摘要
大气颗粒物中的有机酸广泛参与大气中的各种物理化学反应,对二次有机气溶胶和霾的形成贡献极大,因此分析颗粒物中有机酸的浓度分布特征、评估其污染来源、探究其二次生成,对深入研究有机气溶胶及其二次转化具有重要意义.在郑州市不同季节采集大气细颗粒物(PM_(2.5))样品,识别并定量二元酸类、脂肪酸类和树脂酸类有机酸共30种,探究其浓度分布特征、季节变化、来源贡献及二次生成.定量的二元酸类以丙二酸(di-C_(3))和琥珀酸(di-C_(4))含量最为丰富,并且表现出明显的季节变化特征:夏季>秋季>冬季>春季;脂肪酸类表现出明显的双峰优势,以棕榈酸和硬脂酸(C_(18))最为丰富,季节变化特征为冬季最高,春季最低.利用主成分分析结合多元线性回归(MLR)方法对郑州市PM_(2.5)中的有机酸进行来源解析,结果表明,35%的有机酸来自于燃烧源和交通源,24%来自于烹饪源、23%来自于二次生成以及17%来自于天然源.利用标记物种的比值(如di-C_(3)/di-C_(4)、F/M和C_(18):1/C_(18))探究有机气溶胶二次形成及其老化过程.结果表明,夏季光化学反应剧烈,有机气溶胶老化或二次生产比例较高,冬季光化学反应较弱,有机气溶胶老化程度较低.采用相关性分析与MLR相结合的方法,量化了气相氧化和液相氧化对二元酸形成的相对贡献,气相氧化在采样过程中起主导作用,占比为58%,特别是夏季,占总二次转化的61%.
Organic acids in atmospheric particulate matter are widely involved in various physical and chemical reactions in the atmosphere and contribute greatly to the formation of secondary organic aerosols and haze pollutions.Therefore,the concentration distribution characteristics,sources,and secondary formation of organic acids in particulate matter are of great significance for further investigation of organic aerosols and their secondary transformation.Fine particulate matter(PM_(2.5))samples were collected in Zhengzhou,and three types of organic acids,including dicarboxylic acids,fatty acids,and resin acids,were analyzed to explore their species distribution,seasonal variations,source contribution,and secondary generation.Malonic acid(di-C_(3))and succinate acid(di-C_(4))were the most abundant in the identified dicarboxylic acids,which showed obvious seasonal variations in the order of summer>autumn>winter>spring.Fatty acids had the highest concentration in winter and the lowest concentration in spring,showing obvious bimodal advantages,with the most abundant compounds being palmitic acid and stearic acid(C_(18)).Principal component analysis and multiple linear regression(MLR)were used to analyze the source of organic acids in PM_(2.5) in Zhengzhou;the results showed that 35% of the organic acids came from combustion and traffic sources,24% from cooking sources,23% from secondary formation,and 17% from natural sources.The ratios of the selected marker species(i.e.,di-C_(3)/di-C_(4),F/M,and C_(18):1/C_(18))were used as tracers for the secondary formation of the organic aerosol and its aging process.The results showed that the photochemical reaction was intense in summer,and the proportion of organic aerosol aging or secondary production was high,whereas the photochemical reaction was weak in winter,and the aging degree of organic aerosol was low.Correlation analysis and MLR were used in combination to quantify the relative contribution of gas-phase oxidation and liquid-phase oxidation to dicarboxylic acid formation,and the results showed that gas-phase oxidation played a dominant role in the sampling period(accounting for 58%),especially in summer(61%).
作者
李子涵
董喆
尚璐琪
孔梓涵
李晓
张瑞芹
LI Zi-han;DONG Zhe;SHANG Lu-qi;KONG Zi-han;LI Xiao;ZHANG Rui-qin(School of Ecology and Environment,Zhengzhou University,Zhengzhou 450001,China;College of Chemistry,Zhengzhou University,Zhengzhou 450001,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2024年第2期700-708,共9页
Environmental Science
基金
郑州市PM_(2.5)与O_(3)协同控制监测项目(20220347A)
国家重点研发计划项目(2017YFC0212403)。
关键词
二元酸
脂肪酸
二次有机气溶胶
二次生成
气相氧化
dicarboxylic acids
fatty acid
secondary organic aerosol
secondary generation
gas-phase oxidation
