基于氧化流动管反应器的多环芳烃大气老化研究  

study on the atmospheric aging of polycyclic aromatic hydrocarbons using an oxidation flow tube reactor

作　　者：杨孔 王巧云 王应昆 潘天乐 张涛 张宇晴 陈多宏 胡伟伟 李军[1,5] 王新明 丁翔[1,5] YANG Kong;WANG Qiaoyun;WANG Yingkun;PAN Tianle;ZHANG Tao;ZHANG Yuqing;CHEN Duohong;HU Weiwei;LI Jun;WANG Xinming;DING Xiang(State Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China;Guangdong Industry Polytechnic University,Guangzhou 510300,Guangdong,China;Environmental Monitoring Center of Guangdong Province,Guangzhou 510308,Guangdong,China;Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control,Guangzhou 510640,Guangdong,China)

机构地区：[1]中国科学院广州地球化学研究所,有机地球化学国家重点实验室,广东广州510640 [2]中国科学院大学,北京100049 [3]广东轻工职业技术学院,广东广州510300 [4]广东省生态环境监测中心,广东广州510308 [5]粤港澳大湾区环境污染过程与控制联合实验室,广东广州510640

出　　处：《地球化学》2024年第6期782-792,共11页Geochimica

基　　金：国家自然科学基金项目(42177090);广东省教育厅高校重点领域专项项目(2022ZDZX4067);广东省基础与应用基础研究基金项目(2022A1515110899)联合资助。

摘　　要：多环芳烃(PAHs)是广泛存在于环境中的一类有机毒害物,其随大气迁移会造成污染物的长距离传输。大气中的PAHs会发生氧化降解(也称为老化),但基于不同类型颗粒物获得的非均相降解速率常数存在数量级的差异,对于实际大气颗粒物中PAHs老化过程的认识较为缺乏。本研究针对PAHs浓度较低的情况(两个观测时段PM2.5中PAHs的平均浓度分别为0.74 ng/m^(3)和0.38 ng/m^(3)),运用氧化流动管反应器(OFR)模拟了环境气溶胶的大气老化过程,对比研究老化前后10种PAHs浓度和组成的差异。结果显示,10种PAHs的非均相反应速率常数范围为0.93×10^(-12)~1.83×10^(-12) cm^(3)/(molecule·s)。大气老化时间从3 d增加到5 d,PAHs浓度的降幅从47%上升为61%,总PAHs的苯并[a]芘(BaP)毒性当量浓度(BaP_(eq))降幅从42%增加到63%,表明大气传输过程中,母体PAHs浓度和毒性均会显著降低。相比于环境样品,老化后的BaP与苯并[g,h,i]苝(BghiP)比值(BaP/BghiP)显著升高,表明该指标在区分机动车与非机动车来源时会造成误判。相关结果对于环境大气中PAHs暴露风险的准确评估和来源判识有重要启示意义。Polycyclic aromatic hydrocarbons(PAHs)are a class of organic toxicants widely present in the environment.The atmospheric PAHs can be transported over long distances.Laboratory studies have shown that atmospheric PAHs undergo oxidative degradation(also known as aging).At present,there is a lack of understanding of the aging process of PAHs in ambient particles because of the order of magnitude differences in the heterogeneous degradation rate constants obtained for different types of particulate matter.Thus,it is still a challenge to accurately assess the changes in PAHs composition and toxicity during atmospheric transport.In this study,the atmospheric aging process was simulated using an oxidation flow tube reactor(OFR)at low PAHs concentrations(the average concentrations of PAHs in PM2.5 were 0.74 ng/m^(3) and 0.38 ng/m^(3) in the two observation periods,respectively),and the differences in the concentrations and compositions of 10 PAHs were compared before and after the aging process.The results showed that the degradation rate constant of 10 PAHs was in the range of 0.93×10^(-12) to 1.83×10^(-12) cm^(3)/(molecule·s).With the increase in the atmospheric aging time from 3 to 5 days,the reductions in the PAHs concentration and toxicity equivalent concentration of benzo[a]pyrene(BaP_(eq))increased from 47% to 61% and 42% to 63%,respectively.This indicates that the concentration and toxicity of PAHs are significantly reduced during atmospheric transport.After aging,the ratios of BaP to benzo(g,h,i)perylene(BaP/BghiP)increased significantly,suggesting that this indicator can cause misclassification of motorized and non-motorized sources.These results are of great significance for accurately assessing PAHs exposure in the ambient atmosphere and identifying sources.

关 键 词：多环芳烃 大气老化 非均相反应速率常数 毒性当量浓度 特征比值 

分 类 号：X131.1[环境科学与工程—环境科学]