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Wintertime water‐soluble aerosol composition and particle water content in Fresno, California
Author(s) -
Parworth Caroline L.,
Young Dominique E.,
Kim Hwajin,
Zhang Xiaolu,
Cappa Christopher D.,
Collier Sonya,
Zhang Qi
Publication year - 2017
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2016jd026173
Subject(s) - aerosol , chemistry , particle (ecology) , sea salt , sulfate , particle counter , nitrate , nitric acid , environmental chemistry , ammonium , ammonia , inorganic chemistry , organic chemistry , oceanography , geology
The composition and concentrations of water‐soluble gases and ionic aerosol components were measured from January to February 2013 in Fresno, CA, with a particle‐into‐liquid sampler with ion chromatography and annular denuders. The average (±1 σ ) ionic aerosol mass concentration was 15.0 (±9.4) µg m −3 , and dominated by nitrate (61%), followed by ammonium, sulfate, chloride, potassium, nitrite, and sodium. Aerosol‐phase organic acids, including formate and glycolate, and amines including methylaminium, triethanolaminium, ethanolaminium, dimethylaminium, and ethylaminium were also detected. Although the dominant species all came from secondary aerosol formation, there were primary sources of ionic aerosols as well, including biomass burning for potassium and glycolate, sea spray for sodium, chloride, and dimethylamine, and vehicles for formate. Particulate methanesulfonic acid was also detected and mainly associated with terrestrial sources. On average, the molar concentration of ammonia was 49 times greater than nitric acid, indicating that ammonium nitrate formation was limited by nitric acid availability. Particle water was calculated based on the Extended Aerosol Inorganics Model (E‐AIM) thermodynamic prediction of inorganic particle water and κ‐Köhler theory approximation of organic particle water. The average (±1 σ ) particle water concentration was 19.2 (±18.6) µg m −3 , of which 90% was attributed to inorganic species. The fractional contribution of particle water to total fine particle mass averaged at 36% during this study and was greatest during early morning and night and least during the day. Based on aqueous‐phase concentrations of ions calculated by using E‐AIM, the average (±1 σ ) pH of particles in Fresno during the winter was estimated to be 4.2 (±0.2).