• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.09a
• /
• pp.1030-1038
• /
• 2010

In order to design and construction of the Antarctic Continental Station at the Terra Nova Bay in the East Antarctic, ground characteristics for soil samples taken from the Antarctic. A series of laboratory tests were performed to investigate the variations of the thermal conductivity, the unfrozen water content according to the temperature change of the soil taken from the Antarctic. The temperature were low down below zero.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.9
• /
• pp.1187-1196
• /
• 2013

Global warming will have far-reaching effects on our ecosystem. However, its effects on Antarctic soils have been poorly explored. To assess the effects of warming on microbial abundance and community composition, we sampled Antarctic soils from the King George Island in the Antarctic Peninsula and incubated these soils at elevated temperatures of $5^{\circ}C$ and $8^{\circ}C$ for 14 days. The reduction in total organic carbon and increase in soil respiration were attributed to the increased proliferation of Bacteria, Fungi, and Archaea. Interestingly, bacterial ammonia monooxygenase (amoA) genes were predominant over archaeal amoA, unlike in many other environments reported previously. Phylogenetic analyses of bacterial and archaeal amoA communities via clone libraries revealed that the diversity of amoA genes in Antarctic ammonia-oxidizing prokaryotic communities were temperature-insensitive. Interestingly, our data also showed that the amoA of Antarctic ammonia-oxidizing bacteria (AOB) communities differed from previously described amoA sequences of cultured isolates and clone library sequences, suggesting the presence of novel Antarctic-specific AOB communities. Denitrification-related genes were significantly reduced under warming conditions, whereas the abundance of amoA and nifH increased. Barcoded pyrosequencing of the bacterial 16S rRNA gene revealed that Proteobacteria, Acidobacteria, and Actinobacteria were the major phyla in Antarctic soils and the effect of short-term warming on the bacterial community was not apparent.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.894-904
• /
• 2008

In this study, soil samples from the Antarctic and Vladivostok, Siberia were tested in the laboratory, and specific gravity, compaction curve and grain size distribution were determined. The effect of temperature change on the thermal conductivity, unfrozen water content and compressive strength were investigated. Samples for the compressive strength test were prepared in a mold with a fixed volume to prevent swelling and the effect of temperature and water content change on the strength were compared. Results from the thermal conductivity test showed that thermal conductivity values for both soils were larger at temperatures below freezing than above freezing. The unfrozen water content dropped sharply within a temperature range of $0{\sim}-5^{\circ}C$ and then gradually decreased further up to $-20^{\circ}C$. Compressive strength test results showed various stress/deformation curves with a change in water content. Sandy soil had much larger strength than pure ice at an identical temperature, while clayey soil had a smaller strength than ice near the freezing point, but showed a larger strength at temperatures belows $-15^{\circ}C$.

• Analytical Science and Technology
• /
• v.21 no.5
• /
• pp.364-374
• /
• 2008

Antarctic Environmental Monitoring Handbook' was published by COMNAP/SCAR in 2000. The standardized method described in this handbook is recommended for monitoring of antarctic environment. High pressure bomb technique in this guide was used to decompose soil samples. In compliance with this guide book, high pressure bomb technique was applied to decompose the antarctic soil sampled at the King Sejong Station. An Isotope Dilution-Inductively Coupled Plasma-Mass Spectrometry (ID-ICP-MS) was applied to determine mass concentrations of Pb, Cu and Zn in the soil. The accuracy in this method was verified by the analysis of certified reference materials (CRM) of NIST 2702 (marine sediment). The analytical results agreed with certified value within the range from 99.5~100.8%. Matrix separation was necessitated for the determination of Cu and Zn by Chelex 100 ion exchange resin. As a result, the average mass concentrations of Pb, Cu and Zn which are suspected to be caused by anthropogenic pollution were 332.9 mg/kg, 95.6 mg/kg and 115.3 mg/kg, respectively. Those for the metals sampled in the soils of the remote regions from the station were 28.1 mg/kg, 101.8 mg/kg and 115.6 mg/kg, respectively.

• Korean Journal of Microbiology
• /
• v.28 no.3
• /
• pp.199-203
• /
• 1990

To study distribution of bacterial flora and their biochemical characteristics in the Antarctic soilecosystem, these experiments were performed during the austral summer(Feb., 1989) on the King George Island, Antarctica. The numbers of heterotrophic bacterial colonies and extracellular enzyme actibities were estimated from the Antarctic terrestrial soils which were sampled from 17 different locations near Sejong station (Korea) and Teniente Jubany station (Argentina) on the King George Island. The numbers of heterotrophic bacterial colonies were extremely variable with sampling sites and incubation temperatures. Arithmetric average numbers were $2.5\times 10^{4}$, $2.7\times 10^{7}$ , $6.9\times 10^{5}$ CFU/$cm^{3}$ soil at the incubation temperature of $37^{\circ}C$, $25^{\circ}C$ and $4^{\circ}C$, respectively. The activities of extracellular $\alpha$-glucosidase, $\beta$-glucosidase and N-acetyl-$\beta$-glucosaminidase were shown as similar mean percentage in the colonies obtained at different temperatures. Mean value of protease activities, however, was remarkably higher (92%) in the colonies grown at $4^{\circ}C$,.

