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Atmospheric gases trapped in polar ice have been used to reconstruct polar and global climate changes, providing better time resolution when less diffused. Experiments have shown that gas diffusion...

Polar snow pits or ice cores preserve valuable information derived from the atmosphere on past climate and environment changes. A 1.57-m snow-pit record from the coastal site (Styx Glacier) in eastern Antarctica covering the period from January 2011 to January 2015 was discussed and compared with meteorological variables. The dominant contribution of the deposition of sea-salt aerosols due to the proximity of the site to the ocean and processes of sea ice formation was revealed in the ionic concentrations. Consistent seasonal peaks in δ18O, δD, MSA, , and indicate the strong enhancement of their source during warm periods, whereas the sea-salt ions (Na+, K+, Mg2+, Ca2+, Cl−, and ) exhibit a distinct distribution. Monthly mean δ18O positively correlates with the air temperature record from an automatic weather station (AWS) located in the main wind direction. Despite the shortness of the record, we suspect that the slight depletion of the isotopic composition and lowering of the snow accumulation could be related to the cooler air temperature with the decrease of open sea area. Consistency with previous studies and the positive correlation of sea-salt ions in the snow pit indicate the relatively good preservation of snow layers with noticeable climate and environmental signals [e.g., changes in sea ice extent (SIE) or sea surface temperature]. We report a new snow-pit record, which would be comparative and supportive to understand similar signals preserved in deeper ice cores in this location.

Ice coring in blue ice areas (BIAs) serves as an alternative to deep ice core drilling, allowing collection of large-sized old ice samples in a cost-effective way because old ice samples are outcropped to the surface. However, the stratigraphy in many blue ice areas can be complicated due to complex ice flows. Based on ice layers defined by dust bands and ground penetration radar (GPR) surveys, we show that Larsen BIA has a surface transect of ice with an undisturbed horizontal stratigraphy from mid- to downstream side ice. However, the upstream ice exhibits a potential repetition of ages on scales of tens of meters. Correlating δ18Oice, δ18Oatm, and CH­4 records of Larsen ice with existing ice core records indicates that the analyzed gas age and ice age ranges between 9.2–23.4 ka BP and 5.6–24.7 ka BP, respectively. Radiometric 81Kr dating of one of the cores confirms the estimated gas ages within uncertainty. A tentative reconstruction based on a simple analytical framework suggests a warming of 15 ± 5 ℃ during the last deglaciation that we attribute to the retreat of the Ross Ice Shelf, and an increase in snow accumulation by a factor of 1.7–4.6 that we attribute to the increased penetration of snow-bearing storms. Exact estimation of the original deposition site and updated ice ages may enhance the tentative climate reconstructions in future studies. Our study shows that BIAs in Northern Victoria Land may contribute to obtain high-quality paleoclimate proxy records through the last deglaciation.

Blue ice areas (BIAs) allow for the collection of large-sized old ice samples in a cost-effective way because deep ice outcrops and make old ice samples available close to the surface. However, most chronostratigraphy studies on blue ice are complicated due to fold and fault structures. Here, we report a simple stratigraphy of ice from the Larsen BIA, Antarctica, making the area valuable for paleoclimate studies. Ice layers defined by dust bands and ground penetration radar (GPR) surveys indicate a monotonic increase in age along the ice flow direction on the downstream side, while the upstream ice exhibits a potential repetition of ages on scales of tens of meters, as shown in the complicated fold structure. Stable water isotopes (δ18Oice and δ2Hice) and components of the occluded air (i.e., CO2, N2O, CH4, δ15N-N2, δ18Oatm (= δ18O-O2), δO2/N2, δAr/N2, 81Kr and 85Kr) were analyzed for surface ice and shallow ice core samples. Correlating δ18Oice, δ18Oatm, and CH4 records of Larsen ice with existing ice core records indicates that the gas age at shallow coring sites ranges between 9.2–23.4 ka BP and ice age for entire surface sampling sites between 5.6–24.7 ka BP. Absolute radiometric 81Kr dating for the two cores confirms the ages within acceptable levels of analytical uncertainty. Our study demonstrates that BIA in northern Victoria Land may help researchers obtain high-quality records for paleoclimate and atmospheric greenhouse gas compositions through the last deglaciation.

