ALBERT

Description: 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, 22.35 m deep, and alas basin, 19.80 m 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 (

Description: Holocene permafrost from ice wedge polygons in the vicinity of large seabird breeding colonies in the Thule District, NW Greenland, was drilled to explore the relation between permafrost aggradation and seabird presence. The latter is reliant on the presence of the North Water Polynya (NOW) in the northern Baffin Bay. The onset of peat accumulation associated with the arrival of little auks (Alle alle) in a breeding colony at Annikitisoq, north of Cape York, is radiocarbon-dated to 4400 cal BP. A thick-billed murre (Uria lomvia) colony on Appat (Saunders Island) in the mouth of the Wolstenholme Fjord started 5650 cal BP. Both species provide marine-derived nutrients (MDNs) that fertilize vegetation and promote peat growth. The geochemical signature of organic matter left by the birds is traceable in the frozen Holocene peat. The peat accumulation rates at both sites are highest after the onset, decrease over time, and were about 2-times faster at the little auk site than at the thick-billed murre site. High accumulation rates induce shorter periods of organic matter (OM) decomposition before it enters the perennially frozen state. This is seen in comparably high C∕N ratios and less depleted δ13C, pointing to a lower degree of OM decomposition at the little auk site, while the opposite pattern can be discerned at the thick-billed murre site. Peat accumulation rates correspond to δ15N trends, where decreasing accumulation led to increasing depletion in δ15N as seen in the little-auk-related data. In contrast, the more decomposed OM of the thick-billed murre site shows almost stable δ15N. Late Holocene wedge ice fed by cold season precipitation was studied at the little auk site and provides the first stable-water isotopic record from Greenland with mean δ18O of -18.0±0.8 ‰, mean δD of -136.2±5.7 ‰, mean d excess of 7.7±0.7 ‰, and a δ18O-δD slope of 7.27, which is close to those of the modern Thule meteoric water line. The syngenetic ice wedge polygon development is mirrored in testacean records of the little auk site and delineates polygon low-center, dry-out, and polygon-high-center stages. The syngenetic permafrost formation directly depending on peat growth (controlled by bird activity) falls within the period of neoglacial cooling and the establishment of the NOW, thus indirectly following the Holocene climate trends.

Description: The North Water (NOW) polynya is one of the most productive marine areas of the Arctic and an important breeding area for millions of seabirds. There is, however, little information on the dynamics of the polynya or the bird populations over the long term. Here, we used sediment archives from a lake and peat deposits along the Greenland coast of the NOW polynya to track long-term patterns in the dynamics of the seabird populations. Radiocarbon dates show that the thick-billed murre ( Uria lomvia ) and the common eider ( Somateria mollissima ) have been present for at least 5500 cal. years. The first recorded arrival of the little auk ( Alle alle ) was around 4400 cal. years bp at Annikitsoq, with arrival at Qeqertaq (Salve Ø) colony dated to 3600 cal. years bp . Concentrations of cadmium and phosphorus (both abundant in little auk guano) in the lake and peat cores suggest that there was a period of large variation in bird numbers between 2500 and 1500 cal. years bp . The little auk arrival times show a strong accord with past periods of colder climate and with some aspects of human settlement in the area.

