ACS Earth and Space Chemistry最新文献

{"title":"Hg Accumulation by Single-Cell Sulfate-Reducing Bacteria Methylating Mercury","authors":"Antoine Le Gohalen,&nbsp;, ,&nbsp;Marisol Goñi-Urriza,&nbsp;, ,&nbsp;Sophie Barrouilhet,&nbsp;, ,&nbsp;Mathilde Monperrus,&nbsp;, ,&nbsp;Mónica Fernández-Monreal,&nbsp;, ,&nbsp;Noémie Pied,&nbsp;, ,&nbsp;Nestor J. Zaluzec,&nbsp;, ,&nbsp;Murielle Salome,&nbsp;, ,&nbsp;Peter Cloetens,&nbsp;, ,&nbsp;Sylvain Bohic,&nbsp;, ,&nbsp;Yanqi Luo,&nbsp;, ,&nbsp;Si Chen,&nbsp;, and ,&nbsp;Marie-Pierre Isaure*,&nbsp;","doi":"10.1021/acsearthspacechem.5c00368","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.5c00368","url":null,"abstract":"<p >Methylmercury (MeHg) is a potent neurotoxin that poses risks to ecosystems and human health. MeHg is produced by microbes following saturating-like kinetics. We hypothesize that this saturation reflects a limited intracellular mercury (Hg) accumulation. In this study, we investigated Hg accumulation in <i>Pseudodesulfovibrio hydrargyri</i> BerOc1, a sulfate-reducing model strain able to methylate Hg. Cells were incubated with 0.5 and 2 μM of mercury (HgCl₂), and mercury localization was studied using synchrotron-based nano-X-ray fluorescence and high-resolution analytical electron microscopy. For both concentrations, Hg was detected in the bacterial cytosol, in addition to extracellular (Hg, S)-containing nanoparticles. Intracellular Hg levels were slightly higher at 2 μM than at 0.5 μM (1.61 vs 1.40 pg.mm^–2), suggesting a regulated accumulation. However, the population exhibited heterogeneity in Hg accumulation, particularly at the highest Hg exposure, with some cells being Hg hyperaccumulators. Correlative imaging between Hg localization and cell viability revealed that these hyperaccumulating cells were non-active. Our results suggest that active cells regulate Hg accumulation. From an analytical perspective, a minor subpopulation of hyperaccumulating cells can bias bulk measurements and should be considered in interpreting Hg accumulation in microorganisms. Environmentally, these cells can impact Hg cycling by acting as a metal sink.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 5","pages":"1228–1238"},"PeriodicalIF":2.9,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147968245","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":"Road-Salt Aerosol Reacts More Efficiently with N2O5 than Sea Spray Aerosol to Produce ClNO2","authors":"James A. Christie,&nbsp;, ,&nbsp;Kerri A. Pratt,&nbsp;, and ,&nbsp;Cassandra J. Gaston*,&nbsp;","doi":"10.1021/acsearthspacechem.6c00042","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.6c00042","url":null,"abstract":"<p >Atmospheric chemical models underpredict the inland production of nitryl chloride (ClNO₂), a precursor to atomic chlorine (Cl·), due to a lack of both a complete inventory of aerosol-chloride sources and their reactive uptake kinetics. One source not represented in atmospheric models is road salt, potentially driving underpredictions of Cl· in regions that apply them. We measured the soluble ion content, dinitrogen pentoxide reactive uptake coefficient (γN₂O₅), and ClNO₂ yield (φClNO₂) of several road-salt samples. To account for diverse deicing practices, we investigated several road-salt additives, including samples with sand abrasives and brines. γN₂O₅ for all samples ranged from 0.003 to 0.067, while φClNO₂ ranged from nondetectable to unity, with both parameters depending on soluble ion composition and relative humidity (RH). Under low RH conditions (&lt;40%), road salts without additives had low values of γN₂O₅ and φClNO₂, due to sodium chloride (NaCl) efflorescence, while samples with sand and/or brine additives, including beet juice extract, showed higher γN₂O₅ and variable φClNO₂. When RH was above 40%, all but one sample showed values of γN₂O₅ and φClNO₂ similar to NaCl, suggesting soluble chloride is driving N₂O₅-road-salt reactions at elevated RHs and can be predicted using current parametrizations. A comparison of N₂O₅-road-salt chemistry demonstrated that road salt reacts more efficiently than several known aerosol-chloride sources, including sea spray aerosol. We estimate that road salt can produce ClNO₂ approximately 7.5 times more efficiently than sea spray aerosol, highlighting the importance of including road salt as an efficient halogen source in atmospheric models.