ACS Earth and Space Chemistry最新文献

{"title":"Selectivity of N2–CH4 Mixed Clathrate Hydrates: A Grand Canonical Monte Carlo Study","authors":"Julien Joliat, Delphine Vardanega-Bonneton, Antoine Patt, Sylvain Picaud","doi":"10.1021/acsearthspacechem.4c00086","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00086","url":null,"abstract":"In this article, we report the results of a grand canonical Monte Carlo simulation study aiming at characterizing the competitive trapping of N₂ and CH₄ molecules into the same clathrate hydrate structure. Simulations have been performed at temperature conditions typical of those encountered at the surface of, e.g., Titan, and in accordance with recent experiments. Various compositions of the fluid in contact with the clathrate hydrate phase, i.e., various nitrogen/methane ratios, have been considered in the simulations. The results of these simulations reveal that, although the ratio between the number of enclathrated methane and that of nitrogen molecules strongly varies with the composition of the fluid phase, the clathrate hydrate lattice remains always selective for methane. This means that the relative proportion of methane with respect to nitrogen is always larger in the clathrate phase than in the fluid phase, with the mixed clathrate hydrate thus acting as a methane concentrator, irrespective of the fluid composition. These features indicate that the formation of clathrate hydrates can strongly influence the composition of the nitrogen–methane fluid phase, which may thus be impoverished in methane, as already inferred from the experimental results.","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141743853","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":"MarSCoDe Martian Material Analysis Based on a PSO–SVR Approach","authors":"Xiong Wan, Peipei Fang, Yian Wang, Yingjian Xin, Mingkang Duan, Hongpeng Wang, Xinru Yan, Chenhong Li, Yanhua Ma, Zhiping He","doi":"10.1021/acsearthspacechem.4c00100","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00100","url":null,"abstract":"Laser-induced breakdown spectroscopy (LIBS) has been used for deep space exploration in recent years. The advantages of LIBS include high efficiency, stand-alone detection, and the ability to analyze multiple elements simultaneously. However, due to the fluctuation of laser energy, matrix effect, and instrumental noises, the quantitative prediction of LIBS instruments for planetary exploration is not satisfactory, especially for unknown targets. Therefore, comprehensive methods with higher adaptability and prediction accuracy must be developed to meet the needs of LIBS planetary material analysis. In this paper, we proposed an approach, which is mainly based on a particle swarm optimization (PSO)–support vector regression (SVR) analysis model, for material analysis of MarSCoDe, the LIBS payload of the Chinese Zhurong Mars rover. The model adopts a PSO algorithm to optimize the parameters and hence improve the prediction accuracy of traditional SVR equations. The training of the model was completed with 3600 LIBS spectra, which involved 60 standards and were obtained in the ground simulated Martian chamber before the launch of MarSCoDe. The quantitative performance of the model was evaluated by the coefficient of determination (<i>R</i>²) and root-mean-square error between real contents and predicted contents. Comparison with convolutional neural network and partial least squares showed that the PSO–SVR model has the highest prediction accuracy and the best robustness. After the launch, we used the LIBS spectra of the LC-005 calibration standard on a Zhurong rover to further evaluate the prediction accuracy of the model. The main element contents of LC-005 predicted by the model are basically consistent with its real contents. Since then, the model has been used in the onboard quantitative element analysis of MarSCoDe. Finally, quantitative analysis results of eight different unknown Martian targets on different Mars days are selected and shown, which reflects the main geological composition of the landing area of the Martian Utopia plain.","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141743854","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":"Selectivity of N2–CH4 Mixed Clathrate Hydrates: A Grand Canonical Monte Carlo Study","authors":"Julien Joliat,&nbsp;Delphine Vardanega-Bonneton,&nbsp;Antoine Patt and Sylvain