Níveis de radioatividade natural decorrente do radônio no complexo rochoso da Serra de São Vicente, SP

Abstract

OBJETIVO: Realizar monitoração passiva e integrada do radônio em várias amostras de águas, solos e locais fechados do complexo rochoso da Serra de São Vicente, SP, com o intuito de avaliar a distribuição de ocorrência deste gás radioativo naquele local. MATERIAIS E MÉTODOS: A técnica utilizada consistiu em expor detectores plásticos policarbonatos (SSNTD) do tipo Makrofol E, na geometria de copo fechado, ao radônio emanado das amostras de águas coletadas dos solos e ao acumulado em ambientes internos (residências e cavidades nas rochas) existentes no complexo rochoso de São Vicente. RESULTADOS: Os valores obtidos para os teores de radônio variaram entre 8,1 e 36 Bq/l para as fontes de água natural, entre 68 e 610 Bq/m³ nas residências, entre 0,41 e 3,46 kBq/m³nos solos e entre 0,72 e 5,85 kBq/m³ nas cavidades do Maciço de São Vicente. CONCLUSÃO: Para algumas residências e na maioria das fontes de água estudadas, os teores de radônio encontrados neste trabalho estiveram acima dos limites máximos propostos por organismos internacionais. Recomenda-se, portanto, que ações de intervenção sejam implementadas para a dissipação do radônio, tanto nessas residências como durante a coleta das águas para fins de consumo.

The role of the implementation of policies for the prevention of exposure to Radon in Brazil—a strategy for controlling the risk of developing lung cancer

“…Marques et al (2006) identified a relatively high concentration of Rn in the water, residences, soil, and caves in a Brazilian region, which in some cases reached levels above the maximum limits recommended internationally. The authors suggest that intervention activities be implemented for the dissipation of Rn both in residences and during the collection of water for human consumption [ 8 ].…”

“…Rn is an inert natural gas, and is a product of the decay of Radium-226 (Ra-226) [ 7 ]. Its concentrations are directly related to the type of geologic formation of a specific region, given that the types of rock that compose these soils can contain smaller or larger quantities of the minerals Uranium (Ur), Thorium (Th), and Radium (Ra), the natural producers of Rn-222 [ 8 ].…”

“…This gas can escape through fissures or be transported from the subsoil to the surface by means of pipes, holes, and groundwater deposits, and thus become a source of exposure for the people who reside in or frequent these areas [ 8 , 9 ].…”

Uranium content and dose assessment for sediment and soil samples from the estuarine system of Santos and Sao Vicente, SP, Brazil

“…For these chemical etching conditions, the fission tracks produced in the detectors presented the best visibility condition when observed in a common optical microscope. The fission tracks were counted scanning all the detector deposit area with a system consisting of a binocular optical microscope, at a magnification of Â400, together with a video camera and a PC (5) . For each sample, it was scanned at least four deposit areas in the plastic films and the final result was calculated by the average of the values obtained in the fission tracks counting.…”