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., δ13 CvsPDB ≈ -43‰), differing in their degradability, were incubated on a C4 soil (δ13CvsPDB ≈ -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 18:2ω6,9) was found to be very depleted in 13C (δ13CvsPDB ≈ from -38 to -42‰) compared to all other PLFAs (δ13CvsPDB ≈ 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 δ13C. 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. © Springer-Verlag 2008.
Isotopic evidences for microbiologically mediated and direct C input to soil compounds from three different leaf litters during their decomposition
RUBINO M.;LUBRITTO, Carmine;D'ONOFRIO, Antonio;TERRASI, Filippo;
2009
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., δ13 CvsPDB ≈ -43‰), differing in their degradability, were incubated on a C4 soil (δ13CvsPDB ≈ -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 18:2ω6,9) was found to be very depleted in 13C (δ13CvsPDB ≈ from -38 to -42‰) compared to all other PLFAs (δ13CvsPDB ≈ 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 δ13C. 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. © Springer-Verlag 2008.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
