Characterizing Ammonia and Methane Emissions from Northern Colorado Livestock

Emissions of ammonia and methane from livestock contribute significantly to reduced air quality and increased greenhouse gas concentrations. Quantifying the magnitude of methane and ammonia emissions from livestock can help guide future mitigation measures. Challenges to this quantification process include isolating livestock emissions from other co-located sectors such as oil and gas production, and accounting for management practices and environmental conditions which can impact the rate and timing of livestock emissions. Here, we present an analysis of a multi-month observational study of methane, ethane, and ammonia performed in Northern Colorado. We demonstrate how a dynamic linear model analysis of ammonia, ethane, and methane time series data can disentangle methane emissions from multiple sectors. Agriculture emissions ratios from this analysis span a wide range of values which were found to be consistent with other studies performed across multiple states. Using directed acyclic graphs to remove confounding variable biases such as temperature and time of day, we calculate the sensitivity of ammonia emissions to latent (e.g. animal activity) and measured (e.g. temperature) variables. Finally, we perform an inverse analysis of the agriculture-apportioned methane time series and find a 50% larger agricultural methane flux than predicted by the emissions inventory within the study’s sensitivity area.