Characteristics And Influencing Factors Of Ozone Pollution In Qingdao

Ozone pollution,as another important pollutant species besides PM2.5,has shown an increase in pollution in many regions of China in recent years.In Qingdao,the study city of this thesis,the air quality has continued to improve in recent years,but the ozone pollution has been increasing year by year in the past three years,which is of great significance for the study of ozone pollution in Qingdao,a typical coastal city.In this study,based on the application of mathematical and statistical analysis,the hourly ozone monitoring data from 23 air quality monitoring stations in Qingdao in2020 were analyzed,the precursors VOCs and NOx and meteorological elements such as temperature,humidity,wind speed and direction were correlated,the characteristic ratio method(X/E)was used to determine the aging degree of air masses,and the backward trajectory model(HYSPLIT)and potential source analysis model(PSCF)to analyze the sources of air masses during the pollution period,the ratio of VOCs/NOx based on the characteristic curve of EKMA to determine the sensitivity of ozone generation during the pollution period,and the positive matrix factor model(PMF)to analyze the sources and contributions of VOCs in Qingdao.The results show that the high ozone concentrations in Qingdao are concentrated in April-September,the ozone concentrations are higher in spring and summer than in autumn and winter,the hourly variation is "single-peak",the maximum ozone concentration occurs at 13:00-14:00,and the spatial distribution has obvious seasonal differences,showing that the concentrations are lower in the central area and higher in Laoshan and The concentration in the central area is lower,the southeast coastal Laoshan and south of the city is higher,and the overall ozone concentration in coastal sites is higher than that in urban areas.September 4-6 typical ozone pollution process shows that this pollution is influenced by transmission from the sea,4 mainly by urban transmission in Shandong Province and Beijing-Tianjin-Hebei region;5 is mainly influenced by Jiangsu Province,the contribution of local generation is relatively low;6 is dominated by local generation;the entire pollution process are in VOCs sensitive.The comprehensive analysis results of the causes of ozone pollution in Qingdao show that from May to September 2020,the concentration of VOCs in Qingdao was28.85 ppb,and the ozone formation potential of olefins was the largest,accounting for37.10%,and butene,n-butane and propylene were the three species with the highest potential for ozone generation.VOCs are greatly affected by LPG volatilization sources(31.1%),fixed combustion sources(22.6%),and mobile sources(20.6%),and the use of LPG is the control point of Qingdao atmospheric VOCs.Ozone concentration and temperature are positively correlated,and relative humidity,wind speed show a negative correlation,when the temperature is higher than 30 °C,humidity is less than60% when the ozone high value.The results of backward air flow trajectory clustering show that low air masses from the southeast and southwest directions have a greater impact on the concentration of Qingdao in summer,and regional transmission has a greater contribution to the ozone concentration in Qingdao,so the "one city,one policy" ozone pollution prevention and control action should be carried out for surrounding cities,and the regional joint prevention and control work should be done around ozone control.