Characteristics of aerosol chemistry and acidity in Shanghai after PM2.5 satisfied national guideline: Insight into future emission control.
Characteristics of aerosol chemistry and acidity in Shanghai after PM2.5 satisfied national guideline: Insight into future emission control.
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DOI：
10.1016/j.scitotenv.2022.154319
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发表时间：
2022-03
期刊：
影响因子：
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通讯作者：
Z. Fu;L. Cheng;X. Ye;Zhen-rong Ma;R. Wang;Yusen Duan;Huo Juntao;Jianmin Chen
中科院分区：
文献类型：
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作者：
Z. Fu;L. Cheng;X. Ye;Zhen-rong Ma;R. Wang;Yusen Duan;Huo Juntao;Jianmin Chen
持续控制大气污染物排放，2019-2020年上海PM2. 5平均浓度首次达到国家二级标准（35微克m−3）。本文利用上海市中心城区2年的PM2. 5逐时分辨率数据，研究了硫酸盐和硝酸盐以及颗粒物酸度对PM2. 5的相对贡献。SO2平均浓度降至7.7 μg m−3，而NOx浓度保持在40 μg m−3以上，表明“十三五”期间SO2的控制比NOx更有效。因此，硫酸盐污染显着减少，而硝酸盐负荷几乎保持不变。各月N/S比值从低于0.6到高于2.0不等，表明机动车尾气对PM2.5的贡献具有季节性。与硫酸盐相反，硝酸盐组分随着PM2. 5质量的增加而迅速增加，这表明硝酸盐的爆炸性增长已成为灰霾形成的主要驱动因素。ISORROPIA模拟结果表明，PM2.5呈中等酸性，pH值呈现冬季>春季>秋季>夏季的趋势。硝酸盐的日变化与气溶胶含水量的变化有关，表明非均相水反应对二次气溶胶形成的影响。排放控制对无机PM2. 5的减排效果因前体物和季节的不同而不同。NH3的减排将增加颗粒物酸度和酸雨污染，但减排量大于60%时效果优于NOx。建议长三角地区应优先控制机动车尾气排放，以协调缓解PM2. 5和酸雨污染。
With continuous endeavors to control air pollutant emissions, the average concentration of PM2.5in Shanghai in 2019–2020 satisfied the national secondary standard (35 μg m−3) for the first time. In this study, the two-year dataset of hourly resolution PM2.5compositions observed in downtown Shanghai was used to investigate the relative contribution of sulfate and nitrate as well as particulate acidity. The average concentration of SO2was reduced to 7.7 μg m−3, while the concentration of NOxremained above 40 μg m−3, indicating that the control of SO2was more effective than that of NOxduring the 13th Five-Year Plan period. Thus, the sulfate pollution was significantly reduced whereas the nitrate loading remained almost constant. The monthly N/S ratio varied from below 0.6 to above 2.0, indicating that the contribution of automobile exhaust to PM2.5is seasonally dependent. Contrary to sulfate, the nitrate fraction increased rapidly with the increase of PM2.5mass, suggesting that the explosive growth of nitrate has become a major driver of haze formation. ISORROPIA simulations show that PM2.5was moderately acidic with pH values following the trend of winter > spring > autumn > summer. The diurnal variation of nitrate was related to the changes in aerosol water content, indicating the effect of heterogeneous aqueous reactions on secondary aerosol formation. The effectiveness of emission control for reducing inorganic PM2.5varied with different gas precursors and seasons. The abatement of NH3emissions will increase particle acidity and acid rain pollution, although it is more effective than that of NOxwhen the emission reduction is larger than 60%. This study suggests that the control of vehicle exhaust should be given priority in the Yangtze River Delta for coordinately mitigating PM2.5and acid rain pollution.