Evaluation of a catalytic reduction technique for the measurement of total reactive odd-nitrogen NO y in the atmosphere     

D. W. Fahey  C. S. Eubank  G. Hübler  F. C. Fehsenfeld 《Journal of Atmospheric Chemistry》1985,3(4):435-468

A catalytic reduction technique for the measurement of total reactive odd-nitrogen NO _y in the atmosphere was evaluated in laboratory and field tests. NO _y component species include NO, NO₂, NO₃, HNO₃, N₂O₅, CH₃COO₂NO₂(PAN), and particulate nitrate. The technique utilizes the reduction of the higher oxides to NO in reaction with CO on a metal catalyst and the subsequent detection of NO by chemiluminescence produced in reaction with O₃. The efficiency and linearity of the conversion of the principal NO _y species were examined for mixing ratios in the range of 0.1 to 100 parts per billion by volume (ppbv). Results of tests with Au, Ni, and stainless steel as the catalyst in the temperature range of 25–500°C showed Au to be the preferred catalyst. NH₃, HCN, N₂O, CH₄, and various chlorine and sulfur compounds were checked as possible sources of NO _y interference with the Au catalyst. The effects of pressure, O₃, and H₂O on NO _y conversion were also examined. The results of the checks and tests in the laboratory showed the technique to be suitable for initial NO _y measurements in the atmosphere. The technique was subsequently tested in ambient air at a remote ground-based field site located near Niwot Ridge, Colorado. The results of conversion and inlet tests made in the field and a summary of the NO _y data are included in the discussion.  相似文献   

Aqueous Oxidation of Sulfur(IV) Catalyzed by Manganese(II): A Generalized Simple Kinetic Model     

Boštjan Podkrajšek  Gorazd Berčič  Janja Turšič  Irena Grgić 《Journal of Atmospheric Chemistry》2004,47(3):287-303

The reaction kinetics of S(IV) autoxidation catalyzed by Mn(II) in the pH range 3–5 typical for atmospheric liquid water, was investigated. For reactions with pH maintained constant during the reaction course, the predictions obtained by a simple integral approach cover kinetic results only for concentrations of HSO ₃ ⁻ up to 0.2 mM at pH 4.5. Thus, a generalized simple kinetic model, which can be used for predicting the reaction kinetics in wider concentration, pH and temperature ranges, was derived. This model is based on the assumption that the reaction rate is proportional to the concentration of a transient manganese-sulfito complex formed in the initial step of a radical chain mechanism. In the proposed power law rate equation the concentration of complex is calculated from the stability constant K and concentrations of reactants at a specific reaction time. This rate equation adequately predicts the reaction kinetics in the pH range 3–5, in the concentration ranges 0.1 ≤ [HSO ₃ ⁻ ] ≤ 0.4 mM and 2 ≤ [Mn(II)] ≤ 14.6 μM. For the temperature range 15–35 °C, the estimated value for activation energy is 92.0 ± 0.1 kJ mol⁻¹ and the Gibbs free energy of formation of the manganese-sulfito complex is −20.4 ± 0.3 kJ mol⁻¹. Furthermore, the kinetics for catalytic reactions with pH maintained constant during the reaction course as well as with initial pH adjusted only at the start of the reaction, is described satisfactorily by the present model.  相似文献   

飞机增雨远程遥控催化作业的实现   总被引：1，自引：0，他引：1  

游积平  冯永基  林俊君  赵博  姜正勇 《气象》2007,33(9):103-106

利用电子计算机以及空地传输等手段,建立飞机增雨远程遥控催化作业平台,通过远程无线通讯技术,实现地面指挥作业指令对空中增雨飞机上的焰条催化设备点火作业的实时控制,同时实现了空中增雨飞机空中信息的对地传输,在国内首次实现飞机增雨的远程遥控无人作业。  相似文献   

细菌对锰的氧化和聚集作用   总被引：6，自引：0，他引：6  

郝瑞霞  彭省临 《海洋地质与第四纪地质》1998,18(2):69-74

细菌是锰矿床生物沉积过程中的主要营力。通过总结生物与锰的关系,重点评述了细菌对锰的氧化和聚集作用,并探讨了锰的微生物氧化机制;同时,分析和总结了锰结核和锰的生物沉积特征。最后得出细菌在锰的地球化学循环中起着重要作用。  相似文献