Organic matter (carbon) is ubiquitous in inland water and ocean and is the main carrier of material and energy in biosphere. It plays dominant roles in eco-systems health and water quality. Due to the heterogeneity and low concentration of aquatic organic matter (AOM), it is a great challenge to accurately and conveniently characterize its behaviors under realistic environmental conditions. Prof. Yan mainly focuses on exploring the quantum optical information in ultraviolet-visible spectrum of AOM; developing new techniques and instruments for characterizing the total amount, composition and activities of AOM based on its quantum optical information; and applying the novel approaches to observe and control AOM behaviors from molecular to global scale.