2024 |
Aroskay, A., Martin, E., Bekki, S., Le Pennec, J., Savarino, J., Temel, A., et al. (2024). Geological Evidence Of Extensive N- Fixation By Volcanic Lightning During Very Large Explosive Eruptions. Proceedings Of The National Academy Of Sciences Of The United States Of America, 1211(7).
Abstract: Most Of The Nitrogen (N) Accessible For Life Is Trapped In Dinitrogen (N2), The Most Stable Atmospheric Molecule. In Order To Be Metabolized By Living Organisms, N2 Has To Be Converted Into Biologically Assimilable Forms, So – Called Fixed N. Nowadays, Nearly All The N- Fixation Is Achieved Through Biological And Anthropogenic Processes. However, In Early Prebiotic Environments Of The Earth, N- Fixation Must Have Occurred Via Natural Abiotic Processes. One Of The Most Invoked Processes Is Electrical Discharges, Including From Thunderstorms And Lightning Associated With Volcanic Eruptions. Despite The Frequent Occurrence Of Volcanic Lightning During Explosive Eruptions And Convincing Laboratory Experimentation, No Evidence Of Substantial N- Fixation Has Been Found In Any Geological Archive. Here, We Report On The Discovery Of A Significant Amount Of Nitrate In Volcanic Deposits From Neogene Caldera- Forming Eruptions, Which Are Well Correlated With The Concentrations Of Species Directly Emitted By Volcanoes (Sulfur, Chlorine). The Multi- Isotopic Composition (Delta 18O, Delta 17O) Of The Nitrates Reveals That They Originate From The Atmospheric Oxidation Of Nitrogen Oxides Formed By Volcanic Lightning. According To These First Geological Volcanic Nitrate Archive, We Estimate That, On Average, About 60 Tg Of N Can Be Fixed During A Large Explosive Event. Our Findings Hint At A Unique Role Potentially Played By Subaerial Explosive Eruptions In Supplying Essential Ingredients For The Emergence Of Life On Earth.
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2023 |
Celli, G., Cairns, W., Scarchilli, C., Cuevas, C., Saiz-Lopez, A., Savarino, J., et al. (2023). Bromine, Iodine And Sodium Along The Eaiist Traverse: Bulk And Surface Snow Latitudinal Variability. Environmental Research, 2392.
Abstract: During The East Antarctic International Ice Sheet Traverse (Eaiist, December 2019), In An Unexplored Part Of The East Antarctic Plateau, Snow Samples Were Collected To Expand Our Knowledge Of The Latitudinal Variability Of Iodine, Bromine And Sodium As Well As Their Relation In Connection With Emission Processes And Photochemical Activation In This Unexplored Area. A Total Of 32 Surface (0-5 Cm) And 32 Bulk (Average Of 1 M Depth) Samples Were Taken And Analysed By Inductively Coupled Plasma Mass Spectrometry (Icp-Ms). Our Results Show That There Is No Relevant Latitudinal Trend For Bromine And Sodium. For Bromine They Also Show That It Has No Sig-Nificant Post-Depositional Mechanisms While Its Inland Surface Snow Concentration Is Influenced By Spring Coastal Bromine Explosions. Iodine Concentrations Are Several Orders Of Magnitude Lower Than Bromine And Sodium And They Show A Decreasing Trend In The Surface Samples Concentration Moving Southward. This Suggests That Other Processes Affect Its Accumulation In Surface Snow, Probably Related To The Radial Reduction In The Ozone Layer Moving Towards Central Antarctica. Even Though All Iodine, Bromine And Sodium Present Similar Long-Range Transport From The Dominant Coastal Antarctic Sources, The Annual Seasonal Cycle Of The Ozone Hole Over Antarctica Increases The Amount Of Uv Radiation (In The 280-320 Nm Range) Reaching The Surface, Thereby Affecting The Surface Snow Photoactivation Of Iodine. A Comparison Between The Bulk And Surface Samples Supports The Conclusion That Iodine Undergoes Spring And Summer Snow Recycling That Increases Its Atmospheric Lifetime, While It Tends To Accumulate During The Winter Months When Photochemistry Ceases.
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Chaillot, J., Dasari, S., Fleurbaey, H., Daeron, M., Savarino, J., & Kassi, S. (2023). High-Precision Laser Spectroscopy Of H<Sub>2</Sub>S For Simultaneous Probing Of Multiple-Sulfur Isotopes. Environmental Science-Advances, 2(1), 78–86.
