Atmospheric Environment最新文献

{"title":"A review of measurements and model simulations of atmospheric nitrous acid","authors":"Like Wang ,&nbsp;Jiajue Chai ,&nbsp;Benjamin Gaubert ,&nbsp;Yaoxian Huang","doi":"10.1016/j.atmosenv.2025.121094","DOIUrl":"10.1016/j.atmosenv.2025.121094","url":null,"abstract":"<div><div>Ambient nitrous acid (HONO) plays a crucial role in the atmosphere's oxidative capacity, significantly impacting air quality and climate. This study reviews the current understanding of HONO formation mechanisms, including in-situ and vertical gradient measurements, as well as the temporal, spatial, and vertical characteristics of HONO and its modeling approaches. HONO concentrations exhibit significant diurnal variation based on sources and sinks in different environments. Typically, concentrations are higher near the ground and decrease with altitude. Additionally, this study examines the incorporation of contemporary HONO chemical mechanisms into box models, regional and global chemical transport models (CTMs), and chemistry-climate models. Models often underestimate observations due to uncertainties in heterogeneous HONO formation and varying measurement techniques. Finally, this review identifies key challenges for future HONO measurements and modeling efforts. Significant opportunities remain to enhance our fundamental understanding of HONO. Precision and accuracy are important for advancing HONO observation measurement techniques. Simultaneously, the representation of HONO in state-of-the-art models helps us better quantify atmospheric oxidation capacity and air quality impacts.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"347 ","pages":"Article 121094"},"PeriodicalIF":4.2,"publicationDate":"2025-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Validation of multi-model decadal simulations of present-day central European air-quality","authors":"Alvaro Patricio Prieto Perez,&nbsp;Peter Huszár,&nbsp;Jan Karlický","doi":"10.1016/j.atmosenv.2025.121077","DOIUrl":"10.1016/j.atmosenv.2025.121077","url":null,"abstract":"<div><div>Although air quality has improved in Europe, most of its population is still exposed to levels of pollutants that are harmful to health, such as nitrogen dioxide (NO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>) or sulphur dioxide (SO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>). Studying the processes that drive atmospheric chemistry is key to understanding their contribution to air quality. However, since many pollutants are secondary, since meteorology influences the chemical evolution of pollutants, disperses them and transport them and their precursors, among other factors, this task is extremely difficult. This makes thus the use of models essential for the study of air quality. In this work, we present the first long-term validation of air quality simulations in Central Europe for the 2010–2019 decade. The simulations were carried out using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) and the Comprehensive Air Quality Model with Extensions (CAMx). Using the AirBase dataset, stations inside the model domain were classified into three categories according to their pollution burden, and the validation of the models was performed independently in each group. Our research shows that, generally, simulations underestimate pollutant concentrations – except ozone (O<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>) – most likely because of an incorrect monthly and hourly emissions profile and an overestimation of vertical mixing.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"349 ","pages":"Article 121077"},"PeriodicalIF":4.2,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143549748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on global atmospheric aerosol type identification from combined satellite and ground observations","authors":"Xin Nie ,&nbsp;Leyi Yu ,&nbsp;Qianjun Mao ,&nbsp;Xiaoyan Zhang","doi":"10.1016/j.atmosenv.2025.121100","DOIUrl":"10.1016/j.atmosenv.2025.121100","url":null,"abstract":"<div><div>Accurate identification of aerosol types is essential for understanding the radiative properties of aerosols and further studying aerosol regional and global climate effects. However, aerosol type identification studies combining satellite and ground observations are rare. In this paper, an aerosol type identification model based on aerosol relative optical depth (AROD) and volume depolarization ratio (VDR) is developed by effectively matching satellite and ground observation data. The accuracy and applicability of the new model are verified by typical AERONET sites with dominant aerosols, and the spatial distribution characteristics of aerosol types in global continents are