Environmental behaviour of inorganic pollutants present in raw and desalinated French marine sediments

International audienceIn the frame of long-term management of contaminated dredged sediments, this paper is centered on determinating the mobility of inorganic contaminants. A methodology derived from waste characterization has been developed and applied to marine sediments from Lazaret bay (Toulon, southern France) to determine the potential mobilization of inorganic pollutants in specific conditions. It consists of mineral and textural analysis combined with leaching tests. This methodology was applied to untreated, 5.8 % organic matter, light sandy silt harbor sediment and to the same sediment after a desalinization treatment. In both untreated and desalinated sediments, the contaminant content was around 26.1, 0.18, 42.5, 34, 31, 35 and 99 mg kg-1 for As, Cd, Cr, Cu, Ni, Pb and Zn, respectively. After 24 hours of time contact between deionized water and sediments, contaminant release of metals was very low (ca. <0.7 total mass %, for all studied elements) due to low solubility of the bearing solid phases (organic matter, carbonates and sulfides), while Mo and B were widely released. After 48 hours, Cd, As, Mo and B release was higher while more significant but no clear differences for other metal appeared

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Ce travail s’inscrit dans une problématique locale de teneur élevée en arsenic naturel dans le but d’améliorer la surveillance et la gestion de la qualité de la ressource en eau dans l’arrière-pays niçois. L’existence de grandes disparités géographiques des teneurs en arsenic font de la géologie la cause principale de cette contamination. L’intérêt de ce travail est d’appréhender les interactions solide/solution entre l’arsenic total dissous et les particules solides (matières en suspensions, sédiment de lit de rivière, solides naturels). Pour décrypter le comportement géochimique de l’arsenic, les trois objectifs principaux sont : de déterminer son état de conservativité dans le milieu naturel ; puis d’étudier les phénomènes d’adsorption en laboratoire sur des solides naturels (illite, oxydes de fer) ou de référence (kaolinite) ; puis enfin d’apporter une application directe au piégeage de l’arsenic par la création d’un pilote de traitement destiné à dépolluer une source d’eau destiné à la consommation humaine. La concentration en particule est le facteur influençant la conservativité de l’arsenic dans le système de confluence Tinée/Var selon les données des compartiments dissous et particulaire. La fraction colloïdale semble avoir une implication de premier ordre lors de la période de crue étudiée. Le piégeage de l’arsenic est favorisé par les oxyhydroxydes de fer, les argiles puis en moindre quantité par les solides acido-solubles.This work aimed to solve a local problem of high water contamination with natural arsenic. In order to monitor and manage the water resource quality in French Riviera region. The different geographical repartition of arsenic content makes the consequences of this contamination to the geology. The interest of this work is to understand the interaction at solid/liquid interfaces between total dissolved arsenic and the solid particles (suspended particles matter, bed sediments and natural solids). To elucidate the geochemical behavior of arsenic, the three main objectives are: to determine the conservative states in the natural environment, then to study the adsorption phenomena under laboratory conditions onto the natural solids (illite and iron oxides) or reference materials (kaolinite); thirdly to apply the outcome of this work to establish a processing pilot for arsenic removal to decontaminate drinking water. The particle content is the main factor which influences the conservativity of arsenic in the confluence Tinée/Var. Colloids seems to have the main role in the arsenic removal in the studied flood period. Arsenic removal is favored by iron oxides, and clays, but less efficiently by acid-soluble compounds. The study of sorption mechanisms onto clays showed that adsorption of arsenic is strongly dependent on pH, quantity of aluminol reactive sites, influence of competitive anions such as carbonates and phosphates. Finally, the association of zeolites (high specific surface area) with coating of amorphous iron oxides (high affinity for arsenic) makes this adsorbent the most efficient, hence was studied and used in this work for arsenic adsorption

Mécanismes et transferts de l'arsenic dans une confluence du Var et étude d'une méthode de remédiation dans les eaux potables

This work aimed to solve a local problem of high water contamination with natural arsenic. In order to monitor and manage the water resource quality in French Riviera region. The different geographical repartition of arsenic content makes the consequences of this contamination to the geology. The interest of this work is to understand the interaction at solid/liquid interfaces between total dissolved arsenic and the solid particles (suspended particles matter, bed sediments and natural solids). To elucidate the geochemical behavior of arsenic, the three main objectives are: to determine the conservative states in the natural environment, then to study the adsorption phenomena under laboratory conditions onto the natural solids (illite and iron oxides) or reference materials (kaolinite); thirdly to apply the outcome of this work to establish a processing pilot for arsenic removal to decontaminate drinking water. The particle content is the main factor which influences the conservativity of arsenic in the confluence Tinée/Var. Colloids seems to have the main role in the arsenic removal in the studied flood period. Arsenic removal is favored by iron oxides, and clays, but less efficiently by acid-soluble compounds. The study of sorption mechanisms onto clays showed that adsorption of arsenic is strongly dependent on pH, quantity of aluminol reactive sites, influence of competitive anions such as carbonates and phosphates. Finally, the association of zeolites (high specific surface area) with coating of amorphous iron oxides (high affinity for arsenic) makes this adsorbent the most efficient, hence was studied and used in this work for arsenic adsorption.Ce travail s’inscrit dans une problématique locale de teneur élevée en arsenic naturel dans le but d’améliorer la surveillance et la gestion de la qualité de la ressource en eau dans l’arrière-pays niçois. L’existence de grandes disparités géographiques des teneurs en arsenic font de la géologie la cause principale de cette contamination. L’intérêt de ce travail est d’appréhender les interactions solide/solution entre l’arsenic total dissous et les particules solides (matières en suspensions, sédiment de lit de rivière, solides naturels). Pour décrypter le comportement géochimique de l’arsenic, les trois objectifs principaux sont : de déterminer son état de conservativité dans le milieu naturel ; puis d’étudier les phénomènes d’adsorption en laboratoire sur des solides naturels (illite, oxydes de fer) ou de référence (kaolinite) ; puis enfin d’apporter une application directe au piégeage de l’arsenic par la création d’un pilote de traitement destiné à dépolluer une source d’eau destiné à la consommation humaine. La concentration en particule est le facteur influençant la conservativité de l’arsenic dans le système de confluence Tinée/Var selon les données des compartiments dissous et particulaire. La fraction colloïdale semble avoir une implication de premier ordre lors de la période de crue étudiée. Le piégeage de l’arsenic est favorisé par les oxyhydroxydes de fer, les argiles puis en moindre quantité par les solides acido-solubles

