Atmospheric ammonia is a significant pollutant throughout the year, necessitating standardized measurement and identification of emission factors. We performed a quantized evaluation of ammonia concentrations at various locations in and around Seoul, South Korea. The established testing methods of the Radiello Passive Sampler were used for ammonia sampling, and the method was validated using annular denuder sampling. Urban and suburban areas were studied to gain a deeper understanding of the factors responsible for ammonia pollution. This study aimed to establish the fluctuations in concentration over one year, by analyzing the seasonal and regional variation in ammonia concentration. Livestock and agricultural areas recorded the highest concentration of ammonia among all sites, with the highest concentration recorded in autumn. However, at most of the other studied sites, the highest and lowest ammonia concentrations were recorded during summer and winter, respectively. This study attempted to establish a correlation between ammonia concentration and temperature, as well as ammonia concentration and altitude.

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This study aimed to identify the factors causing NH3 emissions in the South Korean Peninsula and West Sea region. To analyze the trends of NH3 and other air pollutants, such as NOx, CO, and NR-PM1, we collected samples from six supersites across the peninsula, a roadside in Seoul, and the West Sea over different sampling periods, ranging from 1 month to 1 year. The highest NH3 concentrations were found at rural areas, ascribed to agricultural activities, particularly NH4NO3 decomposition at high summer temperatures. Areas with low population densities recorded the lowest NH3 concentrations, attributed to the lack of anthropogenic activities. A roadside field experiment confirmed the close link between ambient NH3 and vehicle emissions in urban regions by showing a strong correlation between CO and NOx concentrations and that of NH3. Moreover, we examined oceanic emissions near the eastern coast of South Korea in the West Sea. Long-range transportation studies confirmed that most of the pollutants (NH3, CO, and PM1) were transported by wind from the northeastern region of China. A maritime origin study showed that oceanic emissions and NH4NO3 decomposition in the atmosphere owing to high temperatures were the causing NH3 pollution. These findings provided valuable insights into the emission sources of NH3 in primary air pollutants in South Korea, highlighting the contributions of land-based and oceanic sources. Our study can help inform policymakers and stakeholders for developing effective regional air pollution control strategies.

Ammonia (NH3) is an important, albeit sticky, precursor for producing secondary inorganic aerosols (SIA), especially in the form of ammonium nitrate (NH4NO3) and ammonium sulfate ((NH4)2SO4). To reduce SIAs, many researchers have attempted to measure the concentration of ambient NH3 using real-time or passive methods. However, NH3 is a highly sticky gas and is therefore difficult to measure using real-time methods without incurring losses during measurement. In this study, four different tubing materials, semi seamless tubes, perfluoroalkoxy (PFA), polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVDF), were used to ascertain the adsorption of NH3 in inlets using real-time instruments. Without heating sample tubes and at 0% relative humidity (RH), this study shows that PTFE had the least adsorption(i.e., 0% at 1 and 2m of sample tube), and semi-seamless tubes had the highest adsorption (i.e., 27.5% at 1 m of sample tube). To calculate the adsorption of NH3 under ambient conditions, at various inlet lengths, the RH of NH3 was varied from 20% to 80%, which showed that shorter inlets and higher RH lower NH3 adsorption at inlets (i.e., 1.74 ppb m−1 at 80% RH and 7.48 ppb m−1 at 20% RH). Additionally, inlet heating was effective in reducing the adsorption of NH3 as the RH decreased. Applying the inlet system (i.e., 2 m of PTFE tube with heating) showed excellent correlation (slope: 0.995 and coefficient: 0.992) between two different real-time measurements while measuring ambient air.