also studied and analyzed with joint observation data from 2018 to 2023 globally. The results show that the East Asian continent, North America, and Europe are the main source regions for continental aerosol emissions. Among the continents, densely populated East/Southeast Asia is more heavily polluted by anthropogenic aerosols than other continents, while North America and Europe are relatively less polluted. The Indo-China Peninsula, central and southern Africa, central South America, and central and northern North America are the main source emission regions of global biomass burning aerosol, while northern Africa, West Asia, and Central Asia emit most of the global dust and polluted dust aerosols. Additionally, marine aerosols are more frequent along the east coast of North America, the west coast of Africa, the Malay Archipelago, and some island sites. The present study provides a basis for aerosol type identification using joint observation data and effectively promotes research in related fields.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"347 ","pages":"Article 121100"},"PeriodicalIF":4.2,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The impact of sky conditions on gross primary production and methane flux from different rice paddies","authors":"Tingting Zhu ,&nbsp;Yanlian Zhou ,&nbsp;Weimin Ju","doi":"10.1016/j.atmosenv.2025.121098","DOIUrl":"10.1016/j.atmosenv.2025.121098","url":null,"abstract":"<div><div>The increase of diffuse radiation fraction has been reported to greatly impact carbon uptake in agroecosystems. However, it is unclear how radiation components affected methane (CH₄) emission. Based on eddy covariance measurement from six sites, the effects of sky conditions on gross primary productivity (GPP) and CH₄ emission were investigated at half-hourly and daily scales. The results showed diurnal patterns of GPP were similar under all sky conditions, while CH₄ emission displayed irregular unimodal curves with greater fluctuations under different sky conditions. GPP responded to the changing radiation more efficiently under overcast conditions than under sunny conditions, whereas CH₄ emission under sunny conditions was higher at the same radiation levels. Parameters describing GPP and CH₄ emission varied across sites and sky conditions. The maximum photosynthetic rate and CH₄ rate at turning point under cloudy and overcast skies were lower than those under sunny conditions. The values of initial light use efficiency from GPP and CH₄ emission were opposite with the increase of diffuse radiation fraction, respectively. Soil moisture, temperature (Ta), vapor pressure deficit, direct, and diffuse radiation (<em>R</em>_dif) were responsible for the variations of GPP and CH₄ emission under different skies, CH₄ emission depended heavily on GPP and Ta under the inhibition of <em>R</em>_dif. This study implies that the direct effects of sky conditions on GPP were greater than those on CH₄ emission and should be paid more attention in ecosystem carbon cycle models.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"346 ","pages":"Article 121098"},"PeriodicalIF":4.2,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143378405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"African dust particles over the western Caribbean: Chemical characterization","authors":"Daniel Rosas ,&nbsp;Ma Montserrat Silva ,&nbsp;Bernardo Figueroa ,&nbsp;Ofelia Morton-Bermea ,&nbsp;Javier Miranda ,&nbsp;Harry Alvarez ,&nbsp;Teresa Pi Puig ,&nbsp;Javier Morales ,&nbsp;Jorge Uuh ,&nbsp;Elizabeth Hernández-Alvarez ,&nbsp;Salett Novelo ,&nbsp;Jessica Olivares ,&nbsp;Dara Salcedo ,&nbsp;Irma Rosas ,&nbsp;Carmen Ponce ,&nbsp;Graciela B. Raga ,&nbsp;Luis A. Ladino","doi":"10.1016/j.atmosenv.2025.121095","DOIUrl":"10.1016/j.atmosenv.2025.121095","url":null,"abstract":"<div><div>African dust (AD) plays a key role in atmospheric and biogeochemical processes across various ecosystems, yet its impact in Mexico, particularly in the Yucatan Peninsula (YP), remains understudied. This study chemically characterized AD transported to the YP during the massive “Godzilla” event in June 2020 and subsequent intrusions in 2021. The objective was to describe the chemical composition of dust, trace its origins, and assess its influence on atmospheric particles at three sites: Cozumel, Mérida, and Sisal. Aerosol samples were collected using PM₁₀ and PM_2.5 samplers and analyzed via Inductively Coupled Plasma-Mass Spectroscopy, X-ray fluorescence, and ion chromatography. Satellite imagery and air mass trajectories were used to identify periods with AD transport. Descriptive statistics and hierarchical clustering were used to identify intrusion periods and group samples based on their chemical