Anthropogenic plutonium (Pu) in the environment is a result of atmospheric nuclear testing during the second half of the 20th century. In this work, we analyzed a 4-meter deep Antarctic Plateau snowpack characterized by a low snow accumulation rate and negligible snow impurities. These sample conditions enabled us to measure the snowpack Pu fallout by applying inductively coupled plasma sector field mass spectrometry to a few mL of snow melt without purification or preconcentration. Pu concentrations in the reconstructed Pu fallout record for the period after 1956 CE increased and decreased in agreement with past atmospheric nuclear testing. Two peaks and two dips associable with historical events were observed, and the highest peak in 1964(±1) CE approximately coincided with the maximum concentration of non-sea-salt sulfate caused by the Mt. Agung eruption in 1963 CE. Enhanced Pu fallout in the 1970s was attributed the geographical proximity of the Southern Hemispheric nuclear test sites. Our results suggest that by improving the instrumental sensitivity and precision, the potential of the Antarctic ice sheet as an archive of Pu fallout can be further explored and utilized for understanding atmospheric dispersion and for dating ice cores.

Among the paleoclimate archives, we may take advantage of ice cores to directly measure greenhouse compositions of ancient air. Nevertheless, ice cores from deep drilling projects recover limited amount of ice for a given time period and hence limiting the studies that need an extensive amount of ice such as trace gas isotopes. In contrast, blue ice areas (BIAs) may provide a large amount of ancient ice outcropped at the surface. However, ice flow makes the blue ice stratigraphy complicated in many areas, and accordingly makes it difficult to reconstruct a continuous stratigraphy. Recently, the oldest ice was discovered at Allan Hills BIA (about 2.7 Ma). However, the stratigraphy is not continuous for the older part. Here we show preliminary results from Larsen Glacier, East Antarctica. The Ground Penetrating Radar (GPR) results show parallel ice layers near the surface with dips of 1-5° and indicate that the ice thickness ranges of 200–400 m. δDice of a vertical core sample matches well with that in the horizontally spaced surface ice samples. Greenhouse gas concentrations are significantly altered at shallow depths of < ~4.5 m. The δ18Oatm, CH4 concentration and stable isotopes of ice (δ18Oice, δDice) indicate that the Larsen BIA cover the Last Glacial Termination at the studied sites. 81Kr ages, corrected by 85Kr for the modern air contamination, are less than 54 ka, supporting the ages constrained by the other chemistry data.

A lead (Pb) isotopic record, covering the two oldest glacial-interglacial cycles (~572 to 801 kyr ago), from the European Project for Ice Coring in Antarctica Dome C ice core provides isotopic evidence for the provenance of dust in deep Antarctic ice prior to the Mid-Brunhes Event (MBE), ~430 kyr ago, characterized by less warm interglacials. The isotopic signatures suggest Patagonia and central-western Argentina (CWA) as the primary sources of dust in central East Antarctica during both pre-MBE glacials and interglacials, in concert with an equatorward shift of the southern westerly winds (SWW). The contribution from extra-Antarctic volcanic emissions appears to be important for non-dust Pb in the pre-MBE interglacial and intermediate climates, most likely due to the reduction of wet removal efficiency with a weakening of the hydrologic cycle. Our results show a close coupling of the Southern Hemisphere atmospheric circulation patterns to climatic conditions prior to the MBE.

In this study, insoluble microparticles from four discrete layers of ice-cores drilled out from the East Rongbuk glacier of the Himalayas were characterized on a single particle basis by scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM/EDX) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) imaging. The combined application of the two single particle analytical techniques for the analysis of the same individual particles provided complementary information, i.e., their elemental compositions and morphology by SEM/EDX and their molecular species, functional groups, and crystallinity by ATR-FTIR imaging, which is crucial for the definite identification of the mineral species including their polymorphs. The results showed that the integrated signatures of volcanic ash (VA), involving their mineralogical characteristics for silica polymorphs, vitreous nature of silica and silicate particles, chemical heterogeneity within the micrometer sized particles, and unique morphology, can be used to clearly differentiate micrometer sized VA from the mineral dust of a soil origin on a single-particle basis. The different mineralogical characteristics among the volcanic samples would be due to their association with different volcanic eruptions.

