Description: The late Pleistocene Yedoma Ice Complex is an ice-rich and organic-bearing type of permafrost deposit widely distributed across Beringia and is assumed to be especially prone to deep degradation with warming temperature, which is a potential tipping point of the climate system. To better understand Yedoma formation, its local characteristics, and its regional sedimentological composition, we compiled the grain-size distributions (GSDs) of 771 samples from 23 Yedoma locations across the Arctic; samples from sites located close together were pooled to form 17 study sites. In addition, we studied 160 samples from three non-Yedoma ice-wedge polygon and floodplain sites for the comparison of Yedoma samples with Holocene depositional environments. The multimodal GSDs indicate that a variety of sediment production, transport, and depositional processes were involved in Yedoma formation. To disentangle these processes, a robust endmember modeling analysis (rEMMA) was performed. Nine robust grain-size endmembers (rEMs) characterize Yedoma deposits across Beringia. The study sites of Yedoma deposits were finally classified using cluster analysis. The resulting four clusters consisted of two to five sites that are distributed randomly across northeastern Siberia and Alaska, suggesting that the differences are associated with rather local conditions. In contrast to prior studies suggesting a largely aeolian contribution to Yedoma sedimentation, the wide range of rEMs indicates that aeolian sedimentation processes cannot explain the entire variability found in GSDs of Yedoma deposits. Instead, Yedoma sedimentation is controlled by local conditions such as source rocks and weathering processes, nearby paleotopography, and diverse sediment transport processes. Our findings support the hypothesis of a polygenetic Yedoma origin involving alluvial, fluvial, and niveo-aeolian transport; accumulation in ponding waters; and in situ frost weathering as well as postdepositional processes of solifluction, cryoturbation, and pedogenesis. The characteristic rEM composition of the Yedoma clusters will help to improve how grain-size-dependent parameters in permafrost models and soil carbon budgets are considered. Our results show the characteristic properties of ice-rich Yedoma deposits in the terrestrial Arctic. Characterizing and quantifying site-specific past depositional processes is crucial for elucidating and understanding the trajectories of this unique kind of ice-rich permafrost in a warmer future.

Description: 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/10.1002/2017GL075571

Description: Since 1994, permafrost deposits of the Siberian Yedoma region have been in the focus of the joint Russian-German scientific cooperation in terrestrial Polar research (Figure 1). These studies focused on cryostratigraphic, geochemical, geochronological, and paleontological characteristics at more than 25 individual study sites of the late Pleistocene Yedoma Ice Complex in Siberia and provided a detailed insight into the paleoenvironments and paleoclimate for the westernmost part of Beringia. The multidisciplinary investigations resulted in new ideas and discussions in the ongoing scientific debate on the origin of Yedoma Ice Complex and the main periglacial processes involved in its formation (1,2,3). The Yedoma Ice Complex is an ice-rich type of permafrost deposit widely distributed across Beringia. The Ice Complex aggradation is mainly controlled by the growth of syngenetic ice wedge polygons