Abstract: The Simultaneous Monitoring Of The Triple Stable S-Isotopes (S-32, S-33 And S-34) Of Hydrogen Sulfide Has Been Conducted With A Vcof-Crds Set-Up (A V-Shaped Cavity For Optical Feedback Coupled To A Cavity Ring Down Spectrometer). The Spectroscopic Investigation Of H2S Was Performed For The First Time In The Near-Infrared Region (Approximate To 1.6 Mu M) With A Stabilized Laser Of Linewidth < 1 Khz And An Optical Pathlength Of 90 Km, Providing Unparalleled Sensitivity And Precision. Pressure Dependencies Of The System Were Explored To As Low As 0.1 Mbar Revealing The Lamb Dip Feature Of The Isotopologue Transitions. A Model Was Developed To Fit Experimental Spectra With Accuracy Better By One Order Of Magnitude Than What The Literature Provides. The S-Isotope Composition Delta S-34 And S-Isotope Anomaly Delta S-33 Are Determined With An Uncertainty Of 5 X 10(-6) Within 10 Seconds, Limited By H2S Reactivity Inside The Measurement Cell. Such High Precision Represents A New Benchmark For Laser Spectroscopy Of H2S And Optical Determination Of Isotopic Measurements And Makes Vcof-Crds A Promising Tool For A Plethora Of Future Applications.
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Lamothe, A., Savarino, J., Ginot, P., Soussaintjean, L., Gautier, E., Akers, P., et al. (2023). An Extraction Method For Nitrogen Isotope Measurement Of Ammonium In Alow-Concentration Environment. Atmospheric Measurement Techniques, 161(171), 4015–4030.
Abstract: Ammonia (Nh3) Participates In The Nucleation And Growth Of Aerosols And Thus Plays A Major Role In Atmospheric Transparency, Pollution, Health, And Climate-Related Issues. Understanding Its Emission Sources Through Nitrogen Stable Isotopes Is Therefore A Major Focus Of Current Work To Mitigate The Adverse Effects Of Aerosol Formation. Since Ice Cores Can Preserve The Past Chemical Composition Of The Atmosphere For Centuries, They Are A Top Tool Of Choice For Understanding Past Nh3 Emissions Through Ammonium (Nh4+), The Form Of Nh3 Archived In Ice. However, The Remote Or High-Altitude Sites Where Glaciers And Ice Sheets Are Typically Localized Have Relatively Low Fluxes Of Atmospheric Nh4+ Deposition, Which Makes Ice Core Samples Very Sensitive To Laboratory Nh3 Contamination. As A Result, Accurate Techniques For Identifying And Tracking Nh3 Emissions Through Concentration And Isotopic Measurements Are Highly Sought To Constrain Uncertainties In Nh3 Emission Inventories And Atmospheric Reactivity Unknowns. Here, We Describe A Solid-Phase Extraction Method For Nh4+ Samples Of Low Concentration That Limits External Contamination And Produces Precise Isotopic Results. By Limiting Nh3Atm Exposure With A Scavenging Fume Hood And Concentrating The Targeted Nh4+ Through Ion Exchange Resin, We Successfully Achieve Isotopic Analysis Of 50 Nmol Nh4+ Samples With A 0.6 Parts Per Thousand Standard Deviation. This Extraction Method Is Applied To An Alpine Glacier Ice Core From Col Du Dome, Mont Blanc, Where We Successfully Demonstrate The Analytical Approach Through The Analysis Of Two Replicate 8 M Water Equivalent Ice Cores Representing 4 Years Of Accumulation With A Reproducibility Of +/- 2.1 Parts Per Thousand. Applying This Methodology To Other Ice Cores In Alpine And Polar Environments Will Open New Opportunities For Understanding Past Changes In Nh3 Emissions And Atmospheric Chemistry.
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Neubauer, C., Kantnerova, K., Lamothe, A., Savarino, J., Hilkert, A., Juchelka, D., et al. (2023). Discovering Nature?S Fingerprints: Isotope Ratio Analysis On Bioanalytical Mass Spectrometers. Journal Of The American Society For Mass Spectrometry, 343(4), 525–537.
Abstract: For A Generation Or More, The Mass Spectrometry That Developed At The Frontier Of Molecular Biology Was Worlds Apart From Isotope Ratio Mass Spectrometry, A Label-Free Approach Done On Optimized Gas-Source Magnetic Sector Instruments. Recent Studies Show That Electrospray-Ionization Orbitraps And Other Mass Spectrom-Eters Widely Used In The Life Sciences Can Be Fine-Tuned For High-Precision Isotope Ratio Analysis. Since Isotope Patterns Form Everywhere In Nature Based On Well-Understood Principles, Intramolecula R Isotope Measure-Ments Allow Unique Insights Into A Fascinating Range Of Research Topics. This Perspective Introduces A Wider Readership To Current Topics In Stable Isotope Research With The Aim Of Discussing How Soft-Ionization Mass Spectrometry Coupled With Ultrahigh Mass Resolution Can Enable Long-Envisioned Progress. We Highlight Novel Prospects Of Observing Isotopes In Intact Polar Compounds And Speculate On Future Directions Of This Adventure Into The Overlapping Realms Of Biology, Chemistry, And Geology.
