天津滨海新区大气细颗粒物载带碳组分特征

Characterization of Carbonaceous Aerosols at Binhai District,China

为了研究天津滨海新区大气细颗粒物载带的碳组分浓度水平和来源,于2017年7月在东疆海泽物流园设置了大气监测点,采集PM_(2.5)样品.基于热光反射法(TOR),测定PM_(2.5)中有机碳(OC)和元素碳(EC)的浓度水平、污染特征;利用OC/EC比值法、相关分析法和浓度丰度法等方法对大气颗粒物中碳组分的可能来源等进行分析.结果表明,监测期间滨海新区PM_(2.5)的平均质量浓度为84.65μg·m^(−3),高于国家二级标准限值(75μg·m^(−3)),其中,OC和EC的平均浓度分别为21.03μg·m^(−3)和8.12μg·m^(−3),各占PM_(2.5)的26.2%和9.9%.本次研究样本OC/EC比值在2.07-3.53,平均值为2.66,表明滨海新区存在明显的二次污染,二次有机碳(SOC)含量为4.23μg·m^(−3),占OC的20.1%;对OC、EC进行相关性分析,结果显示,两者相关性较好(R=0.776,P<0.01),具有共同的一次来源;基于浓度丰度法对PM_(2.5)中8种碳组分浓度进行分析对比,结果显示滨海大气颗粒物中的碳组分主要来源为机动车排放的汽油尾气,部分来源于燃煤和道路扬尘.

To understand the concentration and source characteristics of carbonaceous aerosols in Tianjin Binhai district,fine particle was collected in Dongjiang logistics park.OC and EC concentrations were analyzed by the IMPROVE thermal/optical reflectance(TOR)protocol.And emission sources of carbonaceous species were analyzed based on OC/EC ratio,pollutant concentration and correlation results.During the observation campaign,the average concentration of PM_(2.5) was 84.65μg·m^(−3),higher than the Class 2 of PM_(2.5) standard(75μg·m^(−3))in China.The average concentrations of organic carbon(OC)and element carbon(EC)in PM_(2.5) were 21.03μg·m^(−3),and 8.12μg·m^(−3),accounting for 26.2%and 9.9%of particulate mass,respectively.The OC/EC ratios varied from 2.07-3.53,with an average value of 2.66,indicating the contribution of secondary pollution in Binhai District.Secondary organic carbon(SOC)calculated based on minimum OC/EC ratio method was 4.23μg·m^(−3),accounting for 20.1%of OC.OC and EC were well related with each other(R=0.776,P<0.01),indicating they shared common emission sources.Based on the analysis of eight carbon fraction concentrations,vehicle emission was the predominant source of carbonaceous aerosols in Binhai District,while coal combustion and road dust had less contribution.