Data from: 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 biogenic CO2
predominated in volcano-affected structures. We integrated the reported
data to calculate the local carbon budget for the Changbaishan volcanic
area, demonstrating that the study area acts as a carbon source.
Additionally, we collected soil hydrothermal CO2 data from 80-degassing
volcanoes and estimated the soil hydrothermal CO2 output from global
volcanic areas to be approximately 150 Mt yr−1. Our study highlighted the
effectiveness of using δ13C-CO2 and Δ14C-CO2 to identify hydrothermal CO2
and emphasized the importance of accurately estimating soil hydrothermal
CO2 emissions.