微塑料对土壤持水性能的影响

Influence of Microplastics on Soil Water Retention

为探究微塑料对土壤持水性能的影响,选用粒径为1 mm和25μm的聚乙烯微塑料(PE—MPs)颗粒进行土培处理后,采用高速离心机法测得不同处理下的土壤水分特征曲线,并使用Gardner模型进行拟合分析。结果表明:(1)土壤中累积少量的PE—MPs(0~5.00 g/kg)能增强土壤持水性,但当累积量超过一定阈值(5.00~50.00 g/kg)会导致土壤持水能力显著降低。(2)1 mm大粒径PE—MPs大量积累对土壤持水性的降低效应更显著;25μm小粒径PE—MPs少量积累对土壤持水性的提升效应更显著。(3)1 mm大粒径PE—MPs进入土壤后主要影响大孔隙与有效孔隙,对土壤有效含水率的影响较大;25μm小粒径PE—MPs进入土壤后主要影响微小孔隙,对萎焉系数影响较大。该研究可为高农膜残留地区水分迁移模拟和农业生态风险评价提供理论依据。

In order to explore the impact of microplastics on soil water retention,1 mm and 25μm polyethylene microplastics(PE-MPs)were selected.After the soil culture,the soil moisture characteristic curves under different treatments were measured by the high-speed centrifuge method,and the Gardner model was used for fitting analysis.The results showed that:(1)A small amount of PE-MPs(0~5.00 g/kg)accumulated in the soil could enhance the soil water holding capacity,but when the cumulative amount exceeded a certain threshold(5.00~50.00 g/kg),it would lead to a significant reduction in soil water holding capacity.(2)The large accumulation of 1 mm PE-MPs had a more significant reduction effect on soil water holding capacity;a small amount of 25μm PE-MPs had a more significant increase effect on soil water holding capacity.(3)After invading into soil,the 1mm PE-MPs mainly affected the macropores and effective pores,and had a greater impact on the effective soil moisture content;while 25μm PE-MPs mainly affected the micro pores and had a greater impact on the wilting coefficient.This study can provide a theoretical basis for water migration simulation and agricultural ecological risk assessment in areas with high agricultural film residues.