华山山腰和山脚点大气PM_(2.5)中非极性有机化合物污染特征及来源  

Pollution characteristics and sources of nonpolar organic compounds in atmospheric PM_(2.5)at mountain side and mountain foot of Mt.Hua

作　　者：张轲 吴灿 陆晔宇 雷亚莉 陈玉宝 王格慧 ZHANG Ke;WU Can;LU Yeyu;LEI Yali;CHEN Yubao;WANG Gehui(Key Laboratory of Geographic Information Sciences,Ministry of Education,School of Geographic Sciences,East China Normal University,Shanghai 200241)

机构地区：[1]华东师范大学地理科学学院,教育部地理信息科学重点实验室,上海200241

出　　处：《环境科学学报》2024年第3期299-309,共11页Acta Scientiae Circumstantiae

基　　金：国家杰出青年科学基金(No.41325014)。

摘　　要：为理解对流层大气污染物分布特征和来源,以华山大气PM_(2.5)为对象,于2016年夏季在山腰和山脚同步开展4 h高时间分辨率PM_(2.5)样品采集,采用气相色谱-质谱(Gas Chromatography Mass Spectrometry,GC-MS)联用技术分析其有机物(organic matter,OM)组成.重点研究正构烷烃(normal alkanes,n-alkanes)和多环芳烃(polycyclic aromatic hydrocarbons,PAHs)的浓度、分子组成,定量解析PM_(2.5)中OM来源.结果表明,观测期间山腰和山脚n-alkanes和PAHs浓度差异显著,山脚n-alkanes和PAHs浓度分别为(197.8±121.0)ng·m^(-3)和(39.2±27.3)ng·m^(-3),是山腰n-alkanes((42.4±29.1)ng·m^(-3))和PAHs((3.5±3.4)ng·m^(-3))的4~10倍,表明关中盆地边界层内不同海拔高度上有机气溶胶浓度梯度变化显著;此外,由于边界层抬升和垂直输送的缘故,山腰n-alkanes和PAHs浓度呈现出与山脚相反的白天高夜晚低的昼夜变化特征.山脚和山腰都呈现出污染期n-alkanes和PAHs浓度显著高于清洁期,这是因为华山地区夏季污染期化石燃料燃烧增多.特征比值和PMF源解析分析显示:山腰和山脚OM来源差异显著,山脚OM受到化石燃料源的影响大,占总来源的52%,而山腰OM则主要来自植物排放及大气光化学氧化,贡献高达62%,表明关中盆地大气边界层上部有显著的二次有机气溶胶生成过程.To investigate the distribution characteristics and sources of atmospheric PM_(2.5) at Mt.Hua in Guanzhong Basin,PM_(2.5) samples with a 4 htime resolution were simultaneously collected on a mountainside site and a mountain foot site in summer 2016,and analyzed for non-polar organic compounds(NPOCs),namely,n-alkanes and polycyclic aromatic hydrocarbons(PAHs).In this paper,we focus on the concentration,molecular composition of n-alkanes and PAHs to quantify the source of organic matter(OM)in PM_(2.5).The results showed that the differences in the concentrations of n-alkanes and PAHs between the mountain side((42.4±29.1)ng·m^(-3),(3.5±3.4)ng·m^(-3))and mountain foot((197.8±121.0)ng·m^(-3),(39.2±27.3)ng·m^(-3))during the observation period were significant with the concentrations at the mountain foot being 4~10 times higher than those at the mountain side,suggesting a significant gradient of OM in vertical abundances in the troposphere.In addition,due to the boundary layer uplift and air mass vertical transport,n-alkanes and PAHs at the mountain side showed higher concentrations during daytime and lower concentrations during nighttime,which is opposite to that at the mountain foot.The concentrations of n-alkanes and PAHs in the polluted period at both sites were significantly higher than those in the clean period,which was attributed to increased fossil fuel combustion during the polluted period at Mt.Hua.Diagnostic ratio and PMF source apportionment further suggest that the origins of OM at the two sites are different,of which OM at the mountain foot are more influenced by fossil fuel combustions,accounting for 52%of the total.In contrast,OM at the mountain side are mainly from plant emissions and atmospheric photochemical oxidation,which contributed up to 62%of the total OM,indicating a significant formation of secondary organic aerosols in the upper boundary layer over the Guanzhong Basin.

关 键 词：正构烷烃和多环芳烃 分子组成 来源解析 垂直分布 地表与高山 

分 类 号：X513[环境科学与工程—环境工程]