Abstract. Improving the spatial and temporal coverage of volcanic records is essential to accurately quantify volcanic forcing and to provide reliable references for climate models validation. In this study, we present a new volcanic record derived from a 133 m ice core (DA2009) drilled at Dome A, Antarctica. Based on measurements of non-sea-salt sulfate concentrations, 95 volcanic events are identified. Using 15 volcanic age markers aligned with the West Antarctic Ice Sheet (WAIS) Divide ice core (WDC) record, the DA2009 core is dated to cover the past 3951 years, from 1951 BCE to 2000 CE. By comparing the DA2009 record with three Antarctic ice cores from WAIS Divide, Dome C and South Pole, 12 prominent volcanic events are recognized. The period between 1000 and 2000 CE exhibits the most intense volcanic activity of the past 4000 years. The mean snow accumulation rates calculated between adjacent age markers indicate a marked decline in accumulation at Dome A since the 13th century CE. This low-accumulation interval coincides with a pronounced cold phase on the East Antarctic Plateau, suggesting a potential connection between regional climate variability and local accumulation rates at Dome A.

This study elucidated the spatial distribution characteristics of surface snow chemistry and stable isotope composition and their influencing factors in Antarctica’s coastal region. We analyzed data from eight surface snow chemical ion transects and five surface snow stable isotope transects to examine the distributions of sea-salt ions (Na+, Cl−, Mg2+, K+), non-sea-salt ions (NO3−, methanesulfonic acid (MSA), non-sea-salt sulfate (nssSO42−), non-sea-salt Ca2+ (nssCa2+)), and the stable isotope δ18O. Concentrations of chemical ions were found to exhibit distinct source signatures. Principal component analysis indicated that the ranking of ion sources in Antarctica’s coastal areas is as follows: sea-salt aerosol transport, followed by marine biological activities and crustal dust and then atmospheric chemical reactions. Data from all transects exhibited a general pattern of diminishing δ18O with increasing distance from the coast but with marked regional differences in the δ18O–distance slope (−6.84 to −1.98‰/100 km), δ18O–altitude slope (−0.97 to −0.20‰/100 m), and δ18O–temperature slope (0.61 to 1.14‰/°C). The moisture source regions and transport pathways, local orographic uplift, and local temperature field jointly affect the differentiation of δ18O in coastal areas. The findings suggest that snow chemistry and isotopic composition in Antarctica’s coastal zones are controlled by marine source transport, biogeochemical cycling, and polar topographic and climatic processes.

The sampling and observation of subglacial lakes play a vital role in studying the physical and chemical properties as well as the microbial characteristics of water within these Antarctic subglacial lakes. Compared to existing techniques, such as deep ice core drilling and clean hot water drilling, recoverable autonomous sondes, inspired by the spinning and reeling silk behavior of spiders, offer several advantages, including lightweight design, low power consumption, and minimal external pollution. Over the past six years, Jilin University, with support from the Ministry of Science and Technology of China, has developed an environmentally friendly sampling and observation system for Antarctic subglacial lakes, utilizing a recoverable autonomous sonde. The whole system includes a melting sonde, detection and control unit, scientific load platform, and ice surface auxiliaries. Extensive laboratory and joint system tests were conducted, both on key components and the complete system, including field tests in ice lakes. The results of these tests validated the feasibility of the underlying principles, the long-term reliability of the system operation, and the cleanliness of the drilling process. Ice penetration speed up to 2.14 m/h was reached with 6~6.5 kW melting tip power and a 660 mL lake water sample was collected. The relevant design concepts and technologies of the system are expected to play an important role in the clean detection and sampling of subglacial lakes in Antarctica, Greenland, and other regions.

