Organic matter sources and early diagenetic alterations in Arctic surface sediments (Lena River delta and Laptev Sea, Eastern Siberia), II.

Global warming in high latitudes causes destabilization of vulnerable permafrost deposits followed by massive thaw-release of organic carbon. Permafrost-derived carbon may be buried in the nearshore sediments, transported towards the deeper basins or degraded into the greenhouse gases, potentially initiating a positive feedback to climate change. In the present study, we aim to identify the sources, distribution and degradation state of organic matter (OM) stored in the surface sediments of the Laptev Sea (LS), which receives a large input of terrestrial carbon from both Lena River discharge and intense coastal erosion. We applied a suite of geochemical indicators including the Rock Eval parameters, traditionally used for the matured OM characterization, and terrestrial lipid biomarkers. In addition, we analyzed a comprehensive grain size data in order to assess hydrodynamic sedimentation regime across the LS shelf. Rock-Eval (RE) data characterize LS sedimentary OM with generally low hydrogen index (100–200 mg HC/g TOC) and oxygen index (200 and 300 CO2/g TOC) both increasing off to the continental slope. According to Tpeak values, there is a clear regional distinction between two groups (369–401 °C for the inner and mid shelf; 451–464 °C for the outer shelf). We suggest that permafrost-derived OM is traced across the shallow and mid depths with high Tpeak and slightly elevated HI values if compared to other Arctic continental margins. Molecular-based degradation indicators show a trend to more degraded terrestrial OC with increasing distance from the coast corroborating with RE results. However, we observed much less variation of the degradation markers down to the deeper sampling horizons, which supports the notion that the most active OM degradation in LS land-shelf system takes part during the cross-shelf transport, not while getting buried deeper.

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

Palaeoworld ◽

10.1016/j.palwor.2021.09.006 ◽

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

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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.

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Trace metal distribution in pristine permafrost-affected soils of the Lena River Delta and its Hinterland, Northern Siberia, Russia

Biogeosciences Discussions ◽

10.5194/bgd-10-2205-2013 ◽

2013 ◽

Vol 10 (2) ◽

pp. 2205-2244 ◽

Cited By ~ 1

Author(s):

I. Antcibor ◽

S. Zubrzycki ◽

A. Eschenbach ◽

L. Kutzbach ◽

D. Bol'shiyanov ◽

...

Keyword(s):

Trace Elements ◽

Organic Matter ◽

Trace Metal ◽

Climatic Changes ◽

River Delta ◽

Metal Distribution ◽

Background Concentrations ◽

Lena River ◽

Trace Metal Distribution ◽

Lena River Delta

Abstract. Soils are an important compartment of ecosystems and have the ability to immobilize chemicals preventing their movement to other environment compartments. Predicted climatic changes together with other anthropogenic influences on Arctic terrestrial environments may affect biogeochemical processes enhancing leaching and migration of trace elements in permafrost-affected soils. This is especially important since the Arctic ecosystems are considered to be very sensitive to climatic changes as well as to chemical contamination. This study characterizes background levels of trace metals in permafrost-affected soils of the Lena River Delta and its hinterland in northern Siberia (73.5° N–69.5° N) representing a remote region far from evident anthropogenic trace metal sources. Investigations on total element contents of iron (Fe), arsenic (As), manganese (Mn), zinc (Zn), nickel (Ni), copper (Cu), lead (Pb), cadmium (Cd), cobalt (Co) and mercury (Hg) in different soil types developed in different geological parent materials have been carried out. The highest concentrations of the majority of the measured elements were observed in soils belonging to ice-rich permafrost sediments formed during the Pleistocene (ice-complex) in the Lena River Delta region. Correlation analyses of trace metal concentrations and soil chemical and physical properties at a Holocene estuarine terrace and two modern floodplain levels in the southern-central Lena River Delta (Samoylov Island) showed that the main factors controlling the trace metal distribution in these soils are organic matter content, soil texture and contents of iron and manganese-oxides. Principal Component Analysis (PCA) revealed that soil oxides play a significant role in trace metal distribution in both top and bottom horizons. Occurrence of organic matter contributes to Cd binding in top soils and Cu binding in bottom horizons. Observed ranges of the background concentrations of the majority of trace elements were similar to background levels reported for other pristine arctic areas and did not exceed mean global background concentrations examined for the continental crust as well as for the world's soils.

