scholarly journals Thermokarst lake methanogenesis along a complete talik profile

2015 ◽  
Vol 12 (14) ◽  
pp. 4317-4331 ◽  
Author(s):  
J. K. Heslop ◽  
K. M. Walter Anthony ◽  
A. Sepulveda-Jauregui ◽  
K. Martinez-Cruz ◽  
A. Bondurant ◽  
...  
Keyword(s):  
Lake Sediments ◽  
Relative Magnitude ◽  
Thermokarst Lake ◽  
Ch4 Production ◽  
Lake Sediment Core ◽  
Permafrost Soils ◽  
Thawing Permafrost ◽  
Top 40 ◽  
Lake Systems

Abstract. Thermokarst (thaw) lakes emit methane (CH4) to the atmosphere formed from thawed permafrost organic matter (OM), but the relative magnitude of CH4 production in surface lake sediments vs. deeper thawed permafrost horizons is not well understood. We assessed anaerobic CH4 production potentials from various depths along a 590 cm long lake sediment core that captured the entire sediment package of the talik (thaw bulb) beneath the center of an interior Alaska thermokarst lake, Vault Lake, and the top 40 cm of thawing permafrost beneath the talik. We also studied the adjacent Vault Creek permafrost tunnel that extends through ice-rich yedoma permafrost soils surrounding the lake and into underlying gravel. Our results showed CH4 production potentials were highest in the organic-rich surface lake sediments, which were 151 cm thick (mean ± SD: 5.95 ± 1.67 μg C–CH4 g dw−1 d−1; 125.9 ± 36.2 μg C–CH4 g C−1org d−1). High CH4 production potentials were also observed in recently thawed permafrost (1.18 ± 0.61 μg C–CH4g dw−1 d−1; 59.60± 51.5 μg C–CH4 g C−1org d−1) at the bottom of the talik, but the narrow thicknesses (43 cm) of this horizon limited its overall contribution to total sediment column CH4 production in the core. Lower rates of CH4 production were observed in sediment horizons representing permafrost that has been thawing in the talik for a longer period of time. No CH4 production was observed in samples obtained from the permafrost tunnel, a non-lake environment. Our findings imply that CH4 production is highly variable in thermokarst lake systems and that both modern OM supplied to surface sediments and ancient OM supplied to both surface and deep lake sediments by in situ thaw and shore erosion of yedoma permafrost are important to lake CH4 production.

scholarly journals Thermokarst-lake methanogenesis along a complete talik profile

2015 ◽  
Vol 12 (6) ◽  
pp. 4865-4905 ◽  
Author(s):  
J. K. Heslop ◽  
K. M. Walter Anthony ◽  
A. Sepulveda-Jauregui ◽  
K. Martinez-Cruz ◽  
A. Bondurant ◽  
...  
Keyword(s):  
Lake Sediments ◽  
Relative Magnitude ◽  
Thermokarst Lake ◽  
Ch4 Production ◽  
Lake Sediment Core ◽  
Permafrost Soils ◽  
Thawing Permafrost ◽  
Top 40 ◽  
Lake Systems

Abstract. Thermokarst (thaw) lakes emit methane (CH4) to the atmosphere formed from thawed permafrost organic matter (OM), but the relative magnitude of CH4 production in surface lake sediments vs. deeper thawed permafrost horizons is not well understood. We assessed anaerobic CH4 production potentials from various depths along a 590 cm long lake sediment core that captured the entire sediment package of the talik (thaw bulb) beneath the center of an interior Alaska thermokarst lake, Vault Lake, and the top 40 cm of thawing permafrost beneath the talik. We also studied the adjacent Vault Creek permafrost tunnel that extends through ice-rich yedoma permafrost soils surrounding the lake and into underlying gravel. Our results showed CH4 production potentials were highest in the organic-rich surface lake sediments, which were 151 cm thick (mean ± SD 5.95 ± 1.67 μg C-CH4 g dw−1 d−1; 125.9± 36.2 μg C-CH4 g C−1org d−1). High CH4 production potentials were also observed in recently-thawed permafrost (1.18± 0.61 μg C-CH4g dw−1 d−1; 59.60± 51.5 μg C-CH4 g C−1org d−1) at the bottom of the talik, but the narrow thicknesses (43 cm) of this horizon limited its overall contribution to total sediment column CH4 production in the core. Lower rates of CH4 production were observed in sediment horizons representing permafrost that has been thawed in the talik for longer periods of time. No CH4 production was observed in samples obtained from the permafrost tunnel, a non-lake environment. Our findings imply that CH4 production is highly variable in thermokarst-lake systems and that both modern OM supplied to surface sediments and ancient OM supplied to both surface and deep lake sediments by in situ thaw as well as shore erosion of yedoma permafrost are important to lake CH4 production.

