Environmental science: atmospheres最新文献

{"title":"Characterising changes in the methane response of a semiconductor-based metal oxide sensor over time","authors":"Adil Shah, Olivier Laurent, Grégoire Broquet, Clément Romand and Philippe Ciais","doi":"10.1039/D5EA00046G","DOIUrl":"https://doi.org/10.1039/D5EA00046G","url":null,"abstract":"<p >The semiconductor-based Figaro Taguchi Gas Sensor (TGS) is sensitive to reducing gases, including methane. TGS methane response can be characterised by using the ratio between resistance in the presence of methane mole fraction ([CH<small>₄</small>]) enhancements and a reference resistance, representative of sampling under the same environmental conditions and with the same background gas composition, but at a reference [CH<small>₄</small>] level. Effects of environmental variables, including water mole fraction ([H<small>₂</small>O]), are expected to cancel in this resistance ratio, allowing for independent [CH<small>₄</small>] characterisation. This work seeks to examine the cause of changes in [CH<small>₄</small>] resistance ratio characterisation over time, including the hypothesis that resistance ratios are independent of [H<small>₂</small>O]. Precise gas blends were sampled under controlled conditions during sensor characterisation in synthetic air (SCS) tests, which showed [H<small>₂</small>O] to influence resistance ratio methane characterisation, although this effect's importance depends on the reference gas. Three SCS tests were also performed with gaps of 137 days followed by 295 days, all under similar environmental conditions and gas blends. [CH<small>₄</small>] resistance ratio response changed significantly during the first time gap, suggesting that something inherently changed sensor behaviour, but negligibly during the second time gap, suggesting that natural ageing is not otherwise a key driver of sensor behaviour. Additional SCS tests showed persistent changes in [CH<small>₄</small>] resistance ratio response following hydrogen sulphide exposure; this may have caused a change between controlled SCS tests conducted 137 days apart, although other atmospheric species may also have been responsible. This is an important consideration for laboratory testing and final sensor application. Meanwhile, power loss and sampling dry air negligibly affected a different TGS. In addition, a total of 147 successful sensor characterisation in ambient air (SCA) tests occurred irregularly over approximately 25 months, where small amounts of gas with a high [CH<small>₄</small>] were blended with ambient outdoor air. SCA tests showed a weaker correlation between time and [CH<small>₄</small>] response when restricted to the period covering the second (295-day) time window between the similar SCS tests. A residual observed SCA testing correlation with time could be attributed to changes in [H<small>₂</small>O] over time, supporting SCS testing conclusions.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 10","pages":" 1119-1143"},"PeriodicalIF":3.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/ea/d5ea00046g?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An unsupervised machine learning approach for indoor air pollution analysis","authors":"Bárbara A. Macías-Hernández, Edgar Tello-Leal, Jailene Marlen Jaramillo-Perez and René Ventura-Houle","doi":"10.1039/D5EA00051C","DOIUrl":"https://doi.org/10.1039/D5EA00051C","url":null,"abstract":"<p >Exposure to indoor air pollutants is one of the most significant environmental and health risks people face, especially since they spend most of their time indoors. Therefore, evaluating indoor air pollution levels and comfort parameters is essential for achieving sustainable indoor air quality (IAQ). The main objective of this study was to identify patterns of indoor air pollution in two buildings with different characteristics located on a university campus in northeastern Mexico. We measured the concentration of particulate matter in fractions of 1.0 μm (PM<small>₁</small>), 2.5 μm (PM<small>_2.5</small>), and 10 μm (PM<small>₁₀</small>), as well as carbon dioxide (CO<small>₂</small>), carbon monoxide (CO), and ozone (O<small>₃</small>), along with the temperature and relative humidity in each microenvironment during the working hours of spring, summer, and autumn. Next, unsupervised machine learning was employed to identify behavioral patterns of air pollutants within the microenvironments. The <em>K</em>-means clustering algorithm was used to identify homogeneous microenvironments within the study area. We performed three clustering analyses per building: (1) considering all the variables in the dataset, (2)selecting the significant variables through principal component analysis (PCA), and (3) examining two time ranges within the working day. The robustness of the proposed approach was evaluated through a comparative analysis of the <em>K</em>-means, DBScan, and hierarchical algorithms, assessing their performance using the Davies–Bouldin index and Silhouette score metrics. Furthermore, the stability of the clusters over time intervals was assessed using the adjusted Rand index. Cluster analysis enabled us to identify microenvironments with maximum similarity and those that change groups, as their behavior depends on the time range. Consequently, grouping microenvironments into homogeneous IAQ classes is effective in accurately identifying spaces based on patterns related to their contamination levels and guiding actions to reduce pollution levels by zone or building.