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  • 1
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    DataSheet3.PDF
    Frontiers Media SA ; 2021
    In:  Frontiers in Earth Science Vol. 9 ( 2021-10-28)
    Details
    In: Frontiers in Earth Science, Frontiers Media SA, Vol. 9 ( 2021-10-28)
    Abstract: Ice-rich permafrost in the circum-Arctic and sub-Arctic (hereafter pan-Arctic), such as late Pleistocene Yedoma, are especially prone to degradation due to climate change or human activity. When Yedoma deposits thaw, large amounts of frozen organic matter and biogeochemically relevant elements return into current biogeochemical cycles. This mobilization of elements has local and global implications: increased thaw in thermokarst or thermal erosion settings enhances greenhouse gas fluxes from permafrost regions. In addition, this ice-rich ground is of special concern for infrastructure stability as the terrain surface settles along with thawing. Finally, understanding the distribution of the Yedoma domain area provides a window into the Pleistocene past and allows reconstruction of Ice Age environmental conditions and past mammoth-steppe landscapes. Therefore, a detailed assessment of the current pan-Arctic Yedoma coverage is of importance to estimate its potential contribution to permafrost-climate feedbacks, assess infrastructure vulnerabilities, and understand past environmental and permafrost dynamics. Building on previous mapping efforts, the objective of this paper is to compile the first digital pan-Arctic Yedoma map and spatial database of Yedoma coverage. Therefore, we 1) synthesized, analyzed, and digitized geological and stratigraphical maps allowing identification of Yedoma occurrence at all available scales, and 2) compiled field data and expert knowledge for creating Yedoma map confidence classes. We used GIS-techniques to vectorize maps and harmonize site information based on expert knowledge. We included a range of attributes for Yedoma areas based on lithological and stratigraphic information from the source maps and assigned three different confidence levels of the presence of Yedoma (confirmed, likely, or uncertain). Using a spatial buffer of 20 km around mapped Yedoma occurrences, we derived an extent of the Yedoma domain. Our result is a vector-based map of the current pan-Arctic Yedoma domain that covers approximately 2,587,000 km 2 , whereas Yedoma deposits are found within 480,000 km 2 of this region. We estimate that 35% of the total Yedoma area today is located in the tundra zone, and 65% in the taiga zone. With this Yedoma mapping, we outlined the substantial spatial extent of late Pleistocene Yedoma deposits and created a unique pan-Arctic dataset including confidence estimates.
    Type of Medium: Online Resource
    ISSN: 2296-6463
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.3389/feart.2021.758360
    DOI: 10.3389/feart.2021.758360.s001
    DOI: 10.3389/feart.2021.758360.s002
    DOI: 10.3389/feart.2021.758360.s003
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2021
    detail.hit.zdb_id: 2741235-0
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  • 2
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    Application of ground-penetrating radar imagery for three-dimensional visualisation of near-surface structures in ice-rich permafrost, Barrow, Alaska : 3D GPR Application Near Barrow, Alaska
    Wiley ; 2007
    In:  Permafrost and Periglacial Processes Vol. 18, No. 4 ( 2007-10), p. 309-321
    Details
    In: Permafrost and Periglacial Processes, Wiley, Vol. 18, No. 4 ( 2007-10), p. 309-321
    Type of Medium: Online Resource
    ISSN: 1045-6740
    URL: Issue
    URL: Article
    DOI: 10.1002/ppp.v18:4
    DOI: 10.1002/ppp.594
    RVK:
    RA 1000
    Language: English
    Publisher: Wiley
    Publication Date: 2007
    detail.hit.zdb_id: 1479993-5
    SSG: 14
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  • 3
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    Identifying historical and future potential lake drainage events on the western Arctic coastal plain of Alaska
    Wiley ; 2020
    In:  Permafrost and Periglacial Processes Vol. 31, No. 1 ( 2020-01), p. 110-127
    Details
    In: Permafrost and Periglacial Processes, Wiley, Vol. 31, No. 1 ( 2020-01), p. 110-127
    Abstract: Arctic lakes located in permafrost regions are susceptible to catastrophic drainage. In this study, we reconstructed historical lake drainage events on the western Arctic Coastal Plain of Alaska between 1955 and 2017 using USGS topographic maps, historical aerial photography (1955), and Landsat Imagery (ca. 1975, ca. 2000, and annually since 2000). We identified 98 lakes larger than 10 ha that partially ( 〉 25% of area) or completely drained during the 62‐year period. Decadal‐scale lake drainage rates progressively declined from 2.0 lakes/yr (1955–1975), to 1.6 lakes/yr (1975–2000), and to 1.2 lakes/yr (2000–2017) in the ~30,000‐km 2 study area. Detailed Landsat trend analysis between 2000 and 2017 identified two years, 2004 and 2006, with a cluster (five or more) of lake drainages probably associated with bank overtopping or headward erosion. To identify future potential lake drainages, we combined the historical lake drainage observations with a geospatial dataset describing lake elevation, hydrologic connectivity, and adjacent lake margin topographic gradients developed with a 5‐m‐resolution digital surface model. We identified ~1900 lakes likely to be prone to drainage in the future. Of the 20 lakes that drained in the most recent study period, 85% were identified in this future lake drainage potential dataset. Our assessment of historical lake drainage magnitude, mechanisms and pathways, and identification of potential future lake drainages provides insights into how arctic lowland landscapes may change and evolve in the coming decades to centuries.
