The Northern zone of the Black sea rapidly desalinate for 6 years due to the discharge of fresh water from the Dnieper, says Alexey Khobot, a representative of the Institute of ecology and nature. The decision of the government of Ukraine to refuse to supply water to the Crimean Peninsula, which came under Russian control in 2014 and to dump fresh water into the sea has already led to a significant change in the composition of water and affected the biosphere. In the future, Alexey Khobot emphasizes, an irreparable environmental disaster may occur.
The North Crimean canal, which has supplied fresh water to the Crimean Peninsula since the Soviet era, had a capacity of 695.3 million m3 of water annually. Now this volume merges into the Karkinit Bay, where the change in the color of the water is visible even from space.
Fresh water
The Black sea is home to about 2,000 species of animals, 100 species of underwater plants and 270 species of bottom-dwelling multicellular algae, recalls Alexey Khobot. In the last four years, researchers of the Black sea have identified a crisis in the environmental situation: the chemical composition of the water shows significant pollution, and biological diversity is decreasing. The marine ecosystem is under significant stress, which leads to a loss of self-cleaning capability.
The biggest negative factor, says Alexey Khobot, is the hundreds of millions of cubic meters of water flowing into the Karkinit Bay.
“Until 2014, Ukraine provided 85% of Crimea’s needs for drinking and fresh water. Now deliveries are stopped, the Ukrainian side cannot use the released volume of water, so the water is simply drained,“ explains Alexey Khobot.
The discharge of fresh water from the Dnieper into the sea causes desalination, marine biological diversity suffers, and marine animals disappear. Redirecting the flow of water from the mouth of the North Crimean canal through fields in southern Ukraine has caused an increase of the agricultural chemical pollution come to sea along with the Dnieper water.
In this regard, Alexey Khobot emphasizes, the state of feeding areas for red book sturgeon, as well as other black sea endemic fish, in particular, Kalkan, has deteriorated.
“The worst thing is that a cascading process of changes has been launched. In the place of fresh water discharge, a rapid proliferation of blue-green algae that absorb oxygen has begun out of the water. The oxygen content in the water is now 2.13 mg per 1 liter of water, which is 2-2. 5 times less than the norm. Oxygen starvation causes mass death of fish, which further pollutes the water and again reduces the amount of oxygen in the water,” warns Alexey Khobot.
The following can be said about the scale of fish deaths: in 2008-2013, the Black sea produced an average of 38.3 thousand tons of fish per year, in 2016 – about 4 thousand tons.
Dead bottom
The black sea has its own unique specifics, says Alexey Khobot. The water column of the Black sea, in addition to the thermocline, divided into several special layers that do not mix with each other.
“The thin surface layer of the sea is rich in oxygen and organic substances. It is here that all the diversity of the black sea fauna is concentrated. But starting from a depth of 100 meters, there is a decrease in the amount of dissolved oxygen, and from about a depth of 200 meters, the Black sea is a toxic hydrogen sulfide environment,” explains Alexey Khobot.
According to experts, amount of the hydrogen sulfide in the Black sea is about 3 billion tons – more than any other sea on the planet. Accumulations of hydrogen sulfide also found in oceanic depressions, but nowhere is there such a large number of people inhabiting the shores of the reservoir, as in the case of the Black sea coast, emphasizes Alexey Khobot.
The reasons that led to the emergence of a huge mass of hydrogen sulfide actively discussed by scientists. However, the most well-reasoned version is the emergence of hydrogen sulfide as a product of decomposition of organic residues.
“The source of organic matter in this case is not so much the animal world of the Black sea as the anthropogenic load on the reservoir. Draining fresh water leads to the death of marine life, and this, in turn, dramatically increases the formation of hydrogen sulfide,” explains Alexey Khobot.
Hydrogen sulfide and methane, which is present in the lower layers of the Black sea, rarely come to the surface. One large-scale case was reliably recorded. This happened in 1927 during the Crimean earthquake, when due to fluctuations in the earth’s surface, the balance between the layers was disturbed and a gas cloud burst out. Eyewitnesses smelled a strong smell of hydrogen sulfide, also observed a huge flame above the surface of the sea. During the earthquake there was a thunderstorm, from which, in all probability, the gases that rose to the surface caught fire.
“It is unlikely that the discharge of fresh water into the Black sea will cause the sea to blow up in one of the thunderstorms. But cases of poisoning of marine life are increasingly noted in the shallow part of the sea, which means that the oxygen-free zone is expanding,” warns Alexey Khobot.
The problem of desalination of the Black sea, especially its Northern region, is getting worse every day, Alexey Khobot is sounding the alarm. According to the ecologist, in the coming years, the Black sea may become the “second Dead sea” if nothing to do.
