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Global warming has accelerated the iodine cycle in the Arctic Ocean, amplifying its significance in the global iodine cycle. However, some intricacies of the iodine cycle in the Arctic marine environment remain unclear. In this study, we present concentrations of stable- and radio-iodine (127I and 129I) in total iodine, iodide (I–), and iodate (IO 3 –) in seawater from the Beaufort, Chukchi, and Bering Seas. Results show a wide range of 129I/127I ratios of total iodine (3.2 × 10–12–9.3 × 10–9), indicating that the total 129I/127I ratio is a valuable fingerprint for identifying water masses and comprehending mixing processes. Iodine loss in surface seawater was quantitatively assessed using 129I, revealing that Arctic rivers substantially contribute to the emission of iodine into the atmosphere from the Arctic and subarctic seas. Our redox simulation in the Arctic intermediate layer shows the concentrations and 129I/127I ratios of I– and IO 3 – during its migration and provides the first evidence of an IO 3 – reduction process masked by the I– oxidation in the intermediate Arctic Ocean. Oxidation and reduction processes in the intermediate Arctic Ocean were characterized by extremely slow rates, at 0.95–2.41 and 0.26 ± 0.13 nM/year, respectively. Our findings demonstrate the effectiveness of anthropogenic 129I in tracking iodine cycling in the Arctic marine environment. [ABSTRACT FROM AUTHOR]

The Arctic, an essential ecosystem on Earth, is subject to pronounced anthropogenic pressures, most notable being the climate change and risks of crude oil pollution. As crucial elements of Arctic environments, benthic microbiomes are involved in climate-relevant biogeochemical cycles and hold the potential to remediate upcoming contamination. Yet, the Arctic benthic microbiomes are among the least explored biomes on the planet. Here we combined geochemical analyses, incubation experiments, and microbial community profiling to detail the biogeography and biodegradation potential of Arctic sedimentary microbiomes in the northern Barents Sea. The results revealed a predominance of bacterial and archaea phyla typically found in the deep marine biosphere, such as Chloroflexi, Atribacteria , and Bathyarcheaota. The topmost benthic communities were spatially structured by sedimentary organic carbon, lacking a clear distinction among geographic regions. With increasing sediment depth, the community structure exhibited stratigraphic variability that could be correlated to redox geochemistry of sediments. The benthic microbiomes harbored multiple taxa capable of oxidizing hydrocarbons using aerobic and anaerobic pathways. Incubation of surface sediments with crude oil led to proliferation of several genera from the so-called rare biosphere. These include Alkalimarinus and Halioglobus , previously unrecognized as hydrocarbon-degrading genera, both harboring the full genetic potential for aerobic alkane oxidation. These findings increase our understanding of the taxonomic inventory and functional potential of unstudied benthic microbiomes in the Arctic. [ABSTRACT FROM AUTHOR]

Schematic diagram of the interaction between the Tibetan Plateau and the Arctic under the projected albedo reduction (darkening) over the Tibetan Plateau. In winter, the future projected darkening of the TP would trigger a stationary Rossby wave train, traveling across the Northern Hemisphere, and instigating a dipole-like surface air temperature anomaly pattern around the Arctic region. The induced Arctic warming may further generate a stationary Rossby wave train and heat the Tibetan Plateau in return, forming a bi-directional linkage between these two climate systems. [Display omitted] The Tibetan Plateau (TP) exerts a profound influence on global climate over million-year timescales due to its past uplift. However, whether the ongoing climate changes over the TP, particularly the persistent reduction in its local albedo (referred to as "TP surface darkening"), can exert global impacts remains elusive. In this study, a state-of-the-art coupled land–atmosphere global climate model has been employed to scrutinize the impact of TP darkening on polar climate changes. Results indicate that the projected TP darkening has the potential to generate a stationary Rossby wave train, thereby modulating the atmospheric circulation in the high-latitudes of the Northern Hemisphere and instigating a dipole-like surface air temperature anomaly pattern around the Arctic region. An additional experiment suggests that the projected Arctic warming may in return warm the TP, thus forming a bi-directional linkage between these two climate systems. Given their association with vast ice reservoirs, the elucidation of this mechanism in our study is crucial in advancing our comprehension of Earth system climate projections. [ABSTRACT FROM AUTHOR]

• Study using Sentinel-2 for inland Arctic bathymetry retrieval was conducted. • Bathymetry was modelled using Google Earth Engine and machine learning. • Machine learning algorithm efficacy and robustness was carefully investigated. • The Random Forest algorithm produced the most accurate results. Lakes and ponds are extensive features throughout the circumpolar region, spanning a broad range of environmental conditions which controls their hydro-ecological processes and spatiotemporal distribution. The physical characteristics of these freshwater ecosystems, including their extent and depth, are particularly responsive to climatic conditions. Thus, having the ability to efficiently map and monitor these elements is crucial as the climate continues to warm, especially over large spatial extents. In this study, satellite derived bathymetry (SDB) methods were implemented to model regional inland Arctic water depths within the open-source and cloud-based Google Earth Engine (GEE) platform. High-resolution (10 m) spectral reflectance data from Sentinel-2 was used as covariates in non-parametric and non-linear machine learning (ML) models, namely random forest (RF), support vector regression (SVR), and classification and regression trees (CART). These three ML models were also compared to a more classical and parametric multiple linear regression (MLR) model. All models were calibrated using in situ bathymetric data collected near the Toolik Field Station, in the Alaskan Arctic tundra. With such a large sample repository available, the effects of training set size, noise, and multicollinearity on model performance was comprehensively investigated. Results clearly demonstrated the superior efficacy and robustness of the RF algorithm for predicting water depths, achieving a best coefficient of determination (R2) of 0.74, mean absolute error (MAE) of 2.12 m, and root mean square error (RMSE) of 3.04 m. Overall, this study highlights the potential of advanced and flexible ML algorithms within the GEE, and demonstrates the capabilities of the polar-orbiting Copernicus Sentinel-2 satellite for this Arctic application. In the future, this ML-driven methodology can be applied using GEE's cloud infrastructure to produce updated, cost-effective, and accurate bathymetry maps over large expanses of the Arctic tundra. [ABSTRACT FROM AUTHOR]

• The first geophysical investigations on a Pomor site on Svalbard were made. • Weak anomalies related to small contrast in dielectric constant of drifts and soil. • Near-surface stratigraphy studied based on reflectors down to ca. 2 m depth. • Below the thaw depth (ca. 2 m) no reflectors are present. • An approach to tackle climate change effects on cultural heritage sites in the Arctic. With climate warming, the cultural heritage sites of the Arctic are in great danger. Extensive research is needed to study such sites. The archaeological site at Russekeila – Kapp Linné, Svalbard was selected for the survey as previous research had highlighted its vulnerability to cryospheric hazards. The main objectives of the survey were (i) to register the precise surface and subsurface locations of cultural heritage (CH) (remains of an 18th century Russian Pomor trapper's hut) objects within the study area, (ii) to determine the impact of coastal erosion on the CH objects and (iii) to understand the near-surface stratigraphy of the site. The geophysical surveys were carried out using a Ground Penetrating Radar (GPR) instrument with two shielded antennas of 500 MHz and 800 MHz centre frequencies. Only weak anomalies were observed at the intersections with wooden drifts, which can be explained by the low contrast between the relative dielectric constant values of the driftwood and the background soil. The depth extent of the driftwood within the soil was understood from the processed GPR data to a depth of approximately 25 cm. A near-surface stratigraphy of the site morphology, including thaw depth, saturated and unsaturated sediments and soil cover, was established based on multiple reflectors observed to 2 m depth. Loose sediments are indicated by reflectors to a depth of approximately 20 cm. Unsaturated fine sediments, which show a stronger signal compared to the underlying saturated sand layers, can be observed from about 1.2 m depth. No reflectors are shown below the thaw depth. [ABSTRACT FROM AUTHOR]

