ACS Earth and Space Chemistry最新文献

{"title":"Thermodynamic Constraints on the Citric Acid Cycle and Related Reactions in Ocean World Interiors.","authors":"Seda Işık, Mohit Melwani Daswani, Emre Işık, Jessica M Weber, Nazlı Olgun Kıyak","doi":"10.1021/acsearthspacechem.4c00371","DOIUrl":"10.1021/acsearthspacechem.4c00371","url":null,"abstract":"<p><p>Icy ocean worlds in our solar system have attracted significant interest for their astrobiological and biogeochemical potential due to the predicted presence of global subsurface liquid water oceans, the presence of organics in Enceladus and Titan, and plausible sources of chemical energy available for life therein. A difficulty in placing quantitative constraints on the occurrence and effectiveness of biogeochemical reactions favorable for life and metabolism in ocean worlds is the paucity of thermodynamic data for the relevant reactions for pressure, temperature and compositional conditions pertaining to ocean worlds, in addition to uncertainties in the estimation of such conditions. Here, we quantify the thermodynamic viability and energetics of various reactions of interest to metabolism at pressures and temperatures relevant to ocean worlds Enceladus, Europa, Titan and Ganymede, and conditions relevant to the Lost City Hydrothermal Field for comparison. Specifically, we examine the tricarboxylic acid cycle (also known as TCA, Krebs cycle, or citric acid cycle) and a plausible precursor prebiotic network of reactions leading to the TCA cycle. We use DEWPython, a program based on the deep earth water (DEW) model (which is a high pressure and high temperature extension of the HelgesonKirkhamFlowers equation of state used to calculate thermodynamic properties of ions and complexes in aqueous solutions), to compute the equilibrium constants and the Gibbs free energy changes for given reactions, as a function of pressure and temperature. Using instantaneous concentrations of inorganics and organics from terrestrial microbial experiments and those derived from the Cassini mission for Enceladus, we calculate chemical affinities of reactions in the network. We carry out similar calculations using the SUPCRT model for lower pressures and temperatures. Together, the two models span temperatures between 0 and 1200 °C and pressures between 1 bar and 60 kbar. We found that across the majority of oceanic pressuretemperature profiles, certain TCA cycle species, such as citrate and succinate, accumulate, while others, including fumarate and oxaloacetate, exhibit a diminishing trend. This observation suggests that the internal conditions of ocean worlds may not thermodynamically favor a unidirectional TCA cycle, thereby implying an additional source of energy (e.g., metabolites) to overcome energy bottlenecks. Notably, we find similar bottlenecks at the Lost City Hydrothermal Field, which is undoubtedly inhabited by organisms. In the prebiotic network, we found that pyruvate and acetate exhibit remarkable stability and accumulate in substantial quantities, thereby feeding the TCA cycle through the production of citrate. In this case the oxaloacetate bottleneck within the TCA cycle is bypassed via the prebiotic pathway. We also found that the formation of all TCA cycle species from inorganic compounds (CO<sub>2</sub> + H<sub>2</sub>) is highly favored","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 6","pages":"1392-1412"},"PeriodicalIF":2.9,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12183719/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144482529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Energetics of Neodymium Titanate Glass Made on Earth and in Space","authors":"Laura Bonatti,&nbsp;Tamilarasan Subramani,&nbsp;Stephen K. Wilke,&nbsp;Richard Weber and Alexandra Navrotsky*,&nbsp;","doi":"10.1021/acsearthspacechem.5c0001110.1021/acsearthspacechem.5c00011","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.5c00011https://doi.org/10.1021/acsearthspacechem.5c00011","url":null,"abstract":"<p >Space exploration presents an increased need for manufacturing materials beyond Earth due to spacecraft launch costs and logistical challenges of long missions. Differences in convection, buoyancy, and sedimentation under microgravity conditions compared to those at the Earth’s surface have the potential to impact the properties of manufactured materials. In order to better understand microgravity effects on melt-quenched glass, this study