Document Detail


Photodegradation of natural organic matter from diverse freshwater sources.
MedLine Citation:
PMID:  17640746     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Natural organic matter (NOM) is significant in determining fate, transport and toxicity of metals in aqueous systems but NOM is not a static component; NOM can undergo photochemical changes in chemical structure. These changes will modify NOM quality and in turn influence how metals are transported in the environment, as well as their toxicity to aquatic organisms. Natural organic matter was collected from five freshwater sources using a portable reverse osmosis unit, diluted to about 10 mg CL(-1), then exposed for 13 days to summer temperatures either in the dark or exposed to sunlight. Light exposed NOM had decreases in total organic carbon (TOC) of 8-35% compared to samples kept in a refrigerator (dark, 4 degrees C), and the NOM became optically lighter, as shown by specific absorbance coefficients (SAC) taken at 340 nm (55-76% decreases in SAC(340)). In contrast, dark exposed NOM showed much smaller decreases in TOC (< or = 3%) or SAC(340) (</=32%). For light exposed samples fluorescence excitation-emission matrix spectroscopy showed loss of fluorescence mainly in the 330 nm excitation, 420-450 nm emission range, consistent with loss of fulvic- and humic-like, aromatic groups in the NOM. Commercial (Aldrich) humic acid showed similar changes when exposed to light, with decreases in fulvic and humic fluorescence peaks. Finely ground fish food, used as a source of protein-rich organic matter, showed similar decreases in TOC and SAC(340) when exposed to light, but showed increased SAC(340) in the foil wrapped samples, presumably because bacteria were involved in decomposition of the food organic matter. Overall, these results indicate photodegradation of terrestrially derived, aromatic functional groups (e.g., from lignin) in natural organic matter from various freshwater sources.
Authors:
Anna R Winter; Terry Anne E Fish; Richard C Playle; D Scott Smith; P Jefferson Curtis
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-06-16
Journal Detail:
Title:  Aquatic toxicology (Amsterdam, Netherlands)     Volume:  84     ISSN:  0166-445X     ISO Abbreviation:  Aquat. Toxicol.     Publication Date:  2007 Aug 
Date Detail:
Created Date:  2007-08-20     Completed Date:  2007-11-30     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8500246     Medline TA:  Aquat Toxicol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  215-22     Citation Subset:  IM    
Affiliation:
Wilfrid Laurier University, Department of Biology, Waterloo, Ontario, Canada N2L 3C5.
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MeSH Terms
Descriptor/Qualifier:
Environmental Monitoring*
Fresh Water / analysis*,  chemistry
Light
Organic Chemicals / chemistry,  radiation effects*
Photolysis*
Seasons
Spectrophotometry
Temperature
Time Factors
Water Pollutants, Chemical / chemistry,  radiation effects*
Chemical
Reg. No./Substance:
0/Organic Chemicals; 0/Water Pollutants, Chemical

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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