{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:20:11Z","timestamp":1760059211024,"version":"build-2065373602"},"reference-count":108,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2025,5,27]],"date-time":"2025-05-27T00:00:00Z","timestamp":1748304000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["22361162668","SJCX24_0484","KYCX24_1526"],"award-info":[{"award-number":["22361162668","SJCX24_0484","KYCX24_1526"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Postgraduate Research &amp; Practice Innovation Program of Jiangsu Province","award":["22361162668","SJCX24_0484","KYCX24_1526"],"award-info":[{"award-number":["22361162668","SJCX24_0484","KYCX24_1526"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Toxics"],"abstract":"<jats:p>Optical properties and chemical composition of atmospheric fine particles (PM2.5) are critical to their environmental and health effects. In this study, we analyzed the organic aerosols (OA) in PM2.5 samples in Nanjing, China, collected during the summer and winter of 2019 and 2023. Results show a decline in both concentrations and light-absorbing abilities of methanol\u2014soluble organic carbon (MSOC) and water-soluble OC (WSOC) in OA from 2019 to 2023. Due to increased combustion activities, MSOC and WSOC concentrations, and their corresponding mass absorption efficiencies were all higher in winter than in summer. Furthermore, fluorescence indices suggest that OA in Nanjing was influenced by a mix of microbial\/biogenic sources. Fluorescent properties of both WSOC and MSOC were dominated by humic-like components but the remaining contribution from protein-like components was more significant in MSOC. The molecular composition of OA did not show a remarkable difference between 2019 and 2023. Overall, CHON compounds were the most abundant species, followed by CHO and CHN compounds, and aliphatic compounds dominated all molecular types except for CHN (in positive mode) and CHON, CHOS (in negative mode). Regarding the OA sources, the numbers of molecules from fossil fuel combustion and biomass burning (BB) were a bit more in 2023 than in 2019, and signal intensities of BB-related molecules were also higher in winter than in summer; the presence of organosulfates indicate the contribution of aqueous-phase oxidation to OA, especially during high relative humidity conditions. At last, correlations between OA molecules and light absorption efficiencies indicate that the key light-absorbing species in winter and summer were likely quite different despite similar chemical compositions, and in summer, CH and CHN compounds were important to light absorption, whereas CHNS compounds became more important in winter.<\/jats:p>","DOI":"10.3390\/toxics13060443","type":"journal-article","created":{"date-parts":[[2025,5,27]],"date-time":"2025-05-27T11:12:57Z","timestamp":1748344377000},"page":"443","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Optical Properties and Molecular Composition of Fine Organic Aerosols in Nanjing, China: A Comparison of 2019 and 2023"],"prefix":"10.3390","volume":"13","author":[{"given":"Binhuang","family":"Zhou","sequence":"first","affiliation":[{"name":"Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yu","family":"Huang","sequence":"additional","affiliation":[{"name":"Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Liangyu","family":"Feng","sequence":"additional","affiliation":[{"name":"Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zihao","family":"Zhang","sequence":"additional","affiliation":[{"name":"Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Haiwei","family":"Li","sequence":"additional","affiliation":[{"name":"Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5002-9360","authenticated-orcid":false,"given":"Yun","family":"Wu","sequence":"additional","affiliation":[{"name":"Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9063-3260","authenticated-orcid":false,"given":"Jianhuai","family":"Ye","sequence":"additional","affiliation":[{"name":"School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9531-6478","authenticated-orcid":false,"given":"Xinlei","family":"Ge","sequence":"additional","affiliation":[{"name":"Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China"},{"name":"School of Environment and Energy Engineering, Anhui Jianzhu University, Hefei 230601, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,5,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1525","DOI":"10.1126\/science.1180353","article-title":"Evolution of Organic Aerosols in the Atmosphere","volume":"326","author":"Jimenez","year":"2009","journal-title":"Science"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"5965","DOI":"10.5194\/acp-10-5965-2010","article-title":"Water-Soluble Organic Aerosol material and the light-absorption characteristics of aqueous extracts measured over the Southeastern United States","volume":"10","author":"Hecobian","year":"2010","journal-title":"Atmos. Chem. Phys."