Datação da fração humina da matéria orgânica do solo e sua comparação com idades 14C de carvões fósseis

Química Nova

Susy Eli Marques Gouveia²  Luiz Carlos Ruiz Pessenda²  Ramon Aravena¹ 

[1] ,Universidade de São Paulo Centro de Energia Nuclear na Agricultura São Paulo SP

关键词: charcoal;    humin fraction;    radiocarbon dating;   

DOI  :  10.1590/S0100-40421999000600007

来源: SciELO

【 摘 要 】

The radiocarbon dating of the soil organic matter (SOM) is a polemic subject, due mainly to the complexity of the formation of the soils and to the variable contamination from several sources. Soil samples from 4 different Brazilian localities were submitted to physical and chemical pre-treatment for the extraction of humin fraction, which is the most stable organic compound and theoretically the oldest and representative of the age of the SOM. The radiocarbon dating obtained from the total SOM and their humin fractions are compared to the 14C ages from buried charcoals at similar depths. The radiocarbon ages obtained from such charcoals are, in most of the cases, concordant within the experimental errors of those obtained on humin fractions, or are in average 10% higher, with one exception. Thus, the ages on humin fractions could be assumed as the minimum ages for the associated soils, while the results obtained on total SOM, even at depths until 200 cm, exhibit pronounced contamination effect by modern carbon, rejuvenating their ages.

【 授权许可】

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