Open AccessIn situ determination of atmospheric aerosol composition as a function of hygroscopic growth
Author(s) -
Herich Hanna,
Kammermann Lukas,
Gysel Martin,
Weingartner Ernest,
Baltensperger Urs,
Lohmann Ulrike,
Cziczo Daniel J.
Publication year - 2008
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 - 10.1029/2008jd009954
Subject(s) - aerosol , differential mobility analyzer , relative humidity , troposphere , chemical composition , environmental science , particle (ecology) , sulfate , in situ , enrichment factor , atmospheric sciences , air mass (solar energy) , combustion , analytical chemistry (journal) , materials science , mineralogy , meteorology , environmental chemistry , chemistry , geology , physics , metallurgy , thermodynamics , oceanography , organic chemistry , boundary layer , heavy metals
An in situ measurement setup to determine the chemical composition of aerosols as a function of hygroscopicity is presented. This has been done by connecting a custom‐built Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) and an Aerosol Time‐of‐Flight Mass Spectrometer (ATOFMS), commercially available from TSI (Model 3800). Single particle bipolar mass spectra from aerosols leaving the HTDMA could thus be obtained as a function of the hygroscopic growth factor. For these studies the HTDMA was set at a relative humidity of 82% and particles with a dry diameter of 260 nm were selected. The setup was first laboratory tested, after which field experiments were performed. Two data sets were obtained during wintertime 2007 in Switzerland: the first in the urban Zurich environment and the other at the remote high alpine research station Jungfraujoch (JFJ). In Zurich, several thousand mass spectra were obtained in less than 2 days of sampling due to a high aerosol loading. At the JFJ, due to low particle concentrations in free tropospheric air masses, a longer sampling period was required. Both in Zurich and at the JFJ, two different growth factor modes were observed. Results from these two locations show that most aerosol particles were a mixture of several compounds. A large contribution of organics and combustion species was found in the less hygroscopic growth mode for both locations. Noncombustion refractory material (e.g., metals, mineral dust, and fly ash) was also highly enhanced in the nonhygroscopic particles. Sulfate, normally considered highly soluble, was found to be a constituent in almost all particles independent of their hygroscopic growth factor.