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Thème 2
Post doc
My research interests are anthropic impacts on water resources and water cycle in general. During my PhD I focused on anthropised coastal aquifers, and during the last 3 years and my coming-back to academic, I have added to this a new theme: climate change impacts on water dynamics and resources in glacierised catchments. I always combine collection of data on the field to numerical modelling. I also collaborate with social scientists.
Post doctorante - Hydrogéologie quantitative, hydrologie
PUBLICATIONS
Articles de journaux |
Cousquer, Yohann; Pryet, Alexandre; Delbart, Célestine; Valois, Rémi; Dupuy, Alain Adaptive optimization of a vulnerable well field Article de journal Hydrogeology Journal, 2019, ISSN: 1435-0157. @article{Cousqueretal2019, title = {Adaptive optimization of a vulnerable well field}, author = {Yohann Cousquer and Alexandre Pryet and C\'{e}lestine Delbart and R\'{e}mi Valois and Alain Dupuy}, url = {https://doi.org/10.1007/s10040-019-01963-8}, doi = {10.1007/s10040-019-01963-8}, issn = {1435-0157}, year = {2019}, date = {2019-03-26}, journal = {Hydrogeology Journal}, abstract = {The contamination of groundwater resources is a challenge for drinking water supplies. To meet water quality standards, well-field operators need practical solutions to reduce the vulnerability of production wells. Strategies for several combinations of management variables such as well flow rate or water level in drains, are usually possible to satisfy the required production rate. However, these strategies may lead to contamination issues for the abstracted groundwater. A surrogate transport model was implemented in a well field vulnerable to a contaminated stream. An adaptive multi-objective optimization approach is proposed. The objective is to maximize the water production at the well field while minimizing the proportion of stream water abstracted. The optimization problem is adaptive to the stream level, which is a key parameter describing hydrological conditions. A systematic exploration of management settings is conducted and a three-dimensional Pareto front is extracted. From these optimum settings, a practical easy-to-use approach is developed. The well-field operator can adjust production settings to optimum conditions as a function of the observed stream water level and desired production rate.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The contamination of groundwater resources is a challenge for drinking water supplies. To meet water quality standards, well-field operators need practical solutions to reduce the vulnerability of production wells. Strategies for several combinations of management variables such as well flow rate or water level in drains, are usually possible to satisfy the required production rate. However, these strategies may lead to contamination issues for the abstracted groundwater. A surrogate transport model was implemented in a well field vulnerable to a contaminated stream. An adaptive multi-objective optimization approach is proposed. The objective is to maximize the water production at the well field while minimizing the proportion of stream water abstracted. The optimization problem is adaptive to the stream level, which is a key parameter describing hydrological conditions. A systematic exploration of management settings is conducted and a three-dimensional Pareto front is extracted. From these optimum settings, a practical easy-to-use approach is developed. The well-field operator can adjust production settings to optimum conditions as a function of the observed stream water level and desired production rate. |
Pereau, Jean-Christophe; Pryet, Alexandre; Rambonilaza, Tina Optimality Versus Viability in Groundwater Management with Environmental Flows Article de journal Ecological Economics, 161 , p. 109 - 120, 2019, ISSN: 0921-8009. @article{Pereauetal2019, title = {Optimality Versus Viability in Groundwater Management with Environmental Flows}, author = {Jean-Christophe Pereau and Alexandre Pryet and Tina Rambonilaza}, url = {http://www.sciencedirect.com/science/article/pii/S0921800918318615}, doi = {https://doi.org/10.1016/j.ecolecon.2019.03.018}, issn = {0921-8009}, year = {2019}, date = {2019-01-01}, journal = {Ecological Economics}, volume = {161}, pages = {109 - 120}, abstract = {The protection of environmental flows is a main challenge pursued by water regulating agencies in their groundwater management policies. A stylised hydro-economic model with natural drainage is used to compare the outcome of the optimal control approach in which environmental flows are introduced as an externality with the viable approach in which environmental flows are modelled as a constraint to satisfy. The optimal and viable paths for the water table, water extraction for irrigation and environmental flows are analytically derived together with their long-term values. We show how results are sensitive to some key parameters like the discount factor and the monetary value of the externality in the optimal control approach. We show how the value of the environmental flows target in the viable approach can be derived from the optimal control approach. Numerical simulations based on the Western La Mancha aquifer illustrate the main results of the study.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The protection of environmental flows is a main challenge pursued by water regulating agencies in their groundwater management policies. A stylised hydro-economic model with natural drainage is used to compare the outcome of the optimal control approach in which environmental flows are introduced as an externality with the viable approach in which environmental flows are modelled as a constraint to satisfy. The optimal and viable paths for the water table, water extraction for irrigation and environmental flows are analytically derived together with their long-term values. We show how results are sensitive to some key parameters like the discount factor and the monetary value of the externality in the optimal control approach. We show how the value of the environmental flows target in the viable approach can be derived from the optimal control approach. Numerical simulations based on the Western La Mancha aquifer illustrate the main results of the study. |
Goff, Le J; Reijmer, J J G; Cerepi, A; Loisy, C; Swennen, R; Heba, G; Cavailhes, T; Graaf, De S The dismantling of the Apulian carbonate platform during the late Campanian – early Maastrichtian in Albania Article de journal Cretaceous Research, 96 , p. 83–106, 2019, ISSN: 0195-6671. @article{LEGOFF201983, title = {The dismantling of the Apulian carbonate platform during the late Campanian \textendash early Maastrichtian in Albania}, author = {Le J Goff and J J G Reijmer and A Cerepi and C Loisy and R Swennen and G Heba and T Cavailhes and De S Graaf}, url = {http://www.sciencedirect.com/science/article/pii/S0195667118300508}, doi = {https://doi.org/10.1016/j.cretres.2018.11.013}, issn = {0195-6671}, year = {2019}, date = {2019-01-01}, journal = {Cretaceous Research}, volume = {96}, pages = {83--106}, abstract = {The Apulian carbonate margin is widely preserved across the Adriatic domain and has been extensively studied in the south of Italy. In Albania, Oligocene\textendashPliocene fold-and-thrust tectonics led to widespread exposure of the Apulian Platform and associated Ionian Basin carbonates. However, the portion linking the platform to the basin is missing, preventing a direct reconstruction of the platform margin. Syn-sedimentary folding and faulting are recognized in the uppermost part of both the platform and basinal/slope series. Mass transport deposits (MTDs) occur within the platform succession incorporated into well-bedded intertidal (stromatolites) to shallow-subtidal (rudist packstones) sedimentary sequences. They display significant lateral variability which is accompanied by both rigid and soft deformation structures. Spectacular slumps made up of sediment density flow deposits are recognized in the adjacent Ionian Basin. The lateral extent of basal shear surfaces, syn-sedimentary faults and folds evidenced in the Ionian Basin points toward multiple regional tectonic triggering events affecting the Apulian Platform margin at that time. Bio- and chrono-stratigraphic analyses suggest that the triggers occurred during the late Campanian \textendash early Maastrichtian. Beyond the obvious interest from a stratigraphic point of view, the study of these events recording the dismantling of the Apulian carbonate platform allows for a better understanding of the triggering mechanisms and the sedimentary characteristics of MTDs and slumps at a basinal scale.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The Apulian carbonate margin is widely preserved across the Adriatic domain and has been extensively studied in the south of Italy. In Albania, Oligocene–Pliocene fold-and-thrust tectonics led to widespread exposure of the Apulian Platform and associated Ionian Basin carbonates. However, the portion linking the platform to the basin is missing, preventing a direct reconstruction of the platform margin. Syn-sedimentary folding and faulting are recognized in the uppermost part of both the platform and basinal/slope series. Mass transport deposits (MTDs) occur within the platform succession incorporated into well-bedded intertidal (stromatolites) to shallow-subtidal (rudist packstones) sedimentary sequences. They display significant lateral variability which is accompanied by both rigid and soft deformation structures. Spectacular slumps made up of sediment density flow deposits are recognized in the adjacent Ionian Basin. The lateral extent of basal shear surfaces, syn-sedimentary faults and folds evidenced in the Ionian Basin points toward multiple regional tectonic triggering events affecting the Apulian Platform margin at that time. Bio- and chrono-stratigraphic analyses suggest that the triggers occurred during the late Campanian – early Maastrichtian. Beyond the obvious interest from a stratigraphic point of view, the study of these events recording the dismantling of the Apulian carbonate platform allows for a better understanding of the triggering mechanisms and the sedimentary characteristics of MTDs and slumps at a basinal scale. |
Vincent, Aude; Violette, Sophie; Aðalgeirsdóttir, Guðfinna Groundwater in catchments headed by temperate glaciers: a review Article de journal Earth-Science Reviews, 2018. @article{vincent_groundwater_2018, title = {Groundwater in catchments headed by temperate glaciers: a review}, author = {Aude Vincent and Sophie Violette and Gu\~{A}°finna A\~{A}°algeirsd\~{A}³ttir}, year = {2018}, date = {2018-01-01}, journal = {Earth-Science Reviews}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Cousquer, Y; Pryet, A; Atteia, O; Ferré, T P A; Delbart, C; Valois, R; Dupuy, A Developing a particle tracking surrogate model to improve inversion of ground water – Surface water models Article de journal Journal of Hydrology, 558 , p. 356–365, 2018. @article{Cousqueretal2018, title = {Developing a particle tracking surrogate model to improve inversion of ground water \textendash Surface water models}, author = {Y Cousquer and A Pryet and O Atteia and T P A Ferr\'{e} and C Delbart and R Valois and A Dupuy}, url = {http://www.sciencedirect.com/science/article/pii/S0022169418300507}, doi = {10.1016/j.jhydrol.2018.01.043}, year = {2018}, date = {2018-01-01}, journal = {Journal of Hydrology}, volume = {558}, pages = {356--365}, abstract = {textcopyright 2018 Elsevier B.V. The inverse problem of groundwater models is often ill-posed and model parameters are likely to be poorly constrained. Identifiability is improved if diverse data types are used for parameter estimation. However, some models, including detailed solute transport models, are further limited by prohibitive computation times. This often precludes the use of concentration data for parameter estimation, even if those data are available. In the case of surface water-groundwater (SW-GW) models, concentration data can provide SW-GW mixing ratios, which efficiently constrain the estimate of exchange flow, but are rarely used. We propose to reduce computational limits by simulating SW-GW exchange at a sink (well or drain) based on particle tracking under steady state flow conditions. Particle tracking is used to simulate advective transport. A comparison between the particle tracking surrogate model and an advective\textendashdispersive model shows that dispersion can often be neglected when the mixing ratio is computed for a sink, allowing for use of the particle tracking surrogate model. The surrogate model was implemented to solve the inverse problem for a real SW-GW transport problem with heads and concentrations combined in a weighted hybrid objective function. The resulting inversion showed markedly reduced uncertainty in the transmissivity field compared to calibration on head data alone.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018 Elsevier B.V. The inverse problem of groundwater models is often ill-posed and model parameters are likely to be poorly constrained. Identifiability is improved if diverse data types are used for parameter estimation. However, some models, including detailed solute transport models, are further limited by prohibitive computation times. This often precludes the use of concentration data for parameter estimation, even if those data are available. In the case of surface water-groundwater (SW-GW) models, concentration data can provide SW-GW mixing ratios, which efficiently constrain the estimate of exchange flow, but are rarely used. We propose to reduce computational limits by simulating SW-GW exchange at a sink (well or drain) based on particle tracking under steady state flow conditions. Particle tracking is used to simulate advective transport. A comparison between the particle tracking surrogate model and an advective–dispersive model shows that dispersion can often be neglected when the mixing ratio is computed for a sink, allowing for use of the particle tracking surrogate model. The surrogate model was implemented to solve the inverse problem for a real SW-GW transport problem with heads and concentrations combined in a weighted hybrid objective function. The resulting inversion showed markedly reduced uncertainty in the transmissivity field compared to calibration on head data alone. |
