Behavior of benzene and 1,3-butadiene concentrations in the urban atmosphere of Tokyo,Japan |
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Authors: | Wanna Laowagul Kunio Yoshizumi |
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Institution: | 1. Department of Anatomy, National University of Singapore, Singapore 119260;2. Division of Neurology, National Neuroscience Institute, Singapore General Hospital Campus, Singapore 169608;3. Department of Neurosurgery, Cedars-Sinai Medical Center, Advanced Health Sciences Pavilion, Los Angeles, CA 90048, USA;4. Neurobiology and Ageing Research Programme, National University of Singapore, Singapore 119260 |
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Abstract: | Benzene and 1,3-butadiene concentration profiles in the urban ambient air were generated to investigate their levels at two specified sampling locations, roadside and residential, in Tokyo, Japan. Air monitoring data for benzene and 1,3-butadiene were obtained from the Air Quality Monitoring Information of the Tokyo Metropolitan Government. Air samples were continuously obtained and analyzed every hour for volatile organic compounds (VOCs) using an automated GC–MS system. The diurnal variations in benzene and 1,3-butadiene concentrations showed bi-modal patterns, which were considered to be related to the increasing and decreasing trends of vehicle emissions and vertical mixing depths in a day. The frequencies of occurrence of various benzene and 1,3-butadiene concentrations were examined. The results of each concentration showed log-normal forms with almost straight lines. The frequency distributions of both pollutants were confirmed to have a log-normal, rather than a simple normal, form. The relationship between benzene and 1,3-butadiene concentrations at both the roadside and residential site were examined. Separate observations of day and night trends revealed that photochemical decomposition showed a greater influence on the data in the residential site than that in the roadside site. These results were considered as direct evidences of photochemical decomposition of 1,3-butadiene in the atmosphere. |
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