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Number of results: 925
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Abstract

A filamentous benthic cyanobacteria, strain USMAC16, was isolated from the High Arctic Svalbard archipelago, Norway, and a combination of morphological, ultrastructural and molecular characterisation (16S rRNA gene sequence) used to identify to species level. Cell dimensions, thylakoid arrangement and apical cell shape are consistent with the Pseudanabaena genus description. The molecular characterisation of P. catenata gave 100% similarity with Pseudanabaena catenata SAG 1464-1, originally reported from Germany. Strain USMAC16 was cultured under a range of temperature and photoperiod conditions, in solid and liquid media, and harvested at exponential phase to examine its phenotypic plasticity. Under different culture conditions, we observed considerable variations in cell dimensions. The longest cell (5.91±0.13 μm) was observed at 15°C under 12:12 light:dark, and the widest cell (3.24±0.06 μm) at 4°C under 12:12 light: dark in liquid media. The study provides baseline data documenting the morphological variation of P. catenata in response to changing temperature regimes.
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Abstract

It is assumed that close to the margins of ice-sheets, glacial, fluvial and aeolian processes overlap, and combined with weathering processes, produce numerous sediments, in which quartz is a common mineral. Quartz grains, if available, may serve as a powerful tool in determining the depositional history, transportation mode and postdepositional processes. However, quartz grain studies in some modern glacial areas are still sparse. In this study, we examine for the first time quartz grains sampled from the modern glacial and proglacial environments of the Russell Glacier, southwest Greenland in binocular microscope and scanning electron microscope, to analyze their shape, character of surface and microtextures. We debate whether the investigated quartz grains reveal glacial characteristics and to what extent they carry a signal of another transportation and sedimentary processes. Although glacial fracturing and abrasion occur in grain suites, most mechanical origin features are not of a high frequency or freshness, potentially suggesting a reduced shear stress in the glacier from its limited thickness and influence of the pressurized water at the ice-bed. In contrast, the signal that originates from the fluvial environment is much stronger derived by numerous aqueous-induced features present on quartz grain surfaces. Aeolian-induced microtextures on grain surfaces increase among the samples the closest to the ice margin, which may be due to enhanced aeolian activity, but are practically absent in sediments taken from the small scale aeolian landforms. In contrast, aeolian grains have been found in the bigger-size (1.0-2.0 mm) investigated fraction. These grains gained the strongest aeolian abrasion, possibly due to changes in transportation mode.
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Abstract

The specific activity of natural gamma emitters like actinium (228Ac), bismuth (212Bi, 214Bi), lead (212Pb, 214Pb), potassium (40K), radium (224Ra), thallium (208Tl) and artificial radioisotope caesium (137Cs) was measured in 2005 in the surface layer of marine sediments in the northern Svalbard: Wijdefjorden, Woodfjorden, Vestfjorden and Bockfjorden as well as in the freshwater reservoirs in Andre Land. Nonuniform spatial distribution of these radionuclides was found. Sediment sample from Bockfjorden had the highest specific activities of all natural radionuclides. The specific radioactivity of 137Cs was much lower than specific radioactivities of natural radionuclides but there were differences between investigated locations. The distribution of 137Cs is similar to persistent organic pollutants of the lake sediments in the area.
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Abstract

Textural properties and microstructures are commonly used properties in the analysis of Pleistocene and older glacial deposits. However, contemporary glacial deposits are seldom studied, particularly in the context of post-depositional changes. This paper presents the results of a micromorphological study of recently deposited tills in the marginal zones of Hansbreen and Torellbreen, glaciers in southwestern Spitsbergen. The main objectives of this study were to compare modern tills deposited in subglacial and supraglacial conditions, as well as tills that were freshly released from ice with those laid down several decades ago. The investigated tills are primarily composed of large clasts of metamorphic rocks and represent coarse-grained, matrix-supported diamictons. The tills reveal several characteristic features for ductile (e.g. turbate structures) and brittle (e.g. lineations, microshears) deformations, which have been considered to be indicative of subglacial conditions. In supraglacial tills, the same structures are common as in the subglacial deposits, which points to the preservation of the primary features, though the sediment was transferred up to the glacier surface due to basal ice layer deformation and redeposited as slumps, or to formation of similar structures due to short-distance sediment re-deposition by mass flows. This study revealed that it might not be possible to distinguish subglacial and supraglacial tills on the basis of micromorphology if the latter are derived from a subglacial position. The only noted difference was the presence of iron oxide cementation zones and carbonate dissolution features in supraglacial tills. These features were found in tills that were deposited at least a few years ago and are interpreted to be induced by early post-depositional processes involving porewater/sediment interactions.
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Abstract