Delottier, H; Pryet, A; Lemieux, J M; Dupuy, A Estimating groundwater recharge uncertainty from joint application of an aquifer test and the water-table fluctuation method Article de journal Hydrogeology Journal, 26 (7), p. 2495–2505, 2018. @article{Delottieretal2018, title = {Estimating groundwater recharge uncertainty from joint application of an aquifer test and the water-table fluctuation method}, author = {H Delottier and A Pryet and J M Lemieux and A Dupuy}, url = {https://doi.org/10.1007/s10040-018-1790-6}, doi = {10.1007/s10040-018-1790-6}, year = {2018}, date = {2018-01-01}, journal = {Hydrogeology Journal}, volume = {26}, number = {7}, pages = {2495--2505}, abstract = {textcopyright 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Specific yield and groundwater recharge of unconfined aquifers are both essential parameters for groundwater modeling and sustainable groundwater development, yet the collection of reliable estimates of these parameters remains challenging. Here, a joint approach combining an aquifer test with application of the water-table fluctuation (WTF) method is presented to estimate these parameters and quantify their uncertainty. The approach requires two wells: an observation well instrumented with a pressure probe for long-term monitoring and a pumping well, located in the vicinity, for the aquifer test. The derivative of observed drawdown levels highlights the necessity to represent delayed drainage from the unsaturated zone when interpreting the aquifer test results. Groundwater recharge is estimated with an event-based WTF method in order to minimize the transient effects of flow dynamics in the unsaturated zone. The uncertainty on groundwater recharge is obtained by the propagation of the uncertainties on specific yield (Bayesian inference) and groundwater recession dynamics (regression analysis) through the WTF equation. A major portion of the uncertainty on groundwater recharge originates from the uncertainty on the specific yield. The approach was applied to a site in Bordeaux (France). Groundwater recharge was estimated to be 335 mm with an associated uncertainty of 86.6 mm at 2$sigma$. By the use of cost-effective instrumentation and parsimonious methods of interpretation, the replication of such a joint approach should be encouraged to provide reliable estimates of specific yield and groundwater recharge over a region of interest. This is necessary to reduce the predictive uncertainty of groundwater management models.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Specific yield and groundwater recharge of unconfined aquifers are both essential parameters for groundwater modeling and sustainable groundwater development, yet the collection of reliable estimates of these parameters remains challenging. Here, a joint approach combining an aquifer test with application of the water-table fluctuation (WTF) method is presented to estimate these parameters and quantify their uncertainty. The approach requires two wells: an observation well instrumented with a pressure probe for long-term monitoring and a pumping well, located in the vicinity, for the aquifer test. The derivative of observed drawdown levels highlights the necessity to represent delayed drainage from the unsaturated zone when interpreting the aquifer test results. Groundwater recharge is estimated with an event-based WTF method in order to minimize the transient effects of flow dynamics in the unsaturated zone. The uncertainty on groundwater recharge is obtained by the propagation of the uncertainties on specific yield (Bayesian inference) and groundwater recession dynamics (regression analysis) through the WTF equation. A major portion of the uncertainty on groundwater recharge originates from the uncertainty on the specific yield. The approach was applied to a site in Bordeaux (France). Groundwater recharge was estimated to be 335 mm with an associated uncertainty of 86.6 mm at 2$sigma$. By the use of cost-effective instrumentation and parsimonious methods of interpretation, the replication of such a joint approach should be encouraged to provide reliable estimates of specific yield and groundwater recharge over a region of interest. This is necessary to reduce the predictive uncertainty of groundwater management models. |
Pereau, Jean Christophe; Pryet, Alexandre Environmental flows in hydro-economic models Article de journal Hydrogeology Journal, 26 (7), p. 2205–2212, 2018, ISSN: 14350157. @article{PereauandPryet2018, title = {Environmental flows in hydro-economic models}, author = {Jean Christophe Pereau and Alexandre Pryet}, url = {https://doi.org/10.1007/s10040-018-1765-7}, doi = {10.1007/s10040-018-1765-7}, issn = {14350157}, year = {2018}, date = {2018-01-01}, journal = {Hydrogeology Journal}, volume = {26}, number = {7}, pages = {2205--2212}, abstract = {The protection ofenvironmental flows, as a management objective for a regulating agency, needs to be consistent with the aquifer water balance and the degree ofresource renewability. A stylized hydro-economic model is used where natural recharge, which sustains environmental flows, is considered both in the aquifer water budget and in the welfare function as ecosystem damage. Groundwater recharge and the associated natural drainage may be neglected for aquifers containing fossil water, where the groundwater is mined. However, when dealing with an aquifer that constitutes a renewable resource, for which recharge is not negligible, natural drainage should explicitly appear in the water budget. In doing so, the optimum path ofnet extraction rate does not necessarily converge to the recharge rate, but depends on the costs associated with ecosystemdamages. The optimal paths and equilibrium values for the water volume and water extraction are analytically derived, and numerical simulations based on the Western La Mancha aquifer (southwest Spain) illustrate the theoretical results of the study.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The protection ofenvironmental flows, as a management objective for a regulating agency, needs to be consistent with the aquifer water balance and the degree ofresource renewability. A stylized hydro-economic model is used where natural recharge, which sustains environmental flows, is considered both in the aquifer water budget and in the welfare function as ecosystem damage. Groundwater recharge and the associated natural drainage may be neglected for aquifers containing fossil water, where the groundwater is mined. However, when dealing with an aquifer that constitutes a renewable resource, for which recharge is not negligible, natural drainage should explicitly appear in the water budget. In doing so, the optimum path ofnet extraction rate does not necessarily converge to the recharge rate, but depends on the costs associated with ecosystemdamages. The optimal paths and equilibrium values for the water volume and water extraction are analytically derived, and numerical simulations based on the Western La Mancha aquifer (southwest Spain) illustrate the theoretical results of the study. |
Dumont, M; Reninger, P A; Pryet, A; Martelet, G; Aunay, B; Join, J L Agglomerative hierarchical clustering of airborne electromagnetic data for multi-scale geological studies Article de journal Journal of Applied Geophysics, 157 , p. 1–9, 2018. @article{Dumontetal2018, title = {Agglomerative hierarchical clustering of airborne electromagnetic data for multi-scale geological studies}, author = {M Dumont and P A Reninger and A Pryet and G Martelet and B Aunay and J L Join}, url = {http://www.sciencedirect.com/science/article/pii/S0926985117301891}, doi = {10.1016/j.jappgeo.2018.06.020}, year = {2018}, date = {2018-01-01}, journal = {Journal of Applied Geophysics}, volume = {157}, pages = {1--9}, abstract = {textcopyright 2018 Elsevier B.V. Airborne electromagnetic methods provide detailed subsurface resistivity imaging over extensive areas. The inversion of electromagnetic measurements can be conducted with a quasi-3D spatially constrained inversion scheme, which yields numerous vertical resistivity soundings. So as to conduct the interpretation, these soundings can be interpolated to obtain a 3D resistivity model. However, large surveys result in huge resistivity models, which can be challenging to interpret with 2D or even 3D views. We propose a complementary approach for the interpretation of airborne electromagnetic surveys based on agglomerative hierarchical clustering. With this statistical classification method, the numerous 1D vertical resistivity profiles distributed over the area of interest can be summarized in a 2D horizontal map. Inverted electromagnetic soundings are aggregated into clusters according to their vertical resistivity profiles. These clusters define areas with a consistent vertical resistivity response, i.e. to the first order, areas with comparable vertical (hydro)-geological structure. The clustering method is illustrated with an extensive airborne electromagnetic survey conducted over Reunion Island. After a description of the method, we show that the proposed classification facilitates the confrontation between airborne geophysical results and geological or hydrogeological observations/data. We highlight that hierarchical clustering is of high interest for multi-scale studies, from regional to local scales. This approach introduces a new way to use geophysical surveys to map areas with specific geological/hydrogeological behaviors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018 Elsevier B.V. Airborne electromagnetic methods provide detailed subsurface resistivity imaging over extensive areas. The inversion of electromagnetic measurements can be conducted with a quasi-3D spatially constrained inversion scheme, which yields numerous vertical resistivity soundings. So as to conduct the interpretation, these soundings can be interpolated to obtain a 3D resistivity model. However, large surveys result in huge resistivity models, which can be challenging to interpret with 2D or even 3D views. We propose a complementary approach for the interpretation of airborne electromagnetic surveys based on agglomerative hierarchical clustering. With this statistical classification method, the numerous 1D vertical resistivity profiles distributed over the area of interest can be summarized in a 2D horizontal map. Inverted electromagnetic soundings are aggregated into clusters according to their vertical resistivity profiles. These clusters define areas with a consistent vertical resistivity response, i.e. to the first order, areas with comparable vertical (hydro)-geological structure. The clustering method is illustrated with an extensive airborne electromagnetic survey conducted over Reunion Island. After a description of the method, we show that the proposed classification facilitates the confrontation between airborne geophysical results and geological or hydrogeological observations/data. We highlight that hierarchical clustering is of high interest for multi-scale studies, from regional to local scales. This approach introduces a new way to use geophysical surveys to map areas with specific geological/hydrogeological behaviors. |
Le Gall, B; Leleu, S; Pik, R; Jourdan, F; Chazot, G; Ayalew, D; Yirgu, G; Cloquet, C; Chauvet, F The Red Beds series in the Erta Ale segment, North Afar. Evidence for a 6 Ma-old post-rift basin prior to continental rupturing Article de journal Tectonophysics, 2018, ISSN: 00401951. @article{LeGall2018, title = {The Red Beds series in the Erta Ale segment, North Afar. Evidence for a 6 Ma-old post-rift basin prior to continental rupturing}, author = {B {Le Gall} and S Leleu and R Pik and F Jourdan and G Chazot and D Ayalew and G Yirgu and C Cloquet and F Chauvet}, doi = {10.1016/j.tecto.2018.10.002}, issn = {00401951}, year = {2018}, date = {2018-01-01}, journal = {Tectonophysics}, abstract = {The Erta Ale rift segment, North Afar, is regarded as the most mature rift part within the entire Afar rift system. Very little is known about its deformation history because of limited exposures of geological records in its inner floor, except volcanics of the Erta Ale chain, and the poorly-known Red Beds series along the flanks of the depression. An integrated study, combining sedimentological, geochemical, 40Ar-39Ar radiometric and tectonic approaches, has been devoted to Red Beds series flanking the depression to the SW. Our new results allow to argue that (1) the textgreater300 m-thick Red Beds exposed section comprises alluvial deposits that enclose (2) basaltic lavas and related sill intrusions that both yield ~6 Ma 40Ar-39Ar ages and display similar geochemical affinities, (3) the Red Beds series locally overlap unconformably basement bounding terrains, and (4) are involved in a limited number of low-displacement normal faults that recorded a modest amount of extension (textless6%), (5) isotope contents of Red Beds volcanics indicate crustal contamination, without any contribution of the Afar plume, by contrast to the younger Erta Ale magmatism which represents the more recent Afar-plume related event in the Erta Ale segment. Combining these results leads us to regard the Red Beds series as part of an alluvial basin that post-dated a major rift event to which are attributed to (1) the present-day Ethiopian fault-scarp, (2) a concealed sedimentary depocenter at depth in its hanging wall, and (3) prominent crustal thinning. Riftward migration and axial focusing of strain during Miocene-Present times is also argued, while later flexuring of the entire Red Beds basin is assigned to magmatic loading during the axial emplacement of the Erta Ale volcanic chain. Lastly, emphasis is put on the large-scale segmentation of the Afar system into the tectonically-accreted Erta Ale rift segment to the north, and the magmatically-accreted Central segment to the south.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The Erta Ale rift segment, North Afar, is regarded as the most mature rift part within the entire Afar rift system. Very little is known about its deformation history because of limited exposures of geological records in its inner floor, except volcanics of the Erta Ale chain, and the poorly-known Red Beds series along the flanks of the depression. An integrated study, combining sedimentological, geochemical, 40Ar-39Ar radiometric and tectonic approaches, has been devoted to Red Beds series flanking the depression to the SW. Our new results allow to argue that (1) the textgreater300 m-thick Red Beds exposed section comprises alluvial deposits that enclose (2) basaltic lavas and related sill intrusions that both yield ~6 Ma 40Ar-39Ar ages and display similar geochemical affinities, (3) the Red Beds series locally overlap unconformably basement bounding terrains, and (4) are involved in a limited number of low-displacement normal faults that recorded a modest amount of extension (textless6%), (5) isotope contents of Red Beds volcanics indicate crustal contamination, without any contribution of the Afar plume, by contrast to the younger Erta Ale magmatism which represents the more recent Afar-plume related event in the Erta Ale segment. Combining these results leads us to regard the Red Beds series as part of an alluvial basin that post-dated a major rift event to which are attributed to (1) the present-day Ethiopian fault-scarp, (2) a concealed sedimentary depocenter at depth in its hanging wall, and (3) prominent crustal thinning. Riftward migration and axial focusing of strain during Miocene-Present times is also argued, while later flexuring of the entire Red Beds basin is assigned to magmatic loading during the axial emplacement of the Erta Ale volcanic chain. Lastly, emphasis is put on the large-scale segmentation of the Afar system into the tectonically-accreted Erta Ale rift segment to the north, and the magmatically-accreted Central segment to the south. |
