Modal structure of chemical mass size distribution in the high Arctic aerosol
Modal structure of chemical mass size distribution in the high Arctic aerosol
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北极高气溶胶中化学质量尺寸分布的模态结构
DOI：
10.1029/2001jd001119
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发表时间：
2001
影响因子：
--
通讯作者：
Caroline Leek
中科院分区：
文献类型：
--
作者：
R. Hillamo;V. Kerminen;M. Aurela;T. Mäkelä;W. Maenhaut;Caroline Leek
作为1996年北冰洋考察大气研究计划(AOE-96)的一部分，在北冰洋中部的偏远海洋边界层中测量了气溶胶粒子的化学质量尺寸分布。使用惯性撞击方法将气溶胶颗粒分为不同的大小类别，以供后续的化学分析。用离子色谱法和粒子诱导X射线发射技术测定了粒子的化学成分。用数据反演法从原始数据中提取了连续的粒度谱。发现了由初级海盐颗粒或与二甲基硫化物排放有关的次级颗粒组成的气溶胶的明确和不同的模式结构。随着离外海距离的增加，各模式的浓度水平迅速下降。在亚微米尺寸范围内，离子色谱发现的主要离子是硫酸盐、甲烷磺酸盐和铵。它们大部分时间具有明显的艾特肯模式和一种或两种积聚模式，其气动质量中值直径分别约为0.1μm、0.3μm和0.5~1.0μm。这三种离子的总体亚微米尺寸分布非常相似，这表明它们在这个尺寸范围的大部分时间内是内部混合的。相应的振型结构与由差动迁移率粒子仪测量的颗粒数尺寸分布得到的质量尺寸分布是一致的。在晴天，NSS-硫酸盐和MSA的Aitken与累积模的质量比明显高于阴天。原始海盐颗粒形成了一种气动质量中值直径在2μm左右的模式。总的来说，所得到的连续质量尺寸分布呈现出一种清晰的模式结构，这与我们对两个已知的主要源机制的理解一致。一种是海水中因气泡破裂而形成的海盐气溶胶。另一个与海水中生物过程排放的二甲基硫化物(DMS)有关，随后是气粒转化、颗粒硫酸盐和甲烷磺酸盐(MSA)的形成以及氨的中和。
Chemical mass size distributions of aerosol particles were measured in the remote marine boundary layer over the central Arctic Ocean as part of the Atmospheric Research Program on the Arctic Ocean Expedition 1996 (AOE-96). An inertial impaction method was used to classify aerosol particles into different size classes for subsequent chemical analysis. The particle chemical composition was determined by ion chromatography and by the particle-induced X-ray emission technique. Continuous particle size spectra were extracted from the raw data using a data inversion method. Clear and varying modal structures for aerosols consisting of primary sea-salt particles or of secondary particles related to dimethyl sulfide emissions were found. Concentration levels of all modes decreased rapidly when the distance from open sea increased. In the submicrometer size range the major ions found by ion chromatography were sulfate, methane sulfonate, and ammonium. They had most of the time a clear Aitken mode and one or two accumulation modes, with aerodynamic mass median diameters around 0.1 μm, 0.3 μm, and between 0.5-1.0 μm, respectively. The overall submicron size distributions of these three ions were quite similar, suggesting that they were internally mixed over most of this size range. The corresponding modal structure was consistent with the mass size distributions derived from the particle number size distributions measured with a differential mobility particle sizer. The Aitken to accumulation mode mass ratio for nss-sulfate and MSA was substantially higher during clear skies than during cloudy periods. Primary sea-salt particles formed a mode with an aerodynamic mass median diameter around 2 μm. In general, the resulting continuous mass size distributions displayed a clear modal structure consistent with our understanding of the two known major source mechanisms. One is the sea-salt aerosol emerging from seawater by bubble bursting. The other is related to dimethylsulfide (DMS) emissions from biogenic processes in seawater, followed by gas-to-particle conversion, formation of particulate sulfate and methane sulfonate (MSA) and neutralization by ammonia.