Evidencing the role of plants vs soils in the understanding of 137Cs phyto availability using a coupled experimental and modelling approach

International audience137Cs is a radionuclide with a half-life of 30 years that is commonly found in soils after nuclear fallout due to nuclear incidents or atmospheric nuclear weapon testing. Due to their properties of accumulation and retention, soils are key compartments for the transfer of contaminants such as 137Cs in the trophic chain. Ingestion of contaminated agricultural products being one of the main component of human exposure, it is essential to be able to predict the fate of 137Cs throughout the soil-plant continuum.The contaminant mobility into the soil, its transfer to the plant and its final distribution between all components are generally described by simple models (equilibrium-based, linear distributions). These models are operational but are not able to account for the variability of soils and plants encountered.Bioavailability is function of both soil physico-chemical characteristics, that impact the environmental availability, and plant physiology which determines the uptake rate and accumulation. The aim of this work is to highlight the preponderant factors controlling the 137Cs bioavailability in the soil-solution-plant continuum by using a model that account for both soil and plant characteristics. The proposed mechanistic model is based on thermodynamic reactions describing the interactions of Cs with the different soil reactive components, coupled with a physiological model of root absorption.Series of experiments were conducted to produce a contrasted data set of 137Cs soil to plant transfer. For those experiments, 2 different plants with contrasted Cs uptake capacities (Millet, Mustard) and 3 different soils with varying texture and mineralogy have been studied. Three weeks exposure studies were conducted with the RHIZOtest® which is a normative device to assess the bioavailability of contaminants in soil. They were completed with batch experiments aiming at characterizing the environmental availability of Cs in soils. A large range of 137Cs soil to plant transfer rates was measured for the different soil/pant combinations. For example a contrasted bioavailability of 137Cs was observed, with the same plant accumulating 10% to 40% of total Cs’s stock depending on the soils. We also observed that during the time of the experiment the plant had absorbed most of the estimated environmental available Cs.Modelling those experiments allowed us to highlight the main soil and plant properties that have a great impact on the contaminant mobility. For example, plant physiological factors were the main driver of bioavailability in condition where environmental availability was not limited (e.g. sandy soils), whereas their roles were reduced in soils with high 137Cs sorption capacity. Such a model may help to reduce uncertainties in the prediction of 137Cs transfer to plants in environmental risk assessment, with a great potential to cover a large range of soils and plants

Modélisation dynamique de la mobilité du 137Cs dans le continuum sol-solution-plante : évaluation de la réponse du modèle à des jeux de données expérimentaux contrastés

The aim of this work was to develop a robust and generical model able to predict 137Cs mobility into the soil-solution-plant continuum. The first part of this work was dedicated to several soil-plant transfer experiments. Two plants (millet, mustard) with contrasted Cs adsorption capacity and three soils with different Cs retention capacities have been used. Results obtained with the experiments permitted to observe the influence of the different system compartments on Cs mobility. Moreover, those experiments permitted to acquire a contrasted experimental data set. The second part of this work was to confront the model with the experimental data generated in the lab. This confrontation showed that the model was able to represent with a good agreement the distribution of the Cs into the soil-solution-plant continuum. Moreover, the model permitted to understand the influence of other cations in the mobility Cs in the system. Dynamic modeling of the 137 Cs in the soil-solution-plant continuum. Evaluation of the model response to contrasted experimental dataCe travail visait à développer un modèle générique capable de mieux prédire les transferts de 137Cs dans le système sol-solution-plante. La première partie de ce travail a été consacrée à des expérimentations de transfert sol-plante du Cs en laboratoire. Deux plantes (millet, moutarde) ayant des capacités d’absorption du Cs potentiellement différentes et trois types de sol ayant des capacités de rétention du Cs contrastées ont été utilisés. Cette partie expérimentale a permis de mettre en évidence l’influence des différentes phases du système sur la mobilité du Cs, mais aussi de générer un jeu de données utilisé dans la deuxième partie de ce travail pour tester la capacité du modèle développé à simuler de transferts du Cs pour différents couples sol x plante. La confrontation modèle-mesure a permis de démontrer la bonne capacité du modèle à représenter la mobilité du Cs pour chaque condition, mais aussi la nécessité de prendre en compte l’influence des cations majeurs pour modéliser correctement la mobilité du Cs dans le système sol-solution-plant

