Contribution of peatland permafrost to dissolved organic matter along a thaw gradient in North Siberia

L. Gandois (1) , Alison May Hoyt (2, 3) , Christine Hatté (4, 5) , Laurent Jeanneau (6) , Roman Teisserenc (1) , Marine Liotaud (6) , Nikita Tananaev (7)

1 LEFE - Laboratoire Ecologie Fonctionnelle et Environnement
2 MPI-BGC - Max Planck Institute for Biogeochemistry
3 LBNL - Lawrence Berkeley National Laboratory [Berkeley]
4 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
5 GEOTRAC - Géochrononologie Traceurs Archéométrie
6 GR - Géosciences Rennes
7 Melnikov Permafrost Institute

Permafrost peatlands are important carbon stocks currently experiencing rapid evolution after permafrost thaw. Following thaw, dissolved organic matter (DOM) is a potentially important pathway for the release of permafrost carbon. This study investigates the origin and composition of DOM across sites at different stages of thaw in a discontinuous permafrost area of North Siberia. We determine the optical properties, molecular composition, stable (δ13C) and radiocarbon (14C) content of DOM. Early stages of thaw are characterized by high DOC concentrations, high aromaticity, contribution of vegetation-derived DOM, and a high contribution of permafrost carbon. In contrast, in later stages, the microbial contribution to DOM increases, and only modern carbon is detected. This work links DOM composition with its radiocarbon content in permafrost peatlands. It shows that DOM originating from previously frozen permafrost peatland is highly aromatic and previously processed. It highlights the variability of post-thaw carbon dynamics in boreal and arctic ecosystems.

Keywords: GEOF; Panoply

Domains: Geochemistry

L. Gandois, Alison May Hoyt, Christine Hatté, Laurent Jeanneau, Roman Teisserenc, et al.. Contribution of peatland permafrost to dissolved organic matter along a thaw gradient in North Siberia. Environmental Science and Technology, 2019, 53 (24), pp.14165-14174. ⟨10.1021/acs.est.9b03735⟩. ⟨insu-02358892⟩