Search

The study of microbial complexes in organo-accumulative horizons of Antarctic soils (Cryosols, Leptosols) at the Larsemann Hills and Schirmacher oases and on King George Island has been carried out by the fouling glass method. This method allows one to study the taxonomic composition of microorganisms, features of their morphology, inter-organism interactions, and spatial organization of the complex of microorganisms, as well as to simulate the processes of colonization of mineral surfaces. The investigated microbial complexes can be subdivided into four groups with respect to dominant microorganisms: (1) diverse microbial complexes of King George Island with a considerable portion of diatoms among algae and with a predominance of mycelium in the fungal biomass; (2) complexes of lichen–moss, moss, and algal–moss associations in lake basins with a greater proportion of eukaryotic and coccoid cyanobacteria and with mycelium and sporous forms of micromycetes; (3) complexes of moss and algal–moss associations in the bottoms of wet valleys with a higher proportion of filamentous cyanobacteria and with the absence of fungi, or their presence in the form of short chains of chlamydospores; and (4) hypolithic microbial complexes of rock baths in dry rocky habitats, where the fouling of glasses did not take place. The microbial complexes in different glass samples taken in February–March in different years proved to be at different stages of development. Microscopic mycelium of fungi was not abundant in all algae and moss associations; in some, it was practically absent. Among algae, not cyanobacteria, but eukaryotic algae dominated in a number of habitats: diatoms, green algae, and streptophytes. The totality of the complex features indicated the extremity of the habitat: one morphotype of melanized fungal mycelium dominated in a particular sample; there was no diversity of spore forms, which indirectly indicates a low taxonomic diversity of fungi; multiple chlamydospore formation and microcycles of development were common. Among cyanobacteria, brown and reddish coloration was often found, and the formation of biofilms on glasses was limited to microcolonies, while algal biofilms abundantly covered the soil of the studied horizons. Apparently, extended biofilms were formed over time exceeding the exposure time of the glasses. Hypolithic communities did not colonize new habitats (glasses) for several years of exposure, unlike the bottoms of hydromorphic valleys and lake basins in oases (glasses overgrown in a year) and King George Island (glasses overgrown in 10 days). [ABSTRACT FROM AUTHOR]

Monitoring of active layer thawing depth and active layer thickness (ALT), using mechanical pronging and continuous temperature data logging, has been undertaken under the Circumpolar Active Layer Monitoring – South (CALM-S) program at a range of sites across Antarctica. The objective of this study was to summarize key data from sites in different Antarctic regions from 2006 to 2015 to review the state of the active layer in Antarctica and the effectiveness of the CALM-S program. The data from 16 sites involving 8 CALM-S and another 8 boreholes across the Antarctic have been used in the study. Probing for thaw depth, while giving information on local spatial variability, often underestimates the maximum ALT of Antarctic soils compared to that determined using continuous temperature monitoring. The differences are likely to be caused by stones limiting probe penetration and the timing of probing not coinciding with the timing of maximum thaw, which varies between seasons. The information on the active layer depth is still sparse in many regions and the monitoring needs to be extended and continued to provide a better understanding of both spatial and temporal variability in Antarctic soil thermal properties. [ABSTRACT FROM AUTHOR]

Cryosols of the Antarctic maritime area are much different from the continental ones. The relatively moderate climate conditions in Maritime Antarctica and a strong interaction between the biotic and abiotic environment are drivers for more intensive soil formation processes than in the continental regions. Soil formation studies from the Maritime Antarctica are, however, rather rare. Therefore, micromorphological investigations on polar soils can contribute to more comprehensive information on soil genesis in Antarctica. In this study, we applied the micromorphological study of thin sections from soil micromonoliths to assess the intensity and trends of the pedogenic processes in selected soils from two adjacent islands of the South-Shetland archipelago: King George Island and Livingston Island. The results obtained show that regional lithology and the origin of the incoming organic matter mainly determine the micromorphological structure of the local soils. Soil matrix micromorphological properties and features (mineralogical content, weathering stage and even partly grain-size distribution) are mainly defined by pyroclastic particles due to recent and ancient volcanic eruptions. The presence of rounded grains and aggregated mineral particles is the evidence of marine origin of the sediments. Ornithogenic soils show the clear evidence of the organic plasma formation and mineral particles aggregation via the zoogenic organic substances provided by penguins which is a unique specifics of the maritime Antarctic soils. [ABSTRACT FROM AUTHOR]

The role of ornithogenic factor in the formation of soils and soil cover patterns in continental and maritime Antarctica is considered. The results of long-term soil studies at key sites in coastal oases of East Antarctica (Larsemann Hills, the Haswell Islands) and on the Subantarctic islands (King George Island, Livingston Island, the Argentine Islands) are summarized. The influence of the penguin rookeries on the morphology and physicochemical properties of soils is shown. These rookeries determine the vast spatial zones of biogeochemical influence on the environment around themselves. Special attention is paid to the phenomenon of ornithochory, which is maintained by the flying seabirds (skuas, albatrosses, terns, petrels, etc.) and is manifested in redistribution of vegetation, soil material, and meso- and microbiota to the areas that were previously free of vegetation and soil cover (periglacial areas, fresh moraines, rocky outcrops, etc.). [ABSTRACT FROM AUTHOR]

The biogeochemical effect of birds can influence the paedogenic processes in the Antarctica soils. The content of nutrients (phosphorus, potassium, nitrate and ammonium) and the total carbon and nitrogen contents in soils were determined at the nesting and feeding sites of flying and non-flying birds in the Fildes Peninsula (King George Island, West Antarctica). The results showed that the difference between soils affected by birds (both flying and non-flying) and the background soils was observed with the higher content of biogenic elements (e.g. C, N, P, K) and fine-earth content, variable soil pH values, more expressed soil structure and specific morphology of the uppermost organogenic and organo-mineral horizons. Additional chemical indices are suggested for diagnostics of current and recent effect of birds on paedoenvironments. [ABSTRACT FROM AUTHOR]

