Sensitivity of pond methane emissions in the Lena River Delta to climate changes in new model MeEP

2021 ◽  
Author(s):  
Zoé Rehder ◽  
Thomas Kleinen ◽  
Lars Kutzbach ◽  
Victor Stepanenko ◽  
Victor Brovkin
Keyword(s):  
Spatial Variability ◽  
Model Performance ◽  
Methane Emissions ◽  
River Delta ◽  
Lena River ◽  
Methane Fluxes ◽  
Eddy Covariance Measurements ◽  
Ice Wedge ◽  
Set Up ◽  
Lena River Delta

<p>Permafrost ponds are a steady source of methane. However, it is difficult to assess the sensitivity of pond methane emissions to ongoing warming and climate-change-induced drainage, because pond methane emissions show large temporal and spatial variability already on local scale.<br>We study this sensitivity on the landscape level with a new process-based model for Methane Emissions from Ponds (MeEP model), which simulates the three main pathways of methane emissions (diffusion, plant-mediated transport and ebullition) as well as the temperature profile of the water column and the surrounding soils. The model was set up for the polygonal tundra in the Lena River Delta. Due to a temporal resolution of one hour, it is capable of capturing the diurnal, day-to-day and seasonal variability in methane fluxes. MeEP also considers one of the main drivers of spatial variability - ground heterogeneity. Depending on where ponds form in the polygonal tundra, they can be classified as ice-wedge, polygonal-centre or merged-polygonal ponds. In MeEP, each of these pond types is simulated separately and the representation of these ponds was informed by dedicated measurements.<br>The model performance is validated against eddy-covariance measurements of methane fluxes and against in-situ measurements of the aqueous methane concentration, both obtained on Samoylov Island.  We will present results regarding the sensitivity of modeled methane emissions from ponds to warming and drainage on the landscape scale.</p>

scholarly journals Scaling and balancing methane fluxes in a heterogeneous tundra ecosystem of the Lena River Delta

2019 ◽  
Vol 266-267 ◽  
pp. 243-255 ◽  
Author(s):  
Norman Rößger ◽  
Christian Wille ◽  
Georg Veh ◽  
Julia Boike ◽  
Lars Kutzbach
Keyword(s):  
River Delta ◽  
Lena River ◽  
Tundra Ecosystem ◽  
Methane Fluxes ◽  
Lena River Delta

scholarly journals Identifying Drivers Behind Spatial Variability of Methane Concentrations in East Siberian Ponds

2021 ◽  
Vol 9 ◽  
Author(s):  
Zoé Rehder ◽  
Anna Zaplavnova ◽  
Lars Kutzbach
Keyword(s):  
Surface Water ◽  
Spatial Variability ◽  
Water Depth ◽  
Methane Emissions ◽  
The Arctic ◽  
Lena River ◽  
Small Water ◽  
Important Region ◽  
Ice Wedge ◽  
Methane Concentrations

Waterbody methane emissions per area are negatively correlated with the size of the emitting waterbody. Thus, ponds, defined here as having an area smaller than 8 · 104m2, contribute out of proportion to the aquatic methane budget compared to the total area they cover and compared to other waterbodies. However, methane concentrations in and methane emissions from ponds show more spatial variability than larger waterbodies. We need to better understand this variability to improve upscaling estimates of freshwater methane emissions. In this regard, the Arctic permafrost landscape is an important region, which, besides carbon-rich soils, features a high pond density and is exposed to above-average climatic warming. We studied 41 polygonal-tundra ponds in the Lena River Delta, northeast Siberia. We collected water samples at different locations and depths in each pond and determined methane concentrations using gas chromatography. Additionally, we collected information on the key properties of the ponds to identify drivers of surface water methane concentrations. The ponds can be categorized into three geomorphological types with distinct differences in drivers of methane concentrations: polygonal-center ponds, ice-wedge ponds and larger merged polygonal ponds. All ponds are supersaturated in methane, but ice-wedge ponds exhibit the highest surface water concentrations. We find that ice-wedge ponds feature a strong stratification due to consistently low bottom temperatures. This causes surface concentrations to mainly depend on wind speed and on the amount of methane that has accumulated in the hypolimnion. In polygonal-center ponds, high methane surface concentrations are mostly determined by a small water depth. Apart from the influence of water depth on mixing speed, water depth controls the overgrown fraction, the fraction of the pond covered by vascular plants. The plants provide labile substrate to the methane-producing microbes. This link can also be seen in merged polygonal ponds, which furthermore show the strongest dependence on area as well as an anticorrelation to energy input indicating that stratification influences the surface water methane concentrations in larger ponds. Overall, our findings underpin the strong variability of methane concentrations in ponds. No single driver could explain a significant part of the variability over all pond types suggesting that more complex upscaling methods such as process-based modeling are needed.

