Li Qihang, Bogush Anna, Van De Wiel Marco, Wu Pan, Holtzman Ran
College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China.
Fluid and Complex Systems Research Centre, Coventry University, Coventry, UK.
iScience. 2025 Jul 24;28(9):113193. doi: 10.1016/j.isci.2025.113193. eCollection 2025 Sep 19.
Microplastics (MPs) pose a substantial threat to humans and ecosystems. How MPs move in soils is controlled by a large number of coupled parameters, including MPs and soil properties as well as hydrological and geochemical conditions. We conduct laboratory experiments where two commonly MPs types found in soils-polyethylene terephthalate (PET) and polypropylene (PP)-are leached into an idealized soil analog (glass beads). We use time-lapse imaging to analyze the water flow pathways and spectroscopy to measure the MPs transport. We find that MPs impede water infiltration into preferential pathways, with a stronger effect for the more hydrophobic PP, and that PET is more mobile than PP. We explain this by the stronger impedance of PP on water flow that carries the MPs (the driving force), as well as PP surface charge enhancing its adsorption onto soil particles, and its lower density that limits downward transport. These findings advance our understanding the mechanisms underlying MP transport in soils.
微塑料对人类和生态系统构成重大威胁。微塑料在土壤中的移动受大量耦合参数控制，包括微塑料和土壤性质以及水文和地球化学条件。我们进行了实验室实验，将土壤中常见的两种微塑料类型——聚对苯二甲酸乙二酯（PET）和聚丙烯（PP）——淋滤到一种理想化的土壤类似物（玻璃珠）中。我们使用延时成像来分析水流路径，并使用光谱学来测量微塑料的迁移。我们发现微塑料会阻碍水渗入优先路径，疏水性更强的PP的影响更大，并且PET比PP的迁移性更强。我们对此的解释是，PP对携带微塑料的水流（驱动力）的阻碍更强，以及PP表面电荷增强了其在土壤颗粒上的吸附，且其较低的密度限制了向下的迁移。这些发现推进了我们对微塑料在土壤中迁移机制的理解。