explores the energetics of crystallization of neodymium titanate glass (83TiO₂-17Nd₂O₃, “NT”), a potential material for advanced optical applications. Differential scanning calorimetry (DSC) reveals no significant thermodynamic differences between NT manufactured on Earth and aboard the International Space Station (ISS). The glass transition and crystallization temperatures are remarkably similar for glasses made on Earth and in space, consistent with their similar atomic structures. Additional research to investigate the critical cooling rates and behavior of glasses is needed to optimize glass processing in low gravity and to identify glass systems that benefit the most from the additional control of heat and mass transfer during processing.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 6","pages":"1277–1281 1277–1281"},"PeriodicalIF":2.9,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144312444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermodynamic Constraints on the Citric Acid Cycle and Related Reactions in Ocean World Interiors","authors":"Seda Işık*,&nbsp;Mohit Melwani Daswani*,&nbsp;Emre Işık,&nbsp;Jessica M. Weber and Nazlı Olgun Kıyak,&nbsp;","doi":"10.1021/acsearthspacechem.4c0037110.1021/acsearthspacechem.4c00371","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00371https://doi.org/10.1021/acsearthspacechem.4c00371","url":null,"abstract":"&lt;p &gt;Icy ocean worlds in our solar system have attracted significant interest for their astrobiological and biogeochemical potential due to the predicted presence of global subsurface liquid water oceans, the presence of organics in Enceladus and Titan, and plausible sources of chemical energy available for life therein. A difficulty in placing quantitative constraints on the occurrence and effectiveness of biogeochemical reactions favorable for life and metabolism in ocean worlds is the paucity of thermodynamic data for the relevant reactions for pressure, temperature and compositional conditions pertaining to ocean worlds, in addition to uncertainties in the estimation of such conditions. Here, we quantify the thermodynamic viability and energetics of various reactions of interest to metabolism at pressures and temperatures relevant to ocean worlds Enceladus, Europa, Titan and Ganymede, and conditions relevant to the Lost City Hydrothermal Field for comparison. Specifically, we examine the tricarboxylic acid cycle (also known as TCA, Krebs cycle, or citric acid cycle) and a plausible precursor prebiotic network of reactions leading to the TCA cycle. We use DEWPython, a program based on the deep earth water (DEW) model (which is a high pressure and high temperature extension of the Helgeson─Kirkham─Flowers equation of state used to calculate thermodynamic properties of ions and complexes in aqueous solutions), to compute the equilibrium constants and the Gibbs free energy changes for given reactions, as a function of pressure and temperature. Using instantaneous concentrations of inorganics and organics from terrestrial microbial experiments and those derived from the Cassini mission for Enceladus, we calculate chemical affinities of reactions in the network. We carry out similar calculations using the SUPCRT model for lower pressures and temperatures. Together, the two models span temperatures between 0 and 1200 °C and pressures between 1 bar and 60 kbar. We found that across the majority of oceanic pressure─temperature profiles, certain TCA cycle species, such as citrate and succinate, accumulate, while others, including fumarate and oxaloacetate, exhibit a diminishing trend. This observation suggests that the internal conditions of ocean worlds may not thermodynamically favor a unidirectional TCA cycle, thereby implying an additional source of energy (e.g., metabolites) to overcome energy bottlenecks. Notably, we find similar bottlenecks at the Lost City Hydrothermal Field, which is undoubtedly inhabited by organisms. In the prebiotic network, we found that pyruvate and acetate exhibit remarkable stability and accumulate in substantial quantities, thereby feeding the TCA cycle through the production of citrate. In this case the oxaloacetate bottleneck within the TCA cycle is bypassed via the prebiotic pathway. We also found that the formation of all TCA cycle species from inorganic compounds (CO&lt;sub&gt;2&lt;/sub&gt; + H&lt;sub&gt;2&lt;/sub&gt;) is highly favored t","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 