Document Detail

Nitrous oxide formation in the Colne estuary, England: the central role of nitrite.
MedLine Citation:
PMID:  11872474     Owner:  NLM     Status:  MEDLINE    
Nitrate and nitrite concentrations in the water and nitrous oxide and nitrite fluxes across the sediment-water interface were measured monthly in the River Colne estuary, England, from December 1996 to March 1998. Water column concentrations of N(2)O in the Colne were supersaturated with respect to air, indicating that the estuary was a source of N(2)O for the atmosphere. At the freshwater end of the estuary, nitrous oxide effluxes from the sediment were closely correlated with the nitrite concentrations in the overlying water and with the nitrite influx into the sediment. Increases in N(2)O production from sediments were about 10 times greater with the addition of nitrite than with the addition of nitrate. Rates of denitrification were stimulated to a larger extent by enhanced nitrite than by nitrate concentrations. At 550 microM nitrite or nitrate (the highest concentration used), the rates of denitrification were 600 micromol N.m(-2).h(-1) with nitrite but only 180 micromol N.m(-2).h(-1) with nitrate. The ratios of rates of nitrous oxide production and denitrification (N(2)O/N(2) x 100) were significantly higher with the addition of nitrite (7 to 13% of denitrification) than with nitrate (2 to 4% of denitrification). The results suggested that in addition to anaerobic bacteria, which possess the complete denitrification pathway for N(2) formation in the estuarine sediments, there may be two other groups of bacteria: nitrite denitrifiers, which reduce nitrite to N(2) via N(2)O, and obligate nitrite-denitrifying bacteria, which reduce nitrite to N(2)O as the end product. Consideration of free-energy changes during N(2)O formation led to the conclusion that N(2)O formation using nitrite as the electron acceptor is favored in the Colne estuary and may be a critical factor regulating the formation of N(2)O in high-nutrient-load estuaries.
Liang F Dong; David B Nedwell; Graham J C Underwood; Daniel C O Thornton; Iman Rusmana
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Applied and environmental microbiology     Volume:  68     ISSN:  0099-2240     ISO Abbreviation:  Appl. Environ. Microbiol.     Publication Date:  2002 Mar 
Date Detail:
Created Date:  2002-03-01     Completed Date:  2002-05-23     Revised Date:  2013-06-09    
Medline Journal Info:
Nlm Unique ID:  7605801     Medline TA:  Appl Environ Microbiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1240-9     Citation Subset:  IM    
Department of Biological Sciences, John Tabor Laboratories, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom.
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MeSH Terms
Bacteria, Anaerobic / metabolism
Fresh Water / chemistry*,  microbiology*
Nitrates / metabolism
Nitrites / metabolism*
Nitrogen / metabolism
Nitrous Oxide / metabolism*
Reg. No./Substance:
0/Nitrates; 0/Nitrites; 10024-97-2/Nitrous Oxide; 7727-37-9/Nitrogen
Comment In:
Appl Environ Microbiol. 2002 Oct;68(10):5202; author reply 5202-4   [PMID:  12324378 ]

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