Distribution and enrichment of Po-210 in the environment of Kaiga in SouthIndia

Several soil and vegetation samples from the environment of Kaiga nuclear p ower plant site in the south western region of India were analysed for Po-2 10. The vertical profile, particle-size distribution, seasonal variation an d the dry deposition rate of Po-210 were measured employing the chemical me thod 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 increa ses to 20 cm and remains nearly constant thereafter. The activity concentra tion 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 ve ry high level of Po-210 activity - 2724 +/- 13 Bq kg(-1). Seasonal variatio n studies show elevated levels of Po-210 in vegetation during winter. The a nnual dry deposition rate of Po-210 was 53.4 Bq m(-2) yr(-1). (C) 2000 Else vier Science Ltd. All rights reserved.