6","pages":"1392–1412 1392–1412"},"PeriodicalIF":2.9,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00371","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144312445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IR-Induced CO Photodesorption from Pure CO Ice and CO on Amorphous Solid Water.","authors":"Laura Slumstrup, John D Thrower, Johanna G M Schrauwen, Thanja Lamberts, Emily R Ingman, Domantas Laurinavicius, Jessalyn DeVine, Jeroen Terwisscha van Scheltinga, Julia C Santos, Jennifer A Noble, Gabi Wenzel, Martin R S McCoustra, Wendy A Brown, Harold Linnartz, Liv Hornekær, Herma M Cuppen, Britta Redlich, Sergio Ioppolo","doi":"10.1021/acsearthspacechem.5c00040","DOIUrl":"10.1021/acsearthspacechem.5c00040","url":null,"abstract":"<p><p>Carbon monoxide (CO) is a key component of the icy mantles that form on the surfaces of dust grains in the interstellar medium. In dense molecular clouds, where grain temperatures are around 10 K, CO freezes out as a nonpolar layer on top of H₂O ice. This CO plays an important role in the formation of complex organic molecules (COMs) through reactions with hydrogen atoms. Interstellar grains are also exposed to photons and charged particles that can both drive chemical reactions and promote desorption of molecules, providing an important link between the solid state reservoir of molecules and the gas phase. While several studies have considered UV photon driven desorption mechanisms, the UV component of the interstellar radiation field is strongly attenuated within dense clouds, with the internal cloud field being dominated by IR photons. We have used the FELIX IR Free Electron Laser (FEL) FEL-2 to irradiate a few monolayer film of CO deposited on the top of amorphous solid water (ASW) and compared the CO desorption yields to those obtained for a pure CO film. Infrared spectroscopy, combined with mass spectrometric detection of desorbing CO molecules, reveals that excitation of vibrational modes in the underlying ASW leads to significant CO desorption. This is in contrast to direct excitation of the stretching mode of CO which results in only inefficient desorption. The desorption efficiencies we derive indicate that energy transfer within ices on interstellar grains might provide an important route to IR photon-induced desorption of volatile species, such as CO.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 6","pages":"1607-1621"},"PeriodicalIF":2.9,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12184678/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144482511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IR-Induced CO Photodesorption from Pure CO Ice and CO on Amorphous Solid Water","authors":"Laura Slumstrup,&nbsp;John D. Thrower*,&nbsp;Johanna G. M. Schrauwen,&nbsp;Thanja Lamberts,&nbsp;Emily R. Ingman,&nbsp;Domantas Laurinavicius,&nbsp;Jessalyn DeVine,&nbsp;Jeroen Terwisscha van Scheltinga,&nbsp;Julia C. Santos,&nbsp;Jennifer A. Noble,&nbsp;Gabi Wenzel,&nbsp;Martin R. S. McCoustra,&nbsp;Wendy A. Brown,&nbsp;Harold Linnartz,&nbsp;Liv Hornekær,&nbsp;Herma M. Cuppen,&nbsp;Britta Redlich and Sergio Ioppolo*,&nbsp;","doi":"10.1021/acsearthspacechem.5c0004010.1021/acsearthspacechem.5c00040","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.5c00040https://doi.org/10.1021/acsearthspacechem.5c00040","url":null,"abstract":"<p >Carbon monoxide (CO) is a key component of the icy mantles that form on the surfaces of dust grains in the interstellar medium. In dense molecular clouds, where grain temperatures are around 10 K, CO freezes out as a nonpolar layer on top of H₂O ice. This CO plays an important role in the formation of complex organic molecules (COMs) through reactions with hydrogen atoms. Interstellar grains are also exposed to photons and charged particles that can both drive chemical reactions and promote desorption of molecules, providing an important link between the solid state reservoir of molecules and the gas phase. While several studies have considered UV photon driven desorption mechanisms, the UV component of the interstellar radiation field is strongly attenuated within dense clouds, with the internal cloud field being dominated by IR photons. We have used the FELIX IR Free Electron Laser (FEL) FEL-2 to irradiate a few monolayer film of CO deposited on the top of amorphous solid water (ASW) and compared the CO desorption yields to those obtained for a pure CO film. Infrared spectroscopy, combined with mass spectrometric detection of desorbing CO molecules, reveals that excitation of vibrational modes in the underlying ASW leads to significant CO desorption. This is in contrast to direct excitation of the stretching mode of CO which results in only inefficient desorption. The desorption efficiencies we derive indicate that energy transfer within ices on interstellar grains might provide an important route to IR photon-induced desorption of volatile species, such as CO.