Beyond abundance: A mechanistic ‘properties-to-behavior’ framework for microplastic fate, risk, and water security in aquatic ecosystems

Microplastics (MPs) are reactive particles whose size, morphology, and surface chemistry govern their mobility, persistence, and toxicity in aquatic ecosystems. However, existing monitoring and policy frameworks focus on quantitative analysis rather than mechanistic traits, which influences their abundance in the ecosystem. Compounding this issue, this review presents a properties-to-behavior framework that links physical (size, morphology, surface roughness), chemical (oxidation index, surface energy, zeta potential) and biological (biofilm colonization) properties to MP fate and ecotoxicological outcomes. A systematic literature synthesis of 930 peer-reviewed studies using PSALSAR methodology was conducted from 2000 to 2024. It identifies property-driven controls on transport, contaminant sorption and trophic transfer, and highlights methodological gaps that hinder comparability. Thus, in this review, we present, a conceptual reactivity index, using literature-derived values for standardized observation and targeted interventions based on composite morphological, electrochemical, and biological studies. The proposed index, therefore, provides a foundation for future empirical calibration. The methodological framework guides MP research beyond the conventional descriptive abundance measures, moving from abundance-oriented perception to property-based risk assessment and water management with a sustainability focus.