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| Titel |
Iodine and bromine speciation in snow and the effect of orographically induced precipitation |
| VerfasserIn |
B. S. Gilfedder, M. Petri, H. Biester |
| 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 ; 7, no. 10 ; Nr. 7, no. 10 (2007-05-21), S.2661-2669 |
| Datensatznummer |
250004994
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| Publikation (Nr.) |
 copernicus.org/acp-7-2661-2007.pdf |
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| Zusammenfassung |
| Iodine is an essential trace element for all mammals and may also influence
climate through new aerosol formation. Atmospheric bromine cycling is also
important due to its well-known ozone depletion capabilities. Despite
precipitation being the ultimate source of iodine in the terrestrial
environment, the processes effecting its distribution, speciation and
transport are relatively unknown. The aim of this study was to determine the
effect of orographically induced precipitation on iodine concentrations in snow
and also to quantify the inorganic and organic iodine and bromine species.
Snow samples were collected over an altitude profile (~840 m) from the
northern Black Forest and were analysed by ion-chromatography - inductively
coupled plasma mass spectrometry (IC-ICP-MS) for iodine and bromine species
and trace metals (ICP-MS). All elements and species concentrations in snow
showed significant (r2>0.65) exponential decrease relationships with
altitude despite the short (5 km) horizontal distance of the transect. In
fact, total iodine more than halved (38 to 13 nmol/l) over the 840 m height
change. The results suggest that orographic lifting and subsequent
precipitation has a major influence on iodine concentrations in snow. This
orographically induced removal effect may be more important than lateral
distance from the ocean in determining iodine concentrations in terrestrial
precipitation. The microphysical removal process was common to all elements
indicating that the iodine and bromine are internally mixed within the snow
crystals. We also show that organically bound iodine is the dominant iodine
species in snow (61–75%), followed by iodide. Iodate was only found in
two samples despite a detection limit of 0.3 nmol/l. Two unknown but most
likely anionic organo-I species were also identified in IC-ICP-MS
chromatograms and comprised 2–10% of the total iodine. The majority of
the bromine was inorganic bromide with a max. of 32% organo-Br. |
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