南京冬夏硫酸盐和硝酸盐对黑碳混合态的影响

采用单颗粒黑碳光度计（SP2）结合MARGA在线分析仪对南京地区冬季和夏季黑碳（BC）的质量浓度，以及硫酸盐，硝酸盐对其混合状态的影响进行了研究.结果表明，冬季和夏季南京地区BC质量浓度分别在1.01~14.5μg/m³和0.20~3.81μg/m³之间，均值分别为（4.39±2.66）μg/m³和（1.67±0.76）μg/m³，均呈现早晚高值的双峰型日变化特征.运用相对包裹层厚度D_p/D_c表示BC混合状态，冬季和夏季D_p/D_c分别在1.39~2.34和1.03~1.45之间，均值分别（1.81±0.21）和（1.24±0.08），D_p/D_c日变化特征与BC相反，冬季D_p/D_c日变化幅度较大.冬季D_p/D_c与SO₄^2-和NO₃^-的相关性较好，D_p/D_c与NO₃^-的相关性高于其与SO₄^2-的相关性，夏季则相反.冬季清洁时期BC以本地源排放为主，其混合状态受硫酸盐和硝酸盐影响较高，冬季重污染时期，受排放源以及区域传输的影响，D_p/D_c与SO₄^2-和NO₃^-的相关性较低.

Impact of sulfate and nitrate on black carbon aerosols at Nanjing in winter and summer

The impact of nitrate and sulfate aerosols on the mixing state of black carbon (BC) particles was investigated by using on-line measurements of a single particles soot photometer (SP2) and a MARGA in urban Nanjing in winter and summer. Results showed that the mass concentration of BC was in the range of 1.01~14.5μg/m³ (0.20~3.81μg/m³), with an average value of (4.39±2.66)μg/m³(1.67±0.76)μg/m³] inwinter (summer), respectively. The diurnal variations of BC particles presented two peaks relative to rush hours in morning and evening. The mixing state of BC-containing particles were evaluated as a ratio of D_p/D_c, the average ratio of which was 1.81±0.21 (1.24±0.08) and ranged from 1.39 to 2.34 (from 1.03 to 1.45) in winter (summer), respectively. D_p/D_cshowed an opposite diurnal trend as comparing with BC, where made more obvious variations for winter. D_p/D_ccorrelated well with sulfate and nitrate, and showed higher correlation with nitrate (sulfate) in winter (summer), respectively. Local emissions were the major source contributing to BC, the mixing state of which was more significant influence of nitrate and sulfate during clean periods in winter. The correlation between D_p/D_cwith sulfate and nitrate in winter was lower during heavy pollution periods, resulting from the effects of both local emissions and regional transports on ambient BC particles.