A Methodological Model for Exchanging Local and Scientific Climate Change Knowledge in Northeastern Siberia

This paper analyzes findings from “Knowledge Exchanges,” which engaged communities of Viliui Sakha, native horse and cattle agropastoralists of northeastern Siberia, Russia, with regional scientific specialists, a cultural anthropologist, and a permafrost scientist. Our process of knowledge exchange involved first gathering ethnographic data from affected communities, through focus groups, interviews, and surveys, and analyzing how people perceived, understood, and responded to local change. Next we documented the community results and compared them with regional climate change data. Lastly, we discussed these results during community knowledge exchange events, facilitating an increased understanding across knowledge systems and stakeholder groups. The knowledge exchange method documented in this article provides an adaptable model for integrating local and scientific knowledge systems that allows participants to reach understanding more quickly at global and local levels of how climate change is affecting places and peoples.Cette communication vient analyser les constatations émanant de l’échange de connaissances auquel ont participé les collectivités de Viliui Sakha, des agropasteurs indigènes s’occupant de chevaux et de bétail dans le nord-est de la Sibérie, en Russie, des spécialistes scientifiques régionaux, un anthropologue des cultures et un scientifique spécialisé en pergélisol. Notre échange de connaissances a commencé par la collecte de données ethnographiques auprès des collectivités concernées, données qui ont été recueillies au moyen de groupes de discussion, d’entrevues et de sondages. Cette collecte de données a été suivie de l’analyse de la manière dont les gens percevaient les changements qui se produisent à l’échelle locale, de la manière dont ils comprenaient ces changements et de la manière dont ils y réagissaient. Ensuite, nous avons consigné les résultats obtenus au sein des collectivités et les avons comparés aux données sur le changement climatique régional. En dernier lieu, nous avons discuté de ces résultats à l’occasion de séances d’échanges de connaissances organisées dans les collectivités, puis nous avons favorisé une plus grande compréhension à l’échelle des systèmes de connaissances et au sein des groupes d’intervenants. La méthodologie de l’échange de connaissances dont il est question dans le présent article présente un modèle adaptable d’intégration des systèmes de connaissances locales et de connaissances scientifiques, modèle qui permet aux participants de comprendre plus rapidement, mondialement et localement, comment le changement climatique influe sur les lieux et les gens

New coumarin-[60] fullerene dyads connected by an alkynyl linkage: Synthesis and fluorescence studies. Evidence for efficient singlet-singlet energy transfer

Two new coumarin-[60] fullerene dyads, in which an alkyne group covalently links C60 to coumarin, are synthesized via 1,3-dipolar cycloaddition and spectroscopically characterized. Their photophysical properties in apolar (toluene) and polar (THF and benzonitrile) solvents are studied at room temperature, revealing the nature and polarity dependence of the excited-state interactions between the coumarin and C60 moieties. In both dyads and in all solvents, a strong quenching of the coumarin emission by C60 was observed. It mainly results from a fast and efficient singletesinglet resonance energy transfer from the coumarin moiety to the C60 moiety, but an electron transfer contribution, enhanced in polar solvents, also exists. In toluene, the fluorescence emission of the fullerene moiety is increased by the nonradiative energy transfer process, which occurs mainly by a dipoleedipole (FRET) mechanism. In polar solvents (THF and benzonitrile), fast electron transfer from ground-state coumarin to excited fullerene is significant, leading to a partial or complete quenching of the fullerene emission, depending on the dyad

The theoretical DFT study of electronic structure of thin Si/SiO2 quantum nanodots and nanowires