Spatiotemporal variability of methane emissions of tundra landscapes in the Lena River Delta, Siberia

2020 ◽  
Author(s):  
Lars Kutzbach ◽  
Norman Rößger ◽  
Tim Eckhardt ◽  
Christian Knoblauch ◽  
Torsten Sachs ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Growing Season ◽  
Landscape Scale ◽  
River Delta ◽  
The Other ◽  
Permafrost Degradation ◽  
River Terrace ◽  
Lena River ◽  
River Terraces ◽  
Lena River Delta

<p>Increased methane (CH<sub>4</sub>) release from a warming Arctic is expected to be a major feedback on the global climate. However, due to the complex effects of climate change on arctic geoecosystems, projections of future CH<sub>4</sub> emissions are highly uncertain. CH<sub>4</sub> emissions from complex tundra landscapes will be controlled not only by direct climatic effects on production, oxidation and transport of CH<sub>4</sub> but, importantly, also by geomorphology and hydrology changes caused by gradual or abrupt permafrost degradation. Therefore, improving our understanding of both the temporal dynamics and the spatial heterogeneity of CH4 fluxes on multiple scales is still necessary.</p><p>Here, we present pedon- and landscape-scale CH<sub>4</sub> flux measurements at two widespread tundra landscapes (active floodplains and late-holocene river terraces) of the Lena River Delta in the Siberian Arctic (72.4° N, 126.5° E). The dominating scales of spatial variability of soil, vegetation and CH<sub>4</sub> fluxes differ between the two landscapes of different geological development stage. The active floodplains are characterized by sandy beaches and ridges, and backswamp depressions, forming a mesorelief with height differences of several meters on horizontal scales of 10-1000 m. On the other hand, the river terraces are characterized by the formation of ice-wedge polygons, which lead to a regular microrelief with height differences of several decimeters on horizontal scales of 1 to 10 meters. CH<sub>4</sub> fluxes were investigated on the landscape scale with the eddy covariance method (15 campaigns during 2002-2018 at the river terrace, 2 campaigns 2014-2015 at the floodplain) and on the pedon scale with chamber methods (campaigns at different sites in 2002, 2006, 2013, 2014, 2015).</p><p>Average growing season (June-September) CH<sub>4</sub> flux for the floodplain was 166 ± 4 mmol m<sup>-2</sup> (<em>n</em>=2) and for the river terrace 100 ± 25 mmol m<sup>-2</sup> (<em>n</em>=15). There was pronounced spatial variability of CH<sub>4</sub> fluxes within both tundra landscapes types. On the river terrace, growing season CH<sub>4</sub> flux was only 20-40 mmol m<sup>-2</sup> at elevated polygon rims and polygon high centers, respectively, and up to 300 mmol m<sup>-2</sup> at polygon low centers. On the floodplain, CH<sub>4</sub> flux was as low as 5 mmol m<sup>-2</sup> at sandy ridges and above 400 mmol m<sup>-2</sup> in backswamp depressions. Mean growing season CH<sub>4</sub> fluxes at the river terrace were positively linearly correlated (<em>r</em><sup>2</sup> = 0.9, <em>n</em>=15) to growing-degree-days (base temperature of 5 °C). Our findings suggest that a warmer climate stimulates the production of CH<sub>4</sub>, which is directly reflected in increased CH<sub>4</sub> emissions. On the other hand, warming effects on CH<sub>4</sub> oxidation appear limited because transport processes that bypass the soil oxidation zone, i.e. plant-mediated transport and ebullition, dominate CH<sub>4</sub> emission from wet tundra landscapes. However, since CH<sub>4</sub> emissions strongly vary with (micro-)topographical situation within tundra landscapes, the changes of geomorphology and hydrology due to permafrost degradation will probably be the dominating driver of future CH<sub>4</sub> emissions from arctic tundra landscapes.</p>