Description: Holocene permafrost from ice wedge polygons in the vicinity of large seabird breeding colonies in the Thule District, NW Greenland, was drilled to explore the relation between permafrost aggradation and seabird presence. The latter is reliant on the presence of the North Water (NOW) polynya in the northern Baffin Bay. The onset of peat accumulation associated with the arrival of little auks (Alle alle) in a breeding colony at Annikitisoq north of Cape York is radiocarbon-dated to 4400 cal yr BP. A thick-billed murre (Uria lomvia) colony on Appat (Saunders Ø) in the mouth of the Wolstenholme Fjord started 5650 cal yr BP. Both species provide marine-derived nutrients (MDNs) that fertilise vegetation and promote peat growth. The geochemical signature of organic matter left by the birds is traceable in the frozen Holocene peat. The peat accumulation rates at both sites are highest after the onset and decrease over time and were about two-times faster at the little auk site than at the thick-billed murre site. High accumulation rates induce shorter periods of organic matter (OM) decomposition before it enters the perennially frozen state. This is seen in comparably high C / N and less depleted δ13C, pointing to a lower degree of OM decomposition at the little auk site, while the opposite pattern can be discerned at the thick-billed murre site. Peat accumulation rates correspond to δ15N trends, where decreasing accumulation led to increasing depletion in δ15N as seen in the little-auk related data. In contrast, the more decomposed OM of the thick-billed murre site shows almost stable δ15N. Late Holocene wedge ice fed by cold season precipitation was studied at the little auk site and provides the first such stable-water isotopic records from Greenland with mean δ18O of −18.0 ± 0.8 ‰, mean δD of −136.2 ± 5.7 ‰, mean d excess of 7.7 ± 0.7 ‰, and a δ18O-δD slope of 7.27, which is close to those of the modern Thule Meteoric Water Line. The syngenetic ice wedge polygon development is mirrored in testacean records of the little auk site and delineates polygon low-centre, dry-out and polygon-high-centre stages. The syngenetic permafrost formation directly depending on peat growth (controlled by bird activity) falls within the period of Neoglacial cooling and the establishment of the NOW polynya, thus indirectly follows the Holocene climate trends.

Description: These five cores were obtained from a terrestrial permafrost area in northeastern Siberia (U1: March 2019; B3, B2, B1, U3: July 2019) during the Chersky 2019 field campaign. This campaign was part of both the CACOON and the PeCHEc project and was based at the Northeast Science Station in Chersky, Sakha, Russia (RU-LAND-2019/CHERSKIY; 02.07.2019 - 19.07.2019). They were taken from the area of the Pleistocene Park experiment (Zimov, 2005; doi:10.1126/science.1113442) and cover areas of a drained thermokarst lake basin (B) as well as the adjacent Yedoma uplands (U). The cores were drilled in areas of different large herbivore impact intensities (3= intensive; 2= extensive; 1= no animal presence). The data are used in a study exermining the impact of large herbivore presence on permafrost stability, vegetation composition and ground carbon storage. The active layer was sampled excavating profiles with a spade using fixed volume cylinders on the profile wall (250 ccm). The frozen ground was sampled using a SIPRE permafrost auger with a Stihl motor. All samples taken from these cores were analyzed between January 2020 and March 2021 at the facilities of AWI. The samples were analyzed for water/ice content, water isotopes, pH, conductivity, DOC, TC, TN, TOC, δ13C, mass specific magnetic susceptibility, grain size composition and radiocarbon age. Water/ice content was derived from weight differences before and after freeze-drying the samples. Water isotope ratios (δ18O, δ2H, d excess), pH, conductivity and DOC were measured using pore water extracted from the sediment samples using Rhizone samplers. Water isotopes were measured at AWI Potsdam Stable Isotope Laboratory using a Finnigan MAT Delta-S mass spectrometer. DOC was measured at AWI Potsdam Hydrochemistry Laboratory using a Shimadzu TOC-V CPH Total Organic Carbon Analyzer. TC and TN were measured at AWI Potsdam CARLA Laboratory using a vario EL III Element Analyzer. TOC was measured at the same laboratory using a varioMAX C Element Analyzer. δ13C was measured at AWI Potsdam Stable Isotope Laboratory using a Delta V Advantage Isotope Ratio MS supplement equipped with a Flash 2000 Organic Elemental Analyzer. Mass specific magnetic susceptibility was measured using a Bartington MS-2 Magnetic Susceptibility System. Grain size composition was determined using a Malvern Mastersizer 3000 equipped with a Malvern Hydro LV wet-sample dispersion unit. Statistics were calculated for this using Gradistat 8.0. Radiocarbon dating was carried out using the Mini Carbon Dating System (MICADAS) at AWI Bremerhaven.

Description: Radiocarbon dating was carried out using the Mini Carbon Dating System (MICADAS) at AWI Bremerhaven.

