太原市城区臭氧变化特征及影响因素

Variation and the influence factors of ozone in urban area in Taiyuan

通过对太原城区环境空气质量监测站^(201)4年全年臭氧的连续观测,分析了其浓度变化特征,并结合二氧化氮的浓度以及气象数据研究了臭氧变化的影响因素.数据分析显示:太原市城区环境空气中臭氧的小时平均值为32.1μg·m^(-3),日变化总体呈现日间高(44.7μg·m^(-3))于夜间(18.0μg·m^(-3))的特点,季节变化呈夏季(67.7μg·m^(-3))高于冬季(11.1μg·m^(-3))的特征;夏季和冬季的臭氧浓度与二氧化氮、环境温度、相对湿度、能见度的相关系数分别是-0.50、0.75、-0.53、0.14和-0.38、0.32、-0.34、0.25;全年节假日的臭氧浓度比工作日高4.37%.研究结果表明,日间太阳辐射的增强和臭氧前驱物浓度的上升,臭氧浓度在15时达到峰值,此后随着太阳辐射的降低和大气化学反应消耗从而导致臭氧浓度不断降低;人为活动排放的二氧化氮是环境空气中的臭氧生成的重要前体物;温度的增加会加快臭氧的生成,相对湿度的增加有利于前驱物和大气中自由基的累积从而影响臭氧浓度,能见度的增加导致的太阳辐射能力增强会一定程度上增加臭氧的浓度,风速的增加会使臭氧出现先升后降的变化,在西南风和南风情况下臭氧的浓度最高;臭氧浓度具有一定的节假日效应.总之影响太原市城区臭氧浓度变化的主要因素是臭氧前驱物(NO_2等)和气象条件(太阳辐射、温度等)的变化,控制NO_2等臭氧前驱物的排放是控制臭氧污染的主要途径.

Annual continuous monitoring of ozone（O_3） was performed in ^（201）4 at the environmental monitor station in urban area of Taiyuan to investigate the variation and influence factors of O_3. The data showed that hourly average concentration of O_3 was 32.1 μg·m^（-3）in urban area of Taiyuan,with the diurnal variation pattern of higher O_3 in daytime（44. 7 μg·m^（-3）） and lower O_3 in nighttime（18.0 μg·m^（-3））,and the seasonal variation of higher concentrations in summer（67.7 μg·m^（-3）） and lower concentrations in winter（11.1 μg·m^（-3））. The correlation coefficients between O_3 concentration and nitrogen dioxide,temperature,relative humidity,visibility were- 0. 50,0. 75,- 0. 53,0. 14 in summer and- 0. 38,0. 32,- 0. 34,0. 25 in winter,respectively. The concentration of O_3 in holidays was 4.37% higher than workday. The results showed that with the enhancement of solar radiation and precursors emission,the level of O_3 reached the peak at 15 o＇ clock,and then descended with theweakening of solar radiation and consumption of chemical reactions. Nitrogen dioxide,emitted from anthropogenic source, was an important precursor during ozone generation. The increase of temperature accelerated the formation of O_3,and the increase of relative humidity affected the O_3 concentration due to ascending precursors and atmospheric radical. The increase of visibility lead to enhanced solar radiation,which promoted the reaction of O_3 production. The increase of wind first lead to increase level of O_3,and then a dease Southwest and South wind resulted in the accumulation of O_3. The ＂holiday effect＂of O_3 was observed in Taiyuan. In conclusion,the main influence factors of O_3 variation are the variation of ozone precursors（such as nitrogen dioxide） and meteorological conditions（such as solar radiation, temperature, etc.）. Controlling the emissions of ozone precursors might be the main regulatory measure of O_3 pollution prevention.