LONG-TERM BEHAVIOR OF RADIOCESIUM IN DAIRY HERDS IN THE YEARS FOLLOWING THE CHERNOBYL ACCIDENT

The longterm behavior of Cs-137 in milk of a Bavarian farm (farm A) de posited as a consequence of the Chernobyl accident has been followed f rom April 1986 until August 1994. On the basis of activity measurement s in milk and feed, transfer coefficients for the different seasons ha ve been estimated in order to see any changes in transfer behavior (ag ing effect) of Cs-137 with time. The influence of different grazing re gimes has been tested by comparison of activity concentrations in milk and pasture grass in one farm (farm A with rotational grazing regime) with that of a nearby farm (farm B with continuous grazing regime) ov er a complete grazing season by frequent measurements in 1993. Though the farms are located only 4 km apart, have similar soils, and were co ntaminated to the same extent by the Chernobyl fallout, tenfold lower Cs-137 activity concentrations in milk have been observed in farm B. T his finding seems to be partly due to the influence of a different gra zing intensity.