Antarctic sea ice plays a crucial role in regulating regional and global climate, as well as ecosystem productivity of the Southern Ocean. Since sea ice data were rare before 1978C.E., reconstruction of past sea ice conditions is of vital importance for understanding their impact on past climate change. Methanesulfonate (MSA) in Antarctic ice cores is considered a potential proxy of sea ice extent (SIE). In this study, we tested this approach by measuring the variations of MSA flux (1950-2016C.E.) in samples collected from a snowpit at Dome A, the summit of Eastern Antarctic ice sheet, and investigating its relationship with the SIE in the Southern Ocean. The result shows a significant and positive correlation between the MSA flux and the observed mean SIE in the Indian Ocean sector of the Southern Ocean from 1979 to 2016C.E. In addition, our study shows that the MSA is mainly influenced by Southern Hemisphere westerly winds (zonal winds) and katabatic winds (flowing from inland to the coast). Enhanced winds in both systems promote sea ice production in the Southern Ocean. These wind systems significantly influence the MSA cycle, stronger westerlies and katabatic winds increase MSA production, whereas meridional winds facilitate the transport and subsequent deposition of MSA at Dome A. Our findings suggest that MSA recorded in snow from Dome A could serve as a reliable proxy or reconstruction for mean SIE. Consequently, MSA in deep ice cores from Dome A offers a valuable archive for investigating past sea ice conditions in the Indian Ocean sector of the Southern Ocean, biogenic sulfur, and their climatic impacts.

Accurate observations of surface mass balance are pivotal for assessing the Antarctic Ice Sheet mass balance and its link to climate dynamics. Studying regional changes in surface mass balance is challenging due to limited on-site observations and the susceptibility of measurements from snow pits and ice cores to localized disturbances. Satellite data and short-term localized measurements suggest no significant changes or a possible increase in surface mass balance across the East Antarctic Ice Sheet in recent decades, but these findings lack large-scale validation. Here we use observations from mass balance stakes to show a significant negative surface mass balance trend along the inland transect from Zhongshan Station to the Antarctic Ice Sheet summit (Dome A) during the period 2005–2020. The mean surface mass balance trend for the inland section over the 15-year period is −2.01 ± 0.37 kg m−2 yr–2, indicating a 35.5

Conducting scientific drilling on subglacial lakes and obtaining samples of subglacial lake water holds great significance in unraveling the formation and evolution of Antarctic subglacial lakes and early Earth’s life forms. Despite various approaches to access and directly sample subglacial water and sediments, clean access and exploration of subglacial lakes remain challenging. To address this concern, Jilin University has developed the RECoverable Autonomous Sonde (RECAS) prototype. This technology enables sampling and in-situ detection of subglacial lake water while being isolated from the surface, thus minimizing the risk of pollution. Laboratory tests, including downward and upward drilling, long-running, remote-control, and cold-environment assessments, were conducted to validate the sonde’s principle and functionality. During the 38th Chinese National Antarctic Research Expedition, CHINARE (2021–2022 season), the RECAS prototype underwent testing on the flank region of Dålk glacier, 10 km from Zhongshan Station in Antarctica. Three boreholes with depths of 200.3, 183.2, and 133.5 m were successfully drilled, with the refrozen meltwater sealing the boreholes during the process. Approximately 600 mL of melted water samples were collected from each hole. Throughout the drilling tests, all systems of the RECAS prototype performed within the expected ranges.

The study of the fabric and microstructure of ice at the shear margin of the Antarctic ice sheet is of great significance for understanding the ice flow and its contributions to sea level rise. In this study, twenty-three one-meter-long ice cores were drilled from blue ice areas at the shear margin of the Dalk Glacier, Antarctica. The ice fabric and microstructure of these ice cores are analyzed using a G50 fabric analyzer. This study shows that the shallow ice cores in this region present a cluster fabric as a consequence of shear stress. The grain size decreases following the direction of the ice flow towards the exposed bedrock at the end of the glacier, due to the blocking and squeezing by the bedrock. The formation mechanism of the shallow ice layers is that the ice from the original accumulation area flows here, lifted by the bedrock and shaped by the summer ablation and denudation. The basal ice at the shear margin of the Dalk Glacier is strongly rubbed by the bedrock and demonstrates a cluster fabric. The analysis of stable water isotopes shows a weak negative correlation between shallow ice fabric and stable water isotopes with depth. Bedrock topography and shear stress have a greater influence on grain microstructure among different ice cores over long distances at shear margins.

