Abstract: Photochemical degradation is typically treated as a removal mechanism of marine dissolved organic matter(DOM).However,DOM photodegradation kinetics in different aquatic environments have not been well documented.Natural solar radiation experiments of DOM collected from Jiulong estuary,Xiamen Bay and highly-polluted urban Yundang Lagoon were conducted based on the absorption and fluorescence spectroscopy.An excitation-emission matrix and parallel factor analysis revealed three humic-like(C1,C2 and C5)and three protein-like(C3,C4 and C6).The results showed that the chromophoric dissolved organic matter(CDOM)in water samples from urban lagoon and Xiamen Bay was photodegraded more easily than that from Jiulong estuary.The higher proportion of protein-like components in sewage reflects the influence of human activities on the DOM composition of sewage in urban lagoons.After 6 days of light culture,the C1~C5 components degraded by 40.1%~78.8%,while the active humus-like components and the tryptophan-like components were preferred to degradation.This study revealed the diverse dynamics and composition change of DOM during solar radiation experiments in different aquatic environments,implied that photodegradation was an effective remediation way for organic pollution in polluted water.