Efficient preservation of old methane-derived organic carbon in deep-sea surface sediments
Methane released from the subseafloor is significantly attenuated during upward migration, yet the preservation of methane-derived organic carbon (OC) in global deep-sea sediments remains poorly understood. Here, we measured carbon isotopes coupled with temperature-ramped analyses on various methane seepage sediments. Our results reveal a correlation between the radiocarbon (14C) content in deep-sea surface sediments and sulfate-methane transition depth. Notably, our findings suggest that a substantial amount of 14C-depleted OC may originate from deep-seated methane and is efficiently preserved in surface seepage sediments. We propose that the efficient OC preservation is related to microbial-mediated aggregate formation at the seawater-sediment interface, where physical occlusion within coarse-grained matrices reduces oxygen availability and enhances OC stability. We estimate that at least 6 Tg C of methane-derived OC are preserved annually in surface sediments of the global continental slopes. This process may play a non-negligible role in OC preservation in sediments, reducing methane emission into the atmosphere. This study finds that ancient methane from deep-sea sediments can be trapped as organic carbon in the seafloor’s top layer, highlighting an overlooked ocean carbon sink, which helps to reduce greenhouse gas release from the seafloor.
Authors
- Zongheng Chen (ORCID: https://orcid.org/0000-0002-9420-9002)
- Luonan Chen (ORCID: https://orcid.org/0000-0002-3960-0068)
- Mutai Bao (ORCID: https://orcid.org/0000-0002-1595-4769)
- Mingzhi Liu (ORCID: https://orcid.org/0000-0001-5842-8307)
- Longhai Zhu (ORCID: https://orcid.org/0000-0001-7245-1335)
- Owen A. Sherwood (ORCID: https://orcid.org/0000-0003-1055-3162)
- David J. Burdige (ORCID: https://orcid.org/0000-0002-8859-7096)
- Rui Bao (ORCID: https://orcid.org/0000-0001-8159-5269)
- Yangli Che (ORCID: https://orcid.org/0000-0001-7795-5487)
- J Chen
- Haoshuai Li (ORCID: https://orcid.org/0000-0001-9536-3266)
- Shengxiong Yang (ORCID: https://orcid.org/0000-0002-6614-0044)
- Weifeng Wu (ORCID: https://orcid.org/0009-0006-0613-110X)
- Min Yu (ORCID: https://orcid.org/0000-0002-4885-8829)
- S Y Li (ORCID: https://orcid.org/0000-0001-8144-6220)
- Naiyu Zhang
- Yang Zhou
- Nan Wang
- Haiyue Ma
- Lihua Dong
Institutions
- Dalhousie University (CA)
- Shanghai Jiao Tong University (CN)
- China Geological Survey (CN)
- Guangzhou Marine Geological Survey (CN)
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (CN)
- Qingdao National Laboratory for Marine Science and Technology (CN)
- Qingdao Institute of Marine Geology (CN)
- Ocean University of China (CN)
- East China Normal University (CN)
- Old Dominion University (US)
Publication Details
- Journal
- Nature Communications
- Published
- 2026-06-17
- DOI
- https://doi.org/10.1038/s41467-026-74250-2
- Primary Topic
- Methane Hydrates and Related Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Natural Science Foundation of China