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 6","pages":"1607–1621 1607–1621"},"PeriodicalIF":2.9,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144312446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dual-Domain Regulation of Dissolved Organic Matter Release in Soil: The Role of pH and Calcium","authors":"Hui Gao,&nbsp;Liping Weng*,&nbsp;Rob N. J. Comans and Gerwin F. Koopmans,&nbsp;","doi":"10.1021/acsearthspacechem.4c0037710.1021/acsearthspacechem.4c00377","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00377https://doi.org/10.1021/acsearthspacechem.4c00377","url":null,"abstract":"<p >Dissolved organic matter (DOM), being the most reactive soil organic matter (SOM) fraction, affects key biogeochemical processes in soil like nutrient cycling, pollutant transport, and organic carbon sequestration. Quantitative understanding of physical-chemical processes regulating the release of DOM in response to variation in factors such as pH and Ca concentration is still lacking. Here, we conducted batch experiments and employed the Natural Organic Matter-Charge Distribution (NOM-CD) model and the Non-Ideal Consistent Competitive Adsorption-Donnan (NICA-Donnan) model to investigate the physical-chemical processes controlling DOM release in seven agricultural topsoils under varying pH (3–9) and Ca concentration (0–10 mM). The DOM fractionation results showed that while hydrophilic acid (Hy), fulvic acid (FA), and humic acid (HA) concentrations increased with pH, their contribution to total DOM differed: Hy and HA dominated at respectively low pH (∼4–6) and high pH (∼8–9), whereas FA peaked at near-neutral pH (∼6.5–7). Our NOM-CD model calculations revealed that changes in the DOM concentration at low pH (pH &lt; ∼5–6.5) were mainly due to OM desorption from soil minerals. Changes in the DOM concentration at high pH (pH &gt; ∼5–6.5) were predominantly controlled by OM dissolution, as demonstrated by the relation between the DOM concentration and Donnan potential (φ_D) of DOM calculated with the NICA-Donnan model. Based on these findings, we propose a conceptual Dual-Domain Desorption Dissolution model in which the relative importance of these two controlling mechanisms is quantitatively assessed for the first time. These insights will be helpful to better quantify soil management effects on the stability and functioning of SOM.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 6","pages":"1377–1391 1377–1391"},"PeriodicalIF":2.9,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00377","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144312443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Noble Gases in Archean Barites: Precise Determination of the Isotopic Fractionation of Atmospheric Xenon 3.48 Ga Ago.","authors":"Guillaume Avice, Helge Mißbach-Karmrodt, Félix Vayrac, Joachim Reitner","doi":"10.1021/acsearthspacechem.4c00356","DOIUrl":"10.1021/acsearthspacechem.4c00356","url":null,"abstract":"<p><p>Following the evolution of the composition of the atmosphere informs on the entire geological evolution of our planet. The discovery that Archean atmospheric xenon was isotopically fractionated compared to modern atmospheric xenon paved the way for using this noble gas as a tracer of hydrogen escape on the primitive Earth. The curve of the evolution of the isotopic composition of atmospheric xenon remains, however, poorly defined. Recent studies proposed that the evolution was discontinuous with brief episodes of escape and fractionation of xenon separated by up to several 100 Ma long pauses. Similarly, some major unknowns remain regarding the progressive depletion of xenon in the atmosphere due to the proposed escape mechanism. In this study, we report the noble gas elemental ratios and isotopic compositions of noble gases released from a ca. 3.48 Ga old barite sample from the Dresser Formation (North Pole, Australia) by stepwise crushing in high vacuum. All samples released xenon enriched in light