Redox and temperature-sensitive changes in microbial communities and soil chemistry dictate greenhouse gas loss from thawed permafrost

Ernakovich, Jessica G.; Lynch, Laurel; Brewer, Paul E.; Calderón, Francisco J.; Wallenstein, Matthew D.

doi:10.1007/s10533-017-0354-5

Cited by 28 publications

(26 citation statements)

References 92 publications

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“…However, the distribution of metabolite diversity ran contrary to our prediction, with higher molecular diversity observed in riparian than hillslope landscape positions. The assimilation of carbohydrates and other labile plant-derived compounds into microbial biomass (Ernakovich et al, 2017;Lynch et al, 2018) could explain the reduced DOM heterogeneity (Liang et al, 2017) we observed in hillslope soils, which are colonized by productive dwarf shrub and tussock-forming sedge communities (Walker & Walker, 1996, Figure 5). The assimilation of carbohydrates and other labile plant-derived compounds into microbial biomass (Ernakovich et al, 2017;Lynch et al, 2018) could explain the reduced DOM heterogeneity (Liang et al, 2017) we observed in hillslope soils, which are colonized by productive dwarf shrub and tussock-forming sedge communities (Walker & Walker, 1996, Figure 5).…”

Section: Discussionmentioning

confidence: 95%

“…While the structural chemistry in hillslope soils was relatively homogenous, NMR region III and EEMS regions III and V-indicative of plant-derived structures (Chen et al, 2003;Simpson et al, 2003)-were elevated in organic soil horizons. The assimilation of carbohydrates and other labile plant-derived compounds into microbial biomass (Ernakovich et al, 2017;Lynch et al, 2018) could explain the reduced DOM heterogeneity (Liang et al, 2017) we observed in hillslope soils, which are colonized by productive dwarf shrub and tussock-forming sedge communities (Walker & Walker, 1996, Figure 5). Recent evidence suggests widespread shrub expansion (Sturm et al, 2001) will shift rooting distributions (Iversen et al, 2015) and deposition of labile root exudates (Zhu et al, 2016) upward into surface organic horizons that are less vulnerable to priming than energy depleted mineral soils (Fontaine et al, 2007;Wild et al, 2014).…”

Section: 1029/2018gb006030mentioning

confidence: 95%

“…Of particular interest is the fate of natural dissolved organic matter (DOM), which comprises the dominant and most mobile form of organic C in soil pore waters (Jansen et al, 2014;Kalbitz et al, 2003). The vast chemical diversity of DOM shapes microbial metabolism (Ernakovich et al, 2017;Mu et al, 2017), links terrestrial and aquatic environments (Battin, Luyssaert, et al, 2009;Kellerman et al, 2014), and influences landscape C balances (Mu et al, 2017). Understanding the chemical composition and mobilization potential of DOM is thus essential in determining the proportion of newly thawed soil C that is converted and released to the atmosphere as carbon dioxide (CO 2 ), incorporated into microbial biomass, or stabilized in the soil mineral matrix (Lynch et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Widespread permafrost thaw in high-latitude regions (Koven et al, 2009;Osterkamp & Romanovsky, 1999) could increase CO 2 release from soils to the atmosphere (Ernakovich et al, 2017;Natali et al, 2015;Schuur et al, 2009) and transform the hydrology of Arctic landscapes (Frey & McClelland, 2009;Rowland et al, 2010;White et al, 2007). While permafrost boundaries currently limit subsurface storage and control the routing of water, carbon (C), nutrients, and sediment across Arctic landscapes (Rowland et al, 2010), permafrost loss is projected to increase soil drainage and the connectivity of surface and subsurface flow paths (Walvoord & Kurylyk, 2016), with implications for catchment biogeochemistry (Harms & Jones, 2012;Vonk et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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Dissolved Organic Matter Chemistry and Transport Along an Arctic Tundra Hillslope

Lynch

Machmuller

Boot

et al. 2019

Global Biogeochemical Cycles

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Permafrost thaw is projected to restructure the connectivity of surface and subsurface flow paths, influencing export dynamics of dissolved organic matter (DOM) through Arctic watersheds. Resulting shifts in flow path exchange between both soil horizons (organic‐mineral) and landscape positions (hillslope‐riparian) could alter DOM mobility and molecular‐level patterns in chemical composition. Using conservative tracers, we found relatively rapid lateral flows occurred across a headwater Arctic tundra hillslope, as well as along the mineral‐permafrost interface. While pore waters collected from the organic horizon were associated with plant‐derived molecules, those collected from permafrost‐influenced mineral horizons had a microbial origin, as determined by fluorescence spectroscopy. Using high‐resolution nuclear magnetic resonance spectroscopy, we found that riparian DOM had greater structural diversity than hillslope DOM, suggesting riparian soils could supply a diverse array of compounds to surface waters if terrestrial‐aquatic connectivity increases with warming. In combination, these results suggest that integrating DOM mobilization with its chemical and spatial heterogeneity can help predict how permafrost loss will structure ecosystem metabolism and carbon‐climate feedbacks in Arctic catchments with similar topographic features.

