Interaction of microplastics with metal(oid)s in aquatic environments: What is done so far?

Abstract

Microplastics (MPs) are being recognized as an emergent route of contaminants to aquatic environments, which initially attracted the research interest on their interactions with organic pollutants. Lately, a turning point of attention is evident, with more published studies reporting the presence of metal(oid)s in plastics. This review assembles the mechanisms occurring on microplastics surfaces that enhance sorption of hazardous elements (i.e., metals and metalloids) over environmental exposure. Reported findings of experimental studies are of major importance to understand the factors controlling the sorption/desorption of metal(oid)s to/from microplastics as much as determination of metal(oid)s in environmental plastics. Existence or formation of oxygen-containing functional groups and complexes from surface coatings strongly allow bond of metal(oid)s on reactive surfaces while sorption dynamics are strongly controlled by water chemistry parameters. Moreover, the present work evidences the potential impacts caused by metal(oid)s-MPs interactions to aquatic organisms, prioritizing the need of environmental realistic parameters to test. Bioaccumulation of metal(oid)s desorbed from ingested MPs prove the significant influence of these plastic particles in the bioavailability of pollutants to aquatic biota. In this way, this is a comprehensive manuscript committed to the estimation of the potential ecological risk of MPs to aquatic environments due to their association with metal(oid)s.