ALBERT

Beschreibung: Abstract

Beschreibung: This dataset was collected during field-based monitoring in the Kali Gandaki River catchment be-tween the years 2013 and 2017. The monitoring aims to understand the hydrological fluxes and feedback with weathering and erosion processes across the mountain range. The Kali Gandaki River sources its water in the North and traverses through the Himalayan Mountain Range, along a north-south transect. The field-based monitoring comprises targeted field campaigns to revisit locations at different years and seasons in order to constrain the annual and intra-annual variability. This is complemented by permanent installations and routine river and rain sampling at two loca-tions, Lete and Purtighat. Lete is situated at the orographic barrier, at ~2500 m asl. and the up-stream catchment integrates the northern part of the Himalayan Range as well as some of the southern edge of the Tibetan Plateau. Purtighat is located further south and integrates the north-ern part as well as south-facing flanks of the Higher and Lower Himalayas. At both locations, auto-mated river monitoring is installed as well as a trained station ward for daily routine sampling. At Lete, rainfall samples are obtained on a daily resolution during the monsoon. This sampling was not feasible at Purtighat for logistic reasons. Instead, rain was sampled daily in Kathmandu. This dataset contains five tables of stable water isotope analysis. One containing grab samples from the Kali Gandaki river in its vicinities and 4 tables with time series sampling from the Kali Gandaki River and from rainfall.

Beschreibung: Methods

Beschreibung: Grab sampling: Grab samples were obtained from all hydrological compartments (spring, river, tributary, snow, ice, and rain) in the Kali Gandaki catchment and its surroundings. The samples were taken during repeated field campaigns covering all seasons during the years 2013 to 2016. Samples were filtered in the field and stored 30ml Nalgene bottles. Snow and ice samples were melted at ambient temperatures before filtering and storing. Stable water isotope time series of rainfall: Samples were collected by a local, trained station ward, during rainfall periods 2016 and 2017. Samples were recuperated always between 8 and 9 o’clock local time (GMT+5:45) if sufficient rainwater was accumulated. At both locations Lete and Kathmandu we used Palmex Rain Sampler RS1 (Gröning et al., 2012). The following isotope ratios, expressed as δ values with VSMOW as a standard, were measured: δ18O and δ2H. Stable water isotope time series of river water: Samples were collected by a local, trained station ward, between the 10th of June 2015 and October 2018 daily during the monsoon (June to Septem-ber) and bi-weekly (October to May) during the dry season. Sampling time was always between 8 and 9 o’clock local time (GMT+5:45). Samples were typically analyzed for stable water isotopic com-position with weekly resolution. The following isotope ratios, expressed as δ values with VSMOW as a standard, were measured: δ18O and δ2H. River time series samples in Purtighat were first obtained at Mirmi Hydropower Intake, upstream of the confluence with Andhi Khola from a suspension bridge in the middle of the river. The sampling location was later moved upstream to Purthighat village, roughly 10km upstream with no major tributary in between.

