Xu Hong-Hui, Xu Jing-Sha, He Jun, Pu Jing-Jiao, Qi Bing, Du Rong-Guang
Zhejiang Institute of Meteorological Sciences, Hangzhou 310008, China.
Department of Chemical and Environmental Engineering, University of Nottingham Ningbo China, Ningbo 315100, China.
Huan Jing Ke Xue. 2018 Aug 8;39(8):3511-3517. doi: 10.13227/j.hjkx.201712245.
To investigate the seasonal variations and sources of carbonaceous aerosols in the cities of Hangzhou and Ningbo, field PM sampling was conducted at four representative sites (two urban, one suburban, and one rural) in this region from December 2014 to November 2015. A thermal/optical carbon analyzer was employed to analyze both organic carbon (OC) and elemental carbon (EC) contents in PM by identifying eight different carbon fractions, including OC1, OC2, OC3, OC4+OPC, EC1-OPC, EC2, and EC3. Based on these fractions, OC and EC were defined as OC1+OC2+OC3+OC4+OPC and EC1+EC2+EC3-OPC, respectively; total carbon (TC) was calculated as the sum of OC and EC; and total carbonaceous aerosols (TCAs) were quantified via the sum of organic aerosols (OAs; converted from OC) and EC. The results showed the following. ①The annual average level of TC in this region was (14.3±4.1) μg·m, accounting for (26.2±6.5)% of the annual average PM concentration. The annual average OC and EC concentrations were (11.3±3.4) μg·m and (3.0±0.9) μg·m, respectively. The highest TC level was observed in winter among the four seasons. ②The annual average TCA concentration in this region was (25.6±7.5) μg·m, contributing (42.2±10.0)% of PM. In addition, secondary organic carbon (SOC) was also estimated by the commonly applied EC method. It was found that SOC contributed (41.1±5.5)% to OC on an annual average basis. ③The sources of carbonaceous aerosols were determined using the correlation between OC and EC, OC/EC mass ratio, and different carbon fraction characteristics. The annual average OC/EC ratio in this region was 4.7±1.7, which falls in the diagnostic ratio range for vehicular emissions, coal combustion, and biomass burning, indicating these sources are probably the major contributors of the regional carbonaceous aerosols. Moreover, a higher char-EC/soot-EC ratio was observed during winter and autumn at all sites, possibly implying the enhanced biomass burning activities during these two seasons.
为研究杭州和宁波两市碳质气溶胶的季节变化及来源，于2014年12月至2015年11月在该地区四个代表性站点（两个城市站点、一个郊区站点和一个农村站点）进行了PM现场采样。采用热/光碳分析仪通过识别八个不同的碳组分（包括OC1、OC2、OC3、OC4 + OPC、EC1 - OPC、EC2和EC3）来分析PM中的有机碳（OC）和元素碳（EC）含量。基于这些组分，OC和EC分别定义为OC1 + OC2 + OC3 + OC4 + OPC和EC1 + EC2 + EC3 - OPC；总碳（TC）计算为OC和EC之和；总碳质气溶胶（TCA）通过有机气溶胶（OA；由OC转换而来）和EC之和进行定量。结果如下：①该地区TC的年平均水平为（14.3±4.1）μg·m，占年平均PM浓度的（26.2±6.5）%。OC和EC的年平均浓度分别为（11.3±3.4）μg·m和（3.0±0.9）μg·m。四个季节中冬季的TC水平最高。②该地区TCA的年平均浓度为（25.6±7.5）μg·m，占PM的（42.2±10.0）%。此外，还通过常用的EC方法估算了二次有机碳（SOC）。发现SOC年均占OC的（41.1±5.5）%。③利用OC与EC的相关性、OC/EC质量比以及不同碳组分特征确定了碳质气溶胶的来源。该地区OC/EC的年平均比值为4.7±1.7，落在车辆排放、煤炭燃烧和生物质燃烧的诊断比值范围内，表明这些来源可能是区域碳质气溶胶的主要贡献者。此外，在所有站点的冬季和秋季均观察到较高的焦炭EC/烟灰EC比值，这可能意味着这两个季节生物质燃烧活动增强。