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 10","pages":" 1144-1157"},"PeriodicalIF":3.5,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/ea/d5ea00051c?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiphase reaction of nitrate radicals with vanillic acid aerosols: kinetics and formation of light-absorbing particles","authors":"Laura-Helena Rivellini, Carolyn Liu-Kang and Jonathan P. D. Abbatt","doi":"10.1039/D5EA00066A","DOIUrl":"https://doi.org/10.1039/D5EA00066A","url":null,"abstract":"<p >Given that biomass-burning aerosol emissions have a direct radiative effect on the atmosphere, it is important to understand the chemistry that occurs within wildfire smoke that may change aerosol particle optical properties. To investigate night-time aging chemistry, this laboratory study explores the kinetics of the reaction between gas-phase nitrate radicals (NO<small>₃</small>) and vanillic acid (VA), a functionalized phenol. As breakdown products of lignin, phenolic compounds are the commonly observed components of biomass burning smoke. They are also present in urban air pollution, formed by the oxidation of aromatic precursors. The study was conducted in an aerosol flow tube with a residence time of 15 minutes, where roughly 1.6 pptv of NO<small>₃</small> was formed by the reaction of NO<small>₂</small> (21 ppbv) and O<small>₃</small> (230 ppbv), and VA/ammonium sulfate (AS) solutions were atomized to form particles in the accumulation mode size range. The reaction was monitored by an aerosol mass spectrometer (AMS), which measured nitrated aerosol products, and by a 5-wavelength aethalometer, which observed the optical absorption of aerosol particles. The observed gas-surface kinetics are consistent with a NO<small>₃</small> reactive uptake coefficient to form a nitrated product of 0.30 ± 0.39 and 0.19 ± 0.12 at respectively RH = 25% ± 5% and 55% ± 5% at 296 K. The aerosol particles became highly absorbing during the reaction in the near ultraviolet (375 nm) and visible (470, 528, and 625 nm) regions. While this change in absorptivity presumably arises <em>via</em> the nitration of the aromatic ring, the reaction drives stronger particle absorption, which extends much more deeply into the visible part of the spectrum than is characteristic of (mono) nitrovanillic acid (NVA), indicative of the formation of complex reaction products. These results demonstrate that night-time atmospheric aging of phenol-containing wildfire smoke and urban particulates will occur rapidly and significantly darken the particles throughout the visible part of the spectrum.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 10","pages":" 1099-1109"},"PeriodicalIF":3.5,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/ea/d5ea00066a?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Size-resolved cloud droplet acidity over the US","authors":"Stylianos Kakavas, Georgios Siderakis and Spyros N. Pandis","doi":"10.1039/D5EA00067J","DOIUrl":"https://doi.org/10.1039/D5EA00067J","url":null,"abstract":"<p >The acidity of cloud droplets can vary with size due to differences in aerosol composition and cloud chemistry and differential soluble gas uptake. Chemical transport models (CTMs) often assume that all droplets have the same composition and therefore acidity. In this work, we use the PMCAMx CTM to simulate size-resolved cloud and fog droplet acidity over the US during a winter and a summer month as a function of altitude. Small droplets are assumed to form on the activated particles smaller than 2.5 μm and have an average diameter of 20 μm, whereas large droplets form on the coarse particles and have an average diameter of 30 μm. Our simulations show that large droplets are often more alkaline than small (up to 100% lower H<small>⁺</small> concentrations) especially in regions influenced by dust. In areas with more acidic conditions, the difference in H<small>⁺</small> concentrations between small and large droplets is smaller. The pH of droplets either decreases or increases with altitude, depending on the composition of the aerosol on which the droplets were formed. Comparison of the bulk and two-section size-resolved approaches indicates that current differences in aqueous-phase sulfate concentrations over the US are generally low and usually less than 20% at approximately 10 min intervals (the most frequent difference ranges from zero to 5%). Based on our results, bulk calculations can simulate current aerosol composition and droplet pH over the US with small discrepancies. This is due to reduced SO<small>₂</small> emissions causing SO<small>₂</small> levels in clouds to often fall below those of H<small>₂</small>O<small>₂</small>. Under these conditions the importance of the pH-dependent ozone sulfate production pathway is diminished. These findings are specific to the US and may not apply to regions with higher SO<small>₂</small> emissions.