Comparative analysis of organic carbon forms and their availability in diverse wetland ecosystems of Nantong, China

Wetlands are vital ecosystems for global carbon cycling and storage, acting as significant carbon reservoirs that surpass many other ecosystems in their capacity to sequester carbon. This study investigates the availability and distribution of various forms of organic carbon across different wetland types in Nantong, China, including coastal, freshwater riverine, saltwater riverine, and inland lake wetlands. Soil samples were collected and analyzed for soil organic carbon (SOC), Dissolved Organic Carbon (DOC), Particulate Organic Carbon (POC), Mineral-Associated Organic Carbon (MAOC), And Easily Oxidizable Organic Carbon (EOC). The results reveal that coastal wetlands exhibit the highest mean SOC (19.8974 mg/g) and DOC (0.2585 mg/g) concentrations, indicating their significant role in carbon sequestration. Meanwhile, freshwater riverine wetlands have the highest mean POC (8.3611 mg/g), highlighting their importance in particulate organic carbon storage. Saltwater riverine wetlands demonstrate significant carbon sequestration potential, with the highest total carbon content (122.53 mg/g). Correlation analysis shows that the levels of ammonia are positively related to SOC, DOC, MAOC, and EOC. This means that the ammonia levels encourage microbes to work harder and break down organic matter faster. Conversely, nitrite levels negatively impact SOC, DOC, and MAOC. These findings underscore the importance of wetland type and environmental conditions in determining carbon storage and turnover. The study provides critical insights for wetland conservation and management strategies aimed at mitigating climate change and preserving biodiversity. PRACTITIONER POINTS: Coastal wetlands show the highest mean SOC and DOC, indicating significant carbon sequestration potential and nutrient availability. Freshwater riverine wetlands have the highest POC levels, highlighting their role in particulate organic matter accumulation. Saltwater riverine wetlands demonstrate substantial total carbon content, showing resilience in saline conditions. Ammonia positively influences SOC, DOC, MAOC, and EOC, enhancing microbial activity and organic matter decomposition. Variability in carbon content across wetland types emphasizes the need for tailored conservation and management strategies.