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>Heterogeneous uptake of gaseous hydrogen peroxide by Gobi and Saharan dust aerosols: a potential missing sink for Hsub2/subOsub2/sub in the troposphere
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Heterogeneous uptake of gaseous hydrogen peroxide by Gobi and Saharan dust aerosols: a potential missing sink for Hsub2/subOsub2/sub in the troposphere
The first direct laboratory measurements of gaseous hydrogen peroxide uptakeby authentic Gobi and Saharan dust aerosol particles as a function ofrelative humidity (RH) have been carried out in an entrained aerosol flowtube coupled to a chemical ionization mass spectrometer. Gobi dust showsuptake coefficients, γH2 O2 = (3.33±0.26) ×10−4at 15% RH rising to γH2 O2 = (6.03±0.42)×10−4 at 70% RH; the corresponding values for Saharan dustare systematically higher (γH2 O2 = (6.20±0.22)×10−4 at 15% RH rising to γH2 O2 = (9.42±0.41)×10−4 at 70% RH). High resolution X-ray photoelectronspectroscopy (XPS) measurements of the surface chemical composition of thetwo mineral dust samples together with published water adsorption isothermsof their principal constituents enables rationalization of theseobservations, which are relevant to nighttime tropospheric chemistry. A boxmodel study performed by incorporating the experimentally determined dataset reveals that uptake of H2O2 onto dust can be an important lossprocess for this species which has been, until now, poorly constrained.
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机译：真实的戈壁和撒哈拉粉尘气溶胶颗粒吸收的气态过氧化氢作为相对湿度（RH）的函数的首次直接实验室测量是在与化学电离质谱仪耦合的气溶胶流管中进行的。戈壁尘埃的吸收系数γ H 2 O 2 =（3.33±0.26）×10 −4 相对湿度（RH）在70％时升至γ H 2 O 2 =（6.03±0.42）×10 −4 相对湿度撒哈拉尘埃的对应值有系统地更高（γ H 2 O 2 =（6.20±0.22）×10 −4 H 2 O 2 =（9.42±0.41）×10 -4 在70％相对湿度下）。对两个矿物粉尘样品的表面化学组成进行高分辨率X射线光电子能谱（XPS）测量，并公布其主要成分的吸水等温线，可以合理化这些观测值，这与夜间对流层化学有关。通过结合实验确定的数据集进行的盒模型研究表明，H 2 O 2 吸收到粉尘上可能是该物种重要的损失过程，迄今为止，该物种一直很差受约束的。
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