Use of X-ray diffractometry and analysis of the atomic pair distribution function to study the interactions between smectite and emerging organic pollutants

Aristilde L.; Lanson B.; Charlet L. (2013) Langmuir, 29,International audienceMany emerging pollutants from pharmaceuticals, pesticides or products for domestic or industrial use are found in the environment and pose the problem of achieving good chemical or ecological status of this system. In the environment, these pollutants can interact with different phases that make up soils or sediments, such as organic matter, natural oxyhydroxides, or clay minerals. However, to date there is very little data describing the reaction mechanisms and the nature of the bonds involved in these interactions (Aristilde et al., 2013). In this context, and in order to improve the state of knowledge on the behaviour of emerging pollutants in the environment, we propose to study the adsorption of two organic molecules, sulfamethoxazole (SMX) and metoprolol tartrate (MPT), considered as emerging pollutants onto a Ca-montmorillonite. SMX and MPT are an antibiotic and a cardioselective beta blocker, respectively, and are widely found in soils and aquatic ecosystems, with concentrations up to several micrograms per liter. In this study, SMX and MPT have been in contact with Ca-montmorillonite for 24 hours at pH 6. Different concentrations, varying from0.1 mg/L to 1 mg/L, were studied. The resulting solids were characterized by X-ray powder diffractometry at constant temperature (25°C) and different humidities (from 10 to 90%). Initial results showed differences in the position (interlayer distance) of the 001 reflection of montmorillonite. In the presence of organic molecules and at low humidity, the interlayer distance is greater than that observed in the case of Ca-montmorillonite. This result indicates that the interlayer space has been modified, in particular by the insertion of organic molecules. For relative humidities above 50%, there are no more differences between the samples with and without organic molecules. Due to their small size, organic molecules do not induce significant swelling when the interlayer space contains many water molecules. To complete this study, analyses of the atomic pair distribution function (PDF), were carried out on the starting materials (Ca-montmorillonite, SMX and MPT) as well as on the montmorillonite after having been in contact with the organic molecules. The comparison between the PDFs confirms the adsorption of organic molecules since characteristic peaks of C-H bonds belonging to the CH 3 groups of SMX and MPT are visible on the montmorillonite PDFs after contact with the organic molecules. However, the interatomic distances between C and H seem to be slightly modified indicating a potential reaction mechanism involving these groups. Aristilde L.; Lanson B.; Charlet L. (2013) Langmuir, 29, 4492-4501

Assessing the potential impacts of CO2 leakage on fresh groundwater: from experiments to predictive models

International audienceGeological storage of CO2 in deep saline aquifers is one of the options considered for the mitigation of CO2 emissions into the atmosphere. A deep geological CO2 storage is not expected to leak, however, potential impacts of CO2 leakage into aquifers overlying deep storage site have to be addressed. . A better understanding on how it could affect groundwater quality, aquifer minerals and trace elements mobilization is necessary to fully characterize a future storage site. Moreover, this characterization is required to evaluate monitoring and remediation plans. As part of the collaborative project CIPRES co-funded by the ANR, we present reactive transport works dedicated to the impact assessment of CCS on fresh groundwaters.In a 3D model using ToughReact v.3, we perform different CO2 leakage scenarios in a confined aquifer. This study focuses on theAlbian aquifer that is a strategic water resource in the Paris Basin. The model is based on groundwater and rock chemistry of the Albian green sand layer (i.e. Quartz, Glauconite, Kaolinite) at 700 m deep. The geochemical model was elaborated from experimental data (Barsotti et al. 2016 and Humez et al. 2014) taking into account kinetics for mineral dissolution, ion exchange and surface complexation processes. The numerical mesh consists of 200 m× 500 m × 60 m. A grid refinement near the leakage point is considered to focus on local phenomena e.g. secondary precipitation, surface processes. The total mesh comprises 21600 cells. The results highlight the importance of sorption processes on trace element mobilization and transport (As, Zn and Ni) in fresh groundwater. Moreover, we distinguish different geochemical behavior (CO2 plume shape, secondary precipitation, desorption...) occurring at different depth and length scale according to the horizontal flow rates and density effects that are influenced by hydrodynamic properties (regional gradient). Coupling geochemical processes and regional flows influence on water chemistry evolution allows to strengthen monitoring and verification plan as well remediation perspectives