A two-year-long data set of air temperature from four different altitudes above Petuniabukta, central Spitsbergen, was analysed in order to assess the near-surface temperature lapse rates and the relative frequency of air temperature inversion occurrence. From August 2013 to July 2015, air temperatures at adjacent altitudes in Petuniabukta were strongly correlated. The near-surface lapse rates in all three layers differed significantly both from the average lapse rate in the international standard atmosphere (0.65°C 100 m-1) and the lapse rate calculated by linear regression. A pronounced annual cycle was detected in the lowermost air layer (from 23 to 136 m a.s.l.) with a variable near-surface lapse rate in the winter months, while an annual cycle was not apparent in the air layers above 136 m a.s.l. The lowermost layer was also characterized by a notable daily cycle in near-surface lapse rate in spring and autumn. Air temperature inversions occurred in up to 80% of the study period in the air layer below 136 m a.s.l., with the relative frequency being much lower in the other two air layers. The air temperature inversions lasted as long as 139 hours. A case study revealed that one of the strongest air temperature inversions was connected to an area of lower pressure gradients at the 850-hPa pressure level.
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Abstract

This paper presents a unique case study and methodology for measurements of the bedload transport in the two, newly created troughs at the forefield of the Baranowski Glacier: Fosa and Siodło creeks. The weather conditions and the granulometric analysis are presented and discussed briefly. Rating curves for the Fosa and Siodło creeks are presented for the first time for this region. Changes of the bedload transport as well as water discharge and water velocity at both creeks are investigated. The hysteresis for the relationships between rate of bedload transport and water discharges were identified showing that for both creeks for the higher water levels a figure of eight loop may be easily recognized. Moreover, a new method for the calculation of bedload transport rate, based on the weighted arithmetic mean instead of the arithmetic mean, is proposed.
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Abstract

It is generally accepted that ice cores archive amount-weighted water stable isotope signals. In order to achieve an improved understanding of the nature of water stable isotope signals stored in ice cores annual δ18O and δ2H averages (i.e. amount-weighted) were calculated for two Antarctic meteorological stations, Vernadsky and Hal-ley Bay, using monthly precipitation amount and monthly net accumulation as weights, respectively. These were then compared with the annual mean δ18O δ2H and records of the nearest available ice cores. In addition, at the stations, both arithmetic means (i.e. time-weighted) and amount-weighted (precipitation amount and net accumulation used as weights) annual air temperature averages were calculated and then compared to amount weighted annual mean δ18O and δ2H using correlation- and regression analyses. The main hypothesis was that amount weighted annual mean water isotope and temperature records from the stations would be able to replicate the annual water isotope signal stored in ice cores to a higher degree. Results showed that (i) amount weighting is incapable of ameliorating the signal replication between the stations and the ice cores, while arithmetic means gave the stronger linear relationships; (ii) post depositional processes may have a more determining effect on the isotopic composition of the firn than expected; and (iii) mean annual air temperature provided the closest match to ice core derived annual water isotope records. This latter conveys a similar message to that of recent findings, in as much as ambient temperature, via equilibrium isotope fractionation, is imprinted into the uppermost snow layer by vapor exchange even between precipitation events. Together, these observations imply that ice core stable water isotope records can be a more continuous archive of near-surface temperature changes than hitherto believed.
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Abstract

Unique and independent historical observations, carried out in the central Arctic during the early twentieth century warming (ETCW) period, were used to evaluate the older (20CRv2) and newer (20CRv2c) versions of the 20th Century Reanalysis and the HIRHAM5 regional climate model. The latter can reduce several biases compared to its forcing data set (20CRv2) probably due to higher horizontal resolution and a more realistic cloud parameterization. However, low-level temperature and near-surface specific humidity agree best between 20CRv2c and the surface-based observations. This better performance results from more realistic lower boundary conditions for sea ice concentration and sea surface temperature, but it is limited mainly to polar night. Although sea level pressures are very similar, the vertical stratification and baroclinicity change in the transition from 20CRv2 to 20CRv2c. Compared to observed temperature profiles, the systematic cold bias above 400 hPa remains almost unchanged indicating an incorrect coupling between the planetary boundary layer and free troposphere. In addition to surface pressures, it is therefore recommended to assimilate available vertical profiles of temperature, humidity and wind speed. This might also reduce the large biases in 10 m wind speed, but the reliability of the sea ice data remains a great unknown.
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Abstract

