ALBERT

Description: Field investigations were performed in four areas: a treeless mountainous tundra (16-KP-04; Lake Rauchuagytgyn area), tundra-taiga transition zone (16-KP-01, Lake Ilirney area) and a northern taiga (18-BIL-01, 18-BIL-02). In total, 39 sites were investigated. The sites were placed to cover different vegetation communities that characterise central Chukotka. Fifteen-meter radius sample plots (sites) were demarcated in the most homogeneous locations. Heterogeneity was accommodated by roughly assorting vegetation into two to three vegetation types per sampling plot. Within each area of roughly estimated vegetation types we selected one 0.5 x 0.5 m subplot for representative ground-layer above-ground biomass (ABG) harvesting (major taxa and other). For moss and lichen AGB harvesting inside 0.5 x 0.5 m subplots representative 0.1 x 0.1 m subplots were chosen. All harvested AGB samples were weighed fresh in the field. In general, AGB samples with a weight of more than 15 g were subsampled. All samples were oven dried (60 °C, 24 h for ground-layer and moss and lichen samples, 48 h for shrub and tree branch samples) and weighed again. This dataset contains the raw data of dry weight for each sub-ground vegetation type sampling plot. All data was collected by scientists from Alfred Wegener Institute (AWI), Helmholtz Centre for Polar and Marine Research and University of Potsdam, Germany, The Institute for Biological problems of the Cryolithozone, Russian Academy of Sciences, Siberian branch, and The Institute of Natural Sciences, North-Eastern Federal University of Yakutsk, Yakutsk, Russia. The AGB data calculations for the plot area including tree and tall shrubs can be found at https://doi.org/10.1594/PANGAEA.923719.

Description: Raw data acquired by position sensors on board RV Heincke during expedition HE621 were processed to receive a validated master track which can be used as reference of further expedition data. During HE621 the inertial navigation system IXSEA PHINS III and the GPS receivers Trimble Marine SPS461 and SAAB R5 SUPREME NAV were used as navigation sensors. Data were downloaded from DAVIS SHIP data base (https://dship.awi.de) with a resolution of 1 sec. Processed data are provided as a master track with 1 sec resolution derived from the position sensors' data selected by priority and a generalized track with a reduced set of the most significant positions of the master track.

Description: 85-day-long aerobic incubation of Yedoma permafrost soil from the Lena Delta into seawater from the eastern Kara Sea, at ~2°C in the dark. The setup is simulating the process of introduction of OC from eroding cost lines along the arctic cost and the resuspension in the shelf bottom waters via the later transport. Samples were incubated in a ratio of Yedoma 3mL to sea water 90 mL. Three treatments were set up 1) Yedoma+Sea water (untreated, 20 vials); 2) Yedoma+filtered Sea Water (0.2µm filter, 6 vials); 3) filtered Sea Water (0.2µm filter, 6 vials). Additionally, vials with pH and O₂ sensors were set up for each treatment: 1) 3 vials; 2) & 3) 2 vials each. Presented data include raw data of temperature, pH, oxygen concentrations, dissolved inorganic carbon concentrations (DIC) and radiocarbon signature (DI14), and sediment data (concentration and radiocarbon signature). Nutrients (NH₄, NO₂, NO₃, and PO₄), ions (Cl & SO₄), DIC, DI14C, total dissolved organic carbon (DOC), and total dissolved nitrogen (TDN) are reported normalized to the water volume in the vials. Further, parameters of the carbonate system were calculated, in order to access CO₂ release and its age signature over the cause of the experiment (carbon budget).

