ACS Earth and Space Chemistry最新文献

{"title":"Theoretical and In Situ FTIR Studies of the Atmospheric Sink of Methyl Dichloroacetate by •OH Radicals and Cl• Atoms: Kinetics, Product Distribution, and Mechanism","authors":"Vianni G. Straccia C,&nbsp;Alejandro L. Cardona,&nbsp;María B. Blanco,&nbsp;Oscar N. Ventura* and Mariano Teruel*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0026410.1021/acsearthspacechem.4c00264","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00264https://doi.org/10.1021/acsearthspacechem.4c00264","url":null,"abstract":"<p >The atmospheric degradation of methyl dichloroacetate can be initiated by ^•OH and Cl^• radicals through H atom abstraction from the alkyl groups (Cl₂HC– or –CH₃) of the chloroester. Product yields for the gas-phase reaction with ^•OH were determined experimentally in a 480 L Pyrex glass atmospheric-simulation reactor coupled to an in situ Fourier transform infrared (FTIR) spectrometer. In addition to those results, we present in this paper a complete degradation mechanism based on thermodynamic data obtained by identifying all critical points on the potential-energy surface for these reactions, employing density functional calculations with the M06-2X and MN15 hybrid exchange–correlation functionals and the aug-cc-pVTZ basis sets. A conformational search for reactants and transition states was performed. The energies of these conformers were later corrected at the CCSD(T,Full)-F12/complete basis set level by using the SVECV-f12 composite method. The corrected energies were then used to obtain the theoretical rate coefficients in a multiconformer approach. The global rate coefficient calculated for the reaction of methyl dichloroacetate with ^•Cl atoms is (7.34 × 10^–12 cm³ molecule^–1·s^–1), and the global rate coefficient calculated for the reaction with ^•OH radicals is (1.07 × 10^–12 cm³ molecule^–1·s^–1). The identified products and their respective yield percentages for the reaction of MDCA with ^•OH were Cl₂CHCOOH (44 ± 3%), COCl₂ (43 ± 3%), and CO (41 ± 6%). The analysis of the mechanism suggests that formation of P1 (Cl₂CO, phosgene) occurs mainly by abstraction from the Cl₂HC– group since the formation of P4 (Cl₂CHC(O)OH, dichloroacetic acid) and P5 (CO, carbon monoxide) is more favorable in the path for abstraction from the –OCH₃ group. The multiconformer calculated rate constant values were compared with the values obtained employing only the low-lying TSs and with our own previous experimental studies. Branching ratios for the reaction with ^•Cl were compared to the experimental product yields.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"8 12","pages":"2599–2610 2599–2610"},"PeriodicalIF":2.9,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142842483","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":"Iodine Activation from Iodate Reduction in Aqueous Films via Photocatalyzed and Dark Reactions","authors":"Mago Reza,&nbsp;Lucia Iezzi,&nbsp;Henning Finkenzeller,&nbsp;Antoine Roose,&nbsp;Markus Ammann and Rainer Volkamer*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0022410.1021/acsearthspacechem.4c00224","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00224https://doi.org/10.1021/acsearthspacechem.4c00224","url":null,"abstract":"<p >Iodine in the atmosphere destroys ozone and can nucleate particles by formation of iodic acid, HIO₃. Recent field observations suggest iodate recycles from particles sustaining significant gas-phase IO radical concentrations (0.06 pptv) in aged stratospheric air, and in elevated dust plumes. However, laboratory evidence for iodine activation from aerosols is currently missing. Here, a series of coated-wall flow tube (CWFT) experiments test for iodine release from thin aqueous films containing iodate. Photocatalyzed reactions were studied using iron(III) citrate (Fe–Cit), Arizona Test Dust (ATD), and Fe₂O₃, along with the dark reaction of iodate with H₂O₂ at 90% RH and 293 K. Fresh films were separately irradiated with visible and UV-A light, and the efficient release of molecular iodine, I₂, was observed from all irradiated films containing photocatalysts. For films with Fe–Cit, visible light reduced larger amounts of iodate than UV-A light, activating ∼40% of iodate as I₂. The formation of oxygenated volatile organic compounds (OVOC) and iodinated OVOC was also observed. Dark exposure of films to H₂O₂ led to I₂ release in smaller amounts than suggested by Bray–Liebhafsky kinetics, consistent with H₂O₂ salting-out in the films, or possibly other reasons. Photochemical activation is enhanced by dust proxies in the film, and by aging the film with H₂O₂ in the dark prior to irradiation. These findings help explain recent field observations of elevated IO radical concentrations in lofted dust layers, and warrant the inclusion of photocatalyzed iodate reduction in atmospheric models.