Work

Constraining Soil Hydrothermal CO2 Degassing Across the Changbaishan Volcanic Area: Insights From 13C‐14C Perspective

Year: 2025

Type: article

Abstract: Soil hydrothermal CO2 represents important forms of diffuse degassing in volcanic areas, but the corresponding CO2 output remains unclear. Herein, we investigated geochemical features of soil gas, that is, soil gas components, carbon isotopic compositions of soil CO2 (δ13C‐CO2 and Δ14C‐CO2), and soil CO2 fluxes in the Changbaishan volcanic area (CHV). The geochemical characteristics of soil gas in diffuse degassing structures differed significantly from those in volcano‐affected structures. Specifically, soil CO2 concentrations were up to 2.5 × 105 ppm, with δ13C‐CO2 values ranging from −6.2‰ to −1.6‰ and Δ14C‐CO2 values spanning from −996‰ to −845‰, showing significant hydrothermal CO2 signatures. The isotopic mixing model was constructed to estimate the contribution of hydrothermal, biogenic, and atmospheric CO2 to soil CO2. The results showed that soil CO2 in diffuse degassing structures was predominantly derived from hydrothermal CO2, while soil CO2 in the volcano‐affected structures was mainly derived from biogenic CO2. Combined with the soil CO2 fluxes, it was concluded that the hydrothermal CO2 output through soil degassing was 5.83 × 104 t yr−1 in CHV, significantly lower than previous estimates. We found that hydrothermal CO2 release in CHV exceeded the CO2 consumption through silicate weathering, thereby acting as the carbon source. We also estimated the hydrothermal soil CO2 output from global volcanoes based on literature‐published values from 80‐degassing volcanoes, which was ∼150 Mt yr−1. Our results highlighted the importance of conducting 13C‐14C investigations in global volcanic areas to replenish the database of hydrothermal CO2 output in different forms and subsequently evaluate their climatic implications.

Source: Geochemistry Geophysics Geosystems

DOI: 10.1029/2024gc011914

Authors: Linan Wang, Jun Zhong, Mao‐Liang Zhang, Guo‐Ming Liu, Si‐Liang Li, Sheng Xu

Institution: Tianjin University

Language: English

Topic: Atmospheric and Environmental Gas Dynamics

Subfield: Global and Planetary Change

Field: Environmental Science

Domain: Physical Sciences

SDG: Climate action

Open Access status: gold

Estimated APC paid: $3,000