High-resolution stable isotope records obtained from Antarctic ice cores can be used as proxies to investigate past climatic changes in Antarctica, overcoming the spatiotemporal limitations of observational and instrumental records. Here, we used a new high-resolution ice core stable isotope record (1709–2001 AD) obtained from the Lambert Glacier Basin 69 (LGB69) site and a published stable isotope record (1757–1987 AD) from coastal Princess Elizabeth Land (PEL) to reconstruct temperature variability in the coastal region of PEL over the past three centuries. The dominant moisture source region for coastal PEL is mid-high latitudes of the South Indian Ocean (SIO) and this has remained stable over the past three centuries. Owing to non-climatic noise, no statistically significant isotope‒temperature relationship can be evidenced at annual-to-decadal scales. However, the ice core δD records do enable us to reconstruct multi-decadal temperature variability in the coastal region of PEL. The temperature reconstructions showed a consistent warming trend during the 20th century, whereas the cold periods prior to the 20th century may be related to the Little Ice Age (LIA). Our reconstructions exhibit high reliability, evidenced by their agreement with previous reconstructions from PEL. We also found that annual temperature variability is related to the Southern Annular Mode (SAM), whereas multi-decadal temperature variability is related to the Indian Ocean Dipole (IOD). However, the relationship between the SAM and temperature is unclear before the 1970s. The results of this study are helpful in understanding long-term temperature changes in Antarctica and provide an important reference for the attribution of temperature changes.

Year-round precipitation in coastal East Antarctica and Antarctic Peninsula was used to investigate the seasonal patterns in sources of atmospheric perchlorate (ClO4 (-)). Although featuring distinct climates, the two locations exhibit similar annual mean and seasonal cycles of ClO4 (-) concentration, with higher values in autumn and lower concentrations in winter and spring. Tropospheric formation dominates atmospheric ClO4- in spring and summer, which is influenced by both oxidants levels and environmental conditions (e.g., air humidity). Troposp....heric ClO4 - production may also be promoted by elevated levels of oxidants brought by air mass from the interior Antarctic ice sheet in spring and summer. The autumn concentration maximum may originate from ClO4 (-) produced in the stratosphere through reactions between reactive chlorine and ozone during spring and summer. In winter, the stratospheric input may contribute to ClO4 (-) via polar stratospheric clouds sedimentation.

Refractory Black carbon (rBC) emitted from the combustion of biomass and fossil fuels plays an important role in the climate system. In this study, we established a record of the rBC concentration spanning 1932-2013 from an ice core retrieved from the Chongce ice cap of the West Kunlun Mountains in the western Tibetan Plateau. The record showed an increasing trend since the 1980s. The mean concentration of rBC was 2.66 ng g-1 before 1980 and 5.33 ng g-1 since 1980. The significant increase since the 1980s was very different from similar records from European ice cores. An analysis of atmospheric circulation and backward trajectories suggested that former USSR, the Middle East, and South Asia were the most likely source regions for the rBC deposited at the Chongce ice cap. This conclusion was also supported by the historical emission data in these regions. Phase analysis indicated that high rBC concentrations were closely associated with drought-induced biomass burning in the rBC source regions at the decadal timescale. These findings suggested that anthropogenic emissions controlled the long-term rBC trend, while the peak phases were caused from an increase of biomass burning.

Atmospheric samples and snowfall collected in coastal East Antarctica over two years are used to investigate the sources, production of atmospheric nitrate (NO3-) and its link with snowfall NO3- based upon the isotopic composition of NO3- (delta N-15, delta O-18 and Delta O-17). Snowfall and the atmosphere show similar seasonal trends in concentrations and isotopic composition of NO3-. In summer, atmospheric NO3- is closely associated with snowpack emissions of NOx from photolysis of snow NO3-. In winter, linear relationships between delta N-15 and delta O-18 (or Delta O-17) of NO3- in both snowfall and the atmosphere indicate mixing between stratospheric inputs and tropospheric sources contributing to NO3-, with stratospheric inputs contributing 55 +/- 21% of the atmospheric NO3- budget. The linear relationships suggest that the lower limits of delta N-15, delta O-18 and Delta O-17 of stratospheric-sourced NO3- are close to similar to 18, similar to 120, and similar to 45 parts per thousand, respectively. Concentration correlates well with the isotopic composition of NO3- in winter, indicating less variable contribution of tropospheric sources. A significant linear correlation between delta O-18 and Delta O-17 of NO3- suggests a mix of oxidation processes by O-3 and H2O/OH which can influence NOx cycling and the production of NO3-. Lower values of Delta O-17 of atmospheric NO3- were observed during O-3 depletion events in September, suggesting that oxygen isotopes of NO3- could be more sensitive to the changes in surface O-3 compared to BrO concentrations. Oxygen isotopic composition of NO3- in snowfall is close to that of the atmosphere throughout the year, suggesting that snowfall NO3- can relay information on oxidative chemistry of NOx in the atmosphere. Snowfall delta N-15 is close in value to that in the atmosphere during winter, but similar to 20 parts per thousand higher than that in the atmosphere during summer, possibly associated with seasonal changes in the gas-aerosol partitioning of atmospheric NO3-. This suggests that the interpretation of delta N-15 in snow needs to consider seasonal changes in sources and chemistry. (C) 2021 Elsevier B.V. All rights reserved.

