Alimi Olubukola S, Claveau-Mallet Dominique, Lapointe Mathieu, Biu Thinh, Liu Lan, Hernandez Laura M, Bayen Stéphane, Tufenkji Nathalie
Department of Chemical Engineering, McGill University, Montreal, Quebec, H3A 0C5 Canada; Department of Civil and Environmental Engineering, University of Alberta, Edmonton, T6G 1H9 Canada.
Department of Chemical Engineering, McGill University, Montreal, Quebec, H3A 0C5 Canada; Department of Civil, Geological and Mining Engineering, Polytechnique Montreal, 2900 Edouard-Montpetit, Montreal, Canada.
J Hazard Mater. 2023 Oct 5;459:131855. doi: 10.1016/j.jhazmat.2023.131855. Epub 2023 Jun 14.
In this work, we probed the changes to some physicochemical properties of polystyrene microplastics generated from a disposable cup as a result of UV-weathering, using a range of spectroscopy, microscopy, and profilometry techniques. Thereafter, we aimed to understand how these physicochemical changes affect the microplastic transport potential and contaminant sorption ability in model freshwaters. Exposure to UV led to measured changes in microplastic hydrophobicity (20-23 % decrease), density (3% increase), carbonyl index (up to 746 % increase), and microscale roughness (24-86 % increase). The settling velocity of the microplastics increased by 53 % after weathering which suggests that UV aging can increase microplastic deposition to sediments. This impact of aging was greater than the effect of the water temperature. Weathered microplastics exhibited reduced sorption capacity (up to 52 % decrease) to a model hydrophobic contaminant (triclosan) compared to unaged ones. The adsorption of triclosan to both microplastics was slightly reversible with notable desorption hysteresis. These combined effects of weathering could potentially increase the transport potential while decreasing the contaminant transport abilities of microplastics. This work provides new insights on the sorption capacity and mobility of a secondary microplastic, advances our knowledge about their risks in aquatic environments, and the need to use environmentally relevant microplastics.
在这项工作中，我们使用一系列光谱、显微镜和轮廓测量技术，探究了一次性杯子产生的聚苯乙烯微塑料因紫外线老化而导致的一些物理化学性质的变化。此后，我们旨在了解这些物理化学变化如何影响模型淡水中微塑料的迁移潜力和污染物吸附能力。暴露于紫外线导致微塑料疏水性（下降20 - 23%）、密度（增加3%）、羰基指数（增加高达746%）和微观粗糙度（增加24 - 86%）发生可测量的变化。老化后微塑料的沉降速度增加了53%，这表明紫外线老化会增加微塑料向沉积物的沉积。这种老化的影响大于水温的影响。与未老化的微塑料相比，老化后的微塑料对模型疏水性污染物（三氯生）的吸附能力降低（下降高达52%）。三氯生在两种微塑料上的吸附略有可逆性，具有明显的解吸滞后现象。这些老化的综合影响可能会增加微塑料的迁移潜力，同时降低其污染物传输能力。这项工作为次生微塑料的吸附能力和迁移性提供了新的见解，推进了我们对其在水生环境中风险的认识，以及使用与环境相关的微塑料的必要性。
