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Diversity of Viridiplantae DNA present on rock surfaces in the Ellsworth Mountains, continental Antarctica. Polar Biol 2022. [DOI: 10.1007/s00300-022-03021-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Marina-Montes C, Pérez-Arribas LV, Anzano J, de Vallejuelo SFO, Aramendia J, Gómez-Nubla L, de Diego A, Manuel Madariaga J, Cáceres JO. Characterization of atmospheric aerosols in the Antarctic region using Raman Spectroscopy and Scanning Electron Microscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 266:120452. [PMID: 34624816 DOI: 10.1016/j.saa.2021.120452] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 09/16/2021] [Accepted: 09/26/2021] [Indexed: 06/13/2023]
Abstract
The non-destructive spectroscopic characterization of airborne particulate matter (PM) was performed to gain better knowledge of the internal structures of atmospheric aerosols at the particle level in the Antarctic region, along with their potential sources. PM and soil samples were collected during the 2016-2017 austral summer season at the surroundings of the Spanish Antarctic Research Station "Gabriel de Castilla" (Deception Island, South Shetland Islands). PM was deposited in a low-volume sampler air filter. Raman spectroscopy (RS) and Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS) were used to determine the elemental and molecular composition of the individual aerosol and soil particles. Filter spectra measured by these techniques revealed long-range atmospheric transport of organic compounds (polystyrene and bacteria), local single and cluster particles made of different kinds of black carbon (BC), exotic minerals (polyhalite, arcanite, niter, ammonium nitrate, syngenite and nitrogen, phosphorus, and potassium (NPK) fertilizer), and natural PM (sea salts, silicates, iron oxides, etc.). In addition to the filter samples, forsterite and plagioclase were discovered in the soil samples together with magnetite. This is the first report of the presence of a microplastic fiber in the Antarctic air. This fact, together with the presence of other pollutants, reflects that even pristine and remote regions are influenced by anthropogenic activities.
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Affiliation(s)
- César Marina-Montes
- Laser Lab, Chemistry & Environment Group, Department of Analytical Chemistry, Faculty of Sciences, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Luis V Pérez-Arribas
- Laser Chemistry Research Group, Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, Plaza de Ciencias 1, 28040 Madrid, Spain
| | - Jesús Anzano
- Laser Lab, Chemistry & Environment Group, Department of Analytical Chemistry, Faculty of Sciences, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Silvia Fdez-Ortiz de Vallejuelo
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Julene Aramendia
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Leticia Gómez-Nubla
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Alberto de Diego
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Juan Manuel Madariaga
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Jorge O Cáceres
- Laser Chemistry Research Group, Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, Plaza de Ciencias 1, 28040 Madrid, Spain.
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de Menezes GCA, Câmara PEAS, Pinto OHB, Carvalho-Silva M, Oliveira FS, Souza CD, Reynaud Schaefer CEG, Convey P, Rosa CA, Rosa LH. Fungal diversity present on rocks from a polar desert in continental Antarctica assessed using DNA metabarcoding. Extremophiles 2021; 25:193-202. [PMID: 33651232 DOI: 10.1007/s00792-021-01221-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 02/11/2021] [Indexed: 01/04/2023]
Abstract
We evaluated the fungal diversity associated with carbonate veins and two types of salt encrustation in rocks in a polar desert region of continental Antarctica using DNA a metabarcoding approach. We detected 262,268 reads grouped into 517 amplicon sequence variants (ASVs) assigned to the phyla Ascomycota, Basidiomycota, Mortierellomycota and Mucoromycota. Fourteen ASVs belonging to the genera Trichosporon, Mortierella, Penicillium, Aspergillus, Cladosporium, Coprinellus, Pleurotus and Pseudogymnoascus were assessed to be dominant taxa. The fungal communities of the three habitats sampled displayed high diversity indices when compared with other habitats of Antarctica, although differing in detail, with the highest diversity indices in the gypsum crust type 2. Only 48 of the 517 ASVs (9.28%) were detected in all three habitats, including dominant, intermediate and minor components. In contrast with previous studies of fungal communities living in the ultra-extreme conditions of continental Antarctica, application of metabarcoding revealed the DNA of a rich and complex resident fungal community. The ASVs detected included fungi with different ecological roles, with xerophilic, human- and animal-associated, phytopathogenic, saprotrophic, mutualistic, psychrotolerant and cosmopolitan taxa. This sequence diversity may be the result of deposition of fungal propagules over time driven by air currents, precipitation or human activities in the region.
