FN Archimer Export Format
PT J
TI Probing the exchange of CO2 and O2 in the shallow critical zone during weathering of marl and black shale
BT 
AF Roylands, Tobias
   Hilton, Robert G.
   McClymont, Erin L.
   Garnett, Mark H.
   Soulet, Guillaume
   Klotz, Sébastien
   Degler, Mathis
   Napoleoni, Felipe
   Le Bouteiller, Caroline
AS 1:1;2:2;3:1;4:3;5:4;6:5;7:6;8:7;9:5;
FF 1:;2:;3:;4:;5:PDG-REM-GEOOCEAN-ASTRE;6:;7:;8:;9:;
C1 Department of Geography, Durham University, Durham, DH1 3LE, United Kingdom
   Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, United Kingdom
   NEIF Radiocarbon Laboratory, SUERC, East Kilbride, G75 0QF, United Kingdom
   Ifremer, Geo-Ocean, Brest University, CNRS, 29280 Plouzané, France
   INRAE, Univ. Grenoble Alpes, CNRS, 38000 Grenoble, France
   Institute of Geosciences, Christian Albrecht University, 24118 Kiel, Germany
   Centro de Estudios Científicos, Valdivia, 5110466, Chile
C2 UNIV DURHAM, UK
   UNIV OXFORD, UK
   SUERC, UK
   IFREMER, FRANCE
   INRAE, FRANCE
   UNIV KIEL, GERMANY
   CECS, CHILE
SI BREST
SE PDG-REM-GEOOCEAN-ASTRE
UM GEO-OCEAN
IN DOAJ
TC 0
UR https://archimer.ifremer.fr/doc/00877/98916/108652.pdf
   https://archimer.ifremer.fr/doc/00877/98916/108653.zip
   https://archimer.ifremer.fr/doc/00877/98916/108654.pdf
   https://archimer.ifremer.fr/doc/00877/98916/108655.zip
LA English
DT Article
AB Chemical weathering of sedimentary rocks can release carbon dioxide (CO2) and consume oxygen (O2) via the oxidation of petrogenic organic carbon and sulfide minerals. These pathways govern Earth's surface system and climate over geological timescales, but the present-day weathering fluxes and their environmental controls are only partly constrained due to a lack of in situ measurements. Here, we investigate the gaseous exchange of CO2 and O2 during the oxidative weathering of black shales and marls exposed in the French southern Alps. On six field trips over 1 year, we use drilled headspace chambers to measure the CO2 concentrations in the shallow critical zone and quantify CO2 fluxes in real time. Importantly, we develop a new approach to estimate the volume of rock that contributes CO2 to a chamber, and assess effective diffusive gas exchange, by first quantifying the mass of CO2 that is stored in a chamber and connected rock pores. Both rock types are characterized by similar contributing rock volumes and diffusive movement of CO2. However, CO2 emissions differed between the rock types, with yields over rock outcrop surfaces (inferred from the contributing rock volume and the local weathering depths) ranging on average between 73 and 1108 tCkm-2yr-1 for black shales and between 43 and 873 tCkm-2yr-1 for marls over the study period. Having quantified diffusive processes, chamber-based O2 concentration measurements are used to calculate O2 fluxes. The rate of O2 consumption increased with production of CO2, and with increased temperature, with an average O2:CO2 molar ratio of 10:1. If O2 consumption occurs by both rock organic carbon oxidation and carbonate dissolution coupled to sulfide oxidation, either an additional O2 sink needs to be identified or significant export of dissolved inorganic carbon occurs from the weathering zone. Together, our findings refine the tools we have to probe CO2 and O2 exchange in rocks at Earth's surface and shed new light on CO2 and O2 fluxes, their drivers, and the fate of rock-derived carbon. 
PY 2024
PD JAN
SO Earth Surface Dynamics
SN 2196-632X
PU Copernicus GmbH
VL 12
IS 1
BP 271
EP 299
DI 10.5194/esurf-12-271-2024
ID 98916
ER

EF