2015年1月16~26日长江三角洲(以下简称长三角)地区出现了一次持续区域性重污染过程,为研究重污染过程期间含碳气溶胶的区域分布特征及其来源.使用中流量采样器分别对南京、苏州和临安1月13~28日PM2.5进行了连续采样,并使用Model 2001A热/光碳分析仪分析了样品中的有机碳(OC)和元素碳(EC)含量.结果表明:长江三角洲地区冬季重污染过程中以PM(2.5)污染为主,南京、苏州、临安PM(2.5)的平均浓度分别为176.84,176.65,158.07μg/m^3,是清洁天的1.91、2.01和2.97倍.含碳气溶胶是PM(2.5)的重要组成部分,总碳(TC,TC=OC+EC)占PM(2.5)的比例分别为南京(18%)、苏州(21%)、临安(23%).轻度污染天和中/重度污染天,长三角地区PM(2.5)中OC的平均浓度分别为20.75,32.64μg/m^3,为清洁天的1.66和2.61倍;EC的平均浓度分别为5.41,8.87μg/m^3,为清洁天的2.06和3.37倍.污染过程中不同碳组分的变化特征不同.一次有机碳(POC)、二次有机碳(SOC)、焦炭(Char-EC)的浓度随着污染程度的加剧而不断上升;烟炱(Soot-EC)随着污染程度变化较小.4个采样时段中,OC、EC浓度峰值出现于15:00-20:40时段.污染期间,长三角地区含碳气溶胶的主要来源为燃煤和机动车尾气,同时还有部分生物质燃烧源的影响,柴油车尾气的影响较弱.清洁天,影响长三角地区的气团主要来自于海洋上空,气团较为清洁,碳气溶胶来源简单;污染天气团主要来自于我国西北地区及长三角周边省份,受到外来输送与本地源排放的影响,使得碳气溶胶来源变得相对复杂.
To characterize the regional distribution and identify the sources of carbonaceous aerosol in a long-lasting regional haze episode, which happened in winter in the Yangtze River Delta(YRD) from Jan 16 th to 26 th in 2015, continuous measurements of PM(2.5) were conducted from Jan 13 th to 28 th in 2015 in three cities-Nanjing, Suzhou, Lin'An. The carbonaceous components were quantified with the thermal optical reflectance(TOR) method. The results showed that: PM(2.5) was the chief pollutant in the Yangtze River Delta(YRD) during this haze episode. The daily average concentrations of PM(2.5) in Nanjing, Suzhou and Lin'An during haze episode were 176.84, 176.65 and 158.07μg/m^3, respectively, and they were 1.91, 2.01 and 2.97 times as high as the concentrations in clean days, respectively. The carbonaceous aerosol were the important part of PM(2.5), and the proportions of TC in PM(2.5) were 18%, 21% and 23% in Nanjing, Suzhou and Lin'An, respectively. During light polluted days and moderate or heavy polluted days, the mass concentrations of OC were 20.75 and 32.64μg/m^3, which were 1.66 and 2.61 times as high as the concentrations in clean days; the mass concentrations of EC were 5.41 and 8.87 μg/m^3, which were 2.06 and 3.37 times as high as the concentrations in clean days. The characteristics of different carbonaceous components varied during the polluted episode; the mass concentrations of the primary and secondary organic carbon(POC, SOC) and Char-EC increased from clean days to the heavy polluted days. However, the mass concentrations of Soot-EC almost remained unchanged. The peak of diurnal variation of OC and EC appeared at 15:00 to 20:40. During the polluted episode, the main sources of carbonaceous aerosols were coal burning and vehicle emission. What's more, biomass burning also contributed to OC and EC burden, while the contribution of diesel vehicle was little. During the clean days, the air trajectories came from the sea, where the air was clean, ca