南京北郊黑碳气溶胶的来源解析

Source Apportionment of Black Carbon Aerosol in the North Suburb of Nanjing

利用七波段黑碳仪对2015年1~12月南京北郊地区黑碳(black carbon,BC)气溶胶实时监测,并结合黑碳仪模型对该期间内BC进行来源解析,探讨化石燃料排放产生BC(BCff)与生物质燃烧产生BC(BCbb)各自的贡献大小.结果表明,观测期间BC的吸收波长指数(α)和生物质燃烧对BC的贡献百分比(BB)的变化范围都较大但趋势较为一致;冬季α值偏高而夏季α值较低,表明不同季节时间BC来源和强度的差异性.BCff在各季节BC总浓度中占比略有不同但均高于75%;BC、BCff和BCbb的日变化趋势均呈双峰特征,在07:00~09:00和18:00~21:00左右浓度有最大值;全天中,BCff对BC贡献最大,浓度值约为BCbb的3~5倍;夜晚BC浓度普遍高于白天,其平均浓度值是白天的1.2倍.由浓度权重轨迹分析的结果可知,影响南京北郊地区高浓度BC的源区主要集中在浙江、安徽以及江西和福建等地区.

Based on one year real-time measurements from a seven-wavelength Aethalometer combined with an Aethalometer model,the measured aerosol absorption coefficients at different wavelengths have been used to apportion the contribution of fossil fuel and biomass burning sources to the total black carbon（BC） mass concentration in the north suburb of Nanjing.Good consistency in the relationship between the Angstrom absorption exponent（α） and the ratio of BC from biomass burning sources to total BC（BB） was obtained during this period.The α was highest in winter and lowest in summer,which indicates the change in the source of the absorbing aerosols and their relative source strength.The BC and the BC from fossil fuel（BCff） and biomass burning（BCbb） mass concentrations exhibit significant diurnal variation,with higher values during 07：00 to 09：00（local time） and 18：00 to 21：00.The BCffwas three to five times higher than the BCbband contributes greatest to the BC mass concentrations throughout the day.Night time BC values were about a factor of 1.2 higher than day time BC values.Meanwhile,the concentration weighted trajectory（CWT） analysis indicates that the highest value of BC was concentrated in the Zhejiang,Anhui,Jiangxi,and Fujian provinces.