Particulate contaminants, such as microplastics (1 μm to 5 mm) and nanoplastics (<1 μm), are disseminated in many terrestrial environments. However, it is still unclear how particles’ properties drive their mobility through soils and aquifers due to (i) poor environmental relevance of the model particles that are studied (e.g., spherical and monodisperse) and (ii) the use of packed bed experiments which do not allow a direct observation of deposition dynamics. Using transparent 2D porous media, this study analyzes deposition dynamics of rough polystyrene fragments with irregular shapes and with a size continuum (≈10 nm to 5 μm). Using in situ and ex situ measurements, particle deposition as a function of size was monitored over time under repulsive conditions. In the absence of natural organic matter (NOM), micrometric particles rapidly deposit and promote the physical interception of smaller nanoparticles by creating local porous roughness or obstacles. In the presence of NOM, differences according to particle size were no longer observed, and all fragments were more prone to being re-entrained, thereby limiting the growth of deposits. This work demonstrates the importance of pore surface roughness and porosity of the pore surface for the deposition of colloidal particles, such as microplastics and nanoplastics, under repulsive conditions.

中文翻译：

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成熟在碎片沉积中的作用：微塑料和纳米塑料的案例


微粒污染物，例如微塑料（1 μm 至 5 mm）和纳米塑料（<1 μm），在许多陆地环境中传播。然而，目前尚不清楚颗粒的特性如何驱动它们在土壤和含水层中的流动性，因为（i）所研究的模型颗粒（例如球形和单分散）的环境相关性较差，以及（ii）使用填充床实验不允许直接观察沉积动力学。本研究使用透明的二维多孔介质，分析了具有不规则形状和尺寸连续体（约 10 nm 至 5 μm）的粗糙聚苯乙烯碎片的沉积动力学。使用原位和非原位测量，在排斥条件下随时间监测颗粒沉积作为尺寸的函数。在缺乏天然有机物 (NOM) 的情况下，测微颗粒会快速沉积，并通过产生局部多孔粗糙度或障碍物来促进较小纳米颗粒的物理拦截。在 NOM 存在的情况下，不再观察到颗粒尺寸的差异，并且所有碎片更容易被重新夹带，从而限制了沉积物的生长。这项工作证明了孔表面粗糙度和孔表面孔隙率对于微塑料和纳米塑料等胶体颗粒在排斥条件下沉积的重要性。