Abstract：
The majority of microplastics (MPs) found in the environment originate from plastic fragmentation occurring in the environment and are influenced by environmental factors such as UV irradiation and biotic interactions. However, the effects of river drying on plastic fragmentation remain unknown, despite the global prevalence of watercourses experiencing flow intermittence. This study investigates, through laboratory experiments, the coupled effects of drying duration and UV irradiation on PVC film fragmentation induced by artificial mechanical abrasion. This study shows that PVC film fragmentation increases with drying duration through an increase in the abundance and size of formed MPs as well as mass loss from the initial plastic item, with significant differences for drying durations >50% of the experiment duration. The average abundance of formed MPs in treatments exposed to severe drying duration was almost two times higher than in treatments nonexposed to drying. Based on these results, we developed as a proof of concept an Intermittence-Based Plastic Fragmentation Index that may provide insights into plastic fragmentation occurring in river catchments experiencing large hydrological variability. The present study suggests that flow intermittence occurring in rivers and streams can lead to increasing plastic fragmentation, unraveling new insights into plastic pollution in freshwater systems.
摘要：
在环境中发现的大多数微塑料（MP）源自环境中发生的塑料碎裂，并受到环境因素如紫外线照射和生物相互作用的影响。然而,河流干燥对塑料碎片的影响仍然未知，尽管全球普遍存在水道经历流量间歇性。这项研究调查了，通过实验室实验,干燥时间和紫外线照射对人工机械磨损引起的PVC薄膜破碎的耦合影响。这项研究表明，PVC薄膜碎片随着干燥时间的增加而增加，形成的MPs的丰度和大小以及初始塑料制品的质量损失。对于干燥持续时间>实验持续时间的50%，差异显著。在暴露于严重干燥持续时间的处理中，形成的MP的平均丰度几乎是未暴露于干燥的处理的两倍。基于这些结果,我们开发了基于间歇性的塑料碎裂指数作为概念的证明，该指数可以提供对经历大水文变化的河流流域中发生的塑料碎裂的见解。本研究表明，河流和溪流中发生的流动间歇性会导致塑料碎片增加，揭示淡水系统中塑料污染的新见解。
