Abstract: Natural organic matter is susceptible to light-induced photochemical reactions, such as photodegradation, photodissolution, photobleaching and photomineralization, which induce the breakdown of large molecules and provide a substantial pool of photoproducts of environmental and biological significance. These photochemical behaviors not only enhance the biogeochemical cycles of bioelements and the migration of heavy metals and organic pollutants, but also change the structure and function of aquatic ecosystems. In this paper, the research progress published to date on photochemical reactions of natural organic matter in water was reviewed, including the basic concepts, reaction mechanisms and updated research techniques. It also made an exposition of ecological and environmental significance of the photochemical reactions. However, the previous researches could not represent complex photochemical reactions comprehensively and veritably because of the single experimental condition and research object, so it was suggested to model ecological process and study the response of interactions between dissolved organic matter and multiple contaminants under light irradiation, contributing to make the photochemistry research more thorough and systemic.

Key words: natural organic matter, photochemical reaction, photodegradation, photodissolution, biogeochemical cycle