LAUSR

Coal mining subsidence wetlands, as important supplementary resources for wetlands, are of great significance for regulating climate change. This study investigated the distribution and influencing factors of carbon in the overlying water and sediment of coal mining subsidence wetlands in Xuzhou, China, during low-water, high-water, and dry seasons. The results revealed significant spatial and temporal variations in the physicochemical properties of the wetlands, with water hypoxia and a trend toward eutrophication due to excess nitrogen and phosphorus. Dissolved organic carbon (WDOC) and dissolved inorganic carbon (WDIC) in water exhibited opposite temporal trends, while sediment organic carbon (SOC) and dissolved organic carbon (SDOC) showed similar temporal and spatial variations. Inorganic carbon in sediment (SIC) and dissolved inorganic carbon (SDIC) showed consistent temporal changes but significant spatial differences. There was a significant positive correlation between WDOC and SDOC, and WDIC was positively correlated with SDOC and SDIC, indicating the interconnection and transformation of dissolved carbon between water and sediment. WDIC was strongly correlated with water temperature and dissolved oxygen, while WDOC was weakly correlated with the physicochemical properties of water. Overall, these findings contribute to our understanding of the carbon distribution and cycling in coal mining subsidence wetlands, which are crucial supplementary resources to natural wetlands for regulating climate change.