Microplastics are emerging contaminants and widely distributed in the environment. They are considered as a vector of numerous organic pollutants including antibiotics in aquatic environments and thereby influence their distribution and transport behaviors. However, the effects of microplastics on the environmental behavior of antibiotics in soils remain largely unclear. In this paper, the influence of polyamide (PA) microplastics on sorption and transport of the selected antibiotic [oxytetracycline (OTC)] in a sandy loamy soil was studied by performing batch and column experiments. Results show that PA microplastics increase the pH of reaction systems, which contributes to OTC sorption onto the tested soils. However, altering pH is not the key influencing mechanism because the overall sorption capacity decreases slightly after adding PA microplastics, which can be attributed to the dilution effect. Reduction of OTC sorption by adding microplastics promotes the migration of OTC in the tested soil, which could be demonstrated by the results of column experiments that the breakthrough of OTC occurs earlier with an increasing content of PA microplastics. According to the fitting parameters of HYDRUS−1D model, PA microplastics can affect the transport of OTC by altering the soil pore structure and dispersion coefficient. These results provide new insight into the interaction between microplastics and organic pollutants in soil environments.

微塑料是新兴的污染物，广泛分布在环境中。它们被认为是水生环境中包括抗生素在内的多种有机污染物的媒介，因此会影响其分布和运输行为。但是，微塑料对土壤中抗生素环境行为的影响仍然不清楚。本文通过分批和柱实验研究了聚酰胺（PA）微塑料对选定的抗生素[土霉素（OTC）]在沙质壤土中的吸附和迁移的影响。结果表明，PA微塑料可提高反应体系的pH值，这有助于OTC在被测土壤上的吸附。然而，改变pH值不是主要的影响机制，因为添加PA微塑料后，总吸附能力会略有下降，这可能是由于稀释作用所致。通过添加微塑料减少OTC吸附可促进OTC在被测土壤中的迁移，这可以通过柱实验的结果证明，随着PA微塑料含量的增加，OTC的突破较早发生。根据HYDRUS-1D模型的拟合参数，PA微塑料可以通过改变土壤孔隙结构和分散系数来影响OTC的运输。这些结果为土壤环境中微塑料与有机污染物之间的相互作用提供了新的见解。通过添加微塑料减少OTC吸附可促进OTC在被测土壤中的迁移，这可以通过柱实验的结果证明，随着PA微塑料含量的增加，OTC的突破较早发生。根据HYDRUS-1D模型的拟合参数，PA微塑料可以通过改变土壤孔隙结构和分散系数来影响OTC的运输。这些结果为土壤环境中微塑料与有机污染物之间的相互作用提供了新的见解。通过添加微塑料减少OTC吸附可促进OTC在被测土壤中的迁移，这可以通过柱实验的结果证明，随着PA微塑料含量的增加，OTC的突破较早发生。根据HYDRUS-1D模型的拟合参数，PA微塑料可以通过改变土壤孔隙结构和分散系数来影响OTC的运输。这些结果为土壤环境中微塑料与有机污染物之间的相互作用提供了新的见解。PA微塑料可通过改变土壤孔隙结构和分散系数来影响OTC的运输。这些结果为土壤环境中微塑料与有机污染物之间的相互作用提供了新的见解。PA微塑料可通过改变土壤孔隙结构和分散系数来影响OTC的运输。这些结果为土壤环境中微塑料与有机污染物之间的相互作用提供了新的见解。