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1. Main water pathways in cultivated clayey calcisols in molassic hills in southwestern France: Toward spatialization of soil waterlogging

Author

Benjamin Trochon, Vincent Bustillo, Laurent Caner, Sylvain Pasquet, Virginie Suc, Franck Granouillac, Anne Probst, Jean‐Luc Probst, Tiphaine Tallec, and Maritxu Guiresse

Subjects
Environmental sciences, GE1-350, Geology, QE1-996.5
Abstract

Abstract Local waterlogging often occurs on the steep slopes of clayey–calcareous soils in southwestern France, causing nutrients and pollutants transfer to the river bodies and reduced ecosystems services. These soils developed in the Miocene molassic hill formation and are generally impermeable with abundant traces of hydromorphy and heterogenous spatial distribution. This article aims to describe the hydrological functioning of these soils, based on a cross analysis of pedological, hydrological, and geophysical characterizations. Our experimental site is the catchment area located in Auradé (southwestern France). Here, we analyze the flows at the outlet of the studied watershed together with piezometric and climatic monitoring from September 2020 to September 2021. We show that the hydrological year is divided into three phases: first, a soil recharge phase with an effective rainfall of about 100 mm; second, a saturation phase, when 80% of the effective precipitation is drained mostly by runoff and hypodermic flows; third, a drying phase. Soil waterlogging events usually occur during the saturation phase. They are due to several forms of flow: surface runoff associated with return flow, hypodermic flow caused by the presence of soil layers with lower hydraulic conductivity in the subsurface (swelling clays and plowing sole) and groundwater flow with intermittent connection of the soil water table in the hillside to the alluvial groundwater table. We also conducted independent seismic refraction tomography analyses that validate localized waterlogging patterns along the catchment and open the way to spatializing areas with high waterlogging potential at the scale of the study plot.

Published
2023
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2. Pesticide Distribution in Pond Sediments from an Agricultural Catchment (Auradé, SW France)

Author

Betty Chaumet, Jean-Luc Probst, Pierre Eon, Virginie Payré-Suc, Franck Granouillac, Thierry Camboulive, David Riboul, Corinne Pautot, Marie-Josée Tavella, Benjamin Trochon, and Anne Probst

Subjects
wetland, pesticides, bottom sediments, agricultural catchment, storage, spatial distribution, Environmental sciences, GE1-350
Abstract

Currently, pesticides are massively used in agricultural areas end up in watercourses, as they are usually final receptacles of organic contamination. A large number of wetlands such as ponds occurred in agricultural catchments. They are dynamic and complex systems which contains different compartments like the water column, sediments and biota. The sediment compartment can store contaminants according to their physicochemical properties, but this process is continuously challenged because of settling and resuspension mechanisms. The role of the sediments regarding pesticides behavior and their fate is still poorly investigated. Our study aimed to fill this gap, particularly considering the Bassioué pond, which is located in the carbonated agricultural upper sub-catchment of the Auradé critical zone observatory (Gers, France), with a wheat/sunflower crop rotation and a steep slope enhancing erosion phenomenon. We focused on pesticide storage in the sediments which represent the main compartment due to the environmental conditions. Our current objective was to understand (i) how and where pesticides are stored in the sediments, and (ii) the relationship with the characteristics of sediments, supposed to be highly involved in the storage and degradation of pesticides. Two field campaigns were carried out to collect sediment samples within a regular quadrat from the inlet to the outlet of the pond in autumn 2019 and summer 2020 at different depth. A set of three pesticide was quantified as well as sediment texture. The results highlighted that sediment particle size distribution varied between upstream and downstream of the pond: from the finest to the coarsest; as did the spatial distribution of pesticides. This reveled that pesticides were partly controlled by their physicochemical properties: most hydrophilic pesticides had greater affinity with the finest fractions of the sediments. A difference in pesticide storage according to the depth has been observed, especially for boscalid (logKOW = 3) which was found in greater quantities in the deepest samples, with increasing coarse silt content. Finally, a seasonal effect was also observed on pesticide levels, as their presence was highly driven by firstly their uses in the catchment and secondly by the soil erosion occurring during intense spring flood events. This work provides new knowledge on the role of ponds in pesticide storage, dissipation and transfer downstream, which can·be used for agricultural landscape management.

