西安市道路PM_(2.5)NO_2 CO水平浓度分布特征

Horizontal Concentration Distribution Characteristics of PM_(2.5),NO_2 and CO on Xi'an Roads

为获得西安市道路PM_(2.5)、NO_2和CO的水平浓度分布特征,选取小寨和秦岭环山路作为西安市城区道路和郊区道路的代表,采用水平分布的监测方法获得了每条道路距离道路边缘0、15和50 m处的ρ(PM_(2.5))、ρ(NO_2)和ρ(CO).结果表明:与秦岭环山路(下称秦岭)相比,城区观测点小寨的ρ(PM_(2.5))、ρ(NO_2)和ρ(CO)分别为(88±50)(78.6±29.8)μg/m^3和(1.5±0.3)mg/m^3,均高于秦岭三者的质量浓度〔分别为(55±23)(47.9±19.8)μg/m^3和(1.4±0.1)mg/m^3〕.在空间分布上,ρ(PM_(2.5))、ρ(NO_2)、ρ(CO)水平梯度分布明显.与距离道路边缘0 m处相比,小寨ρ(PM_(2.5))在距离道路边缘15和50 m处分别减少了6.48%、7.96%,秦岭减少了5.45%、9.09%;小寨ρ(NO_2)在15和50 m处分别减少了8.57%、14.29%,秦岭减少了15.45%、24.89%;在距离道路边缘50 m处小寨ρ(CO)减少了25.00%,而秦岭在距离道路边缘15和50 m处分别减少了25.00%、41.67%.研究显示,来自于机动车排放的PM_(2.5)、NO_2和CO在道路两侧有明显的距离效应,并且郊区观测点水平递减更明显.

In order to understand the concentration distributions of PM_（2.5）,NO_2 and CO with different distances away from roads,Xiaozhai and Qinling were selected as the downtown and rural areas in Xi＇an City,respectively. The horizontal profile method was used to measure the concentrations ρ（ PM_（2.5））,ρ（ NO_2） and ρ（ CO） at three sites 0 m,15 m and 50 m away from the road sides at each road. During the observation,E-BAM was used to detect the ρ（ PM_（2.5））,Ecotech 9841 and Thermo 42 i were used to detect the ρ（ NO_2）,and Thermo 48 i and Ecotech 9830 were used to detect the ρ（ CO）. The results indicated that the ρ（ PM_（2.5））,ρ（ NO_2） and ρ（ CO） at Xiaozhai were higher than those at Qinling; this is related to more vehicle emissions downtown. The values of ρ（ PM_（2.5））,ρ（ NO_2） and ρ（ CO） at Xiaozhai were（ 88 ± 50） μg/m^3,（ 78. 6 ± 29. 8） μg/m^3and（ 1. 5 ± 0. 3） mg/m^3,respectively,which is much higher than（ 55 ± 23） μg/m^3,（ 47. 9 ±19. 8） μg/m^3and（ 1. 4 ± 0. 1） mg/m^3observed at Qinling. The concentrations ρ（ PM_（2.5））,ρ（ NO_2） and ρ（ CO） by horizontal distribution significantly decreased with distance from both road sides. Compared with the concentrations of PM_（2.5）,NO_2 and CO at 0 m,ρ（ PM_（2.5）） of Xiaozhai at 15 and 50 m were reduced 6. 48% and 7. 96%,respectively,and those for Qinling were decreased 5. 45% and 9. 09%,respectively; ρ（ NO_2） of Xiaozhai at 15 and 50 m were reduced 8. 57% and 14. 29%,respectively,and those for Qinling Ring road were decreased 15. 45% and 24. 89%,respectively; ρ（ CO） of Xiaozhai at 50 m was reduced 25. 00%,Qinling of 15 m,50 m were reduced25. 00% and 41. 67%,respectively. PM_（2.5）,NO_2 and CO emitted from motor vehicles on the road diffuse obviously according to the different distances,and the decreasing rate at the downtown site was much greater than that at rural site.