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"8 12","pages":"2495–2508 2495–2508"},"PeriodicalIF":2.9,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00224","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142842099","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":"Iodine Activation from Iodate Reduction in Aqueous Films via Photocatalyzed and Dark Reactions.","authors":"Mago Reza, Lucia Iezzi, Henning Finkenzeller, Antoine Roose, Markus Ammann, Rainer Volkamer","doi":"10.1021/acsearthspacechem.4c00224","DOIUrl":"10.1021/acsearthspacechem.4c00224","url":null,"abstract":"<p><p>Iodine in the atmosphere destroys ozone and can nucleate particles by formation of iodic acid, HIO₃. Recent field observations suggest iodate recycles from particles sustaining significant gas-phase IO radical concentrations (0.06 pptv) in aged stratospheric air, and in elevated dust plumes. However, laboratory evidence for iodine activation from aerosols is currently missing. Here, a series of coated-wall flow tube (CWFT) experiments test for iodine release from thin aqueous films containing iodate. Photocatalyzed reactions were studied using iron(III) citrate (Fe-Cit), Arizona Test Dust (ATD), and Fe₂O₃, along with the dark reaction of iodate with H₂O₂ at 90% RH and 293 K. Fresh films were separately irradiated with visible and UV-A light, and the efficient release of molecular iodine, I₂, was observed from all irradiated films containing photocatalysts. For films with Fe-Cit, visible light reduced larger amounts of iodate than UV-A light, activating ∼40% of iodate as I₂. The formation of oxygenated volatile organic compounds (OVOC) and iodinated OVOC was also observed. Dark exposure of films to H₂O₂ led to I₂ release in smaller amounts than suggested by Bray-Liebhafsky kinetics, consistent with H₂O₂ salting-out in the films, or possibly other reasons. Photochemical activation is enhanced by dust proxies in the film, and by aging the film with H₂O₂ in the dark prior to irradiation. These findings help explain recent field observations of elevated IO radical concentrations in lofted dust layers, and warrant the inclusion of photocatalyzed iodate reduction in atmospheric models.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"8 12","pages":"2495-2508"},"PeriodicalIF":2.9,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11664648/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142884780","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":"Solar Wind Irradiation of Methane and Methane–Water Ices: A Molecular Dynamics Approach","authors":"Alessandra Ricca*,&nbsp; and ,&nbsp;Justin B. Haskins,&nbsp;","doi":"10.1021/acsearthspacechem.4c0022510.1021/acsearthspacechem.4c00225","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00225https://doi.org/10.1021/acsearthspacechem.4c00225","url":null,"abstract":"<p >Molecular dynamics simulations were performed to characterize reaction products, resulting from solar wind irradiation, namely, H⁺, of methane and methane–water ices. In our approach, we used seven 0.829 keV H⁺ (total energy of 5.8 keV), with a velocity of 400 km/s, to hit the icy surface simultaneously, and we repeated this process multiple times to simulate continuous irradiation while quenching the ice to 15 K after each irradiation to prevent excessive heating and sublimation. Our simulations produced complex organic molecules previously obtained in laboratory experiments. For methane ice, molecules containing two carbons were predominant, with ethane and ethyl radicals being the most abundant, followed by ethylene, vinyl radical, and acetylene. Hydrocarbons containing three carbons (e.g., propane, propene, and propyl) were minor products, and only a few molecules containing four carbon atoms (e.g., iso-butene, 1-methylpropylidene, and 2-buten-2-yl) formed. Products that can be formed from the reaction of 1–3 impact fragmentation events, ethane, ethyl radical, and ethylene, monotonically increased over time, while products of 3 or more impact fragmentation events, vinyl, propane, and acetylene, formed over longer time scales. The number of methane complexes decreased over time. For a methane/water (1:1) ice mixture, most of the products consisted of methyl–water complexes, and their number increased with time. All the other oxygenated and nonoxygenated products formed in small amounts due to the water solvation of radicals. For a methane/water (4:1) ice mixture, the methyl–water complexes constituted 45% of the total products, with oxygenated and nonoxygenated products being formed in almost equal amounts. For methane–water ices, the proportions of alkanes, alkenes, and alkynes were very similar to those of pure methane. Dimethyl ether and ethanol formed for both 1:1 and 4:1 methane–water ices.