Stabilization of organic material from soils and soil-like bodies in the Lena River Delta (13C-NMR spectroscopy analysis)

The Arctic ecosystem has a huge reservoir of soil organic carbon stored in permafrost-affected soils and biosediments. During the short vegetation season, humification and mineralization processes in the active soil layer result in the formation of specific soil organic substances – humic substances. Humic acids are high molecular, specific, thermodynamically stable macromolecules. The study was conducted in the Lena River Delta, the largest river delta located in the Arctic. Cryosol-type soils on alluvial deposits of the river form an area of about 45 thousand km2 under permafrost conditions. The vegetation cover is represented by moss-lichen communities with the presence of Salix glauca in the flooded areas, as well as Betula nana in the areas not subject to flooding. The paper presents the elemental and molecular composition of humic acids isolated from soils, integral indicators of humification (stabilization) of organic matter in the soils of the Lena River Delta. The study was conducted using the 13C (CP/MAS) NMR spectroscopy method. In the work, it was revealed that up to 33% of aromatic and up to 15% COOR fragments are accumulated in humic acids. The AR/AL ratio ranged from 0.69 to 0.89. The studied soils are variants of modern soil formation (not subjected to alluvial processes) and soil-like bodies that melted from the IC of the river delta. A relatively high degree of condensation of humic acid macromolecules in comparison with other polar regions of the Arctic and Antarctic was noted.

Download Full-text

Humus formation in soils of the Lena River Delta

Почвы и окружающая среда ◽

10.31251/pos.v4i4.163 ◽

2021 ◽

Vol 4 (4) ◽

Author(s):

V. I. Polyakov ◽

E. V. Abakumov

Keyword(s):

Nmr Spectroscopy ◽

Humic Substances ◽

Humic Acids ◽

13C Nmr ◽

Vascular Plants ◽

13C Nmr Spectroscopy ◽

River Delta ◽

Lena River ◽

Soil Microstructure ◽

Lena River Delta

The aim of the study. Nowadays close attention is paid to polar soils due to the expected landscape transformation rate under the predicted climate crisis. Intensive degradation of permafrost and the release of nutrients from their frozen state can lead to an increase in the emission of greenhouse gases into the atmosphere, as well as the loss of landscapes. The aim of the study was to investigate the peculiarities of organic residues formation and humification degree as well as humus structure and functioning in soil the Lena River Delta. Location and time of the study. The study was conducted on the Samoylov and Sardach Islands in the Lena River Delta (Yakutia, Russia). Field studies were performed during the summer of 2019. Objects and methodology. Soils of the Lena River Delta from the Samoylov Island (flooded area) and Sardakh (non-flooded zone), i.e. Subaquatic Fluvisol (Arenic) and Histic Cryosol (Siltic) were the objects of the study, respectively. To examine the features of humification chemical-analytical, sedimentation, micromorphological methods were used, as well as CP/MAS 13C-NMR spectroscopy. Main results. The data obtained indicate a high diversity of soils and soil formation conditions in the Lena River Delta. Under non-flooded conditions Histic Cryosol (Siltic) were formed in the flooded parts of the Samoylov Island, Subaquatic Fluvisol (Arenic) were formed. These soils play an important role in the global carbon cycle, accumulation, transformation and deposition of condensed high- and low molecular mass organic compounds in the composition of soils and permafrost. The main soil micromorphology features were identified. In the young landscapes the soil microstructure was represented by poorly sorted sand with a circular type of optical orientation of the soil plasma (which indicated the influence of the river), as well as vertically oriented micas (muscovite/biotite). Soils influenced by the floodplain process were characterized by the presence of coarse amorphous humus. Due to the long-term effect of the freezing/thawing processes on the permafrost-affected soils the biogenic aggregates were formed. In such organo-mineral microaggregates humus is fixed in the composition of mineral components consisting of particles of quartz, micas and Mn-Fe nodules and is in a stable state (physical stabilization of humus). To analyze the molecular composition the 13C NMR spectroscopy method was used. According to 13C NMR spectroscopy data, up to 37% of aromatic structural fragments accumulated in soils, which indicates the process of condensation of molecules in humic acids, thus showing a relatively high level of humus stabilization in the soils of the Lena River delta. From the data obtained, three main groups of chemical structural fragments that accumulate in the delta soils can be distinguished, such as C,H - alkyls ((CH2)n/CH/C and CH3), aromatic compounds (C–C/C–H, C–O) and the OCH group (OCH/OCq). In the studied humic preparations aliphatic structural fragments of HAs (63–64%) predominated, which indicated a deficiency of lignin and lignin-like compounds in the composition of humification precursors. The predominance of aliphatic structures is typical of humic substances formed under reduction conditions, including the aqueous humic substances, as well as in soils, the precursors of humification of which are typical tundra vegetation (mosses and lichens) with a predominance of carbohydrates (up to 80%). A significant amount of aromatic fragments accumulated in the delta in the alluvial soils of the first terrace of the river (flooded zone). This is apparently due to the formation of vascular plants in the flooded areas of the Lena River Delta. The chemical composition of vascular plants includes components such as tannins, flavonoids and lignin (arenas). Thus in the samples formed under vascular plants with a lignin content of about 30%, an increase in signals in the range of 110-160 ppm were observed. Aromatic and carboxyl fragments in the structure of HA were formed during the transformation of lignin, which leads to the resistance of HAs to biodegradation. Conclusion. Under the floodplain condition humus is represented by coarse amorphous forms, whereas without the influence of flooding humus is fixed in mineral microaggregates. Specific humic acids composition in the studied regions is determined by bioclimatic conditions, cryogenic processes and the composition of humification precursors. High abundance of aromatic structures in humus substances suggests relatively stable humus status (most likely due to the putative condensation of humic acids) in the Lena River Delta during the study period.

