Chapter III. Consequences of the Chernobyl Catastrophe for the Environment


Address for correspondence: Alexey V. Yablokov, Russian Academy of Sciences, Leninsky Prospect 33, Office 319, 119071 Moscow, Russia. Voice: +7-495-952-80-19; fax: +7-495-952-80-19.


Air particulate activity over all of the Northern Hemisphere reached its highest levels since the termination of nuclear weapons testing—sometimes up to 1 million times higher than before the Chernobyl contamination. There were essential changes in the ionic, aerosol, and gas structure of the surface air in the heavily contaminated territories, as measured by electroconductivity and air radiolysis. Many years after the catastrophe aerosols from forest fires have dispersed hundreds of kilometers away. The Chernobyl radionuclides concentrate in sediments, water, plants, and animals, sometimes 100,000 times more than the local background level. The consequences of such a shock on aquatic ecosystems is largely unclear. Secondary contamination of freshwater ecosystems occurs as a result of Cs-137 and Sr-90 washout by the high waters of spring. The speed of vertical migration of different radionuclides in floodplains, lowland moors, peat bogs, etc., is about 2–4 cm/year. As a result of this vertical migration of radionuclides in soil, plants with deep root systems absorb them and carry the ones that are buried to the surface again. This transfer is one of the important mechanisms, observed in recent years, that leads to increased doses of internal irradiation among people in the contaminated territories.

Plants and mushrooms accumulate the Chernobyl radionuclides at a level that depends upon the soil, the climate, the particular biosphere, the season, spotty radioactive contamination, and the particular species and populations (subspecies, cultivars), etc. Each radionuclide has its own accumulation characteristics (e. g., levels of accumulation for Sr-90 are much higher than for Cs-137, and a thousand times less than that for Ce-144). Coefficients of accumulation and transition ratios vary so much in time and space that it is difficult, if not impossible, to predict the actual levels of Cs-137, Sr-90, Pu-238, Pu-239, Pu-240, and Am-241 at each place and time and for each individual plant or fungus. Chernobyl irradiation has caused structural anomalies and tumorlike changes in many plant species. Unique pathologic complexes are seen in the Chernobyl zone, such as a high percentage of anomalous pollen grains and spores. Chernobyl's irradiation has led to genetic disorders, sometimes continuing for many years, and it appears that it has awakened genes that have been silent over a long evolutionary time.

The radioactive shock when the Chernobyl reactor exploded in 1986 combined with chronic low-dose contamination has resulted in morphologic, physiologic, and genetic disorders in every animal species that has been studied—mammals, birds, amphibians, fish, and invertebrates. These populations exhibit a wide variety of morphological deformities not found in other populations. Despite reports of a “healthy” environment in proximity to Chernobyl for rare species of birds and mammals, the presence of such wildlife is likely the result of immigration and not from locally sustained populations. Twenty-three years after the catastrophe levels of incorporated radionuclides remain dangerously high for mammals, birds, amphibians, and fish in some areas of Europe. Mutation rates in animal populations in contaminated territories are significantly higher and there is transgenerational genomic instability in animal populations, manifested in adverse cellular and systemic effects. Long-term observations of both wild and experimental animal populations in the heavily contaminated areas show significant increases in morbidity and mortality that bear a striking resemblance to changes in the health of humans—increased occurrence of tumor and immunodeficiencies, decreased life expectancy, early aging, changes in blood and the circulatory system, malformations, and other factors that compromise health.

Of the few microorganisms that have been studied, all underwent rapid changes in the areas heavily contaminated by Chernobyl. Organisms such as tuberculosis bacilli; hepatitis, herpes, and tobacco mosaic viruses; cytomegalovirus; and soil micromycetes and bacteria were activated in various ways. The ultimate long-term consequences for the Chernobyl microbiologic biota may be worse than what we know today. Compared to humans and other mammals, the profound changes that take place among these small live organisms with rapid reproductive turnover do not bode well for the health and survival of other species.