HENRYS LAW CONSTANTS AND REMOVAL PROCESSES FOR SEVERAL ATMOSPHERIC BETA-HYDROXY ALKYL NITRATES

The oxidation of atmospheric alkenes by OH radicals results in small y ields of P-hydroxy alkyl nitrates that can then provide a vehicle for the ultimate removal of MO, from the atmosphere. Although rainout may be an efficient mechanism for the removal of these species from the at mosphere, the Henry's law constants for these species are largely unkn own. in this work, the Henry's law constants for P-hydroxy alkyl nitra tes that are produced from the atmospheric oxidation of small alkenes in the presence of NO have been determined, over the temperature range 279-304 K. The compounds investigated were 2-nitrooxyethanol, 1-nitro oxy-2-propanol, 2-nitrooxy-1-propanol, 2-nitrooxy-3-butanol, 1-nitroox y-2-butanol, and 2-nitrooxy-1-butanol. At 298 K, the measured Henry's law constants were 38800, 10900, 4500, 10100, 5800, and 6000 M/atm, re spectively. From estimates of the rates of removal of these species fr om the lower troposphere by wet and dry deposition, OH radical reactio n, and photolysis, we find that wet deposition accounts for between 26 and 60% of the removal rate, on average. Calculated atmospheric lifet imes for these species are all on the order of 2-3 days, which is long enough for long-range transport of these species to be possible. For hydroxy nitrates that retain a C=C functionality, such as the isoprene nitrates, reaction with OH is expected to be more important than wet deposition.