RESUMO
The radiometric monitoring carried out in the present study allowed the discovery of anomalous granite outcrops in natural radionuclides in the rural area of São Mamede in the state of Paraíba, Brazil. The characterisation study made it possible to determine maximum specific concentrations of approximately 199 kBq kg-1 of 238U, 85 kBq kg-1 of 226Ra, 26 kBq kg-1 of 232Th and 24 kBq kg-1 of 40K. Models for environmental dosimetry were applied, which resulted in obtaining the following quantities: radium equivalent (Raeq), indices of external (Hex), internal (Hin) and representative (Iyr) damage, and the effective outdoor dose (HE). The maximum results presented were approximately 123 kBq kg-1, 332, 562, 832, and 68 mSv y-1, respectively. Consequently, it was possible to define the region as of high radioactive background due to isolated rocky outcrops located in the rural area of the mentioned municipality.
Assuntos
Radiação de Fundo , Radioisótopos de Potássio/análise , Monitoramento de Radiação/métodos , Rádio (Elemento)/análise , Poluentes Radioativos do Solo/análise , Tório/análise , Urânio/análise , BrasilRESUMO
Environmental radioactivity studies have been allowed establishing radiometric patterns in several area of the earth's crust. The work was conducted through radiometric analyses of regions with high levels of radionuclides and others with no history of anomalies. The research allowed establishing the radiometric profile of soils in the state of Pernambuco, Brazil, using a gamma spectrometry system. The specific activities ranged from 16.5 to 287.5 Bq kg-1 for 238U, 2.0 to 191.7 Bq kg-1 for 226Ra, 1.3 to 281.4 Bq kg-1 for 232Th and from 5.0 to 2600.9 Bq kg-1 for 40K. The results showed areas with low levels of ionizing radiation. However, for 40K some points presented high values, although non-representative of the number of samples investigated. The 226Ra/238U and 232Th/238U ratios allowed to determine the radioactive imbalance condition and to obtain information about aspects of soil availability providing an assessment of the dynamics of these radionuclides.