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"8 12","pages":"2509–2521 2509–2521"},"PeriodicalIF":2.9,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00225","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142842643","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":"Solar Wind Irradiation of Methane and Methane-Water Ices: A Molecular Dynamics Approach.","authors":"Alessandra Ricca, Justin B Haskins","doi":"10.1021/acsearthspacechem.4c00225","DOIUrl":"10.1021/acsearthspacechem.4c00225","url":null,"abstract":"<p><p>Molecular dynamics simulations were performed to characterize reaction products, resulting from solar wind irradiation, namely, H⁺, of methane and methane-water ices. In our approach, we used seven 0.829 keV H⁺ (total energy of 5.8 keV), with a velocity of 400 km/s, to hit the icy surface simultaneously, and we repeated this process multiple times to simulate continuous irradiation while quenching the ice to 15 K after each irradiation to prevent excessive heating and sublimation. Our simulations produced complex organic molecules previously obtained in laboratory experiments. For methane ice, molecules containing two carbons were predominant, with ethane and ethyl radicals being the most abundant, followed by ethylene, vinyl radical, and acetylene. Hydrocarbons containing three carbons (e.g., propane, propene, and propyl) were minor products, and only a few molecules containing four carbon atoms (e.g., iso-butene, 1-methylpropylidene, and 2-buten-2-yl) formed. Products that can be formed from the reaction of 1-3 impact fragmentation events, ethane, ethyl radical, and ethylene, monotonically increased over time, while products of 3 or more impact fragmentation events, vinyl, propane, and acetylene, formed over longer time scales. The number of methane complexes decreased over time. For a methane/water (1:1) ice mixture, most of the products consisted of methyl-water complexes, and their number increased with time. All the other oxygenated and nonoxygenated products formed in small amounts due to the water solvation of radicals. For a methane/water (4:1) ice mixture, the methyl-water complexes constituted 45% of the total products, with oxygenated and nonoxygenated products being formed in almost equal amounts. For methane-water ices, the proportions of alkanes, alkenes, and alkynes were very similar to those of pure methane. Dimethyl ether and ethanol formed for both 1:1 and 4:1 methane-water ices.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"8 12","pages":"2509-2521"},"PeriodicalIF":2.9,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11664651/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142884795","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":"Subsequent Reaction of CH2(1A) with N2 Molecule as a Potentially Important Source of HCN in the Atmosphere of Titan: Studies by Quantum-Chemical and Statistical Rate Theories","authors":"Vahid Saheb*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0021310.1021/acsearthspacechem.4c00213","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00213https://doi.org/10.1021/acsearthspacechem.4c00213","url":null,"abstract":"<p >In this theoretical research, the possibility of the formation of the significant prebiotic hydrogen cyanide molecule and other important species in Titan’s atmosphere through the subsequent reactions of singlet methylene species, ¹CH₂, with the N₂ molecule is investigated. The stationary points geometries and energies of species involved in the studied reaction are calculated by high-level quantum-chemical methods such as W1RO and CCSDT(Q) methods. Next, the rate coefficients for the formation of products are computed by sophisticated statistical rate theories including RRKM and VRC-TST. It is inferred from a previous theoretical study that CH₂NN is produced predominantly from the reaction of ¹CH₂ with N₂ in the atmosphere of Titan [<contrib-group><span>Xu, S.</span>; <span>Lin, M. C.</span></contrib-group> <cite><i>J. Phys. Chem. A</i></cite> <span>2010</span>, <em>114</em>, 5195–5204]. The reactive CH₂NN molecules react with other atmospheric species like ¹CH₂ to produce new species. According to the present study, ¹CH₂ species add to CH₂NN molecules through relatively fast barrierless processes to produce some chemically activated intermediates. These intermediates rapidly decompose to yield 2 NCH₂, HCN + CH₂NH, and C₂H₄ + N₂ products. The calculated data reveal that HCN and C₂H₄ are efficiently produced from the subsequent reaction of ¹CH₂ with N₂ molecules in the atmosphere of Titan. The following rate constant expressions are suggested for the computed rate coefficients for the production of 2 NCH₂ (<i>k</i>₁), HCN + CH₂NH (<i>k</i>₂), and C₂H₄ + N₂ (<i>k</i>₃) from ¹CH₂ + CH₂NN reaction over the temperature range 200–700 K: <i>k</i>₁ = 5.48 × 10^–10 (T/300)^0.258 exp (255/T) <i>k</i>₂ = 1.15 × 10^–14 (T/300)^0.901 exp (355/T) <i>k</i>₃ = 3.10 × 10^–10 (T/300)^−0.428 exp (130/T).