Picaud*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0008610.1021/acsearthspacechem.4c00086","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00086https://doi.org/10.1021/acsearthspacechem.4c00086","url":null,"abstract":"<p >In this article, we report the results of a grand canonical Monte Carlo simulation study aiming at characterizing the competitive trapping of N₂ and CH₄ molecules into the same clathrate hydrate structure. Simulations have been performed at temperature conditions typical of those encountered at the surface of, e.g., Titan, and in accordance with recent experiments. Various compositions of the fluid in contact with the clathrate hydrate phase, i.e., various nitrogen/methane ratios, have been considered in the simulations. The results of these simulations reveal that, although the ratio between the number of enclathrated methane and that of nitrogen molecules strongly varies with the composition of the fluid phase, the clathrate hydrate lattice remains always selective for methane. This means that the relative proportion of methane with respect to nitrogen is always larger in the clathrate phase than in the fluid phase, with the mixed clathrate hydrate thus acting as a methane concentrator, irrespective of the fluid composition. These features indicate that the formation of clathrate hydrates can strongly influence the composition of the nitrogen–methane fluid phase, which may thus be impoverished in methane, as already inferred from the experimental results.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141984499","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":"MarSCoDe Martian Material Analysis Based on a PSO–SVR Approach","authors":"Xiong Wan*,&nbsp;Peipei Fang,&nbsp;Yian Wang,&nbsp;Yingjian Xin,&nbsp;Mingkang Duan,&nbsp;Hongpeng Wang,&nbsp;Xinru Yan,&nbsp;Chenhong Li,&nbsp;Yanhua Ma and Zhiping He*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0010010.1021/acsearthspacechem.4c00100","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00100https://doi.org/10.1021/acsearthspacechem.4c00100","url":null,"abstract":"<p >Laser-induced breakdown spectroscopy (LIBS) has been used for deep space exploration in recent years. The advantages of LIBS include high efficiency, stand-alone detection, and the ability to analyze multiple elements simultaneously. However, due to the fluctuation of laser energy, matrix effect, and instrumental noises, the quantitative prediction of LIBS instruments for planetary exploration is not satisfactory, especially for unknown targets. Therefore, comprehensive methods with higher adaptability and prediction accuracy must be developed to meet the needs of LIBS planetary material analysis. In this paper, we proposed an approach, which is mainly based on a particle swarm optimization (PSO)–support vector regression (SVR) analysis model, for material analysis of MarSCoDe, the LIBS payload of the Chinese Zhurong Mars rover. The model adopts a PSO algorithm to optimize the parameters and hence improve the prediction accuracy of traditional SVR equations. The training of the model was completed with 3600 LIBS spectra, which involved 60 standards and were obtained in the ground simulated Martian chamber before the launch of MarSCoDe. The quantitative performance of the model was evaluated by the coefficient of determination (<i>R</i>²) and root-mean-square error between real contents and predicted contents. Comparison with convolutional neural network and partial least squares showed that the PSO–SVR model has the highest prediction accuracy and the best robustness. After the launch, we used the LIBS spectra of the LC-005 calibration standard on a Zhurong rover to further evaluate the prediction accuracy of the model. The main element contents of LC-005 predicted by the model are basically consistent with its real contents. Since then, the model has been used in the onboard quantitative element analysis of MarSCoDe. Finally, quantitative analysis results of eight different unknown Martian targets on different Mars days are selected and shown, which reflects the main geological composition of the landing area of the Martian Utopia plain.