The atomic and electronic structure of a set of proposed thin (1.6 nm in diameter) silicon/silica quantum nanodots and nanowires with narrow interface, as well as parent metastable silicon structures (1.2 nm in diameter), was studied in cluster and PBC approaches using B3LYP/6-31G* and PW PP LDA approximations. The total density of states (TDOS) of the smallest quasispherical silicon quantum dot (Si85) corresponds well to the TDOS of the bulk silicon. The elongated silicon nanodots and 1D nanowires demonstrate the metallic nature of the electronic structure. The surface oxidized layer opens the bandgap in the TDOS of the Si/SiO2 species. The top of the valence band and the bottom of conductivity band of the particles are formed by the silicon core derived states. The energy width of the bandgap is determined by the length of the Si/SiO2 clusters and demonstrates inverse dependence upon the size of the nanostructures. The theoretical data describes the size confinement effect in photoluminescence spectra of the silica embedded nanocrystalline silicon with high accuracy.Comment: 22 pages, 5 figures, 1 tabl

Thermokarst Landscape Development Detected by Multiple-Geospatial Data in Churapcha, Eastern Siberia

Thermokarst is a typical process that indicates widespread permafrost degradation in yedoma landscapes. The Lena-Aldan interfluvial area in Central Yakutia in eastern Siberia is now facing extensive landscape changes with surface subsidence due to thermokarst development during the past few decades. To clarify the spatial extent and rate of subsidence, multiple spatial datasets, including GIS and remote sensing observations, were used to analyze the Churapcha rural locality, which has a typical yedoma landscape in Central Yakutia. Land cover classification maps for 1945 and 2009 provide basic information on anthropogenic disturbance to the natural landscape of boreal forest and dry grassland. Interferometric synthetic aperture radar (InSAR) with ALOS-2/PALSAR-2 data revealed activated surface subsidence of 2 cm/yr in the disturbed area, comprising mainly abandoned agricultural fields. Remote sensing with an unmanned aerial system also provided high-resolution information on polygonal relief formed by thermokarst development at a disused airfield where InSAR analysis exhibited extensive subsidence. It is worth noting that some historically deforested areas have likely recovered to the original landscape without further thermokarst development. Spatial information on historical land-use change is helpful because most areas with thermokarst development correspond to locations where land was used by humans in the past. Going forward, the integrated analysis of geospatial information will be essential for assessing permafrost degradation

Impact of climate change on the ground thermal regime in the lower Lena region, Arctic central Siberia

This paper presents the results of 30 years of permafrost thermal monitoring in the Tiksi area in the eastern Russian Arctic. At a stone ridge site, the mean annual temperatures in the upper 30 m of the ground have increased by 1–2.4 C compared to the first years of observations, with trends of C/yr. At the same time, its change was uneven. In the last 20 years, the rate of increase has increased compared with the first decade of observations. At wet tundra sites in the foothill plain, the mean annual temperatures at the top of permafrost have increased by 2.4–2.6 C between 2005 and 2022 at rates of 0.11–0.15 C/yr, and the active layer thicknesses have increased at rates of 0.05–0.41 cm/yr

Metagenomic survey of the microbiome of ancient Siberian permafrost and modern Kamchatkan cryosols

In the context of global warming, the melting of arctic permafrost raises the threat of a re-emergence of microorganisms some of which were shown to remain viable in ancient frozen soils for up to half a million years. In order to evaluate this risk, it is of interest to acquire a better knowledge of the composition of the microbial communities found in this understudied environment. Here we present a metagenomics analysis of 12 soil samples from Russian Arctic and subarctic pristine areas: Chukotka, Yakutia, and Kamchatka, including 9 permafrost samples collected at various depths. These large datasets (9.2 1011 total bp) were assembled (525,313 contigs > 5kb), their encoded protein contents predicted, then used to perform taxonomical assignments of bacterial, archaeal, and eukaryotic organisms, as well as DNA viruses. The various samples exhibited variable DNA contents and highly diverse taxonomic profiles showing no obvious relationship with their locations, depths or deposit ages. Bacteria represented the largely dominant DNA fraction (95%) in all samples, followed by archaea (3.2%), surprisingly little eukaryotes (0.5%), and viruses (0.4%). Although no common taxonomic pattern was identified, the samples shared unexpected high frequencies of β-lactamase genes, almost 0.9 copy/bacterial genome. In addition of known environmental threats, the particularly intense warming of the Arctic might thus enhance the spread of bacterial antibiotic resistances, today's major challenge in public health. β-lactamases were also observed at high frequency in other types of soils, suggesting their general role in the regulation of bacterial populations

