Temporal Distribution of Arsenic and Metals in Soil From King George Island, Antarctica

The polar regions are vulnerable to impacts caused by local and global pollution. The Antarctic continent has been considered an environment that has remained little affected by human activities. Direct exposure to contaminants may occur in areas continuously occupied by research stations for several decades. Admiralty Bay on the southeast coast of King George Island, has potential for being affected by human activities due research stations operating in the area, including the Brazilian Commandant Ferraz Antarctic Station (CFAS). The levels of metals and arsenic were determined in soils collected near CFAS (points 5, 6, 7, and 9), Base G and at two points distant from the CFAS: Refuge II and Hennequin. Samples were collected after the fire in CFAS occurred in February 2012, up to December 2018 to assess the environmental impacts in the area. Al and As were related with Base G. Refuge II and Hennequin can be considered as control points for this region. As a consequence of the accident, the increased levels for Cd, Cu, Pb, and Zn, especially at point 9 (inside the CFAS) and in the soil surrounding the CFAS in 2013. The results from 2016 to 2018 demonstrated a reduction in levels of all studied metals near CFAS, which may be related to the leaching of metals into Admiralty Bay; it is thus, being important the continue monitoring soil, sediments, and Antarctic biota.

PELLETS AND PREY REMAINS AS INDICATORS OF THE DIET OF TWO SYMPATRIC SKUAS (AVES: STERCORARIIDAE) ON KING GEORGE ISLAND, ANTARCTICA

South Polar skua (Stercorarius maccormicki) and Brown skua (Stercorarius antarcticus lonnbergi) have opportunistic feeding habits and are the dominant predators in terrestrial Polar regions. These skuas exploit a wide range of food items, including marine organisms, other birds, and even garbage. In the present study, we compare the diets of these two skua species during the breeding season, using pellets and prey remains collected within their territories. The samples were collected at six sites in Admiralty Bay, on King George Island, Antarctica. We identified eight different items, which we classified as “penguin”, “flying bird”, “skua”, “fish”, “gastropod”, “krill”, “egg” and “marine debris”. In the first breeding season (2008/2009), penguins and flying birds were the food resources more abundant for both skua species, and their diet composition was similar. In the second breeding season (2010/2011) South Polar skua exploited more fish and flying birds than Brown skua; the latter exploited more eggs and penguins. Our findings corroborate those of previous studies, demonstrating that in sympatry South Polar skua exploit more fish than Brown skua. The diet of South Polar skua also varied between breeding seasons, reflecting the opportunistic foraging behavior of these skuas. As in other studies, we recorded that skua is a food resource for both skua species, but it was more common in the diet of South Polar skua. Marine debris was recorded only in the samples of Brown skua. Birds are important food items for both skuas, although significant differences were found in the diets of these sympatric species, with shifts in the composition of the diet probably reflecting fluctuations in the abundance of prey populations, which are known to be common at Admiralty Bay, although more data will be needed to confirm this link.

Study of the Lange Glacier and its impact due to temperature increase in Admiralty Bay, King George Island, Antarctica

I n the western Antarctic Peninsula one of the areas the highest warming in the southern hemisphere has been identified. To characterize this tendency, we selected the Lange Glacier (LG) on King George Island, to evaluate: 1) LG surface temperature and dynamics using stakes with temperature data loggers; 2) LG submerged thickness and sea parameters through bathymetry (BT) and 29 CTD stations in front of LG; 3) glacier front (GF) using BT and a Digital Elevation Model (DEM); 4) change in GF position using DEM and historical data of GF width; 5) Calving flux (QC). Our findings showed 85 % of temperatures were above the 0 °C melting point (mean = 5.0 ± 5.2 °C). The stakes had an average ice loss of 9.3 ± 1.3 cm. The LG mean dynamics was 8.8 ± 1.5 m (0.40 ± 0.70 m/day), corroborated by Sentinel-1 satellite images (Offset Tracking = 0.43 ± 0.01 m/day). An intrusion of external waters warmer in the LG bay was identified, which destabilizes the water column due to convection processes. Our findings together indicated a continuous glacial melt that increases its dynamics due to the increase in temperature, with a contribution of fresh water to the Admiralty Bay. Based on historical results and this study, the LG retracement was estimated in 2,492 m between 1956 and 2019.