A snow pit samples contain information of atmospheric composition and weather condition for recent years. In this study, water isotope ratio and concentrations of major ions and rare earth elements (REE) were determined from a 2 m snow pit sampled at 5 cm intervals at Hercules Neve in northern Victoria Land, Antarctica (73° 03'S, 165° 25'E, 2900m). The water stable isotope ratios range from -45.10 to -29.51 ‰ for δ18O and from 355.8 to -229.2 ‰ for δD. From their clear seasonality, the snow pit is expected to cover the period of 2012–2015. The REE patterns reveal that there exist at least two distinct sources of terrestrial aerosols; One that makes superior contribution when sea salt input is high is likely located closer than another.

Ice cores provide records of past aerosol composition and have been used to reconstruct the relative contribution of different emission sources changing in time. A precise age scale is essential to achieve this goal, for which annual layer counting of seasonal cycles in water stable isotope ratios (δ18O and δD) and major ion concentrations have been basically utilized. Introducing additional time markers are helpful for reducing the uncertainty of the depth-age scale, and the fallout of volcanic products has offered useful time markers when they are well-dated. Here, we report lead isotope ratios (206Pb/207Pb and 208Pb/207Pb) and concentrations of thallium (Tl) and major ions in a shallow ice core from the Styx Glacier (73°51 S, 163°41 E) in the Victoria Land, Antarctica, analyzed for discriminating volcanic products of the 1815 AD Tambora eruption, Indonesia from local volcanic inputs. Mechanically decontaminated 19 inner core pieces between the depth interval 40.8 – 42.4 m were analyzed. The results show that the increases of volcanic SO42- input are accompanied by either (1) input of more-radiogenic lead (higher 206Pb/207Pb) and Tl or (2) relatively 208Pb enriched lead. These results suggest that the Tambora volcanic input is overprinted by local volcanic aerosol input and that the isotope-based assessment of the Pb sources can help to discriminate between remote and local components of the volcanic input signals recorded in Victoria Land glaciers.

To evaluate recent changes in anthropogenic Pb pollution and its sources and origins in Antarctica, Pb and Ba concentrations and Pb isotopic compositions were determined in a continuous series of 40 snow samples from a 2-m deep snow pit, covering 4 full years from 2011/12 summer to 2015/16 summer, at the Hercules Névé plateau in Victoria Land, Antarctica. The results show that more than 90% of the atmospheric Pb deposited in Victoria Land was of noncrustal origin. This result implies the persistence of a significant human impact on the atmospheric cycle of Pb in the most remote places on Earth, despite a substantial reduction in anthropogenic Pb emissions in the Southern Hemisphere during recent years. The Pb isotopic fingerprints indicate that South America, particularly Brazil and Chile, has become a major source of anthropogenic Pb reaching Victoria Land. Our data highlight the need for both national and international measures to further reduce Pb emissions.

Three different ice core samples from Antarctica were analyzed to identify activity concentrations of radioactive isotopes. Tracking migration of radioactive isotopes to Antarctica can provide a key clue to understand global environmental changes caused by radiation exposures because the Antarctic ice cores can preserve unique characteristics of various environmental conditions. We are particularly interested in the 137Cs nucleus, because it is closely related to radiation exposure from nuclear power plant accidents and nuclear bomb tests. With its half life of 30.17±0.03 years, 137Cs can also be used to assess the age of sedimentation occurring after around the year 1945. We selected three ice core samples, called Tarn8, Styx27, and H25, from different time periods; the Tarn8 sample is known to be from earlier than ~ 1000 AD, the Styx27 sample is approximately from the year 1945, and the H25 sample is from the year 2012. Radioactive isotope measurements of the ice core samples were performed using a 100% HPGe detector at Cheongpyeong Underground Radiation Laboratory (CURL). We measured the activity of 137Cs in the H25 sample to be 0.98 ± 0.82 mBq/kg. Although the activity has a large uncertainty mainly due to the limited sample quantity, the 137Cs isotopes in the Antarctic ice core were measured for the first time in Korea.

