Multidecadal Trajectory of Riverine Nitrogen and Phosphorus Dynamics in Rural Catchments

• Published in: Water Resources Research
• Main Authors: Dupas, Rémi, Minaudo, Camille, Gruau, Gérard, Ruiz, Laurent, Gascuel-Odoux, Chantal
• Other Authors: Sol Agro et hydrosystème Spatialisation (SAS), AGROCAMPUS OUEST, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut National de la Recherche Agronomique (INRA), GéoHydrosystèmes COntinentaux (GéHCO EA6293), Université de Tours, Géosciences Rennes (GR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: catchment; nutrient; agriculture; climate; legacy; long term; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology; Isi; North Atlantic; North Atlantic oscillation
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-01857435; https://hal-insu.archives-ouvertes.fr/insu-01857435/document; https://hal-insu.archives-ouvertes.fr/insu-01857435/file/Dupas_et_al-2018-Water_Resources_Research.pdf; https://doi.org/10.1029/2018wr022905

ISI Document Delivery No.: GU6UJ Times Cited: 0 Cited Reference Count: 66 Dupas, Remi Minaudo, Camille Gruau, Gerard Ruiz, Laurent Gascuel-Odoux, Chantal Amer geophysical union Washington International audience 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 mesoscale agricultural catchments (median size 800 km 2) of western France from seasonal to multidecadal 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 interannual climate variations during three 5-to 10-year dry-wet cycles, influenced by the North Atlantic Oscillation, affected N and P dynamics with persistent interannual 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.