Polylactide Microplastics Influence Carbon, Nitrogen and Phosphorus Cycles in Dry Sandy Soils Through Mediated Physical Properties and Enzyme Activities

Biodegradable plastic‐derived microplastic particles generated during degradation processes have been widely detected in agricultural soils, raising increasing concerns regarding their potential impacts on soil ecological environments. However, systematic studies investigating the effects of biodegradable microplastics on aeolian sandy soil ecosystems in arid desert regions remain limited. Therefore, this study investigated the effects of polylactic acid microplastics (PLA MPs) at different addition levels (0%, 0.1%, 0.5%, 1% and 1.5%) on soil properties, nutrient dynamics and enzyme activities in aeolian sandy soils by integrating correlation analysis, redundancy analysis (RDA) and partial least squares path modelling (PLS‐PM). The results demonstrated that: (1) the effects of PLA MPs on the soil ecosystem were jointly regulated by microplastic concentration and aging duration; (2) with increasing PLA MPs concentrations and aging duration, the physicochemical properties of aeolian sandy soils (e.g., SMC, SBD and EC), enzyme activities (e.g., S‐UE and S‐SC), and nutrient contents exhibited significant nonlinear variations; (3) PLA MPs could regulate soil enzyme activities by altering key soil properties, including soil structure, moisture status and electrical conductivity, thereby further disturbing the transformation and supply capacity of carbon, nitrogen and other nutrients; additionally, PLA MPs indirectly affected soil stoichiometric characteristics through changes in soil enzyme activities and nutrient availability, ultimately influencing soil nutrient cycling and overall ecosystem functioning. These findings highlight the critical role of biodegradable microplastics in regulating nutrient cycling in aeolian sandy soils and provide a scientific basis for desertification control and ecosystem function restoration in arid desert regions.