烟花爆竹燃放对北京大气污染物和水溶性无机离子的影响

Effects of Fireworks on Gaseous Pollutants and Water-Soluble Inorganic Ions in the Atmosphere

为了解春节期间烟花爆竹燃放对北京大气污染物和PM_(2.5)中水溶性无机离子贡献的影响,采用浓度特征对比、相关性分析等方法,对2011年2月1日—3月1日期间的PM_(10)、气态污染物、PM_(2.5)中水溶性无机离子浓度等在线数据进行了分析.结果表明:烟花爆竹的燃放会在短时间内加重PM_(10)颗粒物污染,集中燃放期(含除夕、春节、正月初五、元宵节)ρ(PM_(10))和φ(SO_2)(分别为232μg/m^3和40.2×10^(-9))是非集中燃放期(63μg/m^3和16.0×10^(-9))的3.7和2.5倍,燃放烟花爆竹对ρ(PM_(10))和φ(SO_2)的小时贡献率分别达到56.8%和35.6%;但对φ(CO)、φ(NO)、φ(NO2)无显著影响.而观测期间由其他因素导致的污染期ρ(PM_(10))和各气态污染物小时体积分数有所增加,分别是非集中燃放期的3.0~8.3倍.燃放烟花爆竹对PM_(2.5)中ρ(Mg^(2+))、ρ(K^+)、ρ(Cl^-)的影响最大,分别为非集中燃放期的65.0、31.6、6.9倍,贡献率分别为88.6%、87.2%、65.8%.ρ(Mg^(2+))、ρ(K^+)与ρ(Cl^-)在集中燃放期表现出较高的相关性(R>0.9).污染期ρ(SO_4^(2-))、ρ(NO_3^-)、ρ(NH_4^+)明显升高,分别为非集中燃放期的3.8、16.4、8.3倍,同时高于集中燃放期(分别为2.7、2.5、2.1倍).集中燃放期PM_(2.5)中主要以NH_4HSO_4、NH_4NO_3、KNO_3、KCl、NH_4Cl、MgCl_2等形式存在.集中燃放期硫氧化物转化率(SOR)高于非集中燃放期和污染期,而氮氧化物转化率(NOR)则是污染期最高.研究显示,燃放烟花爆竹对ρ(PM_(10))及PM_(2.5)中ρ(Mg^(2+))、ρ(K^+)、ρ(Cl^-)影响最大,污染期各离子浓度均有大幅升高,NOR在污染期的高值是导致ρ(NO_3^-)升高的重要原因.

In order to understand the contribution of fireworks to Beijing＇s gaseous pollutants and water-soluble inorganic ions in PM2.5 during the Spring Festival, online data of PM10, gaseous pollutants and water-soluble inorganic ions from February 1st to March 1st, 2011, were analyzed by comparing concentration characteristics and conducting correlation analysis. The results showed that fireworks aggravated the PM10 pollution in a short time period. During the dense firework-setting-off period （i. e. , New Year＇s Eve, Spring Festival, the 5th day of the first lunar month and the Lantern Festival） , hourly mass concentration of PM10 （232 μg/m3 ） and volume fraction of SO2 （40.2 × 10-9） were 3.7 and 2.5 times more than their levels during normal days （63 μg/m3 and 16.0 × 10-9） , respectively. The ratios of the contribution of fireworks to PM10 （hourly ρ） and SO2 （hourly φ） were 56.8% and 35.6% , respectively. No significant impacts from fireworks on CO, NO or NO2 were detected. The concentration of PM10 and gaseous pollutants increased 3.0-8.3 times during the pollution caused by other factors in February 2011. Setting off fireworks had the greatest impacts on Mg2＋ , K＋ and C1- , with contribution ratios 88. 6% , 87. 2% and 65. 8% , which were higher than their levels during normal days （65.0 times, 31.6 times and 6.9 times, respectively）. Mg2＋ , K＋ and C1-showed a high correlation during the dense firework-setting-off period; the correlation coefficient between any two of these species was above 0.9. The concentrations of SO_4-2- , NO_3 - and NH4 ＋significantly increased during the polluted period, being 3.8 times, 16.4 times and 8.3 times higher than their levels during normal days, respectively, which were also higher than their levels during the dense firework-setting- off period （2.7, 2. 5 and 2.1 times respectively）. During the firework-setting-off period, ions existed in the form of NH_4HSO_4 , NH_4NO_3 , KNO_3 , KCl, NH_4Cl and MgCl_2 in PM2.5 , and the value of SOR was higher than in both normal days and the polluted period. The highest value of NOR appeared in the polluted period. The research showed that fireworks had the greatest impact on ρ （ PM10 ） , ρ（Mg2＋）, ρ（K＋） and ρ（Cl-） in PM2.5; during the polluted period, the ions＇ concentrations were significantly increased, and the higher value of NOR was responsible for the increasing of ρ（ NO_3- ）.