Open AccessNitrate and oxidized organic ions in single particle mass spectra during the 1999 Atlanta Supersite Project
Author(s) -
Lee ShanHu,
Murphy Daniel M.,
Thomson David S.,
Middlebrook Ann M.
Publication year - 2003
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2001jd001455
Subject(s) - nitrate , sulfate , relative humidity , aerosol , particle (ecology) , ion , analytical chemistry (journal) , environmental chemistry , chemistry , mass spectrum , geology , meteorology , organic chemistry , physics , oceanography
We measured the chemical components of 0.35–2.5 μm diameter aerosols with a Particle Analysis by Laser Mass Spectrometry (PALMS) instrument during the Atlanta Supersite Project in August 1999. This paper presents the results for nitrate and oxidized organics. More than 20% of the negative ion spectra of single particles contained nitrate ion peaks. Nitrate peaks showed a clear maximum during the morning at the time of high ambient relative humidity. Nitrate peaks also had a small local maximum during the afternoon when the gas‐phase HNO 3 concentrations were high. This afternoon maximum was more significant for the particles containing soot/hydrocarbons or aluminosilicate components than for the typical organic/sulfate particles. About 45% of negative spectra contained ions indicative of the oxidized organics. Oxidized organic peaks showed a diurnal variation similar to the nitrate: a morning time maximum during the relative humidity maximum and a small maximum in the afternoon. However, in contrast to the nitrate peaks, the afternoon local maximum of oxidized organic peaks was apparent on the organic/sulfate particles. Both nitrate and oxidized organic peaks had larger ion fractions in particles with higher scattered light intensities.