Characterization of radionuclides in the marine sediments of Orca Seamount, Admiralty Bay, and Mackellar Cove

Contamination by radioactive elements and their transfer through the trophic chain can have harmful effects on ecosystems and human health, therefore its continuous monitoring is important. The present study aimed to characterize the concentration of radionuclides of natural and anthropogenic origin in marine sediments from three areas in the northwest of Antarctica, Orca Seamount, Admiralty Bay and Mackellar Inlet, in order to evaluate possible risk levels, sources and transportation routes. Measurements were made using a high-resolution Canberra spectrometer and methodological precision and accuracy was assessed by analyzing reference materials certified by the International Atomic Energy Agency (IAEA), SOIL-6 and Moss SOIL-447. The results showed a low concentration of 137Cs activity in the marine sediments, decreasing towards the deep zone, validating the atmospheric pathway as the main transport route for this radionuclide of anthropic origin. The activity concentration of radionuclides of natural origin 226Ra and 40K, confirm the volcanic origin of the region, corroborating the geological evolution stages of the sector, and the changes in the source of material to the mantle. The calculated radiation hazard indexes showed that current activity concentrations of radioactive elements do not pose a health risk. It is important in the future to improve the understanding of the relationship between hydrothermalism in the area and the activity concentration of radionuclides of natural origin.

Petrography and geochemistry of magmatic rocks from Admiralty Bay, King George Island (South Shetland Islands, Antarctica): Preliminary results

<p>South Shetland Islands in Western Antarctica is dominated by a widespread magmatism through Meso-Cenozoic due to the magmatic arc created by the subduction of Phoenix plate along the South Shetland trench. Within the scope of 4th Turkish Antarctic Expedition (TAE-IV) and Turkey-Poland Bilateral cooperation, field studies were conducted in Admiralty Bay (King George Island) that host various magmatic units  in order to understand the magmatic evolution beneath Meso-Cenozoic Western Antarctica.</p><p>Magmatic products consists of Paleocene-Eocene aged volcanic and subvolcanic rocks in Admiralty Bay. Volcanic rocks are represented by terrestrial lavas and pyroclastic rocks (agglomerates, tuffs and volcanic breccias) while subvolcanic rocks consist of dykes and stocks. According to the petrographic investigations, volcanic and subvolcanic rocks in the area mostly display disequilibrium textures such as sieve textures and embayments in plagioclase and pyroxenes, patchy and oscillatory zoning in different generations of plagioclases and the existence of K-Feldspar xenocrysts with reaction rims along the borders.</p><p>Geochemically, the compositions of the magmatic rocks in the study area range from dacite to basalt. Volcanic and subvolcanic rocks show similar geochemical signatures. The samples show mostly calc-alkaline affinities. There are two predominant compositional variations, felsic and intermediate-mafic. Their MgO content ranges within 0.28-1.20 wt. % for the more felsic lavas and 2.78-5.24 wt. % for intermediate-mafic lavas. Their Al<sub>2</sub>O<sub>3</sub> contents are relatively high (14.91-24.29 wt. %). The samples are slightly enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE) compared to HFSE and HREE. The samples display high Th/Yb ratios ranging from 3.78 to 0.69. Strong depletions in Nb and Ti elements are observed as typical indicators for subduction zone magmatism. Although most of the samples show similar patterns in spider diagrams, a strong discrepancy is seen in immobile elements such as Hf and Zr, resulting in positive anomalies in felsic and negative anomalies in intermediate-mafic rocks. Similarly, negative Eu anomalies observed only in the felsic rocks. Eu/Eu* ratios varies within 0.59-0.71 for felsic rocks, and 0.85-1.12 for intermediate-mafic rocks. These different patterns in different compositions suggest an open system differentiation for the melt evolution. Petrographic and geochemical evaluations indicate that the magma beneath Meso-Cenozoic Western Antarctica is originated from lithospheric mantle metasomatized by subduction components, and fractional crystallization/assimilation fractional crystallization contributed to the magmatic evolution.</p><p> </p><p> </p><p> </p>

Metabolic fingerprinting of the Antarctic cyanolichen Leptogium puberulum–associated bacterial community (Western Shore of Admiralty Bay, King George Island, Maritime Antarctica)

Lichens are presently regarded as stable biotopes, small ecosystems providing a safe haven for the development of a diverse and numerous microbiome. In this study, we conducted a functional diversity assessment of the microbial community residing on the surface and within the thalli of Leptogium puberulum, a eurytopic cyanolichen endemic to Antarctica, employing the widely used Biolog EcoPlates which test the catabolism of 31 carbon compounds in a colorimetric respiration assay. Lichen thalli occupying moraine ridges of differing age within a proglacial chronosequence, as well as those growing in sites of contrasting nutrient concentrations, were procured from the diverse landscape of the western shore of Admiralty Bay in Maritime Antarctica. The L. puberulum bacterial community catabolized photobiont- (glucose-containing carbohydrates) and mycobiont-specific carbon compounds (d-Mannitol). The bacteria also had the ability to process degradation products of lichen thalli components (d-cellobiose and N-acetyl-d-glucosamine). Lichen thalli growth site characteristics had an impact on metabolic diversity and respiration intensity of the bacterial communities. While high nutrient contents in lichen specimens from “young” proglacial locations and in those from nitrogen enriched sites stimulated bacterial catabolic activity, in old proglacial locations and in nutrient-lacking sites, a metabolic activity restriction was apparent, presumably due to lichen-specific microbial control mechanisms.