Yi-Jun Yu, Min Zhuang, Zhen Wang, Kai-Ji Li, Wei-Fen Yang
{"title":"[Role of Ammonia in Aerosol Liquid Water, pH, and Secondary Inorganic Aerosols Formation at an Ammonia-rich City in Changzhou].","authors":"Yi-Jun Yu, Min Zhuang, Zhen Wang, Kai-Ji Li, Wei-Fen Yang","doi":"10.13227/j.hjkx.202309100","DOIUrl":null,"url":null,"abstract":"<p><p>Ammonia (NH<sub>3</sub>) is an important alkaline reactive nitrogen, which, as a precursor of fine particulate matter, raises public health issues. In this study, online NH<sub>3</sub>, SO<sub>2</sub>, NO<sub>2</sub>, PM<sub>2.5</sub>, and its water-soluble inorganic ions were detected to deduce the influence of NH<sub>3</sub> on aerosol liquid water content (AWC) and aerosol pH, including the formation of water-soluble secondary ions in PM<sub>2.5</sub> in winter in Changzhou, an ammonia-rich city in the Yangtze River Delta area in winter. The results showed that NH<sub>4</sub><sup>+</sup> mainly existed in the form of NH<sub>4</sub>NO<sub>3</sub> and (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>, and the remaining NH<sub>4</sub><sup>+</sup> existed as NH<sub>4</sub>Cl. Owing to the NH<sub>3</sub>-NH<sub>4</sub><sup>+</sup> buffer system, the aerosol pH values were found at 4.2 ± 0.4, which was positively correlated with the NH<sub>3</sub> content. The aerosol pH value variation narrowed with the increase in PM<sub>2.5</sub> concentration and tended to be between 4 to 5. AWC increased exponentially with the increase in humidity and SNA content, among which NH<sub>4</sub>NO<sub>3</sub>, (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>, and NH<sub>4</sub>Cl contributed 58.5%, 18.4%, and 8.3%, respectively, due to their hygroscopicity. Aerosol pH, AWC, and NH<sub>3</sub>-NH<sub>4</sub><sup>+</sup> conversion promoted the gas-to-particle conversion of SO<sub>2</sub> and NO<sub>2</sub>. In Changzhou, rich NH<sub>3</sub>-NH<sub>4</sub><sup>+</sup> were found to maintain relatively high pH values, push up AWC, and promote the heterogeneous reaction of SO<sub>2</sub>, whereas NO<sub>3</sub><sup>-</sup> generation was dominated by a homogeneous reaction, which was accelerated by NH<sub>3</sub>. According to the simulation results, relatively noticeable changes in aerosol pH and AWC could be found by the reduction of up to 30% of NH<sub>3</sub>.</p>","PeriodicalId":35937,"journal":{"name":"Huanjing Kexue/Environmental Science","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Huanjing Kexue/Environmental Science","FirstCategoryId":"1087","ListUrlMain":"https://doi.org/10.13227/j.hjkx.202309100","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"Environmental Science","Score":null,"Total":0}
引用次数: 0
Abstract
Ammonia (NH3) is an important alkaline reactive nitrogen, which, as a precursor of fine particulate matter, raises public health issues. In this study, online NH3, SO2, NO2, PM2.5, and its water-soluble inorganic ions were detected to deduce the influence of NH3 on aerosol liquid water content (AWC) and aerosol pH, including the formation of water-soluble secondary ions in PM2.5 in winter in Changzhou, an ammonia-rich city in the Yangtze River Delta area in winter. The results showed that NH4+ mainly existed in the form of NH4NO3 and (NH4)2SO4, and the remaining NH4+ existed as NH4Cl. Owing to the NH3-NH4+ buffer system, the aerosol pH values were found at 4.2 ± 0.4, which was positively correlated with the NH3 content. The aerosol pH value variation narrowed with the increase in PM2.5 concentration and tended to be between 4 to 5. AWC increased exponentially with the increase in humidity and SNA content, among which NH4NO3, (NH4)2SO4, and NH4Cl contributed 58.5%, 18.4%, and 8.3%, respectively, due to their hygroscopicity. Aerosol pH, AWC, and NH3-NH4+ conversion promoted the gas-to-particle conversion of SO2 and NO2. In Changzhou, rich NH3-NH4+ were found to maintain relatively high pH values, push up AWC, and promote the heterogeneous reaction of SO2, whereas NO3- generation was dominated by a homogeneous reaction, which was accelerated by NH3. According to the simulation results, relatively noticeable changes in aerosol pH and AWC could be found by the reduction of up to 30% of NH3.