    Type of Medium: Online Resource
    ISSN: 1045-6740 , 1099-1530
    URL: Issue
    URL: Article
    DOI: 10.1002/ppp.v31.1
    DOI: 10.1002/ppp.2038
    RVK:
    RA 1000
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 1479993-5
    SSG: 14
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  • 4
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    Biogeochemical and geocryological characteristics of wedge and thermokarst-cave ice in the CRREL permafrost tunnel, Alaska : Wedge and Thermokarst-Cave Ice in the CRREL Permafrost Tunnel, Alaska
    Wiley ; 2011
    In:  Permafrost and Periglacial Processes Vol. 22, No. 2 ( 2011-04), p. 120-128
    Details
    In: Permafrost and Periglacial Processes, Wiley, Vol. 22, No. 2 ( 2011-04), p. 120-128
    Type of Medium: Online Resource
    ISSN: 1045-6740
    URL: Article
    DOI: 10.1002/ppp.709
    RVK:
    RA 1000
    Language: English
    Publisher: Wiley
    Publication Date: 2011
    detail.hit.zdb_id: 1479993-5
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  • 5
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    Cryostratigraphy and Permafrost Evolution in the Lacustrine Lowlands of West‐Central Alaska
    Wiley ; 2014
    In:  Permafrost and Periglacial Processes Vol. 25, No. 1 ( 2014-01), p. 14-34
    Details
    In: Permafrost and Periglacial Processes, Wiley, Vol. 25, No. 1 ( 2014-01), p. 14-34
    Abstract: The influence of permafrost growth and thaw on the evolution of ice‐rich lowland terrain in the Koyukuk‐Innoko region of interior Alaska is fundamental but poorly understood. To elucidate this influence, the cryostratigraphy and properties of perennially frozen sediments from three areas in this region are described and interpreted in terms of permafrost history. The upper part of the late Quaternary sediments at the Koyukuk and Innoko Flats comprise frozen organic soils up to 4.5 m thick underlain by ice‐rich silt characterised by layered and reticulate cryostructures. The volume of visible segregated ice in silt locally reaches 50 per cent, with ice lenses up to 10 cm thick. A conceptual model of terrain evolution from the Late Pleistocene to the present day identifies four stages of yedoma degradation and five stages of subsequent permafrost aggradation‐degradation: (1) partial thawing of the upper ice wedges and the formation of small shallow ponds in the troughs above the wedges; (2) formation of shallow thermokarst lakes above the polygons; (3) deepening of thermokarst lakes and yedoma degradation beneath the lakes; (4) complete thawing of yedoma beneath the lakes; (5) lake drainage; (6) peat accumulation; (7) permafrost aggradation in drained lake basins; (8) formation of permafrost plateaus; and (9) formation and expansion of a new generation of thermokarst features. These stages can occur in differing places and times, creating a highly complex mosaic of terrain conditions, complicating predictions of landscape response to future climatic changes or human impact. Copyright © 2014 John Wiley & Sons, Ltd.