contributing up to 60 vol% of the entire formation. The clastic sedimentation of ice-oversaturated Yedoma deposits with considerable organic matter content is further controlled by local conditions such as source rocks and periglacial weathering processes, paleotopography, and temporary surface stabilization with autochthonous peat growth and soil formation. Key processes include alluvial, fluvial, and niveo-aeolian transport (4) as well as accumulation in ponding waters and continued in-situ frost weathering over millennial time-scales. Important post-depositional processes affecting Yedoma deposits are solifluction, cryoturbation, and pedogenesis. Major joint Russian-German field studies were conducted on Taymyr Peninsula (5,6,7,8,9,10,11), along the western and central Laptev Sea coasts (12,13,14,15,16,17,18), in the Lena Delta (19,20,21,22), on islands of the New Siberian Archipelago (23,24,25,26,27,28), and the adjacent mainland (29). Further study sites were conducted in the Kolyma Lowland (30), the Yana Highlands (31,32), in the foothills of the Verkhoyan Mountains (33,34,35,36), and in Central Yakutia (37). Comprehensive sampling and further analytical work included not only the Yedoma Ice Complex itself but also included its stratigraphic context of older underlying sequences and younger overlying deposits. The latter often are subaerial or subaquatic deposits associated with late-Glacial to Holocene thermokarst dynamics that led to Yedoma degradation during the deglacial and Holocene warming of these regions (38,39,40). Figure 1: Joint Russian-German fieldwork sites in NE Siberia labeled with the year of expedition. Besides geomorphological and cryolithological studies, extensive paleo-ecological investigations were carried out on zoological (41,42,43,44,45) and botanic fossils (46,47,48,49,50,51) to derive quantitative and qualitative reconstructions late Pleistocene Beringian environments and climate conditions. New methods in geochronology were also tested (52,53,54,55). In addition to the sedimentary components of the frozen deposits, segregated ground ice and in particular the large syngenetic ice wedges of Yedoma Ice Complex were also studied as geochemical and stable isotope archives of paleoclimate (56,57,58, 59,60,61,62). In addition, a range of remote sensing methods in combination with GIS analyses (63,64,65) and geophysical surveys (66) were used for large-scale analyses of landscape changes associated with Yedoma Ice Complex degradation (67,68,69). In the last few years, an additional important focus has been on using modern biogeochemical methods of organic matter analysis to characterize the frozen organic matter in Yedoma Ice Complex deposits and for permafrost carbon pool calculations (70, 71,72,73,74,75,76,77) as well as microbiological studies (78) and genetic studies on fossil DNA (79,80). The rich body of scientific data and literature produced in Russian-German co-authorship within the more than 25 years of joint research on Yedoma Ice Complex represents an important cornerstone for understanding the Late Quaternary evolution of Siberian Yedoma regions, its role in the Earth System, and its feedbacks with climate and ecosystems. References 1.Schirrmeister, L., Dietze, E., Matthes, H., Grosse, G., Strauss, J., Laboor, S., Ulrich, M., Kienast, F., and Wetterich, S. (2020) The genesis of Yedoma Ice Complex permafrost – grain-size endmember modeling analysis from Siberia and Alaska, E&G Quaternary Sci. J., 69, 33–53, doi: 10.5194/egqsj-69-33-2020. 