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Affiliation(s)
- Graciéle Cunha Alves de Menezes
- Laboratório de Microbiologia Polar e Conexões Tropicais, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, PO Box 486, Belo Horizonte, MG, CEP 31270-901, Brazil
| | | | | | | | - Fábio Soares Oliveira
- Departamento de Geografia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | | | - Peter Convey
- British Antarctic Survey, NERC, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
| | - Carlos Augusto Rosa
- Laboratório de Microbiologia Polar e Conexões Tropicais, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, PO Box 486, Belo Horizonte, MG, CEP 31270-901, Brazil
| | - Luiz Henrique Rosa
- Laboratório de Microbiologia Polar e Conexões Tropicais, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, PO Box 486, Belo Horizonte, MG, CEP 31270-901, Brazil.
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Xie L, Spiro B, Wei G. Purification of BaSO 4 precipitate contaminated with organic matter for oxygen isotope measurements (δ 18 O and Δ 17 O). RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:1727-1733. [PMID: 28328040 DOI: 10.1002/rcm.7610] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Revised: 05/10/2016] [Accepted: 05/16/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE Sulfate precipitates are often contaminated with nitrates and organic materials (OM), which reduce the precision and accuracy of measurements of δ18 O and Δ17 O values in the sulfate. Although nitrates can be effectively removed using diethylenetriaminepentaacetic acid solution, removing OM from the precipitates is often difficult. One effective approach is to heat powdered precipitates to high temperatures. In this study, the effect of this procedure on the δ18 O and Δ17 O values of BaSO4 precipitate was fully examined. METHODS OM-contaminated BaSO4 precipitates and 18 O- and 17 O-labeled purified BaSO4 precipitates were loaded into alumina and gold crucibles and heated at 450 °C, 600 °C and 800 °C for 2 h. The nitrogen and carbon contents in the initial and the final BaSO4 were measured using an elemental analyzer. The values of δ18 O and Δ17 O were measured using a temperature conversion/elemental analyzer coupled with an isotope ratio mass spectrometer, and a CO2 laser system coupled with an isotopic ratio mass spectrometer. RESULTS OM was effectively (88 ± 17%) removed from the BaSO4 precipitates by this treatment, and heating at 800 °C had the highest removal efficiency (98%). The differences in δ18 O and Δ17 O values between the final and initial BaSO4 precipitates was -0.6‰ to 0.3‰ (average of -0.1‰) and -0.24‰ to 0.10‰ (average of -0.02‰), respectively. Significant positive relationships between the δ18 O and Δ17 O values of the initial BaSO4 precipitate and those of the high-T-treated aliquots were found, with slopes having mean values of 0.96 ± 0.06 and 1.04 ± 0.01, respectively. CONCLUSIONS The result demonstrates high removal efficiency for OM in BaSO4 precipitates and no significant differences in the oxygen isotopic compositions between high-T treated BaSO4 and initial BaSO4 . This study indicates that the modified high-T treatment (800 °C, 2 h) is an effective method for purifying BaSO4 precipitated from geological and environmental samples with a high OM content for δ18 O and Δ17 O measurements. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Luhua Xie
- State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, P.R. China
- Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, P.R. China
| | - Baruch Spiro
- Department of Mineralogy, Natural Science Museum, London, SW7 5BD, UK
| | - Gangjian Wei
- State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, P.R. China
- Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, P.R. China
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Buelow HN, Winter AS, Van Horn DJ, Barrett JE, Gooseff MN, Schwartz E, Takacs-Vesbach CD. Microbial Community Responses to Increased Water and Organic Matter in the Arid Soils of the McMurdo Dry Valleys, Antarctica. Front Microbiol 2016; 7:1040. [PMID: 27486436 PMCID: PMC4947590 DOI: 10.3389/fmicb.2016.01040] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 06/21/2016] [Indexed: 11/27/2022] Open
Abstract
The soils of the McMurdo Dry Valleys, Antarctica are an extreme polar desert, inhabited exclusively by microscopic taxa. This region is on the threshold of anticipated climate change, with glacial melt, permafrost thaw, and the melting of massive buried ice increasing liquid water availability and mobilizing soil nutrients. Experimental water and organic matter (OM) amendments were applied to investigate how these climate change effects may impact the soil communities. To identify active taxa and their functions, total community RNA transcripts were sequenced and annotated, and amended soils were compared with unamended control soils using differential abundance and expression analyses. Overall, taxonomic diversity declined with amendments of water and OM. The domain Bacteria increased with both amendments while Eukaryota declined from 38% of all taxa in control soils to 8 and 11% in water and OM amended soils, respectively. Among bacterial phyla, Actinobacteria (59%) dominated water-amended soils and Firmicutes (45%) dominated OM amended soils. Three bacterial phyla (Actinobacteria, Proteobacteria, and Firmicutes) were primarily responsible for the observed positive functional responses, while eukaryotic taxa experienced the majority (27 of 34) of significant transcript losses. These results indicated that as climate changes in this region, a replacement of endemic taxa adapted to dry, oligotrophic conditions by generalist, copiotrophic taxa is likely.
