The general objective of this project is to support ongoing research on carbon and nitrogen dynamics in aquatic systems. Covering more than 2/3d of Earths surface, aquatic ecosystems are probably the most important systems of the world. They are key-players in the control of global climate, global elemental cycles and world biodiversity. In these aquatic systems, elemental cycles, and especially the cycles of biological elements (C, N, P, O, H, trace metals), are one of the major control factors of Earth's production with large repercussions on atmospheric chemistry (O2 and CO2), and their alteration due to anthropogenic activities can influence the whole ecosystem productivity with cascading side effects such as, for example, eutrophication, ocean acidification, biodiversity loss, ... Studying and understanding these cycles, and more important, determining their major controlling factors is thus of major importance.