Resumen
Natural radioactivity, namely 226Ra, 232Th and 40K, was determined in commercial granite samples of 6 quarries of Espírito Santo State, southeast Brazil, located in regions of municipalities Ecoporanga, Nova Venécia, Colatína, Afonso Cláudio, Castelo and Mimoso do Sul. All samples were measured by high resolution gamma spectrometry after a 30-days ingrowth period. The results show concentrations varying from 40±5 Bq·kg-1 to 225±20 Bq·kg-1 for 232Th, from 20±5 Bq·kg-1 to 275±15 Bq·kg-1 for 226Ra and from 520±20 Bq·kg-1 to 1405±60 Bq·kg-1 for 40K. The radium equivalent index, considering the activity concentrations, ranged from 190±60 Bq·kg-1 to 475±70 Bq·kg-1. The southern region of Espírito Santo State (Afonso Claudio, Castelo and Mimoso do Sul) shows the highest values concentrations for 226Ra, 232Th and 40K, while the lowest values were observed for the central and north region (Colatina, Nova Venécia and Ecoporanga).