2.Schirrmeister, L., Froese, D., Tumskoy, V., Grosse,G., Wetterich, S. (2013.) Yedoma: Late Pleistocene ice-rich syngenetic permafrost of Beringia. In: Elias S.A. (ed.) The Encyclopedia of Quaternary Science 2nd edition, vol. 3, pp. 542-552. Amsterdam: Elsevier. 3.Schirrmeister, L., Kunitsky, V.V., Grosse, G., Wetterich, S., Meyer, H., Schwamborn, G., Babiy, O., Derevyagin, A.Y., and Siegert, C.: Sedimentary characteristics and origin of the Late Pleistocene Ice Complex on North-East Siberian Arctic coastal lowlands and islands - a review. Quaternary International 241, 3-25, doi: 10.1016/j.quaint.2010.04.004, 2011. 4.Kunitsky, V., Schirrmeister, L., Grosse, G., Kienast, F. (2002). Snow patches in nival landscapes and their role for the Ice Complex formation in the Laptev Sea coastal lowlands, Polarforschung, 70, 53-67, doi:10.2312/polarforschung.70.53. 5.Andreev, A. , Siegert, C. , Klimanov, V. A. , Derevyagin, A. Y. , Shilova, G. N. and Melles, M. (2002) Late Pleistocene and Holocene vegetation and climate changes in the Taymyr lowland, Northern Siberia Quaternary research, 57, pp. 138-150 . 6.Andreev, A. , Tarasov, P. E. , Siegert, C. , Ebel, T. , Klimanov, V. A. , Melles, M. , Bobrov, A. A. , Derevyagin, A. Y. , Lubinski, D. J. and Hubberten, H. W. (2003) Vegetation and climate changes on the northern Taymyr, Russia during the Upper Pleistocene and Holocene reconstructed from pollen records, Boreas, 32 (3), pp. 484-505 . 7.Chizhov, A. B. , Derevyagin, A. Y. , Simonov, E. F. , Hubberten, H. W. and Siegert, C. (1997) Isotopic composition of ground ice at the Labaz Lake region (Taymyr). Kriosfera Zemlii (Earth Cryoshere), 1, No 3, pp. 79-84 . (in Russian), 8.Derevyagin, A.Yu., Chizhov, A.B., Brezgunov, V.S., Siegert, C., Hubberten, H.-W., 1999.Isotopic composition of ice wedges of Cape Sabler (Lake Taymyr). Kriosfera Zemlii (Earth Cryosphere) 3/3, 41-49 (in Russian). 9.Kienast, F., Siegert, C., Dereviagin, A., Mai, H.D. Climatic implications of Late Quaternary plant macrofossil assemblages from the Taymyr Peninsula, Siberia, Global and Planetary Change, Volume 31, Issues 1–4, 265-281, 2001, https://doi.org/10.1016/S0921-8181(01)00124-2. 10.Kienel, U. , Siegert, C. and Hahne, J. (1999) Late Quarternary paeloenvironmental reconstruction from a permafrost sequence (Northsiberian Lowland, SE Taymyr Peninsula) - a multidisciplinary case study, Boreas, 28 (1), pp. 181-193 . 11.Siegert C., Derevyagin A.Y., Shilova G.N., Hermichen WD., Hiller A. (1999) Paleoclimatic Indicators from Permafrost Sequences in the Eastern Taymyr Lowland. In: Kassens H. et al. (eds) Land-Ocean Systems in the Siberian Arctic. Springer, Berlin, Heidelberg. 12.Bobrov, A.A., Müller, S., Chizhikova, N.A., Schirrmeister, L., Andreev, A.A.(2009).Testate Amoebae in Late Quaternary Sediments of the Cape Mamontov Klyk (Yakutia), Biology Bulletin, 36(4), 363-372. 13.Schirrmeister, L., Grosse, G., Kunitsky, V., Magens, D., Meyer, H., Dereviagin, A., Kuznetsova, T., Andreev, A., Babiy, O., Kienast, F., Grigoriev, M., Overduin, P.P., and Preusser, F.: Periglacial landscape evolution and environmental changes of Arctic lowland areas for the last 60,000 years (Western Laptev Sea coast, Cape Mamontov Klyk), Polar Research, 27(2), 249-272, doi: 10.1111/j.1751-8369.2008.00067.x, 2008. 14.Winterfeld, M., Schirrmeister, L., Grigoriev, M., Kunitsky, V.V., Andreev, A., and Overduin, P.P.: Permafrost and Landscape Dynamics during the Late Pleistocene, Western Laptev Sea Shelf, Siberia, Boreas 40(4), 697–713, doi: 10.1111/j.1502-3885.2011.00203.x, 2011. 