Microplastics are a big and growing part of global pollution, which has aroused increasing concern in recent years because of their large amount, wide distribution, and adverse effects. Microplastics can sorb various pollutants from aquatic environments and act as vectors of pollutants. Most studies mainly focused on the virgin microplastics. However, microplastics in environments can be easily colonized by microorganisms, and form biofilm, which will influence the behaviors and potential risks of microplastics. The formation of biofilm on microplastics and its effects on their properties have been studied before, but their sorption and transport behaviors, and potential risks for pollutants' transfer have not been reviewed. In this paper, the role of biofilm-developed microplastics as vectors of pollutants was thoroughly analyzed and summarized. First, the formation of biofilm on microplastics, the compositions of microorganisms in biofilm, the influencing factors, and the property changes of microplastics after biofilm attachment are thoroughly reviewed. Second, the sorption of pollutants onto biofilm-developed microplastics is discussed. Third, the role of biofilm-developed microplastics as vector of pollutants are analyzed. We concluded that microplastics could provide unique substrates for microorganisms. Biofilm-developed microplastics can sorb more pollutants than the virgin ones, then act as vectors to introduce pollutants and attached microorganisms to aquatic environments and to organisms.
Keywords: biofilm; microplastics; pollutants; vector.