青岛大气气溶胶水溶性无机离子的粒径分布特征

Particle size distribution of water-soluble inorganic ions of atmospheric aerosol in Qingdao

为了解大气颗粒物中水溶性离子的来源及环境效应,利用安德森采样器连续采集青岛近海2008年1~12月大气颗粒物分级样品,用离子色谱法分析其中主要的水溶性离子,并讨论其粒径分布特征.结果表明,NH4＋、K＋、Cl-、NO3-、PO43-、SO42-主要存在于粒径小于2.1μm的细粒子中,Na＋、Mg2＋、Ca2＋、F-则主要存在于粒径大于2.1μm的粗粒子中.各离子的粒径分布存在明显的季节变化.NH4＋、K＋和SO42-四季均主要分布于细粒子中,而Mg2＋和Ca2＋则主要分布在粗粒子中,两者均在3.3~4.7μm出现峰值;Na＋在春、夏、秋3个季节主要存在于粗粒子中,集中分布在3.3~7.0μm粒径范围内,而在冬季则集中分布于0.43~1.1μm且细粒子含量高于粗粒子;春季Cl-在粗粒子中分布较多,尤以2.1~3.3μm范围内的最为突出,而其他3个季节均是细粒子比例明显偏高;NO3-春、夏两季在粗、细粒子中的含量各占50%,秋、冬季节均为细粒子占多数;PO43-夏季只出现在0.65~1.1μm以及〉11μm的粒径范围内,粗粒子占95%,其他3个季节则是细粒子含量较高;春季F-在3.3~4.7μm出现峰值,夏季各粒径均未检出,而秋、冬两季粗、细粒子各占50%.K＋、NH4＋、F-、Cl-、NO3-、SO42-和PO43-受供暖期燃煤取暖的影响较大.K＋和NH4＋在供暖期和非供暖期峰值均出现在0.43~0.65μm粒径范围;F-供暖期在0.43~0.65μm和3.3~4.7μm粒径段出现峰值;供暖期Cl-的峰值出现在0.43~0.65μm粒径段,而在非供暖期,则出现在2.1~3.3μm的粗粒径段;SO42-和NO3-在供暖期和非供暖期的峰值均出现在0.43~0.65μm和3.3~4.7μm粒径段;供暖期PO43-的最大峰值出现在0.43~0.65μm粒径段,而在非供暖期其最大峰值出现在3.3~4.7μm粒径段.

Size-segregated aerosol samples were collected from January to December in 2008 at a Qingdao coastal site to investigate the sources and environmental effects of the water-soluble ions in the particles.Concentrations of major water-soluble inorganic ions in different size bins were analyzed using ion chromatography.The results showed that NH4＋,K＋,Cl-,NO3-,PO43-,and SO42-dominantly existed in the fine particles（aerodynamic diameters less than 2.1μm）,while Na＋,Mg2＋,Ca2＋,and F-were mainly presented in the coarse particles（aerodynamic diameters larger than 2.1μm）.The size distributions of ions showed obviously seasonal variations.NH4＋,K＋ and SO42-mainly existed in the fine particles all the year around,while Mg2＋and Ca2＋mainly existed in the coarse particles with a peak in the size-bin of 3.3~4.7μm.Na＋ was mainly found in the coarse particles in spring,summer and autumn,but in the fine particles and had a concentration peak in the size-bin of 0.43~0.65μm in winter.Cl-peaked in the coarse particles with the peak in the size-bin of 2.1~3.3μm in spring while in the fine particles in other three seasons.NO3-was almost equally distributed in the fine and coarse particles in spring and summer,while showed a single peak in the accumulation mode in autumn and winter.PO43was largely distributed in the coarse particles with a predominant peak in the coarse mode of larger than 11μm and a secondary peak in the fine mode of 0.65~1.1μm in summer,but it was mainly found in the fine particles in spring,autumn and winter. F mainly existed in the coarse particles in spring and was equally distributed in the fine and coarse particles in autumn and winter. Coal combustion had a great effect on the size distributions of water-soluble ions. Both K＋ and NH4＋ reached peaks in 0.43-0.65μm during both the heating and non-heating periods. The size distribution of F was bimodal, with one peak in 0.43-0.65μm and the other in 3.3-4.7μm during the heating period. Peak concentrations of C1- appeared in the size range of 0.43-0.65μm during the heating period and 2.1-3.3μm during the non-heating period. Both SO42 and NO3 were bimodal during the heating and non-heating periods, with peak concentrations in 0.43-0.65μm and 3.3-4.7μm. The maximum concentrations of PO43 existed in 0.43-0.65μm during the heating period whilst in 3.3-4.7μm during the non-heating period.