Sean Gibbs, “Characterization of Dissolved Organic Matter of Disposable Face Masks during Photochemical Weathering in Freshwater Environments”
Mentor: Laodong Guo, Freshwater Sciences
Poster #72
The astounding surge in the use of disposable face masks has exacerbated the adverse consequences associated with their improper disposal, posting a significant threat to the environment. Despite growing concerns, there remains a lack of comprehensive understanding of the biological and chemical reactivities of disposable face masks (FMs) and their ultimate fate in aquatic ecosystems. In this study, we investigated the photochemical reactivity of KN95 FMs (5-ply) and their degradation products. The FMs were split into five layers, consisting of outer and inner layers of non-woven fabric (1st and 5th, hydrophobic), a layer of hot air cotton (2nd, hydrophilic) and two layers of melt-blown fabric (3rd and 4th, hydrophobic), for photochemical degradation. Time-series samples were collected for optical and chemical characterization of dissolved organic matter (DOM), including dissolved organic carbon (DOC), chromophoric and fluorescence DOM (CDOM and FDOM), and surface properties. All layers show significant extent of degradation, with DOC exhibiting exponential increase following UV-irradiation exposure, and notably the 2nd layer released the highest DOC. Similarly, the 2nd layer released more CDOM during photodegradation, with the sequence 2nd ly>1st ly>5th ly>4th ly≥3rd ly. The fluorescence intensities of FMs-released DOM consistently increased during the photochemical degradation of KN95, demonstrating a continuous DOM production from each layer. The results from fluorescence EEMs are consistent with those observed for both DOC and CDOM. In terms of the quality of FMs-released DOM, there was a concurrent decrease in both aromaticity (SUVA254) and apparent DOM-molecular weight (based on S275-295) under UV-irradiation, suggesting simultaneous DOM production and degradation. Disposable face masks are a fundamental part of the collaborative effort to safeguard public health, particularly during pandemics. Further studies are needed to quantify the environmental impacts of degradation products of FMs.