Mécanismes et transferts de l'arsenic dans une confluence du Var et étude d'une méthode de remédiation dans les eaux potables

Ce travail s inscrit dans une problématique locale de teneur élevée en arsenic naturel dans le but d améliorer la surveillance et la gestion de la qualité de la ressource en eau dans l arrière-pays niçois. L existence de grandes disparités géographiques des teneurs en arsenic font de la géologie la cause principale de cette contamination. L intérêt de ce travail est d appréhender les interactions solide/solution entre l arsenic total dissous et les particules solides (matières en suspensions, sédiment de lit de rivière, solides naturels). Pour décrypter le comportement géochimique de l arsenic, les trois objectifs principaux sont : de déterminer son état de conservativité dans le milieu naturel ; puis d étudier les phénomènes d adsorption en laboratoire sur des solides naturels (illite, oxydes de fer) ou de référence (kaolinite) ; puis enfin d apporter une application directe au piégeage de l arsenic par la création d un pilote de traitement destiné à dépolluer une source d eau destiné à la consommation humaine. La concentration en particule est le facteur influençant la conservativité de l arsenic dans le système de confluence Tinée/Var selon les données des compartiments dissous et particulaire. La fraction colloïdale semble avoir une implication de premier ordre lors de la période de crue étudiée. Le piégeage de l arsenic est favorisé par les oxyhydroxydes de fer, les argiles puis en moindre quantité par les solides acido-solubles.This work aimed to solve a local problem of high water contamination with natural arsenic. In order to monitor and manage the water resource quality in French Riviera region. The different geographical repartition of arsenic content makes the consequences of this contamination to the geology. The interest of this work is to understand the interaction at solid/liquid interfaces between total dissolved arsenic and the solid particles (suspended particles matter, bed sediments and natural solids). To elucidate the geochemical behavior of arsenic, the three main objectives are: to determine the conservative states in the natural environment, then to study the adsorption phenomena under laboratory conditions onto the natural solids (illite and iron oxides) or reference materials (kaolinite); thirdly to apply the outcome of this work to establish a processing pilot for arsenic removal to decontaminate drinking water. The particle content is the main factor which influences the conservativity of arsenic in the confluence Tinée/Var. Colloids seems to have the main role in the arsenic removal in the studied flood period. Arsenic removal is favored by iron oxides, and clays, but less efficiently by acid-soluble compounds. The study of sorption mechanisms onto clays showed that adsorption of arsenic is strongly dependent on pH, quantity of aluminol reactive sites, influence of competitive anions such as carbonates and phosphates. Finally, the association of zeolites (high specific surface area) with coating of amorphous iron oxides (high affinity for arsenic) makes this adsorbent the most efficient, hence was studied and used in this work for arsenic adsorption.NICE-Bibliotheque electronique (060889901) / SudocSudocFranceF

Environmental Quality Assessment for Valorization of Raw and Desalinated Dredged Marine Sediment Contaminated by Potentially Toxic Elements

International audienceWithin the framework of evaluating the long-term management of contaminated dredged sediments, we studied the mobility of inorganic contaminants contained marine sediment submitted to desalination and to leaching in an outdoor lysimeter. A set of complementary analytical techniques were used: mineral and textural analysis; simple selective extractions; sequential selective extractions; acid neutralization capacity tests and percolation dynamic leaching tests, using standardized procedures. The raw sediment presented a critical concentration of As, Hg and soluble salts compared to most European sediment quality guidelines (SQGs). Desalination allowed the leaching of soluble salts without significant leaching of most potentially toxic elements (PTEs), but greatly enhanced the mobility of Mo. Five months outdoor storage with natural cycles of wetting and drying increased the fraction bound to organic matter (OM) or sulfides of Cu, Pb, Cd, Mo, As and Pb. Cu and As mobility appeared highly related to OM dynamics. Na, Cl, B and Mo appeared highly mobile, but Mo release was lower at pH < 5. Zn, Pb, Mn, Al, Ni and Cr had behavior characteristic of species adsorbed on mineral oxides surfaces, being highly leachable at acid pH. Colloidal transport was significant for DOC, As, Ni and Co and was the main process for Pb. Drying the sediment greatly enhanced the mobility of a number of elements and compounds, particularly Cd, Pb, Mo, Ba, As. Mo mobility after drying turned the material unsuitable for technical embankment; the material may still be used in road engineering under impervious pavement