Sulphur dioxide precipitation scavenging
1983; Elsevier BV; Volume: 17; Issue: 4 Linguagem: Inglês
10.1016/0004-6981(83)90429-8
ISSN1878-2442
Autores Tópico(s)Air Quality and Health Impacts
ResumoAbstract Sulphur dioxide washout ratios (rainborne/airborne concentrations) calculated from hourly observations in a heavily industrialized area show a reasonable agreement with predicted values (Barrie, 1981, Atmospheric Environment15, 31–41) although they are also lower. Because the equilibrium scavenging assumption may not be valid in a heavily industrialized area, an attempt was made to assess the effect of the atmospheric sulphur dioxide vertical gradient by measuring airborne and rainborne sulphur dioxide at two sites in a steep valley, 100 m vertical distance apart. Although the correlation between the observed washout ratios for the air layer and the predicted ratios was good, the observed ratios were lower (arithmetic mean of the observed washout ratios was about half that of the predicted ratios, although the median values were much closer) and did not appear to be related to vertical atmospheric sulphur dioxide gradients. Because the rainborne and airborne SO2 levels were measured at the entrance and exit of the air layer, it was possible to calculate scavenging coefficients. Sulphur dioxide washout was also studied throughout precipitation events in a rural area with sampling durations from one minute to several hours. Generalization of the fine structure of sulphur dioxide during events is difficult, but the observed washout ratios are still less than those predicted by the adopted model.
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