Faucher, Stéphane; ë, Ga; Lützen, Elias; Coustumer, Philippe Le; Schaumlöffel, Dirk; Sivry, Yann; ë, Ga Analytica Chimica Acta, 1028 , p. 104–112, 2018, ISSN: 0003-2670. @article{FAUCHER2018104, title = {Characterization of polymer-coated CdSe/ZnS quantum dots and investigation of their behaviour in soil solution at relevant concentration by asymmetric flow field-flow fractionation \textendash multi angle light scattering \textendash inductively coupled plasma - mass spectro}, author = {St\'{e}phane Faucher and Ga{\"{e}}lle Charron and Elias L\"{u}tzen and Philippe Le Coustumer and Dirk Schauml\"{o}ffel and Yann Sivry and Ga{\"{e}}tane Lespes}, url = {http://www.sciencedirect.com/science/article/pii/S0003267018304306}, doi = {https://doi.org/10.1016/j.aca.2018.03.051}, issn = {0003-2670}, year = {2018}, date = {2018-01-01}, journal = {Analytica Chimica Acta}, volume = {1028}, pages = {104--112}, abstract = {A careful separation, identification and characterization of polymer-coated quantum dots (P-QDs) in complex media such as soil solution is the key point to understand their behaviour and to accurately predict their fate in the environment. In the present study, a synthesized CdSe/ZnS core/shell P-QDs suspension, proved to be stable for at least six months, was investigated with respect to P-QDs dimension, structure and elemental composition. Separation of P-QDs and size distribution determination were carried out by Asymmetric Flow Field-Flow Fractionation (AF4) - Multi Angle Light Scattering (MALS). AF4 and MALS were coupled to Inductively Coupled Plasma-Mass Spectrometry (ICPMS) as a selective and sensitive technique for the detection and the characterization of metallic and metalloid analytes. The exploration of element-specific data obtained by ICPMS after AF4 separation enabled the signal to be deconvoluted reliably. Thus, 3 classes of size populations were identified from the whole population of P-QDs. Additionally, a soil solution and a mix of P-QDs suspension with soil solution were characterized by the same method. This strategy enabled the P-QD population, which interacted with the soil solution, to be determined, this interaction leading either to an aggregation or dissolution of the P-QDs. Reproducibility and recovery of the size distributions and element concentrations were examined for each sample. Complementarily, Dynamic Light Scattering (DLS) and Scanning Transmission Electron Microscopy (STEM) were used jointly with AF4-MALS-ICPMS in order to demonstrate all potentialities of this coupling technique.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A careful separation, identification and characterization of polymer-coated quantum dots (P-QDs) in complex media such as soil solution is the key point to understand their behaviour and to accurately predict their fate in the environment. In the present study, a synthesized CdSe/ZnS core/shell P-QDs suspension, proved to be stable for at least six months, was investigated with respect to P-QDs dimension, structure and elemental composition. Separation of P-QDs and size distribution determination were carried out by Asymmetric Flow Field-Flow Fractionation (AF4) - Multi Angle Light Scattering (MALS). AF4 and MALS were coupled to Inductively Coupled Plasma-Mass Spectrometry (ICPMS) as a selective and sensitive technique for the detection and the characterization of metallic and metalloid analytes. The exploration of element-specific data obtained by ICPMS after AF4 separation enabled the signal to be deconvoluted reliably. Thus, 3 classes of size populations were identified from the whole population of P-QDs. Additionally, a soil solution and a mix of P-QDs suspension with soil solution were characterized by the same method. This strategy enabled the P-QD population, which interacted with the soil solution, to be determined, this interaction leading either to an aggregation or dissolution of the P-QDs. Reproducibility and recovery of the size distributions and element concentrations were examined for each sample. Complementarily, Dynamic Light Scattering (DLS) and Scanning Transmission Electron Microscopy (STEM) were used jointly with AF4-MALS-ICPMS in order to demonstrate all potentialities of this coupling technique. |
Guignabert, Arthur; Delerue, Florian; Gonzalez, Maya; Augusto, Laurent; Bakker, Mark R Effects of management practices and topography on ectomycorrhizal fungi of maritime pine during seedling recruitment Article de journal Forests, 2018, ISSN: 19994907. @article{Guignabert2018, title = {Effects of management practices and topography on ectomycorrhizal fungi of maritime pine during seedling recruitment}, author = {Arthur Guignabert and Florian Delerue and Maya Gonzalez and Laurent Augusto and Mark R Bakker}, doi = {10.3390/f9050245}, issn = {19994907}, year = {2018}, date = {2018-01-01}, journal = {Forests}, abstract = {Symbiosis with ectomycorrhizal (ECM) fungi can be important for regeneration success. In a context of increasing regeneration failures in the coastal forest of maritime pine in Southwest France, we tried to identity whether differences in ECM communities could partly explain the variation of regeneration success and how they are influenced by forest practices and stand characteristics. In particular, we focused on the effects of harvesting methods (comparing mature forest with seed-tree regeneration and clear-cuts) and topography (bottom-, mid-, and top positions). Five field trials (two in regeneration failure areas and three in successful areas) were used to sample 450 one-year-old seedlings. Assessments of ECM of seedling nutrient concentrations and of seedling growth based on exploration types were made. ECM root colonisation was similar in all harvesting treatments, suggesting that enough inoculum remained alive after logging. Harvesting-induced effects modifying soil properties and light availability respectively impacted ECM composition and seedling growth. Topography-induced variations in water and nutrient availability led to changes in ECM composition, but had little impact on seedling growth. Contact, short-distance, and long-distance exploration types improved the nutritional status of seedlings (Ca, K, and N), showing that mycorrhization could play an important role in seedling vitality. However, neither ECM root colonisation nor exploration types could be related to regeneration failures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Symbiosis with ectomycorrhizal (ECM) fungi can be important for regeneration success. In a context of increasing regeneration failures in the coastal forest of maritime pine in Southwest France, we tried to identity whether differences in ECM communities could partly explain the variation of regeneration success and how they are influenced by forest practices and stand characteristics. In particular, we focused on the effects of harvesting methods (comparing mature forest with seed-tree regeneration and clear-cuts) and topography (bottom-, mid-, and top positions). Five field trials (two in regeneration failure areas and three in successful areas) were used to sample 450 one-year-old seedlings. Assessments of ECM of seedling nutrient concentrations and of seedling growth based on exploration types were made. ECM root colonisation was similar in all harvesting treatments, suggesting that enough inoculum remained alive after logging. Harvesting-induced effects modifying soil properties and light availability respectively impacted ECM composition and seedling growth. Topography-induced variations in water and nutrient availability led to changes in ECM composition, but had little impact on seedling growth. Contact, short-distance, and long-distance exploration types improved the nutritional status of seedlings (Ca, K, and N), showing that mycorrhization could play an important role in seedling vitality. However, neither ECM root colonisation nor exploration types could be related to regeneration failures. |
Webster, J M; Braga, J C; Humblet, M; Potts, D C; Iryu, Y; Yokoyama, Y; Fujita, K; Bourillot, R; Esat, T M; Fallon, S; Thompson, W G; Thomas, A L; Kan, H; McGregor, H V; Hinestrosa, G; Obrochta, S P; Lougheed, B C Response of the Great Barrier Reef to sea-level and environmental changes over the past 30,000 years Article de journal Nature Geoscience, 2018, ISSN: 1752-0908. @article{Webster2018, title = {Response of the Great Barrier Reef to sea-level and environmental changes over the past 30,000 years}, author = {J M Webster and J C Braga and M Humblet and D C Potts and Y Iryu and Y Yokoyama and K Fujita and R Bourillot and T M Esat and S Fallon and W G Thompson and A L Thomas and H Kan and H V McGregor and G Hinestrosa and S P Obrochta and B C Lougheed}, doi = {10.1038/s41561-018-0127-3}, issn = {1752-0908}, year = {2018}, date = {2018-01-01}, journal = {Nature Geoscience}, abstract = {Previous drilling through submerged fossil coral reefs has greatly improved our understanding of the general pattern of sea-level change since the Last Glacial Maximum, however, how reefs responded to these changes remains uncertain. Here we document the evolution of the Great Barrier Reef (GBR), the world's largest reef system, to major, abrupt environmental changes over the past 30 thousand years based on comprehensive sedimentological, biological and geochronological records from fossil reef cores. We show that reefs migrated seaward as sea level fell to its lowest level during the most recent glaciation (∼20.5-20.7 thousand years ago (ka)), then landward as the shelf flooded and ocean temperatures increased during the subsequent deglacial period (∼20-10 ka). Growth was interrupted by five reef-death events caused by subaerial exposure or sea-level rise outpacing reef growth. Around 10 ka, the reef drowned as the sea level continued to rise, flooding more of the shelf and causing a higher sediment flux. The GBR's capacity for rapid lateral migration at rates of 0.2-1.5 m yr-1 (and the ability to recruit locally) suggest that, as an ecosystem, the GBR has been more resilient to past sea-level and temperature fluctuations than previously thought, but it has been highly sensitive to increased sediment input over centennial-millennial timescales. textcopyright 2018 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Previous drilling through submerged fossil coral reefs has greatly improved our understanding of the general pattern of sea-level change since the Last Glacial Maximum, however, how reefs responded to these changes remains uncertain. Here we document the evolution of the Great Barrier Reef (GBR), the world's largest reef system, to major, abrupt environmental changes over the past 30 thousand years based on comprehensive sedimentological, biological and geochronological records from fossil reef cores. We show that reefs migrated seaward as sea level fell to its lowest level during the most recent glaciation (∼20.5-20.7 thousand years ago (ka)), then landward as the shelf flooded and ocean temperatures increased during the subsequent deglacial period (∼20-10 ka). Growth was interrupted by five reef-death events caused by subaerial exposure or sea-level rise outpacing reef growth. Around 10 ka, the reef drowned as the sea level continued to rise, flooding more of the shelf and causing a higher sediment flux. The GBR's capacity for rapid lateral migration at rates of 0.2-1.5 m yr-1 (and the ability to recruit locally) suggest that, as an ecosystem, the GBR has been more resilient to past sea-level and temperature fluctuations than previously thought, but it has been highly sensitive to increased sediment input over centennial-millennial timescales. textcopyright 2018 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. |
Schafer, David; Donn, Michael; Atteia, Olivier; Sun, Jing; MacRae, Colin; Raven, Mark; Pejcic, Bobby; Prommer, Henning Fluoride and phosphate release from carbonate-rich fluorapatite during managed aquifer recharge Article de journal Journal of Hydrology, 2018, ISSN: 00221694. @article{Schafer2018, title = {Fluoride and phosphate release from carbonate-rich fluorapatite during managed aquifer recharge}, author = {David Schafer and Michael Donn and Olivier Atteia and Jing Sun and Colin MacRae and Mark Raven and Bobby Pejcic and Henning Prommer}, doi = {10.1016/j.jhydrol.2018.05.043}, issn = {00221694}, year = {2018}, date = {2018-01-01}, journal = {Journal of Hydrology}, abstract = {Managed aquifer recharge (MAR) is increasingly used as a water management tool to enhance water availability and to improve water quality. Until now, however, the risk of fluoride release during MAR with low ionic strength injectate has not been recognised or examined. In this study we analyse and report the mobilisation of fluoride (up to 58 µM) and filterable reactive phosphorus (FRP) (up to 55 µM) during a field groundwater replenishment experiment in which highly treated, deionised wastewater (average TDS 33 mg/L) was injected into a siliciclastic Cretaceous aquifer. In the field experiment, maximum concentrations, which coincided with a rise in pH, exceeded background groundwater concentrations by an average factor of 3.6 for fluoride and 24 for FRP. The combined results from the field experiment, a detailed mineralogical characterisation and geochemical modelling suggested carbonate-rich fluorapatite (CFA: Ca10(PO4)5(CO3,F)F2) to be the most likely source of fluoride and phosphate release. An anoxic batch experiment with powdered CFA-rich nodules sourced from the target aquifer and aqueous solutions of successively decreasing ionic strength closely replicated the field-observed fluoride and phosphate behaviour. Based on the laboratory experiment and geochemical modelling, we hypothesise that the release of fluoride and phosphate results from the incongruent dissolution of CFA and the simultaneous formation of a depleted layer that has hydrated di-basic calcium phosphate (CaHPO4textperiodcenterednH2O) composition at the CFA-water interface. Disequilibrium caused by calcium removal following breakthrough of the deionised injectate triggered the release of fluoride and phosphate. Given the increasing use of highly treated, deionised water for MAR and the ubiquitous presence of CFA and fluorapatite (Ca10(PO4)6F2) in aquifer settings worldwide, the risk of fluoride and phosphate release needs to be considered in the MAR design process.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Managed aquifer recharge (MAR) is increasingly used as a water management tool to enhance water availability and to improve water quality. Until now, however, the risk of fluoride release during MAR with low ionic strength injectate has not been recognised or examined. In this study we analyse and report the mobilisation of fluoride (up to 58 µM) and filterable reactive phosphorus (FRP) (up to 55 µM) during a field groundwater replenishment experiment in which highly treated, deionised wastewater (average TDS 33 mg/L) was injected into a siliciclastic Cretaceous aquifer. In the field experiment, maximum concentrations, which coincided with a rise in pH, exceeded background groundwater concentrations by an average factor of 3.6 for fluoride and 24 for FRP. The combined results from the field experiment, a detailed mineralogical characterisation and geochemical modelling suggested carbonate-rich fluorapatite (CFA: Ca10(PO4)5(CO3,F)F2) to be the most likely source of fluoride and phosphate release. An anoxic batch experiment with powdered CFA-rich nodules sourced from the target aquifer and aqueous solutions of successively decreasing ionic strength closely replicated the field-observed fluoride and phosphate behaviour. Based on the laboratory experiment and geochemical modelling, we hypothesise that the release of fluoride and phosphate results from the incongruent dissolution of CFA and the simultaneous formation of a depleted layer that has hydrated di-basic calcium phosphate (CaHPO4textperiodcenterednH2O) composition at the CFA-water interface. Disequilibrium caused by calcium removal following breakthrough of the deionised injectate triggered the release of fluoride and phosphate. Given the increasing use of highly treated, deionised water for MAR and the ubiquitous presence of CFA and fluorapatite (Ca10(PO4)6F2) in aquifer settings worldwide, the risk of fluoride and phosphate release needs to be considered in the MAR design process. |
