Spectroscopic characteristics of humates isolated from different soils
2011
Fasurova, N.,Vysoke Uceni Technicke, Brno (Czech Republic). Ustav Fyzikalni a Aplikovane Chemie | Pospisilova, L.,Mendelova Univ., Brno (Czech Republic). Ustav Agrochemie, Pudoznalstvi, Mikrobiologie a Vyzivy Rostlin
Spectral characterisation of soil humic substances is one of the important methods for their quality identification. In this work, two optical methods (UV-VIS and SFS) were used. The absorbance in the spectral range of 300-700 nm was measured using spectrometer Varian Cary 50 Probe. Fluorescence (SFS) in the range of 255-655 nm was performed by spectrofluorimeter Aminco Bowman. Five Czech soil humates samples (Leptic Cambisol, Haplic Cambisol, Eutric Cambisol 1-arable soil, Eutric Cambisol 2-grassland, Haplic Chernozem) were compared. The basic soil properties were determined by the commonly used methods. Colour indexes (Q4/6) were calculated from the absorbance of humic substances in UV-VIS spectral range. Fluorescence indexes (F) were calculated from SFS spectra at 55 nm (as a ratio RFI468/RFI522). The classical method of humic substances fractionation was applied to assess their quality. The calculated parameters from different spectral regions were compared with results of humic substances fractionation. There was a linear correlation between carbon concentration and fluorescence indexes (R2 = 0.91), between total organic carbon content in soil and fluorescence indexes (R2 = 0.92), as well as between colour indexes (Q4/6) and humic substances content. The same main fluorophores at the wavelengths 467/522 nm were observed in all soil humates samples.
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