Cerium dioxide nanoparticles (CeO₂ NPs) are ubiquitous in the water environment due to the extensive commercial applications. The complexity of heterogeneous humic acid (HA) plays a significant role in affecting the physicochemical properties of CeO₂ NPs in aqueous environments. However, the effects of light intensities and HA fractions on the interaction mechanism between CeO₂ NPs and HA are poorly understood. Here, we provided the evidence that both light intensities (>3 E L⁻¹ s⁻¹) and molecular weights (>10 kDa) can effectively affect the interactions between CeO₂ NPs and HA. The absolute content of reactive oxygen species (ROS) and quantum yield (Φ) of ³HA* were inhibited when HA (10 mg of C L⁻¹) interacts with CeO₂ NPs. However, they were positively correlated with the increasing irradiation time and simulated sunlight intensities. High molecular weights of HA fraction (>100 kDa) restrained the ROS generation and Φ of ³HA* due to surface adsorption between HA and CeO₂ NPs blocking reactive sites, competitive absorption for simulated sunlight. Fourier transform infrared and three-dimensional excitation-emission matrix fluorescence spectroscopy confirmed that the carboxylic groups of HA have high complexation capacity with CeO₂ NPs. These findings are essential for us to improve the understanding of the impacts of HA on CeO₂ NPs under different conditions in natural waters.

由于广泛的商业应用，二氧化铈纳米颗粒（CeO ₂ NPs）在水环境中无处不在。异质腐殖酸（HA）的复杂性在影响水性环境中CeO ₂ NP的理化性质方面起着重要作用。然而，光强度和HA分数对CeO ₂ NP和HA之间相互作用机制的影响知之甚少。在这里，我们提供的证据表明，光强度（> 3 E L ^-1  s ^-1）和分子量（> 10 kDa）均可有效影响CeO ₂ NP与HA之间的相互作用。活性氧的绝对含量（ROS）和量子产率（Φ）为³当HA（10 mg CL ^-1）与CeO ₂ NPs相互作用时，HA *被抑制。然而，它们与增加的辐照时间和模拟的日照强度呈正相关。高分子量的HA组分（> 100 kDa）抑制了³ HA *的ROS生成和Φ，这是因为HA和CeO ₂ NP之间的表面吸附阻止了活性位点，从而竞争了模拟太阳光的吸收。傅里叶变换红外和三维激发发射矩阵荧光光谱证实，HA的羧基与CeO ₂ NPs具有很高的络合能力。这些发现对我们增进对HA对CeO ₂影响的理解至关重要。 天然水中不同条件下的NP。