Impact of transparent exopolymer particles on the dynamics of dissolved organic carbon in the Amundsen Sea,Antarctica

The Southern Ocean is an important carbon sink pool and plays a critical role in the global carbon cycling.The Amundsen Sea was reported to be highly productive in inshore area in the Southern Ocean.In order to investigate the influence of transparent exopolymer particles(TEP)on the behavior of dissolved organic carbon(DOC)in this region,a comprehensive study was conducted,encompassing both open water areas and highly productive polynyas.It was found that microbial heterotrophic metabolism is the primary process responsible for the production of humic-like fluorescent components in the open ocean.The relationship between apparent oxygen utilization and the two humic-like components can be accurately described by a power-law function,with a conversion rate consistent with that observed globally.The presence of TEP was found to have little impact on this process.Additionally,the study revealed the accumulation of DOC at the sea surface in the Amundsen Sea Polynya,suggesting that TEP may play a critical role in this phenomenon.These findings contribute to a deeper understanding of the dynamics and surface accumulation of DOC in the Amundsen Sea Polynya,and provide valuable insights into the carbon cycle in this region.

Evaluating Parameterizations for Turbulent Fluxes over the Landfast Sea-Ice Surface in Prydz Bay, Antarctica

It is crucial to appropriately determine turbulent fluxes in numerical models.Using data collected in East Antarctica from 8 April to 26 November 2016,this study evaluates parameterization schemes for turbulent fluxes over the landfast seaice surface in five numerical models.The Community Noah Land Surface Model with Multi-Parameterizations Options(Noah_mp)best replicates the turbulent momentum flux,while the Beijing Climate System Model(BCC_CSM)produces the optimum sensible and latent heat fluxes.In particular,two critical issues of parameterization schemes,stability functions and roughness lengths,are investigated.Sensitivity tests indicate that roughness lengths play a decisive role in model performance.Based on the observed turbulent fluxes,roughness lengths over the landfast sea-ice surface are calculated.The results,which can provide a basis for setting up model parameters,reveal that the dynamic roughness length(z0m)increases with the increase of frictional velocity(u*)when u*≤0.4 m s^(−1) and fluctuates around 10^(−3 )m when u*>0.4 m s^(−1);thermal roughness length(z0t)is linearly related to the temperature gradient between air and sea-ice surface(ΔT)with a relation of lg(z0t)=−0.29ΔT−3.86;and the mean water vapor roughness length(z0q)in the specific humidity gradient(Δq)range ofΔq≤−0.6 g kg^(−1) is 10^(−6) m,3.5 times smaller than that in the range ofΔq˃−0.6 g kg^(−1).

Chemical composition of natural waters at Broknes Peninsula, Larsemann Hills, Antarctica

The article contributes to the study of the content of major and trace elements in various types of natural waters of the Broknes Peninsula,Larsemann Hills,Antarctica collected in January–February 2014 and 2020 during the 7th and 12th Belarusian Antarctic Expeditions.Samples of old(13 samples)and newly fallen snow(5),lakes(23)and groundwater(8)were analyzed.The content of 25 major and trace elements was determined using ICP-MS method,main anions was determined by titrimetric and turbidimetric methods.Good similarity chemical composition of snow,groundwater and lake waters in spite of differences in the content of major ions and trace elements has been obtained.The influence of marine salts on natural waters are analyzed,and their accumulation in lake waters especially in the endorheic small and shallow lakes in spite of ultra-oligotrophic atmospheric precipitates are shown.The spatial heterogeneity of groundwater and temporal and spatial heterogeneity of lake waters have been demonstrated.The results are important for understanding the variabilities of major and trace elements content in snow,groundwater and lake waters,and their relationship,as well as for identifying trends in their change,taking into account anthropogenic loads in the region and climate change.

Call for Papers:Special Issue“Past and Present Climatic Change in Antarctica:Geological Proxies and Biological Processes”

Dear colleagues,We would like to invite you to participate in the special issue of the journal Advances in Polar Science(ISSN 1674-9928)entitled“Past and Present Climatic Change in Antarctica:Geological Proxies and Biological Processes”,which is expected to be published in March 2024 as general issue(Vol.35,No.1).We are honored to invite Dra.Carolina Acosta Hospitaleche,Dr.Javier N.Gelfo,Dr.Marcelo Reguero,Dra.Adolfina Savoretti and Dra.

