近年山东德州PM_(2.5)和O_(3)相互作用的季节变化及其机理分析

Analysis on seasonal changes with the mechanisms of interaction between PM_(2.5) and O_(3) in Dezhou,Shandong Province over recent years

为全面认识减排过程中华北平原城市大气复合型污染变化特征,本文利用最近6年(2017-2022)山东省德州市环境-气象监测资料,分析关键大气复合污染物PM_(2.5)和O_(3)的季节特征及其相互作用,探究东亚季风气候背景下冬夏季PM_(2.5)和O_(3)的相互作用机理.德州市近6年城市环境PM_(2.5)和O_(3)超标率分别为20.22%和23.56%,O_(3)污染凸显.环境大气PM_(2.5)和O_(3)在夏季表现为显著正相关,相关系数高达0.53(p<0.01),而冬季则呈显著负相关,相关系数为-0.30 (p<0.01),两者具有明显“夏正冬负”的相反季节变化特征.环境气象机理分析表明,夏季高温及强太阳辐射的气象条件促进光化学反应生成O_(3),加大大气氧化性的增强二次颗粒物生成,导致PM_(2.5)浓度升高;冬季低温及弱太阳辐射气象背景下,高浓度PM_(2.5)的局地累积显著削弱太阳辐射,抑制大气O_(3)光化学生成,降低环境大气O_(3)水平.

To comprehensively understand the variations of atmospheric compound pollution(ACP)in urban areas over the North China Plain,this paper investigates the changes of major ACP pollutants PM_(2.5) and O_(3) with their interactions over the period of emission reduction in 2017—2022 by analyzing the environmental and meteorological data in Dezhou City,Shandong Province,and we explores the underlying mechanism of PM_(2.5) and O_(3) interaction in winter and summer of East Asian monsoon climate.The exceedance rates of ambient PM_(2.5) and O_(3) pollution in Dezhou over the past six years were 20.22%and 23.56%,respectively with prominent O_(3) pollution.The correlation analysis of PM_(2.5) and O_(3) showed that the correlation coefficient was as high as 0.53(p<0.01)in summer with a significant positive correlation,while the correlation coefficient was-0.30(p<0.01)in winter,presenting a significant negative correlation,which indicates a distinct seasonal shift of"positive summer and negative winter"in the interaction of PM_(2.5) and O_(3).Based on the analysis of environmental and meteorological data it is revealed that the high air temperature and strong solar radiation in summer could enhance the photochemical productions and strengthen the atmospheric oxidization,promoting the generation of secondary particulate matter for increasing PM_(2.5) concentrations.Under the wintertime meteorological conditions of low air temperature and the weak solar radiation and high PM_(2.5) accumulations in winter could largely weaken solar radiation inhibiting atmospheric photochemical production,resulting in lower O_(3) concentrations.