Beschreibung: 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). 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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. 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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). Kriosfera Zemli 13,( 2), 3-15 (in Russian). 54.Blinov, A., Alfimov, V., Beer, J., Gilichinsky, D., Schirrmeister, L., Kholodov, A., Nikolskiy, P., Opel, T., Tikhomirov, D., Wetterich, S.(2009).36Cl/Cl ratio in ground ice of East Siberia and its application for chronometry, Geochemistry, Geophysics, Geosystems (G3). 10(1), doi: 10.1029/2009GC002548. 55.Schirrmeister, L., Oezen, D., Geyh, M.A. (2002). 230Th/U dating of frozen peat, Bol'shoy Lyakhovsky Island (North Siberia), Quaternary research, 57, 253-258. doi:10.1006/qres.2001.2306. 56.Meyer, H. , Derevyagin, A. Y. , Siegert, C. and Hubberten, H. W. (2002) Paleoclimate studies on Bykovsky Peninsula, North Siberia - hydrogen and oxygen isotopes in ground ice, Polarforschung 70:, pp. 37-51 . 57.Derevyagin, A. Y., Chizhov, A. , Meyer, H. , Opel, T. , Schirrmeister, L. and Wetterich, S. (2013). Isotopic composition of texture ices, Laptev Sea coast , Kriosfera Zemlii (Earth Cryosphere), XVII (3), pp. 27-34 (in Russian). 58.Meyer, H. , Derevyagin, A. Y. , Siegert, C. , Schirrmeister, L. and Hubberten, H. W. (2002) Paleoclimate reconstruction on Big Lyakhovsky Island, North Siberia - Hydrogen and oxygen isotopes in ice wedges, Permafrost and periglacial processes, 13 , pp. 91-105 . 59.Opel, T., Dereviagin, A., Meyer, H., Schirrmeister, L., Wetterich, S. (2010).Paleoclimatic information from stable water isotopes of Holocene ice wedges at the Dmitrii Laptev Strait (Northeast Siberia), Permafrost and Periglacial Processes. 22 (1), 84-100, doi:10.1002/ppp.667. 60.Opel, T., Wetterich, S., Meyer, H., Dereviagin, A.Yu., Fuchs, M.C., and Schirrmeister, L.: Ground-ice stable isotopes and cryostratigraphy reflect late Quaternary palaeoclimate in the Northeast Siberian Arctic (Oyogos Yar coast, Dmitry Laptev Strait). Clim. Past, 13, 587–611, 2017, doi: 10.5194/cp-13-587-2017, 2017. 61.Opel, T., Murton, J. B., Wetterich, S., Meyer, H., Ashastina, K., Günther, F., Grotheer, H., Mollenhauer, G., Danilov, P. P., Boeskorov, V., Savvinov, G. N., Schirrmeister, L. (2019) Past climate and continentality inferred from ice wedges at Batagay megaslump in the Northern Hemisphere's most continental region, Yana Highlands, interior Yakutia, Clim. Past, 15, 1443–1461, doi: 10.5194/cp-15-1443-2019. 62.Ulrich, M., Grosse, G., Strauss, J. and Schirrmeister, L. (2014): Quantifying wedge-ice volumes in yedoma and thermokarst basin deposits, Permafrost and Periglacial Processes 25, 151–161. doi:10.1002/ppp.1810. 63.Grosse, G., Schirrmeister, L., Siegert, C., Kunitsky, V.V., Slagoda, E.A., Andreev, A.A., and Dereviagyn, A.Y.: Geological and geomorphological evolution of a sedimentary periglacial landscape in Northeast Siberia during the Late Quaternary, Geomorphology, 86(1/2), 25-51, doi:10.1016/j.geomorph.2006.08.005, 2007. 64.Grosse, G., Schirrmeister, L., Kunitsky, V. V., Hubberten, H. -W. (2005). The Use of CORONA Images in Remote Sensing of Periglacial Geomorphology: An Illustration from the NE Siberian Coast, Permafrost and periglacial processes, 16, 163-172. doi:10.1002/ppp.509 65.Grosse, G., Robinson, J.E., Bryant, R., Taylor, M.D., Harper, W., DeMasi, A., Kyker-Snowman, E., Veremeeva, A., Schirrmeister, L., Harden, J. (2013). Distribution of late Pleistocene ice-rich syngenetic permafrost of the Yedoma Suite in east and central Siberia, Russia. U.S. Geological Survey Open File Report 2013-1078, 37p. 66.Schennen, S., Tronicke, J., Wetterich, S., Allroggen, N., Schwamborn, G., Schirrmeister, L. (2016) 3D GPR imaging of Ice Complex deposits in northern East Siberia, Geophysics 81(1), WA185-WA192, doi: 10.1190/GEO2015-0129.1. 67.Günther, F. , Overduin, P. P. , Yakshina, I. A. , Opel, T. , Baranskaya, A. V. and Grigoriev, M. N. (2015) Observing Muostakh disappear: permafrost thaw subsidence and erosion of a ground-ice-rich island in response to arctic summer warming and sea ice reduction, The Cryosphere, 9 (1), pp. 151-178 . doi.org/10.5194/tc-9-151-2015 68.Günther, F. , Overduin, P. P. , Sandakov, A. V. , Grosse, G. and Grigoriev, M. N. (2013) Short- and long-term thermo-erosion of ice-rich permafrost coasts in the Laptev Sea region, Biogeosciences, 10 , pp. 4297-4318 . doi:https://doi.org/10.5194/bg-10-4297-2013 69.Overduin, P. P. , Strzelecki, M. C. , Grigoriev, M. N. , Couture, N. , Lantuit, H. , St-Hilaire-Gravel, D. , Günther, F. and Wetterich, S. (2013) Coastal changes in the Arctic, Geological Society of London Special Publication, 388 . doi:https://doi.org/10.1144/SP388.13 70.Strauss J., Schirrmeister L., Grosse G., Wetterich S., Ulrich M., Herzschuh U., H.-W.Hubberten (2013). The Deep Permafrost Carbon Pool of the Yedoma Region in Siberia and Alaska. GRL 40, 6165-6170. doi 10.1002/2013GL058088. 71.Strauss, J., Schirrmeister, L., Mangelsdorf, K., Eichhorn, L., Wetterich S., and Herzschuh U.: Organic matter quality of deep permafrost carbon - a study from Arctic Siberia. Biogeosciences, 12, 2227–2245, doi: 10.5194/bg-12-2227-2015, 2015. 72.Strauss,J., Schirrmeister, L., Grosse, G., Fortier, D., Hugelius, G., Knoblauch, C., Romanovsky, V., Schädel, C., Schneider von Deimling, T., Schuur, E.A.G., Shmelev, D., Ulrich, M.,, Veremeeva, A. (2017). Deep Yedoma permafrost: A synthesis of depositional characteristics and carbon vulnerability. Earth-Science Reviews 172, 75-86, doi: 10.1016/j.earscirev.2017.07.007. 73.Stapel, J. G., L. Schirrmeister, P. P. Overduin, S. Wetterich, J. Strauss, B. Horsfield, and K. Mangelsdorf (2016), Microbial lipid signatures and substrate potential of organic matter in permafrost deposits - implications for future greenhouse gas production, J. Geophys. Res. Biogeosci., 121, doi: 10.1002/2016JG003483. 74.Stapel, J.G, Schwamborn, G., Schirrmeister, L., Horsfield, B. and Mangelsdorf, K. (2018) Substrate potential of last interglacial to Holocene permafrost organic matter for future microbial greenhouse gas production. Biogeosciences, 15, 1969–1985, doi: 10.5194/bg-15-5423-2018. 75.Walz, J., Knoblauch, C., Tigges, R., Opel, T., Schirrmeister, L., and Pfeiffer, E.-M. (2018) Greenhouse gas production in degrading ice-rich permafrost deposits in northeast Siberia. Biogeosciences, 15, 5423–5436, doi: 10.5194/bg-2018-225. 76.Fuchs, M. , Grosse, G. , Strauss, J. , Günther, F. , Grigoriev, M. N. , Maximov, G. M. and Hugelius, G. (2018) Carbon and nitrogen pools in thermokarst-affected permafrost landscapes in Arctic Siberia, Biogeosciences, 15 , pp. 953-971 . 77.Kusch, S., Winterfeld, M., Mollenhauer, G., Höfle, S.T., Schirrmeister, L., Schwamborn, G., and Rethemeyer, J. (2019) Glycerol dialkyl glycerol tetraethers (GDGTs) in high latitude Siberian permafrost: Diversity, environmental controls, and implications for proxy applications. Organic Geochemistry 136, 103888, doi: 10.1016/j.orggeochem.2019.06.009. 78.Mitzscherling, J., Horn, F., Winterfeld, M., Mahler, L., Kallmeyer, J., Overduin, P.P., Schirrmeister, L., Winkel, M., Grigoriev, M.N., Wagner, D., Liebner, S. (2019) (6bial community composition and abundance after millennia of submarine permafrost warming. Biogeosciences, 16, 3941–3958, doi: 10.5194/bg-16-3941-2019. 79.Zimmermann, H.H., Raschke, E., Epp, L.S., Stoof-Leichsenring, K.R., Schirrmeister, L., Schwamborn, G., Herzschuh, U. (2017). The history of tree and shrub taxa on Bol’shoy Lyakhovsky Island (New Siberian Archipelago) since the last interglacial uncovered by sedimentary ancient DNA and pollen data. Genes 8(10), E273; doi: 10.3390/genes8100273. 80.Zimmermann, H.H., Raschke, E., Epp, L.S., Stoof-Leichsenring, K., Schwamborn, G., Schirrmeister, L., Overduin, P.P., Herzschuh, U. (2017) Sedimentary ancient DNA and pollen reveal the composition of plant organic matter in Late Quaternary permafrost sediments of the Buor Khaya Peninsula (north-eastern Siberia). Biogeosciences 14, 575-596, doi:10.5194/bg-14-575-2017

