Carbon dioxide (CO 2 ) stands as the primary driver of Earth's greenhouse effect, and it's suggested that the global contribution of CO 2 emissions from lakes cannot be ignored. Despite the numerous estimations of CO 2 fluxes from lakes, limited focus has been directed towards the carbon isotopes (δ 13 C) of dissolved CO 2 in lake water. Particularly, the potential use of δ 13 C values in tracing the CO 2 concentrations in lake water remains as an understudied area, warranting further exploration and investigation. In this study, we conducted an analysis of the concentrations and δ 13 C values of dissolved CO 2 in 33 lakes located at the Tibetan Plateau, Chinese Loess Plateau, and Yangtze Plain (among which high-resolution spatial investigations were performed in 6 lakes through in-situ continuous monitoring). Our findings revealed spatial variations in both the CO 2 concentrations and δ 13 C values in lakes. Additionally, notable differences are observed among lakes in different regions of China, with lakes in the Yangtze Plain exhibiting considerably higher CO 2 concentrations, and the overall CO 2 δ 13 C values in lakes on the Tibetan Plateau tend to be more positive, while those in lakes on the Chinese Loess Plateau tend to be more negative. The pH values, dissolved oxygen, and dissolved organic carbon are likely crucial factors influencing the CO 2 concentrations and δ 13 C values in the lakes. Furthermore, lake water CO 2 concentrations are negatively correlated with δ 13 C values of CO 2 and dissolved inorganic carbon (DIC) both within a single lake with high spatial resolutions or in lake groups across different regions. These results highlight that the CO 2 /DIC δ 13 C values can be applied to trace the concentration variations of dissolved CO 2 in lakes.