Measurement of natural radionuclides in the soil of Highlands agricultural farmland

Natural occuring radioctive material (NORM) is distributed in the environment including soil. It consist the gamma emmiting radionuclides such as
⁴⁰
K, the decay products of
²³⁸
U and
²³²
Th such as
²¹⁴
Bi,
²¹⁴
Pb (representing
²²⁶
Ra) and
²²⁸
Ac (representing
²²⁸
Ra). This study was carried out to determine the radioactivity concentration of NORM in soil, to calculated the radium equivalent, absorbed dose, annual effective dose and external hazard index level for the study area. The measurement was done by using gamma spectrometer with high resolution hyperpure germenium (HPGe) detector. Soil samples were collected using hand auger from the highland agricultural farm area in Cameron Highlands. These samples were dried, pulverized and sieved prior to analysis. The range of the radionuclides activity concentration for
⁴⁰
K is 363.6 to 1244.1Bq Bq/kg; range for
²²⁶
Ra is 131.1 to 200.0 Bq/kg
²²⁸
Ra 18.6 to 237.7 Bq/kg and Radium equivalent activity range 222 to 453 Bq/kg; 153.2 to 263.8 nGy/h is the range for absorbed dose rate while annual dose range from 0.17 to 0.30 mSv. External hazard index is in the range of 0.92–1.54, which are higher than unity. These value should be less than unity in order to keep the radiation hazard to be insignificant. Therefore, it can be concluded that soil from this study area might be contaminated by the fertilizer applied to the the plants itself and from the geological and geographial location soil types.