Radionuclídeos como marcadores de um novo tempo: o Antropoceno

AUTOR(ES)

Silva, Cleyton Martins da; Arbilla, Graciela; Machado, Wilson; Soares, Ricardo

FONTE

Quím. Nova

DATA DE PUBLICAÇÃO

2020-04

RESUMO

On May 2019, the members of the Anthropocene Working Group completed a binding vote to affirm some of the key questions that have been agreed in 2016: the Anthropocene should be considered as a formal chronostratigraphic unit, defined by a Global Boundary Stratotype Section and Point (GSSP), using one of the stratigraphic signals around the mid-twentieth century of the Common Era. The fallout from nuclear weapons testing appears as the most suitable GSSP. In this article, the main anthropogenic markers are discussed as well as the sources or human-made radiation and the signature of nuclear weapons testing. The appearance of 239+240Pu in the early 1950s and the clear peak, in 1963, makes a good marker. High resolution archives include layers of sedimentary rocks, lacustrine and marine sediments and corals and polar ice cores. A coupled application of other radioactive isotopes, as 137Cs, 14C and 241Am, may be useful to categorize distinct fallout signatures. A site to define the Anthropocene (golden spike) would ideally be located between 30º and 60º north of the equator. Nevertheless, results obtained in sediments on the Brazilian coast showed that both 239+240Pu and 137Cs signatures could be detected and quantified as markers of this “atomic age”.

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