Fulvic acid composition in degraded fenlands

Citation
P. Leinweber et al., Fulvic acid composition in degraded fenlands, J PLANT NU, 164(4), 2001, pp. 371-379
Citations number
29
Categorie Soggetti
Agriculture/Agronomy
Journal title
JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE-ZEITSCHRIFT FUR PFLANZENERNAHRUNG UND BODENKUNDE
ISSN journal
14368730 → ACNP
Volume
164
Issue
4
Year of publication
2001
Pages
371 - 379
Database
ISI
SICI code
1436-8730(200108)164:4<371:FACIDF>2.0.ZU;2-#
Abstract
Fulvic acids (FAs) from topsoil and ground water solutions were investigate d to discover effects of land use and peat degradation on their molecular c hemical composition and thermal proper-ties. The FAs were extracted from th ree Gleysols under arable land, intensive and extensive grassland, and from three Histosols under alder forest, extensive grassland, and a natural suc cession in a long-term (> 200 years) cultivated fen area. Functional groups and molecular subunits of the FAs were investigated by C-13 Nuclear Magnet ic Resonance (C-13 NMR) spectroscopy. Thermal properties and structural mol ecular subunits were investigated by off-line pyrolysis, and Pyrolysis-Fiel d Ionization Mass Spectrometry (Py-FIMS). The C-13 NMR spectra showed that the FAs from topsoil solutions had smaller proportions of alkyl C (mean: -8 %) and more aromatic C (mean: + 6 %) than FAs from ground water. This clea r differentiation of dissolved FAs in the soil profiles is consistent with Py-FIMS data which have shown enrichments of lipids in ground water FAs. Fu rthermore, Py-FIMS revealed that the FAs from topsoils were richer in pheno ls + lignin monomers, carbohydrates, as well as mostly aromatic NI-containi ng compounds. These molecular subunits of FAs, relatively enriched in topso il, were also the main indicators of land use and peat degradation. For top soil solutions, the proportions of phenols + lignin monomers and carbohydra tes increased stepwise with peat degradation in Gleysols and Histosols. Cor respondingly, the thermal properties indicated the incorporation of these c ompounds into FAs by chemical bonds of larger thermal stability. Statistica l evaluation by principal component analysis of Py-FIMS clearly supported t he differentiation of FAs according to the origin from topsoils and ground water, different soil types, and land use and peat degradation. Hence, it i s concluded that water soluble FAs can be utilized as objective ecological indicators for soil effects on adjacent ground and surface waters.