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 5","pages":"1418–1428"},"PeriodicalIF":2.9,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147968265","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":"Spatiotemporal Variations in Fossil vs Non-Fossil Source Contributions to Carbonaceous Aerosols across Diverse Indian Environments: An Assessment via Radiocarbon","authors":"M. Devaprasad,&nbsp;, ,&nbsp;Neeraj Rastogi*,&nbsp;, ,&nbsp;Konika Sharma,&nbsp;, ,&nbsp;Pradeep Attri,&nbsp;, ,&nbsp;Ranjan Kumar Mohanty,&nbsp;, ,&nbsp;S. Harithasree,&nbsp;, ,&nbsp;Atinderpal Singh,&nbsp;, ,&nbsp;Shweta Yadav,&nbsp;, ,&nbsp;Devleena Mani Tiwari,&nbsp;, ,&nbsp;Amzad Hussain Laskar,&nbsp;, ,&nbsp;Ankur Dabhi,&nbsp;, ,&nbsp;Ravi Bhushan,&nbsp;, ,&nbsp;Sanat Kumar Das,&nbsp;, and ,&nbsp;A. K. Sudheer,&nbsp;","doi":"10.1021/acsearthspacechem.6c00055","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.6c00055","url":null,"abstract":"<p >Carbonaceous aerosols (CAs) are a dominant component of particulate matter over South Asia, yet the relative contributions of fossil-fuel combustion and nonfossil sources remain poorly constrained across India’s diverse emission environments. Here, we present a comprehensive assessment of CA sources using dual-carbon isotopes (¹⁴C and ¹³C), complemented by chemical composition (OC, EC, and WSOC), and aerosol mass spectrometer (AMS)-derived oxidation indicators (<i>f</i>₄₃ and <i>f</i>₄₄). Aerosol samples were collected across eight geographically distinct locations spanning the Indo-Gangetic Plain (IGP), semiarid western India, southern India, the Himalayan foothills, and the Bay of Bengal during the postmonsoon, winter, spring, and summer seasons. Radiocarbon-derived nonfossil fractions of total carbon (<i>f</i>_{bio_TC}) ranged from 0.39 to 0.86 (mean = 0.71 ± 0.13), with the highest values observed during the postmonsoon paddy-residue-burning period over the IGP (up to 0.82 at Patiala), reflecting the overwhelming dominance of biomass-burning-derived carbon, and the lowest values during summer at Delhi (0.45) and Ahmedabad (0.49), indicating a clear seasonal shift toward fossil-fuel-dominated CAs. Stable carbon isotope signatures (δ¹³C), together with oxidation indicators (<i>f</i>₄₃ and <i>f</i>₄₄), reveal pronounced regional contrasts in aerosol aging and secondary processing, with aged, highly oxidized biomass-burning aerosols prevailing over northern and northeastern India during the postmonsoon and winter, and fresher primary fossil-fuel emissions dominating during summer and at southern and western sites. Comparison with MERRA-2 reanalysis reveals a systematic underestimation of TC concentrations across all sites and seasons (mean bias ∼−42%), most severe during the PRB period over the IGP and in winter over northeastern India, pointing to deficiencies in fire emission inventories and aerosol transport representation in current reanalysis products. These findings provide robust, observation-based constraints on the seasonal and regional evolution of CA sources across India, offering critical inputs for refining emission inventories, improving chemical transport model performance, and designing targeted mitigation strategies for reducing the air-quality and climate impacts of carbonaceous aerosols over South Asia.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 5","pages":"1439–1452"},"PeriodicalIF":2.9,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147968339","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":"Contrasting Fungal-Assisted Aggregation between Layered and Fibrous Clay Particles","authors":"Yingxi Chen,&nbsp;, ,&nbsp;Bihe Zhu,&nbsp;, ,&nbsp;Jingjing Qiu,&nbsp;, ,&nbsp;Yuekun Chen,&nbsp;, ,&nbsp;Zhenyu Chao,&nbsp;, ,&nbsp;Qi Shao,&nbsp;, ,&nbsp;Zhijun Wang,&nbsp;, ,&nbsp;Shihui Yan,&nbsp;, ,&nbsp;Shang Pan,&nbsp;, ,&nbsp;Kun He,&nbsp;, and ,&nbsp;Zhen Li*,&nbsp;","doi":"10.1021/acsearthspacechem.5c00348","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.5c00348","url":null,"abstract":"<p >Interactions between extracellular polymeric substances (EPS) and clay minerals promote the aggregation of mineral particles. The aggregation process is influenced by various crystal structures of clay minerals. In this study, we conducted a 30-day incubation by using <i>Rhodotorula mucilaginosa</i> (Rho, a fungus with a high ability to produce EPS) and two types of clay minerals, i.e., the layered montmorillonite (Mt) and the fibrous palygorskite (Pal). The D50 size of Mt consistently increased from 55.6 μm (Mt@CK) to 127.0 μm (Mt@30d). Meanwhile, evident yellow-red growth clusters gradually appeared after the addition of montmorillonite. This phenomenon is likely attributed to the promotion of fungal growth by the layered