Gas-aerosol relationships of H2SO4, MSA, and OH:: Observations in the coastal marine boundary layer at Mace Head, Ireland -: art. no. 8100
Gas-aerosol relationships of H2SO4, MSA, and OH:: Observations in the coastal marine boundary layer at Mace Head, Ireland -: art. no. 8100
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DOI：
10.1029/2000jd000229
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发表时间：
2002-09-01
影响因子：
4.4
通讯作者：
O'Dowd, CD
中科院分区：
文献类型：
--
作者：
Berresheim, H;Elste, T;O'Dowd, CD
[1] 1999 年 6 月在爱尔兰梅斯海德举行的第二届沿海环境新粒子形成和命运 (PARFORCE) 活动期间，通过化学电离质谱 (CIMS) 测量了大气中气态硫酸 (H2SO4)、甲磺酸 (MSA) 和羟基自由基 (OH) 的浓度。海洋背景空气中的总体中值浓度分别为1.5、1.2和0.12 x 10(6) cm(-3)。 H2SO4 也在夜间存在，表明非光化学来源的贡献很大。清洁海洋空气中的白天 OH 和 H2SO4 水平之间存在很强的相关性，表明硫前体气体在本地快速产生 H2SO4。如果假定 H2SO4 粘附系数非常低 (0.02-0.03) 或除 SO2 + OH 反应之外的来源，则环境 H2SO4 水平的稳态平衡计算与测量浓度一致。总体而言，环境 H2SO4 水平的变化与潮汐周期或超细颗粒 (UFP) 浓度没有相关性。然而，在特定的日子里，偶尔会观察到 H2SO4 和 UFP 水平之间的反相关性，这为 H2SO4 对新颗粒形成和/或颗粒生长的贡献提供了证据。气态 MSA 浓度与露点温度呈负相关，反映了该化合物高度敏感的气体-颗粒分配平衡。目前的观察严重质疑一般使用 MSA 作为保守示踪剂来推断二甲硫醚 (DMS) 氧化产生 H2SO4 的相对产量。在地面海洋空气中，MSA/H2SO4 浓度比通常在 0.06 到 1.0 之间。测量的 diel OH 曲线显示与臭氧光解频率的同时变化存在显着偏差。与使用简单的光化学盒模型计算的 OH 浓度相比，它们的值低了 1 个数量级。这些差异在阳光明媚的中午和低潮时发生的粒子成核事件中最为明显。目前的结果表明，沿海边界层的氧化能力和颗粒形成潜力均受到此类环境中普遍存在的未知化合物反应的显着影响。
[1] Atmospheric concentrations of gaseous sulfuric acid (H2SO4), methane sulfonic acid (MSA), and hydroxyl radicals (OH) were measured by chemical ionization mass spectrometry (CIMS) during the second New Particle Formation and Fate in the Coastal Environment (PARFORCE) campaign in June 1999 at Mace Head, Ireland. Overall median concentrations in marine background air were 1.5, 1.2, and 0.12 x 10(6) cm(-3), respectively. H2SO4 was also present at night indicating significant contributions from nonphotochemical sources. A strong correlation was found between daytime OH and H2SO4 levels in clean marine air suggesting a fast local production of H2SO4 from sulfur precursor gases. Steady state balance calculations of ambient H2SO4 levels agreed with measured concentrations if either very low H2SO4 sticking coefficients (0.02-0.03) or sources in addition to the SO2 + OH reaction were assumed. Overall, variations in ambient H2SO4 levels showed no correlation with either the tidal cycle or ultrafine particle (UFP) concentrations. However, on particular days an anticorrelation between H2SO4 and UFP levels was occasionally observed providing evidence for the contribution of H2SO4 to new particle formation and/or particle growth. Gaseous MSA concentrations were inversely correlated with dew point temperature reflecting a highly sensitive gas-particle partitioning equilibrium of this compound. The present observations seriously question the general use of MSA as a conservative tracer to infer the relative production yield of H2SO4 from dimethylsulfide (DMS) oxidation. MSA/H2SO4 concentration ratios typically ranged between 0.06 and 1.0 in marine air at ground level. Measured diel OH profiles showed a significant deviation from concurrent variations of the ozone photolysis frequency. They also showed up to 1 order of magnitude lower values compared to OH concentrations calculated with a simple photochemical box model. These differences were most pronounced during particle nucleation events occurring on sunny days around noon and at low tide. The present results suggest that both the oxidation capacity and the particle formation potential in the coastal boundary layer were significantly affected by reactions of unknown compounds prevailing in this type of environment.