ACS Earth and Space Chemistry最新文献

{"title":"CHF3 (HFC-23) and CF3CHO Quantum Yields in the Pulsed Laser Photolysis of CF3CHO at 248, 266, 281, and 308 nm","authors":"Daniel Van Hoomissen,&nbsp;Aparajeo Chattopadhyay,&nbsp;Stephen A. Montzka and James B. Burkholder*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0031610.1021/acsearthspacechem.4c00316","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00316https://doi.org/10.1021/acsearthspacechem.4c00316","url":null,"abstract":"<p >Ultraviolet (UV) photolysis of trifluoroacetaldehyde (CF₃CHO), an atmospheric degradation product of anthropogenically emitted compounds, is a potential source of fluoroform (CHF₃, HFC-23), which is a potent greenhouse gas. In this study, CF₃CHO photolysis quantum yields, ϕ_CF₃CHO(λ, <i>P</i>), and CHF₃ product and quantum yields were measured following the pulsed laser photolysis of CF₃CHO at 248, 266, 281, and 308 nm at total pressures between 100 and 678 Torr (N₂/NO bath gas mixtures). Loss of CF₃CHO was measured using Fourier transform infrared spectroscopy (FTIR), and the formation of CHF₃ was measured by FTIR (248, 266, and 281 nm) and off-line gas chromatography–mass spectrometry (GC/MS) (248, 266, and 308 nm). ϕ_CF₃CHO(248 nm, 650–678 Torr) and ϕ_CF₃CHO(266 nm, 650 Torr) were measured to be 1.03 ± 0.06 and 0.94 ± 0.06, respectively, i.e., near unity, using CBrF₂CBrF₂ (Halon-2402) and CF₃I as the actinometry references, respectively. The CHF₃ molar product yields at 248 and 266 nm were measured to be 0.348 ± 0.02 and 0.438 ± 0.015, respectively. CF₃CHO quantum yields measured for 281 and 308 nm photolysis were found to be pressure-dependent over the 100 to 650 Torr (N₂/NO) pressure range. A Stern–Volmer analysis of the CF₃CHO quantum yield results yielded <i>k</i>_Q/<i>k</i>_D values of (3.25 ± 0.20) × 10^–20 cm³ molecule^–1 at 281 nm and (1.91 ± 0.02) × 10^–19 cm³ molecule^–1 at 308 nm, i.e., ϕ_CF₃CHO(281 nm, 650 Torr) = 0.54 ± 0.06 and (308 nm, 650 Torr) = 0.204 ± 0.028. The CHF₃ molar product yields obtained at 281 and 308 nm showed a weak decrease with increasing pressure with values of 0.105 ± 0.002 and (1.71 ± 0.70) × 10^–3 obtained at 650 Torr, respectively. All quoted measurement uncertainties are 2σ standard deviation. An evaluation of this photochemical source of CHF₃ following the atmospheric degradation of hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), hydrofluoroolefins (HFOs), and hydrochlorofluoroolefins (HCFOs) that are observed in the present-day atmosphere is presented and the atmospheric implications discussed.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 3","pages":"589–602 589–602"},"PeriodicalIF":2.9,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654378","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":"Detection of Aerosolized Anabaenopeptins from Cyanobacterial Harmful Algal Blooms in Atmospheric Particulate Matter","authors":"Jia H. Shi,&nbsp;Johnna A. Birbeck,&nbsp;Nicole E. Olson,&nbsp;Rebecca L. Parham,&nbsp;Andrew L. Holen,&nbsp;Isabel R. Ledsky,&nbsp;Boddu S. Ramakrishna,&nbsp;Landon Bilyeu,&nbsp;Stephen J. Jacquemin,&nbsp;David G. Schmale III,&nbsp;Jennifer L. Stockdill,&nbsp;Judy A. Westrick* and Andrew P. Ault*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0032010.1021/acsearthspacechem.4c00320","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00320https://doi.org/10.1021/acsearthspacechem.4c00320","url":null,"abstract":"<p >Cyanobacterial harmful algal blooms (cHABs) can produce bioactive compounds that can pose a public health risk, including anabaenopeptins (APs), a family of metabolites comprised of six amino acids in a five-membered cyclic structure shown to inhibit several important enzymes. Only a few studies have quantified APs in water, and no studies have measured APs in the atmosphere. The limited waterborne measurements indicate that APs are frequently present at concentrations higher than other potent toxins and metabolites produced by cyanobacteria. Herein, this study quantifies concentrations of the four abundant AP congeners (AP-B, AP-F, AP-A, and Osc-Y) in water samples and atmospheric aerosol samples from around Grand Lake St. Marys (GLSM), Ohio, in 2019 and 2022. In 2019, the total AP concentration in GLSM water was 130 ± 20 μg/L, dominated by the AP-B congener. In 2022, the total water concentration of APs was 70 ± 20 μg/L and was instead dominated by AP-F. Particulate matter (PM) AP concentrations up to 48 pg/m³ were detected in 2019, 3.7 times higher than microcystin toxins (13 pg/m³) sampled at the same time. Aerosolization of extracellular versus intracellular APs was explored using raw and lysed GLSM water samples. Water samples lysed via freeze–thaw cycles showed up to a 100× increase in aerosolized AP concentrations. Measurements of aerosolized APs in the ambient atmosphere and the connection to water concentrations demonstrate the need for further research on inhalation exposure to airborne APs and evaluation of potential impacts on public health.