[Functional Zoning of Carbon Balance and Carbon Offset in Dongting Lake Basin]

Accounting for carbon revenues and expenditures and determining functional zoning for carbon compensation are crucial for achieving regional low-carbon development and advancing the "dual-carbon" strategy. This study focuses on 200 county units in the Dongting Lake Basin, systematically evaluating the basin's carbon income and expenditure, and proposes strategies for functional zoning of carbon compensation. The findings are as follows： ① Over the past 20 years, carbon emissions in the Dongting Lake Basin have shown an overall upward trend, increasing from 132 million tons in 2000 to 499 million tons in 2020, while carbon absorption has remained relatively stable at around 200 million tons. Spatially, carbon emissions in the Dongting Lake Basin exhibited a distinct "higher in the east, lower in the west" distribution pattern, whereas carbon absorption aligned closely with the terrain's opening towards the north. ② The overall trend of carbon pressure in the Dongting Lake Basin has been increasing, indicating a growing risk of carbon imbalance. The spatial distribution of carbon pressure showed a pattern of "high in the east, low in the west, high in the north, and low in the south." Further comparison between the center of gravity of carbon pressure and the center of gravity of the economy revealed that their spatial locations were very close, yet their trajectories diverged latitudinally, indicating a spatial coupling relationship between carbon pressure and regional economic development, as well as a degree of differentiation. ③ Over the past 20 years, the low-carbon development zones and high-carbon source optimization zones in the Dongting Lake Basin have been shrinking, while the carbon sink functional zones and carbon source control zones have been expanding. This indicates a weakening of the ecological function of carbon sinks in the Dongting Lake Basin. Analysis of the transfer direction revealed that carbon function zoning mainly followed the paths of "low-carbon development zone → carbon sink functional area" and "high-carbon optimization area → carbon source control area," while carbon compensation zoning showed a trend of shifting from compensation areas to payment areas. In the future, a differentiated low-carbon development strategy should be implemented, and a cross-county （district） carbon compensation system should be established to promote synergistic regional ecological and environmental governance and high-quality development.