Daly, Shane M.;
O'Connor, David J.;
Healy, David A.;
Hellebust, Stig;
Arndt, Jovanna;
McGillicuddy, Eoin J.;
Feeney, Patrick;
Quirke, Michael;
Wenger, John C.;
Sodeau, John R.
Investigation of coastal sea-fog formation using the WIBS (wideband integrated bioaerosol sensor) technique
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Medientyp:
E-Artikel
Titel:
Investigation of coastal sea-fog formation using the WIBS (wideband integrated bioaerosol sensor) technique
Beteiligte:
Daly, Shane M.;
O'Connor, David J.;
Healy, David A.;
Hellebust, Stig;
Arndt, Jovanna;
McGillicuddy, Eoin J.;
Feeney, Patrick;
Quirke, Michael;
Wenger, John C.;
Sodeau, John R.
Beschreibung:
<jats:p>Abstract. A wideband integrated bioaerosol sensor (WIBS-4) was deployed in
Haulbowline Island, Cork Harbour, to detect fluorescence particles in
real time during July and September 2011. A scanning mobility particle sizer
(SMPS) was also installed providing sizing analysis of the particles over the
10–450 nm range. During the campaign, multiple fog formation events
occurred; they coincided with dramatic increases in the recorded fluorescent
particle counts. The WIBS sizing and fluorescence intensity profiles indicated
that the origin of the signals was potentially non-biological in nature (i.e.
PBAPs, primary biological aerosol particles). Furthermore, the data did not
support the presence of known fluorescing chemical particles like SOA
(secondary organic aerosol). Complementary laboratory studies showed that the
field results could potentially be explained by the adsorption of molecular
iodine onto water droplets to form
I2 ⋅ (H2O)x complexes. The release of
iodine into the coastal atmosphere from exposed kelp at low tides has been
known for many years. This process leads to the production of small
IxOy particles, which can act as cloud condensation
nuclei (CCN). While the process of molecular iodine release from coastal kelp
sources, subsequent particle formation, and the observations of sea mists and
fogs have been studied in detail, this study provides a potential link
between the three phenomena. Of mechanistic interest is the fact that
molecular iodine included into (rather than on) water droplets does not
appear to fluoresce as measured using WIBS instrumentation. The study
indicates a previously unsuspected stabilizing transport mechanism for iodine
in the marine environment. Hence the stabilization of the molecular form
would allow its more extensive distribution throughout the troposphere before
eventual photolysis.
</jats:p>