典型海滨城市与海洋气溶胶中水溶性离子的粒径分布  

Size Distributions of Water-soluble Ions in Aerosols from a Coastal Urban Site and the Ocean

作　　者：刘元隆[1] 张银菊[1] 黄帅[1] 胡清华 林长城[3] 吴水平[1] 

机构地区：[1]厦门大学环境与生态学院,福建厦门361102 [2]福建省环境监测中心站,福建福州350003 [3]福建省气象科学研究所,福建福州350001

出　　处：《厦门大学学报（自然科学版）》2016年第4期531-539,共9页Journal of Xiamen University：Natural Science

基　　金：国家自然科学基金(41471390);厦门大学-贵州师范大学山海科研基金(2013SH011)

摘　　要：为研究厦门地区不同粒径颗粒物中水溶性离子的来源及海洋气溶胶对海滨城市大气颗粒物的影响,利用8级大流量MOUDI碰撞采样器分不同季节在厦门大学海洋楼及台湾海峡采集了气溶胶分级样品,并用离子色谱方法对气溶胶中的水溶性离子进行了分析.结果表明:城市点大气气溶胶中水溶性离子总质量浓度表现为春季最高(60.38μg/m^3)、夏季最低(8.76μg/m^3)、秋冬季介于两者之间的季节特征;而海洋气溶胶中水溶性离子质量浓度的季节差异较小(30.77~35.13μg/m^3).城市气溶胶中SO_4^(2-)和NH_4^+呈单模态分布,峰值粒径为0.44~1.0μm;NO_3^-呈双模态分布,峰值粒径分别为2.5~10.0μm和0.44~1.0μm.海洋气溶胶中NH_4^+和SO_4^(2-)的粒径分布规律与城市气溶胶类似,但NO_3^-在细模态(0.44~1.0μm)没有出现峰值,Cl^-和Na^+在大于16μm的粒径段有非常高的浓度,说明海浪飞沫的影响较大,在粗模态中的比例也明显高于城市气溶胶.干沉降速率为颗粒物大小的函数,其中在0.1μm左右的颗粒干沉降速率最小;通过干沉降速率和它们的浓度分布来计算无机氮(NO_3^-和NH_4^+)的沉降通量,估算得到远海颗粒态无机氮的干沉降通量明显超过近海(秋季NH_4^+除外).In order to study the sources of water-soluble ions in different particle size in Xiamen and the influence of sea salt aerosols to the atmospheric particles of coastal city,we collected size-fractionated aerosols from a coastal urban site （Xiamen University Oceanography Build-ing）and Taiwan Strait （the ocean）in different seasons using high volume MOUDI sampler equipped with Teflon and Quartz filters.The MOUDI samples were extracted by Milli-Q water for water-soluble ions analysis.The results showed that the highest concentration of all measured ions at the urban site was found in spring （60.38μg/m3 ）and the lowest level was found in summer （8.76μg/m3 ）;however,there were no obvious seasonal trends for ions in aerosols from the ocean,ranging from 30.77μg/m3 to 35.13μg/m3 .Both SO4 2- and NH4 ＋showed unimodal distributions and peaked at 0.44-1.0μm in aerosols from the urban site,which were similar to those observed in aerosols from the ocean.NO3 - exhibited bimodal distribution and peaked at 2.5-10.0μm and 0.44-1.0μm at the urban site,whereas one peak （2.5-10.0μm）was observed for NO3 - in aerosols from the ocean.Very high concentrations of Na＋ and Cl- were found in aerosols with diameter larger than 1 6μm,suggesting the influence of sea spray droplets.The concentrations of Na＋ and Cl- found in aerosols from the ocean were higher than in urban aerosols.The dry deposition velocities as a function of particle size were calculated,which showed the minimum deposi-tion velocities at diameter around 0.1μm in all seasons.The dry deposition fluxes for particulate inorganic nitrogen （NH4 ＋ and NO3 -）were calculated based on the dry deposition velocities and size distribution of their concentrations.Although the levels of inorganic nitrogen were higher above offshore surface,much higher deposition fluxes were estimated in the ocean （except for NH4 ＋ in autumn）due to their different size distributions.

关 键 词：水溶性离子 季节变化 粒径分布 干沉降 

分 类 号：X513[环境科学与工程—环境工程]