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 210Po. The vertical profile, particle-size distribution, seasonal variation and the dry deposition rate of 210Po were measured employing the chemical method and α – counting technique. 210Po 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 210Po 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 μm and below 177 μm. Pterobryopsis tumida (Hook.) Dix, a plant of the moss family, shows a very high level of 210Po activity — 2724±13 Bq kg−1. Seasonal variation studies show elevated levels of 210Po in vegetation during winter. The annual dry deposition rate of 210Po was 53.4 Bq m−2 yr−1.