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"835","DOI":"10.1016\/j.atmosenv.2014.03.030","article-title":"Brown carbon in atmospheric outflow from the Indo-Gangetic Plain: Mass absorption efficiency and temporal variability","volume":"89","author":"Srinivas","year":"2014","journal-title":"Atmos. Environ."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"313","DOI":"10.5194\/acp-17-313-2017","article-title":"Characteristics of brown carbon in the urban Po Valley atmosphere","volume":"17","author":"Costabile","year":"2017","journal-title":"Atmos. Chem. Phys."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"3476","DOI":"10.1002\/2013JD020041","article-title":"Water-soluble organic carbon aerosols during a full New Delhi winter: Isotope-based source apportionment and optical properties","volume":"119","author":"Kirillova","year":"2014","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"7841","DOI":"10.5194\/acp-15-7841-2015","article-title":"Brown carbon aerosol in the North American continental troposphere: Sources, abundance, and radiative forcing","volume":"15","author":"Liu","year":"2015","journal-title":"Atmos. Chem. Phys."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1016\/j.envpol.2018.04.085","article-title":"Light absorption of organic carbon emitted from burning wood, charcoal, and kerosene in household cookstoves","volume":"240","author":"Xie","year":"2018","journal-title":"Environ. Pollut."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"234","DOI":"10.1016\/j.atmosenv.2016.01.042","article-title":"Seasonal variations in the light-absorbing properties of water-soluble and insoluble organic aerosols in Seoul, Korea","volume":"129","author":"Kim","year":"2016","journal-title":"Atmos. Environ."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"12389","DOI":"10.5194\/acp-13-12389-2013","article-title":"Size-resolved measurements of brown carbon in water and methanol extracts and estimates of their contribution to ambient fine-particle light absorption","volume":"13","author":"Liu","year":"2013","journal-title":"Atmos. Chem. Phys."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"370","DOI":"10.1016\/j.atmosres.2018.06.017","article-title":"Characterization, sources, and light absorption of fine organic aerosols during summer and winter at an urban site","volume":"213","author":"Park","year":"2018","journal-title":"Atmos. Res."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1016\/j.atmosenv.2019.05.014","article-title":"Significant secondary organic aerosol production from aqueous-phase processing of two intermediate volatility organic compounds","volume":"211","author":"Lu","year":"2019","journal-title":"Atmos. Environ."},{"key":"ref_12","first-page":"976","article-title":"A comprehensive investigation of aqueous-phase photochemical oxidation of 4-ethylphenol","volume":"685","author":"Ye","year":"2019","journal-title":"Environ. Sci. Technol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"8607","DOI":"10.5194\/acp-13-8607-2013","article-title":"Brown carbon: A significant atmospheric absorber of solar radiation?","volume":"13","author":"Feng","year":"2013","journal-title":"Atmos. Chem. Phys."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3413","DOI":"10.5194\/acp-16-3413-2016","article-title":"A global simulation of brown carbon: Implications for photochemistry and direct radiative effect","volume":"16","author":"Jo","year":"2016","journal-title":"Atmos. Chem. Phys."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1414","DOI":"10.1016\/j.atmosenv.2010.01.042","article-title":"A contribution of brown carbon aerosol to the aerosol light absorption and its radiative forcing in East Asia","volume":"44","author":"Park","year":"2010","journal-title":"Atmos. Environ."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1773","DOI":"10.5194\/acp-10-1773-2010","article-title":"Light absorption by organic carbon from wood combustion","volume":"10","author":"Chen","year":"2010","journal-title":"Atmos. Chem. Phys."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"3563","DOI":"10.5194\/acp-6-3563-2006","article-title":"Optical properties of humic-like substances (HULIS) in biomass-burning aerosols","volume":"6","author":"Hoffer","year":"2006","journal-title":"Atmos. Chem. Phys."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"3131","DOI":"10.5194\/acp-6-3131-2006","article-title":"Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols","volume":"6","author":"Andreae","year":"2006","journal-title":"Atmos. Chem. Phys."