城市间PM_(2.5)源的碳成分谱比较

Comparison of carbonaceous profiles of PM_(2.5) sources within different cities

为了解我国不同城市PM2.5源的碳成分谱特征和地域差异,采集沈阳市、十堰市和乌鲁木齐市的燃煤源、柴油车尾气源、汽油车尾气源和餐饮源样品,使用热光透射法分析PM2.5中的总碳(TC)、有机碳(OC)和元素碳(EC),以及细分的8种碳组分(OC1,OC2,OC3,OC4,EC1,EC2,EC3和OPCT),构建各类污染源碳成分谱.结果表明:3个城市4类源TC/PM2.5从高到低分别为:餐饮源(65.1%±8.4%)、柴油车尾气源(46.2%±9.5%)、汽油车尾气源(37.7%±3.5%)和燃煤源(17.3%±8.0%);OC/TC在餐饮源中最高(98.0%±0.5%),EC/TC在柴油车尾气源中最高(38.6%±8.5%).3个城市同类源的碳组分含量受污染源细分后的不同类型影响有一定差异,但归一化处理后总体仍表现为燃煤源中OC2(14%~30%)和OC3(13%~23%)含量最高,柴油车尾气源中EC2(22%~56%)含量最高,汽油车尾气源中OC2(24%~41%)、OC1(16%~42%)和OC3(12%~26%)含量最高,餐饮源中OC2(21%~43%)和OC3(23%~49%)含量最高.不同污染源的OC/EC值为燃煤源在0.4~7.6之间,柴油车尾气源在0.2~5.6之间,汽油车尾气源在1.1~38.5之间,餐饮源在6.4~170.2之间.分歧系数结果显示3个城市不同源的碳成分谱具有差异性,同类源的碳成分谱具有相似性.将3个城市同类源碳成分谱合并后利用化学质量平衡灵敏度矩阵得到OC2,OC3,OC4,EC1和OPCT可共同作为燃煤源的标识组分;EC2是柴油车尾气源的标识组分;OC1,OC2和OC3可共同作为汽油车尾气源的标识组分;OC2和OC3可共同作为餐饮源的标识组分.沈阳市、十堰市和乌鲁木齐市相同污染源相似的碳成分谱和一致的标识碳组分可为国内其他城市相关研究提供数据参考.

To investigate the characteristics and regional differences of carbonaceous profiles of PM_(2.5) sources within different cities,filter samples of coal combustion,diesel vehicles emission,gasoline vehicles emission and cooking emission from Shenyang,Shiyan and Urumqi were collected in this study.We analyzed the carbonaceous fractions(OC,EC,OC1,OC2,OC3,OC4,EC1,EC2,EC3,OPCT)based on thermal-optical transmittance method,and established the profiles of carbonaceous fractions of above four sources.The results showed that the mass fractions of total carbon(TC)in PM_(2.5) from high to low were cooking emission(65.1%±8.4%),diesel vehicles emission(46.2%±9.5%),gasoline vehicles emission(37.7%±3.5%)and coal combustion(17.3%±8.0%).The highest ratio of OC/TC was found in cooking emission,while the highest ratio of EC/TC was found in diesel vehicles emission.The levels of carbonaceous fractions within three cities can be affected by the different types of the same pollution source after subdivision.However,the overall characteristics were that the proportion of OC2 and OC3 in coal combustion were the highest,and the EC2 proportion in diesel vehicle emission was the highest,the proportion of OC2,OC1 and OC3 in the gasoline vehicles emission were the highest and the proportion of OC2 and OC3 in the cooking emission were the highest.The OC/EC ratios ranged from 0.4 to 7.6 for coal combustion,from 0.2 to 5.6 for diesel vehicles emission,from 1.1 to 38.5 for gasoline vehicles emission,and from 6.4 to 170.2 for cooking emission,respectively.The results of coefficient of divergence showed that different sources in the three cities had different profiles on the carbonaceous fractions,while the carbonaceous fractions from the same source type had similar profiles.We combined the carbonaceous fractions of the same sources type within three cities,used the modified pseudo-inverse matrix in the chemical mass balance receptor model.OC2,OC3,OC4,EC1 and OPCT.were the marker species of coal combustion;EC2 was the marker species of diesel vehicle emission;OC1,OC2 and OC3 were the marker species of gasoline vehicle emission;OC2 and OC3 were the marker species of cooking emission.We can notice that the similar carbon profiles and the consistent marker species of the same pollution sources in Shenyang,Shiyan and Urumqi can provide data reference for related researches within other cities in China.