Fujian Provincial Engineering Research Center for Monitoring and Assessing Terrestrial Disasters, Fujian Normal University, Fuzhou, 350007, China; School of Geographical Sciences, Fujian Normal University, Fuzhou, China, Fuzhou, 350007, China; State Key Laboratory for Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou, 350007, China.
Fujian Provincial Engineering Research Center for Monitoring and Assessing Terrestrial Disasters, Fujian Normal University, Fuzhou, 350007, China; School of Geographical Sciences, Fujian Normal University, Fuzhou, China, Fuzhou, 350007, China; State Key Laboratory for Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou, 350007, China.
Environ Pollut. 2023 Jan 1;316(Pt 2):120649. doi: 10.1016/j.envpol.2022.120649. Epub 2022 Nov 11.
Microplastics (MPs) are emerging as a class of pollutants that are a potential threat to biological and human health. Aggregation and settling are crucial to controlling MPs transport and environmental fate. However, the influence of clay minerals in the aqueous environment on the aggregation-settling processes of larger size MPs and its mechanisms remain unclear. In this study, homoaggregation of pristine and aged polyethylene microplastics (PEs) and heteroaggregation-settling of PEs with typical clay minerals (chlorite, illite, kaolinite, montmorillonite) under different hydrochemical conditions (NaCl, CaCl, MgCl) were systematically investigated. The results showed that the cation type has a greater influence on the homoaggregation system. In detail, the aged PEs is more stable than pristine PEs in monovalent electrolyte solutions, but not in divalent electrolytes. In heteroaggregation systems, electrostatic repulsion dominates the interaction of PEs (pristine, aged) with clay minerals. However, the settling ratio of PEs (pristine, aged) contributed by clay minerals is not very dependent on the clay mineral type. Conversely, high NaCl concentrations are more conducive to the heteroaggregation-settling of PEs, which can be explained by the DLVO theory. The findings of this study provide new insights into the environmental fate and distribution of MPs in natural waters.
微塑料（MPs）作为一类新兴污染物，对生物和人类健康构成潜在威胁。聚集和沉降对于控制 MPs 的迁移和环境归宿至关重要。然而，水相环境中粘土矿物对较大尺寸 MPs 的聚集-沉降过程及其机制的影响仍不清楚。在这项研究中，系统研究了不同水化学条件（NaCl、CaCl2、MgCl2）下原始和老化聚乙烯微塑料（PEs）的同聚、典型粘土矿物（绿泥石、伊利石、高岭石、蒙脱石）的共聚-沉降。结果表明，阳离子类型对同聚体系的影响更大。具体来说，在单价电解质溶液中，老化的 PEs 比原始 PEs 更稳定，但在二价电解质中则不然。在共聚体系中，静电排斥主导着 PEs（原始、老化）与粘土矿物的相互作用。然而，粘土矿物对 PEs（原始、老化）的沉降比例并不十分依赖于粘土矿物类型。相反，高 NaCl 浓度更有利于 PEs 的共聚-沉降，这可以用 DLVO 理论来解释。本研究的结果为 MPs 在天然水中的环境归宿和分布提供了新的见解。
