{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,11]],"date-time":"2026-01-11T01:00:01Z","timestamp":1768093201708,"version":"3.49.0"},"reference-count":39,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2025,2,6]],"date-time":"2025-02-06T00:00:00Z","timestamp":1738800000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Toxics"],"abstract":"<jats:p>Nitroaromatic compounds (NACs) have adverse effects on human health and climate. Daily PM2.5 samples were collected in winter and summer of 2022 in two cities, Chengdu (CD) and Mianyang (MY), located in Sichuan Basin of southwestern China. Four types of NACs in PM2.5, containing nitrophenols, nitrocatechols, nitrosalicylic acids, and nitronaphthol, were analyzed. The mean concentration of a total of 10 NACs (\u03a3NACs) in winter at the suburban MY site (71.7 \u00b1 35.6 ng m\u22123) was higher than that in urban CD (29.5 \u00b1 16.2 ng m\u22123), while in summer, the mean concentrations of \u03a3NACs in the two cities were similar, around 2.2 ng m\u22123. The much higher concentrations of \u03a3NACs in winter were attributed to the impact of biomass burning. 4-Nitrocatechol (4NC) was the most abundant species during the sampling period, accounting for 35\u201356% of \u03a3NACs mass. In winter, the mean light absorption coefficient of methanol-soluble brown carbon (Abs365,M) was 10.5 \u00b1 3.4 and 13.6 \u00b1 4.3 Mm\u22121 in CD and MY, respectively, which was about 4\u20137 times that of summer. The contributions of light absorption of \u03a3NACs at 365 nm to Abs365,M were 1.6\u20133.6% in winter and 0.5\u20130.7% in summer, with 4NC contributing the most to brown carbon among all NACs. The geographical origins of potential sources of NACs at both sites were mainly distributed within the basin.<\/jats:p>","DOI":"10.3390\/toxics13020124","type":"journal-article","created":{"date-parts":[[2025,2,6]],"date-time":"2025-02-06T06:30:29Z","timestamp":1738823429000},"page":"124","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Seasonal Trends and Site Differences of Nitroaromatic Compounds in PM2.5 in Sichuan Basin and Their Effects on Light Absorption of Brown Carbon"],"prefix":"10.3390","volume":"13","author":[{"given":"Tian","family":"Tang","sequence":"first","affiliation":[{"name":"School of Environment and Resource, Southwest University of Science and Technology, Mianyang 621010, China"},{"name":"Sichuan Meteorological Disaster Prevention Technology Centre, Chengdu 610072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Buyi","family":"Xu","sequence":"additional","affiliation":[{"name":"Sichuan Provincial Department of Public Security, Chengdu 610041, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hongli","family":"Tao","sequence":"additional","affiliation":[{"name":"School of Environment and Resource, Southwest University of Science and Technology, Mianyang 621010, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tingting","family":"Huo","sequence":"additional","affiliation":[{"name":"School of Environment and Resource, Southwest University of Science and Technology, Mianyang 621010, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Huanbo","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Environment and Resource, Southwest University of Science and Technology, Mianyang 621010, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,2,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"11624","DOI":"10.1073\/pnas.1203707109","article-title":"Observationally constrained estimates of carbonaceous aerosol radiative forcing","volume":"109","author":"Chung","year":"2012","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"486","DOI":"10.1038\/ngeo2960","article-title":"Top-of-atmosphere radiative forcing affected by brown carbon in the upper troposphere","volume":"10","author":"Zhang","year":"2017","journal-title":"Nat. Geosci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1901","DOI":"10.5194\/acp-20-1901-2020","article-title":"Modeling the global radiative effect of brown carbon: A potentially larger heating source in the tropical free troposphere than black carbon","volume":"20","author":"Zhang","year":"2020","journal-title":"Atmos. Chem. Phys."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Niu, H., Wu, C., Schindler, M., Silva, L.F.O., Ma, B., Ma, X., Ji, X., Tian, Y., Zhu, H., and Bao, X. (2024). Characterization of PM2.5 Carbonaceous Components in a Typical Industrial City in China under Continuous Mitigation Measures. Toxics, 12.","DOI":"10.3390\/toxics12070461"},{"key":"ref_5","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_6","doi-asserted-by":"crossref","unstructured":"Afsana, S., Zhou, R.C., 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_7","doi-asserted-by":"crossref","first-page":"4415","DOI":"10.1021\/acs.est.7b00397","article-title":"Light-Absorbing Brown Carbon Aerosol Constituents from Combustion of Indonesian Peat and Biomass","volume":"51","author":"Budisulistiorini","year":"2017","journal-title":"Environ. Sci. Technol."