Identification of particulate heavy metal pollution sources in urban river sediment using scanning electron microscopy coupled with energy dispersive spectrometer (SEM-EDS)

8 p.International audienceScanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) was used to develop a protocol for the identification of trace element carriers in the Seine River. Various Pb, Ni, Zn, V, Cr, and Cu bearing phases were identified on the sediment of the Seine River. Lead and nickel were found to be preferentially bound with iron sulfide particles. This phase is known to be a significant trace metal carrier in a reducing environment. Association of vanadium and calcium was identified which would be a product of road surface runoff. Zinc was also found associated with barite, possibly indicating an urban-related contamination source. Microscopic particle analysis shows to be a powerful tool in the characterization of their different sources and their eventual mobility in the environment

Medulloblastomas with ELP1 pathogenic variants: A weakly penetrant syndrome with a restricted spectrum in a limited age window

Background: ELP1 pathogenic variants (PV) have been recently identified as the most frequent variants predisposing to Sonic Hedgehog (SHH) medulloblastomas (MB); however, guidelines are still lacking for genetic counseling in this new syndrome. Methods: We retrospectively reviewed clinical and genetic data of a French series of 29 ELP1-mutated MB. Results: All patients developed SHH-MB, with a biallelic inactivation of PTCH1 found in 24 tumors. Other recurrent alterations encompassed the TP53 pathway and activation of MYCN/MYCL signaling. The median age at diagnosis was 7.3 years (range: 3-14). ELP1-mutated MB behave as sporadic cases, with similar distribution within clinical and molecular risk groups and similar outcomes (5 y - OS=86%); no unusual side effect of treatments was noticed. Remarkably, a germline ELP1 PV was identified in all patients with available constitutional DNA (n=26); moreover, all tested familial trio (n=11) revealed that the PVs were inherited. Two of the 26 index cases from the French series had a family history of MB; pedigrees from these patients and from 1 additional Dutch family suggested a weak penetrance. Apart from MB, no cancer was associated with ELP1 PVs; second tumors reported in 4 patients occurred within the irradiation fields, in the usual time-lapse for expected radiotherapy-induced neoplasms. Conclusions: The low penetrance, the "at risk' age window limited to childhood and the narrow tumor spectrum, question the actual benefit of genetic screening in these patients and their family. Our results suggest restricting ELP1 germline sequencing to patients with SHH-MB, depending on the parents"request

Sédiments, racontez-moi l’histoire de la Seine…

National audienceComment reconstituer l’histoire de la contamination d’un fleuve comme la Seine ? Les sédiments qui se sont déposés dans la plaine alluviale à chaque crue du fleuve ont gardé la mémoire des contaminants portés par les particules. Analyser et dater ces dépôts permet de comprendre comment nos activités, mais aussi nos législations, ont impacté le fleuve

Phytoextraction of Thorium from Soil and Water Media

International audienceRemediation of ecosystems that have been exposed to radionuclides is of great importance for many countries. At present the remediation efforts using existing technologies are rather expensive. Phytoremediation can serve as a perspective method for rehabilitation of the radioactive contaminated soils and wastes. Among other radio-nuclides, limited information is available on screening and selection of plants for thorium uptake. In our work short-term pot experiments in a greenhouse have been performed to study the phytoextraction of thorium by wheat seedlings grown in soil and different water media artificially contaminated with thorium. Addition of a small amount of thorium to the media resulted in a significant increase of thorium concentration both in roots and leaves of the wheat seedlings. The uptake of Th by roots depended of the media where the plants grew: it was more significant in water-grown plants. The rate of Th translocation from roots to leaves was approximately the same regardless of the growth medium. The bioaccumulation of Th in the wheat resulted inthe removal of Th from the soil and water. During the short-term vegetation test concentration of Th in all the media decreased: in water — 2—5 times, in soil — 1.7 times. Th accumulation in the wheat seedlings affected concentrations and relationships between other elements in the plants. More significant changes were found in the wheat grown in doubly distilled water and in nutrient solution.The most affected part of the plants was the root system

Scandium bioaccumulation and its effect on uptake of macro- and trace elements during initial phases of plant growth

International audienceUptake of scandium (Sc) by wheat seedlings was studied during 6-d germination of wheat seeds in Sc supplemented medium and during 1-week growth of wheat seedlings germinated under normal conditions in soil amended with Sc. The most significant increase in Sc content in the seedlings was observed during germination of seeds in Sc supplemented medium. Transfer of the seedlings to normal soil resulted in a decrease of Sc level in upper plant parts, but Sc concentration in roots remained rather high. Scandium bioaccumulation caused variations in concentrations of Na, K, Ca, and Zn 0n different parts of the seedlings. The least variations were observed in leaves

