CHARACTERIZATION OF SAND SAMPLES FROM KARACHI BEACHES USING GAMMA SPECTROMETRY AND XRD

Soil mineral analysis and environmental radioactivity in Ghizer, Eastern Hindukush, Pakistan

Distribution of natural and anthropogenic radionuclides (226Ra, 232Th, 137Cs and 40K) was determined in 32 samples from Ghizer, an Eastern Hindukush district at an altitude of 2286 m in Pakistan using high resolution gamma-ray spectrometry. Mineralogical analysis by X-ray diffractometry identified quartz, calcite, albite and anorthite as major phases whereas actinolite, chlorite serpentine and kaolinite as minor phases. The activity concentrations for 226Ra, 232Th, 137Cs and 40K varied from 25.2 ± 1.7 to 145.3 ± 10.1 Bq kg−1, 24.9 ± 1.1 to 197 ± 9 Bq kg−1, 2.03 ± 0.21 to 16.7 ± 1.1 and 252 ± 6 to 1433 ± 35 Bq kg−1, respectively. The samples yielded average radium equivalent activity as 178.4 ± 23.3 Bq kg−1. The majority of the samples revealed external hazard index and representative level index less than one. The average air absorbed dose rate was 91.2 ± 13.6 nGy h−1 corresponding to the annual effective dose rate 111.8 ± 17.4 μSv y−1. These values were higher than the world averages for air absorbed dose rate and outdoor annual effective dose rate. Principal component analysis was applied to obtain distribution pattern within the samples and among the radionuclides.

EVALUATION OF INDOOR/OUTDOOR GAMMA EXPOSURE RATES AND EXCESS LIFE TIME CANCER RISK IN DIFFERENT CITIES OF PAKISTAN

This study presents a detailed measurement of indoor and outdoor terrestrial gamma radiation levels in different cities of Pakistan. The measurements covered dwellings in 27 cities, covering all provinces and region of Azad Kashmir. Most of the houses were of attached type, made of brick walls and concrete roofs. The measurements were made by a handheld radiation survey meter containing Geiger-Muller tube. The average absorbed dose rate in air was 100 ± 32 nGy h-1 for indoor and 74 ± 30 nGy h-1 for outdoor. The population-weighted mean terrestrial dose rates were 90 nGy h-1 for indoor and 78 nGyh-1 for outdoor. The ratio of indoor to outdoor absorbed dose rate was 1.5 as compared to 1.3 for the world average. The estimated average annual effective dose rate was 0.58 ± 0.18 mSv a-1 and the mean excess life time cancer risk was 2.0 × 10-3.