},{"key":"ref_8","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_9","doi-asserted-by":"crossref","unstructured":"Zhang, L., Son, J.H., Bai, Z., Zhang, W., Li, L., Wang, L., and Chen, J. (2022). Characterizing Atmospheric Brown Carbon and Its Emission Sources during Wintertime in Shanghai, China. Atmosphere, 13.","DOI":"10.3390\/atmos13060991"},{"key":"ref_10","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_11","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_12","doi-asserted-by":"crossref","first-page":"120650","DOI":"10.1016\/j.envpol.2022.120650","article-title":"Characterization of nitrated aromatic compounds in fine particles from Nanjing, China: Optical properties, source allocation, and secondary processes","volume":"316","author":"Cao","year":"2023","journal-title":"Environ. Pollut."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"3685","DOI":"10.5194\/acp-21-3685-2021","article-title":"Measurement report: PM-bound nitrated aromatic compounds in Xi\u2019an, Northwest China\u2014Seasonal variations and contributions to optical properties of brown carbon","volume":"21","author":"Yuan","year":"2021","journal-title":"Atmos. Chem. Phys."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"111982","DOI":"10.1016\/j.envres.2021.111982","article-title":"Evolution of aerosol chemistry in Beijing under strong influence of anthropogenic pollutants: Composition, sources, and secondary formation of fine particulate nitrated aromatic compounds","volume":"204","author":"Ren","year":"2022","journal-title":"Environ. Res."},{"key":"ref_15","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_16","doi-asserted-by":"crossref","first-page":"6835","DOI":"10.5194\/acp-23-6835-2023","article-title":"Contributions of primary emissions and secondary formation to nitratedaromatic compounds in themountain background region of Southeast China","volume":"23","author":"Ren","year":"2023","journal-title":"Atmos. Chem. Phys."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"170523","DOI":"10.1016\/j.scitotenv.2024.170523","article-title":"The role of nitroaromatic compounds (NACs) in constraining BrC absorption in the Indo-Gangetic Plain (IGP)","volume":"917","author":"Rana","year":"2024","journal-title":"Sci. Total Environ."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"134381","DOI":"10.1016\/j.chemosphere.2022.134381","article-title":"Seasonal variability of nitroaromatic compounds in ambient aerosols: Mass size distribution, possible sources and contribution to water-soluble brown carbon light absorption","volume":"299","author":"Frka","year":"2022","journal-title":"Chemosphere"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"117289","DOI":"10.1016\/j.atmosenv.2020.117289","article-title":"Light absorption properties of brown carbon (BrC) in autumn and winter in Beijing: Composition, formation and contribution of nitrated aromatic compounds","volume":"223","author":"Li","year":"2020","journal-title":"Atmos. Environ."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"483","DOI":"10.1016\/j.jes.2022.09.033","article-title":"Comprehensive understanding on sources of high levels of fine particulate nitro-aromatic compounds at a coastal rural area in northern China","volume":"135","author":"Jiang","year":"2024","journal-title":"J. Environ. Sci."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"5160","DOI":"10.1021\/acs.est.2c07324","article-title":"Polar Nitrated Aromatic Compounds in Urban Fine Particulate Matter: A Focus on Formation via an Aqueous-Phase Radical Mechanism","volume":"57","author":"Shi","year":"2023","journal-title":"Environ. Sci. Technol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"147418","DOI":"10.1016\/j.scitotenv.2021.147418","article-title":"Links between the optical properties and chemical compositions of brown carbon chromophores in different environments: Contributions and formation of functionalized aromatic compounds","volume":"786","author":"Li","year":"2021","journal-title":"Sci. Total Environ."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"113255","DOI":"10.1016\/j.envres.2022.113255","article-title":"Chemical composition, sources and optical properties of nitrated aromatic compounds in fine particulate matter during winter foggy days in Nanjing, China","volume":"212","author":"Gu","year":"2022","journal-title":"Environ. Res."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"172672","DOI":"10.1016\/j.scitotenv.2024.172672","article-title":"Nitroaromatic compounds in six major Chinese cities: Influence of different formation mechanisms on light absorption properties","volume":"930","author":"Huang","year":"2024","journal-title":"Sci. Total Environ."