Significant factors influencing the multi-temporal-scale evolutions of PM2.5 and O3 concentrations in Xingtai City.
To reveal the evolution characteristics and influencing factors of atmospheric PM2.5-O3 complex pollution in Xingtai City,this study,based on the meteorological elements and pollutant concentration data provided by the online monitoring platform,deployed the KZ filtering method to decompose the original concentration sequences of PM2.5 and O3 in Xingtai City,and combined the multiple stepwise regression method to quantitatively identify the contribution of source emissions and meteorological factors to pollutant concentration in long-term component.Meanwhile,Random Forest method was used to qualitatively explore the effects of specific source emissions and meteorological factors on the original concentration series of PM2.5 and O3 in Xingtai City.The results showed that the long-term component of PM2.5 concentration in Xingtai City showed a significant downward trend,however,short-term component was major contributor to PM2.5 concentration.The long-term component of O3 concentration showed an increasing trend,and the seasonal component was main contributor to O3 concentration.The contribution ratio of source emissions to meteorological factors in the long-term component concentrations of PM2.5 was about 5:1,and that for O3 was close to 3.5:1.The source emission processes were the main cause of long-term atmospheric PM2.5-O3 complex pollution in Xingtai City.Relative humidity(RH)presented a significant influence on the original concentration series of PM2.5 in Xingtai City,followed by industrial source emission and vehicle exhaust emission.The three factors effectively affecting the original O3 concentration sequences were the short-wave radiation intensity(SR),temperature(T)and vehicle exhaust emission.
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