Beschreibung: Warming air temperatures, shifting hydrological regimes and accelerating permafrost thaw in the catchments of the Arctic rivers is affecting their biogeochemistry. Arctic river monitoring is necessary to observe changes in the mobilization of dissolved organic matter (DOM) from permafrost. The Lena River is the second largest Arctic river and 71% of its catchment is continuous permafrost. Biogeochemical parameters, including temperature, electrical conductivity (EC), stable water isotopes, dissolved organic carbon (DOC) and absorption by colored dissolved organic matter (aCDOM) have been measured as part of a new high-frequency sampling program in the central Lena River Delta. The results show strong seasonal variations of all biogeochemical parameters that generally follow seasonal patterns of the hydrograph. Optical indices of DOM indicate a trend of decreasing aromaticity and molecular weight from spring to winter. High-frequency sampling improved our estimated annual fluvial flux of annual dissolved organic carbon flux (6.79 Tg C). EC and stable isotope data were used to distinguish three different source water types which explain most of the seasonal variation in the biogeochemistry of the Lena River. These water types match signatures of (1) melt water, (2) rain water, and (3) subsurface water. Melt water and rain water accounted for 84% of the discharge flux and 86% of the DOC flux. The optical properties of melt water DOM were characteristic of fresh organic matter. In contrast, the optical properties of DOM in subsurface water revealed lower aromaticity and lower molecular weights, which indicate a shift toward an older organic matter source mobilized from deeper soil horizons or permafrost deposits. The first year of this new sampling program sets a new baseline for flux calculations of dissolved matter and has enabled the identification and characterization of water types that drive the seasonality of the Lena River water properties.

