Ukrainian Antarctic Journal

The impact of surface waves of South American earthquakes on the ice sheet of the Antarctic Peninsula

Dmytro Gryn — 2024-12-31

Earthquakes cause fluctuations in the surface of the geological environment, which may affect Antarctica’s ice sheet. As seismic waves interact with a glacier, more fissures appear, and its speed may increase. These processes may accelerate the reduction in the total mass of the West Antarctic ice cover. We analysed the physical impact of earthquakes registered at the Ukrainian Antarctic Akademik Vernadsky station on some local glaciers. We also aimed to indirectly identify the consequences of the destruction of the integrity of the glacier structure, which are accompanied by the appearance of induced seismicity. The most characteristic wave fields from various seismically active tectonic zones around Galindez Island were selected to analyse glacier response to earthquake-related seismic forces. We analysed the acceleration of the ground’s surface for short-term earthquakes and the time during which these seismic waves were acting on the local glaciers. Seismic data from the most distant earthquake in Peru, magnitude 7.2, which occurred on May 26, 2022, at 12:02:21 UTC, were used to avoid the cumulative effect of P waves, S waves, and surface waves. Seismic waves of different types arrive at the observation point at different times due to the large distance from the source and different rates of wave propagation. This separation allows us to study the interaction of each type of wave and the glacier individually. This publication reports our analysis of the effect of a long-period surface wave on glaciers near Galindez Island. Induced cryoseismicity manifests itself in the high-frequency region of seismic records as a series of pulses associated with the formation of ice cracks. We used the data from the Guralp CMG 40-TDE seismic station, currently the only one at the Akademik Vernadsky station. The available seismic data made it possible to identify the cause-and-effect relationship between teleseismic waves from tectonic earthquakes and local cryoseismicity. However, the data from a single station do not allow for locating cryoseismic sources. We also analysed the characteristic local interference wave fields that complicate detecting target waves.

The procedure for preparing one-second variometer data of the Argentine Island geomagnetic observatory

Yurii Sumaruk — 2024-12-31

Magnetic observatories have been and continue to be basic elements for studying historical and contemporary changes in the Earth’s geomagnetic field. In most cases, satellite data are used to characterize and study rapidly evolving processes in near-Earth space. However, in recent decades, data from ground-based observatories have been used to support satellite missions. These data must have high temporal resolution to analyze rapidly changing processes. Furthermore, processed data from observatories should be delivered with minimal delay. Advances in technology now allow geomagnetic observatories to be equipped with high-resolution instruments, enabling the rapid delivery of final data. This paper outlines the methods developed to obtain one-second ImagCDF data of the Quasi-definitive level using the geomagnetic records of the Argentine Island observatory (INTERMAGNET code AIA). The observatory's state-of-the-art equipment and absence of anthropogenic noise produce results that meet the INTERMAGNET requirements. The primary data were validated by analyzing the distribution of instrumental errors in the absolute
measurements. The quality of the difference in the field’s absolute value was assessed using statistical parameters, including the mean, standard deviation, and the absolute value of the maximum deviation. Peak and irregular noise values were identified by analyzing the results of numerical differentiation of the 10 Hz records from the LEMI-025N63 and the difference signals between this magnetometer and the proton magnetometer POS-1. Regular noises were identified from the signal spectra. Occasional spikes in the POS-1 readings were corrected by interpolating data between valid counts. One-minute temperature data of the sensor and electronic unit of the LEMI-025N63 variometer were aligned with the magnetic records (using identical digital filtering and resampling procedures). The data were processed using software recommended by INTERMAGNET.

Lagrangian pathways connecting the Weddell and Bellingshausen Seas

Roman Bezhenar — 2024-12-31

This study assesses the connectivity of currents around the Antarctic Peninsula and identifies the structure of flows carrying virtual particles from the Eastern to Western Antarctic Peninsula continental shelves. We use circulation data for the Weddell and Bellingshausen Seas from the Whole Antarctica Ocean Model to obtain and analyse particle trajectories using the Probably A Really Computationally Efficient Lagrangian Simulator (Parcels) model. The software included the main Parcels kernels and a previously developed kernel that ensures the conservation of the number of particles during flow around irregularities in the bottom relief and the lower edge of ice shelves. We also developed a kernel to simulate convection in the ocean’s upper mixed layer. Around 170 000 virtual particles were released at a depth of 10 m during a year with a spatial step of 1° in two shelf and slope sectors in the southern Weddell Sea where the depth is less than 1500 m. The first sector covers the shelf area between 71°S and 77°S adjacent to the Filchner-Ronne Ice Shelf. The second sector covers the shelf area between 70°S and 65°S adjacent to the Larsen Ice Shelf. The pathways of water masses were characterised by the percentage of particles that visit each 10 × 10 km grid cell at least once in a modelling period of 20 years. 21% of particles cross 58°W (tip of the Antarctic Peninsula), while 70% of particles turn northeast. The smaller sector, adjacent to the Larsen Ice Shelf, is the main source of particles transferred to the Bellingshausen Sea (51%). In contrast, particles released in the larger sector were mostly transported to the northeast (75%). Only 3.4% of the released particles were transported to the west of 80°W, while the Amundsen Sea (105°W) was reached only by 0.1% of released particles. That indicates a virtual lack of circulation connectivity between the Weddell and the Amundsen Seas.