Implementation of agronomical and geochemical modules into a 3D groundwater code for assessing nitrate storage and transport through unconfined Chalk aquifer

International audienceChalk aquifer is the main water resource for domestic water supply in many parts in northern France. In same basin, groundwater is frequently affected by quality problems concerning nitrates. Often close to or above the drinking water standards, nitrate concentration in groundwater is mainly due to historical agriculture practices, combined with leakage and aquifer recharge through the vadose zone. The complexity of processes occurring into such an environment leads to take into account a lot of knowledge on agronomy, geochemistry and hydrogeology in order to understand, model and predict the spatiotemporal evolution of nitrate content and provide a decision support tool for the water producers and stakeholders. To succeed in this challenge, conceptual and numerical models representing accurately the Chalk aquifer specificity need to be developed. A multidisciplinary approach is developed to simulate storage and transport from the ground surface until groundwater. This involves a new agronomic module " NITRATE " (NItrogen TRansfer for Arable soil to groundwaTEr), a soil-crop model allowing to calculate nitrogen mass balance in arable soil, and the " PHREEQC " numerical code for geochemical calculations, both coupled with the 3D transient groundwater numerical code " MARTHE ". Otherwise, new development achieved on MARTHE code allows the use of dual porosity and permeability calculations needed in the fissured Chalk aquifer context. This method concerning the integration of existing multidisciplinary tools is a real challenge to reduce the number of parameters by selecting the relevant equations and simplifying the equations without altering the signal. The robustness and the validity of these numerical developments are tested step by step with several simulations constrained by climate forcing, land use and nitrogen inputs over several decades. In the first time, simulations are performed in a 1D vertical unsaturated soil column for representing experimental nitrates vertical soil profiles (0-30m depth experimental measurements in Somme region). In the second time, this approach is used to simulate with a 3D model a drinking water catchment area in order to compared nitrate contents time series calculated and measured in the domestic water pumping well since 1995 (field in northern France – Avre Basin region). This numerical tool will help the decision-making in all activities in relation with water uses

Multidisciplinary subsurface monitoring for a better understanding of Soil Aquifer Treatment capacity applied on coastal operational wastewater treatment plant (Agon-Coutainville, France)

International audienceUnconfined coastal aquifers are potentially subject to both saline intrusion near the seashore and over discharge of treated wastewater in the surficial environment during the tourist season. In Agon-Coutainville (Normandy, France), managed aquifer recharge (MAR) system, combined with Soil Aquifer Treatment (SAT), was integrated as part of the full-scale operational wastewater treatment plant. Such integrated natural/engineered water treatment system ensure the sustainability of the seaside activities (seafood production, beach) and locally supply freshwater for the irrigational needs of the golf course. Concerning the MAR system, the secondary treated wastewater is infiltrated alternatively into three natural reed bed areas before reaching the sand dune aquifer and thus to enhance the quantity of freshwater in the aquifer. Treated wastewater potentially contains various compounds (chemical, virus, pathogen) which can, however, affect the groundwater quality. Nevertheless, some of these compounds are partly removed, during the SAT. To assess performance and efficiency of the integrated system in the natural environment, we have designed and performed an innovating and multidisciplinary monitoring dedicated to 1) spatial evolution of the freshwater generating by the MAR system, 2) mean residence time of water during SAT and 3) potential reactivity occurring during SAT. Spatial field campaigns and tracer tests were conducted by associating classical and innovative approaches including physico-chemical measurements and quantitative analyses, non target analysis for screening organic compounds, ecotoxicological bioassays, online biomonitoring BACTcontrol® system to detect fecal contamination and online system monitoring device dedicated to saline intrusion. Results show that the MAR system provides a freshwater barrier in the aquifer which is seasonally affected by saline intrusion. A part of the aquifer is assessed for freshwater potential production regardless of the natural and anthropogenic recharge. SAT mean residence time is around two weeks that allows SAT reactivity and thus increases quality of the pumped groundwater. This novel subsurface monitoring provides a better understanding of the SAT capacity to enhance the quantity of freshwater and improve its quality

