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Stream regulation and nitrogen dynamics in sediment interstices: comparison of natural and straightened sectors of a third‐order stream
Author(s) -
Lefebvre S.,
Marmonier P.,
Pinay G.
Publication year - 2004
Publication title -
river research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.679
H-Index - 94
eISSN - 1535-1467
pISSN - 1535-1459
DOI - 10.1002/rra.765
Subject(s) - hyporheic zone , riffle , biogeochemical cycle , environmental science , hydrology (agriculture) , denitrification , streams , benthic zone , sediment , stream restoration , stream bed , nitrogen , sink (geography) , surface water , habitat , ecology , geology , oceanography , geomorphology , environmental engineering , chemistry , geography , computer network , geotechnical engineering , cartography , organic chemistry , computer science , biology
Nitrogen dynamics were studied in the interstitial environment (i.e. hyporheic zone) of a sandy‐bottom stream in a rural landscape. A third‐order stream in Brittany (France) was studied at 11 stations (riffles) to evaluate spatial patterns of water exchange between surface and interstitial habitats. More intensive sampling was conducted in three riffles selected according to their hydrological characteristics. Chemical characteristics (especially nitrogen) and microbial denitrification were studied at 12.5 and 25 cm depth upstream, and 25 cm depth downstream of each riffle. This study confirms that the interstitial habitat of a N‐rich stream acts as a sink for the nitrate‐nitrogen. Experimental manipulation of sediment cores indicates that denitrification is limited by carbon in surface (i.e. benthic) and by nitrate in hyporheic sediments. River regulation increases inputs of fine sediments, modifies river channel location, and generates changes in the spatial patterns of biogeochemical processes, water origins, and hydrologic exchanges. Copyright © 2004 John Wiley & Sons, Ltd.