Study of the magnetic response to the AGW propagation based on measurements at the Akademik Vernadsky station

Alla Fedorenko — 2024-12-31

To find the electromagnetic response to the propagation of atmospheric gravity waves (AGWs), wave fluctuations of the magnetic field were studied according to measurement data at the Ukrainian Antarctic Akademik Vernadsky station. We analysed continuous data for three components of the geomagnetic field of January–March 2024. We considered wave fluctuations of the magnetic field in the period range of 5–60 min, which correspond to medium-scale AGW in the atmosphere. From January–March, a total of 500 wave events were analysed. The amplitudes ranged from ~one nT to several tens of nT. Two dominant period groups were observed: ~5–12 minutes (including the Brunt–Väisälä period) and 25–30 minutes. We suppose that this pattern indicates a different origin of the AGW. This new result indicates the experimental possibility of separating the effects of AGW influences “from below” and “from above”. Time intervals during the day when magnetic field fluctuations are observed most often were determined. In all three magnetic field components, fluctuations are observed simultaneously in the evening. In geomagnetically quiet conditions, there is a daily asymmetry in the frequency of occurrence of meridional and zonal disturbances. Wave activity in the meridional B_x and vertical B_z components is registered mainly in the morning and evening. In the component B_y, wave disturbances prevail in the daytime from 10 to 14 hours (UT) and are also observed in the evening. In March 2024, there were two geomagnetic storms during which the amplitudes of magnetic field fluctuations increased simultaneously in different period ranges. The fluctuations may be caused by modulation of polar current systems and/or dynamo-current generation during the propagation of AGW at heights in the E-region of the ionosphere. Further studies are needed to establish which mechanism contributes more to the phenomenon.

Intron length polymorphism of β-tubulin genes in Colobanthus quitensis across the Argentine Islands-Kyiv Peninsula region

Anastasiia Rabokon — 2024-12-31

This work analyses intron length polymorphism of β-tubulin genes in populations of Antarctic pearlwort (Colobanthus quitensis) from the relatively compact region of the Argentine Islands-Kyiv Peninsula (the maritime Antarctic). Analysis of the length polymorphism of the two introns of β-tubulin genes in natural populations of C. quitensis revealed a generally low level of genetic polymorphism. Investigation of the first intron length polymorphism revealed two groups of populations. The population of the largest of Berthelot Islands has representatives of both groups. The second intron length polymorphism of β-tubulin genes identified individual genotypes in 7 of the 11 studied populations of C. quitensis. We speculate that this might be due to the spread of plants from different locations or a combination of changes under different environmental conditions.

Chromosomal polymorphism of Belgica antarctica populations: possible links on ecology and geography

Pavlo Kovalenko — 2024-12-31

Chromosomal inversion polymorphism is an important evolutionary mechanism for many species, particularly insects. Belgica antarctica (Chironomidae) is the only endemic insect of the Antarctic Peninsula and is currently considered a model organism for studying adaptations of living organisms to climate change in the extreme terrestrial ecosystems of Antarctica. This polar midge has salivary gland polytene chromosomes, making it convenient for investigating various chromosomal aberrations and analysing their potential relationship with geographical and ecological factors. In this study, chromosomal polymorphism was analysed in the salivary glands of 99 fourth-instar larvae of Belgica antarctica, collected in four different localities in the West Antarctic Peninsula region in 2022. Six of the seven previously described heritable heterozygous inversions for this species were found in the newly tested populations. Notably, the precise location of a large inversion in chromosome I, containing the nucleolar organizer region, was identified for the first time since its discovery in 1962. Additionally, the data on chromosomal inversion frequencies
were combined with all currently available data – together from 1436 Belgica antarctica individuals across 26 populations, from 1962 to 2022, to determine potential links to specific ecological (ecological complexity, ornithogenic influence, and whether samples were collected from nesting or non-nesting material) and geographical (longitude and latitude) factors. It was found that, overall, the ecological factors do not affect the frequency of the studied inversions. However, slight trends were observed in the frequency of four heterozygous rearrangements with latitude, as well as the frequency of specimens with at least one non-sex-linked heterozygous inversion with longitude.

Biocontrol potential of Antarctic endophytic bacteria

Olga Iungin — 2024-12-31

Antarctic endophytes, adapted to harsh environmental conditions, possess unique metabolic capabilities that can influence plant-microbe interactions. In this study, we investigated the impact of 15 plant growth-promoting bacterial strains isolated from Deschampsia antarctica and Colobanthus quitensis on the growth of phytopathogenic fungi. Besides everything else, among growth-promoting traits it was shown that bacteria synthesized biosurfactants, ammonia, and auxin-like hormones for plant growth, and also have shown significant growth in a wide temperature range. While these endophytes exhibited significant antifungal activity against agriculturally important fungi, we also observed the stimulation of fungal growth by certain strains. This dual role of endophytes highlights the complex and contextdependent nature of plant-microbe interactions. Our findings suggest that the effects of endophytes on plant health can
be multifaceted. While they can directly inhibit pathogens, they can also indirectly influence the plant microbiome, potentially leading to beneficial and detrimental outcomes. Further research is needed to elucidate the mechanisms underlying these complex interactions and to harness Antarctic endophytes’ potential for sustainable agriculture.