Characteristics and Formation Mechanisms of Fine Particulate Nitrate in Typical Urban Areas in China
Characteristics and Formation Mechanisms of Fine Particulate Nitrate in Typical Urban Areas in China
复制标题
我国典型城市地区细颗粒物硝酸盐特征及形成机制
DOI：
10.3390/atmos8030062
复制
发表时间：
2017-03-01
期刊：
影响因子：
2.9
通讯作者：
Chen, Mindong
中科院分区：
文献类型：
--
作者：
Ge, Xinlei;He, Yanan;Chen, Mindong
硝酸盐是一种非常重要的气溶胶成分，阐明其特性及其形成机制对有效减少气溶胶污染至关重要。本文利用Aerodyne气溶胶质谱仪（AMS）在南京、北京和兰州夏季和冬季测量的高时间分辨亚微米气溶胶（PM1）数据，研究了中国城市空气中硝酸盐的行为。结果表明，硝酸盐占PM1质量的1/8 ~ 1/4，明显高于农村和偏远地区。不同污染水平下硝酸盐的相对质量分数也有显著差异。夏季硝态氮质量分数总体上随PM1负荷的增加而增加，冬季硝态氮质量分数的贡献随污染水平的增加先增加后降低。我们进一步提出至少有三种机制可能控制城市硝酸盐的行为：热力学驱动型，光化学驱动型和行星边界层（PBL）动力学驱动型。对硫酸铵-硝酸铵数据的分析表明，在一些城市地区，硝酸铵能够在硫酸完全中和之前形成。我们的研究结果为表征和减少细颗粒物硝酸盐污染提供了有用的见解。
Nitrate is a very important aerosol component, thus elucidation of its characteristics and formation mechanisms is essential and important for effective reduction of aerosol pollution. In this work, highly time-resolved submicron aerosol (PM1) data measured by Aerodyne aerosol mass spectrometers (AMS) in Nanjing, Beijing and Lanzhou during both summer and winter were integrated to investigate the nitrate behaviors in urban China air. Results showed that nitrate occupied 1/8-1/4 of PM1 mass, typically higher than those observed in rural/remote regions. Relative mass fractions of nitrate also varied significantly at different pollution levels. Nitrate mass fractions generally increased with the increase of PM1 loadings during summer, while the contributions during winter increased first and then decreased with the increase of pollution levels. We further propose that there are at least three mechanisms that likely govern the urban nitrate behaviors: Type Ithermodynamics driven, Type IIphotochemistry driven, and Type IIIplanetary boundary layer (PBL) dynamics driven. Analyses of the ammonium-sulfate-nitrate data revealed that ammonium nitrate was able to form before sulfuric acid was fully neutralized in some urban areas. Our findings provide useful insights into the characterization and reduction of fine particulate nitrate pollution.