Determination of Gross Alpha, Gross Beta, and Natural Radionuclides (²¹⁰Po, ²¹⁰Pb, ²³⁸U, ²³²Th and ⁴⁰K) Activity Concentrations in Bread and Their Contribution to the Effective Dose

摘要

In this paper the gross alpha, gross beta and natural radionuclides (²¹⁰Po, ²¹⁰Pb, ²³⁸U, ²³²Th and ⁴⁰K) activities were determined in bread samples collected during 2013-2015 from Galati, Braila and Vrancea counties, South-Eastern Romania. The concentrations of ²¹⁰Po and ²¹⁰Pb were determined after self deposition on nickel disc by gross alpha measurements. The concentrations of ²³⁸U and ²³²Th were calculated after the determination of the concentration of ^natU and ^natTh through spectrophotometric measurements of arsenazo III-U⁴⁺ complex and arsenazo III-Th⁴⁺ complex, respectively. The concentrations of ⁴⁰K were measured by gammaspectrometry using a NaI(Tl) detector. The gross alpha and gross beta activity in bread samples ranged from 0.006 to 0.180 Bq kg^-1, and from 21.3 to 45.7 Bq kg^-1, respectively. The radionuclide concentrations (fresh weight) in bread ranged in the intervals 0.014-0.031 Bq kg^-1 for ²¹⁰Po, 0.006-0.080 Bq kg^-1 for ²¹⁰Pb, 0.009-0.040 Bq kg^-1 for ²³⁸U, 0.001-0.021 Bq kg^-1 for ²³²Th, and 10.4-31.4 Bq kg^-1 for ⁴⁰K. The annual effective dose obtained ranged between 0.023 μSv y^-1 (for ²³²Th) and 19.572 μSv y^-1 (for ⁴⁰K).