After the accident at Chornobyl Nuclear Power Plant, research in the exclusion zone was concerned primarily with the effects of radiation on humans. And this is quite natural because it was vitally important to assist the liquidators of the accident, residents displaced from the contaminated areas, as well as to monitor health of people who returned to the exclusion zone.
And only relatively recently have scientists ‘reached out’ to research the effects of radiation on other living organisms – plants, fish, etc. Researchers from the Institute of Hydrobiology of the National Academy of Sciences of Ukraine carried out this kind of research supported with grant funding from the National Research Foundation of Ukraine. The project ‘Comprehensive assessment of the radiation hazard of nuclear heritage sites for aquatic ecosystems’ was successful in the call ‘Support for Research of Leading and Young Scientists’.
Dmytro Gudkov, Head of the Aquatic Radioecology Department of the Institute, a corresponding member of the National Academy of Sciences of Ukraine, and PI of the project, confirms that the topic of long-term irradiation of aquatic organisms in the Chornobyl zone has not been studied enough. Therefore, his team decided to investigate how radiation affects groups of aquatic organisms and the ecosystem as a whole, what changes occur on the genetic level, in the hematopoietic system, etc.
“The modern global strategy for radiation security provides not only for the protection of people but also for the preservation of the biota,” said Dmytro. “And it is not only necessary to study the impact on different types of plants or animals, but it is also essential to prove that they are safe.”
Another reason why the researchers decided to carry out this large-scale project is lack of standards in the field of environmental radiation security in Ukraine. These standards should determine which levels of exposure of various representatives of the biota are safe and which are not.
According to the project PI, it is impossible to borrow the standards approved by the International Atomic Energy Agency (IAEA).
“International standards were developed primarily based on the results of acute (short-term, but powerful) exposure,” explains the researcher. “They are developed based on the results of experimental studies of certain representatives of the animal and plant world in laboratory conditions. But the problem is that the species diversity of living organisms (and their sensitivity to the influence of ionizing radiation) is much wider than the list of species that were used in the development of these standards. In addition, long-term exposure of biota in natural conditions for decades causes much more serious consequences.”
That is why the data obtained in natural conditions are very important. Based on them, it will be possible to develop more realistic standards that will take into account exposure in natural conditions after radiation accidents and emergencies at nuclear fuel cycle enterprises. “The final part of our project is development of recommendations for the creation of such standards in accordance with Ukrainian legislation and international radiation safety standards,” Dmytro added.
Before the war, researchers had managed to complete about 60% of the planned tasks. In particular, modern equipment had been purchased. Before that, according to the project PI, researchers of the department used to work mainly with old equipment, which had long been due for a ‘well-deserved rest’. In particular, a modern Zeissian microscope, a binocular, a hem analyzer for measuring animal blood samples, and a beta energy spectrometer for analyzing the content of radionuclides in environmental samples without lengthy sample preparation were purchased.
By the way, the results of the analysis showed that the disorders in the hematopoietic system of fish are quite serious, in particular, there are numerous deformations of erythrocytes, and the leukocyte formula is disturbed. An increased level of damage to chromosomes in aquatic plants and mollusks is observed, and a decrease in the reproductive performance of fish and plants is registered. Thus, problems in the ecosystem of reservoirs in Chornobyl Exclusion Zone exist, and it is high time to pay attention to them.
Before the war, researchers had managed to conduct four expeditions to the exclusion zone. The expeditions were accompanied by ichthyologists, botanists, and specialists in benthic invertebrate. A huge amount of work had to be done during each of the expeditions. In particular, the researchers collected samples of water, bottom sediments, aquatic plants, fish, and mollusks, performed sampling of fish blood and plant tissues for genetic analysis, carried out field measurements of several parameters of the water environment, radiation level, etc.
The following expedition was to have taken place in the early spring of 2022. The researchers expected to callect fish samples before spawning, to conduct a series of experiments with plants. The war prevented implementation of these plans.
Researchers are now closely monitoring every message from the exclusion zone. They understand: it will not be possible to go there until the territory is completely demined. “In addition, the russian occupiers ransacked the Central Analytical Laboratory in Chornobyl, based on which monitoring of the exclusion zone used to be carried out,” Dmytro continues. “All computers were smashed and databases that Ukrainian researchers had been collecting for years were destroyed, unique equipment was damaged…”
We ask the Professor: what were the first months of the war like for the project team?
The researcher said that the first weeks of the full-scale invasion were ‘hot’ for the institute’s researchers. The institution is located on Obolon in Kyiv, and there, on the northern outskirts of the city, it was most dangerous. One day, an enemy armored personnel carrier broke to the avenue where the institute is located, but the defenders of the city destroyed it.
In the first days after the start of the full-scale invasion, the radiation unit in the basement of the department was converted into a shelter. When the subway was closed, most researchers went into remote work mode.
“Today, a significant part of the project team members work outside Kyiv or abroad, one is fighting in the Armed Forces”, the researcher added. “I really hope that after the victory, the early-career researchers (our team includes three leading researchers and seven young ones) will be able to return and continue their work. The results of this research are important not only for Ukraine but also for the entire world science.
