Humic fractions from Amazon soils: Lifetime study and humification process by fluorescence spectroscopy

The Amazon Forest is an important and primordial ecosystem, as it controls the dynamics of soil organic matter (SOM) considered one crucial carbon reservoirs in world. Based on that, this study evaluated molecular properties humic (HA) fulvic (FA) acid from soil, with without Cu(II) ions, by Time-Resolved Laser Fluorescence Spectroscopy (TRLFS) (FS). excitation-emission matrix (EEM) was obtained FS, EEM spectra were treated canonical polyadic/parallel factor analysis (EEM-CP/PARAFAC). results showed that humification index (A465nm) determined FS directly dependent fluorophores’ CII/CI ratio these soils depth (r = 0.89), especially for HA samples deep horizons, which demonstrated CII consists more complex humified structure SOM. lifetime decay presence static quenching fractions. From data provided TRLFS different correlations content A465nm, can be suggested fluorescence suppression modifies fractions addition such altering mobility availability metal complexation reactions Amazonian Spodosols, mainly fraction.