Radium content in ground water from a granitic batholith of the metamorphic basement, eastern Sao Paulo State, Brazil

The radon emanation method was applied to measure the activity of Ra-226, dissolved and associated with suspended solids, in the ground waters from two wells drilled in the Morungaba Batholith fractured granites, intruded in the metamorphic basement, eastern border of the Parana basin in Sao Paulo State, Brazil. The water samples were collected from March 2003,to April 2004, with a time interval of about one month between sampling campaigns. The mean observed dissolved Ra-226 activity concentrations in the two wells were 47.9 +/- 7.1 and 51.6 +/- 8.8mBq/L. No systematic time dependence of the Ra-226 activity concentration was clearly identified. The activity of Ra-226 associated with suspended solids contained in I L of ground water fell, during the sampling period, from 13 +/- 1 to 0.8 +/- 0.1 mBq in one well and from 4.9 +/- 0.3 to 0.6 +/- 0.1 mBq in the second well. (c) 2006 Elsevier Ltd. All rights reserved.