IMIS

The net supply of N displays a small seasonal variation, while the net supply of P exhibits both a spring maximum and a winter minimum. The seasonal nutrient turnover cycle is estimated from the residual of the net supply and the seasonal variation in nutrient pools. Net release of DIP from the sediment takes place during late summer and winter, while net release of DIN occurs mainly during winter. Thus, the net release from the sediment adds to the pool of nutrients available for the spring bloom in the Baltic entrance the following year. Both advection and the autumn–winter release of P exceed the land load of P. Thus, on a short time-scale, reductions in P load cannot be expected to significantly change the availability of P for biogeochemical processes. However, the monthly N load from land and atmosphere exceeds the advective supply. Reductions in N load thus have a significant influence on availability of N for biogeochemical processes.