Abstract
The vertical distribution was reported on the concentrations of ambient hydrocar bons [17 volatile hydrocarbon components (VHC), methane, non-methane (NMHC)] and carbon monoxide (CO) measured aloft over Kansai area and at one site near the ground level in Osaka City during the springtime (April 20 and 21) in 1993. The average concentrations of these air pollutants decreased following with the elevated level of sampling sites (ground level, 300 m, 600 m and 2, 000 m). The average percentages of total 17 VHC in NMHC decreased gradually too. Some differences were observed among the average decreasing ratios of vertical 17 VHC concentrations. The concentrations of propylene above 300 m were below the detection limit. The average decreasing ratios of ethylene (C2H4) concentrations were larger than those of acetylene (C2H2). Above 300 m, atmospheric CO decreased at the more decreasing ratios than acetylene did. Both average ratios of [C2H4]/[C2H2] (E/A) and [CO]/[C2H2] (CO/A) smoothly decreased above 300 m. From the ground level of one site to 300 m vertically, however, the average ratios of CO/A increased very much and those of E/A gave little change. From these results, it is suggested that the strong influences of the neighboring main emission sources took on the average concentrations of these air pollutants at one site near the ground level, which became to be relatively weak in the case of average concentrations measured aloft over 300 m in a broad area to make the vertical decreases of E/A and CO/A values due to the differences of atmospheric reactions obvious.
