Diurnal variation of organic aerosols in a severely polluted atmosphere
Journal
Journal of Environmental Science and Health. Part A: Environmental Science and Engineering and Toxicology
Journal Volume
28
Journal Issue
7
Pages
1565-1579
Date Issued
1993
Author(s)
Abstract
In this study, the complete diurnal variation of organic aerosols for 24 hours in urban atmosphere was investigated, which has not yet been done before. In addition, the formation of secondary organic aerosols was also studied. Samples for both fine and coarse particulates were taken every four hours from the 24-hour continuous sampling by dichomous sampler. There is a total of five successful sampling days including three sunny days, one cloudy day, and one sunny day after rain. The average total carbon concentration is 69.1, 56.7 and 23.2 μg/M3for sunny, cloudy, and sunny days after rain respectively. The organic aerosols comprise of about 19% to 45% of PM l0μ. In addition, higher concentration of organic aerosols are distributed in fine particulates. For instance, 59% to 70% of total carbon (TC) and 55% - 74% of organic carbon (OC) are present in fine particulates. Two peaks were found in the diurnal variations of organic aerosols, which is primarily consistent with the traffic flow pattern. The diurnal variations of TC/EC ratio which is usually applied for the study of the formation of secondary organic aerosols were further investigated. EC stands for elemental carbon. The highest TC/EC ratio was found on the sunny day after rain. The accumulated suspended particulates have been washed out. The effect of the secondary organic aerosols on the organic aerosols is evident in sunny day after rain because the suspended particulates are more likely to be daily produced for local sources. In addition, the highest OC/TC in fine particulates was also observed. Thus, the formation of secondary organic aerosols was further studied based on the diurnal variation of TC/EC ratio on the sunny day after rain. The highest TC/EC occurred during the time period of 2 – 6 P.M. but the lowest TC/EC was present during 2 – 6 in the morning. It was indicated that the contribution of secondary organic aerosols can be as high as 73% increase in total organic aerosols in this severely polluted city. © 1993, Taylor & Francis Group, LLC. All right reserved.
Subjects
diurnal variation; fine particulates; organic aerosols; secondary organic aerosols
SDGs
Other Subjects
organic compound; aerosol; air pollution; air sampling; article; circadian rhythm; suspended particulate matter; total organic carbon; urban area
Type
journal article