Al-Mojel, Abdullah; Dera, Guillaume; Razin, Philippe; Le Nindre, Yves Michel Carbon and oxygen isotope stratigraphy of Jurassic platform carbonates from Saudi Arabia: Implications for diagenesis, correlations and global paleoenvironmental changes Article de journal Palaeogeography, Palaeoclimatology, Palaeoecology, 2018, ISSN: 00310182. @article{Al-Mojel2018, title = {Carbon and oxygen isotope stratigraphy of Jurassic platform carbonates from Saudi Arabia: Implications for diagenesis, correlations and global paleoenvironmental changes}, author = {Abdullah Al-Mojel and Guillaume Dera and Philippe Razin and Yves Michel {Le Nindre}}, doi = {10.1016/j.palaeo.2018.09.005}, issn = {00310182}, year = {2018}, date = {2018-01-01}, journal = {Palaeogeography, Palaeoclimatology, Palaeoecology}, abstract = {Major carbon cycle disturbances reflected by carbon isotope excursions (CIE) have been reported in the Jurassic successions of Euro-Boreal and Mediterranean basins. However, sedimentary and geochemical data from other domains are still required to unravel the global or regional nature of paleoenvironmental disturbances and identify the potential triggers. Here, we present biostratigraphically well-constrained (middle Toarcian to lower Kimmeridgian) bulk-rock $delta$13C and $delta$18O data from central Saudi Arabia. Five major negative $delta$18O excursions are identified in back-reef facies below sequence boundaries and disconformities (Aalenian-Bajocian boundary, upper Bajocian, middle Bathonian, upper Callovian and lower Kimmeridgian), suggesting that these carbonates underwent intense meteoric diagenesis during partial or major subaerial exposures of the Arabian Platform. The $delta$13C record is less altered and shows correlations with the regional relative sea-level changes influencing the productivity levels and inflows of fluvial (12C-enriched) or oceanic (12C-depleted) waters onto the platform. Overall, most of the $delta$13C variations recorded at the scale of the Arabian Platform within the lower and middle Jurassic are in agreement with NW Tethyan data. Among these variations, the increase in $delta$13C values recorded in the middle Toarcian, lower Bajocian, and lower Bathonian zigzag Zone indicate a considerable increase of productivity and12Corgburial concomitant with global sea-level rises. Conversely, the occurrence of major but diachronous negative CIEs at the Aalenian-Bajocian boundary and around the lower-upper Bajocian transition are interpreted as accelerations of terrestrial12Corgtransfer to the ocean and atmosphere linked to regional but widespread emergences of landmasses. Whether global (eustatic) or regional (tectonic), all these sea-level changes and carbon transfers could be distal consequences of successive episodes of the Pangean breakup.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Major carbon cycle disturbances reflected by carbon isotope excursions (CIE) have been reported in the Jurassic successions of Euro-Boreal and Mediterranean basins. However, sedimentary and geochemical data from other domains are still required to unravel the global or regional nature of paleoenvironmental disturbances and identify the potential triggers. Here, we present biostratigraphically well-constrained (middle Toarcian to lower Kimmeridgian) bulk-rock $delta$13C and $delta$18O data from central Saudi Arabia. Five major negative $delta$18O excursions are identified in back-reef facies below sequence boundaries and disconformities (Aalenian-Bajocian boundary, upper Bajocian, middle Bathonian, upper Callovian and lower Kimmeridgian), suggesting that these carbonates underwent intense meteoric diagenesis during partial or major subaerial exposures of the Arabian Platform. The $delta$13C record is less altered and shows correlations with the regional relative sea-level changes influencing the productivity levels and inflows of fluvial (12C-enriched) or oceanic (12C-depleted) waters onto the platform. Overall, most of the $delta$13C variations recorded at the scale of the Arabian Platform within the lower and middle Jurassic are in agreement with NW Tethyan data. Among these variations, the increase in $delta$13C values recorded in the middle Toarcian, lower Bajocian, and lower Bathonian zigzag Zone indicate a considerable increase of productivity and12Corgburial concomitant with global sea-level rises. Conversely, the occurrence of major but diachronous negative CIEs at the Aalenian-Bajocian boundary and around the lower-upper Bajocian transition are interpreted as accelerations of terrestrial12Corgtransfer to the ocean and atmosphere linked to regional but widespread emergences of landmasses. Whether global (eustatic) or regional (tectonic), all these sea-level changes and carbon transfers could be distal consequences of successive episodes of the Pangean breakup. |
Peruzzo, Luca; Schmutz, Myriam; Franceschi, Michel; Wu, Yuxin; Hubbard, Susan S The Relative Importance of Saturated Silica Sand Interfacial and Pore Fluid Geochemistry on the Spectral Induced Polarization Response Article de journal Journal of Geophysical Research: Biogeosciences, 2018, ISSN: 21698961. @article{Peruzzo2018, title = {The Relative Importance of Saturated Silica Sand Interfacial and Pore Fluid Geochemistry on the Spectral Induced Polarization Response}, author = {Luca Peruzzo and Myriam Schmutz and Michel Franceschi and Yuxin Wu and Susan S Hubbard}, doi = {10.1029/2017JG004364}, issn = {21698961}, year = {2018}, date = {2018-01-01}, journal = {Journal of Geophysical Research: Biogeosciences}, abstract = {textcopyright2018. American Geophysical Union. All Rights Reserved. Adsorption at the solid-pore fluid interface is a key mechanism controlling the mobility of nutrients and contaminants in subsurface soils and sediments. The spectral induced polarization (SIP) method has been shown to be sensitive to the quantity and type of adsorbed ions. Extending previous results, we investigated the relevance of pH, solution conductivity, and ion type on the SIP response of saturated silica sand. We also performed adsorption experiments to evaluate whether adsorption plays a relevant role on the effect of saturating solution conductivity and pH. Given their environmental relevance and different electrochemical characteristics, we focused on exploring the influence of Cu2+and Na+adsorption on the SIP signature. The adsorption results confirm the expected and modeled pH influence on the adsorption of both Cu2+and Na+. The measured quadrature conductivity spectra indicate that pH and solution conductivity control the electrical double layer electrochemical state and its capacitive behavior. On the contrary, no appreciable SIP signal changes are associated with ion substitution. The adsorption experiments highlight low values of site occupancy for Na and Cu, which suggests that the effects of pH and fluid conductivity are unrelated to their control on the ion adsorption. We interpret the solution conductivity as a proxy for ionic strength. The relative importance of pH and solution conductivity over ion type helps to further constrain the interpretation of SIP results in field geochemical and biogeochemical characterization and monitoring.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright2018. American Geophysical Union. All Rights Reserved. Adsorption at the solid-pore fluid interface is a key mechanism controlling the mobility of nutrients and contaminants in subsurface soils and sediments. The spectral induced polarization (SIP) method has been shown to be sensitive to the quantity and type of adsorbed ions. Extending previous results, we investigated the relevance of pH, solution conductivity, and ion type on the SIP response of saturated silica sand. We also performed adsorption experiments to evaluate whether adsorption plays a relevant role on the effect of saturating solution conductivity and pH. Given their environmental relevance and different electrochemical characteristics, we focused on exploring the influence of Cu2+and Na+adsorption on the SIP signature. The adsorption results confirm the expected and modeled pH influence on the adsorption of both Cu2+and Na+. The measured quadrature conductivity spectra indicate that pH and solution conductivity control the electrical double layer electrochemical state and its capacitive behavior. On the contrary, no appreciable SIP signal changes are associated with ion substitution. The adsorption experiments highlight low values of site occupancy for Na and Cu, which suggests that the effects of pH and fluid conductivity are unrelated to their control on the ion adsorption. We interpret the solution conductivity as a proxy for ionic strength. The relative importance of pH and solution conductivity over ion type helps to further constrain the interpretation of SIP results in field geochemical and biogeochemical characterization and monitoring. |
Le Lous, M; Larroque, F; Dupuy, A; Moignard, A; Damy, P -C Performance of an open-loop well-doublet scheme located in a deep aquitard–aquifer system: Insights from a synthetic coupled heat and flow model Article de journal Geothermics, 74 , p. 74–91, 2018. @article{LeLous2018, title = {Performance of an open-loop well-doublet scheme located in a deep aquitard\textendashaquifer system: Insights from a synthetic coupled heat and flow model}, author = {M {Le Lous} and F Larroque and A Dupuy and A Moignard and P -C Damy}, doi = {10.1016/j.geothermics.2018.02.008}, year = {2018}, date = {2018-01-01}, journal = {Geothermics}, volume = {74}, pages = {74--91}, abstract = {textcopyright 2018 Elsevier Ltd Understanding hydrothermal processes during production is critical to optimize geothermal reservoir operation and reduce the risk of its failure. The influence of the subsurface physical parameters, the design of the wells, and their operational settings on a high-enthalpy liquid-dominated geothermal operation has been investigated. For this purpose, a numerical model was developed, accounting for the flow, mass and heat transport in a single-phase aquitard\textendashaquifer system, in the vicinity of a vertical 4-km well-doublet scheme. The sensitivity analysis varies the thermal power from 34.0 MWt to 58.1 MWt and the productivity index altered within the range 0\textendash4.9 × 102 l s−1 bar−1. The parameters affecting both the hydraulic and thermal performances are (1) the reservoir permeability, (2) the injection temperature, (3) the production/injection rates, (4) the aquifer thermal conductivity, and (5) the length of the openhole section. These parameters provide a general control of the project and should be carefully estimated and designed. The predominant role of the aquifer parameters over the aquitard parameters is clearly demonstrated in this specific study. However, ignoring the caprock and bedrock in the model simulations would result in strongly and negatively biased estimates of the reservoir temperatures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018 Elsevier Ltd Understanding hydrothermal processes during production is critical to optimize geothermal reservoir operation and reduce the risk of its failure. The influence of the subsurface physical parameters, the design of the wells, and their operational settings on a high-enthalpy liquid-dominated geothermal operation has been investigated. For this purpose, a numerical model was developed, accounting for the flow, mass and heat transport in a single-phase aquitard–aquifer system, in the vicinity of a vertical 4-km well-doublet scheme. The sensitivity analysis varies the thermal power from 34.0 MWt to 58.1 MWt and the productivity index altered within the range 0–4.9 × 102 l s−1 bar−1. The parameters affecting both the hydraulic and thermal performances are (1) the reservoir permeability, (2) the injection temperature, (3) the production/injection rates, (4) the aquifer thermal conductivity, and (5) the length of the openhole section. These parameters provide a general control of the project and should be carefully estimated and designed. The predominant role of the aquifer parameters over the aquitard parameters is clearly demonstrated in this specific study. However, ignoring the caprock and bedrock in the model simulations would result in strongly and negatively biased estimates of the reservoir temperatures. |
Cherubini, A; Garcia, B; Cerepi, A; Revil, A Streaming potential coupling coefficient and transport properties of unsaturated carbonate rocks Article de journal Vadose Zone Journal, 17 (1), 2018. @article{Cherubini2018, title = {Streaming potential coupling coefficient and transport properties of unsaturated carbonate rocks}, author = {A Cherubini and B Garcia and A Cerepi and A Revil}, doi = {10.2136/vzj2018.02.0030}, year = {2018}, date = {2018-01-01}, journal = {Vadose Zone Journal}, volume = {17}, number = {1}, abstract = {textcopyright Soil Science Society of America. We measured the streaming potential coupling coefficient of natural saturated and unsaturated carbonate rocks. Saturation was achieved with NaCl brines with salinities ranging from 2 × 10−3 to 2.0 mol L−1. The magnitude of the coupling coefficient increased with decreasing salinity, similarly to the trend observed for sandstones. The permeability had a low impact on the values of the streaming potential coupling coefficient at high and low salinity. The zeta potential was calculated at full saturation using a modified version of the Helmholtz\textendashSmoluchowski equation that accounts for surface electrical conductivity. Under atmospheric conditions, the magnitude of the zeta potential decreased with the increase in salinity. We also explored the relationships between the streaming potential coupling coefficient and water saturation in three partially saturated limestones using a steady-state flow experiment. We found good agreement between the van Genuchten approach and experimental data, and fitted both the relative permeability and capillary pressure curves with the same value of the van Genuchten exponent mv. We validated the predictive water relative permeability model described by Revil in water-wet rocks when the second fluid phase is non-polar.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright Soil Science Society of America. We measured the streaming potential coupling coefficient of natural saturated and unsaturated carbonate rocks. Saturation was achieved with NaCl brines with salinities ranging from 2 × 10−3 to 2.0 mol L−1. The magnitude of the coupling coefficient increased with decreasing salinity, similarly to the trend observed for sandstones. The permeability had a low impact on the values of the streaming potential coupling coefficient at high and low salinity. The zeta potential was calculated at full saturation using a modified version of the Helmholtz–Smoluchowski equation that accounts for surface electrical conductivity. Under atmospheric conditions, the magnitude of the zeta potential decreased with the increase in salinity. We also explored the relationships between the streaming potential coupling coefficient and water saturation in three partially saturated limestones using a steady-state flow experiment. We found good agreement between the van Genuchten approach and experimental data, and fitted both the relative permeability and capillary pressure curves with the same value of the van Genuchten exponent mv. We validated the predictive water relative permeability model described by Revil in water-wet rocks when the second fluid phase is non-polar. |
