合肥市冬季细颗粒物中碳组分特征分析

Analysis of Carbon Composition Characteristics of Fine Particulate Matter in Winter in Hefei

利用2020年12月1日至2021年2月28日合肥市细颗粒物(PM_(2.5))、有机碳(OC)和元素碳(EC)等环境空气质量监测数据和气象观测数据,分析了合肥市大气PM_(2.5)中OC和EC的污染特征,并探讨了其来源以及气象因素影响。结果表明:合肥市冬季碳质气溶胶是PM_(2.5)中主要组分,随着污染程度的加重,碳质气溶胶的质量浓度逐步增加,但其在PM_(2.5)中的占比先减小后增加。在以PM_(2.5)为首要污染物的不同污染级别天气条件下,OC和EC的相关性说明不同程度下碳质气溶胶来源复杂。OC/EC表明机动车尾气和燃煤源排放是碳质气溶胶的主要来源。二次有机碳(SOC)会随着污染程度的加重而呈现升高趋势。OC和EC在冬季受温度影响较小;较大的相对湿度对OC和EC具有一定的清除作用,明显降水或连续降水的清除作用更加显著;而风速对含碳气溶胶的影响主要出现在污染天气背景下。

Using the air quality monitoring data of PM_(2.5),organic carbon(OC),elemental carbon(EC) and meteorological observation data,the characteristics and sources of OC and EC were analyzed and the influence of meteorological factors were investigated in Hefei from December 1,2020 to February 28,2021.The results showed that carbonaceous aerosol was the main component of PM_(2.5) in Hefei in winter.And the mass concentration of carbonaceous aerosol increased gradually with the pollution level increasing,but its proportion in PM_(2.5) was on the contrary;The correlation between OC and EC under different pollution levels with PM_(2.5) as the primary pollutant,which indicates the sources of carbonaceous aerosols were complex.The ratio of OC/EC indicated that vehicle exhaust and coal combustion emissions were the main sources of carbonaceous aerosol.The concentration of secondary organic carbon(SOC) increased with the aggravation of pollution;OC and EC were not significantly affected by temperature in winter.However high relative humidity had a certain scavenging efficiency on OC and EC.The wet deposition efficiency of high precipitation or continuous precipitation was more obvious.The influence of high wind speed on carbonaceous aerosol was also significant.