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Soil redistribution and weathering controlling the fate of geochemical and physical carbon stabilization mechanisms in soils of an eroding landscape

(2015) BIOGEOSCIENCES. 12(5). p.1357-1371
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Abstract
The role of eroding landscapes in organic carbon stabilization operating as C sinks or sources has been frequently discussed, but the underlying mechanisms are not fully understood. Our analysis aims to clarify the effects of soil redistribution on physical and biogeochemical soil organic carbon (SOC) stabilization mechanisms along a hillslope transect. The observed mineralogical differences seem partly responsible for the effectiveness of geochemical and physical SOC stabilization mechanisms as the mineral environment along the transect is highly variable and dynamic. The abundance of primary and secondary minerals and the weathering status of the investigated soils differ drastically along this transect. Extractable iron and aluminum components are generally abundant in aggregates, but show no strong correlation to SOC, indicating their importance for aggregate stability but not for SOC retention. We further show that pyrophosphate extractable soil components, especially manganese, play a role in stabilizing SOC within non-aggregated mineral fractions. The abundance of microbial residues and measured C-14 ages for aggregated and non-aggregated SOC fractions demonstrate the importance of the combined effect of geochemical and physical protection to stabilize SOC after burial at the depositional site. Mineral alteration and the breakdown of aggregates limit the protection of C by minerals and within aggregates temporally. The C-14 ages of buried soil indicate that C in aggregated fractions seems to be preserved more efficiently while C in non-aggregated fractions is released, allowing a re-sequestration of younger C with this fraction. Old C-14 ages and at the same time high contents of microbial residues in aggregates suggest either that microorganisms feed on old carbon to build up microbial biomass or that these environments consisting of considerable amounts of old C are proper habitats for microorganisms and preserve their residues. Due to continuous soil weathering and, hence, weakening of protection mechanisms, a potential C sink through soil burial is finally temporally limited.
Keywords
ORGANIC-MATTER, BELGIAN LOESS BELT, AMINO-SUGARS, AGGREGATE STABILITY, TEMPERATE SOILS, CLAY-MINERALS, IRON-OXIDES, EROSION, DEPOSITION, ALUMINUM

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Citation

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Chicago
Doetterl, Sebastian, Jean-Thomas Cornelis, Johan Six, Samuel Bodé, Sophie Opfergelt, Pascal Boeckx, and Kristof Van Oost. 2015. “Soil Redistribution and Weathering Controlling the Fate of Geochemical and Physical Carbon Stabilization Mechanisms in Soils of an Eroding Landscape.” Biogeosciences 12 (5): 1357–1371.
APA
Doetterl, S., Cornelis, J.-T., Six, J., Bodé, S., Opfergelt, S., Boeckx, P., & Van Oost, K. (2015). Soil redistribution and weathering controlling the fate of geochemical and physical carbon stabilization mechanisms in soils of an eroding landscape. BIOGEOSCIENCES, 12(5), 1357–1371.
Vancouver
1.
Doetterl S, Cornelis J-T, Six J, Bodé S, Opfergelt S, Boeckx P, et al. Soil redistribution and weathering controlling the fate of geochemical and physical carbon stabilization mechanisms in soils of an eroding landscape. BIOGEOSCIENCES. 2015;12(5):1357–71.
MLA
Doetterl, Sebastian, Jean-Thomas Cornelis, Johan Six, et al. “Soil Redistribution and Weathering Controlling the Fate of Geochemical and Physical Carbon Stabilization Mechanisms in Soils of an Eroding Landscape.” BIOGEOSCIENCES 12.5 (2015): 1357–1371. Print.
@article{6994257,
  abstract     = {The role of eroding landscapes in organic carbon stabilization operating as C sinks or sources has been frequently discussed, but the underlying mechanisms are not fully understood. Our analysis aims to clarify the effects of soil redistribution on physical and biogeochemical soil organic carbon (SOC) stabilization mechanisms along a hillslope transect. The observed mineralogical differences seem partly responsible for the effectiveness of geochemical and physical SOC stabilization mechanisms as the mineral environment along the transect is highly variable and dynamic. The abundance of primary and secondary minerals and the weathering status of the investigated soils differ drastically along this transect. Extractable iron and aluminum components are generally abundant in aggregates, but show no strong correlation to SOC, indicating their importance for aggregate stability but not for SOC retention. We further show that pyrophosphate extractable soil components, especially manganese, play a role in stabilizing SOC within non-aggregated mineral fractions. The abundance of microbial residues and measured C-14 ages for aggregated and non-aggregated SOC fractions demonstrate the importance of the combined effect of geochemical and physical protection to stabilize SOC after burial at the depositional site. Mineral alteration and the breakdown of aggregates limit the protection of C by minerals and within aggregates temporally. The C-14 ages of buried soil indicate that C in aggregated fractions seems to be preserved more efficiently while C in non-aggregated fractions is released, allowing a re-sequestration of younger C with this fraction. Old C-14 ages and at the same time high contents of microbial residues in aggregates suggest either that microorganisms feed on old carbon to build up microbial biomass or that these environments consisting of considerable amounts of old C are proper habitats for microorganisms and preserve their residues. Due to continuous soil weathering and, hence, weakening of protection mechanisms, a potential C sink through soil burial is finally temporally limited.},
  author       = {Doetterl, Sebastian and Cornelis, Jean-Thomas and Six, Johan and Bod{\'e}, Samuel and Opfergelt, Sophie and Boeckx, Pascal and Van Oost, Kristof},
  issn         = {1726-4170},
  journal      = {BIOGEOSCIENCES},
  keyword      = {ORGANIC-MATTER,BELGIAN LOESS BELT,AMINO-SUGARS,AGGREGATE STABILITY,TEMPERATE SOILS,CLAY-MINERALS,IRON-OXIDES,EROSION,DEPOSITION,ALUMINUM},
  language     = {eng},
  number       = {5},
  pages        = {1357--1371},
  title        = {Soil redistribution and weathering controlling the fate of geochemical and physical carbon stabilization mechanisms in soils of an eroding landscape},
  url          = {http://dx.doi.org/10.5194/bg-12-1357-2015},
  volume       = {12},
  year         = {2015},
}

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