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Steep decline in radioactive caesium after 30 years of monitoring

Published on: 21. June 2024
Author: Trine Hay Setsaas

Following the Chernobyl accident in 1986, large areas of northern Europe were exposed to radioactive caesium, detrimental to both terrestrial and aquatic ecosystems. Recent results from 30 years of monitoring in the mountain areas of Norway show steep declines in radiocaesium – an important find when evaluating potential impact on wildlife and human health. 

Steep decline in radioactive caesium after 30 years of monitoring

Reindeer grazing in the mountains. Photo credit: Olav Strand, NINA

Norway received large amounts of radiocaesium from atmospheric tests of nuclear weapons in the 1950–60's and with the accident at the Chernobyl Nuclear Power Plant in 1986. Mid and central regions of Norway experienced the highest deposition rates, resulting in detrimental exposure for both terrestrial and aquatic ecosystems. 

In Norway, concerns were immediately raised following the Chernobyl accident, especially because the most heavily contaminated areas overlapped with key grazing areas for reindeer and domestic sheep, with possible harmful consequences for human health.

Faster declines than predicted 

In a recently published paper, NINA researchers present the results from a long-term study of radiocaesium in selected alpine plant species in Rondane National Park and Dovrefjell National Park, central Norway. Data were collected over a 31-year period from 1991 to 2022, comparable to the physical half-life of the radioactive substance. 

We found that the effective rates of decay of radiocaesium in alpine plants were much faster than the rate predicted from the physical half-life, says Signe Nybø, Research Director at NINA and head author.  

Further, functional groups of plants differed in concentrations in early years after the accident, with higher rates of contamination in lichens and bryophytes than vascular plants. Also, variations were also observed among plant species important for grazing.  

These results are encouraging because current estimates of radiocaesium concentrations in alpine plants in central Norway lead to levels of radiocaesium concentrations in wild game and reindeer that are less than national guidelines for acceptable concentrations of radiocaesium.   

Filling crucial knowledge gaps 

Early investigations of radiocaesium in plants in Europe focused on grazed pastures and agricultural crops on cultivated lands. Therefore, estimates of concentrations in plants in natural habitats have been a knowledge gap for models of exposure for wild and domestic animals. 

Since plant herbivory is one of the main pathways for radioactive caesium to enter the food chain, new information on this substance in alpine plants will help to understand the environmental impacts of radioactive contamination for other trophic levels, says Nybø. 

The study states further that knowledge on plant uptake and differences among plant species are important for implementing effective strategies to minimize the transfer not only from soil to wild plants, but also to wildlife, livestock, agricultural products, and potentially to humans.

Read the full article here

Contact: Signe Nybø


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Norwegian Institute for Nature Research

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