Gross alpha- and beta-activities in surface and ground water of Rio Grande do Norte, Brazil.
Gross alpha- and beta-activities were determined on 37 fresh water samples collected from 14 artificial basins, 13 deep drilled wells, two dug wells, two lakes, two rivers, one spring, and a tap belonging to 30 locations scattered throughout the eastern and central parts of the Brazilian state of Rio Grande do Norte. The surveyed area was about 35,000 km2 with a lithology including both crystalline (18 towns) and sedimentary (12 towns) rocks. Concentrations ranging from < 2.8 to 354 Bq m-3 and from 50.5 to 580 Bq m-3 were observed for the gross alpha- and beta-activities, respectively. For the gross beta-activity, which was always higher than the corresponding alpha-activity, the arithmetic mean with its standard deviation was 226 +/- 154 Bq m-3. In order to evaluate the radioactive dose due to the ingestion of these waters, a conservative dosimetric calculation was carried out using the dose conversion factors suggested by the ICRP. An average annual effective dose equivalent of 60 +/- 42 microSv was obtained together with a range of 14-161 microSv y-1.
Malanca
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Department of Physics, University of Parma, Italy. malanca@fisica.unipr.it
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de Macêdo
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D000512:Alpha Particles; D001610:Beta Particles; D001938:Brazil; D005618:Fresh Water / Q000032:analysis*; D014878:Water Pollution, Radioactive / Q000032:analysis*; D014881:Water Supply / Q000032:analysis*