Cloud condensation nuclei activity, droplet growth kinetics, and hygroscopicity of biogenic and anthropogenic secondary organic aerosol (SOA)
Item
Title (Dublin Core)
Cloud condensation nuclei activity, droplet growth kinetics, and hygroscopicity of biogenic and anthropogenic secondary organic aerosol (SOA)
Description (Dublin Core)
<p class="p">Interaction of biogenic volatile organic compounds (VOCs) with Anthropogenic VOC (AVOC) affects the physicochemical properties of secondary organic aerosol (SOA). We investigated cloud droplet activation (CCN activity), droplet growth kinetics, and hygroscopicity of mixed anthropogenic and biogenic SOA (ABSOA) compared to pure biogenic SOA (BSOA) and pure anthropogenic SOA (ASOA). Selected monoterpenes and aromatics were used as representative precursors of BSOA and ASOA, respectively.</p><p class="p">We found that BSOA, ASOA, and ABSOA had similar CCN activity despite the higher oxygen to carbon ratio (O/C) of ASOA compared to BSOA and ABSOA. For individual reaction systems, CCN activity increased with the degree of oxidation. Yet, when considering all different types of SOA together, the hygroscopicity parameter, <i>κ</i><sub>CCN</sub>, did not correlate with O/C. Droplet growth kinetics of BSOA, ASOA, and ABSOA were comparable to that of (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>, which indicates that there was no delay in the water uptake for these SOA in supersaturated conditions.</p><p class="p">In contrast to CCN activity, the hygroscopicity parameter from a hygroscopic tandem differential mobility analyzer (HTDMA) measurement, <i>κ</i><sub>HTDMA</sub>, of ASOA was distinctively higher (0.09–0.10) than that of BSOA (0.03–0.06), which was attributed to the higher degree of oxidation of ASOA. The ASOA components in mixed ABSOA enhanced aerosol hygroscopicity. Changing the ASOA fraction by adding biogenic VOC (BVOC) to ASOA or vice versa (AVOC to BSOA) changed the hygroscopicity of aerosol, in line with the change in the degree of oxidation of aerosol. However, the hygroscopicity of ABSOA cannot be described by a simple linear combination of pure BSOA and ASOA systems. This indicates that additional processes, possibly oligomerization, affected the hygroscopicity.</p><p class="p">Closure analysis of CCN and HTDMA data showed <i>κ</i><sub>HTDMA</sub> was lower than <i>κ</i><sub>CCN</sub> by 30–70 %. Better closure was achieved for ASOA compared to BSOA. This discrepancy can be attributed to several reasons. ASOA seemed to have higher solubility in subsaturated conditions and/or higher surface tension at the activation point than that of BSOA.</p>
Creator (Dublin Core)
Zhao, D. F.
Buchholz, A.
Kortner, B.
Schlag, P.
Rubach, F.
Fuchs, H.
Kiendler-Scharr, A.
Tillmann, R.
Wahner, A.
Watne, Å. K.
Hallquist, M.
Flores, J. M.
Rudich, Y.
Kristensen, K.
Hansen, A. M. K.
Glasius, M.
Kourtchev, I.
Kalberer, M.
Mentel, Th. F.
Date (Dublin Core)
2018-09-07
Type (Dublin Core)
info:eu-repo/semantics/Text
Format (Dublin Core)
info:eu-repo/semantics/application/pdf
Identifier (Dublin Core)
10.5194/acp-16-1105-2016
https://acp.copernicus.org/articles/16/1105/2016/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
Relation (Dublin Core)
info:eu-repo/grantAgreement/EC/FP7/228335
Rights (Dublin Core)
info:eu-repo/semantics/openAccess
