How erosion of salt marsh edges leads to the loss of organic carbon: Insights from Jiangsu coast, China

Abstract

Salt marshes are important blue carbon ecosystems, demonstrating significantly higher rates of organic carbon (OC) burial than terrestrial forests, thus playing a crucial role in mitigating global warming. However, these ecosystems are inherently fragile and vulnerable to degradation due to a variety of environmental stressors. An accurate assessment of the carbon sink capacity of salt marshes requires a comprehensive evaluation of OC burial and OC loss. Previous studies have often focused on quantifying OC loss roughly at large scale, while there has been less discussion about adequately addressing the geomorphological processes that drive such losses at finer regional scale. In this study, we investigate OC loss due to edge erosion in the salt marshes of Jiangsu, China, utilizing an integrated approach involving field surveys, remote sensing, and geochemical analyses. The results indicate that soil erosion is the predominant mechanism of OC loss. Furthermore, OC loss within sediments is principally determined by the erosion height and the OC content. The study also finds that autochthonous OC is more susceptible to decomposition and remineralization than allochthonous OC. From 2014 to 2021, the annual OC loss in Yancheng, Jiangsu Province, offset approximately 32 % of the OC sequestration. These findings aim to enhance understanding of OC dynamics in eroded salt marshes and emphasize the necessity for targeted management strategies to maintain the long-term carbon sequestration potential of these critical ecosystems.