Conceptual model of the crustal structure of the Mendeleev Rise and adjacent area. [Display omitted] • SDR-like seismic units are typical for Alpha-Mendeleev Rise (AMR) and adjoining basins. • AMR formed as a double-sided volcanic passive continental on continental crust. • AMR formed synchronously with the adjoining basins. Data collected by several expeditions to the Arctic Ocean have yielded a seismic stratigraphic framework and basin fill history for the Alpha-Mendeleev Rise (AMR) and adjacent Podvodnikov, Makarov, North Chukchi, Toll, Mendeleev, Nautilus and Stefansson basins. The AMR comprises a double-sided volcanic passive margin formed in Aptian-Albian time. The North Chukchi, Podvodnikov, Toll, Mendeleev, Nautilus, and Stefansson basins formed synchronously with the Alpha-Mendeleev Rise as failed micro-oceanic basins. Their formation started with rifting and volcanism at ∼ 125 Ma and ended at 100–90 Ma. Ages are constrained by new isotope magmatic rock ages. The region now comprising the Amerasia Basin was in an intraplate tectonic setting during Aptian-Albian times. On the Mendeleev Rise seismic units interpreted as seaward-dipping reflectors (SDRs) form wedges separated by highs. We propose an axial line along the Mendeleev Rise that separates probable half-grabens of different polarity. On the western slope of the Rise, all bright reflections have westward dips, while on the eastern slope they have eastward dips. SDR-like seismic units are common within the adjacent basins as well. Gravity/magnetic crustal modelling for two regional seismic lines demonstrate that the Mendeleev Rise and adjacent basins are associated with stretched continental crust. [ABSTRACT FROM AUTHOR]

This study focuses on the distribution of some selected organochlorine pesticides and emerging contaminants within the surface sediments of an Arctic fjord, Kongsfjorden and nearby lakes. Organochlorine pesticides (OCPs) such as dicloran, p,p'-DDT, p,p'-DDE, p,p'-DDD were studied along with five emerging contaminants namely diuron, chlorpyrifos, dicofol, pendimethalin and bifenthrin. The highest values of OCPs recorded among the fjord and lake environments during the time of study was 0.3355 ng/g (dicloran), 0.0152 ng/g (p,p'-DDT), 0.0117 ng/g (p,p'-DDE), and 0.0137 ng/g (p,p'-DDD). Except dicofol, all other pesticides were found in both the years (2018 & 2019) with an elevated concentration during 2019. The presence of fresh as well as past input of contaminants was obtained from the values of DDTs ratio. The sediment quality guidelines of DDTs confirm that the fjord and lakes are clean to marginally polluted in which the adverse effects can rarely occur at this present juncture. • The study is on the distribution of organochlorine pesticides and emerging contaminants within the surface sediments of an Arctic fjord and lakes. • Organochlorine pesticides (OCPs) such as dicloran, p,p′-DDT, p,p′-DDE, p,p′-DDD and emerging contaminants namely diuron, chlorpyrifos, dicofol, pendimethalin and bifenthrin was studied. • The fjord and lakes are clean to marginally polluted in which the adverse effects can rarely occur. [ABSTRACT FROM AUTHOR]

This paper explores the implications of the Anthropocene and its associated planetary awareness on the concept and exercise of sovereignty, particularly through the lens of the Svalbard Treaty. The Arctic archipelago of Svalbard is not only a space undergoing rapid environmental change today, but its treaty-based governance arrangements are based on an early-twentieth century spatial imaginary of fishery, coal, and resource extraction. By examining Norway's governance shift from resource extraction to environmental stewardship on Svalbard, this paper reflects on transformations of the practice of sovereignty in response to global environmental challenges. Through interviews with local stakeholders, the research highlights the contentious nature of these shifts, revealing how increased environmental regulations, while necessary, may paradoxically entrench existing power structures and complicate the presence of non-Norwegian entities. This case study of the Svalbard Treaty serves as a normative microcosm for broader issues of sovereignty, treaty obligations, and international governance as they may evolve due to planetary change, pointing to the urgent need to rethink these evolving dynamics. The paper underscores the pressing and complex challenges facing the international system in the Anthropocene, suggesting that while Svalbard's geopolitical stability may be maintained and Norwegian sovereignty remains uncontested, the instability of global environmental realities is already leading to changes to the ways in which sovereignty is exercised in the present. [ABSTRACT FROM AUTHOR]

Microplastic pollution was studied in surface waters of Isfjorden, Svalbard in July 2021 as a part of an international regional harmonisation exercise. Surface microplastics (0.5–5 mm) were sampled with a neuston net in triplicate per study site in several branches of Isfjorden, covering populated and unpopulated fjords. High spatial variability of microplastic abundance (0–32,700 items/km2) was observed within a single fjord resulting from the hydrodynamic pattern formed through the interaction of surface currents, freshwater runoff, and wind conditions. Maximum microplastic abundance was not correlated with the distance from the local source and was instead defined by local small-scale hydrodynamics. Future recommendations for correct assessment of surface microplastics concentration in estuarine environments are presented. • High spatial variability of MP within one fjord and transfer between fjords were found. • Higher abundances of MP were uncorrelated to the distance from possible local sources. • Inner parts of fjords can act as accumulation sites for floating microplastics. • Hydrodynamic conditions must be considered when planning sample sites in estuaries. [ABSTRACT FROM AUTHOR]

Loess–palaeosol sequences serve as valuable archives of changes in climate and atmospheric mineral dust deposition. However, little work has been conducted on Holocene loess in the Arctic, despite the sensitivity of this region to climate changes. Aeolian silt/loess profiles in the ice-free region of western Greenland near Kangerlussuaq were sampled to develop a robust age framework using both luminescence and bulk organic matter radiocarbon dating. Radiocarbon ages generally show consistent age increases with depth but are likely offset to younger ages due to sediment mixing in the upper 10–20 cm of the profiles. Quartz OSL signals exhibit insensitivity, while low-temperature infrared stimulated luminescence performed at 50 °C (IR 50) and the post-IR IRSL at 180 °C (pIRIR 180) signals of polymineral fine grain revealed a consistent natural inherited dose of approximately 5 Gy for pIRIR 180 and an unbleachable residual of around 2 Gy for IR 50 , with substantial fading rates in the latter. This led to a notable age overestimation when compared with bulk organic matter radiocarbon ages. To develop an appropriate dating approach, we evaluated the differential bleaching rates of feldspar IR 50 and pIRIR 180 signals, and corrected for modern inherited doses. Radiocarbon ages measured on the bulk organic carbon oxidised at 400 °C (LT 14C) increased very consistently with depth, allowing calculation of accumulation rates. The presence of the atmospheric radiocarbon bomb signal at depth indicated down-mixing of surface material into the profile, which caused negative (younger) age offsets. The offset-corrected radiocarbon-based age-depth model could be compared to the luminescence results. We show that a combination of LT 14C with polymineral pIRIR 180 dating allows the development of age models for these deposits. This multi-chronological approach reveals that loess accumulation in the region was initiated around 4 ka, probably consisting of two main phases of loess accumulation at 4–3 ka and <1 ka. The initial phase matches the proposed onset of aeolian sand activity in the wider region, but post-dates local ice retreat by c. 3 kyr. The more recent phase of accumulation also matches the timing of increased sand accumulation in the region and likely coincides with Neoglacial to Little Ice Age ice advances, or even enhanced dust activity in the last decades. [ABSTRACT FROM AUTHOR]

As climate warms and modern technologies advance, the Artic waters may offer new opportunities for shipping, notably in the Euro-Asian Arctic. This paper presents five alternative scenarios for commercial destination and transit shipping in the region until 2050. Using a pluralistic backcasting approach to foresight, these scenarios were co-created by the authors of this paper together with thirteen experts in relevant fields from seven different countries. The scenario-building exercise integrated global and regional factors and demonstrated that the future of commercial shipping in the Arctic is subject to vast uncertainties in global politics and global development trajectory alongside the sea ice conditions and technological progress. While the current volumes of commercial shipping in the Euro-Asian Arctic are insignificant, its future will largely depend on the development of these factors and how they will interface with each other. Plausible futures of commercial shipping in the region range from extensive international transit shipping through the Northern Sea Route to restricted shipping by vessels with Arctic flags only or even no shipping, to shipping over the transpolar route. The scenarios presented here can be used to inform national policymaking as well as to support strategic decision-making within corporate entities operating in related industries. • Pluralistic backcasting led to five alternative plausible scenarios for shipping in the Euro-Asian Arctic until 2050. • Global politics, development trajectory, climate, and technology are key factors to determine the future of shipping. • Plausible futures include extensive transit through the Northern Sea Route and shipping over the Transpolar Route. • Restricted shipping, no shipping, and shipping focused on exports of resources are also plausible. • Accounting for future uncertainty is essential for robust national and corporate planning involving shipping. [ABSTRACT FROM AUTHOR]

