Comparative Study on the Environmental Behavior and Ecological Risks of Microplastics and Natural Particles

The widespread use of plastics has resulted in the accumulation of microplastics (MPs) as persistent contaminants across diverse ecosystems. Although extensive research has examined the prevalence and impacts of MPs, comparatively fewer studies have investigated their differences and interactions with natural particles (NPs). In this study, we systematically compared MPs and NPs by assessing their physicochemical properties, environmental behaviors, and ecological impacts. Our findings reveal both commonalities and significant distinctions between the two particle types. MPs exhibit heterogeneous chemical compositions that drive complex environmental interactions, whereas NPs generally possess more uniform compositions, leading to more predictable behaviors. Both particle types can adsorb and transport contaminants; however, NPs typically demonstrate stronger adsorption capacity due to their abundant functional groups, while MPs exhibit greater desorption potential, thereby posing a higher risk of pollutant re-release. NPs mainly settle through flocculation and gravitational processes, whereas MPs are influenced by density, morphology, and aging, factors that enhance their mobility and long-range transport. Ecotoxicity analysis indicates that, unlike NPs, which present relatively low chemical risks, MPs pose greater ecotoxicological threats owing to their complex compositions and potential for additive leaching. Overall, this study emphasizes that, despite certain parallels, MPs and NPs differ in fundamental ways that shape their environmental behaviors and ecological effects. These findings highlight the need to broaden current particulate matter frameworks to explicitly incorporate MPs, drawing on established approaches from NP research to advance understanding of their ecological roles and environmental risks.