Published
2020
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4. Measurement and evaluation of the soil thermal parameters on the surface energy balance in an agricultural plot

Author

Aurore Brut, Odile De La Rue Du Can, Franck Granouillac, Bartosz Zawilski, Aaron Boone, Guylaine Canut, Marie Lothon, and Fabienne Lohou

Abstract

A precise estimation of the surface energy budget is a challenge to better understand, model and forecast both weather and climate, and their dependence on external constraints. However, in the micrometeorology community, it is already well known that the energy balance closure is an issue over many surfaces (Foken, 2008). Previous studies often focused on turbulent fluxes, effects of advection or time averaging for the flux calculation. This study is dedicated to evaluating the accuracy of the ground heat flux, thanks to a field experiment carried out on the ICOS site of Lamasquère (FR-Lam). Both the soil heat flux and storage are often difficult to precisely measure because thermal conductivity and heat capacity are strongly dependent on the very local soil texture (% clay, % sand, % organic matter) and water content. The experimental campaign is conducted over a wheat field from autumn 2021 to summer 2022, and heat pulse sensors are installed in various pits to measure thermal parameters (conductivity and heat capacity) at different depths within the ploughing crust. This device currently complements the operational measurements of temperature and soil water content profiles (sensors at 5, 10, 30, 50 and 100 cm), meteorological measurements and turbulent fluxes from an Eddy Covariance set-up. In a first step, we will present the results of the sensor measurements for the soil thermal parameters, their local dynamics in relation to the soil parameters, the vegetation development and the weather. Then, using these measurements and the temperature profiles in the soil, we will evaluate the accuracy of the ground heat flux in order to estimate its impact on the closure of the energy balance of vegetated surfaces. These results will be also compared to measurements from self-calibrated heat flux plate and the heat storage in the soil layer above the plate.

Published
2022

5. Calculation of soil water content using dielectric permittivity measurements; benefits of soil-specific calibration

Author

Bartosz Marian Zawilski, Franck Granouillac, Nicole Claverie, Baptiste Lemaire, Aurore Brut, and Tiphaine Tallec

Abstract

Soil Water Content (SWC) probes are widely used around the Earth for scientific and agricultural usage. Most of them are based on soil dielectric permittivity measurement as the dry soil relative dielectric permittivity ε, typically from 3 to 5, is much smaller than the water relative dielectric permittivity: about 80. The measure of dielectric permittivity in wet soils allows deducing the soil volumetric water content. Capacitance, Time Domain Reflectometry (TDR), Frequency Domain Reflectometry (FDR) and even remote sensing techniques such as Ground-Penetrating Radar (GPR) and microwave-based techniques are concerned. This study presents SWC measurements with commercial FDR probes on clayey soil highlighting the benefit of a meticulous soil-specific calibration although constructors indicate probes calibrated with generic constants as convenient. Locally, the use of the manufacturer’s transfer equation can lead to a strong overestimation or underestimation of the actual soil water content. A simple protocol for clayey soil calibration is proposed. Without soil-specific calibration on clayey soil, we observe errors as important as 115 % with a factory-calibrated probe based on the real part of the dielectric permittivity and up to 245 % with the factory-calibrated probes based on the modulus of the dielectric permittivity.

