Thirty years of snow deposition at Talos Dome (Northern Victoria Land, East Antarctica): Chemical profiles and climatic implications

The aim of this study was to use ion chromatographic methods to measure trace species under clean conditions in Antarctic snow samples. Both anionic and cationic contents of the snow samples were measured using preconcentration columns for both the ion chromatographic systems due to the low concentrations typical of Antarctic snow and ice samples. Samples were collected from a snow-pit dug in Talos Dome (East Antarctica) during the 2003-2004 Italian Antarctic Campaign to perform a preliminary survey of the site chosen for deep drilling in the framework of the TALos Dome ICE core (TALDICE) international project. Stratigraphic dating was attempted for the entire snow-pit, covering about 30 years, in order to achieve climatic information from the chemical profiles of the measured species. In particular, ions coming mainly from biogenic sources were investigated as potential markers for historical reconstruction of parameters expressing atmospheric and oceanic circulation, such as Southern Oscillation Index (SOI). For the studied period, a good correlation between biogenic species and SOI and sea-ice extent in the Ross Sea sector was observed, suggesting that these ions, as recorded in Talos Dome, can be used as markers for the reconstruction of the oceanic and atmospheric conditions in the past.     

Suppressed ion chromatography methods for the routine determination of ultra low level anions and cations in ice cores.

The concentration of trace ionic species in snow and ice samples was determined using suppressed ion chromatography (IC) with conductivity detection and ultra-clean sample preparation techniques. Trace anion species were determined in a single 24-min run by combining sample preconcentration with gradient elution using Na2B4O7 eluent. The detection limits (ranging from 0.001 to 0.006 microM) are the lowest reported in the literature. Cation species were analysed by direct injection of 0.25 ml and isocratic elution with a H2SO4 eluent. The clean preparation techniques showed no evidence of a difference (Student's t-test) between Milli-Q water samples analysed directly and processed Milli-Q ice samples. These robust, ultra-clean IC methods were routinely applied to the analysis of large number of samples to produce a high-resolution trace ion ice core record from Law Dome, East Antarctica.     

Thallium and cadmium in recent snow and firn layers in the Canadian Arctic by atomic fluorescence and absorption spectrometries

Compared to the Antarctic and Greenland, the Canadian Arctic has seen extremely few trace metal studies on snow and ice. Surface, subsurface and depth samples of snow and firns were collected from the Agassiz Ice Cap, Ellesmere Island, Canada using clean room practices. Results for Tl (directly determined by LEAFS) and Cd (determined by GFAAS) are reported. To our knowledge, the thallium depth profile presented here is the first one so far reported for both polar systems, Greenland or other places. Tl concentrations peak in the winter-spring periods, when the Arctic atmosphere is loaded with foreign pollutants and suspended particulates which sometime severely reduce the visibility, creating a phenomenon commonly known as the Arctic haze. These results are in general accordance with the historical Arctic air pollution and acidity/conductivity data on ice cores. Surface concentrations of Tl range from 0.3 to 0.9 pg/g, which is a few times higher than those found in Antarctica. Cadmium shows seasonal characteristics similar to Tl although there is not a definite correlation between the two. However, there could be two predominant origins of metals which were deposited in the snow: Eurasian origin in January–April corresponding to high level metals (main deposition), and a less definite origin in May–December corresponding to low level metals.     

Influence of ice and snow covers on the UV exposure of terrestrial microbial communities: dosimetric studies

Bacillus subtilis spore biological dosimeters and electronic dosimeters were used to investigate the exposure of terrestrial microbial communities in micro-habitats covered by snow and ice in Antarctica. The melting of snow covers of between 5- and 15-cm thickness, depending on age and heterogeneity, could increase B. subtilis spore inactivation by up to an order of magnitude, a relative increase twice that caused by a 50% ozone depletion. Within the snow-pack at depths of less than approximately 3 cm snow algae could receive two to three times the DNA-weighted irradiance they would receive on bare ground. At the edge of the snow-pack, warming of low albedo soils resulted in the formation of overhangs that provided transient UV protection to thawed and growing microbial communities on the soils underneath. In shallow aquatic habitats, thin layers of heterogeneous ice of a few millimetres thickness were found to reduce DNA-weighted irradiances by up to 55% compared to full-sky values with equivalent DNA-weighted diffuse attenuation coefficients (K(DNA)) of >200 m(-1). A 2-mm snow-encrusted ice cover on a pond was equivalent to 10 cm of ice on a perennially ice covered lake. Ice covers also had the effect of stabilizing the UV exposure, which was often subject to rapid variations of up to 33% of the mean value caused by wind-rippling of the water surface. These data show that changing ice and snow covers cause relative changes in microbial UV exposure at least as great as those caused by changing ozone column abundance.     