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"4335","DOI":"10.1021\/cr5006167","article-title":"Chemistry of Atmospheric Brown Carbon","volume":"115","author":"Laskin","year":"2015","journal-title":"Chem. Rev."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"7389","DOI":"10.1002\/jgrd.50561","article-title":"Speciation of \u201cbrown\u201d carbon in cloud water impacted by agricultural biomass burning in eastern China","volume":"118","author":"Desyaterik","year":"2013","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"3685","DOI":"10.1021\/es305047b","article-title":"Sources, Composition and Absorption \u00c5ngstr\u00f6m Exponent of Light-absorbing Organic Components in Aerosol Extracts from the Los Angeles Basin","volume":"47","author":"Zhang","year":"2013","journal-title":"Environ. Sci. Technol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"6825","DOI":"10.1021\/acs.est.8b02386","article-title":"Brown Carbon Aerosol in Urban Xi\u2019an, Northwest China: The Composition and Light Absorption Properties","volume":"52","author":"Huang","year":"2018","journal-title":"Environ. Sci. Technol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"989","DOI":"10.1126\/science.adr4473","article-title":"Nitrogen dominates global atmospheric organic aerosol absorption","volume":"387","author":"Li","year":"2025","journal-title":"Science"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"12815","DOI":"10.5194\/acp-16-12815-2016","article-title":"Optical properties and aging of light-absorbing secondary organic aerosol","volume":"16","author":"Liu","year":"2016","journal-title":"Atmos. Chem. Phys."},{"key":"ref_25","first-page":"137322","article-title":"Identification of species and sources of atmospheric chromophores by fluorescence excitation-emission matrix with parallel factor analysis","volume":"718","author":"Chen","year":"2020","journal-title":"Environ. Sci. Technol."},{"key":"ref_26","first-page":"138290","article-title":"Occurrence and sources of chromophoric organic carbon in fine particulate matter over Xi\u2019an, China","volume":"725","author":"Li","year":"2020","journal-title":"Environ. Sci. Technol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"126350","DOI":"10.1016\/j.chemosphere.2020.126350","article-title":"Light-absorbing and fluorescent properties of atmospheric brown carbon: A case study in Nanjing, China","volume":"251","author":"Xie","year":"2020","journal-title":"Chemosphere"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"11561","DOI":"10.1021\/acs.est.7b02276","article-title":"Molecular Chemistry of Atmospheric Brown Carbon Inferred from a Nationwide Biomass Burning Event","volume":"51","author":"Lin","year":"2017","journal-title":"Environ. Sci. Technol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"355","DOI":"10.1016\/j.atmosenv.2015.12.035","article-title":"The characteristics of brown carbon aerosol during winter in Beijing","volume":"127","author":"Cheng","year":"2016","journal-title":"Atmos. Environ."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"8293","DOI":"10.1021\/acs.est.7b01630","article-title":"Structural and Light-Absorption Characteristics of Complex Water-Insoluble Organic Mixtures in Urban Submicrometer Aerosols","volume":"51","author":"Chen","year":"2017","journal-title":"Environ. Sci. Technol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1038\/s41612-019-0069-5","article-title":"Infrared-absorbing carbonaceous tar can dominate light absorption by marine-engine exhaust","volume":"2","author":"Corbin","year":"2019","journal-title":"Npj Clim. Atmos. Sci."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Afsana, S., Zhou, R., Miyazaki, Y., Tachibana, E., Deshmukh, D.K., Kawamura, K., and Mochida, M. (2022). Abundance, chemical structure, and light absorption properties of humic-like substances (HULIS) and other organic fractions of forest aerosols in Hokkaido. Sci. Rep., 12.","DOI":"10.1038\/s41598-022-18201-z"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"10859","DOI":"10.1021\/acs.est.6b02541","article-title":"Light Absorption and Excitation\u2013Emission Fluorescence of Urban Organic Aerosol Components and Their Relationship to Chemical Structure","volume":"50","author":"Chen","year":"2016","journal-title":"Environ. Sci. Technol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"7836","DOI":"10.1021\/acs.est.0c01149","article-title":"Water-Insoluble Organics Dominate Brown Carbon in Wintertime Urban Aerosol of China: Chemical Characteristics and Optical Properties","volume":"54","author":"Huang","year":"2020","journal-title":"Environ. Sci. Technol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"119710","DOI":"10.1016\/j.atmosenv.2023.119710","article-title":"Fluorescence of solvent-extractable organics in sub-micrometer forest aerosols in Hokkaido, Japan","volume":"303","author":"Afsana","year":"2023","journal-title":"Atmos. Environ."