疫情管控对关中城市群大气污染特征及颗粒物化学组成的影响  

Influence of epidemic control on air pollution characteristics and chemical composition of particulate matter in Guanzhong urban agglomeration

作　　者：蒋星星 陈庆彩 熊梦琪 Ainur Dyussenova JIANG Xingxing;CHEN Qingcai;XIONG Mengqi;Ainur Dyussenova(College of Environmental Science and Engineering,Shaanxi University of Science and Technology,Xi’an,710021,China)

机构地区：[1]陕西科技大学环境科学与工程学院,西安710021

出　　处：《环境化学》2023年第8期2640-2650,共11页Environmental Chemistry

基　　金：陕西青年科技新星项目(2021KJXX-36);未央区扬尘污染特征、来源及其控制研究(202224).

摘　　要：新冠肺炎疫情的暴发对生产生活模式产生了重大影响,进而改变了大气污染现状和规律,是一次极限减排的“大气实验”.本研究以中国典型大气污染控制区的关中城市群为研究对象,考察该地区疫情管控下大气污染物污染特征、来源和形成机制,解析了大气细颗粒物(PM_(2.5))中化学组分的浓度变化特征.结果显示,除O_(3)外,其余大气污染物浓度的整体变化趋势均表现为管控前>管控后,与全国趋势一致、但程度不同.新冠肺炎疫情的社会隔离措施大幅度削减了各类排放源,西安市、咸阳市、铜川市、宝鸡市、渭南市等5个城市PM10、PM_(2.5)、NO_(2)和CO浓度值明显降低,其中PM_(10)、SO_(2)、NO_(2)、CO在疫情期间的浓度达到近5年来历史最低.O_(3)浓度在封城期间却有显著上升的现象,表明大气氧化性可能在燃烧排放减少的背景下由于NO_(2)滴定效应减小而得到强化.对西安市PM_(2.5)中水溶性阴阳离子浓度对比分析结果显示,Ca^(2+)、Na^(+)、Cl^(-)、NO_(3)^(-)、NH_(4)^(+)、SO_(4)^(2-)等几种主要水溶性离子浓度在疫情管控后明显降低,由于来源和形成机制不同,NH_(4)^(+)、SO_(4)^(2-)离子在管控后占比有所上升,其他4种离子占比都有所下降,这与对交通源和工业源的大幅消减以及颗粒物中NH_(4)^(+)和SO_(4)^(2-)、NO_(3)^(-)之间的二次反应有很大关系.特别是,交通源排放的减排对大气污染物NO_(2)、CO、PM浓度的减小是显著的,因此未来在城市汽车尾气治理、机动车低耗能低排放以及清洁能源等方面多加投入是必要的.适当的排放源管控有利于大气环境质量的改善,但除了要考虑污染源和减排目标以外,还需要结合当地大气污染特征和气象条件、考虑O_(3)的“滴定效应”,实现大气颗粒物与O_(3)协同控制,改变颗粒物浓度下降而O_(3)污染加剧的局面.The outbreak of the COVID-19 epidemic situation has had a significant impact on production and life patterns,which has changed the present situation and law of air pollution.In this study,the Guanzhong area,a typical air pollution control area in China,was taken as the research object.The types,sources,and formation mechanism of air pollutants under epidemic control in this area were investigated,as well as the concentration variation characteristics of chemical components in atmospheric fine particles(PM2.5).The results show that,except for O_(3),the overall change trend in the average concentration of other air pollutants before control>after control.However,the concentration of O_(3)increased significantly during the city lockdown,indicating that the atmospheric oxidation may be strengthened due to the reduction of the NO_(2)in the context of reduced combustion emissions.The social isolation measures during the COVID-19 epidemic have greatly reduced the concentrations of various pollutants,and the concentrations of PM_(10),PM_(2.5),NO_(2)and CO have obviously decreased in five cities,including Xi'an,Xianyang,Tongchuan,Baoji and Weinan.During the epidemic,the concentrations of PM10,SO_(2),NO_(2)and CO reached the lowest level in the past five years.A comparative analysis of the concentration of water-soluble anions and cations in PM_(2.5) in Xi’an shows that the concentration of several main water-soluble ions such as Ca^(2+),Na^(+),Cl^(-),NO_(3)-,NH_(4)^(+),SO_(4)^(2-)decreased significantly after the epidemic control.During the lockdown,the proportion of NH_(4)^(+)and SO_(4)^(2-)ions increased due to different sources,whereas the proportion of other four ions decreased,which is related to the strict control of traffic sources and the chemical reaction between NH_(4)^(+)and NO_(3)-and SO_(4)^(2-)in particulate matter.NO_(2),CO,PM and other pollutants are greatly reduced after control.Automobile exhaust emission reduction is very important for air pollution control.In the future,more invest would be required

关 键 词：疫情管控 关中城市群 大气污染特征 颗粒物化学组成 

分 类 号：X51[环境科学与工程—环境工程]