Efficient Heterogeneous Formation of Ammonium Nitrate on the Saline Mineral Particle Surface in the Atmosphere of East Asia during Dust Storm Periods.
Efficient Heterogeneous Formation of Ammonium Nitrate on the Saline Mineral Particle Surface in the Atmosphere of East Asia during Dust Storm Periods.
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DOI：
10.1021/acs.est.0c04544
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发表时间：
2020-11
影响因子：
11.4
通讯作者：
Can Wu;Shenmin Zhang;Gehui Wang;Shaojun Lv;Dapeng Li;Lang Liu;Jianjun Li;Shijie Liu;W. Du-W.
中科院分区：
文献类型：
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作者：
Can Wu;Shenmin Zhang;Gehui Wang;Shaojun Lv;Dapeng Li;Lang Liu;Jianjun Li;Shijie Liu;W. Du-W.
为了了解当前东亚大气中灰尘的化学演变，研究了2019年沙尘暴事件期间中国上海PM2.5和尺寸分辨气溶胶的化学。结果表明，由于CaSO 4和Na 2SO 4的直接排放，沙尘暴期间北京市的SO 42-浓度与Ca 2+和Na+浓度呈显著正相关。相反，在事件期间，NO3-与NH 4+以接近1：1的摩尔比线性相关，并且两者几乎完全停留在粗颗粒中，这表明它们以NH 4 NO3的形式积累在尘埃表面。基于现场观测和实验室烟雾室模拟，我们发现，在沙尘期间，上海的NO2和O3反应形成N2 O 5，N2 O 5随后在盐矿物粉尘表面水解成HNO 3（例如，CaSO 4和Na 2SO 4），并进一步用NH3中和为NH 4 NO3。沙尘暴期间上海大气中NO3-和NH 4+的相对丰度明显高于10年前，表明当前东亚大气中大量共存的NOx、O3和NH3促进了NH 4 NO3在沙尘上的非均匀形成，这在未来的模拟研究中应予以考虑。
To understand the chemical evolution of dust in the current East Asian atmosphere, the chemistry of PM2.5 and size-resolved aerosols in Shanghai, China, during the 2019 dust storm event was investigated. Our results showed that concentrations of SO42- in the city during the event highly correlated with Ca2+ and Na+ due to the direct emissions of CaSO4 and Na2SO4 from the upwind deserts. In contrast, during the event, NO3- linearly correlated with NH4+ at a molar ratio close to 1:1, and both almost entirely stayed in coarse particles, suggesting they accumulated on the dust surface as NH4NO3. Based on the field observations and laboratory smog chamber simulations, we found that NO2 and O3 in Shanghai during the dust period reacted to form N2O5, which subsequently hydrolyzed into HNO3 on the surface of saline mineral dusts (e.g., CaSO4 and Na2SO4) and was further neutralized by NH3 as NH4NO3. The relative abundances of NO3- and NH4+ in Shanghai during the dust event were notably higher than those a decade ago, indicating that this heterogeneous formation of NH4NO3 on dust was enhanced by the abundantly coexisting NOx, O3, and NH3 in the current East Asian atmosphere, which should be considered in future modeling studies.