Mercury in deep ice-rich permafrost deposits of Siberia. Russian Conference

The late Pleistocene ice-rich Yedoma permafrost is extremely sensitive to Arctic warming. Warming air temperatures, decreasing sea ice extent lead to an increasing degradation of the Yedoma permafrost and thus to a greater sediment input from coastal shorelines and river floodplains to the Laptev Sea. Thus, so far freeze-locked sediments and any potentially hazardous contaminants contained in them are entering Arctic waters and the biological food chain. Shallow (down to <2m) Arctic permafrost soil layers were found to include high levels of mercury (Hg) due to natural enrichment processes of environmentally available Hg (Schuster et al. 2018). However, opposed to seasonal thaw processes of the active layer and long-term gradual thaw through active layer deepening, abrupt thaw processes such as thermokarst, thermo-erosion, and coastal erosion are capable of mobilising permafrost-soils and stored contaminants from tens of meters depth within years to decades. In this study, we determined Hg concentrations from various deposits in Siberia’s deep permafrost sediments. We studied links between sediment properties and Hg enrichment in order to assess a first deep Hg inventory in late Pleistocene permafrost down to 36 m below surface. To do this, we used sediment profiles from seven sites representing different permafrost degradation states on Bykovsky Peninsula (northern Yakutian coast) and in the Yukechi Alas region (Central Yakutia). We analysed 41 samples for Hg content, total carbon, total nitrogen and organic carbon as well as grain size distribution, bulk density and mass specific magnetic susceptibility. Figure 1: (a) geographical overview and detailed location of the study site at Bykovsky Peninsula (b) and Yukechi Alas in Yakutia (c); (d) stratigraphical transect of the study sites and different states of degrading permafrost in Siberia. The numbers indicate the areas of interest in this study. 1) Talik in Yedoma (unfrozen), 2) late Pleistocene Yedoma (frozen), 3) talik in thermokarst (unfrozen), 4) refrozen drained lake basin = Alas (frozen), 5) talik in thermokarst close to sea (unfrozen), 6) talik below seawater flooded thermokarst basins (= lagoons) (unfrozen). We show that the deep sediments (to 30 meter below surface) are characterized by an Hg concentration of 9.72 ± 9.28 μg kg-1 and an correlation of Hg to organic carbon, total nitrogen, grain-size distribution and mass specific magnetic susceptibility. Hg concentrations are higher in the generally sandier sediment of the Bykovsky Peninsula than in the siltier sediment of the Yukechi Alas. In conclusion, we found that the deep permafrost sediments, frozen since tens of millennia, contain sizeable amounts of Hg. Even though the average amount of Hg is with 9.72 μg/kg below levels immediately critical for life and our median is 85 % less (Schuster et al. 2018) than found in Arctic topsoil outside Siberia. Even if the Hg concentrations are not particularly high compared to other sites, the permafrost’s huge spatial coverage results in a significant amount of Hg that can be introduce into nearby aquatic environments and food webs. As the next step, the consequences of old Hg re-entering the active biogeochemical cycles and food webs with ongoing Arctic warming remain unclear and need to be studied in more detail. References 1. Schuster, P. et al. Geophysical Research Letters, 2018, 45, 1463– 1471, https://doi.org/10.1002/2017GL07557

Organic carbon characteristics in ice-rich permafrost in alas and Yedoma deposits, central Yakutia, Siberia