A melting system was improved for measurement of trace elements in a firn core drilled at the North Greenland Eemian Ice Drilling (NEEM) site (77.45°N, 51.06°W). The melting heads of the melting system were specifically constructed with fluorinated ethylene propylene (FEP)-coated copper (type A) and pure nickel (type B) to reduce percolation of melted samples. Firn core sections with densities in the range of ~0.76–0.86 g cm−3 (depth interval: ~58.10–88.83 m) and ~0.56–0.76 g cm−3 (depth interval: ~17.32–58.10 m) were successfully decontaminated by the melting system with type A and B melting heads, respectively, as verified by the volume ratios of melted samples from inner and outer zones and video recorded during the melting procedures. Systematic performance tests of the type A melting head melter were performed using artificial ice cores. The procedural blanks and detection limits of V, Cr, Co, Rb, Cd, Ba, Tl, Th and U were generally lower than those in previous studies, whereas the levels of Mn, Sr and Pb were similar to those reported elsewhere. The concentration ratios of these elements from inner and outer zones of the melting head indicated that the melting system had good decontamination efficiency. Finally, the concentrations of elements in the NEEM firn core measured following mechanical removal of the outer layer with chisels and the type A melting head melter showed a good agreement with each other.

A total of 82 aerosol samples (PM 10-2.5 ) were collected from June 18, 2015 to October 1, 2016 at the remote sea site, the Ieodo Ocean Research Station (IORS), in the East China Sea. Samples were analyzed for 10 elements (Al, Fe, Cu, Zn, As, Mo, Cd, Sb, Tl, and Pb) as well as Pb isotopic composition to characterize temporal variations in elemental concentration levels, and to identify the potential source regions of atmospheric pollutants transported over the remote East China Sea. The results showed that the annual average element concentrations were lowest compared to those at different sites in East Asia, suggesting a very clean background area of IORS, with values ranging from 114 ng m −3 for Al to 0.045 ng m −3 for Tl. Concentrations averaged seasonally for all the elements revealed the highest levels occurring between winter and spring, and the lowest levels in summer. High enrichment factors (EF) of more than 100 for trace elements suggest that these elements originated mostly from anthropogenic sources. Coupling the Pb isotopic composition with a back trajectory analysis identified the potential source regions for each sample. Our approach identified China as a dominant contributor affecting atmospheric composition changes at IORS, the remote area of the East China Sea. As the largest anthropogenic emission source in East Asia, China contributed to almost 100% of the elemental concentration levels in winter and spring, ∼53% in summer and ∼63% in autumn. Because IORS's ambient air is sensitive to even slight changes in pollutant loading due to the significantly low pollution levels, long-term monitoring of air quality at IORS will provide invaluable information on the progress and efforts of atmospheric pollution management linked to emission controls in East Asian countries, especially China.

We present high-resolution lead (Pb) concentrations and isotopic ratios from a northwest Greenland snow pit covering a six-year period between 2003 and 2009. Pb concentrations ranged widely from 2.7 pg g−1 to 97.3 pg g−1, with a mean concentration of 21.6 pg g−1. These values are higher than those recorded for the pre-industrial period. Pb concentrations exhibit seasonal spikes in winter−spring layers. Crustal Pb enrichment factors (EF) suggest that the northwest Greenland snow pit is highly enriched with Pb of predominantly anthropogenic origin. The 206Pb/207Pb ratios ranged from 1.144 to 1.169 with a mean value of 1.156, which fall between less radiogenic Eurasian-type and more radiogenic Canadian-type signatures. This result suggests that several potential source areas of Pb impact on northwest Greenland. Abrupt changes in Pb concentrations and Pb isotope ratios were observed and related to seasonal shifts in source regions of aerosol transport. The 206Pb/207Pb isotope ratio increased gradually between 2003 and 2009. The similarity of the three-isotope plot (206Pb/207Pb versus 208Pb/207Pb) between some of our samples and Chinese urban aerosols suggests a steadily increasing contribution of Chinese Pb to northwest Greenland snow.