Chemical signals of past climate and environment from polar ice cores and firn air

Chemical and isotopic records obtained from polar ice cores have provided some of the most iconic datasets in Earth system science. Here, I discuss how the different records are formed in the ice sheets, emphasising in particular the contrast between chemistry held in the snow/ice phase, and that which is trapped in air bubbles. Air diffusing slowly through the upper firn layers of the ice sheet can also be sampled in large volumes to give more recent historical information on atmospheric composition. The chemical and geophysical issues that have to be solved to interpret ice core data in terms of atmospheric composition and emission changes are also highlighted. Ice cores and firn air have provided particularly strong evidence about recent changes (last few decades to centuries), including otherwise inaccessible data on increases in compounds that are active as greenhouse gases or as agents of stratospheric depletion. On longer timescales (up to 800?000 years in Antarctica), ice cores reveal major changes in biogeochemical cycling, which acted as feedbacks on the very major changes in climate between glacial and interglacial periods.     

Schwermetalle in der Umwelt. Auf Ultra‐Spurensuche

The reliable determination of (ultra‐)trace elements is not a trivial task at all. Trace analyses of extremely clean environmental samples (ground water, snow, ice) require the cleanest sample collection and pre‐treatment procedures currently available, the most sensitive analysis techniques as well as highly motivated and well experienced lab personnel. It is only through the perfect interaction of all mentioned components that modern analysis strategies allow to answer succesfully questions of sociopolitical relevance. As such, looking back to ancient periods – through the analysis of ice cores – allows to put the current heavy metal pollution into perspective and to better predict future trends. Tap water or mineral water? What is better? Here too, modern ultra trace analysis opens news perspectives.     

Vertical Distribution of137 Cs in The Lacustrine Areas and Preliminary Results of 7Be Activity in Snow Samples at Terra Nova Bay (ANTARCTICA)

Abstract

¹³⁷ Cs activity in samples from lacustrine areas around the Italian base in Antarctica is reported as an integration of a previous work. Preliminary data of cosmogenic ⁷ Be activity determined in snowfalls, total atmospheric depositions, soil and air particulate collected during the 1990–91 and 1991–92 Italian expeditions in Antarctica is presented. The results obtained point out the efficiency of snow in the processes of air particulate scavenging and provide useful information for the development of research in Antarctica in the study of air/snow transfer processes by means of natural radionuclides.     

Synthesis and biodistribution of the 99mTc nitrido complex with 2-(4-nitro-1H-imidazolyl)ethyl dithiocarbamate (NIET)

Sodium and chlorine measurements were made by instrumental neutron activation analysis (INAA) on stratigraphically dated ice core samples from Byrd Station, Antarctica, for the last three centuries. The time period between 1969 and 1989 showed an enhanced impact on the Antarctic ice sheets from oceans in the form of marine aerosols. A disturbed ocean-atmosphere interface due to El Niño Southern Oscillation (ENSO) events seems to be a candidate for this observation in Antarctica.     

Determination of nitrate at the ng/g level in Antarctic snow samples with ion chromatography and isotope dilution mass spectrometry

Summary Nitrate traces in Antarctic snow and hoar-frost samples, which were collected on the Ekström ice shelf during January and February, 1987, were determined with ion chromatography at the German Antarctic station Georg-von-Neumayer. For comparison, sample preparations for isotope dilution mass spectrometry were also carried out at the German station whereas the mass spectrometric measurements took place in Regensburg. Comparable reproducibilities of 1%–5% were found for both methods of analysing nitrate concentrations in the range of 40–190 ng/g. An excellent agreement of the results of both methods with an average deviation of 0.1% was found in three sets of firn core samples. The average relative deviation of the ion chromatographic values from those of isotope dilution mass spectrometry was –10% for eleven hoar-frost and surface snow samples. The highest nitrate concentrations were analysed in hoar-frost samples with an average value of 548 ng/g. The following order, which corresponds to the age of nitrate depositions, was: new snow (206 ng/g), old surface snow (146 ng/g), and snow from firn cores (61 ng/g). The decreasing concentration with the age of samples is the result of re-emission of nitrate into the atmosphere after its deposition by snow. A seasonal variation of the nitrate concentration with a summer maximum and a winter minimum was observed for firn core samples. Accurate results of analytical data, which are published from all parts of Antarctica today, can only be guaranteed by the application of independent methods, e.g., by ion chromatography and isotope dilution mass spectrometry as it is shown in this work.