    Type of Medium: Online Resource
    ISSN: 1045-6740 , 1099-1530
    URL: Issue
    URL: Article
    DOI: 10.1002/ppp.v25.1
    DOI: 10.1002/ppp.1800
    RVK:
    RA 1000
    Language: English
    Publisher: Wiley
    Publication Date: 2014
    detail.hit.zdb_id: 1479993-5
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  • 6
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    Taliks, cryopegs, and permafrost dynamics related to channel migration, Colville River Delta, Alaska
    Wiley ; 2020
    In:  Permafrost and Periglacial Processes Vol. 31, No. 2 ( 2020-04), p. 239-254
    Details
    In: Permafrost and Periglacial Processes, Wiley, Vol. 31, No. 2 ( 2020-04), p. 239-254
    Abstract: Talik and cryopeg development related to channel migration has been observed in arctic deltas, but our knowledge on the configuration, properties, and rate of freezeback has remained limited. Along a main channel of the Colville River Delta (Alaska), we integrated subsurface data from 79 boreholes with a remote sensing analysis to measure channel changes in 1948–2013. We found that closed taliks occurred under the active channel and extended into intrapermafrost cryopeg layers under the riverbed/riverbar and active floodplain. Cryopegs as isolated small pockets were also identified at depths in older terrain units. In the study corridor, we estimated that the likelihood of talik and cryopeg occurrence was predominantly (42.2% of area) low, yet a high likelihood was also identified (27.0% of area). Permafrost growth occurred at a rapid rate in the land exposed following channel migration, likely due to the low and delayed release of latent heat as the freezing front progresses downward in the coarse‐grained soils of increasing salinity but decreasing temperatures. As the deposits keep cooling, ground ice will continue forming therefore increasing furthermore the salinity of the remaining unfrozen soil pore‐water and likely prevent the complete freezeback of the cryopegs developed in relation to channel migration.
    Type of Medium: Online Resource
    ISSN: 1045-6740 , 1099-1530
    URL: Issue
    URL: Article
    DOI: 10.1002/ppp.v31.2
    DOI: 10.1002/ppp.2046
    RVK:
    RA 1000
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 1479993-5
    SSG: 14
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  • 7
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    Alterations in the CD56− and CD56+ T Cell Subsets during COVID-19
    MDPI AG ; 2023
    In:  International Journal of Molecular Sciences Vol. 24, No. 10 ( 2023-05-20), p. 9047-
    Details
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 24, No. 10 ( 2023-05-20), p. 9047-
    Abstract: The effectiveness of the antiviral immune response largely depends on the activation of cytotoxic T cells. The heterogeneous group of functionally active T cells expressing the CD56 molecule (NKT-like cells), that combines the properties of T lymphocytes and NK cells, is poorly studied in COVID-19. This work aimed to analyze the activation and differentiation of both circulating NKT-like cells and CD56− T cells during COVID-19 among intensive care unit (ICU) patients, moderate severity (MS) patients, and convalescents. A decreased proportion of CD56+ T cells was found in ICU patients with fatal outcome. Severe COVID-19 was accompanied by a decrease in the proportion of CD8+ T cells, mainly due to the CD56− cell death, and a redistribution of the NKT-like cell subset composition with a predominance of more differentiated cytotoxic CD8+ T cells. The differentiation process was accompanied by an increase in the proportions of KIR2DL2/3+ and NKp30+ cells in the CD56+ T cell subset of COVID-19 patients and convalescents. Decreased percentages of NKG2D+ and NKG2A+ cells and increased PD-1 and HLA-DR expression levels were found in both CD56− and CD56+ T cells, and can be considered as indicators of COVID-19 progression. In the CD56− T cell fraction, increased CD16 levels were observed in MS patients and in ICU patients with lethal outcome, suggesting a negative role for CD56−CD16+ T cells in COVID-19. Overall, our findings suggest an antiviral role of CD56+ T cells in COVID-19.
