Mass Spectral Characterization of Size Resolved Atmospheric Aerosol Particles Collected from Skidaway Island, GA

TRET BURDETTE, Rachel Bramblett, Kathryn Zimmermann, Amanda Frossard, University of Georgia

     Abstract Number: 70
     Working Group: Remote and Regional Atmospheric Aerosol

Abstract
Atmospheric aerosol particles in a coastal environment are influenced by multiple sources and may include fresh and aged sea spray aerosols, as well as biogenic and anthropogenic particles. During a two-week period in May and June of 2018, atmospheric aerosol particles were collected at the Skidaway Institute of Oceanography, located on the Georgia coast. Sized-resolved particles in 10 size ranges were collected over 24-hour sampling periods, and accompanying number size distributions were measured continuously. HYSPLIT back trajectories suggest that air masses from two different source regions were influencing the particle number concentrations and compositions. During the first half of the study, air masses originated over the ocean, and there were higher wind speeds and lower particle concentrations (~800 cm^-3). The second half of the study had higher particle number concentrations (~3000 cm^-3), larger particles, lower wind speeds, and air masses coming from the west, over Savannah, GA. High resolution electrospray ionization quadrupole time of flight mass spectrometry (ESI-Q-TOF-MS), in both positive and negative ionization modes, was used to characterize the organic fraction of the aerosol particles extracted with graphitized carbon and C-18 solid phase extractions. Specific peaks were present in the mass spectra across all 10 size ranges, while others varied in intensity as a function of particle size. Concentrations of major ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, NH₄⁺, Cl^-, and SO₄^2-) in the particles were compared to organic signatures to infer the influences of different sources. The results suggest that aged sea spray aerosols influenced the particles from the first half of the study, indicated with high O/C values and spectral signatures that compared well with those of organic molecules extracted from estuarine water collected at the sampling site. The spectral signatures of the organics differed in the second half of the study and had more anthropogenic and terrestrial influences.