Migration Behavior Of Typical Microplastics Derived From Aged Light-Degradable Plastic Film In Distinct Soils Under Rainfall
摘要
Microplastics (MPs) migration in soil has attracted significant attention. While most existing studies employ raw materials of plastic products as MPs to investigate their migration in (quartz) sand column, and these MPs differ substantially from typical MPs (T-MPs) derived from aged plastic products. Moreover, sand and soil also differ in property. This study examines the migration behaviour of T-MPs derived from aged light-degradable plastic films in three distinct soils (red, black, and fluvo-aquic) under simulated rainfall conditions using large soil columns, and the related impact factors were discussed. Results indicated consistent vertical migration patterns of T-MPs across all soil types that T-MPs amounts decreased with soil depth. Higher T-MPs level (75 kg/ha), neutral rain (pH=7.0), and heavy rainfall (30 mm/24 h) significantly enhanced T-MPs migration in soil compared with lower T-MPs level (25 kg/ha), acid rain (pH=5.5), and light rainfall (10 mm/24 h). Black soil retained more large-sized T-MPs (>0.46 mm) in both soil and leachate due to high porosity and low bulk density, whereas red and fluvo-aquic soils restricted large-T-MP migration but facilitated the transport of small-sized T-MPs (<0.33 mm) into leachate due to lower porosity and higher bulk density. This study indicates that T-MPs can largely migrate in soils under rainfall and pose risks to groundwater safety, particularly under heavy and neutral rainfall.