Effect of Microplastics on the Environmental Fate of Atrazine in Soil: Adsorption and Dissipation

The accumulation of microplastics (MPs) in agricultural soils and atrazine in agricultural soils creates compound pollution that severely threatens soil health. The present study aimed to evaluate the effect of polyethylene (PE), polyvinyl chloride (PVC), and polybutylene succinate (PBS) on the adsorption and degradation of atrazine in yellow-brown and black soil. Batch adsorption kinetic and isotherm experiments were conducted in two distinct soils amended with MPs. A 90-day degradation experiment was performed to monitor atrazine persistence and the activities of key soil enzymes. The adsorption process was best described by the pseudo-second-order model and the Freundlich isotherm model, suggesting dominant chemisorption and multilayer adsorption on heterogeneous surfaces of the soil–MP composites. All MPs significantly enhanced the adsorption capacity for atrazine (6.80–39.93 mg kg−1), with the order PBS > PE > PVC. Furthermore, the degradation of atrazine was impeded by all MPs, with PVC exhibiting the strongest inhibitory effect. The half-life of atrazine ranges from 22.97 to 81.76 days in two soils. The presence of MPs also influenced soil enzyme activities and the effects varied by MP type and soil property. These results demonstrate that MPs can modify the adsorption and persistence of atrazine in soil, thereby increasing its environmental risk. This study provides valuable insights for the long-term ecological risk assessment of co-existing MPs and pesticide pollution in terrestrial environments.