| 富氨对常州PM2.5理化性质与二次反应的影响 |
| 摘要点击 2108 全文点击 455 投稿时间：2023-09-12 修订日期：2023-11-21 |
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| 中文关键词 氨（NH3） 铵（NH4+） 气粒转化 气溶胶含水量（AWC） 气溶胶酸度 |
| 英文关键词 NH3 NH4+ gas-to-particle conversion aerosol water content（AWC） aerosol acidity |
| DOI 10.13227/j.hjkx.20240812 |
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| 中文摘要 |
| NH3是PM2.5重要前体物,并影响其理化性质.基于2021年12月至2022年2月江苏常州NH3、 SO2、 NO2、 PM2.5及其水溶性离子在线观测,结合热力学平衡模型计算气溶胶酸度和气溶胶含水量（AWC）,分析了富氨条件下NH3-NH4+转化对AWC、酸度及二次反应的影响.结果表明,2021年冬季常州为富氨,富余程度随PM2.5浓度升高而加强,NH4+以NH4NO3和（NH4）2SO4为主,多数时段有少量NH4Cl.气溶胶呈中等酸度,pH均值4.2 ± 0.4,与大气NH3浓度正相关,pH值变幅随污染升级收窄趋中至4~5之间；AWC随湿度和颗粒物二次离子浓度升高而指数级攀升,主要由NH4NO3、 （NH4）2SO4和NH4Cl吸湿贡献,占比分别为58.5%、 18.4%和8.3%,污染条件下NH4NO3主导颗粒物吸湿增长. NH3-NH4+促进SO2非均相反应和NO3-均相反应生成.因富氨环境,需降低30%以上NH3方可影响pH值和含水量等理化性质.该结果对理解二次反应影响、支撑当地空气质量改善提供了参考. |
| 英文摘要 |
| 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. |
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