Transfer of radiocesium from lichen to reindeer

An empirical two compartment model is presented which describes the transfer of radiocesium from fallout contaminated lichen to reindeer. Kinetic parameters were calculated from data derived from retention studies following a single dose of 134Cs to reindeer maintained on a natural mountain tundra pasture at Cantwell, Alaska. Cesium retention values were statistically indistinguishable for the autumn and winter period, however cesium retention half times were reduced 2–4 fold during the summer months as compared to the autumn-winter studies. Cesium kinetics in the reindeer were not influenced significantly by animal sex although a significant increase in cesium retention with animal weight was observed. Results obtained from controlled lichen feeding experiments indicated that about 20–30% of the radiocesium contaminating lichen is available for absorption by the reindeer. The model was tested by comparing predicted values with results obtained with a single reindeer maintained on a constant 134Cs intake. Predicted values are compared to observed radiocesium concentrations in the lichen-caribou segment of the Arctic food chain.