| 南京亚微米级颗粒物化学组成的季节变化、粒径分布和来源 |
| 摘要点击 2636 全文点击 2793 投稿时间：2022-03-23 修订日期：2022-06-02 |
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| 中文关键词 PM1.1 化学组分 季节变化 粒径分布 源解析 |
| 英文关键词 PM1.1 chemical components seasonal variation size distribution source apportionment |
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| 中文摘要 |
| 于2016~2017年不同季节在南京大学仙林校区采集分粒径的颗粒物样品，分析了粒径≤1.1 μm颗粒物（PM1.1；<0.4、0.4~0.7和0.7~1.1 μm）中水溶性离子、碳质组分和元素的浓度.结果表明，受当地扩散条件以及热不稳定组分在高温下挥发分解的影响，PM1.1、OC、NO3-、SO42-和NH4+浓度均表现出秋冬高、春夏低的特点.而元素碳在春季因工业和道路扬尘贡献的升高达到最大浓度［（1.87±0.98）μg ·m-3］.根据丰量组分间的特征比值，南京PM1.1中的阴离子由NO3-、SO42-和Cl-主导，碳质组分主要来自化石燃料燃烧及老化过程.随着温度的升高，热不稳定组分NH4+、NO3-和有机碳的粒径分布向细粒子方向移动；EC因机动车排放强度和扬尘贡献的升高粒径分布向粗粒子方向移动.由于高湿度（>70%）往往伴随着高温（>20℃）及扩散条件的改善，60%~70%的相对湿度更有利于PM1.1中二次无机离子的形成.基于PM1.1化学组分的源解析结果表明，二次形成过程［（66.6±18.3）%］和扬尘［（16.8±14.8）%］是南京PM1.1的主要贡献源，有必要进一步控制各种前体物和扬尘的排放. |
| 英文摘要 |
| Size-segregated particulate matter (PM) samples were collected in different seasons from 2016 to 2017 at the Xianlin Campus of Nanjing University. Mass concentrations of water-soluble inorganic ions, carbonaceous components, and elements were analyzed for PM with an aerodynamic diameter ≤ 1.1 μm (PM1.1; <0.4 μm, 0.4-0.7 μm, and 0.7-1.1 μm). The results showed that PM1.1, OC, NO3-, SO42-, and NH4+ exhibited higher ambient levels in fall-winter than those in spring-summer, which was attributed to the changes in local diffusion conditions, evaporation, and decomposition of non-refractory components. Elemental carbon (EC) reached its maximum concentration[(1.87±0.98) μg·m-3]in spring due to the increase in industrial and road dust resuspension. According to the characteristic ratio between bulk components, the anions in PM1.1 were dominated by NO3-, SO42-, and Cl- in Nanjing, and the carbonaceous components were mainly from fossil fuel combustions and associated aging processes. As the ambient temperature increased, the size distributions of thermo-unstable components including NH4+, NO3-, and OC shifted towards finer particles, whereas EC became more enriched in coarse particles, possibly due to the increase in emission intensity of motor vehicles and fugitive dust contributions. Since high relative humidity (>70%) is often accompanied by high temperature (>20℃) and improved diffusion conditions, a relative humidity of 60%-70% was more conducive to the formation of secondary inorganic ions in PM1.1. Source apportionment results based on the speciation data of PM1.1 showed that secondary formation processes[(66.6±18.3)%]and dust resuspension[(16.8±14.8)%]were the main contributors to PM1.1 in Nanjing, and further control of the emissions of gaseous precursors and dust is necessary. |
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