Phaeocystis globosa与Phaeocystis antarctica叶绿体psbA基因的比较

测定了2株球形棕囊藻PhaeocystisglobosaP1、P2的 psbA基因序列 ,发现得到的2个序列完全相同。以P2序列对比分析了P.globosa和P.antarctica的psbA基因在DNA序列、氨基酸序列和RNA二级结构上的差异性 ,发现2种棕囊藻psbA基因DNA序列和氨基酸序列非常保守 ,无插入/缺失 ,其核苷酸和氨基酸变异率分别为1.88 %和1.13 %。与核基因核苷酸的碱基替换不同 ,psbA基因核苷酸的碱基替换主要发生在密码子的第1位上 ,且不引起氨基酸的变化 ,引起氨基酸变化的碱基替换都发生在密码子的第2位和第3位上。在RNA二级结构上两序列的1～4茎环结构完全相同 ,表现出明显的棕囊藻属的特异性 ,其它结构区域差异较大 ,种间差异表现明显。由于 psbA基因DNA序列和氨基酸序列非常保守 ,可能不适宜棕囊藻属的系统发育分析。但其RNA二级结构可能对于棕囊藻的分子分类有一定的参考价值。

吸附-聚合物修饰组合固定化Candida antarctica脂肪酶研究

通过吸附法联合PEG非共价修饰,研发了一种固定化南极假丝酵母脂肪酶(Candida antarctica lipase)的新方法,可以有效提高固定化酶在非水介质中的催化活性。最佳固定化条件为硅藻土:酶粉(W/W)=8,PEG4000:酶粉(W/W)=0.6,缓冲液pH7.5。采用三油酸甘油酯与甲醇的转酯化反应,测定了固定化酶的转酯活性。结果表明,固定化酶同时加入PEG进行非共价修饰,可显著提高固定化酶的转酯活力。PEG修饰的固定化酶转酯比活是未经PEG修饰的固定化酶的4.1倍,转酯酶活回收率为604.8%,说明PEG两性分子的特性对制备用于非水介质的固定化酶有重要作用。该固定化方法可显著提高Candida antarctica脂肪酶在非水介质中的催化效率,且固定化方法简单、成本低,具有工业应用价值。

The sediments of lake on the Ardley Island, Antarctica: Identification of penguin-dropping soil

During CHINARE 15(Dec. 1998 Mar. 1999), a lake core 67.5 cm in length, was sampled in Y2 lake, which is located on the Ardley Island, Antarctica. The concentrations of some chemical elements in Y2 lake sediments were analyzed. According to comparative research on elementary characters of sediments in Antarctic West Lake, fresh penguin dropping as well as guano soil on the Ardley Island and Pacific Island in South China Sea, it presents that the Y2 lake sediments were ameliorated by penguin dropping. The result of element cluster analysis shows that the type elements in the sediment impacted by penguin dropping include Sr,F,S,P,Ca,Se,Cu,Zn and Ba. This can provide a base for further interpreting the climatic and environmental event recorded in the sediment.

Variation of Stable Isotopes in Surface Snow along a Traverse from Coast to Plateau's interior in East Antarctica and Its Climatic Significance

The variations of stable water isotopes of surface snow in east Antarctic Ice Sheet, are discussed by a total of 251 samples, which were taken along a 330 km traverse from Zhongshan Station to the outer edge of the Antarctic plateau and from four snow pits excavated along the route. Analyzing results of the samples showed the expected linear relationship between the parameters ?D and ?18O with slope S1 and intercept d1. When the data set was examined using a sliding window with a width of 5 samples, it was found that there were two areas with different ratios of S1 and d1. The boundary between these two areas occurred at an elevation of about 2,000 m, suggesting two different sources of water vapour. Nearly half (47%) of the fresh-snow samples had negative deuterium excess (d=?D? 8?18O) values, but few of the snow pit samples did, suggesting that variations of ? are quickly smoothed by isotopic diffusion in the near-surface firn. Analysis of the phase relationship between ?D and deuterium excess in the snow pit stratigraphies showed that they were mostly in phase from Jan. 1994 to Sept. 1995, but mostly out of phase from Sept. 1995 to Jan. 1997.