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Bestimmung von Nitrat im ng/g Bereich in antarktischen Schneeproben durch Ionen-Chromatographie und massenspektrometrische Isotopenverdünnungsanalyse

     

A new sensitive method for the quantification of glyoxal and methylglyoxal in snow and ice by stir bar sorptive extraction and liquid desorption-HPLC-ESI-MS

In this study, the development of a new sensitive method for the analysis of alpha-dicarbonyls glyoxal (G) and methylglyoxal (MG) in environmental ice and snow is presented. Stir bar sorptive extraction with in situ derivatization and liquid desorption (SBSE-LD) was used for sample extraction, enrichment, and derivatization. Measurements were carried out using high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). As part of the method development, SBSE-LD parameters such as extraction time, derivatization reagent, desorption time and solvent, and the effect of NaCl addition on the SBSE efficiency as well as measurement parameters of HPLC-ESI-MS/MS were evaluated. Calibration was performed in the range of 1–60 ng/mL using spiked ultrapure water samples, thus incorporating the complete SBSE and derivatization process. 4-Fluorobenzaldehyde was applied as internal standard. Inter-batch precision was <12 % RSD. Recoveries were determined by means of spiked snow samples and were 78.9?±?5.6 % for G and 82.7?±?7.5 % for MG, respectively. Instrumental detection limits of 0.242 and 0.213 ng/mL for G and MG were achieved using the multiple reaction monitoring mode. Relative detection limits referred to a sample volume of 15 mL were 0.016 ng/mL for G and 0.014 ng/mL for MG. The optimized method was applied for the analysis of snow samples from Mount Hohenpeissenberg (close to the Meteorological Observatory Hohenpeissenberg, Germany) and samples from an ice core from Upper Grenzgletscher (Monte Rosa massif, Switzerland). Resulting concentrations were 0.085–16.3 ng/mL for G and 0.126–3.6 ng/mL for MG. Concentrations of G and MG in snow were 1–2 orders of magnitude higher than in ice core samples. The described method represents a simple, green, and sensitive analytical approach to measure G and MG in aqueous environmental samples.     

Analysis of Organic Compounds in Antarctic Snow and Their Origin

Abstract

Organic compounds extractable with n-hexane were identified and quantitatively determined in pack, surface and deep snow samples taken at different depths and collected at several altitudes above sea level from Antarctica during the 1993/94 Italian expedition. The comparison between the composition of organic compounds in snow and the ones in pack and sea-water samples pointed out that the three matrices substantially contain the same biogenic and anthropogenic organic compounds. The contribution of marine aerosol to organic content in the snow is confirmed by the enrichment ratios calculated for the more representative classes of identified compounds (n-alkanes, phthalates and low molecular weight alkylbenzenes). The changes in the composition of organic compounds in snow as the altitude increases seem to depend on the dimensional spectrum of the aerosol. Thus, smallest particles, richest in surfactant material, reach the highest altitudes.     

青藏高原雪冰样品中低含量水溶金属离子分析方法对比研究

从采自青藏高原阿汝和古里雅冰川的两支冰芯中选取31个样品,分别用三种仪器对比分析K^+、Na^+、Ca^2+、Mg^2+四种水溶金属离子,寻求最佳分析方案。分析结果对比发现,电感耦合等离子体发射光谱(ICP-OES)法在K+测量中存在困难,而离子色谱(IC)法和电感耦合等离子体质谱(ICP-MS)法均能够满足要求,且分析结果具有高度的一致性,四种离子的相关系数(R2)均在0.97以上,且并未出现ICP-MS法比IC法测量值明显偏高的现象。因此,除IC法外,ICP-MS法也是检测青藏高原雪冰样品中水溶金属离子的有效手段,其测定速度更快,且可以同时进行微、痕量元素检测,适用于大批量冰芯样品的快速分析。     

‘Extreme Mass Spectrometry’: the role of mass spectrometry in the study of the Antarctic Environment