Download Full-text

Assessments of Organic Carbon Stabilization Using the Spectroscopic Characteristics of Humic Acids Separated from Soils of the Lena River Delta

Separations ◽

10.3390/separations8060087 ◽

2021 ◽

Vol 8 (6) ◽

pp. 87

Author(s):

Vyacheslav Polyakov ◽

Evgeny Abakumov

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Organic Carbon ◽

Humic Acids ◽

Terrestrial Ecosystems ◽

River Delta ◽

The Arctic ◽

Lena River ◽

Organic Matter Stabilization ◽

Lena River Delta

In the Arctic zone, where up to 1024 × 1013 kg of organic matter is stored in permafrost-affected soils, soil organic matter consists of about 50% humic substances. Based on the analysis of the molecular composition of humic acids, we assessed the processes of accumulation of the key structural fragments, their transformations and the stabilization rates of carbon pools in soils in general. The landscape of the Lena River delta is the largest storage of stabilized organic matter in the Arctic. There is active accumulation and deposition of a significant amount of soil organic carbon from terrestrial ecosystems in a permafrost state. Under ongoing climate change, carbon emission fluxes into the atmosphere are estimated to be higher than the sequestration and storing of carbon compounds. Thus, investigation of soil organic matter stabilization mechanisms and rates is quite an urgent topic regarding polar soils. For study of molecular elemental composition, humic acids were separated from the soils of the Lena River delta. Key structural fragments of humic matter were identified and quantified by CP/MAS 13C NMR spectroscopy: carboxyl (–COOR); carbonyl (–C=O); CH3–; CH2–; CH-aliphatic; –C-OR alcohols, esters and carbohydrates; and the phenolic (Ar-OH), quinone (Ar = O) and aromatic (Ar–) groups as benchmark Cryosols of the Lena delta river terrestrial ecosystem. Under the conditions of thermodynamic evolutionary selection, during the change between the dry and wet seasons, up to 41% of aromatic and carboxyl fragments accumulated in humic acids. Data obtained showed that three main groups of carbon played the most important role in soil organic matter stabilization, namely C, H-alkyls ((CH2)n/CH/C and CH3), aromatic compounds (C-C/C-H, C-O) and an OCH group (OCH/OCq). The variations of these carbon species’ content in separated humics, with special reference to soil–permafrost organic profiles’ recalcitrance in the current environment, is discussed.

Download Full-text

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

Remote Sensing ◽

10.3390/rs10091360 ◽

2018 ◽

Vol 10 (9) ◽

pp. 1360 ◽

Cited By ~ 22

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.

Download Full-text

Lena River Delta formation during the Holocene

Biogeosciences Discussions ◽

10.5194/bgd-11-4085-2014 ◽

2014 ◽

Vol 11 (3) ◽

pp. 4085-4122 ◽

Cited By ~ 1

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.

Download Full-text

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

Геотектоника ◽

10.31857/s0016-853x2019562-77 ◽

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.

