南充市城区冬季非甲烷总烃污染特征分析

Analysis of pollution characteristics of NMHC in winter of urban in Nanchong City

为了解南充市城区冬季环境空气中非甲烷总烃(NMHC)的污染特征及来源,2020年12月1日~2021年2月28日利用在线监测仪器对NMHC含量进行了连续监测。结果表明:南充市城区冬季环境空气中的NMHC总平均体积分数为(0.37±0.00)×10^(−6),元旦和春节期间的NMHC含量显著低于周末和工作日;受城区居民生产、生活和出行等日常活动规律的影响,元旦、春节、周末和工作日期间的NMHC日变化曲线虽呈“双峰双谷”型,但峰值和谷值出现的时间略有差异;NMHC含量与气温、相对湿度、气压和风速的相关性均达到显著水平,但气压对NMHC的影响最大,相对湿度次之,风速和气温对NMHC的影响最小;冬季南充市城区PM_(2.5)与NMHC同源性较高,PM_(2.5)浓度较低时,NMHC与O_(3)日变化曲线波动较小,PM_(2.5)浓度升高,NMHC和O_(3)日变化曲线波动变大,但O_(3)的生成会受到PM_(2.5)的抑制。

In order to understand the pollution characteristics and sources of NMHC in the ambient air of Nanchong City in winter,the NMHC content was continuously monitored by online monitoring instruments from December 1st,2020 to February 28th,2021.The results showed that the total average volume fraction of NMHC in the ambient air of Nanchong in winter was(0.37±0.00)×10^(−6),and the NMHC content during New Year's Day and Spring Festival was significantly lower than that on weekends and weekdays.The diurnal variations of NMHC showed a"double peaks and double valleys"during the New Year's Day,Spring Festival,weekends and weekdays.However,the time of the peak value and the valley value were different accounting for the daily activities of urban residents,such as production,living and travel.The correlations between NMHC content and air temperature,relative humidity,air pressure and wind speed all reached a significant level.The air pressure had the greatest effect on NMHC,followed by the relative humidity,and the wind speed and the air temperature had the least effect on NMHC.In winter,the homology of PM_(2.5) and NMHC in urban was high.When the concentration of PM_(2.5) was lower,the fluctuation of diurnal variation curve of NMHC and O_(3) were relatively small.With the increase of PM_(2.5) concentration,the fluctuation of diurnal variation curve of NMHC and O_(3) was increased.But,the generation of O_(3) was inhibited by PM_(2.5).