ACS Earth and Space Chemistry最新文献

{"title":"Charge-Selective Adsorption of Organic Molecules in Microfluidic Mg(OH)2 Precipitate Membranes","authors":"Maggie A. Cooper,&nbsp;Konrad Sehler,&nbsp;Kenneth Hanson and Oliver Steinbock*,&nbsp;","doi":"10.1021/acsearthspacechem.6c00050","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.6c00050","url":null,"abstract":"<p >The porous mineral structures of alkaline hydrothermal vent chimneys have been proposed as natural concentrators of dissolved organic molecules, potentially addressing the longstanding dilution problem in deep-sea origin-of-life hypotheses. Here, we use microfluidic chemical garden precipitates composed of a primary mineral phase in white smoker chimneys, Mg(OH)₂, to evaluate the adsorption and diffusion behavior of organic dye molecules as a function of their charge state. Pregrown precipitate membranes are exposed to anionic (methyl orange, fluorescein), zwitterionic (rhodamine B), and cationic (crystal violet, malachite green) dye solutions under controlled flow conditions. UV–visible spectroscopy of digested membranes reveals millimolar loading concentrations for anionic dyes after 20 h, limited uptake of the zwitterionic dye over the same period, and negligible adsorption of cationic species. Light-intensity analyses of time-lapse microscopy confirm that anionic dyes permeate the full membrane width within 4 h, while zwitterionic and cationic dyes remain confined near the injection interface. Steady-state and time-resolved emission measurements indicate increased environmental heterogeneity for membrane-bound fluorophores, consistent with adsorption across a distribution of pore sites. Raman spectroscopy corroborates dye-mineral interactions. These results demonstrate that monomineral Mg(OH)₂ precipitates have pronounced charge-selective permeability, favoring anion transport in a manner analogous to the preferential hydroxide diffusion observed during membrane growth. This selectivity implies that negatively charged prebiotic molecules may have been preferentially concentrated within alkaline vent chimney walls, offering a mineral-mediated mechanism to locally elevate reactant concentrations in an otherwise dilute deep-sea environment.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 6","pages":"1554–1561"},"PeriodicalIF":2.6,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148268109","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":"Oxidative Polymerization of Organic Compounds in the Presence of Iron-Bearing Minerals: Implications for Organic Preservation on Mars","authors":"John J. Gumbley*,&nbsp;Nizana Lau,&nbsp;Jonathan S. Watson and Mark A. Sephton,&nbsp;","doi":"10.1021/acsearthspacechem.6c00016","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.6c00016","url":null,"abstract":"<p >Exploring for evidence of life on Mars involves detecting organic signals that may reflect the prebiotic processes which led to the emergence of life or the molecular remnants of biology. For detection at the present day, organic signals, whether abiotic or biological in origin, must have survived over periods that extend to billions of years. The terrestrial fossil organic record indicates that polymerization enhances preservation over time. One polymer-forming process that is observed on Earth, but may be especially relevant to Mars, is oxidative polymerization, where organic compounds are assembled into polymers or macromolecules by reaction with oxidants. On Earth, oxidative polymerization commonly uses atmospheric oxygen, but mineral oxidants can also promote the reaction. Oxidized iron can act as a polymerizing agent for organic compounds and is widespread on the surface of Mars. For instance, the iron oxyhydroxide goethite (α-FeO(OH)) has been detected on Mars by spectrometers carried by orbiters and rovers. This study examines whether Fe(III)-bearing minerals under Mars-relevant conditions can promote oxidative coupling of simple aromatic compounds. Our results show that in environments representative of the Martian near surface, the ferric/iron(III) content of goethite causes oxidative coupling of 2-naphthol (C₁₀H₈O) to its dimer, 1,1′-bi-2-naphthol (BINOL) and, under certain conditions, to larger fused-ring aromatic products. Recognition of the effective polymerization of organic compounds in the presence of a mineral that is common on Mars provides direction for the ongoing search for preserved Martian organic matter when selection of landing sites or sampling locations is taking place.