Abstract

The natural radionuclide contents in some medicinal plants commonly found around oil and gas facilities in Ughelli and nearby communities have been investigated. A class of such medicinal plants are those that are regarded as grasses and are usually taken for healing purposes. The plants investigated are lemon grass (Cymbopogan citrates), Spear grass (Imperata cylindrical) and Carpet grass (Eleusin indicageartin). The plants were assayed for their radionuclide contents by means of gamma spectrometry using a shielded  and well calibrated NaI(Tl) detector coupled to a computer interfaced  multichannel analyser, quantumTm MCA 2100R. Results of the analysis showed that the radionuclides detected in the grasses around the oil and gas facilities belong to the primordial radionuclide series of 238U and 232Th as well as non serial 40K. On the average, the values for lemon grass has 238U (15.3 + 1.7 Bqkg-1), 232Th (1.1 + 2.7 Bqkg-1) and 40K(67.9 + 7.4 Bqkg-1). In spear grass, 238U (15.8 + 2.4 Bqkg-1), 232Th (1.7 + 4.3 Bqkg-1) and 40K(69.3 + 9.4 Bqkg-1) were determined while  carpet grass recorded 40K (70.2 + 11.6 Bqkg-1) with 238U(16.0 + 1.9 Bqkg-1) and 232Th(1.6 + 4.2 Bqkg-1). The measured levels of the radioactivity in the samples translated to very low values of the annual effective dose equivalent, implying safe level of radiological health consequences. No significant difference was determined between radionuclide contents of samples of medicinal plants around oil and gas facilities and samples of the same species of medicinal plants from an undisturbed and virgin location in Nigeria where industrial activities, waste dump nor is farming practised. However, no trace of artificial radionuclide was determined in all the samples assayed in both areas, hence, measurements can be taken as representing baseline values of the radionuclides in medicinal plants in the areas.

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