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| Titel |
Sea-air fluxes and 1-D ocean modelling of volatile photolabile iodocarbons |
| VerfasserIn |
C. E. Jones, K. E. Hornsby, R. Dunk, G. McFiggans, L. J. Carpenter |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250025926
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| Zusammenfassung |
| Recent research carried out at the Cape Verde Observatory has demonstrated that reactive
iodine chemistry can contribute significantly to photochemical ozone depletion
within the marine boundary layer of the atmosphere. Organoiodine compounds
emitted from the oceans have been proposed as a major source of atmospheric
iodine, however there is currently considerable ambiguity associated with estimates
of iodocarbon sea-air fluxes, and hence the global importance of these gases as
an I atom source to the atmosphere remains unclear. During the MAP (Marine
Aerosol Production) and RHaMBLe (Reactive Halogens in the Marine Boundary
Layer experiment) cruises in the Atlantic Ocean during summer 2006 and 2007
respectively, we made simultaneous measurements of a range of iodocarbons in
surface seawater (2 - 6 m depth) and in marine air, using two GC-MS systems. Our
measurements suggest that the dihalomethanes CH2I2, CH2IBr and CH2ICl may provide a
combined global I atom source which is comparable to that of CH3I, and are the
dominant organic source of iodine in the marine boundary layer. However, since
the dihalomethanes are rapidly photolysed within the top few metres of the water
column, deriving sea-air fluxes for these short-lived gases based on their sub-surface
seawater concentrations is more complex than for the longer-lived iodocarbons
such as CH3I. Consequently, we have developed an oceanic mixed layer model
to predict the difference between the true surface and sub-surface dihalomethane
concentrations, based on a combination of meteorological, biological and physical
ocean parameters, in order to obtain more accurate sea-air fluxes for these gases. |
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