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 10","pages":" 1110-1118"},"PeriodicalIF":3.5,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/ea/d5ea00067j?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hot and dry conditions elevate grass pollen and sub-pollen particle concentrations in Melbourne, Australia","authors":"C. B. A. Mampage, K. M. Emmerson, E. R. Lampugnani, R. Schofield and E. A. Stone","doi":"10.1039/D5EA00024F","DOIUrl":"10.1039/D5EA00024F","url":null,"abstract":"<p >A Wideband Integrated Bioaerosol Sensor (WIBS) was used in conjunction with chemical tracer analysis for the first time during the 2022–2023 grass pollen season in Melbourne, Australia. WIBS detected continuous levels of bioaerosol throughout the campaign. From 18th November to 7th December 2022, fluorescent particles accounted for an average of 10% of total particles in number, corresponding to an estimated 0.18 μg m<small>⁻³</small> PM<small>_2.5</small> (14%) and 0.49 μg m<small>⁻³</small> PM<small>₁₀</small> (25%). Using mannitol as a chemical tracer, fungal spores were estimated to contribute to an average of 2% of PM<small>_2.5</small> and 9% of PM<small>₁₀</small> mass. Analysis of fructose in PM<small>_2.5</small> as a marker for sub-pollen particles (SPPs) showed elevated concentrations during periods of hot and dry weather. There was negligible fructose observed with rain, suggesting that SPP production is not limited to water absorption processes or high relative humidity in Melbourne. Estimates of SPP mass <em>via</em> fructose corresponded to the equivalent of 1.1 m<small>⁻³</small> intact pollen grains on average, 2% of the total pollen concentration, 7% of PM<small>_2.5</small> fluorescent particle mass, and 1% of PM<small>_2.5</small> mass. New hourly measured grass pollen data confirmed the timing and magnitude of grass pollen emissions in the Victorian Grass Pollen Emission Model (VGPEM) and captured the strong diurnal variation. Five grass pollen rupturing mechanisms using different meteorological drivers were tested against the WIBS and fructose measurements. Whilst the WIBS and model were not well correlated, likely due to the complex mixture of bioaerosols and low relative abundance of SPPs, the mechanical wind speed rupturing mechanism represented the fructose time series well. Conceptually, this suggests that mechanical rupturing describes SPP formation during hot and dry conditions in Melbourne. Long-term measurements in Melbourne will improve SPP formation process forecasting.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 10","pages":" 1081-1098"},"PeriodicalIF":3.5,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12396348/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144981000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Environmental health hazards attributed to deteriorated indoor air quality caused by inferior construction practices","authors":"Atun Roy Choudhury, Neha Singh, Sumanth Chinthala, Jitesh Lalwani, Sri Kalyana Rama J., Chandana N., Sankar Ganesh Palani, Mohammad Mehdizadeh, V. Vinayaka Ram and Azam Akhbari","doi":"10.1039/D5EA00027K","DOIUrl":"https://doi.org/10.1039/D5EA00027K","url":null,"abstract":"<p >Accounting for nearly 5% of the global gross domestic product, the construction industry significantly contributes to environmental pollution, emitting a broad range of hazardous pollutants, including particulate matter (PM<small>₁₀</small>, PM<small>_2.5</small>), carbon monoxide (CO), nitrogen oxides (NO<small>_<em>x</em></small>), volatile organic compounds (VOCs), benzene and polycyclic aromatic hydrocarbons (PAHs). Individuals spend approximately 90% of their time indoors, where the air quality is heavily influenced by construction and demolition (C&amp;D) activities that are carried out within or adjacent to residences. Despite regulatory interventions in the early 21st century emphasizing the importance of indoor air quality (IAQ), the contribution of C&amp;D activities to indoor pollution remains largely underexplored, particularly to seasonal variations, extended renovation periods, and the release of case-specific pollutants. This review bridges knowledge gaps by examining the correlation between construction activities, pollutant emissions, health risks, and the efficacy of existing regulations. Key investigations include the impact of infrastructural inefficiencies and improper ventilation on IAQ, seasonal pollutant variations, and the disproportionate exposure risks faced by vulnerable populations, such as women and workers. The literature suggests that prolonged exposure prompts sick-building syndrome and ailments such as compromised immunity, bronchial allergy, asthma, and lung cancer. A survey-based data