Published
2022

6. Dynamics of nitrous oxide emissions from two cropping systems in southwestern France over 5 years: Cross impact analysis of heterogeneous agricultural practices and local climate variability

Author

Tiphaine Tallec, Laurent Bigaignon, Claire Delon, Aurore Brut, Eric Ceschia, Patrick Mordelet, Bartosz Zawilski, Franck Granouillac, Nicole Claverie, Rémy Fieuzal, Baptiste Lemaire, Valérie Le Dantec, Centre d'études spatiales de la biosphère (CESBIO), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire d'aérologie (LAERO), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Observatoires de la zone critique - OZCAR (FRANCE), Aix-Marseille Université - Faculté de pharmacie (AMU PHARM), and Aix Marseille Université (AMU)

Subjects
Atmospheric Science, Global and Planetary Change, [SDE.MCG]Environmental Sciences/Global Changes, Forestry, Agronomy and Crop Science, Cover crop, Deep tillage, Residues, Water amount, Nitrogen use efficiency
Abstract

International audience; Nitrous oxide (N2O) emissions were measured and compared on 2 typical crop rotations of a grain farm and a dairy farm with feed cropping, over 5 years (from 2012 to 2016) in southwestern France. The annual N2O emissions of the 5 typical rotational crops of the region (summer crops: irrigated maize and sunflower; winter crops: winter wheat, rapeseed and barley) varied from 0.95 +/- 0.88 to 7.96 +/- 1.73 kgN ha-1, with the highest values observed on the dairy farm plot and for summer crops. N2O emissions were analysed on a daily, monthly, seasonal and annual basis, and correlated with their main direct or indirect drivers, i. e. water and nitrogen (mineral or organic) supply amount, rotational crops, vegetation covering and tillage. We observed a marked seasonal pattern of N2O emission peaks. On average, more than 50% of N2O emissions occurred during spring for summer crops, and more than 40% occurred in winter for winter crops. We have identified agricultural practices that increase N2O emissions. In particular, our results show that when the soil is left bare or with limited crop development, spring mineralization of organic N residues (from previous crop or winter cover crop) results in N losses, partly as emissions of N2O, which are detrimental to agronomic performance (low NUE).We also conducted an agronomic assessment of annual N2O emissions versus nitrogen surplus and nitrogen use efficiency (NUE), which lead us to discuss agricultural practices that may mitigate N2O emissions while optimizing agronomic and economic performance of crops. Indeed, we point out that N surplus and N fate may be controlled through the right timing of sowing, cover crop, irrigation and fertilization.

Published
2022

7. Spatial variation of denitrification and key controlling factors in streams and ponds sediments from a critical zone (southwestern France)

Author

Anne Probst, M Barret, Thierry Camboulive, Franck Granouillac, Virginie Payre-Suc, X Wu, Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
N2O flux, Denitrification, STREAMS, 010501 environmental sciences, 010502 geochemistry & geophysics, 01 natural sciences, Sediments, chemistry.chemical_compound, PDR, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Nitrate, Geochemistry and Petrology, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Environmental Chemistry, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, 0105 earth and related environmental sciences, Total organic carbon, Hydrology, Discharge, [SDE.IE]Environmental Sciences/Environmental Engineering, Sediment, Pollution, 6. Clean water, Constructed pond, Water quality, chemistry, Agricultural catchment, 13. Climate action, Environmental science, Spatial variability, NO3- Contamination, Denitrifiers
Abstract

International audience; Numerous ponds were constructed along streams for local water supply in agricultural areas of southwestern France. Although the water quality of streams and ponds has been surveyed for nitrate (NO 3 −), the role of ponds in NO 3 − mitigation at a catchment scale has rarely been investigated. Since denitrification in sediments is a key NO 3 − pathway, the denitrification variability in stream and pond sediments and its controlling factors, particularly the pond position and characteristics are important aspects to investigate. Potential denitrification rate (PDR), physico-chemical factors, and denitrification functional genes were quantified in sediments from nine ponds located in three adjacent agricultural catchments in spring period. PDR showed a great spatial variation (both horizontal and vertical) and was mainly driven by the availability of water NO 3 − and sediment organic carbon. Stream discharge and pond hydraulic retention time can also affect PDR in stream and pond sediments, respectively. Although high PDR was observed in stream sediments, stream discharge diluted NO 3 − and can indirectly lower PDR downstream. The function of denitrifiers was revealed by the abundance ratio of nirK/16S rRNA, but no significant relationship was found between PDR and abundance of functional genes. N 2 O emission rate was positively related to PDR, which should be aware of in the upstream PDR hotspot ponds. Simple empirical models based on pond and sediment characteristics were good predictors of PDR, which could also help a better management of ponds by policy makers with the aim to improve NO 3 − mitigation and water quality.

