Impact of ZnO nanoparticles on soil lead bioavailability and microbial properties

In the present study, we investigated the responses of microbial respiration and community structure, enzyme activity and DTPA-extractable Pb within 60 days of incubation in soils treated with Pb and nano-ZnO. The results showed that when the concentration of nano-ZnO exceeded 10 mg/kg, the concentration of DTPA-extractable Pb significantly decreased by 10.6%-21.3% on the 60th day of the experiment. The addition of nano-ZnO decreased the Pb-contaminated soil pH from 6.18 to 6.08 at 7 days, which is part of the reason for the β-glucosidase activity change. Ten mg/kg nano-ZnO significantly reduced the qCO₂ value, which represented the microbial energy demand for the conversion of carbon sources into biomass. Nano-ZnO improved the microbial diversity and richness of some metal-tolerant bacteria at 60 days. The findings provide deeper insight into the responses of soil microbes and Pb bioavailability in the presence of nano-ZnO particles.