HR: 1340h
AN: H43D-1620    [Abstracts]
TI: EFFECTS OF URBANIZATION ON NITROGEN DYNAMICS IN STREAM (CITY OF LYON, France)
AU: Breil, P
EM: pascal.breil@cemagref.fr
AF: Cemagref, 3 bis quai Chauveau, Lyon, F69336, France
AU: Lafont, M
EM: michel.lafont@cemagref.fr
AF: Cemagref, 3 bis quai Chauveau, Lyon, F69336, France
AU: Namour, P
EM: philippe.nanour@cemagref.fr
AF: Cemagref, 3 bis quai Chauveau, Lyon, F69336, France
AU: Perrin, J
EM: jean-francosi.perrin@cemagref.it
AF: Cemagref, 3 bis quai Chauveau, Lyon, F69336, France
AU: Bariac, T
EM: thierry.baraic@grinon.inra.fr
AF: Université Paris 6 INRA-CNRS- INAPG, Bātiment EGER, Thiverval-Grignon, F 78850, France
AU: Sebilo, M
EM: mathieu.sebilo@ccr.jussieu.fr
AF: Université Paris 6 INRA-CNRS- INAPG, Bātiment EGER, Thiverval-Grignon, F 78850, France
AU: Schimitt, L
EM: laurent.schmitt@univ-lyon2.fr
AF: UMR 5600 CNRS , Universite Lyon2, av. Pierre Mendès-France, Bron, F 69676, France
AU: Chocat, B
EM: bernard.chocat@insa.fr
AF: INSA LYON, Bat Coulomb, Villeurbanne, F69621, France
AU: Aucour, A
EM: aucour@univ-lyon1.fr
AF: UMR 5570 CNRS Université Claude-Bernard Lyon I, 2 rue Dubois, Villeurbanne, F69621, France
AU: * Zuddas, P
EM: zuddas@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4, place jussieu, Paris, F75005, France
AB: The objective of this project was to investigate the impact of urbanization on water exchange and nitrogen dynamics in the surface and-hyporheic waters. The watershed of the Yzeron stream, close to the city of Lyon (France), was selected. It covers rural and periurban areas and has a total surface area of 150 km2. Two stream reaches were sampled: a rural reach and a periurban reach. In every reach, surface and hyporheic waters were collected at six different points up and downstrean geomorphic riffles. Six sampling campaigns were carried out between February 2004 and June 2005. Similar water delta D and delta18O values in surface and hyporheic waters indicate fast exchange between these two compartments in the rural reach. In contrast, water isotopic composition differs between surface and hyporheic waters in the periurban reach. This suggests slower exchange probably related to weaker slope and slight different stream-bed grain-size, compared to rural reach. Nitrate concentration is rather low with a relatively higher level in the rural reach. Inorganic nitrogen is essentially composed of nitrate with occasional occurrence of ammonium in the hyporheic zone of the periurban reach. High delta15N values in nitrate (up to 13.20 per mil), coupled with rather low nitrate concentrations, reflect the process of denitrification in the hyporheic waters. Large fluctuations in nitrate delta15N values (-2.2 to 13.20 per mil) in the rural reach suggest the occurrence of nitrification-denitrification patches. The results of this field study stress the importance of geomorphic riffles in surface-hyporheic water exchange and in stream-bed denitrification pattern.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1625 Geomorphology and weathering (0790, 1824, 1825, 1826, 1886)
DE: 4251 Marine pollution (0345, 0478)
DE: 4870 Stable isotopes (0454, 1041)
SC: Hydrology [H]
MN: 2007 Fall Meeting