Abstract
Background: As a part of environmental radioactivity monitoring program, it is necessary to determine the activities of alpha emitting radionuclides in the environmental samples. Identification and quantification of particle alpha emitting radionuclides such as thorium, plutonium, uranium etc. with long half-life plays a key role in environmental characterization and radiation protection. However, studies on alpha emitting radionuclide, thorium present in environmental samples are rare and deserve a systematic and extensive research work. In order to do so several environmental samples such as soil, water have been collected from the Rooppur Nuclear Power Plant area, a sunflower plant from the Curzon Hall, Dhaka university area along with a borehole water sample from Beximco Pharmaceuticals Ltd. Method: The measurement of the concentration of alpha emitting radionuclide, thorium, comprises of chemical dissolution of samples, chemical separation using ion-exchange method, preparation of counting source by electrodeposition and need to count by an alpha spectrometry system. Dry ashing method has been used for preparing soil and plant samples. On the other hand co-precipitation method has been used for preparing water samples. An essential requirement for the measurement of alpha emitter is the exact identification of photo peaks present in a spectrum produced by the silicon surface barrier detector system which is calibrated by the standard sources of 230Th and 239+240Pu. A single photo peak observed in alpha spectrum within the energy range 4.64-4.72 MeV. This indicates the presence of 230Th in soil, water and plant samples. Results: The measured activity concentrations of 230Th in different environmental samples were found to be in the range of 3.86 to 8.13 Bq/kg in soil; 0.32 to 0.44 Bq/L in water; 2.5 to 5.4 Bq/kg in different parts of a matured sunflower plant. Conclusion: Our studied will be helpful for the radiological impact on the environment after commissioning of the nuclear power plant and any other nuclear fallout could be assessed by using this baseline data. In addition, these data will be useful in the assessment of internal doses partly and the trend of public radiation exposure.

Keywords
Environmental Samples, Alpha Spectrometry System, Alpha emitting radionuclide, and Rooppur Nuclear Power Plant area.

Cite this paper
Md. Saiful Islam, Jannatul Ferdous, Dr. Aleya Begum, Dr. Pradip Kumar Bakshi, Measurement of Activity concentration of Thorium in Environmental samples by Alpha Spectrometry system , SCIREA Journal of Chemistry. Volume 1, Issue 1, October 2016 | PP. 31-48.

References

[ 1 ]	Wrenn ME, Singh NP, Cohen N, Ibrahim SI, Saccomanno G (1981) Thorium in Human Tissues. NUREG/CR-1227, US.
[ 2 ]	International Commission on Radiological Protection (1978) Limits for intakes by workers. ICRP Publication 30, Pergammon Press, Oxford.
[ 3 ]	Hart EI, Boag JW (1962) Absorption Spectrum of the Hydrated Electron in Water an in Aqueous solution. J. Am. Chem. Soc. 84: 4090-4095.
[ 4 ]	Ikezoe H (1996) Alpha Decay of a New Isotope of 209Th. Phys Rev C 54:2043–2046.
[ 5 ]	Begum A, Rab Molla MA, Ahmad GU, Mollah AS (1998) Determination of Plutonium some Environmental and Biological Samples by Alpha Spectrometry. J Radia Prot Austrlia 15:63-68.
[ 6 ]	Begum A, Rab Molla MA, Ahmad GU, Miah FK, Mollah AS (1994) Determination of Thorium in Agricultural and Biological Samples by Alpha Spectrometry. J Bang Acad of Sci 18: 163-170.
[ 7 ]	Jia G, Torri G, Ocone R, Di Lullo A, De Angelis A, Boschetto R (2008) Determination of thorium isotopes in mineral and environmental water and soil samples by alpha-spectrometry and the fate of thorium in water. Appl Radiat Isot 66:1478-87.
[ 8 ]	LaFlamme BD, Murray JW (1987) Solid/solution interaction: The effect of carbonate alkalinity on adsorbed thorium. Geochim. Cosmochim. Acta 51: 250.
[ 9 ]	Harmsen K, De Haan FAM (1980) Occurrence and behavior of uranium and thorium in soil and water. Neth J Agric Sci 28:62.
[ 10 ]	Anderson RF, Bacon MP, Brewer PG (1982) Elevated Concentrations of Actinides in Mono Lake (California, USA). Science 216: 514-516.
[ 11 ]	Clemencia Rodriguze, Devine B, Cook A, Weinstein P, Van Buynder P (2009) Gross Alpha and Gross Beta Particle Activity in Recyled water supplies. J water supply: Resear and Tech 58: 191-202.
[ 12 ]	Taskayev AI, Popova ON, Alexakhin RM (1986) Root Absorption of Radon-222 and its Transfer into Above Ground Plant Organs. Health Phys 50: 589-594.