The remnants of Chernobyl are still present in the Black Sea

Forty years have passed since Chernobyl, but Chernobyl-related radioactive contamination in the Black Sea has not ended. TENMAK’s research has revealed that the concentration of caesium-137 in the Black Sea is seven times higher than in the Mediterranean Sea.

BirGün Daily, Giriş: 07.11.2025 , https://www.birgun.net/haber/the-remnants-of-chernobyl-are-still-present-in-the-black-sea-667018

Nearly 40 years have passed since the Chernobyl disaster, considered one of the world’s three largest nuclear accidents, but the radioactive contamination caused by the accident continues to affect the Black Sea. At the IVth National Symposium on Monitoring and Assessment in the Seas, Dr Aysun Kılınçarslan, presenting on behalf of the Turkish Energy, Nuclear and Mining Research Institute (TENMAK), announced the results of monitoring studies on radioactive contamination in Turkey’s coastal waters and sediments.

Analyses conducted in coastal sediments between 2015 and 2023 detected high levels of caesium-137 and strontium-90. While an average of 21 becquerels of caesium-137 isotope per kilogram was observed in the Black Sea, this rate was recorded as only 3.2 becquerels in the Mediterranean Sea. Values that are relatively high in the Sea of Marmara decrease as one moves towards the Aegean and Mediterranean Seas. The highest value found in the analyses exceeds 82 becquerels. This figure is 10 times higher than the highest value observed in the Mediterranean Sea. When viewed on a regional basis, the highest caesium-137 value in sediments, 50 becquerels, was found in Hopa. Hopa is followed by Trabzon and Sinop.

HIGH FIGURES IN TRABZON AND HOPA

In measurements taken in coastal surface waters between 2014 and 2023, the caesium-137 concentration averaged 9 millibecquerels per litre in the Black Sea, while this figure dropped to 1.6 millibecquerels in the Mediterranean Sea. Rates in the Bosphorus, Marmara and Çanakkale ranged between 8.4 and 6.9 millibecquerels, while the amount of caesium-137 in the water decreased in the Aegean Sea, falling to 1.8 millibecquerels. The highest figures were found in Trabzon and Hopa, which have been affected by Chernobyl for years and where cancer rates have increased. Tekirdağ, Ordu, Karasu and İğneada stand out as other regions with high measurements. Although the study’s findings indicate that these levels do not pose a risk to human health or environmental pollution, the significant difference between the Black Sea and the Mediterranean clearly demonstrates the consequences of Chernobyl-related contamination.

CHERNOBYL FLOWS

Another noteworthy finding of the study was the detection of plutonium-239, which does not occur naturally and is produced by nuclear reactions, alongside caesium-137. While average values do not differ between seas, the locations most affected by this contamination include Erdek, the Bosphorus Strait, Hopa, and Sinop. Experts point out that the sources of contamination linked to these isotopes are nuclear power plant accidents, nuclear weapons tests, and operational nuclear reactors. Chernobyl is also cited as a source of contamination in the Black Sea. Radioactive pollution from the out-of-control melted reactor and the surrounding area reaches the Black Sea via groundwater and the Dnieper River.

MARINE ASSESSMENT IS NECESSARY

Prof. Dr. İnci Gökmen, who revealed high levels of radiation in tea after Chernobyl, points out that the radiation level detected at 21 becquerels per kilogram is quite high. Gökmen states that data collected from the seas and coasts also highlights the need to measure radiation levels in the soil, adding, “It is surprising to see plutonium in the seas, even at low levels. Strontium is not surprising. However, since strontium does not emit gamma radiation and must be measured by chemical separation, measurements were rarely taken despite the presence of strontium in the environment and food after Chernobyl. However, the strontium values immediately after the accident can be estimated from the current results. By looking at the caesium levels in coastal surface water in some areas, it would be good to calculate the doses that swimmers or those working at sea, such as fishermen, would receive. It would be appropriate to take measurements in fish, mussels and other seafood. Thirty-nine years have passed since Chernobyl. Caesium has only undergone one half-life. This means that radioactive elements will remain in the seas for a long time to come,” he said. WHAT IS CAESIUM (CS-137)?

The most common radioactive form of caesium is Cs-137. Caesium-137 is produced by nuclear reactions. External exposure to Cs-137 can cause burns, acute radiation sickness and even death. Exposure to large amounts of Cs-137 can result from the misuse of a powerful industrial Cs-137 source, a nuclear explosion, or a major nuclear accident. Under normal conditions, large amounts of Cs-137 are not found in the environment. Exposure to Cs-137 can increase the risk of cancer due to the presence of high-energy gamma radiation. Ingestion or inhalation of Cs-137 increases the risk of cancer by causing the radioactive material to spread to soft tissues, particularly muscle tissue. Vascular plants do not accumulate high levels of caesium through root uptake because caesium is strongly adsorbed to the soil. However, the accumulation of radioactive residues on flora with large surface areas, such as lichens or mosses, is significant. Animals that feed on these plants can consume large amounts of radiocaesium (and other radionuclides present in radioactive fallout). Human consumption of the meat of such animals leads to the uptake of these radionuclides into the body.

Note: This article is translated from the original article titled Çernobil’in izleri hâlâ Karadeniz’de, published in BirGün newspaper on November 7, 2025.