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Dissolved organic matter sorption on sub soils and minerals studied by 13 C‐NMR and DRIFT spectroscopy
Author(s) -
KAISER K.,
GUGGENBERGER G.,
HAUMAIER L.,
ZECH W.
Publication year - 1997
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/j.1365-2389.1997.tb00550.x
Subject(s) - sorption , chemistry , ferrihydrite , dissolved organic carbon , soil water , clay minerals , goethite , alkyl , mineral , nmr spectra database , organic matter , protonation , inorganic chemistry , environmental chemistry , mineralogy , spectral line , geology , organic chemistry , ion , adsorption , soil science , physics , astronomy
Summary Sorption on the mineral matrix is an important process restricting the movement of dissolved organic matter (DOM) in soils. In this study, we aimed to identify the chemical structures responsible for the retention of DOM by sorption experiments with total DOM and acidic humic substances (AHS), containing humic and fulvic acids, on soil samples and minerals (goethite, ferrihydrite, and amorphous Al(OH) 3 ). The AHS remaining in solution after sorption were studied by 13 C nuclear magnetic resonance (NMR) analysis, and total DOM and AHS for bed on the surfaces of minerals by diffuse reflectance Fourier‐transform infrared (DRIFT) spectroscopy. The soil samples were taken from strongly sorbing Bw horizons of two Inceptisols rich in pedogenetic Fe (29 and 35 g kg −1 ) and containing little C (7 and 22 g kg −1 ). The 13 C‐NMR spectra showed that sorption causes a preferential removal of aromatic and carboxyl C from the solution, whereas alkyl‐C accumulates in the solution. No change was observed for O‐alkyl C. The DRIFT spectra of sorbed total DOM and AHS showed a relative increase of the band intensity of carboxyl groups compared to DOM in the initial solution, confirming the importance of those groups for the sorption to mineral surfaces. The spectra also indicated reactions of carboxyl groups with metals at the mineral surfaces. The extent to which the carboxyl groups are bound depended on the surface coverage with DOM and the type of mineral.