Emmanuelle Montarges-Pelletier

Identification of nickel chelators in three hyperaccumulating plants: An X-ray spectroscopic study

We have investigated the accumulation of nickel in a hyperaccumulating plant from the Brassicacae family Leptoplax emarginata (Boiss.) O.E. Schulz. Two supplementary hyperaccumulating plants, which have been the subject of a high number of publications, Alyssum murale Waldst. & Kit and Thlaspi caerulescens J.&C. Presl, and a nonaccumulating species Aurinia saxatilis were also studied for reference. The plants were grown during 4 months in specific rhizoboxes with Ni-bearing minerals as a source of nickel. Nickel speciation was analyzed through X-ray absorption spectroscopy at Ni K-edge (X-ray absorption near edge spectroscopy and extended X-ray absorption fine structure spectroscopy) in the different parts of the plants (leaves, stems and roots) and compared with aqueous solutions containing different organo-Ni(II) complexes. Carboxylic acids (citrate, malate) appeared as the main ligands responsible of nickel transfer within those plants. Citrate was found as the predominant ligand for Ni in stems of Leptoplax and Alyssum, whereas in leaves of the three plants, malate appeared as the chelating organic acid of accumulated metal. Histidine could not be detected either in leaves, stems nor roots of any studied plant sample.

Activated sludge exopolymers: separation and identification using size exclusion chromatography and infrared micro-spectroscopy.

Extracellular polymeric substances were extracted from activated sludge using a resin exchange method and analyzed. The separation and identification of EPS were carried out by size exclusion chromatography and Fourier transform infrared micro-spectroscopy. Chromatograms of extracted EPS exhibited seven peaks. Proteins varying in molecular weights from 670 to 45 kDa were present in all the peaks. Polysaccharides corresponding to molecular weights of approximately 1 and approximately 0.5 kDa were present in only three peaks. Strong association of polysaccharides and proteins was observed. Infrared results revealed the presence of one type of polysaccharide and two types of proteins (A and B). Proteins differed mainly in the length of their associated alkyl chains and in the ratio of ester/acidic functionalities.

Sources, nature, and fate of heavy metal-bearing particles in the sewer system.

A preliminary insight into metal cycling within the urban sewer was obtained by determining both the heavy metal concentrations (Cu, Zn, Pb, Cd, Ni, Cr) in sewage and sediments, and the nature of metal-bearing particles using TEM-EDX, SEM-EDX and XRD. Particles collected from tap water, sump-pit deposits, and washbasin siphons, were also examined to trace back the origin of some mineral species. The results show that the total levels in Cu, Pb, Zn, Ni, and Cr in sewage are similar to that reported in the literature, thus suggesting that a time-averaged heavy metal fingerprint of domestic sewage can be defined for most developed cities at the urban catchment scale. Household activities represent the main source of Zn and Pb, the water supply system is a significant source of Cu, and in our case, groundwater infiltration in the sewer system provides a supplementary source of Ni and Cd. Concentrations in heavy metals were much higher in sewer sediments than in sewage suspended solids, the enrichment being due to the preferential settling of metal-bearing particles of high density and/or the precipitation of neoformed mineral phases. TEM and SEM-EDX analyses indicated that suspended solids, biofilms, and sewer sediments contained similar heavy metal-bearing particles including alloys and metal fragments, oxidized metals and sulfides. Copper fragments, metal carbonates (Cu, Zn, Pb), and oxidized soldering materials are released from the erosion of domestic plumbing, whereas the precipitation of sulfides and the sulfurization of metal phases occur primarily within the household connections to the sewer trunk. Close examination of sulfide phases also revealed in most cases a complex growth history recorded in the texture of particles, which likely reflects changes in physicochemical conditions associated with successive resuspension and settling of particles within the sewer system.

Lanthanide ecotoxicity: First attempt to measure environmental risk for aquatic organisms

The geochemical cycles of lanthanides are being disrupted by increasing global production and human use, but their ecotoxicity is not fully characterized. In this study, the sensitivity of Aliivibrio fischeri and Pseudokirchneriella subcapitata to lanthanides increased with atomic number, while Daphnia magna, Heterocypris incongruens, Brachionus calyciflorus and Hydra attenuata were equally sensitive to the tested elements. In some cases, a marked decrease in exposure concentrations was observed over test duration and duly considered in calculating effect concentrations and predicted no effect concentrations (PNEC) for hazard and risk assessment. Comparison of PNEC with measured environmental concentrations indicate that, for the present, environmental risks deriving from lanthanides should be limited to some hotspots (e.g., downstream of wastewater treatment plants). However, considering the increasing environmental concentrations of lanthanides, the associated risks could become higher in the future. Ecotoxicological and risk assessment studies, along with monitoring, are required for properly managing these emerging contaminants.

