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| Titel |
In situ measurements of molecular iodine in the marine boundary layer: the link to macroalgae and the implications for O3, IO, OIO and NOx |
| VerfasserIn |
R.-J. Huang, K. Seitz, J. Buxmann, D. Pöhler, K. E. Hornsby, L. J. Carpenter, U. Platt, 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 ; 10, no. 10 ; Nr. 10, no. 10 (2010-05-26), S.4823-4833 |
| Datensatznummer |
250008479
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| Publikation (Nr.) |
 copernicus.org/acp-10-4823-2010.pdf |
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| Zusammenfassung |
| Discrete in situ atmospheric measurements of molecular iodine
(I2) were carried out at Mace Head and Mweenish Bay on the west coast
of Ireland using diffusion denuders in combination with a gas
chromatography-mass spectrometry (GC-MS) method. I2, IO and OIO were
also measured by long-path differential optical absorption spectroscopy
(LP-DOAS). The simultaneous denuder and LP-DOAS I2 measurements were
well correlated (R2=0.80) but the denuder method recorded much higher
concentrations. This can be attributed to the fact that the in situ measurements
were made near to macroalgal sources of I2 in the intertidal zone,
whereas the LP-DOAS technique provides distance-averaged mixing ratios of an
inhomogeneous distribution along the light-path. The observed mixing ratios
of I2 at Mweenish Bay were significantly higher than that at Mace Head,
which is consistent with differences in local algal biomass density and
algal species composition. Above algal beds, levels of I2 were found to
correlate inversely with tidal height and positively with the concentrations
of O3 in the surrounding air, indicating a role for O3 in the
production of I2 from macroalgae, as has been previously suggested from
laboratory studies. However, measurements made ~150 m away from the
algal beds showed a negative correlation between O3 and I2 during
both day and night. We interpret these results to indicate that the released
I2 can also lead to O3 destruction via the reaction of O3 with I
atoms that are formed by the photolysis of I2 during the day and via the
reaction of I2 with NO3 radicals at night. The results show that
the concentrations of daytime IO are correlated with the mixing ratios of
I2, and suggest that the local algae sources dominate the inorganic
iodine chemistry at Mace Head and Mweenish Bay. |
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