Radioactivity mapping of north western areas of Pakistan

A systematic study of natural and fall-out radionuclides was carried out with the environmental samples of soil, vegetation and water from some regions of North West Frontier Province (NWFP) of Pakistan. The pretreatment of the samples was performed in the laboratory using IAEA recommended methods. The analysis of gamma-emitters such as 40K, 226Ra, 232Th and 137Cs was performed with a high purity germanium detector (HPGe). For the determination of 90Sr, a liquid scintillation counting system was used. The average specific activities of 40K, 226Ra, 232Th and 137Cs have been found to be 307±101 Bq x kg-1, 10.2±3 Bq x kg-1, 24±6 Bq x kg-1 and 2.8±1.3 Bq x kg-1, respectively, in soil samples. Vegetation samples have smaller values of specific activities and even the analysis of water samples showed values less than LLD for earlier reported radionuclides. Other parameters like hazard indices, radium equivalent activities, absorbed dose rates and effective dose equivalents have also been determined. All these parameters have values less than their respective limiting values representing that the surveyed areas have no significant hazard from health point of view. Analysis of 90Sr for all the samples showed results below LLD. The present study provides a general background of the detectable radionuclides for the surveyed areas that will be helpful in any radiological emergency. (author)