Bio-indicators for Impact Assessment of Radionuclides Contamination

Abstract

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.