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2022 |
Aviles, G. P. F., Spadini, L., Sacchi, E., Rossier, Y., Savarino, J., Ramos, O. E., et al. (2022). Hydrogeochemical and nitrate isotopic evolution of a semiarid mountainous basin aquifer of glacial-fluvial and paleolacustrine origin (Lake Titicaca, Bolivia): the effects of natural processes and anthropogenic activities. Hydrogeology Journal, 303(1), 181–201.
Abstract: A hydrogeochemical and stable isotopic (delta(15) N-NO3 and delta O-18(NO3)) multitracer approach was combined with previous geological and hydrogeological knowledge in a groundwater-dominated basin, located within the semiarid region of the Bolivian Altiplano (SE of Lake Titicaca). Major natural processes and anthropogenic impacts controlling water chemistry and isotopic compositions of groundwater were identified and corresponding aquifer impacted zones determined. The main natural processes are, by following water flowlines, (1) silicate weathering in the piedmont subsystem (similar to 4,600-3,910 m asl, Ca(Mg)HCO3 facies), (2) Na-Ca exchange within glacial-fluvial deposits overlying paleolacustrine deposits (similar to 3,910 to 3,860 m asl, Na-HCO3 facies), and (3) evaporite dissolution in the confined zone of the lacustrine plain (similar to 3,860-3,810 m asl, Na-Cl-SO4 facies). The highest contributions of anthropogenic nitrate in groundwater have been observed at 3,960-3,860 m asl in the piedmont subsystem and were isotopically associated with leaching from areas influenced by manure piles, synthetic N fertilizers, and sewage collector pipes. In this subsystem, natural water-rock interactions could be deciphered with minimal anthropogenic impact, allowing nitrate sources to be clearly identified. Denitrification, occurring in the topographic lows of the piedmont subsystem, was identified as the main natural attenuation process. The multitracer approach provided a consistent understanding of the major processes that take place along the groundwater flow system and confirmed the significant role of anthropogenic nitrate. This aquifer system thus represents an ideal model of the region's hydrochemical evolution along the gravity-driven flow caused by natural water-rock interaction processes and the influence of anthropogenic contamination.
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Barbero, A., Grilli, R., Frey, M., Blouzon, C., Helmig, D., Caillon, N., et al. (2022). Summer Variability Of The Atmospheric No2 : No Ratio A Dome C On The East Antarctic Plateau. Atmospheric Chemistry And Physics, 222(181), 12025–12054.
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Cao, Y., Jiang, Z., Alexander, B., Cole-Dai, J., Savarino, J., Erbland, J., et al. (2022). On The Potential Fingerprint Of The Antarctic Ozone Hole In Ice-Core Nitrate Isotopes: A Case Study Based On A South Pole Ice Core. Atmospheric Chemistry And Physics, 222(202), 13407–13422.
Abstract: Column Ozone Variability Has Important Implications For Surface Photochemistry And The Climate. Ice-Core Nitrate Isotopes Are Suspected To Be Influenced By Column Ozone Variability And Delta N-15(No3-) Has Been Sought To Serve As A Proxy Of Column Ozone Variability. In This Study, We Examined The Ability Of Ice-Core Nitrate Isotopes To Reflect Column Ozone Variability By Measuring Delta N-15(No3-) And Delta O-17(No3-) In A Shallow Ice Core Drilled At The South Pole. The Ice Core Covers The Period 1944-2005, And During This Period Delta N-15(No3-) Showed Large Annual Variability ((59.2 +/- 29.3)Parts Per Thousand), But With No Apparent Response To The Antarctic Ozone Hole. Utilizing A Snow Photochemical Model, We Estimated 6.9 Parts Per Thousand Additional Enrichments In Delta N-15(No3-) Could Be Caused By The Development Of The Ozone Hole. Nevertheless, This Enrichment Is Small And Masked By The Effects Of The Snow Accumulation Rate At The South Pole Over The Same Period Of The Ozone Hole. The Delta O-17(No3-) Record Has Displayed A Decreasing Trend By Similar To 3.4 Parts Per Thousand Since 1976. This Magnitude Of Change Cannot Be Caused By Enhanced Post-Depositional Processing Related To The Ozone Hole. Instead, The Delta O-17(No3-) Decrease Was More Likely Due To The Proposed Decreases In The O-3 / Hox Ratio In The Extratropical Southern Hemisphere. Our Results Suggest Ice-Core Delta N-15(No3-) Is More Sensitive To Snow Accumulation Rate Than To Column Ozone, But At Sites With A Relatively Constant Snow Accumulation Rate, Information Of Column Ozone Variability Embedded In Delta N-15(No3-) Should Be Retrievable.
