Quantification of Atmospheric Ammonia Concentrations: A Review of Its Measurement and Modeling

Abstract

Ammonia (NH3), the most prevalent alkaline gas in the atmosphere, plays a significant role in PM2.5 formation, atmospheric chemistry, and new particle formation. This paper reviews quantification of [NH3] through measurements, satellite-remote-sensing, and modeling reported in over 500 publications towards synthesizing the current knowledge of [NH3], focusing on spatiotemporal variations, controlling processes, and quantification issues. Most measurements are through regional passive sampler networks. [NH3] hotspots are typically over agricultural regions, such as the Midwest US and the North China Plain, with elevated concentrations reaching monthly averages of 20 and 74 ppbv, respectively. Topographical effects dramatically increase [NH3] over the Indo-Gangetic Plains, North India and San Joaquin Valley, US. Measurements are sparse over oceans, where [NH3] ≈ a few tens of pptv, variations of which can affect aerosol formation. Satellite remote-sensing (AIRS, CrIS, IASI, TANSO-FTS, TES) provides global [NH3] quantification in the column and at the surface since 2002. Modeling is crucial for improving understanding of NH3 chemistry and transport, its spatiotemporal variations, source apportionment, exploring physicochemical mechanisms, and predicting future scenarios. GEOS-Chem (global) and FRAME (UK) models are commonly applied for this. A synergistic approach of measurements↔satellite-inference↔modeling is needed towards improved understanding of atmospheric ammonia, which is of concern from the standpoint of human health and the ecosystem.

Seasonal and Spatial Variations of Atmospheric Ammonia in the Urban and Suburban Environments of Seoul, Korea

“…With the exception of the Background (HUFS) site, all of the studied sites recorded the lowest ammonia concentrations during winter, which agrees with the findings of previous ammonia measurement studies [66]. This decrease in ammonia concentration during the winter has been linked to the formation of NH 4 NO 3 (ammonium nitrate) particulates [6,[67][68][69].…”

4D‐Var Inversion of European NH3 Emissions Using CrIS NH3 Measurements and GEOS‐Chem Adjoint With Bi‐Directional and Uni‐Directional Flux Schemes

“…Meanwhile, direct ammonia emission monitoring is usually expensive and thus is not feasible to be carried out at large scales. Instead, monitoring NH 3 concentrations and its downstream products (e.g., $$\mathrm{N}{\mathrm{H}}_{4}^{+}$$ and NH x wet deposition) at relatively lower cost can be used to investigate NH 3 emissions from local to national scales and to help assess the effectiveness of emission control policies (Nair & Yu, 2020; Sutton et al., 2003).…”

Recent Advances in Ammonia Gas Sensors Based on Carbon Nanomaterials

“…The exposure limit of ammonia to humans is 35 ppm for 10 min according to Occupational Safety and Health Administration [ 5 , 6 ], showing that this substance is incredibly dangerous. It can be noted that the content of ammonia in the atmosphere is relatively low and only reaches the level of ppb (1–5 ppb) [ 2 , 7 ]. At the same time, this gas is extremely aggressive and highly toxic and has harmful effects on the skin, eyes, digestive tract, and mouth [ 8 , 9 ].…”