冰芯记录了自然和人类活动等各种因子的变化,是研究全球气候变化和环境变化的良好载体.极地冰芯可以将高分辨率古气候记录的时间尺度延长至过去几十万年,具有重要的科学意义.近年来,极地冰芯在气候及环境记录上取得了一系列新的研究进展,但尚缺乏系统的总结.本文对极地冰芯的研究进展进行了梳理,从冰芯物理特性、冰芯氢氧同位素、可溶及不可溶物质理化特征、冰芯气体等方面进行了概述,重点关注了最新分析方法在极地冰芯中的应用.最后对极地冰芯研究的未来发展方向进行了展望,以期为今后深入开展极地冰芯气候及环境记录研究提供参考.

Interpretation of NO 3 − variability recorded in ice cores remains challenging as it can be lost from snow. Here, we present 60‐year records of NO 3 − and its isotopic composition ( δ 15 N, δ 18 O, and Δ 17 O) in snow in central Antarctica, Dome A. In the upper ∼90 cm snowpack, variations in concentration and isotopic composition of NO 3 − are dominated by photolytic loss, and δ 18 O and Δ 17 O of NO 3 − are associated with the recycling of NO x to NO 3 − in the condensed phase driven by photolysis. In the deeper snowpack (∼1960–2000), we observe prolonged trends in concentration and isotopic composition of NO 3 − , which are best explained as enhanced snow NO 3 − photolysis due to long‐term decreasing total column ozone (TCO). That is, the prolonged period of trends in NO 3 − and its isotopes in extremely low snow accumulation sites such as Dome A relay information on variations in TCO and consequently surface solar ultraviolet radiation over time.

Recent studies have suggested that water isotopologues in snow pits from remote East Antarctica can be influenced by the input of stratospheric water, which has anomalously high 17 O‐excess values. However, it remains unclear whether the 17 O‐excess records preserved in snow and ice from this region can be used to reconstruct stratosphere‐troposphere exchange (STE). In this study, we present high‐resolution 17 O‐excess records from two snow pits at Dome A, the highest point of the Antarctic ice sheet. The 17 O‐excess records show a significant positive correlation with the strength of the Brewer‐Dobson circulation (BDC), the hemispheric‐scale troposphere‐stratosphere overturn circulation. Stronger BDC leads to more stratospheric water input over Antarctica and higher 17 O‐excess, and vice versa. In addition, the 17 O‐excess records also have a significant positive correlation with the Southern Annular Mode (SAM) index, because SAM modulates Antarctic precipitation, which has a dilution effect on the stratospheric water input. The 17 O‐excess records do not show significant correlations with local temperature and relative humidity in the moisture source region. These results suggest the dominant effect of BDC on 17 O‐excess and indicate the potential for using 17 O‐excess records in ice cores from remote sites in East Antarctica for reconstructing long‐term variations of STE, and understanding their mechanisms and climate effects.

