137Cs concentration in the environment of Kaiga of south west coast of India.

Abstract

This paper presents the results of 137Cs activity in soil and vegetation obtained through a carefully planned pre-operational survey for the establishment of baseline data on background radiation level and distribution of radionuclides in the environment of Kaiga, in the south west coast of India, where two nuclear power reactors of 235 MWe each are under construction. The vertical profile in soil and the seasonal variation in the activity have been studied. Nine commonly available vegetation species of Kaiga region were analyzed for their 137Cs activity, and the soil-to-plant transfer coefficients were evaluated. Measurements were made by gamma spectrometry method employing a 90 cc HpGe detector and a 3 x 3-inch well type NaI(Tl) detector. Results show significant levels of 137Cs activity in soil samples--ranging from below detection limit (BDL) to 65.4 Bq kg(-1). The mean value of activity observed in 0-5 cm soil profiles of Kaiga environs is significantly higher when compared to the reported values for other environs of India. Depth profile studies show that the 137Cs activity decreases with the increasing soil depth, and it is below detection limit for depths more than 25 cm. The mean value of effective dose commitment due to the presence of 137Cs in soil was 167.2 microSv. Vegetation samples of the region show elevated levels of 137Cs concentration. Epiphytic plants Cymbidium aloifolium (Lo.) Swartz. and Petrobryopsis tumida (Hook.) Dix. have been identified as bio-indicators to monitor the fallout of this radionuclide in the environment of Kaiga. Seasonal variation studies indicate higher fallout of this radionuclide along with rain.