南京市黑碳气溶胶时间演变特征及其主要影响因素

为了研究南京市黑碳（black carbon，BC）气溶胶的时间演变特征及其主要影响因素，使用多波长Aethalometer（AE-33）每个季节选取典型月份观测了BC质量浓度，结合大气污染物数据、气象要素和边界层探测数据，分析了BC的季节变化、日变化、周末效应和来源特征.结果表明，南京的BC浓度具有明显的季节变化，春季（3351±919）ng·m^-3] > 冬季（3234±2102）ng·m^-3] > 秋季（3064±967）ng·m^-3] > 夏季（2632±1705）ng·m^-3].4个季节BC日变化均为双峰型分布，峰值分别位于06：00~08：00和21：00~23：00.BC不同季节的早晚高峰分布特征不同.早高峰春季BC浓度最高，晚高峰冬季浓度最高.冬季早高峰出现时间要比其他季节滞后2 h，而夏季晚高峰时间反而比其他季节提前2 h.风速对BC日变化季节分布差异的影响远大于相对湿度（relative humidity，RH）.逆温层结对大气污染物浓度的影响机制比较复杂，在不同季节中逆温的高度、厚度和逆温强度对污染物的影响机制不同.BC不同季节的周末效应不同，风速对BC周末效应的影响较小，逆温层结差异是造成BC周末效应的主要原因.南京地区液体燃料燃烧对BC的贡献较大，固体燃烧对BC贡献较小.

Temporal Evolution and Main Influencing Factors of Black Carbon Aerosol in Nanjing

Temporal evolution of black carbon (BC) in Nanjing was studied along with its main influencing factors. The multi-wavelength aethalometer (AE-33) was used to select the typical month of each season to observe BC mass concentration, combined with atmospheric pollutant data, meteorological elements, and boundary layer detection data. Seasonal, daily, weekly trends, and source characteristics of BC were analyzed. The results showed that the BC concentration in Nanjing had obvious seasonal changes, which were higher in spring and winter, in the decreasing order:spring(3351±919) ng·m^-3] > winter(3234±2102) ng·m^-3] > in autumn(3064±967) ng·m^-3] > summer(2632±1705) ng·m^-3]. The diurnal changes in BC during the four seasons are bimodal, with peaks at 06:00-08:00 and 21:00-23:00. The morning and evening peak distribution characteristics of BC in different seasons are different. The peak concentration of BC was highest in the early morning peak spring and the highest in the late peak winter. The morning peak timing of winter is 2 h behind other seasons, while the summer peak timing is 2 h ahead of other seasons. The effect of the wind speed on the seasonal distribution of BC diurnal variation is significantly larger than that on RH. The mechanism of the influence of the inversion layer on the concentration of atmospheric pollutants is complicated. The effects of height, thickness, and temperature of the inversion layer on the pollutants are different in different seasons. Weekly BC effects vary seasonally. The effect of RH and wind speed on the weekly BC effect is small, and the difference in the inversion layer is the main reason behind it. Liquid fuel combustion in Nanjing has a greater contribution to BC, whereas solid combustion contributes by a lesser extent.