藏东南大气中多环芳烃的污染特征及来源分析

Pollution Characteristics and Source Analysis of Polycyclic Aromatic Hydrocarbons in the Atmosphere of Southeast Tibet

为探究青藏高原东南部大气中多环芳烃(Polycyclic Aromatic Hydrocarbons,简称PAHs)的污染、源及输送特征,利用鲁朗地区(29.77°N,94.73°E)总悬浮颗粒物(Total Suspended Particles,简称TSP)和大气中的14种PAHs含量,结合同期气象环境数据进行了综合分析。结果表明,该地区TSP中PAHs和气相的PAHs质量浓度变化范围分别为0.22~5.05 ng m^(-3)和0.83~63.75 ng m^(-3),平均值分别为2.13 ng m^(-3)和11.33 ng m^(-3)。薪柴和柴油的燃烧是污染的主要方式,汽油燃烧等其他排放为次要方式。PAHs来自本地污染和远距离传输(Long Range Transmission,简称LRT)共同的影响。本地污染在四季各个源地均不相同。冬春季本地污染大,源在东南及正南方,夏秋季受本地和外来输送共同作用,本地源在东南方且占比小,LRT占比大。LRT受西北气流、西风气流和西南气流三支气流影响,污染严重时西南气流占主导,西风气流次之,污染较轻时西风气流或西北气流占主导,西北气流所传输的污染最少。该研究结果加深了对藏东南区域PAHs变化、输送特征的认识,为该区域大气污染治理提供了理论依据。

To investigate the pollution,source,and transport characteristics of polycyclic aromatic hydrocarbons(PAHs)in the atmosphere of the southeast of Tibetan Plateau,a comprehensive analysis was carried out using 14 different PAHs from the total suspended particulate(TSP)matter and the atmospheric gaseous state in the Lulang area(29.77°N,94.73°E)and combined with meteorological environment data from the same period.The results show that the variation ranges of PAHs mass concentration in TSP and gas phase are 0.22–5.05 ng m^(-3) and 0.83–63.75 ng m^(-3),respectively,with average values of 2.13 ng m^(-3) and 11.33 ng m^(-3).The primary source of pollution is the combustion of firewood and diesel,while other sources of pollution include the combustion of gasoline.PAHs are emitted by both local pollution and long-range transmission(LRT).In the four seasons,local pollution varies from source to source.Local pollution is serious in the winter and spring,and the source is in the southeast and due south.Pollution in the summer and autumn is primarily caused by local and LRT sources.The primary local source is mainly in the southeast,but LRT is dominant.The northwest air flow,westerly airflow,and southwest air flow all have an impact on the LRT.When pollution is serious,the dominant airflow is southwest,while the secondary dominant airflow is westerly.When the pollution is light,the dominant airflow is westerly or northwest,and the pollution transmitted by the northwest airflow is the least.The results of this study have contributed to a better knowledge of the changes and transport characteristics of PAHs in Southeast Tibet and a theoretical basis for the control of air pollution in this region and the improvement of plateau air quality.