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Jiang, Z., Savarino, J., Alexander, B., Erbland, J., Jaffrezo, J. L., & Geng, L. (2022). Impacts Of Post-Depositional Processing On Nitrate Isotopes In The Snow and the overlying atmosphere at Summit, Greenland. Cryosphere, 161(7), 2709–2724.
Abstract: The effect of post-depositional processing on the preservation of snow nitrate isotopes at Summit, Greenland, remains a subject of debate and is relevant to the quantitative interpretation of ice-core nitrate (isotopic) records at high snow accumulation sites. Here we present the first year-round observations of atmospheric nitrate and its isotopic compositions at Summit and compare them with published surface snow and snowpack observations. The atmospheric delta N-15(NO3-) remained negative throughout the year, ranging from -3.1 parts per thousand to -47.9 parts per thousand with a mean of (-14.8 +/- 7.3)parts per thousand (n = 54), and displayed minima in spring which are distinct from the observed spring delta N-15(NO3-) maxima in snowpack. The spring average atmospheric delta N-15(NO3-) was (-17.9 +/- 8.3) parts per thousand (n = 21), significantly depleted compared to the snowpack spring average of (4.6 +/- 2.1)parts per thousand, while the surface snow delta N-15(NO3-) of (-6.8 +/- 0.5)parts per thousand was in between the atmosphere and the snowpack. The differences in atmospheric, surface snow and snowpack delta N-15(NO3-) are best explained by the photo-driven post-depositional processing of snow nitrate, with potential contributions from fractionation during nitrate deposition. In contrast to delta N-15(NO3-) the atmospheric Delta O-1(7)(NO3-) was of a similar seasonal pattern and magnitude of change to that in the snowpack, suggesting little to no changes in Delta O-1(7)(NO3-) from photolysis, consistent with previous modeling results. The atmospheric delta O-18(NO3-) varied similarly to atmospheric Delta O-1(7)(NO3-), with summer low and winter high values. However, the difference between atmospheric and snow delta O-18(NO3-) was larger than that of Delta O-17(NO3-). We found a strong correlation between atmospheric delta O-18(NO3-) and Delta O-17(NO3-) that is very similar to previous measurements for surface snow at Summit, suggesting that atmospheric delta O-18(NO3-) versus Delta O-17(NO3-) relationships were conserved during deposition. However, we found the linear relationships between delta O-18 and Delta O-17(NO3-) were significantly different for snowpack compared to atmospheric samples. This likely suggests the oxygen isotopes are also affected before preservation in the snow at Summit, but the degree of change for delta O-18(NO3-) should be larger than that of Delta O-17(NO3-). This is because photolysis is a massdependent process that would directly affect delta O-18(NO3-) in snow but not Delta O-17(NO3-) as the latter is a mass-independent signal. Although there were uncertainties associated with the complied dataset, the results suggested that post-depositional processing at Summit can induce changes in nitrate isotopes, especially delta N-15(NO3-), consistent with a previous modeling study. This reinforces the importance of understanding the effects of post-depositional processing before ice-core nitrate isotope interpretation, even for sites with relatively high snow accumulation rates.
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Lim, S., Hwang, J., Lee, M., Czimczik, C. I., Xu, X. M., & Savarino, J. (2022). Robust Evidence Of C-14, C-13, And N-15 Analyses Indicating Fossil Fuel Sources for Total Carbon and Ammonium in Fine Aerosols in Seoul Megacity. Environmental Science & Technology, 565(111), 6894–6904.
Abstract: Carbon- and nitrogen-containing aerosols are ubiquitous in urban atmospheres and play important roles in air quality and climate change. We determined the C-14 fraction modern (f(M)) and delta C-13 of total carbon (TC) and delta N-15 of NH4+ in the PM2.5 collected in Seoul megacity during April 2018 to December 2019. The seasonal mean delta C-13 values were similar to -25.1% +/- 2.0% in warm and -24.2%+/- 0.82% in cold seasons. Mean delta N-15 values were higher in warm (16.4%+/- 2.8%) than in cold seasons (4.0%+/- 6.1%), highlighting the temperature effects on atmospheric NH3 levels and phase- equilibrium isotopic exchange during the conversion of NH3 to NH4+. While 37% +/- 10% of TC was apportioned to fossilfuel sources on the basis of f(M) values, delta N-15 indicated a higher contribution of emissions from vehicle exhausts and electricity generating units (power-plant NH3 slip) to NH3: 60% +/- 26% in warm season and 66% +/- 22% in cold season, based on a Bayesian isotope-mixing model. The collective evidence of multiple isotope analysis reasonably supports the major contribution of fossil-fuel-combustion sources to NH4+, in conjunction with TC, and an increased contribution from vehicle emissions during the severe PM2.5 pollution episodes. These findings demonstrate the efficacy of a multiple-isotope approach in providing better insight into the major sources of PM2.5 in the urban atmosphere.
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