Analysis of ammonia variation in the urban atmosphere

Long-term monitoring of ammonia concentration and other trace gases was made at hourly intervals along with meteorological parameters in Seoul, Korea for a one-year period (1 September 2010–23 August 2011). The mean ammonia concentrations measured at two sites (Gwang-Jin (GJ) and Gang-Seo (GS) districts) were 10.9 ± 4.25 and 12.3 ± 4.23 ppb, respectively. A comparison of the seasonal data shows its relative dominance at both GJ and GS sites during the warm period (summer and spring) over the cool period (winter and fall). Likewise, over the diurnal scale, relative dominance during daytime was also apparent (p < 0.05). A comparison between different studies suggests that the long-term trend of ammonia levels should be tightly affected by an increasing number of vehicles. As such, the results of our statistical analysis also point to the potentially significant role of traffic activities in the elevation of ammonia levels in urban areas.

► The on-line analysis of ammonia is conducted at two urban monitoring sites.
► Sources affecting its temporal variation are evaluated in a number of respects.
► Ammonia levels in the urban air exhibit unique temporal trends over seasonal cycle.
► The results indicate a potential linkage between ammonia levels and traffic activities.