Short-term climate and vegetation dynamics in Lena River Delta (northern Yakutia, Eastern Siberia) during early Eocene

Palaeoworld ◽  
2021 ◽  
Author(s):  
Olesya V. Bondarenko ◽  
Nadezhda I. Blokhina ◽  
Tatiyana A. Evstigneeva ◽  
Torsten Utescher
Keyword(s):  
Vegetation Dynamics ◽  
River Delta ◽  
Early Eocene ◽  
Eastern Siberia ◽  
Short Term ◽  
Lena River ◽  
Lena River Delta

The Rock Magnetic Portrait of the Devonian Section of Stolb Island (Lena River Delta)

2021 ◽  
Vol 501 (1) ◽  
pp. 906-911
Author(s):  
D. V. Metelkin ◽  
A. I. Chernova ◽  
V. A. Vernikovsky ◽  
N. E. Mikhaltsov ◽  
V. V. Abashev
Keyword(s):  
River Delta ◽  
Lena River ◽  
Lena River Delta

scholarly journals Sentinel-1 SAR Interferometry for Surface Deformation Monitoring in Low-Land Permafrost Areas

2018 ◽  
Vol 10 (9) ◽  
pp. 1360 ◽  
Author(s):  
Tazio Strozzi ◽  
Sofia Antonova ◽  
Frank Günther ◽  
Eva Mätzler ◽  
Gonçalo Vieira ◽  
...  
Keyword(s):  
Time Series ◽  
Surface Displacement ◽  
Deformation Monitoring ◽  
In Situ Measurements ◽  
River Delta ◽  
Sar Interferometry ◽  
The Arctic ◽  
Lena River ◽  
Lena River Delta

Low-land permafrost areas are subject to intense freeze-thaw cycles and characterized by remarkable surface displacement. We used Sentinel-1 SAR interferometry (InSAR) in order to analyse the summer surface displacement over four spots in the Arctic and Antarctica since 2015. Choosing floodplain or outcrop areas as the reference for the InSAR relative deformation measurements, we found maximum subsidence of about 3 to 10 cm during the thawing season with generally high spatial variability. Sentinel-1 time-series of interferograms with 6–12 day time intervals highlight that subsidence is often occurring rather quickly within roughly one month in early summer. Intercomparison of summer subsidence from Sentinel-1 in 2017 with TerraSAR-X in 2013 over part of the Lena River Delta (Russia) shows a high spatial agreement between both SAR systems. A comparison with in-situ measurements for the summer of 2014 over the Lena River Delta indicates a pronounced downward movement of several centimetres in both cases but does not reveal a spatial correspondence between InSAR and local in-situ measurements. For the reconstruction of longer time-series of deformation, yearly Sentinel-1 interferograms from the end of the summer were considered. However, in order to infer an effective subsidence of the surface through melting of excess ice layers over multi-annual scales with Sentinel-1, a longer observation time period is necessary.

