天津滨海新区秋冬季大气污染特征分析

为了解天津滨海新区大气污染物浓度水平和污染来源,2009年9月1日~2010年2月28日对NOx、CO、SO2、O3、PM2.5、PM10进行了连续在线观测,并同步观测了气象要素.结果表明,秋冬季上述污染物最高日均值(秋冬平均值±标准差,O3为日小时均值最大值)分别达到300.7(65.4±52.9)×10-9、7.278(1.324±1.169)×10-6、53(13±12)×10-9、95(28±21)×10-9(体积分数)和287.4(62.3±53.6)μg/m3、1421.4(161.9±136) μg/m3. NOx和SO2秋季低于冬季,O3和PM10反之. CO和PM10相对国家二级标准超标率为2%和38%,PM2.5相对WHO标准(75μg/m3)超标率为31%.季节统计日变化显示CO和NOx为早晚双峰型,SO2为中午的单峰型,O3为午后单峰型,且秋季日变化振幅远大于冬季, PM10为早晚双峰型,但冬季比秋季晚出峰2~3h.除冬季PM10,大气污染物浓度49%~74%的逐日变化由气象要素影响.滨海新区大气污染受局地排放和外源输送共同影响,西南方向气流易造成污染物积累,其次是东北方向,而东和东南气流最有利于污染物扩散;各污染物具体表现为NOx主要受局地源控制;SO2主要受外来输送影响;CO和PM2.5同时受本地源和外来源的共同影响;PM10秋季表现为本地源污染,而冬季为本地源和外来源的共同影响.

Characteristics of atmospheric pollutants in Tianjin Binhai New Area during autumn and winter

NOx, CO, SO2, O3, PM2.5, PM10, along with meteorological factors, were observed in Tianjin Binhai New Area, a coastal site southeast of Beijing and Tianjin, in order to understand atmospheric pollution levels and their sources in that region. From September 2009 to February 2010 the daily average maximum (mean ±standard deviation) concentrations of NOx, CO, SO2, O3, PM2.5, PM10 were 300.7(65.4±52.9)×10-9,7.278(1.324±1.169)×10-6,53(13±12)×10-9,95(28±21)×10-9 (maximum hourly averaged O3)(V/V) and 287.4(62.3±53.6)μg/m3, 1421.4(161.9±136) μg/m3, respectively; the levels of NOx and SO2 were lower and the level of O3 and PM10 were higher in autumn than those in winter; the daily average concentration of CO and PM10 exceeded the National Ambient Air Quality Standard Ⅱ for 2% and 38%, and PM2.5 exceeded the WHO Standard for 31%. The average diurnal variations of NOx and CO were similar, peaking in the early morning and night, while SO2 peaking at noon, O3 peaking in the afternoon with larger diurnal amplitude in autumn than that in winter; PM10 occurred maximum in the early morning and night during autumn, while earlier 2~3 hours than that in winter. Meteorological parameters could explain from 49% to 74% of the day-to-day variations of pollutant concentrations, except PM10 during winter. The findings suggested that the atmospheric pollution in Binhai New Area was related to local emission and regional transport, that was to say, southwest wind was firstly favorable for accumulating pollutants and northeast wind secondly, while east and southeast winds were helpful for dispersing pollutants; aiming for different pollutants, NOx was controlled by local emission, SO2 by regional transport, CO and PM2.5 by both local and regional influence, PM10 by local emission in autumn and both local and regional influence in winter.