Postglacial permafrost depositional history of Grøndalen, West Spitsbergen

To shed light on the postglacial landscape evolution on the western coast of Nordenskiöld Land (West Spitsbergen), drilling and outcrop sampling was performed in the framework of the Russian Scientific Arctic Expedition on Spitsbergen (RAE-S) between 2015 and 2022. The transect near Barentsburg stretches over 20 km and comprises 19 drill locations between 5 and 25 m depths below surface on the marine terraces at Isfjorden, along the Grønfjorden, in the Grøndalen and in the Iradalen. Special emphasis was given to the study of pingos. Permafrost cores were obtained with a Russian portable gasoline powered rotary drilling rig (UKB 12/25). The core pieces of 79 to 109 mm in diameter were lifted to the surface every 30–50 cm. For each core segment visible features like granulometry, color, organic content, sediment type and ice structures were described. In some of the boreholes ground temperatures were measured. Analyses of gravimetric moisture content, stable water isotope composition, and ion content of water extracts from permafrost deposits have been carried out. Further studies of grain-size distribution, mass-specific magnetic susceptibility, organic components (TOC, TC, TN, δ13C) as well as radiocarbon dating are in progress. First results of this ongoing effort have been published in recent years on pingo properties, formation and distribution (Demidov et al. 2019, 2021, 2022) and on geocryological and hydrogeological conditions (Demidov et al., 2020), while the paleo-environmental and paleo-landscape aspect is only partly studied yet (Verkulich et al., 2018) and subject to further research. As the area of West Spitsbergen became ice-free about 14 400 years ago, permafrost formation and periglacial landscape evolution covers parts of the Late Glacial and the entire Holocene. The complex interplay of glacial (e.g. retreat), periglacial (e.g. deposition) and marine (e.g. transgression) processes superimposed by climate variability over time define the local permafrost history

vPermafrost monitoring network in Barentsburg as part of Eurasian Arctic high-latitude permafrost monitoring transect

The Russian Arctic scientific expedition on Spitsbergen performs permafrost observations in Barentsburg since 2016, including as a part of the Russian-German initiative to establish a Eurasian Arctic high-latitude permafrost monitoring transect covering the Spitsbergen, Franz Josef Land, Severnaya Zemlya, Novosibirskiye Islands and Wrangel Island. The permafrost monitoring network in Barentsburg includes: (1) four temperature monitoring boreholes of the Global Terrestrial Network for Permafrost with depth up to 26 m, (2) one site of the Circumpolar Active Layer Monitoring Network (CALM) for observing the dynamics of the seasonally thawed active layer equipped with an automatic meteostation, (3) a study area for repeated morphometric and temperature observations of a group of seven pingos, (4) the periodic observation and sampling of a number of groundwater springs, ice blisters and icings, and (5) the periodic ground penetrating radar and electrical survey of glaciogenic and hydrogenic taliks. The ground temperatures at a depth of zero amplitude vary from -2.2 °C to -3.56 °C. Quaternary drill core deposits, formed according to radiocarbon analysis during the period of MIS 3 - MIS 1, have a thickness up to 40 m. In the upper parts deposits are mainly represented by gravel with structureless cryostructure. The lower parts of the core sections are built by clay with streaky cryostructures. Clays are characterized by high salt content and thus freezing temperatures between -1 and -2 °C, which makes them highly sensitive to even slight ground temperature increase. The measurements of the active layer dynamics on a CALM site showed values from 1.15 to 1.60 m with an average of 1.38 m in 2017. The upper boundary of pingos ice body was observed at the depth 1.5 – 13.0 m, thus some of them are degrading or soon will start to degrade due to propagation of 0 °C isotherm to the ice

Radiocarbon dating on four sediment profiles from Bunger Hills, East Antarctica

Radiocarbon dating was carried out on the total organic carbon of 19 lacustrine and marine sediment samples from the Bunger Hills. The results indicate that radiocarbon contamination is negligible throughout two sediment sequences from a fresh water lake. In contrast, two sequences from marine basins are irregularly influenced by the Antarctic Marine Reservoir Effect, which today amounts to more than 1000 years, depending on the degree of dilution with meltwater. All sediments were deposited during Holocene time

Geochemical signatures of pingo ice and its origin in Grøndalen, West Spitsbergen