compositions. Our results showed that PM₁₀ concentrations during AD events increased up to 20 times compared to baseline levels. Among the analyzed elements, Al, Fe, Ca, and Si were the most abundant. Enrichment of ionic species like SO₄²⁻ and NO₃⁻ was attributed to marine sources and local emissions. Correlation analysis and rare earth element clustering confirmed the African origin of the dust, primarily from Morocco and northern Algeria and Mali (Sahara region), with evidence of particle dilution as the dust traveled across the YP. These findings emphasize the significant role of AD intrusions in altering the aerosol chemical composition in the YP, contributing to a better understanding of dust and element transport mechanisms and their atmospheric and biogeochemical impacts in the region.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"347 ","pages":"Article 121095"},"PeriodicalIF":4.2,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pollution characteristics and health risks of size-resolved particulate-bound polycyclic aromatic compounds in Zhengzhou","authors":"Junmei Zhang ,&nbsp;Zhiyu Wang ,&nbsp;Yuhang Wei ,&nbsp;Shushen Yang ,&nbsp;Xiaoyan Song ,&nbsp;Sen Yao ,&nbsp;Lingxiao Yang","doi":"10.1016/j.atmosenv.2025.121099","DOIUrl":"10.1016/j.atmosenv.2025.121099","url":null,"abstract":"<div><div>Size-segregated particulate samples were collected from a megacity in Central China during four different seasons to determine the concentrations of polycyclic aromatic compounds (PACs), explore their size distributions, and evaluate their health risks. The annual average concentrations of Σ₁₇PAHs (polycyclic aromatic hydrocarbons), Σ₇NPAHs, and Σ₆OPAHs (nitrated and oxygenated PAHs) were 22.0 ng m⁻³, 0.59 ng m⁻³, and 4.65 ng m⁻³, respectively, which all exhibited significantly seasonal variations with peak values in winter. Five-to seven-ring PAHs were dominant, explaining 47.0%–63.5% of the Σ₁₇PAHs, with BbF being the most important component across the four different seasons. (2 + 3)-NFLT and 9,10-ATQ were the most abundant NPAHs and OPAHs, respectively. More than 60% of the PACs masses were enriched in fine particles (aerodynamic diameter (D_p) &lt; 2.1 μm), and the mass median diameters (MMDs) of PACs were much less than 2.1 μm. The main sources of PACs identified by diagnostic ratios and principal component analysis (PCA) were coal/biomass combustion, vehicular exhaust emission, and secondary generation. Inhalation exposure assessment revealed that the annual average deposition efficiency of PACs was 48.2%, with PACs mainly deposited in the head airway (36.7%). The inhalation exposure pathway was more significant than the dermal absorption exposure pathway, whereas the incremental lifetime cancer risk (ILCR) for inhalation exposure (ILCR_inh) was slightly lower than the ILCR for dermal absorption exposure (ILCR_derm). The PACs in the fine particles (D_p &lt; 2.1 μm) contributed more than half of the ILCR_inh values, but the coarse particles (D_p &gt; 3.3 μm) contributed more than 76.2% of the ILCR_derm values. The total ILCR, including the ILCR_inh and ILCR_derm for adults, exceeded the acceptable limit of 10⁻⁶ set by the USEPA.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"346 ","pages":"Article 121099"},"PeriodicalIF":4.2,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143373029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Association between air pollution, socioeconomic inequalities and cause specific mortality in a large administrative cohort in a contaminated site of central Italy","authors":"Matteo Renzi,&nbsp;Chiara Badaloni,&nbsp;Alessandro Trentalange,&nbsp;Daniela Porta,&nbsp;Marina Davoli,&nbsp;Paola Michelozzi","doi":"10.1016/j.atmosenv.2025.121082","DOIUrl":"10.1016/j.atmosenv.2025.121082","url":null,"abstract":"<div><h3>Introduction</h3><div>The association between air pollution and mortality has been extensively explored in epidemiological literature in recent decades. Individual factors such as socioeconomic status (SES) and gender have been identified as significant contributors to population vulnerability to the health effects. This study aims to assess how individual (SES), environmental (air pollution) factors and their influence the risk of cause-specific mortality in an administrative cohort of residents of the River Sacco Valley (RSV), a contaminated site of central Italy.