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 6","pages":"1493–1506"},"PeriodicalIF":2.6,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acsearthspacechem.6c00016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148268398","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":"Molecular Insights into Forest Aerosols: Diacids, Oxoacids, and Fatty Acids over a Year in Hokkaido","authors":"Bhagawati Kunwar,&nbsp;Kimitaka Kawamura*,&nbsp;Kei Nosaka,&nbsp;Yuzo Miyazaki,&nbsp;Petr Vodička,&nbsp;Md. Mozammel Haque and Ambarish Pokhrel,&nbsp;","doi":"10.1021/acsearthspacechem.5c00396","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.5c00396","url":null,"abstract":"<p >To better understand the seasonal changes, sources, and transformation pathways of water-soluble organics in a boreal forest, aerosol samples were collected from the deciduous forest in Hokkaido, Japan during January to December 2010. Here, we present the seasonal distributions of diacids (C₂–C₁₀), oxoacids (C₂–C₉), α-dicarbonyls, and fatty acids (FAs) in the forest aerosols. Oxalic acid is the most abundant diacid species followed by malonic and succinic acids, whereas glyoxylic acid (ωC₂) is the dominant ω-oxoacid. The maximum concentrations of short chain diacids (C₂–C₄) in the summer explain an enhanced emission of biogenic volatile organic compounds (VOCs). In contrast, higher concentrations of phthalic acid (Ph), ωC₂, pyruvic acid (Pyr), glyoxal (Gly), and methylglyoxal (MeGly) in the winter suggest enhanced anthropogenic emission of polynuclear aromatic hydrocarbons followed by photochemical degradation in the cold season. Azelaic acid (C₉), a tracer for the oxidation of biogenic unsaturated fatty acids, showed higher concentrations during the summer. Concentration ratios of Ph/C₉ peaked in February and gradually decreased until May, showing lower concentrations until October. Higher concentrations of glutaric (C₅), adipic (C₆), and FAs (except for C_14:0) in autumn suggest the emission from microbial activities in deciduous forests. Water-soluble organic carbon (WSOC) strongly correlated with aerosol liquid water content (LWC) (<i>r</i> = 0.74) in summer, suggesting WSOC is directly involved in the formation of cloud condensation nuclei (CCN) activation. A strong correlation between C₅ and C₆ in autumn suggests a common source, likely VOC emissions, and subsequent degradation. Their correlation with LWC indicates the role of heterogeneous aqueous-phase reactions, suggesting that C₅ and C₆ may be generated from cycloalkenes through such processes.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 6","pages":"1479–1492"},"PeriodicalIF":2.6,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148268337","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":"Quantitative Evaluation of Organic Matter Enrichment of the Lower Cambrian Shale in Intraplatform Basins of the Yangtze Platform (South China): A Machine Learning Approach","authors":"Wei Liu,&nbsp;Ping Gao*,&nbsp;Gary G. Lash,&nbsp;Jinku Li,&nbsp;Guangming Meng,&nbsp;Siyi Liu,&nbsp;Yijie Xing,&nbsp;Yanming Zhao,&nbsp;Dongsheng Li and Xianming Xiao,&nbsp;","doi":"10.1021/acsearthspacechem.6c00056","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.6c00056","url":null,"abstract":"<p >The Ediacaran-Cambrian transition marked a critical period in Earth’s history with dramatic marine environmental fluctuations. Shale successions in intraplatform basins preserve sedimentary records reflecting early Cambrian ocean evolution. However, differences in paleo-marine environments among Yangtze Block’s intraplatform basins and their controls on organic matter enrichment remain poorly constrained. This study presents a comparative geochemical analysis of the western Hubei–eastern Chongqing (EYIB) and Deyang–Anyue intraplatform basins (DAIB) based on data from 13 Lower Cambrian sections. Using machine learning integrated with explanation models, we quantitatively identified dominant factors controlling organic matter enrichment. During the early Cambrian, the Yangtze Block experienced climate shift from cool-arid to relatively warm-humid, with weathering transitioning from physical to chemical dominance. The DAIB received more terrigenous sediment than the EYIB despite similar sedimentation rates. Interval II deposits accumulated under largely anoxic conditions with intermittent euxinia, while Interval III records oxygenated conditions interrupted by anoxia episodes and reduced productivity. The EYIB evolved from moderate to strongly restricted hydrological conditions, with Interval II showing enhanced upwelling. Conversely, the DAIB remained highly restricted with minimal upwelling evidence during Interval III. Machine learning reveals preservation as the dominant control on organic matter enrichment in Interval II (49.4% contribution), followed by productivity (30.6%). Preservation importance increased during Interval III (52.5%), with sedimentation rate (20.6%) and terrigenous input (16.3%) becoming secondary factors. The early Cambrian organic-rich shales record complex interactions among paleoclimate fluctuation, environmental variation, and biological evolution, enhancing our understanding of oceanic evolution and organic carbon burial during this critical transition.