石家庄市城区和郊区细颗粒物碳组分污染特征及来源对比分析

Comparative analysis of pollution characteristic and source of carbon components in fine particulate matter in urban areas and suburbs of Shijiazhuang

为探索石家庄市城区和郊区细颗粒物(PM_(2.5))碳组分的异同,2019年1、4、7、10月在石家庄市城区、郊区采集大气PM_(2.5)样品,并测定了其中有机碳(OC)和元素碳(EC)的浓度。结果表明:(1)石家庄市城区、郊区年平均OC在总碳组分中占比分别为83.9%(质量分数,下同)、85.7%,明显大于EC,表明OC为石家庄市PM_(2.5)的主要碳组分。城区二次OC(SOC)年平均质量浓度(5.42μg/m^(3))高于郊区(5.09μg/m^(3)),说明城区二次污染高于郊区。(2)城区和郊区各季节OC、EC相关性均为秋季>冬季>春季>夏季。(3)城区、郊区四季碳组分中均为裂解碳(OPC)、EC1(含2%(体积分数)氧气的氦气环境下升温至580℃得到)占比较大。冬季OC2(无氧纯氦气的环境下升温至280℃得到)浓度均高于其他季节,秋冬OC3(无氧纯氦气的环境下升温至480℃得到)浓度高于春夏。

In order to explore the similarities and differences of PM_(2.5) carbon components in urban areas and suburbs of Shijiazhuang,PM_(2.5) samples were collected in urban areas and suburbs of Shijiazhuang in January,April,July,and October 2019,and the concentrations of organic carbon(OC)and elemental carbon(EC)were determined.The results showed that:(1)the annual average concentration of OC accounted for 83.9%(mass fraction,the same below)and 85.7%of the total carbon components in urban areas and suburbs,which were significantly higher than EC,indicating that OC was the main carbon component in PM_(2.5) in Shijiazhuang.The annual average secondary organic carbon(SOC)concentration in urban areas(5.42μg/m^(3))was higher than that in suburbs(5.09μg/m^(3)),indicating that secondary aerosol pollution in urban areas was higher than that in suburbs.(2)The correlation of OC and EC was autumn>winter>spring>summer.(3)Pyrolytic carbon(OPC)and EC1(obtained by heating to 580℃in helium environment containing 2%(volume fraction)oxygen)accounted for large proportions of carbon components in urban areas and suburbs in the four seasons.The concentration of OC2(obtained by heating to 280℃in pure helium environment)in winter was higher than that in other seasons,and the concentration of OC3(obtained by heating to 480℃in pure helium environment)in autumn and winter was higher than that in spring and summer.