Published
2021

8. Pesticide Distribution in Pond Sediments from an Agricultural Catchment (Auradé, SW France)

Author

Corinne Pautot, Thierry Camboulive, Benjamin Trochon, Marie-Josée Tavella, Franck Granouillac, Jean-Luc Probst, Virginie Payre-Suc, David Riboul, Betty Chaumet, Anne Probst, Pierre Eon, Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), LTSER ZA PYRenees GARonne, and Centre National de la Recherche Scientifique (CNRS)

Subjects
Hydrology, geography, geography.geographical_feature_category, spatial distribution, fungi, agricultural catchment, Sediment, Wetland, pesticides, Pesticide, Crop rotation, storage, bottom sediments, Water column, Granulometry, parasitic diseases, Environmental science, Spatial variability, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Quadrat
Abstract

International audience; Currently, pesticides are massively used in agricultural areas end up in watercourses, as they are usually final receptacles of organic contamination. A large number of wetlands such as ponds occurred in agricultural catchments. They are dynamic and complex systems which contains different compartments like the water column, sediments and biota. The sediment compartment can store contaminants according to their physicochemical properties, but this process is continuously challenged because of settling and resuspension mechanisms. The role of the sediments regarding pesticides behavior and their fate is still poorly investigated. Our study aimed to fill this gap, particularly considering the Bassioué pond, which is located in the carbonated agricultural upper sub-catchment of the Auradé critical zone observatory (Gers, France), with a wheat/sunflower crop rotation and a steep slope enhancing erosion phenomenon. We focused on pesticide storage in the sediments which represent the main compartment due to the environmental conditions. Our current objective was to understand (i) how and where pesticides are stored in the sediments, and (ii) the relationship with the characteristics of sediments, supposed to be highly involved in the storage and degradation of pesticides. Two field campaigns were carried out to collect sediment samples within a regular quadrat from the inlet to the outlet of the pond in autumn 2019 and summer 2020 at different depth. A set of three pesticide was quantified as well as sediment texture. The results highlighted that sediment particle size distribution varied between upstream and downstream of the pond: from the finest to the coarsest; as did the spatial distribution of pesticides. This reveled that pesticides were partly controlled by their physicochemical properties: most hydrophilic pesticides had greater affinity with the finest fractions of the sediments. A difference in pesticide storage according to the depth has been observed, especially for boscalid (logK OW = 3) which was found in greater quantities in the deepest samples, with increasing coarse silt content. Finally, a seasonal effect was also observed on pesticide levels, as their presence was highly driven by firstly their uses in the catchment and secondly by the soil erosion occurring during intense spring flood events. This work provides new knowledge on the role of ponds in pesticide storage, dissipation and transfer downstream, which can•be used for agricultural landscape management.

Published
2020

9. Role of Pond Sediments for Trapping Pesticides in an Agricultural Catchment (Auradé, SW France): Distribution and Controlling Factors

Author

Virginie Payre, Thierry Camboulive, Franck Granouillac, Jean-Luc Probst, Betty Chaumet, Anne Probst, Pierre Eon, David Riboul, Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Observatoires de la zone critique - OZCAR (FRANCE), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université Fédérale Toulouse Midi-Pyrénées

