弱动力水体中聚合物密度主导微塑料沉降行为:光老化程度与钙离子浓度的协同调控

弱动力水体中聚合物密度主导微塑料沉降行为:光老化程度与钙离子浓度的协同调控

张昊天, 李沛钊, 舒小华, 汝旋, 李宗宸, 张倩

中国环境科学 ›› 2026, Vol. 46 ›› Issue (1) : 440-449.

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中国环境科学 ›› 2026, Vol. 46 ›› Issue (1) : 440-449.

弱动力水体中聚合物密度主导微塑料沉降行为:光老化程度与钙离子浓度的协同调控

张昊天¹, 李沛钊¹, 舒小华², 汝旋¹, 李宗宸¹, 张倩¹

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Polymer density dominates the sedimentation behavior of microplastics in weakly dynamic water bodies: Synergistic regulation by photoaging degree and concentration of calcium ion

ZHANG Hao-tian¹, LI Pei-zhao¹, SHU Xiao-hua², RU Xuan¹, LI Zong-chen¹, ZHANG Qian¹

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摘要

微塑料(MPs)在水体中的沉降行为受颗粒自身性质、光老化程度以及溶液化学条件的协同调控.现有研究忽视了不同类型老化MPs在喀斯特小水体中的沉降行为.通过模拟实验考察了聚苯乙烯(PS)、聚酰胺6(PA6)和聚对苯二甲酸乙二醇酯(PET)3种不同光老化程度的MPs在弱动力水体及不同CaCl₂浓度环境中的沉降行为.结果表明,3种MPs在纯水中的沉降比均随光老化程度的加深呈下降趋势,而在CaCl₂环境中结果与之相反.相较于原始MPs,老化1000h后的MPs在纯水中沉降比降低了38.8%~56.0%,在10mmol/L和100mmol/LCaCl₂环境中的沉降比分别提高了23.8%~93.3%和66.1%~357.1%.Ca²⁺通过压缩MPs双电层降低颗粒间的静电斥力,还与老化后MPs表面含氧官能团桥接,这有利于颗粒间同质聚集从而促进其沉降.皮尔逊相关性分析与DLVO理论计算结果表明,Ca²⁺桥接是调控老化前后MPs聚集沉降的重要外部因素.尽管光老化程度和盐离子会影响MPs沉降过程,但3种聚合物MPs的Peclet值小于1证明了材料密度是其沉降过程的主导因素.综上,聚合物密度主导MPs的沉降过程,光老化通过改变MPs表面含氧官能团和粒径分布调节颗粒间的相互作用,而Ca²⁺导致的双电层压缩和桥接效应则进一步影响MPs的聚集沉降行为.

Abstract

The sedimentation behavior of microplastics (MPs) in water bodies is synergistically regulated by the intrinsic properties of the particles, the photoaging degree, and the chemical conditions of the solution. Existing studies have overlooked the sedimentation behavior for different types of aged MPs in karst small water bodies. Through simulation experiments, the sedimentation behavior of three types of MPs (polystyrene (PS), polyamide 6 (PA6), and polyethylene terephthalate (PET)) with different photoaging degrees wasinvestigated in weakly dynamic water bodies and environments with different concentrations of CaCl₂. The results showed that the sedimentation ratios of the three types of MPs exhibited a decreasing trend with the deepening of photoaging under pure water conditions,while the opposite result was observed in the CaCl₂ environment.Compared with pristine MPs, the sedimentation ratios of MPs aged for 1000h decreased by 38.8% to 56.0%in pure water. In contrast, the sedimentation ratios increased by 23.8% to 93.3% and 66.1% to 357.1% in 10mmol/L and 100mmol/L CaCl₂ solution, respectively. Ca²⁺ can compress the electrical double layer of MPs, reducing the electrostatic repulsion between particles. Simultaneously, It can also bridge with the oxygen-containing functional groups on the surface of aged MPs. These effects facilitate the homogeneous aggregation of particles, therebypromoting their sedimentation. The results of Pearson correlation analysis and DLVO theory calculations indicated that bridging of Ca²⁺ was an important external factor regulating the aggregation and sedimentation of MPs before and after aging. Although the photoaging degree and salt ions influenced the sedimentation process of MPs, the fact that Peclet values of the three polymer MPs were below 1demonstratedthat material densitywas the dominantfactor governing their sedimentation behavior. the sedimentation of MPs is primarily governed by polymer density. Photoaging regulates interparticle interactions by changing the oxygen-containing functional groups and size distribution of MPs. While the compression of the electrical double layer and bridging effects induced by Ca²⁺ further influence their aggregation and sedimentation behavior of MPs.

关键词

微塑料 / 沉降行为 / 聚合物类型 / 光老化 / 多价阳离子

Key words

microplastics / sedimentation behavior / polymer type / photoaging / multivalent cations

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张昊天, 李沛钊, 舒小华, 汝旋, 李宗宸, 张倩. 弱动力水体中聚合物密度主导微塑料沉降行为:光老化程度与钙离子浓度的协同调控[J]. 中国环境科学. 2026, 46(1): 440-449

ZHANG Hao-tian, LI Pei-zhao, SHU Xiao-hua, RU Xuan, LI Zong-chen, ZHANG Qian. Polymer density dominates the sedimentation behavior of microplastics in weakly dynamic water bodies: Synergistic regulation by photoaging degree and concentration of calcium ion[J]. China Environmental Science. 2026, 46(1): 440-449

中图分类号： X524

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基金

广西八桂青年拔尖人才项目(桂人才办[2024]1);国家自然科学基金项目(52260030)

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