Pingos are common features in permafrost regions that form by subsurface massive-ice aggradation and create hill-like landforms. Pingos on Spitsbergen have been previously studied to explore their structure, formation timing and connection to springs as well as their role in postglacial landform evolution. However, detailed hydrochemical and stableisotope studies of massive-ice samples recovered by drilling have yet to be used to study the origin and freezing conditions in pingos. Our core record of 20.7 m thick massive pingo ice from Grøndalen is differentiated into four units: two characterised by decreasing δ 18O and δD and increasing d (units I and III) and two others showing the opposite trend (units II and IV). These delineate changes between episodes of closed-system freezing with only slight recharge inversions of the water reservoir and more complicated episodes of groundwater freezing under semi-closed conditions when the reservoir was recharged. The water source for pingo formation shows similarity to spring water data from the valley with prevalent Na+ and HCO− 3 ions. The sub-permafrost groundwater originates from subglacial meltwater that most probably followed the fault structures of Grøndalen and Bøhmdalen. The presence of permafrost below the pingo ice body suggests that the talik is frozen, and the water supply and pingo growth are terminated. The maximum thaw depth of the active layer reaching the top of the massive ice leads to its successive melt with crater development and makes the pingo extremely sensitive to further warming

Evaluating trace element bioavailability and potential transfer into marine food chains using immobilised diatom model species Phaeodactylum tricornutum , on King George Island, Antarctica

In order to evaluate trace element bioavailability and potential transfer into marine food chains in human impacted areas of the Fildes Peninsula (King George Island, South Shetland Islands Archipelago), element levels (Cr, Ni, Cu, Zn, Cd, and Pb) were determined in water, sediments, phytoplankton, and in diatom Phaeodactylum tricornutum Bohlin (Bacillariophyceae) cells immobilised in alginate and exposed to water and sediments, from the Bellingshausen Dome (reference site) and Ardley Cove (human impacted area), during January 2014. High element concentrations in exposed P. tricornutum indicated element mobilisation from sediments into the water. Levels in exposed cells reflected the sediment element content pattern, comparable to those found in phytoplankton, supporting phytoplankton as an important path of trace element entry into marine food chains. This study clearly shows immobilised P. tricornutum as good proxy of phytoplankton concerning element accumulation efficiency, and an effective tool to monitor trace element contamination in polar coastal ecosystems

Pingo drilling reveals sodium-chloride dominated massive ice in Grøndalen, Spitsbergen

Drilling of a 21.8-m-deep borehole on top of the 10.5-m-high Nori pingo that stands at 32 m asl in Grøndalen Valley (Spitsbergen) revealed a 16.1-m-thick massive ice enclosed by frozen sediments. The hydrochemical compositions of both the massive ice and the sediment extract show a prevalence of Na+ and Cl� ions throughout the core. The upper part of the massive ice (stage A) has low mineralization and shows an isotopically closed-system trend in δ18O and δD isotopes decreasing down-core. Stage B exhibits high mineralization and an isotopically semi-open system. The crystallographic structure of Nori pingo’s massive ice provides evidence of several large groundwater intrusions that support the defined formation stages. Analysis of local aquifers leads to suggest that the pingo was hydraulically sourced through a local fault zone by low mineralized sodium–bicarbonate groundwater of a Paleogene strata aquifer. This groundwater was enriched by sodium and chloride ions while filtering through marine valley sediments with residual salinity. The comparison between the sodium–chloride-dominated massive ice of the Nori pingo and the sodium–bicarbonate-dominated ice of the adjacent Fili pingo that stands higher up the valley may serve as an indicator for groundwater source patterns of other Nordenskiöld Land pingos

Assessing trace element contamination in Fildes Peninsula (King George Island) and Ardley Island, Antarctic

King George Island, situated in the South Shetland Islands archipelago, is one of the most visited sites in Antarctica. This has contributed to a high density of scientific stations and shelters in the region, especially in Fildes Peninsula. In order to evaluate the natural and anthropogenic sources of trace elements (As, Cd, Cu, Zn, Pb and Hg) soil and moss samples were collected from different sites in January 2013. In general, the results revealed homogeneous concentrations (μg g−1) for each element in the majority of collected samples (As: 3.8 ± 1.4; Cd: 0.4 ± 0.9; Cu: 34 ± 4; Zn: 115 ± 13; Pb: 20 ± 5; Hg; 0.011 ± 0.009). However, some samples in specific areas of Fildes Bay showed the existence of local anthropogenic activities that have contributed to the enrichment of contaminants in soils and moss samples that correlated to one another (e.g. Pb: 1101 μg g−1). Human presence is linked to examples of contamination and environmental perturbation, making essential the implementation of this type of study in order to understand and protect unique places in Antarctica