Chair of Hydrogeology and Hydrochemistry, Freiberg University of Mining and Technology (TU Bergakademie Freiberg), 09599 Freiberg, Germany; Zittau Institute for Process Development, Recycling Management, Surface Technology, and Natural Substance Research (ZIRKON), University of Applied Sciences Zittau/Görlitz (HSZG), 02763 Zittau, Germany.
Chair of Hydrogeology and Hydrochemistry, Freiberg University of Mining and Technology (TU Bergakademie Freiberg), 09599 Freiberg, Germany.
Sci Total Environ. 2022 Aug 25;836:155657. doi: 10.1016/j.scitotenv.2022.155657. Epub 2022 May 2.
Microplastics are an obstinate pollutant in terrestrial environments, posing a risk to the subsurface soil matrix and potentially to groundwater. In this study, the transport and retention behaviour of two major plastic polymers, 125-300 μm Polyvinyl chloride (PVC) plastic fragments and 300 μm Low-density polyethylene (LDPE) spherical particles, were explored in saturated quartz sand (1.6-2.0 mm) columns. The PVC used in this study represented secondary microplastics, while the LDPE represented primary microplastics. Retention profiles at different ultrapure water flow rates (2.0-3.5 ml/min) were compared and analysed. At the beginning and end of each column test, the microplastic particles were scrutinized, identified, and quantified by light microscopy. The results showed that the transport distance of microplastic particles increased with their decreasing diameter. Small-sized PVC microplastic particles, whose morphology was more 1-dimensional, were more susceptible to fragmentation within the column, promoting migration. Spherical LDPE remained at their initial position without fragmenting. Microplastic degradation into fragments appeared to play an important role in improving the movement of particles. This study offers initial indications of infiltration depths and shape-dependent fragmentation of secondary microplastics in coarse sand based on the lab experiments.
微塑料是陆地环境中一种顽固的污染物，对地下土壤基质构成潜在威胁，并可能对地下水造成影响。本研究在饱和石英砂（1.6-2.0 毫米）柱中探索了两种主要塑料聚合物，即 125-300 μm 聚氯乙烯（PVC）塑料碎片和 300 μm 低密度聚乙烯（LDPE）球形颗粒的迁移和滞留行为。本研究中使用的 PVC 代表了次生微塑料，而 LDPE 则代表了原生微塑料。比较并分析了不同超纯水流速（2.0-3.5 ml/min）下的保留曲线。在每个柱试验的开始和结束时，通过光学显微镜仔细检查、识别和定量分析微塑料颗粒。结果表明，微塑料颗粒的迁移距离随其直径的减小而增加。形态更一维的小尺寸 PVC 微塑料颗粒在柱内更容易发生碎裂，从而促进迁移。球形 LDPE 则保持在初始位置，没有发生碎裂。微塑料降解为碎片似乎在改善颗粒的迁移方面发挥了重要作用。本研究基于实验室实验，初步表明了次生微塑料在粗砂中的渗透深度和形状依赖性碎裂。