collection and analysis were conducted to gather and refine residents' practical insights across India, contributing to the development of an IAQ index. This tailored index, ranging from 22 to 100, is designed for indoor environments, incorporating building-specific and occupancy-related factors. In the long term, the index can provide actionable insights for administrators and communities to mitigate IAQ risks effectively, promoting healthier indoor environments by providing a quantitative measure of the health risks associated with exposure to poor indoor air quality in the absence of a pollutant dataset. The study enables individual households to take measures to retrofit indoor spaces by upgrading to better-quality materials or modifying the design of the building to reduce health risks and improve air exchange.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 9","pages":" 941-961"},"PeriodicalIF":3.5,"publicationDate":"2025-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/ea/d5ea00027k?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145028055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Airborne cloud water pH measurements in diverse regions: statistics and relationships with constituents","authors":"Kayla M. Preisler, Ewan C. Crosbie, Miguel Ricardo A. Hilario, Grace Betito, Rachel A. Braun, Andrea F. Corral, Eva-Lou Edwards, Alexander B. MacDonald, Ali Hossein Mardi, Michael A. Shook, Connor Stahl, Edward L. Winstead, Kira Zeider, Luke D. Ziemba and Armin Sorooshian","doi":"10.1039/D5EA00070J","DOIUrl":"https://doi.org/10.1039/D5EA00070J","url":null,"abstract":"<p >Airborne cloud water measurements are examined in this study, with a focus on pH and interrelationships with influential species for three regions: the Northwest Atlantic (winter and summer 2020–2022), the West Pacific (summer 2019), and the Northeast Pacific (summers between 2011 and 2019). Northwest Atlantic results are categorized into three ways: data closer to the U.S. east coast for (i) winter, (ii) summer, and (iii) summertime measurements over Bermuda. The median pHs are as follows: Northwest Atlantic winter/summer = 4.83/4.96, Bermuda = 4.74, West Pacific = 5.17, and Northeast Pacific = 4.40. The regions exhibit median pH values of ∼4–6 across various altitude bins reaching as high as 6.8 km, with the overall minimum and maximum values being 2.92 and 7.58, respectively (both for the Northeast Pacific). Principal component analysis of species to predict pH shows that the most influential principal component is anthropogenic in nature. Machine leaning modeling suggests that the most effective combination of species to predict pH includes some subset of oxalate, non-sea salt Ca<small>²⁺</small>, NO<small>₃</small><small>⁻</small>, non-sea salt SO<small>₄</small><small>²⁻</small>, and methanesulfonate. These results demonstrate that cloud water acidity is relatively well constrained between a pH of 4 and 5.5 and that anthropogenic activities impact regional cloud water pH in the areas examined, with dust offsetting acidity at times.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 10","pages":" 1158-1172"},"PeriodicalIF":3.5,"publicationDate":"2025-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/ea/d5ea00070j?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effervescent nozzle design to enable outdoor marine cloud brightening experimentation","authors":"Luke P. Harrison, Chris Medcraft and Daniel P. Harrison","doi":"10.1039/D5EA00073D","DOIUrl":"https://doi.org/10.1039/D5EA00073D","url":null,"abstract":"<p >Marine Cloud Brightening (MCB) is a proposed solar radiation management technique whereby the albedo of low-lying clouds is artificially enhanced by the addition of Cloud Condensation Nuclei (CCN). It is generally accepted that these would be produced by atomisation of seawater to produce droplets which form appropriately sized artificial sea spray aerosol (SSA). Despite extensive theoretical consideration of the MCB concept, progress in understanding how perturbations to complex cloud microphysical processes would evolve has been hampered by the technical inability to produce the very large numbers of SSA required. To facilitate the first phase of outdoor experimentation a single MCB station should be capable of producing around 10<small>¹⁵</small> per s CCN. Effervescent nozzle technology has been posited as potentially capable of meeting these requirements. Here we describe an effervescent nozzle design that produces ∼1.73 × 10<small>¹²</small> per s SSA, with ∼71% of aerosols within a 30 to 1000 nm range (considered likely CCN), using ∼512 W of energy per nozzle. Producing 10<small>¹⁵</small> CCN using this design would then require 814 nozzles and around 417 kW of energy, a demand that can be practically met on a research vessel. The nozzle described here is therefore sufficiently practical to facilitate outdoor <em>in situ</em> experimentation of MCB, enabling a new generation of perturbation experiments that directly probe cloud microphysical and radiative responses to aerosol.