Spatial and temporal evolution of landfast ice near Zhongshan Station, East Antarctica, over an annual cycle in 2011/2012

Annual observations of first-year ice(FYI) and second-year ice(SYI) near Zhongshan Station, East Antarctica,were conducted for the first time from December 2011 to December 2012. Melt ponds appeared from early December 2011. Landfast ice partly broke in late January, 2012 after a strong cyclone. Open water was refrozen to form new ice cover in mid-February, and then FYI and SYI co-existed in March with a growth rate of 0.8 cm/d for FYI and a melting rate of 2.7 cm/d for SYI. This difference was due to the oceanic heat flux and the thickness of ice,with weaker heat flux through thicker ice. From May onward, FYI and SYI showed a similar growth by 0.5 cm/d.Their maximum thickness reached 160.5 cm and 167.0 cm, respectively, in late October. Drillings showed variations of FYI thickness to be generally less than 1.0 cm, but variations were up to 33.0 cm for SYI in March,suggesting that the SYI bottom was particularly uneven. Snow distribution was strongly affected by wind and surface roughness, leading to large thickness differences in the different sites. Snow and ice thickness in Nella Fjord had a similar "east thicker, west thinner" spatial distribution. Easterly prevailing wind and local topography led to this snow pattern. Superimposed ice induced by snow cover melting in summer thickened multi-year ice,causing it to be thicker than the snow-free SYI. The estimated monthly oceanic heat flux was ～30.0 W/m2 in March–May, reducing to ～10.0 W/m2 during July–October, and increasing to ～15.0 W/m2 in November. The seasonal change and mean value of 15.6 W/m2 was similar to the findings of previous research. The results can be used to further our understanding of landfast ice for climate change study and Chinese Antarctic Expedition services.

LENGTH FREQUENCY ANALYSIS OF PLEURAGRAMMA ANTARCTICUM,ELECTRONA ANTARCTICA,PROTOMYCTOPHUM BOLINI

British Antarctic Survey(BAS)data collected near the Antarctic Peninsula area were used in this1988/1989 study on the length frequency of three Antarctic fish species(Pleuragramma antarcticum,Electrona antarctica and Protomyctophum bolini)showing that the standard length(SL)of P.Antarcticumranged from 26.0 mm to 161.0 mm,that the 26.0 mm to 54.0 mm SL juveniles could be considered tobe the age group 1 fish,and that the SL of E.antarctica ranged from 39.4 mm to 89.7 mm for themales and 48.0 mm to 118.0 mm for the females,which may contain at least 6 age groups.This ismore than previously thought.P.Bolini had 29.2 mm to 60.2 mm SL and complicated age com-position.

Variations of Atmospheric Carbon Dioxide Concentration and Greenhouse Effect at Syowa Station (69°00'S, 39°35'E), Antarctica

On the basis of the analysis of atmospheric carbon dioxide concentration variations and the annual mean air temperature at Syowa Station, Antarctica in the period of 1984-1988, the following results are easily obtained:(1) The annual mean values of the atmospheric carbon dioxide concentration are gradually increased and equal to 342.59, 343.80, 345.15, 346.83 and 348.82 ppmv for 1984, 1985, 1986, 1987 and 1988, respectively. Its annual increase rates are 1.21, 1.35, 1.68 and 1.99 ppmv/yr. For 1984-1985, 1985-1986, 1986-1987 and 1987-1988, respectively and are raised year by year.The seasonal variations are observed and the maximum concentration is in spring and the minimum one is in late-summer or early-autumn.(2)The increasing tendency of the concentration of the atmospheric carbon dioxide is consistent with that of the a.ir temperature.

Atmospheric River Signatures in Radiosonde Profiles and Reanalyses at the Dronning Maud Land Coast,East Antarctica