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Section: Discussionmentioning

confidence: 95%

Section: 1029/2018gb006030mentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dissolved Organic Matter Chemistry and Transport Along an Arctic Tundra Hillslope

Lynch

Machmuller

Boot

et al. 2019

Global Biogeochemical Cycles

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“…The large biomolecules in the DOC pool went through multiple hydrolysis and fermentation steps to produce lowmolecular-weight organic acids that would further respire into CO 2 and CH 4 (Boye et al, 2017;Zheng and Graham, 2018;Yang et al, 2016;Roy Chowdhury et al, 2015). Under anoxic conditions, hydrolysis of polysaccharides was considered the rate-limiting step for downstream methanogenesis (Glissmann and Conrad, 2002). Polysaccharide hydrolysis has a favorable free energy, due to increased entropy, but cannot be readily coupled to biological energy transduction outside of the cell.…”

Section: Anaerobic Carbon Decomposition Modelmentioning

confidence: 99%

Modeling anaerobic soil organic carbon decomposition in Arctic polygon tundra: insights into soil geochemical influences on carbon mineralization

et al. 2019

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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.

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Thermokarst processes increase the supply of stabilizing surfaces and elements (Fe, Mn, Al, and Ca) for mineral–organic carbon interactions

Monhonval

Strauß

Thomas

et al. 2022

Permafrost & Periglacial

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The stabilizing properties of mineral-organic carbon (OC) interactions have been studied in many soil environments (temperate soils, podzol lateritic soils, and paddy soils). Recently, interest in their role in permafrost regions is increasing as permafrost was identified as a hotspot of change. In thawing ice-rich permafrost regions, such as the Yedoma domain, 327-466 Gt of frozen OC is buried in deep sediments. Interactions between minerals and OC are important because OC is located very near the mineral matrix. Mineral surfaces and elements could mitigate recent and future greenhouse gas emissions through physical and/or physicochemical protection of OC. The dynamic changes in redox and pH conditions associated with thermokarst lake formation and drainage trigger metal-oxide dissolution and precipitation, likely influencing OC stabilization and microbial mineralization. However, the influence of thermokarst processes on mineral-OC interactions remains poorly constrained. In this study, we aim to characterize Fe, Mn, Al, and Ca minerals and their potential protective role for OC. Total and selective extractions were used to assess the crystalline and amorphous oxides or complexed metal pools as well as the organic acids found within these pools. We analyzed four sediment cores from an ice-rich permafrost area in Central Yakutia, which were drilled (i) in undisturbed Yedoma uplands, (ii) beneath a recent lake formed within Yedoma deposits, (iii) in a drained thermokarst lake basin, and (iv) beneath a mature thermokarst lake from the early Holocene period. We find a decrease in the amount of reactive Fe, Mn, Al, and Ca in the deposits on lake formation (promoting reduction reactions), and this was largely balanced by an increase in the amount of reactive metals in the deposits on lake drainage (promoting oxidation reactions). We demonstrate an increase in the metal to C molar ratio on thermokarst process, which may indicate an increase in metal-C bindings and could provide a higher protective role against microbial mineralization of organic matter. Finally, we find that an increase in mineral-OC interactions corresponded to a decrease in CO 2 and CH 4 gas emissions on thermokarst process.

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Redox and temperature-sensitive changes in microbial communities and soil chemistry dictate greenhouse gas loss from thawed permafrost

Cited by 28 publications

References 92 publications

Dissolved Organic Matter Chemistry and Transport Along an Arctic Tundra Hillslope

Dissolved Organic Matter Chemistry and Transport Along an Arctic Tundra Hillslope

Modeling anaerobic soil organic carbon decomposition in Arctic polygon tundra: insights into soil geochemical influences on carbon mineralization

Thermokarst processes increase the supply of stabilizing surfaces and elements (Fe, Mn, Al, and Ca) for mineral–organic carbon interactions

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