Modélisation dynamique de la mobilité du 137Cs dans le continuum sol-solution-plante : évaluation de la réponse du modèle à des jeux de données expérimentaux contrastés

The aim of this work was to develop a robust and generical model able to predict 137Cs mobility into the soil-solution-plant continuum. The first part of this work was dedicated to several soil-plant transfer experiments. Two plants (millet, mustard) with contrasted Cs adsorption capacity and three soils with different Cs retention capacities have been used. Results obtained with the experiments permitted to observe the influence of the different system compartments on Cs mobility. Moreover, those experiments permitted to acquire a contrasted experimental data set. The second part of this work was to confront the model with the experimental data generated in the lab. This confrontation showed that the model was able to represent with a good agreement the distribution of the Cs into the soil-solution-plant continuum. Moreover, the model permitted to understand the influence of other cations in the mobility Cs in the system. Dynamic modeling of the 137 Cs in the soil-solution-plant continuum. Evaluation of the model response to contrasted experimental dataCe travail visait à développer un modèle générique capable de mieux prédire les transferts de 137Cs dans le système sol-solution-plante. La première partie de ce travail a été consacrée à des expérimentations de transfert sol-plante du Cs en laboratoire. Deux plantes (millet, moutarde) ayant des capacités d’absorption du Cs potentiellement différentes et trois types de sol ayant des capacités de rétention du Cs contrastées ont été utilisés. Cette partie expérimentale a permis de mettre en évidence l’influence des différentes phases du système sur la mobilité du Cs, mais aussi de générer un jeu de données utilisé dans la deuxième partie de ce travail pour tester la capacité du modèle développé à simuler de transferts du Cs pour différents couples sol x plante. La confrontation modèle-mesure a permis de démontrer la bonne capacité du modèle à représenter la mobilité du Cs pour chaque condition, mais aussi la nécessité de prendre en compte l’influence des cations majeurs pour modéliser correctement la mobilité du Cs dans le système sol-solution-plant

Dynamic modeling of 137Cs in the soil-solution-plant continuum : evaluation of the model response to contrasted experimental data

Ce travail visait à développer un modèle générique capable de mieux prédire les transferts de 137Cs dans le système sol-solution-plante. La première partie de ce travail a été consacrée à des expérimentations de transfert sol-plante du Cs en laboratoire. Deux plantes (millet, moutarde) ayant des capacités d’absorption du Cs potentiellement différentes et trois types de sol ayant des capacités de rétention du Cs contrastées ont été utilisés. Cette partie expérimentale a permis de mettre en évidence l’influence des différentes phases du système sur la mobilité du Cs, mais aussi de générer un jeu de données utilisé dans la deuxième partie de ce travail pour tester la capacité du modèle développé à simuler de transferts du Cs pour différents couples sol x plante. La confrontation modèle-mesure a permis de démontrer la bonne capacité du modèle à représenter la mobilité du Cs pour chaque condition, mais aussi la nécessité de prendre en compte l’influence des cations majeurs pour modéliser correctement la mobilité du Cs dans le système sol-solution-planteThe aim of this work was to develop a robust and generical model able to predict 137Cs mobility into the soil-solution-plant continuum. The first part of this work was dedicated to several soil-plant transfer experiments. Two plants (millet, mustard) with contrasted Cs adsorption capacity and three soils with different Cs retention capacities have been used. Results obtained with the experiments permitted to observe the influence of the different system compartments on Cs mobility. Moreover, those experiments permitted to acquire a contrasted experimental data set. The second part of this work was to confront the model with the experimental data generated in the lab. This confrontation showed that the model was able to represent with a good agreement the distribution of the Cs into the soil-solution-plant continuum. Moreover, the model permitted to understand the influence of other cations in the mobility Cs in the system. Dynamic modeling of the 137 Cs in the soil-solution-plant continuum. Evaluation of the model response to contrasted experimental dat

