郑州市臭氧污染变化特征、气象影响及输送源分析

Characteristics,Meteorological Influences,and Transport Source of Ozone Pollution in Zhengzhou City

基于环境空气质量和气象在线监测数据,研究了郑州市近地面臭氧(O_(3))污染的年际变化、空间差异及气象影响,并分析了O_(3)传输路径和潜在源区.结果表明,2014~2018年郑州市近地面O_(3)污染超标时间跨度增加,城区站点O_(3)日最大8 h滑动平均值(MDA8)第90%分位呈显著上升趋势(P<0.05),增长速率为15.50μg·(m^(3)·a)^(-1);O_(3)月变化呈"M"型,峰值出现在夏季;日变化呈单峰型,峰值出现在15:00~16:00,农村站点O_(3)日峰值浓度(130.94μg·m^(-3))最高;气温(T)>23℃、相对湿度(RH)<65%和风速(WS)为2.0~4.0 m·s^(-1)及风向在东南和东北方向时城市站点易发生高浓度O_(3)污染.各影响因子和O_(3)浓度的多元线性回归分析表明,T和RH是城市和工业站点的主控因子,T和WS是城市交通和郊区站点的主控因子;不同季节后向轨迹聚类分析和O_(3)潜在来源差异明显,春夏季大气传输路径以正南及东北方向近距离慢移速的轨迹为主,秋冬季以西北方向远距离快移速的轨迹为主;夏季高O_(3)浓度主要受本地生成和河北、山东及安徽等地传输影响.

Based on online monitoring data of air quality and meteorological parameters,the long-term variations,spatial differences,and meteorological influencing factors of ground-level ozone(O_(3))pollution in Zhengzhou were studied.In addition,the transport pathways and potential source regions of O_(3)were investigated.The results show that surface O_(3)concentrations at the city station in Zhengzhou City increased significantly during the period 2014-2018(P<0.05)with a growth rate of 15.50μg·(m^(3)·a)^(-1),and the timespan of exceeding pollutant standards was extended.The monthly O_(3)variations showed an"M"pattern with the seasonal maximum in summer.The diurnal O_(3)variations showed a"single-peak"pattern with a diurnal concentrations peak at 15:00-16:00,while the diurnal peak at the rural station was relatively high(130.94μg·m^(-3)).At the urban station,the exceedance probability of O_(3)concentrations was relative high when hourly temperature(T)exceeded 23℃,relative humidity(RH)was less than 65%,wind speed(WS)ranged 2.0-4.0 m·s^(-1),and wind direction was southeast or northeast.Based on the multivariate linear fitting of impact factors on O_(3),the main controlling factors at the city and industrial sites were also identified as T and RH compared to T and WS at the traffic and suburb sites.Back trajectory analysis and potential sources of O_(3)during different seasons were significantly different,with the dominant transport trajectories during spring and summer being short-distance and slow-moving airflows from the south and northeast;autumn and winter were characterized by long-distance and quick-moving airflows from the northwest.The high O_(3)concentrations observed in summer were mainly affected by local photochemical formation and regional transport from Hebei,Shandong,and Anhui Provinces.