| 摘要: |
| 本文依据三峡库区悬沙矿物组成和泥沙级配为依据配置沙样,选择两种长江上游两种典型微塑料PMMA和PS,在自制大型水箱中开展水流剪切作用下微塑料和泥沙异质吸附试验,分析微-泥絮体的形态特征和聚集机制。结果表明水流紊动剪切作用下,相比泥沙同质吸附的絮团粒径,微-泥异质聚集的絮团粒径更大,且每毫升样品中微-泥絮团上的微塑料吸附数量随水流剪切率增大而迅速增加。扫描电镜和能谱分析结果表明,在水动力条件下泥沙与PMMA、PS微球发生异质聚集,聚集过程中存在电子转移和化学态的转变,并产生不饱和键(C=C)。由于PMMA官能团的结合能变化比PS大,表明此过程失电子更多、表面电荷越大,更容易吸附泥沙。 |
| 关键词: 微塑料 悬沙 微-泥絮体形貌 聚集机制 |
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| 基金项目:国家重点研发计划(2023YFB2604702)；国家自然科学基金青年(52109077)；重庆市技术创新与应用发展重点项目(CSTB2022TIAD-KPX0198)；重庆市水利科技项目(CQSLK-2022001)；水利部重大科技项目(SKS-2022076) |
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| Analysis of the aggregation characterization and mechanism of microplastics and suspended sand in the mega reservoir |
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Liu Jie,Zhang Zhichao,Li Xia,Zhu Lifan,Jiang Hui
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National Inland Waterway Regulation Engineering Research Center,Chongqing Jiaotong University
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| Abstract: |
| To analyze the morphological characteristics and aggregation mechanism between microplastics and sediment, this research used a homemade large-scale water tank to carry out heterogeneous adsorption experiments between microplastics and sediments under the effect of water flow shear. Two kinds of microplastics, PMMA and PS, were selected based on the typical microplastic types in the upper Changjiang River. The sediment sample configuration was determined based on the mineral composition and the grading of the suspended sediment in the Three Gorges Reservoir backwater area. The results showed that there were two response zones for the microplastics-sediment flocs size under turbulent shear: Compared with the microplastics-sediment flocs particle size for sediment homogenous adsorption, the floc particle size for microplastics-sediment flocs heterogeneous aggregation was larger, and the number of microplastics adsorbed on microplastics-sediment flocs per milliliter of sample increased rapidly with the increase of water flow shear rate. Scanning electron microscopy and energy spectrum analyses showed that heterogeneous aggregation of sediment-PMMA and sediment-PS occurred under hydrodynamic conditions. The aggregation process involves electron transfers and chemical state transitions, with unsaturated bonds (C=C). Since the binding energy variation of PMMA functional group was larger than that of PS, it indicated that PMMA loses more electrons and surface charge during this process, which made it easier to adsorb sediment. |
| Key words: microplastic suspended sediment microplastics-sediment flocs shape aggregation mechanism |