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 3","pages":"603–616 603–616"},"PeriodicalIF":2.9,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654333","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":"Photochemical Degradation of Iron Citrate in Anoxic Viscous Films Enhanced by Redox Cascades","authors":"Ashmi Mishra,&nbsp;Kevin Kilchhofer,&nbsp;Lucia Iezzi,&nbsp;Ulrich Pöschl,&nbsp;Peter A. Alpert,&nbsp;Markus Ammann and Thomas Berkemeier*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0036410.1021/acsearthspacechem.4c00364","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00364https://doi.org/10.1021/acsearthspacechem.4c00364","url":null,"abstract":"<p >Iron contained in atmospheric aerosol particles can form complexes with organic ligands and initiate photochemical reactions that alter the composition and physicochemical properties of the particles. Depending on the temperature and humidity, organic particles exist in different phase states, which affects reactant diffusivity and chemical reaction rates. We performed coated-wall flow-tube experiments using citric acid films doped with iron as proxies for secondary organic aerosols. We quantified the CO₂ production under UV irradiation as a function of time and relative humidity (RH) and observed a pronounced decrease of CO₂ production with decreasing RH. The kinetic multilayer model of aerosol surface and bulk chemistry (KM-SUB) and a Monte Carlo-based global optimization method were applied to all measured data to determine the underlying effects of mass transport and chemical reactions. The model analysis revealed that after an initial rapid reaction, photooxidation becomes limited by the reoxidation of Fe^II. Under dry conditions (RH &lt; 65%), the reoxidation of Fe^II is kinetically limited by the supply of O₂, as slow diffusion in the viscous organic matrix leads to anoxia in the interior of the film. At high humidity (RH &gt; 85%), mass transport limitations cease, resulting in full O₂ saturation, and photooxidation becomes limited by the chemical reaction of Fe^II with oxidants. Reactive oxygen species play a key role in Fe^II reoxidation and thus in perpetuating photooxidation chemistry. A single O₂ molecule triggers a redox cascade from O₂ to HO₂, H₂O₂, and OH, leading to ≈3 cycles of the Fe^II/Fe^III redox pair. Our model and kinetic parameters provide new insights and constraints in the interplay of microphysical properties and photochemical aging of mixed organic–inorganic aerosol particles, which may influence their effects on air quality, climate, and public health.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 3","pages":"689–698 689–698"},"PeriodicalIF":2.9,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00364","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654335","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":"Photochemical Degradation of Iron Citrate in Anoxic Viscous Films Enhanced by Redox Cascades.","authors":"Ashmi Mishra, Kevin Kilchhofer, Lucia Iezzi, Ulrich Pöschl, Peter A Alpert, Markus Ammann, Thomas Berkemeier","doi":"10.1021/acsearthspacechem.4c00364","DOIUrl":"10.1021/acsearthspacechem.4c00364","url":null,"abstract":"<p><p>Iron contained in atmospheric aerosol particles can form complexes with organic ligands and initiate photochemical reactions that alter the composition and physicochemical properties of the particles. Depending on the temperature and humidity, organic particles exist in different phase states, which affects reactant diffusivity and chemical reaction rates. We performed coated-wall flow-tube experiments using citric acid films doped with iron as proxies for secondary organic aerosols. We quantified the CO₂ production under UV irradiation as a function of time and relative humidity (RH) and observed a pronounced decrease of CO₂ production with decreasing RH. The kinetic multilayer model of aerosol surface and bulk chemistry (KM-SUB) and a Monte Carlo-based global optimization method were applied to all measured data to determine the underlying effects of mass transport and chemical reactions. The model analysis revealed that after an initial rapid reaction, photooxidation becomes limited by the reoxidation of Fe^II. Under dry conditions (RH < 65%), the reoxidation of Fe^II is kinetically limited by the supply of O₂, as slow diffusion in the viscous organic matrix leads to anoxia in the interior of the film. At high humidity (RH > 85%), mass transport limitations cease, resulting in full O₂ saturation, and photooxidation becomes limited by the chemical reaction of Fe^II with oxidants. Reactive oxygen species play a key role in Fe^II reoxidation and thus in perpetuating photooxidation chemistry. A single O₂ molecule triggers a redox cascade from O₂ to HO₂, H₂O₂, and OH, leading to ≈3 cycles of the Fe^II/Fe^III redox pair. Our model and kinetic parameters provide new insights and constraints in the interplay of microphysical properties and photochemical aging of mixed organic-inorganic aerosol particles, which may influence their effects on air quality, climate, and public health.