137Cs global fallout in Latin-American and Antarctic soils,

MUNIZ, M.; CARDOSO, R.; FAGUNDES, B.; MEIGIKOS DOS ANJOS, R.; J. JURI AYUB; LOHAIZA F.; H. VELASCO; RIZZOTTO, M.

Sao Sebastiao

Congreso; XXXV Reunião de Trabalho sobre Física Nuclear no Brasil; 2012

Sociedade Brasileira de Fisica

For North hemisphere and European countries information about the 137Cs content in soils due to global fallout is very extensive; and the resulting patterns are well known and understood. For Latin American soils the information is more scarce and scattered. In the last years with the beginning of the use of 137Cs to determine soil redistribution rates, information about 137Cs soil content in several experimental sites (reference sites) can be found in the literature for some Latin American countries; and it is now possible to expand our understanding of how has been the 137Cs fallout in this region. With this aim in mind a database of 137Cs areal activity density was constructed. The database contains more than 330 values of 137Cs for Latin America and Antarctic regions. The database was elaborated using bibliographic sources and personal data. When the effect of the latitude is evaluated, a typical pattern is found. The 137Cs soil content increases from Ecuador and the Antarctic region to the middle latitudes. The 137Cs values for each range of latitude are lower than that reported for the Northern hemisphere, but higher than that estimated by UNSCEAR for the Southern hemisphere. For the Latin American region, the 137Cs areal activity density shows correlation with the annual mean rainfall rate (Pearson coefficient  0.6). Although this coefficient value is not large, taking into account the large surface of land assessed, the effect of precipitation should not be rejected. In order to assess the distribution within these vast areas, the available data were grouped according to geographical location and maps of 137Cs fallout and annual mean rainfall were constructed and analyzed, focused in the like