New particle formation (NPF) significantly contributes to the number-based aerosol population in the ambient atmosphere, thereby affecting cloud formation and human health. We compared NPF characteristics, including the occurrence frequency, occurrence criteria, particle formation rate (J), and growth rate (GR) obtained from continuous measurements of the number–size distribution of particles and various gases, among different atmospheric environments (urban, agricultural (livestock and cropland), and Arctic sites). The highest NPF occurrence frequency (55%) was observed at agricultural (livestock) site (vs. urban, 45%; agricultural (cropland), 26%; Arctic, 24%). Despite the increased evaporation rate of nucleating clusters in summer, the NH 3 -rich environment (79.6 ppb) of pig and chicken farms promoted NPF. The NPF frequency at the Arctic showed a distinct seasonal pattern (high in summer and low in winter) when compared with that at the urban site (high in spring and fall and low in summer and winter). The J varied more significantly than GR among different sites, suggesting that J is more sensitive to the environment than GR. The highest GR (7.94 nm h−1) and J (2.72 cm−3 s−1) were observed at the agricultural (livestock) site, whereas the Arctic site had the lowest GR (3.34 nm h−1) and J (0.04 cm−3 s−1). The contribution of H 2 SO 4 vapor to NPF was the least in the Arctic and the highest in the urban environment. For NPF to occur, the ratio of the loss rate of condensable vapors to preexisting aerosols to their growth rate should be low, and this ratio was substantially lower in the Arctic than in the other environments. Our results underscore the complexity of NPF characteristics in different environments and highlight the interplay of various factors in governing NPF. • We compared new particle formation (NPF) characteristics at urban, agricultural, and Arctic sites. • The NPF frequency was the highest at the agricultural (livestock) site in summer. • In the Arctic, the NPF frequency showed a distinct seasonal pattern. • The L Γ threshold value, a criterion for NPF, was lower for the Arctic sites than for other sites. • Thus, NPF dynamics are complex in various environments and governed by several factors. [ABSTRACT FROM AUTHOR]

Permafrost degradation has led to increased riverine ion concentrations and export to the sea. This study uses major ion data collected in summer in 2012 and 2013 and during spring flood in 2015 to investigate the spatio-temporal variability in chemical weathering patterns and the associated CO 2 consumptions in one of the major Arctic Rivers – the Lena River and its tributaries. The catchment shows strong spatial variations in major ion concentrations in the main river and tributaries. The weathering flux represented by TIS (total inorganic solids) is calculated to be 112 Tg/yr, which is almost double that calculated in an earlier study 20 years ago for the same region. The CO 2 consumption is estimated to be 4.9 Tg C/yr, which is approximately equally shared between weathering of carbonates and silicates, despite two thirds of TIS derived from carbonates and the rest of TIS by silicates and evaporites. Our results suggest an enhanced role for silicate weathering in elemental export and CO 2 drawdown due to the ongoing transition from a near surface-dominated system towards a deep groundwater dominated system caused by permafrost degradation in the Arctic region under a warmer climate. Such an enhanced weathering pattern is also expected in other Arctic rivers; hence, a re-evaluation of the weathering budgets is clearly needed. Our findings improve our understanding of the response of the weathering regime in large Arctic river catchments to ongoing climate-driven permafrost loss, which also sheds lights into the role of land-sea element fluxes in sustaining primary production and carbon cycling on the Arctic shelf seas. [ABSTRACT FROM AUTHOR]

Mobile colistin resistance (mcr) genes are pivotal contributors to last-line of antimicrobial resistance in human infections. Shewanella , historically recognized as a natural environmental bacterium with metal reduction capabilities, recently has been observed in clinical settings. However, limited knowledge has been explored on genetic differences between strains from non-clinical and clinical strains. In this study, we conducted the whole genome sequencing on six Arctic strains, illustrated the phylogenetic relationships on published 393 Shewanella strains that categorized the genus into four lineages (L1 to L4). Over 86.4% of clinical strain group (CG) strains belonged to L1 and L4, carrying mcr-4 genes and a complete metal-reduction pathways gene cluster. Remarkably, a novel Arctic Shewanella strain in L3, exhibits similar genetic characteristics with CG strains that carried both mcr-4 genes and a complete metal reduction pathway gene cluster. It raised concerns about the transmission ability from environment to clinic setting causing in the potential infections, and emphasized the need for monitoring the emerging strains with human infections. • We found a novel Arctic Shewanella strain– Shewanella sp. B6, which belong to non-clinical group. • We also detected the mcr-4.3 gene in the Shewanella sp. B6 genome. • Shewanella sp. B 6 has both environmental tolerance and drug resistance, which need to raise concerns about the transmission ability from environment to clinic setting causing in the potential infections. [ABSTRACT FROM AUTHOR]

Mercury (Hg) is a toxic contaminant of global concern and the impact on Arctic ecosystems, particularly in seabirds, is critical due to large-scale Hg transport towards polar regions and its biomagnification in marine trophic systems. While the adverse effects of Hg on reproductive processes in seabirds are established, the understanding of Hg maternal transfer pathways and their control on Hg reproductive toxicity is limited. The combination of Hg compounds speciation (inorganic mercury and monomethylmercury MMHg) and Hg stable isotope composition in the different egg compartments (yolk, albumen, membrane, and shell) before embryo development was investigated to provide information on (i) Hg maternal transfer mechanisms, (ii) influence of egg biochemical composition on Hg organotropism and (iii) proxies of inputs of Hg contamination. Eggs of three seabird species (the common eider, the black-legged kittiwake and the little auk) collected within the same breeding period (summer 2020) in East Greenland were investigated. For all seabirds, albumen and membrane, the most protein-rich compartments, were the most contaminated (from 1.2 to 2.7 μg g−1 for albumen and from 0.3 to 0.7 μg g−1 for membrane). In these two compartments, more than 82% of the total Hg amount was in the form of MMHg. Additionally, mass-dependent fractionation values (δ 202Hg) were higher in albumen and membrane in the three species. This result was mainly due the organotropism of MMHg as influenced by the biochemical properties and chemical binding affinity of these proteinous compartments. Among the different egg compartments, individuals and species, mass-independent fractionation values were comparable (mean ± sd were 0.99 ± 0.11‰, 0.78 ± 0.11‰, 0.03 ± 0.05‰, 0.04 ± 0.10‰ for Δ199Hg, Δ201Hg, Δ200Hg and Δ204Hg, respectively). We conclude that initial MMHg accumulated in the three species originated from Arctic environmental reservoirs exhibiting similar and low photodemethylation extent. This result suggests a unique major source of MMHg in those ecosystems, potentially influenced by sea ice cover. [Display omitted] • Protein-rich egg compartments exhibited highest Hg contamination, mostly as MMHg. • MDF values likely reflected Hg organotropism for protein-rich compartments. • Odd-isotopes MIF indicated a single origin of MMHg contamination among seabirds. • Egg membranes/shells are non-invasive indicators of the source of Hg contamination. [ABSTRACT FROM AUTHOR]

• The coal phase-out, adds to Longyearbyen, Svalbard, as a place in and of change. • Imagined spatial and sociotechnical futures are mutually constitutive. • The multi-scalar dynamics of imagined futures are understudied. • Local perspectives and geopolitical ambitions are not independent from each other. • Renewed geopolitical interest shapes the role of energy transitions in the Arctic. As Longyearbyen, Svalbard, embarks on a transition away from the century-long reliance on coal as the backbone of the Arctic community, existing understandings of place are destabilised. However, as an important Norwegian outpost in an increasingly tense Arctic geopolitical landscape, the phase-out transcends local visions for Longyearbyen and its new energy system. Drawing upon a mix of semi-structured interviews, fieldwork, and desk research, this paper examines the interconnected imagined socio-spatial and sociotechnical futures through the concept of place-framing. Identifying key actors, conflicts, and place-frames, three place-frames emerged: i) the environmental, ii) the techno-economic, and iii) the social, highlighting respectively the nature, renewable technology research, development, and innovation, and the social community as potential core anchors for the future Longyearbyen after coal. The paper underlines a need to attend more closely to the multi-scalarity of such processes to better understand the what's, how's, where's, and who's of imagined futures following phase-outs. [ABSTRACT FROM AUTHOR]