Description: Water/ice content was derived from weight differences before and after freeze-drying the samples. Water isotope ratios (δ18O, δ2H, d excess), pH, conductivity and DOC were measured using pore water extracted from the sediment samples using Rhizone samplers. Water isotopes were measured at AWI Potsdam Stable Isotope Laboratory using a Finnigan MAT Delta-S mass spectrometer. DOC was measured at AWI Potsdam Hydrochemistry Laboratory using a Shimadzu TOC-V CPH Total Organic Carbon Analyzer.

Description: Mass specific magnetic susceptibility was measured using a Bartington MS-2 Magnetic Susceptibility System. Grain size composition was determined using a Malvern Mastersizer 3000 equipped with a Malvern Hydro LV wet-sample dispersion unit. Statistics were calculated for this using Gradistat 8.0.

Description: These data originate from soil samples collected on several field campaigns, aiming at identifying impacts of large herbivore activity on soil carbon storage and degradation in permafrost (northeastern Siberia (68.51 °N, 161.50 °E); campaign in July 2019) and seasonally frozen Arctic ground (northern Finland (69.15 °N, 27.00 °E); campaigns in September 2020 and June 2022). The samples were collected in transects across grazing intensity gradients, spanning over 5 different intensities: 1 - no grazing / exclosure sites (Siberia: 23 years; Finland: 50 years) 2 - occasional animal migration (Siberia: year-round; Finland: seasonal) 3 - daily animal migration (Siberia: year-round; Finland: seasonal) 4 - high-frequency daily animal migration (Siberia: year-round; Finland: seasonal) 5 - pasture / supplementary feeding sites (Siberia: year-round; Finland: seasonal) Samples cover different ground types and seasonalities, which are marked out in the site names: B - drained thermokarst basin U - Yedoma upland P - peat M - mineral soil (podsol) E - exclosure (Finland-specific) S - reindeer summer ranges W - reindeer winter ranges In this context, 'grazing' refers to any animal activity exerted by large herbivorous animals, including browsing, trampling and defecation. Values were measured following the lab procedure after Jongejans et al. (2021): 1. Lipids were extracted from the freeze-dried and homogenised samples using accelerated solvent extraction (ASE). For this, we used a ThermoFisher Scientific Dionex ASE 350, equipped with dichloromethane / methanol (DCM / MeOH 99:1 v/v) as the solvent. Samples were hold in a static phase for 20 minutes (heating for 5 minutes to 75 °C a 5 MPa). Extracts were subsequently concentrated using a Genevac SP Scientific Rocket Synergy evaporator at 42 °C. 2. Internal standards for compound quantification (5α-androstane for n-alkanes, 5α-androstan-17-one for n-alcohols) were added. 3. Asphaltenes (n-hexane-insoluble compounds) were removed by asphaltene precipitation. 4. The remaining maltene fraction was separated by medium pressure liquid chromatography (MPLC) (Radke et al. 1980) into aliphatic, aromatic and NSO (nitrogen-, sulphur- and oxygen-containing) compounds. 5. The NSO fraction was afterwards separated into acidic and neutral polar compounds applying column separation. The acidic compounds were trapped by impregnating the column with potassium hydroxide before sample addition. After washing the neutral compounds off the column using DCM, a mixture of DCM / formic acid (98:2 v/v) was added to wash the acidic compounds off the column. 6. The neutral NSO fraction, containing n-alcohols, was silyllated by adding 100 µl DCM / MSTFA (N-Methyl-N-(trimethylsilyl)trifluoroacetamide; 50:50 v/v) and heating for 60 minutes at 75 °C. 7. For measurement, we used a Thermo Scientific ISQ 7000 Single Quadrupole Mass Spectrometer with a Thermo Scientific Trace 1310 Gas Chromatograph (capillary column from BPX5, 2 mm x 50 m, 0.25 mm) with a MS transfer line temperature of 320 °C. The ion source temperature was set to 300 °C with an ionisation energy of 70 eV at 50 µA. The scan was set to the full mass spectrum (m/z 50-600 Da, 2.5 scans / second). 8. Peaks were identified and quantified in relation to the added standards using the software Xcalibur. The measurement results of n-alkanes and n-alcohols are given in µg/g(TOC) in reference to the organic carbon (OC) content of the sediment samples.