邢台市影响PM_(2.5)和O_(3)浓度多时间尺度演变的重要因素

Significant factors influencing the multi-temporal-scale evolutions of PM_(2.5) and O_(3) concentrations in Xingtai City

为了揭示邢台市大气PM_(2.5)-O_(3)复合污染的演变特征及其影响因素,基于在线监测平台提供的气象要素及污染物浓度数据,使用KZ滤波法分解邢台市PM_(2.5)和O_(3)的原始浓度序列,之后将多元逐步回归法与KZ滤波法结合定量识别污染物的长期分量中源排放及气象因素对污染物浓度的贡献.同时使用随机森林方法,定性探究具体的源排放和气象因子对于邢台市PM_(2.5)和O_(3)原始序列浓度的影响.结果表明:邢台市PM_(2.5)浓度的长期分量呈现显著的下降趋势,短期分量是PM_(2.5)浓度的主要贡献者.O_(3)浓度长期分量呈现增加的趋势,季节分量是O_(3)浓度的主要贡献者.源排放和气象因素对PM_(2.5)长期分量浓度变化的贡献占比约为5:1,两者对于O_(3)长期分量浓度变化贡献占比接近3.5:1,源排放过程是邢台市长期大气PM_(2.5)-O_(3)复合污染的主因.相对湿度(RH)对邢台市PM_(2.5)原始序列浓度的影响最大,其次为工业源排放和机动车尾气排放;影响O_(3)原始序列最大的的3个因子分别是气象因素中的短波辐射强度(SR)、温度(T)以及机动车尾气排放.

To reveal the evolution characteristics and influencing factors of atmospheric PM_(2.5)-O_(3) 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 PM_(2.5) and O_(3) 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 PM_(2.5) and O_(3) in Xingtai City.The results showed that the long-term component of PM_(2.5) concentration in Xingtai City showed a significant downward trend,however,short-term component was major contributor to PM_(2.5) concentration.The long-term component of O_(3) concentration showed an increasing trend,and the seasonal component was main contributor to O_(3) concentration.The contribution ratio of source emissions to meteorological factors in the long-term component concentrations of PM_(2.5) was about 5:1,and that for O_(3) was close to 3.5:1.The source emission processes were the main cause of long-term atmospheric PM_(2.5)-O_(3) complex pollution in Xingtai City.Relative humidity (RH) presented a significant influence on the original concentration series of PM_(2.5) in Xingtai City,followed by industrial source emission and vehicle exhaust emission.The three factors effectively affecting the original O_(3) concentration sequences were the short-wave radiation intensity (SR),temperature (T) and vehicle exhaust emission.