Constraining soil hydrothermal CO2 degassing across the Changbaishan volcanic area: insights from 13C-14C perspective

Volcanic degassing releases large amounts of hydrothermal CO2, which influences long-term global climate. Soil hydrothermal CO2 is an important form of volcanic degassing, making the corresponding output crucial for understanding the solid Earth degassing and climate change. We investigated the soil gases from the Changbaishan volcanic area, the most active volcano in China, focusing on their gas compositions and carbon isotopic compositions, and soil CO2 fluxes. Our results showed that the soil gases from diffuse degassing structures had higher CO2 concentrations and isotopic compositions closer to hydrothermal CO2 compared to gases from volcano-affected structures. We developed an isotopic mixing model to determine the fractions of atmospheric CO2, biogenic CO2, and hydrothermal CO2 in soil gases, providing a more accurate constraint of carbon sources. Our findings revealed that hydrothermal CO2 was the primary carbon source for soil CO2 in diffuse degassing structures, whereas biogen..., We collected 31 soil gas samples following CO2 flux measurements in October 2023 in the Changbaishan volcanic area. Gas chromatography-quadrupole time-of-flight mass spectrometry (GC/Q-TOF) was used to measure gas components. The ratio of 13C/12C was analyzed by GC combined with isotope ratio mass spectrometer (IRMS). The ratio of 14C/12C was analyzed by a 0.5 MV accelerator mass spectrometer (AMS). The soil CO2 fluxes was measured  by accumulation chamber method in 85 sites in the Changbaishan volcanic area. , , # Data from: Constraining Soil Hydrothermal CO2 Degassing across the Changbaishan Volcanic Area: Insights from 13C-14C Perspective

[https://doi.org/10.5061/dryad.15dv41p5r](https://doi.org/10.5061/dryad.15dv41p5r)

## Description of the data and file structure

This data set is about the soil CO2 fluxes and soil gas components, carbon isotopic compositions of soil CO2 in the Changbaishan volcanic area. Gas chromatography-quadrupole time-of-flight mass spectrometry (GC/Q-TOF) was used to measure gas components. The ratio of C/C was analyzed by GC combined with isotope ratio mass spectrometer (IRMS). The ratio of C/C was analyzed by a 0.5 MV accelerator mass spectrometer.

Table 1 is Soil CO2 fluxes in the Changbaishan volcanic area.

Table 2 is Component and carbon isotopic compositions of soil gas.

Table 3 is Hydrothermal CO2 output in soil degassing.

Table S1 is Characteristic values of different carbon sources in soil CO2.

Table S2 is Fractional contributions of different carbon s...