남극 빙원에서 오랜 기간 삭박에 의해 형성된 블루아이스 지역에는 수 십 만년에서 백 만년 이상된 얼음이 표면에 노출되어 있다. 따라서, 많은 비용과 기간이 소요되는 심부빙하시추와는 달리, 적은 비용과 짧은 시간에 오래된 얼음 시료를 블루아이스 지역에서 확보하여 고기후 연구에 활용할 수 있다. 블루아이스 시료를 고기후 연구에 적용하기 위해서는 얼음 시료에 대한 정확한 연대측정이 선행되어야 하기 때문에, 다양한 연대측정이 시도 되고 있다. 최근에, 한국과학자에 의해서 남극 장보고과학기지 주변의 엘리펀트 모레인 블루아이스 지역의 운석탐사가 집중적으로 수행되었으며, 이 지역에서 오래된 얼음 획득을 위한 예비 연구가 수행되었다. 향후 운석, 지질, 지구물리, 빙하, 대기 등의 종합적인 연구를 통해 블루아이스의 생성과 거동을 더 잘 이해하고, 정확한 연령을 가지고 고기후 연구수행이 가능할 것으로 전망된다.

The continuous growth of atmospheric nitrous oxide (N2O) is of concern for its potential role in global warming and future stratospheric ozone destruction. Climate feedbacks that enhance N2O emissions in response to global warming are not well understood, and past records of N2O from ice cores are not sufficiently well resolved to examine the underlying climate-N2O feedbacks on societally relevant time scales. Here, we present a new high-resolution and high-precision N2O reconstruction obtained from the Greenland NEEM (North Greenland Eemian Ice Drilling) and the Antarctic Styx Glacier ice cores. Covering the N2O history of the past two millennia, our reconstruction shows a centennial-scale variability of similar to 10 ppb. A pronounced minimum at similar to 600 CE coincides with the reorganizations of tropical hydroclimate and ocean productivity changes. Comparisons with proxy records suggest association of centennial- to millennial-scale variations in N2O with changes in tropical and subtropical land hydrology and marine productivity.Plain Language Summary Nitrous oxide (N2O) is a greenhouse and ozone-depleting gas. The growing level of N2O in the atmosphere is of global concern, and records of past N2O variations can provide an important context for understanding the links between N2O and climate change. In this study, we report new, high-quality N2O records covering the last two millennia using ice cores obtained from Greenland and Antarctica. Our N2O records show rapid centennial-scale changes in atmospheric N2O and confirm a pronounced minimum near 600 CE. Comparison with climate records suggests that hydroclimate change on land and changes in marine productivity contribute to centennial- to millennial-scale N2O variations.

We report the first high-resolution record of arsenic (As) observed in Greenland snow and ice for the periods 1711-1970 and 2003-2009 AD. The results show well-defined large-scale atmospheric pollution by this toxic element in the northern hemisphere, beginning as early as the 18th century. The most striking feature is an abrupt, unprecedented enrichment factor (EF) peak in the late 1890s, with an ∼30-fold increase in the mean value above the Holocene natural level. Highly enriched As was evident until the late 1910s; a sharp decline was observed after the First World War, reaching a minimum in the early 1930s during the Great Depression. A subsequent increase lasted until the mid-1950s, before decreasing again. Comparisons between the observed variations and Cu smelting data indicate that Cu smelting in Europe and North America was the likely source of early anthropogenic As in Greenland. Despite a significant reduction of ∼80% in concentration and ∼60% in EF from the 1950s to the 2000s, more than 80% of present-day As in Greenland is of anthropogenic origin, probably due to increasing As emissions from coal combustion in China. This highlights the demand for the implementation of national and international environmental regulations to further reduce As emissions.

