TY - JOUR
T1 - Hygroscopic growth and CCN activity of HULIS from different environments
AU - Kristensen, Thomas Bjerring
AU - Wex, Heike
AU - Nekat, Bettina
AU - Nøjgaard, Jacob Klenø
AU - Pinxteren, Dominik van
AU - Lowenthal, Douglas H.
AU - Mazzoleni, Lynn R.
AU - Dieckmann, Katrin
AU - Bender Koch, Christian
AU - Mentel, Thomas F.
AU - Herrmann, Hartmut
AU - Hallar, A. Gannet
AU - Stratmann, Frank
AU - Bilde, Merete
PY - 2012
Y1 - 2012
N2 - Humic-like substances (HULIS) constitute a significant fraction of aerosol particles in different environments. Studies of the role of HULIS in hygroscopic growth and cloud condensation nuclei (CCN) activity of aerosol particles are scarce, and results differ significantly. In this work the hygroscopic growth and CCN activity of water extracts (WE) and HULIS extracted from particulate matter (PM) collected at a polluted urban site (Copenhagen, Denmark), a rural site (Melpitz, Germany) and the remote site Storm Peak Laboratory (Colorado, USA) were investigated. Measurements of inorganic ions, elemental carbon, organic carbon and water soluble organic carbon (WSOC) within the PM confirmed that the sources of aerosol particles most likely differed for the three samples. The hygroscopic properties of the filtered WE were characterized by hygroscopicity parameters for subsaturated conditions (κGF) of 0.25, 0.41 and 0.22, and for supersaturated conditions κCCN were 0.23, 0.29 and 0.22 respectively for the urban, rural and remote WE samples. The measured hygroscopic growth and CCN activity were almost identical for the three HULIS samples and could be well represented by κGF = 0.07 and κCCN = 0.08-0.10 respectively. Small amounts of inorganic ions were present in the HULIS samples so the actual values for pure HULIS are expected to be slightly lower (κ GF* = 0.04-0.06 and κCCN* = 0.07-0.08). The HULIS samples are thus less hygroscopic compared to most previous studies. To aid direct comparison of hygroscopic properties of HULIS from different studies, we recommend that the fraction of inorganic species in the HULIS samples always is measured and reported.
AB - Humic-like substances (HULIS) constitute a significant fraction of aerosol particles in different environments. Studies of the role of HULIS in hygroscopic growth and cloud condensation nuclei (CCN) activity of aerosol particles are scarce, and results differ significantly. In this work the hygroscopic growth and CCN activity of water extracts (WE) and HULIS extracted from particulate matter (PM) collected at a polluted urban site (Copenhagen, Denmark), a rural site (Melpitz, Germany) and the remote site Storm Peak Laboratory (Colorado, USA) were investigated. Measurements of inorganic ions, elemental carbon, organic carbon and water soluble organic carbon (WSOC) within the PM confirmed that the sources of aerosol particles most likely differed for the three samples. The hygroscopic properties of the filtered WE were characterized by hygroscopicity parameters for subsaturated conditions (κGF) of 0.25, 0.41 and 0.22, and for supersaturated conditions κCCN were 0.23, 0.29 and 0.22 respectively for the urban, rural and remote WE samples. The measured hygroscopic growth and CCN activity were almost identical for the three HULIS samples and could be well represented by κGF = 0.07 and κCCN = 0.08-0.10 respectively. Small amounts of inorganic ions were present in the HULIS samples so the actual values for pure HULIS are expected to be slightly lower (κ GF* = 0.04-0.06 and κCCN* = 0.07-0.08). The HULIS samples are thus less hygroscopic compared to most previous studies. To aid direct comparison of hygroscopic properties of HULIS from different studies, we recommend that the fraction of inorganic species in the HULIS samples always is measured and reported.
U2 - 10.1029/2012JD018249
DO - 10.1029/2012JD018249
M3 - Journal article
SN - 0148-0227
VL - 117
JO - Journal of Geophysical Research
JF - Journal of Geophysical Research
IS - D22, 27
M1 - D22203
ER -