利用黑碳仪获取北京市冬季气溶胶吸光系数的方法研究  

Methodology of Deriving Absorption Coefficient of Winter Aerosol Using Aethalometer Measured Attenuation Coefficient in Beijing

作　　者：张宇哲[1,2] 支国瑞[1] 靳文静 张洋 程苗苗[1] 李术元[2] 张红亮 ZHANG Yuzhe;ZHI Guorui;JIN Wenjing;ZHANG Yang;CHENG Miaomiao;LI Shuyuan;ZHANG Hongliang(State Key Laboratory of Environmental Criteria and Risk Assessment,Chinese Research Academy of Environmental Sciences,Beijing 100012,China;College of Science,China University of Petroleum,Beijing 102249,China;College of Environment,Henan Normal University,Xinxiang 453007,China;Nanjing Handa ES & T Limited,Nanjing 211102,China)

机构地区：[1]中国环境科学研究院,环境基准与风险评估国家重点实验室,北京100012 [2]中国石油大学(北京)理学院,北京102249 [3]河南师范大学环境学院,河南新乡453007 [4]南京瀚达环境科技有限公司,江苏南京211102

出　　处：《环境科学研究》2019年第8期1314-1323,共10页Research of Environmental Sciences

基　　金：国家重点研发计划项目(No.2017YFC0213001);中国环境科学研究院基本科研业务专项(No.JY41373131);陕西省重点产业创新链项目(No.2015KTZDSF01-04)~~

摘　　要：黑碳仪是最常用的气溶胶吸光碳测试仪器,但其测得的吸光性能受到滤膜多重散射效应、颗粒物散射效应、颗粒物遮蔽效应的影响,只能算是 b ATN (光衰减系数),而不是 b in-situ (原位吸光系数).虽然已有学者提出几种将 b ATN 转换为 b cor (校正后吸光系数)的算法,但多是基于实验室模拟或高海拔地区气溶胶而开展的,与我国城市的气溶胶在理化性质方面有明显差别.为探索我国城市气溶胶将 b ATN 转换为 b cor 的问题,于2016—2017年冬季在北京市城区使用黑碳仪及光声消光仪分别测量 b ATN 和 b in-situ ,在分析多种算法的基础上,提出了面向城市气溶胶的校正方法.结果显示:在我国北方城市(以北京市为例),适应城市气溶胶的 f 值(遮蔽因子,为计算遮蔽校正系数的一个参数)为1.13, C (综合散射效应系数)为5.44;使用这些校正系数,将观测点由黑碳仪获取的 b ATN 转换为 b cor .与光声消光仪测定的 b in-situ 对比发现,无论是滤膜样点周期内还是长期观测时间内, b cor 与 b in-situ 均呈一致性,其中,长期观测时间内二者的相关性表达为 y =0.954 x +0.829(r 2为0.996),证明了校正方法的有效性和可信性.研究显示, b cor 与 b in-situ 整体相关性较高,并且获得了本地化的校正因子,实现了仅通过黑碳仪获取准确颗粒物吸光系数的目的.Aethalometer is the most popular equipment for the measurement of light absorbing carbon.However,what it measures is the light attenuation coefficient ( b ATN ) rather than the in-situ light absorption coefficient of aerosols ( b in-situ ) due to the influences of filter multiple scattering,particle scattering and particle shadowing.Although a few correction algorithms have been proposed by some scholars to compensate for the artifacts so as to convert the b ATN to the aerosol absorption coefficient ( b cor ),most of them are based on the aerosols from laboratory generators or from high altitudes,which are usually different in physical and chemical properties from the urban aerosols in China.To explore the methodology of conversion from b ATN to b cor for the urban aerosols in China,an aethalometer was used to monitor the b ATN and a photoacoustic Extinctiometer was used in parallel to monitor the b in-situ during the winter season of 2016-2017 in Beijing.Based on the study of the available algorithms,a method to correct the artifacts existing in aethalometer measurements of urban aerosols was proposed.It is found that the shadowing factor f (a parameter used for calculating shadowing effect coefficient) and the total scattering correction coefficient ( C ) fitting for the investigated city are 1.13 and 5.44,respectively.With these correctors,the observed b ATN values by the aethalometer were successfully converted into b cor .A comparison between PAX-measured b in-situ and aethalometer-converted b cor shows that the two absorption coefficients are similar in value and are significantly correlated both for a filter spot duration and a long-term duration (among which,the correlation of long-term duration can be represented by y =0.954 x +0.829,r 2=0.996),which demonstrates the effectiveness and reliability of the above correction scheme.This lays a good foundation for deriving b in-situ from aethalometer-measured b ATN .

关 键 词：吸光系数 黑碳仪 光学特性 北京市城区 光声消光仪 

分 类 号：X513[环境科学与工程—环境工程]