In situ modeling of PAH dynamics in agricultural soils amended with composts using the “VSOIL” platform

In situ modeling of PAH dynamics in agricultural soils amended with composts using the “VSOIL” platform. EGU 2017, European Geophysical Union General Assembly 201

Modélisation de la dynamique des hydrocarbures aromatiques polycycliques (HAP) dans des sols soumis à un gradient de contamination allant d’un contexte agricole à un contexte industriel

Due to former industrial activities and the increasing recycling of organic waste products from urban areas in agricultural soils, increasing amounts of persistent organic compounds, among them polycyclic aromatic hydrocarbons (PAH), are to be found in French soils. In the framework of the management of polluted sites and soils and the risk assessment of PAH transfer in the environment, it is essential to better understand the behavior, dissipation, transfer or accumulation of PAH in soils. For this purpose, there is a need to develop a new generation of numerical models based on the flexible coupling between the processes describing PAH dynamics in soil. Our work presents the development and assessment of such model. It is based on the implementation of an interdisciplinary global model, and applicable at the field scale, for PAH in soil by coupling modules describing the major physical, biochemical and biological processes influencing the fate of PAH in soil, with modules that simulate water transfer, heat transfer, solute transport, and organic matter transformation under real climatic conditions. The coupling is performed using the «VSoil» modeling platform of INRA (https://www6.inra.fr/vsoil/The-Project). The steps of our modelling study are the following: i) calibrate the model at the field scale using previously estimated parameters at the lab-scale and completed with field data on a short period of time, ii) test and validate the calibrated model using field experimental data on mid term periods, iii) test different hypotheses of variation of availability and climatic scenarios or repeated applications of different composts on the fate of PAH in soil. Our results show that the model can adequately predict the fate of PAH in soil over a wide range of contamination ranging from agricultural plots amended with weakly contaminated composted organic wastes to old industrial sites heavily contaminated. This new tool allows, therefore, a better understanding of the processes controlling the dynamics of PAH in these different systems.Du fait des activités industrielles anciennes et du recyclage croissant des produites résiduaires organiques d’origine urbaine dans les sols agricoles, des composés organiques persistants, parmi lesquels les hydrocarbures aromatiques polycycliques (HAP) se retrouvent présents dans les sols français. Dans le cadre de la gestion des sites et sols pollués et de l'évaluation des risques associés aux HAP dans l'environnement, une meilleure connaissance du comportement, de la dissipation, du transfert ou de l’accumulation des HAP dans les sols est alors indispensable. Dans ce but, il est utile de développer une nouvelle génération de modèles numériques basés sur le couplage flexible de l’ensemble des processus majeurs contrôlant la dynamique des HAP dans le sol. Notre travail repose sur la mise en œuvre, dans le cadre de la plateforme VSoil de l’INRA (https://www6.inra.fr/vsoil/The-Project), d'un modèle global interdisciplinaire de dynamique des HAP dans les sols, applicable à l’échelle du terrain et couplant des modules décrivant les principaux processus physiques, biochimiques et biologiques. Ce modèle associe d’une part des modules déjà publiés simulant la décomposition des matières organiques exogènes apportées, le transfert d'eau, le transfert de chaleur et le transport de solutés dans des conditions climatiques réelles, et d’autre part, un nouveau modèle représentant spécifiquement la réactivité des HAP.La démarche numérique adoptée dans ce travail a alors été de i) calibrer le modèle de terrain en utilisant des paramètres déterminés à partir de données expérimentales obtenues au laboratoire et complétées avec une partie des données de terrain obtenues sur une courte période, ii) tester et valider le modèle calibré au terrain à l'aide des données de terrain complémentaires sur des périodes plus longues, iii) tester différentes hypothèses de variation de disponibilité et scenarios climatiques ou d’apports répétés de différents composts sur le devenir de HAP dans le sol. Nos résultats montrent que le modèle peut prédire de manière satisfaisante le devenir des HAP dans le sol sur une gamme de contamination allant de parcelles agricoles amendées avec des matières organiques faiblement contaminées jusqu’à d’anciens sites industriels fortement contaminés et permettent alors de mieux appréhender les processus contrôlant la dynamique des HAP dans ces différents systèmes

