In 1986 the Chernobyl accident contaminated 125,000 square miles of land in Belarus, Russia and Ukraine with radionucleotides including cesium-137, strontium-90 and plutonium-239. It is too early to determine the long-term effects of the radioactive contaminants on the various affected habitats, because genetic changes are often not expressed in a general population for two or three generations. From early observations, however, the prognosis is much more promising than had originally been expected.
About 40% of the contaminated area was used for agriculture. The remainder was forest, bodies of water and urban centers. Plants and animals living in the 30-km exclusion zone received the highest level of radiation. Since radionucleotides migrate very slowly in soil, the radiation level in this region remains high. In Belrus 2,640 sq. km of farmland and 1,900 sq. km of forest have been taken out of use by humans forever; so predicted Igor V. Rolevich, Belarus first deputy minister for emergencies.
The Chernobyl accident took place during the growing season. It took only two weeks for the conifers to suffer significant damage from exposure. Initially many trees suffered sever damage to reproductive tissue.
Within three years of the accident, the trees had regained their reproductive functions. The forests have begun to thrive. Areas within the heart of the exclusion zone have the largest density of animals as well as the greatest diversity. Since people and their livestock do not enter the exclusion zone, there is not much overgrazing, no fires and no destruction. The grass is very deep and the habitat is doing very well. The area outside the exclusion zone has been so severely overgrazed by cattle that there is little grass. In addition, the trees have been cut for firewood, a stress factor that has not affected the exclusion zone.
One must avoid the temptation to become too overly optimistic about the rapid recovery of the contaminated area. Currently there is no standard by which to predict the long-term effects on populations, species or ecosystems.
Contamination of the soil by radionucleotides with long half-lives such as cesium-137 is a particular problem for the local residents near the Chernobyl Nuclear Reactor. These radionucleotides remain in the soil for a long while, is taken up by plants and transferred to the milk and meat products of cattle that graze the area. Human exposure could have been reduced by imposing strict countermeasures immediately following the release. Had local residents not worked in the field, or eaten fresh vegetables, and had they kept their livestock from eating the contaminated forage. Such measures need to be taken immediately, however, and they were not. Very specific countermeasures applied immediately can have a great bearing on the long term effects of a radioactive release. Changing the type of crop planted (each species has a different rate at which it absorbs specific chemical elements or compounds) or adding chemicals such as lime or potassium fertilizers can protect the population. In order for this to happen, residents have to be trained to respond, and the needed supplies must be readily available. No emergency procedure was in place for dealing with the catastrophe.
It is interesting that the water supply is not nearly as contaminated as the soil. The radionucleotides tend to settle out with time. Aquatic habitats also tend to be more tolerant of radioactive contamination. There is no evidence of any long term effects to the populations in the water near the nuclear reactor's cooling pond, which was the most contaminated body of water in the exclusion zone.
While the groundwater has not been contaminated to date, the Sarcophagus, which was built around Reactor Unit 4 is crumbling and there are many sites where radiation contaminated equipment were dumped.
While the environment in the exclusion zone seems to have recovered, it still has to deal with long term effects (such as genetic mutations, which may not surface for a few generations) and the real threat of another release of radioactivity should the integrity of the sarcophagus continue to disintegrate.
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Roberta C. Barbalace. Chernobyl Disaster's Agricultural and Environmental Impact. EnvironmentalChemistry.com. 1999. Accessed on-line: 12/1/2021