Temporal and spatial variability of ammonia in urban and agricultural regions of northern Colorado, United States

Abstract

Concentrated agricultural activities and animal feeding operations in the northeastern plains of Colorado represent an important source of atmospheric ammonia (NH 3 ). The NH 3 from these sources contributes to regional fine particle formation and to nitrogen deposition to sensitive ecosystems in Rocky Mountain National Park (RMNP), located ∼ 80 km to the west. In order to better understand temporal and spatial differences in NH 3 concentrations in this source region, weekly concentrations of NH 3 were measured at 14 locations during the summers of 2010 to 2015 using Radiello passive NH 3 samplers. Weekly (biweekly in 2015) average NH 3 concentrations ranged from 2.66 to 42.7 µg m −3 , with the highest concentrations near large concentrated animal feeding operations (CAFOs). The annual summertime mean NH 3 concentrations were stable in this region from 2010 to 2015, providing a baseline against which concentration changes associated with future changes in regional NH 3 emissions can be assessed. Vertical profiles of NH 3 were also measured on the 300 m Boulder Atmospheric Observatory (BAO) tower throughout 2012. The highest NH 3 concentration along the vertical profile was always observed at the 10 m height (annual average concentration of 4.63 µg m −3 ), decreasing toward the surface (4.35 µg m −3 ) and toward higher altitudes (1.93 µg m −3 ). The NH 3 spatial distributions measured using the passive samplers are compared with NH 3 columns retrieved by the Infrared Atmospheric Sounding Interferometer (IASI) satellite and concentrations simulated by the Comprehensive Air Quality Model with Extensions (CAMx). The satellite comparison adds to a growing body of evidence that IASI column retrievals of NH 3 provide very useful insight into regional variability in atmospheric NH 3 , in this case even in a region with strong local sources and sharp spatial gradients. The CAMx comparison indicates that the model does a reasonable job simulating NH 3 concentrations near sources but tends to underpredict concentrations at locations farther downwind. Excess NH 3 deposition by the model is hypothesized as a possible explanation for this trend.

The vertical variability of ammonia in urban Beijing, China

“…S4). High temperatures enhance NH 3 emissions from soil, applied fertilizers, animal waste, vertical mixing and increase volatilization of NH 3 from NH 4 NO 3 particulate matter (Bari et al, 2003;Ianniello et al, 2010;Lin et al, 2006;Meng et al, 2011;Plessow et al, 2005;Walker et al, 2004;Zbieranowski and Aherne, 2012). While high (low) mixed-layer heights in spring and summer (autumn and winter) could dilute (concentrate) NH 3 in the surface boundary layer (Fig.…”

Temporal characteristics of atmospheric ammonia and nitrogen dioxide over China based on emission data, satellite observations and atmospheric transport modeling since 1980

“…Satellite remote sensing offers an opportunity to monitor atmospheric NH 3 and NO 2 with high temporal and spatial resolutions (Warner et al, 2017;Li et al, 2017). NO 2 was measured by multiple space-based instruments, including the Global Ozone Monitoring Experiment (GOME), SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY), Ozone Monitoring Instrument (OMI) and Global Ozone Monitoring Experiment-2 (GOME-2).…”

Technical note: How are NH<sub>3</sub> dry deposition estimates affected by combining the LOTOS-EUROS model with IASI-NH<sub>3</sub> satellite observations?

“…Passive samplers 20 %-41 % (monthly means) (Lolkema et al, 2015) LML Continuous-flow denuders (AMORs)…”