邯郸市黑碳气溶胶浓度变化及影响因素分析

根据2013年3月—2017年2月邯郸市河北工程大学站点的黑碳气溶胶、PM2.5、大气污染物的小时浓度数据及常规气象数据,对邯郸市黑碳浓度的时间变化特征及影响因素进行分析.结果表明,4年来邯郸市黑碳浓度呈逐年下降的趋势:与2013年相比,2014—2016年黑碳气溶胶浓度分别下降了5%、16%、24%;邯郸市黑碳气溶胶浓度的季节变化趋势基本一致且季节变化特征明显,冬季黑碳气溶胶浓度最高,秋季次之,春夏两季最低,其中,冬季平均浓度分别是春、夏、秋季的2.07、2.77、1.49倍;其日变化呈单峰单谷状,且4个季节的日变化趋势相同,峰值均出现在6:00—8:00,谷值均出现在14:00—15:00.黑碳与PM2.5的相关系数r为0.860,相关性显著,说明黑碳气溶胶和PM2.5的来源大部分是一致的;风速和风向对黑碳气溶胶浓度也有影响,黑碳气溶胶浓度随风速增加而降低;4个季节高频风向为南-西南方向,且该风向下黑碳气溶胶浓度均较高,冬季南-西南风向下的黑碳浓度最高;应用后向轨迹对研究时段内4段重污染期间的气流轨迹进行模拟发现,邯郸市黑碳气溶胶浓度较高的主要原因是本地源排放和近距离传输,远距离传输贡献较小.

Variation of black carbon aerosol concentration and its influencing factors in Handan City, Hebei Province

This study used the hourly concentrations of black carbon (BC) aerosol, PM_2.5, major gaseous pollutants, and meteorological data from March 2013 to February 2017, observed at the site in Hebei University of Engineering located in Handan, to analyze the temporal characteristics of BC concentrations and its influencing factors. Our results showed that the concentration of BC in Handan kept decreasing in the past 4 years, and its concentrations decreased by 5%, 16%, and 24% respectively, in 2014-2016 comparing with 2013. The seasonal variations of BC concentrations in Handan were consistent in the past 4 years, the highest concentration occurred in winter, followed by autumn, spring, and summer. The average concentrations of BC in winter was 2.07, 2.77, and 1.49 times of those in spring, summer and autumn, respectively. The daily variations presented unimodal, and the peak value appeared at 6:00-8:00, the valley value appeared at 14:00-15:00, which was same to four seasons. We also found that the r of BC and PM_2.5 was 0.860, indicating that the sources of BC and PM_2.5 are very consistent. Wind speed and wind direction also had influence on BC concentration, its concentrations would decrease when wind speed increased, and the south-southwest direction had higher frequencies in all seasons which accompanied by higher BC concentrations. The highest BC concentrations occurred under south-southwest wind direction. By applying the backward trajectory for 4 heavy pollution processes, we found that the main contributor for the high concentrations of BC in Handan was local source emissions, and the long distance transport contributed only a small fraction.