On the structure of the zone of interaction of aerobic and anaerobic waters of the Black Sea on the basis of measurements with a membrane-free sensorof oxygen

High reproducibility and sensitivity of the open (membrane-free) oxygen sen sor of measurements in the zone of interactions of aerobic and anaerobic wa ters allowed us to obtain some new data on the zone structure. The interact ion zone is shown to be subdivided into two parts: the upper-subaerobic-par t about 15 m thick with an oxygen content of 0.5-0.1 ml/l, where the layer of relatively transparent water is formed; and the lower-subanaerobic-one 1 5-25 m thick with an oxygen content of less than 0.03 ml/l, where the deep- seated layer of turbidity is formed. The zone of coexistence, where the oxy gen content at the boundary of the deep hydrogen sulfide layer would not ex ceed 0.03 ml/l, was not registered. The pronounced variability of the O-2 c ontent and distribution profile in the subaerobic zone is shown. The nonsta tionary character of physical and/or chemical processes occurring in the zo ne is presumed.