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Environmental radiation

The effects of the Chernobyl accident on animals and the ecosystem

The effects of the Chernobyl accident on animals and the ecosystem

The 1986 Chernobyl nuclear power plant accident polluted several thousands of square kilometres of land with various radioactive substances, such as radioactive isotopes of caesium, strontium, americium and plutonium. People and some domestic animals were evacuated, but the wild animals and plants in the area were exposed to high levels of radiation. The harmful effects of radiation have since been detected in several species.

The Chernobyl accident has offered an opportunity to study the effects of ionising radiation on ecosystems. We are able to study the effects of radiation on wild animals because of the remaining high dose rate caused by external radiation in the isolated precautionary action zone covering a distance of 30 kilometres from the ruptured reactor. Several studies have been conducted on insects (such as butterflies, bumblebees, grasshoppers and dragonflies), spiders, birds and mammals (including elk, deer, wolves, lynx, wild boar, bats).

Even today, over 30 years after the Chernobyl nuclear power plant accident, the scientific community is unable to reach a consensus on how long-term exposure to radiation has affected wild animals. The data on the effects of radiation is conflicting. Observations made in nature and the reference values recommended by the International Commission on Radiological Protection’s (ICRP), for example, do not unambiguously set a limit value for effects on animals.

It is also unclear which radiation level causes a considerable impact on the ecosystem. The uncertainty of research results is increased by the uneven distribution of the concentrations of radioactive substances in the area, fluctuations in the transmission of the substances and, as a result, the challenges of evaluating the actual radiation dose in living organisms. However, studies have indicated that ecosystems can recover even from vast disruption and recover their diversity. The seed production of the pines in the Chernobyl area, for example, regained its usual levels in only a few years after the accident.

The accident and the resulting radioactive pollution killed most of the pines in the forest near the nuclear power plant, impaired the production of pine seeds, reduced the number of invertebrates in the soil and increased the mortality of small mammals. The effects were clear and consistent with the established views of the harmful effects of radiation.

The forest of dead pines is called the Red Forest. The direct impact of radiation killed the trees, while the consequent, indirect effects transformed the lighting and nutrients in the area. Over time, a deciduous forest took over the previous pine forest. As the forest type changed, the fauna in the area was replaced by species better suited to the new biome, increasing biodiversity in the area.

The disruptions and changes caused by the Chernobyl disaster in the species and biodiversity have influenced the subsequent transformation of the area over time. Before the accident, people also played a role in the ecosystem. As the area was evacuated and the influence of people was lost, new opportunities opened up for various species. Long-term studies on large mammals have shown that species previously vacant in Chernobyl, such as the bison and Przewalski's horse, now thrive in the area.