biostudies-literatureZhang JGuangdong Basic and Applied Basic Research FoundationNational Natural Science Foundation of ChinaNational Natural Science Foundation of China (National Science Foundation of China)8994https://www.ebi.ac.uk/biostudies/studies/S-EPMC11489663biostudies-literatureUnknown15(1)Mangroves can retain both autochthonous and allochthonous marine and/or terrestrial organic carbon (OC) in sediments. Accurate quantification of these OC sources is essential for the proper allocation of blue C credits. Here, we conduct a global-scale analysis of sediments autochthonous and allochthonous OC contributions in estuarine and marine mangroves using stable isotopes. Globally, mangrove-derived autochthonous OC was the main contributor to estuarine and marine mangrove top-meter soil organic carbon (SOC) (49% and 62%, respectively). Less marine allochthonous OC (21%) was deposited than terrestrial allochthonous OC (30%) in estuarine mangrove sediments. Estuarine mangroves accumulated more SOC in sediments than marine mangroves (282 ± 8.1 Mg C ha^-1 and 250 ± 5.0 Mg C ha<sNature communicationsA global assessment of mangrove soil organic carbon sources and implications for blue carbon credit.PMC1148966342471067，U2106209Gan SSaintilan NZhang JHuang XHe HSanders CJYang PWang FChen HZhou JfalseA global assessment of mangrove soil organic carbon sources and implications for blue carbon credit.Mangroves can retain both autochthonous and allochthonous marine and/or terrestrial organic carbon (OC) in sediments. Accurate quantification of these OC sources is essential for the proper allocation of blue C credits. Here, we conduct a global-scale analysis of sediments autochthonous and allochthonous OC contributions in estuarine and marine mangroves using stable isotopes. Globally, mangrove-derived autochthonous OC was the main contributor to estuarine and marine mangrove top-meter soil organic carbon (SOC) (49% and 62%, respectively). Less marine allochthonous OC (21%) was deposited than terrestrial allochthonous OC (30%) in estuarine mangrove sediments. Estuarine mangroves accumulated more SOC in sediments than marine mangroves (282 ± 8.1 Mg C ha^-1 and 250 ± 5.0 Mg C ha<s2024-01-01T00:00:00Z2024 Oct2025-04-04T19:46:06.436Z2025-04-04T19:46:06.436ZS-EPMC114896633942481310.1038/s41467-024-53413-z