Firn air provides plenty of old air from the near past, and can therefore be useful for understanding human impact on the recent history of the atmospheric composition. Most of the existing firn air records cover only the last several decades (typically 40 to 55 years) and are insufficient to understand the early part of anthropogenic impacts on the atmosphere. In contrast, a few firn air records from inland sites, where temperatures and snow accumulation rates are very low, go back in time about a century. In this study, we report an unusually old firn air effective CO2 age of 93 years from Styx Glacier, near the Ross Sea coast in Antarctica. This is the first report of such an old firn air age (>55 years) from a warm coastal site. The lock-in zone thickness of 12.4 m is larger than at other sites where snow accumulation rates and air temperature are similar. High-resolution X-ray density measurements demonstrate a high variability of the vertical snow density at Styx Glacier. The CH4 mole fraction and total air content of the closed pores also indicate large variations in centimeter-scale depth intervals, indicative of layering. We hypothesize that the large density variations in the firn increase the thickness of the lock-in zone and, consequently, increase the firn air ages because the age of firn air increases more rapidly with depth in the lock-in zone than in the diffusive zone. Our study demonstrates that all else being equal, sites where weather conditions are favorable for the formation of large density variations at the lock-in zone preserve older air within their open porosity, making them ideal places for firn air sampling.

Stable water vapor isotopes have been utilized as a tracer for studying atmospheric global circulations, climate change and paleoclimate with ice cores. Recently, since laser spectroscopy has been available, water vapor isotopes can be measured more precisely and continuously. Studies of water vapor isotopes have been conducted over the world, but it is the early stage in south Korea. For vapor isotopes study, a cryogenic sampling device for water vapor isotopes has been developed. The cryogenic sampling device consists of the dewar bottle, filled with extremely low temperature material and impinger connected with a vacuum pump. Impinger stays put in the dewar bottle to change the water vapor which passes through the inside of impinger into the solid phase as ice. The fact that water vapor has not sampled completely leads to isotopic fractionation in the impinger. To minimize the isotopic fractionation during sampling water vapor, we have tested the method using a serial connection with two sets of impinger device in the laboratory. We trapped 98.02% of water vapor in the first trap and the isotopic difference of the trapped water vapor between two impinger were about 20‰ and 6‰ for hydrogen and oxygen, respectively. Considering the amount of water vapor trapped in each impinger, the isotopic differences for hydrogen and oxygen were 0.33‰ and 0.06‰, respectively, which is significantly smaller than the precision of isotopic measurements. This work can conclude that there is no significant fractionation during water vapor trapping.

Two aerosol samples collected at King Sejong Korean scientific research station, Antarctica, on 9 December 2011 in the austral summer (sample S1) and 23 July 2012 in the austral winter (sample S2), when the oceanic chlorophyll a levels on the collection days of the samples were quite different, by ∼ 19 times (2.46 vs. 0.13 µg L−1, respectively), were investigated on a single-particle basis using quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), called low-Z particle EPMA, Raman microspectrometry (RMS), and attenuated total reflection Fourier transform infrared (ATR-FTIR) imaging techniques to obtain their characteristics based on the elemental chemical compositions, molecular species, and mixing state. X-ray analysis showed that the supermicron summertime and wintertime Antarctic aerosol samples have different elemental chemical compositions, even though all the individual particles analyzed were sea spray aerosols (SSAs); i.e., the contents of C, O, Ca, S, and Si were more elevated, whereas Cl was more depleted, for sample S1 than for sample S2. Based on qualitative analysis of the chemical species present in individual SSAs by the combined application of RMS and ATR-FTIR imaging, different organic species were observed in samples S1 and S2; i.e., Mg hydrate salts of alanine were predominant in samples S1 and S2, whereas Mg salts of fatty acids internally mixed with Mg hydrate salts of alanine were significant in sample S2. Although CaSO4 was observed significantly in both samples S1 and S2, other inorganic species, such as Na2SO4, NaNO3, Mg(NO3)2, SiO2, and CH3SO3Mg, were observed more significantly in sample S1, suggesting that those compounds may be related to the higher phytoplankton activity in summer.

