宝鸡高新区春节前后大气中黑碳浓度特征及来源解析

Characteristics and sources analysis of black carbon concentration in the atmosphere of Baoji High-tech Zone around the Spring Festival

基于春节前后(2018年1月1日—2018年3月31日)宝鸡市高新区宝鸡文理学院站点的黑碳气溶胶(BC)、浊度仪、颗粒态污染物(PM10、PM2.5和PM1.0)、气态污染物(CO、NO2、SO2和O3)的逐时数据及常规气象数据,对宝鸡市高新区BC气溶胶的时间变化特征、来源及影响因素进行分析.结果表明,观测期间BC质量浓度的变化范围为0.01—5.62μg·m-3,平均浓度为0.63μg·m-3.BC与风速和能见度均呈负相关.观测期间BC浓度日变化呈"双峰双谷"型,峰值出现在09:00和19:00,谷值出现在05:00和16:00;寒假前BC浓度昼夜变化整体高于寒假期间和春季开学,可能与寒假前频繁的人为活动,不易扩散的气象条件有关.BC占PM2.5的0.84%,其吸收作用占大气消光的2.14%.除O3外,BC日平均浓度与PM2.5、CO和NO2呈显著相关,相关系数分别为0.626、0.623和0.473,说明BC气溶胶与之均有部分共同源.

This study used the hourly concentrations of black carbon(BC) aerosol, the nephelometer, particulate pollutants(PM10, PM2.5 and PM1.0), gaseous pollutants(CO, NO2, SO2 and O3) and meteorological data from the Spring Festival(2018-1-1—2018-3-31), observed at the site in Baoji University of arts and sciences located in Baoji High-tech Zone, to analyze the temporal characteristics of BC concentrations, sources and its influencing factors. The results showed that during the observation period, the mass concentration of BC varied from 0.01 to 5.62 μg·m-3, and the average concentration was 0.63 μg·m-3. BC concentration was negatively correlated with wind speed and visibility. During the observation period, the daily variation of BC concentration showed a "double peak and double valley" structure, with peaks appearing at 09:00 and 19:00 and valley values appearing at 05:00 and 16:00. The diurnal variation of BC concentration before the winter vacation was higher than that during the winter vacation and spring school, which might be related to the frequent human activities before the winter vacation and the weather conditions that were not easy to spread. BC accounted for 0.84% of PM2.5, and its absorption effect accounted for 2.14% of atmospheric extinction. In addition to the O3, the BC daily average concentration was significantly correlated with the concentrations of PM2.5, CO and NO2, with correlation coefficients of 0.626, 0.623, and 0.473, respectively, indicating that BC aerosol had some common sources.