Phosphorus Fluxes in the Pelagic Zone of the Black Sea

Abstract

On the basis of these long-term observations of hydrophysical, hydrochemical and biological structure of water the seasonal variability of the upward, regeneration, sedimentation and fluxes of phosphorus from external sources in the photosynthetic zone in the deepwater area of the Black Sea was established. The estimates of the contribution of upward and regeneration fluxes of phosphorus in its total flux into the photosynthetic zone and sedimentation removal in some months urea are obtained. The relationship between the monthly averages of the rising contribution of phosphorus flux and its concentration chlorophyll “a” and biomass of phytoplankton in photosynthesis zone was established. Potentially possible values of the “new”, regeneration and total phytoplankton production in the deepwater area of the Black Sea are calculated. The correspondence between the annual estimates of primary production, calculated on the flux of phosphorus and averaged data of direct measurements of phytoplankton production in the deepwater area of the Black Sea is shown. It was found that the average annual value of the upward flux of phosphorus in the photosynthesis zone is equivalent to the average value of its sediment flux, indicating that the balance of the phosphorus cycle and absence of human influence on the level of primary production in the deepwater area of the Black Sea. The results are discussed in terms of the general laws of formation of the “new” and the regeneration of the primary production.