The activity of important radionuclides 232Th, 226Ra and 40K were analysed in twelve medicinal plants collected from Mangalore and surrounding region by gamma spectrometry. The activity in the representative soil sample is also measured in order to study the transfer of radionuclides from soil to plant. In plant the average values of 232Th, 226Ra and 40K activity were found to be 0.8 Bqkg-1, 5.0 Bqkg-1 and 37.1 Bqkg-1 respectively. In soil the average values of 232Th, 226Ra and 40K activity were found to be 54.7 Bqkg-1, 64.2 Bqkg-1 and 384.3 Bqkg-1 respectively. The average values of transfer coefficient for 232Th, 226Ra and 40K were found to be 0.02, 0.08 and 0.10 respectively. The 232Th activity was below detection level for most of the plant samples, though the activity was significant in soils associated to these plants. The significant activity of 226Ra in both plant and associated soil shows the higher root uptake of this radionuclide from soil. All the plants and associated soils showed significant 40K activity. The plant Mamia suregia showed higher transfer coefficient for all the three radionuclides. The plant can be used as bioindicator for the future monitoring of these radionuclides. The absorbed gamma dose rates prevailing in the study area were also measured using portable scintillometer. The results of these systematic investigations are presented and discussed in this paper.
Radionuclide, 232Th, 226Ra, 40K, Soil, Scintillometer, Transfer Coefficient.
Prakash V1, Narayana Y2
1 Department of PG Studies and Research in Physics, Payyanur College Kannur - 670 327, Kerala
2 Department of Studies in Physics, Mangalore University, Mangalagangotri D.K. - 574 199, Karnataka