A 10-year study of the Cs-137 distribution in soil and a comparison of Cs soil inventory with precipitation-determined deposition

During a 10-year period, 1988-1998, surface soil samples have been collected at Blentarp in southern Sweden and analysed for Cs-137 from the Chernobyl accident and from the nuclear weapons tests, The distance between the sampling plots on the different sampling occasions has been no more than 3 m. The results show that the depth distribution of Cs-137 is very similar for each of the sampling occasions, indicating that the caesium migration at this site is very small. The total activity measured in the soil cores is in agreement with the calculated activity of Cs-137 deposited at the site after nuclear weapons tests and the Chernobyl accident, based on air activity concentration and the amount of precipitation. The calculated deposition of Cs-137 originating from the bomb tests amounts to 1.41 kBq m(-2) for the period 1962-1986, which is in agreement with the activity of nuclear weapons fallout measured in the soil samples (1.60 kBq m-2 as a mean value of the first four years of sampling). The calculated activity of Cs-137 Of Chernobyl origin was 0.79 kBq m(-2), which agrees well with the value of 0.79 kBq m(-2) measured in the soil samples in 1988. (C) 2001 Elsevier Science Ltd. All rights reserved.