Wang Yi, Chen Xingwei
Fujian Provincial Engineering Research Center for Monitoring and Assessing Terrestrial Disasters, Fujian Normal University, Fuzhou 350117, China; School of Geographical Sciences, School of Carbon Neutrality Future Technology, Fujian Normal University, Fuzhou 350117, China; State Key Laboratory for Subtropical Mountain Ecology, Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou 350117, China.
Fujian Provincial Engineering Research Center for Monitoring and Assessing Terrestrial Disasters, Fujian Normal University, Fuzhou 350117, China; School of Geographical Sciences, School of Carbon Neutrality Future Technology, Fujian Normal University, Fuzhou 350117, China; State Key Laboratory for Subtropical Mountain Ecology, Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou 350117, China.
Sci Total Environ. 2023 Nov 25;901:165941. doi: 10.1016/j.scitotenv.2023.165941. Epub 2023 Aug 2.
Estuary and coastal waters are hotspot areas for microplastics (MPs) pollution. MPs of varying sizes converge in this complex nearshore environment. Aggregation is an important process that affects the transport and fate of MPs in the aqueous environment. Nevertheless, the influence of different factors on the aggregation behavior and the aggregates structure of MPs is unclear. In this study, the aggregation behavior and the aggregates structure of polyethylene microplastics (PEs) of different sizes under the impact of nearshore environmental conditions (i.e., salinity gradient, dissolved organic matter-DOM, turbulent flow) were investigated. The results show that particle size was the dominant factor affecting the stability of PEs in the aqueous environment, and the critical coagulation concentration (CCC) of PEs shifts to the right with increasing size. It was also found that the size of PEs stable aggregates is negatively correlated with the turbulent kinetic energy dissipation rate. The particle size of PEs can significantly affect the fractal dimension (FD) of stable aggregates, and the smaller the particle size, the more compact the aggregates formed. Moreover, salinity and DOM control the size and FD of PEs stable aggregates through different mechanisms. The findings of this study will be helpful for the prediction of the transport and fate of MPs in the aqueous environment.
河口和沿海水域是微塑料（MPs）污染的热点区域。不同大小的微塑料在这个复杂的近岸环境中汇聚。聚集是影响微塑料在水环境中迁移和归宿的一个重要过程。然而，不同因素对微塑料聚集行为和聚集体结构的影响尚不清楚。在本研究中，研究了不同大小的聚乙烯微塑料（PEs）在近岸环境条件（即盐度梯度、溶解有机物-DOM、湍流）影响下的聚集行为和聚集体结构。结果表明，粒径是影响水环境中聚乙烯稳定性的主导因素，聚乙烯的临界凝聚浓度（CCC）随粒径增大而右移。还发现聚乙烯稳定聚集体的大小与湍流动能耗散率呈负相关。聚乙烯的粒径能显著影响稳定聚集体的分形维数（FD），粒径越小，形成的聚集体越紧密。此外，盐度和DOM通过不同机制控制聚乙烯稳定聚集体的大小和分形维数。本研究结果将有助于预测微塑料在水环境中的迁移和归宿。
