上海市路边环境空气黑碳气溶胶污染特征及影响因素研究

为研究上海市路边环境空气黑碳(BC)的污染特征,采用连续监测方法对2016年1月至2018年12月上海市路边环境空气BC浓度进行了监测,并同步监测了气象因子,分析了BC的时间变化特征,探讨了气象因素对BC的影响以及不同空气质量等级下BC浓度水平。结果表明:2016、2017、2018年上海市路边环境空气BC年均质量浓度分别为(2 908±2 189)、(2 959±2 224)、(2 824±2 002) ng/m3,呈现出下降趋势;2016、2017、2018年BC与PM2.5年均质量浓度比分别为9. 30%、9. 20%、9. 50%;BC季节变化特征明显,整体表现为春夏高、秋冬低的特点;昼夜变化特征均呈现出双峰分布,第一个峰值均出现在06:00,第二个峰值均出现在16:00-19:00,且第一个峰值高于第二个峰值。气象因素对BC有一定影响,在降水、相对湿度低以及非静风条件下BC浓度较低。随着上海市空气质量由好转差,上海市路边环境空气BC浓度均呈现上升趋势,空气质量为良、轻度污染、中度污染、重度污染时路边环境空气BC平均浓度分别较空气质量为优时增加了0. 38、0. 96、1. 61、1. 96倍。

Study on Characteristics and Influencing Factors of Black Carbon Aerosol Concentration in Roadside Ambient Air of Shanghai

In order to study the pollution characteristics of Black Carbon (BC) in the roadside environment of Shanghai,the BC concentration in the roadside environment of Shanghai from January 2016 to December 2018 was monitored by continuous monitoring method,and the meteorological factors were simultaneously monitored. The time variation characteristics of BC,the influence of meteorological factors on BC,and the concentration level of BC under different air quality grades were analyzed. The results showed that the annual average concentrations of BC were (2908 ± 2189), (2959 ± 2224), (2824 ± 20020) ng/m3,respectively,showing a decreasing trend from 2016 to 2018. The average ratios of BC/PM2.5 were 9. 3%,9. 2% and 9. 5% during the monitoring period,respectively. The BC of roadside ambient air in Shanghai had obvious seasonal variation characteristic,which was higher in spring and summer,but lower in autumn and winter. Its diurnal variation showed a"double peak"structure,with the first peak appearing at 6: 00 and the second peak appearing between 16: 00 and 19: 00,and the first peak was higher than the second peak. Meteorological factors also had a greater impact on BC. With precipitation,low relative humidity and non-static wind conditions,BC prone to show low concentrations. With the decrease of air quality grade in Shanghai,the concentration of BC in roadside air in Shanghai was on the rise. Compared with BC concentration at excellent air quality,the concentration of BC in roadside environment increased 0. 38,0. 96,1. 61 and 1. 96 times respectively,when the air quality was good,light,moderately polluted and heavily polluted.