The Arctic is undergoing rapid environmental change that is creating a variety of environmental, social, political, and economic challenges for the people living in this region. These changes are not limited to the Arctic, but are global, affecting weather, ecosystems, and human society at low, mid, and high latitudes. Many unresolved issues remain concerning the warming phenomenon in the Arctic, its causes, and its effects on mid-latitude regions, and these issues were addressed at the 7th International Symposium on Arctic Research (ISAR-7) held in Tokyo, Japan, from March 6–10, 2023. The symposium was broadly interdisciplinary, with particular emphasis on research in the social sciences and humanities. This special issue of ISAR-7 brings together papers that span a variety of disciplines and their linkages to promote the information and knowledge needed for the future sustainable development of the Arctic. [ABSTRACT FROM AUTHOR]

In the context of accelerated climate dynamics and uncertainties surrounding climate change research, collaborative approaches to knowledge generation are increasingly cited as a pathway needed for navigating the complexity of challenges. There is a widespread consensus that researcher-community joint expertise deepens our understanding of climatic changes. However, how this unfolds in practical settings lacks rigorous empirical support in the landscape of contemporary environmental studies. The article focuses on the intrinsic process of expert knowledge exchange and creating knowledge-in-action space for meaningful community-researcher partnerships. Addressing these issues draws upon experiences facilitating public events for diverse audiences in different countries and varying settings of scale, format and level of engagement. This account refers to the essential role of dialogue, interactivity, culturally sensitive devotion and visualization as powerful tools in building a platform for knowledge co-creation. It analyzes different ways of designing knowledge exchange that give access to a spectrum of experimentation, self-reflection and liaison with art but also requires mobilizing ethics and flexibility. [ABSTRACT FROM AUTHOR]

The Arctic region has been experiencing an extensive transformation and several economic opportunities have emerged due to the shrinking sea ice. While the Arctic Ocean has become more convenient for navigation, both Arctic and non-Arctic states have updated their Arctic policies according to recent developments. There has been a substantial increase in the number of studies studying three main Arctic sea routes: Northwest Passage (NWP), Northeast Passage (NEP), and Trans-Polar Sea Route (TSR). Albeit the existence of contradictory results, the interest in Arctic shipping presents a growing trend. The Turkish shipyards increasingly participate in tenders as well. While Çelik Tekne Shipyard stands out as the first Turkish shipyard to win the shipbuilding tender in accordance with polar conditions, a significant increase has been observed in the number of shipyards within the Arctic shipping tenders since 2018. In addition to Atlas and Akdeniz Shipyards, producing ice-class vehicles in accordance with the requirements of the Polar Code, it is possible to multiply examples from Beşiktaş Shipyard, which built ice class fuel ships, Sanmar Shipyard, which won the icebreaker tugboat tender, and Sefine and Kuzey Star Shipyards, which participated in the icebreaker tenders. Besides, the participation of Turkish shipyards as sole contractors in the Russian Arctic as of 2021 indicates their determination to become active actors in the Arctic shipping industry. Accordingly, this paper discusses the opportunities and challenges of Arctic shipping based on the Turkish case. [ABSTRACT FROM AUTHOR]

Plastic ingestion by seabirds is an increasing issue worldwide, yet species can vary in ingestion based on ecological and morphological differences. This provokes the ecological question of which species are better suited to monitor plastic ingestion across regions and time. In Canada, we examined plastic ingestion in sympatric northern fulmars (Fulmarus glacialis), black-legged kittiwakes (Rissa tridactyla), thick-billed murres (Uria lomvia), and black guillemots (Cepphus grylle). Here, we present new data and compare to historical work to inform plastic pollution monitoring in Canada. In 2021, 51 % of fulmars, 7 % of kittiwakes and 7 % of murres contained plastic, whereas guillemots had no pieces >1 mm. Regardless of the methods used to collect and process samples, fulmars continue to have low levels of ingestion compared to the European Arctic, but high levels compared to other species in the Canadian Arctic, emphasizing their continued utility as a monitoring tool for plastic pollution in Canada. [Display omitted] • We review data and present new data on plastics in four seabird species in Canada. • Plastic ingestion appears to be stable in kittiwakes, murres and guillemots. • Plastic ingestion by fulmars increased at two colonies, but remains stable in others. • Fulmars exhibit a north-south plastic gradient, with lower ingestion in the north. • Continued higher plastics in fulmars underscores their utility as a monitoring tool. [ABSTRACT FROM AUTHOR]

Plastic pollution is ubiquitous in the marine environment. Beach cleanups are considered a cost-effective mitigative measure with generally few negative environmental impacts. Beached litter is not static, however, and may wash back out to sea or be buried, meaning it is only temporarily available for cleanup. We studied deposition and turnover of litter on three Arctic beaches in Lofoten, Norway, biweekly for 31 months. The mean estimated daily deposition rate was 10 items/100 m, with a median residence time of 99 days. Both processes were impacted by seasons and weather and varied both spatially and temporally. Strong winds during the fall increased litter influx and onshore winds contributed to its loss. Heavier objects and those higher on the beach persisted longer yet were still subject to turnover. Snow temporarily buries litter but protects it in the long run. Given the turnover of litter, frequent (albeit smaller) cleanups can readily remove 3–4 times more litter from circulation in the environment than larger, infrequent cleanups. With limited resources, it is recommended to prioritise late fall cleanups. [Display omitted] • Litter deposition and resuspension monitored for 31 months on three Arctic beaches. • Mean estimated daily deposition of 10 items per day per 100 m coastline. • Median residence time of litter on the beach was 99 days. • Frequent smaller cleanups remove most litter from circulation in the environment. • In event of limited resources, it is recommended to prioritise late fall cleanups. [ABSTRACT FROM AUTHOR]

The remote and harsh environment that endemic Arctic whales (bowhead, narwhal and beluga) reside in has so far limited their exposure to many human activities. However, Arctic industrialisation coupled with increasingly accessible ice-free waters means these species increasingly co-occur, and are exposed to, a number of potentially impactful activities, many of which are directly or indirectly associated with marine vessels. We conducted a systematic map, using five search databases, to ascertain the current level of understanding relating to how Arctic whales respond to marine vessels and vessel-associated activities. We identified a limited volume of literature (n = 169), and a disparity in volume between species, subpopulations, and vessel types. Several vessel types are increasingly present in the Arctic (e.g. cruise ships, fishing vessels), yet received limited consideration. Similarly, several endangered subpopulations have received little attention. Only with sufficient understanding of the associated impacts of vessels can we develop appropriate management and mitigation measures which can effectively conserve these unique, vulnerable and inherently valuable species. [Display omitted] • Marine vessel traffic in the Arctic is increasing, and often overlaps with Arctic whale range (beluga, bowhead, narwhal). • We used a systematic map to review current knowledge of Arctic whale response(s) to vessels, and found research has been limited, and is unequal across species, stocks and vessel types. • Many endangered subpopulations have little research related to their response to vessels. • Vessel types that are increasing in the Arctic, e.g. fishing, cruise, have so far received limited research effort. • Knowledge gaps should be addressed to inform the development of proactive and adaptive vessel-related management approaches. [ABSTRACT FROM AUTHOR]

