Distribution and enrichment of 210Po in the environment of Kaiga in South India

Several soil and vegetation samples from the environment of Kaiga nuclear power plant site in the south western region of India were analysed for Po-210. The vertical profile, particle-size distribution, seasonal variation and the dry deposition rate of Po-210 were measured employing the chemical method and alpha - counting technique. Po-210 activity in soil varies from 17.1 to 228.2 Bq kg(-1) with a mean value of 83.3 Bq kg(-1). The activity of Po-210 is higher in the surface soil (0-5 cm) and decreases as depth increases to 20 cm and remains nearly constant thereafter. The activity concentration is almost uniform in the grain sizes of 350-177 mu m and below 177 mu m. Pterobryopsis tumida (Hook.) Dir, a plant of the moss family, shows a very high level of Po-210 activity - 2724 +/- 13 Bq kg(-1). Seasonal variation studies show elevated levels of Po-210 in vegetation during winter. The annual dry deposition rate of Po-210 was 53.4 Bq m(-2) yr(-1). (C) 2000 Elsevier Science Ltd. All rights reserved.