</div></div><div><h3>Materials and methods</h3><div>Individual exposure to pollutants (PM₁₀, PM_2.5, NO₂, SO₂, C₆H₆, O₃) at residential addresses was evaluated using dispersion models (FARM) with a 1 km² resolution from the Environmental Protection Agency of Lazio Region (ARPA Lazio). SES was determined by a 5-level area index at the census block level (high to low). Health data, coded with ICD-9 and ICD-10, included non-accidental (0–799 and (A00-R99)), cardiovascular (390–459 and (I00-I99)), respiratory (460–519 and (J00-J99)), and malignancy (140–250 and (C00-C97)) causes of mortality. Residents in the RSV and adjacent area (∼100 municipalities) were enrolled from January 1, 2008, to December 31, 2018. We used Cox proportional hazard models, adjusted for gender, SES, and air pollution to estimate the associations between exposure and outcomes. We also evaluated the interaction between air pollution and SES on the study outcomes. Finally, we estimated the health impact of air pollution by SES category.</div></div><div><h3>Results</h3><div>We enrolled 665,160 subjects (median age: 41 years) at the baseline. High SES constituted 8% while low SES 13% of the study population. We observed 59,767 non-accidental deaths during the study period. SES-related estimates show a clear pattern for each outcome, with HR for low SES up to 1.165 (1.097, 1.238) for non-accidental and 1.184 (1.087, 1.290) for cancer mortality. Air pollutants exhibited positive associations with cancer and respiratory mortality only, with estimates up to 1.05 (1.02, 1.07) and 1.06 (1.03, 1.09) for PM_2.5 and C₆H₆. Air pollution-SES interaction estimates were higher in the low SES category, with HRs up to 1.14 (1.07, 1.21) and 1.19 (1.10, 1.29) for non-accidental and cancer mortality with C₆H₆ exposure. Attributable fraction of causes-specific deaths were higher in lowest SES categories compared to highest ones.</div></div><div><h3>Conclusions</h3><div>Socioeconomic deprivation indicates individual frailty, and air pollution is a major environmental risk factor. However, the association of long-term exposure vary across the population. Higher effects were detected in socioeconomical deprivated subjects. A major public health concerns has to be faced about that.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"347 ","pages":"Article 121082"},"PeriodicalIF":4.2,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143386307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lifetime exposure to health-related air pollutants in the United Kingdom: A spatiotemporal evaluation (1930–2010) through WRF-CMAQ modeling","authors":"Ge Chen ,&nbsp;Yiming Liu ,&nbsp;Haofan Wang ,&nbsp;Menghe Wang ,&nbsp;Lan Chen ,&nbsp;Hejun Hu ,&nbsp;Shiyu Zhang ,&nbsp;Baozhuo Ai ,&nbsp;Miao Cai ,&nbsp;Zilong Zhang ,&nbsp;Qi Fan ,&nbsp;Hualiang Lin","doi":"10.1016/j.atmosenv.2025.121093","DOIUrl":"10.1016/j.atmosenv.2025.121093","url":null,"abstract":"<div><div>Historical air pollutants data are essential for assessing health effects of air pollution exposure across the life course or early life. In the United Kingdom (UK), a lack of high-quality data sources, including emission data, has resulted in limited research on historical air pollution exposure and the health effects. This study aimed to address this gap by developing Weather Research and Forecast (WRF)- Community Multiscale Air Quality modeling system (CMAQ) for particulate matters (PM), gaseous pollutants, and chemical compositions of fine particulate matter (PM_2.5) at an annual level and 10 km resolution. The root mean squared error (RMSE) (normalized mean bias, NMB) between predictions from models and measurements from monitoring stations in 2010 was 4.09 (−0.10) for PM_2.5, 6.34 (−0.22) for PM₁₀, 17.49 (−0.24) for nitrogen dioxide (NO₂), 4.02 (0.13) for sulfur dioxide (SO₂), and 9.2 (0.11) for ozone (O₃) at annual level, and the predicting accuracy was consistent at annual level. The WRF-CMAQ could capture spatiotemporal patterns of the air pollutants. High concentrations of particulate matters and gaseous pollutants, except for ozone, tended to occur in UK densely populated cities such as Greater London. The Humber River estuary and the Mersey River port area had higher concentrations of SO₂. O₃ showed a geographical distribution that was higher in rural areas and lower in urban areas. The annual changes showed most of the areas of UK experienced a reduction of air pollution since 1990, with the exception of O₃ concentrations. Therefore, this research model could provide high-quality historical exposure data on air pollution, supporting future epidemiological studies on the impact of air pollution on the life course health effects in the UK.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"346 ","pages":"Article 121093"},"PeriodicalIF":4.