Aden and water from the Persian Gulf participate in this subsurface 

 circulation. In the southeastern part of the Arabian Sea the sub- 

 surface flow has a southern direction and crosses the Equator into 

 the eastern part of the ocean. At approximately JO°Fa.st part of the 

 circulation bends eastward and continues on into the Bay of Bengal. 

 Layer of Minimum Oxygen . The tropical subsurface layer of minimum 

 oxygen has been described in reports of the John Murray Expedition''' 

 of 1933-3^' Of all tropical seas this layer is most pronounced in 

 the Arabian Sea v^here the oxygen content almost disappears at mid- 

 depth. The Russian vessel Vityaz reported a complete lack of oxygen 

 from a depth of 250 meters to the bottom (832 meters) in parts of 

 the northeast sector. The low oxygen content also extends to the 

 surface and the pH content^ having the sajne distribution pattern as 

 Og, reaches the smallest values in the Arabian Sea (j.6k - J.6j). 

 Another peculiarity of this sea is the existence of HgS in the 

 intermediate waters over an extensive area. An earlier expedition 

 of the vessel Mabahiss had reported HgS in the near-bottom layer 

 near the entrance of the Gulf of Oman and near Bombay. 



The layer of minimum oxygen is most usually found in the 

 northern part of the Arabian Sea at a depth of 75 meters, but toward 

 the Equator it descends to a depth of 150 meters. According to 

 Schott^ the layer of minimum oxygen is most pronounced off Bombay, 

 where it is generally found at the depth of 50 meters. Although 



^ The John Murray Expedition 1933-3^ ^ Scientific Reports, I 

 (Londonl 1935)' 



^P.L. Bezriikov, "Investigations in the Indian Ocean on the 

 33rd Cruise of the Expeditionary Vessel Vityaz," Trans. 

 Okeanologiya , Vol. 1, No. h (Moscow: I961). 



^G. -Schott, Geographie des Indischen und Stillen Ozeans 

 (Hamb urg : Boys e n, 1935)- 



10 



