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Isotopic evidences for microbiologically mediated and direct C input to soil compounds from three different leaf litters during their decomposition

Isotopic evidences for microbiologically mediated and direct C input to soil compounds from three different leaf litters during their decomposition Thumbnail


Abstract

We show the potentiality of coupling together different compound-specific isotopic analyses in a laboratory experiment, where 13C-depleted leaf litter was incubated on a 13C-enriched soil. The aim of our study was to identify the soil compounds where the C derived from three different litter species is retained. Three 13C-depleted leaf litter (Liquidambar styraciflua L., Cercis canadensis L. and Pinus taeda L., d13CvsPDB ˜ -43‰), differing in their degradability, were incubated on a C4 soil (d13CvsPDB ˜ -18‰) under laboratory-controlled conditions for 8 months. At harvest, compound-specific isotope analyses were performed on different classes of soil compounds [i.e. phospholipids fatty acids (PLFAs), n-alkanes and soil pyrolysis products]. Linoleic acid (PLFA 18:2?6,9) was found to be very depleted in 13C (d13CvsPDB ˜ from -38 to -42‰) compared to all other PLFAs (d13CvsPDB ˜ from -14 to -35‰). Because of this, fungi were identified as the first among microbes to use the litter as source of C. Among n-alkanes, long-chain (C27–C31) n-alkanes were the only to have a depleted d13C. This is an indication that not all of the C derived from litter in the soil was transformed by microbes. The depletion in 13C was also found in different classes of pyrolysis products, suggesting that the litter-derived C is incorporated in less or more chemically stable compounds, even only after 8 months decomposition.

Acceptance Date Jan 24, 2008
Publication Date Feb 15, 2008
Publicly Available Date Mar 29, 2024
Journal ENVIRONMENTAL CHEMISTRY LETTERS
Print ISSN 1610-3653
Publisher Springer Verlag
Pages 85 - 95
DOI https://doi.org/10.1007/s10311-008-0141-6
Keywords litter decomposition; n-alkanes; PLFA; Pyrolysis-GC/MS-C-IRMS; SOM
Publisher URL https://link.springer.com/article/10.1007%2Fs10311-008-0141-6#copyrightInformation

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