structure of montmorillonite. In contrast, after the addition of palygorskite, the D50 size of Pal slightly decreased from 50.6 μm (Pal@CK) to 33.9 μm (Pal@10d). This decrease was likely due to the sorption of relatively small fibrous palygorskite particles that restricted fungal nutrient intake. In addition, ATR-FTIR spectra confirmed the intense adsorption of EPS onto the montmorillonite particles. Evident shifts were clearly observed in the FTIR spectra of the Mt@20d and Mt@30d samples. Moreover, the intense symmetric COO^– stretching vibrations (1318 cm^–1) indicated that a polysaccharide–montmorillonite complex was formed. At the genetic level, the STE7 and STE11 genes (which facilitate EPS secretion) exhibited higher levels of upregulation in the treatment with the addition of montmorillonite than in that with palygorskite. These findings provide new insights into the roles of different clay minerals during the fungal-assisted aggregation process.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 5","pages":"1201–1209"},"PeriodicalIF":2.9,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147968236","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":"Manganese and Cobalt in Olivine-Group Silicates Offer Potential for Natural H2 Generation","authors":"Lauren N. Pincus,&nbsp;, ,&nbsp;Catherine A. Peters*,&nbsp;, ,&nbsp;Conghao Yi,&nbsp;, and ,&nbsp;Hamed M. Kermani,&nbsp;","doi":"10.1021/acsearthspacechem.5c00301","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.5c00301","url":null,"abstract":"<p >As demand for hydrogen (H₂) rises to achieve decarbonization and sustainable energy goals, the need to explore natural H₂ sources is pressing. The potential for geologic H₂ generation via serpentinization has focused on fayalite (Fe^II₂SiO₄) and other iron-rich ultramafic minerals, but there are compelling reasons to think beyond iron. Here, we consider tephroite (Mn^II₂SiO₄) and Co-olivine (Co^II₂SiO₄), olivine-group minerals that contain redox-active transition metals, manganese, and cobalt. We detail mineral alteration reactions with respect to productive and nonproductive pathways for H₂ generation and discuss relevant thermodynamic and kinetic factors. The ligand-stabilization energy of Mn^II is low, leading to tephroite having rapid dissolution kinetics. This suggests the potential for more rapid H₂ generation compared to fayalite in conditions where Mn^II oxidation is thermodynamically favored. H₂ generation is maximized when geochemical conditions such as temperature, pH, and silica activity promote precipitation of secondary minerals ((hydr)oxides and silicates) that stabilize the metals in their oxidized forms. Tephroite serpentinization can generate many Mn^III-stabilizing secondary minerals and minerals that stabilize Mn^II have a significant likelihood of dissolving and remobilizing the reduced metal, unlike the serpentinization products of iron-rich olivine. For Mn and Co, more research is needed to understand the mineral transformation sequences and conditions that maximize H₂ generation, from both pure end members as well as solid solutions, as well as to address data gaps that limit predictions from reactive transport simulators. Thinking beyond iron may lead to favorable prospects for siting geologic H₂ generation operations, as Mn and Co are less abundant than Fe but are geographically ubiquitous.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 5","pages":"1174–1184"},"PeriodicalIF":2.9,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acsearthspacechem.5c00301","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147968242","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":"Diurnal and Seasonal Variability of Gas–Particle Partitioning of Secondary Organic Aerosols in the Tropical Atmosphere","authors":"Suresh K. R. Boreddy*,&nbsp;, ,&nbsp;T. C. Ajith,&nbsp;, ,&nbsp;Sobhan Kumar Kompalli,&nbsp;, ,&nbsp;Prashant Hegde,&nbsp;, and ,&nbsp;S. Suresh Babu,&nbsp;","doi":"10.1021/acsearthspacechem.6c00003","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.6c00003","url":null,"abstract":"<p >Gas-particle partitioning is a critical process in the formation and development of secondary organic aerosols, yet its behavior in the atmosphere remains uncertain. The present study examines the diurnal and seasonal characteristics of gas-particle distribution of fine aerosols (PM₁; particulate matter less than 1 μm in aerodynamic diameter) at a tropical coastal station (Thumba; 8.5° N, 77° E, ∼4 m above sea level) in southern peninsular India. Simultaneous measurements of