scholarly journals Organic carbon characteristics in yedoma and thermokarst deposits on Baldwin Peninsula, West-Alaska

2018 ◽  
Author(s):  
Loeka L. Jongejans ◽  
Jens Strauss ◽  
Josefine Lenz ◽  
Francien Peterse ◽  
Kai Mangelsdorf ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Lake Sediments ◽  
Lake Basin ◽  
Study Region ◽  
Thermokarst Lake ◽  
Discontinuous Permafrost ◽  
Lipid Biomarker ◽  
Biomarker Analysis ◽  
Thawing Permafrost

Abstract. As Arctic warming continues and permafrost thaws, more soil and sedimentary organic carbon (OC) will be decomposed in northern high latitudes. Still, uncertainties remain in the quantity and quality of OC stored in different deposit types of permafrost landscapes. This study presents OC data from deep permafrost and lake deposits on the Baldwin Peninsula which is located in the southern portion of the continuous permafrost zone in West Alaska. Sediment samples from yedoma and drained thermokarst lake basin (DTLB) deposits as well as thermokarst lake sediments were analyzed for cryostratigraphical and biogeochemical parameters and their lipid biomarker composition to identify the size and quality of belowground OC pools in ice-rich permafrost on Baldwin Peninsula. We provide the first detailed characterization of yedoma deposits on Baldwin Peninsula. We show that three quarters of soil organic carbon in the frozen deposits of the study region (total of 68 Mt) is stored in DTLB deposits (52 Mt) and one quarter in the frozen yedoma deposits (16 Mt). The lake sediments contain a relatively small OC pool (4 Mt), but have the highest volumetric OC content (93 kg/m3) compared to the DTLB (35 kg/m3) and yedoma deposits (8 kg/m3), largely due to differences in the ground ice content. The biomarker analysis indicates that the OC in both yedoma and DTLB deposits is mainly of terrestrial origin. Nevertheless, the relatively high carbon preference index of plant leaf waxes in combination with a lack of degradation trend with depth in the yedoma deposits indicates that OC stored in yedoma is less degraded than that stored in DTLB deposits. This suggests that OC in yedoma has a higher potential for decomposition upon thaw, despite the relatively small size of this pool. These findings highlight the importance of molecular OC analysis for determining the potential future greenhouse gas emissions from thawing permafrost, especially because this area close to the discontinuous permafrost boundary is projected to thaw substantially within the 21st century.

scholarly journals Organic matter characteristics in yedoma and thermokarst deposits on Baldwin Peninsula, west Alaska

2018 ◽  
Vol 15 (20) ◽  
pp. 6033-6048 ◽  
Author(s):  
Loeka L. Jongejans ◽  
Jens Strauss ◽  
Josefine Lenz ◽  
Francien Peterse ◽  
Kai Mangelsdorf ◽  
...  
Keyword(s):  
Organic Matter ◽  
Lake Sediments ◽  
Lake Basin ◽  
Study Region ◽  
Thermokarst Lake ◽  
Discontinuous Permafrost ◽  
Lipid Biomarker ◽  
Biomarker Analysis ◽  
Thawing Permafrost