The aim of this research was to study the biodiversity of cyanobacteria and microalgae in hydro-terrestrial habitats from the area of Hornsund fjord (Svalbard archipelago). This research is particularly important, because hitherto no complex research (including all taxonomic groups) has previously been conducted on the cyanobacterial and microalgal flora in Arctic water ecosystems. The research was conducted during the summer seasons of 2011 and 2013. Shannon’s diversity index was used to describe species diversity and evenness. Data on cyanobacteria and microalgae were analyzed using the MVSP and PCA. Additionally, a basic analysis of the physicochemical properties of water in the studied ecosystems was performed. A total of 506 taxa were noted in the studied hydro-terrestrial habitats. The most numerous group was cyanobacteria, constituting 35% of all recorded taxa. Ochrophyta and Chlorphyta were almost equally numerous (percentage again as for cyanobacteria). Nineteen types of assemblages were noted in all studied hydro-terrestrial habitats. The diversity of cyanobacteria and microalgae and the assemblages formed by them were used to determine the characteristics of the studied ecosystems. Each type of water ecosystem was represented by specific phycoflora and assemblages. Ecological parameters along with biological data (the diversity of cyanobacteria and microalgae) allowed us to sort the studied hydro-terrestrial habitats by similarity. Our analyses clearly distinguished water ecosystem groups differing in species composition determining their trophic status. The research shows the usefulness of cyanobacteria and microalgae diversity defined by the Shannon-Weaver index for characterizing bodies of water and determining the trophic status of these habitats.
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Abstract

Beach pollution is one of the most common hazards in present-day anthropogenic environments. Even in the remote Svalbard Archipelago, pollution impacts the beach system and can pose environmental threats. The significant increase in human activity observed in Svalbard over the last 20–30 years has resulted in a visible change in the amount of coastal pollution. A 5 km long transect of modern beach developed along Calypsostranda (Recherchefjorden, Bellsund) was surveyed in the summer of 2015 in order to characterize the beach pollution. During the survey 296 pieces of trash were found on beach surface. 82% of found trash was plastic, followed by glass (8%), and metal (5%). The comparison with previous pollution survey showed the significant increase of plastic waste in local beach environment. Similar problem has been recently recorded in other parts of Svalbard suggesting an urgent need for coastal pollution monitoring.
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Abstract

Usnea aurantiaco-atra is the dominant flora around King George Island, Antarctica, whose specimens exhibited various phenotypes, even for those with the same ITS sequences in both mycobiont and photobiont. A comprehensive analysis of morphological traits of U. aurantiaco-atra including the reproductive structures, growth forms and ornamentation, cross section of the branches, and the substratum was carried out. Four arbitrary groups were identified based on their reproductive characters, but these groups cannot be distinguished from molecular phylogenetic trees based on fungal or algal ITS sequences. Further, the complicated morphological diversity of the thalli with the same ITS haplotypes in both mycobiont and photobiont suggest that some other factors in addition to the symbionts could influence the morphology of lichens. This implies that lichen is indeed a complex-mini-ecosystem rather than a dual symbiotic association of fungus and alga. Also, a lichenous fungi Phacopsis sp. was identified based on its anatomical characters and ITS sequence, which was also responsible for the black burls-like structures on U. aurantiaco-atra.
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Abstract

The Antarctic Peninsula region has experienced a recent cooling for about 15 years since the beginning of the 21st century. In Livingston Island, this cooling has been of 0.8°C over the 12-yr period 2004–2016, and of 1.0°C for the summer average temperatures over the same period. In this paper, we analyse whether this observed cooling has implied a significant change in the density of the snowpack covering Hurd and Johnsons glaciers, and whether such a density change has had, by itself, a noticeable impact in the calculated surface mass balance. Our results indicate a decrease in the snow density by 22 kg m-3 over the study period. The density changes are shown to be correlated with the summer temperature changes. We show that this observed decrease in density does not have an appreciable effect on the calculated surface mass balance, as the corresponding changes are below the usual error range of the surface mass balance estimates. This relieves us from the need of detailed and time-consuming snow density measurements at every mass-balance campaign.
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Abstract