Description: Organic carbon (OC) stored in Arctic permafrost represents one of Earth's largest and most vulnerable terrestrial carbon pools. Amplified climate warming across the Arctic results in widespread permafrost thaw. Permafrost deposits exposed at river cliffs and coasts are particularly susceptible to thawing processes. Accelerating erosion of terrestrial permafrost along shorelines leads to increased transfer of organic matter (OM) to nearshore waters. However, the amount of terrestrial permafrost carbon and nitrogen as well as the OM quality in these deposits are still poorly quantified. Here, we characterise the sources and the quality of OM supplied to the Lena River at a rapidly eroding permafrost river shoreline cliff in the eastern part of the delta (Sobo-Sise Island). Our multi-proxy approach captures bulk elemental, molecular geochemical and carbon isotopic analyses of late Pleistocene Yedoma permafrost and Holocene cover deposits, discontinuously spanning the last ~52 ka. We show that the ancient permafrost exposed in the Sobo-Sise cliff has a high organic carbon content (mean of about 5 wt%).We found that the OM quality, which we define as the intrinsic potential to further transformation, decomposition, and mineralization, is also high as inferred by the lipid biomarker inventory. The oldest sediments stem from Marine Isotope Stage (MIS) 3 interstadial deposits (dated to 52 to 28 cal kyr BP) and is overlaid by Last Glacial MIS 2 (dated to 28 to 15 cal ka BP) and Holocene MIS 1 (dated to 7–0 cal ka BP) deposits. The relatively high average chain length (ACL) index of n-alkanes along the cliff profile indicates a predominant contribution of vascular plants to the OM composition. The elevated ratio of iso and anteiso-branched FAs relative to long chain (C ≥ 20) n-FAs in the interstadial MIS 3 and the interglacial MIS 1 deposits, suggests stronger microbial activity and consequently higher input of bacterial biomass during these climatically warmer periods. The overall high carbon preference index (CPI) and higher plant fatty acid (HPFA) values as well as high C / N ratios point to a good quality of the preserved OM and thus to a high potential of the OM for decomposition upon thaw. A decrease of HPFA values downwards along the profile probably indicates a relatively stronger OM decomposition in the oldest (MIS 3) deposits of the cliff.

Description: These data originate from 11 soil profiles sampled in northern Finland in September 2020 as part of the PeCHEc project. 8 sites were sampled on the Kutuharjue Field Research Station, a reindeer research station run by the Reindeer Herders' Association of Finland. Additional 3 sites were collected in the area around the station in the Muotkatunturi reindeer herding district as reference sites for the different landscape types found. In total, 5 sites with mineral soil (profiles with fixed volume cylinders) and 6 sites with peat (peat corer) were sampled in tundra, grassland and birch forest landscapes, covering a range of 5 different reindeer grazing intensities: a) exclosure site with no grazing (intensity 1), b) occassional migration route (intensity 2), c) regular migration route (intensity 3), d) frequent migration route (intensity 4), e) pasture (intensity 5). Analysis took place at the facilities of AWI between October 2020 and August 2021. All samples taken from the cores were analyzed for water content, bulk density, TOC, TN and δ13C. Additional radiocarbon measurements were done for selected samples of all sites. For mineral soil samples, both from mineral soil sites as well as from the bottom of the peat cores, grain size composition was determined. 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. 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: The data sets were made during the summer 2021, with samples collected from three cores, at two depths (active and permafrost layers). In total, six samples (3 replicates by samples) were incubated for 67 days at two temperatures (4°C and 20°C). Core sampling were performed during the joint Russian-German LENA 2018 expedition. The data sets were both collected at Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research and GeoForschungsZentrum Helmholtz-Zentrum, Potsdam, Germany. The aim of this study was to understand and quantify how much carbon may be lost during short-term permafrost thaw across different landscape units at the example of study area in the Lena Delta, Siberia. The study measures greenhouse gases (GHG) emissions based on an incubation experiment and focuses on relationships between GHG emissions and microbial abundance shifts during short-term permafrost thaw under anaerobic conditions. The objectives of the study were to: (1) Quantify CH4 and CO2 production during a short-term anaerobic incubation; (2) Establish relationships between CH4 and CO2 production and microbes (methanogens and methanotrophs); (3) and to identify settings and controls that drive gas production rates in thawed permafrost soils.

