Diurnal Study of the Oxygen Isotope Composition of Nitrate Aerosols in Riverside

Previous research has shown that atmospheric nitrate is anomalously enriched in both 18O/16O and 17O/16O isotopic rations with a Δ17O (Δ17O = δ17O - 0.52×δ18O) of 20 to 30.8 ‰. The Δ17O of ozone is conservatively transferred to nitrate by photochemical NOx oxidation pathways. The isotopic composition of atmospheric nitrate has been modeled on a seasonal level and is a unique tool for tracing the chemical pathways that form atmospheric nitrate and understanding the global nitrogen cycle. The Study of Organic Aerosols in Riverside (SOAR) in the summer of 2005, goals were to characterize organic aerosol particle composition by a variety of techniques and instrumentation by different groups from around the country and through the comparison of data from the various instrumentations and methods gain a better understanding of aerosol composition, transformation over time as well as the analytical techniques in one of the most polluted cities in the United States. Ambient atmospheric nitrate aerosols were collected during the SOAR study from July 15 to August 14, 2005 on the UC Riverside campus. The aerosols were collected for 2 days and 2 nights on glass fiber filters using a high volume aerosol sampler with a 4 stage size-segregating impactor. Other meteorologically significant data was also collected over the course of the study. The data will be analyzed for concentrations and oxygen isotope composition to study the origin, chemical transformation and horizontal transport of aerosol nitrate. The data will also be paired with the data collected by other groups at the study for a more complete understanding of atmospheric nitrate aerosols.