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Wet-removal study of air pollutants using a one-dimensional transport/transformation/removal model

Thesis/Dissertation ·
OSTI ID:6154577
A one-dimensional scavenging model has been developed and compared to field data of sequential sampling of ground level precipitation rates and chemical compositions of precipitation. Field results from convective showers and frontal precipitations obtained by Dawson (1978) and Asman (1987) which clearly indicate the variation of pollutant rain concentrations during a rain event, are compared with model output. The sequences for modeling these rain events are that the precipitation rates are matched followed by modeling the pollutant rain concentrations. Nucleation scavenging by cloud water in the in-cloud region dominates the removal of submicrometer particles; inertial impaction by raindrops in the below-cloud region dominates the removal of coarse particles. The major scavenging mechanisms of NH/sub 4/ and NO/sub 3/ are gas absorption. The contribution of (NH/sup 4/)/sub 2/SO/sub 4/ scavenging to the NH/sub 4/ rain concentration is also important, whereas the NH/sub 4/ rain concentration is not sensitive to the type of concentration profile of NH/sub 3/ in the below-cloud region. The absorption of SO/sub 2/ by aqueous drops and oxidation of S(IV) by O/sub 3/ and H/sub 2/O/sub 2/ in the aqueous phase is the major formation and scavenging mechanism for SO4.
Research Organization:
Rensselaer Polytechnic Inst., Troy, NY (USA)
OSTI ID:
6154577
Country of Publication:
United States
Language:
English