Distribution and enrichment of 210Po in monazite areas of coastal Kerala

Significantly high radiation level and radionuclide concentration along Quilon beach area of coastal Kerala have been reported by several investigators. However systematic studies on the distribution and enrichment of 210Po, an important daughter product of 238U, has not been reported. In view of this, detailed studies on the distribution and enrichment of 210Po was undertaken in the coastal areas of Karunagapalli, Chavara, Neendakara and Kollam. As part of the programme, detailed gamma radiation level survey was carried out using a portable scintillometer. The sand samples collected at different depth from these beaches were analyzed for 210Po activity to understand the distribution and enrichment of 210Po in different depth intervals. Soil samples collected from inland of the beach area were also analysed for 210Po activity. The absorbed gamma dose rates in air in high background area is in the range 43- 17400 nGyh-1. Gamma radiation level is found to be maximum at a distance of 20 m from the sea waterline in all beaches. The 210Po activity in sand at waterline varies in the range 2.4 to 20.5 Bq kg-l with a mean value of 8.3 Bq kg-1. For sand samples 20 m away from the waterline, the activity varies from 2.5 to 19.9 Bq kg-1 with a mean value of 10.2 Bq kg-1 for 0-10 cm depth, for 10-20 cm it varies from 1.9 to 16.7 Bq kg-1 with a mean value of 8.0 Bq kg-1 and for 20-30 cm, activity varies from 2.4 to 19.1 Bq kg-1 with a mean value of 7.7 Bq kg-1. For sand samples 40 m away from waterline the activity varies from 2.1 to 6.7 Bq kg-1 with mean of 3.5 Bq kg-1 for 0-10 cm depth, for 10-20 cm it varies from 3.3 to 4.7 Bq kg-1 with a mean value of 3.7 Bq kg-1 and for 20-30 cm the activity varies from 2.8 to 6.5 Bq kg-1 with a mean value of 4.7 Bq kg-1. For surface soil the activity is in the range 3.1 -6.7 Bq kg-1 with a mean value of 4.7 Bq kg-1. The results of these studies are presented and discussed in this paper. (author)