</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"8 12","pages":"2474–2482 2474–2482"},"PeriodicalIF":2.9,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142850485","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":"Coupling of Li-Fe: Li Isotope Fractionation during Sorption onto Fe-Oxides.","authors":"Xu Yvon Zhang, David J Wilson, Maartje F Hamers, Philip A E Pogge von Strandmann, Josephina J P A Mulders, Oliver Plümper, Helen E King","doi":"10.1021/acsearthspacechem.4c00205","DOIUrl":"10.1021/acsearthspacechem.4c00205","url":null,"abstract":"<p><p>Chemical weathering processes play a key role in regulating the global climate over geological time scales. Lithium (Li) isotope compositions have proven to be a robust proxy for tracing weathering processes that produce secondary minerals, such as clays and oxides, with a focus often placed on Li adsorption to, or incorporation into, clay minerals. In addition, the interaction between Li and Fe-oxides has long been assumed and discussed based on field observations, but experimental constraints on this process are lacking. Here, we investigated the geochemical behavior of Li during its sorption onto individual Fe-oxides, including goethite, hematite, wüstite, and magnetite. With a point of zero charge at ∼7.7, poorly crystallized goethite nanoparticles take up ∼20% of dissolved Li over a pH range from ∼4 to ∼10, rising to ∼90% at pH ∼12. In contrast, the sorption of dissolved Li is insignificant for well-crystallized Fe-oxides (hematite, wüstite, magnetite, and goethite). This Li uptake by poorly crystallized goethite is likely attributed to dissolution and reprecipitation reactions at poorly crystalline goethite surfaces. The goethite particles preferentially take up light ⁶Li isotopes, resulting in an isotope fractionation of Δ⁷Li_oxide-fluid ∼ -16.7 to -20.1‰. Overall, our study provides valuable data to better understand the processes occurring in highly weathered soil and sediment profiles that are rich in Fe-oxides, such as laterites. This research also emphasizes the significance of chemistry at mineral surfaces during mineral-water interactions and illuminates the mechanisms of large-scale Li extraction for future applications.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 1","pages":"49-63"},"PeriodicalIF":2.9,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11744929/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142996037","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":"Reaction of the Acetyl Peroxy Radical and OH Radical as a Source of Acetic Acid in the Atmosphere","authors":"Hanhao Chen,&nbsp;Sainan Wang and Liming Wang*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0021110.1021/acsearthspacechem.4c00211","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00211https://doi.org/10.1021/acsearthspacechem.4c00211","url":null,"abstract":"<p >The potential role of the reaction between the acetyl peroxy radicals (CH₃C(O)O₂) and the hydroxyl radical in the atmosphere was investigated. Theoretical calculations show that this reaction would form acetic acid (AAc) and ¹O₂ almost exclusively. The reaction proceeds by formation of a trioxide compound as CH₃C(O)OOOH, in which rapid intramolecular hydrogen atom transfer followed by decomposition to AAc and ¹O₂ was found, while decomposition of the trioxide to CH₃CO₂ + HO₂ is negligible. With the relatively fast reaction between CH₃C(O)O₂ and OH with an estimated rate coefficient of 1.8 × 10^–10 cm³ molecule^–1 s^–1, the reaction might be a significant secondary source of AAc in the troposphere. A global atmospheric simulation using GEOS-Chem found that the title reaction results in an average increase of the mixing ratios of AAc by ∼33% (about 6.4 pptv for increase) and a net formation of about 8.0 Tg/yr AAc. Reactions between other RC(O)O₂ and OH may also contribute significantly to the formation of RC(O)OH. The atmospheric chemistry model may need to include the title reaction.