Download Full-text

Stabilization of organic carbon isolated from cryoconite holes in polar and mountain systems by 13С NMR spectroscopy

10.5194/egusphere-egu21-4156 ◽

2021 ◽

Author(s):

Vjacheslav Polyakov ◽

Evgeny Abakumov

Keyword(s):

Carbon Dioxide ◽

Organic Matter ◽

Nmr Spectroscopy ◽

Humic Acids ◽

Carbon Dioxide Emissions ◽

Heterogeneous Systems ◽

Basic Research ◽

13C Nmr Spectroscopy ◽

The Arctic ◽

Additional Contribution

Black carbon is one of the short-lived climatically significant factors. This term refers to climate-forming substances that are located for a short amount of time in the atmosphere - from several days to several years. To identify the role of cryoconite in the conditions of a possible climatic crisis, the stabilization of organic matter isolated from cryoconite holes was assessed. Humic acids are part of the organic matter accumulating in soils and cryoconites and are heterogeneous systems of high-molecular condensed compounds formed as a result of the decomposition of organic remains of plants and animals in terrestrial and aquatic ecosystems. Climatic parameters, precursors of humification, and the local position in the landscape determine the diversity of the composition and properties of HAs. Stabilization of organic material is defined as the transformation of organic matter into a state inaccessible to soil microorganisms, and the very property of stabilization is a characteristic stage in the dynamics of carbon. Using 13C NMR spectroscopy, we determined the proportion of aromatic and aliphatic compounds in the composition of HAs in order to assess the stabilization of organic matter in cryoconites from Mount Elbrus (Caucasus Mountains, Russia), the Arctic (Severnaya Zemlya archipelago, Russia) and Antarctica (King George Island, West Antarctica).Samples for qualitative analysis of carbon accumulated in cryoconites were carried out during fieldwork in 2020. The studied samples were analyzed at the Department of Applied Ecology, St. Petersburg State University. Humic acids (HAs) were extracted from each sample according to a published IHSS protocol. Solid-state CP/MAS 13C-NMR spectra of HAs were measured with a Bruker Avance 500 NMR spectrometer.Thus, it follows from the obtained results that aliphatic fragments of humic acids predominate in all studied cryoconites. A similar composition of humic acids testifies to a single mechanism of accumulation and development of organic matter in glacier regions. Low biological activity and climatic features prevent condensation of high-molecular compounds in the organic matter of cryoconite holes. This is an essential prerequisite for high rates of carbon dioxide emissions into the atmosphere under the conditions of deglaciation of the studied regions. With the thawing of glaciers and the ingress of cryoconites into warmer conditions, an additional contribution of carbon dioxide to the atmosphere can occur and, therefore, increase the possible climate crisis on our planet.This study was supported by Russian Foundation for Basic Research No. 19-05-50107.

Download Full-text

Organic carbon and total nitrogen stocks in soils of the Lena River Delta

Biogeosciences ◽

10.5194/bg-10-3507-2013 ◽

2013 ◽

Vol 10 (6) ◽

pp. 3507-3524 ◽

Cited By ~ 50

Author(s):

S. Zubrzycki ◽

L. Kutzbach ◽

G. Grosse ◽

A. Desyatkin ◽

E.-M. Pfeiffer

Keyword(s):

Organic Carbon ◽

Active Layer ◽

River Delta ◽

The Arctic ◽

River Terrace ◽

Total N ◽

Lena River ◽

The Holocene ◽

Lena River Delta ◽

N Pool

Abstract. The Lena River Delta, which is the largest delta in the Arctic, extends over an area of 32 000 km2 and likely holds more than half of the entire soil organic carbon (SOC) mass stored in the seven major deltas in the northern permafrost regions. The geomorphic units of the Lena River Delta which were formed by true deltaic sedimentation processes are a Holocene river terrace and the active floodplains. Their mean SOC stocks for the upper 1 m of soils were estimated at 29 kg m−2 &pm; 10 kg m−2 and at 14 kg m−2 ± 7 kg m−2, respectively. For the depth of 1 m, the total SOC pool of the Holocene river terrace was estimated at 121 Tg ± 43 Tg, and the SOC pool of the active floodplains was estimated at 120 Tg ± 66 Tg. The mass of SOC stored within the observed seasonally thawed active layer was estimated at about 127 Tg assuming an average maximum active layer depth of 50 cm. The SOC mass which is stored in the perennially frozen ground at the increment 50–100 cm soil depth, which is currently excluded from intense biogeochemical exchange with the atmosphere, was estimated at 113 Tg. The mean nitrogen (N) stocks for the upper 1 m of soils were estimated at 1.2 kg m−2 ± 0.4 kg m−2 for the Holocene river terrace and at 0.9 kg m−2 ± 0.4 kg m−2 for the active floodplain levels, respectively. For the depth of 1 m, the total N pool of the river terrace was estimated at 4.8 Tg ± 1.5 Tg, and the total N pool of the floodplains was estimated at 7.7 Tg ± 3.6 Tg. Considering the projections for deepening of the seasonally thawed active layer up to 120 cm in the Lena River Delta region within the 21st century, these large carbon and nitrogen stocks could become increasingly available for decomposition and mineralization processes.

