Visualization and assessment of the microbial colonization process of disposable surgical masks in a typical natural aquatic environment

Currently, there is little knowledge about the microbial colonization process in disposable surgical mask waste, as well as a lack of quantitative investigation on the behaviors and potential risks of biofilm-colonized disposable surgical masks discarded into the environment. Therefore, we performed an exposure time-series experiment to investigate the microbial colonization process in disposable surgical mask waste exposed to multiple sites along the Nanhu Pond in Beijing (China). Our results showed that disposable surgical masks can be rapidly colonized by microorganisms with evidence of formation of complex and heterogeneous biofilms after 14 days of exposure to the pond water. The microorganisms in mask biofilms had strong activity and vitality. In general, the middle layer showed a higher microbial colonization capacity, while in the outer and inner layers, larger-size microbial aggregates are more abundant. Additionally, the chemical structure and component of disposable surgical masks did not change during the 35 day exposure to the natural water environment. Our study provides insightful information about the biofilm formation process of disposable surgical masks and advances the knowledge of the fate of biofilm-colonized disposable surgical masks in natural water environments.