Vennin, E; Bouton, A; Bourillot, R; Pace, A; Roche, A; Brayard, A; Thomazo, C; Virgone, A; Gaucher, E C; Desaubliaux, G; Visscher, P T The lacustrine microbial carbonate factory of the successive Lake Bonneville and Great Salt Lake, Utah, USA Article de journal Sedimentology, 2018. @article{Vennin2018, title = {The lacustrine microbial carbonate factory of the successive Lake Bonneville and Great Salt Lake, Utah, USA}, author = {E Vennin and A Bouton and R Bourillot and A Pace and A Roche and A Brayard and C Thomazo and A Virgone and E C Gaucher and G Desaubliaux and P T Visscher}, doi = {10.1111/sed.12499}, year = {2018}, date = {2018-01-01}, journal = {Sedimentology}, abstract = {textcopyright 2018 The Authors. Sedimentology textcopyright 2018 International Association of Sedimentologists The Bonneville Basin is a continental lacustrine system accommodating extensive microbial carbonate deposits corresponding to two distinct phases: the deep Lake Bonneville (30 000 to 11 50014C bp) and the shallow Great Salt Lake (since 11 50014C bp). A characterization of these microbial deposits and their associated sediments provides insights into their spatio-temporal distribution patterns. The Bonneville phase preferentially displays vertical distribution of the microbial deposits resulting from high-amplitude lake level variations. Due to the basin physiography, the microbial deposits were restricted to a narrow shoreline belt following Bonneville lake level variations. Carbonate production was more efficient during intervals of relative lake level stability as recorded by the formation of successive terraces. In contrast, the Great Salt Lake microbial deposits showed a great lateral distribution, linked to the modern flat bottom configuration. A low vertical distribution of the microbial deposits was the result of the shallow water depth combined with a low amplitude of lake level fluctuations. These younger microbial deposits display a higher diversity of fabrics and sizes. They are distributed along an extensive ‘shore to lake' transect on a flat platform in relation to local and progressive accommodation space changes. Microbial deposits are temporally discontinuous throughout the lake history showing longer hiatuses during the Bonneville phase. The main parameters controlling the rate of carbonate production are related to the interaction between physical (kinetics of the mineral precipitation, lake water temperature and runoff), chemical (Ca2+, Mg2+and HCO3−concentrations, Mg/Ca ratio, dilution and depletion) and/or biological (trophic) factors. The contrast in evolution of Lake Bonneville and Great Salt Lake microbial deposits during their lacustrine history leads to discussions on major chemical and climatic changes during this interval as well as the role of physiography. Furthermore, it provides novel insights into the composition, structure and formation of microbialite-rich carbonate deposits under freshwater and hypersaline conditions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018 The Authors. Sedimentology textcopyright 2018 International Association of Sedimentologists The Bonneville Basin is a continental lacustrine system accommodating extensive microbial carbonate deposits corresponding to two distinct phases: the deep Lake Bonneville (30 000 to 11 50014C bp) and the shallow Great Salt Lake (since 11 50014C bp). A characterization of these microbial deposits and their associated sediments provides insights into their spatio-temporal distribution patterns. The Bonneville phase preferentially displays vertical distribution of the microbial deposits resulting from high-amplitude lake level variations. Due to the basin physiography, the microbial deposits were restricted to a narrow shoreline belt following Bonneville lake level variations. Carbonate production was more efficient during intervals of relative lake level stability as recorded by the formation of successive terraces. In contrast, the Great Salt Lake microbial deposits showed a great lateral distribution, linked to the modern flat bottom configuration. A low vertical distribution of the microbial deposits was the result of the shallow water depth combined with a low amplitude of lake level fluctuations. These younger microbial deposits display a higher diversity of fabrics and sizes. They are distributed along an extensive ‘shore to lake' transect on a flat platform in relation to local and progressive accommodation space changes. Microbial deposits are temporally discontinuous throughout the lake history showing longer hiatuses during the Bonneville phase. The main parameters controlling the rate of carbonate production are related to the interaction between physical (kinetics of the mineral precipitation, lake water temperature and runoff), chemical (Ca2+, Mg2+and HCO3−concentrations, Mg/Ca ratio, dilution and depletion) and/or biological (trophic) factors. The contrast in evolution of Lake Bonneville and Great Salt Lake microbial deposits during their lacustrine history leads to discussions on major chemical and climatic changes during this interval as well as the role of physiography. Furthermore, it provides novel insights into the composition, structure and formation of microbialite-rich carbonate deposits under freshwater and hypersaline conditions. |
Mench, M J; Dellise, M; Bes, C M; Marchand, L; Kolbas, A; Coustumer, P L; è, Oustri N Phytomanagement and remediation of cu-contaminated soils by high yielding crops at a former wood preservation site: Sunflower biomass and ionome Article de journal Frontiers in Ecology and Evolution, 6 (SEP), 2018. @article{Mench2018, title = {Phytomanagement and remediation of cu-contaminated soils by high yielding crops at a former wood preservation site: Sunflower biomass and ionome}, author = {M J Mench and M Dellise and C M Bes and L Marchand and A Kolbas and P L Coustumer and N Oustri{\`{e}}re}, doi = {10.3389/fevo.2018.00123}, year = {2018}, date = {2018-01-01}, journal = {Frontiers in Ecology and Evolution}, volume = {6}, number = {SEP}, abstract = {textcopyright 2018 Mench, Dellise, Bes, Marchand, Kolbas, Le Coustumer and Oustri\`{e}re. This long-term field trial aimed at remediating a Cu-contaminated soil to promote crop production and soil functions at a former wood preservation site. Twenty-eight field plots with total topsoil Cu in the 198-1,169 mg kg-1 range were assessed. Twenty-four plots (OMDL) were amended in 2008 with a compost (made of pine bark chips and poultry manure, OM, 5% w/w) and dolomitic limestone (DL, 0.2%), and thereafter annually phytomanaged with a sunflower-tobacco crop rotation. In 2013, one untreated plot (UNT) was amended with a green waste compost (GW, 5%) whereas 12 former OMDL plots received a second compost dressing using this green waste compost (OM2DL, 5%). In 2011, one plot was amended with the Carmeuse basic slag (CAR, 1%) and another plot with a P-spiked Linz-Donawitz basic slag (PLD, 1%). Thus six soil treatments, i.e., UNT, OMDL, OM2DL, GW, CAR, and PLD, were cultivated in 2016 with sunflower (Helianthus annuus L. cv Ethic). Shoots were harvested and their ionome analyzed. At high soil Cu contamination, the 1M NH4NO3-extractable vs. total soil Cu ratio ranked in decreasing order: Unt (2.35) textgreater CAR (1.02), PLD (0.83) textgreater GW (0.58), OMDL (0.44), OM2DL (0.37), indicating a lower Cu extractability in the compost-amended plots. All amendments improved the soil nutrient status and the soil pH, which was slightly acidic in the UNT soil. Total organic C and N and extractable P contents peaked in the OM2DL soils. Both OMDL and OM2DL treatments led to higher shoot DW yields and Cu removals than the GW, CAR, and PLD treatments. Shoot DW yields decreased as total topsoil Cu rose in the OMDL plots, on the contrary to the OM2DL plots, demonstrating the benefits to repeat compost application after 5 years. Shoot Cu concentrations notably of OMDL and OM2DL plants fitted into their common range and can be used by biomass processing technologies and oilseeds as well. In overall, there is a net gain in soil physico-chemical properties and underlying soil functions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018 Mench, Dellise, Bes, Marchand, Kolbas, Le Coustumer and Oustrière. This long-term field trial aimed at remediating a Cu-contaminated soil to promote crop production and soil functions at a former wood preservation site. Twenty-eight field plots with total topsoil Cu in the 198-1,169 mg kg-1 range were assessed. Twenty-four plots (OMDL) were amended in 2008 with a compost (made of pine bark chips and poultry manure, OM, 5% w/w) and dolomitic limestone (DL, 0.2%), and thereafter annually phytomanaged with a sunflower-tobacco crop rotation. In 2013, one untreated plot (UNT) was amended with a green waste compost (GW, 5%) whereas 12 former OMDL plots received a second compost dressing using this green waste compost (OM2DL, 5%). In 2011, one plot was amended with the Carmeuse basic slag (CAR, 1%) and another plot with a P-spiked Linz-Donawitz basic slag (PLD, 1%). Thus six soil treatments, i.e., UNT, OMDL, OM2DL, GW, CAR, and PLD, were cultivated in 2016 with sunflower (Helianthus annuus L. cv Ethic). Shoots were harvested and their ionome analyzed. At high soil Cu contamination, the 1M NH4NO3-extractable vs. total soil Cu ratio ranked in decreasing order: Unt (2.35) textgreater CAR (1.02), PLD (0.83) textgreater GW (0.58), OMDL (0.44), OM2DL (0.37), indicating a lower Cu extractability in the compost-amended plots. All amendments improved the soil nutrient status and the soil pH, which was slightly acidic in the UNT soil. Total organic C and N and extractable P contents peaked in the OM2DL soils. Both OMDL and OM2DL treatments led to higher shoot DW yields and Cu removals than the GW, CAR, and PLD treatments. Shoot DW yields decreased as total topsoil Cu rose in the OMDL plots, on the contrary to the OM2DL plots, demonstrating the benefits to repeat compost application after 5 years. Shoot Cu concentrations notably of OMDL and OM2DL plants fitted into their common range and can be used by biomass processing technologies and oilseeds as well. In overall, there is a net gain in soil physico-chemical properties and underlying soil functions. |
Rhino, K; Loisy, C; Cerepi, A; Garcia, B; Rouchon, V; Khamlichi, A E; Noirez, S International Journal of Greenhouse Gas Control, 77 , p. 55–69, 2018. @article{Rhino2018, title = {Characterization and quantification of a COtextlessinftextgreater2textless/inftextgreaterand CHtextlessinftextgreater4textless/inftextgreaterleakage experiment from a well into the carbonate vadose zone}, author = {K Rhino and C Loisy and A Cerepi and B Garcia and V Rouchon and A E Khamlichi and S Noirez}, doi = {10.1016/j.ijggc.2018.07.025}, year = {2018}, date = {2018-01-01}, journal = {International Journal of Greenhouse Gas Control}, volume = {77}, pages = {55--69}, abstract = {textcopyright 2018 Elsevier Ltd An ultra-diffusive leakage experiment was performed on the pilot site of Saint-Emilion near Bordeaux in France. It consisted in the injection of 85% CO2and 5% of each He, Kr and CH4in a vertical well with a very low injection pressure. This study allowed the development of an automated tool that continuously monitored the gas phase within the vadose zone. Measurements showed that the gas plume had a heterogeneous spatial and temporal variation. Mathematical calculations performed on the time series of the gas species showed that diffusive transport mainly occurred in the porous media. However, every stage of the migration could not be driven by diffusive process as shown by the exponential regression. A non-identified transport mechanism may have occurred during the increase of concentration. He was proven to be a suitable temporal tracer for a CO2leakage as it was a good temporal precursor. Even if the process was weaker than in the former injection experiments, Kr could show help foreseeing the extent of the gas plume within the pilot site. CH4was also shown to be an excellent temporal precursor of CO2arrival. The amount of gas migrating through the preferential path identified in the previous experiment was weaker than in the previous study. Moreover, the monitoring showed that a significant amount of injected gas migrated deeper in the vadose zone. The ratios CO2/Kr vs. CO2/He and the evolution of CO2/Kr, CO2/He and CO2/CH4put in evidence three groups of probes. The first consists in the subsurface probes and is characterized by a potential reactive transport ofCO2through the vadose zone such as gas dissolution in the aqueous phase. The second group gathers the closest probes to the injection point and underlines a very slow return to baseline value through diffusion. The third group is characterized by a competition between the process occurring in the first and second group. Isotopic measurement of Kr could not bring relevant information about the CO2fates into the vadose zone. However, it shows the possible presence of mechanism transport such as vertical flux and gravitational settlings. Observations from both of all the leakage experiment and future laboratory experiment could improve our understandings of the buffering zone and help to foresee CO2leakage for future storage site.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018 Elsevier Ltd An ultra-diffusive leakage experiment was performed on the pilot site of Saint-Emilion near Bordeaux in France. It consisted in the injection of 85% CO2and 5% of each He, Kr and CH4in a vertical well with a very low injection pressure. This study allowed the development of an automated tool that continuously monitored the gas phase within the vadose zone. Measurements showed that the gas plume had a heterogeneous spatial and temporal variation. Mathematical calculations performed on the time series of the gas species showed that diffusive transport mainly occurred in the porous media. However, every stage of the migration could not be driven by diffusive process as shown by the exponential regression. A non-identified transport mechanism may have occurred during the increase of concentration. He was proven to be a suitable temporal tracer for a CO2leakage as it was a good temporal precursor. Even if the process was weaker than in the former injection experiments, Kr could show help foreseeing the extent of the gas plume within the pilot site. CH4was also shown to be an excellent temporal precursor of CO2arrival. The amount of gas migrating through the preferential path identified in the previous experiment was weaker than in the previous study. Moreover, the monitoring showed that a significant amount of injected gas migrated deeper in the vadose zone. The ratios CO2/Kr vs. CO2/He and the evolution of CO2/Kr, CO2/He and CO2/CH4put in evidence three groups of probes. The first consists in the subsurface probes and is characterized by a potential reactive transport ofCO2through the vadose zone such as gas dissolution in the aqueous phase. The second group gathers the closest probes to the injection point and underlines a very slow return to baseline value through diffusion. The third group is characterized by a competition between the process occurring in the first and second group. Isotopic measurement of Kr could not bring relevant information about the CO2fates into the vadose zone. However, it shows the possible presence of mechanism transport such as vertical flux and gravitational settlings. Observations from both of all the leakage experiment and future laboratory experiment could improve our understandings of the buffering zone and help to foresee CO2leakage for future storage site. |
Pace, A; Bourillot, R; Bouton, A; Vennin, E; Braissant, O; Dupraz, C; Duteil, T; Bundeleva, I; Patrier, P; Galaup, S; Yokoyama, Y; Franceschi, M; Virgone, A; Visscher, P T Formation of stromatolite lamina at the interface of oxygenic–anoxygenic photosynthesis Article de journal Geobiology, 16 (4), p. 378–398, 2018. @article{Pace2018, title = {Formation of stromatolite lamina at the interface of oxygenic\textendashanoxygenic photosynthesis}, author = {A Pace and R Bourillot and A Bouton and E Vennin and O Braissant and C Dupraz and T Duteil and I Bundeleva and P Patrier and S Galaup and Y Yokoyama and M Franceschi and A Virgone and P T Visscher}, doi = {10.1111/gbi.12281}, year = {2018}, date = {2018-01-01}, journal = {Geobiology}, volume = {16}, number = {4}, pages = {378--398}, abstract = {textcopyright 2018 John Wiley & Sons Ltd In modern stromatolites, mineralization results from a complex interplay between microbial metabolisms, the organic matrix, and environmental parameters. Here, we combined biogeochemical, mineralogical, and microscopic analyses with measurements of metabolic activity to characterize the mineralization processes and products in an emergent (textless18 months) hypersaline microbial mat. While the nucleation of Mg silicates is ubiquitous in the mat, the initial formation of a Ca-Mg carbonate lamina depends on (i) the creation of a high-pH interface combined with a major change in properties of the exopolymeric substances at the interface of the oxygenic and anoxygenic photoautotrophic layers and (ii) the synergy between two major players of sulfur cycle, purple sulfur bacteria, and sulfate-reducing bacteria. The repetition of this process over time combined with upward growth of the mat is a possible pathway leading to the formation of a stromatolite.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018 John Wiley & Sons Ltd In modern stromatolites, mineralization results from a complex interplay between microbial metabolisms, the organic matrix, and environmental parameters. Here, we combined biogeochemical, mineralogical, and microscopic analyses with measurements of metabolic activity to characterize the mineralization processes and products in an emergent (textless18 months) hypersaline microbial mat. While the nucleation of Mg silicates is ubiquitous in the mat, the initial formation of a Ca-Mg carbonate lamina depends on (i) the creation of a high-pH interface combined with a major change in properties of the exopolymeric substances at the interface of the oxygenic and anoxygenic photoautotrophic layers and (ii) the synergy between two major players of sulfur cycle, purple sulfur bacteria, and sulfate-reducing bacteria. The repetition of this process over time combined with upward growth of the mat is a possible pathway leading to the formation of a stromatolite. |