isotopes relative to heavy isotopes compared to modern atmospheric xenon but with various degrees of isotopic fractionation. Krypton is enriched in heavy isotopes relative to light isotopes in some crushed samples. After correction for Kr and Xe loss, results show that 3.48 Ga ago atmospheric xenon was fractionated by -19.1 ± 1.8‰ per atomic mass unit (u^-1). This value is more negative than that reported previously for 3.3 Ga old atmospheric xenon. A new curve for the evolution of the isotopic composition of atmospheric xenon is proposed. Xenon is also enriched relative to Kr in the gas released from the measured samples. While this is consistent with the scenario of a progressive selective escape of xenon from the Archean atmosphere, the exact abundance of Xe in the paleoatmosphere remains elusive.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 6","pages":"1367-1376"},"PeriodicalIF":2.9,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12183778/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144482515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Secondary Organic Aerosol Formation in the Tropical Coastal Atmosphere: Impact of Land- and Sea-Breeze Circulations","authors":"Suresh Kumar Reddy Boreddy*,&nbsp;Parvathy Anand,&nbsp;Dhananjay Kumar,&nbsp;Prashant Hegde and S. Suresh Babu,&nbsp;","doi":"10.1021/acsearthspacechem.5c0002810.1021/acsearthspacechem.5c00028","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.5c00028https://doi.org/10.1021/acsearthspacechem.5c00028","url":null,"abstract":"<p >The present study investigates secondary organic aerosol (SOA) formation in the tropical coastal atmosphere (Thumba: 8.5° N, 76.9° E, ∼3 m a.s.l.) in India during sea-breeze (SB) and land-breeze (LB) circulations by analyzing water-soluble organic compounds using gas chromatography (GC). The molecular distribution of organic compounds is characterized by a predominance of oxalic acid (C₂) during both circulations, with higher abundance during LB. While phthalic (Ph; an oxidation product of aromatics) and azelaic (C₉; an oxidation product of unsaturated fatty acids) acids are the next most abundant compounds during SB, terephthalic acid (tPh; a tracer of plastic-burning) is the second most dominant compound during LB. As markers of photochemical activity, the ratios of fumaric-to-maleic (F/M) and malonic-to-succinic (C₃/C₄) acids are doubled during SB. In contrast, C₂/Σ(C₂ – C₁₀) and water-soluble organic carbon (WSOC)/organic carbon (OC) ratios are higher during LB, suggesting secondary oxidation in an aqueous medium. The ISORROPIA II model’s results show that, consistent with relative humidity levels, aerosol-liquid water content (ALWC) in LB is 7 times larger than in SB. The 18-fold rise in the tPh/C₉ ratio during LB suggests a significant quantity of organics originated from plastic burning. Based on diagnostic mass ratios of organic and inorganic tracer compounds and their relationships, the present study emphasizes that SOA formation in the coastal atmosphere is likely caused by photochemical processes of marine-derived-organic precursors, such as unsaturated fatty acids and hydrolysis of phthalates, and related biogenic precursors during SB. However, the aqueous-phase formation of SOA relates to human-induced pollutants, including plastic burning dominant during LB. The impact of inorganics on daytime photooxidation of organic acids is also discussed.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 6","pages":"1566–1579 1566–1579"},"PeriodicalIF":2.9,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144312441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Noble Gases in Archean Barites: Precise Determination of the Isotopic Fractionation of Atmospheric Xenon 3.48 Ga Ago","authors":"Guillaume Avice*,&nbsp;Helge Mißbach-Karmrodt,&nbsp;Félix Vayrac and Joachim Reitner,&nbsp;","doi":"10.1021/acsearthspacechem.4c0035610.1021/acsearthspacechem.4c00356","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00356https://doi.org/10.1021/acsearthspacechem.4c00356","url":null,"abstract":"<p >Following the evolution of the composition of the atmosphere informs on the entire geological evolution of our planet. The discovery that Archean atmospheric xenon was isotopically fractionated compared to modern atmospheric xenon paved the way for using this noble gas as a tracer of hydrogen escape on the primitive Earth. The curve of the evolution of the isotopic composition of