Soon Do Hur

A lead (Pb) isotopic record, covering the two oldest glacial–interglacial cycles (~572 to 801 kyr ago) characterized by lukewarm interglacials in the European Project for Ice Coring in Antarctica Dome C ice core, provides evidence for dust provenance in central East Antarctic ice prior to the Mid-Brunhes Event (MBE), ~430 kyr ago. Combined with published post-MBE data, distinct isotopic compositions, coupled with isotope mixing model results, suggest Patagonia/Tierra del Fuego (TdF) as the most important sources of dust during both pre-MBE and post-MBE cold and intermediate glacial periods. During interglacials, central-western Argentina emerges as a major contributor, resulting from reduced dust supply from Patagonia/TdF after the MBE, contrasting to the persistent dominance of dust from Patagonia/TdF before the MBE. The data also show a small fraction of volcanic Pb transferred from extra-Antarctic volcanoes during post-MBE interglacials, as opposed to abundant transfer prior to the MBE. These differences are most likely attributed to the enhanced wet removal efficiency with the hydrological cycle intensified over the Southern Ocean, associated with a poleward shift of the southern westerly winds (SWW) during warmer post-MBE interglacials, and vice versa during cooler pre-MBE ones. Our results highlight sensitive responses of the SWW and the associated atmospheric conditions to stepwise Antarctic warming.

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.

Seasonal variations of the isotopic and chemical compositions of snowpits can provide useful tools for dating the age of the snowpit and examining the sources of aerosol. Based on the seasonal layers with D and 18O maxima and minima, it was determined that the snowpit, conducted in the vicinity of the Jang Bogo Station in Antarctica, contained snow deposited over a three-year period (2008–2010). Distinct seasonal variations of stable water isotopes were observed, with a slope of 8.2 from the linear isotopic relationship between oxygen and hydrogen, which indicates that the snow accumulated during three years without a significant post-depositional process. The positive correlations (r > 0.85) between Na+ and other ions in the winter period and the positive relationship the concentrations of the methanesulphonic acid (MSA) and non-sea salt sulfate (nssSO42–) in the warm period (r = 0.6, spring to summer) indicate the significant contributions of an oceanic source to the snowpit. Based on principal component analysis, the isotopic and chemical variables were classified into species representing input of sea-salt aerosol and suggesting potential seasonal markers. This study will support further investigations using ice cores in this region.

This study presents ultraclean procedures used in the challenging task of determining trace elements at or below the pg/g concentration level encountered in Greenland snow and ice. In order to validate these ultraclean procedures, recent snowfall and Holocene ice from northwest Greenland were analyzed for Cd, U, and Zn concentrations. The total procedural blanks brought through the entire measurement procedure proved to be negligible, compared to trace element concentrations, measured in snow and ice samples. This validates the overall practicality of the proposed ultraclean procedures, thereby ensuring the reliable measurements of ultra-trace analysis. A comparison between our study and published data shows that improper procedures employed throughout all stages, from field sampling to analysis to elevate the concentrations by several orders of magnitude, relative to the reliable concentration ranges. The risk of contamination exposure for selected trace elements appears to increase in the order of U < As ≤ Pb < Cd < Zn. Reliable measurements of Cd, U, and Zn concentrations in snow and ice allowed us to interpret the data in terms of seasonal variations in the inputs of crustal and anthropogenic sources to Greenland ice sheet.

Atmospheric water vapor transfers energy, causes meteorological phenomena and can be modified by climate change in the western coast region of Korea. In Korea, previous studies have utilized precipitation isotopic compositions in the water cycle for correlations with climate variables, but there are few studies using water vapor isotopes. In this study, water vapor was directly collected by a cryogenic method, analyzed for its isotopic compositions, and used to trace the origin and history of water vapor in the western coastal region of Korea during the winter of 2015/2016. Our analysis of paired mixing ratios with water vapor isotopes can explain the mechanism of water vapor isotopic fractionation and the extent of the mixing of two different air masses. We confirm the correlation between water vapor isotopes and meteorological parameters such as temperature, relative humidity, and specific humidity. The main water vapor in winter was derived from the continental polar region of northern Asia and showed an enrichment of 10 per mil (δ¹⁸O) through the evaporation of the Yellow Sea. Our results demonstrate the utility of using ground-based isotope observations as a complementary resource for constraining isotope-enabled Global Circulation Model in future investigations of atmospheric water cycles. These measurements are expected to support climate studies (speleothem) in the west coast region of Korea.

Photochemical oxidation of atmospheric elemental mercury (Hg⁰) promotes reactive oxidized Hg (Hg^II) adsorption on particles and deposition to the polar snowpack. The deposited Hg either returns to the atmosphere via photochemical reduction or remains in the snowpack depending on the strength of adsorption. In this study, we performed ab initio calculations to understand the atomic-level cause of the fate of adsorbed Hg by determining the adsorption affinity for Hg²⁺, the simplest form of Hg^II, of barite, halite, muscovite, illite, and ice-Ih as potential adsorbents. The adsorption affinity was estimated by calculating the energy required to dissociate adsorbed Hg²⁺ from the adsorbents. The results reveal that Hg²⁺ is stable on the surfaces of the selected adsorbents, except barite, but is prone to photodissociation under solar ultraviolet radiation. This mild adsorption is expected to contribute to the bidirectional exchange of Hg between the atmosphere and the polar snowpack. Thus, this theoretical approach can provide complementary perspectives on polar Hg dynamics beyond the limitations of field and laboratory experiments. Further studies on more complicated and realistic adsorption models with different Hg^II species and adsorbent surfaces having diverse defective structures are required to better comprehend air–snow Hg cycling in the polar regions.

Trace elements (V, Cr, Mn, Fe, Co, Cu, Zn, As, Rb, Sr, Mo, Cd, Sb, Ba, Tl, Pb, Bi, Th and U) and Pb isotopic compositions from the EPICA (European Project for Ice Coring in Antarctica) Dome C ice core have been determined using inductively coupled plasma sector field mass spectrometry (ICP-SFMS) and thermal ionization mass spectrometry (TIMS), covering the period from ~533 kyr BP to ~800 kyr BP, respectively. Our data have enabled us to extend the previous EDC records of trace elements and Pb isotopes from the Holocene back to the Marine Isotopic Stage 20.2, ~800 kyr BP. We here discuss the EDC records of Ba, Rb, Mo, Sb, Cd, Tl, Bi and Pb isotopes. Crustal elements such as Ba and Rb show well defined variations in concentrations in relation to climatic conditions with lower values during the interglacial periods and much higher values during the coldest periods of the last eight climatic cycles. Volcanogenic Cd, Tl and Bi show a less pronounced relationship between concentrations and climatic conditions. The isotopic signatures of Pb suggest that changes in the provenance of dust reaching the East Antarctic Plateau from Potential Source Areas occurred during the interglacial periods before the MBE. Our data suggest that the main factors affecting deposition fluxes and sources of natural trace elements over Antarctica are most likely linked to a progressive coupling of the climates of Antarctica and lower latitudes over the past 800 kyr.