Portois, C; Essouayed, E; Annable, M D; Guiserix, N; Joubert, A; Atteia, O Field demonstration of foam injection to confine a chlorinated solvent source zone Article de journal Journal of Contaminant Hydrology, 214 , p. 16–23, 2018. @article{Portois2018, title = {Field demonstration of foam injection to confine a chlorinated solvent source zone}, author = {C Portois and E Essouayed and M D Annable and N Guiserix and A Joubert and O Atteia}, doi = {10.1016/j.jconhyd.2018.04.003}, year = {2018}, date = {2018-01-01}, journal = {Journal of Contaminant Hydrology}, volume = {214}, pages = {16--23}, abstract = {textcopyright 2018 Elsevier B.V. A novel approach using foam to manage hazardous waste was successfully demonstrated under active site conditions. The purpose of the foam was to divert groundwater flow, that would normally enter the source zone area, to reduce dissolved contaminant release to the aquifer. During the demonstration, foam was pre generated and directly injected surrounding the chlorinated solvent source zone. Despite the constraints related to the industrial activities and non-optimal position of the injection points, the applicability and effectiveness of the approach have been highlighted using multiple metrics. A combination of measurements and modelling allowed definition of the foam extent surrounding each injection point, and this appears to be the critical metric to define the success of the foam injection approach. Information on the transport of chlorinated solvents in groundwater showed a decrease of contaminant flux by a factor of 4.4 downstream of the confined area. The effective permeability reduction was maintained over a period of three months. The successful containment provides evidence for consideration of the use of foam to improve traditional flushing techniques, by increasing the targeting of contaminants by remedial agents.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018 Elsevier B.V. A novel approach using foam to manage hazardous waste was successfully demonstrated under active site conditions. The purpose of the foam was to divert groundwater flow, that would normally enter the source zone area, to reduce dissolved contaminant release to the aquifer. During the demonstration, foam was pre generated and directly injected surrounding the chlorinated solvent source zone. Despite the constraints related to the industrial activities and non-optimal position of the injection points, the applicability and effectiveness of the approach have been highlighted using multiple metrics. A combination of measurements and modelling allowed definition of the foam extent surrounding each injection point, and this appears to be the critical metric to define the success of the foam injection approach. Information on the transport of chlorinated solvents in groundwater showed a decrease of contaminant flux by a factor of 4.4 downstream of the confined area. The effective permeability reduction was maintained over a period of three months. The successful containment provides evidence for consideration of the use of foam to improve traditional flushing techniques, by increasing the targeting of contaminants by remedial agents. |
Baalousha, M; Stoll, S; Motelica-Heino, M; Guigues, N; Braibant, G; Huneau, F; Le Coustumer, P Suspended particulate matter determines physical speciation of Fe, Mn, and trace metals in surface waters of Loire watershed Article de journal Environmental Science and Pollution Research, p. 1–16, 2018. @article{Baalousha2018, title = {Suspended particulate matter determines physical speciation of Fe, Mn, and trace metals in surface waters of Loire watershed}, author = {M Baalousha and S Stoll and M Motelica-Heino and N Guigues and G Braibant and F Huneau and P {Le Coustumer}}, doi = {10.1007/s11356-018-1416-5}, year = {2018}, date = {2018-01-01}, journal = {Environmental Science and Pollution Research}, pages = {1--16}, abstract = {textcopyright 2018 Springer-Verlag GmbH Germany, part of Springer Nature This study investigates the spatiotemporal variability of major and trace elements, dissolved organic carbon (DOC), total dissolved solids (TDS), and suspended particulate matter (SPM) in surface waters of several hydrosystems of the Loire River watershed in France. In particular, this study aims to delineate the impact of the abovementioned water physicochemical parameters on natural iron and manganese physical speciation (homoaggregation/heteroaggregation) among fine colloidal and dissolved (textless 10 nm), colloidal (10\textendash450 nm) and particulate (textgreater 450 nm) phases in Loire River watershed. Results show that the chemistry of the Loire River watershed is controlled by two end members: magmatic and metamorphic petrographic context on the upper part of the watershed; and sedimentary rocks for the middle and low part of the Loire. The percentage of particulate Fe and Mn increased downstream concurrent with the increase in SPM and major cations concentration, whereas the percentage of colloidal Fe and Mn decreased downstream. Transmission electron microscopy analyses of the colloidal and particulate fractions (from the non-filtered water sample) revealed that heteroaggregation of Fe and Mn rich natural nanoparticles and natural organic matter to the particulate phase is the dominant mechanism. The heteroaggregation controls the partitioning of Fe and Mn in the different fractions, potentially due to the increase in the ionic strength, and divalent cations concentration downstream, and SPM concentration. These findings imply that SPM concentration plays an important role in controlling the fate and behavior of Fe and Mn in various sized fractions. [Figure not available: see fulltext.]}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018 Springer-Verlag GmbH Germany, part of Springer Nature This study investigates the spatiotemporal variability of major and trace elements, dissolved organic carbon (DOC), total dissolved solids (TDS), and suspended particulate matter (SPM) in surface waters of several hydrosystems of the Loire River watershed in France. In particular, this study aims to delineate the impact of the abovementioned water physicochemical parameters on natural iron and manganese physical speciation (homoaggregation/heteroaggregation) among fine colloidal and dissolved (textless 10 nm), colloidal (10–450 nm) and particulate (textgreater 450 nm) phases in Loire River watershed. Results show that the chemistry of the Loire River watershed is controlled by two end members: magmatic and metamorphic petrographic context on the upper part of the watershed; and sedimentary rocks for the middle and low part of the Loire. The percentage of particulate Fe and Mn increased downstream concurrent with the increase in SPM and major cations concentration, whereas the percentage of colloidal Fe and Mn decreased downstream. Transmission electron microscopy analyses of the colloidal and particulate fractions (from the non-filtered water sample) revealed that heteroaggregation of Fe and Mn rich natural nanoparticles and natural organic matter to the particulate phase is the dominant mechanism. The heteroaggregation controls the partitioning of Fe and Mn in the different fractions, potentially due to the increase in the ionic strength, and divalent cations concentration downstream, and SPM concentration. These findings imply that SPM concentration plays an important role in controlling the fate and behavior of Fe and Mn in various sized fractions. [Figure not available: see fulltext.] |
Delerue, F; Gonzalez, M; Achat, D L; Puzos, L; Augusto, L Competition along productivity gradients: news from heathlands Article de journal Oecologia, 187 (1), p. 219–231, 2018. @article{Delerue2018, title = {Competition along productivity gradients: news from heathlands}, author = {F Delerue and M Gonzalez and D L Achat and L Puzos and L Augusto}, doi = {10.1007/s00442-018-4120-8}, year = {2018}, date = {2018-01-01}, journal = {Oecologia}, volume = {187}, number = {1}, pages = {219--231}, abstract = {textcopyright 2018, Springer-Verlag GmbH Germany, part of Springer Nature. The importance of competition in low productive habitats is still debated. Studies which simultaneously evaluate preemption of resources and consequences for population dynamics are needed for a comprehensive view of competitive outcomes. We cultivated two emblematic species of European heathlands (Calluna vulgaris and Molinia caerulea) in a nursery for 2 years at two fertility levels, reproducing the productivity gradient found in phosphorus (P)-depleted heathlands in southwest France. The second year, we planted Ulex europaeus seedlings, a ubiquitous heathland species, under the cover of the two species to evaluate its ability to regenerate. Half of the seedlings were placed in tubes for exclusion of competitor roots. We measured the development of the competitors aboveground and belowground and their interception of resources (light, water, inorganic P). Ulex seedlings' growth and survival were also measured. Our results on resources interception were consistent with species distribution in heathlands. Molinia, which dominates rich heathlands, was the strongest competitor for light and water in the rich soil. Calluna, which dominates poor heathlands, increased its root allocation in the poor soil, decreasing water and inorganic P availability. However, the impact of total competition and root competition on Ulex seedlings decreased in the poor soil. Other mechanisms, especially decrease of water stress under neighbouring plant cover, appeared to have more influence on the seedlings' response. We found no formal contradiction between Tilman and Grime's theories. Root competition has a primary role in acquisition of soil resources in poor habitats. However, the importance of competition decreases with decreasing fertility.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018, Springer-Verlag GmbH Germany, part of Springer Nature. The importance of competition in low productive habitats is still debated. Studies which simultaneously evaluate preemption of resources and consequences for population dynamics are needed for a comprehensive view of competitive outcomes. We cultivated two emblematic species of European heathlands (Calluna vulgaris and Molinia caerulea) in a nursery for 2 years at two fertility levels, reproducing the productivity gradient found in phosphorus (P)-depleted heathlands in southwest France. The second year, we planted Ulex europaeus seedlings, a ubiquitous heathland species, under the cover of the two species to evaluate its ability to regenerate. Half of the seedlings were placed in tubes for exclusion of competitor roots. We measured the development of the competitors aboveground and belowground and their interception of resources (light, water, inorganic P). Ulex seedlings' growth and survival were also measured. Our results on resources interception were consistent with species distribution in heathlands. Molinia, which dominates rich heathlands, was the strongest competitor for light and water in the rich soil. Calluna, which dominates poor heathlands, increased its root allocation in the poor soil, decreasing water and inorganic P availability. However, the impact of total competition and root competition on Ulex seedlings decreased in the poor soil. Other mechanisms, especially decrease of water stress under neighbouring plant cover, appeared to have more influence on the seedlings' response. We found no formal contradiction between Tilman and Grime's theories. Root competition has a primary role in acquisition of soil resources in poor habitats. However, the importance of competition decreases with decreasing fertility. |
Carmeille, M; Bourillot, R; Brunet, M -F; Pellenard, P; Fürsich, F T; Schnyder, J; Barrier, E; Blanpied, C; Sidorova, I Architecture and sedimentary evolution of the southwestern Gissar carbonate platform (Uzbekistan) during the Middle‒Late Jurassic Article de journal Marine and Petroleum Geology, 97 , p. 437–465, 2018. @article{Carmeille2018, title = {Architecture and sedimentary evolution of the southwestern Gissar carbonate platform (Uzbekistan) during the Middle‒Late Jurassic}, author = {M Carmeille and R Bourillot and M -F Brunet and P Pellenard and F T F\"{u}rsich and J Schnyder and E Barrier and C Blanpied and I Sidorova}, doi = {10.1016/j.marpetgeo.2018.07.021}, year = {2018}, date = {2018-01-01}, journal = {Marine and Petroleum Geology}, volume = {97}, pages = {437--465}, abstract = {textcopyright 2018 Elsevier Ltd Sedimentological investigations have been carried out in the southwestern part of the Gissar Range (Uzbekistan) in order to document the stratigraphic evolution of a vast Middle\textendashUpper Jurassic carbonate platform developed on the northern margin of the Amu Darya Basin. Two major sequences are distinguished, based on their contrasting facies pattern, platform configuration and carbon isotope signature: (1) a Callovian Sequence and (2) an Upper Jurassic Sequence, potentially Oxfordian to Kimmeridgian in age. A carbonate ramp with a double proximal-distal polarity developed during the Callovian Sequence. Oo-bioclastic grainstones were produced in two permanently agitated shallow water areas developing to the north and to the south. Patch and pinnacle reefs mainly built up close to the storm-wave base, passing distally to pellet- and foraminiferal-oncoid-rich mid-to outer-ramp deposits. The top of the Callovian Sequence is a regional discontinuity that could have formed by subaerial exposure of the platform. This probable hiatus could record a major climatic change associated to the Middle‒Late Jurassic transition. The Upper Jurassic Sequence consists of metre-thick alternations of pellet/algal-pack- to grainstones, microbial oncoid floatstones, ooid grainstones, and mudstones, which have likely accumulated in a vast lagoon protected by a large-scale barrier reef observed south of the study area. Gypsum and anhydrite content gradually increased towards the top of the Upper Jurassic Sequence, ending up with a thick chicken-wire gypsum accumulation recording the progradation of a large-scale sabkha over the lagoon. This phenomenon is related to a progressive aridification and restriction of the Amu Darya Basin that could have begun during the Middle/Late Oxfordian and reached its climax during the Tithonian with massive halite deposition. Comparable events occurred in Jurassic platforms located along the Tethyan margins, pointing to regional and global controls on sedimentation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018 Elsevier Ltd Sedimentological investigations have been carried out in the southwestern part of the Gissar Range (Uzbekistan) in order to document the stratigraphic evolution of a vast Middle–Upper Jurassic carbonate platform developed on the northern margin of the Amu Darya Basin. Two major sequences are distinguished, based on their contrasting facies pattern, platform configuration and carbon isotope signature: (1) a Callovian Sequence and (2) an Upper Jurassic Sequence, potentially Oxfordian to Kimmeridgian in age. A carbonate ramp with a double proximal-distal polarity developed during the Callovian Sequence. Oo-bioclastic grainstones were produced in two permanently agitated shallow water areas developing to the north and to the south. Patch and pinnacle reefs mainly built up close to the storm-wave base, passing distally to pellet- and foraminiferal-oncoid-rich mid-to outer-ramp deposits. The top of the Callovian Sequence is a regional discontinuity that could have formed by subaerial exposure of the platform. This probable hiatus could record a major climatic change associated to the Middle‒Late Jurassic transition. The Upper Jurassic Sequence consists of metre-thick alternations of pellet/algal-pack- to grainstones, microbial oncoid floatstones, ooid grainstones, and mudstones, which have likely accumulated in a vast lagoon protected by a large-scale barrier reef observed south of the study area. Gypsum and anhydrite content gradually increased towards the top of the Upper Jurassic Sequence, ending up with a thick chicken-wire gypsum accumulation recording the progradation of a large-scale sabkha over the lagoon. This phenomenon is related to a progressive aridification and restriction of the Amu Darya Basin that could have begun during the Middle/Late Oxfordian and reached its climax during the Tithonian with massive halite deposition. Comparable events occurred in Jurassic platforms located along the Tethyan margins, pointing to regional and global controls on sedimentation. |