We improved an on-line multi-ion chromatography (IC) system combined with a custom firn core melter (IC-melter). Five anions (F−, CH3SO3−, Cl−, NO3−, SO42−) and five cations (Na+, NH4+, K+, Mg2+, Ca2+) are simultaneously determined every 1.3 min; high-resolution ion data, with a depth interval of approximately 1.8 cm, can thus be obtained from Antarctic firn cores using the IC-melter. The IC-melter provides a processing speed of 1.1–1.7 h per ~0.7–0.8 m firn core. The depth resolution was designed to capture seasonal variations of ions based on the accumulation rate of Styx Glacier (Northern Victoria Land, Antarctica), where a firn core used herein was obtained, and variations of the firn core density. The analytical conditions (eluent concentration and flow rate, run time, peak separation, and sensitivity) of the multi-IC system were optimized to achieve the research goals. Cations and anions were separated through 4-min isocratic elution (CH3SO3H eluent) and 5-min isocratic elution (KOH eluent), respectively. The isocratic elution method for anion analysis was selected, rather than the gradient elution method, due to the exceptionally low ionic strength of the meltwater and easy operation of the multi-IC system. All ionic species showed calibration curves with determinant coefficients >0.997, standard errors of estimated values 0.67. In this study, as an application of the IC-melter, high-resolution ion species data from the firn core (depth interval: ~20.11–22.85 m) are shortly presented.

The stable isotopic compositions of snow and meltwater are a very useful tool to investigate water provenances and to increase the accuracy of paleoclimate studies in glacial watershed systems. To better understand the factors that affect the isotopic compositions of snow and meltwater in the western Antarctic Peninsula, the isotopic compositions of snow/ice and meltwater from the Barton Peninsula in Antarctica were examined. The isotopic compositions of snow are more enriched than those of meltwater and the variability of the isotopic compositions decreases from snow to meltwater. The melting process changes the linear slope between two water isotopes, which is different from the meteoric water line. We observe that the isotopic compositions of snow are altered by tephra, which results in isotopically enriched snow that is covered by tephra. This tephra decreases the snow's albedo, and the increased energy that is absorbed by the snow surface increases the melting rate, which causes isotopic exchange between liquid water and ice. Hydrological processes, such as daily variations in the melting rate and contributions from groundwater/runoff to seawater, also affect the isotopic compositions of water over the Barton Peninsula. Our works imply that uncertainty caused by these variations should be considered when applying stable water isotopes in this area for water flowpath and paleoclimate study.

Dust concentrations in Greenland ice show pronounced glacial/interglacial variations with almost two orders of magnitude increase during the Last Glacial Maximum. Greenland glacial dust was previously sourced to two East Asian deserts: the Taklimakan and Gobi deserts. Here we report the first high-resolution Pb and Sr isotopic evidence for a significant Saharan dust influence in Greenland during the last glacial period, back to ~31 kyr ago, from the Greenland NEEM ice core. We find that during Greenland Stadials 3–5.1 (~31 to 23 kyr ago), the primary dust provenance was East Asia, as previously proposed. Subsequently, the Saharan isotopic signals emerge during Greenland Stadials 2.1a–2.1c (~22.6 to 14.7 kyr ago) and from the late Bølling-Allerød to the Younger Dryas periods (~13.6 to 12 kyr ago), coincident with increased aridity in the Sahara and efficient northward transport of dust during these cold periods. A mixing isotopic model proposes the Sahara as an important source, accounting for contribution to Greenland glacial dust of up to 50%, particularly during Greenland Stadial 2.1b and the late Bølling-Allerød to the Younger Dryas periods. Our findings provide new insights into climate-related dust provenance changes and essential paleoclimatic constraints on dust-climate feedbacks in northern high latitudes.

International audience

Isotopic compositions of ice and meltwater play a very crucial role in paleoclimate studies based on ice cores and water resources research conducted in alpine hydrogeology. Better understanding of variations in the stable isotopic compositions of water is required since changes from ice to liquid water are gaining more attention due to recent climate change. In this work, a melting experiment was designed and conducted to investigate how the isotopic compositions of ice vary with time by heat sources, such as solar radiation. We conducted the melting experiment for 22 hours. The discharge rate rose to a maximum value after 258 minutes and gradually declined because we fixed the heat source. The isotopic compositions of meltwater increased linearly or to a second degree polynomial. The linear relationship between oxygen and hydrogen has a slope of 6.8, which is less than that of the Global Meteoric Water Line (8) and higher than a theoretical value (6.3). The deuterium excess decreased when δD or δ 18 O increases or vise versa since the slope of the relationship for ice-liquid exchange is less than 8. These findings and the apparatus of the melting experiments will make a helpful contribution to the studies of stable isotopes and the melting process in temperate and polar regions.

