GEOSCAN, résultats de la recherche


TitreNitrate isotopes unveil distinct seasonal N-sources and the critical role of crop residues in groundwater contamination
AuteurSavard, M M; Somers, G; Smirnoff, A; Paradis, D; van Bochove, E; Liao, S
SourceJournal of Hydrology vol. 381, issue 1-2, 2010 p. 134-141,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20100307
ÉditeurElsevier BV
Documentpublication en série
Mediapapier; en ligne; numérique
SNRC11L/05; 11L/12; 21I/09
Lat/Long OENS-64.5000 -63.5000 46.7500 46.2500
Sujetsrégimes des eaux souterraines; pollution de l'eau souterraine; géochimie des eaux souterraines; eau souterraine; bassins versants; etudes de l'environnement; analyse environnementales; nitrate; hydrogéologie; géochimie
Illustrationstables; plots; histograms; location maps
ProgrammeGéoscience des eaux souterraines
Résumé(disponible en anglais seulement)
Globally, fertilizers are identified as principle sources of nitrate in waters of intensely cultivated areas. Here this general concept is appraised on a seasonal basis over a two year period, under temperate climatic conditions. Water (delta2H and delta18O) and nitrate (delta15N and delta18O) isotopes in surface water and groundwater suggest that freshwater is acting as a transport vector conducting nitrate from agricultural soils to groundwater and ultimately to surface water. Measured nitrate isotopes of organic and inorganic fertilizers and of nitrate in groundwater are used to constrain a conceptual apportionment model quantifying the relative seasonal N contributions in an area of intense potato production. Source inputs differ strongly between the growing (summer and fall) and non-growing (winter and spring) periods. Chemical fertilizers and soil organic matter equally dominate and contribute to the growing period load, whereas soil organic matter dominates the non-growing period load, and accounts for over half of the overall annual nitrogen charge. These findings reveal the magnitude of nitrogen cycling by soil organic matter, and point to the benefits of controlling the timing of its nitrate release from this organic material. We conclude that strategies to attenuate contamination by nitrate in waters of temperate climate row-cropping regions must consider nitrogen cycling by soil organic matter, including the crucial role of crop residues throughout both the growing and non-growing seasons.