Suspended Materials in River Waters Differentially Enrich Class 1 Integron- and IncP-1 Plasmid-Carrying Bacteria in Sediments

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Les fantômes remontent la Meuse… Observations préliminaires à propos d'un fantôme de roche en forêt de Jaulnay (Lorraine, France)

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Investigation of using Ni isotopes as anthropogenic source tracer in river sediments: a preliminary study

International audienceIn the past decade, high precision Ni stable isotopes of continental rocks and sediments, river and seawater have been studied and significant isotope variation has been reported [1-4]. Recently, Ni isotope fractionation during ore smelting and refining have been demonstrated, showing that slag holds isotopically heavier Ni than the feeding material and fly ash [5]. These studies showed the potential of using Ni isotopes for anthropogenic source tracing in the environment.As metal pollution in riverine systems poses a serious threat to water and sediment quality, it is of key importance to understand the pollution sources and their fate. Therefore, this study aims to (i) determine the Ni isotopic compositions of two river sediment cores from an industrial surrounded river in northern France and their origin; (ii) assess the movement of the anthropogenic sources in the riverine systems.We observed that 1) the δ60/58NiNIST986 values of the surface river sediments and suspended particles ranged from -0.15 ±0.04‰ to -0.04 ±0.04‰. 2) In the sediment cores, significantly different isotope signatures were measured (from -0.09‰ to -0.53‰ with a cluster around -0.36‰). Nearby natural soil dust, slag tailings could explain the excessive Ni of the river sediments. However, further studies of the isotope fractionation mechanisms in the riverine system are needed to better evaluate the anthropogenic source movements by using Ni isotope signatures as tracers.[1]Cameron et al.,2009,PNAS 106,10944-10948; [2]Cameron and Vance,2014,GCA 128,195-211; [3]Gall et al., 2013, EPSL 375,148-155; [4]Estrade et al.,2015,EPSL 423,24-35; [5]Ratié et al.,2016,APPL GEOCHEM 64, 136-145

Iron distribution in the octahedral sheet of dioctahedral smectites. An Fe K-edge X-ray absorption spectroscopy study

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Table ronde sur les aspects "utilisateurs" : intérêts et retours d’expériences de chercheurs et enseignants-chercheurs du site

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Ni isotopic fractionation due to interaction with small organic acids and purified humic acids

International audienceThe biogeochemical cycle of metals in the environment can be considerably influenced by the role of vegetation. Several Ni accumulating plants are able to enrich Ni composition up to 5% in dry leaf matter [1]. Some recent studies have reported a significant Ni isotopic fractionation in hyperaccumulating plants between roots and storage organs, until the maximum absorption is reached (-0.18‰) [2], therefore, the use of stable isotopes can allow to understand the dynamics of trace elements and tracing Ni fate in the soil-plant system and in the environment.Several organic acids are present in plant roots, such as citric or malic, that are involved in soil-plant processes, including metal mobilization and uptake, and plant detoxification [3]. However, up to now, no specific investigations were performed about the potential Ni isotopic fractionation due to complexation with organic acids present in plant roots, or due to adsorption to organic matter in soils. To investigate the potential mechanisms responsible for Ni isotopic fractionation in the soil-plant system, the complexation by two different organic acids, citric and oxalic, with increasing complexation constants, was studied at pH=5 and pH=7. In addition, Ni adsorption onto purified humic acid (PHA) [4] from peats collected in São Paulo State, Brazil, an analog of organic matter, was investigated at pH=7 with PHA concentration of 40mg L-1 and 80mg L-1. According to Visual-MinteQ modeling, in these conditions, free Ni2+ in solution represents 63% and 40% of the total Ni, respectively, which is coherent with the measurements. The Donnan Membrane device (DMT) was used to separate complexed Ni from free Ni2+ after reaching equilibrium. The obtained results revealed that Ni complexation with citric and oxalic acids did not induce any significant isotopic fractionation, whatever the pH considered. On the contrary, in both PHA experiments, Ni complexed with PHA is slightly enriched in heavier isotopes compared to free Ni2+, inducing a Δ60 Nicomplexed-free ranging from 0.1 to 0.2 ‰. [1] Baker A.J.M. (2000), Phytoremediation of contaminated soil and water, Lewis Publishers, 85-107. [2] Estrade et al. (2015), EPSL, 423, 24-35. [3] Jones D.L. (1998), Plant and Soil, 205, 25-44. [4] Swift, R.S. (1996) Methods of soil analysis. D.L. Sparks et al. (eds), 35, 1018-1020

Impact of past steel-making activities on lanthanides and Y (REY) fractionation and potential mobility in riverbank sediments