Exogenous LRRK2G2019S induces parkinsonian-like pathology in a nonhuman primate

Parkinson’s disease (PD) is the second most prevalent neurodegenerative disease among the elderly. To understand pathogenesis and to test therapies, animal models that faithfully reproduce key pathological PD hallmarks are needed. As a prelude to developing a model of PD, we tested the tropism, efficacy, biodistribution, and transcriptional impact of canine adenovirus type 2 (CAV-2) vectors in the brain of Microcebus murinus, a nonhuman primate that naturally develops neurodegenerative lesions. We show that introducing helper-dependent (HD) CAV-2 vectors results in long-term, neuron-specific expression at the injection site and in afferent nuclei. Although HD CAV-2 vector injection induced a modest transcriptional response, no significant adaptive immune response was generated. We then generated and tested HD CAV-2 vectors expressing LRRK2 (leucine-rich repeat kinase 2) and LRRK2 carrying a G2019S mutation (LRRK2G2019S), which is linked to sporadic and familial autosomal dominant forms of PD. We show that HD-LRRK2G2019S expression induced parkinsonian-like motor symptoms and histological features in less than 4 months

Fate of TiO2 nanoparticles in the aquatic environment in the presence of anthropogenic compounds

International audienceThe increasing production and use of nanoparticles (NP) in consumer products inevitably lead to ENP emissions into the environment. The physicochemical properties of NP depend on various parameters (e.g. pH, cations, IS). In natural waters, the stability of NP can vary as a function of a sum of these parameters and occurs by one of the numerous scenarios. In particular, the presence of anthropogenic organic molecules (AOM) can change the NP fate. Also, the presence of NP may affect the organic pollutants (fate and toxicity). The main objective of the work was to study the aggregation of TiO2 NP (pure hydrophilic 100 % rutile and pure hydrophilic 100 % anatase, 5−30 nm) in the presence of the most frequently occur and representative pesticides (glyphosate, AMPA, 2.4D) in natural waters considering lab experiments under relevant aqueous conditions (pH, ionic strength, presence and concentrations of mono- and bivalent cations). The presence of pesticides affected TiO2 NP homoaggregation in solutions (IS=10-3M - 10-2M) with pH values below the NP point of zero charge (PZC) for the anatase NPs (pH=6.5) and with pH values above the NP PZC for the rutile NP (pH=4.5). No changes in NP aggregation were observed in very low (IS=10-4M) or very high (IS= 10-1M) ionic strength solutions. The presence of the pesticides caused a significant modification of the NP surface charge (zeta potential) over a large range of salt concentrations (IS=10-4M - 10-1M). Compared to mono-valent cations (Na+), bi-valent cations (Ca2+) favor an increase in zeta potential of NP (anatase and rutile) at pH 8. There is no significant difference between at pH 5. Finally, these results demonstrated that, among the studied AOMs, glyphosate (with 4 pKa-s from 0.8 to 11) affects NP aggregation/stabilization in a wider range of physicochemical conditions. Overall, these results will aid in the evaluation of potential environmental risks posed by engineered NP in the aquatic environments exposed to pesticide load

Processus rhizosphériques déterminant la disponibilité en phosphore : apport de la modélisation mécaniste géochimique

