Outdoors modelling of snowdrift at SANAE IV Research Station, Antarctica

This paper describes the experimental modelling procedure and results to evaluate the snowdrift characteristics surrounding the research station of the South African National Antarctic Expedition, SANAE IV. For this purpose a 1:25 scale model of the research station was constructed and mounted on a large flat snow covered area in the vicinity of the base. The wind profiles of the prevailing winds were measured with a 6-m wind mast positioned near the base model and the characteristic surface roughness and shear velocity functions were derived and analysed. Snow buildup was measured behind the scale model as well as the existing research station and a comparison was evaluated between the two, based on a similarity analysis. The similarity analysis method and results are presented in this paper. It is found that the surface roughness and shear velocity functions derived from the wind velocity data compares favourably with available results in literature for similar measurements of wind profiles in drifting snow conditions. From these results an inner law velocity relationship is established with additional parameters to account for the effects of surface roughness and saltating snow. It is further shown that the scaling parameters employed for the snowdrift modelling provide acceptable results when applied to outdoors modelling of snowdrifting.     

Hydrogen vector for using PV energy obtained at Esperanza Base,Antarctica

The use of solar photovoltaic (PV) is universally considered valuable for its renewable and clean nature; solar energy is especially important in regions far from urban centers and power distribution networks. It is known that the loss due to the latitude and the atmospheric layer is partially offset in very different annual distribution (i.e., by the long summer days) and in sparsely populated areas, because of the clearer atmosphere. Even with these assumptions, low temperatures (snow often combined with strong winds) and the effects of seasonality are difficult obstacles for the proper use of solar PV energy at high latitudes.In this work, both analytical and experimental data of the solar resource at Esperanza Base, Antarctica, are presented. The PV modules were installed in a vertical configuration and NW–NE orientation, which not only maximizes performance but also mitigates the adverse effects due to the latitude. In order to overcome the very asymmetric annual irradiance distribution, the use of a system of hydrogen production and accumulation, is proposed for effective energy storage.The results of two years of evaluation of PV potential at Esperanza Base show that duplicating the PV capture area in Esperanza allows to obtain the same total annual energy than the maximum acquired in Buenos Aires (PV module facing north with optimum tilt for solar capture).To effectively overcome discontinuity of solar energy and its sharp drop in four of the twelve months of the year an appropriate hydrogen vector system is proposed and analyzed.     

抗铜绿假单胞菌南极微生物的筛选、鉴定及其抑菌谱研究

该研究采用稀释涂布平板法从南极团结湖沉积物中分离、纯化南极微生物,采用双层平板法和琼脂扩散法从中筛选铜绿假单胞菌的拮抗菌,通过形态观察、生理生化试验及16S rDNA序列分析对筛选菌株进行菌种鉴定,并测定其抑菌谱。结果表明,共分离纯化出64株南极微生物,8株对铜绿假单胞菌具有抑制作用,其中菌株NO.TJ31的抑制效果最好,抑菌圈直径达（22.3±0.7） mm,经鉴定,其为弗氏甲基杆菌（Methylobacterium frigidaeris）,菌株NO.TJ31对大肠杆菌、金黄色葡萄球菌、白色念珠菌、副溶血弧菌、鼠伤寒沙门氏菌、鲍曼不动杆菌、屎肠球菌、肺炎克雷伯氏菌都具有一定的抑制作用,具有较广的抑菌谱。     

Tourism on ice: environmental impact assessment of Antarctic tourism

The evolving institutional arrangements for the environmental impact assessment (EIA) of Antarctic tourism are evaluated and suggestions made on its future. The EIA provisions of the 1991 Madrid Protocol are legally required by companies, registered in Treaty signatory states, in planning and managing all tourist activities. An assessment of the three tiers of EIA established under the Protocol is presented. Potential solutions for assessing impacts of Antarctic tourism include adoption of strategic environmental assessment, regional assessments and environmental auditing. International best practice methods should be adopted in the initial environmental evaluation along with greater consistency of EIA application through indicative lists and guidelines, a dedicated database of Antarctic EIAs and increased cooperation in the EIA process between the tourism industry and Antarctic Treaty Consultative Parties that support Antarctic logistics and science.     

Assessment and development of snowmelt retrieval algorithms over Antarctica from K-band spaceborne brightness temperature (1979-2008)

Results from several previously published algorithms for wet snow detection in Antarctica from K-band spaceborne brightness temperature are compared and evaluated vs. estimates of wet snow conditions from ground measurements. In addition, a new physically-driven algorithm, in which the detectable liquid water content is assumed constant, is proposed and assessed. All algorithms are also evaluated by analyzing their results during collapses of ice shelves. Two algorithms are selected for deriving updated trends of melting index (MI, the number of melting days times the area subject to melting) between 1979 and 2008 over the whole Antarctica and at sub-continental scales. In the first algorithm wet snow is identified when brightness temperature exceeds the mean of winter brightness temperature plus 30 K and the second is the new model-based approach described here. Both negative and positive MI trends are obtained, depending on the algorithm used. A high number of melting days (up to 100 days) are detected over the Wilkins ice shelf, the Peninsula and the George VI ice shelf. Over East Antarctica, the West and Amery ice shelves are subject to melting for a maximum of approximately 50 days. Positive trends of number of melting days are detected over most of the West Antarctica, with peak values up to 1.2 days/year over the Larsen C ice shelf, 1.8 days/year over the George VI ice shelf and 0.55 days/year over the Wilkins ice shelf area. The correlation between MI values and December-January (DJ) averaged air/surface temperature over selected locations show values ranging between ∼ 0.8 and ∼ 0.4. Results suggest that a 1 °C increase in the monthly averaged DJ air/surface temperature corresponds to an average MI increase of approximately 2·10⁶ × km² × day.     

