微塑料是一类土壤中广泛存在的新兴污染物，其对土壤磷吸附的影响尚不明确。文中分析了0.1%～10%含量微塑料对土壤磷吸附特性的影响及机制。结果表明，微塑料会使得吸附第一阶段液膜扩散阶段速率显著提升（p<0.05）。与纯土壤（q_e=6.456 mg/g）相比，含量1%以下的微塑料显著降低了土壤磷吸附容量（p<0.05），但5%以上的微塑料显著提升了土壤磷吸附容量（p<0.05）。同等含量下，微塑料粒径越小，微塑料-土壤体系的磷吸附量越大。微塑料可与磷竞争吸附位点，降低了微塑料-土壤体系对磷的吸附，但微塑料也可直接吸附磷，故当微塑料为5%及以上时，微塑料-土壤体系对磷的吸附量升高。因此，土壤微塑料污染可显著改变土壤对磷的吸附特性，且与微塑料的含量和粒径等因素密切相关。

Microplastics are emerging pollutants widely present in soil, and their effects on soil phosphorus (P) adsorption are still unclear. This paper examined the effects of 0.1% to 10% microplastics on soil P adsorption and the underlying mechanisms. The results showed that microplastics could significantly increase the rate of liquid film diffusion stage in the first stage of the adsorption process (p<0.05). Compared with the pure soil (q_e=6.456 mg/g), the soil P adsorption capacity was significantly reduced by microplastics with less than 1% concentration (p<0.05). However, the soil P adsorption capacity was significantly increased by microplastic with concentrations higher than 5% (p<0.05). Additionally, the smaller the particle size of microplastics, the greater the P adsorption capacity of soil with the same microplastic concentration. Microplastics could compete with P for adsorption sites, which reduced the adsorption of P in the microplastic-soil system. However, microplastics could also directly adsorb P, leading to an increase in the P adsorption capacity of microplastic-soil system when microplastic concentration were more than 5%. Therefore, microplastics pollution in soil could significantly change P adsorption characteristics, which closely related to the microplastics concentration and particle size.

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国家自然科学基金资助项目（32001195）；国家重点研发计划资助项目（2019YFD1100501）。