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"909","DOI":"10.1021\/acs.est.2c05918","article-title":"Molecular Composition of Beijing PM2.5 Brown Carbon Revealed by an Untargeted Approach Based on Gas Chromatography and Time-of-Flight Mass Spectrometry","volume":"57","author":"Kuang","year":"2023","journal-title":"Environ. Sci. Technol."},{"key":"ref_37","first-page":"156189","article-title":"Molecular characterization of nitrogen-containing organic compounds in the winter North China Plain","volume":"838","author":"Mao","year":"2022","journal-title":"Environ. Sci. Technol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1016\/j.atmosenv.2018.06.036","article-title":"UHPLC-Orbitrap mass spectrometric characterization of organic aerosol from a central European city (Mainz, Germany) and a Chinese megacity (Beijing)","volume":"189","author":"Wang","year":"2018","journal-title":"Atmos. Environ."},{"key":"ref_39","first-page":"149419","article-title":"Molecular characterization of organic aerosols in Taiyuan, China: Seasonal variation and source identification","volume":"800","author":"Wang","year":"2021","journal-title":"Environ. Sci. Technol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"9109","DOI":"10.5194\/acp-16-9109-2016","article-title":"Highly time-resolved urban aerosol characteristics during springtime in Yangtze River Delta, China: Insights from soot particle aerosol mass spectrometry","volume":"16","author":"Wang","year":"2016","journal-title":"Atmos. Chem. Phys."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"66","DOI":"10.1016\/j.atmosenv.2018.09.008","article-title":"Responses of secondary aerosols to relative humidity and photochemical activities in an industrialized environment during late winter","volume":"193","author":"Wu","year":"2018","journal-title":"Atmos. Environ."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Li, D., Cui, S., Wu, Y., Wang, J., and Ge, X. (2024). Direct Measurement of Aerosol Liquid Water Content: A Case Study in Summer in Nanjing, China. Toxics, 12.","DOI":"10.3390\/toxics12030164"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1016\/j.envpol.2017.03.044","article-title":"Aerosol characteristics and sources in Yangzhou, China resolved by offline aerosol mass spectrometry and other techniques","volume":"225","author":"Ge","year":"2017","journal-title":"Environ. Pollut."},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Chen, Y., Chen, Y., Xie, X., Ye, Z., Li, Q., Ge, X., and Chen, M. (2019). Chemical Characteristics of PM2.5 and Water-Soluble Organic Nitrogen in Yangzhou, China. Atmosphere, 10.","DOI":"10.3390\/atmos10040178"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"523","DOI":"10.1038\/nmeth.3393","article-title":"MS-DIAL: Data-independent MS\/MS deconvolution for comprehensive metabolome analysis","volume":"12","author":"Tsugawa","year":"2015","journal-title":"Nat. Methods."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"4193","DOI":"10.1021\/ac200464q","article-title":"Study of Double Bond Equivalents and the Numbers of Carbon and Oxygen Atom Distribution of Dissolved Organic Matter with Negative-Mode FT-ICR MS","volume":"83","author":"Bae","year":"2011","journal-title":"Anal. Chem."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"2445","DOI":"10.1002\/rcm.7038","article-title":"Structural characterization of organic aerosol using Fourier transform ion cyclotron resonance mass spectrometry: Aromaticity equivalent approach","volume":"28","author":"Yassine","year":"2014","journal-title":"Rapid Commun. Mass Spectrom."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"11899","DOI":"10.5194\/acp-16-11899-2016","article-title":"Molecular composition of organic aerosols in central Amazonia: An ultra-high-resolution mass spectrometry study","volume":"16","author":"Kourtchev","year":"2016","journal-title":"Atmos. Chem. Phys."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1039\/C5FD00206K","article-title":"Molecular composition of organic aerosols at urban background and road tunnel sites using ultra-high resolution mass spectrometry","volume":"189","author":"Tong","year":"2016","journal-title":"Faraday Discuss."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1038\/nchem.948","article-title":"Carbon oxidation state as a metric for describing the chemistry of atmospheric organic aerosol","volume":"3","author":"Kroll","year":"2011","journal-title":"Nat. Chem."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"7454","DOI":"10.1021\/es300285d","article-title":"Elemental Composition of HULIS in the Pearl River Delta Region, China: Results Inferred from Positive and Negative Electrospray High Resolution Mass Spectrometric Data","volume":"46","author":"Lin","year":"2012","journal-title":"Environ. Sci. Technol."