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Mercury photolytic transformation affected by low-molecular-weight natural organics in water.
MedLine Citation:
PMID:  22225824     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Mechanisms by which dissolved organic matter (DOM) mediates the photochemical reduction of Hg(II) in aquatic ecosystems are not fully understood, owing to the heterogeneous nature and complex structural properties of DOM. In this work, naturally occurring aromatic compounds including salicylic, 4-hydrobenzoic, anthranilic, 4-aminobenzoic, and phthalic acid were systematically studied as surrogates for DOM in order to gain an improved mechanistic understanding of these compounds in the photoreduction of Hg(II) in water. We show that the photoreduction rates of Hg(II) are influenced not only by the substituent functional groups such as -OH, -NH(2) and -COOH on the benzene ring, but also the positioning of these functional groups on the ring structure. The Hg(II) photoreduction rate decreases in the order anthranilic acid>salicylic acid>phthalic acid according to the presence of the -NH(2), -OH, -COOH functional groups on benzoic acid. The substitution position of the functional groups affects reduction rates in the order anthranilic acid>4-aminobenzoic acid and salicylic acid>4-hydroxybenzoic acid. Reduction rates correlate strongly with ultraviolet (UV) absorption of these compounds and their concentrations, suggesting that the formation of organic free radicals during photolysis of these compounds is responsible for Hg(II) photoreduction. These results provide insight into the role of low-molecular-weight organic compounds and possibly DOM in Hg photoredox transformation and may thus have important implications for understanding Hg geochemical cycling in the environment.
Authors:
Feng He; Wang Zheng; Liyuan Liang; Baohua Gu
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-1-4
Journal Detail:
Title:  The Science of the total environment     Volume:  -     ISSN:  1879-1026     ISO Abbreviation:  -     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-1-9     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0330500     Medline TA:  Sci Total Environ     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011 Elsevier B.V. All rights reserved.
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