• Hydrothermal coupling model between wellbore and permafrost is established. • Hydrothermal characteristics of wellbore and formation are analyzed. • Insulation effect of main wellbore temperature-controlling techniques is studied. The abundant oil and natural gas resources in the Arctic cold regions have driven people to conduct drilling operations in these harsh environments. During drilling operations in Arctic permafrost regions, the linear heat source effect generated by the flow of drilling fluid in the wellbore continuously melts the surrounding permafrost, which can lead to wellhead settlement and instability of the wellbore wall, among other accidents. In order to provide guidance for drilling engineering in cold regions, there is an urgent need to study the coupled heat transfer between the wellbore and the permafrost in Arctic drilling. Due to the significant influence of hydrothermal coupling process in permafrost on temperature transfer, conventional wellbore heat transfer models are not suitable. Therefore, this paper proposes a hydrothermal coupling model between the wellbore and permafrost for drilling in Arctic cold regions and analyzes the heat transfer in the wellbore and the hydrothermal processes of the formation using numerical methods. By applying this model, the insulation effects of existing main wellbore temperature control and insulation technologies were studied. The main research findings indicate that drilling process can cause the permafrost around the wellbore to thaw, and the thawed permafrost around the wellbore presents a "horn" shape that expands from the wellhead to the bottom of permafrost layer; Without insulation measures, the volume of thawed permafrost around the wellbore can reach 315 m³ after 7 days of circulation; During the drilling process, moisture migration occurs. Under the effect of gravitational seepage, unfrozen water content in the thawed permafrsot around the wellbore increases from the wellhead to the bottom of the permafrsot layer; Vacuum insulated tubing has almost negligible impact on the temperature of the drilling fluid in the wellbore, while it can reduce the volume of thawed permafrost around the wellbore by 62.5 % to 88 % or even higher; Drilling fluid cooling systems can significantly lower the temperature of the drilling fluid in the wellbore but cannot effectively prevent the thawing of permafrost around the wellbore. Therefore, in practical drilling operations, priority should be given to using high-quality vacuum insulated tubing or combining both methods simultaneously. [ABSTRACT FROM AUTHOR]

Moon-photometric measurements were made at two locations in the Arctic during winter nights using two different modified Sun photometers; a Carter Scott SP02 and a Precision Filter Radiometer (PFR) developed at PMOD/WRC. Values of aerosol optical depth (AOD) were derived from spectral irradiance measurements made at four wavelengths for each of the devices. The SP02 was located near Barrow, Alaska and recorded data from November 2012 to March 2013, spanning five lunar cycles, while the PFR was deployed to Ny-Ålesund, Svalbard each winter from February 2014 to February 2019 for a total of 56 measurement periods. A methodology was developed to process the raw data, involving calibration of the instruments and normalizing measured spectral irradiance values in accordance with site-specific determinations of the extraterrestrial atmospheric irradiance (ETI) as Moon phase cycled. Uncertainties of the derived AOD values were also evaluated and found to be in the range, 0.006–0.030, depending on wavelength and which device was evaluated. The magnitudes of AOD determined for the two sites were in general agreement with those reported in the literature for sunlit periods just before and after the dark periods of Arctic night. Those for the PFR were also compared with data obtained using star photometers and a Cimel CE318-T, recently deployed to Ny-Ålesund, showing that Moon photometry is viable as a means to monitor AOD during the Arctic night. Such data are valuable for more complete assessments of the role aerosols play in modulating climate, the validation of AOD derived using various remote sensing techniques, and applications related to climate modeling. [Display omitted] • Aerosol Optical Depth (AOD) was continuosly measured at two Arctic sites during the polar night. • The Moon was used as light source for custom-modified conventional solar photometers. • Uncertainty on AOD was evaluated to be similar to the solar case. • This technique has proven to be suitable to measure night-time AOD even in the pristine Arctic. [ABSTRACT FROM AUTHOR]

• The Barents Sea is undergoing accelerated warming and sea ice loss. • Capelin and polar cod feed mainly on lipid rich sub-Arctic and Arctic zooplankton. • Atlantification alters prey composition towards more boreal species. • Significant negative relationship between capelin and mesozooplankton (1990–2022) • Predation and Atlantic water transport are key drivers of zooplankton biomass. Capelin (Mallotus villosus) and polar cod (Boreogadus saida) hold a fundamental position in the Barents Sea ecosystem as consumers of zooplankton while serving as forage fish for the commercial and ecological key species Atlantic cod (Gadus morhua). The ongoing warming and Atlantification of the Barents Sea, along with increasing net primary production, makes previously inaccessible northern areas available as feeding grounds for capelin. The opposite effect is anticipated for the ice-dependent polar cod. The transport of Atlantic water with boreal plankton from the Norwegian Sea is important for sustaining biodiversity and production in the Barents Sea. A decline of the medium-sized mesozooplankton biomass to a low level during 2016 to 2022 coincided with a strongly decreasing summer volume transport with the Atlantic Current. The low biomass of medium-sized zooplankton observed in later years raises concern about the feeding conditions now experienced by the higher trophic levels. Both capelin and polar cod feed predominantly on lipid rich sub-Arctic and Arctic zooplankton species. We found a significant inverse relationship between capelin and mesozooplankton biomass and a clear dietary shift from smaller to larger predator size. Smaller capelin (<12 cm) contained a comparatively higher proportion of copepods, dominated by Calanus glacialis, followed by C. finmarchicus and Metridia longa (copepodite stages IV-VI). As the capelin grow, their diet switches towards larger zooplankton, primarily euphausiids (mainly Thysanoessa inermis). All age groups of polar cod fed heavily on pelagic amphipods (mostly Themisto libellula) in addition to copepods and euphausiids, and to some degree also on fish, thus displaying a higher trophic position than capelin. Capelin growth from age 1 to 2 was negatively associated with their abundance at age 2, but positively related to stomach fullness for 2-year-old fish, indicating density-dependent growth. While our study reveals interactions between capelin and zooplankton, such signals between polar cod and their prey were not evident. [ABSTRACT FROM AUTHOR]

Greenland's peripheral glaciers and ice caps (GICs) contribute significant amounts of meltwater to the oceans but also affect local economies and livelihoods. Here we created multi-temporal geodetic elevation change datasets to compute mass changes for 6149 glaciers around the entire periphery of Greenland. These glaciers have lost a total of at least 276 ± 55 Gt of ice, or 0.76 ± 0.15 mm sea level equivalent, from their ablation areas between 1978 and 2015. If we assume no mass loss within accumulation areas, then the mean mass balance has been at least −0.10 ± 0.02 m w.e. yr−1. In general, west Greenland glaciers have had a more negative mass balance and experienced accelerated mass loss since 2006 (x 2.7 in south west region, x 5.6 in central west region). Conversely, east Greenland glaciers have generally experienced a decrease in the rate of mass loss. Lake-terminating glaciers have experienced the most negative mass balance, exacerbated by the occurrence of debris cover. These findings quantify great spatial heterogeneity, give context to the recent history of mass loss from GICs, and suggest the importance of including local glacier properties within glacier evolution models. • Mean mass balance of -0.1 ± 0.02 m w.e yr-1 between 1978 and 2015 (276 ± 55 Gt, 0.76 ± 0.15 mm sea level rise equivalent) • Acceleration of mass loss in west Greenland since the 1980s and deceleration in east Greenland since 2000 • Lake-terminating glaciers and debris-covered glaciers have the highest rates of mass loss [ABSTRACT FROM AUTHOR]

This study investigated the occurrence, stereoisomeric behavior, and potential sources of hexabromocyclododecanes (HBCDs) in topsoil and terrestrial vegetation from Svalbard and ocean sediment samples from Kongsfjorden, an open fjord on the west coast of Spitsbergen. The mean levels of total concentrations (Σ 3 HBCDs) were comparable to those in other remote regions and were lower than those in source regions. Elevated proportions of α-HBCD with an average of 41% in the terrestrial samples and 25% in ocean sediments compared to those in commercial products (10–13% for α-HBCD) were observed, implying isomerization from γ- to α-HBCD in the Arctic environment. In addition, the extensive deviations of enantiomeric fractions (EFs) from the racemic values reflected the effect of biotransformation on HBCD accumulation. Linear correlation analysis, redundancy analysis, and back-trajectory were combined to infer possible HBCD sources, and the results showed the important role of global production and long-range environmental transport (LRET) for the entry of HBCDs into the Arctic at an early stage. To the best of our knowledge, this study represents the first report on the diastereoisomer- and enantiomer-specific profiles of HBCDs in the Arctic terrestrial environment and sheds light on the transport pathways and environmental fate for more effective risk management related to HBCDs in remote regions. [Display omitted] • HBCD stereoisomers in Arctic soil, vegetation, and sediment were investigated. • HBCDs in the Arctic environment might undergo isomerization from γ- to α-HBCD. • Different profiles in the ocean and proglacial sediments implied source disparities. • Deviations from racemic for α-HBCD and γ-HBCD indicated secondary sources. • Plant species and biotransformation in soils affected the BCFs of HBCDs. [ABSTRACT FROM AUTHOR]

