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This study aimed at isolating microorganisms associated with the mesopelagic jellyfish Periphylla periphylla collected in Irminger Sea at a depth of 325 m in July 2020. Three different solid cultivation media; Hastings, Marine agar and Wickerham media were used for the isolation of the associated microorganisms. A total of 43 bacteria were isolated from the inner and outer surfaces of the umbrella of P. periphylla, but unfortunately, no fungal strain was isolated. Isolates were further identified by Sanger sequencing of the 16S rRNA gene, and based on phylogenetic distinctiveness (differences in closest relative species according to the nucleotide BLAST), 16 bacteria belonging to 8 different genera were selected and subjected to an OSMAC cultivation regime approach using liquid and solid marine broth and glucose– yeast–malt media. After 7 days of cultivation, cultures were extracted with ethyl acetate and assessed for antimicrobial activity against fish and human pathogens. Based on antimicrobial activity assessment, four most bioactive strains; Polaribacter sp. SU124, Shewanella sp. SU126, Psychrobacter sp. SU143 and Psychrobacter sp. SU137, were prioritized for a comparative and untargeted metabolomics analysis using feature-based molecular networking. These findings highlight the biotechnological potential of P. periphylla-associated microbiota.

Here, we present internal reflection horizons (IRHs) picked in radargrams in the Dome Fuji region, Antarctica based on 22 radar profiles collected with the airborne radio-echo sounding (RES) system of the AWI mounted on its Basler BT-67 aircraft during the 2016/17 Antarctic season. 6 or 7 IRHs are traced in each radargram. The IRHs are then conneced to the Dome Fuji ice core and used to transfer the age-depth scale from the ice core to the large Dome Fuji region. The age-depth information of the IRHs are then input to a 1D ice flow model to recostruct the age field in the lower part of ice, and to evaluate basal thermal state.

Short sediment cores were taken at six stations in Wismar Bay, southern Baltic Sea (Germany) in May 2019 using a Rumohr-Lot device. Our aim in this study was to investigate the role of diagenetic element fluxes and different fresh water sources, including submarine groundwater discharge, on the water column in the bay. Porewaters were extracted from the sediment cores by applying the rhizon technique at a resolution between 2 and 5 cm. The porewaters were analyzed for major and trace metals and selected nutrients using a ICP-OES (iCAP, 7400, Duo Thermo Fischer Scientific), total sulphide by a Specord 40 spectrophotometer (Analytik Jena), dissolved inorganic carbon (DIC) and δ13CDIC using an isotope gas mass spectrometre (MAT 253) coupled to a Gasbench II, and δ18OH2O, and δ2HH2O using a CRDS system (laser cavity-ring-down-spectroscopy, Picarro L2140- I). Sediment cores were further sliced at 2 to 4 cm resolution and each freeze-dried solid subsample was analyzed for contents of total carbon, nitrogen, and sulphur using an Elemental Analyzer (Euro Vector EuroEA 3, 052), inorganic carbon using an Elemental Analyzer multi EA (Analytik Jena), total mercury by a DMA-80 analyzer, and HCl-extractable Pb, Mn and Fe using an ICP-OES (iCAP, 7400, Duo Thermo Fischer Scientific).

We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.

Permafrost is perennially frozen ground, such as soil, rock, and ice. In permafrost regions, plant and microbial life persists primarily in the near-surface soil that thaws every summer, called the ‘active layer’ (Figure 20). The cold and wet conditions in many permafrost regions limit decomposition of organic matter. In combination with soil mixing processes caused by repeated freezing and thawing, this has led to the accumulation of large stocks of soil organic carbon in the permafrost zone over multi-millennial timescales. As the climate warms, permafrost carbon could be highly vulnerable to climatic warming. Permafrost occurs primarily in high latitudes (e.g. Arctic and Antarctic) and at high elevation (e.g. Tibetan Plateau, Figure 21). The thickness of permafrost varies from less than 1 m (in boreal peatlands) to more than 1 500 m (in Yakutia). The coldest permafrost is found in the Transantarctic Mountains in Antarctica (−36°C) and in northern Canada for the Northern Hemisphere (-15°C; Obu et al., 2019, 2020). In contrast, some of the warmest permafrost occurs in peatlands in areas with mean air temperatures above 0°C. Here permafrost exists because thick peat layers insulate the ground during the summer. Most of the permafrost existing today formed during cold glacials (e.g. before 12 000 years ago) and has persisted through warmer interglacials. Some shallow permafrost (max 30–70m depth) formed during the Holocene (past 5000 years) and some even during the Little Ice Age from 400–150 years ago. There are few extensive regions suitable for row crop agriculture in the permafrost zone. Additionally, in areas where large-scale agriculture has been conducted, ground destabilization has been common. Surface disturbance such as plowing or trampling of vegetation can alter the thermal regime of the soil, potentially triggering surface subsidence or abrupt collapse. This may influence soil hydrology, nutrient cycling, and organic matter storage. These changes often have acute and negative consequences for continued agricultural use of such landscapes. Thus, row-crop agriculture could have a negative impact on permafrost (e.g. Grünzweig et al., 2014). Conversely, animal husbandry is widespread in the permafrost zone, including horses, cattle, and reindeer.

