菏泽市PM_(2.5)碳组分季节变化特征

Seasonal Variation of Carbon Fractions in PM_(2.5)in Heze

于2015年8月到2016年4月在菏泽市城区采集PM_(2.5)颗粒,利用热/光碳分析仪测定了颗粒物中8种碳组分,获得了有机碳(OC)和元素碳(EC)的质量浓度,分析了OC与EC的比值、相关性,使用OC/EC比值法估算了二次有机碳(SOC)的浓度,并使用主成分分析法研究8种碳组分含量.结果表明,(1)PM_(2.5)中OC、EC的年质量浓度变化范围分别为1.2~60.6μg·m^(-3)、0.6~24.8μg·m^(-3),OC/PM_(2.5)、EC/PM_(2.5)的季节分布特征相似:冬季>春季>秋季>夏季;(2)OC/EC的年平均值为2.6±1.0,春夏秋冬OC、EC的相关系数分别为0.91、0.56、0.86、0.75,估算的SOC年平均浓度为(4.7±5.0)μg·m^(-3);(3)不同季节8种碳组分质量分数均为EC1最高,EC3最低.主成分分析结果显示,春秋冬这3个季节碳组分的主要来源为燃煤、机动车和生物质燃烧.

PM2.5 samples were collected in Heze from August 2015 to April 2016. Eight carbon fractions were analyzed by a thermal/optical carbon analyzer, and organic carbon （ OC） and elemental carbon （ EC） analyses were obtained. The OC/ EC ratio and the correlation between OC and EC were analyzed. Secondary organic carbon （SOC） mass concentration was estimated by the OC/ EC ratio method; and eight carbon fractions were analyzed using a principal component analysis. The results showed that： ① The annual average mass concentrations of OC and EC were 1. 2-60. 6 μg·m - 3 and 0. 6-24. 8 μg·m - 3 , respectively; and the characterization of OC and EC percentages in PM2. 5 during different seasons were similar with winter 〉 spring 〉 autumn 〉 summer. ② The annual average OC/ EC ratio was 2. 6 ± 1. 0, and the correlations between OC and EC during spring, summer, autumn, and winter were 0. 91, 0. 56, 0. 86, and 0. 75, respectively, and the estimated mass concentration of SOC was （4. 7 ± 5. 0） μg·m - 3 . ③The characterization of eight carbon fractions percentages in PM2. 5 in the different seasons demonstrated similar seasonal variations, with EC1 having the highest percentage and EC3 having the lowest percentage. The result of the principal component analysis showed that coal burning, motor vehicle emissions, and biomass burning were the major sources of carbon.