Subjects
010504 meteorology & atmospheric sciences, Geography, Planning and Development, Drainage basin, Partition coefficients, Wetland, 010501 environmental sciences, Aquatic Science, Ecotoxicologie, Spatial distribution, 01 natural sciences, Biochemistry, Metolachlor, chemistry.chemical_compound, Tebuconazole, Seasonality effect, TD201-500, Hydrologie, 0105 earth and related environmental sciences, Water Science and Technology, Hydrology, geography, geography.geographical_feature_category, Water supply for domestic and industrial purposes, business.industry, Aquatic ecosystem, Sediment, Hydraulic engineering, Particle size, Pesticide, 6. Clean water, chemistry, 13. Climate action, Agriculture, Bottom sediments, Sorption, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, TC1-978, Boscalid, business
Abstract

In agricultural areas, ponds are suitable wetland environments to dissipate and reduce the occurrence of pesticides in aquatic environments. However, their impact at a catchment scale is still poorly understood. This study aims to determine how these organic contaminants were trapped in a pond located in an agricultural critical zone from SW France (Auradé catchment). The spatial distribution of pesticide concentrations and their different controlling factors were investigated in waters and sediments collected during two distinct seasons. The results highlighted (i) the link between the presence of the molecules and the agricultural practices upstream, (ii) the influence of hydrological/seasonal conditions, especially on hydrophobic molecule accumulation such as tebuconazole, (iii) the key role of clay content in sediments on the control of moderately hydrophilic pesticides (metolachlor and boscalid), but also the unexpected role of coarse particles for boscalid, and (iv) the influence of sediment depth on pesticide storage. Nevertheless, other physico-chemical parameters, such as mineralogical composition of sediment, needed to be considered to explain the pesticide patterns. This study brings a new hypothesis to be investigated in the future about pesticide behaviour in such pond environments.

Published
2021

10. Long and short-term trends of stream hydrochemistry and high frequency surveys as indicators of the influence of climate change, agricultural practices and internal processes (Aurade agricultural catchment, SW France)

Author

Anne-Sophie Perrin, Jean-Luc Probst, Sylvain Ferrant, Franck Granouillac, Vivien Ponnou-Delaffon, Virginie Payre-Suc, Anne Probst, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Centre d'études spatiales de la biosphère (CESBIO), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - INPT (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)

Subjects
0106 biological sciences, Hydrological conditions, Biodiversité et Ecologie, Hydrochemical indicators, General Decision Sciences, Climate change, 010501 environmental sciences, 010603 evolutionary biology, 01 natural sciences, Major elements trends, chemistry.chemical_compound, Hydrology (agriculture), Nitrate, High frequency, Evapotranspiration, Dissolved organic carbon, Precipitation, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, 2. Zero hunger, Hydrology, Nitrates, Ecology, Vegetation, 15. Life on land, 6. Clean water, Critical Zone, chemistry, Nycthemeral cycle, 13. Climate action, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Surface runoff
Abstract

International audience; The hydrochemical time series of stream water from a cultivated catchment were investigated at different time scales and survey frequencies. A 35-year time series of nitrate concentration and discharge, a 15-year time series of major elements and dissolved organic carbon (DOC) concentrations were analysed from a yearly to a daily/hourly basis during discharge recession after storm event periods, to determine the origin of elements, the time trends and the main controlling factors of the trends. A significant decrease over time of nitrate, base cations and other major anions was observed. These trends were controlled by agricultural practice changes (decrease of N-fertiliser input, grass-band set up) and discharge increase, especially in the last years of the period. On the other hand, K and DOC increased over the 15-year period. This increase might result from both 1) organic matter eroded from the soil surface by runoff during flood events and 2) an increase in mineralisation with increasing temperature. Seasonal variations and nycthemeral cycles indicated either calcite precipitation and nitrification processes and/or evapotranspiration, water and/or vegetation uptake during the day with increasing temperature. This paper highlights that the hydrochemical parameters measured at various time scales and frequencies can be used as powerful indicators of catchment internal processes, and of changes in agricultural management and climate change. Particularly, the multivariate high-resolution survey has shown its ability to evidence very tenuous processes not detectable by discrete sampling. The recent observed changes in hydrology argue for the need to continue the hydrochemical survey over decades.

Published
2019

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