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"230","DOI":"10.1016\/j.atmosenv.2018.06.002","article-title":"Seasonal light absorption properties of water-soluble brown carbon in atmospheric fine particles in Nanjing, China","volume":"187","author":"Chen","year":"2018","journal-title":"Atmos. Environ."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"105028","DOI":"10.1016\/j.atmosres.2020.105028","article-title":"Brown carbon in atmospheric fine particles in Yangzhou, China: Light absorption properties and source apportionment","volume":"244","author":"Chen","year":"2020","journal-title":"Atmos. Res."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"6557","DOI":"10.1039\/c3ay41160e","article-title":"Fluorescence spectroscopy and multi-way techniques. PARAFAC","volume":"5","author":"Murphy","year":"2013","journal-title":"Anal. Methods"},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"270","DOI":"10.1016\/j.orggeochem.2009.11.002","article-title":"Characterization of dissolved organic matter in cave and spring waters using UV\u2013Vis absorbance and fluorescence spectroscopy","volume":"41","author":"Birdwell","year":"2010","journal-title":"Org. Geochem."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"38","DOI":"10.4319\/lo.2001.46.1.0038","article-title":"Spectrofluorometric characterization of dissolved organic matter for indication of precursor organic material and aromaticity","volume":"46","author":"McKnight","year":"2001","journal-title":"Limnol. Oceanogr."},{"key":"ref_57","doi-asserted-by":"crossref","unstructured":"Zhang, B., Tang, J., Geng, X., Mo, Y., Zhao, S., Zhong, G., Li, J., and Zhang, G. (2024). Seasonal changes in water-soluble brown carbon (BrC) at Nanling background station in South China. Front. Environ. Sci., 12.","DOI":"10.3389\/fenvs.2024.1360453"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"12609","DOI":"10.5194\/acp-23-12609-2023","article-title":"Characterizing water-soluble brown carbon in fine particles in four typical cities in northwestern China during wintertime: Integrating optical properties with chemical processes","volume":"23","author":"Zhong","year":"2023","journal-title":"Atmos. Chem. Phys."},{"key":"ref_59","first-page":"135902","article-title":"Impact of secondary and primary particulate matter (PM) sources on the enhanced light absorption by brown carbon (BrC) particles in central Los Angeles","volume":"705","author":"Soleimanian","year":"2020","journal-title":"Environ. Sci. Technol."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"6349","DOI":"10.1021\/es401043j","article-title":"Relationship between Oxidation Level and Optical Properties of Secondary Organic Aerosol","volume":"47","author":"Lambe","year":"2013","journal-title":"Environ. Sci. Technol."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"48","DOI":"10.1016\/j.atmosenv.2018.09.025","article-title":"Optical properties and oxidative potential of water- and alkaline-soluble brown carbon in smoke particles emitted from laboratory simulated biomass burning","volume":"194","author":"Fan","year":"2018","journal-title":"Atmos. Environ."},{"key":"ref_62","doi-asserted-by":"crossref","unstructured":"Shamjad, P.M., Tripathi, S.N., Thamban, N.M., and Vreeland, H. (2016). Refractive Index and Absorption Attribution of Highly Absorbing Brown Carbon Aerosols from an Urban Indian City-Kanpur. Sci. Rep., 6.","DOI":"10.1038\/srep37735"},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"6449","DOI":"10.5194\/acp-22-6449-2022","article-title":"Measurement report: Optical properties and sources of water-soluble brown carbon in Tianjin, North China\u2014insights from organic molecular compositions","volume":"22","author":"Deng","year":"2022","journal-title":"Atmos. Chem. Phys."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"4889","DOI":"10.5194\/acp-20-4889-2020","article-title":"Optical properties and molecular compositions of water-soluble and water-insoluble brown carbon (BrC) aerosols in northwest China","volume":"20","author":"Li","year":"2020","journal-title":"Atmos. Chem. Phys."},{"key":"ref_65","first-page":"147971","article-title":"Water-soluble brown carbon in atmospheric aerosols along the transport pathway of Asian dust: Optical properties, chemical compositions, and potential sources","volume":"789","author":"Wen","year":"2021","journal-title":"Environ. Sci. Technol."},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"115932","DOI":"10.1016\/j.envpol.2020.115932","article-title":"Absorption properties and forcing efficiency of light-absorbing water-soluble organic aerosols: Seasonal and spatial variability","volume":"272","author":"Choudhary","year":"2021","journal-title":"Environ. Pollut."