Abstract. As Arctic warming continues and permafrost thaws, more soil and sedimentary organic matter (OM) will be decomposed in northern high latitudes. Still, uncertainties remain in the quality of the OM and the size of the organic carbon (OC) pools stored in different deposit types of permafrost landscapes. This study presents OM data from deep permafrost and lake deposits on the Baldwin Peninsula which is located in the southern portion of the continuous permafrost zone in west Alaska. Sediment samples from yedoma and drained thermokarst lake basin (DTLB) deposits as well as thermokarst lake sediments were analyzed for cryostratigraphical and biogeochemical parameters and their lipid biomarker composition to identify the belowground OC pool size and OM quality of ice-rich permafrost on the Baldwin Peninsula. We provide the first detailed characterization of yedoma deposits on Baldwin Peninsula. We show that three-quarters of soil OC in the frozen deposits of the study region (total of 68 Mt) is stored in DTLB deposits (52 Mt) and one-quarter in the frozen yedoma deposits (16 Mt). The lake sediments contain a relatively small OC pool (4 Mt), but have the highest volumetric OC content (93 kg m−3) compared to the DTLB (35 kg m−3) and yedoma deposits (8 kg m−3), largely due to differences in the ground ice content. The biomarker analysis indicates that the OM in both yedoma and DTLB deposits is mainly of terrestrial origin. Nevertheless, the relatively high carbon preference index of plant leaf waxes in combination with a lack of a degradation trend with depth in the yedoma deposits indicates that OM stored in yedoma is less degraded than that stored in DTLB deposits. This suggests that OM in yedoma has a higher potential for decomposition upon thaw, despite the relatively small size of this pool. These findings show that the use of lipid biomarker analysis is valuable in the assessment of the potential future greenhouse gas emissions from thawing permafrost, especially because this area, close to the discontinuous permafrost boundary, is projected to thaw substantially within the 21st century.

scholarly journals Acetate turnover and methanogenic pathways in Amazonian lake sediments

2019 ◽  
Author(s):  
Ralf Conrad ◽  
Melanie Klose ◽  
Alex Enrich-Prast
Keyword(s):  
Lake Sediments ◽  
Turnover Rates ◽  
Hydrogenotrophic Methanogenesis ◽  
Ch4 Production ◽  
Relative Contribution ◽  
Acetate Methyl ◽  
Syntrophic Oxidation ◽  
Aceticlastic Methanogenesis ◽  
Respiratory Index ◽  
Amazonian Lake

Abstract. Lake sediments in Amazonia are a significant source of CH4, a potential greenhouse gas. Previous studies of sediments using 13C analysis found that the contribution of hydrogenotrophic versus aceticlastic methanogenesis to CH4 production was relatively high. Here, we determined the methanogenic pathway in the same sediments (n = 6) by applying [14C]bicarbonate or [2-14C]acetate, and confirmed the high relative contribution (50–80 %) of hydrogenotrophic methanogenesis. The respiratory index (RI) of [2-14C]acetate, which is 14CO2 relative to 14CH4 + 14CO2, divided the sediments into two categories, i.e., those with an RI  0.4 showing that a large percentage of the acetate-methyl was oxidized to CO2 rather than reduced to CH4. Hence, part of the acetate was probably converted to CO2 plus H2 via syntrophic oxidation, thus enhancing hydrogenotrophic methanogenesis. This happened despite the presence of potentially aceticlastic Methanosaetaceae in all the sediments. Alternatively, acetate may have been oxidized with a constituent of the sediment organic matter (humic acid) serving as oxidant. Indeed, apparent acetate turnover rates were larger than CH4 production rates except in those sediments with a R 

scholarly journals Increases in temperature and nutrient availability positively affect methane‐cycling microorganisms in Arctic thermokarst lake sediments

2018 ◽  
Vol 20 (12) ◽  
pp. 4314-4327 ◽  
Author(s):  
Anniek E. E. de Jong ◽  
Michiel H. in ’t Zandt ◽  
Ove H. Meisel ◽  
Mike S. M. Jetten ◽  
Joshua F. Dean ◽  
...  
Keyword(s):  
Lake Sediments ◽  
Nutrient Availability ◽  
Methane Cycling ◽  
Thermokarst Lake

