Downward migration of radiocaesium in organic soils across a transect in Scotland

Following the accident at the Chernobyl nuclear power plant in 1986, radioactive materials including Cs-137 were distributed over large parts of the former Soviet Union and Europe. Due to the relatively long physical half-life of Cs-137 (30.1 y) measurable activity concentrations can still be observed in the natural environment. We have determined the depth distribution of Cs-137 from the testing of nuclear weapons in the atmosphere and Chernobyl, in eight highly-organic soils along an approximately east to west transect across the Central Highlands of Scotland. The Cs-137 activity concentrations in the soil profiles, corrected for radioactive decay to May 1986, were between 2.8 and 14.4 kBq m(-2). There were differences in the pattern of distribution of Cs-137 in the soil profiles. The mean migration depth of Cs-137 in the soil profiles was 12.2 cm with a range between 8.2 and 17.4 cm. Quantitative mineralogical analysis of the ash obtained after heating the soil to 400 degrees C indicated that clay minerals alone did not have a prime role in controlling the migration of Cs-137 down the profile. (C) 2012 Elsevier Ltd. All rights reserved.