},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"2335","DOI":"10.1021\/acsearthspacechem.2c00047","article-title":"Evolution of Brown Carbon Aerosols during Atmospheric Long-Range Transport in the South Asian Outflow and Himalayan Cryosphere","volume":"6","author":"Choudhary","year":"2022","journal-title":"ACS Earth Space Chem."},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"540","DOI":"10.1021\/acs.estlett.7b00393","article-title":"Atmospheric Photooxidation Diminishes Light Absorption by Primary Brown Carbon Aerosol from Biomass Burning","volume":"4","author":"Sumlin","year":"2017","journal-title":"Environ. Sci. Technol. Lett."},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"706","DOI":"10.1016\/j.orggeochem.2009.03.002","article-title":"Properties of fluorescent dissolved organic matter in the Gironde Estuary","volume":"40","author":"Huguet","year":"2009","journal-title":"Org. Geochem."},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"5763","DOI":"10.1021\/es400644c","article-title":"Excitation\u2013Emission Spectra and Fluorescence Quantum Yields for Fresh and Aged Biogenic Secondary Organic Aerosols","volume":"47","author":"Lee","year":"2013","journal-title":"Environ. Sci. Technol."},{"key":"ref_71","doi-asserted-by":"crossref","unstructured":"Fu, P., Kawamura, K., Chen, J., Qin, M., Ren, L., Sun, Y., Wang, Z., Barrie, L.A., Tachibana, E., and Ding, A. (2015). Fluorescent water-soluble organic aerosols in the High Arctic atmosphere. Sci. Rep., 5.","DOI":"10.1038\/srep09845"},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"203","DOI":"10.1016\/j.atmosenv.2018.04.049","article-title":"Fluorescence fingerprinting properties for exploring water-soluble organic compounds in PM2.5 in an industrial city of northwest China","volume":"184","author":"Qin","year":"2018","journal-title":"Atmos. Environ."},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"5887","DOI":"10.5194\/acp-24-5887-2024","article-title":"Measurement report: Optical characterization, seasonality, and sources of brown carbon in fine aerosols from Tianjin, North China: Year-round observations","volume":"24","author":"Dong","year":"2024","journal-title":"Atmos. Chem. Phys."},{"key":"ref_74","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1016\/j.atmosenv.2019.02.039","article-title":"The aging behaviors of chromophoric biomass burning brown carbon during dark aqueous hydroxyl radical oxidation processes in laboratory studies","volume":"205","author":"Fan","year":"2019","journal-title":"Atmos. Environ."},{"key":"ref_75","doi-asserted-by":"crossref","first-page":"325","DOI":"10.1016\/0304-4203(95)00062-3","article-title":"Characterization of marine and terrestrial DOM in seawater using excitation-emission matrix spectroscopy","volume":"51","author":"Coble","year":"1996","journal-title":"Mar. Chem."},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"2909","DOI":"10.1021\/es103015e","article-title":"Organic Matter Fluorescence in Municipal Water Recycling Schemes: Toward a Unified PARAFAC Model","volume":"45","author":"Murphy","year":"2011","journal-title":"Environ. Sci. Technol."},{"key":"ref_77","doi-asserted-by":"crossref","unstructured":"Yu, H., Liang, H., Qu, F., Han, Z.-S., Shao, S., Chang, H., and Li, G. (2015). Impact of dataset diversity on accuracy and sensitivity of parallel factor analysis model of dissolved organic matter fluorescence excitation-emission matrix. Sci. Rep., 5.","DOI":"10.1038\/srep10207"},{"key":"ref_78","doi-asserted-by":"crossref","first-page":"10351","DOI":"10.1021\/acs.est.6b01643","article-title":"Characterization of Chromophoric Water-Soluble Organic Matter in Urban, Forest, and Marine Aerosols by HR-ToF-AMS Analysis and Excitation\u2013Emission Matrix Spectroscopy","volume":"50","author":"Chen","year":"2016","journal-title":"Environ. Sci. Technol."},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"111","DOI":"10.3189\/172756411795931912","article-title":"Characterization of dissolved organic matter (DOM) from glacial environments using total fluorescence spectroscopy and parallel factor analysis","volume":"51","author":"Dubnick","year":"2010","journal-title":"Ann. Glaciol."},{"key":"ref_80","doi-asserted-by":"crossref","first-page":"99","DOI":"10.2343\/geochemj.1.0047","article-title":"Excitation-emission matrix characterization of dissolved organic matter sources in two eutrophic lakes (Southwestern China Plateau)","volume":"44","author":"Fu","year":"2010","journal-title":"Geochem. J."},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1016\/j.jphotochem.2015.09.012","article-title":"Computational assessment of the fluorescence emission of phenol oligomers: A possible insight into the fluorescence properties of humic-like substances (HULIS)","volume":"315","author":"Barsotti","year":"2016","journal-title":"J. Photochem. Photobiol. A Chem."