Ammonia emissions from a dairy housing and wastewater treatment plant quantified with an inverse dispersion method accounting for deposition loss

ABSTRACT

Ammonia (NH₃) emissions negatively impact air, soil, and water quality, hence human health and biodiversity. Significant emissions, including the largest sources, originate from single or multiple structures, such as livestock facilities and wastewater treatment plants (WWTPs). The inverse dispersion method (IDM) is effective in measuring total emissions from such sources, although depositional loss between the source and point of measurement is often not accounted for. We applied IDM with a deposition correction to determine total emissions from a representative dairy housing and WWTP during several months in autumn and winter in Switzerland. Total emissions were 1.19 ± 0.48 and 2.27 ± 1.53 kg NH₃ d⁻¹ for the dairy housing and WWTP, respectively, which compared well with literature values, despite the paucity of WWTP data. A concurrent comparison with an inhouse tracer ratio method at the dairy housing indicated an offset of the IDM emissions by < 20%. Diurnal emission patterns were evident at both sites mostly driven by changes in air temperature with potential lag effects such as following sludge agitation. Modeled deposition corrections to adjust the concentration loss detected at the measurement point with the associated footprint were 22–28% of the total emissions and the cumulative fraction of deposition to emission modeled with distance from the source was between 7% and 12% for the measurement distances (60–150 m). Although estimates of depositional loss were plausible, the approach is still connected with substantial uncertainty, which calls for future validation measurements. Longer measurement periods encompassing more management activities and environmental conditions are required to assess predictor variable importance on emission dynamics. Combined, IDM with deposition correction will allow the determination of emission factors at reduced efforts and costs, thereby supporting the development and assessment of emission reducing methods and expand the data availability for emission inventories.

Implications: Ammonia emissions must be measured to determine emission factors and reporting national inventories. Measurements from structures like farms and industrial plants are complex due to the many different emitting surfaces and the building configuration leading to a poor data availability. Micrometeorological methods provide high resolution emission data from the entire structure, but suffer from uncertainties, as the instruments must be placed at a distance from the structure resulting in a greater loss of the emitted ammonia via dry deposition before it reaches the measurement. This study constrains such emission measurements from a dairy housing and wastewater treatment plant by applying a simple correction to account for the deposition loss and compares the results to other methods.

Acknowledgment

Funding was obtained from the Swiss Federal Office for the Environment (Contract 00.5082.P2I R254-0652 for the dairy housing measurements and Contract 06.0091.PZ/R281-0748 for the WWTP). We thank Michael Zähner (Ruminant Nutrition and Emission Research Group, Agroscope, Tänikon), Kerstin Zeyer and Simon Wyss (Laboratory for Air Pollution/Environmental Technology, EMPA, Dübendorf) for conducting the iTRM measurements and the operators of the WWTP Moossee-Urtenenbach, specifically B. Oberer, as well as Wenzel Gruber and Tobias Bührer (Eawag) for their support. We are grateful to Markus Jocher (Climate and Agriculture Group, Agroscope, Zürich) for supporting the operation of the measurement devices. Support with modeling issues and interpretation of the data by Christof Ammann (Climate and Agriculture Group, Agroscope, Zürich) and Albrecht Neftel (NRE) is gratefully acknowledged. Finally, we thank the farmers, namely Walter Denzler, Wängi and those surrounding the WWTP for their collaboration and allowing the placement of the measurement devices.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this paper can be accessed online at https://doi.org/10.1080/10962247.2023.2271426

Data availability statement

Due to the data volume only the 30-min averaged data that support the findings of this study are openly available in Zenodo (DOI: 10.5281/zenodo.8047581 for the dairy housing data and DOI: 10.5281/zenodo.8032908 for the WWTP data). The raw data are available from the corresponding author, AV, upon reasonable request.

Additional information

Funding

The work was supported by the Swiss Federal Office for the Environment [Contract 00.5082.P2I R254-0652 and contract 06.0091.PZ/R281-0748].

Notes on contributors

Alex C. Valach

Alex C. Valach Research Scientist in the group on Gaseous Emissions from Agriculture at the Bern University of Applied Sciences, Switzerland with a focus on trace gas flux measurements from natural ecosystems and anthropogenic sources.

Christoph Häni

Christoph Häni Research Scientist in the group on Gaseous Emissions from Agriculture at the Bern University of Applied Sciences, Switzerland focussing on dispersion modelling and emission estimation of agricultural ammonia and methane sources.

Marcel Bühler

Marcel Bühler Postdoc at the Department of Biological and Chemical Engineering at Aarhus University, Denmark researching gaseous emissions from dairy barns.

Joachim Mohn

Joachim Mohn Leader of the Emissions and Isotopes group at the Swiss Federal Laboratory for Material Science and Technology, Empa in Dübendorf, Switzerland. The group researches and provides analytical tools to quantify diffuse emissions and trace transformation pathways using isotopes.

Sabine Schrade

Sabine Schrade Project Leader in sustainable dairy production systems with the Ruminant Research Unit based at the experimental dairy barn run by the Swiss Federal Research Station Agroscope Tänikon, Switzerland.

Thomas Kupper

Thomas Kupper Leader of the group on Gaseous Emissions from Agriculture at the Bern University of Applied Sciences, Switzerland. Responsible for the Agrammon emissions model and providing the Swiss national emission inventory for ammonia emissions.