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Abstract: A method was developed for the quantitative determination of cations and anions in Antarctic ice cores at μgL−1 and sub-μgL−1 levels by ion chromatography (IC), after ultra-clean decontamination procedures. Strict manipulation and decontamination procedures were used in sub-sampling, in order to minimise sample contamination. Na+, NH4 +, K+, Mg2+ and Ca2+ were determined by 12-min isocratic elution (H2SO4 eluent). Contemporaneously, in a parallel device, F−, MSA (methanesulfonic acid), Cl−, NO3 − and SO4 2− were analysed in a single 12-min run with multiple-step elution using Na2CO3/NaHCO3 as eluent. Melted ice samples were pumped from their still-closed containers (polystyrene accuvettes with polyethylene caps), shared between the two ion chromatographic systems, online filtered (0.45μm Teflon membrane) and pre-concentrated (anions and cations pre-concentration columns) using a flow analysis system, thus avoiding uptake of contaminants from the laboratory atmosphere. Sensitivity, linear range, reproducibility and detection limit were evaluated for each chemical species. Anion or cation detection limits ranged from 0.01 to 0.15μgL−1 by using a relatively small sample volume (1.5mL). Such values are significantly lower than those reported in literature for almost all the components. These methods were successfully applied to the analysis of cations and anions at trace levels in the Dome C ice core. The composition of the atmospheric aerosol for the last 850kyr was reconstructed by high-resolution continuous chemical stratigraphies. Concentration trends in the last nine glacial-interglacial climatic cycles were shown and briefly discussed. [Copyright &y& Elsevier]

The chemical analysis of shallow firn cores sampled in coastal and plateau areas in Northern Victoria Land and along a transect from Talos Dome to Dome C (East Antarctica, Pacific Ocean sector) allowed a global view of spatial and temporal changes in chemical composition of snow depositions over the last 100 years. Variations in concentration of primary (sea spray) and secondary (biogenic emission, atmospheric inputs) source markers were observed and discussed as a function of distance from the sea and altitude. In the stations characterized by relatively high snow accumulation rates, the sub-sampling resolution was sufficient to obtain a stratigraphic dating by using the periodical variations of seasonal markers. In these stations, a subdivision in "summer" and "winter" samples was carried out in order to study the seasonal changes of the contributions of the measured compounds to the snow composition as elevation and distance from the sea increase. Some evidence of post-depositional effects which are able to change the original deposition of chloride and nitrate, was observed at stations with low accumulation rates. The reliability of the depth/concentration profile of these substances for reconstructing past deposition was also discussed. [ABSTRACT FROM AUTHOR]

High-resolution chemical records of main and trace ionic components of snow precipitation over the last 250 years were obtained by analysing the first 36 m of a firn core drilled at Talos Dome, a dome located in the ice divide between northern Victoria Land and Oates Land (East Antarctica Pacific Ocean/Ross Sea sector). The concentration/depth profiles of some relevant chemical parameters are discussed on the basis of a previous stratigraphic dating, set up following the seasonal signatures of non-sea-salt (nss) sulphate deposition and synchronised by using tritium and volcanic temporally known horizons. Particular attention is paid to the study of the temporal trends of the sea spray components (Na + , Cl - , Mg 2+ ) and S and N cycle compounds ( ) to understand the main sources, transport mechanisms and depositional processes of these compounds at the deposition site. Good correlations between the sea spray markers show that the primary marine contribution is relevant, though Talos Dome is located at a relatively high altitude (2316 m a.s.l.) and far from the coast line (about 250 km). The study of the snow chemical composition and of the recent (for the last few centuries) atmosphere/snow relationship at Talos Dome is important as a preliminary survey at this station, which will probably be chosen for a deep ice coring project. [ABSTRACT FROM AUTHOR]

In this work, we present chemical stratigraphies of two sampling lines collected within a 4 m depth snow pit dug in Dome C during the Antarctic summer Campaign 2017/2018, 12 years after the last reported snow pit. The first sampling line was analyzed for nine anionic and cationic species using Ion Chromatography (IC); the second sampling line was analyzed for seven major elements in an innovative way with Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) after sample pre-concentration, allowing the study of deposition processes of new markers especially related to crustal source. This coupled analysis, besides confirming previous studies, allowed us to investigate the depositions of the last decades at Dome C, enriching the number of the detected chemical markers, and yielding these two techniques complementary for the study of different markers in this kind of matrix. As a result of the dating, the snow layers analyzed covered the last 50 years of snow depositions. The assessment of the accumulation rate, estimated about 9 cm yr−1, was accomplished only for the period 1992–2016, as the eruption of 1992 constituted the only tie-point found in nssSO42− depth profile. Na, the reliable sea salt marker, together with Mg and Sr, mainly arose from marine sources, whereas Ca, Al and Fe originated from crustal inputs. Post-depositional processes occurred on Cl− as well as on NO3− and methanesulfonic acid (MSA); compared to the latter, Cl− had a more gradual decrease, reporting a threshold at 2.5 m for the post-depositional process completion. For NO3− and MSA, instead, the threshold was shallower, at about 1 m depth, with a loss of 87% for NO3− and of 50% for MSA. [ABSTRACT FROM AUTHOR]

Major explosive volcanic eruptions may significantly alter the global atmosphere for about 2–3 years. During that period, volcanic products (mainly H2SO4) with high residence time, stored in the stratosphere or, for shorter times, in the troposphere are gradually deposited onto polar ice caps. Antarctic snow may thus record acidic signals providing a history of past volcanic events. The high resolution sulphate concentration profile along a 197 m long ice core drilled at GV7 (Northern Victoria land) was obtained by Ion Chromatography on around 3500 discrete samples. The relatively high accumulation rate (241 ± 13 mm we yr −1) and the 5-cm sampling resolution allowed a preliminary counted age scale. The obtained stratigraphy covers roughly the last millennium and 24 major volcanic eruptions were identified, dated, and tentatively ascribed to a source volcano. The deposition flux of volcanic sulphate was calculated for each signature and the results were compared with data from other Antarctic ice cores at regional and continental scale. Our results show that the regional variability is of the same order of magnitude as the continental one. [ABSTRACT FROM AUTHOR]