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Flood survey of nitrate behaviour using nitrogen isotope tracing in the critical zone of a French agricultural catchment

Paul, Alexia and Moussa, Issam and Payre, Virginie and Probst, Anne and Probst, Jean-Luc Flood survey of nitrate behaviour using nitrogen isotope tracing in the critical zone of a French agricultural catchment. (2015) Comptes Rendus Geoscience, 347 (7-8). 328-337. ISSN 1631-0713

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Official URL: https://dx.doi.org/10.1016/j.crte.2015.06.002


Measurements of δ15N–NO3– were taken in a highly flood-responsive agricultural catchment in the southwest of France to trace the sources and transfer pathways of nitrates during flood events. From January to March 2013, surface water samples were collected every week at the outlet, and four floods were sampled with a high resolution. Sampling was also performed in surface waters and sand lenses from the rest of the basin to trace nitrate sources and processes spatially. Nitrate extractions were performed using a method based on the solubility difference between inorganic salts and organic solutions. The δ15N values were in the range of surface water contaminated by N-fertilisers. Depending on the hydroclimatic event, nitrates resulted from a combination of sources and processes. At the start of the floods, the values of δ15N–NO3– and nitrate concentrations were low, demonstrating the dilution of water with rainwater. During a second phase, the nitrate concentration and the δ15N were higher. Deeper waters and soil solutions were the second source of nitrates. When the water level was low, both nitrate concentration and isotopic composition were high. These values reflected the denitrification processes that occurred in the soil under anaerobic conditions. An analysis of δ15N–NO3– in stream water in a small agricultural catchment was efficient at determining the origin of nitrates during flood events using a simple method.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The original PDF of the article can be found at Comptes Rendus Geoscience website : https://www.sciencedirect.com/science/article/pii/S1631071315000607?via%3Dihub
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
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Deposited On:07 Oct 2015 07:49

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