scholarly journals Lena River Delta formation during the Holocene

2014 ◽  
Vol 11 (3) ◽  
pp. 4085-4122 ◽  
Author(s):  
D. Bolshiyanov ◽  
A. Makarov ◽  
L. Savelieva
Keyword(s):  
Sea Water ◽  
River Delta ◽  
The Arctic ◽  
Laptev Sea ◽  
Lena River ◽  
Sea Levels ◽  
Marine Terraces ◽  
Delta Formation ◽  
Carbon Reservoir ◽  
Lena River Delta

Abstract. The Lena River Delta, the largest delta of the Arctic Ocean, differs from other deltas because it consists mainly of organomineral sediments, commonly called peat, that contain a huge organic carbon reservoir. The analysis of Delta sediment radiocarbon ages showed that they could not have formed as peat during floodplain bogging, but accumulated when Laptev Sea water level was high and green mosses and sedges grew and were deposited on the surface of flooded marshes. The Lena River Delta formed as organomineral masses and layered sediments accumulated during transgressive phases when sea level rose. In regressive phases, the islands composed of these sediments and other, more ancient islands were eroded. Each new sea transgression led to further accumulation of layered sediments. As a result of alternating transgressive and regressive phases the first alluvial-marine terrace formed, consisting of geological bodies of different ages. Determining the formation age of different areas of the first terrace and other marine terraces on the coast allowed the periods of increasing (8–6 Ka, 4.5–4 Ka, 2.5–1.5 Ka, 0.4–0.2 Ka) and decreasing (5 Ka, 3 Ka, 0.5 Ka) Laptev Sea levels to be distinguished in the Lena Delta area.

scholarly journals Dynamics of the relief and sesmotectonic activity of the modern structures in the delta of the river lena

2019 ◽  
pp. 62-77
Author(s):  
L. P. Imaeva ◽  
G. S. Gusev ◽  
V. S. Imaev
Keyword(s):  
Transition Zone ◽  
North American ◽  
Active Faults ◽  
River Delta ◽  
The Arctic ◽  
Main Element ◽  
Dominant Factor ◽  
Lena River ◽  
Lithospheric Plates ◽  
Lena River Delta

This paper presents seismogeodynamic analysis of modern structures located in the Lena river delta. These structures are key elements in the tectonic evolution of the shelf–continent transition zone in the Arctic segment of the boundary between the Eurasian and North American lithospheric plates. The geological structure of the Lena river delta is predetermined by the junction of the ancient Siberian platform and the Mesozoic Laptev Sea plate. These two large geoblocks of the crust, which differ in age, are separated by a fragment of the Kharaulakh segment of the Verkhoyansk fold system. In our study aimed to reveal regularities in seismotectonic destruction of the crust, we analyzed the geological and geophysical data on the crustal structure, active faults, modern structural plan, dynamic characteristics of the modern relief, and hydrological features characterizing of the flow redistribution in the Lena riverbed. A system of active faults identified in the Lena river delta shows a contrasting kinematic plan of the junction zone of the main geostructures. According to the analysis results, shear faulting is a dominant factor of impact on the morphologic features and seismogeodynamic activation of the modern structures. A regional right-lateral strike-slip fault of the sublatitudinal strike is traced as a major structural boundary that cuts the Lena river delta into several geodynamic segments. Seismotectonic destruction of the crust in the segments differs in types (transpression, transtension and compression). The above-mentioned fault is not only the main element of the kinematic plan of the newest structures in the Lena river delta – it controls the general structural pattern and seismotectonic parameters of active fault zones in the entire northern sector of the Verkhoyansk marginal suture. The seismogeodynamic analysis results obtained in our study provide a reliable basis for estimating potential seismic hazard of the modern structures in the Lena river delta and updating the available seismic zoning maps of the shelf–continent transition zone in the Arctic segment of the boundary between the Eurasian and North American lithospheric plates.

Sign in / Sign up

Export Citation Format

Share Document