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141984498","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":"Thermodynamics and Kinetics of Atmospherically Relevant Acetalization Reactions","authors":"Shira S. Presberg, Cara M. Waters, Sophie A. Lyon, Matthew J. Elrod","doi":"10.1021/acsearthspacechem.4c00136","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00136","url":null,"abstract":"Accretion reactions have been suggested as an important mechanism in the formation of low volatility secondary organic aerosol (SOA). Acetals are potential accretion products formed through the acid-catalyzed reactions of aldehydes and alcohols (both of which are ubiquitous in the atmosphere) via nucleophilic addition of alcohols to the aldehyde C═O bond. The thermodynamics and kinetics of the acetalization reaction mechanism for model aldehydes and polyols were examined with computational electronic structure methods and experimental bulk kinetics experiments using nuclear magnetic resonance (NMR) spectroscopy. The formation of all possible nucleophilic addition reaction products (hydrates, hemiacetals, acyclic acetals, and cyclic acetals) was found to be thermodynamically feasible under aqueous acidic conditions, a result at odds with an earlier computational study. Except for the formation of the thermodynamically most favored cyclic acetal products, the reactions occurred on a time scale shorter than the NMR experiment (lifetimes &lt;5 min). Polyols that could form both a 5- or 6-membered ring cyclic acetal product formed the 5-membered ring faster but exhibited interconversion to the 6-membered ring on the multihour lifetime scale. Reactions involving structurally different aldehydes and polyols were also examined, but both the thermodynamics and kinetics results depended only weakly on the carbon backbone of reactant aldehydes and polyols. Even the relatively slow cyclic acetal-forming reactions were found to have lifetimes &lt;1 day for pH 2.2 SOA acidities which are well within atmospherically relevant time scales. These thermodynamic and kinetic results indicate that acetalization reactions are a plausible accretion mechanism in SOA.","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141718498","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":"Thermodynamics and Kinetics of Atmospherically Relevant Acetalization Reactions","authors":"Shira S. Presberg,&nbsp;Cara M. Waters,&nbsp;Sophie A. Lyon and Matthew J. Elrod*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0013610.1021/acsearthspacechem.4c00136","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00136https://doi.org/10.1021/acsearthspacechem.4c00136","url":null,"abstract":"<p >Accretion reactions have been suggested as an important mechanism in the formation of low volatility secondary organic aerosol (SOA). Acetals are potential accretion products formed through the acid-catalyzed reactions of aldehydes and alcohols (both of which are ubiquitous in the atmosphere) via nucleophilic addition of alcohols to the aldehyde C═O bond. The thermodynamics and kinetics of the acetalization reaction mechanism for model aldehydes and polyols were examined with computational electronic structure methods and experimental bulk kinetics experiments using nuclear magnetic resonance (NMR) spectroscopy. The formation of all possible nucleophilic addition reaction products (hydrates, hemiacetals, acyclic acetals, and cyclic acetals) was found to be thermodynamically feasible under aqueous acidic conditions, a result at odds with an earlier computational study. Except for the formation of the thermodynamically most favored cyclic acetal products, the reactions occurred on a time scale shorter than the NMR experiment (lifetimes &lt;5 min). Polyols that could form both a 5- or 6-membered ring cyclic acetal product formed the 5-membered ring faster but exhibited interconversion to the 6-membered ring on the multihour lifetime scale. Reactions involving structurally different aldehydes and polyols were also examined, but both the thermodynamics and kinetics results depended only weakly on the carbon backbone of reactant aldehydes and polyols. Even the relatively slow cyclic acetal-forming reactions were found to have lifetimes &lt;1 day for pH 2.2 SOA acidities which are well within atmospherically relevant time scales. These thermodynamic and kinetic results indicate that acetalization reactions are a plausible accretion mechanism in SOA.