Contrasting soil organic carbon sequestration mechanisms in intertidal and supratidal habitats of coastal wetlands divided by seawalls

[Geoengineering News]

https://www.sciencedirect.com/science/article/abs/pii/S0959652625019869

Authors: Jiayuan Liu, Ning Zhang, Xinyu Miao, Zhen Xu, Tianyu Zhang, Ying Wei, Hailong Wu, Fude Liu

https://doi.org/10.1016/j.jclepro.2025.146636

18 September 2025

Highlights

•Contrasting SOC and DOM pools between intertidal and supratidal habitat

•POC and humus-like substances in supratidal habitats show higher levels.

•Protein-like substances tend to increase MAOC content in intertidal habitats.

•Natural attributes shaped by seawalls determine SOC sequestration mechanisms.

Abstract

Soil organic carbon (SOC) sequestration in coastal wetlands is crucial for mitigating global climate change. However, coastal seawall construction alters habitats, potentially affecting the carbon sequestration potential. This study analyzed the content, distribution patterns, and dynamics of SOC and dissolved organic matter (DOM) in two seawall-protected coastal wetlands in the Yellow River Delta, comparing inside (supratidal habitat) and outside (intertidal habitat) habitats. In the study areas, SOC and DOM components showed similar distribution patterns. Dissolved organic carbon, particulate organic carbon (POC), easily oxidized organic carbon (the above three components together accounting for 77.75 ± 0.55 % of total SOC), and humus-like substances (52.81 ± 0.12 % of total DOM) tended to accumulate in supratidal habitats, whereas protein-like substances (59.98 ± 0.24 % of total DOM) and mineral-associated organic carbon (MAOC; 74.18 ± 0.45 % of the total SOC) accumulated in intertidal habitats. SOC stock was higher in intertidal habitats (76.90 ± 2.28 t ha−1) than in supratidal habitats (64.28 ± 3.26 t ha−1). The fitting lines of soil substrates with respect to SOC and its components showed positive and negative effects on SOC sequestration potential in the intertidal and supratidal habitats. Supratidal habitats were characterized by higher levels of both humus-like substances and POC, whereas protein-like substances dominated intertidal habitats, enhancing MAOC retention. Seawalls amplify the divergence in SOC pool compositions and their sequestration mechanisms between intertidal and supratidal wetlands by accelerating seaward inundation and landward isolation. This study emphasizes the importance of the integrated management of intertidal and supratidal habitats in coastal wetlands and adoption of targeted measures to respond to future climate change.

Source: ScienceDirect