Caesium concentration factors in wild herbivores and the fox ( Vulpes vulpes L)

Abstract

A selection of wild animals was sampled in the winter of 1986/87. The sites chosen for sampling were based on information obtained from survey carried out by The Institute of Terrestrial Ecology in the spring and autumn of 1986. Animals included deer, grouse, hares and rabbits, and foxes which were collected as a top carnivore in the food chain. Variation in concentration of caesium between species from the same area was unpredictable; rabbits, for instance, never exceeded 200 Bq kg −1 (fresh wt) of 137 Cs in their flesh, even when adjacent to deer forests with over 1000 Bq kg −1 in the vension. The greatest complication grose from areas of peaty uplands where the pre-Chernobyl 137 Cs from weapons-testing was much higher than expected. This pre-Chernobyl contribution amounted to 630 Bq kg −1 in a red grouse from the Pennines, and 650 Bq kg −1 in a roe deer from near the Borders, being c. 60% of the total. Concentration factors were calculated using values from freshly ingested vegetation and tissues from individual animals. Significant differences in concentration factors were found depending on species, food, sex, breeding condition and age. Contrasting the decrease of the two caesium isotopes in roe deer from forestry on peat with those from woodlands on mineral soils, it appeared that after an initial fall in concentration, the only decrease thereafter occured on the mineral soils. Nowhere were radiocaesium concentrations high enough to cause concern amongst consumers of game and other wild animals, even when levels exceed 3000 Bq kg −1 (fresh wt) as they did in red deer, red grouse and the blue hare.