GEOSCAN, résultats de la recherche

Menu GEOSCAN


TitreMulti-scale nitrate transport in a sandstone aquifer system under intensive agriculture
AuteurParadis, D; Ballard, J -M; Lefebvre, R; Savard, M M
SourceHydrogeology Journal vol. 26, issue 2, 2017 p. 511-531, https://doi.org/10.1007/s10040-017-1668-z (Accès ouvert)
Année2017
Séries alt.Secteur des sciences de la Terre, Contribution externe 20100143
ÉditeurSpringer Nature
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1007/s10040-017-1668-z
Mediapapier; en ligne; numérique
Formatspdf
ProvinceÎle-du-Prince-Édouard
SNRC11E/03; 11E/04; 11E/05; 11E/06
Lat/Long OENS -64.0000 -63.0000 46.5000 46.1667
Sujetsressources en eau souterraine; aquifères; eaux de surface; rivières; bassins versants; géochimie des eaux souterraines; pollution de l'eau souterraine; nitrate; mécanismes de transport; géochimie de l'eau de cours d'eau; géologie du substratum rocheux; lithologie; roches sédimentaires; grès; caractéristiques structurales; fractures; établissement de modèles; simulations par ordinateur; analyses hydrauliques; conductivité hydraulique; lessivage; porosité; qualité de l'eau; regimes d'écoulement; puits d'eau; utilisation du terrain; météorologie; etudes isotopiques; isotopes d'oxygène; azote; datation radiométrique; engrais; fumier; hydrogéologie; géochimie; géologie de l'environnement; Agriculture; géochronologie
Illustrationslocation maps; tables; profiles; time series; models; geoscientific sketch maps; diagrams
ProgrammeGéoscience des eaux souterraines, Caractéristiques d'aquifères et support cartographique
ProgrammeGéosciences environnementales, Sources
Diffusé2017 09 26
Résumé(disponible en anglais seulement)
Nitrate transport in heterogeneous bedrock aquifers is influenced by mechanisms that operate at different spatial and temporal scales. To understand these mechanisms in a fractured sandstone aquifer with high porosity, a groundwater-flow and nitrate transport model - reproducing multiple hydraulic and chemical targets - was developed to explain the actual nitrate contamination observed in groundwater and surface water in a study area on Prince Edward Island, Canada. Simulations show that nitrate is leached to the aquifer year-round, with 61% coming from untransformed and transformed organic sources originating from fertilizers and manure. This nitrate reaches the more permeable shallow aquifer through fractures in weathered sandstone that represent only 1% of the total porosity (17%). Some of the nitrate reaches the underlying aquifer, which is less active in terms of groundwater flow, but most of it is drained to the main river. The river-water quality is controlled by the nitrate input from the shallow aquifer. Groundwater in the underlying aquifer, which has long residence times, is also largely influenced by the diffusion of nitrate in the porous sandstone matrix. Consequently, following a change of fertilizer application practices, water quality in domestic wells and the river would change rapidly due to the level of nitrate found in fractures, but a lag time of up to 20 years would be necessary to reach a steady level due to diffusion. This demonstrates the importance of understanding nitrate transport mechanisms when designing effective agricultural and water management plans to improve water quality.
GEOSCAN ID286161