Beschreibung: Due to the recent and severe downtrend in sea ice coverage, Arctic-derived moisture serves as new, increasingly important, water source for the northern hemisphere. Feedback and exchange processes between the different hydrological compartments of the Arctic might be tracked by stable water isotopologues (H216O, H218O, HD16O). This is possible as evaporative sources, phase changes and transport history have a specific imprint on the isotopic compositions. The MOSAiC drift experiment offered the unique possibility to tackle the main hydrological processes occurring in the Central Arctic, covering a complete seasonal cycle, including the understudied Arctic winter. A Cavity Ring Down Spectrometer (CRDS) was installed on board of RV Polarstern and atmospheric humidity, δ18O, δD and d-excess were observed continuously from October 2019 to October 2020. Simultaneously, isotopic changes of water vapour have been measured by international partners at several land-based Arctic stations. A first analysis of the Polarstern isotopic vapour dataset reveals a range of 30‰ (min=-48.4; max=-11.4; mean=-32.4) variations in δ18Ο of atmospheric water vapour. A clear seasonal cycle with the most depleted values occurring in the dry and cold winter months and increasingly enriched values in spring, peaking in August is noticed. Strong, positive correlation is found with both local specific humidity (r2 = 0.87) and air temperature (r2=0.81). Several short-term events on synoptical time scales with abrupt fluctuations in the isotopic composition are detected throughout the entire dataset, especially during the freeze up phase (Oct-Nov) and the transition from frozen conditions to summer melt (Apr-Jun). Preliminary comparison of the Polarstern data with measurements from different Arctic stations indicates a strong influence of sea ice coverage on the isotopic signal. For an in-depth understanding of the observed isotopic changes, we quantitatively compare the measured isotopic signatures with model results from an ECHAM6 atmosphere simulation, which includes explicit water isotope diagnostics. For this simulation, pressure and temperature fields have been nudged to ERA5 data. The model-data comparison assesses the capability of this state-of-the-art AGCM to capture the first-order evaporation/condensation processes and their seasonal evolution. However, both a systematic overestimation of winter values and overall decreased variability of modeled isotope values as compared to the observation is found. Investigation of such discrepancies may help to identify deficits in the representation of the fine-scale exchange processes characterizing the central-Arctic water cycle.

