Effects of disposable face mask microplastics on soil properties and microbial communities

Improper disposal of disposable face masks (DFMs), which are used as a fundamental measure to limit the spread of pandemics, can lead to the release of microplastics (MPs) into the soil. However, limited data exist regarding their impacts on soil physicochemical properties, as well as the composition and structure of microbial communities. In this study, we conducted a 92-day soil microcosm experiment with added MP DFMs to investigate the effects of these additions on the physicochemical properties and microbial communities of agricultural soils. Our findings demonstrated that a 5 % addition of MP DFMs decreased the bulk density (BD), mean weight diameter (MWD), and cation exchange capacity (CEC) while increasing pH, dissolved organic carbon (DOC), and total organic carbon (TOC) content. No significant changes were detected in the alpha diversity of the bacterial or fungal communities. However, at the 5 % MP DFM addition level, there was an increase in the abundance of Gp6, Rhabdothermincola, and Metacordyceps bacteria, in addition to a decrease in Sphingomonas abundance. Furthermore, an increase in the abundance of phototrophic bacteria, as well as ammonification- and sulfate-respiring bacteria, at the 5 % MP DFM addition level may accelerate carbon transformation processes, NH4+ accumulation, and SO4 2-consumption within the soil. These results provide valuable insights into the impact of MP DFMs on soil health while also offering a scientific foundation for effective DFM management.