VERTICAL CHEMISTRY OF THE THREE DYNAMICALLY DIFFERENT REGIONS OF THE BLACK SEA

Vertical chemistry of the three dynamically different regions of the Black Sea

Özden Baştürk, Süleyman Tuğrul, İlkay Salihoğlu

Middle East Technical University, Institute of Marine Sciences (IMS-METU), Erdemli Icel, TURKEY

Abstract

In the upper layer of the Black Sea, the vertical distributions of nutrients and dissolved oxy’gen display very characteristic features at specific density surfaces. Moreover, data from a survey in September 1991 indicate that the positions and magnitudes of these properties show small regional differences from the core of the cyclonic gyres towards the anticyclonic eddies established in the coastal regions. The nutricline always appeared at shallower depths but at greater density surfaces within the cyclonic gyres. The molar ratios of N:P reached peak values of as much as 100 at the upper boundary of the nitracline due to a consistent shift between the onsets of the nitracline and the phosphocline. The subsurface phosphate mininium is a permanent feature of the cyclonic regions; however, it almost disappears in the meandering rim current, yielding lower concentrations at the depth of the deep phosphate maximum coinciding with the onset of the sulphidic waters.

Keywords: Black Sea, chemical properties, upwelling, downwelling, rim current