Li Kun, Chen Zhangle, Hao Wanqi
School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing, 210044, China; Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, China.
School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing, 210044, China; Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, China.
Environ Pollut. 2025 Oct 15;383:126876. doi: 10.1016/j.envpol.2025.126876. Epub 2025 Jul 23.
As emerging microplastic pollutants, tire wear particles (TWPs) have unclear photochemical impacts on aquatic nitrogen cycles. This study investigated how three types of TWPs-mechanically generated via rolling (R-TWPs), sliding (S-TWPs), and low-temperature crushing (C-TWPs)-and their aged counterparts (AC-, AR-, AS-TWPs) influenced nitrate reduction in periphytic biofilms. Aging in lake water altered the surface properties of TWPs: AC- and AR-TWPs accumulated inorganic ions and organic coatings, while AS-TWPs facilitated microbial colonization. Aged TWPs exhibited enhanced electron exchange capacity (EEC) and elevated levels of environmentally persistent free radicals (EPFRs). However, neither fresh nor aged TWPs altered nitrate removal, denitrification gene abundance (nirK, nirS), or microbial community structure in a dose-dependent manner; their impacts showed no simple correlation with EEC or EPFRs. Under illumination, TWPs acted as electron shuttles, transferring photogenerated electrons. Quenching hydroxyl radicals (·OH) revealed a strong positive correlation between EEC (specifically, electron donating and accepting capacities) and nitrate removal rates (r = 0.928-0.957, p < 0.01). Variance partitioning analysis identified EPFRs as promoters (contribution: 0.16) and ·OH as inhibitors (contribution: -0.18) of denitrification. At concentrations of 1.0-50.0 mg L over 7 days, TWPs exerted paradoxical effects on urban river nitrogen cycling. This paradox arose from synergistic interactions between surface-active components (e.g., carbon black, zinc oxide) and photosensitive moieties (e.g., EPFRs, redox functional groups). This work highlights the dual role of photoactive TWPs in modulating aquatic nitrogen cycles and underscores the necessity of evaluating their photochemical reactivity and oxidative stress effects when assessing microplastic pollution in urban water systems.
作为新兴的微塑料污染物，轮胎磨损颗粒（TWPs）对水生氮循环的光化学影响尚不清楚。本研究调查了三种类型的TWPs——通过滚动机械产生的（R-TWPs）、滑动产生的（S-TWPs）和低温破碎产生的（C-TWPs）——以及它们的老化对应物（AC-、AR-、AS-TWPs）如何影响周丛生物膜中的硝酸盐还原。在湖水中老化改变了TWPs的表面性质：AC-和AR-TWPs积累了无机离子和有机涂层，而AS-TWPs促进了微生物定殖。老化的TWPs表现出增强的电子交换能力（EEC）和升高的环境持久性自由基（EPFRs）水平。然而，新鲜的和老化的TWPs都没有以剂量依赖的方式改变硝酸盐去除、反硝化基因丰度（nirK、nirS）或微生物群落结构；它们的影响与EEC或EPFRs没有简单的相关性。在光照下，TWPs充当电子穿梭体，转移光生电子。猝灭羟基自由基（·OH）揭示了EEC（特别是电子供体和受体能力）与硝酸盐去除率之间存在很强的正相关（r = 0.928 - 0.957，p < 0.01）。方差分解分析确定EPFRs是反硝化的促进剂（贡献：0.16），而·OH是反硝化的抑制剂（贡献：-0.18）。在7天内浓度为1.0 - 50.0 mg/L时，TWPs对城市河流氮循环产生了矛盾的影响。这种矛盾源于表面活性成分（如炭黑、氧化锌）和光敏部分（如EPFRs、氧化还原官能团）之间的协同相互作用。这项工作突出了光活性TWPs在调节水生氮循环中的双重作用，并强调在评估城市水系统中的微塑料污染时评估其光化学反应性和氧化应激效应的必要性。