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Affiliation(s)
- Heather N Buelow
- Department of Biology, University of New Mexico Albuquerque, NM, USA
| | - Ara S Winter
- Department of Biology, University of New Mexico Albuquerque, NM, USA
| | - David J Van Horn
- Department of Biology, University of New Mexico Albuquerque, NM, USA
| | - John E Barrett
- Department of Biological Sciences, Virginia Tech Blacksburg, VA, USA
| | - Michael N Gooseff
- Department of Civil, Architectural, and Environmental Engineering, Institute of Arctic and Alpine Research, University of Colorado Boulder Boulder, CO, USA
| | - Egbert Schwartz
- Department of Biological Sciences, Northern Arizona University Flagstaff, AZ, USA
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Lost cold Antarctic deserts inferred from unusual sulfate formation and isotope signatures. Nat Commun 2015; 6:7579. [PMID: 26119082 DOI: 10.1038/ncomms8579] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 05/20/2015] [Indexed: 11/08/2022] Open
Abstract
The Antarctic ice cap significantly affects global ocean circulation and climate. Continental glaciogenic sedimentary deposits provide direct physical evidence of the glacial history of the Antarctic interior, but these data are sparse. Here we investigate a new indicator of ice sheet evolution: sulfates within the glaciogenic deposits from the Lewis Cliff Ice Tongue of the central Transantarctic Mountains. The sulfates exhibit unique isotope signatures, including δ(34)S up to +50‰ for mirabilite evaporites, Δ(17)O up to +2.3‰ for dissolved sulfate within contemporary melt-water ponds, and extremely negative δ(18)O as low as -22.2‰. The isotopic data imply that the sulfates formed under environmental conditions similar to today's McMurdo Dry Valleys, suggesting that ice-free cold deserts may have existed between the South Pole and the Transantarctic Mountains since the Miocene during periods when the ice sheet size was smaller than today, but with an overall similar to modern global hydrological cycle.
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Budhavant K, Safai PD, Rao PSP. Sources and elemental composition of summer aerosols in the Larsemann Hills (Antarctica). ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:2041-2050. [PMID: 25167815 DOI: 10.1007/s11356-014-3452-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 08/14/2014] [Indexed: 06/03/2023]
Abstract
Atmospheric aerosols play a major role in the global climate change. A better physical characterization of the chemical composition of atmospheric aerosols, especially in remote atmosphere, is an important step to reduce the current uncertainty in their effect on the radiative forcing of the climate. In the present work, surface aerosols have been studied over the Southern Ocean and over Bharati, Indian Research Station at Larsemann Hills at the Antarctic coast during the summer season of 2009-2010. Aerosol samples were collected using optical particle counter (OPC) and high-volume air sampler. PM10 and PM2.5 aerosol samples were analyzed for various water-soluble and acid-soluble ionic constituents. The Hysplit model was used to compute the history of the air masses for their possible origin. Supplementary measurements of meteorological parameters were also used. The average mass concentration for PM10 over the Southern Ocean was found to be 13.4 μg m(3). Over coastal Antarctica, the mass of PM10 was 5.13 μg m(-3), whereas that of PM2.5 was 4.3 μg m(-3). Contribution of marine components, i.e., Na, Cl and Mg was dominant over the Southern Ocean (79 %) than over the coastal Antarctica where they were dominant in coarse mode (67 %) than in fine mode (53 %) aerosols. The NH4/nss-SO4 ratio of 1.12 in PM2.5 indicates that the NH4 and SO4 ions were in the form of NH4HSO4. Computation of enrichment factors indicate that elements of anthropogenic origin, e.g., Zn, Cu, Pb, etc., were highly enriched with respect to crustal composition.