International audienceNew technologies significantly disturb the natural riverine cycle of some Rare Earth Elements and Yttrium (REY). Whereas large evidence exists on the anthropogenic impact on REY dissolved and colloidal loads in rivers, there is still a knowledge gap on how suspended load could be impacted. As the river suspended matter is a key driver for the quantity of trace metal transport and mobility toward the other river compartments, it is of importance to evaluate how anthropogenic activity could affect its REY composition. Here, we report how past steel-making processes impacted the REY composition and potential mobility in riverbank sediments collected from a French River basin heavily disturbed by this industrial activity. In comparison to sediment originated from the local soil erosion, the industrial waste released in the river presented very unusual REY patterns. We observed specific LaN/GdN, LaN/LuN and Y/Ho ratios that indicate a strong heritage in the industrial waste of the iron ore used to produce steel. REY enrichments were also highlighted and can be classified as follow: Eu>Yb>Sm>Ce>Tm. The different enrichments might illustrate various fractionation processes that occurred separately on the different lanthanides inside the blast furnace according to temperature, pressure and oxygen fugacity changes. Sequential extractions performed on natural and industrial waste samples showed that REY enrichments in the industrial waste are included in one main fraction, which is strongly labile, whereas REYs contained in the sediment originating from the soil erosion are related to different mineralogical fractions having lower and more specific lability. Finally, REY composition showed that the sediment deposited on the riverbank is composed of two types of materials, which progressively evolved, after the ending of the industrial activity in this region, from a pure industrial waste in depth to a pure natural suspended sediment originated from local soil erosion at the surfac

Identifying the Anthropogenic Sources in River Sediments with Zn and Pb Isotope Signatures: A Case Study in Northeast France

International audienceThe Orne River is a tributary of Moselle River in the northeastern part of France, which has been strongly modified by steel-making facilities and associated urbanization. As a heritage of the past steel activities, the river displays several dams that were built for blast furnace cooling purpose. Those dams enhance the deposition of highly contaminated material in the riverbed and despite a river dredging in late 1980’s, several spots of steel-making waste are still present in the vicinity of the dams. Those sediment deposits, as deep as 1.3 m in some places, contain high content of Fe, Zn and Pb. In order to follow the eventual re-suspension of those sediments in the water column, a multi-marker study was performed, including the determination of Zn and Pb isotopic fingerprints. This study aims to (i) determine the Zn and Pb isotopic signatures of two dam front river sediment cores and suspended particles (SPM) along the river; (ii) establish the Zn and Pb isotope signatures of local anthropogenic and natural sources; (iii) assess the anthropogenic input sources with the isotope signatures as indicators.The δ66ZnIRMM-3702 values of the river sediments and SPM were shown to range from -0.12 to 1.36 ‰ and -0.12 to -0.05 ‰, respectively, while the 206Pb/204Pb ratio ranges between 18.326 and 18.690 for river sediments and from 18.370 to 18.609 for SPM. Within both cores, the isotope signatures suggest different source origins, including mining tailings, slag and atmospheric deposition. In the bottom 50 cm of the down stream core, the distinctive isotope signatures highlight one more source coming from past activities. Comparing the SPM signatures to the surface sediments show the potential of using isotopic tools to follow sediment re-suspension in the river

Zinc behavior in river materials through the double spectroscopic and isotopic tools

International audienceActually, the fate of the metal rich sediments and the dynamics of their re-mobilization need to be better understood for a better management of water resources. Widely used in industry and urban areas, Zn is ubiquitous in continental waterbodies, with contents ranging from few dozens to several thousand ppm in sediments and suspended particulate matter (SPM). In a double context of metal contamination and global climate change, we aim to identify the resuspended contaminated sediments via several markers, including Zn speciation and Zn isotopic fingerprinting.Sediments and SPM were collected in different rivers of the Moselle watershed, France, including rivers previously impacted by steelmaking activities (the Orne and Fensch Rivers). River SPM were collected during low an high water discharges and with intensive sampling during several flood events. Besides chemical composition and mineralogy, Zn speciation in river materials was unraveled using TEM and X-ray absorption spectroscopy at the Zn K-edge. Contaminated sediments were characterized by the predominance of Zn-sulfides, while SPM and recent sediments display Zn mainly bound to clay minerals and to a lesser extent to iron oxyhydroxides and carbonates. Concerning isotopic signature, δ66ZnIRMM-3702 values ranged from -0.12 to 1.36 ‰ and from -0.12 to -0.05 ‰ for sediments and SPM, respectively. The combination of spectroscopic and isotopic tools provided insights about sources and resuspension processes during flood events

Sediment transport modelling in riverine environments: on the importance of grain-size distribution, sediment density, and suspended sediment concentrations at the upstream boundary

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