The method of luminescent microscopy has been applied to study the structure of the microbial biomass of soils and soil-like bodies in East (the Thala Hills and Larsemann Hills oases) and West (Cape Burks, Hobbs coast) Antarctica. According to Soil Taxonomy, the studied soils mainly belong to the subgroups of Aquic Haploturbels, Typic Haploturbels, Typic Haplorthels, and Lithic Haplorthels. The major contribution to their microbial biomass belongs to fungi. The highest fungal biomass (up to 790 μg C/g soil) has been found in the soils with surface organic horizons in the form of thin moss/lichen litters, in which the development of fungal mycelium is most active. A larger part of fungal biomass (70-98%) is represented by spores. For the soils without vegetation cover, the accumulation of bacterial and fungal biomass takes place in the horizons under surface desert pavements. In the upper parts of the soils without vegetation cover and in the organic soil horizons, the major part (>60%) of fungal mycelium contains protective melanin pigments. Among bacteria, the high portion (up to 50%) of small filtering forms is observed. A considerable increase (up to 290.2 ± 27 μg C/g soil) in the fungal biomass owing to the development of yeasts has been shown for gley soils (gleyzems) developing from sapropel sediments under subaquatic conditions and for the algal-bacterial mat on the bottom of the lake (920.7 ± 46 μg C/g soil). The production of carbon dioxide by the soils varies from 0.47 to 2.34 μg C-CO/(g day). The intensity of nitrogen fixation in the studied samples is generally low: from 0.08 to 55.85 ng СН/(g day). The intensity of denitrification varies from 0.09 to 19.28 μg N-NO/(g day). [ABSTRACT FROM AUTHOR]

Only 0.35% (49,500 km 2 ) of Antarctica is ice-free. These areas are scattered around the periphery of the continent and in interior mountain ranges, making soil mapping difficult. Here we compile the results of mapping in five of the nine ice-free areas that account for 79% of the ice-free area on a reconnaissance scale and interpret the distribution of soil subgroups in Soil Taxonomy . Soils of Antarctica are contained in four orders, dominantly Gelisols (84%), 13 suborders, 27 great groups, and 76 subgroups. Forty-five percent of the soils of Antarctica are Orthels, Gelisols that show minimal cryoturbation and occur in dry landscape positions; 38% of the soils are Turbels showing cryoturbation and occurring in more moist landscape positions. Only 16% of the soils of Antarctica lack permafrost in the control section and are classified as Entisols (Gel-great groups), Inceptisols (Gelepts suborder or Gelaquepts), or Histosols (Gel-great groups). These soils occur almost exclusively along the western Antarctic Peninsula and at elevations below 30 m in the South Shetland Islands (SSI) and South Orkney Islands (SOI). Typic Anhyorthels are the dominant soil subgroup comprising nearly 15,340 km 2 , or 31% of the soils in Antarctica. These soils occur primarily in central and southern Victoria Land, but also occur in the Thiel and Pensacola Mountains and Shackleton Range, the Prince Charles Mountains, and the mountains of Queen Maud Land. Typic Haploturbels and Typic Anhyturbels occupy 14 and 13% of the soils of ice-free regions of Antarctica, respectively. Most abundant in central Victoria Land, they are common in most mountainous regions of Antarctica. The dominant soil processes of maritime Antarctica are cryoturbation, gleization, melanization, podzolization, paludization, and phosphatization. In coastal East Antarctica, the major soil processes are rubification, salinization, calcification, pervection, and gleization. The predominant soil-forming processes in the Transantarctic Mountains include rubification, salinization, desert pavement formation, and permafrost development. Measures of pedodiversity will be valuable in the selection of protected areas in Antarctica. [ABSTRACT FROM AUTHOR]

• The soil-geomorphological map of Fildes Peninsula and Ardley Island was prepared. • The approximately 30 km2 of the ice-free area were surveyed. • Cryosols dominate on the nearly half (42.9%) of the territory. • Protic Arenosols comprise the second largest soil map unit. • Nearly 1% of the territory is covered by human-affected Technosols. Data on the morphology and major physical and chemical properties of 130 pedons sampled in the ice-free area of the Fildes Peninsula and adjacent Ardley Island (King George Island, West Antarctica) are analyzed, and the soil-geomorphological map of the surveyed area on the scale of 1:10 000 is presented. The soils have been classified according to the WRB (2014/2015) system. The map provides information on the soil cover patterns in relation to geomorphic elements and also reflects the degree of anthropogenic load on the studied territory. Nearly half (42.9%) of the total area is covered by different subgroups of Cryosols. Flat watersheds are mainly occupied by Protic Arenosols (Turbic) (22.9%). Leptosols are mainly represented by the Lithic (Ochric) subgroup covering 13.8% of the area. Fluvisols are locally developed in the tidal zone (3.3% of the total area) and are represented by the Tidalic (Skeletic) subgroup. The unique area of Fibric Cryic Histosol (0.02%) is separately delineated. Various Hyperskeletic Technosols (Toxic, Transportic, and Urbic) are formed under the influence of human loads and cover about 0.9% of the Fildes Peninsula and Ardley Island. The map as the main result of the study can be used for monitoring and forecasting the environmental changes of soil cover pattern under the global climate change and local anthropogenic impact. [ABSTRACT FROM AUTHOR]