Origins and Distributions of Atmospheric Ammonia in Jeonju during 2019~2020

Abstract Atmospheric ammonia (NH₃) plays an important role in secondary particle formation and air quality. Herein, we conducted real-time measurements of NH₃ at Samcheon-dong in Jeonju from May 2019 to January 2020. During the measurement periods, the average concentration of atmospheric NH₃ was 10.5±5.1 ppb. NH₃ monthly variations were dependent on its source and meteorological conditions. The highest monthly average value of NH₃ was 17.1±5.4 ppb in June, which was approximately 2 times higher than in wintertime, with peak concentrations from late afternoon to midnight. The increased NH₃ level was influenced by agricultural activities and regional transport, coincided with the prevailing meteorological conditions of extended planetary boundary layer. However, the concentration of NH₃ was decreased remarkably after the rainy season and the concentration was maintained over the wintertime. When the NH₃ level dropped down to below 10 ppb, significantly different diurnal variation was monitored with two peaks in the morning and late afternoon. The diurnal cycle of the NH₃ level in the period was dependent on the traffic emissions nearby.