Estudo de solos antropogênicos da Amazônia utilizando a espectroscopia Raman

Abstract

The Terras Pretas de Índios da Amazônia are very productive soils found in northern Brazil. These soils are fleeing from the reality of tropical regions, deeply affected by heavy rains and high temperatures. Studies have shown higher amounts of black carbon and polycyclic aromatic structures which are related to the stability of the soil organic matter (SOM) and essential to the long-term productivity of the soils. In this work the Raman spectra of carbon forms present in three different Terras Pretas de Índios (TPIs) da Amazônia samples and a soil sample from Belo Horizonte - MG are analyzed using a 632,8 nm (1.96 eV) laser. The spectra of charcoal produced from Manaus AM typical plant species at a temperature of 600°C, as well as Diamondlike Carbon (DLC) thin films that went through different thermal treatment temperatures are analyzed and compared with those of the TPI.s. The defect induced mode (D band 1350 cm-1) and the tangential stretching mode (G band 1580 cm-1) are observed and the analysis of the band shapes shows different phases for the TPI.s samples, allowing their distinction from charcoal samples produced under controlled laboratory conditions. The amount of sp2 and sp3 hybridizations and the presence of polycyclic and distorted chains determine the spectroscopic signature.