Iron(III)-induced activation of chloride from artificial sea-salt aerosol
Iron(III)-induced activation of chloride from artificial sea-salt aerosol
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DOI：
10.1071/en14279
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发表时间：
2015-07
影响因子：
4.3
通讯作者：
J. Wittmer;S. Bleicher;J. Ofner;C. Zetzsch
中科院分区：
文献类型：
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作者：
J. Wittmer;S. Bleicher;J. Ofner;C. Zetzsch
无机、天然气溶胶（海盐、矿物粉尘、冰川粉）和人为成分（飞灰、钢铁生产和加工产生的粉尘等）的贡献含有铁，可以溶解为FeIII在盐水介质中。本研究探讨在云和气溶胶产生的气相氯盐和气相组成的函数，采用模拟室的光化学过程。原子氯可能有助于对流层的氧化能力，我们的研究结果意味着当地的来源。摘要在聚四氟乙烯模拟箱中，研究了不同组成的Fe Ⅲ人工海盐气溶胶中pH值和对流层微量气体NO2、O3和SO2对氯离子光化学活化的影响。原子氯（Cl）在气相中检测和定量的自由基时钟技术。雾化具有已知Fe III含量的稀盐水，直到相对湿度达到70- 90%。用模拟阳光照射所得液滴（最丰富的粒径：0.35-0.46µm，初始表面积：高达3×10- 2cm 2cm-3），并评估碳氢化合物测试混合物中Cl、Br和OH的消耗。在Cl-/FeIII=13时，气溶胶表面产生的Cl原子的初始速率随FeIII的增加而增加，约为1.9×1018 atoms cm-2s-1。NO2（~20 ppb）的存在使其增加至~7×1018 atoms cm-2s-1，O3（630 ppb）的存在使其增加至~9×1018 atoms cm-2s-1，SO2（20和200 ppb）的存在使释放轻微抑制至~1.7和~1.1×1018 atoms cm-2s-1。所观察到的生产原子氯进行了讨论相对于pH值和形态的光不稳定的水FeIII络合物。
Environmental context Inorganic, natural aerosols (sea-salt, mineral dust, glacial flour) and contributions of anthropogenic components (fly ash, dust from steel production and processing, etc.) contain iron that can be dissolved as FeIII in saline media. This study investigates photochemical processes in clouds and aerosols producing gas-phase Cl as a function of salt- and gas-phase composition employing a simulation chamber. Atomic Cl may contribute to the oxidative capacity of the troposphere, and our findings imply local sources. Abstract Artificial sea-salt aerosol, containing FeIII at various compositions, was investigated in a simulation chamber (made of Teflon) for the influence of pH and of the tropospheric trace gases NO2, O3 and SO2 on the photochemical activation of chloride. Atomic chlorine (Cl) was detected in the gas phase and quantified by the radical clock technique. Dilute brines with known FeIII content were nebulised until the relative humidity reached 70–90%. The resulting droplets (most abundant particle diameter: 0.35–0.46µm, initial surface area: up to 3×10–2cm2cm–3) were irradiated with simulated sunlight, and the consumption of a test mixture of hydrocarbons was evaluated for Cl, Br and OH. The initial rate of atomic Cl production per aerosol surface increased with FeIII and was ~1.9×1018 atoms cm–2s–1atCl–/FeIII=13. The presence of NO2 (~20 ppb) increased it to ~7×1018 atoms cm–2s–1, the presence of O3 (630 ppb) to ~9×1018 atoms cm–2s–1 and the presence of SO2 at 20 and 200 ppb inhibited the release slightly to ~1.7 and ~1.1×1018 atoms cm–2s–1. The observed production of atomic Cl is discussed with respect to pH and speciation of the photolabile aqueous FeIII complexes.