An overview of the occurrence, characteristics, carrier role, and ecotoxicity of aged MPs in the terrestrial environment

Aged microplastics (MPs) are widely distributed in soil environments and pose significant ecological risks. This study presents a bibliometric review of research on aged MPs in soil using CiteSpace software, the results indicate that although China contributes the highest number of publications in the metrology of aged MPs, but the academic impact of these studies remains comparatively lower, coupled with insufficient international institutional collaboration. This review special emphasis is placed on elucidating the important roles of extracellular polymeric substances (EPS), oxygen-containing functional groups, hydrophobic interactions, coordination bonds, biofilm effects, and aging mechanisms in the co-migration behavior of MP-pollutant complexes within complex soil systems. It summarizes how exposure to aged MPs exacerbates toxicity in organisms by inducing oxidative stress, DNA damage, metabolic interference, and gut microbiota disruption, as well as by accelerating additive release and influencing the environmental degradation behavior of co-occurring pollutants. Notably, the co-migration of aged MP-pollutant complexes in soil can alter the bioavailability of pollutants, with adsorption efficiency being jointly influenced by the intrinsic properties of MPs and environmental factors. Significant gaps remain in current research regarding contamination assessment methodologies, real-world exposure data, and long-term health effects, underscoring the urgent need for standardized research frameworks and further investigation.