Modeling the dynamic of polycyclic aromatic hydrocarbons (PAH) in soils impacted by a gradient of contamination ranging from agricultural to industrial contexts

Du fait des activités industrielles anciennes et du recyclage croissant des produites résiduaires organiques d’origine urbaine dans les sols agricoles, des composés organiques persistants, parmi lesquels les hydrocarbures aromatiques polycycliques (HAP) se retrouvent présents dans les sols français. Dans le cadre de la gestion des sites et sols pollués et de l'évaluation des risques associés aux HAP dans l'environnement, une meilleure connaissance du comportement, de la dissipation, du transfert ou de l’accumulation des HAP dans les sols est alors indispensable. Dans ce but, il est utile de développer une nouvelle génération de modèles numériques basés sur le couplage flexible de l’ensemble des processus majeurs contrôlant la dynamique des HAP dans le sol. Notre travail repose sur la mise en œuvre, dans le cadre de la plateforme VSoil de l’INRA (https://www6.inra.fr/vsoil/The-Project), d'un modèle global interdisciplinaire de dynamique des HAP dans les sols, applicable à l’échelle du terrain et couplant des modules décrivant les principaux processus physiques, biochimiques et biologiques. Ce modèle associe d’une part des modules déjà publiés simulant la décomposition des matières organiques exogènes apportées, le transfert d'eau, le transfert de chaleur et le transport de solutés dans des conditions climatiques réelles, et d’autre part, un nouveau modèle représentant spécifiquement la réactivité des HAP.La démarche numérique adoptée dans ce travail a alors été de i) calibrer le modèle de terrain en utilisant des paramètres déterminés à partir de données expérimentales obtenues au laboratoire et complétées avec une partie des données de terrain obtenues sur une courte période, ii) tester et valider le modèle calibré au terrain à l'aide des données de terrain complémentaires sur des périodes plus longues, iii) tester différentes hypothèses de variation de disponibilité et scenarios climatiques ou d’apports répétés de différents composts sur le devenir de HAP dans le sol. Nos résultats montrent que le modèle peut prédire de manière satisfaisante le devenir des HAP dans le sol sur une gamme de contamination allant de parcelles agricoles amendées avec des matières organiques faiblement contaminées jusqu’à d’anciens sites industriels fortement contaminés et permettent alors de mieux appréhender les processus contrôlant la dynamique des HAP dans ces différents systèmes.Due to former industrial activities and the increasing recycling of organic waste products from urban areas in agricultural soils, increasing amounts of persistent organic compounds, among them polycyclic aromatic hydrocarbons (PAH), are to be found in French soils. In the framework of the management of polluted sites and soils and the risk assessment of PAH transfer in the environment, it is essential to better understand the behavior, dissipation, transfer or accumulation of PAH in soils. For this purpose, there is a need to develop a new generation of numerical models based on the flexible coupling between the processes describing PAH dynamics in soil. Our work presents the development and assessment of such model. It is based on the implementation of an interdisciplinary global model, and applicable at the field scale, for PAH in soil by coupling modules describing the major physical, biochemical and biological processes influencing the fate of PAH in soil, with modules that simulate water transfer, heat transfer, solute transport, and organic matter transformation under real climatic conditions. The coupling is performed using the «VSoil» modeling platform of INRA (https://www6.inra.fr/vsoil/The-Project). The steps of our modelling study are the following: i) calibrate the model at the field scale using previously estimated parameters at the lab-scale and completed with field data on a short period of time, ii) test and validate the calibrated model using field experimental data on mid term periods, iii) test different hypotheses of variation of availability and climatic scenarios or repeated applications of different composts on the fate of PAH in soil. Our results show that the model can adequately predict the fate of PAH in soil over a wide range of contamination ranging from agricultural plots amended with weakly contaminated composted organic wastes to old industrial sites heavily contaminated. This new tool allows, therefore, a better understanding of the processes controlling the dynamics of PAH in these different systems

Long term decrease of 137Cs bioavailability in French pastures: results from 25 years of monitoring

