Hydrochemical basis of productivity in the deep-water area of the White Sea

Data on the spatiotemporal variability of the principal nutrients (oxygen, phosphorus, all forms of nitrogen, and silicon) in the deep-water part of the sea in different seasons are presented. The principal changes in the contents of these nutrients in the photic layer are related to the seasonal variations of the intensity of the production-destruction processes. The high primary production (PP) in the spring-summer period causes a supersaturation of the waters with oxygen (103-115%) with minimum concentrations of the mineral forms of silicon, phosphorus, and nitrogen and the growth of their organic forms. At the same time, below the pycnocline, the concentrations of the mineral forms of these elements increase with depth. In the deep-seated layers, the distribution of mineral phosphorus and silicon is under a pronounced affect of the waters supplied from the Gorlo. Nitrogen in the deep waters exists mainly in organic forms, whereas phosphorus is in mineral forms. On the basis of the seasonal variations of the concentrations of nutrients, an estimation of the new PP is made and the great contribution of the PP provided by the recycling of nutrients to the productivity of the waters mentioned is revealed.