南京市主城区NO_(2)重污染工作日和节假日的变化差异及原因

Differences and causes of NO_(2) variation in workdays and holidays under heavy pollution in the main urban area of Nanjing

基于2017—2019年南京市主城区空气质量自动监测站NO_(2)小时浓度数据和交通道路数据,统计分析了重污染情况下工作日和节假日NO_(2)的日变化差异,并进一步分析原因。结果表明:(1)工作日和节假日的日变化特征有明显差异,工作日呈现“双峰”现象,日峰值出现于10:00左右,夜峰值出现于21:00左右;节假日呈现“单峰”现象,没有日峰值,夜峰值出现于20:00左右。(2)工作日白天NO_(2)浓度整体高于节假日。(3)工作日NO_(2)小时浓度的“早高峰”现象主要受400 m内道路密度影响,道路密度越大,“早高峰”现象越明显。

Based on the NO_(2) hourly concentration data of the air quality automatic monitoring stations in the main urban area of Nanjing from 2017 to 2019 and the traffic road data,statistical analysis of the daily variation of NO_(2) on workdays and holidays under heavy pollution was conducted.The causes were further analyzed.Results showed that:(1)there existed significant difference between workdays and holidays for NO_(2) daily variation.The NO_(2) hourly concentration in workdays presented two peaks with day peak at about 10:00 and night peak at about 21:00.The NO_(2) hourly concentration in holidays presented a single peak with night peak at about 20:00 but without day peak.(2)The NO_(2) concentration in workdays was generally higher than that in holidays.(3)The“morning peak”of NO_(2) hourly concentration was significantly affected by road density in 400 m reach.The denser the road density,the more obvious the“morning peak”of NO_(2) hourly concentration.