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 10","pages":" 1071-1080"},"PeriodicalIF":3.5,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/ea/d5ea00073d?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Emission speciation of volatile and intermediate volatility organic compounds from a marine engine: effect of engine load, fuel type and photochemical aging","authors":"Deeksha Shukla, Hendryk Czech, Tuukka Kokkola, Martin Bauer, Andreas Paul, Uwe Etzien, Mika Ihalainen, Zheng Fang, Anni Hartikainen, Nadine Gawlitta, Thorsten Hohaus, Yinon Rudich, Thorsten Streibel, Bert Buchholz, Olli Sippula, Johan Øvrevik, Jürgen Schnelle-Kreis and Ralf Zimmermann","doi":"10.1039/D5EA00040H","DOIUrl":"https://doi.org/10.1039/D5EA00040H","url":null,"abstract":"<p >The enforcement of global fuel sulfur content (FSC) regulations has significantly reduced SO<small>₂</small> and particulate matter (PM) emissions from ships. However, the impact of the International Maritime Organization's (IMO) sulfur reduction policy on gaseous hydrocarbon emissions, including volatile and intermediate volatility organic compounds (VOCs/IVOCs), remains underexplored. In this study, a 4-stroke single cylinder marine engine was operated using marine gas oil (MGO, FSC = 0.01%) and low-sulfur heavy fuel oil (LS-HFO, FSC = 0.5%) across various engine loads, ranging from 20 kW to a maximum of 80 kW. Emissions were photochemically aged in the oxidation flow reactor “PEAR,” simulating an equivalent photochemical aging period from 1.4 ± 0.2 to 4.6 ± 0.8 days related to the OH· exposure. Emission factors (EFs) of all targeted VOCs/IVOCs varied significantly, ranging from 20.0 ± 2.5 to 180 ± 20 mg kWh<small>⁻¹</small> and from 26.0 ± 11.0 to 280 ± 100 mg kWh<small>⁻¹</small> from a high (80 kW) to low engine load (20 kW) for MGO and LS-HFO, respectively. Monoaromatics dominated total fresh emissions for MGO (64%) and LS-HFO (76%), followed by alkanes. Naphthalene and alkylated naphthalene content declined more than monoaromatic and alkane content, thus changing the VOC/IVOC emission pattern after photochemical aging. Estimated SOA from targeted VOC/IVOC precursors accounted for 41% of the measured secondary organic aerosol (SOA) for MGO, while a lower contribution (34%) was observed for LS-HFO at 20 kW engine load, highlighting the role of unmeasured VOCs/IVOCs in SOA formation. Expanding the research on the effects of atmospheric aging on marine emissions will offer valuable insights into this underexplored area.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 9","pages":" 973-986"},"PeriodicalIF":3.5,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/ea/d5ea00040h?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145028057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimizing stratospheric aerosol lifetime and albedo through particle morphology and refractive index","authors":"Benjamin Vennes, Alison Bain, James F. Davies and Thomas C. Preston","doi":"10.1039/D5EA00026B","DOIUrl":"https://doi.org/10.1039/D5EA00026B","url":null,"abstract":"<p >Stratospheric aerosol injection (SAI) has been proposed as a geoengineering approach to temporarily offset global warming by increasing Earth's albedo. Here, we utilize light scattering calculations to examine how introducing solid aerosol particles into the stratosphere can enhance the Bond albedo, a key metric linking reflectivity directly to radiative forcing. We explore how particle size, refractive index (both real and imaginary components), and morphology (core–shell configurations) affect single scattering albedo, phase function, and the resulting integrated solar reflectivity. Our results show how the optimal aerosol size is governed by matching the wavelength of dipolar resonances with the peak of incoming solar spectral irradiance. We also examine how dispersion, absorption, and size distribution affect the extent of the Bond albedo enhancement and radiative forcing. Coated particles are also studied, and we find that very thin lower-index coatings can spoil albedo enhancement (<em>e.g.</em>, layers of water or sulfuric acid that are only a few nanometres thick). Conversely, designing core–shell particles with a thin, higher-index shell and a low-density core can retain high reflectivity while substantially reducing particle mass and settling velocity, potentially extending the stratospheric residence time. The framework discussed here is versatile, readily extending to systems beyond homogeneous spherical particles, and it provides a straightforward means of comparing candidate SAI materials while guiding future laboratory studies, work on particle design, field experiments, and climate model parameterizations to assess the viability and risks of stratospheric aerosol geoengineering.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 9","pages":" 998-1013"},"PeriodicalIF":3.5,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/ea/d5ea00026b?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145028059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}