Radionuclídeos naturais e artificiais em seis perfis de solos do estado do Rio Grande do Sul

Luiz Alexandre Schuch, Daniel Jean Roger Nordemann, Ari Zago, Brigitte Pecequilo, José Marcos Godoy


Concentrations of natural radioactive series radionuclides, of K-40, and of radioactive fallout Cs-137 are determined. Many physical, chemical and biological parameters influence the radioactivity vertical distribution in soils. Among these factors are soil type and characteristics; rainfall; superficial layers perturbations and other peculiar properties of the soil such as concentration and types of clay mineral, organic matter, etc. High performance gamma-ray spectrometry is used to determine radionuclide concentrations. Ten samples of each type of soil are collected, down to 50 cm with samples collected every 5 cm. pH, clay concentration, organic carbon and K+, Na +, Ca++ and Mg++ cations and total acidity are analyzed, among other parameters. Data on local pluviometry, temperatures and relief, latitude, longitude and altitude are also collected. It is observed that the highest concentrations of Cs-137 are found in the three uppermost superficial samples for every profile. More than 60% of the Cs-137 lays within the 25 cm uppermost layer for all sampling locations. It is observed for soil superficial samples of every profile, a high linear
correlation between Cs-137 concentration and organic carbon concentration and that, down to a depth of 50 cm, Ac-228 and TI-208 concentrations do not vary appreciably for different equivalent samples. These results help showing the state of relative equilibrium within the six profiles studied. So it may be observed that these soils have not suffered from erosion and that lixiviation process is not important for these elements which belong to natural radioactive series.


Aarkrog, A. The radiological impact of the Chernobyl debris compared with that from nuclear weapons fallout. Joumal of Environmental Radioactivity 2:151-162, 1988.

Aoyama, M.; Hirose, K.; Sugimura, Y. The temporal variation of stratospheric fallout derived from the Chernobyl accident. Journal of Environmental Radioactivity, li: 103-115, 1991.

Arnalds, O.; Cutshall, N.H.; Nielsen, G.A. Cesium-137 in Montana soils. Health Physics, 57(6): 955-958, Dec. 1989.

Arruda-Neto, J.D.T. The content of alpha particle emitters in Brazilian tobacco, and the associated problem o( high cancer risk in snokers. São Paulo, Instituto de Física, USP, Sep. 1988.

Bettencourt, A.O.; Teixeira, M.M.G.R.; Elias, M.D.T.; Faisca, M.C. Soil to plant transfer of radium-226. Journal of Environmental Radioactivity, Q: 49-60, 1988.

Bunzl, K.; Kracke, W. Cumulative deposition of Cs-137, Pu-238, Pu-239+240 and Am-241 from global fallout in soils from forest, grassland and arable land in Bavaria (FRG). Journal of Environmental Radioactivity, 8: 1-14, 1988.

Carter, M.W.; Moghissi, MAA Three decades of nuclear testing. Hea1th Physics, 33:55-71, Jul. 1977.

Cox, M.E.; Fankhauser, B.L. Distribution of fallout cesium-137 in Hawaii. Health Physics, 46(1): 65-71, Jan. 1984.

Ehhalt, D.H.; Haumacher, G. The seasonal variation in the concentration of strontium-90 in rain and its dependence on latitude. Journal of Geophysical Research, 75(15):3027-3031, May 1970.

Eisenbud, M. Environmental radioactivity. 3. ed. Orlando, FO, Academic, 1987.

Eisenbud, M.; Paschoa, AS. Environmental radioactivity. Nuclear Instruments and Methods in Physics Research, A280:470-482, 1989.

Erdtmann, G.; Soyka, W. The gamma rays of the radionuclides -tables for applied gamma ray spectrometry. Weinheim, NY, Verlag Chemie, 1979.

