Analysis of the 40K levels in soil using gamma spectrometry

Abstract

Potassium-40 was determined in soil in an area with 40,000 m 2 situated in the western State of Pernambuco, Brazil. For radiometric measurements, the gamma spectrometry method with a high purity germanium (HPGe) detector was used. Sampling of 78 soil samples has been performed at intervals of 25 m. The specific activities of 40K were calculated based on the photopeak of 1.46 MeV. Values from 541 to 3,572 Bq kg -1 were obtained (mean of 1,827 Bq kg -1). These values allowed the determination of the elemental concentrations as well as the absorbed dose rates in air, 1 m above the ground. The values varied from 1.7 to 11.5% (mean of 6%) and from 23.4 to 154.3 nGy h -1 (mean of 79 nGy h -1), respectively.