广州市区公交车站PM_(2.5)与CO暴露水平研究

用便携式颗粒物浓度测定仪(DustTrak Model8520)和CO测定仪(Q-Trak Model8551),于2008年9月至2009年1月对广州市区11个代表性公交车站的PM2.5和CO暴露水平进行了测定。结果表明,公交车站7:00～19:00时间段PM2.5的平均浓度范围为206～348μg/m3,总体均值达288μg/m3,显示公交车站PM2.5污染问题突出;CO平均浓度范围1.5～4.0mg/m3,总体平均2.8mg/m3,有六个站点平均浓度超过了我国环境空气质量标准限值(4.0mg/m3或3.2mg/m3)。大多数站点工作日与非工作日PM2.5与CO水平差异不大,部分站点则受车流量和客流量变化影响呈现差异。同一站点PM2.5日变化特征不如CO明显,一次污染物CO变化受交通高峰影响呈双峰特征,而PM2.5水平影响因素复杂,一般白天较低,夜晚21:00出现峰值。不同站点CO与车流量未见显著相关性,表明车流量并不是决定公交站点CO水平的唯一因素,而扩散条件及公交车排放可能也是重要影响因素;与CO不同,不同站点PM2.5与车流量表现出显著相关(p0.05),可能侧面反映路面扬尘对公交车站PM2.5水平的影响和贡献。

Exposure Levels of PM2.5 and CO at Bus Stations in Urban Guangzhou

Exposure levels of PM2.5 and CO at 11 representative bus stations in urban Guangzhou were measured using portable PM2.5 analyzer (DustTrak Model 8520) and CO analyzer (Q-Trak Model 8551) from September 2008 to January 2009. Results showed that during 7:00～19:00 PM2.5 levels averaged 206～348μg/m3 with a mean of 288μg/m3,indicating serious PM2.5 pollution at bus stations. Average CO levels in the stations ranged 1.5～4.0mg/m3 with a mean of 2.8mg/m3,and at 6 bus stations which exceeded the limit of national ambient air quality standard of 4.0mg/m3 or 3.2mg/m3. At most stations PM2.5 and CO levels were not significantly different between weekday and weekend,but in a few stations there was significant difference due to substantial changes in traffic/passenger flows. In each station CO showed larger daily variation than PM2.5. As a primary pollutant CO has a bimodal pattern with peaks coinciding with those of traffic flow. PM2.5 showed lower levels in daytime and peaked at about 21:00. Among different stations there was no significant correlation between CO and traffic flow,suggesting that traffic flow was not the sole factor determining CO levels at the stations,and dispersion conditions and emission from buses were also very important affecting factors. Unlike CO,PM2.5 did show significant correlation with traffic flow,implying possible influence of road dust re-suspension apart from direct traffic emission.