Mary, B; Peruzzo, L; Boaga, J; Schmutz, M; Wu, Y; Hubbard, S S; Cassiani, G Small-scale characterization of vine plant root water uptake via 3-D electrical resistivity tomography and mise-à-la-masse method Article de journal Hydrology and Earth System Sciences, 22 (10), p. 5427–5444, 2018. @article{Mary2018, title = {Small-scale characterization of vine plant root water uptake via 3-D electrical resistivity tomography and mise-\`{a}-la-masse method}, author = {B Mary and L Peruzzo and J Boaga and M Schmutz and Y Wu and S S Hubbard and G Cassiani}, doi = {10.5194/hess-22-5427-2018}, year = {2018}, date = {2018-01-01}, journal = {Hydrology and Earth System Sciences}, volume = {22}, number = {10}, pages = {5427--5444}, abstract = {textcopyright 2018Author(s). The investigation of plant roots is inherently difficult and often neglected. Being out of sight, roots are often out of mind. Nevertheless, roots play a key role in the exchange of mass and energy between soil and the atmosphere, in addition to the many practical applications in agriculture. In this paper, we propose a method for roots imaging based on the joint use of two electrical noninvasive methods: electrical resistivity tomography (ERT) and mise-\`{a}-la-masse (MALM). The approach is based on the key assumption that the plant root system acts as an electrically conductive body, so that injecting electrical current into the plant stem will ultimately result in the injection of current into the subsoil through the root system, and particularly through the root terminations via hair roots. Evidence from field data, showing that voltage distribution is very different whether current is injected into the tree stem or in the ground, strongly supports this hypothesis. The proposed procedure involves a stepwise inversion of both ERT and MALM data that ultimately leads to the identification of electrical resistivity (ER) distribution and of the current injection root distribution in the three-dimensional soil space. This, in turn, is a proxy to the active (hair) root density in the ground. We tested the proposed procedure on synthetic data and, more importantly, on field data collected in a vineyard, where the estimated depth of the root zone proved to be in agreement with literature on similar crops. The proposed noninvasive approach is a step forward towards a better quantification of root structure and functioning.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018Author(s). The investigation of plant roots is inherently difficult and often neglected. Being out of sight, roots are often out of mind. Nevertheless, roots play a key role in the exchange of mass and energy between soil and the atmosphere, in addition to the many practical applications in agriculture. In this paper, we propose a method for roots imaging based on the joint use of two electrical noninvasive methods: electrical resistivity tomography (ERT) and mise-à-la-masse (MALM). The approach is based on the key assumption that the plant root system acts as an electrically conductive body, so that injecting electrical current into the plant stem will ultimately result in the injection of current into the subsoil through the root system, and particularly through the root terminations via hair roots. Evidence from field data, showing that voltage distribution is very different whether current is injected into the tree stem or in the ground, strongly supports this hypothesis. The proposed procedure involves a stepwise inversion of both ERT and MALM data that ultimately leads to the identification of electrical resistivity (ER) distribution and of the current injection root distribution in the three-dimensional soil space. This, in turn, is a proxy to the active (hair) root density in the ground. We tested the proposed procedure on synthetic data and, more importantly, on field data collected in a vineyard, where the estimated depth of the root zone proved to be in agreement with literature on similar crops. The proposed noninvasive approach is a step forward towards a better quantification of root structure and functioning. |
Bertrin, V; Boutry, S; Alard, D; Haury, J; Jan, G; Moreira, S; Ribaudo, C Prediction of macrophyte distribution: The role of natural versus anthropogenic physical disturbances Article de journal Applied Vegetation Science, 21 (3), p. 395–410, 2018. @article{Bertrin2018, title = {Prediction of macrophyte distribution: The role of natural versus anthropogenic physical disturbances}, author = {V Bertrin and S Boutry and D Alard and J Haury and G Jan and S Moreira and C Ribaudo}, doi = {10.1111/avsc.12378}, year = {2018}, date = {2018-01-01}, journal = {Applied Vegetation Science}, volume = {21}, number = {3}, pages = {395--410}, abstract = {textcopyright 2018 International Association for Vegetation Science Questions: Do natural and anthropogenic physical disturbances equally affect the distribution of aquatic plant communities? Can hydrodynamic and geomorphological features be used to predict the establishment of macrophyte communities at the shoreline scale?. Locations: Two large, shallow lakes, southwest France. Methods: Based on field observations (vegetation occurrence and anthropogenic modifications of the shore) and data generated by a geographic information system (wave exposure, wave-induced sediment re-suspension, slope and land cover), we defined sites and community groups using cluster and indicator species analyses. The groups were then analysed by means of a statistical classifier (Random Forest). These different steps in data treatment enabled us to characterize the importance of each physical factor in determining macrophyte occurrence and distribution. As a result, a predictive map to forecast aquatic plant distribution at the shoreline scale was obtained. Results: Anthropogenic disturbances were less important parameters than natural physical variables in structuring the distribution of lakeshore macrophytes. Within natural factors, wave-induced sediment re-suspension and slope had the most impact; nevertheless, the presence of swimming areas seemed to have a strong impact on aquatic habitats, being correlated with the total absence of aquatic vegetation. The predictive map obtained through the model spatially defined the position and occurrence of suitable sites for the settlement of both invasive and rare and endangered species. Conclusions: In this study, natural disturbances play a major role in structuring aquatic plant distribution over physical anthropogenic factors. The model contributes to improving knowledge on plant communities with respect to local hydrodynamic and morphological features of lakeshores. Furthermore, the model provides a predictive map as a useful tool for the management of aquatic vegetation in temperate shallow lakes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018 International Association for Vegetation Science Questions: Do natural and anthropogenic physical disturbances equally affect the distribution of aquatic plant communities? Can hydrodynamic and geomorphological features be used to predict the establishment of macrophyte communities at the shoreline scale?. Locations: Two large, shallow lakes, southwest France. Methods: Based on field observations (vegetation occurrence and anthropogenic modifications of the shore) and data generated by a geographic information system (wave exposure, wave-induced sediment re-suspension, slope and land cover), we defined sites and community groups using cluster and indicator species analyses. The groups were then analysed by means of a statistical classifier (Random Forest). These different steps in data treatment enabled us to characterize the importance of each physical factor in determining macrophyte occurrence and distribution. As a result, a predictive map to forecast aquatic plant distribution at the shoreline scale was obtained. Results: Anthropogenic disturbances were less important parameters than natural physical variables in structuring the distribution of lakeshore macrophytes. Within natural factors, wave-induced sediment re-suspension and slope had the most impact; nevertheless, the presence of swimming areas seemed to have a strong impact on aquatic habitats, being correlated with the total absence of aquatic vegetation. The predictive map obtained through the model spatially defined the position and occurrence of suitable sites for the settlement of both invasive and rare and endangered species. Conclusions: In this study, natural disturbances play a major role in structuring aquatic plant distribution over physical anthropogenic factors. The model contributes to improving knowledge on plant communities with respect to local hydrodynamic and morphological features of lakeshores. Furthermore, the model provides a predictive map as a useful tool for the management of aquatic vegetation in temperate shallow lakes. |
Portois, C; Boeije, C S; Bertin, H J; Atteia, O Foam for Environmental Remediation: Generation and Blocking Effect Article de journal Transport in Porous Media, 124 (3), p. 787–801, 2018. @article{Portois2018a, title = {Foam for Environmental Remediation: Generation and Blocking Effect}, author = {C Portois and C S Boeije and H J Bertin and O Atteia}, doi = {10.1007/s11242-018-1097-z}, year = {2018}, date = {2018-01-01}, journal = {Transport in Porous Media}, volume = {124}, number = {3}, pages = {787--801}, abstract = {textcopyright 2018, Springer Science+Business Media B.V., part of Springer Nature. Foam injection is widely used in petroleum industry for enhanced oil recovery, but has received limited attention for the application of environmental remediation at the field scale. This study analyses the use of foam as a blocking agent, i.e. to confine a source zone of contaminant in groundwater. Laboratory experiments in 1D porous media with a commercially available biodegradable surfactant performed on columns using pre-generated foam show that the foam reduces the relative water permeability krw by a factor of 100\textendash1000. krw was measured right after foam placement by injecting only water (drainage test) and corresponding to the relative permeability of water in presence of foam. A comparison to a theoretical two-phase flow in porous medium shows that the Van Genuchten equation can be used to estimate the krw value. In the field, experiments done on two different porous media and using three different injection techniques (co-injection, surfactant alternating gas, pre-generation) show a clear confining ability of the produced foam. A krw reduction by a factor of 1000 is observed very close to the well and close to 100 at 1 m of this well. These values were obtained with a much weaker foam than the laboratory one in order to allow the injection at shallow depth environmental compatible ssure (≤ 4 bar). The reduction in water relative permeability can occur in the presence of a foam that does not cause an extreme reduction of the mobility, indicating that this reduction does not depend on resistance factor (RF) values. There is potential for improvement of the foam as it loses its efficiency with increasing distance from the injection well.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2018, Springer Science+Business Media B.V., part of Springer Nature. Foam injection is widely used in petroleum industry for enhanced oil recovery, but has received limited attention for the application of environmental remediation at the field scale. This study analyses the use of foam as a blocking agent, i.e. to confine a source zone of contaminant in groundwater. Laboratory experiments in 1D porous media with a commercially available biodegradable surfactant performed on columns using pre-generated foam show that the foam reduces the relative water permeability krw by a factor of 100–1000. krw was measured right after foam placement by injecting only water (drainage test) and corresponding to the relative permeability of water in presence of foam. A comparison to a theoretical two-phase flow in porous medium shows that the Van Genuchten equation can be used to estimate the krw value. In the field, experiments done on two different porous media and using three different injection techniques (co-injection, surfactant alternating gas, pre-generation) show a clear confining ability of the produced foam. A krw reduction by a factor of 1000 is observed very close to the well and close to 100 at 1 m of this well. These values were obtained with a much weaker foam than the laboratory one in order to allow the injection at shallow depth environmental compatible ssure (≤ 4 bar). The reduction in water relative permeability can occur in the presence of a foam that does not cause an extreme reduction of the mobility, indicating that this reduction does not depend on resistance factor (RF) values. There is potential for improvement of the foam as it loses its efficiency with increasing distance from the injection well. |
Al-Ajrah, Saja; Lafdi, Khalid; Liu, Yufei; Le Coustumer, Philippe Fabrication of ceramic nanofibers using polydimethylsiloxane and polyacrylonitrile polymer blends Article de journal Journal of Applied Polymer Science, 135 (10), p. 45967, 2018. @article{Al-Ajrah2018, title = {Fabrication of ceramic nanofibers using polydimethylsiloxane and polyacrylonitrile polymer blends}, author = {Saja Al-Ajrah and Khalid Lafdi and Yufei Liu and Philippe {Le Coustumer}}, url = {http://doi.wiley.com/10.1002/app.45967 http://onlinelibrary.wiley.com/doi/10.1002/app.45967/full}, doi = {10.1002/app.45967}, year = {2018}, date = {2018-03-01}, journal = {Journal of Applied Polymer Science}, volume = {135}, number = {10}, pages = {45967}, abstract = {textcopyright 2017 Wiley Periodicals, Inc. Nanofibers with several hundred of nanometers were successfully fabricated using electrospinning process and a mixture of two types of polymers which are: polydimethylsiloxane and polyacrylonitrile as precursors. After stabilization and carbonization at 1000 °C, three phases which are: silicon carbide (SiC), carbon, and oxy-SiC were presented. Spectroscopic and microscopic techniques had confirmed the presence of nanocrystalline SiC and turbostratic carbons. These phases formed an intertwined network at the nanometric scale. In addition, the resulted fibers showed a core-skin effect with skin richer in carbon and a core mainly dominated by silicon-based phases in the form SiC or SiOC ceramics. A significant improvement was observed in both tensile strength and elastic modulus in these hybrid fibers. In term of crystallography, these nanofibers seem to exhibit similar microstructure that was observed in Nicalon fiber. However, it was difficult to determine the ratio of these phases and their influence on the physical properties of these hybrid fibers. textcopyright 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45967.}, keywords = {}, pubstate = {published}, tppubtype = {article} } textcopyright 2017 Wiley Periodicals, Inc. Nanofibers with several hundred of nanometers were successfully fabricated using electrospinning process and a mixture of two types of polymers which are: polydimethylsiloxane and polyacrylonitrile as precursors. After stabilization and carbonization at 1000 °C, three phases which are: silicon carbide (SiC), carbon, and oxy-SiC were presented. Spectroscopic and microscopic techniques had confirmed the presence of nanocrystalline SiC and turbostratic carbons. These phases formed an intertwined network at the nanometric scale. In addition, the resulted fibers showed a core-skin effect with skin richer in carbon and a core mainly dominated by silicon-based phases in the form SiC or SiOC ceramics. A significant improvement was observed in both tensile strength and elastic modulus in these hybrid fibers. In term of crystallography, these nanofibers seem to exhibit similar microstructure that was observed in Nicalon fiber. However, it was difficult to determine the ratio of these phases and their influence on the physical properties of these hybrid fibers. textcopyright 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45967. |