The underwater soundscape, a habitat component for Arctic marine mammals, is shifting. We examined the drivers of the underwater soundscape at three sites in the Amundsen Gulf, Northwest Territories, Canada from 2018 to 2019 and estimated the contribution of abiotic and biotic sources between 20 Hz and 24 kHz. Higher wind speeds and the presence of bearded seal (Erignathus barbatus) vocalizations led to increased SPL (0.41 dB/km/h and 3.87 dB, respectively), while higher ice concentration and air temperature led to decreased SPL (−0.39 dB/% and − 0.096 dB/°C, respectively). Other marine mammals did not significantly impact the ambient soundscape. The presence of vessel traffic led to increased SPLs (12.37 dB) but was quieter at distances farther from the recorder (−2.57 dB/log m). The presence of high frequency and broadband signals produced by ice led to increased SPLs (7.60 dB and 10.16 dB, respectively). • We analyzed acoustic datasets collected in the Amundsen Gulf from 2018 to 2019. • Wind speed (0.41 dB/km/h) was the primary driver of underwater sound. • Ice concentration (−9.8e10−4 dB/%km/h) dampened wind sound when present. • Large vessels (>100 m) increased ambient SPL by 12.37 dB on average when present. • Bearded seal vocalizations increased ambient SPLs by 3.87 dB on average when present. [ABSTRACT FROM AUTHOR]

• The real-time single-frequency precise point positioning technique was evaluated for the first time in the Arctic, and Antarctic based on real experimental data. • The ionosphere-free single-frequency precise point positioning approach was investigated for the first time in Actic and Antarctic, considering all possible auroral activities. • The ionosphere-free single-frequency precise point positioning technique is not affected by ionospheric scintillations. • The real-time ionosphere-free single-frequency precise point positioning technique can be reliably employed for real-time navigation applications both arctic and Antarctic polar regions. This contribution presents an evaluation of the positioning ability of the real-time (RT) ionosphere-free (IF) single-frequency precise point positioning (SF-PPP) technique in Arctic and Antarctic under different auroral activities. Firstly, Global Positioning System (GPS)-only observations obtained from International GNSS Service (IGS) stations in the Arctic were evaluated with RT IF SF-PPP under all possible auroral activities. Then, a series of kinematic experiments were conducted using a zodiac boat on Livingston Island, located on the Antarctic Peninsula, under different auroral activities. Observations from the kinematic experiments were also evaluated using the RT IF SF-PPP. The outcomes indicate that the IF SF-PPP approach is not affected by ionospheric activities. Furthermore, the results reveal that the RT IF SF-PPP provides dm- and m-level positioning accuracy for horizontal and vertical components, respectively. The findings demonstrate that the RT IF SF-PPP technique can be reliably employed in real-time navigation applications in the Arctic and Antarctic. [ABSTRACT FROM AUTHOR]

The accurate prediction of atmospheric polycyclic aromatic hydrocarbons (PAHs) concentrations in the Arctic is crucial in guiding the development of pollution control measures for atmospheric PAHs. However, the complex formation process and strong time-dependence of PAHs in the Arctic increase the difficulty of prediction. Herein, deep learning (DL) models were developed to predict monthly air concentrations of 16 priority PAHs at Alert monitoring station by incorporating the inherent periodicity of PAH concentrations and ancillary data including PAH emissions, meteorological information, fire emissions, and sea ice area. The prediction performance of long short-term memory (LSTM), gated recurrent unit (GRU) and bidirectional LSTM (Bi LSTM) algorithms were compared by multiple model evaluation metrics. The results showed that Bi LSTM models outperformed LSTM and GRU in predicting PAHs concentrations because it exhibited higher accuracy in terms of average R 2 ext (0.09) and errors (average MAPE ext = 1.45). The DL interpretation based on SHAP values suggested that the main drivers of PAHs concentrations were PAHs emissions and sea ice area, with a more prominent contribution from meteorological conditions. The interpretable deep learning approach provides a potential shortcut for predicting time-delayed PAHs concentrations in the Arctic, promoting the management and control of global PAHs pollution. [Display omitted] • 3 DL models developed for monthly PAHs concentration prediction in the Arctic. • Bi LSTM models that capture cyclical information was validated as the best models. • The results of SHAP assist in formulating pollution control strategies. • Meteorological conditions probably contribute most to Arctic PAHs concentrations. [ABSTRACT FROM AUTHOR]

The emergence of mining projects for rare earth elements (REEs) in response to rising global demand and geopolitical factors introduces environmental concerns, such as the suspected release of anthropogenic REEs to aquatic systems and the coexistence of radionuclides (U, Th). Northern regions confront heightened challenges from limited research and accelerated climate change. Drivers of REEs in surface waters (including George and Koroc rivers, their tributaries, and thermokarst lakes) were studied (2017–2023) in subarctic Canada within a climate transition zone, near a prospective REE mine. Dissolved REEs (<0.45 μ m) correlated positively with Al, Fe, Th, U, Cl– and DOC. A novel relationship with water temperature demonstrated an approximate 10-fold decrease in REE concentrations over the environmental gradient (2–20 ℃), suggesting complex implications for REE speciation under climate pressures. Optical analyses further predicted REEs were mobilized by humic-rich, terrestrial DOC, with correlations presenting a possible co-transport with Al, Fe and Th. Relationships for redox-sensitive Ce anomalies (Ce/Ce* = 0.18–1.2) with multi-valent trace metals (Al, Fe, Ti) and DOC were suggestive of a preferential adsorption of Ce by inorganic colloids in low-DOC systems. Findings emphasized the potential for changes in REE geochemistry with ongoing northern surface warming and vegetation shifts. [Display omitted] • First insights into REEs, U and Th in two subarctic river basins before REE mining. • Modelled field data predicted lower dissolved REEs with higher water temperatures. • REE distribution and Ce fractionation driven by colloidal Al, Fe and Ti. • Suspected co-transport of REEs, Th, Al and Fe with humic-rich terrestrial DOC. • Changes in DOM release to northern systems may alter aquatic REE geochemistry. [ABSTRACT FROM AUTHOR]

Vertical distribution of macrobenthos in sediments remains poorly studied; data from higher latitudes are especially scarce. At the same time, it is believed to contain important information about communities that should not be neglected. Hence, our main objectives are to study the peculiarities of macrobenthos vertical patterns in the Arctic and to find out features specific to this region. For this, 24 stations were sampled in 2019 aboard the R/V "Akademik Tryoshnikov" while drifting in the North Barents Sea and along a transect south-west of the Franz Joseph Land. Sediments were obtained using a box corer; afterwards, subsamples were taken by a tube corer and cut into vertical sub-cores. Three to four strata (depending on biotope) characterized by similar species composition and abundance were distinguished. No direct relation between the increase in species richness and the complication of vertical structure was found. Avoiding competition through dwelling in different layers at one station was observed in some groups of closely related species. Factors playing important roles in determining infaunal properties depended on the layer. The thin upper layer played a more important role in terms of species number and abundance as compared to lower latitudes. However, the most abundant and widespread polychaete species Spiochaetopterus typicus penetrated down to 30 cm. It formed vertical distribution patterns in deeper sediment layers at most stations, including facilitating penetration into deep layers for other species. The exception was stations dominated by large maldanid polychaetes. Such a vertical pattern, with a particularly large share of species richness and abundance concentrated in the several upper cm combined with the very deep penetration of a few species, is likely typical of the Eurasian Arctic shelf. • Three to four vertical layers (strata) differing in the infauna structure. • Different factors play significant role for invertebrates in each layer. • Close species avoid co-occurring in one sub-core, but may exchange relative position. • Increase in species diversity does not bring to complication of vertical structure. • Higher importance of the upper layer compared to lower latitudes. [ABSTRACT FROM AUTHOR]

