A novel design for continuous measurement of CO2 from deep remineralization of petrogenic organic carbon

Abstract The oxidation of petrogenic organic carbon contributes a large CO2 flux to the atmosphere, regulating the geological carbon cycle. While few in situ fluxes have been measured in near‐surface sedimentary rocks, deep fracture‐controlled metamorphic terranes remain unexplored. Here, we present...

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Bibliographic Details
Main Authors: Wan‐Yin Lien, Rick Chen, Jui‐Fen Tsai, Jhen‐Nien Chen, Li‐Hung Lin, Pei‐Ling Wang
Format: Article
Language:English
Published: Wiley 2025-05-01
Series:Vadose Zone Journal
Online Access:https://doi.org/10.1002/vzj2.70020
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Summary:Abstract The oxidation of petrogenic organic carbon contributes a large CO2 flux to the atmosphere, regulating the geological carbon cycle. While few in situ fluxes have been measured in near‐surface sedimentary rocks, deep fracture‐controlled metamorphic terranes remain unexplored. Here, we present a novel design for continuous in situ measurements of subsurface CO2 flux feasible for metamorphic rocks. The accumulative CO2 measurements were performed by either the passive mode or active recirculation on an 80‐m deep borehole in eastern Taiwan. Measurements in the passive mode yielded stepwise CO2 releases in the fractured zone and steady accumulation in the pulverized zone at rates (18.9–132 mgC m−2 day−1) resembling those for other active orogens. By contrast, the active recirculation produced an overestimation of CO2 flux. The high flux combined with variation patterns highlights heterogeneous metamorphic terranes as an important CO2 source and the necessities of extended monitoring using the passive mode.
ISSN:1539-1663