Measurement of terrestrial radiation for assessment of gamma dose from cultivated and barren saline soils of Faisalabad in Pakistan

Abstract

Natural radioactivity originates from extraterrestrial sources as well as from primordial radioactive elements in the earth crust. The amount of radioactivity in soil varies widely and is a source of continuous exposure of human beings to terrestrial radioactivity that depends upon the type of soil and its uses. For the investigation of radioactivity in barren and cultivated soil, an area of about 80 ha of saline soil was selected in Pakka Anna near the city of Faisalabad in the Punjab province of Pakistan. Activity concentration levels due to 40K, 137Cs, 226Ra and 232Th were measured with HPGe detector in 250 saline soil samples collected at a spacing of about 8 ha at a depth of 0–25 cm with intervals of 5 cm depth. Activity concentration ranges of the concerned radionuclides for both of the soils were as follows: 40K, for barren and cultivated saline soil was 499–604 and 563– 629 Bq kg - 1 , respectively; 137Cs, 3.57–3.63 and 1.98– 5.15 Bq kg - 1 ; 226Ra, 24–29 and 27– 33 Bq kg - 1 , and 232Th, 49–54 and 46– 62 Bq kg - 1 . Gamma dose was estimated using the activity to dose rate conversion factors. The measured activity concentrations and the estimated radiation dose were found to be lying within the range specified in the 2000 report of UNSCEAR. Chemical analysis for Na, Ca and Mg was also carried out along with the measurement of electrical conductivity and pH of soil samples.