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143317789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A data-driven method for aerosol FMF retrieval over land using single-view polarization satellite data","authors":"Zheng Shi ,&nbsp;Jiaxu Guo ,&nbsp;Zhengqiang Li ,&nbsp;Zhe Ji ,&nbsp;Ying Zhang ,&nbsp;Linlu Mei","doi":"10.1016/j.atmosenv.2025.121083","DOIUrl":"10.1016/j.atmosenv.2025.121083","url":null,"abstract":"<div><div>The aerosol fine mode fraction (FMF), which quantitatively describes the fine mode aerosol optical depth (FAOD) as a proportion of the total AOD, is difficult to obtain through remote sensing retrieval. The Chinese advanced Particulate Observing Scanning Polarimeter (POSP) can achieve multispectral polarimetric observation from ultraviolet (UV) to short-wave infrared (SWIR), making it sensitive to aerosol particle size and expected to enhance the capability of FMF retrieval. In this paper, an FMF retrieval model based on an ensemble neural network (ENN) is proposed, which fully exploits the relationship between multi-spectrally polarimetric data of POSP and FMF parameter, and realizes the high-precision as well as spatiotemporal continuous FMF retrieval. The validation shows that the retrieved FMF is in high agreement with AErosol RObotic NETwork (AERONET) FMF, and the retrieval accuracy increases as AOD increase. By analyzing the importance of the input parameters, it is found that the polarimetric measurement at 865 nm is the most important for FMF retrieval, and the average importance of the polarimetric measurement is the highest. By comparing the global seasonal FMF and FAOD for 2022, as well as cases of forest fires and dust, it can be observed that POSP FMF accurately captures the distribution of fine and coarse aerosol particles, aligning well with real-world conditions. This demonstrates the effectiveness of the proposed algorithm in FMF retrieval.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"346 ","pages":"Article 121083"},"PeriodicalIF":4.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143318328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal characterization of primary and secondary sources of fine PM-bound water-soluble organic carbon in central Los Angeles","authors":"Yashar Aghaei ,&nbsp;Mohammad Mahdi Badami ,&nbsp;Mohammad Aldekheel ,&nbsp;Ramin Tohidi ,&nbsp;Constantinos Sioutas","doi":"10.1016/j.atmosenv.2025.121084","DOIUrl":"10.1016/j.atmosenv.2025.121084","url":null,"abstract":"<div><div>Understanding the sources and formation processes of fine particulate matter (PM_2.5) is crucial for improving urban air quality and public health. This study provides a real-time analysis of PM_2.5-bound water-soluble organic carbon (WSOC) and related carbonaceous species during winter, spring, and summer periods in 2023–2024, aiming to identify their major sources in central Los Angeles. Using advanced online monitoring equipment, including a Sunset Laboratory EC/OC analyzer and a custom-developed setup including a total organic carbon (TOC) analyzer coupled with a particle collection system, we obtained hourly measurements of organic carbon (OC), its fractions (OC₁-OC₄, based on volatility), elemental carbon (EC), and WSOC. Positive matrix factorization (PMF) identified three principal PM_2.5 sources: vehicular emissions, secondary organic carbon (SOC) formation influenced by nighttime aqueous-phase chemical processes, and SOC formation driven by daytime photochemical reactions. Vehicular emissions dominated EC levels, accounting for 86–95% across seasons. This factor also had high contributions from nitrogen oxides (NOₓ) (75–82%), vehicle counts (approximately 85%), and OC₁ (51–83%), reflecting the persistent influence of traffic emissions. Nighttime SOC formation was significant in winter, with WSOC and OC₄ contributing 58% and 40% to this factor. In contrast, daytime photochemical SOC formation was prominent in summer, with WSOC and OC₄ contributing 63% and 47%, and ozone loading up to 89%, reflecting increased photochemical activity. Spring exhibited a mix of aqueous and photochemical SOC formation, with similar contributions from WSOC (38-35%) and OC₄ (35-33%), reflecting the transitional season's mixed SOC formation mechanisms. Diurnal profiles revealed that primary emissions peaked during morning rush hours, while secondary formation processes elevated OC levels at night in winter and during afternoons in summer. The EC tracer method corroborated these findings by estimating primary and secondary organic carbon levels, highlighting significant seasonal and diurnal variations in carbonaceous aerosols. These results emphasize the need for targeted strategies addressing both primary emissions and the precursors of secondary aerosol formation, to improve air quality in Los Angeles.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"346 ","pages":"Article 121084"},"PeriodicalIF":4.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143317790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}