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 3","pages":"689-698"},"PeriodicalIF":2.9,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11931546/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143707774","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":"Kaolinite as a Key Transporter of Mg and Fe in Subtropical Weathering Crust: Insights from Mg and Fe Isotopes","authors":"Kadi Song,&nbsp;Meng Qi,&nbsp;Ting Gao* and Chengshuai Liu,&nbsp;","doi":"10.1021/acsearthspacechem.4c0036710.1021/acsearthspacechem.4c00367","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00367https://doi.org/10.1021/acsearthspacechem.4c00367","url":null,"abstract":"<p >Silicate weathering plays a central role in regulating elemental cycling on the Earth’s surface, supplying essential nutrients to terrestrial vegetation and marine ecosystems. Magnesium (Mg) and iron (Fe) isotopes are useful tools for tracking the migration pathways of Mg and Fe during silicate weathering. Here, we analyzed the Mg and Fe isotopic compositions of a weathering profile on a granite pluton from subtropical Central China. The profile displays higher δ²⁶Mg (−0.10‰–0.28‰) and δ⁵⁶Fe (0.08‰–0.33‰) values than the parent granite rocks. The weathering layer contains abundant kaolinites (16.6–31.5 wt %) that are enriched in isotopically heavier structural Mg and Fe species compared to the regolith. A covariation of kaolinite content, δ²⁶Mg, and δ⁵⁶Fe in this profile highlights the critical role of the downward migration of kaolinite in causing vertical variations of δ²⁶Mg and δ⁵⁶Fe. These findings highlight kaolinite as a key transporter of Mg and Fe in weathering profiles and suggest that the variation of δ²⁶Mg and δ⁵⁶Fe in weathering profiles is not solely a result of isotope fractionation during redox reactions and mineral transformations. This study enhances our understanding of Mg and Fe isotopic fractionations during silicate weathering, providing critical constraints on their behavior and emphasizing the critical role of fine-grained materials, such as clay, in driving multielemental migration during physical transport.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 3","pages":"681–688 681–688"},"PeriodicalIF":2.9,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654334","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":"Silicon Isotope Effects of He Ion Irradiation on Olivine","authors":"Delphine Losno,&nbsp;Caroline Fitoussi,&nbsp;Ingo Leya,&nbsp;Mathieu Roskosz and Bernard Bourdon*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0018210.1021/acsearthspacechem.4c00182","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00182https://doi.org/10.1021/acsearthspacechem.4c00182","url":null,"abstract":"<p >During the early history of the Solar System or in molecular clouds, dust particles were submitted to intense irradiation by protons, and helium nuclei accelerated to MeV energies or higher. The consequence of this irradiation on the isotope composition of solids at such energies is unknown, but major element modifications of chemical compositions suggest that there could be isotope fractionation associated with irradiation. In this study, we have analyzed the Si isotope composition of olivine layers produced by sputter deposition starting from San Carlos olivine. The deposits were irradiated by He²⁺ with a total fluence of 1.5 × 10¹⁷. The olivine deposits were analyzed prior to and after irradiation for Si isotopes by multicollector ICPMS. The Si isotope composition after sputter deposition (prior to He irradiation) was enriched in heavy Si isotopes with a mean δ³⁰Si value of 12.6‰ relative to the NBS-28 standard, whereas the irradiated olivine had lower δ³⁰Si values of 10.8‰ and 8.2‰ for the 200 keV and 6 MeV He irradiation, respectively. In both cases, the Si isotope fractionation are strictly mass-dependent. First, these results show that the process of sputter deposition induces a large enrichment in heavy Si isotopes that we attribute to a difference in the sticking coefficient of SiO isotopologues. Second, the effect of He irradiation is the reverse of what is expected from theoretical studies and numerical simulations of isotope fractionation under these irradiation conditions at lower energies (keV range). The enrichment in light Si isotopes could be due to redistribution processes and segregation that take place during the irradiation. This study suggests that Si isotopes could be powerful tracers of irradiation processes in astrophysical settings.