摘要
采用离线分析法和在线分析法同步监测了武汉市PM_(2.5)中有机碳(OC)、元素碳(EC)和总碳(TC)的浓度,分析了2种方法的差别。结果表明,离线分析法与在线分析法对TC的测定结果具有很好的可比性,2种方法对TC的测定结果显著相关(r=0.970 9)。离线分析法得到的OC浓度普遍高于在线分析法,前者为后者的1.12倍,造成OC结果差异的主要原因可能是采样系统的差异。2种方法对EC测定的相关性较低(r=0.763 0),且2种方法对EC测定的精密度(相对偏差为13.14%)也不如其对TC和OC测定的精密度(相对偏差分别为3.42%和5.95%),造成EC结果差异的原因较复杂。离线分析法测得的OC/EC值明显高于在线分析法,鉴于OC/EC值在颗粒物源解析研究中具有重要意义,需要规范OC/EC分析方法。
The concentration of organic carbon(OC), elemental carbon(EC) and total carbon(TC) in fine particulate matter(PM_(2.5)) of Wuhan city were simultaneously analyzed by off-line analysis and on-line analysis methods. The differences between the results of these two methods were compared. The results showed that the concentration of total carbon(TC) was well correlated with off-line analysis and on-line analysis, with the correlation coefficients r was 0.9709, these two methods were in good agreement with TC determination. The concentration of OC obtained by off-line analysis was generally higher than that of OC obtained by on-line analysis, with the former was 1.12 times higher than the latter. The main reason that the results of OC obtained by off-line analysis was higher than on-line analysis may be due to the difference of sampling system. The correlation between these two methods for EC determination was lower(r=0.7630), and the precision(relative deviation was 13.14%) of these two methods for EC determination was also lower than that for TC and OC determination(relative deviations were 3.42% and 5.95%, respectively). The reasons for the differences in EC results were more complicated. The OC/EC ratio measured by off-line analysis method was obviously higher than on-line analysis method. In view of the significance of OC/EC ratio in source apportionment of particulates, it is need to standardize the OC/EC analysis method.
引文
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