成都春季生物质燃烧和沙尘期间气溶胶散射特征及其重建

于2009年4月19日～5月17日在成都城区每天采集PM2.5样品.利用热光碳分析仪、离子色谱、X荧光光谱仪和高效阴离子交换色谱分别分析样品中有机碳/元素碳、水溶性离子、地壳元素和左旋葡聚糖,同步测量了大气散射系数(bsp)和气象数据.利用IMPROVE方程重建大气散射系数,并与实测大气散射系数进行对比.结果发现,PM2.5浓度均值为133.2μg.m-3,大气散射系数为530 Mm-1.左旋葡聚糖和地壳元素能很好地反映生物质燃烧和沙尘事件.观测期间成都城区计算值b’sp为504 Mm-1,(NH4)2SO4、NH4NO3、OM(organic matter)、FS(fine soil)和CM(coarse mass)贡献率分别为26%、15%、53%、4%和2%.DS(dust storm)期间,计算值b’sp为575 Mm-1,FS和CM贡献率达到17%和21%.BB(biomass burning)期间,计算值b’sp为635 Mm-1,OM贡献率达到62%.

Characterization and Reconstruction of Aerosol Light Scattering Coefficient at Chengdu During Biomass Burning and Dust Storm Period in Spring

Aerosol samples for PM2.5 were collected from 19 April to 17 May in 2009 at Chengdu.The concentrations of organic carbon,element carbon,water-solubility ions,crustal elements and levoglucosan of all particle samples were determined by thermal/optical carbon analyzer,ion chromatography,X-ray fluorescence spectrometer and high performance anion exchange chromatography,respectively.In-situ scattering coefficients(bsp) and meteorological parameters for this period were also conducted.Ambient scattering coefficients were reconstructed by IMPROVE formula and compared with measured scattering coefficients.The results showed that the average mass concentration of PM2.5 and measured bsp were 133.2 μg·m-3 and 530 Mm-1,respectively.Levoglucosan and crustal elements were good traces for biomass burning and dust storm events,respectively.The calculated b′sp was 504 Mm-1 during campaigning period.The major contributors to scattering coefficients included:(NH4)2SO4(26%),NH4NO3(15%),OM(53%),FS(4%) and CM(2%),respectively.The calculated b′sp was 575 Mm-1 and the dominant species were FS(17%) and CM(21%) during dust storm period(DS).The calculated b′sp was 635 Mm-1 and OM contributed 62% during biomass burning(BB) period.