Microplastics in agricultural soils: A comprehensive perspective on occurrence, environmental behaviors and effects

Abstract

Microplastics (MPs) have been widely detected in agricultural soils, raising concerns regarding their potential impact on agroecosystems. However, a comprehensive understanding of the environmental fate of MPs in agroecosystems is lacking. This work aimed to offer a comprehensive analysis and synthesis of the distribution characteristics of MPs in agricultural soils, as well as their environmental behaviors and effects. To this end, a meta-analysis was initially performed to elucidate the distribution characteristics of MPs in agricultural soils worldwide. Subsequently, an in-depth analysis and discussion linked various potential aging and degradation pathways of MPs in surface and subsurface agricultural soils under natural conditions, offering a holistic perspective to explain the widespread detection of conventional inert MPs in agricultural soils. Moreover, a three-stage model encompassing partition, diffusion (external and internal), and adsorption, coupled with a tripartite binding model involving MPs, microbial detritus, and dissolved organic matter carrying pollutants, was introduced to elucidate the complex sorption mechanisms of pollutants on MPs in soil environments. Additionally, the mechanisms by which MPs affect soil physicochemical properties, biota, and carbon dioxide emissions were systematically examined and discussed to elucidate the effect of MPs on agroecosystems within a relatively comprehensive framework. Finally, research challenges and directions for the fate of MPs in agricultural soil environments were proposed. By offering a holistic review, this study significantly deepens and broadens the understanding of MPs' lifecycle in agricultural soils, laying the groundwork for further research and policy advancements in this domain.