济南市夏、冬季PM2.5中化学组分的季节变化特征及来源解析  

Analysis of Seasonal Variations in Chemical Characteristics and Sources of PM_(2.5) During Summer and Winter in Ji'nan City

作　　者：刘晓迪[1] 孟静静[1,2] 侯战方 李静 邢继钊 魏本杰 张二勋[1] 刘加珍[1] 董杰[1] LIU Xiao-di;MENG Jlng-jing;HOU Zhan-fang;LI Jing;XING Ji-zhao;WEI Ben-jie;ZHANG Er-xun;LIU Jia-zhen;DONG Jie(School of Environment and Planning,Liaocheng University,Liaocheng 252000,China;State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,Chinese Academy of Sciences,Xi＇an 710061,China)

机构地区：[1]聊城大学环境与规划学院,聊城252000 [2]中国科学院地球环境研究所,黄土与第四纪地质国家重点实验室,西安710061

出　　处：《环境科学》2018年第9期4014-4025,共12页Environmental Science

基　　金：国家自然科学基金项目(41505112); 山东省自然科学基金项目(BS2015HZ002); 黄土与第四纪地质国家重点实验室开放基金项目(SKLLQG1504); 大学生创新创业项目(26312161016);大学生创新创业项目(201710447046)

摘　　要：为探究济南市大气气溶胶中化学组分的季节变化特征,于2015年夏季、冬季分别连续进行1个月的PM_(2.5)样品采集,并分析无机离子、碳质组分与水溶性二次有机碳(WSOC)的组成、浓度水平及来源.结果表明,济南市冬季PM_(2.5)的质量浓度[(158.3±95.3)μg·m^(-3)]约为夏季[(75.3±25.9)μg·m^(-3)]的2倍,在我国其浓度处于中上等水平.无机离子的总浓度呈夏低冬高的季节变化特征,其中SO_4^(2-)、NO_3^-、NH_4^+是浓度最高的3种离子,且这3种离子的相关性均较好,NH_4^+在夏季和冬季均以(NH_4)_2SO_4和NH_4NO_3的形式存在.大气中存在较高程度的SO_2和NO_2的二次氧化,其中硫氧化率(SOR)呈夏高冬低的变化特征,而氮氧化率(NOR)呈相反的季节变化特征.通过分析PM_(2.5)中阴、阳离子电荷平衡可知,PM_(2.5)呈弱碱性.基于热力学模型ISORROPIA-Ⅱ,结果表明冬季PM_(2.5)的酸性比夏季强.OC与EC浓度均呈夏低冬高的变化特征,由OC/EC的比值、WSOC/OC的比值和估算的二次有机碳(SOC)的浓度可知,夏季二次污染的程度比冬季更为严重.主成分分析(PCA)结果表明,济南市夏季无机离子主要来自二次氧化及生物质燃烧,而冬季无机离子主要来自煤炭燃烧及其产生的前体物经光化学氧化形成的二次污染物.To investigate seasonal variations in the chemical compositions of aerosols in Ji＇nan City,PM2.5 samples were collected during summer and winter in 2015. The sampling period lasted one month during each season. PM2.5 samples were analyzed for the composition,concentration,and sources of water-soluble inorganic ions,organic carbon（OC）,elemental carbon（EC）,and watersoluble organic carbon（WSOC）. Results showed that mass concentrations of PM2.5 in winter were about twice those in summer,and concentration levels varied between fine and excellent. The concentrations of total water-soluble inorganic ions were also higher in winter than in summer,with SO4^2-,NO3^-,and NH4^＋ being the dominant species and well correlated with each other. NH4^＋ in PM2.5 mostly existed in the form of（NH4）2SO4 and NH4NO3 in both summer and winter. There was strong secondary oxidation of SO2 and NO2. The sulfate oxidizing rate（SOR） was higher in summer than in winter,while the nitrate oxidizing rate（NOR） showed the opposite trend. The ratio of anions to cations in both summer and winter were less than one,suggesting that PM2.5 were slightly alkaline. The ISORROPIA-II mode showed that acidity in winter was stronger than in summer. Concentations of OC and EC were both higher in winter than in summer. The ratios of OC to EC and WSOC to OC and estimated concentrations of secondary organic carbon（SOC） showed that secondary pollution was more serious in winter than in summer. Principal component analysis（PCA） indicated that the major sources contributing to inorganic ions were secondary oxidation and biomass burning in summer,and coal combustion and secondary pollutants formed by chemical oxidation of precursors emitted from coal combustion in winter.

关 键 词：水溶性离子 碳质组分 季节变化特征 济南市 PM2.5 

分 类 号：X513[环境科学与工程—环境工程]