Moragas, Mar; Vergés, Jaume; Saura, Eduard; Martín-Martín, Juan-Diego; Messager, Grégoire; Merino-Tomé, Óscar; Suárez-Ruiz, Isabel; Razin, Philippe; Grélaud, Carine; Malaval, Manon; Joussiaume, Rémi; Hunt, David William Jurassic rifting to post-rift subsidence analysis in the Central High Atlas and its relation to salt diapirism Article de journal Basin Research, 30 (S1), p. 336–362, 2018, ISSN: 0950091X. @article{Moragas2018, title = {Jurassic rifting to post-rift subsidence analysis in the Central High Atlas and its relation to salt diapirism}, author = {Mar Moragas and Jaume Verg\'{e}s and Eduard Saura and Juan-Diego Mart\'{i}n-Mart\'{i}n and Gr\'{e}goire Messager and \'{O}scar Merino-Tom\'{e} and Isabel Su\'{a}rez-Ruiz and Philippe Razin and Carine Gr\'{e}laud and Manon Malaval and R\'{e}mi Joussiaume and David William Hunt}, url = {http://doi.wiley.com/10.1111/bre.12223}, doi = {10.1111/bre.12223}, issn = {0950091X}, year = {2018}, date = {2018-02-01}, journal = {Basin Research}, volume = {30}, number = {S1}, pages = {336--362}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Amor, Ines Ben Slimene Ben; Chehata, Nesrine; Bailly, Jean-Stephane; Farah, Imed Riadh; Lagacherie, Philippe Parcel-Based Active Learning for Large Extent Cultivated Area Mapping Article de journal IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 11 (1), p. 79–88, 2018, ISSN: 1939-1404. @article{Amor2018, title = {Parcel-Based Active Learning for Large Extent Cultivated Area Mapping}, author = {Ines Ben Slimene Ben Amor and Nesrine Chehata and Jean-Stephane Bailly and Imed Riadh Farah and Philippe Lagacherie}, url = {http://ieeexplore.ieee.org/document/8052487/}, doi = {10.1109/JSTARS.2017.2751148}, issn = {1939-1404}, year = {2018}, date = {2018-01-01}, journal = {IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing}, volume = {11}, number = {1}, pages = {79--88}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Vincent, Aude; Violette, Sophie Why seawater intrusion has not yet occurred in the Kaluvelli-Pondicherry basin, Tamil Nadu, India Article de journal Hydrogeology Journal, 2017. @article{vincent_why_2017, title = {Why seawater intrusion has not yet occurred in the Kaluvelli-Pondicherry basin, Tamil Nadu, India}, author = {Aude Vincent and Sophie Violette}, doi = {10.1007/s10040-017-1558-4}, year = {2017}, date = {2017-01-01}, journal = {Hydrogeology Journal}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Valois, Remi; Cousquer, Yohann; Schmutz, Myriam; Pryet, Alexandre; Delbart, Célestine; Dupuy, Alain Characterizing Stream-Aquifer Exchanges with Self-Potential Measurements Article de journal Groundwater, p. –, 2017, ISSN: 1745-6584. @article{Valoisetal2017, title = {Characterizing Stream-Aquifer Exchanges with Self-Potential Measurements}, author = {Remi Valois and Yohann Cousquer and Myriam Schmutz and Alexandre Pryet and C\'{e}lestine Delbart and Alain Dupuy}, url = {http://dx.doi.org/10.1111/gwat.12594}, doi = {10.1111/gwat.12594}, issn = {1745-6584}, year = {2017}, date = {2017-01-01}, journal = {Groundwater}, pages = {--}, publisher = {Blackwell Publishing Ltd}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Cousquer, Yohann; Pryet, Alexandre; Flipo, Nicolas; Delbart, Cￃﾩlestine; Dupuy, Alain Estimating River Conductance from Prior Information to Improve Surface-Subsurface Model Calibration Article de journal Groundwater, 2017, ISSN: 0017-467X. @article{Cousqueretal2017, title = {Estimating River Conductance from Prior Information to Improve Surface-Subsurface Model Calibration}, author = {Yohann Cousquer and Alexandre Pryet and Nicolas Flipo and Cￃﾩlestine Delbart and Alain Dupuy}, url = {http://dx.doi.org/10.1111/gwat.12492}, doi = {10.1111/gwat.12492}, issn = {0017-467X}, year = {2017}, date = {2017-01-01}, journal = {Groundwater}, publisher = {Wiley-Blackwell}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Delottier, H; Pryet, A; Dupuy, A Why Should Practitioners be Concerned about Predictive Uncertainty of Groundwater Management Models? Article de journal Water Resources Management, 31 (1), p. 61￢ﾀﾓ73, 2016, ISSN: 1573-1650. @article{Delottieretal2016, title = {Why Should Practitioners be Concerned about Predictive Uncertainty of Groundwater Management Models?}, author = {H Delottier and A Pryet and A Dupuy}, url = {http://dx.doi.org/10.1007/s11269-016-1508-2}, doi = {10.1007/s11269-016-1508-2}, issn = {1573-1650}, year = {2016}, date = {2016-10-01}, journal = {Water Resources Management}, volume = {31}, number = {1}, pages = {61￢ﾀﾓ73}, publisher = {Springer Nature}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Domínguez, C G; Pryet, A; Vera, García M; Gonzalez, A; Chaumont, C; Tournebize, J; Villacis, M; d'Ozouville, N; Violette, S Comparison of deep percolation rates below contrasting land covers with a joint canopy and soil model Article de journal Journal of Hydrology, 532 , p. 65￢ﾀﾓ79, 2016, ISSN: 0022-1694. @article{Dominguez2016, title = {Comparison of deep percolation rates below contrasting land covers with a joint canopy and soil model}, author = {C G Dom\'{i}nguez and A Pryet and M Garc\'{i}a Vera and A Gonzalez and C Chaumont and J Tournebize and M Villacis and N d'Ozouville and S Violette}, url = {http://dx.doi.org/10.1016/j.jhydrol.2015.11.022}, doi = {10.1016/j.jhydrol.2015.11.022}, issn = {0022-1694}, year = {2016}, date = {2016-01-01}, journal = {Journal of Hydrology}, volume = {532}, pages = {65￢ﾀﾓ79}, publisher = {Elsevier BV}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Malcuit, E; Atteia, O; Larroque, F; Franceschi, M; Pryet, A On the role of low-permeability beds in the acquisition of F and SO4 concentrations in a multi-layer aquifer, South-West France Article de journal Journal of Contaminant Hydrology, 169 , p. 37￢ﾀﾓ49, 2014, ISSN: 0169-7722. @article{Malcuit2014, title = {On the role of low-permeability beds in the acquisition of F and SO4 concentrations in a multi-layer aquifer, South-West France}, author = {E Malcuit and O Atteia and F Larroque and M Franceschi and A Pryet}, url = {http://dx.doi.org/10.1016/j.jconhyd.2014.05.001}, doi = {10.1016/j.jconhyd.2014.05.001}, issn = {0169-7722}, year = {2014}, date = {2014-11-01}, journal = {Journal of Contaminant Hydrology}, volume = {169}, pages = {37￢ﾀﾓ49}, publisher = {Elsevier BV}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Pryet, A; Labarthe, B; Saleh, F; Akopian, M; Flipo, N Reporting of Stream-Aquifer Flow Distribution at the Regional Scale with a Distributed Process-Based Model Article de journal Water Resources Management, 29 (1), p. 139-159, 2014, ISSN: 1573-1650. @article{Pryet2014, title = {Reporting of Stream-Aquifer Flow Distribution at the Regional Scale with a Distributed Process-Based Model}, author = {A Pryet and B Labarthe and F Saleh and M Akopian and N Flipo}, url = {http://dx.doi.org/10.1007/s11269-014-0832-7}, doi = {10.1007/s11269-014-0832-7}, issn = {1573-1650}, year = {2014}, date = {2014-10-01}, journal = {Water Resources Management}, volume = {29}, number = {1}, pages = {139-159}, publisher = {Springer Nature}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Pryet, A; d'Ozouville, N; Violette, S; Deffontaines, B; Auken, E Hydrogeological settings of a volcanic island (San Cristóbal, Galapagos) from joint interpretation of airborne electromagnetics and geomorphological observations Article de journal Hydrology and Earth System Sciences, 16 (12), p. 4571-4579, 2012, ISSN: 1607-7938. @article{Pryet2012a, title = {Hydrogeological settings of a volcanic island (San Crist\'{o}bal, Galapagos) from joint interpretation of airborne electromagnetics and geomorphological observations}, author = {A Pryet and N d'Ozouville and S Violette and B Deffontaines and E Auken}, url = {http://dx.doi.org/10.5194/hess-16-4571-2012}, doi = {10.5194/hess-16-4571-2012}, issn = {1607-7938}, year = {2012}, date = {2012-12-01}, journal = {Hydrology and Earth System Sciences}, volume = {16}, number = {12}, pages = {4571-4579}, publisher = {Copernicus GmbH}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Pryet, Alexandre; Domínguez, Christian; Tomai, Pilar Fuente; Chaumont, Cédric; d'Ozouville, Noémi; Villacís, Marcos; Violette, Sophie Quantification of cloud water interception along the windward slope of Santa Cruz Island, Galapagos (Ecuador) Article de journal Agricultural and Forest Meteorology, 161 , p. 94-106, 2012, ISSN: 0168-1923. @article{Pryet2012b, title = {Quantification of cloud water interception along the windward slope of Santa Cruz Island, Galapagos (Ecuador)}, author = {Alexandre Pryet and Christian Dom\'{i}nguez and Pilar Fuente Tomai and C\'{e}dric Chaumont and No\'{e}mi d'Ozouville and Marcos Villac\'{i}s and Sophie Violette}, url = {http://dx.doi.org/10.1016/j.agrformet.2012.03.018}, doi = {10.1016/j.agrformet.2012.03.018}, issn = {0168-1923}, year = {2012}, date = {2012-08-01}, journal = {Agricultural and Forest Meteorology}, volume = {161}, pages = {94-106}, publisher = {Elsevier BV}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Pryet, Alexandre; Ramm, James; Chilès, Jean-Paul; Auken, Esben; Deffontaines, Benoit; Violette, Sophie 3D resistivity gridding of large AEM datasets: A step toward enhanced geological interpretation Article de journal Journal of Applied Geophysics, 75 (2), p. 277-283, 2011, ISSN: 0926-9851. @article{Pryet2011, title = {3D resistivity gridding of large AEM datasets: A step toward enhanced geological interpretation}, author = {Alexandre Pryet and James Ramm and Jean-Paul Chil\`{e}s and Esben Auken and Benoit Deffontaines and Sophie Violette}, url = {http://dx.doi.org/10.1016/j.jappgeo.2011.07.006}, doi = {10.1016/j.jappgeo.2011.07.006}, issn = {0926-9851}, year = {2011}, date = {2011-10-01}, journal = {Journal of Applied Geophysics}, volume = {75}, number = {2}, pages = {277-283}, publisher = {Elsevier BV}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
CONFERENCES
inproceedings |
Boukir, Samia; Mellor, Andrew Ensemble diversity analysis on remote sensing data classification using random forests Inproceedings Proceedings - International Conference on Image Processing, ICIP, 2018, ISSN: 15224880. @inproceedings{Boukir2018, title = {Ensemble diversity analysis on remote sensing data classification using random forests}, author = {Samia Boukir and Andrew Mellor}, doi = {10.1109/ICIP.2017.8296492}, issn = {15224880}, year = {2018}, date = {2018-01-01}, booktitle = {Proceedings - International Conference on Image Processing, ICIP}, abstract = {textcopyright 2017 IEEE. Ensemble classifiers perform better than single classifiers and result in reduced generalisation error. Diversity across ensemble members is a key factor affecting classification performance. Here, an original exploration of the relationship between ensemble diversity and classification performance applied to large area remote sensing classification, using random forests, is undertaken. Results demonstrate how targeting lower margin training samples is both a strategy for inducing diversity in ensemble classifiers and achieving better classifier performance for difficult or rare classes, and a way to reduce data redundancy.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } textcopyright 2017 IEEE. Ensemble classifiers perform better than single classifiers and result in reduced generalisation error. Diversity across ensemble members is a key factor affecting classification performance. Here, an original exploration of the relationship between ensemble diversity and classification performance applied to large area remote sensing classification, using random forests, is undertaken. Results demonstrate how targeting lower margin training samples is both a strategy for inducing diversity in ensemble classifiers and achieving better classifier performance for difficult or rare classes, and a way to reduce data redundancy. |
Violette, Sophie; Vincent, Aude; DÓzouville, Noemi; de Marsily, Ghislain; Gassama, Nathalie; Dia, Aline; Jendrzejewski, Nathalie Comprehensive View of the Hydrologic Cycle of the Kaliveli-Pondicherry Sedimentary Basin, Tamil Nadu, India Inproceedings p. 24–31, Auroville, 2004. @inproceedings{violette_comprehensive_2004, title = {Comprehensive View of the Hydrologic Cycle of the Kaliveli-Pondicherry Sedimentary Basin, Tamil Nadu, India}, author = {Sophie Violette and Aude Vincent and Noemi D\'{O}zouville and Ghislain de Marsily and Nathalie Gassama and Aline Dia and Nathalie Jendrzejewski}, year = {2004}, date = {2004-01-01}, pages = {24--31}, address = {Auroville}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Quo, L; Boukir, S Building an ensemble classifier using ensemble margin. Application to image classification Inproceedings Proceedings - International Conference on Image Processing, ICIP, p. 4492–4496, 2018, ISBN: 9781509021758. @inproceedings{Quo2018, title = {Building an ensemble classifier using ensemble margin. Application to image classification}, author = {L Quo and S Boukir}, doi = {10.1109/ICIP.2017.8297132}, isbn = {9781509021758}, year = {2018}, date = {2018-01-01}, booktitle = {Proceedings - International Conference on Image Processing, ICIP}, volume = {2017-Septe}, pages = {4492--4496}, abstract = {textcopyright 2017 IEEE. Bagging is a simple and powerful ensemble method which relies on bootstrap sampling over training data to produce diversity. Indeed, ensembles generalise better when their members form a diverse and accurate set. In this paper, the margin theory is exploited to select training instances for bagging. The selection of training data is performed using a new iterative guided bagging algorithm exploiting low margin instances. This method has been successfully applied to image data. Results show that low margin instances have a major influence on forming an appropriate training set to build reliable ensemble classifiers, leading to a significant increase in both overall and per-class accuracies.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } textcopyright 2017 IEEE. Bagging is a simple and powerful ensemble method which relies on bootstrap sampling over training data to produce diversity. Indeed, ensembles generalise better when their members form a diverse and accurate set. In this paper, the margin theory is exploited to select training instances for bagging. The selection of training data is performed using a new iterative guided bagging algorithm exploiting low margin instances. This method has been successfully applied to image data. Results show that low margin instances have a major influence on forming an appropriate training set to build reliable ensemble classifiers, leading to a significant increase in both overall and per-class accuracies. |