gases and aerosols were collected on a day and night basis using an in-house-developed two-stage low-volume air sampler from January to April 2022 (covering winter and premonsoon). Results show that the chemical composition was characterized by a high abundance of organic carbon (OC) in both phases. While sulfate (SO₄^2–) was found predominantly in the particle phase, nitrate (NO₃^–) and methanesulfonate (CH₃SO₃^–) are prevalent in the gas phase. Oxalate (C₂O₄^2–) was found in both the gas and particle phases. The gas-particle partitioning coefficient (<i>K</i>_<i>p</i>^<i>f</i>) of C₂O₄^2– was higher by 2 orders of magnitude compared to methanesulfonate (CH₃SO₃^–), indicating that C₂O₄^2– has a high tendency to partition into the particle phase. The <i>K</i>_<i>p</i>^<i>f</i>_OC was higher at night than during the day in both seasons. Furthermore, the average daytime values were three times higher in winter than in the premonsoon period. These findings indicate that the gas-particle partitioning mechanism is more prominent at lower air temperatures and higher relative humidity, especially during winter. This inference was further supported by a substantial linear (inverse) relationship between nighttime (daytime) relative humidity (temperature) and <i>K</i>_<i>p</i>^<i>f</i>_OC. A high abundance of gas-phase OC in premonsoon indicates significant volatilisation of particle OC at elevated temperatures.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 5","pages":"1310–1319"},"PeriodicalIF":2.9,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147968241","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":"Acenaphthene Derivatives as Signatures of C11H9+ Reactivity with Methylated Naphthalenes","authors":"Ana I. Lozano,&nbsp;, ,&nbsp;Anthony Bonnamy,&nbsp;, ,&nbsp;Aude Simon,&nbsp;, and ,&nbsp;Christine Joblin*,&nbsp;","doi":"10.1021/acsearthspacechem.5c00386","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.5c00386","url":null,"abstract":"<p >C₁₁H₉⁺ ion is the dominant fragment cation formed from methyl-naphthalene (MeNp) and dimethyl-naphthalene (diMeNp). Using the multiplex capabilities of PIRENEA, a setup dedicated to laboratory astrophysics, we studied the reactivity of the benzylium-like isomers of C₁₁H₉⁺ with diMeNp under isolated conditions relevant to radiative association. Two reaction products are observed, C₁₂H₁₁⁺ – also formed in the reaction with MeNp– and C₁₃H₁₃⁺, with branching ratios that depend on the specific diMeNp isomer. The reaction products were subsequently exposed to UV–visible irradiation to gain insight into their structures. The acenaphthylene radical cation, C₁₂H₈^•+, was identified as the most stable photofragment. We show that this experimental approach, supported by density functional theory calculations and molecular dynamics simulations, provides new constraints on the chemistry of benzylium-type species. We highlight the role that long-lived ion–molecule complexes can have in promoting C–C coupling and the formation of a pentagonal cycle. Moreover, the chemistry uncovered here highlights new pathways for the formation of pentagonal rings during PAH growth under low-pressure and cold conditions. In particular, it can lead to efficient formation of acenaphthylene-like species, recently detected in the TMC-1 cold cloud.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 5","pages":"1254–1266"},"PeriodicalIF":2.9,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147968277","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":"Modeling an SN2 Reaction Mechanism for Hydrolysis of Siloxane Linkages with Density Functional Theory under Basic Conditions and Implications for Dissolution of Quartz","authors":"Heath D. Watts,&nbsp; and ,&nbsp;James D. Kubicki*,&nbsp;","doi":"10.1021/acsearthspacechem.5c00356","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.5c00356","url":null,"abstract":"<p >An extended silicate molecular cluster was used to perform density functional theory calculations to determine if an S_N2 mechanism, where OH^– attacks a Q¹ Si coupled with Na⁺ charge balancing an adjacent siloxane bridging O atom, could explain the observed energy of activation of quartz dissolution under basic conditions.