作者：Duan, C., Liu, F., You, J., Cao, Y. & Xu, H.

Natural colloidal particles (NCPs) are ubiquitous in lake ecosystems, whereas information on the photochemical production, distribution, and formation mechanism for hydroxyl radicals (center dot OH) from NCPs remains unknown. Herein, NCPs from different lake waters were extracted, with source- and concentration-dependent heterogeneities in formation potential, microheterogeneous distribution, and mechanism for center dot OH being explored. NCPs were composed of inorganic colloidal particles (ICPs) and organic colloidal particles (OCPs), and NCPs-mediated center dot OH was divided into free center dot OH and bound center dot OH. Results showed that, regardless of NCP sources and concentrations, apparent quantum yields of free center dot OH were 1.22-5.24 times lower than those of bound center dot OH, indicating high production potential and microheterogeneous distribution. It was indicated that ICPs primarily contributed to the production of bound center dot OH, while OCPs were the main components responsible for free center dot OH generation. Furthermore, water oxidation by valence band holes in ICPs acted as the primary pathway for bound center dot OH formation, while oxygen-mediated chain reactions driven by excited triplet states and superoxide anions contributed to free center dot OH formation. The microheterogeneous distribution of center dot OH exhibited distinct attenuation rates toward aquatic contaminants. This study highlights NCPs as important photochemical center dot OH sources that significantly influence the behaviors and fate of nutrients and contaminants in aquatic ecosystems.

天然胶体粒子（NCPs）普遍存在于湖泊生态系统中，然而关于NCPs光化学生成羟基自由基（·OH）的产生、分布与形成机制的信息尚属空白。本研究从不同湖泊水体中提取了NCPs，探究了·OH的生成潜力、微异质性分布及其机制的来源依赖性和浓度依赖性异质性。NCPs由无机胶体粒子（ICPs）和有机胶体粒子（OCPs）组成，NCPs介导产生的·OH分为游离态·OH和结合态·OH。结果表明，无论NCPs的来源和浓度如何，游离态·OH的表观量子产率均比结合态·OH低1.22–5.24倍，显示出高的生成潜力与微异质性分布。研究证实，ICPs主要贡献结合态·OH的生成，而OCPs则是游离态·OH产生的主要组分。此外，ICPs中价带空穴对水的氧化是结合态·OH形成的主要途径，而激发三重态和超氧阴离子驱动的氧介导链式反应则贡献于游离态·OH的形成。·OH的微异质性分布对水体污染物表现出明显不同的衰减速率。本研究揭示了NCPs是重要的光化学·OH来源，显著影响着水生生态系统中营养物和污染物的行为与归趋。

（来源：Environmental Science & Technology 2026  DOI: 10.1021/acs.est.5c14991）