Biomonitoring of Pt and Pd with Mosses

International audiencePlatinum (Pt), palladium (Pd), and rhodium (Rh) belong to the rarest element group in the lithosphere and biosphere. Their background values lie in the range of 0.1 ng$^.$g$^{-1}$ to 1 ng$^.$g$^{-1}$ (Wedepohl, 1995). However, since the introduction of Pt-containing auto catalyst converters during the 1970’s in the USA and later in Japan and Europe, their concentrations in the environment, especially in the roadside environment, have increased rapidly (Lustig, 1997). Retrospective studies on airborne dust samples (Zereini et al. 1997) and ancient ice (Barbante et al. 2001) have facilitated the assessment of the environmental dispersion of these platinum group elements (PGE). Increases in the concentration of PGEs in the environment have been documented in numerous countries and matrixes (Ravindra et al.2004).As a result, there is now a growing concern on the ecological and human risk of increasing concentrations of PGE in the environment. There have been several passive biomonitoring studies to investigate the bioaccumulation of platinum in animals and plants. An experiment of active biomonitoring of platinum has been performed using grass cultures (Dietl et al. 2000). Palladium bioaccumulation has been less documented as stated by Lustigand Schramel (2000). Moss analyses have been utilized successfully in the environmental biomonitoring of heavy metal atmospheric deposition studies during the past 30 years (e.g. Steinnes, 1995). Both active (using transplanted moss)and passive (using endogenous) monitoring methods have been developed and applied to the monitoring of inorganic and organic pollutants. The following sections examine the feasibility of using mosses to assess Pt and Pd pollution in the region of Paris, France, and compare the obtained data with those published on PGE biomonitoring using grass

Characteristics of a spark discharge as an adjustable acoustic source for scale model measurements

International audienceThe simulation of acoustic phenomena using urban street scale models requires the use of a small and powerfull sound sources with a wide frequency bandwidth and omnidirectional radiation. Among different source types able to provide these characteristics, spark discharge in air is an interesting solution. The principle is based on the generation of an electric discharge by applying a high voltage between two electrodes. First the gas becomes electrically conducting, the electric current heats up the gas, causing the formation of an impulsive sound signal. These sources have been also widely used for shock wave propagation, like sonic boom, for which propagation is non linear. However, the behaviour of spark discharges and their acoustic radiation depend greatly on the electrodes gap. As very little investigation has been done of this dependance, this work provides a detailled characterisation of a spark discharge in function of the electrodes gap. Electrical characteristics, repeatability, acoustic characteristics and the limits between linear and non linear propagation domains are studied in function of various electrodes gaps. This experimental study is meant to be a useful resource for experimenters to design a spark discharge adapted to their specific applications

Trace element behavior and partition versus urbanization gradient in an urban river (Orge River, France)

International audienceIn order to assess the spatial (i.e., multi-site) and temporal (i.e., seasonal time scale) dynamics of trace elements (TE) along the Orge River (France), the geochemistry of both suspended particulate matter (SPM) and dissolved phase (<0.45 μm) was investigated during a whole hydrological year. TE concentrations in the different compartments were discriminated using principal component analysis (PCA), which allows to highlight both correlated or opposite behaviors between major, minor and trace elements. The Orge River watershed presents a highly contrasted land use pattern, with, upstream, mainly forests and agricultural lands and, downstream, a highly dense urban area (up to 8000 inh. km−2), in the suburbs of Paris Megacity. TE concentrations, particularly urban ones (Pb, Zn, Cu, and Sb) drastically increased in both dissolved and particulate compartment due to urbanization in the Orge River catchment. This enrichment was found to be associated with a spatial increase in the dissolved contribution of TE (20–30% for Zn), which may lead to their increasing bioavailability and toxicity. Urban runoff and sewage releases were found to have a strong influence on the river geochemistry and PCA allows identifying the limits of urbanization influence. According to statistical analyses, the dissolved data are more representative of urban processes, i.e., spatial trends, while the particulate compartment data mainly described seasonal variability, i.e., the temporal trends. Finally, this study highlights the necessity of following both dissolved and particulate concentrations of TE to characterize accurately the contamination trends and their possible implications on urban river systems. As the present European guidelines are only fixed for dissolved species, we show here that the SPM contamination must also be monitored to better understand the geochemical processes involved and the degree of contamination of the river

Urbanization impact on metals mobility in riverine suspended sediment: Role of metal oxides

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