Modélisation dynamique de la mobilité du 137Cs dans le continuum sol-solution-plante : évaluation de la réponse du modèle à des jeux de données expérimentaux contrastés

The aim of this work was to develop a robust and generical model able to predict 137Cs mobility into the soil-solution-plant continuum. The first part of this work was dedicated to several soil-plant transfer experiments. Two plants (millet, mustard) with contrasted Cs adsorption capacity and three soils with different Cs retention capacities have been used. Results obtained with the experiments permitted to observe the influence of the different system compartments on Cs mobility. Moreover, those experiments permitted to acquire a contrasted experimental data set. The second part of this work was to confront the model with the experimental data generated in the lab. This confrontation showed that the model was able to represent with a good agreement the distribution of the Cs into the soil-solution-plant continuum. Moreover, the model permitted to understand the influence of other cations in the mobility Cs in the system. Dynamic modeling of the 137 Cs in the soil-solution-plant continuum. Evaluation of the model response to contrasted experimental dataCe travail visait à développer un modèle générique capable de mieux prédire les transferts de 137Cs dans le système sol-solution-plante. La première partie de ce travail a été consacrée à des expérimentations de transfert sol-plante du Cs en laboratoire. Deux plantes (millet, moutarde) ayant des capacités d’absorption du Cs potentiellement différentes et trois types de sol ayant des capacités de rétention du Cs contrastées ont été utilisés. Cette partie expérimentale a permis de mettre en évidence l’influence des différentes phases du système sur la mobilité du Cs, mais aussi de générer un jeu de données utilisé dans la deuxième partie de ce travail pour tester la capacité du modèle développé à simuler de transferts du Cs pour différents couples sol x plante. La confrontation modèle-mesure a permis de démontrer la bonne capacité du modèle à représenter la mobilité du Cs pour chaque condition, mais aussi la nécessité de prendre en compte l’influence des cations majeurs pour modéliser correctement la mobilité du Cs dans le système sol-solution-plant

Cesium transfer to millet and mustard as a function of Cs availability in soils

International audience137Cs is one of the most persistent radioactive contaminant in soil after a nuclear accident. It can be taken up by plants and enter the human food chain generating major hazard for population health. Although a huge literature have highlighted the role of different processes involved in Cs uptake by plants, there is still no simple way to predict its transfer for a specific plant from a particular soil. The objective of this study is to assess the assumption that concentration ratio (CR) of Cs can be predicted from one plant taxon knowing the CR of another taxon taken as reference whatever the soils on which plants are grown. A series of plant/soil Cs transfer experiments were performed on Rhizotest using three soils with contrasted Cs retention capacity and two plants (millet and mustard) with contrasted Cs uptake capacity based on their phylogeny. Results highlighted a different behaviour than that expected, with CR of mustard being either higher, equal or lower than the one of millet depending on the soils. These results can be put in regards to the large variation of the CR of millet on these 3 soils (3 orders of magnitude). Parameters linked to plant physiology (growth, water use efficiency, potassium (K) uptake and distribution in planta) or K level in soil solution failed to explain the relative behaviour of millet compared to mustard as a function of soils. However considering Cs availability in soils and defining a new CR based on the amount of Cs available in the soil (CRavail) permits to decrease the range of variation of CR for a given plant between the soils

Evidencing the role of plants vs soils in the understanding of 137Cs phyto availability using a coupled experimental and modelling approach