Short-term variations in the occurrence of heavy metals in Antarctic snow from Coats Land since the 1920s

Short-term variations in heavy metals concentrations in Antarctic snow have been investigated by analysing 13 metals (Al, V, Cr, Mn, Co, Cu, Zn, Ag, Cd, Ba, Pb, Bi and U) in a series of ultraclean samples collected from two snow pits in Coats Land in the Atlantic sector of Antarctica. The samples covered a approximately 70 years time period from the 1920s to 1990. They were analysed by inductively coupled plasma sector field mass spectrometry and graphite furnace atomic absorption spectrometry. The results conclusively show that there is a pronounced short-term (intra- and inter-annual) variability of heavy metal in Antarctic snow, with the highest concentrations being up to 100 times higher than the lowest ones for metal such as Cr, Mn, Pb and U. Contributions from the different possible natural and anthropogenic sources are found to be extremely variable. This is especially due to the large variability in the transport patterns of heavy metals from Southern America, Southern Africa and Australia to the Antarctic continent. Inputs from several volcanic events were identified in our samples from non-seasalt sulfate concentrations profiles. The only ones that gave clear signals for heavy metals were eruptions at Deception Island the proximity of which allowed for tropospheric transport to Coats Land.     

Fulvic acid in microlayer waters of the Gerlache Inlet Sea (Antarctica): their distribution in dissolved and particulate phases

In this work we studied the distribution of humic compounds between microlayer and subsurface waters. Both dissolved (DFA) and particulate (PFA) matter were considered. Humic acids were not found. The amount of total particulate matter is the same both in microlayer and subsurface waters. Conversely, particulate organic matter and fulvic acid concentrations were greater in microlayer waters. Enrichment factors (microlayer PFA/subsurface PFA and microlayer DFA/subsurface DFA) show a greater presence of fulvic acids in the microlayer. Moreover, the enrichment process is greater for the particulate phase. C/N values both in microlayer and subsurface waters are greater for DFA with respect to PFA and C/N values for DFA of microlayer are greater than that of subsurface waters. So DFA could be older than PFA, and DFA of subsurface waters younger than that of microlayer waters. For PFA S/C ratios in microlayer waters are greater than that of subsurface waters, underlining that the enrichment process is selective as regards sulphur-containing structures.     

Persistent iceberg groundings in the western Weddell Sea, Antarctica

We use the time-average of a series of satellite synthetic aperture radar (SAR) images from 2005 to 2007 to identify grounded icebergs in the western Weddell Sea. Satellite laser altimetry along repeated ground tracks confirms that regions of high mean backscatter are associated with stationary, tabular icebergs. The altimeter data also provide iceberg freeboard, from which we infer maximum ice draft assuming the lightly-grounded limit and a two-layer density model consistent with a source at Filchner-Ronne Ice Shelf. The maximum iceberg draft agrees very well with the ocean depth at a point where the bathymetry is well constrained by ship soundings. However, for an extensive region near 71°S, south of Larsen C Ice Shelf, the maximum grounding depth for several icebergs reveals the ocean to be locally more than 200 m shallower than in bathymetry products. This previously uncharted bank is expected to have a profound effect on the northward flow of the western Weddell Gyre and the cross-slope transport of offshore warm deep water towards the eastern Antarctic Peninsula ice shelves. Passive microwave data also show that sea-ice concentration is reduced in the vicinity of this group of grounded icebergs, indicating an iceberg influence on ocean/atmosphere heat and freshwater exchanges.     

Spatial distribution of 10m firn temperature in the Antarctic Ice Sheet

A database of Antarctic 10m firn temperature was constructed using available borehole temperature measurements with data quality control to extend knowledge of Antarctic climate.Slopes from a high-resolution digital elevation model and the main ice divide were used to delineate main drainage sectors across Antarctica.In each drainage sector,a quantitative relationship between temperature and latitude,longitude and altitude was established using available firn temperature data.Quantitative relationships inco...     

Ionic Liquids Increase the Catalytic Efficiency of a Lipase (Lip1) From an Antarctic Thermophilic Bacterium

Lipases catalyze the hydrolysis and synthesis of triglycerides and their reactions are widely used in industry. The use of ionic liquids has been explored in order to improve their catalytic properties. However, the effect of these compounds on kinetic parameters of lipases has been poorly understood. A study of the kinetic parameters of Lip1, the most thermostable lipase from the supernatant of the strain ID17, a thermophilic bacterium isolated from Deception Island, Antarctica, and a member of the genus Geobacillus is presented. Kinetic parameters of Lip1 were modulated by the use of ionic liquids BmimPF6 and BmimBF4. The maximum reaction rate of Lip1 was improved in the presence of both salts. The highest effect was observed when BmimPF6 was added in the reaction mix, resulting in a higher hydrolytic activity and in a modulation of the catalytic efficiency of the enzyme. However, the catalytic efficiency did not change in the presence of BmimBF4. The increase of the reaction rates of Lip1 promoted by these ionic liquids could be related to possible changes in the Lip1 structure. This effect was measured by quenching of tryptophan fluorescence of the enzyme, when it was incubated with each liquid salt. In conclusion, the hydrolytic activity of Lip1 is modulated by the ionic liquids BmimBF4 and BmimPF6, improving the reaction rate and the catalytic efficiency of this enzyme when BmimPF6 was used. This effect is probably due to changes in the structure of Lip1 induced by the presence of these ionic liquids, stimulating its catalytic activity.