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"142845","DOI":"10.1016\/j.chemosphere.2024.142845","article-title":"Characterization of atmospheric nitroaromatic compounds in Southwest China by direct injection liquid chromatography-tandem mass spectrometry analysis of aerosol extracts","volume":"363","author":"Tao","year":"2024","journal-title":"Chemosphere"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"865","DOI":"10.5194\/acp-18-865-2018","article-title":"Seasonal characteristics, formation mechanisms and source origins of PM2.5 in two megacities in Sichuan Basin, China","volume":"18","author":"Wang","year":"2018","journal-title":"Atmos. Chem. Phys."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"170374","DOI":"10.1016\/j.scitotenv.2024.170374","article-title":"Light absorption enhancement of black carbon and its impact factors during winter in a megacity of the Sichuan Basin, China","volume":"918","author":"Lan","year":"2024","journal-title":"Sci. Total Environ."},{"key":"ref_28","first-page":"5483","article-title":"Characteristics of Water-Soluble Inorganic Ions and their Impacts on PM2.5 Pollution Events in Mianyang, Southwest China","volume":"32","author":"An","year":"2023","journal-title":"Pol. J. Environ. Stud."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"e2021JD036167","DOI":"10.1029\/2021JD036167","article-title":"Formation of Secondary Nitroaromatic Compounds in Polluted Urban Environments","volume":"127","author":"Cai","year":"2022","journal-title":"J. Geophys. Res.-Atmos."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"e2022JD037130","DOI":"10.1029\/2022JD037130","article-title":"Atmospheric Nitrated Phenolic Compounds in Particle, Gaseous, and Aqueous Phases During Cloud Events at a Mountain Site in North China: Distribution Characteristics and Aqueous-Phase Formation","volume":"127","author":"Li","year":"2022","journal-title":"J. Geophys. Res.-Atmos."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"117712","DOI":"10.1016\/j.atmosenv.2020.117712","article-title":"Characterizing chemical composition and light absorption of nitroaromatic compounds in the winter of Beijing","volume":"237","author":"Li","year":"2020","journal-title":"Atmos. Environ."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"118046","DOI":"10.1016\/j.atmosenv.2020.118046","article-title":"Characterization of nitroaromatic compounds in atmospheric particulate matter from Beijing","volume":"246","author":"Wang","year":"2021","journal-title":"Atmos. Environ."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"126256","DOI":"10.1016\/j.chemosphere.2020.126256","article-title":"Size distributions of nitrated phenols in winter at a coastal site in north China and the impacts from primary sources and secondary formation","volume":"250","author":"Liang","year":"2020","journal-title":"Chemosphere"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"136760","DOI":"10.1016\/j.scitotenv.2020.136760","article-title":"Nitrated phenols and the phenolic precursors in the atmosphere in urban Jinan, China","volume":"714","author":"Li","year":"2020","journal-title":"Sci. Total Environ."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Huang, J., Cai, A., Wang, W., He, K., Zou, S., and Ma, Q. (2024). The Variation in Chemical Composition and Source Apportionment of PM2.5 before, during, and after COVID-19 Restrictions in Zhengzhou, China. Toxics, 12.","DOI":"10.3390\/toxics12010081"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1016\/j.egyr.2021.11.129","article-title":"Chlorine emission characteristics and control status of coal-fired units","volume":"8","author":"Zhou","year":"2022","journal-title":"Energy Rep."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"134550","DOI":"10.1016\/j.jhazmat.2024.134550","article-title":"Long-term source apportionment of PM2.5 across the contiguous United States (2000\u20132019) using a multilinear engine model","volume":"472","author":"Zhu","year":"2024","journal-title":"J. Hazard. Mater."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"120070","DOI":"10.1016\/j.envpol.2022.120070","article-title":"Emissions and light absorption of PM2.5-bound nitrated aromatic compounds from on-road vehicle fleets","volume":"312","author":"Zhang","year":"2022","journal-title":"Environ. Pollut."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"5129","DOI":"10.5194\/acp-20-5129-2020","article-title":"Characterization of the light-absorbing properties, chromophore composition and sources of brown carbon aerosol in Xi\u2019an, northwestern China","volume":"20","author":"Yuan","year":"2020","journal-title":"Atmos. Chem. Phys."}],"container-title":["Toxics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2305-6304\/13\/2\/124\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T16:27:57Z","timestamp":1760027277000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2305-6304\/13\/2\/124"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,2,6]]},"references-count":39,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2025,2]]}},"alternative-id":["toxics13020124"],"URL":"https:\/\/doi.org\/10.3390\/toxics13020124","relation":{},"ISSN":["2305-6304"],"issn-type":[{"value":"2305-6304","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,2,6]]}}}