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Alkyl C and hydrophobicity in B and C horizons of an acid forest soil
Author(s) -
Rumpel Cornelia,
Seraphin Ariane,
Goebel MarcOliver,
Wiesenberg Guido,
GonzalesVila Francisco,
Bachmann Jörg,
Schwark Lorenz,
Michaelis Walter,
Mariotti André,
KögelKnabner Ingrid
Publication year - 2004
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/jpln.200421484
Subject(s) - subsoil , chemistry , cambisol , soil horizon , soil organic matter , organic matter , pyrolysis , hydrolysis , humus , environmental chemistry , alkyl , organic chemistry , soil water , geology , soil science
Aliphatic C most probably derived from ester‐bound moieties was found to be present in sandy subsoil horizons. The hydrophobic nature of such compounds may increase their stabilization potential. Therefore, the aim of this study was to investigate the potential of aliphatic compounds in mineral soil horizons along a Dystric Cambisol profile under beech forest to increase hydrophobicity. The conceptual approach included the analyses of soil samples before and after solvent extraction and base hydrolysis for elemental and isotopic composition. Additionally, the advancing contact angle was measured to quantify hydrophobicity. Curie‐point pyrolysis GC/MS was carried out to characterize the nature of alkyl C present in subsoil samples. A close correlation between the 14 C activity and the stable‐C‐isotope ratio (δ 13 C) indicates isotopic fractionation upon C stabilization in subsoils. Free lipids contributed less than 10% to the organic C found in subsoil horizons. Base hydrolysis revealed very high amounts of hydroxyalkanoic acids in the B horizons of the acid forest soil. Hydrophobicity of SOM was not found to be correlated to esterified‐ or free‐lipid content. The contact angle was in a similar range for all bulk soil horizons, suggesting greater hydrophobicity of organic matter in subsoil horizons considering their very low concentrations of organic C compared to the A horizon. The quantity and nature of pyrolysis products change with increasing depth in the soil profile. Aliphatic products cannot be detected in B and C horizons by Curie‐point pyrolysis GC/MS.