A focus on the studies of the Antarctic environment that have been performed by mass spectrometry is presented herein; our aim is to give evidence of the essential role of this instrumental technique in the framework of the scientific research in Antarctica, with a comprehensive review on the main literature of the last two decades. Due to the wideness of the topic, the present review is limited to the determination of organic pollutants, natural molecules and biomarkers in Antarctica, thus excluding elemental analysis and studies on inorganic species. The work has been divided into five sections, on the basis of the considered environmental compartment: air; ice and snow; seawater, pack ice and lakes; soil and sediments; and organisms and biomarkers. Copyright © 2014 John Wiley & Sons, Ltd.     

Laser ablation inductively coupled plasma mass spectrometry: a new tool for trace element analysis in ice cores

A new method for the detection of trace elements in polar ice cores using laser ablation with subsequent inductively coupled plasma mass spectrometry analysis is described. To enable direct analysis of frozen ice samples a special laser ablation chamber was constructed. Direct analysis reduces the risk of contamination. The defined removal of material from the ice surface by means of a laser beam leads to higher spatial resolution (300-1000 microm) in comparison to investigations with molten ice samples. This is helpful for the detection of element signatures in annual layers of ice cores. The method was applied to the successful determination of traces for the elements Mg, Al, Fe, Zn, Cd, Pb, some rare-earth elements (REE) and minor constituents such as Ca and Na in ice cores. These selected elements serve as tracer elements for certain sources and their element signatures detected in polar ice cores can give hints to climate changes in the past. We report results from measurements of frozen ice samples, the achievable signal intensities, standard deviations and calibration graphs as well as the first signal progression of 205Pb in an 8,000-year-old ice core sample from Greenland. In addition, the first picture of a crater on an ice surface burnt by an IR laser made by cryogenic scanning electron microscopy is presented.     

Clean conditions for the determination of ultra-low levels of mercury in ice and snow samples

Laboratory facilities and methods are presented for the determination of ultra-low levels of mercury (Hg) in ice and snow samples originating from polar ice caps or temperate regions. Special emphasis will be given to the presentation of the clean laboratory and the cleaning procedures. The laboratory is pressurized with air filtered through high efficiency particle filters. This first filtration is not enough to get rid of contamination by Hg in air. Experiments are conducted in a clean bench, especially built for Hg analysis, equipped with both particle filter and activated charcoal filter. It allows to obtain very low levels of atmospheric Hg contamination. Ultrapure water is produced for cleaning all the plastic containers that will be used for ice and snow samples and also for the dilution of the standards. Hg content in laboratory water is about 0.08+/-0.02 pg/g. A Teflon system has been developed for the determination of Hg in ice and snow samples based on Hg(II) reduction to Hg(0) with a SnCl2/HNO3 solution followed by the measurement of gaseous Hg(0) with a Hg analyzer GARDIS 1A+ based on the Cold Vapor Atomic Absorption Spectroscopy method. Blank determination is discussed.     

Micrometeorites in Antarctic ice detected by Ir: estimation of 120k year old accretion rate

The accretion rate of micrometeorites (MMs) was estimated from Ir contents in snow around Dome Fuji Station and ice shards obtained during ice core drilling at Dome Fuji Station, Antarctica. The snow and ice shards were melted and filtered from the residues. Although MMs were not found on filters, we tried to detect them from the residues as Ir peaks determined by instrumental neutron activation analysis (INAA). Although Ir is very rare in the earth’s crust, its concentration is high in extraterrestrial matter (e.g., chondrites). Trace amounts of Ir can be easily detected by INAA, because the cross section of Ir is relatively large (e.g., 309 barn). The accretion rates were estimated for 120k year ago, 5k year ago and at present, as (3.2 ± 0.9) × 10² t/year (8.6 ± 0.18) × 10³ t/year and (1.3 ± 0.10) × 10³ t/year, respectively. These estimates were comparable to those of previous studies, however the rate of 120k year ago was approximately an order of magnitudes lower than the others.     