Interaction of Fe(III) and Al(III) during hydroxylation by forced hydrolysis: The nature of Al–Fe oxyhydroxy co-precipitates

Al-Fe oxyhydroxy co-precipitates were synthesised by forced hydrolysis of Fe(NO3)3·9H2O and Al(NO3)3·9H2O solutions. Solids containing 0, 1, 10, 25, 50, 75, 90 mol% Al were characterised for composition, texture, mineral structure and local atomic environment. Cation substitution in the hydrous oxides was not observed. The solids consisted of hydrous ferric oxide (HFO) nuclei surrounded by Al-hydroxide. Below 50 mol% Al, unit particle size, high specific surface area and microporosity of HFO were preserved. Al-K-edge XANES showed ordered arrangements of Al-octahedra suggesting that some Al bound specifically to HFO surface sites. Above 50 mol%, Al precipitated in multiple layers around the nuclei and also as individual entities. The HFO nuclei exhibited the general characteristics of a 2-line ferrihydrite. However, as Al increased, the structure was slightly modified. While the symmetry of the FeO6 octahedra improved, the number of Fe-Fe linkages decreased, suggesting less polymerisation. An organisation of the Fe-octahedra, faintly resembling akaganeite, was expressed in Raman spectra. These changes in HFO structure were attributed to hindrance in the progressive olation/oxolation of the primary Fe-hydroxypolymers, caused by Al bound to the surface of nuclei. The presence of nitrate is suspected to have favoured the structural changes.

Characterization of suspended particulate matter in the Moselle River (Lorraine, France): evolution along the course of the river and in different hydrologic regimes

PurposeSuspended particulate matter (SPM) plays an important role in the transport and fate of contaminants in the environment. To better understand the relationships between contaminants and SPM, SPM properties, and their variations with flow regime, river size, land use, and season should be considered.Materials and methodsThe grain size distribution, elemental composition, and mineralogy of SPM from different stations along the Moselle River (Lorraine, France) were investigated at the particle scale during different flow regimes. The resulting data were compared with the elemental composition of the dissolved compartment to understand the role of particles in element transport.Results and discussionThe grain size distribution, elemental composition, and mineralogy of SPM along the Moselle River and during different flow regimes showed only slight variations, except for the Fensch and Orne tributaries, two rivers that were impacted by inherited steel-making industrialization and different land use. In the Moselle River, SPM mainly consisted of clay minerals, while in Fensch and Orne Rivers, SPM mainly consisted of multiple types of anthropogenic particles. The diffuse urbanization gradient was hardly recognized based on the Trace Metal Element (TMEs) content in the river SPM, while the rivers impacted by the steel industries had greater TME contents. Finally, the TME content in the Moselle SPM was more strongly influenced by water flow than by the position of sampling on the linear reach of the Moselle River. The partitioning of TMEs in the particles and water at the main Moselle station (Frouard) revealed that SPM predominantly contributed to TMEs transport.ConclusionsThis study confirmed that catchment geology greatly contributed to the SPM composition in the mean-sized rivers. In addition, the high anthropogenic pressure could be deciphered for small tributaries. Furthermore, this study allowed us to observe the high contribution of particles to TMEs and Rare Earth Element (REEs) transportation.

Evolution of the source apportionment of the lipidic fraction from sediments along the Fensch River, France: A multimolecular approach

The Fensch River (FR) is one of the most contaminated rivers in France due to the population density and the concentration of industrial activities in this small watershed area. From upstream to downstream, the organic matter extracted from sediments has been analyzed by gas chromatography-mass spectrometry and molecules have been quantified and classified into natural, petrogenic, pyrogenic and sewage water (SW) markers. Upstream the river, anthropogenic molecules are already predominant and represent 87.1% of the molecules quantified. This proportion increases from upstream to downstream and rises to 96.8% at the confluence of the FR with the Moselle River. In the upper part of the FR the contamination is mainly due to human waste (coprostanol: 36.44 microg/g; 42.1% of anthropogenic markers). In the lower part, the contribution of SW markers decreases from 42.1 to 2.4% and the proportion of pyrogenic molecules increases from 29.6 to 59.6%. The major sources of pyrogenic organic matter have been determined by calculation of specific ratios on polycyclic aromatic hydrocarbons and by comparison with reported data. Coal tar, road runoff and atmospheric depositions of urban particles seem to be the major pyrogenic sources. Along the river, the proportion of petrogenic molecules remains constant and those molecules seem to be mainly inherited from road runoff, in the upper part of the FR. Industrial lubricants that occur in steel plant sludge are an additional source in the lower part of the river.

