| Electron pulse radiolysis determination of hydroxyl radical rate constants with Suwannee River fulvic acid and other dissolved organic matter isolates. | |
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MedLine Citation:
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PMID: 17695909 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Pulse radiolysis experiments were conducted on dissolved organic matter (DOM) samples isolated as hydrophobic and hydrophilic acids and neutrals from different sources (i.e., stream, lake, wastewater treatment plant). Absolute bimolecular reaction rate constants for the reaction of hydroxyl radicals (*OH) with DOM (k*(OH), DOM) were determined. k*(OH, DOM) values are expressed as moles of carbon. Based on direct measurement of transient DOM radicals (DOM*) and competition kinetic techniques, both using pulse radiolysis, the k*(OH, DOM) value for a standard fulvic acid from the Suwannee River purchased from the International Humic Substances Society was (1.60 +/- 0.24) x 10(8) M(-1) s(-1). Both pulse radiolysis methods yielded comparable k*(OH, DOM) values. The k*(OH, DOM) values for the seven DOM isolates from different sources ranged from 1.39 x 10(8) M(-1) s(-1) to 4.53 x 10(8) M(-1) s(-1), and averaged 2.23 x 108 M(-1) s(-1) (equivalent to 1.9 x 10(4) (mgC/L)(-1) s(-1)). These values represent the first direct measurements of k*(OH, DOM,) and they compare well with literature values obtained via competition kinetic techniques during ozone or ultraviolet irradiation experiments. More polar, lower-molecular-weight DOM isolates from wastewater have higher k*(OH, DOM) values. In addition, the formation (microsecond time scale) and decay (millisecond time scale) of DOM* transients were observed for the first time. DOM* from hydrophobic acids exhibited broader absorbance spectra than transphilic acids, while wastewater DOM isolates had narrower DOM* spectra more skewed toward shorter wavelengths than did DOM* spectra for hydrophobic acids. |
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Authors:
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Paul Westerhoff; Stephen P Mezyk; William J Cooper; Daisuke Minakata |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Environmental science & technology Volume: 41 ISSN: 0013-936X ISO Abbreviation: Environ. Sci. Technol. Publication Date: 2007 Jul |
Date Detail:
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Created Date: 2007-08-16 Completed Date: 2007-10-12 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0213155 Medline TA: Environ Sci Technol Country: United States |
Other Details:
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Languages: eng Pagination: 4640-6 Citation Subset: IM |
Affiliation:
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Department of Civil and Environmental Engineering, Arizona State University, Box 5306, Tempe, Arizona 85287-5306, USA. p.westerhoff@asu.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Benzopyrans
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chemistry* Fresh Water Hydroxyl Radical / chemistry* Organic Chemicals / chemistry* Pulse Radiolysis* |
| Chemical | |
Reg. No./Substance:
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0/Benzopyrans; 0/Organic Chemicals; 3352-57-6/Hydroxyl Radical; 479-66-3/fulvic acid |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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