Department of Environment and Energy, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, South Korea.
Department of Environment and Energy, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, South Korea; K-water Institute, 200 Sintanjin-Ro, Daedeok-Gu, Daejeon 34350, South Korea.
Water Res. 2022 Aug 1;221:118806. doi: 10.1016/j.watres.2022.118806. Epub 2022 Jul 1.
Microplastic (MP) pollution in soil/subsurface environments has been increasingly researched, given the uncertainties associated with the heterogeneous matrix of these systems. In this study, we tracked the spectroscopic signatures of MP-derived dissolved organic matter (MP-DOM) in infiltrated water from MP contaminated sandy subsurface systems and examined their potential to form trihalomethanes (THMs) and haloacetic acids (HAAs) by chlorination. Sand-packed columns with commercial MPs (expanded polystyrene and polyvinylchloride) on the upper layer were used as the model systems. Regardless of the plastic type, the addition of MPs resulted in a higher amount of DOM during infiltration compared with the clean sand system. This enhancement was more pronounced when the added MPs were UV-irradiated for 14 days. The infiltration was further characterized using FT-IR and fluorescence spectroscopy, which identified two fluorescent components (humic-like C1 and protein/phenol-like C2). Compared with pure MP-DOM, C1 was more predominant in sand infiltration than C2. Further studies have established that C2 may be more labile in terms of biodegradation and mineral adsorption that may occur within the sand column. However, both these environmental interferences were inadequate for entirely expanding the spectroscopic signatures of MP-DOM in sand infiltration. The infiltration also exhibited a higher potential in generating carbonaceous disinfection byproducts than natural groundwater and riverside bank filtrates. A significant correlation between the generated THMs and decreased C1 suggests the possibility of using humic-like components as optical precursors of carbonaceous DBPs in MP-contaminated subsurface systems. This study highlighted an overlooked contribution of MPs in terms of the infiltration of DOM levels in sandy subsurface systems and the potential environmental risk when used as drinking water sources.
土壤/地下环境中的微塑料 (MP) 污染越来越受到关注，因为这些系统的非均相基质存在不确定性。在这项研究中，我们跟踪了源自 MP 污染沙地下系统渗透水中的 MP 衍生溶解有机物质 (MP-DOM) 的光谱特征，并研究了它们通过氯化形成三卤甲烷 (THMs) 和卤乙酸 (HAAs) 的潜力。使用商业 MPs（膨胀聚苯乙烯和聚氯乙烯）上层的砂填充柱作为模型系统。无论塑料类型如何，与清洁砂系统相比，添加 MPs 会导致渗透过程中 DOM 量增加。当添加的 MPs 经过 14 天的紫外线照射时，这种增强更为明显。使用傅里叶变换红外 (FT-IR) 和荧光光谱进一步对渗透进行了表征，该方法确定了两种荧光成分（类腐殖质 C1 和类蛋白质/酚类 C2）。与纯 MP-DOM 相比，C1 在砂渗透中比 C2 更为主要。进一步的研究表明，C2 在生物降解和矿物吸附方面可能更具易变性，而这些可能会在砂柱内发生。然而，这两种环境干扰都不足以完全扩展 MP-DOM 在砂渗透中的光谱特征。与天然地下水和河岸滤出液相比，渗透也显示出更高的生成碳质消毒副产物的潜力。生成的 THMs 与 C1 减少之间存在显著相关性，这表明在 MP 污染的地下系统中，可能可以使用类腐殖质成分作为碳质 DBPs 的光学前体。本研究强调了 MPs 在沙质地下系统中 DOM 水平渗透方面的被忽视的贡献，以及将其用作饮用水源时可能带来的潜在环境风险。
