In:
Biogeosciences, Copernicus GmbH, Vol. 16, No. 3 ( 2019-02-04), p. 663-680
Abstract:
Abstract. Rapid warming of Arctic ecosystems exposes soil organic matter
(SOM) to accelerated microbial decomposition, potentially leading to
increased emissions of carbon dioxide (CO2) and methane
(CH4) that have a positive feedback on global warming. Current
estimates of the magnitude and form of carbon emissions from Earth system
models include significant uncertainties, partially due to the oversimplified
representation of geochemical constraints on microbial decomposition. Here, we
coupled modeling principles developed in different disciplines, including a
thermodynamically based microbial growth model for methanogenesis and iron
reduction, a pool-based model to represent upstream carbon transformations,
and a humic ion-binding model for dynamic pH simulation to build a more
versatile carbon decomposition model framework that can be applied to soils
under varying redox conditions. This new model framework was parameterized
and validated using synthesized anaerobic incubation data from permafrost-affected
soils along a gradient of fine-scale thermal and hydrological
variabilities across Arctic polygonal tundra. The model accurately simulated
anaerobic CO2 production and its temperature sensitivity using data
on labile carbon pools and fermentation rates as model constraints.
CH4 production is strongly influenced by water content, pH,
methanogen biomass, and presence of competing electron acceptors, resulting
in high variability in its temperature sensitivity. This work provides new
insights into the interactions of SOM pools, temperature increase, soil
geochemical feedbacks, and resulting CO2 and CH4
production. The proposed anaerobic carbon decomposition framework presented
here builds a mechanistic link between soil geochemistry and carbon
mineralization, making it applicable over a wide range of soils under
different environmental settings.
Type of Medium:
Online Resource
ISSN:
1726-4189
DOI:
10.5194/bg-16-663-2019
DOI:
10.5194/bg-16-663-2019-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2019
detail.hit.zdb_id:
2158181-2
Permalink
