US EPA

3796148 

Technical Report 

Cesio-137 E Radionuclideos Naturais Em Solos Do Sul Do Brasil E Em Solos E Outras Amostras Ambientais DA Antartica (Cesium-137 and Natural Radionuclides in Soils from Southern Brazil and in Soils and Others Environmental Samples from Antarctic) 

Schuch, LA 

1993 

NTIS/02996977 

GRA and I 

GRA and I 

This work presents a study of environmental artificial and natural radioactivity levels in soil samples from Southern Brazil and in soils and other environmental samples from Antarctica. Artificial radioactivity was determined by measuring Cs-137 which is a 30.1 year half-life man-made radionuclide produced in the past by atmospheric tests of nuclear weapons. Natural radioactivity was determined by measuring some radionuclides belonging to Th-232 and U-238 natural radioactive families, and of K-40 concentrations. Several types of soil from Southern Brazil and soil samples, marine sediments, lichens, mosses, and algae collected at King George and other nearby islands (South Shetland Archipelago, Antarctica) were analyzed. A gamma-ray spectrometer was used to measure radioactivity levels of the collected samples and its overall characteristics are analyzed. Measurements on the collected samples have shown: low radioactivity levels when compared with similar samples from the Northern Hemisphere; the characteristic latitudinal variation of the fallout product Cs-137; higher Cs-137 lixiviation when compared with that of natural radionuclides in soils collected at different dates; the impossibility to measure in collected soil samples fallout products from Chernobyl nuclear accident that occured in April, 1986; and low correlation of Cs-137 concentrations with some pedological parameters. A high linear correlation was observed between the integrated Cs-137 concentrations, in Bqm(exp -2), and organic carbon, in individual vertical soil profiles. However this is not observed when the integrated Cs-137 concentrations are compared in all the profiles, with the mean value of organic carbon for each profile. It was also observed that among environmental samples from Antarctic, lichens and mosses have shown the highest Cs-137 concentrations. These results are being used to select the species that will be used for yearly fallout follow-up among the most abundant ones.