90Sr, 137Cs, 239+240Pu and 238Pu concentrations in surface soils of Korea

The concentrations and activity ratios of 90Sr, 137Cs, 239+240Pu and 238Pu in surface soils (0–5 cm) of Korea were determined. The concentrations were in the range of 1•10–13•5 Bq kg-1 for 90Sr, 7•86–70•1 Bq kg-1 for 137Cs, 0•18–1•85 Bq kg-1 for 239+240Pu, and 0•006–0•062 Bq kg-1 for 238Pu. The mean activity ratios of 137Cs/90Sr, 239+240Pu/137Cs and 238Pu/239+240Pu were 10•7, 0•024 and 0•038, respectively. The concentrations and activity ratios are similar to those reported from neighboring countries and from other mid-latitude locations in the northern hemisphere. The concentrations of 137Cs correlate with those of 239+240Pu (r=0•97). The concentrations of 239+240Pu and 137Cs increase with increasing organic matter content,clay content and mean annual precipitation.