Ammonia (NH₃) is a gas readily released into the air from a variety of biological sources, as well as from industrial and combustion processes. As the most prevalent base gas in the atmosphere, it contributes to the formation of atmospheric particulate matter and its deposition increases the alkalinity of sensitive ecosystems.  In 2010, an Ammonia Monitoring Network (AMoN) was approved to track long-term trends in ambient NH₃ concentrations.  The network currently contains 66 active sites throughout the United States. 

Agriculture has been considered to be the primary source of anthropogenic ammonia, and this research project is looking at how ambient ammonia can vary within a local region with different land uses.  The Champaign-Urbana region (CU) is a micro-urban area surrounded by cropland, so there are a number of possible sources besides agriculture including: urban centers, interstates, parks, and a major university campus. This research study is looking at a transect of CU, roughly perpendicular to prevailing winds.  Radiello® passive samplers were deployed at nine locations for eight 1-week sampling periods along a 15 kilometer transect of CU during the growing season. The aim of the research is to both help determine how representative ammonia concentrations are of a surrounding region and examine the impact of land use on those ambient concentrations.

During spring 2014, when fertilization was prevalent, ambient ammonia concentrations at all sampler sites were between 2.4 μg/m³ and 4.7 μg/m³ with the cropland-located sampler representing the highest concentration.  Once the period of fertilization was over, concentration at all sites were lower and the cropland was no longer the highest concentration.  The lowest site observed is in restored prairie land, located within 0.75 km of cropland and other farm activity.  It is believed other sources besides agriculture are contributing to the background ambient ammonia concentrations of the CU region.