H. Saathoff et al., The loss of NO2, HNO3, NO3/N2O5, and HO2/HOONO2 on soot aerosol: A chamberand modeling study, GEOPHYS R L, 28(10), 2001, pp. 1957-1960
The heterogeneous loss of NO2, HNO3, NO3 / N2O5, and HO2 / HO2NO2 on soot a
erosol was investigated in a large aerosol chamber for interaction times of
up to several days. By fitting a detailed model to the measured time profi
les of the trace gas concentrations in the presence / absence of soot aeros
ol, the following reaction probabilities have been deduced at 294 K and <10
ppm H2O tin parentheses: at 50% r.h.): <gamma>(NO2) less than or equal to
4x10(-8); gamma (HNO3--> NO2)less than or equal to 3x10(-7); gamma (NO3)les
s than or equal to 3x 10(-4) (less than or equal to 10(-3)); gamma (N2O5, h
ydrolysis) = (4 +/-2)x10(-6); ((2 +/-1)x10(-4)); gamma (N2O5, reduction) =
(4 +/-2)x10(-6); gamma (HO2) less than or equal to 10(-2); gamma (HO2NO2) l
ess than or equal to 10(-5). These results were adopted in a series of box
model calculations for four-day summer smog episodes, probing a wide range
of NO emission rates. The 2(nd) day ozone maxima were reduced up to 10 % in
the presence of 20 mug m(-3) soot aerosol, mainly due to the heterogeneous
loss of HO2.