Biofouling Promotes
Higher Concentration of Heavy
Metal on Disposable Face Masks than Microplastic Films and Particles
in Seawater: Mechanisms and Potential Ecological Risks
The insufficient control of waste associated with personal
protective
equipment (PPE) resulted in a large influx of disposable face masks
(DFMs) in marine environments. Herein, we investigated the biofilm
colonization on three types of polypropylene microplastics (MPs, i.e.,
DFMs, films, and particles) as well as the potential risks of MP-associated
heavy metals (HMs) in seawater. Compared to conventional MP particles
and films, DFMs were conducive to colonization by microorganisms and
minerals, resulting in the formation of a typical spatial network
biofilm structure. This triggered more HM adsorption by the biofilm-developed
DFMs through surface complexation with the organic components in the
biofilm. By BCR sequential extraction analysis, we found that organic
and mineral components comprised 70.2–85.6% and 14.4–29.8%
of the HM concentration in the biofilm-developed DFMs, respectively.
In an in vitro gastrointestinal tract model, biofilm-developed
DFMs had a much higher desorption capacity for HMs than MP particles
and films. Moreover, the ecological risk index of biofilm-developed
DFMs was significantly higher than that of biofilm-developed films
and particles. Considering the potential ecological risk of biofilm-developed
DFMs, we advocate that the reasonable recycling and environmentally
friendly treatment of PPE MP pollutants should be considered as a
bursting challenge for sustainable coastal development.