Humic substances from typical Czech forest soil Humic Podzol: Chemical and spectroscopic characterisation

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The aim of this work was to study chemical composition, chemical properties and humification degree of different soil humic substances (HS). Five various samples of humic substances were the object of our study. Humic acids (HAs) and fulvic acid (FA) were isolated from typical Czech forest soil Humic Podzol (locality Krkonoše, Czech Republic). Isolation of soil humic substances was performed according to the procedure recommended by the International Humic Substances Society (IHSS). Samples of soil HS were compared with Elliott Soil humic acid (1S102H) and fulvic acid (2S102F) as standards of soil humic substances. All samples of soil HS were characterized by elemental analysis (EA), total organic carbon analysis (TOC), ultraviolet-visible spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR), steady-state fluorescence spectroscopy and nuclear magnetic resonance (13C NMR). The elemental composition was determined by a CHNS/O Microanalyser Flash 1112 Carlo Erba. Absorption coefficients (EET/EBz, E250/E365 and E465/E665) of soil HS were calculated from the absorbance values. Infrared spectroscopy is a useful technique in characterization of structure, functional groups and formation modes of HS. For the fluorescence experiments, the final concentration of the HS was adjusted to 10 mg∙L–1. The pH-value of the samples was adjusted to seven using a standard phosphate buffer. Fluorescence mono-dimensional spectra and total luminescence spectra (TLS) of soil HS were obtained using steady-state fluorescence spectroscopy. All fluorescence spectra were performed on a Horiba Scientific Fluorolog. Total luminescence spectra (TLS) were obtained in the form of excitation/emission matrix (EEM) by scanning of emission wavelengths over the range of 300–600 nm and the excitation wavelengths were in 5 nm steps from 240 to 550 nm. Fluorescence index (Milori index and HIX) of HS was calculated from the area of the emission spectra. The fluorescence intensity (IF) values (in CPS) of samples were corrected using method of Lakowicz. 13C NMR spectra of soil HS were obtained with a Bruker Avance III NMR spectrometer at an observation frequency of 125.8 MHz for 13C. The approximate number of scans was 25.000. Aromaticity (fa), hydrophilicity and hydrophobicity ratio (Hfi/Hfo) and biological activity (BiA) of HS were calculated from the area of the NMR spectra. Soil A55 HA was characterized high molecular weight, low molecular heterogeneity, high degree of aromatic polycondensation, high level of conjugated fluorophores, and high humification degree. HS isolated from organic horizon were characterized by lower molecular mass, simple structural components of wide molecular heterogeneity, lower degree of aromatic polycondensation, and lower humification degree.

soil humic substances, standards of soil humic substances IHSS, elemental analysis, UV/Vis, FTIR, 13C NMR and fluorescence spectroscopy, fluorescence and NMR structural parameters, aromaticity, hydrophilicity and hydrophobicity ratio, biological activity

ENEV, V.; NOVÁK, F.; TÜRKEOVÁ, I.; KLUČÁKOVÁ, M.

2015

3. 9. 2015

Global Network for Environmental Science and Technology (Global-NEST), University of the Aegean

Rhodos, Greece

978-960-7475-52-7

Proceedings of the 14th International Conference on Environmental Science And Technology, CEST2015

First

First

1106-5516

Proceedings of the International Conference on Environmental Sciene and Technology

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