Atmospheric rivers(ARs)are an important component of the hydrological cycle linking moisture sources in lower latitudes to the Antarctic surface mass balance.We investigate AR signatures in the atmospheric vertical profiles at the Dronning Maud Land coast,East Antarctica,using regular and extra radiosonde measurements conducted during the Year of Polar Prediction Special Observing Period November 2018 to February 2019.Prominent AR events affecting the locations of Neumayer and Syowa cause a strong increase in specific humidity extending through the mid-troposphere and a strong low-level jet(LLJ).At Neumayer,the peak in the moisture inversion(up to 4 g kg^?1)is observed between 800 and 900 hPa,while the LLJ(up to 32 m s^?1)is concentrated below 900 hPa.At Syowa the increase in humidity is less pronounced and peaks near the surface,while there is a substantial increase in wind speed(up to 40 m s?1)between 825 and 925 hPa.Moisture transport(MT)within the vertical profile during the ARs attains a maximum of 100 g kg?1 m s?1 at both locations,and is captured by both ERA-Interim and ERA5 reanalysis data at Neumayer,but is strongly underestimated at Syowa.Composites of the enhanced MT events during 2009?19 show that these events represent an extreme state of the lower-tropospheric profile compared to its median values with respect to temperature,humidity,wind speed and,consequently,MT.High temporal-and vertical-resolution radiosonde observations are important for understanding the contribution of these rare events to the total MT towards Antarctica and improving their representation in models.

Distribution of dissolved organic carbon in and near the Prydz Bay, Antarctica

During the 16th Chinese National Antarctic Research Expedition (CHINARE) (from November 1999 to April 2000) seawater samples were collected for (DOC) determination in the Prydz Bay and its nearby sea areas. DOC concentrations were determined by high temperature catalytic oxidation (HTCO) method. The results shows that DOC concentrations in the upper water column (0～100 m) range from 14.3 to 181.1 μmol/dm 3, with averaging 52.5 μmol/dm 3(n=55).These values are slightly higher than those reported for the Ross Sea, the Pacific Ocean and others. Profiles of DOC concentration in the study areas show a decreasing concentration with increasing depth in the upper 100 m, which is related to biological activities in the water column. DOC concentrations below 100 m are relatively constant with a mean of 40.4 μmol/dm 3. These DOC are unactive for physical and biological activities and are called refractory DOC. Concentration of the refractory DOC in the study area is consistent with the previous reported values for the Southern Ocean, which is about 41 μmol/dm 3.Based on the difference between the measured DOC concentration and the refractory concentration, the excess DOC concentration in the upper column can be calculated at every station. The excess DOC shows a spatial variability with a higher excess in the north of 64°S and little excess in the south of 64°S. In conclusion, DOC concentrations in the Prydz Bay and its nearby sea areas are consistent with the previous reported values in the Southern Ocean, which show a low DOC concentration with respect to the other oceans. Distribution of surface DOC concentrations in the study areas shows an increase from the southwestern to the northeastern, which is ascribed to the northern spread of continental shelf water from the Prydz Bay in summer. Contents of DOC and their distribution in the Prydz Bay and its nearby sea areas are mainly controlled by physical and biological processes.

Concentration level of heavy metals in the Great Wall Bay， Antarctica in austral summer

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Organic contamination in the Great Wall bay,Antarctica in austral summer

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Sea Salt Sodium Record in a Shallow Ice Core from East Antarctica as a Potential Proxy of the Antarctic Sea Ice Extent in Southern Indian Ocean

Antarctic sea ice has experienced an increasing trend in recent decades,especially in the Ross Sea and Indian Ocean sectors.Sea ice variability affects greatly the maritime airmass transport from high latitude to Antarctic continent.Here we present a new ice core record of sea salt sodium(ssNa+)concentration at annual-resolution in the Princess Elizabeth Land spanning from 1990 to 2016,showing that this marker could be used as a potential proxy for reconstructing the sea ice extent(SIE)in the Southern Indian Ocean(SIO)given their significant correlation(R=-0.6,P<0.01)over the past 27 years.The correlation and composite analyses results show that the ssNa^+at the 202 km inland from Zhongshan Station and the SIE changes in SIO are closely related to the Indian Ocean Dipole(IOD)and Southern Annular Mode(SAM).The northward wind in central SIO occurs during positive IOD and the strengthened westerlies occurs during positive SAM,both of which favor increased sea ice in SIO and lead to the decreased ssNa^+concentration at the coastal site.

Seismic Imaging of the Upper Mantle under the Erebus Hotspot in Antarctica

P-wave velocity images are determined under the Mount Erebus hotspot,Antarctica by using teleseismic tomography.Our results show a prominent low-velocity(low-v)anomaly of nearly circular symmetry(about 250-300 km in diameter)to about 200 km depth under the Mount Erebus volcanic region,which further extends down to～400 km as a narrow tilted column.The observed low-v anomaly beneath the Mount Erebus volcano can be an expression of a thermal anomaly of deep origin.

