Abstract

BOLZON-DE MUNIZ, G. Inés; LOMELI-RAMIREZ, M. Guadalupe; MANGRICH, Antonio S.  and  CARBAJAL- ARIZAGA, G. Guadalupe. Fast qualitative method based on electron paramagnetic resonance (EPR) to date Gmelina arborea and Araucaria angustifolia wood. Agrociencia [online]. 2014, vol.48, n.7, pp.739-749. ISSN 2521-9766.

In Brazil, Gmelina arborea is a common tree to produce char and the content of carbon is an important factor to correlate with the energy content or carbon sequestration capability, whereas Araucaria angustifolia occupies 6 % of its original territory and Brazilian laws protect old native specimens, since the commercial use of wood is restricted for young cultivated specimens. Electron paramagnetic resonance (EPR) spectroscopy is used for detection and quantification of organic free radicals (OFR) and, in this study, it was utilized for exploring OFR content along the rings of one log from G. arborea and A. angustifolia trees, both randomly chosen. The amount of OFR correlated with the carbon content in G. arborea and the age of rings in G. arborea and A. angustifolia. The content of OFR in rings of Gmelina arborea was compared with previous analyses of carbon sequestration in the same tree. Without statistical treatment, an inverse relationship between the carbon and OFR content was found. The concentration of OFR in inner rings (older ages) of A. angustifolia was higher than in outer rings (younger ages). This trend was also observed in G. arborea, suggesting that EPR provides qualitative information about the age. Additionally, a Pleistocene sample of A. angustifolia was analyzed and the content of OFR was one order of magnitude higher than that in the young sample. In conclusion, EPR spectroscopy is proposed as a fast qualitative method to identify the age of wood, especially for confiscated wood loads in protected areas of A. angustifolia and to determine the carbon content in wood.

Keywords : Araucaria angustifolia; electron paramagnetic resonance; organic free radicals; Gmelina arborea.