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| Titel |
The seaweeds Fucus vesiculosus and Ascophyllum nodosum are significant contributors to coastal iodine emissions |
| VerfasserIn |
R.-J. Huang, U. R. Thorenz, M. Kundel, D. S. Venables, D. Ceburnis, K. F. Ho, J. Chen, A. L. Vogel, F. C. Küpper, P. P. A. Smyth, U. Nitschke, D. B. Stengel, H. Berresheim, C. D. O'Dowd, T. Hoffmann |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 10 ; Nr. 13, no. 10 (2013-05-27), S.5255-5264 |
| Datensatznummer |
250018669
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| Publikation (Nr.) |
 copernicus.org/acp-13-5255-2013.pdf |
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| Zusammenfassung |
| Based on the results of a pilot study in 2007, which found high mixing ratios
of molecular iodine (I2) above the intertidal macroalgae (seaweed) beds
at Mweenish Bay (Ireland), we extended the study to nine different locations
in the vicinity of Mace Head Atmospheric Research Station on the west coast
of Ireland during a field campaign in 2009. The mean values of \chem{I_2} mixing
ratio found above the macroalgae beds at nine different locations ranged from
104 to 393 ppt, implying a high source strength of I2. Such mixing
ratios are sufficient to result in photochemically driven coastal
new-particle formation events. Mixing ratios above the Ascophyllum
nodosum and Fucus vesiculosus beds increased with exposure time:
after 6 h exposure to ambient air the mixing ratios were one order of
magnitude higher than those initially present. This contrasts with the
emission characteristics of Laminaria digitata, where most I2 was
emitted within the first half hour of exposure. Discrete in situ measurements
(offline) of I2 emission from ambient air-exposed chamber experiments
of L. digitata, A. nodosum and F. vesiculosus
substantially supported the field observations. Further online and
time-resolved measurements of the I2 emission from O3-exposed
macroalgal experiments in a chamber confirmed the distinct I2 emission
characteristics of A. nodosum and F. vesiculosus compared to
those of L. digitata. The emission rates of A. nodosum and F.
vesiculosus were comparable to or even higher than L. digitata after
the initial exposure period of ~20–30 min. We suggest that
A. nodosum and F. vesiculosus may provide an important source of
photolabile iodine in the coastal boundary layer and that their impact on
photochemistry and coastal new-particle formation should be reevaluated in
light of their longer exposure at low tide and their widespread distribution. |
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