Cryogenic Sampling and Analysis of Peroxyacetyl Nitrate in the Atmosphere

Henry's law constant and hydrolysis of peroxyacetyl nitrate (PAN)

“…Both, Henry's law coefficients and hydrolysis rate constants of PAN in neutral and slightly acidic water, are too low to significantly affect the atmospheric lifetime of the compound, or contribute to the acidity of cloud and fog water. However, due to the relatively important solubility in cold water, PAN measurements by cryotrapping techniques, which may accumulate significant quantities of liquid water (Glavas and Schurath, 1983;Meyrahn et al, 1984), can be affected. Note that the decreasing solubility of PAN at elevated temperatures is balanced by a concomitant increase of the hydrolysis rate constant, because the enthalpy of solution, AH" = -54.2 kJ mol-', is approximately equal (but with opposite sign) to the activation energy of the hydrolysis rate, E, = 55 kJ mol-I.…”

“…They indicate that PAN does not contribute significantly to the acidification of cloud and fog water, and that its loss from the atmosphere by deposition on sea surfaces is slow. However, in view of the ubiquity of the compound in the troposphere, and in order to better understand persistence or loss of PAN in cryotrapping techniques (Glavas and Schurath, 1983;Meyrahn et al, 1984), in gas chromatography (Roumelis and Glavas, 1989), and in other analytical procedures which involve air-liquid phase interactions, a more thorough investigation of the solubilitv and hydrolysis mechanism of PAN in water seemed indicated. …”

Gas chromatographic determination of peroxyacetyl nitrate: Two convenient calibration techniques

“…Interpolation between the initial and final sections of the decay curve provided the mixing ratios applicable at the time of field calibrations. The method was tested in conjunction with aircraft measurements of PAN directed at determining its vertical distribution over a continental area (Meyrahn et al, 1984). Due to the unavoidable scatter of individual data points, we estimate this method to have a reproducibility of about 30% for the period 100-200 h after preparation of the initial mixture.…”

Large‐scale distribution of peroxyacetylnitrate results from the STRATOZ III flights

“…In contrast to the large number of PAN measurements in urban, polluted areas (see, for example, Temple and Taylor [1983]) there are few series of measurements over rural and semirural areas [Spicer et al, 1983;Meyrahn et al, 1984;Brice et al, 1984;Penkett et al, 1975•, and extremely limited data are available for the remote troposphere or from above ground level [Sinqh andSalas, 1983, Sinqh et al, 1986]. There are also some studies of PAN and NO•, together with several other atmospheric trace gases [Bottenheim et al, 1986;Fahey et al, 1986;Sinqh et al, 1985].…”