Doses from 222Rn, 226Ra, and 228Ra in groundwater from Guarani aquifer, South America

Natural radioactivity in Brazilian groundwater

“…Other publications dealing with natural radionuclides in groundwater in Brazil can be found in the literature (Almeida et al, 2004;Bonotto, 2004;de Oliveira et al, 1998de Oliveira et al, , 2001. However, their results were not included in this database because either the sampling points were already included on it or no information about the sampling points was available, or only few sampling points were in common with the present publication and a similar data validation was not possible.…”

A combined method for evaluating radon and progeny in waters and its use at Guarani aquifer, São Paulo State, Brazil

“…radionuclides ingestion by humans (mSv/Bq), and the amount of people utilizing the water must be known. The population-weighted average activity concentration must also be estimated and an equation involving the sum of the activity concentration (Bq/L) of every individual radionuclide measured in each sample is then utilized for such purpose (Oliveira et al, 2001;Bonotto, 2004). All these factors must be addressed for proper dose evaluation due to radon ( 222 Rn) and its progeny ( 214 Pb and 214 Bi) in drinking water.…”

“…The first aspect to be considered is that there is no consensus in the scientific community on the value of the dose conversion factor for 222 Rn and a value of 10 ÿ8 Sv/Bq resulting from the application of a modified ICRP model for the ingestion of 222 Rn in water has been adopted by different authors like Kendall et al (1988), Oliveira et al (2001) and Bonotto (2004), among others. The use of such factor and assuming 100 Bq/L as the guideline value for 222 Rn volumetric activity in drinking water for public water supplies allows estimate 0.7 mSv/year as an individual dose criterion, which is a value seven times higher than the WHO (2004) value of 0.1 mSv/year.…”

“…The alpha counting was performed utilizing ZnS(Ag) as the scintillation material and a photomultiplier tube coupled to a counter/timer assembly as described by Bonotto (2004). It allows calculation of the 222 Rn volumetric activity, whereas the gamma spectrometry permits direct measurement of their short-lived daughters 214 Pb and 214 Bi.…”

Development and calibration of a portable radon sampling system for groundwater 222Rn activity concentration measurements

“…As a consequence, 222 Rn is normally in great radioactive disequilibrium with its parent 226 Ra nuclide in groundwater. The 222 Rn activity concentration in groundwater mostly varies in the broad interval between 1 Bq/dm 3 and 1000 Bq/dm 3 Kahlos, 1979, 1980;Bonotto, 2004;Dillon et al, 1991;Zhuo et al, 2001), but local concentrations up to 10 000 Bq/dm 3 or more have been reported in the literature (e.g. Brutsaert et al, 1981).…”