Comprehensive characterisation of temporal variations in concentrations of gaseous ammonia and nitrogen oxides in typical urban atmosphere

Atmospheric ammonia (NH3) is a well-known contributor to secondary particle formation and can lead to severe environmental degradation and human health outcomes. In the context of the very limited knowledge about updated data on NH3 levels in urban areas, this paper presents the results of a one-year (Apr 2023–Mar 2024) measurement campaign of NH3 concentrations conducted at the urban background site in Zabrze, located in the central part of the Upper Silesian Industrial District (USID) (southern Poland), which could be considered one of the European hotspots. The research was performed using an automatic ammonia analyzer Model T201 by Teledyne API, which provides data on the levels of NH3 and other gaseous nitrogen compounds (NO (nitrogen oxide), NO2 (nitrogen dioxide), NOx (nitrogen oxides)) at hourly time resolution. Consequently, this enabled an analysis of specific temporal variations of NH3 concentrations, and therefore allowed the identification of its possible emission sources and insight into processes involving ammonia. The results obtained in this study revealed that ammonia stood out from nitrogen oxides and other atmospheric pollutants – with high NH3 concentrations recorded during spring and summer, which is related to the high intensity of gaseous NH3 formation under warm meteorological conditions. A different situation was observed in the hourly NH3 concentration distribution scheme, which was manifested by much less visible diurnal variations of NH3 levels, with no characteristic morning maximum, as well as the occurrence of a broad afternoon maximum in the summer. In summary, anthropogenic sources had a significant impact on NH3 concentrations in the area under consideration, with a greater role of traffic in the case of NOx, and a biomass and fossil fuel combustion and/or industrial sources – for NH3. Local meteorological conditions also had a notable influence on NH3 levels, of which air temperature (positive correlation) and wind speed (negative correlation) were found to be the most important. The ongoing research is planned to be continued, as it can provide valuable scientific data for the development of air quality protection strategies and programmes in urban areas, especially in the field of reducing emissions of gaseous precursors of particulate matter.

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Opracowanie rekordu ze środków MNiSW, umowa nr POPUL/SP/0154/2024/02 w ramach programu "Społeczna odpowiedzialność nauki II" - moduł: Popularyzacja nauki (2025).