An assessment of the impacts of diesel power plants on air quality in Antarctica

This study assessed the effects of diesel generators on air quality in the Antarctic.These devices are the primary energy sources for Antarctic research stations and the main stationary sources of anthropogenic emissions in this region.Taking the Vecherny Oasis,Enderby Land,East Antarctica as an example,NOx,SO2 and PM10 emissions were estimated and surface concentrations of these same pollutants as well as the dry deposition of PM10 were calculated for various periods of exploration of the oasis,based on generator capacities.Estimated values were compared with air quality standards and background air concentrations.The areas associated with increased maximum hourly surface concentrations of SO2,NO2 and PM10 over the past 30 a were found to have been reduced by factors of 4355,916 and 1327,respectively.The region affected by increased maximum monthly PM10 deposition has been reduced by a factor of 7.Emissions,surface concentrations and dry depositions in the Vecherny Oasis were calculated for diesel generators in the same power range as used at Antarctic research stations.The most powerful diesel generator currently scheduled to be installed in this region was predicted to generate maximum hourly NO2 concentrations above 50μg m^- 3,which is 13 times greater than current levels.The area over which the PM10 deposition rate will exceed 10 mg m^- 2 month 1 will be increased by a factor of 40.The technique employed herein has been demonstrated to be applicable to the preliminary assessment of stationary sources of pollutant emissions in Antarctica,including retrospective assessments.

Stenian A-type granitoids in the Namaqua-Natal Belt,southern Africa,Maud Belt,Antarctica and Nampula Terrane,Mozambique:Rodinia and Gondwana amalgamation implications

We carried out SHRIMP zircon U-Pb dating on A-type granitic intrusions from the Namaqua-Natal Province,South Africa,Sverdrupfjella,western Dronning Maud Land,Antarctica and the Nampula Province of northern Mozambique.Zircon grains in these granitic rocks are typically elongated and oscillatory zoned,suggesting magmatic origins.Zircons from the granitoid intrusions analyzed in this study suggest^1025-1100 Ma ages,which confirm widespread Mesoproterozoic A-type granitic magmatism in the Namaqua-Natal(South Africa),Maud(Antarctica)and Mozambique metamorphic terrains.No older inherited(e.g.,~2500 Ma Achean basement or^1200 Ma island are magmatism in northern Natal)zircon grains were seen.Four plutons from the Natal Belt(Mvoti Pluton,Glendale Pluton,Kwalembe Pluton,Ntimbankulu Pluton)display 1050-1040 Ma ages,whereas the Nthlimbitwa Pluton in northern Natal indicates older 1090-1080 Ma ages.A sample from Sverdrupfjella,Antarctica has^1091 Ma old zircons along with^530 Ma metamorphic rims.Similarly,four samples analysed from the Nampula Province of Mozambique suggest crystallization ages of^1060-1090 Ma but also show significant discordance with two samples showing younger^550 Ma overgrowths.None of the Natal samples show any younger overgrowths.A single sample from southwestern Namaqualand yielded an age of^1033 Ma.Currently available chronological data suggest magmatism took place in the Namaqua-Natal-MaudMozambique(NNMM)belt between^1025 Ma and^1100 Ma with two broad phases between^1060-1020 Ma and 1100-1070 Ma respectively,with peaks at between^1030-1040 Ma and^1070-1090 Ma.The age data from the granitic intrusions from Namaqualand.combined with those from Natal,Antarctica and Mozambique suggest a crude spatial-age relationship with the older>1070 Ma ages being largely restricted close to the eastern and western margins of the Kalahari Craton in northern Natal,Mozambique.Namaqualand and WDML Antarctica whereas the younger<1060 Ma ages dominate in southern Natal and western Namaqualand and are largely restricted to the southern and possibly the western margins of the Kalahari Craton.The older ages of magmatism partially overlap with or are marginally younger than the intracratonic Mkondo Large lgneous Provinee intruded into or extruded onto the Kalahari Craton,suggesting a tectonic relationship with the Maud Belt.Similar ages from granitic augen gneisses in Sri Lanka suggest a continuous belt stretching from Namaqualand to Sri Lanka in a reconstituted Gondwana,formed during the terminal stages of amalgamation of Rodinia and predating the East African Orogen.This contiguity contributes to defining the extent of Rodinia-age crustal blocks,subsequently fragmented by the dispersal of Rodinia and Gondwana.