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| Titel |
Incorporating redox processes improves prediction of carbon and nutrient cycling and greenhouse gas emission |
| VerfasserIn |
Guoping Tang, Jianqiu Zheng, Ziming Yang, David Graham, Baohua Gu, Melanie Mayes, Scott Painter, Peter Thornton |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250127577
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| Publikation (Nr.) |
 EGU/EGU2016-7469.pdf |
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| Zusammenfassung |
| Among the coupled thermal, hydrological, geochemical, and biological processes, redox
processes play major roles in carbon and nutrient cycling and greenhouse gas (GHG)
emission. Increasingly, mechanistic representation of redox processes is acknowledged as
necessary for accurate prediction of GHG emission in the assessment of land-atmosphere
interactions. Simple organic substrates, Fe reduction, microbial reactions, and the
Windermere Humic Aqueous Model (WHAM) were added to a reaction network used in the
land component of an Earth system model. In conjunction with this amended reaction
network, various temperature response functions used in ecosystem models were assessed for
their ability to describe experimental observations from incubation tests with arctic soils.
Incorporation of Fe reduction reactions improves the prediction of the lag time between CO2
and CH4 accumulation. The inclusion of the WHAM model enables us to approximately
simulate the initial pH drop due to organic acid accumulation and then a pH increase due to
Fe reduction without parameter adjustment. The CLM4.0, CENTURY, and Ratkowsky
temperature response functions better described the observations than the Q10 method,
Arrhenius equation, and ROTH-C. As electron acceptors between O2 and CO2 (e.g., Fe(III),
SO42−) are often involved, our results support inclusion of these redox reactions for
accurate prediction of CH4 production and consumption. Ongoing work includes
improving the parameterization of organic matter decomposition to produce simple
organic substrates, examining the influence of redox potential on methanogenesis
under thermodynamically favorable conditions, and refining temperature response
representation near the freezing point by additional model-experiment iterations. We
will use the model to describe observed GHG emission at arctic and tropical sites. |
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