Study of Araucaria angustifolia nuts by Gamma-ray and X-Rays Fluorescence spectrometry

Abstract

The seed of Araucaria angustifolia is largely produced and consumed in Parana state, Brazil. It has an estimated annual consumption of approximately 0.167 kg per capita. The samples of seeds were acquired in 8 different commercial points of Londrina city in the state of Paraná, Brazil. To determine the natural level of radiation and elemental composition were analysed the seed pulp and peels, to determine the level of radiation in these samples and to calculate the effective dose per intake, the gamma ray spectrometry was applied using the HPGe detector with a 60% relative efficiency, and the X-rays Fluorescent by Dispersive Energy (EDXRF) was applied for elemental identification of the composition with a spectrometer from Shimadzu EDX-720 model. The samples were qualitatively analyzed by EDXRF, where the elements K, Fe, Cu, Zn, Rb, Ca, P, Mg and Sr were found in pulp and peels of seed, however, the elements Mg and Sr were detected only in the peel samples. The results obtained by gamma spectrometry showed that the radioactive activities in the Araucaria angustifolia pulp per kilogram in nature, for 226Ra ranged from 0.691 to 2.269 Bq/kg, the interval activity measured for the 228Ra were 0.386 to 1.767 Bq/kg and the 40K were 283.405 to 1,536.820 Bq/kg. Activities of 137Cs were detected in the pulp and peels of seed. The average dose per intake was 0.68 µSv/year for 226Ra and 0.35 µSv/year for 228Ra.