Wild Chernobyl

A few years ago, I saw a documentary about Chernobyl made over twenty years after the 1986 nuclear power plant disaster. Soon after the disaster, people were evacuated from a 30km exclusion zone around the reactor. Even today, many parts of this region remains contaminated with high doses of radiation. The Chernobyl exclusion zone to the north of the Black Sea straddles Belarus and Ukraine and remains practically uninhabited.


Map of Chernobyl Exclusion Zone

The prolonged absence of humans has had interesting effects on the local wildlife. In the immediate aftermath of the accident, Soviet scientists reported a sharp drop in the population of small animals and birds in the area. Since then, the area has been a battleground for zoologists studying the competing effects of radiation and human absence.


The most remarkable feature has been the increase in the number of many kinds of animals including beavers, horses and especially wolves which free from human hunters have grown in numbers. There are probably more wolves in the Chernobyl Exclusion Zone than in Yellowstone Park. But exact numbers are harder to get because researchers can’t remain there for extended periods.

Some zoologists maintain that despite this, the populations of several species of insects and small animals has actually dropped. They believe the effects of radiation poisoning has led to a terrible increase in mutations and animal mortality. Others insist the effects are not so sever and question the data of the former.


Consider the effect of radiation on the food chain. The radiation in the soil is concentrated in the mushrooms that grow on it. Voles eating the mushrooms accumulate the radiation of all the mushrooms they eat. When a wolf or a fox eats many voles, it gets the combined effect of the radiation from what the vole had eaten. Thus, the further up the chain an animal is, the higher a dose of radiation it will get.


But there are some complications to this simple model. For starters, the radiation is distributed very unevenly over the whole area. Predators like wolves can wander in and out of these regions eating prey from all over. This means it can be difficult to predict how much radiation a wolf is actually likely to be exposed to.


Cesium-137 Radiation Map of the Chernobyl Exclusion Zone

The evidence reflects this complexity. If anything, wolves are doing better in Chernobyl than anywhere nearby.

So what does this mean for the effects of radiation poisoning? One suggestion is that if the death rates for the animals are a few percent. Say that every generation 4-6% babies die due to mutations, then this would be insignificant beside natural factors in the wild such as predation and disease. But for civilized humans, this would be catastrophic.

To think that of all the things people do to animals, nuking them seems relatively benign.


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