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Geng L, Schauer AJ, Kunasek SA, Sofen ED, Erbland J, Savarino J, Allman DJ, Sletten RS, Alexander B. Analysis of oxygen-17 excess of nitrate and sulfate at sub-micromole levels using the pyrolysis method. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2013; 27:2411-2419. [PMID: 24097397 DOI: 10.1002/rcm.6703] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 08/04/2013] [Accepted: 08/05/2013] [Indexed: 06/02/2023]
Abstract
RATIONALE The oxygen-17 excess (Δ(17)O) of nitrate and sulfate contains valuable information regarding their atmospheric formation pathways. However, the current pyrolysis method to measure Δ(17)O requires large sample amounts (>4 µmol for nitrate and >1 µmol for sulfate). We present a new approach employing a Gas Bench interface which cryofocuses O2 produced from sample pyrolysis, enabling the analysis of sub-micromole size samples. METHODS Silver nitrate or sulfate at sub-micromole levels in a sample container was thermally decomposed to O2 and byproducts in a modified Temperature Conversion/Elemental Analyzer (TC/EA). Byproducts (mainly NO2 for silver nitrate and SO2 for silver sulfate) were removed in a liquid nitrogen trap and the sample O2 was carried by ultra-pure helium (He) gas to a Gas Bench II interface where it was cryofocused prior to entering an isotope ratio mass spectrometer. RESULTS Analysis of the international nitrate reference material USGS35 (Δ(17)O = 21.6‰) within the size range of 300-1000 nmol O2 gave a mean Δ(17)O value of (21.6 ± 0.69) ‰ (mean ±1σ). Three inter-laboratory calibrated sulfate reference materials, Sulf-α, Sulf-β and Sulf-ε, each within the size range of 180-1000 nmol O2, were analyzed and shown to possess mean Δ(17)O values of (0.9 ± 0.10)‰, (2.1 ± 0.25)‰ and (7.0 ± 0.63)‰, respectively. CONCLUSIONS The analyses of nitrate and sulfate reference materials at sub-micromole levels gave Δ(17)O values consistent with their accepted values. This new approach of employing the Gas Bench to cryofocus O2 after the pyrolysis of AgNO3 and Ag2SO4 particularly benefits the effort of measuring Δ(17)O in sample types with a low abundance of nitrate and sulfate such as ice cores.
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Affiliation(s)
- Lei Geng
- Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA
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Marchant DR, Mackay SL, Lamp JL, Hayden AT, Head JW. A review of geomorphic processes and landforms in the Dry Valleys of southern Victoria Land: implications for evaluating climate change and ice-sheet stability. ACTA ACUST UNITED AC 2013. [DOI: 10.1144/sp381.10] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractThe Dry Valleys are subdivided into three microclimate zones on the basis of summertime measurements of atmospheric temperature, soil moisture, relative humidity and wind-speed/ direction. Subtle variations in these climate parameters result in considerable differences in process geomorphology and in the development of unique landforms within each zone. The mapped zones include a coastal thaw zone, an inland mixed zone and a stable upland zone. Landforms within each zone are subdivided into macroscale features (e.g. valleys, slopes and gullies), mesoscale features (e.g. polygons and viscous-flow features) and microscale features (e.g. rock and near-surface soil features, including the effects of salt weathering, wind erosion and pitting). We present a review of landscape development in the Dry Valleys with implications for long-term climate change and ice-sheet stability. Chronological control is afforded by 40Ar/39Ar dating of volcanic ash-fall deposits and cosmogenic nuclide analyses of surface boulders. Collectively, the data call for persistent cold and dry conditions in the stable upland zone for approximately the last 14 Ma, although some level of climatic amelioration and landform modification may have occurred within low-lying regions and in the inland mixed zone.
