Document Detail

Long-term increase in dissolved organic carbon in streamwaters in Norway is response to reduced acid deposition.
MedLine Citation:
PMID:  18075078     Owner:  NLM     Status:  MEDLINE    
Concentrations of dissolved organic carbon (DOC) in freshwaters have increased significantly in Europe and North America, but the driving mechanisms are poorly understood. Here, we test if the significant increase in TOC (total organic carbon, 90-95% DOC) in three acid-sensitive catchments in Norway of 14 to 36% between 1985 and 2003 is related to climate, hydrology, and/or acid deposition. Catchment TOC export increased between 10 and 53%, which was significant at one site only. The seasonal variation in TOC was primarily climatically controlled, while the deposition of SO4 and NO3--negatively related to TOC--explained the long-term increase in TOC. We propose increased humic charge and reduced ionic strength--both of which increase organic matter solubility--as mechanistic explanations for the statistical relation between reduced acid deposition and increased TOC. Between 1985 and 2003, ionic strength decreased significantly at all sites, while the charge density of TOC increased at two of the sites from 1-2 meq g(-1) C to about 5 meq g(-1) C and remained constant at the third site at 5 meq g(-1) C. The solubility of organic matter is discussed in terms of the pH-dependent deprotonation of carboxylic groups and the ionic strength-dependent repulsion of organic molecules.
Heleen A De Wit; Jan Mulder; Atle Hindar; Lars Hole
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Environmental science & technology     Volume:  41     ISSN:  0013-936X     ISO Abbreviation:  Environ. Sci. Technol.     Publication Date:  2007 Nov 
Date Detail:
Created Date:  2007-12-13     Completed Date:  2008-02-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  7706-13     Citation Subset:  IM    
Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, N-0349 Oslo, Norway.
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MeSH Terms
Carbon / chemistry*
Environmental Monitoring / methods*
Hydrogen-Ion Concentration
Models, Statistical
Organic Chemicals / chemistry*
Regression Analysis
Time Factors
Water Pollutants, Chemical / analysis*
Water Supply
Reg. No./Substance:
0/Acids; 0/Ions; 0/Organic Chemicals; 0/Water Pollutants, Chemical; 7440-44-0/Carbon

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

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