Study on atmospheric chemical mechanisms related to each hemispherical atmospheric OH trend derived from AGAGE observation

根据AGAGE中CH_3CCl_3的长期地面观测资料推断大气OH浓度时，认为与OH的气相反应是CH_3CCl_3的主要大气汇，而光解和溶解到海水中是CH_3CCl_3的次要汇。本研究考察了CH_3CCl_3的附加汇，即对粘土矿物的非均相分解。用闭式循环反应器考察了CH_3CCl_3与25种标准日矿物的反应，发现对大多数被测黏土矿物（γ ~ 10-9）在313 K下进行了CH_3CCl_3→CH_2=CCl_2+HCl的分解。用冲击流仪测定了NO_2和SO_2在水表面的吸收系数（γ）。含H_2O_2或C_6H_4(OH)_2的水溶液中NO_2的γ值高于纯水，这是由于NO_2与溶质的水相反应增加了NO_2的γ值。在准海水中观察到NO_2和SO_2的γ值没有增加，估计了水相化学反应对OH自由基γ值的影响。研究了水蒸气对化学电离质谱仪测定Br_2的影响。由于试剂与水结合形成水合离子，Br_2离子的质量峰不能与试剂离子的峰归一化。然而，我们已经表明它可以用试剂和水合离子的峰归一化。制备了一种降膜吸收器，用于测量液体表面的吸收系数（γ），并将其应用于测量Br_2在水面的吸收系数。结果表明，水相反应是Br_2吸附到水中的一个限制步骤。

When the atmospheric OH concentration is inferred from long-term ground-based observatory data on atmospheric concentration of CH_3CCl_3 in the AGAGE, a gas-phase reaction with OH is considered a main atmospheric sink of CH_3CCl_3,and photolysis and dissolution into sea water are regarded as minor sinks of CH_3CCl_3. In this study, an additional sink of CH_3CCl_3, that is, heterogeneous decomposition on clay minerals, was examined. The reaction of CH_3CCl_3 on 25 standard day minerals was examined with a closed-circulation reactor and found that the decomposition of CH_3CCl_3 proceeded through CH_3CCl_3→CH_2=CCl_2+HCl at 313 K for most of the clay minerals examined (γ〜10-9).The uptake coefficients (γ) of NO_2 and SO_2 to the aqueous surface were measured using the impinging flow apparatus. The aqueous solution including H_2O_2 or C_6H_4(OH)_2 gave larger γ values of NO_2 than pure water, because aqueous phase reaction of NO_2 with the solutes increased the γ value. We cannot observe any increase in the γ values of NO_2 or SO_2 when quasi-seawater was examined, influence of aqueous phase chemical reaction on the γ value of OH radicals was estimated.The influence of water vapor on determination of Br_2 with a chemical ionization mass spectrometer was studied. Since a reagent associated with water to form hydrated ions, the mass peak of Br_2 ion could not be normalized with the peak of the reagent ion. However, we have indicated that it can be normalized with the peaks of both the reagent and the hydrated ions. A falling film absorber was prepared to measure the uptake coefficients (γ) to liquid surfaces and it was applied to measurement of γ of Br_2 to the water surface. Comparison of the measurement with the simulated calculation revealed that the aqueous phase reaction was a limiting-step in the uptake of Br_2 to water.