15.Siegert, C., Schirrmeister, L., and Babiy, O.: The sedimentological, mineralogical and geochemical composition of late Pleistocene deposits from the ice complex on the Bykovsky peninsula, northern Siberia, Polarforschung, 70, 2000, 3-11, doi: 10.2312/polarforschung.70.3, 2002. 16.Schirrmeister, L., Siegert, C., Kuznetsova, T., Kuzmina, S., Andreev, A.A., Kienast, F., Meyer, H., and Bobrov, A.A.: Paleoenvironmental and paleoclimatic records from permafrost deposits in the Arctic region of Northern Siberia, Quaternary International, 89, 97-118, doi: 10.1016/S1040-6182(01)00083-0, 2002. 17.Schirrmeister, L., Siegert, C., Kunitzky, V.V., Grootes, P.M., and Erlenkeuser, H.: Late Quaternary ice-rich permafrost sequences as a paleoenvironmental archive for the Laptev Sea Region in northern Siberia, International Journal of Earth Sciences, 91, 154-167, doi: 10.1007/s005310100205, 2002. 18.Schirrmeister, L., Schwamborn, G., Overduin, P.P., Strauss, J., Fuchs, M.C., Grigoriev, M., Yakshina, I., Rethemeyer, J., Dietze, E., and Wetterich, S.: Yedoma Ice Complex of the Buor Khaya Peninsula (southern Laptev Sea), Biogeosciences 14, 1261-1283, doi: 10.5194/bg-14-1261-2017, 2017. 19.Schirrmeister, L., Kunitsky, V.V., Grosse, G., Schwamborn, G., Andreev, A.A., Meyer, H., Kuznetsova, T., Bobrov, A., and Oezen, D.: Late Quaternary history of the accumulation plain north of the Chekanovsky Ridge (Lena Delta, Russia) - a multidisciplinary approach, Polar Geography, 27(4), 277-319, doi: 10.1080/789610225, 2003. 20.Schirrmeister, L., Grosse, G. Schnelle, M., Fuchs, M., Krbetschek, M., Ulrich, M., Kunitsky, V., Grigoriev, M., Andreev, A. Kienast, F., Meyer, H., Klimova, I., Babiy, O., Bobrov, A., Wetterich, S., and Schwamborn, G.: Late Quaternary paleoenvironmental records from the western Lena Delta, Arctic Siberia, Palaeogeography, Palaeoclimatology, Palaeoecology 299, 175–196, doi: 10.1016/j.quascirev.2009.11.017, 2011. 21.Schwamborn, G., Rachold, V., and Grigoriev, M.N.: Late Quaternary sedimentation history of the Lena Delta, Quaternary International 89, 119–134, doi: 10.1016/S1040-6182(01)00084-2, 2002. 22.Wetterich, S., Kuzmina, S., Andreev, A.A., Kienast, F., Meyer, H., Schirrmeister, L., Kuznetsova, T., and Sierralta, M.: Palaeoenvironmental dynamics inferred from late Quaternary permafrost deposits on Kurungnakh Island, Lena Delta, Northeast Siberia, Russia, Quaternary Science Reviews, 27, 1523-1540, doi: 10.1016/j.quascirev.2008.04.007, 2008. 23.Andreev, A.A., Grosse, G., Schirrmeister, L., Kuzmina, S.A., Novenko, E.Yu., Bobrov, A.A., Tarasov, P. E., Kuznetsova, T.V., Krbetschek, M., Meyer, H., and Kunitsky, V.V.: Late Saalian and Eemian palaeoenvironmental history of the Bol'shoy Lyakhovsky Island (Laptev Sea region, Arctic Siberia), Boreas 33(4), 319-348, doi:10.1080/03009480410001974, 2004. 24.Andreev, A., Grosse, G., Schirrmeister, L., Kuznetsova, T.V., Kuzmina, S.A., Bobrov, A.A., Tarasov, P.E., Novenko, E.Yu., Meyer, H., Derevyagin, A.Yu., Kienast, F., Bryantseva, A., and Kunitsky, V.V.: Weichselian and Holocene palaeoenvironmental history of the Bol’shoy Lyakhovsky Island, New Siberian Archipelago, Arctic Siberia, Boreas 38(1), 72–110, doi: 10.1111/j.1502-3885.2008.00039.x, 2009. 25.Wetterich, S., Rudaya, N., Meyer, H., Opel, T., and Schirrmeister, L.: Last Glacial Maximum records in permafrost of the East Siberian Arctic, Quaternary Science Reviews 30, 3139-3151, doi: 10.1016/j.quascirev.2011.07.020, 2011. 