浙江省城市大气污染特性研究

The study of air pollution characteristics in urban area over Zhejiang

本文以浙江省城市（主要指杭州）为研究区域,利用大气成分观测数据,通过对比、相关分析研究了浙江省城市的大气污染特性.研究结果表明,2011—2013年间,杭州PM2.5和NO2月均质量浓度均呈上升趋势,增幅皆为10μg·m^-3左右,PM10和SO2则呈下降趋势,PM10降幅微弱,SO2降幅为8μg·m^-3左右.PM1、PM2.5、PM10质量浓度与大气消光系数之间相关系数为0.73、0.83和0.74,其中粒径为0.25～1.0μm的粒子对大气消光系数的贡献率最大,达到66.4%,1.0～2.5μm粒子为23.2%,大于2.5μm的粗粒子仅为10.4%.与临安相比,杭州NO2日均浓度超标日数多了50天左右.杭州大气气溶胶中占主导地位的无机水溶性离子依次为NO3^-、NH4^＋和SO4^2-,它们占到总水溶性离子浓度的52.66%～96.61%,与北京、广州等地区SO4^2-〉NO3^-的研究结果明显不同.NO3^-、NH4^＋浓度季节变化特点与NO2相似,而且NO3^-和NH4^＋具有较好的相关性,SO4^2-与SO2浓度季节变化特点则不同.受夏季主导风向的影响,这一季节Na^＋和Cl^-浓度最高,而秋季明显偏高的K＋浓度是长三角秋季秸秆焚烧现象的指示.

Based on observations data of atmospheric compositions,the characteristics of air pollution were investigated in Hangzhou over Zhejiang province through the comparison and correlation analysis.The results showed that the increasing trends of the monthly average mass concentrations of PM2.5and NO2 with 10μm·m^-3 amplitude and the decreasing trends of PM10 and SO2 with drop slightly and 8μm·m^-3 were present in Hangzhou from 2011 to 2013.The average correlation coefficients were 0.73,0.83 and 0.74 between atmospheric extinction and mass concentra-tion of PM1,PM2.5as well as PM10,respectively.The contributions of 0.25～1.0μm and 1.0～2.5μm particles on atmospheric extinction were 66.4% and 23.2%,respectively,and larger than 2.5μm particles only 10.4%.Compared with Lin＇an,the above-norm days of daily average concentration of NO2 was over 50,which is the important reason of heavy haze pollution in Hangzhou.The results also showed that NO3^-,NH4^＋,and SO4^2-were the dominant water-soluble fractions in PM2.5,accounting for 52.66% ～96.61% of the total water-soluble ion concentration in Hangzhou,and present NO3^-〉 NH4^＋ 〉SO4^2-descending order,which was different from the condition of Beijing and Guangzhou with SO4^2-〉 NO3^-.In addition,NO3^-and NH4^＋ present the same seasonal variations of NO2 and good correlation each other,but SO4^2-was different to the seasonal variations of SO2.The highest concentrations of Na^＋and Cl^-were found in summer because of dominant wind direction Marine aerosol to inland transportation,and the highest concentration of K＋was found in autumn which is a good indicator of straw burning in Yangtze River delta.