Beschreibung: The diatom oxygen isotope composition (δ18Odiatom) from lacustrine sediments helps tracing the hydrological and climate dynamics in individual lake catchments, and is generally linked to changes in temperature and δ18Olake. Lake Bolshoye Shchuchye (67°53′N; 66°19′ E; 186 m a.s.l) is the largest and deepest freshwater reservoir in the Polar Urals, Arctic Russia. The diatom oxygen isotope interpretation is supported by modern (isotope) hydrology, local bioindicators such as chironomids, isotope mass-balance modelling and a digital elevation model of the catchment. The Bolshoye Shchuchye δ18Odiatom record generally follows a decrease in summer insolation and the northern hemisphere (NH) temperature history. However, it displays exceptional, short-term variations exceeding 5‰, especially in Mid and Late Holocene. This centennial-scale variability occurs roughly contemporaneously with and similar in frequency to Holocene NH glacier advances. However, larger Holocene glacier advances in the Lake Bolshoye Shchuchye catchment are unknown and have not left any significant imprint on the lake sediment record. As Lake Bolshoye Shchuchye is deep and voluminous, about 30–50% of its volume needs to be exchanged with isotopically different water within decades to account for these shifts in the δ18Odiatom record. A plausible source of water with light isotope composition inflow is snow, known to be transported in surplus by snow redistribution from the windward to the leeward side of the Polar Urals. Here, we propose snow melt variability and associated influx changes being the dominant mechanism responsible for the observed short-term changes in the δ18Odiatom record. This is the first time such drastic, centennial-scale hydrological changes in a catchment have been identified in Holocene lacustrine diatom oxygen isotopes, which, for Lake Bolshoye Shchuchye, are interpreted as proxy for palaeo precipitation and, on millennial timescales, for summer temperatures.

Beschreibung: The Arctic atmosphere has undergone a process of moistening during the past decades. The loss of sea ice has led to enhanced transfer of heat and moisture from the ocean to the lower atmosphere, while strengthening of cyclonic events has enhanced the poleward transport of moisture from lower latitudes. Eventually, the increased humidity of the Arctic air masses serves today as a new, increasingly important source of moisture for the northern hemisphere. Still, to date, the relative contributions of local evaporation versus distant-moisture sources remains uncertain, as well as the processes responsible for exchanges within and between the hydrological compartments of the Arctic. Such uncertainties limit our ability to understand the importance of the Arctic water cycle to global climate change and to project its future. In this study we use atmospheric water vapour isotopes to investigate the origin of the Arctic moisture and assess whether and which relevant changes occur within the coupled ocean-sea ice-atmosphere system (i.e., sea ice, sea water, snow, melt ponds). Stable isotopologues of water (HDO, H218O) have different saturation vapour pressures and molecular diffusivity coefficients in air. These differences lead to isotopic fractionation during each phase change of water, making water isotopes a powerful tracer of the Arctic hydrological cycle. Water vapour humidity, delta-18O, and delta-D have been measured continuously by a Picarro L2140i Cavity Ringdown Spectrometer installed onboard research vessel Polarstern during the MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition, which took place in the Central Arctic Ocean from October 2019 to September 2020. Our measurements depict a clear seasonal cycle and a strong and significant covariance of delta-18O and delta-D with air temperature and specific humidity. At the synoptic time scale the dataset is characterized by the occurrence of events associated with humidity peaks and abrupt isotopic excursions. We use statistical analysis and backwards trajectories to i) identify the origin of the air masses and the relative contributions of distant vs. locally sourced moisture, and ii) illustrate the isotopic fingerprint of these two distinct moisture contributors and discuss on the source-to-sink processes leading to their differences. Further, the MOSAiC observations are compared to an ECHAM6 simulation, nudged to ERA5 reanalysis data and enabled for water isotope diagnostics. The model-data comparison makes it possible to explore the spatial representativeness of our observations and assess whether the model can correctly simulate the observed isotopic changes. In the future, our observations may serve as a benchmark to test the parametrization of under(mis-)represented fractionation processes such as snow sublimation, evaporation from leads and melt ponds. Our study provides the very first isotopic characterization of the Central Arctic moisture throughout an entire year and contributes to disentangling the influence of local evaporative processes versus large-scale vapour transport on the Arctic moistening.