Download Full-text

Bioindication of the water salinity dynamics by the microalgae communities in the Lena River Delta, Laptev Sea, Russian Arctic

Marine Biological Journal ◽

10.21072/mbj.2021.06.3.02 ◽

2021 ◽

Vol 6 (3) ◽

pp. 15-28

Author(s):

S. S. Barinova ◽

V. A. Gabyshev ◽

A. P. Ivanova ◽

O. I. Gabysheva

Keyword(s):

Species Composition ◽

River Delta ◽

Water Bodies ◽

Water Salinity ◽

The Arctic ◽

Laptev Sea ◽

Russian Arctic ◽

Lena River ◽

Lena River Delta ◽

The Laptev Sea

The Lena River in the Laptev Sea forms a vast delta, one of the largest in the world. The Ust-Lensky State Nature Reserve saves biodiversity on the Lena Delta territory beyond the Arctic Circle, in the zone of continuous permafrost. In recent years, large-scale plans for the development of extractive industries are implemented in this Russian Arctic sector. In this regard, the study of biodiversity and bioindication properties of aquatic organisms in the Lena River estuary area is becoming more and more relevant. This study aims to identify the species composition of microalgae in lotic and lentic water bodies of the Lena River Delta and use their indicator property for water salinity. It was a trace indicator of species distribution over the delta and their dynamics along the delta main watercourses to assess the impact of river waters on the Laptev Sea coastal areas. For this, all previously published materials on algae and chemical composition of the region waters as well as data obtained in recent years for the waters of the lower Lena reach were involved. In total, 700 species considered to 10 phyla were analyzed: Cyanobacteria (83), Euglenozoa (13), Ochrophyta (Chrysophyta, Xanthophyta) (41), Eustigmatophyta (4), Bacillariophyta (297), Miozoa (20), Cryptophyta (3), Rhodophyta (1), Chlorophyta (125), and Charophyta (111). The available materials of the field and reference observations were analyzed using several statistical methods. The study results indicate that hydrological conditions are the main factor regulating the spatial structure of the species composition of the microalgae communities in the Lena River Delta. The distribution of groups of salinity indicators across flowing water bodies reflects the effect of water salinity, and this allows suggesting possible sources of this effect. The mechanism of tracking the distribution of environmental indicators itself is a sensitive method, that reveals even their subtle changes in them; therefore, as an integral method, it can be helpful for further monitoring.

Download Full-text

Origin and Pathways of Dissolved Organic Carbon in a Small Catchment in the Lena River Delta

Frontiers in Earth Science ◽

10.3389/feart.2021.759085 ◽

2022 ◽

Vol 9 ◽

Author(s):

Lydia Stolpmann ◽

Gesine Mollenhauer ◽

Anne Morgenstern ◽

Jens S. Hammes ◽

Julia Boike ◽

...

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

River Delta ◽

Aquatic Systems ◽

The Arctic ◽

Small Catchment ◽

Lena River ◽

Thermokarst Lake ◽

Doc Concentration ◽

Lena River Delta

The Arctic is rich in aquatic systems and experiences rapid warming due to climate change. The accelerated warming causes permafrost thaw and the mobilization of organic carbon. When dissolved organic carbon is mobilized, this DOC can be transported to aquatic systems and degraded in the water bodies and further downstream. Here, we analyze the influence of different landscape components on DOC concentrations and export in a small (6.45 km2) stream catchment in the Lena River Delta. The catchment includes lakes and ponds, with the flow path from Pleistocene yedoma deposits across Holocene non-yedoma deposits to the river outlet. In addition to DOC concentrations, we use radiocarbon dating of DOC as well as stable oxygen and hydrogen isotopes (δ18O and δD) to assess the origin of DOC. We find significantly higher DOC concentrations in the Pleistocene yedoma area of the catchment compared to the Holocene non-yedoma area with medians of 5 and 4.5 mg L−1 (p < 0.05), respectively. When yedoma thaw streams with high DOC concentration reach a large yedoma thermokarst lake, we observe an abrupt decrease in DOC concentration, which we attribute to dilution and lake processes such as mineralization. The DOC ages in the large thermokarst lake (between 3,428 and 3,637 14C y BP) can be attributed to a mixing of mobilized old yedoma and Holocene carbon. Further downstream after the large thermokarst lake, we find progressively younger DOC ages in the stream water to its mouth, paired with decreasing DOC concentrations. This process could result from dilution with leaching water from Holocene deposits and/or emission of ancient yedoma carbon to the atmosphere. Our study shows that thermokarst lakes and ponds may act as DOC filters, predominantly by diluting incoming waters of higher DOC concentrations or by re-mineralizing DOC to CO2 and CH4. Nevertheless, our results also confirm that the small catchment still contributes DOC on the order of 1.2 kg km−2 per day from a permafrost landscape with ice-rich yedoma deposits to the Lena River.

Download Full-text