• Journal of Korean Society for Atmospheric Environment
• /
• v.16 no.E2
• /
• pp.85-96
• /
• 2000

The concentrations of Pb, Mn, Al and Na were measured from a total of 26 snow samples collected from a 1.5-m deep snow pit in Livingston Island, South Shetland Islands, at the northern tip of the Antarctic Peninsula. Ore sampling location is great concern, because of its proximity to the southern extremity of south America, a candidate for the source regions of pollutant aerosols entering Antarctica. The mean concentrations of Pb and Mn were found to be 4.97 pg g(sup)-1 and 20.6 pgg(sup)-1, respectively. These concentrations levels are similar to those reported for recent snow at other Antarctic sites with pronounced spring maxima for both metals. Contributions form natural sources are estimated to be minor (∼16%) for Pb. For Mn, on the other hand, contribution from rock and soil dusts is found to be very important. Excess Pb over Pb from natural sources is likely to be anthropogenic, especially from South Americal. Our results show that yearly Pb fallout flux is much greater in Antarctic coastal areas than at other Antarctic locations far from the coast , indicating that the transport and deposition patterns of pollutant aerosols are not simple is Antarctica. It is also suggested that the recycling of anthropogenic Pb in seawater to the atmosphere could significantly contribute to the Pb fallout flux in the Antarctic coastal regions.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.5
• /
• pp.661-667
• /
• 2013

Lipase-producing bacterial strains were isolated from Antarctic soil samples using the tricaprylin agar plate method. Seven strains with relatively strong lipase activities were selected. All of them turned out to be Bacillus pumilus strains by the 16S rRNA gene sequence analysis. Their corresponding lipase genes were cloned, sequenced, and compared. Finally, three different Bacillus pumilus lipases (BPL1, BPL2, and BPL3) were chosen. Their amino acid sequence identities were in the range of 92-98% with the previous Bacillus pumilus lipases. Their optimum temperatures and pHs were measured to be $40^{\circ}C$ and pH 9. Lipase BPL1 and lipase BPL2 were stable up to $30^{\circ}C$, whereas lipase BPL3 was stable up to $20^{\circ}C$. Lipase BPL2 was stable within a pH range of 6-10, whereas lipase BPL1 and lipase BPL3 were stable within a pH range of 5-11, showing strong alkaline tolerance. All these lipases exhibited high hydrolytic activity toward p-nitrophenyl caprylate ($C_8$). In addition, lipase BPL1 showed high hydrolytic activity toward tributyrin, whereas lipase BPL2 and lipase BPL3 hydrolyzed tricaprylin and castor oil preferentially. These results demonstrated that the three Antarctic Bacillus lipases were alkaliphilic and had a substrate preference toward short- and medium-chain triglycerides. These Antarctic Bacillus lipases might be used in detergent and food industries.

• Korean Journal of Microbiology
• /
• v.55 no.1
• /
• pp.83-85
• /
• 2019

Pseudomonas sp. PAMC 29040 was isolated from a maritime tundra soil in Antarctica for its ability to degrade lignin and subsequently confirmed to be able to depolymerize heterogeneous humic substance (HS), a main component of soil organic matter. The draft genome sequences of PAMC 29040 were analyzed to discover the putative genes for depolymerization of polymeric HS (e.g., dye-decolorizing peroxidase) and catabolic degradation of HS-derived small aromatics (e.g., vanillate O-demethylase). The information on degradative genes will be used to finally propose the HS degradation pathway(s) of soil bacteria inhabiting cold environments.

• Journal of Ecology and Environment
• /
• v.43 no.3
• /
• pp.289-296
• /
• 2019

We investigated the mortality and the oxidative damages of Deschampsia antarctica in response to waterlogging stress. In field, we compared the changes in the density of D. antarctica tuft at the two different sites over 3 years. The soil water content at site 2 was 6-fold higher than that of site 1, and the density of D. antarctica tuft decreased significantly by 55.4% at site 2 for 3 years, but there was no significant change at site 1. Experimental results in growth chamber showed that the $H_2O_2$ and malondialdehyde content increased under root-flooding treatment (hypoxic conditions-deficiency of $O_2$), but any significant change was not perceptible under the shoot-flooding treatment (anoxic condition-absence of $O_2$). However, total chlorophyll, soluble sugar, protein content, and phenolic compound decreased under the shoot-flooding treatment. In addition, the catalase activity increased significantly on the 1st day of flooding. These results indicate that hypoxic conditions may lead to the overproduction of reactive oxygen species, and anoxic conditions can deplete primary metabolites such as sugars and protein in the leaf tissues of D. antarctica. Under present warming trend in Antarctic Peninsula, D. antarctica tuft growing near the shoreline might more frequently experience flooding due to glacier melting and inundation of seawater, which can enhance the risk of this plant mortality.

• Journal of the Korean GEO-environmental Society
• /
• v.13 no.12
• /
• pp.5-16
• /
• 2012

The second scientific antarctic station of South Korea is under construction at Terra Nova Bay located in eastern Antarctica. Ground condition in the Antarctica is frozen in general, but there are seasonal frozen grounds with active layers sporadically. When the active layer is frozen, frost heaving occurs that might cause the differential movement of frozen ground and the failure of structures. Therefore, it is necessary to determine the frost heaving susceptibility of soils at Terra Nova Bay before starting antarctic station construction. This study presents experimental investigation of the frost heaving susceptibility of soil samples with variation of particle sizes and unfrozen water contents. The soil samples were taken from five different locations at Terra Nova Bay and physical properties, unfrozen water content, and frost heaving tests were performed. For the frost heaving tests, soil specimens were frozen with constant freezing temperatures at the top and with drainage at the bottom in order to stimulate the frost heaving. The frost heaving tests provide volume expansion, volumetric strain, and heaving rate which can be used to analyze the relationship between the frost heaving vs. particle size and the frost heaving vs. unfrozen water content. Experimental results show that the more the fine contents exist in soils, the more frost heaving occurs. In addition, the frost heaving depends on unfrozen water content. Experimental data can be used to evaluate the frost heaving susceptibility of soils at the future construction site in the Antarctica.