THE TRANSFER OF CS-137 AND SR-90 ALONG THE SOIL-PASTURE-COWS MILK PATHWAY IN AN AREA OF LAND RECLAIMED FROM THE SEA

An area of reclaimed land on the Lancashire coast of the UK has been u sed to provide data on transfer parameters in the soil-pasture-milk fo odchain pathway when the activity is almost entirely of marine origin. Measured grass:soil concentration ratios for Cs-137 were at the lower end of the range of values published by the International Union of Ra dioecologists (IUR), and about five times lower than the figure recomm ended by them for generic assessments. Feed:milk transfer coefficients for Cs-137 between June and September 1988 were about half of the val ue considered appropriate when all of the ingested activity was in an available form. This can be accounted for by the ingestion of soil dur ing open-pasture grazing, together with the observation that most of t he soil-associated radiocaesium would be relatively unavailable for up take. For Sr-90, the grass: soil concentration ratios were one to two orders of magnitude higher then those for Cs-137 and close to the gene ric soil:grass transfer factor recommended by the IUR. The ingestion o f soil-associated activity was not an important contributor to intake for this radionuclide. Moreover, a significant fraction of the soil-as sociated activity was found to be soluble in rumen fluid. The results of this work are discussed in terms of their applicability to other si tuations involving the introduction of radionuclide-bearing marine sed iment into the terrestrial environment.