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 6","pages":"1576–1592"},"PeriodicalIF":2.6,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148268399","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":"Sailboat Measurements of Trace Gases in Urban Environments: In Toronto, Canada, Ground-Level NO2 Is Consistently Elevated over Lake Ontario versus at the Shoreline, but O3 Is Not","authors":"D. James Donaldson*,&nbsp;","doi":"10.1021/acsearthspacechem.6c00049","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.6c00049","url":null,"abstract":"<p >Ozone (O₃) and nitrogen dioxide (NO₂) are important urban air pollutants which are closely coupled via chemical reactions: in the atmosphere, photolysis of NO₂ forms NO and ozone, while the reaction of NO with O₃ reforms NO₂. The local meteorology near urban centers located on coasts (e.g., sea- or lake-breezes) often gives rise to the advection of polluted air from over the land to over the water during nighttime, and the readvection of the air back ashore during the daytime. Sea- and lake-breeze effects have led to higher-than-normal ozone concentrations over coastal urban areas; concentrations of both O₃ and NO₂ have been reported to be higher over the water than inland. Most of these findings have come from remote sensing column measurements, using satellites and Pandora (DOAS), combined with land-based measurements from air quality stations. Here we present results from a 3-year campaign of measurements of “ground level” O₃ and NO₂ concentrations made over 17 cruises on Lake Ontario and at its shoreline near Toronto. Using portable sensors mounted on a sailboat, we found that while there is no clear or consistent difference in ozone concentrations over water vs at the shoreline, NO₂ was higher over the water for 12 of the 17 cruises and was the same over water and at the shoreline for the remaining 5. We discuss possible reasons for this observation.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 6","pages":"1543–1553"},"PeriodicalIF":2.6,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148268172","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":"Molecular Insights into the Photochemistry of cis-Pinonic Acid and Its Complexes with O2 and H2O","authors":"Sophie Sobanska*,&nbsp;Rosana M. Romano,&nbsp;Joëlle Mascetti and Stéphane Coussan*,&nbsp;","doi":"10.1021/acsearthspacechem.6c00041","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.6c00041","url":null,"abstract":"<p >cis-Pinonic acid (cPA) is one of the major photooxidation products of α-pinene and contributes to the formation of biogenic secondary organic aerosol (BSOA). Although the direct photolysis of cPA in aqueous solution has already been described, showing mainly Norrish II-type reaction, the molecular process, in particular the role of water and oxygen, has not yet been fully understood. This experimental work aims to study cis-pinonic acid and how its complexation with water and/or oxygen influences its ultraviolet (UV) photochemistry. One method for studying these complexes at the molecular level in their ground state is the cryogenic matrix technique coupled with Fourier transform infrared (FTIR) spectroscopy, which can be compared with density functional theory (DFT) theoretical calculations of the potential energy surface (PES) minima and their sets of vibrational frequencies. We studied cPA and its complexes in four cryogenic matrices: nitrogen, argon, neon, and xenon, to evaluate the potential matrix influence. The effects of broad band UV irradiation using a mercury vapor lamp under solar conditions (wavelength greater than 290 nm) can be contrasted with unfiltered irradiations. Although the observed effects are generally similar for all matrices, we clearly identified <i>syn-anti</i> isomerization of the carboxyl group in the nitrogen matrix even under solar conditions irradiation. When irradiated without a filter, carbon dioxide, carbon monoxide, and water are formed, showing the exclusive Norrish I-type reaction in the matrix. Neither water nor oxygen alters the photoinduced fragmentation. Even when it forms a complex with cPA, water appears to be a spectator to this fragmentation. However, the presence of oxygen considerably increases the amount of carbon dioxide and carbon monoxide produced, which confirms a triplet state transition during the electronic relaxation of cPA.