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1.3 PHYSICAL SCIENCES, 1.4 CHEMICAL SCIENCES
Abstract. A wideband integrated bioaerosol sensor (WIBS4) 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 10–450nm 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.Thereleaseofiodineintothecoastalatmosphere from exposed kelp at low tides has been known for many years. This process leads to the production of small IxOy particles,whichcanactascloudcondensationnuclei(CCN). While the process of molecular iodine release from coastal kelp sources, subsequent particle formation, and the observationsofseamistsandfogshavebeenstudiedindetail,this studyprovidesapotentiallinkbetweenthethreephenomena. 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 studyindicatesapreviouslyunsuspectedstabilizingtransport mechanism for iodine in the marine environment.
S.M.Daly et al.(2019) Investigation of Coastal Sea-Fog Formation using the WIBS (Wide Band Integrated Bioaerosol Sensor) Technique, Atmos. Chem. Phys., 19, 5737–5751, 2019. doi: 10.5194/acp-19-5737-2019