Hu Enzhu, Yuan Hongbo, Du Yichun, Chen Xijuan
Institute of Resources and Environmental Sciences, School of Metallurgy, Northeastern University, Shenyang 110819, China.
Shaanxi Key Laboratory of Land Consolidation, Shaanxi Provincial Land Engineering Construction Group Co., Ltd., Chang'an University, Xi'an 710054, China.
Materials (Basel). 2021 Apr 2;14(7):1757. doi: 10.3390/ma14071757.
The accumulation of microplastics (MPs) in soil and sediments may influence the penetration of contaminants into subsurface environments. However, little attention has been paid to comparing the different roles of two common polyethylene (PE) types-low-density polyethylene (LDPE) and high-density polyethylene (HDPE). In this study, the transport behaviors of tetracycline in saturated quartz sand columns in the presence and absence of these two MPs were investigated, respectively. The results showed that both types of PE MPs restrained the mobility of tetracycline at neutral conditions, while such detrimental effects were weak at acid and alkaline conditions. The degree of nonequilibrium adsorption was higher, and tetracycline transferred easier to the kinetic site for the existence of LDPE than of HDPE. The increased roughness and Brunauer-Emmett-Teller (BET) surface areas, more negative zeta potentials and the formation of oxygen function groups on the surface of MPs after UV-weathering intensified the retardation of tetracycline transport. This study revealed that the PE type and weathering should be taken into account in risk assessment, along with the solution chemistry.
微塑料（MPs）在土壤和沉积物中的积累可能会影响污染物向地下环境的渗透。然而，很少有人关注比较两种常见聚乙烯（PE）类型——低密度聚乙烯（LDPE）和高密度聚乙烯（HDPE）——的不同作用。在本研究中，分别研究了在有和没有这两种微塑料存在的情况下，四环素在饱和石英砂柱中的迁移行为。结果表明，两种类型的PE微塑料在中性条件下均抑制了四环素的迁移，而在酸性和碱性条件下这种不利影响较弱。与HDPE相比，由于LDPE的存在，非平衡吸附程度更高，四环素更容易转移到动力学位点。紫外线老化后，微塑料表面粗糙度增加、比表面积（BET）增大、zeta电位更负以及形成了氧官能团，这些都加剧了四环素迁移的阻滞。本研究表明，在风险评估中，除了溶液化学外，还应考虑PE类型和老化情况。