Microscale investigations of the fate of heavy metals associated to iron-bearing particles in a highly polluted stream

As it flows through a dense steelmaking area, the Fensch River does transport iron-rich particles and colloids, displaying high contents in metallic contaminants (Zn, Cr, Pb, Cu, Ni, and As). Chemical analysis using inductively coupled plasma mass spectrometry (ICP-MS) was carried out on three compartments—waters, suspended materials, and sediments—along the river linear. The variations of metallic trace element concentrations along the river were shown to be partially related to external inputs (industrial and domestic wastewaters and urban surfaces leaching). However, some discrepancies of element partitioning were evidenced. Pb, Cu, and Mn tend to concentrate in suspended particulate and in dissolved fraction, while Cr and As follow the trend of Fe and concentrate within sediments of the most downstream station, just before the junction with Moselle waters. Zn appears strongly associated to iron-rich particles, resulting in a decrease of its concentration in waters for the last station. Along the Fensch linear, the variation of metal partitioning between water and particulate phases is accompanied with strong modifications of the nature and mineralogy of iron-rich particles, as evidenced by microanalyses using electron and X-ray beams. The combination of bulk analyses using ICP-MS and microanalyses applied to the three compartments allowed us to propose a three-step process “settling–weathering–resuspension” to explain Zn partitioning.

Fate of nickel and calcium in seedlings of the hyperaccumulator Berkheya coddii during germination

Little is known about Ni storage in seeds of hyperaccumulating plants and its possible role in the first stages of plant development. The aim of this study was to determine Ni distribution in seeds and seedlings during germination and to test its role during germination with and without an external Ni supply. Field-harvested seeds from the South African Ni-hyperaccumulator Berkheya coddii Roessler were germinated either in Ni-free deionised water or in ultramafic soil. Sections of seeds and seedlings were analyzed using micro-proton induced X-ray emission (micro-PIXE) in order to localise Ni and other elements. Results show that high amounts of Ni were stored within the seeds. In germinating seeds, Ni was located in different parts: the lower epidermis, margins of cotyledons, and the pericarp in the micropylar area. The Ni and Ca were not mobilised during germination sensu stricto. Emergence of the first leaf seemed to trigger the translocation of Ni and Ca within the seedling. Besides, no effect of Ni supply from soil on its redistribution could be established for the germination stage.

Iron mineralogy as a fingerprint of former steelmaking activities in river sediments

Submerged sediment cores were collected upstream of a dam in the Orne River, northeastern France. This dam was built in the context of steelmaking to constitute a water reservoir for blast furnace cooling and wet cleaning of furnace smokes. The dam also enhanced sediment deposition in the upstream zone. This study was performed to unravel the contamination status of sediments and to evidence possible contribution sources. The sediment layers were analyzed for water content, grain size, chemical composition, crystalline phases at a bulk scale and poorly crystalline and amorphous phases at a sub-micrometer scale. Visual aspect, texture, color, and chemical and mineralogical analyses showed that the settled sediments were mainly composed of fine black matter, certainly comprising steelmaking by-products. Those materials were highly enriched with Fe, Zn, Pb and other trace metals, except for a relatively thin layer of surficial sediments that had settled more recently. Bulk mineralogy revealed crystalline iron minerals, such as magnetite, goethite, wuestite and pyrite, in the deep layers of the sediment cores. Furthermore, microscopic investigations evidenced the presence of ferrospheres, goethite nanoparticles and newly formed Fe-aluminosilicates; all originating from the former steelmaking facilities. The variation of iron mineralogy, combined with specific chemical profiles and other sediment features, demonstrate the different contributions that constitute the sediment deposit. Furthermore, chemical and mineralogical features of goethite and Fe-aluminosilicates could be used as a fingerprint for such contaminated sediments.