Reactive nitrogen in Rocky Mountain National Park during the Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ)

Tuesday, 16 December 2014
Anthony J Prenni1, Katherine Beem Benedict2, Ashley Ruth Evanoski-Cole2, Yong Zhou2, Amy Sullivan2, Derek Day3, Barkley C Sive1, Mark A Zondlo4, Bret A Schichtel5, John Vimont1 and Jeffrey Lee Collett Jr2, (1)National Park Service Lakewood, Lakewood, CO, United States, (2)Colorado State University, Atmospheric Science, Fort Collins, CO, United States, (3)Colorado State University, Fort Collins, CO, United States, (4)Princeton University, Princeton, NJ, United States, (5)National Park Service Fort Collins, Air Resources Division, Fort Collins, CO, United States
The Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) took place in July-August 2014. This collaborative study was aimed at characterizing those processes which control air quality along Colorado’s Front Range. Although the study was largely focused on ozone, an additional goal of the study included characterizing contributions from Front Range sources and long-range transport to total reactive nitrogen in Rocky Mountain National Park (ROMO). Import of reactive nitrogen into ROMO and other pristine, high elevation areas has the potential to negatively impact terrestrial and aquatic ecosystems. We present measurements of reactive nitrogen species measured within ROMO during FRAPPÉ, and compare these data to measurements made in the surrounding areas. At our monitoring site in ROMO, co-located with IMPROVE and CASTNet monitoring, measurements of NO, NO2, NOx, NOy, NH3, and total reactive nitrogen (TNx) were made at high time resolution. Additional measurements of NH3, HNO3 and PM2.5 ions were made at hourly resolution using a MARGA and also at 24-hour time resolution using URG denuder-filter pack sampling. Precipitation samples also were collected to quantify wet deposition of ammonium, nitrate, and organic nitrogen. Finally, measurements of organic gases were made using online gas chromatography and proton transfer reaction-mass spectrometry. Preliminary results for ammonia show both a diel pattern, with concentrations increasing each morning, and a strong dependence on wind direction, implicating the importance of transport. Higher concentrations of NOx and NOy also were observed in the daytime, but in general these patterns differed from that of ammonia. Several upslope events were observed during the measurement period during which NOx, NH3, 2-propylnitrate, 2-butylnitrate, ethane, butane, and pentane were observed to increase in concentration along with ozone.