Do organic surface films on sea salt aerosols influence atmospheric chemistry? - a model study
Do organic surface films on sea salt aerosols influence atmospheric chemistry? - a model study
复制标题
海盐气溶胶上的有机表面膜会影响大气化学吗？
DOI：
--
复制
发表时间：
2006
期刊：
影响因子：
--
通讯作者：
R. Glasow
中科院分区：
文献类型：
--
作者：
L. Smoydzin;R. Glasow
来自海洋表面的有机物质可以被纳入海盐气溶胶颗粒，通常在气溶胶上产生表面膜。这种有机涂层可以减少影响海洋大气中海盐化学的气相和气溶胶相之间的传质。为了研究这些影响及其对海洋边界层（MBL）的重要性，我们使用了一维数值模型MISTRA。我们考虑了吸收减少的幅度、海盐气溶胶中有机化合物的浓度和有机物的氧化速率的不确定性，以分析有机表面活性剂对气相和液相化学的可能影响，特别关注卤素化学。通过假设基于实验室测量的有机涂层的破坏率，我们得到了在MBL的前几米内有机单层的快速破坏。较大的有机初始浓度导致涂层寿命较长，但也导致o3浓度的不现实的强烈下降，因为有机膜被o3反应破坏。假设o3的反应吸收系数较小，或者假设部分有机表面活性剂与OH发生反应，膜的寿命就会增加。关于对流层化学，我们发现由于气相和气溶胶相之间的传质减少，氯和溴的气相浓度下降。水相氯浓度也降低，而溴浓度升高。气相浓度的差异一般小于液相浓度的差异。对气相NO 2或NO的影响非常小（减少不到5%），而液相NO 2浓度在某些情况下增加了近100%。我们列出了改进模型研究所需的进一步实验室研究的建议。
Organic material from the ocean's surface can be incorporated into sea salt aerosol particles often producing a surface film on the aerosol. Such an organic coating can reduce the mass transfer between the gas phase and the aerosol phase influencing sea salt chemistry in the marine atmosphere. To investigate these effects and their importance for the marine boundary layer (MBL) we used the one-dimensional numerical model MISTRA. We considered the uncertainties regarding the magnitude of uptake reduction, the concentrations of organic compounds in sea salt aerosols and the oxidation rate of the organics to analyse the possible influence of organic surfactants on gas and liquid phase chemistry with a special focus on halogen chemistry. By assuming destruction rates for the organic coating based on laboratory measurements we get a rapid destruction of the organic monolayer within the first meters of the MBL. Larger organic initial concentrations lead to a longer lifetime of the coating but lead also to an unrealistically strong decrease of O 3 concentrations as the organic film is destroyed by reaction with O 3 . The lifetime of the film is increased by assuming smaller reactive uptake coefficients for O 3 or by assuming that a part of the organic surfactants react with OH. With regard to tropospheric chemistry we found that gas phase concentrations for chlorine and bromine species decreased due to the decreased mass transfer between gas phase and aerosol phase. Aqueous phase chlorine concentrations also decreased but aqueous phase bromine concentrations increased. Differences for gas phase concentrations are in general smaller than for liquid phase concentrations. The effect on gas phase NO 2 or NO is very small (reduction less than 5%) whereas liquid phase NO 2 concentrations increased in some cases by nearly 100%. We list suggestions for further laboratory studies which are needed for improved model studies.