Different chromosomal forms of Deschampsia antarctica Desv. (Poaceae), including diploids (2n=26), hypotriploid (2n=36–38) and a genotype with an occasional occurrence of B chromosome (2n=26+0-1B) that originated from southern marginal populations (Argentine Islands region, maritime Antarctic) were studied using molecular cytogenetic, morphometric and biochemical methods. FISH analysis revealed variations in the number of rDNA sites between the diploid and hypotriploid plants. The genome size varied among plants with a different chromosome number and was on average 10.88 pg/2C for diploids and 16.46 pg/2C for hypotriploid. The mean values of leaf length of plants grown in vitro varied within a range of 5.23–9.56 cm. The total phenolic content ranged from 51.10 to 105.40 mg/g, and the total flavonoid content ranged from 1.22 to 4.67 mg/g. The amount of phenolic compounds did not differ significantly between the genotypes, while a variation in the flavonoid content was observed for L59 and DAR12. The diploids did not differ significantly among each other in terms of the number of rDNA loci, but differed slightly in their genome size. The individuals of DAR12 carrying B chromosome were similar to other diploids in terms of their genome size, but statistically differed in leaf length. The hypotriploid had both a greater number of rDNA sites and a larger genome size. No statistical correlations were observed between the genome size and leaf length or genome size and accumulation of phenolic and flavonoid compounds. The results of this study suggest that D. antarctica plants from the southern edge of the range are characterised by the heterogeneity of the studied parameters.
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Abstract

In polar regions, apart from tundra and glaciers, geothermally active areas with elevated temperatures are important elements of ecosystems. One such geothermally active region characterized by mosaic ecosystems and vast areas covered by recent lava fields is Iceland. The aim of our study was to explore the diversity of invertebrates inhabiting geothermally active lava fields in the Krafla area (Iceland). Eight bryophyte samples were collected from a warm surface, mainly from the steaming areas. We have found Nematoda, Rotifera, Tardigrada and Oribatida in the samples. Habitat analysis demonstrated there to be 12 bryophyte species (five liverworts and seven mosses). The diversity of bryophytes in a single sample ranged from one to six species. The most common bryophyte was Racomitrium lanuginosum (Hedw.) Brid. Four species of tardigrades were found, including one that was new. Pilatobius islandicus sp. nov. is described herein by morphological, morphometric and molecular approaches (COI, 28S rRNA, 18S rRNA). Oribatida mites were identified as two species (Malaconothrus monodactylus (Michael, 1888) and Camisia foveolata Hammer, 1955). The average density of invertebrates was 13.1 ind./g with a maximum of 40.8 ind./g calculated per dry material. The tardigrades found in our study belonged to herbivores, microbivores and omnivores, whereas the mites belonged to saprophages, which indicates complex trophic networks in geothermally active lava fields.
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Abstract

Climate change has been affecting plants over the last century and caused changes in life history features such as the flowering time. Herbarium specimens provide a snapshot of the past environmental conditions during their collection. The collection date in a herbarium specimen is a good proxy to determine the flowering period (phenology). In this study, phenological data from subarctic plant specimens collected over 100 years were gathered by using one of the largest herbarium databases in the World. The collection dates of 7146 herbarium specimens were analyzed and significant shifts in the phenology of subarctic plants were detected. In this study, most of the analyzed 142 species in a subarctic biogeographic region tended to flower earlier in the 1950–2018 period compared to the 1900–1949 as a possible result of the climate change. Flowering time shifted from 8 to 26 days in some species. Changes in flowering time may alter species interactions, community composition, and species distribution in a region. Therefore, results of this study may shed light on the possible shifts in phenology and plant responses under the climate change.
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Abstract