26.Wetterich, S., Rudaya, N., Andreev, A.A., Opel, T., Schirrmeister, L., Meyer, H., and Tumskoy, V.: Ice Complex formation in arctic East Siberia during the MIS3 Interstadial, Quaternary Science Reviews 84: 39-55, doi:. 10.1016/j.quascirev.2013.11.009, 2014. 27.Wetterich, S.; Tumskoy:V.E., Rudaya, N., Kuznetsov, V., Maksimov, F., Opel T. , Meyer H., Andreev, A.A., Schirrmeister, L (2016) Ice Complex permafrost of MIS5 age in the Dmitry Laptev Strait coastal region (East Siberian Arctic). Quaternary Science Reviews, 147:298-31, doi.org/10.1016/j.quascirev.2015.11.016. 28.Wetterich, S., Rudaya, N., Kuznetsov V., Maksimov, F., T. Opel, Meyer, H., Guenther, F., Bobrov, A., Raschke, E., Zimmermann, H., Strauss, J., Fuchs, M.C., Schirrmeister, L. (2019) Recurrent Ice Complex formation in arctic eastern Siberia since about 200 ka. Quaternary Research 92 (2); 530-548, doi.org/10.1017/qua.2019.6. 29.Wetterich, S., Schirrmeister, L., Andreev A. A., Pudenz, M., Plessen, B, Meyer, H., Kunitsky, V. V. (2009). Eemian and Late Glacial/Holocene palaeoenvironmental records from permafrost sequences at the Dmitry Laptev Strait (NE Siberia, Russia), Palaeogeography, Palaeoclimatology, Palaeoecology 279: 73-95 doi:10.1016/j.palaeo.2009.05.002. 30.Strauss, J., Schirrmeister, L., Wetterich, S., Borchers, A, and Davydov S.P.: Grain-size properties and organic-carbon stock of Yedoma Ice Complex permafrost from the Kolyma lowland, northeastern Siberia. GBC. 26: GB3003, doi: 10.1029/2011GB004104, 2012. 31.Ashastina, K., Schirrmeister, L., Fuchs M., and Kienast F.: Palaeoclimate characteristics in interior Siberia of MIS 6–2: first insights from the Batagay permafrost mega-thaw slump in the Yana Highlands, Clim. Past, 13, 795–818, doi: 10.5194/cp-13-795-2017, 2017. 32.Kunitsky, V.V., Syromyatnikov, I.I., Schirrmeister, L., Skachkov, Yu.B., Grosse, G., Wetterich, S., and Grigoriev, M.N.: Ice-rich permafrost and thermal denudation in the Kirgillyakh area, Kriosfera Zemli. 17(1), 56-68, 2013 (in Russian). 33.Popp, S., Diekmann,B., Meyer, H., Siegert, C.,Syromyatnikov, I., Hubberten, H.-W. Palaeoclimate Signals as Inferred from Stable-isotope Composition of Ground Ice in the Verkhoyansk Foreland, Central Yakutia. Permafrost and Periglac. Process. 17: 119–132 (2006) DOI: 10.1002/ppp.556 34.Popp, S., Belolyubsky, I., Lehmkuhl, F., Prokopiev, A., Siegert, C., Spektor, V., Stauch, G., Diekmann,B. Sediment provenance of late Quaternary morainic, fluvialand loess-like deposits in the southwestern VerkhoyanskMountains (eastern Siberia) and implications for regionalpalaeoenvironmental reconstructions. Geol. J.42: 477–497 (2007), DOI: 10.1002/gj.1088 35.Siegert, C. , Sergeyenko, A. I. and Schirrmeister, L. (2017) Late Quaternary Deposits of the Northern Verkhoyansk Mountains: Geochronology and Questions of their Genesis (in Russian), Bulletin of the Commission for Study of the Quaternary = БЮЛЛЕТЕНЬ КОМИССИИ ПО ИЗУЧЕНИЮ ЧЕТВЕРТИЧНОГО ПЕРИОДА, 75 , pp. 100-112 . 36.Siegert, C. , Stauch, G. , Lehmkuhl, F. , Sergeyenko, A. I. , Diekmann, B. , Popp, S. and Belolyubsky, I. N. (2007) Development of glaciation in the Verkhoyansk Range and its foreland during the Pleistocene: Results of new investigations., Regionalnaya Geologiya i Metallogeniya (Regional Geology and Metallogeny), No. 30-31(in Russian)., 222 . 37.Ulrich, M., Morgenstern, A., Günther, F., Reiss, D. Bauch, K. E., Hauber, E., Rössler, S. and Schirrmeister, L. (2010) Thermokarst in Siberian ice-rich permafrost: Comparison to asymmetric scalloped depressions on Mars, Journal of Geophysical Research, 115, E10009 . doi:10.1029/2010JE003640 , 38.Morgenstern, A. , Grosse, G. , Günther, F. , Fedorova, I. and Schirrmeister, L. (2011): Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta. The Cryosphere, 5(4), 849–867, doi:10.5194/tc-5-849-2011. 