Fluorescent Dissolved Organic Matter in Natural Waters

Dissolved organic matter (DOM), of allochthonous and autochthonous origin, is a heterogeneous mixture of organic compounds, with molecular weights ranging from less than 100 to over 300,000 Da in natural waters. The DOM components are involved into key biogeochemical processes such as global carbon cycle, nutrient dynamics, photosynthesis, biological activity and finally as energy sources in the aquatic environments. Among the DOM components, only a limited fraction of organic compounds show fluorescence properties. These compounds are termed the fluorescent DOM (FDOM). In the pioneering works conducted by Kalle and Duursma, the fluorescence of terrestrial humic substances served as a tracer of soil organic matter in freshwater and seawater environments. The fluorescence of humic substances has then been used to distinguish the mixing of river water with seawater as well as their sources.