燃放烟花爆竹对北京城区气溶胶细粒子的影响

Effect of firecracker setting-off on the fine particle pollution in Beijing downtown areas

为了研究燃放烟花爆竹对空气中气溶胶细粒子污染的影响,采用TEOM于2003年1月31日—2月25日对PM2.5和PM10质量浓度和化学成分进行了研究,分析了春节期间北京城区气溶胶细粒子的污染特征。结果显示:燃放烟花爆竹会导致空气中PM2.5在短时间内上升到很高的水平,最大小时平均质量浓度达549μg/m3,平均每小时质量浓度增加100μg/m3左右。并且随着PM2.5质量浓度的上升,PM2.5在PM10中的比例也明显上升,两者质量浓度小时平均值的比值最大可达0.9。稳定天气条件下,燃放高峰期过后随着粒径在2.5～10μm之间的较粗粒子的沉降(约需3～4h),PM10的质量浓度下降,但PM2.5/PM10的比值仍持续偏高。燃放烟花爆竹导致PM2.5中以燃烧为代表的元素(S、P、As)、部分金属元素(Al、Fe、Ti、Se、K)、可溶性离子成分以及OC的升高。这些成分与烟花爆竹的金属粉末、无机盐类,以及复杂的S、P化合物等主要成分吻合。

The present article aims to report the authors＇ investigation of the effects of the firecrackers＇ setting off on fine particle pollution in Beijing＇ s downtown areas during the Spring Festival period in 2003. Using TEOM （Tapered element oscillating microbalance） series 1400A instrument, the authors observed the data of mass concentration of PM2.5 and PM10. In doing the investigation, we have linked ACCU system to the bypass of TEOM instrument, with some filter aerosol samples collected. And then the chemical composition of PM2.5 was analyzed with the above mentioned method. The results of the above said investigation reveal that the firecrackers firing made the concentration of PM2.5 extremely high in a short moment with its actually hourly maximum mass concentration reaching 549 μg/m^3 from our observed data. While the increasing speed of PM2.5 mass concentration went up as about 100 μg/m^3 per-hour during the dense firecrackers time. In addition, when the mass concentration of PM10 was increasing, the value of PM2.5/PM10 would also increase simultaneously by getting to 0.9. Under the stable weather condition, high concentration of PM2.5 and PM10 may last 5-6 hours when the firecrackers were firing for longer time. In such a situation, the sedimentation of the particles whose diameter remained from 2.5 to 10 μm may lead to the dropping of the concentration, though the percentage of PM2.5 in PM10 may keep high. Thus, the firecrackers made the concentration of the elements S, P, As, Al, Fe, Ti, Se, and K, the organic carbon, some soluble ions of PM2.5 higher. In conclusion, all the analogical compositions of fireworks, such as metallic powder, inorganic salt, sulfid and phosphide can be proved in correspondence with the actual oollution that occurred.