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| Titel |
Methane processing in arctic shelves and the role of anaerobic methane oxidation |
| VerfasserIn |
Iana Tsandev, Pierre Regnier, Andrew Dale, Andy Ridgwell |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053457
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| Zusammenfassung |
| Fluxes of methane to the ocean and atmosphere from sea floor gas hydrates are a key forcing
of Earth’s climate. It is believed that massive hydrate dissolution events have contributed to
pronounced global warming and environmental crises of past climate and may do the same in
the future. If this released sedimentary methane is oxidized aerobically, it results in loss
of seawater dissolved inorganic carbon (DIC) and alkalinity (ALK) and CaCO3
dissolution. The effect can be opposite if anaerobic oxidation of methane takes place. It
is therefore worth examining whether anaerobic oxidation of methane released
by the thermal dissociation of gas hydrates can alleviate or exacerbate the future
global warming due to the anthropogenic CO2 emissions. In this study we model
global ocean water column dynamics with an Earth system model of intermediate
complexity – GENIE – and present steady state fields of the relevant variables (organic
matter flux to the sediment water interface (SWI), bottom water oxygen content,
DIC and ALK content of the water column, etc). The modern pre-anthropogenic
ocean is modeled with a 16 slab ocean configuration and 10o x 10o resolution. We
couple the Earth system model GENIE to a 1-D biogeochemical reaction network
simulator (BRNS) of sedimentary dynamics – which includes all relevant early
diagenetic processes of the coupled cycles of C, O, N, S and Fe as well as all relevant
advective diffusive and non-local transport processes. We identify high latitude shelf
environments known for high methane hydrate concentrations and apply the GENIE
values at these sites as boundary conditions to the BRNS sedimentary model. We
further impose bottom advective fluxes of methane on the sediment column based on
hydrate dissolution estimates and quantify the pathways of methane transformation –
aerobic vs. anaerobic. We then compute benthic fluxes of DIC and alkalinity and
study the response of the benthic anoxic diagenesis cycle (AOM, methanogenesis)
subjected to the proposed forcings and its feedback onto the inorganic carbon cycle. |
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