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Affiliation(s)
- D. R. Marchant
- Department of Earth and Environment, Boston University, Boston, MA 02215, USA
| | - S. L. Mackay
- Department of Earth and Environment, Boston University, Boston, MA 02215, USA
| | - J. L. Lamp
- Department of Earth and Environment, Boston University, Boston, MA 02215, USA
| | - A. T. Hayden
- Department of Earth and Environment, Boston University, Boston, MA 02215, USA
| | - J. W. Head
- Department of Geological Sciences, Brown University, Providence, RI 02912, USA
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Schauer AJ, Kunasek SA, Sofen ED, Erbland J, Savarino J, Johnson BW, Amos HM, Shaheen R, Abaunza M, Jackson TL, Thiemens MH, Alexander B. Oxygen isotope exchange with quartz during pyrolysis of silver sulfate and silver nitrate. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2012; 26:2151-2157. [PMID: 22886811 DOI: 10.1002/rcm.6332] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
RATIONALE Triple oxygen isotopes of sulfate and nitrate are useful metrics for the chemistry of their formation. Existing measurement methods, however, do not account for oxygen atom exchange with quartz during the thermal decomposition of sulfate. We present evidence for oxygen atom exchange, a simple modification to prevent exchange, and a correction for previous measurements. METHODS Silver sulfates and silver nitrates with excess (17)O were thermally decomposed in quartz and gold (for sulfate) and quartz and silver (for nitrate) sample containers to O(2) and byproducts in a modified Temperature Conversion/Elemental Analyzer (TC/EA). Helium carries O(2) through purification for isotope-ratio analysis of the three isotopes of oxygen in a Finnigan MAT253 isotope ratio mass spectrometer. RESULTS The Δ(17)O results show clear oxygen atom exchange from non-zero (17)O-excess reference materials to zero (17)O-excess quartz cup sample containers. Quartz sample containers lower the Δ(17)O values of designer sulfate reference materials and USGS35 nitrate by 15% relative to gold or silver sample containers for quantities of 2-10 µmol O(2). CONCLUSIONS Previous Δ(17)O measurements of sulfate that rely on pyrolysis in a quartz cup have been affected by oxygen exchange. These previous results can be corrected using a simple linear equation (Δ(17)O(gold) = Δ(17)O(quartz) * 1.14 + 0.06). Future pyrolysis of silver sulfate should be conducted in gold capsules or corrected to data obtained from gold capsules to avoid obtaining oxygen isotope exchange-affected data.
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Affiliation(s)
- Andrew J Schauer
- Department of Earth and Space Sciences, University of Washington, Seattle, WA, USA.
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Michalski G, Kasem M, Rech JA, Adieu S, Showers WS, Genna B, Thiemens M. Uncertainties in the oxygen isotopic composition of barium sulfate induced by coprecipitation of nitrate. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2008; 22:2971-2976. [PMID: 18763262 DOI: 10.1002/rcm.3687] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Coprecipitation of nitrate and sulfate by barium has probably resulted in significant error in numerous studies dealing with the oxygen isotopic composition of natural sulfates using chemical/thermal conversion of BaSO(4) and analysis by isotope ratio mass spectrometry. In solutions where NO(3) (-)/SO(4) (2-) molar ratios are above 2 the amount of nitrate coprecipitated with BaSO(4) reaches a maximum of approximately 7% and decreases roughly linearly as the molar ratio decreases. The fraction of coprecipitated nitrate appears to increase with decreasing pH and is also affected by the nature of the cations in the precipitating solution. The size of the oxygen isotope artifact in sulfate depends both on the amount of coprecipitated nitrate and the delta(18)O and Delta(17)O values of the nitrate, both of which can be highly variable. The oxygen isotopic composition of sulfate extracted from atmospheric aerosols or rain waters are probably severely biased because photochemical nitrate is usually also present and it is highly enriched in (18)O (delta(18)O approximately 50-90 per thousand) and has a large mass-independent isotopic composition (Delta(17)O approximately 20-32 per thousand). The sulfate delta(18)O error can be 2-5 per thousand with Delta(17)O artifacts reaching as high as 4.0 per thousand.
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Affiliation(s)
- Greg Michalski
- Department of Earth & Atmospheric Sciences, Purdue University, West Lafayette, IN 47907-2051, USA.
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Abstract
To get a proper perspective on the current status of atmospheric ozone, which protects the biosphere from ultraviolet-B (UV-B; 280-315 nm) radiation, it would be of value to know how ozone and UV-B radiation have varied in the past. The record of worldwide ozone monitoring goes back only a few decades, and the record of reliable UV-B measurements is even shorter. Here we review indirect methods to assess their status further back in time. These include variations in the Sun's emission and how these affect the atmosphere, changes in the Earth's orbit, geologic imprints of atmospheric ozone, effects of catastrophic events such as volcanic eruptions, biological proxies of UV-B radiation, the spectral signature of terrestrial ozone in old recordings of star spectra, and the modeling of UV-B irradiance from ozone data and meteorological recordings. Although reliable reconstructions do not yet extend far into the past, there is some hope for future progress.
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Affiliation(s)
- Lars Olof Björn
- Lund University, Department of Cell and Organism Biology, Sweden.
