The transfer of 137Cs and 90Sr along the soil-pasture-cows' milk pathway in an area of land reclaimed from the sea

Abstract

An area of reclaimed land on the Lancashire coast of the UK has been used to provide data on transfer parameters in the soil-pasture-milk foodchain pathway when the activity is almost entirely of marine origin. Measured grass: soil concentration ratios for 137Cs were at the lower end of the range of values published by the International Union of Radioecologists (IUR), and about five times lower than the figure recommended by them for generic assessments. Feed: milk transfer coefficients for 137Cs between June and September 1988 were about half of the value considered appropriate when all of the ingested activity was in an available form. This can be accounted for by the ingestion of soil during open-pasture grazing, together with the observation that most of the soil-associated radiocaesium would be relatively unavailable for uptake. For 90Sr, the grass: soil concentration ratios were one to two orders of magnitude higher than those for 137Cs and close to the generic soil: grass transfer factor recommended by the IUR. The ingestion of soil-associated activity was not an important contributor to intake for this radionuclide. Moreover, a significant fraction of the soil-associated activity was found to be soluble in rumen fluid. The results of this work are discussed in terms of their applicability to other situations involving the introduction of radionuclide-bearing marine sediment into the terrestrial environment.