Root-induced chemical processes are recognized as a major strategy developed by plants to enhance phosphorus (P) availability and thus to promote P acquisition. However, the exact influence of these root-induced chemical processes is still poorly understood and quantified. The present study aimed at investigating the influence of root-induced chemical processes, especially root-induced pH changes, on P availability in the rhizosphere. In this work, we used a set of mechanistic adsorption models (« 1-pK triple plane », ion-exchange and Nica-Donnan) within the framework of the component additive approach in order to simulate the effects of root activity on P availability. First, we described the effects of pH on P availability in several soils unaffected by roots, a Chromic Cambisol and a Luvisol. The Luvisol showed different concentrations in inorganic P because of a long-term fertilisation trial. In the rhizosphere of durum wheat (Triticum tu rgidum durum L.) grown on these two soils, we found that calcium (Ca) uptake, in addition to P uptake and root-induced alkalisation, controlled to various extents the changes of soil P availability. Calcium uptake markedly increased P availability by decreasing the promoting effect of Ca adsorption on P adsorption. The relative influence of these three root processes depended on the solution composition (especially concentration of Ca and pH). Our simulations showed the relationship between changes in P availability and the speciation of adsorbed P onto the different soil minerals. Soil mineralogy, especially the relative abundance of illite vs. Fe oxides, controlled the influence of root processes by regulating the contribution of soil minerals to P adsorption. By identifying a novel root-induced processes, namely the Ca uptake, and describing its influence on P availability, our results demonstrate the ability of surface complexation models to predict the effects of root-i nduced processes on P availability in soils.Les processus rhizosphériques sont reconnus comme une des stratégies majeures élaborées par les plantes afin d'augmenter la disponibilité en phosphore (P) et ainsi améliorer leur nutrition phosphatée. Pourtant, l'effet exact de ces processus est encore mal caractérisé et quantifié. L'objectif de ces travaux a été de déterminer le rôle exercé par les modifications chimiques induites par les racines, particulièrement la modification de pH, dans les changements de disponibilité en P dans la rhizosphère. Pour ce faire, nous avons utilisé des modèles mécanistes géochimiques (« triple plane », échange d'ion et Nica-Donnan) en considérant une approche additive pour simuler l'effet de l'activité racinaire sur la disponibilité en P. Dans une première étape, nous avons caractérisé l'effet du pH sur la disponibilité en P dans plusieurs sols, un Cambisol et un Luvisol. Le Luvisol présentait deux concentrations en P inorganique contrastées en raison d'un essai de fertilisation phosphatée longue durée. Dans la rhizosphère du blé dur (Triticum turgidum durum L.) cultivé sur les mêmes sols, nous avons caractérisé qu'en plus de l'alcalinisation, le prélèvement en P et surtout en calcium (Ca) sont les processus rhizosphériques responsables du changement de disponibilité en P observé. Le prélèvement du Ca favorise l'augmentation de la disponibilité en P dans la rhizosphère, en diminuant l'effet promoteur du processus d'adsorption-désorption du Ca sur celui du P. L'influence relative de ces trois processus rhizosphériques dépend toutefois de la composition chimique de la solution du sol (concentration en Ca et pH en particulier). Nos simulations mettent également en évidence la relation entre les changements de disponibilité en P est la distribution du P adsorbé sur les différentes phases minérales. La minéralogie du sol, spécialement l'abondance relative d'illite vs. les oxydes de fer, contrôle l'influence des processus rhizosphériques en déterminant les minéraux impliqués dans l'adsorption du P. A travers l'identification d'un nouveau processus rhizosphérique découlant du prélèvement en Ca et de ses effets sur la disponibilité en P, nos résultats démontrent la validité des modèles géochimiques pour prédire l'influence des processus rhizosphériques déterminant la disponibilité en

Rhizosphere processes controlling phosphorus availability : mechanisitic geochemical modelling approach

