Determination of 137Cs and 90Sr in calcareous soils: Geographical distribution on the island of Majorca

In this work radioactive concentrations of the man-made radionuclides 137Cs, 89Sr and 90Sr have been studied in calcareous soils of the island of Majorca (Spain), by analysing the top 5 cm of the surface layer. The activity of 137Cs was determined by γ-ray spectrometry and ranged from about 10 to 60 Bq/kg. The possibility of carrying out extraction of Sr from calcereous soils was evaluated by using three different methods previously used in other samples with a high calcium content. Only the method based on precipitation in a fuming HNO3 medium gave rise to successful results with a yield of around 75%. The activity 90Sr was determined using a low-background αβ proportional counter. Results varied between about 2 and 8 Bq/kg. The activity of 89Sr was below the lower limit of detection.