Permafrost ground is one of the largest repositories of terrestrial organic carbon and might become or already is a carbon source in response to ongoing global warming. With this study of syngenetically frozen, ice-rich and organic carbon (OC)-bearing Yedoma and associated alas deposits in central Yakutia (Republic of Sakha), we aimed to assess the local sediment deposition regime and its impact on permafrost carbon storage. For this purpose, we investigated the Yukechi alas area (61.76495°N, 130.46664°E), which is a thermokarst landscape degrading into Yedoma in central Yakutia. We retrieved two sediment cores (Yedoma upland, 22.35m deep, and alas basin, 19.80m deep) in 2015 and analyzed the biogeochemistry, sedimentology, radiocarbon dates and stable isotope geochemistry. The laboratory analyses of both cores revealed very low total OC (TOC) contents (< 0.1 wt %) for a 12m section in each core, whereas the remaining sections ranged from 0.1 wt% to 2.4 wt% TOC. The core sections holding very little to no detectable OC consisted of coarser sandy material were estimated to be between 39 000 and 18 000 BP (years before present) in age. For this period, we assume the deposition of organic-poor material. Pore water stable isotope data from the Yedoma core indicated a continuously frozen state except for the surface sample, thereby ruling out Holocene reworking. In consequence, we see evidence that no strong organic matter (OM) decomposition took place in the sediments of the Yedoma core until today. The alas core from an adjacent thermokarst basin was strongly disturbed by lake development and permafrost thaw. Similar to the Yedoma core, some sections of the alas core were also OC poor (< 0.1 wt %) in 17 out of 28 samples. The Yedoma deposition was likely influenced by fluvial regimes in nearby streams and the Lena River shifting with climate. With its coarse sediments with low OC content (OC mean of 5.27 kg m-3), the Yedoma deposits in the Yukechi area differ from other Yedoma sites in North Yakutia that were generally characterized by silty sediments with higher OC contents (OC mean of 19 kg m-3 for the non-icewedge sediment). Therefore, we conclude that sedimentary composition and deposition regimes of Yedoma may differ considerably within the Yedoma domain. The resulting heterogeneity should be taken into account for future upscaling approaches on the Yedoma carbon stock. The alas core, strongly affected by extensive thawing processes during the Holocene, indicates a possible future pathway of ground subsidence and further OC decomposition for thawing central Yakutian Yedoma deposits

Molecular biomarkers in Batagay megaslump permafrost deposits reveal clear differences in organic matter preservation between glacial and interglacial periods

The Batagay megaslump, a permafrost thaw feature in north-eastern Siberia, provides access to ancient permafrost up to ∼650 kyr old. We aimed to assess the permafrost-locked organic matter (OM) quality and to deduce palaeo-environmental information on glacial–interglacial timescales. We sampled five stratigraphic units exposed on the 55 m high slump headwall and analysed lipid biomarkers (alkanes, fatty acids and alcohols). Our findings revealed similar biogeochemical signatures for the glacial periods: the lower ice complex (Marine Isotope Stage (MIS) 16 or earlier), the lower sand unit (sometime between MIS 16–6) and the upper ice complex (MIS 4–2). The OM in these units has a terrestrial character, and microbial activity was likely limited. Contrarily, the n-alkane and fatty acid distributions differed for the units from interglacial periods: the woody layer (MIS 5), separating the lower sand unit and the upper ice complex, and the Holocene cover (MIS 1), on top of the upper ice complex. The woody layer, marking a permafrost degradation disconformity, contained markers of terrestrial origin (sterols) and high microbial decomposition (iso- and anteiso-fatty acids). In the Holocene cover, biomarkers pointed to wet depositional conditions and we identified branched and cyclic alkanes, which are likely of microbial origin. Higher OM decomposition characterised the interglacial periods. As climate warming will continue permafrost degradation in the Batagay megaslump and in other areas, large amounts of deeply buried ancient OM with variable composition and degradability are mobilised, likely significantly enhancing greenhouse gas emissions from permafrost regions