Organic carbon sorbed to reactive iron minerals released during permafrost collapse

2020 ◽  
Author(s):  
Monique S. Patzner ◽  
Merritt Logan ◽  
Carsten W. Mueller ◽  
Hanna Joss ◽  
Sara E. Anthony ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Greenhouse Gas ◽  
Carbon Sink ◽  
Gas Analysis ◽  
Mineral Dissolution ◽  
Dynamic Interactions ◽  
Iron Minerals ◽  
Reactive Iron ◽  
Permafrost Soils ◽  
Thawing Permafrost

<p>The release of vast amounts of organic carbon during thawing of high-latitude permafrost is an urgent issue of global concern, yet it is unclear what controls how much carbon will be released and how fast it will be subsequently metabolized and emitted as greenhouse gases. Binding of organic carbon by iron(III) oxyhydroxide minerals can prevent carbon mobilization and degradation. This “rusty carbon sink” has already been suggested to protect organic carbon in soils overlying intact permafrost. However, the extent to which iron-bound carbon will be mobilized during permafrost thaw is entirely unknown. We have followed the dynamic interactions between iron and carbon across a thaw gradient in Abisko (Sweden), where wetlands are expanding rapidly due to permafrost retreat. Using both bulk (selective extractions, EXAFS) and nanoscale analysis (correlative SEM and nanoSIMS), we found that up to 19.4±0.7% of total organic carbon is associated with reactive iron minerals in palsa underlain by intact permafrost. However, during permafrost collapse, the rusty carbon sink is lost due to more reduced conditions which favour microbial Fe(III) mineral dissolution. This leads to high dissolved Fe(II) (2.93±0.42 mM) and organic carbon concentrations (480.06±34.10 mg/L) in the porewater at the transition of desiccating palsa to waterlogged bog. Additionally, by combining FT-ICR-MS and greenhouse gas analysis both in the field and in laboratory microcosm experiments, we are currently determining the fate of the mobilized organic carbon directly after permafrost collapse. Our findings will improve our understanding of the processes controlling organic carbon turnover in thawing permafrost soils and help to better predict future greenhouse gas emissions.</p><p> </p>

scholarly journals In situ adsorption of mercury, methylmercury and other elements by iron oxyhydroxides and organic matter in lake sediments

2010 ◽  
Vol 25 (7) ◽  
pp. 984-995 ◽  
Author(s):  
Stéphane Feyte ◽  
André Tessier ◽  
Charles Gobeil ◽  
Daniel Cossa
Keyword(s):  
Organic Matter ◽  
Lake Sediments ◽  
Iron Oxyhydroxides ◽  
In Situ Adsorption

scholarly journals Thermal diffusivity of thermokarst lake ice in the Beiluhe basin of the Qinghai–Tibetan Plateau

2014 ◽  
Vol 55 (66) ◽  
pp. 153-158 ◽  
Author(s):  
Liqiong Shi ◽  
Zhijun Li ◽  
Fujun Niu ◽  
Wenfeng Huang ◽  
Peng Lu ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Tibetan Plateau ◽  
Temperature Regime ◽  
Freezing Point ◽  
Control Model ◽  
Ecological Systems ◽  
Lake Ice ◽  
Point Temperature ◽  
Thermokarst Lake

AbstractThe ice cover on the Qinghai–Tibetan Plateau plays an important role in the environmental and ecological systems. We analyze the in situ measurements of ice growth and examine the thermal diffusivity of thermokarst lake ice in the Beiluhe basin. We evaluate numerically the change of thermal diffusivity of thermokarst lake ice with changing ice temperature using an optimal control model. In a higher ice temperature regime (–3 to 0°C), the thermal diffusivity of thermokarst lake ice decreases exponentially with increasing ice temperature, and approaches the thermal diffusivity value of fresh water near the freezing-point temperature. In a lower ice temperature regime (–15 to –3°C), the thermal diffusivity increases slowly with decreasing ice temperature.

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