Modeling the Dynamic Behavior of Radiocesium in Grazing Reindeer

Radiocesium contamination in Norwegian reindeer and the factors influencing contamination levels have been studied for more than 50 years, providing significant amounts of data. Monitoring contamination in reindeer is of utmost importance for reindeer husbandry and herders in Norway and will need to be studied for many years because of the persistent contamination levels due to the 1986 Chernobyl fallout. This paper presents a novel dynamic model that takes advantage of the large data sets that have been collected for reindeer monitoring to estimate ¹³⁷Cs in reindeer meat at any given time. The model has been validated using detailed ¹³⁷Cs data from one of the herds most affected by the fallout. The model basis includes detailed ¹³⁷Cs soil data from aerial surveys, GPS-based knowledge of reindeer migration, and local soil-to-vegetation ¹³⁷Cs transfer information. The validation exercise shows that the model satisfactorily predicts both short- and long-term changes in ¹³⁷Cs concentrations in reindeer meat and suggests that the model will be a useful tool in estimating seasonal changes and evaluating possible remedial actions in case of a future fallout event.