拉萨市夏季含碳气溶胶的浓度水平与组成特征研究  

Concentration level and composition characteristics of summertime carbonaceous aerosol in Lhasa

作　　者：蔡肯敏 郑雪芹 钟冰倩 尼玛楚多 边巴 王雨静 刘俊文 俞鹏飞 李军[3] 张干[3] CAI Kenmin;ZHENG Xueqin;ZHONG Bingqian;NIMA Chuduo;BIAN Ba;WANG Yujing;LIU Junwen;YU Pengfei;LI Jun;ZHANG Gan(Institute of Environment and Climate,Jinan University,Guangzhou 511443,Guangdong,China;Lhasa Meteorological Bureau,Lhasa 850000,Xizang,China;State Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China)

机构地区：[1]暨南大学环境与气候研究院,广东广州511443 [2]拉萨市气象局,西藏拉萨850000 [3]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

出　　处：《地球化学》2024年第4期496-503,共8页Geochimica

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0604);国家自然科学基金项目(41603096、41877349)联合资助。

摘　　要：利用颗粒物采样器采集拉萨市夏季(2021年8月30日~2021年9月23日)大气细颗粒物(PM_(2.5))样品,并对不同含碳气溶胶组分进行测定和探讨。根据碳组分挥发性的强弱,将有机碳(OC)分为易挥发组分(HOC)、中等挥发组分(MOC)和难挥发组分(LOC),元素碳(EC)分为焦碳(char)和烟炱(soot)。结果显示,拉萨市夏季大气环境白天OC和EC的平均浓度分别为4.39±0.98μg/m^(3)和1.09±0.69μg/m^(3),夜晚OC和EC的平均浓度分别为4.39±1.43μg/m^(3)和1.17±0.57μg/m^(3)。系统比较OC/EC和char/soot源示踪指标在源辨识上的差异,发现char/soot值比OC/EC值可以更准确地识别关键排放源对含碳气溶胶的影响,说明char/soot值是一个可靠的源解析工具。本研究测定的char/soot平均值为0.20,符合机动车尾气污染特征,远小于生物质燃烧和煤炭燃烧特征值,说明拉萨夏季大气环境主要受机动车尾气排放影响。LOC是拉萨夏季含碳气溶胶最丰富的OC组分,在所有碳组分中的占比为47.7%,其次为MOC(18.2%)和HOC(10.8%)。不同碳组分之间的相关性分析表明,HOC主要通过大气化学反应生成,未来可成为评估二次有机气溶胶的一个潜在指标。Atmospheric fine particulate matter(PM_(2.5))samples were collected by a particle sampler in Lhasa during summer,and different carbonaceous aerosol components were determined.According to the volatility of carbon components,organic carbon(OC)can be divided into high volatile OC(HOC),median volatile OC(MOC),and low volatile OC(LOC),while elemental carbon(EC)can be divided into char and soot.The results showed that the average concentrations of OC and EC were 4.39±0.98μg/m^(3)and 1.09±0.69μg/m^(3)at daytime and 4.39±1.43μg/m^(3)and 1.17±0.57μg/m^(3)at nighttime,respectively.We thoroughly explored the ability of source identification for OC/EC and char/soot as source indicators and found that the char/soot ratio can more accurately identify the influence of emission sources on carbonaceous aerosols than the OC/EC ratio.This suggests that char/soot is a more reliable source analysis tool.In this study,the average char/soot value was 0.20,which corresponds to the characteristics of vehicle exhaust,and was much lower than those of biomass and coal combustion.This indicates that in summer,vehicle exhaust emissions primarily affect the atmospheric environment in Lhasa.LOC is the most abundant organic component of carbonaceous aerosols in Lhasa during summer,accounting for 47.7%,followed by MOC(18.2%)and HOC(10.8%).Correlation analysis showed that HOC is mainly generated through atmospheric chemical reactions and can be used as a potential index for the evaluation of secondary organic aerosols.

关 键 词：含碳气溶胶 有机碳 元素碳 碳组分 OC/EC char/soot 

分 类 号：X131.1[环境科学与工程—环境科学] X142