New application of a traditional analytical method – arsenic removal from water works sludge during iron(III) chloride coagulant production

A new method for the detection of trace elements in polar ice cores using laser ablation with subsequent inductively coupled plasma mass spectrometry analysis is described. To enable direct analysis of frozen ice samples a special laser ablation chamber was constructed. Direct analysis reduces the risk of contamination. The defined removal of material from the ice surface by means of a laser beam leads to higher spatial resolution (300– 1000 μm) in comparison to investigations with molten ice samples. This is helpful for the detection of element signatures in annual layers of ice cores. The method was applied to the successful determination of traces for the elements Mg, Al, Fe, Zn, Cd, Pb, some rare-earth elements (REE) and minor constituents such as Ca and Na in ice cores. These selected elements serve as tracer elements for certain sources and their element signatures detected in polar ice cores can give hints to climate changes in the past. We report results from measurements of frozen ice samples, the achievable signal intensities, standard deviations and calibration graphs as well as the first signal progression of ²⁰⁸Pb in an 8,000-year-old ice core sample from Greenland. In addition, the first picture of a crater on an ice surface burnt by an IR laser made by cryogenic scanning electron microscopy is presented.     

Analytical quality control: Sampling procedures to detect trace metals in environmental matrices

The problem of contamination during the collection of samples of environmental interest to detect trace metal is discussed. Attention is focused on the leaching of metals from sampling devices used to collect surface and deep seawater. A procedure to test metal release is applied to emphasize the importance of conditioning samplers before use. The procedure for checking the contamination extent and decontamination of firn and ice cores to detect ultratrace elements (particularly Cd and Pb) is presented and applied to some firn cores collected in Antarctica during the 1990–1991 Italian expedition.     

Clean conditions for the determination of ultra-low levels of mercury in ice and snow samples

Laboratory facilities and methods are presented for the determination of ultra-low levels of mercury (Hg) in ice and snow samples originating from polar ice caps or temperate regions. Special emphasis will be given to the presentation of the clean laboratory and the cleaning procedures. The laboratory is pressurized with air filtered through high efficiency particle filters. This first filtration is not enough to get rid of contamination by Hg in air. Experiments are conducted in a clean bench, especially built for Hg analysis, equipped with both particle filter and activated charcoal filter. It allows to obtain very low levels of atmospheric Hg contamination. Ultrapure water is produced for cleaning all the plastic containers that will be used for ice and snow samples and also for the dilution of the standards. Hg content in laboratory water is about ¶0.08 ± 0.02 pg/g. A Teflon system has been developed for the determination of Hg in ice and snow samples based on Hg(II) reduction to Hg(0) with a SnCl₂/HNO₃ solution followed by the measurement of gaseous Hg(0) with a Hg analyzer GARDIS 1A+ based on the Cold Vapor Atomic Absorption Spectroscopy method. Blank determination is discussed.     

Ultratrace analysis of Antarctic snow samples by reaction cell inductively coupled plasma mass spectrometry using a total-consumption micro-sample-introduction system

In this work, a new sensitive procedure for the determination of ultratrace elements in snow samples based on quadrupole ICP-MS has been developed. After filtration through a 0.5 microm PTFE membrane (for dissolved element determination) or acidification with 0.5% nitric acid (for acid dissolvable element determination), the analytes were preconcentrated by sample volume reduction and analysed by ICP-MS. Micro-samples were efficiently introduced into the plasma source at 20 microl min(-1) uptake rate by using a PFA micronebulizer coupled to an evaporation chamber of the torch integrated sample introduction system (TISIS). As a result, the amount of sample required was about one order of magnitude lower than that required with a conventional liquid sample introduction system. In order to improve the transport efficiency, the TISIS chamber was electrically-heated at 70 degrees C and a sheathing gas stream was used to protect the aerosol from the chamber walls. Under these conditions, negative solvent plasma effects were no more severe than for conventional systems, because the total solvent plasma load was 20 mg min(-1). The operating parameters were optimized to obtain maximum sensitivity, while limiting oxides and double charge ion formation. The polyatomic interferences were removed by applying the dynamic reaction cell (DRC) technique, using ammonia as the reaction gas. Under the optimized conditions, limits of detection ranged from 0.02 to 4.5 pg g(-1), allowing the determination of Cr, V, Fe, Mn, Pb, Zn, Cd, Co and Cu in Antarctic snow samples. Signal repeatability was lower than 10% which prevented the use of an internal standard. Precision of the procedure ranged from 2.0% to 5.6%. The accuracy of the method was verified by the analysis of both certified reference water and surface snow samples collected in coastal and inland areas of Antarctica. The DRC program used, the short wash out and signal stabilization times registered under these conditions led to a 10 h(-1) sample throughput.