2019年西安市大气PM_(2.5)中多环芳烃污染特征及来源分析

Analysis on pollution characteristics and sources of polycyclic aromatic hydrocarbons in atmospheric PM_(2.5) of Xi’an City in 2019

目的了解2019年西安市大气细颗粒物(fine particulate matter,PM_(2.5))中多环芳烃污染水平及特征,并对其来源进行分析。方法2019年1—12月,对西安市两个监测点采集的PM_(2.5)样品中16种多环芳烃进行分析,采用毒性当量浓度对多环芳烃的毒性进行评价,采用特征比值对多环芳烃的来源进行分析。结果西安市PM_(2.5)的24 h平均浓度为84.39μg/m^(3),采暖期PM_(2.5)的24 h平均浓度高于非采暖期(P<0.05);西安市总多环芳烃的年平均浓度为19.50 ng/m^(3),采暖期总多环芳烃的24 h平均浓度高于非采暖期(P<0.05);西安市16种多环芳烃总毒性当量浓度为2.65 ng/m^(3),其中苯并[a]芘的毒性当量浓度最高,7种致癌多环芳烃的毒性当量浓度占总毒性当量浓度的99.05%,采暖期总毒性当量浓度远高于非采暖期;西安市不同环数多环芳烃占总多环芳烃的比例为4环>5环>6环>2~3环,与采暖期相比,非采暖期2~3环和6环有所增加;西安市及采暖期多环芳烃的主要来源为燃煤、生物质燃烧、机动车燃油和石油挥发源,非采暖期多环芳烃的主要来源为燃煤和机动车燃油。结论2019年西安市大气污染情况,尤其是采暖期较为严峻,其对居民健康及生活的影响不容忽视,应加强对大气环境的治理,促进产业转型升级,从根本上减少污染源的排放。

Objective To investigate the pollution levels and characteristics of polycyclic aromatic hydrocarbons(PAHs)in atmospheric fine particulate matter(PM_(2.5))of Xi’an City in 2019,analyze the sources of PAHs.Methods Totally 16 kinds of PAHs in PM_(2.5) samples collected from two monitoring sites in Xi’an City were analyzed from January to December 2019.The toxicity of PAHs was evaluated by toxic equivalent concentration(TEQ),and the sources of PAHs were analyzed by characteristic ratio.Results The24-hour average concentration of PM_(2.5) in Xi’an City was 84.39μg/m^(3),and the 24-hour average concentration of PM_(2.5) in heating period was higher than that in non heating period(P<0.05).The annual average concentration of total PAHs in Xi’an City was19.50 ng/m^(3),and the 24-hour average concentration of total PAHs in heating period was higher than that in non heating period.The total TEQ of 16 PAHs in Xi’an was 2.65 ng/m^(3),of which benzo[a]pyrene had the highest TEQ,and the TEQ of seven carcinogenic PAHs accounted for 99.05%of total TEQ.The total TEQ in heating period was much higher than that in non heating period.The proportion of PAHs with different rings to the total PAHs in Xi’an City was 4-ring>5-ring>6-ring>2-3-ring.Compared with heating period,the proportion of 2-3-ring and 6-ring PAHs were increased in non heating period.Coal,biomass combustion,motor vehicle fuel and petroleum volatilization were the main sources of PAHs in Xi’an City and heating period,and the main sources during non heating period were coal and motor vehicle fuel.Conclusion The air pollution in Xi’an City in 2019,especially in heating period,is still serious.Its impact on health and life of residents can not be ignored.It is necessary to strengthen the management of the atmo-spheric environment,promote the industrial transformation and upgrading,and fundamentally reduce the emission of pollution sources.