The Arctic Cretaceous Tectonic and Igneous Mega-Province (Arctic TIMP) was active in the period 125–80 Ma. We define a TIMP as a region that is large on a global scale and experiences widespread magmatism and tectonic extension. This province has three main domains: (1) the North Atlantic with its continental rifting, (2) the High Arctic Large Igneous Province (HALIP – the Arctic Ocean and some islands), and (3) part of the Verkhoyansk-Chukotka Orogen where collapse, extension and magmatism occurred. The classical HALIP regional domain has three main elements: (1) intraplate basalt plateau traps (flood basalts), (2) areas of intraplate intrusive magmatism (dykes and sills), and (3) the Alpha-Mendeleev LIP magnetic domain. Nine magmatic seismic facies for the Alpha-Mendeleev LIP magnetic domain are recognized, including SDRs, half-grabens with SDR-like units, layered horizontal volcanic flows and large volcanic constructions. New data support the hypothesis that below all the magmatic seismic facies lies continental crust stretched on different scales and intruded by basalts. Three possible stages of HALIP-age magmatism and tectonics are recognized: (1) formation of basalt trap-type plateaus (±125–120 Ma); (2) synrift and postrift magmatism with SDR units containing both tholeiitic and alkali basalts in the Alpha-Mendeleev region along with conjugate basins (±120–100 Ma); and (3) formation of a number of large, Fedotov-type volcanic constructions in the Alpha-Mendeleev region (±100–80 Ma). At about 120 Ma orogenic collapse started in Verkhoyansk-Chukotka Orogen. The collapse was accompanied by regional uplift and magmatism. Granitoid syn-extension magmatism occurred commonly throughout the area. A large part of the land was covered by volcanics with variable compositions. Rift valleys were common. Orogenic collapse ended at about 100 Ma. The general timing of the orogenic collapse, extension, and magmatism in the Verkhoyansk-Chukotka region coincides with magmatic and tectonic events in the HALIP. The Arctic TIMP formed as a single, connected geodynamic system. [Display omitted] [ABSTRACT FROM AUTHOR]

• PVs can cover 30% of the annual electricity needs of off-grid Arctic houses. • On average, house-tailored PVs eliminate annually 1.1 tons of CO 2 per building. • Important production surplus is generated for potential exchange with microgrid. • Minimizing the Mean Squared Error affected the azimuth in PV systems design. • Best performance and diversity were obtained when maximizing solar penetration. Nunavik is a remote region in northern Quebec, Canada relying on off-grid diesel-based electricity production. In this study, photovoltaic (PV) systems for residential buildings are optimized using real electricity consumption data. The region is characterized by a significant temporal mismatch between electricity demand and PV production. Two PV systems are studied: standalone arrays and building-integrated systems (BIPV). Three multiobjective optimization problems are formulated to represent different ways to manage the demand-production mismatch, involving objectives such as the mean squared error between production and consumption, penetration of solar energy, energy gap between production and usage, and PV size. Solutions were obtained using a genetic algorithm (NSGA-II). It was found that moderately sized PV systems (60–140 m2) could cover about one third of the instantaneous electricity demand of a semi-detached house, yielding an average annual GHG emissions reduction of 1.112 ton CO 2 per house. An important surplus was found with two optimization problems, suggesting a potential for reinjection in the microgrid or batteries. Optimal designs of PV systems for both configurations were influenced by how the mismatch is managed, i.e. the choice of objective functions. The first optimization problem minimized excess energy by favoring less sunny directions, while the second and third supported energy storage or surplus reinjection, favoring south facing or vertical PVs. A robustness analysis underscored the importance of matching PV system design to consumption profiles. Ultimately, this study contributes to the emerging field of renewable energy integration in the Arctic, aiming to reduce reliance on fossil fuels. [ABSTRACT FROM AUTHOR]

Alkylated polycyclic aromatic hydrocarbons are abundant in crude oil and are enriched during petroleum refinement but knowledge of their cardiotoxicity remains limited. Polycyclic aromatic hydrocarbons (PAHs) are considered the main hazardous components in crude oil and the tricyclic PAH phenanthrene has been singled out for its direct effects on cardiac tissue in mammals and fish. Here we test the impact of the monomethylated phenanthrene, 3-methylphenanthrene (3-MP), on the contractile and electrical function of the atrium and ventricle of a polar fish, the navaga cod (Eleginus nawaga). Using patch-clamp electrophysiology in atrial and ventricular cardiomyocytes we show that 3-MP is a potent inhibitor of the delayed rectifier current I Kr (IC50 = 0.25 μM) and prolongs ventricular action potential duration. Unlike the parent compound phenanthrene, 3-MP did not reduce the amplitude of the L-type Ca2+ current (I Ca) but it accelerated current inactivation thus reducing charge transfer across the myocyte membrane and compromising pressure development of the whole heart. 3-MP was a potent inhibitor (IC50 = 4.7 μM) of the sodium current (I Na), slowing the upstroke of the action potential in isolated cells, slowing conduction velocity across the atrium measured with optical mapping, and increasing atrio-ventricular delay in a working whole heart preparation. Together, these findings reveal the strong cardiotoxic potential of this phenanthrene derivative on the fish heart. As 3-MP and other alkylated phenanthrenes comprise a large fraction of the PAHs in crude oil mixtures, these findings are worrisome for Arctic species facing increasing incidence of spills and leaks from the petroleum industry. 3-MP is also a major component of polluted air but is not routinely measured. This is also of concern if the hearts of humans and other terrestrial animals respond to this PAH in a similar manner to fish. [Display omitted] • 3-MP is a potent inhibitor of I Kr and prolongs action potential duration which is pro-arrhythmic. • Unlike phenanthrene, 3-MP does not cause reduction of I Ca amplitude. • 3-MP greatly accelerates I Ca inactivation, reducing cellular Ca2+-influx and contractile activity of the whole heart. • 3-MP is a potent inhibitor of I Na slowing conduction velocity which is pro-arrhythmic. • More robust environmental monitoring of individual PAHs will improve risk apportionment and inform mitigation policy. [ABSTRACT FROM AUTHOR]

Recent studies have identified the presence of microplastics and other anthropogenic microparticles in Arctic marine environments, but very little is known about anthropogenic microparticles in Arctic and sub-Arctic freshwater systems. Given the importance of freshwater systems to the health of northern communities, and their large input of water to the Arctic Ocean, circumpolar rivers and lakes should be considered within the context of anthropogenic microparticles in the region. Sample collections for this study were conducted in July and August of 2021 via a collaborative community-based approach. Thirty surface water samples were collected using a 300 µm Manta trawl from three sampling areas, the Yellowknife River (n = 10), Yellowknife Back Bay (n = 10), and Yellowknife Outer Bay (n = 10), to assess concentrations and transport of microplastics and other anthropogenic microparticles to Great Slave Lake, Northwest Territories. Each trawl was towed for 20-minutes, resulting in 16 to 233 m3 of water filtered per sample. Suspected anthropogenic microparticles were found in all samples, with concentrations ranging from 0.03–2.04 particles m−3, however, there were no significant differences in microparticle concentrations between sampling areas. A wide range of microparticle morphologies and colours were observed in the samples. A total of 1012 suspected anthropogenic microparticles were extracted from the surface water samples, of which fibres accounted for 87 % (n = 883), followed by fragments (11 %, n = 112), films (1 %, n = 7), and foams (1 %, n = 10). Our results indicate a widespread occurrence of microplastics and other anthropogenic microparticles in the surface waters surrounding Yellowknife, Northwest Territories. [ABSTRACT FROM AUTHOR]

The Agreement to Prevent Unregulated High Seas Fisheries in the Central Arctic Ocean (CAOFA) is a unique treaty that deals with a unique scenario: in an area of the high seas where no fishing has ever taken place, it determines the conditions under which future fishing can commence. Another innovation for which the CAOFA is less well-known are various aspects relating to Arctic Indigenous peoples. This article examines Arctic Indigenous issues relating to the CAOFA and focuses in particular on the participation of Arctic Indigenous peoples in the negotiations on the CAOFA and subsequent meetings of the CAOFA, as well as the needs of, and impacts on, Arctic Indigenous peoples as considerations in decisions by the CAOFA's Conference of the Parties (COP) on commercial and exploratory fishing. [ABSTRACT FROM AUTHOR]

