Fu Xianshu, Pan Xiangliang, Chen Jun, Zhang Mingzhou, Ye Zihong, Yu Xiaoping
College of Environment, Zhejiang University of Technology, Hangzhou 310032, China.
Key Laboratory of Microbiological Metrology, Measurement & Bio-Product Quality Security, State Administration for Market Regulation, College of Life Sciences, China Jiliang University, Hangzhou 310018, China.
Molecules. 2025 Apr 2;30(7):1586. doi: 10.3390/molecules30071586.
Microplastics (MPs) are ubiquitous in aquatic environments, soils, and beach sediments, demonstrating a remarkable ability to adsorb dissolved organic matter (DOM). Although there are methods for extracting DOM from water, the approaches for directly extracting DOM from microplastics have not been thoroughly investigated, and the characterization of DOM adsorbed on microplastics is also insufficient. In this study, five different types of microplastic samples were collected from each of five environmental media (water and sediment), and finally 25 samples were obtained. This paper comparatively assessed the extraction efficiency of DOM from MPs with various solvents by using total organic carbon (TOC), culminating in the development of a sodium pyrophosphate-NaOH solution extraction method optimized for DOM. The morphology, material and environmental medium of microplastics were the three primary factors affecting the adsorption of DOM on microplastics, with the highest enrichment ratio of 1.4-1.8 times for extruded polyethylene microplastics (EPE-MPs) characterized by their porous structure in the flowing water environment. The molecular weight of DOM adsorbed on microplastics showed a multi-modal distribution pattern with great dissimilarities among the different environmental media. Gel permeation chromatography (GPC) indicated that the weight-average molecular weight () of DOM was 2750-4552 Da for river MPs, 2760-5402 Da for Qiantang River MPs, 1233-5228 Da for East China Sea MPs, 440-7302 Da for soil sediment MPs and 438-6178 Da for beach sediment MPs, respectively. Excitation-emission matrix-parallel factor analysis (EEM-PARAFAC) identified that tyrosine-like substances with high excitation in region IV and low excitation in region I were predominantly adsorbed on MPs, followed by tryptophan-like substances with low excitation in region II and protein-like substances in region IV, while humic- and fulvic-like substances in regions V and III, respectively, exhibited the least adsorption affinity. The findings underscored the critical need to comprehensively consider the interactions between MPs and DOM and their environmental impacts in pollution control strategies.
微塑料（MPs）在水生环境、土壤和海滩沉积物中普遍存在，具有吸附溶解有机 matter（DOM）的显著能力。虽然有从水中提取 DOM 的方法，但直接从微塑料中提取 DOM 的方法尚未得到充分研究，且对吸附在微塑料上的 DOM 的表征也不足。在本研究中，从五种环境介质（水和沉积物）中的每一种收集了五种不同类型的微塑料样本，最终获得了 25 个样本。本文使用总有机碳（TOC）比较评估了各种溶剂从 MPs 中提取 DOM 的效率，最终开发出了一种针对 DOM 优化的焦磷酸钠 - 氢氧化钠溶液提取方法。微塑料的形态、材料和环境介质是影响 DOM 吸附在微塑料上的三个主要因素，在流水环境中，具有多孔结构的挤出聚乙烯微塑料（EPE - MPs）的富集率最高，为 1.4 - 1.8 倍。吸附在微塑料上的 DOM 的分子量呈现多峰分布模式，不同环境介质之间差异很大。凝胶渗透色谱（GPC）表明，河流 MPs 的 DOM 的重均分子量（）为 2750 - 4552 Da，钱塘江 MPs 为 2760 - 5402 Da，东海 MPs 为 1233 - 5228 Da，土壤沉积物 MPs 为 440 - 7302 Da，海滩沉积物 MPs 为 438 - 6178 Da。激发 - 发射矩阵 - 平行因子分析（EEM - PARAFAC）确定，在区域 IV 中具有高激发且在区域 I 中具有低激发的类酪氨酸物质主要吸附在 MPs 上，其次是在区域 II 中具有低激发的类色氨酸物质和在区域 IV 中的类蛋白质物质，而区域 V 和 III 中的类腐殖质和类富里酸物质分别表现出最小的吸附亲和力。研究结果强调了在污染控制策略中全面考虑 MPs 与 DOM 之间的相互作用及其环境影响的迫切需求。
