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Insights into the Photochemical Transformation of Iodine in Aqueous Systems: Humic acid photosensitised reduction of iodate.
MedLine Citation:
PMID:  23038990     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Marine aerosol is highly enriched in iodine, mostly in the form of iodate (IO3-) ions, compared to its relative abundance in seawater. This paper describes a laboratory study of the photochemical reduction of IO3- in the presence of humic acid. Spectroscopic analysis showed that ~ 20% of IO3- was converted to 'free' iodide (I-) ions and this fraction remained constant as a function of time. Direct detection of an organically fixed fraction (i.e. ~ 80%) was not possible, but a number of test reactions with surrogate organic compounds containing functional groups identified in humic acid structures indicate that efficient substitution of iodine occurs at aromatic 1,2 diol sites. These iodinated humic acids are stable with respect to photolysis at near-UV/visible wavelengths and are likely to account for a significant proportion of the soluble iodine-containing organic material occurring within aerosols. In the lower atmosphere, oxidation of I- to I2 in marine aerosol occurs mostly through the uptake of O3, with H2O2 playing a very minor role. A model of iodine chemistry in the open ocean tropical boundary layer, which incorporates these experimental results, is able to account for the observed enrichment of iodine in marine aerosol.
Authors:
Russell William Saunders; Ravi Kumar; Samantha Macdonald; John Maurice Campbell Plane
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-8
Journal Detail:
Title:  Environmental science & technology     Volume:  -     ISSN:  1520-5851     ISO Abbreviation:  Environ. Sci. Technol.     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-8     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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