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 5","pages":"1210–1215"},"PeriodicalIF":2.9,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acsearthspacechem.5c00356","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147968280","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":"Detecting Nitrogen Carriers in the Inner Regions of Protoplanetary Disks","authors":"Marissa Vlasblom*,&nbsp;, ,&nbsp;Aditya M. Arabhavi,&nbsp;, ,&nbsp;Niels de Klerk,&nbsp;, ,&nbsp;Inga Kamp,&nbsp;, ,&nbsp;Benoît Tabone,&nbsp;, and ,&nbsp;Ewine F. van Dishoeck,&nbsp;","doi":"10.1021/acsearthspacechem.6c00011","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.6c00011","url":null,"abstract":"<p >Nitrogen is a key element for building habitable worlds, yet only a small fraction of the available N-budget of planet-forming disks has been detected. In particular, the lack of any IR NH₃ detection is striking, as this molecule is predicted to be rather abundant in the warm, inner regions of protoplanetary disks and therefore potentially readily incorporated into (giant) planets’ atmospheres. We present a combined modeling and observational study of N-bearing molecules in planet-forming disks, using detailed thermo-chemical disk models that investigate the sensitivity of N-containing molecules to the bulk elemental composition of the disk. Our models predict a strong increase in HCN flux with high C/H and conversely, a strong increase in flux from NO when O/H is high. The flux from NH₃ is not very sensitive to O/H, but it does decrease at high C/H due to competition with HCN. However, the absolute NH₃ flux predicted by our model is not large enough to be detected with JWST-MIRI, even when N/H is enhanced by an order of magnitude. The flux from NO, on the other hand, is potentially detectable and could therefore provide further insights into the N-budget of the inner disk. Using a cross-correlation technique, we search for NH₃ and NO detections in three disks, GW Lup, Sz 98, and V1094 Sco. We do not find any NH₃ detections and only one tentative NO detection in V1094 Sco, though this needs further study to be confirmed. Additionally, we demonstrate that future facilities in the FIR may provide a better opportunity to detect NH₃ and thereby draw a comparison to the NH₃ budget known to be present in interstellar ices.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 5","pages":"1329–1344"},"PeriodicalIF":2.9,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147968243","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":"Equilibrium Fe–S Isotope Fractionation among Pyrite Precursor Minerals: Insights from Density Functional Theory","authors":"Hao-Long Li,&nbsp;, ,&nbsp;Zhi-Jie Liu,&nbsp;, ,&nbsp;Ming-Shi Wang,&nbsp;, ,&nbsp;Yu-Ce Zhang,&nbsp;, ,&nbsp;Dong-Sheng Ding,&nbsp;, ,&nbsp;Chao Liu,&nbsp;, ,&nbsp;Fa-Yang Guo,&nbsp;, ,&nbsp;Ya-Ru Zhou,&nbsp;, ,&nbsp;Yong-Hui Li,&nbsp;, and ,&nbsp;Yin-Chuan Li*,&nbsp;","doi":"10.1021/acsearthspacechem.5c00391","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.5c00391","url":null,"abstract":"<p >Pyrite (FeS₂) isotopic compositions (δ⁵⁶Fe and δ³⁴S) are widely used as paleoenvironmental tracers, but the interpretations are complicated by isotopic fractionation during transformation of metastable Fe–sulfide precursors (amorphous FeS/cubic FeS/mackinawite/greigite/marcasite → pyrite). While pyrite formation typically proceeds via metastable precursors, these transient phases are rarely preserved in geological records, which makes the determination of Fe–S isotopes during the phase transition process difficult. Herein, density functional theory (DFT) and DFT + U calculations were employed to determine the equilibrium Fe and S isotopic fractionation factors among these minerals across a temperature range of 0–700 °C. Our results establish distinct fractionation levels: marcasite preferentially enriches heavy S (19.97‰) and heavy Fe (10.54‰) isotopes, while greigite hosts the lightest isotopes. Phase transitions induce significant isotopic fractionation, with the largest S isotope fractionation occurring between greigite and pyrite (−10.60‰ at 25 °C) and the significant Fe isotopic fractionation also observed between these two phases (−5.59‰ at 25 °C). Analyses of bond lengths and force constants confirm that 1000 ln β values are inversely proportional to Fe–S bond lengths and positively correlated with force constants. This study provides atomic-scale quantification of equilibrium Fe–S isotope fractionation during the transformation of pyrite precursors, yielding critical insights for interpreting isotopic records in sedimentary diagenesis, hydrothermal mineralization, and paleoredox reconstruction.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 5","pages":"1267–1279"},"PeriodicalIF":2.9,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147968279","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}