The reason for the formation of hydrogen sulfide in the Black Sea.

The wind waves enrich the water with oxygen only to a depth of several tens of meters of the seas and oceans surface, while the whirlpools deliver the water enriched with oxygen to a depth of more than 10 km. (Mariana Trench)  How does this happen:

The waters of the lakes, seas and oceans of the northern hemisphere rotate counterclockwise, and the waters of the southern hemisphere rotate clockwise, forming giant whirlpools. https://en.m.wikipedia.org/wiki/Ocean_gyre

As is known, everything that rotates, including whirlpools, has the property of a gyroscope (whirligig) to maintain the vertical position of the axis in space, regardless of the rotation of the Earth.

If you look at the Earth from the side of the Sun, the whirlpools, rotating with the Earth, overturn, due to which the whirlpools precess, resulting in a vertical movement of ocean water. http://goo.gl/AM5g1s

The presented theory can easily be verified by relation between the oxygen content and the whirlpools rotation speed.  Based on the map of the depths and currents of the seas and oceans.  The higher the current velocity, the greater the oxygen content and the lower the hydrogen sulfide content. https://youtu.be/ihM1I5r_MUg https://youtu.be/X6PavdKXIE8

List of seas with low oxygen content:  Black Sea. East of the Mediterranean. Gulf of Mexico. Norway fjords.  As we see, whirlpools are involved not only in the horizontal circulation of the sea and ocean waters, but also in the vertical. https://en.m.wikipedia.org/wiki/Deadzone(ecology) https://www.scientificamerican.com/article/ocean-dead-zones/

The coefficient of oxygen content can be expressed mathematically by the following formula O = V / G V - whirlpool rotation speed, km / h. G - depth of the reservoir, km. Black Sea 0.2 / 1200 = 0.00016 Sea of Okhotsk 1/800 = 0.0012

Vertical movement of ocean waters can be convincingly modeled using simple experience. For this, a half-filled vessel with a rotating liquid (bucket, tumbler, mixer) must be rotated around itself (in orbit). If the liquid in the bucket rotates to the right, the bucket around itself (in orbit) must be rotated to the left.

Continued. Forum. National Research Nuclear University MEPhI <a href="https://mephi.ru/communication/forum/talk/forum13/topic5498/messages/ ">https://mephi.ru/communication/forum/talk/forum13/topic5498/messages/  Forum Federal Target Program "World Ocean" http://okeany.com/forum/570.htm Cambridge University Forum https://www.thenakedscientists.com/forum/index.php?topic=73127.0