Salt marshes are pivotal blue carbon ecosystems, demonstrating significantly higher rates of organic carbon (OC) burial than terrestrial forests, thus playing a crucial role in mitigating global warming. Despite their effectiveness, these ecosystems are intrinsically fragile and vulnerable to degradation from various factors. A comprehensive assessment that evaluates both OC loss attributable to erosion or inundation and OC burial could yield a more precise estimation of the carbon sink capacity of salt marsh ecosystems. Previous research has primarily quantified the extent of OC loss without adequately considering the underlying geomorphological processes. In this study, OC loss due to erosion in the salt marshes of Jiangsu, China, was investigated using an integrated approach of field surveys, remote sensing images, and geochemical analyses. The results indicate that soil erosion, induced by collapsing, is the predominant mechanism of OC loss. Additionally, OC loss within sediments is principally influenced by the erosion height and the OC content. Notably, autochthonous OC exhibited a higher susceptibility to decomposition and remineralization than allochthonous OC, leading to increased carbon emissions. Between 2014 and 2021, the annual OC loss in Yancheng, Jiangsu Province, was significant enough to counteract approximately 32% of the OC sequestration recorded during the same timeframe. This study aims to enhance our understanding of OC dynamics in eroded salt marshes and underscore the need for targeted management strategies and conservation measures to preserve the long-term carbon sequestration capacity of these essential ecosystems.

salt marsh,blue carbon,organic carbon loss,erosion