Lakes in permafrost regions are dynamic landscape components and play an important role for climate change feedbacks. Lake processes such as mineralization and flocculation of dissolved organic carbon (DOC), one of the main carbon fractions in lakes, contribute to the greenhouse effect and are part of the global carbon cycle. These processes are in the focus of climate research, but studies so far are limited to specific study regions. In our synthesis, we analyzed 2167 water samples from 1833 lakes across the Arctic in permafrost regions of Alaska, Canada, Greenland, and Siberia to provide first pan-Arctic insights for linkages between DOC concentrations and the environment. Using published data and unpublished datasets from the author team, we report regional DOC differences linked to latitude, permafrost zones, ecoregions, geology, near-surface soil organic carbon contents, and ground ice classification of each lake region. The lake DOC concentrations in our dataset range from 0 to 1130 mg L−1 (10.8 mg L−1 median DOC concentration). Regarding the permafrost regions of our synthesis, we found median lake DOC concentrations of 12.4 mg L−1 (Siberia), 12.3 mg L−1 (Alaska), 10.3 mg L−1 (Greenland), and 4.5 mg L−1 (Canada). Our synthesis shows a significant relationship between lake DOC concentration and lake ecoregion. We found higher lake DOC concentrations at boreal permafrost sites compared to tundra sites. We found significantly higher DOC concentrations in lakes in regions with ice-rich syngenetic permafrost deposits (yedoma) compared to non-yedoma lakes and a weak but significant relationship between soil organic carbon content and lake DOC concentration as well as between ground ice content and lake DOC. Our pan-Arctic dataset shows that the DOC concentration of a lake depends on its environmental properties, especially on permafrost extent and ecoregion, as well as vegetation, which is the most important driver of lake DOC in this study. This new dataset will be fundamental to quantify a pan-Arctic lake DOC pool for estimations of the impact of lake DOC on the global carbon cycle and climate change.

This study presents simulations of Greenland surface melt for the Eemian interglacial period (∼130 000 to 115 000 years ago) derived from regional climate simulations with a coupled surface energy balance model. Surface melt is of high relevance due to its potential effect on ice core observations, e.g., lowering the preserved total air content (TAC) used to infer past surface elevation. An investigation of surface melt is particularly interesting for warm periods with high surface melt, such as the Eemian interglacial period. Furthermore, Eemian ice is the deepest and most compressed ice preserved on Greenland, resulting in our inability to identify melt layers visually. Therefore, simulating Eemian melt rates and associated melt layers is beneficial to improve the reconstruction of past surface elevation. Estimated TAC, based on simulated melt during the Eemian, could explain the lower TAC observations. The simulations show Eemian surface melt at all deep Greenland ice core locations and an average of up to ∼30 melt days per year at Dye-3, corresponding to more than 600 mm water equivalent (w.e.) of annual melt. For higher ice sheet locations, between 60 and 150 mmw.e.yr-1 on average are simulated. At the summit of Greenland, this yields a refreezing ratio of more than 25 % of the annual accumulation. As a consequence, high melt rates during warm periods should be considered when interpreting Greenland TAC fluctuations as surface elevation changes. In addition to estimating the influence of melt on past TAC in ice cores, the simulated surface melt could potentially be used to identify coring locations where Greenland ice is best preserved.

In July 2017, we collected apparent resistivity data (ohm-m) in a sub-aquatic permafrost environment on the southern coastline of the Bykovsky Peninsula in northeast Siberia. The project goal was to determine the depth to the top of frozen sediment for multiple submerged landscapes. The submerged landscapes included ice-rich Yedoma permafrost, permafrost that had undergone prior thermokarst (Alases), and a former lagoon (i.e. offshore at the lagoon's coastline positions in earlier years). The data was collected with an IRIS Syscal Pro Deep Marine resistivity system that was equipped with a GPS and an echo-sounder to record water depths. The geoelectric cable had an electrode separation of 10 m and the electrodes were arranged in a reciprocal Wenner Schlumberger array. The offset between the first electrode and the boat was approximately 10 m.