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 3","pages":"445–456 445–456"},"PeriodicalIF":2.9,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654332","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":"Trends in Structure and IR Spectra of Mixed H2O/CO2 Ices of Astrochemical Relevance","authors":"Niels M. Mikkelsen,&nbsp;Thanja Lamberts* and Mie Andersen*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0035310.1021/acsearthspacechem.4c00353","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00353https://doi.org/10.1021/acsearthspacechem.4c00353","url":null,"abstract":"<p >Molecular clouds in the interstellar medium harbor ices formed on the surfaces of dust grains, consisting primarily not only of H₂O but also, for example, CO, CO₂, and CH₃OH. The dangling O–H bands at frequencies around 3630–3720 cm^–1, slightly higher than the high-frequency shoulder of the bulk O–H stretch band, provide information on the structural properties of amorphous water ices. The presence of the dangling mode indicates that an interface is present: a vacuum interface is often interpreted as porosity, as opposed to an interface with a nonwater neighboring molecule. We computationally study the role played by mixing ratio, segregation level, and the type of interface present in the ice for the IR peak positions of the dangling O–H band and the CO₂ bend and stretch bands in mixed H₂O/CO₂ ices. Molecular interactions are described using the MB-nrg force field, and we show that it can accurately predict experimentally observed shifts in IR peaks, although absolute peak positions are generally overestimated. Overall, our study reveals a significant influence of the local environment of a molecule on the dangling O–H and the CO₂ stretch band, where in particular the mixing ratio, type of interface, and to a lesser extent segregation level come out as influential, while the density and temperature have negligible effects on peak positions.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 3","pages":"627–637 627–637"},"PeriodicalIF":2.9,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654328","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":"Catalytic Efficiencies for Methane Removal: Impact of HOx, NOx, and Chemistry in the High-Chlorine Regime","authors":"Luisa Pennacchio,&nbsp;Maarten van Herpen,&nbsp;Daphne Meidan,&nbsp;Alfonso Saiz-Lopez and Matthew S. Johnson*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0028310.1021/acsearthspacechem.4c00283","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00283https://doi.org/10.1021/acsearthspacechem.4c00283","url":null,"abstract":"<p >Catalytic production of chlorine atoms from iron salt aerosols has been suggested as a means of achieving atmospheric methane removal. The feasibility of this approach, its efficiency, and the optimum conditions for deployment must be determined, but this is not straightforward as the mechanism involves interlocking nonlinear atmospheric free radical chain reactions; under some conditions added chlorine is known to increase methane lifetime. Here we evaluate the catalytic efficiency of atmospheric methane oxidation under different conditions, initiated by the photocatalytic conversion of chloride to chlorine by iron chlorides Fe(III)Cl_<i>n</i>^{(3–<i>n</i>)} using a box model. While HO<i>x</i> and high NO<i>x</i> behaviors are well-known, a new regime for tropospheric chemistry is found and described, one characterized by high ClO<i>x</i> conditions. We find that at chlorine production rates below 1 × 10⁶ Cl₂ /(cm³ s) and ambient NO<i>x</i> and O₃ levels of 4–80 ppt NO<i>x</i> at 14 ppb O₃, 8–180 ppt NO<i>x</i> at 30 ppb O₃, and 14–200 ppt NO<i>x</i> at 40 ppb O₃ the net effect on CH₄ is negative, increasing CH₄ concentrations. This variation is driven by the formation and hydrolysis of ClONO₂ leading to the loss of O₃ and NO₂. At high rates of Cl₂ addition the reaction of CH₃OOH with Cl becomes the major source of OH and CH₄ is removed. At elevated ClO<i>x</i>, ClO^• usurps the role of NO in converting HO₂ to OH and CH₃O₂ to CH₃O. The efficiencies seen in the model range from −0.62 to 2.81 CH₄/Cl. The modeling shows that due to the dispersion of a ship’s plume into low NO<i>x</i> conditions, iron emitted by ships is likely to increase the lifetime of atmospheric methane.