atmospheric xenon remains, however, poorly defined. Recent studies proposed that the evolution was discontinuous with brief episodes of escape and fractionation of xenon separated by up to several 100 Ma long pauses. Similarly, some major unknowns remain regarding the progressive depletion of xenon in the atmosphere due to the proposed escape mechanism. In this study, we report the noble gas elemental ratios and isotopic compositions of noble gases released from a ca. 3.48 Ga old barite sample from the Dresser Formation (North Pole, Australia) by stepwise crushing in high vacuum. All samples released xenon enriched in light isotopes relative to heavy isotopes compared to modern atmospheric xenon but with various degrees of isotopic fractionation. Krypton is enriched in heavy isotopes relative to light isotopes in some crushed samples. After correction for Kr and Xe loss, results show that 3.48 Ga ago atmospheric xenon was fractionated by −19.1 ± 1.8‰ per atomic mass unit (u^–1). This value is more negative than that reported previously for 3.3 Ga old atmospheric xenon. A new curve for the evolution of the isotopic composition of atmospheric xenon is proposed. Xenon is also enriched relative to Kr in the gas released from the measured samples. While this is consistent with the scenario of a progressive selective escape of xenon from the Archean atmosphere, the exact abundance of Xe in the paleoatmosphere remains elusive.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 6","pages":"1367–1376 1367–1376"},"PeriodicalIF":2.9,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00356","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144312442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Online Speciation of Glyoxal Multiphase Reactions on Deliquesced Ammonium Sulfate Particles","authors":"Nicolas Brun*,&nbsp;Anil Kumar Mandariya,&nbsp;Junteng Wu,&nbsp;Francesco Battaglia,&nbsp;Jian Xu,&nbsp;Manon Rocco,&nbsp;Laurent Poulain,&nbsp;Mathieu Cazaunau,&nbsp;Antonin Berge,&nbsp;Edouard Pangui,&nbsp;Brice Temime-Roussel,&nbsp;Bénédicte Picquet-Varrault,&nbsp;Jean-Louis Clément,&nbsp;Aline Gratien,&nbsp;Paola Formenti,&nbsp;Liang Wen,&nbsp;Thomas Schaefer,&nbsp;Andreas Tilgner,&nbsp;Hartmut Herrmann,&nbsp;Jean-François Doussin and Anne Monod*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0036910.1021/acsearthspacechem.4c00369","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00369https://doi.org/10.1021/acsearthspacechem.4c00369","url":null,"abstract":"<p >The reaction between glyoxal and ammonia in bulk Ammonium Sulfate (AS) aqueous solutions is known to be slow under acidic conditions, limiting its atmospheric relevance in wet acidic aerosol conditions. However, previous chamber experiments observed the formation of chromophores during the reactive uptake of gaseous glyoxal on ammonium sulfate particles within minutes. The mechanisms remained unresolved due to the lack of organic speciation and the Relative Humidity (RH) did not allow the seed particles to deliquesce. This study presents chemical speciation of the gas and the particle phases during the uptake of gaseous glyoxal on deliquesced AS seed particles (RH ≥ 80 ± 3%) in the CESAM simulation chamber. The chemical speciation of the particles was performed using AMS measurements complemented by a CHARON-PTR-ToF-MS. The influence of H₂O₂ addition, seed acidity and UV–vis photolysis was explored. Fast reactive uptake of gaseous glyoxal on AS particles was consistently observed in all experiments. The combined measurements from the two mass spectrometers enabled source apportionment analysis through positive matrix factorization of the AMS data and led to the identification and quantification of three dominant processes: (i) glyoxal hydration, (ii) fast dark aging of glyoxal, including the formation of brown carbon and (iii) photochemical aging. The CHARON-PTR-ToF-MS allowed the identification of individual products, such as oxazole and imidazole-2-carboxaldehyde, appearing within minutes during the chamber experiments. A detailed mechanism of glyoxal uptake was proposed, highlighting significant differences in kinetics and dominant reaction pathways compared to the glyoxal reactivity in the bulk aqueous phase.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 6","pages":"1350–1366 1350–1366"},"PeriodicalIF":2.9,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144312419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}