中文摘要：

以氙灯为光源，研究了模拟日光照射下土霉素（oxytetracycline，OTC）的光解行为、机制，以及水中腐殖酸（humicacid，HA）对OTC光降解的影响。纯水中性条件下，OTC的光解主要是通过直接光降解，光解动力学符合准一级反应动力学，光解速率随初始浓度的增加而减小。来源于土壤的HA在低浓度（2mg·L-1）时促进OTC的光解，而高浓度HA（〉10mg·L-1）抑制OTC的光降解；来自Suwannee河的富里酸（Suwanneeriverfulvicacid，SRFA）抑制OTC的光降解。在HA和SRFA存在条件下，OTC主要的降解途径是单线态氧（1O2）和羟基自由基（·OH）参与的敏化光解。实验结果为了解四环素类抗生素在水体中的迁移转化机制提供了参考。

英文摘要：

The photochemical degradation of the antibiotic oxytetracycline （OTC） in aqueous solution was investigated under the simulated solar light irradiation. The photolytic kinetics of OTC in pure water was studied as a function of initial concentration （C0）. A linear plot of the pseudo~first-order rate constant vs. Co was observed with a negative slop. Dissolved organic matter was found to influence OTC degradation. Low concentration of soil-derived humic acid （HA） promoted OTC degradation, and high concentration of HA inhibited OTC degradation~ Suwannee river-derived fulvic acid （SRFA） decreased OTC degradation with any concentrations. It was found that, in the presence of HA and SRFA, OTC degradation processed the self-sensitization degrada- tion where singlet oxygen and hydroxyl radical participated. These results are helpful for better understanding the photochemical process of antibiotics in the water environment.