Continuous monitoring of ammonia (NH3) concentrations with Cavity Ring-Down Spectroscopy

Ammonia is a hazardous air pollutant with detrimental impacts on both health and the environment. The primary sources of NH₃ emissions into the atmosphere are associated with agricultural activities and processes, including fertilizer utilization, decomposition of organic matter, and animal excretions. The characterization and quantification of NH₃ emissions in livestock environments are pivotal to comply with regulations and in assessing mitigation options. However, accurate monitoring of NH₃ emissions can be challenging due to the high reactivity of NH₃ and its tendency to adsorb to surfaces.

Here we present performance data for two new Cavity Ring-Down Spectroscopy (CRDS) ammonia analyzers that allow to accurately determine ammonia concentrations over a wide dynamic range: The SI2103 analyzer is the successor of the G2103 analyzer and the ideal solution for air quality monitoring at ambient concentrations as well as close to ammonia sources, and the newly released G2509 analyzer is the ideal solution to monitor ammonia concentrations along with CO₂, CH₄ and N₂O.

Key features of the SI2103 and the G2509 are: (i) excellent response time, (ii) low calibration requirements, (iii) field deployable, (iv) negligible interference (‘interference-free’) [1] , (v) long term unattended operation, and (vi) the possibility to measure multiple species. We will compare the performance of the SI2103 and the G2509 and discuss best practices for accurately measuring ammonia concentrations.

[1] Kamp, J. N., Chowdhury, A., Adamsen, A. P. S. & Feilberg, A. Negligible influence of livestock contaminants and sampling system on ammonia measurements with cavity ring-down spectroscopy. Atmos. Meas. Tech. Discuss. 1–20 (2019). doi:10.5194/amt-2018-377