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 6","pages":"1521–1534"},"PeriodicalIF":2.6,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148268124","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":"Effect of Photochemical Aging on Biomass Burning Emissions: Contributions of Oxidized Organic Nitrogen from a Variety of Biomass Types","authors":"Osayomwanbor E. Oghama*,&nbsp;Aristeidis Voliotis,&nbsp;Thomas J. Bannan,&nbsp;Sara A. Syafira,&nbsp;Dawei Hu,&nbsp;Huihui Wu,&nbsp;Peter Gallimore,&nbsp;Emily Matthews,&nbsp;Gordon McFiggans,&nbsp;Hugh Coe and James D. Allan*,&nbsp;","doi":"10.1021/acsearthspacechem.6c00093","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.6c00093","url":null,"abstract":"<p >Biomass burning is a major source of reactive organic nitrogen, yet the fuel-specific, combustion-dependent, and time-resolved chemistry of these emissions during photooxidation remains incompletely characterized. This study examines how stove emissions from four biomass fuels evolve under laboratory-controlled chamber oxidation, with a focus on the oxidized organic nitrogen (OON). Rather than sampling emissions over an entire burn, short-duration, burning-phase-resolved emissions were introduced into the Manchester aerosol chamber (MAC), allowing the chemical evolution of smoke from specific combustion phases to be examined in isolation. Wood (generated under flaming and smoldering conditions), peat, and leaves’ smoke were aged for 6 h, and the gas- and particle-phase composition was monitored using online and offline measurements. The results showed that gas-phase aging followed patterns consistent with fragmentation, leading to an increase in carbon oxidation state, a decrease in mean carbon number, and a reduction in aromaticity. In contrast, particle-phase aging showed an increasing contribution of larger, more aromatic and nitrogen-rich OON, consistent with the formation or retention of lower-volatility products through accretion-type processes, gas–particle partitioning, and/or heterogeneous oxidation. Clear burn-phase-, fuel-type-, and time-dependent evolution was observed, with organo-nitrate formation occurring predominantly within the first ∼2 h of photooxidation, followed by convergence in organic aerosol (OA) properties (<i>f</i>₄₃, <i>f</i>₄₄, <i>f</i>₆₀) with continued aging. Levoglucosan (<i>f</i>₆₀) decayed most rapidly in flaming wood emissions, reaching near-background levels by 6 h, which may contribute to the underestimation of aged BBOA in ambient-source apportionment studies. Overall, the results show that OON formation and evolution vary by fuel type, combustion phase, and oxidation time scale, with relevance for atmospheric modeling and exposure assessment.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 6","pages":"1626–1640"},"PeriodicalIF":2.6,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148268218","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":"Integrated Evaluation of Oxidative Potential and Antioxidant Activity of Ambient PM2.5 in Lahore: Decoupling between Mass Concentration and Redox Reactivity","authors":"Rana Haris Abdullah,&nbsp; and ,&nbsp;Shahana Sarfraz Khurshid*,&nbsp;","doi":"10.1021/acsearthspacechem.6c00097","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.6c00097","url":null,"abstract":"<p >Ambient fine particulate matter (PM_2.5) exerts adverse effects largely through redox-mediated mechanisms; however, conventional mass-based metrics do not adequately capture its chemical reactivity. Here, we present a nine-month field investigation (August 2024–April 2025) of the redox behavior of ambient PM_2.5 in Lahore, Pakistan, using an integrated multiassay approach. Oxidative potential was quantified using the dithiothreitol (DTT) assay, while antioxidant capacity was evaluated using DPPH and ABTS assays to characterize both pro-oxidant and electron-donating components of atmospheric aerosols. PM_2.5 concentrations exhibited pronounced seasonal variability, increasing from 166.14 ± 5.24 μg m^–3 in August to a maximum of 400.23 ± 63.82 μg m^–3 in November. Volume-normalized oxidative potential (DTT_v) ranged from 6.71 to 20.22 nmol min^–1 m^–3 and increased significantly with PM_2.5 concentration (<i>r</i> = 0.518, <i>p</i> &lt; 0.001), indicating greater oxidative burden during high-pollution episodes. In contrast, mass-normalized oxidative potential (DTT_m) ranged from 0.02 to 0.13 nmol min^–1 μg^–1 and exhibited a significant inverse relationship with PM_2.5 concentration (<i>r</i> = −0.714, <i>p</i> &lt; 0.001), suggesting enhanced intrinsic particle reactivity during lower-pollution periods. Antioxidant activity showed similar seasonal trends, with DPPH antioxidant capacity ranging from 57.50–133.57 μg AAE mg^–1 (aqueous extract) and 58.57–144.64 μg AAE mg^–1 (ethanolic extract), while ABTS antioxidant capacity ranged from 83.35–205.49 μg TE mg^–1; all were positively associated with PM_2.5 concentration. The contrasting behavior of DTT_v and DTT_m, together with the observed antioxidant responses, demonstrates that aerosol redox properties are governed not only by particle abundance but also by chemical composition and atmospheric transformation processes. These findings highlight the importance of integrating oxidative-potential and antioxidant-capacity measurements to provide a more chemically informed assessment of urban aerosol reactivity and potential health relevance in highly polluted environments.