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141984496","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":"Effects of Wind Speed on Size-Dependent Morphology and Composition of Sea Spray Aerosols","authors":"Chamika K. Madawala,&nbsp;Carolina Molina,&nbsp;Deborah Kim,&nbsp;Dilini Kirindigoda Gamage,&nbsp;Mengnan Sun,&nbsp;Raymond J. Leibensperger III,&nbsp;Lincoln Mehndiratta,&nbsp;Jennie Lee,&nbsp;Chathuri P. Kaluarachchi,&nbsp;Ke’La A. Kimble,&nbsp;Greg Sandstrom,&nbsp;Charbel Harb,&nbsp;Julie Dinasquet,&nbsp;Francesca Malfatti,&nbsp;Kimberly A. Prather,&nbsp;Grant B. Deane,&nbsp;M. Dale Stokes,&nbsp;Christopher Lee,&nbsp;Jonathan H. Slade,&nbsp;Elizabeth A. Stone,&nbsp;Vicki H. Grassian and Alexei V. Tivanski*,&nbsp;","doi":"10.1021/acsearthspacechem.4c0011910.1021/acsearthspacechem.4c00119","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00119https://doi.org/10.1021/acsearthspacechem.4c00119","url":null,"abstract":"<p >Variable wind speeds over the ocean can have a significant impact on the formation mechanism and physical-chemical properties of sea spray aerosols (SSA), which in turn influence their climate-relevant impacts. Herein, for the first time, we investigate the effects of wind speed on size-dependent morphology and composition of individual nascent SSA generated from wind-wave interactions of natural seawater within a wind-wave channel as a function of size and their particle-to-particle variability. Filter-based thermal optical analysis, atomic force microscopy (AFM), AFM infrared spectroscopy (AFM-IR), and scanning electron microscopy (SEM) were employed in this regard. This study focuses on SSA with sizes within 0.04–1.8 μm generated at two wind speeds: 10 m/s, representing a wind lull scenario over the ocean, and 19 m/s, indicative of the wind speeds encountered in stormy conditions. Filter-based measurements revealed a reduction of the organic mass fraction as the wind speed increases. AFM imaging at 20% relative humidity of individual SSA identified six main morphologies: prism-like, rounded, core–shell, rod, rod inclusion core–shell, and aggregates. At 10 m/s, most SSA were rounded, while at 19 m/s, core–shells became predominant. Based on AFM-IR, rounded SSA at both wind speeds had similar composition, mainly composed of aliphatic and oxygenated species, whereas the shells of core–shells displayed more oxygenated organics at 19 m/s and more aliphatic organics at 10 m/s. Collectively, our observations can be attributed to the disruption of the sea surface microlayer film structure at higher wind speeds. The findings reveal a significant impact of wind speed on morphology and composition of SSA, which should be accounted for accurate assessment of their climate effects.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsearthspacechem.4c00119","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141984365","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":"Effects of Wind Speed on Size-Dependent Morphology and Composition of Sea Spray Aerosols","authors":"Chamika K. Madawala, Carolina Molina, Deborah Kim, Dilini Kirindigoda Gamage, Mengnan Sun, Raymond J. Leibensperger, III, Lincoln Mehndiratta, Jennie Lee, Chathuri P. Kaluarachchi, Ke’La A. Kimble, Greg Sandstrom, Charbel Harb, Julie Dinasquet, Francesca Malfatti, Kimberly A. Prather, Grant B. Deane, M. Dale Stokes, Christopher Lee, Jonathan H. Slade, Elizabeth A. Stone, Vicki H. Grassian, Alexei V. Tivanski","doi":"10.1021/acsearthspacechem.4c00119","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.4c00119","url":null,"abstract":"Variable wind speeds over the ocean can have a significant impact on the formation mechanism and physical-chemical properties of sea spray aerosols (SSA), which in turn influence their climate-relevant impacts. Herein, for the first time, we investigate the effects of wind speed on size-dependent morphology and composition of individual nascent SSA generated from wind-wave interactions of natural seawater within a wind-wave channel as a function of size and their particle-to-particle variability. Filter-based thermal optical analysis, atomic force microscopy (AFM), AFM infrared spectroscopy (AFM-IR), and scanning electron microscopy (SEM) were employed in this regard. This study focuses on SSA with sizes within 0.04–1.8 μm generated at two wind speeds: 10 m/s, representing a wind lull scenario over the ocean, and 19 m/s, indicative of the wind speeds encountered in stormy conditions. Filter-based measurements revealed a reduction of the organic mass fraction as the wind speed increases. AFM imaging at 20% relative humidity of individual SSA identified six main morphologies: prism-like, rounded, core–shell, rod, rod inclusion core–shell, and aggregates. At 10 m/s, most SSA were rounded, while at 19 m/s, core–shells became predominant. Based on AFM-IR, rounded SSA at both wind speeds had similar composition, mainly composed of aliphatic and