Russia (bbabo.net), - Scientists from the Institute of Biology of the Southern Seas (FITS IBSS) of the Russian Academy of Sciences have identified zones in the coastal waters of the Black and Azov Seas where the concentration of radioactive strontium-90 has increased. This may be due to the blocking of the North Crimean Canal, said Natalya Mirzoeva, head of the Department of Radiation and Chemical Biology, Leading Researcher of the Federal Research Center of the InBYuM RAS.

The data was obtained in 2021 during the voyages of the Professor Vodyanitsky research vessel and land expeditions.

“In 2021, new areas of the Black and Azov Seas potentially critically contaminated with strontium-90 were identified,” Mirzoeva said. - In the Sea of ​​Azov, this is the water area of ​​the Sivash Bay, in the Black Sea - the apex of the Karkinitsky Bay, where the concentration of strontium-90 in sea water is 180 times higher than the level that was before the accident at the Chernobyl nuclear power plant.

Scientists have established that radionuclides released into the environment during the accident in 1986 continue to flow with the waters of the Dnieper into the Azov-Black Sea basin. In the Sea of ​​Azov, immediately after the closure of the North Crimean Canal (NCC), there was a "calm", no excesses of radionuclides were observed. However, 3 years and 7 months after the closure of the SCC, in mid-2018, scientists recorded secondary pollution of the waters of the Sea of ​​Azov with strontium-90.

“When the North Crimean Canal was operating, we periodically recorded an excess of the pre-accident level of cesium-137 and strontium-90 in the Kerch region, which was the main consumer of the Dnieper water, as well as in the northwestern part of the peninsula, in the Karkinitsky Bay,” says Natalia Mirzoeva. - Now the Dnieper water is flooding the territory of the Kherson region, we see reports of this in the media. Pollutants are likely to enter groundwater and from there into the Sea of ​​Azov. But we do not have exact data, we cannot get to these territories and explore them.

In 2021, employees of the Department of Radiation Chemical Biology and the Laboratory of Phytoresources of the IBSS during a joint land expedition to the apex of the Karkinitsky Bay received data on a high level of sea water pollution with strontium-90. According to Mirzoyeva, these indicators will still be checked, but they indicate that the Dnieper is carrying radioactive substances. This may be due to the fact that since 2010, the Chernobyl NPP began to drain the cooling pond, which stood in the way of radioactive substances during the accident. Water from it is discharged into the Pripyat and the cascade of the Dnieper reservoirs, and then enters the Black Sea.

The excess of the pre-accident level of strontium-90 was also recorded in the center of the western part of the Black Sea, where this radionuclide is transported by currents from the northwestern region of the sea. Further, with water masses, pollutants are carried throughout the sea.

In 2021, a new problem has been identified - plutonium-241 and its decay product - americium-241. Examining bottom sediments in the deep part of the Black Sea, scientists found that plutonium entered the water area mainly as a result of global radioactive fallout (after nuclear tests in the 1950s and 60s, radioactive substances entered the troposphere and spread throughout the globe, falling out with precipitation) , and about 10 percent of plutonium radioisotopes ended up in the Azov-Black Sea basin after the Chernobyl accident. And now, as a result of the decay of plutonium-241, natural environments are contaminated with americium-241.

“Plutonium-241, with a half-life of about 14 years, gives rise to americium-241, which has a half-life of more than 430 years,” says Mirzoyeva. - Its concentration is still small, but it will increase. We will continue to observe this process by studying the bottom sediments of the sea, where the main amount of plutonium-241 radioisotopes is concentrated.

Mirzoeva stressed that the concentration of all detected radionuclides did not exceed the normative levels adopted in the Russian Federation. The obtained research results can also be used in case of accidents and releases of various substances, they will help to predict the consequences and make decisions in case of a threat of pollution of the Black Sea waters.

Meanwhile

In 2021, the R/V "Professor Vodyanitsky" for the first time used the acoustic method developed in the Department of Radiation Chemical Biology of the Federal Research Center of the InSBYuM to determine the bioproductivity of the Black and Azov Seas, in particular, to study the mass commercial fish species. For this, an echo sounder installed on the ship, purchased with funds from the Russian Foundation for Basic Research, was used. The method allows you to estimate the number of commercial fish without harming the ecosystem, unlike the traditional trawling method.

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