<p>The interaction between acidic mine drainage (AMD) in karst areas and carbonates or groundwater before it enters the surrounding streams is often overlooked, thus posing a risk of underestimating the carbon sink flow. The evolution of dissolved inorganic carbon (DIC) and the CO₂ degassing process was investigated by analyzing the hydrostoichiometric properties of AMD in conjunction with groundwater and stream dynamics in a typical karst basin of Dashu. Hydrochemical and isotopic analyses reveal that carbonate weathering and dissolution predominantly contribute to the DIC levels, resulting in δ¹³CDIC &lt; 10.0 ‰, and rich in lighter isotopes. However, AMD and affected groundwater or surface water primarily undergo HCO₃⁻ neutral degassing and proton-enhanced degassing, and the surface water degassing caused by AMD only accounts for 12.83% of the total dissolved inorganic carbon in the water. AMD facilitates the continuous release of carbon stored within carbonate rock formations, converting it into CO₂. Although this process serves to neutralize acidity and diminishes the release of CO₂ from streams into the atmosphere, the degasification resulting from AMD directly interacting with carbonate or groundwater was ≈ 500 times greater than that of surface water. This study assessed the effect of carbon sinks considering the interaction between AMD and groundwater or carbonate minerals before they enter the stream and the effect of entering the stream, providing an example for accurately assessing the effect of AMD on carbon emissions. Considering the widespread distribution of AMD in karst regions globally, the effect of this substantial potential source of CO₂ should not be overlooked. Therefore, precise and detailed quantitative analysis based on empirical observation is important for accurately assessing the effect of AMD on regional and even global carbon sinks.</p>