oxygenated species, whereas the shells of core–shells displayed more oxygenated organics at 19 m/s and more aliphatic organics at 10 m/s. Collectively, our observations can be attributed to the disruption of the sea surface microlayer film structure at higher wind speeds. The findings reveal a significant impact of wind speed on morphology and composition of SSA, which should be accounted for accurate assessment of their climate effects.","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141718499","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":"Sources of Particulate Bound Mercury in the Northwest Pacific Constrained by Hg Isotopes","authors":"Shuyuan Huang, Yunlong Huo, Heng Sun, Supeng Lv, Yuhan Zhao, Kunning Lin, Yaojin Chen, Yuanbiao Zhang","doi":"10.1021/acsearthspacechem.3c00365","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.3c00365","url":null,"abstract":"Atmospheric mercury (Hg) transport and transformation controls the global Hg budget. Of which, the particulate-bound mercury (PBM) sources and subsequent deposition are crucial, especially in the open ocean. Here, we present the first Hg isotope compositions of PBM in the Northwest Pacific during three cruises from 2018 to 2019. The PBM samples were less influenced by long-range transport of anthropogenic emissions according to the low PBM concentrations (19.7 ± 10.9, <i>n</i> = 52, 1SD). The mass-independent fractionation signatures are mainly controlled by photochemical reactions as the ratio of Δ¹⁹⁹Hg/Δ²⁰¹Hg was close to 1.0. The <i>in situ</i> Hg oxidation of Br radicals plays an important role in keeping PBM Δ²⁰⁰Hg values lower, while the background atmospheric Hg(II) pool, which is derived from Hg oxidation by O₂ in the free troposphere, provides highly positive Δ²⁰⁰Hg values for PBM. The common photoredox reactions and subsequent adsorption adjust the PBM isotopic composition within a moderate range. We used an isotope mixing model to estimate the contributions of each factor. Compared with PBM in other areas (e.g., urban, high-altitude), contributions from photochemical oxidation increased in the marine boundary layer of the open ocean. The results of this study have improved our understanding of the transport pathways of PBM in the atmosphere and highlighted the important use of Hg isotopes in process analysis and source tracing.","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141610815","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":"Sources of Particulate Bound Mercury in the Northwest Pacific Constrained by Hg Isotopes","authors":"Shuyuan Huang,&nbsp;Yunlong Huo,&nbsp;Heng Sun,&nbsp;Supeng Lv,&nbsp;Yuhan Zhao,&nbsp;Kunning Lin,&nbsp;Yaojin Chen and Yuanbiao Zhang*,&nbsp;","doi":"10.1021/acsearthspacechem.3c0036510.1021/acsearthspacechem.3c00365","DOIUrl":"https://doi.org/10.1021/acsearthspacechem.3c00365https://doi.org/10.1021/acsearthspacechem.3c00365","url":null,"abstract":"<p >Atmospheric mercury (Hg) transport and transformation controls the global Hg budget. Of which, the particulate-bound mercury (PBM) sources and subsequent deposition are crucial, especially in the open ocean. Here, we present the first Hg isotope compositions of PBM in the Northwest Pacific during three cruises from 2018 to 2019. The PBM samples were less influenced by long-range transport of anthropogenic emissions according to the low PBM concentrations (19.7 ± 10.9, <i>n</i> = 52, 1SD). The mass-independent fractionation signatures are mainly controlled by photochemical reactions as the ratio of Δ¹⁹⁹Hg/Δ²⁰¹Hg was close to 1.0. The <i>in situ</i> Hg oxidation of Br radicals plays an important role in keeping PBM Δ²⁰⁰Hg values lower, while the background atmospheric Hg(II) pool, which is derived from Hg oxidation by O₂ in the free troposphere, provides highly positive Δ²⁰⁰Hg values for PBM. The common photoredox reactions and subsequent adsorption adjust the PBM isotopic composition within a moderate range. We used an isotope mixing model to estimate the contributions of each factor. Compared with PBM in other areas (e.g., urban, high-altitude), contributions from photochemical oxidation increased in the marine boundary layer of the open ocean. The results of this study have improved our understanding of the transport pathways of PBM in the atmosphere and highlighted the important use of Hg isotopes in process analysis and source tracing.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141984364","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}