长沙市城区臭氧浓度特征研究

Analysis of the Characteristics of Ozone Concentration in Urban Area of Changsha

根据2014年4月至2015年3月湖南省长沙市城区10个监测点O_3小时浓度监测数据,综合分析了长沙市O_3的时空分布及其与前体物、气象要素相关关系。结果显示:监测期间长沙市城区O_3小时平均浓度为44.47μg/m^3,O_3高值浓度主要集中在5-9月份,季节分布上O_3平均浓度整体呈现出冬季<春季<秋季<夏季的特征。日变化上O_3呈现倒U型分布,一般在15:00、16:00左右达到峰值浓度,日循环可分为4个阶段:即臭氧累积阶段、臭氧抑制阶段、臭氧光化学生成阶段、臭氧的消耗阶段。空间分布上整体呈现出对照点峰值浓度明显大于城市环境评价点,从城区外围站点浓度大于市中心点浓度特征。O_3的前体物CO、NO_2均呈现双峰型分布,其中O_3与CO、NO_2呈现显著的负相关关系;与气压、湿度呈负相关关系,与温度呈正明显相关关系。

The spatial-temporal distribution characteristics of O3 and the correlations between O3 and ozone precursors, meteorological elements in Changsha urban area were investigated based on the hourly O3 monitoring data from April, 2014 to March,2015. The annual concentration of O3 in Changsha was about 44.47 μg/m^3 and high O3 concentration mainly concentrated in May and September and seasonal variations concentrations of PM2.5 were as winter〉 spring〉 autumn 〉 summer. The diurnal distribution of ozone presented a clear unimodal pattern with its peak appearing at 15：00 or 16：00. The diurnal cycle of ozone can be divided into four stages： ozone accumulation stage and ozone abatement stage, photochemical generation stage and ozone consumption stage. For the spatial distribution of O3, the concentration was lower in central urban area with the highest concentration appeared at background station.The diurnal patterns of the precursors such as CO, NO2 of O3 Presented an obvious bimodal distribution, that were well negatively correlated to O3 diurnal patterns. The concentration of Oa was negatively correlated with the air pressure, humidity while it was positively correlated with temperature.