Modelling nitrogen fluxes in a semi-enclosed environment (the Black Sea): transport versus biogeochemical processes and quantification of the exchanges at the shelf break

A three-dimensional coupled biogeochemical-hydrodynamical model has been developed to get a better understanding of the biogeochemical functioning of the Black Sea. The in?uence on the ecodynamics of hydrodynamical and biogeochemical processes is quantified. Nitrogen inputs from the rivers, from the sediments and from the deep sea are estimated and compared in terms of potential fertilization. The exchanges between the north-western shelf and the deep sea are quantified. The results illustrate a highly complex spatial variability of the phytoplankton annual cycle and thus, stress the importance of using a 3D model to capture the essential physical-biological interactions that explain the data.