39.Morgenstern, A. , Ulrich, M. , Günther, F. , Roessler, S. , Fedorova, I. V. , Rudaya, N. A. , Wetterich, S. , Boike, J. and Schirrmeister, L. (2013). Evolution of thermokarst in East Siberian ice-rich permafrost: A case study, Geomorphology, 201 , 363-379. doi:10.1016/j.geomorph.2013.07.011 40.Biskaborn, B. , Herzschuh, U. , Bolshiyanov, D. Y. , Schwamborn, G. and Diekmann, B. (2013) Thermokarst Processes and Depositional Events in a Tundra Lake, Northeastern Siberia, Permafrost and Periglac. Process.24: 160–174 doi:https://doi.org/10.1002/ppp.1769, 41.Kuznetsova, T. V. , Sulerzhitsky, L. D. , Andreev, A. , Siegert, C. , Schirrmeister, L. and Hubberten, H. W. (2003) Influence of Late Quaternary paleoenvironmental conditions on the distribution of mammals fauna in the Laptev Sea region, Occasional Papers in Earth Sciences, 5 , pp. 58-60 . 42.Kuznetsova T.V., Tumskoy V.E., Schirrmeister L., Wetterich S., (2019.) Paleozoological characteristics of the Late Neo-Pleistocene - Holocene sediments of Bykovsky Peninsula, Northern Yakutia (Палеозоологическая характеристика поздненеоплейстоценовых – голоценовых отложений Быковского Полуострова (Северная Якутия). Zoological Journal 98(11), 1268-1290. Special issue in honor of Andrey Sher. (in Russian) doi: 10.1134/S0044513419110102. 43.Bobrov, A. A. , Andreev, A. , Schirrmeister, L. and Siegert, C. (2004) Testate amoebae (Protozoa: Testacea) as bioindicators in the Late Quaternary deposits of the Bykovsky Peninsula, Laptev Sea, Russia, Palaeogeography palaeoclimatology palaeoecology, 209 , pp. 165-181 . doi:https://doi.org/10.1016/J.PALAEO.2004.02.012 44.Wetterich, S., Schirrmeister, L., Pietrzeniuk, E. (2005). Freshwater ostracodes in Quaternary permafrost deposits from the Siberian Arctic, Journal of Paleolimnology, 34, 363-376. doi:10.1007/s10933-005-5801-y 45.Müller, S., Bobrov, A. A., Schirrmeister, L., Andreev, A. A., Tarasov, P. E. (2009). Testate amoebae record from the Laptev Sea coast and its implication for the reconstruction of Late Pleistocene and Holocene environments in the Arctic Siberia, Palaeogeography, Palaeoclimatology, Palaeoecology 271(3-4), 301-315. doi:10.1016/j.palaeo.2008.11.003 46.Andreev, A.A., Schirrmeister, L., Siegert, C., Bobrov, A.A., Demske, D., Seiffert, M., Hubberten, H.-W. (2002). Paleoenvironmental changes in Northeastern Siberia during the Late Quaternary - evidence from pollen records of the Bykovsky Peninsula, Polarforschung, 70, 13-25, doi:10.2312/polarforschung.70.13. 47.Andreev, A.A.; Schirrmeister, L.; Tarasov , P.E.; Ganopolski , A.; Brovkin V.; Siegert, C.; Hubberten, H.-W. (2011). Vegetation and climate history in the Laptev Sea region (arctic Siberia) during Late Quaternary inferred from pollen records. Journal of Quaternary science reviews. 30, 2182-2199 doi:10.1016/j.quascirev.2010.12.026. 48.Kienast, F. , Schirrmeister, L. , Siegert, C. and Tarasov, P. (2005) Palaeobotanical evidence for warm summers in the East Siberian Arctic during the last cold stage, Quaternary Research, 63 (3), pp. 283-300. doi:https://doi.org/10.1016/j.yqres.2005.01.003 , 49.Kienast, F., Tarasov, P., Schirrmeister, L., Grosse, G., Andreev, A.A. (2008). Continental climate in the East Siberian Arctic during the last interglacial: implications from palaeobotanical records, Global and Planetary Change, 60(3/4), 535-562. doi:10.1016/j.gloplacha.2007.07.004 50.Kienast, F., Wetterich, S., Kuzmina, S., Schirrmeister, L., Andrev, A., Tarasov, P., Nazarova, L., Kossler, A., Frolova, A., Kunitsky, V. V.