Abstract：
Nitrate (NO3-) is a major component of atmospheric fine particles. Recent studies in eastern China have shown the increasing trend of NO3- in contrast to the ongoing control of nitrogen oxide (NOx). Here, we elucidate the effects of reduced sulfur dioxide (SO2) on the enhancement of NO3- formation based on field measurements at the summit of Mt. Tai (1534 m a.s.l.) and present detailed modelling analyses. From 2007 to 2018, the measured springtime concentrations of various primary pollutants and fine sulfate (SO42-) decreased sharply (-16.4 % to -89.7 %), whereas fine NO3- concentration increased by 22.8 %. The elevated NO3- levels cannot be explained by the changes in meteorological conditions or other related parameters but were primarily attributed to the considerable reduction in SO42- concentrations (-73.4 %). Results from a multi-phase chemical box model indicated that the reduced SO42- levels decreased the aerosol acidity and prompted the partitioning of HNO3 into the aerosol phase. WRF-Chem model analyses suggest that such a negative effect is a regional phenomenon throughout the planetary boundary layer over eastern China in spring. This study provides new insights into the worsening situation of NO3- aerosol pollution and has important implications for controlling haze pollution in China.
摘要：
硝酸盐(NO3-)是大气细颗粒物的主要成分。最近在中国东部的研究表明，与持续控制氮氧化物（NOx）相比，NO3-呈增加趋势。这里,根据在山顶的现场测量，我们阐明了减少的二氧化硫（SO2）对增强NO3-形成的影响。泰(1534ma.s.l.)并提供详细的建模分析。从2007年到2018年，各种主要污染物和细硫酸盐（SO42-）的实测春季浓度急剧下降（-16.4％至-89.7％），而细NO3-浓度增加了22.8%。升高的NO3-水平不能通过气象条件或其他相关参数的变化来解释，但主要归因于SO42-浓度的显着降低（-73.4％）。多相化学盒模型的结果表明，降低的SO42-水平降低了气溶胶酸度，并促使HNO3分配到气溶胶相中。WRF-Chem模型分析表明，这种负面影响是春季整个中国东部行星边界层的区域现象。该研究为NO3-气溶胶污染的恶化提供了新的见解，对控制中国的雾霾污染具有重要意义。
