Saltmarshes are vital coastal ecosystems that store substantial amounts of organic carbon (OC) in sediments. The stability of this OC is crucial for climate mitigation efforts. Black carbon (BC) and microbial necromass carbon (MNC) are key components of OC that significantly contribute to its stability due to their resistance to decomposition. As inert constituents of the soil carbon pool, BC and MNC retard carbon decomposition and release, thereby enhancing the saltmarsh's capacity as a carbon sink. Despite their importance, research on the distribution, interactions, and combined contributions of BC and MNC to the stability of OC in coastal wetland soil profiles remains limited. To address this gap, we conducted a comprehensive assessment in the Yellow River Delta. The study focused on distinct types of coastal ecosystems, including unvegetated tidal flats and three types of salt marshes vegetated by either Spartina alterniflora, Suaeda salsa, or Phragmites australis. We combined field sampling and data analysis to assess the characteristics of BC and MNC in soil profiles across different vegetation types, and explore their contributions to the storage and stability of OC. This research provides insights into the mechanisms by which vegetation types influence the accumulation of inert carbon, thereby enhancing our understanding of OC stability in coastal wetlands.

Saltmarshes,Organic carbon,Black carbon,Coastal wetlands,Microbial Necromass Carbon Contents