College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China; Tianjin Key Laboratory of Environmental Technology for Complex Trans-Media Pollution, Nankai University, Tianjin, 300350, China.
College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China; Tianjin Key Laboratory of Environmental Technology for Complex Trans-Media Pollution, Nankai University, Tianjin, 300350, China.
Environ Pollut. 2021 Jun 1;278:116833. doi: 10.1016/j.envpol.2021.116833. Epub 2021 Mar 1.
Microplastics are highly accumulated in soils and supposed to migrate vertically due to water infiltration, fauna activities, and root growth. In this study, the vertical migration of microplastics along soil profile under three crop roots (corn, soybean, and ryegrass) was analyzed by a laboratory-scale incubation experiment. When microplastics were initially distributed in the surface layer, crop roots showed little effects on the vertical migration of microplastics. But in terms of homogenous microplastic distribution along soil profile, corn roots could contribute to the upward movement of microplastics in the middle layers (7-12 cm). It could be related to more pores and fissures created by primary and secondary corn roots and buoyancy effects once the pores and fissures were filled with water. Additionally, a significant positive correlation between microplastic numbers and tertiary roots of ryegrass has been observed and indicated the microplastic retention ability of fine crop roots. According to the results, in contrast to the downward microplastic migration caused by water infiltration and soil fauna activities, crop roots tended to move microplastics upwards or maintain them in soil layers.
微塑料在土壤中高度积累，并由于水的渗透、动物活动和根系生长而被推测会垂直迁移。在这项研究中，通过实验室规模的培养实验分析了三种作物根系（玉米、大豆和黑麦草）下土壤剖面中微塑料的垂直迁移。当微塑料最初分布在表层时，作物根系对微塑料的垂直迁移影响不大。但是，就均匀分布在土壤剖面上的微塑料而言，玉米根系可能有助于微塑料在中层（7-12 厘米）向上移动。这可能与玉米的初生和次生根系所产生的更多孔隙和裂缝以及一旦孔隙和裂缝被水填满后的浮力效应有关。此外，还观察到微塑料数量与黑麦草的三级根之间存在显著的正相关关系，这表明了细作物根系对微塑料的保持能力。根据研究结果，与水的渗透和土壤动物活动引起的微塑料向下迁移相比，作物根系倾向于将微塑料向上移动或使它们保持在土壤层中。