},{"key":"ref_82","first-page":"147412","article-title":"Diurnal evolutions and sources of water-soluble chromophoric aerosols over Xi\u2019an during haze event, in Northwest China","volume":"786","author":"Chen","year":"2021","journal-title":"Environ. Sci. Technol."},{"key":"ref_83","doi-asserted-by":"crossref","first-page":"13187","DOI":"10.5194\/acp-21-13187-2021","article-title":"Chemical composition, optical properties, and oxidative potential of water- and methanol-soluble organic compounds emitted from the combustion of biomass materials and coal","volume":"21","author":"Cao","year":"2021","journal-title":"Atmos. Chem. Phys."},{"key":"ref_84","doi-asserted-by":"crossref","first-page":"588","DOI":"10.1016\/j.atmosenv.2013.05.027","article-title":"A regional study of the seasonal variation in the molecular composition of rainwater","volume":"77","author":"Cottrell","year":"2013","journal-title":"Atmos. Environ."},{"key":"ref_85","doi-asserted-by":"crossref","first-page":"4495","DOI":"10.1021\/acs.analchem.6b00378","article-title":"Characterization of Highly Oxidized Molecules in Fresh and Aged Biogenic Secondary Organic Aerosol","volume":"88","author":"Tu","year":"2016","journal-title":"Anal. Chem."},{"key":"ref_86","doi-asserted-by":"crossref","first-page":"525","DOI":"10.1016\/j.atmosenv.2014.02.051","article-title":"Effects of anthropogenic emissions on the molecular composition of urban organic aerosols: An ultrahigh resolution mass spectrometry study","volume":"89","author":"Kourtchev","year":"2014","journal-title":"Atmos. Environ."},{"key":"ref_87","doi-asserted-by":"crossref","first-page":"524","DOI":"10.1016\/j.atmosenv.2010.10.012","article-title":"Atmospheric amines\u2014Part I. A review","volume":"45","author":"Ge","year":"2011","journal-title":"Atmos. Environ."},{"key":"ref_88","doi-asserted-by":"crossref","first-page":"228","DOI":"10.1016\/j.chroma.2008.05.078","article-title":"Thermal extraction\u2013two-dimensional gas chromatography\u2013mass spectrometry with heart-cutting for nitrogen heterocyclics in biomass burning aerosols","volume":"1200","author":"Ma","year":"2008","journal-title":"J. Chromatogr. A"},{"key":"ref_89","doi-asserted-by":"crossref","first-page":"7649","DOI":"10.5194\/acp-19-7649-2019","article-title":"The formation of nitro-aromatic compounds under high NOx and anthropogenic VOC conditions in urban Beijing, China","volume":"19","author":"Wang","year":"2019","journal-title":"Atmos. Chem. Phys."},{"key":"ref_90","doi-asserted-by":"crossref","first-page":"4349","DOI":"10.5194\/acp-18-4349-2018","article-title":"Observations of fine particulate nitrated phenols in four sites in northern China: Concentrations, source apportionment, and secondary formation","volume":"18","author":"Wang","year":"2018","journal-title":"Atmos. Chem. Phys."},{"key":"ref_91","doi-asserted-by":"crossref","first-page":"13607","DOI":"10.1021\/acs.est.9b04331","article-title":"Molecular Characterization of Water- and Methanol-Soluble Organic Compounds Emitted from Residential Coal Combustion Using Ultrahigh-Resolution Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry","volume":"53","author":"Song","year":"2019","journal-title":"Environ. Sci. Technol."},{"key":"ref_92","doi-asserted-by":"crossref","first-page":"23312","DOI":"10.1039\/C5CP02563J","article-title":"Molecular characterization of brown carbon (BrC) chromophores in secondary organic aerosol generated from photo-oxidation of toluene","volume":"17","author":"Lin","year":"2015","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_93","doi-asserted-by":"crossref","first-page":"231","DOI":"10.1016\/j.atmosenv.2004.09.044","article-title":"Nitrated phenols in the atmosphere: A review","volume":"39","author":"Harrison","year":"2005","journal-title":"Atmos. Environ."},{"key":"ref_94","doi-asserted-by":"crossref","first-page":"5951","DOI":"10.1021\/acs.est.7b00248","article-title":"Molecular Characterization of Nitrogen-Containing Organic Compounds in Humic-like Substances Emitted from Straw Residue Burning","volume":"51","author":"Wang","year":"2017","journal-title":"Environ. Sci. Technol."},{"key":"ref_95","doi-asserted-by":"crossref","first-page":"8453","DOI":"10.1021\/es102938a","article-title":"Methyl-Nitrocatechols: Atmospheric Tracer Compounds for Biomass Burning Secondary Organic Aerosols","volume":"44","author":"Iinuma","year":"2010","journal-title":"Environ. Sci. Technol."},{"key":"ref_96","doi-asserted-by":"crossref","first-page":"561","DOI":"10.1016\/j.atmosenv.2013.09.041","article-title":"One-year study of nitro-organic compounds and their relation to wood burning in PM10 aerosol from a rural site in Belgium","volume":"81","author":"Kahnt","year":"2013","journal-title":"Atmos. Environ."