Divergent changes in particulate and mineral-associated organic carbon upon permafrost thaw

• Published in: Nature communications Vol. 13; no. 1; pp. 5073 - 10
• Main Authors: Liu, Futing, Qin, Shuqi, Fang, Kai, Chen, Leiyi, Peng, Yunfeng, Smith, Pete, Yang, Yuanhe
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29.08.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 631/158/47/4113; 704/47/4113; Carbon; Climate change; Decomposition; Enrichment; Feedback; Global warming; Humanities and Social Sciences; Iron; Microorganisms; multidisciplinary; Organic carbon; Particulate organic carbon; Permafrost; Permafrost thaws; Science; Science (multidisciplinary); Soil dynamics; Soils; Topsoil; Tibetan Plateau
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-32681-7

Permafrost thaw can stimulate microbial decomposition and induce soil carbon (C) loss, potentially triggering a positive C-climate feedback. However, earlier observations have concentrated on bulk soil C dynamics upon permafrost thaw, with limited evidence involving soil C fractions. Here, we explore how the functionally distinct fractions, including particulate and mineral-associated organic C (POC and MAOC) as well as iron-bound organic C (OC-Fe), respond to permafrost thaw using systematic measurements derived from one permafrost thaw sequence and five additional thermokarst-impacted sites on the Tibetan Plateau. We find that topsoil POC content substantially decreases, while MAOC content remains stable and OC-Fe accumulates due to the enriched Fe oxides after permafrost thaw. Moreover, the proportion of MAOC and OC-Fe increases along the thaw sequence and at most of the thermokarst-impacted sites. The relatively enriched stable soil C fractions would alleviate microbial decomposition and weaken its feedback to climate warming over long-term thermokarst development. Based on observations from thermokarst-impacted sites on the Tibetan Plateau, the authors find substantial particulate organic carbon loss but stable mineral-associated organic carbon and enriched iron-bound organic carbon upon permafrost thaw.