doctoralThesis
Radioatividade natural: instrumentos legais e normativos no Brasil e interações do radônio outdoor com variáveis micrometeorológicas no planalto da Borborema
Fecha
2022-02-24Registro en:
ALBUQUERQUE, Bruno César Dias de. Radioatividade natural: instrumentos legais e normativos no Brasil e interações do radônio outdoor com variáveis micrometeorológicas no planalto da Borborema. 2022. 126f. Tese (Doutorado em Desenvolvimento e Meio Ambiente) - Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, 2022.
Autor
Albuquerque, Bruno César Dias de
Resumen
Radon is a colorless and odorless radioactive gas, the heaviest of all noble gases of natural
origin. Rocks and soils with high concentrations of Uranium and Thorium are the main sources
of Radon. Research has proven its carcinogenic power. There are studies that try to establish
relations between aspects that can influence the concentration of the gas into the atmosphere.
In Brazil the theme is little investigated and, in terms of legislation, it is restricted to the
exploration of Uranium and Nuclear Energy. In this context, the study aimed to answer three
hypotheses: the Brazilian legislation is outdated in relation to natural radioactivity and needs to
consider aspects related to the theme; the micrometeorological variables (temperature, air
humidity, solar radiation and winds) explain the pattern of 222Rn concentration in Cuité and
Bananeiras, municipalities of the State of Paraíba; the photosynthetically active vegetation
biomass explains the pattern of 222Rn concentration in Cuité and Bananeiras, in diverse climatic
periods. The main objectives of the research were: to evaluate how the Brazilian legislation and
the environmental standards address the natural radioactivity in different geochemical
compartments, and to evaluate if the micrometeorological variables and the variation of
photosynthetically active vegetation biomass explain the pattern of Radon concentration, in the
rainy and dry seasons. For this, the thesis was divided into three articles, which respectively
follow the sequence of the listed hypotheses. In the first article (chapter 1) bibliographic and
documental research was used, where the methodology of systematic mapping for
environmental sciences was employed; it was concluded that the Brazilian legislation is
incipient regarding natural radioactivity and that there are gaps regarding the radioactivity
present in environmental compartments. The second article (chapter 2) shows results of passive
measurements of 222Rn concentration in the low atmosphere and micrometeorological variables
during the rainy season in Bananeiras and Cuité. A statistical model of multiple linear
regression was applied, which indicated individual significance of the variables wind (negative
relationship) and solar radiation (positive relationship); the model analysis showed that the
222Rn concentration can indeed be influenced, but in a punctual way, without evidence of
predictive relationship in the context of the variables studied. In the third article (chapter 3), to
understand other factors of influence on the concentration of 222Rn and its variation in different
climatic periods, passive radon measurements were also made in Bananeiras and Cuité, during
the dry period, besides the sampling and analysis of soil and rock samples, and vegetation
analysis by means of vegetation indices. In the comparison with the 222Rn data measured in the
rainy period (article 2), no significant variations in the averages were observed. Vegetation
analysis by means of vegetation indices (NDVI) and site visits showed significant differences
in the areas in the different climatic periods, but there was no evidence of any influence on the
concentrations of 222Rn. The results suggest that the slightly higher values of 222Rn measured
in Bananeiras in the two periods may have been influenced by soil particle size, higher
vegetation density, and meteorological parameters (solar radiation, temperature, and wind) that
suggest less dispersion of the gas in comparison with Cuité. In summary, when analyzing in
general the hypotheses raised, the micrometeorological variables and the variations that
occurred in different climatic periods were apparently not able to overlap with the background
radioactivity profile for each location.