},{"key":"ref_97","doi-asserted-by":"crossref","first-page":"1105","DOI":"10.5194\/acp-20-1105-2020","article-title":"Molecular composition and photochemical lifetimes of brown carbon chromophores in biomass burning organic aerosol","volume":"20","author":"Fleming","year":"2020","journal-title":"Atmos. Chem. Phys."},{"key":"ref_98","doi-asserted-by":"crossref","first-page":"8037","DOI":"10.5194\/acp-19-8037-2019","article-title":"Organic aerosol source apportionment in Zurich using an extractive electrospray ionization time-of-flight mass spectrometer (EESI\u2212TOF-MS)\u2014Part 2: Biomass burning influences in winter","volume":"19","author":"Qi","year":"2019","journal-title":"Atmos. Chem. Phys."},{"key":"ref_99","first-page":"1220","article-title":"The effect of sub-zero temperature on the formation and composition of secondary organic aerosol from ozonolysis of alpha-pinene","volume":"19","author":"Kristensen","year":"2017","journal-title":"Environ. Sci. Proc. Imp."},{"key":"ref_100","doi-asserted-by":"crossref","first-page":"747","DOI":"10.1038\/s41561-024-01493-3","article-title":"Substantial contribution of transported emissions to organic aerosol in Beijing","volume":"17","author":"Daellenbach","year":"2024","journal-title":"Nat. Geosci."},{"key":"ref_101","doi-asserted-by":"crossref","first-page":"e2020EA001615","DOI":"10.1029\/2020EA001615","article-title":"Chemical Characteristics, Size Distributions, Molecular Composition, and Brown Carbon in South Asian Outflow to the Indian Ocean","volume":"8","author":"Boreddy","year":"2021","journal-title":"Earth Space Sci."},{"key":"ref_102","doi-asserted-by":"crossref","first-page":"2575","DOI":"10.1021\/acs.est.7b06126","article-title":"Molecular Characterization of Water-Soluble Humic like Substances in Smoke Particles Emitted from Combustion of Biomass Materials and Coal Using Ultrahigh-Resolution Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry","volume":"52","author":"Song","year":"2018","journal-title":"Environ. Sci. Technol."},{"key":"ref_103","doi-asserted-by":"crossref","first-page":"14222","DOI":"10.1021\/acs.est.9b06152","article-title":"Enhancement in Particulate Organic Nitrogen and Light Absorption of Humic-Like Substances over Tibetan Plateau Due to Long-Range Transported Biomass Burning Emissions","volume":"53","author":"Wang","year":"2019","journal-title":"Environ. Sci. Technol."},{"key":"ref_104","doi-asserted-by":"crossref","first-page":"126431","DOI":"10.1016\/j.jhazmat.2021.126431","article-title":"Molecular characterization of atmospheric particulate organosulfates in a port environment using ultrahigh resolution mass spectrometry: Identification of traffic emissions","volume":"419","author":"Qi","year":"2021","journal-title":"J. Hazard. Mater."},{"key":"ref_105","doi-asserted-by":"crossref","first-page":"10693","DOI":"10.5194\/acp-18-10693-2018","article-title":"The secondary formation of organosulfates under interactions between biogenic emissions and anthropogenic pollutants in summer in Beijing","volume":"18","author":"Wang","year":"2018","journal-title":"Atmos. Chem. Phys."},{"key":"ref_106","doi-asserted-by":"crossref","first-page":"144339","DOI":"10.1016\/j.scitotenv.2020.144339","article-title":"Detection of organosulfates and nitrooxy-organosulfates in Arctic and Antarctic atmospheric aerosols, using ultra-high resolution FT-ICR mass spectrometry","volume":"767","author":"Ye","year":"2021","journal-title":"Sci. Total Environ."},{"key":"ref_107","doi-asserted-by":"crossref","first-page":"114742","DOI":"10.1016\/j.envpol.2020.114742","article-title":"Effects of NOx and SO2 on the secondary organic aerosol formation from the photooxidation of 1,3,5-trimethylbenzene: A new source of organosulfates","volume":"264","author":"Yang","year":"2020","journal-title":"Environ. Pollut."},{"key":"ref_108","doi-asserted-by":"crossref","first-page":"1237","DOI":"10.1021\/es5043707","article-title":"Aqueous Organic Chemistry in the Atmosphere: Sources and Chemical Processing of Organic Aerosols","volume":"49","author":"McNeill","year":"2015","journal-title":"Environ. Sci. Technol."}],"container-title":["Toxics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2305-6304\/13\/6\/443\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:41:44Z","timestamp":1760031704000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2305-6304\/13\/6\/443"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,5,27]]},"references-count":108,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2025,6]]}},"alternative-id":["toxics13060443"],"URL":"https:\/\/doi.org\/10.3390\/toxics13060443","relation":{},"ISSN":["2305-6304"],"issn-type":[{"type":"electronic","value":"2305-6304"}],"subject":[],"published":{"date-parts":[[2025,5,27]]}}}