International audience137Cs is a radionuclide with a half-life of 30 years that is commonly found in soils after nuclear fallout due to nuclear incidents or atmospheric nuclear weapon testing. Due to their properties of accumulation and retention, soils are key compartments for the transfer of contaminants such as 137Cs in the trophic chain. Ingestion of contaminated agricultural products being one of the main component of human exposure, it is essential to be able to predict the fate of 137Cs throughout the soil-plant continuum.The contaminant mobility into the soil, its transfer to the plant and its final distribution between all components are generally described by simple models (equilibrium-based, linear distributions). These models are operational but are not able to account for the variability of soils and plants encountered.Bioavailability is function of both soil physico-chemical characteristics, that impact the environmental availability, and plant physiology which determines the uptake rate and accumulation. The aim of this work is to highlight the preponderant factors controlling the 137Cs bioavailability in the soil-solution-plant continuum by using a model that account for both soil and plant characteristics. The proposed mechanistic model is based on thermodynamic reactions describing the interactions of Cs with the different soil reactive components, coupled with a physiological model of root absorption.Series of experiments were conducted to produce a contrasted data set of 137Cs soil to plant transfer. For those experiments, 2 different plants with contrasted Cs uptake capacities (Millet, Mustard) and 3 different soils with varying texture and mineralogy have been studied. Three weeks exposure studies were conducted with the RHIZOtest® which is a normative device to assess the bioavailability of contaminants in soil. They were completed with batch experiments aiming at characterizing the environmental availability of Cs in soils. A large range of 137Cs soil to plant transfer rates was measured for the different soil/pant combinations. For example a contrasted bioavailability of 137Cs was observed, with the same plant accumulating 10% to 40% of total Cs’s stock depending on the soils. We also observed that during the time of the experiment the plant had absorbed most of the estimated environmental available Cs.Modelling those experiments allowed us to highlight the main soil and plant properties that have a great impact on the contaminant mobility. For example, plant physiological factors were the main driver of bioavailability in condition where environmental availability was not limited (e.g. sandy soils), whereas their roles were reduced in soils with high 137Cs sorption capacity. Such a model may help to reduce uncertainties in the prediction of 137Cs transfer to plants in environmental risk assessment, with a great potential to cover a large range of soils and plants

Evidencing the role of plants vs soils in the understanding of 137Cs phyto availability using a coupled experimental and modelling approach

International audience137Cs is a radionuclide with a half-life of 30 years that is commonly found in soils after nuclear fallout due to nuclear incidents or atmospheric nuclear weapon testing. Due to their properties of accumulation and retention, soils are key compartments for the transfer of contaminants such as 137Cs in the trophic chain. Ingestion of contaminated agricultural products being one of the main component of human exposure, it is essential to be able to predict the fate of 137Cs throughout the soil-plant continuum.The contaminant mobility into the soil, its transfer to the plant and its final distribution between all components are generally described by simple models (equilibrium-based, linear distributions). These models are operational but are not able to account for the variability of soils and plants encountered.Bioavailability is function of both soil physico-chemical characteristics, that impact the environmental availability, and plant physiology which determines the uptake rate and accumulation. The aim of this work is to highlight the preponderant factors controlling the 137Cs bioavailability in the soil-solution-plant continuum by using a model that account for both soil and plant characteristics. The proposed mechanistic model is based on thermodynamic reactions describing the interactions of Cs with the different soil reactive components, coupled with a physiological model of root absorption.Series of experiments were conducted to produce a contrasted data set of 137Cs soil to plant transfer. For those experiments, 2 different plants with contrasted Cs uptake capacities (Millet, Mustard) and 3 different soils with varying texture and mineralogy have been studied. Three weeks exposure studies were conducted with the RHIZOtest® which is a normative device to assess the bioavailability of contaminants in soil. They were completed with batch experiments aiming at characterizing the environmental availability of Cs in soils. A large range of 137Cs soil to plant transfer rates was measured for the different soil/pant combinations. For example a contrasted bioavailability of 137Cs was observed, with the same plant accumulating 10% to 40% of total Cs’s stock depending on the soils. We also observed that during the time of the experiment the plant had absorbed most of the estimated environmental available Cs.Modelling those experiments allowed us to highlight the main soil and plant properties that have a great impact on the contaminant mobility. For example, plant physiological factors were the main driver of bioavailability in condition where environmental availability was not limited (e.g. sandy soils), whereas their roles were reduced in soils with high 137Cs sorption capacity. Such a model may help to reduce uncertainties in the prediction of 137Cs transfer to plants in environmental risk assessment, with a great potential to cover a large range of soils and plants

An alternative model of Cs transfer to plants that accounts for Cs availability in soils and dynamics of transfer

International audienc