西安市夏末秋初PM_(2.5)中碳组分分析

ANALYSIS OF CARBON COMPONENTS IN PM_(2. 5) DURING LATE SUMMER AND EARLY AUTUMN OF XI'AN CITY

2012年9月1日至30日利用大气气溶胶OC/EC在线分析仪在线分析了西安PM2.5中的OC、EC,并结合O3和紫外辐射数据(UV)进行了分析。结果表明:PM2.5、OC、EC、及O3的日均值分别为85.22,19.50,7.18,56.69μg/m3。PM2.5及其中OC、EC的日变化规律呈现"双峰"分布,OC、EC的日波动范围较PM2.5小,且OC的波动范围较EC大,OC、EC的相关性较高(R2=0.73)。PM2.5中TCA的平均比重为47.85%,是PM2.5的主要成分之一,TCA以OM为主,OM中SOC的平均比重高达54.76%,PM2.5中SOC的平均比重为21.25%,SOC和O3的相关性较高,表明研究期间西安市有机物光化学反应较重。1 d中10:00至19:00是PM2.5中SOC比重最高的时段且呈上升趋势,而PM2.5中TCA的变化规律则呈"W"型双峰分布。

An on-line monitoring of OC,EC in PM2. 5was done by OC / EC online analyzer from 1st to 30 th September,2012 in Xi' an. O3 and UV were also monitored and analyzed. The results showed that the daily average concentration of PM2. 5,OC,EC,O3 was 85. 22,19. 50,7. 18 and 56. 69 μg / m3,respectively. The daily change rules of PM2. 5,OC and EC were present'bimodal'distribution,and the daily changes of OC and EC were both smaller than PM2. 5. Furthermore,OC had a larger fluctuation range than EC,while the relative correlation of them was high( R2= 0. 72899). TCA was the main component of PM2. 5and could occupy 47. 85%. The majority composition of TCA was OM,and the concentrations of SOC in the OM could be up to 54. 76%. SOC and O3 showed a high correlation,which indicated that the organic photochemical reactions were relatively heavy during the study period in Xi' an. The proportions of SOC in PM2. 5were highest during10: 00 am to 7: 00 pm in a day,and did a increasing trend,The changes of TCA in the PM2. 5were present 'W shape 'bimodal distribution.