Les processus rhizosphériques sont reconnus comme une des stratégies majeures élaborées par les plantes afin d'augmenter la disponibilité en phosphore (P) et ainsi améliorer leur nutrition phosphatée. Pourtant, l'effet exact de ces processus est encore mal caractérisé et quantifié. L'objectif de ces travaux a été d e déterminer le rôle exercé par les modifications chimiques induites par les racines, particulièrement la modification de pH, dans les changements de disponibilité en P dans la rhizosphère. Pour ce faire, nous avons utilisé des modèles mécanistes géochimiques (« triple plane », échange d'ion et Nica-Donnan) en considérant une approche additive pour simuler l'effet de l'activité racinaire sur la disponibilité en P. Dans une première étape, nous avons caractérisé l'effet du pH sur la disponibilité en P dans plusieurs sols, un Cambisol et un Luvisol. Le Luvisol présentait deux concentrations en P inorganique contrastées en raison d'un essai de fertilisation phosphatée longue durée. Dans la rhizosphère du blé dur (Triticum turgidum durum L.) cultivé sur les mêmes sols, nous avons caractérisé qu'en plus de l'alcalinisation, le prélèvement en P et surtout en calcium (Ca) sont les processus rhizosphériques responsables du changement de disponibilit é en P observé. Le prélèvement du Ca favorise l'augmentation de la disponibilité en P dans la rhizosphère, en diminuant l'effet promoteur du processus d'adsorption-désorption du Ca sur celui du P. L'influence relative de ces trois processus rhizosphériques dépend toutefois de la composition chimique de la solution du sol (concentration en Ca et pH en particulier). Nos simulations mettent également en évidence la relation entre les changements de disponibilité en P est la distribution du P adsorbé sur les différentes phases minérales. La minéralogie du sol, spécialement l'abondance relative d'illite vs. les oxydes de fer, contrôle l'influence des processus rhizosphériques en déterminant les minéraux impliqués dans l'adsorption du P. A travers l'identification d'un nouveau processus rhizosphérique découlant du prélèvement en Ca et de ses effets sur la disponibilité en P, nos résultats démontrent la validité des modèles géochimiques pour prédire l'influence des processus rhizosphériques déterminant la disponibilité en P.Root-induced chemical processes are recognized as a major strategy developed by plants to enhance phosphorus (P) availability and thus to promote P acquisition. However, the exact influence of these root-induced chemical processes is still poorly understood and quantified. The present study aimed at investigating the influence of root-induced chemical processes, especially root-induced pH changes, on P availability in the rhizosphere. In this work, we used a set of mechanistic adsorption models (« 1-pK triple plane », ion-exchange and Nica-Donnan) within the framework of the component additive approach in order to simulate the effects of root activity on P availability. First, we described the effects of pH on P availability in several soils unaffected by roots, a Chromic Cambisol and a Luvisol. The Luvisol showed different concentrations in inorganic P because of a long-term fertilisation trial. In the rhizosphere of durum wheat (Triticum tu rgidum durum L.) grown on these two soils, we found that calcium (Ca) uptake, in addition to P uptake and root-induced alkalisation, controlled to various extents the changes of soil P availability. Calcium uptake markedly increased P availability by decreasing the promoting effect of Ca adsorption on P adsorption. The relative influence of these three root processes depended on the solution composition (especially concentration of Ca and pH). Our simulations showed the relationship between changes in P availability and the speciation of adsorbed P onto the different soil minerals. Soil mineralogy, especially the relative abundance of illite vs. Fe oxides, controlled the influence of root processes by regulating the contribution of soil minerals to P adsorption. By identifying a novel root-induced processes, namely the Ca uptake, and describing its influence on P availability, our results demonstrate the ability of surface complexation models to predict the effects of root-i nduced processes on P availability in soils

Processus rhizosphériques déterminant la disponibilité en phosphore (apport de la modélisation mécaniste géochimique)

