Abstract
The activity concentrations of 238U, 232Th and 40K in soil samples from different soil types has been collected in the state of Perak, Malaysia. The samples were determined using a high resolution co-axial HPGe gamma ray spectrometry system. Mean values for 238U, 232Th and 40K activity concentrations were found to be (127 ± 97) Bq kg-1, (304 ± 28) Bq kg-1, and (302 ± 29) Bq kg-1 respectively. The highest concentration of 238U and 232Th was found for soil of the types Paleudults-Hapludults and 40K for the typic Aeric Tropaquepts. The external hazard values (Hex) are between 0.35 and 3.07. Soil type typic Paleudults and typic Hapludults have a hazard index, Hex value which is greater than 2, and the rest of the soil types (ten soil types) have Hex values between 1 to 2. The concentrations of 238U and 232Th in soil samples in the study area are higher than the reference value.
Highlights
The most common terrestrial radioelements that produce gamma-rays are uranium (238U), thorium (232Th) and potassium (40K)
The activity concentrations of 238U, 232Th and 40K in soil samples from different soil types has been collected in the state of Perak, Malaysia
To determine the relative hazard of materials that contain 238U, 232Th and 40K were used by the radium-equivalent activity Raeq as shown in Equation (2) (Krieger, 1981; Beretka & Mathew, 1985), Raeq = 370 Bq kg-1 Hex where, Hex is the external hazard index which is calculated by using Equation (3), Hex where CU, CTh, and CK are the activity concentrations of 238U, 232Th and 40K in Bq kg-1 respectively
Summary
The most common terrestrial radioelements that produce gamma-rays are uranium (238U), thorium (232Th) and potassium (40K). The abnormally high terrestrial gamma radiation (HTGR) dose rates in Brazil are due to the presence of monazite sand along the Atlantic coast and volcanic intrusion in the state of Minas Gerais. Dose rate in this area ranged up to 2.1 Gy h-1, which is more than 30 times the world average value (Malanca et al, 1993; Roser & Cullen, 1964). The concentrations of uranium and thorium in high background radiation dose rate areas are associated with soil developed from igneous rocks (Kogan et al, 1969; Larsen & Gottfried, 1960). The concentrations of the naturally occurring radionuclide of 238U, 232Th and 40K in soil samples were determined in Perak States of Malaysia
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