Chen Zhikun, Elektorowicz Maria, An Chunjiang, Tian Xuelin, Wang Zheng, Yang Xiaohan, Lyu Linxiang
Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, QC H3G 1M8, Canada.
Environ Sci Technol. 2024 Jul 20. doi: 10.1021/acs.est.4c05322.
Ice can serve as a significant temporary repository and conveyance mechanism for microplastics (MPs). MPs present in the water column can become entrapped within developing ice formations, subsequently being sequestered and transported by ice floes. With changing temperatures, MPs stored in ice can be released back into the environment, while freezing conditions can alter the properties of MPs, ultimately affecting the fate of MPs in the environment. Freezing of MPs in freshwater ice results in the aggregation of MP particles due to physical compression, leading to an increase in particle size once the MPs are released from the ice. The freezing-induced aggregation enhances buoyancy effects, accelerating the settling/rising velocity of MPs in water. Additionally, freezing can lead to enhanced surface wetting alterations, thus improving the dispersion of hydrophobic MPs. The presence of salt in the water can mitigate the effect of freezing on MPs due to the formation of a brine network within the ice structure, which reduces the pressure on MPs entrapped by ice. In cold regions, numerous MPs undergo freezing and thawing, re-entering the water column.
冰可以作为微塑料（MPs）的一个重要临时储存库和输送机制。水柱中存在的微塑料会被困在正在形成的冰层中，随后被浮冰隔离并运输。随着温度变化，储存在冰中的微塑料会被释放回环境中，而冰冻条件会改变微塑料的性质，最终影响微塑料在环境中的归宿。淡水冰中微塑料的冻结会因物理压缩导致微塑料颗粒聚集，一旦微塑料从冰中释放，颗粒尺寸就会增大。冻结诱导的聚集增强了浮力效应，加快了微塑料在水中的沉降/上升速度。此外，冻结会导致表面润湿性改变增强，从而改善疏水性微塑料的分散性。水中盐分的存在可以减轻冻结对微塑料的影响，这是因为在冰结构内形成了盐水网络，从而降低了冰所捕获的微塑料上的压力。在寒冷地区，大量微塑料经历冻结和解冻，重新进入水柱。