Les processus rhizosphériques sont reconnus comme une des stratégies majeures élaborées par les plantes afin d'augmenter la disponibilité en phosphore (P) et ainsi améliorer leur nutrition phosphatée. Pourtant, l'effet exact de ces processus est encore mal caractérisé et quantifié. L'objectif de ces travaux a été d e déterminer le rôle exercé par les modifications chimiques induites par les racines, particulièrement la modification de pH, dans les changements de disponibilité en P dans la rhizosphère. Pour ce faire, nous avons utilisé des modèles mécanistes géochimiques ( triple plane , échange d'ion et Nica-Donnan) en considérant une approche additive pour simuler l'effet de l'activité racinaire sur la disponibilité en P. Dans une première étape, nous avons caractérisé l'effet du pH sur la disponibilité en P dans plusieurs sols, un Cambisol et un Luvisol. Le Luvisol présentait deux concentrations en P inorganique contrastées en raison d'un essai de fertilisation phosphatée longue durée. Dans la rhizosphère du blé dur (Triticum turgidum durum L.) cultivé sur les mêmes sols, nous avons caractérisé qu'en plus de l'alcalinisation, le prélèvement en P et surtout en calcium (Ca) sont les processus rhizosphériques responsables du changement de disponibilit é en P observé. Le prélèvement du Ca favorise l'augmentation de la disponibilité en P dans la rhizosphère, en diminuant l'effet promoteur du processus d'adsorption-désorption du Ca sur celui du P. L'influence relative de ces trois processus rhizosphériques dépend toutefois de la composition chimique de la solution du sol (concentration en Ca et pH en particulier). Nos simulations mettent également en évidence la relation entre les changements de disponibilité en P est la distribution du P adsorbé sur les différentes phases minérales. La minéralogie du sol, spécialement l'abondance relative d'illite vs. les oxydes de fer, contrôle l'influence des processus rhizosphériques en déterminant les minéraux impliqués dans l'adsorption du P. A travers l'identification d'un nouveau processus rhizosphérique découlant du prélèvement en Ca et de ses effets sur la disponibilité en P, nos résultats démontrent la validité des modèles géochimiques pour prédire l'influence des processus rhizosphériques déterminant la disponibilité en P.Root-induced chemical processes are recognized as a major strategy developed by plants to enhance phosphorus (P) availability and thus to promote P acquisition. However, the exact influence of these root-induced chemical processes is still poorly understood and quantified. The present study aimed at investigating the influence of root-induced chemical processes, especially root-induced pH changes, on P availability in the rhizosphere. In this work, we used a set of mechanistic adsorption models ( 1-pK triple plane , ion-exchange and Nica-Donnan) within the framework of the component additive approach in order to simulate the effects of root activity on P availability. First, we described the effects of pH on P availability in several soils unaffected by roots, a Chromic Cambisol and a Luvisol. The Luvisol showed different concentrations in inorganic P because of a long-term fertilisation trial. In the rhizosphere of durum wheat (Triticum tu rgidum durum L.) grown on these two soils, we found that calcium (Ca) uptake, in addition to P uptake and root-induced alkalisation, controlled to various extents the changes of soil P availability. Calcium uptake markedly increased P availability by decreasing the promoting effect of Ca adsorption on P adsorption. The relative influence of these three root processes depended on the solution composition (especially concentration of Ca and pH). Our simulations showed the relationship between changes in P availability and the speciation of adsorbed P onto the different soil minerals. Soil mineralogy, especially the relative abundance of illite vs. Fe oxides, controlled the influence of root processes by regulating the contribution of soil minerals to P adsorption. By identifying a novel root-induced processes, namely the Ca uptake, and describing its influence on P availability, our results demonstrate the ability of surface complexation models to predict the effects of root-i nduced processes on P availability in soils.MONTPELLIER-SupAgro La Gaillarde (341722306) / SudocSudocFranceF

Impact of a CO2 leakage on groundwater quality. Influence of regional flow using reactive transport models.

Carbon Capture and Storage in deep and saline aquifers is one of the most hopeful technologies to reduce CO2 emissions into the atmosphere. However, CO2 leakages into shallow freshwater aquifers are a potential risk and potential impacts on groundwater have to be studied. A better understanding on how it could affect groundwater quality, aquifer minerals and trace elements is necessary to characterize a future storage site. Moreover, monitoring and remediation solutions have to be evaluated before storage operations. As part of the ANR project CIPRES, we present here reactive transport works. In a 3D model using ToughReact2, we perform different CO2 leakage scenarios in a confined aquifer, considering both brines and carbon dioxide gas. Our modeling works are based on the Albian aquifer, a strategic water resource for the Paris basin. This layer is the main aquifer overlying the Dogger deep saline aquifer. We consider one groundwater and rocks chemistry of the Albian aquifer composed by the Albian green sand (Quartz, Calcite, Glauconite , Kaolinite) at 700 m deep. The geochemical model was elaborated from experimental data performed in previous study (Humez, 2012). The aquifer consists in a mesh, divided roughly in 20000 cells making a 60 m thick and a 500 m large layer. Furthermore, cells are subdivided near the leakage point to consider local phenomena (secondary precipitation, kinetics, sorption/desorption...). We highlight the importance of surface complexation on trace element transport (As, Zn and Ni). Moreover, we distinguish different geochemical behavior (CO2 plume shape, secondary precipitation of siderite or chalcedony, desorption...) according to different horizontal flow rate influenced directly by the hydrodynamics (regional gradient). Understanding how geochemical reactions and regional flows influence water chemistry, allows to ascertain measurement monitoring and verification plan and remediation works in case of leak considering a given location