(2011) Paleontological records indicate the occurrence of open woodlands in a dry inland climate at the present-day Arctic coast in western Beringia during the last interglacial. Quaternary Science Reviews 30: 2134-2159, doi:10.1016/j.quascirev.2010.11.024. 51.Palagushkina, O.V., Wetterich, S., Schirrmeister, L., Nazarova, L.B. (2017) Modern and fossil diatom assemblages from Bol'shoy Lyakhovsky Island (New Siberian Archipelago, Arctic Siberia). Contemporary Problems of Ecology, 10, (4), 380–394. doi: 10.1134/S1995425517040060. 52.Gilichinsky, D. A. , Nolte, E., Basilyan, A.E., Beer, J., Blinov, A., Lazarev, V., Kholodov, A., Meyer, H., Nikolsky, P.A., Schirrmeister, L., Tumskoy, V. (2007). Dating of syngenetic ice wedges in permafrost with 36Cl and 10Be, Quaternary science reviews. 26, 1547-1556. doi:10.1016/j.quascirev.2007.04.004 53.Blinov A.V., Beer J., Tikhomirov D.A., Schirrmeister L., Meyer H., Abramov A.A., Basylyan A.E., Nikolskiy P.A., Tumskoy V.E., Kholodov A.L., Gilichinsky D.A. (2009) Permafrost dating with the cosmogenic radionuclides ( Report 1) (= Датирование многолетнемерзлых пород с помощью космогенных радионуклидов (сообщение 1). 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Description: Warming in the Arctic causes strong environmental changes with degradation of permafrost (permanently frozen ground). Active layer deepening (gradual thaw) and permafrost erosion (abrupt thaw) results in the mobilization and lateral transport of organic carbon, altering current carbon cycling in the Arctic. Ground ice content is a crucial factor limiting our understanding and ability to determine the rates and dynamics of permafrost thaw and its impact on potential thaw subsidence rates, changes in lateral hydrological pathways and its driving mechanisms on a landscape scale. In this study we investigate ground ice content and its characteristics across the most dominant landscape units of the Yukon coastal plain (Canadian Arctic), using two spatially and technically contrasting approaches. In our bottom-up approach, twelve permafrost cores were collected from moraine, lacustrine, fluvial and glaciofluvial deposits using a SIPRE corer (mean drilling depth of 2 m) in spring of 2019. Ground ice and sediment contents within polygon centers were analyzed and classified using computed tomography and image recognition software (k-means). Our top-down approach quantified ice-wedge volumes from remote sensing imagery tracing the circumference of polygon troughs over the same area. Preliminary results - extrapolated to the entire coastal plain - show that the ground-ice content in polygon centers vary significantly from massive ice in the polygon troughs (wedge-ice). Total ice volume was estimated around 80.2 vol.-%, of which 68.2 ± 18.1 vol.-% was attributed to ground ice in polygon centers, and 12 ± 3.1 vol.-% of the landscape is massive ice in wedge-ice along polygon troughs. Additionally, differences among and between landscape units are also substantial, with highest ice volume contents in moraines landscapes, where polygon centers contain 58.8 vol.-% ground ice and wedge-ice volume is 16.2 vol.-%), while the lowest ice contents are found in glacio-fluvial deposits (22.1 vol.-% resp. 9.1 vol.