AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Volatility Measurement of Ultrafine Particles in the Midwestern United States: Field Measurement from Bondville, IL
ASHISH SINGH, Robert Bullard, Matthew Johnson, Charles Stanier, University of Iowa
Abstract Number: 405 Working Group: Remote and Regional Atmospheric Aerosols
Abstract Volatility measurement of ultrafine particles (10-100 nm) provides important information about particle growth pathways and thermodynamic properties, and can assist in constraining chemical composition. Bondville, Illinois is a Midwestern United States site where particle nucleation and extensive secondary sulfate and organic aerosol formation has been reported. Furthermore, the volatility of UFPs using V-TDMA has not been reported for many sites in the Midwestern U.S. Consequently, the relative contributions of organic and inorganic constituents to particle growth in the UFP size ranges, and the presence or absence of low-volatile particle cores in 10-100 nm particles, has not been determined.
This study will present results for UFP volatility from preliminary measurements during summer 2013 and spring 2014 sampling campaign in Bondville, IL. Analysis of sub-sample of days showed that nuclei mode particles were mainly from two sources: regional nucleation and localized plume enhanced in SO2. Comparison of volatility across these two conditions indicated similar volume fraction profiles from 100 to 2500 C, with the presence of low-volatile cores during regional nucleation only. These results will be extended to include all sampled data, diurnal, and seasonal variability. Data analysis will be conducted fitting the volatility profile to dynamic and equilibrium volatility basis set profiles for comparison to other studies and to model input profiles. The presence of low volatile particle cores will be determined as a function of co-pollutants and air mass history. Additionally, the mixing state of nuclei and Aitken mode aerosol will be investigated using size resolved volatility at 80-250 0 C. V-TDMA results will be interpreted with respect to pollutant trace gases and particulate times series (e.g. CO, SO2 and NOX, NH3, and BC).