AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Response of Total NH$_3 to Reductions in Atmospheric Levels of SO$_2 and NO$_x: An Analysis of Data from SEARCH
RICK SAYLOR, LaToya Myles, Eric Edgerton, NOAA Air Resources Laboratory
Abstract Number: 53 Working Group: Remote and Regional Atmospheric Aerosols
Abstract Ammonia (NH$_3) emissions constitute a major source of reactive nitrogen to the atmosphere and NH$_3 is recognized as an important link in the global nitrogen cycle. Neutralization of sulfuric (H$_2SO$_4) and nitric (HNO$_3) acids in the atmosphere by NH$_3 forms ammonium (NH$_4^+) salts that comprise a significant fraction of the total mass of fine particles in many areas. Due to the rapid equilibration of NH$_3 with ambient ammonium nitrate (NH$_4NO$_3) aerosol particles measurements of gas-phase NH$_3 alone are not sufficient to fully characterize its nature. To do so requires simultaneous measurements of both gas-phase NH$_3 and particle-phase NH$_4^+, preferably at similar temporal resolutions. Nine years (2004-2012) of 24-hr-integrated total NH$_3 (gaseous NH$_3 + PM$_(2.5) NH$_4^+) data from the Southeastern Aerosol Research and Characterization study (SEARCH) network are analyzed and presented in this work and trends in total NH$_3, the ratio of gas-phase to particle-phase NH$_3 and particle acidity are examined in light of the implementation of air quality regulations over recent decades which have reduced concentrations of SO$_2 and NO$_x, precursors to H$_2SO$_4 and HNO$_3 respectively, in the southeast U. S. atmosphere. Implications of the trend findings are explored.