Dernière mise à jour le : 1 juillet 2018

Multi?decadal trajectory of riverine nitrogen and phosphorus dynamics in rural catchments

DESCRIPTION

The long?term evolution of nutrient dynamics in rivers under changing external forcings, termed hereafter trajectory, is influenced by local human activities and regional climatic variations. Here, we investigate nitrogen (N) and phosphorus (P) dynamics in seven meso?scale agricultural catchments (median size 800 km2) of western France from seasonal to multi?decadal time scales (1970?2016). Results show that, in these catchments dominated by shallow groundwater, long?term nitrate exports responded to variations of the agricultural N surplus with time lags of approximately 10 years. Presence of legacy N storage, related to the catchments' denitrification capacity, was found to increase response times. In contrast, P trends were predominantly controlled by decreasing point source emissions during the study period, and P dynamics were influenced by in?stream retention/remobilization processes that hampered precise quantification of land?to?river diffuse transport processes. Occurrence of inter?annual climate variations during three 5 to 10?year dry?wet cycles, influenced by the North Atlantic Oscillation (NAO), affected N and P dynamics with persistent inter?annual hysteresis patterns among catchment and years. Thus, water quality assessment programs should cover at least five years to decipher the effect of mitigation measures from climate variations.

NOTICE BIBLIOGRAPHIQUE DETAILLÉE

keyboard_arrow_right Titre : Multi?decadal trajectory of riverine nitrogen and phosphorus dynamics in rural catchments
keyboard_arrow_right Type de documentation : Articles
keyboard_arrow_right Auteur(s) personne(s) : Gruau Gérard, Dupas Rémi, Minaudo C., Gascuel-Odoux, Chantal
keyboard_arrow_right Date de publication : 1 juillet 2018
keyboard_arrow_right Editeur(s) : s. n.
keyboard_arrow_right Tags thématiques : bassin versant, changement climatique, dénitrification
keyboard_arrow_right Langue : Anglais
keyboard_arrow_right Collection : Water Resources Research

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