| 尹福玉,李旺,祖波,陈魏,王梅,张中杰,陈馨,李浩闻.微塑料在紊流中的聚沉行为[J].农业环境科学学报,2025,44(7):1836-1847. |
| 微塑料在紊流中的聚沉行为 |
| Aggregation and sedimentation behavior of microplastics in turbulence |
| 投稿时间：2024-10-17 |
| DOI：10.11654/jaes.2024-0890 |
| 中文关键词: 微塑料 紊流 泥沙 聚集 沉降 |
| 英文关键词: microplastics turbulence sediment aggregation sedimentation |
| 基金项目:重庆市水利科技重点项目（CQSLK-2023005）；重庆市博士后研究项目特别资助项目（2023CQBSHTB1004）；招商局生态环保科技有限公司科技自主创新项目（240128）；重庆交通大学科研启动经费项目（F1230105）；重庆市城市管理科研项目（城管科字2021第12号） |
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| 中文摘要: |
| 本研究旨在探究含沙紊流中微塑料的聚集与沉降特性，并揭示其机制。通过自研的各向同性均匀紊流装置和粒子跟踪测速（PTV）方法，研究分析了微塑料的聚集与沉降行为。结果表明：水流剪切强度的增加能够促进微塑料的聚集，但过高的剪切强度可能破坏聚体结构，限制聚团进一步增大。同时，紊流作用下，泥沙的存在能够促进微塑料产生更大的聚团。随着剪切率的增加，水中颗粒整体结构分形维数增大，而表面形态分形维数减小，且这些变化趋势随着剪切率的进一步增加而逐渐减缓。在含沙紊流中，颗粒的两种分形维数均略高于清水紊流中的相应值。在清水紊流中，微塑料颗粒的整体沉降速度随着剪切率增加先增后减，而在含沙紊流中，整体沉降速度随剪切率增加而增加。无论是否含有泥沙，微塑料颗粒的最小沉降速度与粒径成正比，最大沉降速度与粒径成反比，小粒径微塑料颗粒在紊流中的沉降稳定性较差，受到紊流的影响更加明显。研究表明，紊流对微塑料聚集的影响具有双重性，并能引起聚团结构及表面形态发生变化，微塑料的沉降行为与粒径密切相关，泥沙的存在不仅能促进微塑料聚集，还能影响微塑料的沉降行为。 |
| 英文摘要: |
| This study aims to investigate the aggregation and sedimentation characteristics of microplastics in sand-carrying turbulence and to reveal the underlying mechanisms. By employing a self-developed isotropic uniform turbulence device and particle tracking velocimetry（PTV）method, the aggregation and sedimentation behavior of microplastics were analyzed. The results indicated that an increase in water flow shear strength could promote the aggregation of microplastics, but excessively high shear strength might disrupt the structure of aggregates, limiting their further enlargement. Concurrently, the presence of sediment in turbulent flow could facilitate the formation of larger microplastic aggregates. As the shear rate increased, the overall structural fractal dimension of particles in water increased, while the surface morphological fractal dimension decreased, and these trends gradually slowed down with further increases in shear rate. In sand-carrying turbulence, both types of fractal dimensions of particles were slightly higher than those in clear water turbulence. In clear water turbulence, the overall settling velocity of microplastic particles first increased and then decreased with increasing shear rate, whereas in sand-carrying turbulence, the overall settling velocity increased with increasing shear rate. Regardless of the presence of sediment, the minimum settling velocity of microplastic particles was directly proportional to particle size, while the maximum settling velocity was inversely proportional to particle size. Smaller microplastic particles exhibited poorer settling stability in turbulence and were more significantly affected by turbulence. The study demonstrates that turbulence has a dual effect on the aggregation of microplastics and can also cause changes in the structure and surface morphology of aggregates. The sedimentation behavior of microplastics is closely related to particle size, and the presence of sediment not only promotes the aggregation of microplastics but also alters their sedimentation behavior. |
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