Antarctic Ozone Depletion Chemistry: Reactions of N2O5 with H2O and HCl on Ice Surfaces

The reactions of dinitrogen pentoxide (N2O5) with H2O and hydrochloric acid (HCl) were studied on ice surfaces in a Knudsen cell flow reactor. The N2O5 reacted on ice at 185 K to form condensed-phase nitric acid (HNO3). This reaction may provide a sink for odd nitrogen (NOx) during the polar winter, a requirement in nearly all models of Antarctic ozone depletion. A lower limit to the sticking coefficient, γ, for N2O5 on ice is 1 x 10-3. Moreover, N2O5 reacted on HCl-ice surfaces at 185 K, with γ greater than 3 x 10-3. This reaction, which produced gaseous nitryl chloride (ClNO2) and condensed-phase HNO3, proceeded until all of the HCl within the ice was depleted. The ClNO2, which did not react or condense on ice at 185 K, can be readily photolyzed in the Antarctic spring to form atomic chlorine for catalytic ozone destruction cycles. The other photolysis product, gaseous nitrogen dioxide (NO2), may be important in the partitioning of NOx between gaseous and condensed phases in the Antarctic winter.

[1]  S. Wofsy,et al.  Interactions between HCl, NO x and H2O ice in the Antarctic stratosphere: Implications for ozone , 1988 .

[2]  D. Golden,et al.  Reaction of Chlorine Nitrate with Hydrogen Chloride and Water at Antarctic Stratospheric Temperatures , 1987, Science.

[3]  M. Molina,et al.  Antarctic Stratospheric Chemistry of Chlorine Nitrate, Hydrogen Chloride, and Ice: Release of Active Chlorine , 1987, Science.

[4]  C. Cantrell,et al.  Reactions of nitrate radical and nitrogen oxide (N2O5) with molecular species of possible atmospheric interest , 1987 .

[5]  R. Cicerone.  Changes in Stratospheric Ozone , 1987, Science.

[6]  P. Crutzen,et al.  Nitric acid cloud formation in the cold Antarctic stratosphere: a major cause for the springtime ‘ozone hole’ , 1986, Nature.

[7]  M. Ko,et al.  Chlorine chemistry in the Antarctic stratosphere: Impact of OClO and Cl2 O2 and implications for observations , 1986 .

[8]  M. McCormick,et al.  SAM II measurements of Antarctic PSC's and aerosols. [Stratospheric Aerosol Measurement satellite - Polar Stratospheric Clouds] , 1986 .

[9]  S. Sander,et al.  A kinetics study of the homogeneous and heterogeneous components of the HCl + ClONO2 reaction. [and its relevance to stratospheric chemistry] , 1986 .

[10]  R. Turco,et al.  Condensation of HNO3 and HCl in the winter polar stratospheres , 1986 .

[11]  R. Turco,et al.  Characteristics of polar stratospheric clouds during the formation of the Antarctic ozone hole , 1986 .

[12]  S. Wofsy,et al.  Antarctic O3: Chemical mechanisms for the spring decrease , 1986 .

[13]  S. Wofsy,et al.  Reductions of Antarctic ozone due to synergistic interactions of chlorine and bromine , 1986, Nature.

[14]  C. T. McElroy,et al.  The conversion of N2O5 to HNO3 at high latitudes in winter , 1985 .

[15]  J. Farman,et al.  Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction , 1985, Nature.

[16]  A. Winer,et al.  The reaction of gas phase N2O5 with water vapor , 1983 .

[17]  H. Nelson,et al.  Kinetics of the reaction of chlorine atoms with nitrosyl chloride and nitryl chloride and the photochemistry of nitryl chloride , 1981 .

[18]  David M. Golden,et al.  Very Low-Pressure Pyrolysis (VLPP); A Versatile Kinetic Tool , 1973 .

[19]  E. W. Pearson,et al.  Laboratory Studies of Sticking Coefficients and Heterogeneous Reactions Important in the Antarctic Stratosphere (Paper 7L6697) , 1988 .

[20]  M. Molina,et al.  Production of Cl2O2 from the self-reaction of the ClO radical , 1987 .

[21]  D. Golden,et al.  Reaction of N2O5 with H2O on carbonaceous surfaces , 1986 .

[22]  S. Solomon,et al.  On the depletion of Antarctic ozone , 1986, Nature.