Titre :
|
Hyporheic zone hydrology and nitrogen dynamics in relation to the streambed topography of a N-rich stream
|
Auteurs :
|
A. Hill ;
C. Labadia ;
K. Sanmugadas
|
Type de document :
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article/chapitre/communication
|
Année de publication :
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1998
|
Format :
|
p. 285-310
|
Langues:
|
= Anglais
|
Catégories :
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EAU
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Mots-clés:
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RELATION NAPPE RIVIERE
;
NITRATE
;
LIT DE COURS D'EAU
;
TOPOGRAPHIE
;
TRACEUR
;
SEDIMENT
;
DENITRIFICATION
|
Résumé :
|
The influence of riffle-pool units on hyporheic zone hydrology and nitrogen dynamics was investigated in Brougham Creek, a N-rich agricultural stream in Ontario, Canada. Subsurface hydraulic gradients, differences in background stream and groundwater concentrations of conservative ions, and the movement of a bromide tracer indicated the downwelling of stream water at the head of riffles and upwelling in riffle-pool transitions under base flow conditions. Channel water also flowed laterally into the floodplain at the upstream end of riffles and followed a subsurface concentric flow path for distances of up to 20 m before returning to the stream at the transition from riffles to pools. Differences in observed vs predicted concentrations based on background chloride patterns indicated that the hyporheic zone was a sink for nitrate and a source for ammonium. The removal of nitrate in the streambed was confirmed by the loss of nitrate in relation to co-injected bromide in areas of downwelling stream water in two riffles. Average stream water nitrate-N concentrations of 1.0 mg/L were often depleted to
|
Source :
|
Biogeochemistry, vol.42
|