Fabian, P.; Libby, W.F.; Palmer, C.E. Stratospheric residence time and interhemispheric mixing of strontium 90 from fallout in rain. Journal or Geophysica1 Research, 73(12):3611-3616, Jun. 1968.

Guimarães, M.F. Césio-137 da precipitação radioativa ("fallout") no estudo da erosão e sedimentação de solo. (Tese de doutoramento) - ESALQ-USP, Piracicaba, ago. 1988

Kogan, R.M.; Nazarov, I.M.; Fridman, S.D. Gamma spectrometry of natural environments and (formations. Jerusalem, Israel Program For ScientificTranslations, 1971.

Lin, Y.M.; Lin, P.H.; Chen, C.J.; Huang, C.C. Measurements of terrestrial radiation in Taiwan, Republic of China. Hea1th Physics, 52(6):805-811, Jun. 1987.

Linsalata, P.; Morse, RS.; Ford, H.; Eisenbud, M.; Penna Franca, E.; Castro, M.B.; Lobao, N. An assessment of soil-to-plant concentration ratios for some natural analogues of the transuranic elements. Health Physics, 56(1): 33-46, Jan. 1989.

Moreira-Nordemann, L.M.; Sieffermann, G. Distribution of uranium in soil profiles of Bahia State, Brazil. Soil Science, 127(5):275-280, 1979.

Nyhan, J.W.; White, G.C.; Schofield, T.G.; Trujillo, G. An evaluation of soil sampling for 137Cs using various field-sampling volumes. Health Physics, 44(5): 541-552, May 1983.

Oliveira, H. Radioatividade natural em solos do município de Piracicaba. (Tese de Mestrado) - ESALQ-USP, Piracicaba, out, 1988.

Pereira, E.B.; Hamza, V.M.; Furtado, V.V.; Adams, J.A.S. U, Th and K content, heat production and thermal conductivity of São Paulo, Brasil, continental shelf sediments: a reconnaissance work. Chemical GeoIogy, 58: 217-226, 1986.

Picciotto, E.; Wilgain, S. Fission products in Antarctic snow, a reference level for measuring accumulation.Journal of Geopbysical Research, 68 (21): 5965-5972, Nov. 1963.

Sakai, T. Distribuição do Cs-137 nos solos do Estado da Bahia. (Tese de Mestrado) – Universidade Federal da Bahia (UFBa), Fev. 1977.

Schuch, L.A. Césio-137 e Radionuclídeos Naturais em Solos do Sul do Brasil e em Solos e outras Amostras Ambientais da Antártica. (Tese de Doutorado) - Instituto Nacional de Pesquisas Espaciais (INPE), Abr. 1993.

Schuch, L.A.; Nordemann, D.J.R.; Zago, A.; Dallpai, D.L.; Godoy, J. M.; Pecequilo, B. Correlation of natural and artificial radionuclides in soils with pedological, climatological and geographic parameters. Joumal of Radioanalytical and Nuclear Chemistry; 177 (1): 101-106, 1994a.

Schuch, L.A.; Nordemann, D.J.R.; Barreto, W.O.; Cardoso, A.; Zago, A. Natural and artificial radionuclides of soils from Paraná State, Brazil. Journal of Radioanalytical and Nuclear Chemistry, 177 (1): 39-49, 1994b.

Vasconcellos, L.M.H.; Amaral, E.C.S.; Vianna, M.E.; Penna-Franca, E. Uptake of Ra-226 and Pb-210 by food crops cultivated in a region of high natural radioactivity in Brasil. Journal of Environmental Radioactivity, 2: 287-302, 1987.

Vettori, L. Método de análise de solo. Equipe de Pedologia e Fertilidade do Solo. Ministério da Agricultura, Jul. 1969. (Boletim Técnico, nº 7).

Walton, A. The distribution in soils of radioactivity from weapons tests. Journal of Geophysical Research, 68 (5): 1485-1496, Mar. 1963.


Copyright (c) 1995 Ciência e Natura

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.