| 华北地区乡村站点(曲周)夏季PM2.5中二次无机组分的生成机制与来源解析 |
| 摘要点击 3045 全文点击 1517 投稿时间：2015-02-15 修订日期：2015-04-08 |
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| 中文关键词 GAC-IC 水溶性离子 气粒转化 来源 PM2.5 曲周 |
| 英文关键词 GAC-IC water-soluble ions gas to particle conversation sources PM2.5 Quzhou |
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| 中文摘要 |
| 利用大气PM2.5水溶性组分及其气态前体物在线测量系统(GAC-IC)于2014年6月9日~7月11日对华北地区乡村站点曲周大气PM2.5中水溶性组分及其气态前体物进行了在线测量,分析了PM2.5中水溶性组分与气态前体物日变化规律及其相互作用,探讨了当地细颗粒物的气粒转化机制并分析了其来源. 结果表明夏季曲周大气PM2.5中水溶性无机离子与相关气态前体物的浓度呈现明显的日变化规律. 观测期间,PM2.5中SO42-、NH4+和NO3-的平均浓度分别是26.28、18.08和16.36 μg·m-3,是PM2.5中最主要的水溶性无机离子,约占PM2.5质量浓度的76.23%;气态前体物中,NH3浓度明显偏高、平均值为44.85 μg·m-3,主要来源于当地的农业活动排放;硫氧化率(SOR)和氮氧化率(NOR)平均值分别是0.60和0.30,表现出明显的二次污染特征. 经相关性分析发现: 曲周大气PM2.5中NH4+与NO3-、SO42-有良好的相关性,且表现为富氨状态,NH4+以(NH4)2SO4形式存在,NO3-的生成主要受HNO3的限制. 对NH4NO3平衡进行研究发现: 与夜间相反,白天曲周大气环境不利于NH4NO3生成和保持. 结果也表明, 二次转化是曲周夏季细颗粒物的主要来源,堆肥与农田释放的NH3是导致高浓度二次无机颗粒物(SNA)的重要因素. |
| 英文摘要 |
| Simultaneously on-line measurements of major water-soluble inorganic ions and gaseous pollutants were performed from June 9 to July 11,2014 at Quzhou, an agriculture site in the North China Plain using a gas-aerosol collector(GAC) and ion chromatograph(IC), aiming to track the diurnal variation rule of secondary inorganic components and gas-phase precursors as well as their interactions.The transformation mechanism and sources of fine particles (PM2.5) were also discussed.The results showed that these water-soluble ions in PM2.5 and their gas-phase precursors varied regularly.As the dominant ionic components of PM2.5(accounting for 76.23%), the average concentrations of SO42-, NH4+, NO3- were 26.28 μg·m-3, 18.08 μg·m-3 and 16.36 μg·m-3 respectively.Among the precursor gases, the NH3, generated from the discharges of local agricultural activities, displayed a significantly higher concentration at an average value of 44.85 μg·m-3.The average fine sulfate and nitrate oxidation ratios (SOR and NOR) were SOR=0.60, NOR=0.30, revealing the remarkable characteristics of secondary pollution.As could be found from the relevant analysis, the NH4+ of Quzhou showed well relations with NO3- and SO42-, and the environment here was rich of ammonia.The NH4+ existed in the form of (NH4)2SO4 and the generation of NO3- was limited by the HNO3.From the analysis for the equilibrium of NH4NO3, we observed that the atmospheric environment of Quzhou was adverse to the generation and maintenance of NH4NO3 during the daytime,in contrast with the night.Integrated with the study, the results displayed that the secondary transformation was the main source of fine particles in Quzhou, and the NH3 from field and compost was the significant factor leading to the high value of S-N-A. |
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