Department of Environmental Engineering, School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China.
Department of Environmental Engineering, School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China.
Chemosphere. 2022 Dec;309(Pt 1):136593. doi: 10.1016/j.chemosphere.2022.136593. Epub 2022 Sep 24.
As an emerging pollutant, the transport behavior of colloidal microplastic particles (CMPs) in saturated porous media may be affected by the simultaneous presence of other substances in the natural environment. In this study, colloidal polystyrene microplastic particles (PSMPs) were selected as the representative of CMPs to investigate the cotransport behaviors of CMPs in the presence of humic acid (HA) under varied environmental conditions (ionic strength: 1, 100 mM KCl; HA concentration: 0, 5, 10, 20 mg⋅L) in porous media. The presence of HA with different concentrations was found to increase the mobility of 1.0-μm and 0.2-μm CMPs in porous media in a non-linear and non-monotonic manner. Furthermore, the HA-facilitated transport of CMPs occurred under both electrostatically unfavorable and favorable attachment conditions (limited to the conditions examined in this study, corresponding to 1 and 100 mM KCl, respectively). The transport behavior of the smaller-sized CMPs (0.2-μm CMPs) was more sensitive to the change of ionic strength and the presence of HA than that of the larger-sized CMPs (1.0-μm CMPs). The cotransport process of CMPs and HA was affected by many factors. Modeling results showed that a small amount of competitive blocking occurred during the cotransport process. Moreover, both the presence of HA and change in ionic strength could affect the surface properties of CMPs. Thus, the cotransport behavior of CMPs with HA was different from the transport of individual CMPs in porous media. Experimental results revealed that HA induced complexity in the transport behavior of CMPs in the aqueous environment. Therefore, undeniably, a lot more systematic explorations are further demanded to better comprehend the CMPs cotransport mechanism in the presence of other substances.
作为一种新兴污染物，胶体微塑料颗粒（CMPs）在饱和多孔介质中的迁移行为可能会受到自然环境中其他物质同时存在的影响。在这项研究中，选择胶体聚苯乙烯微塑料颗粒（PSMPs）作为 CMPs 的代表，研究了在不同环境条件下（离子强度：1、100 mM KCl；腐殖酸浓度：0、5、10、20 mg⋅L），腐殖酸（HA）存在时 CMPs 在多孔介质中的共运移行为。研究发现，不同浓度的 HA 以非线性和非单调的方式增加了 1.0-μm 和 0.2-μm CMPs 在多孔介质中的迁移性。此外，在静电不利和有利附着条件下（限于本研究中检查的条件，分别对应于 1 和 100 mM KCl）都发生了 HA 促进的 CMPs 输运。较小粒径（0.2-μm CMPs）的 CMPs 的输运行为对离子强度和 HA 存在的变化比较大粒径（1.0-μm CMPs）的 CMPs 更为敏感。CMPs 和 HA 的共运移过程受到许多因素的影响。建模结果表明，在共运移过程中发生了少量的竞争阻塞。此外，HA 的存在和离子强度的变化都会影响 CMPs 的表面性质。因此，HA 存在时 CMPs 的共运移行为与多孔介质中单个 CMPs 的输运行为不同。实验结果表明，HA 增加了 CMPs 在水相环境中的输运行为的复杂性。因此，不可否认的是，需要进一步进行更多的系统探索，以更好地理解其他物质存在时 CMPs 的共运移机制。
