College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
Key Laboratory of Plant Nutrition and the Agro-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China.
Environ Sci Technol. 2024 Aug 6;58(31):13973-13985. doi: 10.1021/acs.est.4c04608. Epub 2024 Jul 24.
The fate of ubiquitous microplastics (MPs) is largely influenced by dissolved organic matter (DOM) in aquatic environments, which has garnered significant attention. The reactivity of DOM is reported to be greatly regulated by molecular weights (MWs), yet little is known about the effects of different MW DOM on MP aging. Here, the aging behavior of polystyrene MPs (PSMPs) in the presence of different MW fulvic acids (FAs) and humic acids (HAs) was systematically investigated. Under ultraviolet (UV) illumination, O/C of PSMPs aged for 96 h surged from 0.008 to 0.146 in the lower MW FA (FA) treatment, suggesting significant PSMP aging. However, FA exhibited a stronger effect on facilitating PSMP photoaging than HA, which can be attributed to the fact that FA contains more quinone and phenolic moieties, demonstrating a higher redox capacity. Meanwhile, compared to other fractions, FA was more actively involved in the increase of different reactive species yields by 50-290%, including •OH, which plays a key role in PSMP photoaging, and contributed to a 25% increase in electron-donating capacity (EDC). This study lays a theoretical foundation for a better understanding of the environmental fate of MPs.
普遍存在的微塑料（MPs）的命运在很大程度上受水生环境中溶解性有机质（DOM）的影响，这引起了人们的极大关注。据报道，DOM 的反应性受分子量（MWs）的极大调节，但对于不同 MW DOM 对 MP 老化的影响知之甚少。在这里，系统研究了不同 MW 富里酸（FA）和腐殖酸（HA）存在下聚苯乙烯 MPs（PSMPs）的老化行为。在紫外（UV）光照下，PSMPs 在低 MW FA（FA）处理下老化 96 h 后 O/C 从 0.008 飙升至 0.146，表明 PSMP 老化明显。然而，FA 比 HA 更能促进 PSMP 光老化，这归因于 FA 含有更多醌和酚部分，表现出更高的氧化还原能力。同时，与其他馏分相比，FA 更积极地参与增加不同活性物质的产量，增幅为 50-290%，包括在 PSMP 光老化中起关键作用的 •OH，并导致电子供体能力（EDC）增加 25%。本研究为更好地理解 MPs 的环境命运奠定了理论基础。