-%). Our results reveal a higher average and a larger variability in ground ice contents than previously found, suggesting a need of both ground-based measurements and remote sensing imagery to further our understanding of the future landscape subsidence, but also to avoid a likely under- or overestimation associated with the chosen approach. We conclude that due to the high ground ice contents on the Yukon coastal plain, substantial changes of the permafrost landscape will occur under current warming trends. These will include subsidence, abrupt erosion, changes in hydrology and organic carbon mobilization, degradation and export processes, which will differ between landscape units.

Description: The complex and non‐linear fluvial river dynamics are characterized by repeated periods of fluvial erosion and re‐deposition in different parts of the floodplain. Understanding the fluvial architecture (i.e. the three‐dimensional arrangement and genetic interconnectedness of different sediment types) is therefore fundamental to obtain well‐based information about controlling factors. However, investigating the fluvial architecture in buried floodplain deposits without natural exposures is challenging. We studied the fluvial architecture of the middle Weiße Elster floodplain in Central Germany, an extraordinary long‐standing archive of Holocene flooding and landscape changes in sensitive loess‐covered Central European landscapes. We applied a novel systematic approach by coupling two‐dimensional transects of electrical resistivity tomography (ERT) measurements and closely spaced core drillings with spatially resolved measurements of electromagnetic induction (EMI) of larger floodplain areas at three study sites. This allowed for (i) time and cost‐efficient core drillings based on preceding ERT measurements and (ii) spatially scaling up the main elements of the fluvial architecture, such as the distribution of thick silt‐clay overbank deposits and paleochannel patterns from the floodplain transects to larger surrounding areas. We found that fine‐grained sand and silt‐clay overbank deposits overlying basal gravels were deposited during several periods of intensive flooding. Those were separated from each other by periods of reduced flooding, allowing soil formation. However, the overbank deposits were severely laterally eroded before and during each sedimentation period. This was probably linked with pronounced meandering or even braiding of the river. Our preliminary chronological classification suggests that first fine‐grained sedimentation must have occurred during the Early to Middle Holocene, and the last phase of lateral erosion and sedimentation during the Little Ice Age. Our study demonstrates the high archive potential of the buried fluvial sediments of the middle Weiße Elster floodplain and provides a promising time and cost‐effective approach for future studies of buried floodplain sediments.

Description: We applied a novel time and cost‐efficient systematic approach to study the architecture of buried floodplain sediments of the Weiße Elster River in Germany by coupling two‐dimensional transects of Electrical Resistivity Measurements and closely spaced core drillings with spatially resolved measurements of Electromagnetic Induction of larger floodplain areas. We found that fine‐grained overbank deposits deposited during several periods of intensive flooding were severely laterally eroded before and during each following sedimentation period probably linked with pronounced meandering or even braiding.

Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659