Natural organic matter (NOM) contains a large number of aromatic ketones and quinones, which can produce reactive oxygen species (ROS), such as ¹O₂ and HO·, through photosensitization. These ROS play important roles in the attenuation of organic pollutants in sunlit surface water. The NOM components fractionated with XAD-8 resin at different pH influence the photo-generation of ROS, which may be related to the degree of dissociation of functional groups. In this study, probe chemicals were used to investigate the effect of dissociation degree (pK_a) of NOM model compounds on ROS production under 254 nm UV irradiation. Experimental results showed that six model compounds with similar molecular weights and structures but different pK_a values have different ROS production abilities in a pH 7.0 reaction system. The ability for DHB_2,5 (2.97), DHB_3,4 (4.48), and GUA (9.99) to photo-generate ¹O₂ increased with increasing dissociation. The ability for DHB_3,4 and GUA to photo-generate HO· followed the same trend. The correlation between NOM dissociation constant and ROS generation is preliminary established, which explains the influence of functional groups. Our results may provide some basic information for understanding the correlation between NOM structural features and ROS generation.

天然有机物（NOM）包含大量的芳族酮和醌，它们可以通过光敏作用产生活性氧（ROS），例如¹ O ₂和HO·。这些ROS在减缓阳光照射的地表水中有机污染物中起重要作用。XAD-8树脂在不同pH下分馏的NOM组分会影响ROS的光生，这可能与官能团的解离程度有关。在这项研究中，使用探针化学试剂来研究NOM模型化合物的解离度（p K _a）在254 nm紫外线照射下对ROS产生的影响。实验结果表明，六个分子质量和结构相似但p K不同的模型化合物_一个值具有在pH 7.0的反应系统中的不同的ROS产生的能力。DHB _2,5（2.97），DHB _3,4（4.48）和GUA（9.99）光解¹ O _2的能力随着解离的增加而增加。DHB _3,4和GUA光生HO·的能力遵循相同的趋势。初步建立了NOM解离常数与ROS生成之间的相关性，这说明了官能团的影响。我们的结果可能为理解NOM结构特征与ROS产生之间的相关性提供一些基础信息。