南极冰芯记录着过去气温、降水等气候环境参数以及影响其变化的太阳活动、火山作用等各种因子变化,是研究古气候、古环境变化及其影响机制的良好载体.东南极LGB69冰芯高分辨率的地球化学分析表明:①该冰芯的水当量年平均积累率高达259 mm/a,利用δ18O和Na+季节性变化和火山喷发标志层,通过数年层的方法确定其沉积时间为290 a(1712-2001年)±2 a;②该冰芯δ18O与邻近的戴维斯站气温距平5年滑动平均值(1968-2001年)之间具有良好的正相关关系,是有效的气温代用指标,1712-2001年该地区气温是一个波动变暖的过程,划分为4个阶段,小冰期结束于1914年,20世纪5年滑动平均气温距平年平均值较小冰期末次冷阶段升高0.30C;③Morlet小波分析表明,1712-2001年该冰芯δ18O(气温)和积累率(降水量)均存在约11年、约22年和约60年的共同周期,多重时间周期的嵌套表明其对气候变化非常敏感.上述研究结果为进一步重建南极气候冷暖、降水序列变化,以及研究太阳活动、火山作用等因子对气候变化影响的内在规律奠定了基础.

Perchlorate (ClO4) is harmful to human health, and knowledge on the levels and sources of natural ClO4 in different environments remains rather limited. Here, we investigate ClO4 in aerosol samples collected along a cross-hemisphere ship cruise between China and Antarctica and on a traverse between coastal East Antarctica and the ice sheet summit (Dome Argus). Perchlorate concentrations range from a few to a few hundred pg m 3. A clear latitudinal trend is found, with elevated ClO4- concentrations near populated areas and in the southern midhigh latitudes. Spatial patterns of atmospheric ClO4- over oceans near the landmasses support that terrestrial ClO4- is not transported efficiently over long distances. In the southern mid-latitudes, higher ClO4- concentrations in March than in November-December may be caused by significant stratospheric inputs in March. Perchlorate concentrations appear to be higher in the warm half than in the cold half of the year in the southern high latitudes, suggesting seasonal difference in main atmospheric sources. ClO4- may be formed in the reactions between chlorine free radical (Cl center dot) and ozone (O-3) in the stratosphere when Antarctic ozone hole occurs during September-October. And the stratosphere-produced ClO4 is moved to the boundary layer in several months and may be responsible for the high ClO4 concentrations in the warm half of the year. Perchlorate produced by photochemical reactions between O-3 and Cl center dot in the Antarctic stratosphere is likely responsible for the higher ClO4 concentrations in Antarctica than in Arctic.

To better understand snow chemistry in different environments across the Antarctic ice sheet, we investigated snow ions on a traverse from the coast to Dome A. Results show that the non-sea-salt (nss) fractions of K+, Mg2+, and Ca2+ are mainly from terrestrial particle mass and nssCl− is associated with HCl. Spatially, the non-sea-salt fractions of ions to the totals are higher in the interior areas than on the coast, and seasonally, the proportions are higher in summer than in winter. Negative nssSO42- on the coast indicates sea salts from the sea ice, and marine biogenic emissions dominate snow SO42- in interior areas throughout the year.

The ice core from polar ice sheet is one of the most valuable archives of past climate and environment. The ice core visual stratigraphy, based on optical scanning analysis, provides the most intuitive information of the micro-particles and/or air bubbles in the ice. At present, only few labs can perform high quality visual stratigraphy analysis in the world. Here, we develop an ice core slice scanning tool based on line-scan camera. The machine uses the high-resolution characteristics of the line-scan camera to complete high-resolution imaging of the ice core slices through linkage with the linear light sources. A motor drive and control system is developed to complete the uniform scanning control of the line-scan camera and light sources. A special control program and human-computer interaction interface are developed to realize the parameter setting, motor control and imaging result display. The test results show that the proposed ice core slice scanning tool meets the design requirements and its imaging results are significantly better than area-scan cameras under the same conditions.

我国于2012年1月在南极Dome A区域正式开展实施了南极昆仑站深冰芯科学钻探工程,截至2021年,钻孔深度已达803.54 m.该工程是我国第一个深冰芯钻探工程,也是国际上第一个在Dome A地区开展的深冰芯钻探项目.本文介绍了昆仑站深冰芯科学钻探工程实施的整体情况,对过去近10年的钻探活动以及取得的成果和经验进行了总结,以期为后续的深冰芯钻探工作提供理论和经验指导.