Beschreibung: Evaporation from the increasingly ice-free Arctic ocean causes moistening of the atmosphere and serves as an unprecedent water source for the Northern Hemisphere. Atmospheric transport of moisture and its interaction with the other Arctic hydrological compartments can be tracked by primary and secondary water isotope parameters. We present observations of atmospheric humidity, δ18O, δD and d-excess, obtained from a cavity-ring-down spectrometer installed on RV Polarstern and operated continuously during the MOSAiC expedition. The dataset reveals a clear seasonal cycle of the atmospheric water vapour; positive correlation is found both with local specific humidity and air temperature. The comparison of synoptical events, characterized by abrupt isotopic fluctuations, with simultaneous observations from land-based Arctic stations indicates a strong influence of sea ice coverage on the isotopic signal. For an in-depth understanding of the isotopic changes, the observations are compared to results of an isotope-enhanced ECHAM6 atmosphere simulation. The model-data comparison assesses the capability of this state-of-the-art AGCM to capture the first-order evaporation/condensation processes and their seasonal evolution. However, a systematic overestimation of winter values and overall decreased variability of modeled values is found. Investigation of such discrepancies may help to identify deficits in the representation of the fine-scale exchange processes characterizing the central-Arctic water cycle.

Beschreibung: The High Arctic is assumed to be the last reserve of a stable cryosphere. Recent publications from the Canadian High Arctic indicate, however, that changes are currently happening much faster than expected, and the future trajectory is unknown. The rate and magnitude of recent climate warming has implications for the stability of ice, especially in the far north. Moreover, air temperatures at unprecedently high levels lead to drastic retreat in sea ice extent, larger and longer ice-free shelf seas, which now may act as a “new Arctic” moisture source with clear impact on the regional hydrological and cryospheric processes. Terrestrial ice (glaciers and ice caps, ice fraction in permafrost) in the high Russian Arctic is expected to change. This terrestrial ice is a freshwater inventory on land or that has been preserved in a stable state for hundreds of years. It contains unique information about past and present climate changes which is stored in the terrestrial ice to be studied, i.e. with stable isotope methods. In this presentation, we focus on the stable hydrogen and oxygen isotopes as a unifying proxy employed for addressing cryospheric, atmospheric, marine and terrestrial research questions In the framework of the Arctic Century 2021 expedition, we addressed the hydroclimate situation of High Arctic Islands, by studying firn/ice cores from three visited ice caps. Here, Windy Ice Dome (WD, Franz-Josef-Land) and Akademii Nauk ice cap (AN, Severnaya Zemlya) have been revisited and cored after more than 20 years, now complementing earlier longer ice cores. The University ice cap (UN, Severnaya Zemlya) has been cored for the first time. Key observations were intensive near-surface melt processes inducing the percolation of meltwater, numerous thick melt layers (reaching up to 80 cm), as well as liquid water in the borehole at AN and UN ice caps complicated drilling. The ice-coring program (5 cores, 27.2 m of core) has been accompanied by snow sampling (N=126) and an extensive hydrological program including 170 sea water samples, 16 terrestrial surface waters and 31 precipitation samples. Moreover, ground ice samples were retrieved from a permafrost exposure at Severnaya Zemlya. The Arctic Century Expedition took place in August/ September 2021 and was jointly organized by the Swiss Polar Institute, the Arctic and Antarctic Research Institute, Russia and the Helmholtz Centre for Ocean Research GEOMAR in Germany.