This article aims to analyse the influence of weather types on meteorological conditions in Petuniabukta (Svalbard) during July and August of 2016. The paper analyses the daily courses of air temperature and humidity at four measurement points located on the west bank of Petuniabukta near Adam Mickiewicz University Polar Station during two different types of weather conditions: (i) cloudy and windy, (ii) calm and clear. These weather types, distinguished on the basis of wind speed and cloudiness, allowed for the creation of composite maps of the synoptic situation (SLP and geopotential height of 500 hPa distribution) and its anomalies. In the study area, the air temperature range in windy and cloudy weather conditions was larger (-10°C to 15°C) than that in sunny and calm weather (0°C to 15°C), which contrasts the range of humidity values. The diurnal cycle of meteorological elements in sunny and calm days is strongly related to the sun elevation angle. In the above-mentioned weather types, the air temperature was higher by several degrees (median 5°C to 8°C) than on windy and cloudy days (median about 0°C to 6°C) at each measurement point. On days with sunny and calm weather, a smaller vertical temperature gradient of air is observed (for sunny and calm days 0.63°C and for windy weather 0.8°C).
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Abstract

The thermal state of permafrost is a crucial indicator of environmental changes occurring in the Arctic. The monitoring of ground temperatures in Svalbard has been carried out in instrumented boreholes, although only few are deeper than 10 m and none are located in southern part of Spitsbergen. Only one of them, Janssonhaugen, located in central part of the island, provides the ground temperature data down to 100 m. Recent studies have proved that significant warming of the ground surface temperatures, observed especially in the last three decades, can be detected not only just few meters below the surface, but reaches much deeper layers. The aim of this paper is evaluation of the permafrost state in the vicinity of the Polish Polar Station in Hornsund using the numerical heat transfer model CryoGrid 2. The model is calibrated with ground temperature data collected from a 2 m deep borehole established in 2013 and then validated with data from the period 1990-2014 from five depths up to 1 m, measured routinely at the Hornsund meteorological station. The study estimates modelled ground thermal profile down to 100 m in depth and presents the evolution of the ground thermal regime in the last 25 years. The simulated subsurface temperature trumpet shows that multiannual variability in that period can reach 25 m in depth. The changes of the ground thermal regime correspond to an increasing trend of air temperatures observed in Hornsund and general warming across Svalbard.
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Abstract

Lichens, as typical obligate associations between lichenized fungi and their photosynthetic partners, are dominant in Antarctica. Three Antarctic lichens, Ochrolechia frigida , Umbilicaria antarctica , and Usnea aurantiaco−atra with different growth forms, were sampled nearby the Great Wall Station, King George Island. Molecular data revealed that the photosynthetic algae in these three lichens were Trebouxia jamesii . The net photo − synthesis (Pn) of three individuals from these species, together with environmental factors such as light and temperature, were recorded by CO 2 gas exchange measurements using a CI−340 portable photosynthetic system in situ . Differences between T(leaf) (the temperature of the thalli) and T(air) (the air temperature) for these lichens were not consistent, which reflected that environment and the growth form of thalli could affect T(leaf) significantly. Strong irradiation was expected to have adverse effects on Pn of Ochrolechia frigida and Umbilicaria antarctica whose thalli spread flat; but this photoinhibition had little effect on Usnea aurantiaco−atra with exuberant tufted thallus. These results indicated that photo − synthetic activity in lichens was affected by the growth forms of thalli besides microhabitat factors. One species of lichenized alga could exhibit diversified types of photosynthetic behavior when it was associated with various lichenized fungi in different microhabitats. It will be helpful for understanding how lichens are able to adapt to and colonize in extreme environments.
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Abstract

Receiver function provides the signature of sharp seismic discontinuities and the information about the shear wave (S−wave) velocity distribution beneath the seismic station. This information is very valuable in areas where any or few reflection and/or refraction studies are available and global and/or regional models give only rough information about the seismic velocities. The data recorded by broadband seismic stations have been analysed to investigate the crustal and upper mantle structure of the Svalbard Archipelago. Svalbard Archipelago is a group of islands located in Arctic, at the north−western part of the Barents Sea continental platform, which is bordered to the west and to the north by passive continental margins. The new procedure of parameterization and selection of receiver functions (RFs) has been proposed. The back−azimuthal sections of RF show a strong variation for the HSPB and KBS stations. Significant amplitudes of transversal component of RF (T−RF) for the HSPB station indicate a shallow dipping layer towards the southwest. The structure of the crust beneath the SPITS array seems to be less heterogeneous, with very low amplitudes of converted phase comparing to the KBS and HSPB stations. Forward modelling by trial−and−error method shows a division of the crust into 3–4 layers beneath all stations and layering of the uppermost mantle beneath the SPITS array and the HSPB stations. The thickness of the mantle transition zone is larger for western part of archipelago and smaller for eastern part comparing to iasp91 model.
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