Chongqing Engineering Laboratory of Environmental Hydraulic Engineering, Chongqing Jiaotong University, Chongqing 400074, China.
Chongqing Engineering Laboratory of Environmental Hydraulic Engineering, Chongqing Jiaotong University, Chongqing 400074, China.
Mar Pollut Bull. 2022 Jul;180:113775. doi: 10.1016/j.marpolbul.2022.113775. Epub 2022 Jun 2.
The interaction between microplastics (MPs) and suspended sediment (SS) is important for the environmental fate of MPs. This study explored the interaction of MPs with SS and the vertical migration behavior of MPs in sediment-bearing turbulence. The turbulent shear flow caused MPs to aggregate. This aggregation resulted in a rapid increase in particle size, which peaked when the shear rate was 19.94 s, and then declined with a further increase in the shear rate. Compared to large MPs, small MPs were more prone to aggregation, which formed heterogeneous aggregate MPs-SS in sediment-bearing turbulence. Owing to the formation of heterogeneous aggregates, small MPs had a much higher settlement rate in sediment-bearing turbulence than in sediment-free turbulence. MPs in bottom sediments may resuspend owing to turbulent shear flow acting on sediments, causing secondary pollution. These results provide new insights into the aggregation, settlement, and resuspension behaviors of MPs in natural waters.
微塑料（MPs）与悬浮物（SS）之间的相互作用对 MPs 的环境归宿非常重要。本研究探讨了 MPs 与 SS 的相互作用以及含沙紊流中 MPs 的垂直迁移行为。紊流剪切流导致 MPs 聚集。这种聚集导致粒径迅速增加，当剪切速率达到 19.94 s 时达到峰值，然后随着剪切速率的进一步增加而下降。与大 MPs 相比，小 MPs 更容易聚集，在含沙紊流中形成非均相聚集 MPs-SS。由于形成了非均相聚集，小 MPs 在含沙紊流中的沉降速率远高于无沙紊流。由于作用在沉积物上的紊流剪切流，底泥中的 MPs 可能会重新悬浮，造成二次污染。这些结果为 MPs 在自然水体中的聚集、沉降和再悬浮行为提供了新的认识。