Description: Hyperspectral field measurements were acquired in the central Lena Delta in August 2018. The aim was to conduct spectral surface reflectance surveys of various homogeneous vegetation areas on different permafrost landforms to establish a representative spectral reflectance database. In total, we took 28 hyperspectral field measurements of 30 m x 30 m homogeneous vegetation plots across Samoylov and Kurungnakh-Island. Four plots were measured twice with a two-week delay, therefore depicting the changes on reflectance signature. We conducted the field-spectrometry measurements with the Spectral Evolution SR-2500 with a 1.5 m Fiber Optic Cable. The instrument is calibrated to a spectral radiance range of 350 to 2.500 nm. Further technical details are provided in a separate document. We identified homogeneous vegetation plots with a size of 30 m x 30 m and acquired about 100 individual spectrometry measurements, randomly scattered across the plot. At the start and at the end of each survey the system was referenced by measuring the back reflected radiance from a Zenith Lite^TM Diffuse Reflectance Target of 50% reflectivity. Hyperspectral field measurements with the plot name SAM18 were taken on Samoylov and those with KUR18 on Kurungnakh-Island. All data was collected by scientists from the Alfred Wegener Institute (AWI) Helmholtz Centre for Polar and Marine Research and University of Potsdam, Germany.

Description: Reconstructing past storm variability is essential to improving our understanding of storminess in a future changing climate. Peat sequences from coastal ombrotrophic bogs are increasingly used for this purpose, where greater quantities of coarser grained beach sand are deposited by strong winds during storm events. Moving inland however, storm intensity decreases, as does sand availability, muting potential paleostorm signals in bogs. We circumvent these issues by taking the innovative approach of using mid-infrared (MIR) spectral data, supported by elemental information, from the inorganic fraction of Store Mosse Dune South (SMDS, 57°16'37.70N, 13°55'30.86E), a 5000-year-old sequence from a large peatland located in southern Sweden. We infer past changes in mineral composition and thereby, the grain size of the deposited material. The record is dominated by quartz, whose coarse nature was confirmed through analyses of potential local source sediments. This was supported by further mineralogical and elemental proxies of atmospheric mineral inputs. Comparison of SMDS with within-bog and regionally relevant records showed that there is a difference in proxy and site response to what should be similar timing in shifts in storminess over the ~100 km transect considered. We suggest the construction of regional storm stacks, built here by applying changepoint modelling to four of the transect sites jointly. This modelling approach has the effect of reinforcing signals in common while reducing the influence of random noise. The resulting Southern Sweden-Storm Stack dates stormier periods to 4495-4290, 3880-3790, 2885-2855, 2300-2005, 1175-1065 and 715-425 cal yr BP.

Description: This collection contains four datasets on (1) chlorophyll a and phaeopigment concentrations, (2) nitrogen and organic carbon contents, (3) sediment oxygen uptakes and benthic boundary fluxes at the sediment-water interface and (4) macrofaunal abundance and biodiversity in sediments in the Canadian Arctic in 2008 and 2009. Data have been produced for a PhD thesis based on samples taken during the following expeditions: - Circumpolar Flaw Lead Study, Legs 9-10 - ArcticNet expedition 2008, Leg 11 (http://www.arcticnet.ulaval.ca/docs/2008_Amundsen_Expedition_Report.pdf) - ArcticNet expedition 2009, Leg 4 (http://www.arcticnet.ulaval.ca/docs/2009_Amundsen_Expedition_Report.pdf) - Malina expedition 2009 (Malina http://malina.obs-vlfr.fr/index.html; http://www.arcticnet.ulaval.ca/docs/2009_Amundsen_Expedition_Report.pdf) In general, sediment retrieved with a giant box corer were used to determine benthic boundary fluxes (oxygen, silicic acid, phosphate, nitrate, ammonium) in incubation chambers, as well as sediment pigment concentration from seperate cores, to study the effect of environmental conditions on benthic ecosystem functions. Parts of the data available in this collection have been analysed for addressing various ecological questions in spatial and temporal context in the publications listed below. A general description of the study region can be found in Link et al. 2013 (POne). Please download the metadata and methods file for more details.

Description: This is a compilation of all short-wave and long-wave radiation datasets from Reunion Island that were and are published in the frame of BSRN. New data will be added regularly. The data are subject to the data release guidelines of BSRN (https://bsrn.awi.de/data/conditions-of-data-release/).