Effects of early diagenesis on the isotopic signature of wood (δ13C and δ15N): incubation in aquatic microcosm

Romain Tramoy (1) , Thanh Thuy T Nguyen Tu (2) , Veronique Vaury (3) , Mathieu Sebilo (3) , Laurence Millot-Cornette (4) , Céline Roose-Amsaleg (4) , Johann Schnyder (1)

1 iSTeP - Institut des Sciences de la Terre de Paris
2 CR2P - Centre de recherche sur la Paléobiodiversité et les Paléoenvironnements
3 iEES - Institut d'écologie et des sciences de l'environnement de Paris
4 METIS - Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols

Wood samples (cm-pieces and powders) were incubated in distilled water (DW) and river water (RW) to assess the effects of early diagenesis on carbon and nitrogen dynamics (δ13C and δ15N). Bacterial activity (BiologECO) was twice higher in DW than RW, although mass loss of wood pieces in RW was 3× greater than in DW (30% vs 10%). This difference was attributed to white-rot fungi that colonized the wood pieces in RW, whereas soft-rot fungi developed in DW. These results confirm that fungi are the main agents of degradation in wood, and that white-rot fungi are much more efficient than soft-rot fungi for wood degradation. Despite obvious degradation in both type of water, wood δ13C was not significantly modified. In contrast, N dynamics showed complex and opposite patterns in both types of water, highlighting the strong impact of early diagenesis on the 15N of organic matter (unlike C). But, most of the 15N changes could be attributed to fungi that relocate N between wood and its micro environment in response to N-availability. Altogether, this suggests that early diagenesis may average an environmental signal by integrating the 15N values of individual signals (woods, fungi, water) and microbial processes.

Domaines: Environnement et Société; Climatologie

Romain Tramoy, Thanh Thuy T Nguyen Tu, Veronique Vaury, Mathieu Sebilo, Laurence Millot-Cornette, et al.. Effects of early diagenesis on the isotopic signature of wood (δ13C and δ15N): incubation in aquatic microcosm. Goldschmidt-2017, Aug 2017, Paris, France. 2017. ⟨insu-01624744⟩