The Arctic is changing rapidly due to climate change, which is allowing unprecedented levels of vessel traffic to transit the region. Vessel traffic can negatively affect marine wildlife in a number of ways, particularly in areas where vessels overlap with high concentrations of ecologically important species, and the significance of these impacts are of increased concern when the wildlife are also culturally important. Tallurutiup Imanga National Marine Conservation Area, located in Lancaster Sound, Nunavut, Canada, at the eastern entrance to the Northwest Passage, is experiencing the greatest levels of vessel traffic in the Canadian Arctic, and is important habitat for marine wildlife, including marine mammals and seabirds. Here, we examined the overlap between vessel traffic, including modeled underwater noise levels, and the distribution of two cetacean species, beluga and narwhal, and three seabird species, thick-billed murre, northern fulmar, and black-legged kittiwake. Narwhal had the highest vessel risk in Eclipse Sound and Milne Inlet, all three seabirds had high vessel risk at the eastern entrance to Eclipse Sound, with additional areas for northern fulmar at southern Devon Island and for black-legged kittiwake at Prince Leopold Island, and belugas had the highest vessel risk along southern and eastern Devon Island. Our results provide crucial information for implementing monitoring, conservation, and management initiatives for species inhabiting this protected area, and allow for a better understanding of the potential cultural implications of vessel-based marine wildlife impacts that will affect traditional subsistence hunting and local livelihoods. • Vessel traffic is increasing in the Arctic, and with it, risk to marine wildlife. • We examined risk from vessels to marine wildlife in Tallurutiup Imanga, Nunavut. • Narwhal and seabirds had highest vessel risk in Eclipse Sound and Milne Inlet. • Belugas had highest vessel risk along southern and eastern Devon Island. • Continued monitoring is needed to track risk to wildlife as vessel traffic increases. [ABSTRACT FROM AUTHOR]

The cost-effectiveness of six Arctic route alternatives, including the Arctic routes likely to be opened in far future due to ice melting faster than expected stemming from the global warming, and current Suez and Panama Canal routes are analyzed for shipping between Asian and European ports. Eleven different size, fully loaded real container ships' single transit voyage from Shanghai to Rotterdam on eight alternative routes at different sea conditions, without interim port calls enroute are studied. A basic cost, revenue and profit empirical calculation model is applied first with near-term data to provide input for FAHP. Then, to evaluate cost-effectiveness and profitability of the routes under a multi-criteria decision environment, Fuzzy Analytic Hierarchy Process (FAHP) is applied as a tool to obtain refined results. For the predictions of transportation sector and shipbuilding industries, it is shown that the Central Arctic Ocean and Northwest Passage routes may become cost-effective for transit voyages between Asia and Europe ports in a few decades. • Arctic shipping market emerges due to global warming and climate change. • Cost-effectiveness and profitability of six current and future Arctic, two international shipping routes are compared. • Eleven container ships' voyage cost, revenue and profit are analyzed and compared. • Fuzzy Analytic Hierarchy Process (FAHP) is used in cost-effectiveness analyzes. • Most recent data as of 2020 are used. [ABSTRACT FROM AUTHOR]

Objectives: Soldier performance in the Arctic depends on planning and training, protective equipment, and human physiological limits. The purpose of this review was to highlight the span of current research on enhancing soldier effectiveness in extreme cold and austere environments.Methods: The practices of seasoned soldiers who train in the Arctic and cold-dwelling natives inform performance strategies. We provide examples of research and technology that build on these concepts.Results: Examples of current performance research include evaluation of equipment and tactics such as the bioenergetics of load carriage over snow in Norwegian exercises; Canadian field monitoring of hand temperatures and freezing cold injuries for better protection of manual dexterity; and Dutch predictive modeling of cold-wet work tolerances. Healthy young men can respond to cold with a substantial thermogenic response based on US and Canadian studies on brown adipose tissue and other mechanisms of non-shivering thermogenesis; the potential advantage of greater fat insulation is offset in obese unfit subjects by a smaller thermogenic response. Current physiological studies are addressing previously unanswered problems of cold acclimation procedures, thermogenic enhancement and regulation, and modulation of sympathetic activation, all of which may further enhance cold survival and expand the performance envelope.Conclusion: There is an inseparable behavioral component to soldier performance in the Arctic, and even the best equipment does not benefit soldiers who have not trained in the actual environment. Training inexperienced soldiers to performance limits may be helped with personal monitoring technologies and predictive models. [ABSTRACT FROM AUTHOR]

Since 2010, the CryoSat-2 satellite mission has enabled to largely improve sea ice freeboard estimations. But due to the complexity of radar echoes over sea ice, freeboard retrieval from altimetry still presents some errors and biases that further limit the potential of these observations for climate studies or for assimilation into models. Various methods have been explored, producing a large range of freeboard estimations. In this study, we analyze the main steps of the radar freeboard computation developed as part of the Cryo-SeaNice Project. The objective is to quantify the impacts of each processing method and to identify optimal strategies to improve freeboard estimations from SAR altimetry measurements. We consider two SAR processing options: the Hamming Window (HW) and with the Zero-Padding (ZP), and 2 retrackers: the Threshold First Maximum Retracker Algorithm (TFMRA) based on heuristic measurements and SAMOSA+ a retracker declined from model based analysis of the surface back-scatter. Four freeboard solutions are generated from combinations of the 2 processing options (HW and ZP or ZP only) and the 2 types of retrackers. In addition, an alternative to the Hamming Window method to filter out side-lobes errors is presented. The impacts of the different approaches to estimate freeboard are quantified from comparisons with Operation Ice Bridge (OIB) and the Beaufort Gyre Exploration project (BGEP) in situ data. Our results show that SAMOSA+ provides more precise freeboard estimations. This new time-series is available on CTOH website. We also identified some impacts of the Hamming Window for both retrackers. Finally, we present the potential of using the simpler threshold retracker but with a correction to account for the surface roughness that is calibrated against SAMOSA+. [ABSTRACT FROM AUTHOR]

As one of the most remote and inaccessible regions in the world, the sea level in the Arctic is still today in large parts uncertain. Sea level estimates from GRACE and satellite altimetry show disagreements in areas of the Arctic while only few in-situ measurements are present to validate satellite products. By using an independent in-situ based dataset of hydrographic data (DTUSteric), this study compares different available datasets from GRACE and altimetry. The best agreement (R = 0.76) is reached between the combination of DTUSteric and the JPL Mascon solution and the altimetry product from Centre of Polar Observation and Modelling (CPOM). A large residual signal is found in the East Siberian Sea, an area with no in-situ observations and in general uncertain satellite observations. The spatial correlation coefficients ranging from 0.32 to 0.76 reflects a large number of unknowns and uncertainties, with coarse GRACE resolution, extensive interpolation and lack of in-situ data in parts of the Arctic Ocean and uncertainty of the altimetric products being the largest sources of error. In general, we recommended that satellite observations are used carefully in the Arctic. Even this study shows that steric estimates from in-situ observations to some extent can explain the gap between GRACE and altimetry, the observed sea level trend in significant regions of the Arctic cannot be validated with in-situ hydrographic data. [ABSTRACT FROM AUTHOR]

An aerosol electrical mobility spectrum analyzer (AEMSA), developed at Hanyang University, was employed to investigate the particle charge characteristics in the Antarctic and Arctic regions. The particle charge characteristics in these areas were compared with the charging state in Ansan, South Korea, located in the midlatitude, where artificial factors, such as human activity, urbanization, and traffic, might result in a higher total concentration. Furthermore, in Ansan, South Korea, the charged-particle polarity ratio was very stable and was close to 1. However, notably different particle charge characteristics were obtained in the Antarctic and Arctic regions. The imbalance between the numbers of positively and negatively charged particles was evident, resulting in more positive charges on the atmospheric particles. On average, the positively charged particle concentrations in the Antarctic and Arctic areas were 1.4 and 2.8 times higher, respectively, compared with the negatively charged particles. The developed AEMSA system and the findings of this study provide useful information on the characteristics of atmospheric aerosols in the Antarctic and Arctic regions and can be further utilized to study particle formation mechanisms. [Display omitted] [ABSTRACT FROM AUTHOR]