP-1000 treatments throughout the incubation period. Moreover, dehydrogenase activity and activities of enzymes involved in N-(leucine-aminopeptidase), P-(alkaline-phosphatase) and C-(β-glucosidase and cellobiohydrolase) cycles in the soil were significantly reduced at day 28 suggesting a broad and detrimental impact of PS NPs on soil microbiota and enzymes. Basal respiration and metabolic quotient increased with increasing PS NP application throughout the incubation period, this, coupled with decrease in MBC clearly indicate detrimental effects of PS NPs on soil microbes that possibly by diverted energy use from growth and reproduction to damage repair. The findings demonstrated for the first time the potential antimicrobial activity of PS NPs in soil, and this may serve as an important resource in environmental risk assessment of PS NPs in the soil environment.