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Studies on the effect of microplastics on the adsorption and migration of Phenanthrene in river sediment
Summary
Researchers investigated how polyethylene and polyvinyl chloride microplastics affect the adsorption and migration of phenanthrene in river sediments using batch and column experiments. Results showed that PE microplastics enhanced sediment adsorption capacity for phenanthrene relative to controls while PVC reduced it, attributable to structural differences between elastic PE and glassy PVC, with humic acid and pH further modulating adsorption behaviour.
Microplastics (MPs) in ecosystems have garnered attention, yet their effects on the environmental behavior of organic pollutants in river sediments remain poorly understood. This study investigated how polyethylene (PE) and polyvinyl chloride (PVC) MPs influence the adsorption and migration of Phenanthrene (Phe) in sediments via batch and column experiments. Results revealed that sediment adsorption capacity for Phe followed: sediment containing 2% PE (120.27 μg g) > sediment without MPs (111.93 μg g) > sediment containing 2% PVC (104.79 μg g), attributed to PE's looser, more elastic structure with larger free volume compared to glassy PVC. Humic acid (HA) inhibited Phe adsorption by occupying sites and solubilizing all sediments. pH effects showed a non-linear trend due to MPs' zero-charge points, with adsorption increasing and decreasing as pH rose. Migration was influenced by Phe's initial concentration, MP type/proportion, and HA levels: higher initial Phe increased maximum penetration rate from 0.36 to 0.44, enhancing mobility, while migration ability ranked: sediment without MPs > sediment containing PE > sediment containing PVC. These findings highlight that PE increased phenanthrene adsorption by 26% compared to PVC, enhancing pollutant retention in sediments and posing risks to downstream ecosystems. Our study provides critical insights into the role of polymer properties and environmental factors in regulating contaminant behavior, advancing the understanding of MPs as vectors for hydrophobic organic pollutants in aquatic environments, and bridging the knowledge gap between microplastic interactions and organic pollutant behavior in river sediments.