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From Fresh to Marine Waters: Characterization and Fate of Dissolved Organic Matter in the Lena River Delta Region, Siberia

Frontiers in Marine Science ◽

10.3389/fmars.2015.00108 ◽

2015 ◽

Vol 2 ◽

Cited By ~ 30

Author(s):

Rafael Gonçalves-Araujo ◽

Colin A. Stedmon ◽

Birgit Heim ◽

Ivan Dubinenkov ◽

Alexandra Kraberg ◽

...

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

River Delta ◽

Delta Region ◽

Marine Waters ◽

Lena River ◽

Lena River Delta

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Spatial and temporal variability of SAR backscatter signatures of coastal sea-ice types off the Lena River Delta (Laptev Sea)

IEEE 1999 International Geoscience and Remote Sensing Symposium. IGARSS'99 (Cat. No.99CH36293) ◽

10.1109/igarss.1999.775018 ◽

2003 ◽

Author(s):

H. Eicken ◽

U. Blahak ◽

W. Dierking ◽

I. Dmitrenko

Keyword(s):

Sea Ice ◽

Temporal Variability ◽

River Delta ◽

Spatial And Temporal Variability ◽

Laptev Sea ◽

Lena River ◽

Coastal Sea ◽

Lena River Delta

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New genetic types of landforms and deposits of the coastal part of the western sector of the Laptev Sea and the Lena River Delta

ARCTIC AND SUBARCTIC NATURAL RESOURCES ◽

10.31242/2618-9712-2021-26-2-5 ◽

2021 ◽

pp. 81-93

Keyword(s):

River Delta ◽

Laptev Sea ◽

Lena River ◽

Western Sector ◽

Genetic Types ◽

Lena River Delta ◽

The Laptev Sea

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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.

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Mercury and methylmercury along a transect from the Lena river estuary across the Laptev Sea Shelf

10.5194/egusphere-egu2020-13727 ◽

2020 ◽

Author(s):

Van Liem Nguyen ◽

Birgit Wild ◽

Örjan Gustafsson ◽

Igor Semiletov ◽

Oleg Dudarev ◽

...

Keyword(s):

Organic Matter ◽

Continental Shelf ◽

Arctic Ocean ◽

River Delta ◽

The Arctic ◽

Laptev Sea ◽

Terrestrial Organic Matter ◽

Lena River ◽

The Arctic Ocean ◽

The Laptev Sea

Widespread accelerated permafrost thawing is predicted for this century and beyond. This threatens to remobilize the large amounts of Mercury (Hg) currently &#8216;locked&#8217; in Arctic permafrost soils to the Arctic Ocean and thus potentially lead to severe consequences for human and wildlife health. Future risks of Arctic Hg in a warmer climate are, however, poorly understood. One crucial knowledge gap to fill is the fate of Hg once it enters the marine environment on the continental shelves. Arctic rivers are already today suggested to be the main source of Hg into the Arctic Ocean, with dissolved and particulate organic matter (DOM and POM, respectively) identified as important vectors for the land to sea transport.In this study, we have investigated total Hg (HgT) and monomethylmercury (MeHg) concentrations in surface sediments from the East Siberian Arctic Shelf (ESAS) along a transect from the Lena river delta to the Laptev Sea continental slope. The ESAS is the world&#8217;s largest continental shelf and receives large amounts of organic carbon by the great Arctic Russian rivers (e.g., Lena, Indigirka and Kolyma), remobilized from continuous and discontinuous permafrost regions in the river catchments, and from coastal erosion. Data on HgT and MeHg levels in ESAS sediments is however limited. Here, we observed concentrations of Hg ranging from 30 to 96 ng Hg g-1 d.w. of HgT, and 0.03 to 9.5 ng Hg g-1 d.w. of MeHg. Similar concentrations of HgT were observed close to the river delta (54 &#177; 19 ng Hg g-1 d.w.), where >95 % of the organic matter is of terrestrial origin, and the other section of the transect (42 &#177; 7 ng Hg g-1 d.w.) where the terrestrial organic matter is diluted with carbon from marine sources. In contrast, we observed higher concentrations of MeHg close to the river delta (0.72 &#177; 0.71 ng Hg g-1 d.w. as MeHg) than further out on the continental shelf (0.031 &#177; 0.71 ng Hg g-1 d.w. as MeHg). We also observed a positive correlation between the MeHg:Hg ratio and previously characterized molecular markers of terrestrial organic matter (Br&#246;der et al. Biogeosciences (2016) & Nature Com. (2018)). We thus suggest riverine inputs, rather than in situ MeHg formation, to explain observed MeHg trends.

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