    Type of Medium: Online Resource
    ISSN: 1422-0067
    URL: Article
    DOI: 10.3390/ijms24109047
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2019364-6
    SSG: 12
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  • 8
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    DataSheet1.docx
    Frontiers Media SA ; 2022
    In:  Frontiers in Earth Science Vol. 9 ( 2022-1-12)
    Details
    In: Frontiers in Earth Science, Frontiers Media SA, Vol. 9 ( 2022-1-12)
    Abstract: Since the discovery of frozen megafauna carcasses in Northern Siberia and Alaska in the early 1800s, the Yedoma phenomenon has attracted many Arctic explorers and scientists. Exposed along coastal and riverbank bluffs, Yedoma often appears as large masses of ice with some inclusions of sediment. The ground ice particularly mystified geologists and geographers, and they considered sediment within Yedoma exposures to be a secondary and unimportant component. Numerous scientists around the world tried to explain the origin of Yedoma for decades, even though some of them had never seen Yedoma in the field. The origin of massive ice in Yedoma has been attributed to buried surface ice (glaciers, snow, lake ice, and icings), intrusive ice (open system pingo), and finally to ice wedges. Proponents of the last hypothesis found it difficult to explain a vertical extent of ice wedges, which in some cases exceeds 40 m. It took over 150 years of intense debates to understand the process of ice-wedge formation occurring simultaneously (syngenetically) with soil deposition and permafrost aggregation. This understanding was based on observations of the contemporary formation of syngenetic permafrost with ice wedges on the floodplains of Arctic rivers. It initially was concluded that Yedoma was a floodplain deposit, and it took several decades of debates to understand that Yedoma is of polygenetic origin. In this paper, we discuss the history of Yedoma studies from the early 19th century until the 1980s—the period when the main hypotheses of Yedoma origin were debated and developed.
    Type of Medium: Online Resource
    ISSN: 2296-6463
    URL: Article
    URL: Article
    DOI: 10.3389/feart.2021.757891
    DOI: 10.3389/feart.2021.757891.s001
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2741235-0
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  • 9
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    Deep Convolutional Neural Networks for Automated Characterization of Arctic Ice-Wedge Polygons in Very High Spatial Resolution Aerial Imagery
    MDPI AG ; 2018
    In:  Remote Sensing Vol. 10, No. 9 ( 2018-09-18), p. 1487-
    Details
    In: Remote Sensing, MDPI AG, Vol. 10, No. 9 ( 2018-09-18), p. 1487-
    Abstract: The microtopography associated with ice-wedge polygons governs many aspects of Arctic ecosystem, permafrost, and hydrologic dynamics from local to regional scales owing to the linkages between microtopography and the flow and storage of water, vegetation succession, and permafrost dynamics. Wide-spread ice-wedge degradation is transforming low-centered polygons into high-centered polygons at an alarming rate. Accurate data on spatial distribution of ice-wedge polygons at a pan-Arctic scale are not yet available, despite the availability of sub-meter-scale remote sensing imagery. This is because the necessary spatial detail quickly produces data volumes that hamper both manual and semi-automated mapping approaches across large geographical extents. Accordingly, transforming big imagery into ‘science-ready’ insightful analytics demands novel image-to-assessment pipelines that are fueled by advanced machine learning techniques and high-performance computational resources. In this exploratory study, we tasked a deep-learning driven object instance segmentation method (i.e., the Mask R-CNN) with delineating and classifying ice-wedge polygons in very high spatial resolution aerial orthoimagery. We conducted a systematic experiment to gauge the performances and interoperability of the Mask R-CNN across spatial resolutions (0.15 m to 1 m) and image scene contents (a total of 134 km2) near Nuiqsut, Northern Alaska. The trained Mask R-CNN reported mean average precisions of 0.70 and 0.60 at thresholds of 0.50 and 0.75, respectively. Manual validations showed that approximately 95% of individual ice-wedge polygons were correctly delineated and classified, with an overall classification accuracy of 79%. Our findings show that the Mask R-CNN is a robust method to automatically identify ice-wedge polygons from fine-resolution optical imagery. Overall, this automated imagery-enabled intense mapping approach can provide a foundational framework that may propel future pan-Arctic studies of permafrost thaw, tundra landscape evolution, and the role of high latitudes in the global climate system.
    Type of Medium: Online Resource
    ISSN: 2072-4292
    URL: Article
    DOI: 10.3390/rs10091487
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2513863-7
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  • 10
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    Recent Warming Fuels Increased Organic Carbon Export From Arctic Permafrost
    American Geophysical Union (AGU) ; 2021
    In:  AGU Advances Vol. 2, No. 2 ( 2021-06)
    Details
    In: AGU Advances, American Geophysical Union (AGU), Vol. 2, No. 2 ( 2021-06)
    Abstract: Arctic warming has likely caused an increase of permafrost organic carbon export and/or deepening of mobilizable permafrost layers over the last 160 years Bank erosion is likely a key mechanism of mobilizing permafrost to the coast under warming conditions The rate of warming and the prevailing boundary conditions may be important modulators of permafrost thawing
    Type of Medium: Online Resource
    ISSN: 2576-604X , 2576-604X
    URL: Article
    DOI: 10.1029/2021AV000396
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2021
    detail.hit.zdb_id: 3008306-0
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