Polar ice sheets conserve atmospheric aerosols at the time of snowfall, which can be used to reconstruct past climate and environmental conditions. We investigated mineral dust and major ion records in snowpit samples obtained from the northwestern Greenland ice sheet near the North Greenland Eemian Ice Drilling (NEEM) camp in June 2009. We analyzed the samples for mineral dust concentrations as well as stable water isotopes (δ18O, δD, and deuterium excess) and major ions (Cl−, SO 4 2 - , methanesulfonic acid (MSA), Na+, and Ca2+). Seasonal δ18O and δD cycles indicate that the snowpit samples covered a six-year period from spring 2003 to early summer 2009. Concentrations of mineral dust, nss-Ca2+, and nss- SO 4 2 - showed seasonal deposition events with maxima in the winter–spring layers. On the other hand, the Cl−/Na+ ratio and the concentrations of MSA exhibited maxima in the summer layers, making them useful indicators for the summer season. Moreover, an anomalous atmospheric mineral dust event was recorded at a depth of 165–170 cm corresponding to late winter 2005 to spring 2006. A back trajectory analysis suggests that a major contributor to the Greenland aerosol was an air mass passing over the Canadian Arctic and North America. Several trajectories point to Asian regions as a dust source. The mineral dust deposited at NEEM was strongly influenced by long-range atmospheric transport and dust input from arid source areas in northern China and Mongolia.

An improved decontamination method and ultraclean analytical procedures have been developed to minimize Pb contamination of processed glacial ice cores and to achieve reliable determination of Pb isotopes in North Greenland Eemian Ice Drilling (NEEM) deep ice core sections with concentrations at the sub-picogram per gram level. A PL-7 (Fuso Chemical) silica-gel activator has replaced the previously used colloidal silica activator produced by Merck and has been shown to provide sufficiently enhanced ion beam intensity for Pb isotope analysis for a few tens of picograms of Pb. Considering the quantities of Pb contained in the NEEM Greenland ice core and a sample weight of 10 g used for the analysis, the blank contribution from the sample treatment was observed to be negligible. The decontamination and analysis of the artificial ice cores and selected NEEM Greenland ice core sections confirmed the cleanliness and effectiveness of the overall analytical process.

A continuous series of 60 snow samples was collected at a 2.5-cm interval from a 1.5-m snow pit at a site on the Styx Glacier Plateau in Victoria Land, Antarctica, during the 2011/2012 austral summer season. Various chemical components (δD, δ 18 O, Na + , K + , Mg 2+ , Ca 2+ , Cl ? , SO 4 2? , NO 3 ? , F ? , CH 3 SO 3 ? , CH 3 CO 2 ? and HCO 2 ? ) were determined to understand the highly resolved seasonal variations of these species in the coastal atmosphere near the Antarctic Jang Bogo station. Based on vertical profiles of δ 18 O, NO 3 ? and MSA, which showed prominent seasonal changes in concentrations, the snow samples were dated to cover the time period from 2009 austral winter to 2012 austral summer with a mean accumulation rate of 226 kg H 2 O m ?2 yr ?1 . Our snow profiles show pronounced seasonal variations for all the measured chemical species with a different pattern between different species. The distinctive feature of the occurrence patterns of the seasonal variations is clearly linked to changes in the relative strength of contributions from various natural sources (sea salt spray, volcanoes, crust-derived dust, and marine biogenic activities) during different short-term periods. The results allow us to understand the transport pathways and input mechanisms for each species and provide valuable information that will be useful for investigating long-term (decades to century scale periods) climate and environmental changes that can be deduced from an ice core to be retrieved from the Styx Glacier Plateau in the near future.