AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Water-soluble PM2.5 Composition and Particle Water Content During Wintertime in Fresno, California: Results from DISCOVER-AQ 2013
CAROLINE PARWORTH, Dominique Young, Hwajin Kim, Sonya Collier, Qi Zhang, University of California, Davis
Abstract Number: 189 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract The chemical composition and concentration of ionic PM$_(2.5) and gas-phase species were measured from January – February, 2013 in Fresno, CA with a Particle-Into-Liquid Sampler with Ion Chromatography (PILS-IC) and annular denuders. The average (±1sigma) ionic PM$_(2.5) mass concentration was 17.4 (±10.9) micro-grams m$^(-3), such that NO$_3$^- dominated followed by NH$_4$^+, SO$_4$^(2-), Cl$^-, K$^+, NO$_2$^-, Na$^+, Ca$^(2+), formate, glycolate, and F$^-. Residential wood burning may be a dominate source of glycolate, and mixed sources of formate include vehicles and wood burning. Several amines were identified including methylamine (CH$_3NH$_3$^+) being the most abundant followed by triethanolamine ((HOCH$_2CH$_2)$_3NH$^+), ethanolamine (HOCH$_2CH$_2NH$_3$^+), dimethylamine ((CH$_3)$_2NH$_2$^+), and ethylamine (CH$_3CH$_2NH$_3$^+). Regional sources of amines are likely, and amines are not expected to be important atmospheric bases compared to NH$_4$^+ during this study. PM$_(2.5) K$^+ was identified as an external tracer for residential wood burning in this region. PM$_(2.5) Na$^+, Cl$^-, and (CH$_3)$_2NH$_2$^+ mass concentrations enhanced during a strong sea-breeze event, with Na$^+ serving as an external tracer for sea spray aerosol. NH$_3 exceeded HNO$_3 mass concentrations, such that NH$_4NO$_3 is predicted to be limited by HNO$_3 availability. Particle water was calculated, such that inorganic particle water was approximated using E-AIM theory and organic particle water was approximated with kappa-Kohler theory. The average (± 1sigma) total particle water mass concentration was 22.8 (±21.8) micro-grams m^(-3) such that inorganic particle water dominated total particle water mass (87%). Particle water mass was the greatest during early morning and night hours.