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 3","pages":"504–512 504–512"},"PeriodicalIF":2.9,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654279","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":"In Situ Atmospheric Plume Thermometry via Carbon Monoxide Spectral Profile: Laboratory and Field Validation","authors":"Michael J. Wilhelm,&nbsp;Molly M. Herzog,&nbsp;Russell G. Tonkyn,&nbsp;Michael J. Howard,&nbsp;Patrick S. Sawyer and Timothy J. Johnson*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0028910.1021/acsearthspacechem.4c00289","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00289https://doi.org/10.1021/acsearthspacechem.4c00289","url":null,"abstract":"<p >For small molecules with large rotational constants, knowing the relative intensities of the ro-vibrational transitions can be used to determine the temperature within a gas plume. We demonstrate the use of carbon monoxide (CO) as an <i>in situ</i> spectroscopic probe of gas plume temperature by application of both laboratory and standoff Fourier transform infrared spectroscopy to monitor the CO spectral response at different temperatures. The measured CO rotational contours were analyzed using a simple Boltzmann model to deduce the population distribution of the J-levels, from which the in-plume temperature is deduced. The method was vetted by comparing calculated temperatures to both static laboratory measurements of known temperatures, as well as field measurements using a simulated smokestack release. The calculated and laboratory values agreed to within 1 °C. For the smokestack experiments, the spectroscopically deduced temperatures were compared to readings from a series of thermocouples placed at strategically sampled distances along the plume trajectory. Both the spectroscopically derived as well as the thermocouple-measured temperatures revealed a rapid cooling of the plume, with the infrared thermometry values displaying greater temperature values which are believed to better represent the actual plume temperatures.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 3","pages":"513–523 513–523"},"PeriodicalIF":2.9,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654364","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":"Surfactant Effects in Irradiated, Hanging-Droplet, Aqueous-Phase Glyoxal/Ammonium Sulfate Aerosol Mimic Systems","authors":"Daphna Fertil,&nbsp;Katherine Pierre-Louis,&nbsp;Stephanie Ingwer,&nbsp;Melissa M. Galloway and Joseph L. Woo*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0028810.1021/acsearthspacechem.4c00288","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00288https://doi.org/10.1021/acsearthspacechem.4c00288","url":null,"abstract":"<p >Carbonyl-containing volatile organic compounds (CVOCs) are present in a wide range of atmospherically relevant contexts and can contribute significant portions of water-soluble organic carbon in aqueous aerosols, forming a variety of heterocyclic or oligomeric products under dark conditions. However, condensed-phase chemistry under irradiated conditions is much less understood and results in potential shifts to the overall extent of CVOC oligomerization. This study reports in situ surface tension measurements of glyoxal/ammonium sulfate hanging-droplet aqueous aerosol mimics that are directly irradiated with ultraviolet light and subsequently undergo aqueous-phase photochemistry due to this exposure. The surface tension values of aged glyoxal/ammonium sulfate solutions (79.7 ± 0.2 dyn/cm) are slightly lower than those of ammonium sulfate solutions without organics (80.1 ± 0.2 dyn/cm). Direct photochemistry in hanging droplets results in the formation of products capable of slight (−2.9 ± 2.3%) but statistically significant (<i>p</i> = 0.002) surface tension depression. Changes in the relative quantities of heterocyclic and aldol oligomeric products are observed in irradiated, hanging-droplet aerosol mimics, in contrast to comparably irradiated bulk solutions and non-irradiated hanging-droplet samples. Mimic solutions containing additional surfactants [sodium dodecyl sulfate (SDS) and methylsuccinic acid (MSA)] also exhibit compositional changes but do not demonstrate statistically significant differences in surface tension upon being irradiated (<i>p</i> = 0.563 and 0.422 for SDS and MSA, respectively).</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":"9 3","pages":"524–532 524–532"},"PeriodicalIF":2.9,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143654365","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}