气象要素对近地层臭氧污染形成的影响研究

Study on the Impact of Meteorological Elements on the Formation of Near Surface Ozone Pollution

近地层臭氧(O_(3))是对人体健康和植被生长有害的重要污染物,O_(3)的形成受气象条件(扩散、稀释等物理过程)、化学反应生成/去除速率和源排放强度的共同影响。以山东省临沂市为研究区,根据2019—2022年的O_(3)历史监测数据及气象资料,深入分析温度、相对湿度、风速、降水量和风向等气象要素的不同区间下近地层O_(3)的变化特征,明确气象要素对O_(3)前体物挥发性有机物(Volatile Organic Compounds,VOCs)浓度的影响。研究结果表明,O_(3)浓度与温度呈正相关,与相对湿度、降水和风速呈负相关。平均温度介于25~30℃,日最大温度大于35℃,温差大于8℃时,O_(3)浓度最容易超标,平均温度、日最大温度和温差均能指示O_(3)超标现象,但温差与日最大温度的影响比较明显。当温度为25~35℃,相对湿度为40%~60%时,临沂市O_(3)浓度易出现高值。温度和相对湿度对VOCs存在相反的影响。当风速小于2 m/s时,VOCs浓度最高。随着风速的逐渐增加,VOCs浓度逐渐减小。当临沂市盛行偏南风且风速为6~8 m/s时,要格外注意O_(3)的污染动向。研究成果有助于理解O_(3)在大气中的传输扩散、化学反应过程,并可以用来初步判断O_(3)来源,为城市O_(3)来源解析提供支撑。

The near surface ozone(O_(3))is an important pollutant that is harmful to human health and vegetation growth,and the formation of O_(3)is influenced by meteorological conditions(diffusion,dilution,and other physical processes),chemical reaction generation/removal rates,and source emission intensity.Taking Linyi city,Shandong province as the research area,based on historical monitoring data and meteorological data of O_(3)from 2019 to 2022,the variation characteristics of near surface O_(3)is deeply analyzed in different intervals of meteorological elements such as temperature,relative humidity,wind speed,precipitation,and wind direction,and the influence of meteorological elements is clarified on the concentration of Volatile Organic Compounds(VOCs)in O_(3)precursors.The research results indicate that O_(3)concentration is positively correlated with temperature and negatively correlated with relative humidity,precipitation,and wind speed.When the average temperature is 25~30℃,the daily maximum temperature is greater than 35℃,and the temperature difference is greater than 8℃,the O_(3)concentration is most likely to exceed the standard,and the average temperature,daily maximum temperature,and temperature difference can all indicate the phenomenon of O_(3)exceeding the standard,but the influence of temperature difference and daily maximum temperature is more obvious.When the temperature is 25~35℃and the relative humidity is 40%~60%,the O_(3)concentration in Linyi city is prone to high values,and temperature and relative humidity have opposite effects on VOCs.When the wind speed is less than 2 m/s,the concentration of VOCs is highest.As the wind speed gradually increases,the concentration of VOCs gradually decreases.When southerly winds prevail in Linyi city with wind speeds of 6~8 m/s,special attention should be paid to the pollution trend of O_(3).The research results contribute to understanding the transport,diffusion,and chemical reaction processes of O_(3)in the atmosphere,and can be used to preliminarily determine the source of O_(3),providing support for the analysis of O_(3)sources in cities.