济南市区黑碳污染变化特征及来源解析OA北大核心CSTPCD

Black Carbon(BC)is a significant contributor to fine particulate matter(PM2.5)pollution,necessitating thorough investigation into its variation characteristics and sources for effective PM2.5 control.We used a Magee Aethalometer AE33 to conduct online continuous observations of BC concentration at the central station(1#)in the urban area of Jinan,from January 2020 to December 2021,to study the characteristics and sources of atmospheric BC particulate pollution.Synchronous online observations of PM2.5,nitrogen oxides(NOx),and carbon monoxide(CO)mass concentrations were also undertaken to obtain the characteristics of BC concentration changes in the urban area,explore the relationship between BC and major atmospheric pollutants,and quantitatively analyze daily variation of BC emission sources in the urban area of Jinan,based on BC monitoring at the provincial central station(2#).Additionally,typical pollution process was selected to study the transport effects of BC from different emission sources.Average BC mass concentration at 1#was(1.86±1.21)μg·m-3,exhibiting positive correlations with PM2.5 and CO.BC concentration showed distinct annual,seasonal,daily,and weekly variations,with a 14%decrease observed in 2021 compared to 2020.The BC mass concentrations were lowest in spring(1.47±0.51)μg·m-3,followed by summer(1.60±0.43)μg·m-3,autumn(1.99±0.77)μg·m-3,and winter(2.48±1.17)μg·m-3.The BC was affected by the morning and evening rush hours of traffic,showing a double-peak in daily concentrations.The concentration was higher on weekends than weekdays in spring and summer,with an apparent"weekend effect".Source analysis results showed that traffic emissions were the main source of BC.The average proportion of BC traffic sources(BCtraffic/BC)in 2020 and 2021 was highest in summer(0.81),followed by autumn(0.79),spring(0.76),and winter(0.67).Patterns of daily variation of BCtraffic in different seasons also confirmed that traffic played a dominant role as a source of BC.The changes of 2#station were similar to those of 1#station,but the BC concentrations were usually higher than that of 1#station due to the influence of traffic flow and industrial sources.During typical PM2.5 pollution periods,BC was affected not only by local emission sources,but also by transportation impacts from northern Jinan,Dezhou City,and Hengshui City in Hebei Province.The influence of wind fields on BCtraffic and BCnontraffic concentrations showed that the surrounding sources were the main emission sources at this site.BCtraffic was significantly affected by emissions from busy road sections,including the tourist road tunnel in the southwest direction and the Shunhua Road in the northeast direction.