International audienceLong term radioactivity monitoring programs contribute to the understanding of the behavior of radionuclides in the environment. This work aims to investigate the long term behavior of Cesium-137 in pasture ecosystem (root soil, grass and cow’s milk) by using of more than twenty five years monitoring data collected at ten of French pasture sites contaminated by atmospheric fallouts from Chernobyl and nuclear atmospheric tests. We estimated with a simple exponential model the long term effective half-lives of radiocesium in root soil, grass vegetation and cow‘s milk along with their associated uncertainties. The average values of the effective half-lives over all the investigated sites were determined as 17, 11 and 9 years for soil, grass and milk respectively. Those values compare favorably to those estimated in previous studies in literature. These findings further enable us to quantify the decrease of 137Cs bioavailability which ranges from 0.008 to 0.044 year-1 (i.e. effective half lives ranging from 16 to 87 years in soil

Evaluation of semi-mechanistic models to predict soil to grass transfer factor of 137Cs based on long term observations in French pastures

International audienceThe aim of this study was to evaluate and improve the accuracy of the semi-mechanistic models used in regulatoryexposure assessment tools, to describe the transfer factors of137Cs from pasture soils to grass observed indifferent grazing areas of France between 2004 and 2017. This involved a preliminary parameterization step ofthe dynamic factor describing the ageing of radiocesium in the root zone using a Bayesian approach. A data setwith mid-term (10 years about) and long term (more than 20 years) field and literature data from 4 Europeancountries was used. A double kinetics of the bioavailability decay was evidenced with two half-life periods equalto 0.46 ±0.11 yr and 9.57 ±1.12 yr for the fast and slow declining rates respectively. We, then, tested a fewexisting alternative models proposed in literature. The comparison with field data showed that these modelsalways underestimated the observations by one to two orders of magnitude, suggesting that the solid-liquidpartition coefficient (Kd) was overestimated by models. The results suggest that semi mechanistic modelsmight fail in the long-term prediction of the radionuclide transfer from soil-to-plant in the food chain. Theyhighlight the need to calculate Kd using easily exchangeable137Cs (i.e. labile fraction) rather than total soil137Cs

Modelling the fate of PAH added with composts in amended soil according to the origin of the exogenous organic matter.

A new model that was able to simulate the behaviours of polycyclic aromatic hydrocarbons (PAH) during composting and after the addition of the composts to agricultural soil is presented here. This model associates modules that describe the physical, biological and biochemical processes involved in PAH dynamics in soils, along with a module describing the compost degradation resulting in PAH release. The model was calibrated from laboratory incubations using three (14)C-PAHs, phenanthrene, fluoranthene and benzo(a)pyrene, and three different composts consisting of two mature and one non-mature composts. First, the labelled PAHs were added to the compost over 28days, and spiked composts were then added to the soil over 55days. The model calculates the proportion of biogenic and physically bound residues in the non-extractable compartment of PAHs at the end of the compost incubation to feed the initial conditions of the model for soil amended with composts. For most of the treatments, a single parameter set enabled to simulate the observed dynamics of PAHs adequately for all the amended soil treatments using a Bayesian approach. However, for fluoranthene, different parameters that were able to simulate the growth of a specific microbial biomass had to be considered for mature compost. Processes that occurred before the compost application to the soil strongly influenced the fate of PAHs in the soil. Our results showed that the PAH dissipation during compost incubation was higher in mature composts because of the higher specific microbial activity, while the PAH dissipation in amended soil was higher in the non-mature compost because of the higher availability of PAHs and the higher co-metabolic microbial activity

In situ long-term modeling of phenanthrene dynamics in an aged contaminated soil using the “VSOIL” platform

In situ long-term modeling of phenanthrene dynamics in an aged contaminated soil using the “VSOIL” platform. 14. International Conference on Sustainable Use and Management of Soil, Sediment and Water Resources (AquaConSoil

Speciation study in the sulfamethoxazole–copper–pH–soil system: Implications for retention prediction

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Estimation des teneurs en carbone organique des sols agricoles par télédétection par drone

Estimation des teneurs en carbone organique des sols agricoles par télédétection par drone. EGU 2017, European Geophysical Union General Assembly 201