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"8 12","pages":"2522–2531 2522–2531"},"PeriodicalIF":2.9,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142850930","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":"Cerium Stable Isotopic Composition of Non-Carbonaceous Chondrites","authors":"Hamed Pourkhorsandi*,&nbsp;Vinciane Debaille,&nbsp;Rosalind M. G. Armytage and Jeroen de Jong,&nbsp;","doi":"10.1021/acsearthspacechem.4c0020610.1021/acsearthspacechem.4c00206","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00206https://doi.org/10.1021/acsearthspacechem.4c00206","url":null,"abstract":"<p >The elemental and isotopic compositions of the rare earth elements (REE) reveal critical information about the physicochemical dynamics of the solar nebula. Cerium (Ce) is the most abundant REE in the Solar System. It has recently received renewed attention due to the decay of ¹³⁸La to ¹³⁸Ce, but its stable isotopic composition still requires a better comprehension. Here, we report the Ce stable isotopic compositions (¹⁴²Ce/¹⁴⁰Ce, expressed as δ¹⁴²Ce) of 18 well-characterized non-carbonaceous chondrites including 11 enstatite chondrites (EH and EL) and 6 ordinary chondrites (H, L, and LL) collected from the Antarctic, and one rumuruti chondrite collected from the Sahara Desert. The analyzed chondrites show relatively homogeneous δ¹⁴²Ce compositions within 0.01 ± 0.30‰ (<i>n</i> = 18; 2SD). This observation indicates lack of any resolvable effects of nebular physicochemical variables, such as differences in <i>f</i>O₂ and chemistry of the accretion regions, in different chondrites. A homogeneous isotopic composition among our analyzed samples also indicates a lack of evidence for any effects of thermal metamorphism on the δ¹⁴²Ce composition of chondrites. In addition, considering a wide range of weathering degrees in our samples, we do not observe any modifications resulting from weathering. Considering the refractory and lithophile behavior of Ce and the limited variation of δ¹⁴²Ce between various non-carbonaceous chondrite groups, their average will not be significantly different from the Ce isotopic composition of the Bulk Silicate Earth (BSE). We discuss the cosmochemical implications of our data and suggest extending the database of the stable isotopic composition of Ce and other REE in different types of chondrites and chondritic components.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"8 12","pages":"2452–2462 2452–2462"},"PeriodicalIF":2.9,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142843732","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":"Coupling of Li–Fe: Li Isotope Fractionation during Sorption onto Fe-Oxides","authors":"Xu Yvon Zhang*,&nbsp;David J. Wilson,&nbsp;Maartje F. Hamers,&nbsp;Philip A. E. Pogge von Strandmann,&nbsp;Josephina J. P. A. Mulders,&nbsp;Oliver Plümper and Helen E. King,&nbsp;","doi":"10.1021/acsearthspacechem.4c0020510.1021/acsearthspacechem.4c00205","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00205https://doi.org/10.1021/acsearthspacechem.4c00205","url":null,"abstract":"<p >Chemical weathering processes play a key role in regulating the global climate over geological time scales. Lithium (Li) isotope compositions have proven to be a robust proxy for tracing weathering processes that produce secondary minerals, such as clays and oxides, with a focus often placed on Li adsorption to, or incorporation into, clay minerals. In addition, the interaction between Li and Fe-oxides has long been assumed and discussed based on field observations, but experimental constraints on this process are lacking. Here, we investigated the geochemical behavior of Li during its sorption onto individual Fe-oxides, including goethite, hematite, wüstite, and magnetite. With a point of zero charge at ∼7.7, poorly crystallized goethite nanoparticles take up ∼20% of dissolved Li over a pH range from ∼4 to ∼10, rising to ∼90% at pH ∼12. In contrast, the sorption of dissolved Li is insignificant for well-crystallized Fe-oxides (hematite, wüstite, magnetite, and goethite). This Li uptake by poorly crystallized goethite is likely attributed to dissolution and reprecipitation reactions at poorly crystalline goethite surfaces. The goethite particles preferentially take up light ⁶Li isotopes, resulting in an isotope fractionation of Δ⁷Li_oxide-fluid ∼ −16.7 to −20.1‰. Overall, our study provides valuable data to better understand the processes occurring in highly weathered soil and sediment profiles that are rich in Fe-oxides, such as laterites. This research also emphasizes the significance of chemistry at mineral surfaces during mineral–water interactions and illuminates the mechanisms of large-scale Li extraction for future applications.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 1","pages":"49–63 49–63"},"PeriodicalIF":2.9,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00205","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143091597","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}