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Cryoconites are the deposits on the surface of glaciers that create specific ecological niches for the development of microorganism communities. The sediment material can vary in origin, structure, and nutrient content, creating local variations in the growth conditions. An additional factor of variability is the location of the glaciers, as they are found in different climatic zones in the high mountain regions and closer to the poles. Here, using the analysis of amplicon sequencing of the 16S rRNA gene, we studied the taxonomic composition of the prokaryotic communities from glaciers from remote regions, including the Arctic (Mushketova on the Severnaya Zemlya, IGAN in Polar Ural), Antarctic (Pimpirev on the Livingstone Island) and Central Caucasus (Skhelda and Garabashi) and connected it with the variation of the physicochemical characteristics of the substrate: pH, carbon, nitrogen, macro- and microelements. The cryoconite microbiomes were comprised of specific for this environment phyla (mostly Pseudomonadota, Cyanobacteria, Bacteroidota, Acidobacteriota, and Actinobacteriota), but each glacier had a unique taxonomic imprint. The core microbiome between regions was composed of only a few ASVs, among which the most likely globally distributed ones attributed to Polaromonas sp., Rhodoferax sp., Cryobacterium sp., and Hymenobacter frigidus. The WGSNA defined clusters of co-occurring ASVs between microbiomes, that significantly change their abundance corresponding with the variation of chemical parameters of cryoconites, but do not fully coincide with their regional separation. Thus, our work demonstrates that the chemical characteristics of the sediment material can explain the variation in the cryoconite prokaryotic community which is not always linked to geographic isolation., (© 2024. The Author(s).)

Although Antarctica is considered one of the most pristine areas on Earth, an accelerating human presence in this remote continent, such as scientific operations and functioning of numerous scientific stations, logistics, and tourism activities, has increased the risks of environmental impacts in recent decades. During the 63rd Russian Antarctic expedition, 42 samples from topsoil horizons were collected from Larsemann Hills, Mirny station, and Fulmar Island, Eastern Antarctica. The purpose of this work was to analyze the accumulation levels 8 trace elements and to assess possible environmental risks associated with contamination of Antarctic soils. Various human activities have been found to be responsible for increase of metal levels in studied Antarctic environments. Our study also revealed a specific role of ornithogenic factor and moss cover in distribution of contaminants in severe conditions of Eastern Antarctica soils. Ornithogenic soils were characterized by higher rates of accumulation of some trace metals and metalloids (especially zinc and copper) compared with other investigated "pristine" sites without significantly visible traces of guano inputs. In general term, obtained geoaccumulation index for trace elements in all samples were under or slightly above the 0 level, indicating low to moderate pollution of the studied soils. Results of principal component analysis revealed the necessity for further detailed research on interactions of trace metals with soil organic matter for better understanding of their biogeochemistry in the Antarctic environment. Although most of contaminated sites were found in anthropogenically affected areas, accumulation of some elements in guano-derived and moss materials were associated with higher values for soil pollution indices in natural soils, as well.

This study is aimed at investigation of various potential contaminants (arsenic, mercury and polycyclic aromatic hydrocarbons) content in soils of different landscapes of Eastern Antarctica ice-free areas. Our data not only showed that intensive human impact might result in significant direct contamination of surrounding landforms, but also revealed a specific role of ornithogenic transport in distribution of contaminants. Analysis revealed that the contents of investigated elements were 0.100-8.055 mg kg -1 (arsenic), 0.025-0.027 mg kg -1 (mercury) in Larsemann Hills and 0.100-1.213 mg kg -1 (arsenic), 0.023-0.593 mg kg -1 (mercury) in vicinities of Mirny station and Fulmar Island. Accumulation of some elements in guano-derived and moss materials lead to higher values of other soil pollution indices at natural sites. Results of our study revealed the predominance of light molecular weight PAHs (fluorene and acenaphthylene) in studied soils. Results of our study are not completely in agreement with the idea of an practically uncontaminated Antarctic ecosystem which was previously reported for Eastern Antarctica ice-free areas. Various human activities carried out at local scale have been found to be responsible for increase of metal levels in studied Antarctic environments.

Antarctica is considered as one of the most pristine areas on Earth. However, increasing intensity of human presence on the sixth continent (scientific operations, functioning of the numerous scientific stations, tourism activities) makes it crucial to investigate the level of environmental pollution within the vulnerable ecosystem of Antarctica. Soils play a significant role in processes of accumulation, mobilization, redistribution of chemical elements within landscapes, and ecosystems. The aim of this work was to analyze the levels of 17 polycyclic aromatic hydrocarbons and eight trace elements in soils of King George and Ardley islands, Western Antarctica. Moreover, our work was aimed to determine the trends and reasons of anthropogenic pollution of Antarctic soils and characterization of accumulation levels of trace elements and PAHs. Results showed the predominance of light PAHs in all studied sites. The content of benzo(a)pyrene does not exceed the threshold concentration (adopted by different national environmental legislation systems). At the same time, the content of benzo(a)pyrene, which is a marker of anthropogenic contamination, is relatively low or equal to 0 in soils of reference landscapes. Cu and Zn were found as most abundant elements in all studied soils. The highest lead concentration content has been described in soil from Bellingshausen station. In general term, obtained Igeo values for trace elements in all samples were under or slightly above the 0 level, indicating low to moderate pollution of the studied soils. This study also contributes new data on trace element accumulation in soils strongly influenced by ornithogenic factor. Principal component analysis allowed to estimate the probable sources of specific trace metals and their relationship with soil variables. Ornithogenic factor has been also revealed as a driver for some trace element accumulation especially in breeding penguin colonies. High contents of organic matter in ornithogenic habitats could increase trace metal mobility, environmental risks for surrounding terrestrial environments should be considered.