重庆市春季大气PM_(10)中有机碳、元素碳浓度水平及污染特征分析

Pollution Character of Organic Carbon and Elemental Carbon in PM_(10) during Springtime in Chongqing

2006年4月于重庆市主城区9个采样点和1个城郊对照点同步采集了大气PM10样品,利用热分解示差热导法元素分析仪测定了PM10中的有机碳(OC)、元素碳(EC)的质量浓度,对OC和EC的污染水平、空间分布、OC和EC的浓度关系以及二次有机碳(SOC)等特征进行了较为详细的分析。结果显示,不同区域采样点的OC、EC浓度存在较明显差异,主城区大气环境中OC、EC平均浓度分别为52.5、8.6μg/m3,是对照点OC(16.8μg/m3)、EC(2.9μg/m3)浓度的3.1和3.0倍;主城区总碳气溶胶(TCA)占PM10总浓度的比例均值为33.3%;无论是高污染城区点还是一般城区点,OC和EC浓度间的相关性均不显著;各样点OC/EC值均超过2,表明存在二次有机碳的贡献;初步估算主城区PM10中的二次有机碳浓度均值为39.6μg/m3,占PM10总浓度的16.1%左右。

PM10 samples were collected at nine urban sites and one suburban site （background site） simultaneously in Chongqing during April, 2006, Organic carbon and element carbon in PM10 were analyzed by element analyzer. The characters such as pollution levels, spatial distributions, correlation between OC and EC, as well as secondary OC were investigated in detail. The results show that spatial variation of OC and EC concentrations were clear in different environments. The average concentration of OC and EC at urban sites were 52.5μg/m^3 and 8.6μg/m^3 , which were 3.1 and 3.0 times of that in suburban site, respectively. The average percentage of total carbon aerosol in PM10 was 33.3 % at urban sites. The correlation between OC and EC is not significant at both high pollution urban sites and ordinary urban sites, The average OC/EC at each urban site were larger than 2, indicating the existence of secondary OC. The estimated concentration of secondary OC was 39.6μg/m^3 , accounting for about 16.1% of the total PM10 in urban area.