Arsenic interaction with microplastics: Implications for soil-water-food nexus

Microplastics (MPs) interact with toxic trace elements available in the surrounding environment (water and soil). This review is focused on the possible impacts of As-bound MPs on soil, water, and food nexus. Arsenic sorption capacities of polystyrene and polytetrafluoroethylene MPs were 1.12 mg/g and 1.05 mg/g, respectively. Sorption capacities depend on MPs size, surface properties, acidity or basicity of surrounding water or soil, temperature, and the presence or absence of organic matter. Arsenic bioavailability in soil, water, and inside organisms changed when present with MPs. Coexistence of MPs and As negatively influences plant growth, photosynthesis rate, and seed germination. However, the presence of both MPs and As has been found to decrease the intake of As by rice seedlings owing to the competition between MPs and As for adsorption sites on roots. Furthermore, the existence of both MPs and As shifts the bacterial community succession pattern via the enrichment of some microbes (Proteobacteria and Bacteroidetes) and inhibition of certain species (Chloroflexi and Verrucomicrobia); however, the exact mechanisms are not known yet. Although research on the combined impact of As and MPs is limited, the addition of MPs to the As contaminated environment may amplify the adverse impact of As on the soil and water food nexus. Hence, more attention should be given to understanding the As impact on soil and aquatic food nexus in presence of MPs for developing feasible solutions to resolve toxicity issues related to the co-occurrence of MPs and As.