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13
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Bao H, Marchant DR. Quantifying sulfate components and their variations in soils of the McMurdo Dry Valleys, Antarctica. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jd006669] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Savarino J, Bekki S, Cole-Dai J, Thiemens MH. Evidence from sulfate mass independent oxygen isotopic compositions of dramatic changes in atmospheric oxidation following massive volcanic eruptions. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2003jd003737] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Joël Savarino
- Laboratoire de Glaciologie et Géophysique de l'Environnement; Université Joseph Fourier, CNRS; St. Martin d'Hères France
| | - Slimane Bekki
- Service d'Aéronomie; Université Pierre et Marie Curie, CNRS; Paris France
| | - Jihong Cole-Dai
- Department of Chemistry and Biochemistry; South Dakota State University; Brookings South Dakota USA
| | - Mark H. Thiemens
- Department of Chemistry and Biochemistry; University of California, San Diego; La Jolla California USA
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15
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Romero AB. Mass-independent sulfur isotopic compositions in present-day sulfate aerosols. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2003jd003660] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bao H. Multiple oxygen and sulfur isotopic analyses on water-soluble sulfate in bulk atmospheric deposition from the southwestern United States. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jd003022] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Miller MF, Franchi IA, Thiemens MH, Jackson TL, Brack A, Kurat G, Pillinger CT. Mass-independent fractionation of oxygen isotopes during thermal decomposition of carbonates. Proc Natl Acad Sci U S A 2002; 99:10988-93. [PMID: 12167677 PMCID: PMC123197 DOI: 10.1073/pnas.172378499] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nearly all chemical processes fractionate 17O and 18O in a mass-dependent way relative to 16O, a major exception being the formation of ozone from diatomic oxygen in the presence of UV radiation or electrical discharge. Investigation of oxygen three-isotope behavior during thermal decomposition of naturally occurring carbonates of calcium and magnesium in vacuo has revealed that, surprisingly, anomalous isotopic compositions are also generated during this process. High-precision measurements of the attendant three-isotope fractionation line, and consequently the magnitude of the isotopic anomaly (delta17O), demonstrate that the slope of the line is independent of the nature of the carbonate but is controlled by empirical factors relating to the decomposition procedure. For a slope identical to that describing terrestrial silicates and waters (0.5247 +/- 0.0007 at the 95% confidence level), solid oxides formed during carbonate pyrolysis fit a parallel line offset by -0.241 +/- 0.042 per thousand. The corresponding CO2 is characterized by a positive offset of half this magnitude, confirming the mass-independent nature of the fractionation. Slow, protracted thermolysis produces a fractionation line of shallower slope (0.5198 +/- 0.0007). These findings of a 17O anomaly being generated from a solid, and solely by thermal means, provide a further challenge to current understanding of the nature of mass-independent isotopic fractionation.
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Affiliation(s)
- Martin F Miller
- Planetary and Space Sciences Research Institute, The Open University, Walton Hall, Milton Keynes MK7 6AA, United Kingdom.
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Farquhar J, Savarino J, Airieau S, Thiemens MH. Observation of wavelength-sensitive mass-independent sulfur isotope effects during SO2photolysis: Implications for the early atmosphere. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000je001437] [Citation(s) in RCA: 370] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Zhu XK, Guo Y, O'Nions RK, Young ED, Ash RD. Isotopic homogeneity of iron in the early solar nebula. Nature 2001; 412:311-3. [PMID: 11460156 DOI: 10.1038/35085525] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The chemical and isotopic homogeneity of the early solar nebula, and the processes producing fractionation during its evolution, are central issues of cosmochemistry. Studies of the relative abundance variations of three or more isotopes of an element can in principle determine if the initial reservoir of material was a homogeneous mixture or if it contained several distinct sources of precursor material. For example, widespread anomalies observed in the oxygen isotopes of meteorites have been interpreted as resulting from the mixing of a solid phase that was enriched in 16O with a gas phase in which 16O was depleted, or as an isotopic 'memory' of Galactic evolution. In either case, these anomalies are regarded as strong evidence that the early solar nebula was not initially homogeneous. Here we present measurements of the relative abundances of three iron isotopes in meteoritic and terrestrial samples. We show that significant variations of iron isotopes exist in both terrestrial and extraterrestrial materials. But when plotted in a three-isotope diagram, all of the data for these Solar System materials fall on a single mass-fractionation line, showing that homogenization of iron isotopes occurred in the solar nebula before both planetesimal accretion and chondrule formation.
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Affiliation(s)
- X K Zhu
- Department of Earth Sciences, University of Oxford, UK.
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