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 6","pages":"1641–1651"},"PeriodicalIF":2.6,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148268435","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":"Decade-Long Soil Cover Promotes Mineral Weathering and Organic Matter Accrual in Fe Ore Tailings But Deteriorates Topsoil","authors":"Hui Wu,&nbsp;Wei Fu,&nbsp;Zijie Yang,&nbsp;Chenglong Lu,&nbsp;Suixiaochen Chen,&nbsp;Yuqi Wu,&nbsp;Yunjia Liu,&nbsp;Meie Wang,&nbsp;Cheng-Wei Kao,&nbsp;Ting-Shan Chan*,&nbsp;Baodong Chen and Songlin Wu*,&nbsp;","doi":"10.1021/acsearthspacechem.6c00034","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.6c00034","url":null,"abstract":"<p >Soil cover is widely adopted to initiate ecological rehabilitation on tailing deposits, yet its influence on geochemical processes and organic matter (OM) dynamics in underlying tailings remains poorly understood. This study investigated the physicochemical and mineralogical evolution of iron (Fe) ore tailings in Hebei Province, China, following a decade of soil cover and revegetation. Soil cover and revegetation generally neutralized alkalinity, fostered microaggregate formation, and improved OM stabilization in the underlying tailings. Synchrotron-based Fe K-edge X-ray absorption spectroscopy (XAS) identified a transformation of primary biotite-like minerals into Fe(III) oxyhydroxides. Nanoscale secondary ion mass spectrometry further delineated the submicrometer association of these secondary Fe and aluminum (Al)-bearing minerals with OM, which underpins the mechanisms of OM stabilization. Notably, soil cover with grass rehabilitation proved more effective than that with cropland in driving the above-mentioned processes. Conversely, the underlying tailings exerted a deleterious influence on the soil cover, manifested by increased alkalinity and metal(loid) concentrations, alongside a reduction in total organic carbon, nitrogen, and aggregate stability relative to those of natural soils. These findings demonstrate that while soil cover and revegetation partially ameliorate unfavorable conditions in Fe ore tailings, they degrade soil cover quality, implying the requirement of an integrated strategy to preserve the functional stability of the entire profile.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 6","pages":"1507–1520"},"PeriodicalIF":2.6,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148268341","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":"Photostability of Quercetin under Oxidative Conditions Relevant to Mars","authors":"Severin Wipf,&nbsp;Florence Hofmann,&nbsp;Ruben Nitsche,&nbsp;Zeba Sultana,&nbsp;Riccardo Giovanni Urso,&nbsp;David J. Burr,&nbsp;Nykola C. Jones,&nbsp;Søren Vrønning Hoffmann and Andreas Elsaesser*,&nbsp;","doi":"10.1021/acsearthspacechem.6c00054","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.6c00054","url":null,"abstract":"<p >Understanding the photochemical stability of organic compounds under Martian surface conditions is essential for assessing their detectability, as such compounds would be exposed to intense ultraviolet (UV) radiation and diverse oxidizing environments. This study investigates the photodegradation of quercetin, a polyphenolic compound discussed as a potential indicator of past organic processes and a target molecule for the European Space Agency (ESA) missions OREOcube and ExocubeChem. Oxidative influences were systematically isolated under experimentally simulated Martian conditions by controlled variation of atmospheric composition and the inclusion of the clay mineral montmorillonite (Mont) as a matrix. Quercetin thin films were exposed to simulated Mars-surface UV radiation and temperatures under two distinct conditions: (i) CO₂-dominated Mars atmosphere (CO₂, 95%; Ar, 3%; and N₂, 2%) and (ii) the same atmosphere with adding 5% relative humidity (RH). Additional experiments were conducted with quercetin intercalated into Mont mineral. Degradation kinetics were monitored by ultraviolet–visible (UV–vis) and infrared (IR) transmission spectroscopy, while vacuum ultraviolet–UV (VUV–UV) spectroscopy enabled detection of gaseous photoproducts. Complementary irradiation under oxygen-rich conditions at room temperature (RT) provided additional kinetic constraints. In a CO₂-dominated atmosphere, quercetin undergoes conformational rearrangement without fragmentation. Humidity accelerates degradation, consistent with hydroxyl radical attack on the conjugated system. Oxygen-rich conditions induce the fastest decay, accompanied by C═O formation and CO release, indicative of superoxide-mediated oxidation. In contrast, intercalation into Mont prolongs quercetin lifetimes, attributed to UV shielding and geometric confinement. These results demonstrate that reactive oxygen species (ROS) govern quercetin photochemistry under Martian-relevant conditions, whereas Mont association can enhance molecular persistence.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"10 6","pages":"1562–1575"},"PeriodicalIF":2.6,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acsearthspacechem.6c00054","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148268367","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}