Evaluating excitation-emission matrix for characterization of dissolved organic matter in natural and engineered water systems: Unlocking submerged secrets

Dissolved organic matter (DOM) is ubiquitous in waters and plays a fundamental role. The examination of DOM properties and their environmental effects, including intrinsic biogeochemical processes and the impact of DOM on the transformation and fate of other contaminants, is of paramount significance. Among the techniques available for DOM characterization, the fluorescent excitation-emission matrix (EEM) stands out as one of the most powerful methods, due to its speed, high sensitivity, and wealth of molecular information provided. This review encapsulates the principles of EEM-based methodologies for DOM interpretation, then critically summarizes DOM characterization in natural waters, and wastewater, as well as the water and wastewater treatment processes. Various scientific issues related to DOM, such as its physicochemical and biochemical properties, spatial and temporal distribution, transformation, removal, and environmental implications, can be discerned using EEM. Finally, the limitations and challenges, as well as the potential advancements and perspectives on EEM collection and analytical tools are discussed, broadening the application scope and utilizing theoretical simulation for mechanism investigation. This review serves as a beneficial guide to selecting suitable EEM-related strategies, facilitating an in-depth understanding and forecasting of the environmental behaviors of DOM in both natural and engineered water systems.